Rotating machine control device

Abstract

A rotary-machine control device (1) includes a voltage application device (3) and a control device (4) that controls a voltage generation operation by the voltage application device (3). The control device (4) executes switching control for switching an operation mode from asynchronous PWM to synchronous PWM in an arbitrary switching phase. In the switching control, a first asynchronous carrier-wave, which is being used in the asynchronous PWM, is changed to a second asynchronous carrier-wave. The control device (4) calculates a frequency of the second asynchronous carrier-wave in order to change the first asynchronous carrier-wave, which is being used in the asynchronous PWM, to the second asynchronous carrier-wave on the basis of a first phase difference from a reference phase to the switching phase of the first asynchronous carrier-wave. In the switching control, by changing the first asynchronous carrier-wave to the second asynchronous carrier-wave, an instantaneous value of the second asynchronous carrier-wave matches the instantaneous value of the synchronous carrier-wave used in the synchronous PWM mode in the switching phase, and a sign of inclination of the second asynchronous carrier-wave matches a sign of inclination of the synchronous carrier-wave.

Description

[Technical Field]

[0001] The present disclosure relates to a rotating machine control device that controls a rotating machine. [Background technology]

[0002] In order to operate an AC motor (hereinafter referred to as "rotating machine"), which is an example of a rotating machine, at a variable speed, it is necessary to convert the power supplied to the rotating machine into a desired voltage and frequency. An inverter device is used for this process. A typical inverter device is composed of a main circuit using semiconductor switching elements and a controller that controls the semiconductor switching elements. The inverter device obtains the desired frequency and voltage by controlling the on / off of the semiconductor switching elements. PWM (Pulse Width Modulation) control is widely used as a method for switching the semiconductor switching elements.

[0003] The pulses used in PWM control are generated by comparing the command for the voltage to be applied to the rotating machine (hereafter referred to as the "voltage command") with a carrier wave for generating the pulses. A triangular wave, for example, is used as the carrier wave. The higher the carrier frequency, which is the frequency of the carrier wave, the fewer harmonics are contained in the output pulse, and the lower the harmonic loss when applied to the rotating machine. On the other hand, raising the carrier frequency increases the number of switching times of the semiconductor switching element, which increases switching loss and generates heat. For this reason, the upper limit of the carrier frequency is determined from the perspective of thermal design.

[0004] If the carrier frequency is kept constant regardless of the rotating machine's rotation speed, the number of switching operations increases as the rotating machine's rotation speed increases, resulting in heat generation that cannot be tolerated. Therefore, a control method is used in which the carrier frequency is kept constant when the rotating machine's rotation speed is low and is changed in synchronization with the voltage command frequency when the rotating machine's rotation speed is high. A PWM method in which the carrier frequency is not synchronized with the voltage command frequency is called an "asynchronous PWM method," and its operating mode is called an "asynchronous PWM mode." A PWM method in which the carrier frequency is synchronized with the voltage command frequency is called a "synchronous PWM method," and its operating mode is called an "synchronous PWM mode." Some synchronous PWM methods use multiple carrier frequencies to change the number of pulses per voltage command cycle. Typical examples include a "synchronous 15-pulse" method, in which 15 pulses are contained in one voltage command cycle, and a "synchronous 3-pulse" method, in which 3 pulses are contained in one voltage command cycle.

[0005] When switching the operating mode from asynchronous PWM mode to synchronous PWM mode, if the switching process is performed without consideration, current oscillation occurs in the rotating machine. Current oscillation is a phenomenon in which the current flowing through the rotating machine oscillates. When current oscillation occurs in a rotating machine, the rotating machine current, which is the current flowing through the rotating machine, deviates from the allowable current of the semiconductor switching elements, which may damage the semiconductor switching elements. Furthermore, depending on the frequency of the current oscillation, it may violate regulations on current harmonics, which may require the addition of a filter circuit. Furthermore, if the torque of the rotating machine oscillates in proportion to the current oscillation, mechanical vibration and noise of the rotating machine may become a problem.

[0006] Various countermeasures have been taken to prevent current oscillations from occurring when switching between operating modes. For example, Patent Document 1 below discloses a technique for increasing the asynchronous carrier frequency when switching from asynchronous PWM mode to synchronous PWM mode, thereby increasing the frequency deviation from the carrier frequency during synchronous operation, thereby shortening the cycle at which a switchable phase signal is output and reducing the delay time in the switching operation, resulting in a smooth transition to synchronous operation. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 62-141974 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the technology described in Patent Document 1 has a restriction that switching from an asynchronous carrier wave, which is a carrier wave for an asynchronous PWM system, to a synchronous carrier wave, which is a carrier wave for a synchronous PWM system, cannot be performed at any phase other than three points: the peaks, valleys, or zero-crossing points of the asynchronous carrier wave. Due to this restriction, if the timing of the generation process of the asynchronous carrier wave and the timing of the generation process of the synchronous carrier wave fluctuate, the switching from the asynchronous carrier wave to the synchronous carrier wave becomes discontinuous, which could cause an overcurrent to flow in the rotating machine. Furthermore, if continuity of the switching is pursued too much, another problem occurs: the timing of switching from asynchronous PWM mode to synchronous PWM mode is delayed.

[0009] The present disclosure has been made in consideration of the above, and aims to provide a rotating machine control device that can switch from an asynchronous carrier wave to a synchronous carrier wave without any constraints on the phase of the asynchronous carrier wave. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems and achieve the object, a rotating machine control device according to the present disclosure includes a voltage applicator and a controller. The voltage applicator generates a three-phase voltage to be applied to the rotating machine. The controller controls the voltage generation operation of the voltage applicator in an asynchronous pulse-width modulation mode, which is an operating mode of pulse-width modulation in which the carrier frequency is not synchronized with the frequency of a voltage command, and a synchronous pulse-width modulation mode, which is an operating mode of pulse-width modulation in which the carrier frequency is synchronized with the frequency of a voltage command. The controller performs switching control to switch the operating mode from the asynchronous pulse-width modulation mode to the synchronous pulse-width modulation mode at an arbitrary switching phase. The controller calculates the frequency of a second asynchronous carrier wave to change the first asynchronous carrier wave used in the asynchronous pulse-width modulation mode to a second asynchronous carrier wave, based on a first phase difference from a reference phase of a first asynchