Power conversion device

Abstract

This power conversion device (100) comprises: a power conversion unit (1) that has a plurality of switching elements and converts DC power to AC power and supplies the AC power to a load in accordance with the switching state amounts of the switching elements; a voltage output calculation unit (11) that, on the basis of the switching state amounts, calculates a voltage output value of the AC supplied from the power conversion unit (1); an integral value calculation unit (12) that integrates each of an AC voltage command value and the AC voltage output value calculated by the voltage output calculation unit (11), and derives a voltage command integral value and a voltage output integral value; and a switching determination unit (13) that calculates and outputs the switching state amount of the power conversion unit (1) when or before the voltage output integral value reaches an allowable range boundary value obtained by setting the setting value of the allowable range to the voltage command integral value, on the basis of the voltage command integral value, the voltage output integral value, and the setting value of the allowable range.

Description

Power Conversion Device

[0001] The present disclosure relates to a power conversion device.

[0002] Power conversion devices using pulse width modulation (hereinafter also referred to as PWM, where PWM is an abbreviation for Pulse Width Modulation) generally use a triangular wave carrier comparison PWM method, which determines the switching state of a switching element by comparing a triangular wave carrier with a voltage command value. In this method, the output voltage is a rectangular pulse that simulates a sine wave, so harmonics are generated in addition to the fundamental sine wave, causing pulsation (also called ripple) in the current flowing through the rotating electrical machine or the torque generated.

[0003] To solve this problem, a method (direct switching control method) has been proposed that directly determines the switching states of multiple switching elements in a power conversion unit. One such direct switching control method is known as direct torque control. Direct torque control sets tolerances for torque and magnetic flux command values ​​of a rotating electric machine and switches the switching state when these values ​​exceed the tolerances. This method determines the switching state to suppress magnetic flux and torque pulsation, thereby reducing the current flowing through the rotating electric machine or the torque pulsation generated compared to the PWM method. Furthermore, setting a large tolerance reduces the number of transitions between the switching states of the multiple switching elements in the power conversion unit, thereby reducing switching losses that occur during transitions between the switching states.

[0004] Model predictive control is also known as a direct switching control method that is an improvement over the direct torque control. Model predictive control calculates the current flowing through a rotating electric machine, the torque generated, or the magnetic flux resulting from all possible switching states of the power conversion unit based on the state equations of the rotating electric machine, and determines the switching state based on these calculated values. By controlling the switching state based on predicted values ​​of the driving state of the rotating electric machine in this way, compared to the PWM method and direct torque control, it is possible to improve the time constants of the current, torque, and magnetic flux in transient states, reduce current or torque pulsation in steady states, reduce the number of switching state transitions, and reduce switching losses.

[0005] However, in order to calculate the values ​​of the rotating electric machine for all candidate switching states, it is necessary to calculate the state equation of the rotating electric machine, which results in a very large amount of calculation.Furthermore, there are many rotating electric machine parameters used, which has the disadvantage of being susceptible to parameter errors.

[0006] For example, in the prior art described in Patent Document 1 below, a direct switching control method based on an integrated voltage value is considered. This control method integrates the error between a voltage command value vector and a voltage output vector, and when this integrated value exceeds a boundary circle set for the voltage command value vector, outputs a voltage output vector in a direction closest to the center of the boundary circle. Therefore, since the switching state is determined so that the voltage integral error between the voltage command vector and the voltage output vector remains on the boundary circle for a long time, it is possible to control the output voltage to a sinusoidal wave while minimizing the number of switching transitions of the switching elements in the power conversion unit.

[0007] Furthermore, in the prior art described in Patent Document 2 below, a direct switching control method based on the integrated value of the voltage value, similar to Patent Document 1, is being considered. The difference from Patent Document 1 is that this method focuses on the integrated value of the voltage value in each phase and switches the switching state quantity when the integrated voltage value of each phase exceeds a tolerance value, reducing the calculation load by determining whether each phase exceeds the tolerance value. Furthermore, since the zero voltage vector can be actively utilized, this method makes it easy to reduce the number of transitions in the switching state.

[0008] Furthermore, in the prior art described in Patent Document 3 listed below, a direct switching control method is considered using direct torque control based on model predictive control. This control method predicts and calculates the torque and stator flux of a rotating electric machine in a predetermined interval based on a state equation of the rotating electric machine, and searches for a switching pattern (combination of multiple switching states) that minimizes the number of switching transitions of each phase switching element while ensuring that the torque and stator flux satisfy desired allowable values ​​in the predicted interval.

[0009] This minimizes the number of switching transitions under the conditions of the desired torque and stator flux ripple in the steady state. Also, in a transient state such as a torque-related step command, the switching state that best follows the torque command is selected from the predicted values ​​of the torque and stator flux of the rotating electric machine, thereby achieving a fast torque response time.

[0010] Japanese Patent Application Laid-Open No. 11-89244 International Publication No. 2022 / 107838 Japanese Patent Application Laid-Open No. 2011-152038

[0011] The direct switching control method based on the integrated value of the voltage value described in Patent Document 1 switches the switching state to reduce the number of switching transitions when the integrated value of the error between the voltage command vector and the voltage output vector exceeds a boundary circle set for the voltage command value vector. However, because the voltage output vector closest to the center of the boundary circle is always selected, it is not possible to actively select a zero voltage vector, and there is a limit to the effect of reducing the number of switching state transitions.

[0012] In addition, the direct switching control method based on the integrated voltage values ​​described in Patent Document 2 is configured to actively utilize the zero voltage vector, making it easy to reduce the number of switching state transitions, and since it determines whether the voltage integral value of each phase exceeds the tolerance, the calculation load is also small. However, because the switching state is changed only when the voltage integral value exceeds the tolerance, it is not possible to further reduce the number of switching state transitions by devising a timing for switching the switching state. In particular, when tolerances are set for each phase for the three-phase voltage integral values, a hexagonal tolerance range is drawn, and if the corners of this hexagonal tolerance range are reached, the number of switching state transitions may suddenly increase.

[0013] Furthermore, compared to Patent Documents 1 and 2, direct torque control based on model predictive control as described in Patent Document 3 determines the switching state by calculating predicted values ​​of the torque and stator magnetic flux of the rotating electric machine to be controlled, and therefore can reduce switching loss in the steady state while maintaining a fast torque response time in the transient state. However, direct torque control based on model predictive control uses many parameters of the rotating electric machine because it calculates the switching state based on the state equation of the rotating electric machine. Furthermore, direct torque control based on model predictive control uses the speed of the rotating electric machine and the value of the current flowing through the rotating electric machine, and therefore, if an error occurs in each parameter, the effect of reducing switching loss will be degraded.

[0014] The present disclosure discloses a technique for solving the above-described problems, and aims to provide a power conversion device that reduces switching loss in a power conversion unit.

[0015] The power conversion device of the present disclosure includes: a power conversion unit having a plurality of switching elements, which converts DC power into AC power according to a switching state quantity of each switching element and supplies the AC power to a load; a voltage output calculation unit which calculates an AC voltage output value supplied from the power conversion unit based on the switching state quantity; an integral value calculation unit which integrates an AC voltage command value to obtain a voltage command integral value, and which integrates the AC voltage output value calculated by the voltage output calculation unit to obtain a voltage output integral value; and a switching determination unit which calculates and outputs a switching state quantity of the power conversion unit based on the voltage command integral value, the voltage output integral value, and a set value of an allowable range, when the voltage output integral value reaches an allowable boundary of an allowable range for which the set value of the allowable range is set for the voltage command integral value, or before the voltage output integral value reaches the allowable boundary of the allowable range within the allowable range.

[0016] According to the power conversion device of the present disclosure, it is possible to provide a power conversion device that reduces the switching loss of the power conversion unit by switching the switching state quantity when or before the voltage output integral value reaches the tolerance boundary, which is the limit of the tolerance range set for the voltage command integral value, based on the voltage output integral value obtained by integrating the voltage values ​​of each phase of a multi-phase AC obtained from the switching state quantity of the power conversion unit, the voltage command integral value obtained by integrating the voltage command value, and the tolerance range for each phase.

[0017] FIG. 1 is a block diagram showing a configuration of a power conversion device according to a first embodiment. FIG. 2 is a hardware configuration diagram of a power conversion device according to a first embodiment. FIG. 3 is a diagram showing all candidate switching states of a power conversion unit according to a first embodiment. FIG. 4 is a diagram showing a relationship between a switching state quantity and a multiphase voltage output value of a power conversion unit according to a first embodiment. FIG. 5 is a diagram showing a relationship between a switching state quantity and a multiphase voltage output value (with a neutral point set to zero) of a power conversion unit according to a first embodiment. FIG. 6 is a diagram for explaining a configuration diagram of a switching calculation unit for calculating a next switching state quantity of a power conversion unit according to a first embodiment. FIG. 7 is a diagram for explaining the maximum number of candidates for a switching state quantity of a power conversion unit according to a first embodiment. FIG. 8 is a diagram for explaining a method for calculating a next switching state quantity of a power conversion unit according to a first embodiment by a switching calculation unit. FIG. 9 is a flowchart (first half) showing an example of an operation of a power conversion device according to a first embodiment. FIG. 10 is a flowchart (second half) showing an example of an operation of a power conversion device according to a first embodiment. FIG. 11 is a diagram for explaining an example of an effect of a power conversion device according to a first embodiment. FIG. 12 is a diagram for explaining another example of an effect of a power conversion device according to a first embodiment. FIG. 13 is a block diagram showing a configuration of a power conversion device according to a second embodiment. FIG. 14 is a diagram for explaining a configuration diagram of a switching calculation unit for calculating a next switching state quantity of a power conversion unit according to a second embodiment. FIG. 1 is a diagram for explaining a method for calculating a next switching state quantity of a power conversion unit according to embodiment 2 by a switching calculation unit. FIG. 2 is a diagram for explaining a flowchart (first half) showing an operation example of a power conversion device according to embodiment 2. FIG. 3 is a diagram for explaining a flowchart (second half) showing an operation example of a power conversion device according to embodiment 2. FIG. 4 is a block diagram for explaining machine learning based on a trained model and teacher data according to embodiment 3. FIG. 5 is a diagram for explaining a hardware configuration for generating a trained model according to embodiment 3. FIG. 6 is a diagram for explaining a configuration diagram of a switching calculation unit for calculating a next switching state quantity of a power conversion unit according to embodiment 3. FIG. 7 is a diagram for explaining a flowchart (first half) for generating teacher data according to embodiment 3.1 is a diagram showing a flowchart (later part) for generating teacher data according to a third embodiment. FIG. 2 is a flowchart showing an example of operation of the power conversion device according to the third embodiment. FIG. 3 is a block diagram showing a configuration of a power conversion device according to a fourth embodiment. FIG. 4 is a diagram for explaining a configuration diagram of a switching calculation unit for calculating a combination of a switching state variable and a duration of a power conversion unit according to the fourth embodiment. FIG. 5 is a diagram for explaining a time point at which a switching state variable of a power conversion unit according to the fourth embodiment is switched before reaching a boundary value of an allowable range. FIG. 6 is a diagram for explaining a method for selecting a solution for a duration after switching a switching state variable of a power conversion unit according to the fourth embodiment before reaching a boundary value of an allowable range. FIG. 7 is a diagram for explaining a method for calculating a combination of a switching state variable and a duration of a power conversion unit according to the fourth embodiment by a switching calculation unit. FIG. 8 is a diagram showing a flowchart (first part) showing an example of operation of the power conversion device according to the fourth embodiment. FIG. 9 is a diagram showing a flowchart (later part) showing an example of operation of the power conversion device according to the fourth embodiment. FIG. 10 is a block diagram showing a configuration of a power conversion device according to a fifth embodiment. FIG. 11 is a diagram for explaining a configuration diagram of a switching calculation unit for calculating a combination of a switching state variable and a duration of a power conversion unit according to the fifth embodiment. FIG. 12 is a diagram for explaining a method for calculating a combination of a switching state variable and a duration of a power conversion unit according to the fifth embodiment by a switching calculation unit. FIG. 10 is a diagram showing a flowchart (first half) illustrating an example of operation of a power conversion device according to embodiment 5. FIG. 11 is a diagram showing a flowchart (middle half) illustrating an example of operation of a power conversion device according to embodiment 5. FIG. 12 is a diagram showing a flowchart (last half) illustrating an example of operation of a power conversion device according to embodiment 5. FIG. 13 is a block diagram showing a configuration of a power conversion device according to embodiment 6. FIG. 14 is a diagram for explaining a configuration diagram of a switching calculation unit for calculating a next switching state quantity of a power conversion unit according to embodiment 6. FIG. 15 is a diagram for explaining a method for calculating a combination of a switching state quantity and a duration of a power conversion unit according to embodiment 6 by a switching calculation unit. FIG. 16 is a diagram showing a flowchart (first half) illustrating an example of operation of a power conversion device according to embodiment 6. FIG. 17 is a diagram showing a flowchart (middle half) illustrating an example of operation of a power conversion device according to embodiment 6.FIG. 10 is a diagram showing a flowchart (later part) illustrating an example of operation of a power conversion device according to a sixth embodiment. FIG. 11 is a block diagram showing a configuration of a power conversion device according to a seventh embodiment. FIG. 12 is a diagram explaining a method of calculating current harmonic data from detected current values ​​according to the seventh embodiment. FIG. 13 is a diagram explaining a method of calculating current sub-harmonic data from detected current values ​​according to the seventh embodiment. FIG. 14 is a hardware configuration diagram of a power conversion device according to the seventh embodiment. FIG. 15 is a diagram showing a flowchart (first part) illustrating an example of operation of a power conversion device according to the seventh embodiment. FIG. 16 is a diagram showing a flowchart (middle part) illustrating an example of operation of a power conversion device according to the seventh embodiment. FIG. 17 is a diagram showing a flowchart (later part) illustrating an example of operation of a power conversion device according to the seventh embodiment. FIG. 18 is a block diagram showing a configuration of a power conversion device according to an eighth embodiment. FIG. 19 is a diagram explaining a time integral value of a deviation between a voltage command integral value and a power output integral value according to the eighth embodiment. FIG. 20 is a diagram explaining a method of generating a switching table which is a combination of switching state quantities for one electrical angle cycle according to the eighth embodiment. FIG. 21 is a diagram showing a flowchart showing an example of operation of a power conversion device according to the eighth embodiment.

[0018] First Embodiment The present disclosure relates to a power conversion device that converts DC power into AC power, and in particular to a power conversion device that controls the switching states of multiple switching elements in a power conversion unit that shares power with a rotating electric machine. A power conversion device 100 according to a first embodiment of the present disclosure will be described below with reference to the drawings.

[0019] Fig. 1 is a block diagram showing the configuration of a power conversion device 100 according to a first embodiment. As shown in Fig. 1, the power conversion device 100 includes a power conversion unit 1, which is a main circuit, and a control device 10 that controls the output of the power conversion unit 1, and is connected between a DC power source 2 and a load 3. The power conversion unit 1 converts DC power from the DC power source into AC power and supplies the AC power to the load to drive the load 3. Note that the load 3 may be, for example, a transformer or a reactor, or any of various electric motors such as an induction motor or a synchronous motor.

[0020] The control device 10 includes a voltage output calculation unit 11 that calculates a multiphase voltage output value Vout to be output from the power conversion unit 1 to the load 3 based on switching state variables SWS of the multiple switching elements included in the power conversion unit 1, an integral value calculation unit 12 that calculates a voltage command integral value Pref and a voltage output integral value Pout by integrating a multiphase voltage command value Vref and the multiphase voltage output value Vout, respectively, and a switching determination unit 13 that determines the switching state variables SWS of the multiple switching elements included in the power conversion unit 1 based on the voltage output integral value Pout, the voltage command integral value Pref, and a set value ΔP of an allowable range (here, the allowable range does not necessarily have to be determined from a single value but may be determined from a range having a larger extent. Hereinafter, the allowable range will be referred to as the allowable range to include both of these meanings). In the above, the term "multiphase voltage" refers to a multiphase AC voltage (the same applies hereinafter).

[0021] The switching determination unit 13 is composed of a switching calculation unit 131 and a switching output unit 132. The switching calculation unit 131 calculates a switching state quantity SWS of the power conversion unit 1 as a setting signal SetSW based on a voltage command integral value Pref, a voltage output integral value Pout, and a set value ΔP of the allowable range, and the switching output unit 132 outputs the switching state quantity SWS of the power conversion unit 1 based on the setting signal SetSW calculated by the switching calculation unit 131. A calculation method of the switching state quantity SWS of the power conversion unit 1 in the switching calculation unit 131 will be described later.

[0022] 2 is a hardware configuration diagram for implementing the power conversion device 100. The power conversion unit 1 is configured with a three-phase inverter circuit that converts DC power from a DC power source 2 into three-phase AC power, and drives a load 3. The power conversion unit 1 includes multiple switching elements Q1 to Q6. A diode D is connected in anti-parallel to each of the multiple switching elements Q1 to Q6. A bus bar connects the connection point between the upper arm and lower arm of each phase to the input terminal of each phase of the load. In this case, the u-phase includes switching elements Q1 and Q2, the v-phase includes switching elements Q3 and Q4, and the w-phase includes switching elements Q5 and Q6.

[0023] The control device 10 is composed of a processor 40 and a storage device 41. The storage device 41 includes a volatile storage device (not shown) such as RAM (abbreviation for Random Access Memory) and a non-volatile auxiliary storage device (not shown) such as an HDD (abbreviation for Hard Disk Drive) or an SSD (abbreviation for Solid State Drive). Note that a flash memory may be used as the non-volatile auxiliary storage device instead of the HDD. The processor 40 executes a control program 42 input from the storage device 41. The storage device 41 includes an auxiliary storage device and a volatile storage device. The control program 42 is input to the processor 40 from the auxiliary storage device via the volatile storage device.

[0024] The processor 40 outputs processing data 43 such as calculation results to the volatile storage device of the storage device 41, and stores the processing data 43 in the auxiliary storage device via the volatile storage device as needed. As described above, the control device 10 controls the power conversion unit 1 by outputting the switching state quantities SWS of the multiple switching elements Q1 to Q6.

[0025] 3 is a diagram showing an example of the switching state quantity SWS of a plurality of switching elements in the case of two levels of the power conversion unit 1. The switching state quantity SWS is determined by a combination of on (:1) and off (:0) signals of each of the switching elements Q1 to Q6. In this case, this combination is uniquely determined by a switching parameter (a numerical value representing the level of the switching state) indicated by level 1, which is a switching state corresponding to on, and level 0, which is a switching state corresponding to off, and therefore can be defined as an index representing the switching state.

[0026] In Figure 3, there are a total of nine combinations of numerical values ​​for the switching state levels of switching elements Q1 and Q2, Q3 and Q4, and Q5 and Q6 that define the u-phase switching state SWu, the v-phase switching state SWv, and the w-phase switching state SWw, and these are distinguished by representing them with nine switching state indexes SW0 to SW8 (also referred to as switching state index SWN (where N is an integer from 0 to 8); the same applies below).

[0027] Specifically, there are nine switching state quantities SWS: eight switching state quantities (switching state quantities corresponding to switching state indexes SW0, SW1, SW2, SW3, SW4, SW5, SW6, and SW7) in which one of the switching elements Q1 to Q6 of the upper arm and lower arm is on and the other is off; and a switching state quantity (switching state quantity corresponding to switching state index SW8) in which all switching elements Q1 to Q6 are turned off when the operation of the power conversion unit 1 stops.

[0028] In the power conversion unit 1, when the polyphase voltage is a three-phase voltage, the voltage output of each phase of the three-phase voltage output value, i.e., the values ​​of the u-phase voltage Vu, the v-phase voltage Vv, and the w-phase voltage Vw, are output as voltages as shown in FIG. 4 based on the switching state quantity SWS of the power conversion unit shown in FIG. 3.

[0029] As shown in Fig. 4, the values ​​of the u-phase voltage Vu, v-phase voltage Vv, and w-phase voltage Vw are shown corresponding to the switching state indices SW0 to SW8. Here, Vdc represents the bus voltage Vdc of the DC power supply. The voltage output calculation unit 11 outputs the u'-phase voltage Vu', v'-phase voltage Vv', and w'-phase voltage Vw' shown in Fig. 5, which are corrected for the values ​​of the u-phase voltage Vu, v'-phase voltage Vv, and w-phase voltage Vw in Fig. 4 so that the neutral point is zero.

[0030] Fig. 6 is a block diagram showing the configuration of the switching calculation unit 131 according to embodiment 1. The switching calculation unit 131 in Fig. 6 performs calculations at predetermined intervals to calculate the switching state quantity SWS. As shown in FIG. 6, the switching calculation unit 131 includes a data integrator 50 that receives as input a primary switching state quantity SWS1 that is the current switching state quantity SWS, a voltage command integral value Pref, a voltage output integral value Pout, a voltage command integral value Pref, and a set value ΔP of the allowable range and outputs initial switching data DATASW0 (hereinafter also referred to as initial switching data DATASW0) that is a combination of these data, an allowable reach calculator 51 (allowable reach calculator-1 in FIG. 6) that calculates primary switching data DATASW1 based on the initial switching data DATASW0, a switching candidate calculator 52 that calculates secondary switching candidate data PreDATASW2 based on the primary switching data DATASW1 calculated by the allowable reach calculator 51, and a allowable reach calculator 53 that calculates secondary switching candidate data PreDATASW2 based on the secondary switching candidate data PreDATASW2 calculated by the switching candidate calculator 52. The system is configured with a reach calculator 51 (referred to as a permissible reach calculator-2 and a permissible reach calculator-3 in FIG. 6), a one-period calculator 53 that calculates primary switching data DATASW1 based on initial switching data DATASW0, a real-time switching candidate calculator 54 that calculates secondary switching candidate data PreDATASW2 based on the primary switching data DATASW1 calculated by the one-period calculator 53, a permissible reach calculator 51 (referred to as a permissible reach calculator-4 and a permissible reach calculator-5 in FIG. 6) that calculates secondary switching data DATASW2 based on the secondary switching candidate data PreDATASW2 calculated by the real-time switching candidate calculator 54, a switching selector 55 that calculates a next switching state quantity NextSWS based on multiple secondary switching data DATASW2, and a switching memory 56 that outputs the next switching state quantity NextSWS as a primary switching state quantity SWS1 for the next calculation. Details of each block will be described below.

[0031] An allowable reach calculator 51 in the secondary switching candidate data generator 57 calculates a duration Tsw1 until the voltage output integrated value Pout reaches an allowable boundary (limit of the allowable range; also simply referred to as a boundary) for an allowable range ΔPref, which is set by setting an allowable range setting value ΔP for the voltage command integrated value Pref when the initial switching data DATASW0 is input and the primary switching state quantity SWS1 continues to be output, and the voltage command integrated value Pref and voltage output integrated value Pout when the allowable boundary is reached, and outputs primary switching data DATASW1 which is a set of the primary switching state quantity SWS1, its duration Tsw1 (meaning the duration Tsw1 of the primary switching state quantity; the same applies hereinafter), and the voltage command integrated value Pref and voltage output integrated value Pout when the allowable boundary is reached.

[0032] The switching candidate calculator 52 in the secondary switching candidate data generator 57 receives the primary switching data DATASW1, selects a plurality of secondary switching state quantity candidates which are the next switching state quantities for which the voltage output integral value Pout can remain within the allowable range ΔPref, and outputs a plurality of secondary switching candidate data PreDATASW2 by adding these secondary switching state quantity candidates to the primary switching data DATASW1.

[0033] The one-period calculator 53 in the secondary switching candidate data generator 57 receives the initial switching data DATASW0, calculates the duration Tsw1 when the primary switching state quantity SWS1 is output for only one calculation period, the voltage command integral value Pref after one calculation period, and the voltage output integral value Pout, and outputs primary switching data DATASW1 that is a combination of the primary switching state quantity SWS1, the duration Tsw1, the voltage command integral value Pref after one calculation period, and the voltage output integral value Pout.

[0034] The instantaneous switching candidate calculator 54 in the secondary switching candidate data generator 57 receives the primary switching data DATASW1, selects one or more secondary switching state quantity candidates that are the next switching state quantities at which the voltage output integral value Pout can remain within the allowable range ΔPref when the switching state quantity SWS is changed during the next calculation, and outputs one or more secondary switching candidate data PreDATASW2 by adding these secondary switching state quantity candidates to the primary switching data DATASW1.

[0035] The plurality of allowable reaching calculators 51 (allowable reaching calculator-2 to allowable reaching calculator-5 in FIG. 6) each receive as input a plurality of secondary switching candidate data PreDATASW2 output by the secondary switching candidate data generator 57, and when switching to a secondary switching state quantity candidate, calculate the duration Tsw2 until the voltage output integral value Pout reaches the allowable boundary for the allowable range ΔPref, the voltage command integral value Pref and the voltage output integral value Pout at the time of arrival, and output secondary switching data DATASW2 by adding the secondary switching duration Tsw2, the voltage command integral value Pref and the voltage output integral value Pout at the time of arrival to the secondary switching candidate data PreDATASW2.

[0036] The switching selector 55 receives the secondary switching data DATASW2 output from the plurality of allowable reach calculators 51, evaluates the data through a predetermined calculation, and outputs a next switching state quantity NextSWS. When making the evaluation using a predetermined calculation, the reciprocal of the total value of the respective durations of the primary switching state quantity SWS1 and the secondary switching state quantity SWS2 included in the secondary switching data DATASW2 may be set as the evaluation value J, and the next switching state quantity NextSWS with the smallest evaluation value J may be searched for. Alternatively, the next switching state quantity NextSWS with the smallest evaluation value J may be searched for based on the number of switching changes SWcount of the primary switching state quantity SWS1 and the secondary switching state quantity SWS2, the primary duration Tsw1, and the secondary duration Tsw2, and the total duration Tswsum of the switching changes SWcount / duration.

[0037] As described above, the method of calculating the switching state quantity SWS of the power conversion unit 1 in embodiment 1 is a method of calculating the case where the switching state quantity SWS of the power conversion unit 1 is switched not only when the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref, but also when the switching state quantity SWS is switched inside the allowable range ΔPref.

[0038] As described above, there are names such as the current switching state quantity SWS1 and the secondary switching state quantity SWS2, and FIG. 7 is a diagram for explaining the maximum number of candidates for these switching state quantities SWS.

[0039] 7, it can be seen that the maximum number of candidates for the switching state quantity to be predicted increases exponentially depending on the order of the switching state quantity to be predicted. However, when calculating the switching state quantity candidates, restrictions are set such that candidates that cannot keep the voltage output integral value Pout within the allowable range ΔPref are excluded from the calculation, so in practice the number of candidates to be calculated for the switching state quantity SWS does not increase suddenly.

[0040] Fig. 8 is a diagram for explaining a method for determining the switching state quantity SWS of the power conversion unit 1 by the switching calculation unit 131 according to embodiment 1. Fig. 8 shows a case where the switching state quantity SWS of the power conversion unit 1 is calculated using the voltage command integral value Pref and the voltage output integral value Pout in the uvw coordinate system, which is a three-phase stationary coordinate system.

[0041] In Figure 8, at the start point, the three-phase voltage output integral value is set within the allowable range ΔPref indicated by Pr1 within the hexagonal allowable range (the same applies to other embodiments described below; see the black circle at time point a in Figure 8). Note that SW2 is being output as the switching state quantity SWS. The dotted arrow indicates the locus of the voltage command integral value. The allowable ranges ΔPref following Pr1 in time series are indicated by Pr2, Pr3, and Pr4, respectively (the same applies below).

[0042] First, a method for calculating the duration Tsw until the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref for the primary switching state quantity SWS1, which is the current switching state quantity SWS. By calculating the voltage output integral value Pout and the voltage command integral value Pref when SW2 continues to be output as the primary switching state quantity SWS1 from the current time point (the same as the above-mentioned start time point) by predictive calculation, it is calculated that the three-phase voltage output integral value will reach the allowable limit on the u-phase positive side of the hexagonal allowable range ΔPref (see time point c indicated by the black circle in FIG. 8), and the duration Tsw1 by the primary switching state quantity SWS1 from the current time point until it reaches the allowable limit is calculated (processed by the allowable reach calculator 51 in FIG. 6 (more accurately, the allowable reach calculator -1)).

[0043] Thereafter, the switching state quantity SWS is switched from SW2 to SW3 in order to keep the three-phase voltage output integral value within the hexagonal permissible range ΔPref (processed by the switching candidate calculator 52 in FIG. 6 ), and it is calculated that if SW3 continues to be output as the secondary switching state quantity SWS2, the three-phase voltage output integral value will reach the permissible limit on the w-phase negative side of the hexagonal permissible range ΔPref (see time point d marked with a black circle in FIG. 8 ), and the duration Tsw2 by the secondary switching state quantity SWS2 (if the duration between time points c and d marked with a black circle in FIG. 6 is expressed as Tcd, then the above Tsw2 becomes Tcd. Hereinafter, the duration between each point will be expressed in a similar manner) is calculated (processed by the permissible reach calculator 51 in FIG. 6 (here, the permissible reach calculator would be more accurately expressed as permissible reach calculator −2; similarly hereinafter)).

[0044] Next, a method of calculating the duration Tsw2 by switching the primary switching state quantity SWS1, which is the current switching state quantity SWS, to the secondary switching state quantity SWS2 after one calculation period will be described.

[0045] From the present time, a duration Tsw1 (=Tab, where Tab is the duration between the time point a indicated by the black circle and the time point b indicated by the black circle in FIG. 8) of the primary switching state quantity SWS1 when the primary switching state quantity SWS1 is output only for one calculation cycle (one calculation cycle) is calculated by predictive calculation (processed by the one-cycle calculator 53 in FIG. 6). Thereafter, the switching state quantity SWS is switched from SW2 to SW3 in order to keep the three-phase voltage output integral value within the hexagonal permissible range ΔPref (processed by the immediate switching candidate calculator 54 in FIG. 6), and if SW3 continues to be output as the secondary switching state quantity SWS2, it is calculated that the three-phase voltage output integral value will reach the permissible limit on the v-phase positive side of the hexagonal permissible range (see time point e indicated by the black circle in FIG. 8), and the duration Tsw2 by the secondary switching state quantity SWS2 is calculated (processed by the permissible reach calculator 51 in FIG. 6 (here, the permissible reach calculator may be more accurately expressed as permissible reach calculator-4)).

[0046] As described above, the primary and secondary durations when the primary and secondary switching state quantities are used from the current time are predicted and calculated. The next switching state quantity NextSWS output from the switching calculation unit 131 is calculated based on the number of switching changes SWcount to the primary and secondary switching state quantities SWS1 and SWS2 and the duration total value Tswsum, which is the sum of the primary duration Tsw1 and the secondary duration Tsw2. In FIG. 8 , it can be seen that the same switching state quantity SWS can be output for a longer period by using the primary switching state quantity SWS1 for only one calculation cycle and then continuing to output the secondary switching state quantity SWS2. Therefore, SW3 is output as the next switching state quantity NextSWS from the switching calculation unit 131.

[0047] In this way, by calculating whether it is better to switch the switching state quantity SWS not only when the allowable limit of the hexagonal allowable range ΔPref is reached (the primary duration Tsw1 in this case is equal to Tac), but also before the allowable limit is reached, it becomes possible to output the same switching state quantity SWS for a long period of time, thereby reducing the switching loss SWloss that occurs when the switching states of the multiple switching elements in the power conversion unit 1 transition.

[0048] Next, the control operation in the power conversion device 100 of this embodiment 1 will be described in detail below with reference to Figures 9A and 9B. Figures 9A and 9B are flowcharts illustrating the control operation in the power conversion device, with Figure 9A showing the first part of the flowchart and Figure 9B showing the second part of the flowchart. First, the voltage output calculation unit 11 calculates the multi-phase voltage output value Vout based on the switching state quantity SWS and Figure 5 (step S1).

[0049] Next, the integral value calculation unit 12 integrates the multiphase voltage command value Vref and the multiphase voltage output value Vout, respectively, to calculate a voltage command integral value Pref and a voltage output integral value Pout (step S2).

[0050] The calculated voltage command integral value Pref, voltage output integral value Pout, allowable range setting value ΔP, and primary switching state quantity SWS1, which is the current switching state quantity SWS, are calculated as initial switching data DATASW0 (step S3).

[0051] The switching calculation unit 131 executes calculations at predetermined intervals and calculates, by predictive calculations from the present time, whether to continue outputting the current switching state quantity SWS1 or to switch to the next switching state quantity SWS2. First, a calculation is made for the case where the current switching state quantity SWS1 is continued to be output.

[0052] When the primary switching state quantity SWS1 continues to be output based on the initial switching data DATASW0, the allowable reach calculator 51 calculates the duration Tsw1 until the voltage output integral value Pout reaches the allowable boundary, the voltage command integral value Pref, and the voltage output integral value Pout at the time of arrival, for the allowable range ΔPref, which is set by setting the allowable range setting value ΔP for the voltage command integral value Pref, and outputs primary switching data DATASW1 that is a combination of the primary switching state quantity SWS1, its duration Tsw1, and the voltage command integral value Pref and voltage output integral value Pout at the time of arrival (step S4).

[0053] The switching candidate calculator 52 selects candidates for the next switching state quantity, the secondary switching state quantity SWS2, based on the primary switching data DATASW1, and outputs one or more secondary switching candidate data PreDATASW2 by adding these secondary switching state quantity candidates to the primary switching data DATASW1 (step S5).

[0054] When the switching state quantity SWS is switched to a plurality of secondary switching candidate data PreDATASW2, the tolerance reach calculator 51 calculates the duration Tsw2 until the voltage output integral value Pout reaches the tolerance boundary for the tolerance range ΔPref, the voltage command integral value Pref and the voltage output integral value Pout at the time of arrival, and calculates the secondary switching data DATASW2 by adding the duration Tsw2 of the secondary switching, the voltage command integral value Pref and the voltage output integral value Pout at the time of arrival to the secondary switching candidate data (steps S6 and S7).

[0055] Next, a case is calculated in which the current switching state quantity SWS1 is switched to the next switching state quantity SWS1 before the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref.

[0056] The one-period calculator 53 calculates the duration Tsw1 of the primary switching state quantity SWS1 when it is output for only one calculation period, the voltage command integral value Pref, and the voltage output integral value Pout after one calculation period based on the initial switching data DATASW0, and outputs primary switching data DATASW1 that is a combination of the primary switching state quantity SWS1, its duration Tsw1, the voltage command integral value Pref, and the voltage output integral value Pout after one calculation period (step S8).

[0057] The instantaneous switching candidate calculator 54 selects a candidate for the next switching state quantity, the secondary switching state quantity SWS2, based on the primary switching data DATASW1 calculated by the one-period calculator 53, and outputs one or more secondary switching candidate data PreDATASW2 by adding this secondary switching state quantity candidate to the primary switching data DATASW1 (step S9).

[0058] When the switching state quantity SWS is switched to the multiple secondary switching candidate data PreDATASW2 calculated by the immediate switching candidate calculator 54, the allowable reaching calculator 51 calculates the duration Tsw2 until the voltage output integral value Pout reaches the allowable boundary for the allowable range ΔPref, the voltage command integral value Pref and the voltage output integral value Pout at the time of reaching, and calculates the secondary switching data DATASW2 by adding the duration Tsw2 of the secondary switching, the voltage command integral value Pref and the voltage output integral value Pout at the time of reaching to the secondary switching candidate data PreDATASW2 (steps S10, S11).

[0059] Based on all the calculated secondary switching data DATASW2, an evaluation value J for all combinations is calculated (step S12).From the calculated evaluation values ​​J, a combination that gives the smallest evaluation value J is calculated (step S13).

[0060] If the smallest evaluation value J results in continuing to output the current switching state quantity SWS1 up to the allowable limit, the primary switching state quantity SWS1, which is the current switching state quantity, is output. If the smallest evaluation value J results in switching the current switching state quantity SWS1 to the next switching state quantity SWS2 after one calculation cycle and continuing to output the next switching state quantity SWS2, the secondary switching state quantity SWS2, which is the next switching state quantity, is output (steps S14 to S16).

[0061] The power conversion unit 1 converts the DC power of the DC power supply 2 into AC power based on the switching state quantity SWS determined by the switching determination unit 13, and outputs the AC power to the load 3 (step S17). The load 3 is driven and controlled by the AC power output from the power conversion unit 1 (step S18).

[0062] 10A and 10B are diagrams illustrating the results of switching the switching state quantity SWS of the power conversion unit 1 only when the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref (see FIG. 10A), and switching the switching state quantity SWS when the allowable limit is reached and before the allowable limit is reached (see FIG. 10B), respectively.

[0063] 10A shows the difference between the voltage command integral value Pref and the voltage output integral value Pout, and the switching state indicators SW0 to SW8 of the switching state quantity SWS, when the switching state quantity SWS of the power conversion unit 1 is switched only when the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref. The results of FIG. 10A show that the switching state quantity SWS frequently switches in some areas.

[0064] In contrast, Fig. 10B shows the results when switching is performed both when the allowable limit is reached and before the allowable limit is reached, and it can be seen from the results of Fig. 10B that the phenomenon of frequent switching of the switching state quantity SWS that occurred in Fig. 10A does not occur, or that the number of switching times per unit time is reduced. From this result, it can be seen (predicted) that the number of switching times can be reduced by switching the switching state quantity SWS of the power conversion unit 1 not only when the allowable limit is reached but also before the allowable limit is reached.

[0065] As described above, the power conversion device 100 of the first embodiment includes the power conversion unit 1 that converts DC power of the DC power supply 2 into AC power and supplies the AC power to the load 3, the voltage output calculation unit 11 that calculates the multiphase voltage output value Vout based on the switching state quantity SWS output by the switching determination unit 13, the integral value calculation unit 12 that integrates the multiphase voltage command value Vref and the multiphase voltage output value Vout, respectively, to calculate the voltage command integral value Pref and the voltage output integral value Pout, and the switching determination unit 13 that calculates the switching state quantity SWS of the power conversion unit 1 based on the voltage command integral value Pref, the voltage output integral value Pout, and the set value ΔP of the allowable range. The switching calculation unit 131 in the switching determination unit 13 performs calculations at predetermined intervals, and calculates the switching state quantity SWS of the power conversion unit 1 based on the voltage command integral value Pref, the voltage output integral value Pout, and the allowable range set value ΔP. In order to determine whether to switch the switching state quantity SWS1, a prediction calculation is performed for the case where the primary switching state quantity SWS1, which is the current switching state quantity, is continued to be output, and the case where the switching state quantity SWS1 is switched to the secondary switching state quantity SWS2, which is the next switching state quantity, one calculation cycle from the present time, and the secondary switching state quantity SWS2 is continued to be output.If it is calculated that the same switching state quantity SWS will be output for a longer time if switched to the next switching state quantity SWS2 at the present time, the switching calculation unit 131 outputs the next switching state quantity before the voltage output integral value Pout reaches the allowable limit (also called the allowable boundary) of the allowable range ΔPref, which is set by the allowable range setting value ΔP of the voltage command integral value Pref.

[0066] For this reason, the power conversion device 100 of the first embodiment does not update the switching state quantity SWS only when the integrated voltage output value Pout reaches the allowable limit of the allowable range ΔPref, but calculates whether it is better to switch before the integrated voltage output value Pout reaches the allowable limit of the allowable range ΔPref, and if it is calculated that switching to the next switching state quantity at the current time will result in the same switching state quantity being output for a longer period of time, the switching calculation unit 131 outputs the next switching state quantity before the integrated voltage output value Pout reaches the allowable limit of the allowable range ΔPref. Therefore, compared to a method of updating the switching state quantity only when the allowable limit is reached, it is possible to drive and control the load 3 so as to reduce the switching loss SWloss of the power conversion unit 1. In other words, when calculating the next switching state quantity, the power conversion device 100 of the first embodiment calculates, based on candidate switching state quantities, a next switching state quantity that will last longer and have fewer switching changes, by predictive calculation, whether to switch the switching state quantity when the allowable limit is reached or to switch the switching state quantity from the current time (a point at which the allowable limit has not been reached). Therefore, compared to a configuration in which the switching state quantity is switched only when the allowable limit is reached, it is possible to reduce the switching loss that occurs when the switching state quantity is switched in the power conversion unit. Note that when only the switching state quantity is output, precision is not required when calculating the duration, so the effect is obtained that the calculation load is not likely to be high.

[0067] Second Embodiment A power conversion device 100A according to a second embodiment will be described below with reference to FIG. 11. FIG. 11 is a block diagram showing the configuration of the power conversion device 100A according to the second embodiment. The power conversion device 100A according to the second embodiment has the same configuration as the power conversion device 100 according to the first embodiment, but differs in the method of calculating the next switching state quantity NextSWS, which is the setting signal SetSW in the switching calculation unit 131A. Therefore, the switching determination unit 13A and the control device 10A have configurations different from those of the corresponding parts of the first embodiment.

[0068] FIG. 12 is a block diagram showing the configuration of a switching calculation unit 131A according to the second embodiment. The switching calculation unit 131A in FIG. 12 executes calculations at predetermined intervals to calculate the next switching state quantity NextSWS.

[0069] 12 , which shows the configuration of a switching calculation unit 131A according to the second embodiment, differs from the configuration of the first embodiment in that three switching state quantities SWS1 to SWS3, namely, the current switching state quantity (=primary switching state quantity SWS1), the secondary switching state quantity SWS2, and the tertiary switching state quantity SWS3, and durations Tsw1 to Tsw3 are calculated as prediction targets for switching of the switching state quantities of the power conversion unit 1. Since the prediction interval is longer by one switching state quantity than in the first embodiment, it is possible to further reduce the switching loss SWloss due to switching of the switching state quantity SWS of the power conversion unit 1 compared to the first embodiment.

[0070] The calculation method for determining whether to continue outputting the primary switching state quantity SWS1 until the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref or to switch before the allowable limit is explained in the first embodiment, and therefore will not be explained here.

[0071] The switching calculation unit 131A of FIG. 12 includes a secondary switching candidate data generator 57 that calculates one or more candidates for the secondary switching state quantity SWS2 based on the initial switching data DATASW0 generated by the data integrator 50, a tertiary switching candidate data generator 58 that generates one or more tertiary switching candidate data based on the secondary switching candidate data PreDATASW2, and a tertiary switching candidate data generator 59 that calculates one or more tertiary switching candidate data based on all the calculated tertiary switching candidate data PreDATASW3. The circuit is configured with a tolerance reach calculator 51 that calculates a duration Tsw3 until the voltage output integrated value Pout reaches the tolerance limit of the tolerance range ΔPref when candidates are continuously output, a switching selector 55A that calculates a next switching state quantity NextSWS based on the primary switching state quantities SWS1 to SWS3 and the primary duration times Tsw1 to SWS3, and a switching memory 56 that outputs the next switching state quantity NextSWS as the primary switching state quantity SWS1 for the next calculation. Each block will be described in detail below.

[0072] The secondary switching candidate data generator 57 has a block diagram similar to that of the first embodiment, and determines the next switching state quantity to be selected after outputting the primary switching state quantity SWS1 as the secondary switching state quantity SWS2, and outputs a plurality of secondary switching candidate data PreDATASW2 to which the primary switching state quantity SWS1, the primary duration Tsw1, the voltage command integral value Pref at the time of switching from the primary switching state quantity SWS1 to the secondary switching state quantity SWS2, and the voltage output integral value Pout are respectively added to this secondary switching state quantity candidate.

[0073] The tertiary switching candidate data generator 58 determines the next switching state quantity to be selected after outputting the secondary switching state quantity SWS2 as the tertiary switching state quantity SWS3 based on the secondary switching candidate data PreDATASW2 output by the secondary switching candidate data generator 57, and outputs a plurality of tertiary switching candidate data PreDATASW3 by adding this tertiary switching state quantity SWS3, the duration Tsw2 of the secondary switching state quantity, the voltage command integral value Pref at the time of switching from the secondary switching state quantity SWS2 to the tertiary switching state quantity SWS3, and the voltage output integral value Pout to the secondary switching candidate data PreDATASW2.

[0074] The allowable reach calculator 51 calculates a tertiary duration Tsw3, which is the time it takes for the voltage output integral value Pout to reach the allowable limit of the allowable range ΔPref when the tertiary switching state quantity SWS3 continues to be output based on the tertiary switching candidate data PreDATASW3 output by the tertiary switching candidate data generator 58, and outputs multiple tertiary switching data DATASW3 by adding this tertiary duration Tsw3 to each of the tertiary switching candidate data PreDATASW3.

[0075] The switching selector 55A receives the tertiary switching data DATASW3 output by the plurality of allowable reach calculators 51, evaluates the data by a predetermined calculation, and outputs the next switching state quantity NextSWS. When making the evaluation by a predetermined calculation, the reciprocal of the total duration value Tswsum of the primary duration times Tsw1 to Tsw3, which are the respective durations of the primary switching state quantities SWS1 to SWS3 included in the tertiary switching data DATASW3, may be set as the evaluation value J, and the next switching state quantity NextSWS with the smallest evaluation value J may be searched for. Alternatively, the total switching switching count value SWcountsum, which is the sum of the switching switching counts SWcount of the primary switching state quantities SWS1 to SWS3, and the total duration value Tswsum of the primary duration times Tsw1 to SWS3 may be set as the evaluation value J, and the next switching state quantity NextSWS with the smallest evaluation value J may be searched for.

[0076] As described above, the method of calculating the switching state quantity SWS of the power conversion unit 1 in the second embodiment calculates three switching state quantities SWS1 to SWS3, namely the current switching state quantity (=primary switching state quantity SWS1), the secondary switching state quantity SWS2, and the tertiary switching state quantity SWS3, and durations Tsw1 to Tsw3 as prediction targets for switching of the switching state quantity SWS of the power conversion unit 1, and then calculates the next switching state quantity NextSWS.Therefore, it is possible to further reduce the switching loss SWloss due to switching of the switching state quantity SWS of the power conversion unit 1 compared to the first embodiment in which calculations are only made up to the secondary switching state quantity SWS2.

[0077] Fig. 13 is a diagram for explaining a method for determining the switching state quantity SWS of the power conversion unit 1 by the switching calculation unit 131A according to embodiment 2. Fig. 13 shows a case where the switching state quantity SWS of the power conversion unit 1 is calculated using a voltage command integral value Pref and a voltage output integral value Pout in a uvw coordinate system, which is a three-phase stationary coordinate system. The method for calculating the switching state quantity SWS according to embodiment 2 in Fig. 13 differs from the method according to embodiment 1 in Fig. 8 in that calculation is performed up to the case where a tertiary switching state quantity SWS3 is output.

[0078] The start point in Fig. 13 is the same as in embodiment 1. Here, SW2 is being output as the switching state quantity SWS1. From this point, the primary duration Tsw1 based on the primary switching state quantity SWS1 and the secondary switching state quantity SWS2 are calculated using the same procedure as in embodiment 1 (secondary switching candidate data generator 57 in Fig. 12).

[0079] In the first embodiment, the secondary duration Tsw2 by the secondary switching state quantity SWS2 is the duration Tsw2 until the voltage output integrated value Pout reaches the allowable limit of the allowable range ΔPref when the secondary switching state quantity SWS2 is continuously output, but when calculating up to the tertiary switching state quantity SWS3, the secondary duration Tsw2 also takes into account the switching of the switching state quantity SWS before reaching the allowable limit, as with the primary duration Tsw1. Therefore, for each of the multiple secondary switching state quantities SWS2, the time until the allowable limit is reached and the time when switching is performed before reaching the allowable limit are calculated as the secondary duration Tsw2.

[0080] Then, based on the voltage command integral value Pref at the time of switching from the secondary switching state quantity SWS2 to the tertiary switching state quantity SWS3, the voltage output integral value Pout, and the set value ΔP of the allowable range, a plurality of candidates for the tertiary switching state quantity SWS3 are calculated, and the time until the allowable limit is reached if the tertiary switching state quantity SWS3 continues to be output is calculated as the tertiary duration time Tsw3 (processed by the allowable reach calculator 51 described above in FIG. 12).

[0081] As described above, the first duration Tsw1 to the third duration Tsw3 are predicted and calculated when the first to third switching state quantities SWS1 to SWS3 are used from the current time point. The switching state quantity SWS output from the switching calculation unit 131A is calculated based on the switching change count total value SWcountsum, which is the sum of the switching change counts SWcount from the first switching state quantities SWS1 to SWS3, and the duration total value Tswsum from the first duration Tsw1 to SWS3.

[0082] In FIG. 13, a candidate that uses the primary switching state quantity SWS1 for only one calculation cycle, then switches to the secondary switching state quantity SWS2 before it reaches the allowable limit, and calculates the tertiary switching state quantity SWS3 up to the allowable limit can output the same switching state quantity for a long time, so SW3 is output as the next switching state quantity NextSWS from the switching calculation unit 131A.

[0083] Next, the control operation of the power conversion device 100A of this embodiment 2 will be described in detail below with reference to FIGS. 14A and 14B. Here, FIGS. 14A and 14B are flowcharts illustrating the control operation of the power conversion device 100A. FIG. 14A is a flowchart (first half) illustrating an example of operation of the power conversion device according to embodiment 2, and FIG. 14B is a flowchart (second half) illustrating an example of operation of the power conversion device according to embodiment 2. Comparing FIGS. 14A and 14B with FIGS. 9A and 9B illustrating the control operation of embodiment 1, they differ in that prediction calculations are performed up to the third-order switching state quantity SWS3. Here, only the differences will be described in detail.

[0084] First, in the same procedure as in the first embodiment, the voltage output calculation unit 11 calculates the multiphase voltage output value Vout based on the switching state quantity SWS and FIG. 5 , and the integral value calculation unit 12 integrates the multiphase voltage command value Vref and the multiphase voltage output value Vout, respectively, to calculate the voltage command integral value Pref and the voltage output integral value Pout (steps S1 and S2).

[0085] Then, the calculated voltage command integral value Pref, voltage output integral value Pout, allowable range setting value ΔP, and primary switching state quantity SWS1, which is the current switching state quantity, are calculated as initial switching data DATASW0 (step S3).

[0086] The switching calculation unit 131A executes calculations at predetermined intervals and calculates, by predictive calculations from the present time, whether to continue outputting the current switching state quantity SWS1 or to switch to the next switching state quantity SWS2. Using the same procedures as in the first embodiment, the primary duration Tsw1 of the primary switching state quantity SWS1 and the secondary switching state quantity SWS2 are calculated in the cases of continuing to output the current switching state quantity SWS1 and switching to the next switching state quantity SWS2 (steps S4 and S5, steps 8 and 9).

[0087] Next, it is calculated whether to continue outputting the secondary switching state quantity SWS2 or switch to the next switching state quantity SWS3, and the secondary duration Tsw2 of the secondary switching state quantity SWS2 and the tertiary switching state quantity SWS3 are calculated. Thereafter, the tertiary switching state quantity SWS3 is continued to be output, and the tertiary duration Tsw3, which is the time until the voltage output integrated value Pout exceeds the allowable limit of the allowable range ΔPref, is calculated, and finally the tertiary switching data DATASW3 is calculated (steps S19 to S22, steps S23 to S26).

[0088] Based on all the calculated tertiary switching data DATASW3, an evaluation value J for all combinations is calculated (step S27).From the calculated evaluation values ​​J, a combination with the smallest evaluation value J is calculated (step S28).

[0089] If the smallest evaluation value J results in continuing to output the current switching state quantity SWS1 up to the allowable limit, the primary switching state quantity SWS1, which is the current switching state quantity, is output. If the smallest evaluation value J results in switching the current switching state quantity SWS1 to the next switching state quantity after one calculation cycle and continuing to output the next switching state quantity SWS2, the secondary switching state quantity SWS2, which is the next switching state quantity, is output (steps S14 to S16).

[0090] The power conversion unit 1 converts the DC power of the DC power supply 2 into AC power based on the switching state quantity SWS determined by the switching determination unit 13A and outputs the AC power to the load 3 (step S17). The load 3 is driven and controlled by the AC power output from the power conversion unit 1 (step S18).

[0091] As described above, the power conversion device 100A of the second embodiment is different from the power conversion device 100 of the first embodiment in the method of calculating the next switching state quantity NextSWS, and in the second embodiment, the prediction interval is set to the time until the voltage output integrated value Pout reaches the allowable limit of the allowable range ΔPref when the tertiary switching state quantity SWS3 is continuously output. Therefore, it is possible to further reduce the switching loss SWloss due to switching of the switching state quantity SWS of the power conversion unit compared to the first embodiment in which only up to the second switching state quantity SWS2 is calculated.

[0092] Third Embodiment A power conversion device 100B according to a third embodiment will be described below with reference to Fig. 15. Fig. 15 is a block diagram showing the configuration of a power conversion device 100B according to the third embodiment.

[0093] 15, compared to the second embodiment, the second embodiment differs in that a trained model 20 is provided instead of a switching calculation unit 131A, and this trained model 20 (which executes machine learning and outputs acquired data) is used. Therefore, a switching determination unit 13B and a control device 10B have configurations different from those of the corresponding parts in the second embodiment.

[0094] Next, a trained model 20 according to the third embodiment, which is different from the second embodiment, will be described below. The trained model 20 performs inference based on the voltage command integral value Pref, the voltage output integral value Pout, the allowable range setting value ΔP, and the current switching state quantity SWS1, based on information obtained by machine learning using teacher data, and calculates the next switching state quantity NextSWS of the power conversion unit.

[0095] 16 is a block diagram illustrating a method for creating a trained model 20 and machine learning based on training data. As shown in Fig. 16, a learning unit 70 performs machine learning based on training data 71 prepared in advance to generate a trained model 20.

[0096] Here, the learning data 71 includes the voltage command integral value Pref, the voltage output integral value Pout, the set value ΔP of the allowable range, and the current switching state quantity SWS1. The learning data 71 stores values ​​calculated using a method for driving the load 3, and may be generated using a method for calculating the switching state quantity SWS of the power conversion unit 1, as in the first or second embodiment, or may be generated using a method for calculating the prediction calculation interval of the second embodiment, which is further expanded, as will be described in a third embodiment.

[0097] As shown in FIG. 16 , learning data 71 is input to a teacher data acquiring unit 72. The teacher data acquiring unit 72 includes an input data acquiring unit 73 and a label data acquiring unit 74. The input data acquiring unit 73 acquires, from the learning data 71, the voltage command integral value Pref, the voltage output integral value Pout, the allowable range setting value ΔP, and the current switching state variable SWS1 as teacher input data 75, and outputs the acquired data to the learning unit 70. The label data acquiring unit 74 acquires, from the learning data 71, the next switching state variable NextSWS of the power conversion unit 1 as teacher label data 76, and outputs the acquired data to the learning unit 70. The teacher data 77 is made up of the teacher input data 75 and the teacher label data 76, and the learning unit 70 performs machine learning based on the teacher data 77, which is a combination of the teacher input data 75 and the teacher label data 76.

[0098] In this embodiment 3, machine learning with teacher data is performed by a neural network configured by combining perceptrons. The teacher data generated by these is provided to the neural network, and learning is repeated while changing the weighting of each perceptron so that the output of the neural network is the same as the teacher label data.

[0099] During the learning process, weighting values ​​are adjusted to reduce the error in the output of each perceptron by repeatedly performing processing using the backpropagation method. In other words, learning with teacher data involves adjusting weighting values ​​to eliminate errors between the teacher label data 76 and the neural network output data. In this way, the features of the teacher data 77 are learned, and a trained model 20 is acquired for making inferences based on inputs and deriving results.

[0100] The trained model 20 generated by machine learning in this way has the characteristics of the teacher data 77. For example, if the trained model 20 uses the data of embodiment 1, it will be able to obtain the same results as when the load 3 is driven using a procedure equivalent to embodiment 1. If the trained model 20 uses the data of embodiment 2, it will obtain the same results as embodiment 2. Note that the neural network used for learning by the learning unit 70 may be three-layered, but may also be more multi-layered, and may perform machine learning using deep learning.

[0101] 17 is a diagram showing a hardware configuration for generating the trained model 20. Machine learning for generating the trained model 20 is performed by a machine learning device that functions as a neural network, and the machine learning device 80 is realized by the hardware configuration shown in FIG.

[0102] The machine learning machine 80 is composed of a processor 81 and a storage device 82. The storage device 82 includes a volatile storage device, such as a RAM 83, and a non-volatile auxiliary storage device, such as an HDD 84. Note that an SSD or flash memory may be used as the non-volatile auxiliary storage device instead of the HDD 84. The HDD 84 stores a learning program 85 and training data 86, and also stores generated learning results 87.

[0103] Various learning programs 85 are input to the processor 81 from the HDD 84 via the RAM 83, and the processor 81 executes the various input learning programs 85. The learning programs 85 cause the processor 81 to perform learning with teacher data. That is, the teacher data 77 is also input to the processor 81 from the HDD 84 via the RAM 83, and the processor 81 learns according to the learning programs 85. The processor 81 also outputs data of the learning results to the RAM 83 of the storage device, and stores the data in the HDD 84 via the RAM 83 as needed. The learning programs 85 are programs that include instructions for causing the processor 81 to perform learning with teacher data and generate data of the results of machine learning (learning results 87).

[0104] The above-described machine learning machine 80 can be realized by a PC (Personal Computer), a server device, etc. However, because the amount of calculation is large, for example, it is possible to install a GPU (Graphics Processing Unit) in the PC and use the GPU for calculation processing of learning with teacher data using a technology called GPGPU (General-Purpose Computing on Graphics Processing Units) to enable high-speed processing.

[0105] Fig. 18 is a diagram for explaining the configuration of a switching calculation unit for calculating the next switching state quantity of the power conversion unit according to embodiment 3. Fig. 18 is a configuration in which the prediction interval of Fig. 12, which is a block diagram of the switching calculation unit 131A according to embodiment 2, is extended to the Nth-order switching state quantity, where N is an integer equal to or greater than 4, such as 4 or 5, and represents the number of switching state quantities to be calculated.

[0106] 18 is similar to that of the second embodiment, and therefore will not be described here. However, up to the N-1th switching state quantity, the calculation is performed as the duration Tsw until the voltage output integrated value Pout reaches the allowable limit of the allowable range ΔPref, or the duration Tsw before reaching the allowable limit, and only the Nth duration TswN, which is the duration of the Nth switching state quantity, is calculated as the duration Tsw until the allowable limit is reached. Note that, since there are many allowable reach calculators 51, not all are shown, but there are M (M: an integer of 3 or more), and Nth switching data DATASWN (N=1, 2, ..., M) output from each allowable reach calculator 51 in FIG. 18 (here, to more accurately express each individual allowable reach calculator, allowable reach calculator-1, allowable reach calculator-2, ..., allowable reach calculator-M) is input to the switching selector 55B. In the above, DATASWn is data including the first n-th SWSn, the first n-th Tswn, Pref at the time of SWS switching, and Pout, where n is an integer (initial value n=0). The same applies below.

[0107] Since it is difficult to implement the calculation method of Figure 18, which is a prediction calculation up to the Nth-order switching state quantity, in an actual device, in this embodiment 3, learning with teacher data is performed to create a learned model 20 and then implemented in an actual device.

[0108] As described above, the method of calculating the switching state quantity SWS of the power conversion unit 1 in the third embodiment calculates up to the Nth-order switching state quantity as a predicted destination for switching of the switching state quantity SWS of the power conversion unit 1, and then calculates the next switching state quantity NextSWS. Therefore, compared to the first or second embodiment, it is possible to further reduce the switching loss SWloss due to switching of the switching state quantity SWS of the power conversion unit 1.

[0109] Next, a method for creating the teacher data 77 according to the third embodiment will be described in detail below with reference to FIGS. 19A and 19B. FIGS. 19A and 19B show a flowchart for calculating the next switching state quantity NextSWS using the block diagram of FIG. 18. The teacher data 77 is generated according to the flowcharts of FIGS. 19A and 19B. Here, FIG. 19A shows the first half of a flowchart for generating the teacher data according to the third embodiment, and FIG. 19B shows the first half of a flowchart for generating the teacher data according to the third embodiment.

[0110] Using the same procedures as those in the flowcharts of Figures 14A and 14B in embodiment 2, Nth-order switching data DATASWN up to the Nth-order switching state quantity SWSN is calculated (steps S1 to S5, step S8, step S9, step S19, step S23, step S29 to step S31, step S32 to step S34).

[0111] Based on all the calculated N-th order switching data DATASWN, an evaluation value J for all combinations is calculated (step S35).From the calculated evaluation values ​​J, a combination with the smallest evaluation value J is calculated (step S36).

[0112] If the smallest evaluation value J results in continuing to output the current switching state quantity SWS1 up to the allowable limit, the primary switching state quantity SWS1, which is the current switching state quantity, is output. If the smallest evaluation value J results in switching the current switching state quantity SWS1 to the next switching state quantity, the secondary switching state quantity SWS2, after one calculation cycle and continuing to output the next switching state quantity, the secondary switching state quantity SWS2, which is the next switching state quantity, is output (steps S14 to S16).

[0113] Finally, the next switching state quantity, which is the secondary switching state quantity SWS2, the current switching state quantity SWS1, the current voltage command integral value Pref, the current voltage output integral value Pout, and the allowable range setting value ΔP are saved as teacher data 77 (step S37).

[0114] By repeatedly executing the above process, the teacher data 77 necessary for learning with teacher data is collected, and the collected teacher data 77 is used to perform learning with teacher data according to the procedure shown in Figure 16, thereby obtaining a trained model 20.

[0115] Finally, the control operation in the power conversion device 100B of this embodiment 3 will be described in detail below with reference to Fig. 20. Fig. 20 is a diagram showing a flowchart explaining the control operation in the power conversion device 100B. Compared with the control operations of the first and second embodiments, this embodiment differs in that the next switching state quantity NextSWS is calculated by the trained model 20 instead of the switching calculation unit 131A. Only the different points will be described in detail here.

[0116] First, in the same procedure as in the first and second embodiments, the voltage output calculation unit 11 calculates the multiphase voltage output value Vout based on the switching state quantity SWS and FIG. 5 , and the integral value calculation unit 12 integrates the multiphase voltage command value Vref and the multiphase voltage output value Vout, respectively, to calculate the voltage command integral value Pref and the voltage output integral value Pout (steps S1 and S2).

[0117] Then, the next switching state quantity NextSWS is calculated based on the calculated voltage command integral value Pref, the voltage output integral value Pout, the allowable range setting value ΔP, the current switching state quantity SWS1, and the learned model 20 (step S38).

[0118] The power conversion unit 1 converts the DC power of the DC power supply 2 into AC power based on the next switching state quantity SWS determined by the switching determination unit 13B and outputs the AC power to the load 3 (step S17). The load 3 is driven and controlled by the AC power output from the power conversion unit 1 (step S18).

[0119] As described above, the power conversion device 100B of the third embodiment is different from the power conversion devices 100 and 100A of the first and second embodiments in the method of calculating the next switching state quantity NextSWS, and the prediction interval is set to the time until the voltage output integrated value Vout reaches the allowable limit of the allowable range ΔPref when the Nth-order switching state quantity SWSN is continuously output. Therefore, it is possible to further reduce the switching loss SWloss caused by switching of the switching state quantity SWS of the power conversion unit 1 compared to the first and second embodiments in which only up to the second or third-order switching state quantity is calculated.

[0120] Fourth Embodiment A power conversion device 100C according to a fourth embodiment will be described below with reference to Fig. 21. Fig. 21 is a block diagram showing the configuration of a power conversion device 100C according to the fourth embodiment.

[0121] A power conversion device 100C according to the fourth embodiment differs from the configurations of the power conversion devices according to the first to third embodiments in that a switching calculation unit 131C outputs a switching state quantity SWS and a duration time Tsw of the switching state quantity as a setting signal SetSW. Therefore, a switching determination unit 13C and a control device 10C have configurations different from those of the corresponding parts of the first to third embodiments. In the fourth embodiment, only a method for calculating the switching state quantity SWS of the power conversion unit 1 and the duration time Tsw of the switching state quantity in the switching calculation unit 131C will be described.

[0122] Fig. 22 is a block diagram showing the configuration of a switching calculation unit 131C according to embodiment 4. The switching calculation unit 131C in Fig. 22 executes calculations at predetermined intervals to calculate the switching state quantity SWS and the duration Tsw of the switching state quantity.

[0123] As shown in FIG. 22, the switching calculation unit 131C includes a data integrator 50 that receives a first switching state quantity SWS1, which is a current switching state quantity, a voltage command integral value Pref, a voltage output integral value Pout, and a set value ΔP of an allowable range, and outputs initial switching data DATASW0, which is a combination of these data; an allowable-reaching switching candidate calculator 59 and an within-allowable switching candidate calculator 60 that calculate one or more secondary switching candidate data PreDATASW2 based on the initial switching data DATASW0 output by the data integrator 50; and a second switching state calculator 60 that outputs the second switching state quantity SWS2 based on one or more secondary switching candidate data PreDATASW2. The control circuit 55 is configured with an allowable reach calculator 51 and an allowable reach calculator 61 (here, the individual allowable reach calculators are more accurately expressed as allowable reach calculator-1, allowable reach calculator-2, and so on below; see FIG. 22) that calculate a secondary duration Tsw2 required for the voltage output integrated value Pout to reach the allowable limit of the allowable range ΔPref when the voltage output integrated value Pout continues to be input, a switching selector 55C that calculates a next switching state quantity NextSWS based on the primary switching state quantity SWS1 to the tertiary switching state quantity SWS3 and the primary duration Tsw1 to the tertiary duration Tsw3, and a switching update determiner 62 that outputs the next switching state quantity NextSWS as the primary switching state quantity SWS1 for the next calculation. Details of each block will be described below.

[0124] The allowable arrival switching candidate calculator 59 (more precisely, the allowable arrival switching candidate calculator is allowable arrival switching candidate calculator-1; see FIG. 22) calculates a primary duration Tsw1 until the voltage output integrated value Pout reaches the allowable limit of the allowable range ΔPref when the primary switching state quantity SWS1 continues to be output, determines the next switching state quantity to be selected after outputting the primary switching state quantity SWS1 as the secondary switching state quantity SWS2, and outputs a plurality of secondary switching candidate data PreDATASW2 to which the primary switching state quantity SWS1, the primary duration Tsw1, the voltage command integrated value Pref at the time of switching from the primary switching state quantity SWS1 to the secondary switching state quantity SWS2, and so on are respectively added to this secondary switching state quantity candidate.

[0125] The allowable reaching calculator 51 calculates a secondary duration Tsw2 required for the voltage output integral value Pout to reach the allowable limit of the allowable range ΔPref if the secondary switching state quantity SWS2 continues to be output, based on the plurality of secondary switching candidate data PreDATASW2 output by the allowable reaching switching candidate calculator 59, and outputs a plurality of secondary switching data DATASW2 each obtained by adding the duration Tsw2 of the secondary switching state quantity SWS2 to the secondary switching candidate data PreDATASW2.

[0126] The within-allowable switching candidate calculator 60 calculates a primary duration Tsw1 up to the point at which the primary switching state quantity SWS1 is switched to the next switching state quantity SWS2 before the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref when the primary switching state quantity SWS1 is continued to be output, determines the next switching state quantity to be selected after outputting the primary switching state quantity SWS1 as the secondary switching state quantity SWS2, and outputs a plurality of secondary switching candidate data PreDATASW2 to which the primary switching state quantity SWS1, the primary duration Tsw1, the voltage command integral value Pref at the time of switching from the primary switching state quantity SWS1 to the secondary switching state quantity SWS2, and so on are respectively added.

[0127] The within-allowable-range arrival calculator 61 calculates a secondary duration Tsw2 required for the voltage output integral value Pout to reach the allowable limit of the allowable range ΔPref if the secondary switching state quantity SWS2 continues to be output, based on the plurality of secondary switching candidate data PreDATASW2 output by the within-allowable-range switching candidate calculator 60, and outputs a plurality of secondary switching data DATASW2 each having the duration Tsw2 of the secondary switching state quantity SWS2 added to the secondary switching candidate data PreDATASW2.

[0128] The switching selector 55C receives the secondary switching data DATASW2 output from the plurality of allowable reach calculators 51 or the allowable reach calculator 61, and evaluates the data through a predetermined calculation. The reciprocal of the total duration value Tswsum of the primary duration Tsw1 and the secondary duration Tsw2 included in the secondary switching data DATASW2 may be set as the evaluation value J, and the combination of the primary and secondary switching state quantities SWS1 and SWS2 and the durations Tsw1 and Tsw2 that results in the smallest evaluation value J may be output. Alternatively, based on the number of switching changes SWcount of the primary and secondary switching state quantities SWS1 and SWS2 and the total duration value Tswsum of the primary and secondary durations Tsw1 and Tsw2, the number of switching changes SWcount / total duration value Tswsum may be set as the evaluation value J, and the combination of the primary and secondary switching state quantities SWS1 and SWS2 and the durations Tsw1 and Tsw2 that results in the smallest evaluation value J may be output.

[0129] If the primary duration Tsw1 is shorter than the calculation period, the switching update determiner 62 uses the secondary switching state quantity SWS2 as the primary switching state quantity SWS1 in the next calculation, and if the primary duration Tsw1 is longer than the calculation period, the switching update determiner 62 uses the primary switching state quantity SWS1 as the primary switching state quantity SWS1 in the next calculation.

[0130] As described above, the switching calculation unit 131C of the power conversion unit 1 in embodiment 4 outputs the primary and secondary switching state quantities SWS1 and SWS2 and the duration times Tsw1 and Tsw2 of the switching state quantities, respectively, and therefore, compared to the methods of embodiments 1 to 3, it is possible to calculate in advance the point in time at which the switching state quantity should be switched before the primary switching state quantity SWS1 reaches its allowable limit, and this can be executed at a calculation cycle with a longer interval than those of embodiments 1 to 3. Therefore, even in a case where the calculation cycle cannot be set short, such as in implementation on an inexpensive microcomputer, the effect of reducing the switching loss SWloss is realized.

[0131] Furthermore, since the duration TswN of the switching state quantity SWSN is also output from the switching calculation unit 131C, the time resolution of the switching timing of the switching state quantity SWSN can be set high, and the resolution of converting DC power to AC power in the power conversion unit 1 can also be increased. In the above, N is an integer. The same applies below. This reduces the total harmonic distortion (THD) contained in the AC power and reduces harmonic components generated in the load 3. In other words, when the duration of the switching state quantity is also selected, although precision is required when calculating the duration, the time resolution when the switching state quantity switches can be set high even if the calculation period is set long. Setting the time resolution when the switching state quantity switches high reduces harmonic components contained in the voltage or current in particular.

[0132] FIG. 23 is a diagram for explaining a switching time point for switching the switching state quantity SWS according to the fourth embodiment before the voltage output integrated value Pout reaches the allowable limit of the allowable range ΔPref.

[0133] 23 is a diagram illustrating the duration Tsw2 until the voltage output integral value Pout of the uvw phase reaches the allowable limit of the allowable range ΔPref of the uvw phase, where the vertical axis represents the duration (unit: seconds) at the switching state index SW4 and the horizontal axis represents (elapsed) time (unit: seconds). From Fig. 23, the time point at which the switching state quantity within the allowable range is switched is the point where the durations Tsw2 of any two phases intersect (hereinafter also referred to as the intersection point) among the durations of the uvw phase at the switching state index SW4.

[0134] In order to calculate the above intersection point, the duration Δt1 of the primary switching state quantity SWS1 and the duration Δt2 of the secondary switching state quantity SWS2 are required in Figure 23. The formulas for calculating these durations will be explained below. For ease of understanding, the duration of the primary switching state quantity is set to Δt1 and the duration of the secondary switching state quantity is set to Δt2.

[0135] The formula shown below is the voltage output value V due to the secondary switching state quantity when the difference between the voltage command integral value and the voltage output integral value matches ±ΔP, which is the limit value of the set value ΔP of the allowable range, at time T2 (the time when the allowable limit is reached using SWS2). n2 out The relationship between the secondary duration Δt and the allowable limit is finally given by equation (1). Similarly, the voltage output value V n1 out The relationship between the first-order duration tolerance limit and the first-order duration tolerance limit is expressed as Equation (2).

[0136]

[0137] Here, P err is the difference between the voltage command integral value Pref and the voltage output integral value Pout, ΔP is the set value of the allowable range, Vref is the amplitude value of the voltage command, ω is the frequency of the voltage command, θ0 is the phase of the uvw phase, with the u phase being 0 degrees, the v phase being -120 degrees, and the w phase being -240 degrees. n1 out is the voltage output value due to the primary switching state quantity (see FIG. 5), Δt is the duration of the primary switching state quantity, V n2out is the voltage output value due to the secondary switching state quantity (see FIG. 5), and Δt2 is the duration of the secondary switching state quantity.

[0138] When Δt1 when the switching state quantity is updated at time T1 (time when SWS1 is switched to SWS2) is calculated based on equation (1), equation (3) is obtained.

[0139] Here, equation (3) is rewritten based on equation (4) to obtain equation (5). From equation (5), if Δt1, which is the duration of the primary switching state quantity, is calculated, Δt2, which is the secondary switching state quantity, can be calculated.

[0140] Equation (5) is used to derive Δt, which is the duration of the primary switching state quantity. Since equation (5) calculates one Δt for each phase, Δt is calculated by focusing on two phases and forming simultaneous equations. If we consider any two γδ phases among the uvw phases, we can form the following simultaneous equations, and by rearranging the equations, we finally obtain equation (6). Using equation (6), it is possible to calculate Δt1 up to the point where the duration Δt2 of the secondary switching state quantities of two phases intersects, as shown in FIG.

[0141] Using the above formulas (1) to (5), in the case of the uvw phase, Δt1 for the uv phase, vw phase, and wu phase is calculated using formula (6), and then Δt2 is calculated using formula (5). When calculating Δt2, all durations Δt2 of the uvw phase are calculated.

[0142] By calculating the duration Δt1 of the primary switching state quantity and the duration Δt2 of the secondary switching state quantity in this way, it is possible to predict and calculate which secondary switching state quantity and at what timing should be switched so that the switching state quantity does not need to be switched for a longer period of time, and therefore the number of times the switching state quantity SWS of the power conversion unit 1 is switched can be reduced.

[0143] 24 explains a method for selecting a solution when the secondary duration Δt, which is the duration of the secondary switching state quantity SWS2, is calculated using equation (5). Since equation (5) provides two solutions for Δt, if the two solutions are positive or negative, the positive value is selected as the solution; if both solutions are negative, there is no solution; and if both solutions are positive, the solution with the smaller Δt is selected as the solution. The reason for selecting the solution with the smaller Δt is to ensure that the voltage output integrated value Pout is always within the allowable range ΔPref.

[0144] Fig. 25 is a diagram for explaining a method for determining the switching state quantity SWS of the power conversion unit 1 by the switching calculation unit 131C according to embodiment 4. Fig. 25 shows a case where the switching state quantity SWS of the power conversion unit 1 is calculated using the voltage command integral value Pref and the voltage output integral value Pout in the uvw coordinate system, which is a three-phase stationary coordinate system.

[0145] The start point in Fig. 25 is the same as in embodiment 1. Note that SW2 is being output as the switching state quantity SWS1.

[0146] In comparison with the first to third embodiments, the fourth embodiment includes an within-permissible arrival calculator 61 in addition to the within-permissible switching candidate calculator 60, and therefore, a method for calculating the switching state quantity SWS and the duration Tsw using these block diagrams will be described below.

[0147] The within-allowable reaching calculator 61 calculates a primary duration Tsw1 based on the primary switching state quantity SWS1 and a secondary duration Tsw2 based on the secondary switching state quantity SWS2 when using one or more candidate secondary switching state quantities (the within-allowable switching candidate calculator 60 calculates the candidate secondary switching state quantities SWS2) from the current time.

[0148] The primary duration Δt of the uv phase, vw phase, and wu phase when using the candidate secondary switching state quantity SWS2, which is the next switching state quantity from the current time point, is calculated by equation (6), and then, based on the calculated primary duration Δt, the secondary duration Δt in each of the uv and w phases when using the candidate secondary switching state quantity SWS2 is calculated by equation (5).

[0149] Note that for the secondary duration Δt, three Δts for the uvw phases are calculated, but only the smallest Δt is retained. Here, the calculated primary duration Δt is set as the duration Tsw1 of the primary switching state quantity SWS1, and the secondary duration Δt is set as the duration Tsw2 of the secondary switching state quantity SWS2. As can be seen from this explanation, the duration Tsw1 of the primary switching state quantity SWS1 is calculated using the following switching state quantity SWS2.

[0150] A predetermined calculation is performed based on the primary and secondary durations Tsw1 and Tsw2 when the primary and secondary switching state quantities SWS1 and SWS2 calculated by the above-mentioned allowable reach calculator 61 are used, and the primary and secondary durations Tsw1 and Tsw2 when the primary and secondary switching state quantities SWS1 and SWS2 calculated by the allowable reach calculator 51 are used, to calculate the switching state quantity SWS and duration Tsw to be output from the switching calculation unit 131C.

[0151] Here, the predetermined calculation is a calculation that calculates an evaluation value J for all combinations based on the number of switching changes SWcount to the primary and secondary switching state quantities SWS1 and SWS2 and the total duration value Tswsum of the primary and secondary durations Tsw1 and Tsw2, selects the combination with the smallest evaluation value J, and outputs this combination from the switching calculation unit 131C.

[0152] 25, SW2 continues to be used as the primary switching state quantity SWS1 from the present time, but switching to SW3 as the secondary switching state quantity SWS2 before the allowable limit is reached allows the same switching state quantity to be output for a longer period of time, and therefore the switching calculation unit outputs the results of calculations by the within-allowable switching candidate calculator 60 for the primary and secondary switching state quantities SWS1 and SWS2 and the primary and secondary durations Tsw1 and Tsw2. In addition, in FIG. 25, Tab is the primary duration from time a to b indicated by a black circle, and is the primary duration Tsw1 until the allowable limit is reached (here, set to the minimum Δt1 as an example) when SW2 continues to be used as the primary switching state quantity SWS1, and duration Tbc (similarly, the primary duration from time b to c indicated by a black circle) is the time until the allowable limit is reached when SW2 continues to be used as the primary switching state quantity SWS1. Similarly, duration Tcd (secondary duration from time c to time d of the black dot) is the secondary duration Tsw2 in the case where SW3 continues to be used as the secondary switching state quantity SWS2. The same is true for Tbe (secondary duration from time b to time e of the black dot).

[0153] In this way, by calculating whether it is better to switch the switching state quantity SWS not only when the allowable limit of the hexagonal allowable range ΔPref is reached but also before the allowable limit is reached, it becomes possible to output the same switching state quantity for a long time, thereby reducing the switching loss SWloss that occurs when the switching state quantities SWS of the multiple switching elements of the power conversion unit 1 transition.

[0154] Compared with the methods of the first to third embodiments, in the fourth embodiment, it is possible to calculate in advance the point in time before the primary switching state quantity SWS1 reaches the allowable limit at which to switch from the primary switching state quantity SWS1 to the secondary switching state quantity SWS2, and this can be executed at a calculation period with a longer interval than that of the first embodiment. The reason for this is that by using the above-mentioned formula, it is possible to predict by calculation the switching state quantity for a period longer than one period (for several periods).

[0155] Therefore, even in a case where the calculation period cannot be set short, such as in an implementation on an inexpensive microcomputer, the effect of reducing the switching loss SWloss can be achieved. Furthermore, since the duration Tsw of the switching state quantity SWS is also output from the switching calculation unit 131C, the time resolution of the switching timing of the switching state quantity SWS can be set high, and the resolution of converting DC power to AC power in the power conversion unit 1 can also be increased. As a result, the total harmonic distortion THD contained in the AC power can be reduced, and the harmonic components generated in the load 3 can also be reduced.

[0156] Next, the control operation in the power conversion device 100C of this embodiment 4 will be described in detail below with reference to Figures 26A and 26B. Figures 26A and 26B are flowcharts illustrating the control operation in the power conversion device 100C, with Figure 26A being a flowchart (first half) illustrating an example of operation of the power conversion device according to embodiment 4, and Figure 26B being a flowchart (second half) illustrating an example of operation of the power conversion device according to embodiment 4.

[0157] First, by performing the same processing as in the first embodiment, the voltage output calculation unit 11 calculates the multiphase voltage output value Vout based on the switching state quantity SWS and FIG. 5, and the integral value calculation unit 12 integrates the multiphase voltage command value Vref and the multiphase voltage output value Vout, respectively, to calculate the voltage command integral value Vref and the voltage output integral value Vout (steps S1 and S2).

[0158] Then, the calculated voltage command integral value Vref, voltage output integral value Vout, allowable range setting value ΔP, and primary switching state quantity SWS1, which is the current switching state quantity, are calculated as initial switching data DATASW0 (step S3).

[0159] The switching calculation unit 131C executes calculations at predetermined intervals and calculates, by predictive calculations from the current time point, whether to continue outputting the primary switching state quantity SWS1 or to switch to the next switching state quantity, that is, the secondary switching state quantity SWS2. The primary duration Tsw1, secondary switching state quantity SWS2, and duration Tsw2 of the primary switching state quantity when continuing to output the current primary switching state quantity SWS1 and when switching to the next secondary switching state quantity SWS2 are calculated as shown in Fig. 25. The primary switching state quantity SWS1, secondary switching state quantity SWS2, primary duration Tsw1, and secondary duration Tsw2 are output as secondary switching data DATASW2 (steps S39 to S44).

[0160] An evaluation value J is calculated based on all the calculated secondary switching data DATASW2 (step S45).A combination of the calculated evaluation values ​​J that results in the smallest evaluation value J is calculated (step S45).

[0161] The combination of the primary switching state quantity SWS1 and secondary switching state quantity SWS2 and the primary duration time Tsw1 and secondary duration time Tsw2 with the smallest evaluation value J is output, and the switching output unit determines the switching state quantity of the power conversion unit from the set switching state quantity and duration time (steps S47 and S48).

[0162] The power conversion unit 1 converts the DC power of the DC power supply 2 into AC power based on the switching state quantity SWS determined by the switching determination unit 13, and outputs the AC power to the load 3 (step S17). The load 3 is driven and controlled by the AC power output from the power conversion unit 1 (step S18).

[0163] As described above, in comparison with the first to third embodiments, the power conversion device 100C of the fourth embodiment calculates in advance the point in time at which the switching state quantity SWS is to be switched before the primary switching state quantity SWS1 reaches the allowable limit, and therefore can be executed at a calculation period with longer intervals than that of the first embodiment. As a result, even in a case where the calculation period cannot be set short, such as in implementation on an inexpensive microcomputer, the effect of reducing the switching loss SWloss is realized.

[0164] Furthermore, since the duration Tsw of the switching state quantity SWS is also output from the switching calculation unit, the time resolution of the switching timing of the switching state quantity SWS can be set high, and the resolution of converting DC power into AC power can also be increased in the power conversion unit 1. This reduces the total harmonic distortion THD contained in the AC power, and enables drive control with fewer harmonic components generated in the load.

[0165] Fifth Embodiment A power conversion device 100D according to a fifth embodiment will be described below with reference to Fig. 27. Fig. 27 is a block diagram showing the configuration of the power conversion device 100D according to the fifth embodiment.

[0166] The power conversion device 100D according to the fifth embodiment has the same configuration as the power conversion device 100C according to the fourth embodiment, but differs in the method of calculating combinations of the first to fourth switching state quantities SWS1 to SWS4 and the durations Tsw1 to Tsw4 as the setting signal SetSW in a switching calculation unit 131D. Therefore, a switching determination unit 13D and a control device 10D have configurations different from those of the corresponding parts of the fourth embodiment.

[0167] That is, the difference is that the switching state quantity SWS of the power conversion unit 1 is predicted to be switched by calculating four switching state quantities, from the current switching state quantity (=first switching state quantity SWS1) to the fourth switching state quantity SWS4, and the duration Tsw4 from the duration Tsw1.

[0168] Therefore, since the prediction interval is longer by two switching state quantities than in the fourth embodiment, it is possible to further reduce the switching loss SWloss due to switching of the switching state quantity SWS of the power conversion unit 1 and the harmonic components of the current or speed in the load 3 than in the fourth embodiment.

[0169] Fig. 28 is a block diagram showing the configuration of a switching calculation unit 131D according to embodiment 4. The switching calculation unit 131D in Fig. 28 performs calculations at predetermined intervals to calculate the switching state quantity SWS and the duration Tsw of the switching state quantity.

[0170] The switching calculation method in embodiment 5 calculates a tertiary duration Tsw3 and a quaternary duration Tsw4 when a tertiary switching state quantity SWS3 and a quaternary switching state quantity SWS4 are further output from the calculation completion point in time, based on the secondary switching data DATASW2 calculated in embodiment 4. Therefore, only a method for calculating the tertiary switching state quantity SWS3 from the secondary switching data DATASW2 calculated in embodiment 4, and a method for calculating the tertiary switching state quantity SWS3, the quaternary switching state quantity SWS4, the tertiary duration Tsw3 and the quaternary duration Tsw4, based on the tertiary switching state quantity SWS3 will be described here.

[0171] The secondary switching data DATASW2 is calculated using the same procedure as in embodiment 4. The secondary switching data DATASW2 includes the primary switching state quantity SWS1, the secondary switching state quantity SWS2, the primary duration time Tsw1, the secondary duration time Tsw2, and the voltage command integral value Pref and the voltage output integral value Pout at the time when the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref when the secondary switching state quantity SWS2 is continuously output.

[0172] Next, the tertiary switching candidate calculator 63 (more precisely, the tertiary switching candidate calculators are tertiary switching candidate calculator-1 and tertiary switching candidate calculator-2; see FIG. 28) selects a tertiary switching state quantity SWS3 based on one or more secondary switching data DATASW2, adds one or more tertiary switching state quantities SWS3 to the secondary switching data DATASW2, and outputs the result as tertiary switching candidate data PreDATASW3.

[0173] Based on one or more tertiary switching candidate data PreDATASW3 calculated by the tertiary switching candidate calculator 63, the allowable reaching switching candidate calculator 59 outputs the tertiary duration Tsw3 when the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref if the tertiary switching state quantity SWS3 is continued to be output, the quaternary switching state quantity SWS4, the voltage command integral value Pref at the time of switching between the tertiary and quaternary switching state quantities, and the voltage output integral value Pout, in addition to the primary switching state quantities SWS1 to tertiary switching state quantities SWS3 and the primary duration Tsw1 to tertiary duration Tsw3.

[0174] Based on one or more tertiary switching candidate data PreDATASW3 calculated by the tertiary switching candidate calculator 63, the within-allowable switching candidate calculator 60 outputs the tertiary duration Tsw3 when switching to the quaternary switching state quantity SWS4 before the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref if the tertiary switching state quantity SWS3 is continued to be output, the quaternary switching state quantity SWS4, the voltage command integral value Pref at the time of switching between the tertiary and quaternary switching state quantities, and the voltage output integral value Pout, in addition to the primary switching state quantities SWS1 to tertiary switching state quantities SWS3 and the primary duration Tsw1 to tertiary duration Tsw3.

[0175] Based on one or more fourth-order switching candidate data PreDATASW4 output from the allowable reaching switching candidate calculator 59 and the within-allowable switching candidate calculator 60, the allowable reaching calculator 51 or the within-allowable reaching calculator 61 calculates the fourth-order duration Tsw4 when the voltage output integrated value Pout reaches the allowable limit of the allowable range ΔPref if the fourth-order switching state quantity SWS4 is continuously output, and outputs this as the fourth-order switching data DATASW4 in addition to the fourth-order switching candidate data PreDATASW4. Note that in the above, the switching candidate data PreDATASWn is data including the nth SWSn, the n-1th Tswn, Pref at the time of SWS switching, and Pout. Here, n is an integer, and initially n=2. The same applies below.

[0176] Up to this point, the calculation procedure has been explained, starting from the data integrator 50 and going from the allowable reached switching candidate calculator 59 to the fourth switching data DATASW4 which is input to the switching selector. However, the calculation procedure starting from the data integrator 50 and going from the within-allowable switching candidate calculator 60 to the fourth switching data DATASW4 which is input to the switching selector is also similar, with the difference being that there is a case where switching is performed between the primary switching state quantity SWS1 and the secondary switching state quantity SWS2 before the voltage output integrated value Pout reaches the allowable limit of the allowable range ΔPref, and therefore detailed explanation will be omitted.

[0177] The switching selector 55D receives the fourth switching data DATASW4 output from the plurality of allowable reach calculators 51 or the allowable reach calculator 61 and evaluates it by a predetermined calculation. The reciprocal of the duration total value Tswsum of the first to fourth durations Tsw1 to Tsw4 included in the fourth switching data DATASW4 is set as an evaluation value J, and the switching selector 55D may output a combination of the first to fourth switching state quantities SWS1 to SWS4 and the first durations Tsw1 to SWS4 that produces the smallest evaluation value J, or may output a combination of the first to fourth switching state quantities SWS1 to SWS4 and the first durations Tsw1 to SWS4 that produces the smallest evaluation value J. Based on the total value SWcounts of switching changes, which is a sum, and the total duration value Tswsum from the first duration Tsw1 to the fourth duration Tsw4, the total value SWcounts of switching changes / total duration value Tswsum may be set as an evaluation value J, and the combination of the first switching state quantity SWS1 to the fourth switching state quantity SWS4 and the first duration Tsw1 to the fourth duration Tsw4 that results in the smallest evaluation value J may be output.

[0178] If the calculation period is shorter than the primary duration Tsw1, the switching update determiner 62D uses the primary switching state quantity SWS1 as the primary switching state quantity SWS1 in the next calculation; if the calculation period is longer than the primary duration Tsw1 and shorter than the sum of the primary duration and the secondary duration, the switching update determiner 62D uses the secondary switching state quantity SWS2 as the primary switching state quantity SWS1 in the next calculation; if the calculation period is longer than the sum of the primary duration and the secondary duration and shorter than the sum of the primary duration to the tertiary duration, the switching update determiner 62D uses the tertiary switching state quantity SWS3 as the primary switching state quantity SWS1 in the next calculation; and if the calculation period is longer than the sum of the primary duration to the tertiary duration, the switching update determiner 62D uses the quaternary switching state quantity SWS4 as the primary switching state quantity SWS1 in the next calculation.

[0179] As described above, the switching calculation unit 131D of the power conversion unit 1 in embodiment 5 outputs the first-order switching state quantity SWS1 to the fourth-order switching state quantity SWS4 and the durations Tsw1 to Tsw4 of the switching state quantities, respectively. Therefore, compared to the method in embodiment 4, the prediction interval is set to the time until the voltage output integrated value Pout reaches the tolerance limit of the tolerance range ΔPref when the fourth-order switching state quantity SWS4 is continuously output.

[0180] Therefore, it is possible to further reduce the switching loss SWloss due to switching of the switching state quantity SWS of the power conversion unit 1 or the harmonic components contained in the current or speed generated in the load 3 compared to the fourth embodiment in which only up to the secondary switching state quantity SWS2 is calculated.

[0181] 29 is a diagram for explaining a method for determining the switching state quantity SWS of the power conversion unit 1 by the switching calculation unit 131D according to the fifth embodiment, and shows a case where the switching state quantity SWS of the power conversion unit 1 is calculated using the voltage command integral value Pref and the voltage output integral value Pout in the uvw coordinate system, which is a three-phase stationary coordinate system. The start point in FIG. 29 is the same as in the first embodiment.

[0182] 29, the secondary switching state quantity SWS2 is output as the primary switching state quantity SWS1. Furthermore, in the fifth embodiment, compared to the fourth embodiment, a tertiary switching state quantity SWS3 and a quaternary switching state quantity SWS4 are further calculated, and therefore only the details of these will be described.

[0183] First, the primary switching state quantity SWS1, the secondary switching state quantity SWS2, the primary duration Tsw1, and the secondary duration Tsw2 are calculated using the same procedure as in embodiment 4. Then, when the secondary switching state quantity SWS2 is continuously output, the time from the point in time when the voltage output integrated value Pout reaches the allowable limit of the allowable range ΔPref until the tertiary switching state quantity SWS3 continues to be output and the time until switching occurs before the allowable limit is reached are calculated.

[0184] Furthermore, after calculating the third duration Tsw3, which is the duration of the third switching state quantity SWS3, the fourth switching state quantity SWS4 is selected, and a fourth duration Tsw4, which is the duration until the voltage output integrated value Pout reaches the tolerance limit of the tolerance range ΔPref, is calculated when the fourth switching state quantity SWS4 is continuously output.

[0185] Based on the calculated first-order switching state quantity SWS1 to fourth-order switching state quantity SWS4 and the first-order duration times Tsw1 to fourth-order duration times Tsw4 of the switching state quantities, a predetermined calculation is performed to calculate the switching state quantity SWS and duration times Tsw output from the switching calculation unit 131D.

[0186] The predetermined calculation is a calculation in which an evaluation value J of all combinations is calculated based on a switching switching count total value SWcountsum, which is the sum of the switching switching counts SWcount from the primary switching state quantity SWS to the fourth switching state quantity SWS4, and a duration total value Tswsum from the primary duration Tsw1 to the fourth duration Tsw4, and the combination with the smallest evaluation value J is selected and output from the switching calculation unit 131D.

[0187] 29, SW2 continues to be used as the primary switching state quantity SWS1 from the present time, but switching to SW3 as the secondary switching state quantity SWS2 before the allowable limit is reached allows the same switching state quantity to be output for a longer period of time, and therefore the primary switching state quantities SWS1 to SWS4 and the primary duration times Tsw1 to Tsw4 are calculated from the within-allowable switching candidate calculator 60 after the data integrator 50 from the switching calculation unit 131D. Note that in FIG. 29, Tab is the primary duration from time point a to time point b indicated by a black circle, and is the primary duration time Tsw1 until the allowable limit is reached (here, the time for one period is taken as an example) when SW2 continues to be used as the primary switching state quantity SWS1, and duration time Tbc (similarly, the primary duration from time point b to time point c indicated by a black circle) is the time until the allowable limit is reached when SW2 continues to be used as the primary switching state quantity SWS1. Similarly, duration Tcd (secondary duration from black circle time point c to black circle time point d) is the secondary duration Tsw2 when SW3 continues to be used as the secondary switching state quantity SWS2. The same is true for Tbg (secondary duration from black circle time point b to black circle time point g). Similarly, the same is true for Tde and Tgh (third-order duration from black circle time point c to black circle time point d and from black circle time point g to black circle time point h, respectively) for the tertiary duration Tsw3 in the tertiary switching state quantity SWS3, and for Tef and Thi (fourth-order duration from black circle time point e to black circle time point f and from black circle time point h to black circle time point i, respectively) for the quaternary duration Tsw4 in the quaternary switching state quantity SWS4.

[0188] Next, the control operation in the power conversion device 100D of this embodiment 5 will be described in detail below with reference to Figures 30A, 30B, and 30C. Here, Figures 30A, 30B, and 30C are diagrams showing flowcharts explaining the control operation in the power conversion device 100D, where Figure 30A is a diagram showing the first half of a flowchart illustrating an example of operation of the power conversion device according to embodiment 5, Figure 30B is a diagram showing the first half of a flowchart illustrating an example of operation of the power conversion device according to embodiment 5, and Figure 30C is a diagram showing the second half of a flowchart illustrating an example of operation of the power conversion device according to embodiment 5.

[0189] First, by performing the same processing as in the fourth embodiment, the voltage output calculation unit 11 calculates the multiphase voltage output value Vout based on the switching state quantity SWS and FIG. 5, and the integral value calculation unit 12 integrates the multiphase voltage command value Vref and the multiphase voltage output value Vout, respectively, to calculate the voltage command integral value Pref and the voltage output integral value Pout.

[0190] Then, the calculated voltage command integral value Pref, voltage output integral value Pout, allowable range setting value ΔP, and primary switching state quantity SWS1, which is the current switching state quantity, are calculated as initial switching data DATASW0.

[0191] The switching calculation unit 131D executes calculations at predetermined intervals and calculates, by predictive calculations from the present time, whether to continue outputting the primary switching state quantity SWS1, which is the current switching state quantity, or to switch to the next secondary switching state quantity SWS2. The primary switching state quantity SWS1 and the primary duration Tsw1, and the secondary switching state quantity SWS2 and the secondary duration Tsw2 are calculated for the case where the current primary switching state quantity SWS1 is continued to be output, and for the case where the current primary switching state quantity SWS1 is switched to the next secondary switching state quantity SWS2.

[0192] Furthermore, from the point in time when the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref while continuing to output the second switching state quantity SWS2, the third switching state quantity SWS3 and the fourth switching state quantity SWS4, and the third duration Tsw3 and the fourth duration Tsw4 when switched to the third switching state quantity SWS3 are calculated using the same procedure.

[0193] A combination of all the calculated first to fourth switching state quantities SWS1 to SWS4 and the first to fourth duration times Tsw1 to Tsw4 is output as fourth switching data DATASW4.

[0194] An evaluation value J is calculated based on all the calculated fourth-order switching data DATASW4. A combination that results in the smallest evaluation value J is calculated from the calculated evaluation values ​​J. The combination of the first-order switching state quantities SWS1 to SWS4 and the first-order duration times Tsw1 to Tsw4 that results in the smallest evaluation value J is output.

[0195] The power conversion unit 1 converts the DC power of the DC power supply 2 into AC power based on the switching state quantity SWS determined by the switching determination unit 13D, and outputs the AC power to the load 3. The load 3 is driven and controlled by the AC power output from the power conversion unit 1.

[0196] As described above, the power conversion device 100D of the fifth embodiment is different from the fourth embodiment in that it calculates four switching state quantities, from the current switching state quantity (=first-order switching state quantity SWS1) to the fourth-order switching state quantity SWS4, and the durations Tsw1 to Tsw4, as prediction targets for switching of the switching state quantity SWS of the power conversion unit 1. Since the prediction interval is two switching state quantities longer than in the fourth embodiment, it is possible to further reduce the switching loss SWloss due to switching of the switching state quantity SWS of the power conversion unit 1 and the harmonic components of the current or speed in the load 3 compared to the fourth embodiment. In other words, in the power conversion devices of the fourth and fifth embodiments, when the durations of the switching state quantities are also selected as setting signals, precision is required in calculating the durations. Therefore, the amount of calculation is greater than in a method of calculating only the switching state quantities. However, even if the calculation period is set long, it is possible to set a high time resolution when switching the switching state quantities. If the time resolution at the time of switching of the switching state quantity is set high, it is possible to reduce the harmonic components contained in the voltage or current in particular.

[0197] In addition, the prediction interval calculated in the power conversion device 100D of embodiment 5 may be changed to calculation up to the Nth-order switching state quantity, as in embodiment 3, and learning with teacher data may be performed to generate a trained model, which may then be implemented in an actual device.In this case, compared to embodiment 5, the switching loss SWloss due to switching of the switching state quantity SWS of the power conversion unit 1 and the harmonic components of the current or speed in the load 3 can be further reduced.

[0198] Sixth Embodiment A power conversion device 100E according to a sixth embodiment will be described below with reference to FIG. 31. Here, FIG. 31 is a block diagram showing the configuration of the power conversion device 100E according to the sixth embodiment. The power conversion device 100E according to the sixth embodiment has the same configuration as the power conversion device 100 according to the first embodiment, but differs in the method of calculating the next switching state quantity NextSWS, which is the setting signal SetSW in the switching calculation unit 131E. Therefore, the switching determination unit 13E and the control device 10E have configurations different from those of the corresponding parts of the first embodiment.

[0199] FIG. 32 is a block diagram showing the configuration of a switching calculation unit 131E according to embodiment 6. The switching calculation unit 131E in FIG. 32 performs calculations at predetermined intervals, calculates the switching state quantity SWS and the duration time Tsw of the switching state quantity, and outputs the next switching state quantity NextSWS.

[0200] In FIG. 32, which shows the configuration of the switching calculation unit 131E of the sixth embodiment, the difference from the configuration of the first embodiment is that the immediate switching candidate calculator 54 and the allowable arrival calculator 51 (the allowable arrival calculator is more accurately expressed as allowable arrival calculator-1, the same below, see FIG. 32) are executed based on the results of the allowable switching candidate calculator 60 (here, this allowable switching candidate calculator is more accurately expressed as allowable switching candidate calculator-1, the same below, see FIG. 32) and the allowable arrival calculator 61 (here, the individual allowable arrival calculators are more accurately expressed as allowable arrival calculator-1, allowable arrival calculator-2, the same below, see FIG. 32), which is described in the fourth embodiment, and the configuration combines the processing of the first embodiment and the fourth embodiment. Note that, since each block diagram is described in the first embodiment and the fourth embodiment, only the method and effect of combining the block diagrams of the first embodiment and the fourth embodiment will be described here.

[0201] First, using the same procedure as in embodiment 4, the within-allowable switching candidate calculator 60 and the within-allowable arrival calculator 61 calculate one or more combinations of primary switching state quantities SWS1 and secondary switching state quantities SWS2, and primary duration times Tsw1 and secondary duration times Tsw2, and output them as provisional secondary switching data.

[0202] The immediate switching candidate selector calculates, by a predetermined calculation, from all the secondary switching temporary data TempDATASW2, a combination that produces the longest duration total value Tswsum of the primary duration Tsw1 and the secondary duration Tsw2 when the primary switching state quantity SWS1 is switched before reaching the allowable limit, or a set of the primary switching state quantity SWS1 and the secondary switching state quantity SWS2 and the primary duration Tsw1 and the secondary duration Tsw2 based on the switching switching count SWcount and the duration total value Tswsum of the primary switching state quantity SWS1 and the secondary switching state quantity SWS2. Here, the secondary switching temporary data TempDATASW2 is data including the first two SWSs, the first two Tswns, the SWS switching time points Pref, and Pout.

[0203] If the calculated primary duration Tsw1 of the primary switching state quantity is equal to or shorter than a predetermined set time, the secondary switching state quantity SWS2 is output as secondary switching candidate data PreDATASW2, and if it is longer than the predetermined set time, the output is invalid.

[0204] The permissible reach calculator 51 (here, the individual permissible reach calculators are more accurately expressed as permissible reach calculator-2, permissible reach calculator-3, permissible reach calculator-4; the same applies below; see FIG. 32) uses the secondary switching state quantity SWS2 based on one or more secondary switching candidate data PreDATASW2 output by the switching candidate calculator 52 (here, the switching candidate calculator is more accurately expressed as switching candidate calculator-1; the same applies below; see FIG. 32) and the immediate switching candidate calculator 54. A secondary duration Tsw2, which is the duration until the voltage output integral value Pout reaches the tolerance limit of the tolerance range ΔPref when the secondary switching state quantity is continuously output, is calculated, and the voltage command integral value Pref, the voltage output integral value Pout, and the secondary duration Tsw2 at the time when the voltage output integral value Pout reaches the tolerance limit of the tolerance range ΔPref when the secondary switching state quantity is continuously output, are added to one or more secondary switching candidate data PreDATASW2, and output as secondary switching data DATASW2.

[0205] The switching selector 55E outputs the next switching state quantity NextSWS by a predetermined calculation based on one or more secondary switching data DATASW2 and on a combination of the primary and secondary switching state quantities and durations.

[0206] In addition, the calculation periods of the data integrator 50, the allowable reach calculator 51, the switching candidate calculator 52, and the within-allowable switching candidate calculator 60 may be set to be the same, and the calculation periods of the immediate switching candidate calculator 54, the allowable reach calculator 51 that performs calculations based on the results of the immediate switching candidate calculator 54, and the switching selector 55E may be set to be shorter.

[0207] By setting the calculation period in this manner, it is possible to perform the calculation at long intervals according to the fourth embodiment, and the effect of reducing the switching loss SWloss can be realized even when implemented in an inexpensive microcomputer, and the resolution of the duration Tsw of the switching state quantity can be increased, thereby reducing harmonic components generated in the load 3. That is, the power conversion device of the sixth embodiment is configured to calculate the point at which the switching state quantity described in the fourth embodiment is switched before it reaches its allowable limit, and to calculate only the switching state quantity near that point, so that the point at which the switching state quantity is switched can be made more accurate.

[0208] Furthermore, by calculating the point at which the switching state quantity SWS switches according to the first embodiment, it is possible to calculate the point at which the switching state quantity SWS switches with greater accuracy than the calculation according to the fourth embodiment, and therefore the effect of reducing the switching loss SWloss is further improved and the harmonic components generated in the load 3 can be further reduced.

[0209] Fig. 33 is a diagram for explaining a method for determining the switching state quantity SWS of the power conversion unit 1 by the switching calculation unit 131E according to embodiment 6. Fig. 33 shows a case where the switching state quantity SWS of the power conversion unit 1 is calculated using the voltage command integral value Pref and the voltage output integral value Pout in the uvw coordinate system, which is a three-phase stationary coordinate system.

[0210] 33, the start point is the point at which the three-phase voltage output integral value is located near the center of the hexagonal permissible range ΔPref. Note that the switching state indicator SW2 is being output as the primary switching state quantity SWS1.

[0211] The sixth embodiment differs from the first to fifth embodiments in that the immediate switching candidate calculator 54 and the permissible reach calculator 51 (the permissible reach calculators here are permissible reach calculator-2, permissible reach calculator-3, and permissible reach calculator-4) of the first embodiment are executed based on the result of the permissible reach calculator 61 in the fourth embodiment. Therefore, the following will only explain under what conditions the calculation result of the permissible reach calculator 61 causes the immediate switching candidate calculator 54 and the associated permissible reach calculator 51 (the associated permissible reach calculators are permissible reach calculator-2, permissible reach calculator-3, and permissible reach calculator-4) to execute processing.

[0212] The within-allowable switching candidate calculator 60 and the within-allowable reach calculator 61 calculate the primary switching state quantity SWS1 and the secondary switching state quantity SWS2, and the primary duration Tsw1 and secondary duration Tsw2 corresponding to these switching state quantities, from the current time point, in the same procedure as in embodiment 4. At this time, if the primary duration Tsw1, which is the duration of the primary switching state quantity, is included in the set time range, the within-allowable reach calculator 51 is executed based on the secondary switching state quantity SWS2 calculated by the within-allowable reach calculator 61, and in the same procedure as in embodiment 1, the primary switching state quantity SWS1 is output for one calculation cycle from the current time point, and then switched to the secondary switching state quantity SWS2, and the secondary duration Tsw2 in the case of continuing to output the secondary switching state quantity SWS2 is calculated.

[0213] Based on all the calculated primary switching state quantities SWS1 and secondary switching state quantities SWS2, the primary duration Tsw1 and the secondary duration Tsw2, a predetermined calculation is performed to calculate the next switching state quantity NextSWS to be output from the switching calculation unit 131E.

[0214] Here, the predetermined calculation is to calculate an evaluation value J for all combinations based on the number of switching changes SWcount to the primary and secondary switching state quantities and the total duration value Tswsum of the primary duration and the secondary duration, select the combination with the smallest evaluation value J, and output this combination from the switching calculation unit 131E.

[0215] In Fig. 33, the voltage output integrated value Pout is located at a point within the set time range for the primary duration Tsw1 calculated by the allowable reach calculator 61, and therefore the secondary duration Tsw2 by SW3 is calculated as the secondary switching state quantity SWS2 by the allowable reach calculator 51. Note that in Fig. 33, the symbols Ta a*b and Tab e indicating durations indicate the duration between time a and time a*b, and the duration between time a*b and time e, respectively. Here, time a*b is the internal division point between time a and time b. Also, Tab indicates the time range set as the time range up to the intersection point.

[0216] In the case of Figure 33, it is possible to output the same switching state quantity for a longer period of time by immediately switching to the secondary switching state quantity SWS2 rather than continuing to output the primary switching state quantity SWS1 from the current point in time, so the secondary switching state quantity SWS2 is output from the switching calculation unit 131E as the next switching state quantity NextSWS.

[0217] In this way, the immediate switching candidate calculator 54 and the associated allowable reaching calculator 51 are not executed at each calculation cycle, but are executed only when the primary duration Tsw1, which is the duration of the primary switching state quantity calculated by the allowable reaching calculator 61, falls within a set time range. This reduces the calculation load compared to the switching calculation method in embodiment 1.

[0218] Furthermore, by setting the calculation period of the immediate switching candidate calculator 54 and the associated allowable reach calculator 51 to be shorter than the calculation period of the allowable reach calculator 61, the influence of calculation errors that depend on the frequency or amplitude value of the voltage command integral value Pref that occurs during the switching calculation of embodiment 4 is reduced.

[0219] Next, the control operation of the power conversion device 100E according to the sixth embodiment will be described in detail below with reference to Figures 34A, 34B, and 34C. Figures 34A, 34B, and 34C are flowcharts showing an example of operation of the power conversion device according to the sixth embodiment, with Figure 34A showing the first half of the flowchart showing the example of operation of the power conversion device according to the sixth embodiment, Figure 34B showing the middle half of the flowchart showing the example of operation of the power conversion device according to the sixth embodiment, and Figure 34C showing the second half of the flowchart showing the example of operation of the power conversion device according to the sixth embodiment.

[0220] First, the same processing as in the first and fourth embodiments is performed. The voltage output calculation unit 11 calculates the multiphase voltage output value Vout based on the switching state quantity SWS and FIG. 5 , and the integral value calculation unit 12 integrates the multiphase voltage command value Vref and the multiphase voltage output value Vout, respectively, to calculate the voltage command integral value Vref and the voltage output integral value Vout.

[0221] Next, the same processing as in the fourth embodiment is performed to output the primary switching state quantity SWS1, the secondary switching state quantity SWS2, and the primary duration Tsw1 and secondary duration Tsw2 corresponding to each switching state quantity. A predetermined calculation is performed based on all the calculated primary and secondary switching state quantities and primary and secondary durations to calculate an evaluation value J for all combinations of the switching state quantities and durations, and the combination that gives the smallest evaluation value J is calculated.

[0222] In the combination of the smallest primary switching state quantity SWS1 and secondary switching state quantity SWS2 and the smallest primary duration time Tsw1 and secondary duration time Tsw2, if the primary duration time Tsw1 is shorter than a set time, the same processing as in embodiment 1 is executed to recalculate the primary and secondary switching state quantities and the duration times.

[0223] Then, based on the initial switching data DATASW0, a primary duration Tsw1 is calculated, which is the duration until the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref when the primary switching state quantity SWS1 continues to be output, and a secondary duration Tsw2 is calculated, which is the duration until the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref when the secondary switching state quantity SWS2 continues to be output after switching to the secondary switching state quantity SWS2.

[0224] Based on all the calculated combinations of the primary and secondary switching state quantities and their durations, an evaluation value J for all combinations is calculated. Among the calculated evaluation values ​​J, the combination that gives the smallest evaluation value J is calculated.

[0225] If the smallest evaluation value J is a combination of the primary switching state quantity SWS1, the secondary switching state quantity SWS2, the primary duration Tsw1 and the secondary duration Tsw2 calculated by the immediate switching candidate calculator 54 of embodiment 1 and the associated allowable reaching calculator 51, the secondary switching state quantity SWS2 is output as the next switching state quantity NextSWS.

[0226] If the smallest evaluation value J is the result of calculation by continuing to output the primary switching state quantity SWS1 until the voltage output integral value Pout reaches the allowable limit of the allowable range ΔPref, the primary switching state quantity SWS1 is output as the next switching state quantity NextSWS.

[0227] The power conversion unit 1 converts the DC power of the DC power supply 2 into AC power based on the switching state quantity SWS determined by the switching determination unit 13E, and outputs the AC power to the load 3. The load 3 is driven and controlled by the AC power output from the power conversion unit 1.

[0228] As explained above, the sixth embodiment is configured by combining the immediate switching candidate calculator 54 and the associated allowable arrival calculator 51 in the first embodiment, and the allowable switching candidate calculator 60 and the allowable arrival calculator 61 in the fourth embodiment.

[0229] The calculation cycle of the control block of embodiment 1 and the calculation cycle of the control block of embodiment 4 can be set separately, and by setting the calculation cycle of the control block of embodiment 4 to be longer, embodiment 6 can be executed with the long calculation cycle of embodiment 4, and the effect of reducing switching loss SWloss can be achieved even when implemented in an inexpensive microcomputer, and the short calculation cycle of embodiment 1 can increase the resolution of the duration Tsw of the switching state quantity, and can reduce harmonic components generated in the load 3.

[0230] Furthermore, by calculating the point at which the switching state quantity SWS switches according to the first embodiment, it is possible to calculate the point at which the switching state quantity is switched with greater accuracy than the calculation according to the fourth embodiment, thereby realizing further reduction of the harmonic components generated in the load 3.

[0231] Seventh Embodiment A power conversion device 100F according to a seventh embodiment will be described below with reference to Fig. 35. Fig. 35 is a block diagram showing the configuration of a power conversion device 100F according to the seventh embodiment.

[0232] As shown in FIG. 35 , a power conversion device 100F according to embodiment 7 differs from embodiment 6 in that it replaces the load 3 with a rotating electric machine 4, includes a current detection unit 15 between the power conversion unit 1 and the rotating electric machine 4, and a bus voltage detection unit 14 in the power conversion unit 1, and further includes a harmonic processing unit 17 that calculates a harmonic current Ithd based on the detected current value Iuvw detected by the current detection unit 15, a harmonic current controller 18 that calculates a set value ΔP of the allowable range based on the harmonic current command value Ithdref and the harmonic current Ithd, a low-frequency extraction unit 16 that calculates a current low-frequency value Ifund based on the detected current value Iuvw, and a current controller 19 that calculates a multi-phase voltage command value Vref based on the current command value Iref and the current low-frequency value Ifund.

[0233] Next, the functions of the bus voltage detection unit 14, current detection unit 15, harmonic processing unit 17, harmonic current controller 18, low-frequency extraction unit 16, and current controller 19 in embodiment 7, which are differences from embodiment 6, will be explained below.

[0234] The bus voltage detection unit 14 detects the bus voltage Vdc in the power conversion unit 1. The voltage output calculation unit 11F calculates a multiphase voltage output value Vout based on the switching state quantity SWS output by the switching determination unit 13F and the bus voltage Vdc detected by the bus voltage detection unit 14. The current detection unit 15 detects a detected current value Iuvw flowing between the power conversion unit 1 and the rotating electric machine 4. The harmonic processing unit 17 calculates a harmonic current Ithd based on two or more detected current values ​​Iuvw. Here, the harmonic current Ithd is calculated by, for example, calculating data that quantifies harmonic components contained in the current, or current spectrum data expressed on a frequency axis.

[0235] The harmonic current controller 18 calculates a set value ΔP of the allowable range based on the harmonic current command value Ithdref and the harmonic current Ithd. The method of calculating the harmonic current Ithd and the set value ΔP of the allowable range will be described in detail later.

[0236] The low-frequency extraction unit 16 calculates a low-frequency current value Ifund based on two or more detected current values ​​Iuvw. Here, the low-frequency current value Ifund is the fundamental wave of the current. The current controller 19 calculates a multi-phase voltage command value Vref based on the current command value Iref and the low-frequency current value Ifund. The method for calculating the low-frequency current value will be described in detail later.

[0237] FIG. 36 shows a case where the harmonic current Ithd is calculated by the harmonic processor 17 based on one current cycle of the current waveform drawn from two or more detected current values ​​Iuvw. A fast Fourier transform (FFT) is applied to the time-axis current waveform in FIG. 36 to calculate the frequency-axis current spectrum. The frequency-axis current spectrum is calculated from the fundamental wave and harmonics of the current waveform. The harmonic current Ithd corresponds to the harmonics in FIG. 36.

[0238] 36, whether the harmonics are expressed as components of each order, as the sum of the harmonics of each order, or as the ratio of the harmonics to the fundamental wave can be changed depending on the harmonic current command value Ithdref. For example, if the harmonic current command value Ithdref is given as the ratio of the harmonics to the fundamental wave, the harmonic current Ithd is also calculated from the ratio of the harmonics to the fundamental wave in the current spectrum on the frequency axis.

[0239] 36 may be used as the current low frequency value Ifund. The set value ΔP of the allowable range is adjusted so that there is no difference between the harmonic current command value Ithdref and the harmonic current Ithd.

[0240] 37 shows a case where the low-frequency current value Ifund is calculated based on two or more detected current values ​​Iuvw by utilizing current oversampling in the low-frequency extraction unit 16. Here, current oversampling means detecting the current at a cycle shorter than the normal calculation cycle.

[0241] As can be seen from Fig. 37, without current oversampling, it is difficult to calculate the current fundamental as the low-frequency current value Ifund from the detected current value Iuvw. In contrast, with current oversampling in Fig. 37, the current is detected at short intervals and the low-frequency current value Ifund is calculated by averaging at regular intervals, so that a value close to the current fundamental can be obtained as the low-frequency current value Ifund from the detected current value Iuvw.

[0242] Fig. 38 is a diagram showing a hardware configuration for realizing a power conversion device 100F according to embodiment 7. Compared with the power conversion devices according to embodiments 1 to 6, the hardware configuration diagram of the power conversion device 100F according to embodiment 7 differs in that it further includes a bus voltage detection unit 14 and a current detection unit 15. As shown in Fig. 38, the names of the components of the control device 10F are different from those of embodiments 1 to 6.

[0243] The bus voltage detection unit 14 is a mechanism that measures the voltage difference between the positive side (+) and negative side (-) of the DC power supply to detect the bus voltage Vdc. The current detection unit 15 detects the detected current value Iuvw for three phases output from the power conversion unit to the rotating electric machine. Here, any current detector, such as a CT (Current Transformer) detector or a shunt resistor, may be used for the current detection unit 15. It is also possible to use a current detector that detects two of the three-phase currents and calculates the current for the remaining one phase. Alternatively, a single-shunt current detection method that reconstructs three-phase AC current values ​​using a single current detector may be used.

[0244] Next, the control operation in the power conversion device 100F of this seventh embodiment will be described in detail below with reference to Figures 39A, 39B, and 39C. Figures 39A, 39B, and 39C are flowcharts illustrating the control operation in the power conversion device 100F, with Figure 39A being a flowchart (first half) illustrating an example of the control operation of the power conversion device according to the seventh embodiment, Figure 39B being a flowchart (middle half) illustrating an example of the control operation of the power conversion device according to the seventh embodiment, and Figure 39C being a flowchart (last half) illustrating an example of the control operation of the power conversion device according to the seventh embodiment.

[0245] First, the current detection unit 15 measures the current flowing through the rotating electric machine 4 as a detected current value Iuvw. At this time, the detected current value Iuvw is measured a specified number of times. Next, based on the detected current values ​​Iuvw at two or more points, the harmonic processing unit 17 and the low-frequency extraction unit 16 calculate the harmonic current Ithd and the low-frequency current value Ifund, respectively.

[0246] The voltage output calculation unit 11F calculates a multiphase voltage output value Vout based on the bus voltage Vdc detected by the bus voltage detection unit 14, the switching state quantity SWS output by the switching calculation unit 131F, and the bus voltage Vdc detected by the bus voltage detection unit 14, the switching state quantity SWS output by the switching calculation unit 131F, and the multiphase voltage output value Vout based on FIG.

[0247] Thereafter, processing is performed in the same procedure as in the sixth embodiment, the switching determination unit 13F outputs the next switching state quantity SWS, and the power conversion unit 1 converts DC power into AC power using the determined switching state quantity SWS to drive and control the rotary electric machine 4. Note that offset amounts may be adjusted for each of the multiphase voltage command value Vref calculated by the integral value calculation unit 12, the multiphase voltage command integral value Pref obtained by integrating the multiphase voltage output value Vout, and the multiphase voltage output integral value Pout, so that the neutral point is always zero.

[0248] As described above, compared to the first to sixth embodiments, the power conversion device 100F of the seventh embodiment can control the harmonic current Ithd of the rotating electric machine 4 according to a command value, and therefore can obtain a desired harmonic current Ithd under various operating conditions. More specifically, when evaluating a combination of the predicted calculated switching state quantity and duration, it is possible to select a combination of the switching state quantity and duration that minimizes switching of the switching state quantity of the power conversion unit and minimizes loss during switching based on the number of switching changes that occur in the upper and lower arms of the power conversion unit when the switching state quantity transitions and the duration for which the switching state quantity is maintained.

[0249] Eighth Embodiment A power conversion device 100G according to an eighth embodiment will be described below with reference to Fig. 40. Fig. 40 is a block diagram showing the configuration of a power conversion device 100G according to the eighth embodiment.

[0250] 40 , a power conversion device 100G according to the eighth embodiment differs from the sixth embodiment in that a switching calculation unit 131E is replaced with a switching table 21. Therefore, a switching determination unit 13G and a control device 10G have configurations different from those of the corresponding parts of the sixth embodiment.

[0251] Next, the switching table 21 of the eighth embodiment, which is different from the sixth embodiment, will be described below. The switching table 21 is a table storing switching state variables SWS for determining the switching state variables SWS of the power conversion unit 1 according to the drive state of the load. The switching table 21 outputs a setting signal SetSW based on the voltage command integral value Pref and the voltage output integral value Pout calculated by the integral value calculation unit 12. At this time, the switching table 21 may store switching tables (e.g., switching tables for one electrical angle cycle) for several conditions assuming the drive state of the load so as to realize a desired drive state. Furthermore, the switching table 21 may refer to the switching state variable SWS based on phase information of the voltage command integral value Pref.

[0252] It is also possible to store combinations of switching state quantities for one electrical angle period calculated by simulation analysis using the calculation methods of the switching state quantities SWS according to the first to sixth embodiments, and generate the switching table 21 from these combinations.

[0253] In the eighth embodiment, a method for calculating the switching state quantity SWS will be described, focusing on the time integral value SUMerr of the deviation (a value obtained by integrating the absolute value of the deviation over time), which is a value obtained by integrating the deviation between the voltage command integral value Pref and the voltage output integral value Pout over time. The eighth embodiment will also describe a processing procedure for generating a combination of the switching state quantities SWS (for one electrical angle cycle) as the switching table 21 and driving the load 3.

[0254] FIG. 41 is a diagram illustrating the time integral value SUMerr of the deviation, which is the value obtained by integrating the deviation between the voltage command integral value Pref and the voltage output integral value Pout over time when calculating a combination of switching state quantities SWS in a certain section. In the vector locus of FIG. 41 , which is drawn from the vector of the voltage command integral value Pref and the vector of the voltage output integral value Pout, the time integral value SUMerr of the deviation is the sum of the areas drawn by the deviation between the voltage command integral value Pref and the voltage output integral value Pout. A limit value ΔParea (hereinafter abbreviated as limit value ΔParea) of the time integral value of the deviation SUMerr is set for this time integral value SUMerr, and all combinations of switching state quantities SWS in a certain section where the time integral value SUMerr of the deviation does not exceed the limit value ΔParea are calculated. Of the calculated combinations of switching state quantities SWS, the combination of switching state quantities SWS that results in the fewest number of switching changes is selected.

[0255] Next, a method for generating the switching table 21 in the power conversion device 100G according to the eighth embodiment will be described in detail below with reference to Fig. 42. Fig. 42 is a flowchart illustrating a method for generating the switching table 21 in the power conversion device 100G.

[0256] First, the multiphase voltage output value Vout is calculated based on the switching state quantities SWS. Then, the set multiphase voltage command value Vref and the calculated multiphase voltage output value Vout are respectively integrated over time to calculate a voltage command integral value Pref and a voltage output integral value Pout. Combinations of the switching state quantities SWS for one electrical angle phase cycle are calculated based on the calculated voltage command integral value Pref and voltage output integral value Pout. During the calculation, all combinations of the switching state quantities SWS for which the temporal integration value SUMerr of the deviation between the voltage command integral value Pref and the voltage output integral value Pout for one electrical angle cycle is equal to or less than the limit value ΔParea are calculated.

[0257] Thereafter, from among the calculated combinations of the switching state quantities SWS, the combination with the smallest number of switching operations is selected, and this combination of the switching state quantities SWS is stored as a combination for one electrical angle cycle. This combination for one electrical angle cycle becomes the switching table 21. At this time, combinations for several driving conditions (such as the frequency at which the load is driven) may be generated as combinations of the switching state quantities SWS for one electrical angle cycle, and these may be used as the switching table 21.

[0258] The method for generating the switching table 21 in the power conversion device 100G of embodiment 8 has been described. A method for controlling the load 3 using the generated switching table 21 will now be described in detail with reference to Fig. 43. Fig. 43 is a flowchart illustrating a method for controlling the load 3 using the switching table 21 in the power conversion device 100G.

[0259] First, the multiphase voltage output value Vout is calculated based on the switching state quantity SWS. Then, the set multiphase voltage command value Vref and the calculated multiphase voltage output value Vout are respectively integrated over time to calculate the voltage command integral value Pref and the voltage output integral value Pout.

[0260] Based on the calculated voltage command integral value Pref and voltage output integral value Pout, the next switching state quantity SWS is referenced from the switching table 21 created in advance as shown in Fig. 42. Based on the switching state quantity SWS referenced from the switching table 21, the power conversion unit 1 converts DC power into AC power to control the load 3.

[0261] It should be noted that when referring to the switching state quantities SWS from the switching table 21, it is possible to generate a combination of the switching state quantities SWS corresponding to a different lower frequency by appropriately inserting a zero voltage vector into the combination of the switching state quantities SWS generated for a certain frequency, thereby stopping the rotation of the vector of the voltage output integral value Pout.

[0262] As described above, in comparison with the first to sixth embodiments, the power conversion device 100G of the eighth embodiment generates, as the switching table 21, combinations of switching state quantities SWS for one electrical angle cycle calculated in advance by simulation analysis, and controls the load 3, and therefore can reduce the calculation time required to calculate the switching state quantities in real time.

[0263] Furthermore, in the eighth embodiment, a method for calculating combinations of switching state quantities SWS has been described, focusing on the temporal integrated value SUMerr of the deviation, which is a value obtained by integrating over time the deviation between the voltage command integrated value Pref and the voltage output integrated value Pout. However, the switching table 21 may be generated by the method for calculating the switching state quantities SWS as in the first to sixth embodiments, or the method for calculating the switching state quantities SWS of the first to sixth embodiments may be combined with the method for calculating the switching state quantities SWS of the eighth embodiment, so that the temporal integrated value SUMerr of the deviation in a certain section is set to be equal to or less than the limit value ΔParea, and combinations of the switching state quantities SWS may be calculated by the methods of the first to sixth embodiments.

[0264] In addition, it goes without saying that in the configuration of embodiment 7, by using the method of calculating the switching state quantity SWS in the method of embodiment 7, a switching table 21 can be generated in the same procedure as in embodiment 8, and the rotating electric machine 4 can be driven and controlled using the switching table 21 instead of the switching calculation unit 131F.

[0265] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0266] 1 Power conversion unit, 2 DC power supply, 3 Load, 4 Rotating electric machine, 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G Control device, 11, 11F Voltage output calculation unit, 12 Integral value calculation unit, 13, 13A, 13B, 13C, 13D, 13E, 13F, 13G Switching decision unit, 131, 131A, 131C, 131D, 131E, 131F Switching calculation unit, 132 Switching output unit, 14 Bus voltage detection unit, 15 Current detection unit, 16 Low frequency extraction unit, 17 Harmonic processing unit, 18 Harmonic current controller, 19 Current controller, 20 Trained model, 21 Switching table, 40 Processor, 41 Storage device, 42 Control program, 43 Processed data, 50 Data integrator, 51 Allowable arrival calculator, 52 Switching candidate calculator, 53 One-cycle calculator, 54 Instantaneous switching candidate calculator, 55, 55A, 55B, 55C, 55D, 55E Switching selector, 56 Switching memory, 57 Secondary switching candidate data generator, 58 Third switching candidate data generator, 59 Allowable arrival switching candidate calculator, 60 Within-allowable switching candidate calculator, 61 Within-allowable arrival calculator, 62, 62D Switching update determiner, 63 Third switching candidate calculator, 70 Learning unit, 71 Learning data, 72 Teacher data acquisition unit, 73 Input data acquisition unit, 74 Label data acquisition unit, 75 Teacher input data, 76 Teacher label data, 80 Machine learning device, 81 Processor, 82 Storage device, 83 RAM, 84 HDD, 85 Learning program, 86 Teacher data, 87 Learning result, 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G power conversion device, D diode, SW0 to SW8 switching state index, SWS switching state quantity, SWS switching state quantity, NextSWS next switching state quantity, Tsw duration, Tswsum duration total value, Vref voltage command value (multi-phase voltage command value), Vout voltage output value (multi-phase voltage output value), Vu u-phase voltage, Vv v-phase voltage, Vw w-phase voltage, Vu' u'-phase voltage, Vv' v'-phase voltage, Vw' w'-phase voltage, Pref voltage command integral value (multi-phase voltage command integral value), Pout voltage output integral value (multi-phase voltage output integral value), ΔP tolerance range setting value,ΔPref: Tolerance range in which the voltage command integral value Pref is set to the tolerance setting value ΔP, ΔParea: Limit value for the time integral value of the deviation, SetSW: Setting signal, Q1 to Q6: Switching element, Vdc: Bus voltage, SWcount: Number of switching changes, SWcountsum: Total number of switching changes, SWloss: Switching loss, THD: Total harmonic distortion, Ifund: Current low frequency value, Iref: Current command value, Ithd: Harmonic current, Ithdref: Harmonic current command value, Iuvw: Detected current value, J: Evaluation value, DATASW0 to DATASW4, DATASWN: Switching data, PreDATASW2 to PreDATASW4: Switching candidate data, SUMerr: Time integral value of the deviation, Tbc, Tcd Duration, TempDATASW2 switching temporary data, Tswsum duration total value,

Claims

1. A power conversion unit having multiple switching elements, which converts DC power to AC power and supplies it to a load according to the switching state of each switching element. A voltage output calculation unit calculates the AC voltage output value supplied from the power conversion unit based on the switching state quantity. An integral value calculation unit that calculates a voltage command integral value by integrating the AC voltage command value and also calculates a voltage output integral value by integrating the AC voltage output value calculated by the voltage output calculation unit. A switching determination unit calculates and outputs the switching state quantity of the power conversion unit based on the voltage command integral value, the voltage output integral value, and the tolerance range setting value, so that the tolerance range setting value is set to the tolerance boundary of the tolerance range, and before the voltage output integral value reaches the tolerance boundary of the tolerance range within the tolerance range. A power conversion device characterized by being equipped with the following features.

2. The power conversion device according to claim 1, wherein the switching determination unit comprises a switching calculation unit that outputs a setting signal for determining the switching state amount of the power conversion unit based on the voltage command integral value, the voltage output integral value, and an allowable range set based on the voltage command integral value, and a switching output unit that determines the switching state amount of the power conversion unit based on the setting signal.

3. The power conversion device according to claim 2, characterized in that the switching calculation unit outputs the switching state amount of the power conversion unit as the setting signal.

4. The switching calculation unit performs calculations at predetermined intervals, A data integrator receives the voltage output integral value, the voltage command integral value, and a primary switching state quantity which is a switching state quantity during calculation, and outputs initial switching data which is a set of the voltage output integral value, the voltage command integral value, and the primary switching state quantity. An allowable reach calculator that, when the initial switching data is input and the primary switching state is maintained, calculates the duration until the voltage output integral value reaches the allowable boundary, the voltage command integral value and the voltage output integral value at the time the allowable boundary is reached, and outputs primary switching data consisting of the primary switching state, the duration of the primary switching state, the voltage command integral value and the voltage output integral value at the time the allowable boundary is reached, with respect to the allowable range set based on the voltage command integral value, and outputs primary switching data consisting of the primary switching state, the duration of the primary switching state, and the voltage command integral value and voltage output integral value at the time the allowable boundary is reached. A switching candidate calculator that takes the primary switching data as input, selects a plurality of secondary switching state quantity candidates, which are the next switching state quantities that keep the voltage output integral value within an acceptable range, and outputs a plurality of secondary switching candidate data obtained by adding each of the plurality of secondary switching state quantity candidates to the primary switching data, A one-period calculator that receives the initial switching data and calculates the duration of the primary switching state, the voltage command integral value and the voltage output integral value after one calculation period, when the primary switching state is maintained for one calculation period, and outputs primary switching data consisting of the primary switching state, the duration of the primary switching state, the voltage command integral value and the voltage output integral value after one calculation period, The system includes an immediate switching candidate calculator that, upon receiving the primary switching data and changing the switching state quantity during the next calculation, selects one or more secondary switching state quantity candidates that will keep the voltage output integral value within an acceptable range, and outputs one or more secondary switching candidate data by adding these secondary switching state quantity candidates to the primary switching data. The aforementioned allowable reach calculator, switching candidate calculator, one-cycle calculator, and immediate switching candidate calculator constitute a secondary switching candidate data generator, and also, Multiple secondary switching candidate data outputs from the secondary switching candidate data generator are each input, and when the switching state quantity is switched to a secondary switching state quantity candidate, the duration until the voltage output integral value reaches the allowable boundary, the voltage command integral value and voltage output integral value at the time the allowable boundary is reached are calculated based on the voltage command integral value set in the allowable range, and multiple allowable reach calculation units output secondary switching data by adding the duration of secondary switching, the voltage command integral value and voltage output integral value at the time the allowable boundary is reached to the secondary switching candidate data. A switching selector receives secondary switching data output from multiple of the aforementioned allowable reach calculators, evaluates the secondary switching data using a predetermined calculation, and outputs the next switching state quantity. A switching memory that receives the next switching state quantity as input, stores the next switching state quantity, and outputs it as the primary switching state quantity for the next calculation, The power conversion device according to claim 2 or 3, characterized by comprising:

5. The switching calculation unit performs calculations at predetermined intervals, and A data integrator receives the voltage output integral value, the voltage command integral value, and a primary switching state quantity which is a switching state quantity during calculation, and outputs initial switching data which is a set of the voltage output integral value, the voltage command integral value, and the primary switching state quantity. A secondary switching candidate data generator receives the initial switching data and outputs a plurality of secondary switching candidate data sets, each set consisting of the primary switching state, the duration of the primary switching state, and the voltage command integral value and voltage output integral value at the point in time when the primary switching state is switched to the next switching state, which is the secondary switching state. A tertiary switching candidate data generator receives multiple secondary switching candidate data as input and outputs multiple tertiary switching candidate data, each consisting of a secondary switching state quantity, the duration of the secondary switching state quantity, and the voltage command integral value and voltage output integral value at the point in time when the secondary switching state quantity is switched to the next switching state quantity, the tertiary switching state quantity. Multiple tolerance-reach calculators receive a number of tertiary switching candidate data as inputs. When the switching state is switched to a candidate tertiary switching state, they calculate the duration until the voltage output integral value reaches the tolerance boundary, the voltage command integral value and voltage output integral value at the time the tolerance boundary is reached, and output tertiary switching data by adding the duration of tertiary switching, the voltage command integral value and voltage output integral value at the time the tolerance boundary is reached to the tertiary switching candidate data. A switching selector receives tertiary switching data output by multiple allowable reach calculators, evaluates the tertiary switching data using a predetermined calculation, and outputs the next switching state quantity. A switching memory that receives the next switching state quantity as input, stores the next switching state quantity, and outputs it as the primary switching state quantity for the next calculation. The power conversion device according to claim 2 or 3, characterized by comprising:

6. The switching calculation unit performs calculations at predetermined intervals, A data integrator receives the voltage output integral value, the voltage command integral value, and a primary switching state quantity which is a switching state quantity during calculation, and outputs initial switching data which is a set of the voltage output integral value, the voltage command integral value, and the primary switching state quantity. A secondary switching candidate data generator receives the initial switching data and outputs a plurality of secondary switching candidate data sets, each set consisting of the primary switching state, the duration of the primary switching state, and the voltage command integral value and voltage output integral value at the point in time when the primary switching state is switched to the next switching state, which is the secondary switching state. A tertiary switching candidate data generator receives multiple secondary switching candidate data as input and outputs multiple tertiary switching candidate data, each consisting of a secondary switching state quantity, the duration of the secondary switching state quantity, and the voltage command integral value and voltage output integral value at the point in time when the secondary switching state quantity is switched to the next switching state quantity, which is the tertiary switching state quantity. The above-mentioned secondary switching candidate data generator, and the above-mentioned tertiary switching candidate data generator, which performs the same procedure as the above-mentioned tertiary switching candidate data generator to generate Nth-order switching candidate data for N being an integer of 4 or more, Multiple tolerance-reach calculators receive the Nth-order switching candidate data, and when the switching state is switched to the Nth-order switching state candidate, they calculate the duration until the voltage output integral value reaches the tolerance boundary, the voltage command integral value at the time the tolerance boundary is reached, and the voltage output integral value, and output Nth-order switching data by adding the duration of the Nth-order switching, the voltage command integral value at the time the tolerance boundary is reached, and the voltage output integral value to the Nth-order switching candidate data. A switching selector receives Nth-order switching data output by multiple allowable reach calculators, evaluates the Nth-order switching data using a predetermined calculation, and outputs the next switching state quantity. A switching memory that receives the next switching state quantity as input, stores the next switching state quantity, and outputs it as the primary switching state quantity for the next calculation. The power conversion device according to claim 2 or 3, characterized by comprising:

7. The switching calculation unit outputs the switching state quantity of the power conversion unit and the duration of the switching state quantity as the setting signal. The power conversion device according to claim 2 or 3.

8. The switching calculation unit performs calculations at predetermined intervals, A data integrator receives the voltage output integral value, the voltage command integral value, and a primary switching state quantity which is a switching state quantity during calculation, and outputs initial switching data which is a set of the voltage output integral value, the voltage command integral value, and the primary switching state quantity. An allowable reach switching candidate calculator receives the initial switching data, and when the voltage output integral value of each phase reaches the allowable boundary with respect to the allowable range set based on the voltage command integral value, it selects a plurality of secondary switching state quantity candidates, which are the next switching state quantities that can keep the voltage output integral value within the allowable range, and outputs a plurality of secondary switching candidate data obtained by adding each of the plurality of secondary switching state quantity candidates to the initial switching data. A switching candidate calculator that receives the initial switching data and, when the switching state quantity is changed before the voltage output integral value for each phase reaches the tolerance boundary with respect to the tolerance range set based on the voltage command integral value, selects one or more secondary switching state quantity candidates that are the next switching state quantities that can keep the voltage output integral value within the tolerance range, and outputs a plurality of secondary switching candidate data by adding one or more of the secondary switching state quantity candidates to the initial switching data, Multiple secondary switching candidate data outputs from the aforementioned allowable reach switching candidate calculator are each input, and the primary and secondary durations until the operation of the primary and secondary switching states reaches the allowable boundary, the voltage command integral value and voltage output integral value at the time the primary and secondary switching reach the allowable boundary are calculated, and multiple allowable reach calculators output secondary switching data by adding the primary and secondary switching durations, the voltage command integral value and voltage output integral value at the time the allowable boundary is reached to the secondary switching candidate data. Multiple tolerance-reach calculators receive secondary switching candidate data output by the tolerance-reach calculator, and when the operation in the primary switching state is before reaching the tolerance boundary, and the operation in the secondary switching state is until reaching the tolerance boundary, they calculate the primary duration that maximizes the sum of the primary and secondary durations, calculate the secondary duration based on the calculated primary duration, and calculate the voltage command integral value and voltage output integral value at the time the tolerance boundary for primary and secondary switching is reached, respectively, and output secondary switching data by adding the primary and secondary switching durations, the voltage command integral value and voltage output integral value at the time the tolerance boundary is reached to the secondary switching candidate data. A switching selector receives multiple secondary switching data as input, evaluates the multiple secondary switching data using a predetermined calculation, selects a primary duration, a secondary switching state quantity, and outputs the secondary duration together with the primary switching state quantity. A switching update determination device that receives a secondary switching state quantity and a primary duration as input, and updates the output primary switching state quantity with the input secondary switching state quantity if the primary duration is shorter than the calculation period. The power conversion device according to claim 2 or 3, characterized by comprising:

9. The switching calculation unit performs calculations at predetermined intervals, and A data integrator receives the voltage output integral value, the voltage command integral value, and a primary switching state quantity which is a switching state quantity during calculation, and outputs initial switching data which is a set of the voltage output integral value, the voltage command integral value, and the primary switching state quantity. An allowable reach switching candidate calculator receives the initial switching data, and when the voltage output integral value of each phase reaches the allowable boundary with respect to the allowable range set based on the voltage command integral value, it selects a plurality of secondary switching state quantity candidates, which are the next switching state quantities that can keep the voltage output integral value within the allowable range, and outputs a plurality of secondary switching candidate data by adding these secondary switching state quantity candidates to the initial switching data. A switching candidate calculator that receives the initial switching data and, when the switching state quantity is changed before the voltage output integral value for each phase reaches the tolerance boundary with respect to the tolerance range set based on the voltage command integral value, selects one or more secondary switching state quantity candidates that are the next switching state quantities that can keep the voltage output integral value within the tolerance range, and outputs a plurality of secondary switching candidate data by adding these secondary switching state quantity candidates to the initial switching data. Multiple secondary switching candidate data outputs from the aforementioned allowable reach switching candidate calculator are each input, and the primary and secondary durations until the operation of the primary and secondary switching states reaches the allowable boundary, the voltage command integral value and voltage output integral value at the time the primary and secondary switching reach the allowable boundary are calculated, and multiple allowable reach calculators output secondary switching data by adding the primary and secondary switching durations, the voltage command integral value and voltage output integral value at the time the allowable boundary is reached to the secondary switching candidate data. Multiple tolerance-reach calculators receive secondary switching candidate data output by the tolerance-reach calculator, and when the operation in the primary switching state is before reaching the tolerance boundary, and the operation in the secondary switching state is until reaching the tolerance boundary, they calculate the primary duration that maximizes the sum of the primary and secondary durations, calculate the secondary duration based on the calculated primary duration, and at the same time calculate the voltage command integral value and voltage output integral value at the time the tolerance boundary for primary and secondary switching is reached, respectively, and output secondary switching data by adding the primary and secondary switching durations, the voltage command integral value and voltage output integral value at the time the tolerance boundary is reached to the secondary switching candidate data. A tertiary switching candidate calculator that, based on the secondary switching data, uses the secondary switching state quantities to select a plurality of tertiary switching state quantity candidates, which are the next switching state quantities that allow the voltage output integral value to remain within the allowable range set based on the voltage command integral value when the voltage output integral value of each phase reaches the allowable boundary, and outputs a plurality of tertiary switching candidate data by adding these tertiary switching state quantity candidates to the secondary switching data, respectively. A second allowable reach switching candidate calculator inputs the tertiary switching candidate data, and when the voltage output integral value of each phase reaches the allowable boundary with respect to the allowable range set based on the voltage command integral value, it selects a plurality of quaternary switching state quantity candidates, which are the next switching state quantities that can keep the voltage output integral value within the allowable range, and outputs a plurality of quaternary switching candidate data by adding these quaternary switching state quantity candidates to the tertiary switching candidate data. Multiple second tolerance-reach calculation units input the tertiary switching candidate data, and when the operation in the tertiary switching state is before reaching the tolerance boundary, and the operation in the quaternary switching state is until reaching the tolerance boundary, calculate the tertiary duration that maximizes the sum of the durations from the tertiary to the quaternary, calculate the quaternary duration based on the calculated tertiary duration, calculate the voltage command integral value and voltage output integral value at the time the tolerance boundary of the tertiary and quaternary switching is reached, respectively, and output quaternary switching data by adding the duration of the tertiary and quaternary switching, the voltage command integral value and voltage output integral value at the time the tolerance boundary is reached to the tertiary switching candidate data. A switching selector receives input from the second allowable reach switching candidate calculator and the second allowable reach calculator, evaluates the multiple fourth-order switching data using a predetermined calculation, outputs first- to fourth-order switching state quantities, and outputs the durations of the first to fourth orders together. A switching update determination device receives the duration of the first to third switching states and the switching state quantities of the second to fourth switching states as inputs, and updates the output primary switching state quantity to one of the input secondary to fourth switching state quantities under predetermined conditions. The power conversion device according to claim 2 or 3, characterized by comprising:

10. The switching calculation unit performs calculations at predetermined intervals, A data integrator receives the voltage output integral value, the voltage command integral value, and a primary switching state quantity which is a switching state quantity during calculation, and outputs initial switching data which is a set of the voltage output integral value, the voltage command integral value, and the primary switching state quantity. An allowable reach calculator that, when the initial switching data is input and the primary switching state is maintained, calculates the duration until the voltage output integral value reaches the allowable boundary, the voltage command integral value and the voltage output integral value at the time the allowable boundary is reached, and outputs primary switching data consisting of the primary switching state, the duration of the primary switching state, the voltage command integral value and the voltage output integral value at the time the allowable boundary is reached, with respect to the allowable range set based on the voltage command integral value, and outputs primary switching data. A switching candidate calculator that takes the primary switching data as input, selects a plurality of secondary switching state quantity candidates that are the next switching state quantities that keep the voltage output integral value within an acceptable range, and outputs a plurality of secondary switching candidate data by adding each of these secondary switching state quantity candidates to the primary switching data, A switching candidate calculator that receives the initial switching data and, when the switching state quantity is changed before the voltage output integral value for each phase reaches the tolerance boundary with respect to the tolerance range set based on the voltage command integral value, selects one or more secondary switching state quantity candidates that are the next switching state quantities that can keep the voltage output integral value within the tolerance range, and outputs a plurality of secondary switching candidate data by adding these secondary switching state quantity candidates to the initial switching data. Multiple tolerance-reach calculators receive secondary switching candidate data output by the tolerance-reach calculator, and when the operation in the primary switching state is before reaching the tolerance boundary, and the operation in the secondary switching state is until reaching the tolerance boundary, they calculate the primary duration that maximizes the sum of the primary and secondary durations, calculate the secondary duration based on the calculated primary duration, calculate the voltage command integral value and voltage output integral value at the time the tolerance boundary for primary and secondary switching is reached, respectively, and output provisional secondary switching data by adding the durations of primary and secondary switching, the voltage command integral value and voltage output integral value at the end of each switching to the secondary switching candidate data. An immediate switching candidate selector receives multiple secondary switching provisional data output from the allowable reach calculation unit, evaluates the multiple secondary switching provisional data using a predetermined calculation, selects one secondary switching provisional data, outputs the selected data as secondary switching candidate data if the primary duration of the secondary switching provisional data is less than or equal to a predetermined set time, and invalidates the output if the primary duration of the secondary switching provisional data is longer than a predetermined set time. Multiple tolerance-reach calculators receive a plurality of secondary switching candidate data as inputs, and when switching is performed to a secondary switching state candidate, they calculate the duration until the voltage output integral value reaches the tolerance boundary, the voltage command integral value and voltage output integral value at the time the tolerance boundary is reached, and output secondary switching data by adding the duration of secondary switching, the voltage command integral value and voltage output integral value at the time the tolerance boundary is reached to the secondary switching candidate data. A switching selector receives secondary switching data output from multiple of the aforementioned allowable reach calculators, evaluates the secondary switching data using a predetermined calculation, and outputs the next switching state quantity. A switching memory that receives the next switching state quantity as input, stores the next switching state quantity, and outputs it as the primary switching state quantity for the next calculation, The power conversion device according to claim 2 or 3, characterized by comprising:

11. The switching calculation unit either selects the switching state with the longest duration from the plurality of switching state quantities, or, based on the number of switching cycles and duration of each phase of the switching state quantity, it selects the combination of switching state quantity and duration that has the smallest evaluation value, based on an evaluation value obtained from the sum of the number of switching cycles and the sum of the durations of each phase. The power conversion device according to feature 4.

12. The switching determination unit is further equipped with a trained model that has undergone training with training data, using the voltage command integral value, the voltage output integral value, the tolerance range, and the current switching state quantity as input data and the setting signal as label training data. The training model is used instead of the switching calculation unit to calculate the setting signal based on the voltage command integral value, the voltage output integral value, and the tolerance range. The power conversion device according to feature 4.

13. The power conversion device according to claim 2 or 3, characterized in that, instead of the switching determination unit calculating the switching state quantity based on the allowable boundary of the allowable range set for the voltage command integral value and the voltage output integral value, the switching state quantity is calculated such that the time integral value obtained by integrating the deviation between the voltage command integral value and the voltage output integral value over a predetermined interval is less than or equal to a set limit value, or the time integral value satisfies the set limit value and the switching state quantity is calculated within the allowable range before the voltage output integral value reaches the allowable boundary of the allowable range.

14. The power conversion device according to claim 13, characterized in that the switching determination unit outputs a combination of switching states that minimizes the total number of switching cycles of the switching states in the predetermined interval.

15. The power conversion device according to claim 2 or 3, further comprising: a current detection unit for detecting the current flowing through the rotating electric machine as a detected current value; a harmonic processing unit for calculating harmonic current data, which is the harmonic component of the detected current value detected by the current detection unit; a harmonic current controller for calculating a set value of the allowable range based on the harmonic current data calculated by the harmonic processing unit and a harmonic current command value; a low-frequency extraction unit for calculating a low-frequency current value, which is the low-frequency component of the detected current value detected by the current detection unit; and a current controller for calculating an AC voltage command value based on the low-frequency current value calculated by the low-frequency extraction unit and a current command value.

16. The power conversion device according to claim 15, characterized in that the low-frequency extraction unit detects two or more detected current values ​​and calculates the current low-frequency value based on the plurality of detected current values.

17. The power conversion device according to claim 15, characterized in that the harmonic processing unit detects two or more detected current values ​​and calculates the harmonic current data based on the plurality of detected current values.

18. The power conversion device according to claim 2 or 3, characterized in that the switching determination unit calculates based on the voltage command integral value with an adjusted offset amount and the voltage output integral value.

19. The power conversion device according to claim 2 or 3, characterized in that the voltage output calculation unit calculates the AC voltage output value supplied from the power conversion unit based on the DC power supply voltage of the DC power supply and the switching state quantity.

20. The power conversion device according to claim 2 or 3, characterized in that a switching table is created based on the calculation results of the switching state quantities over one electrical angle period calculated by simulation analysis in the switching determination unit, and the setting signal is calculated using the switching table instead of the switching calculation unit.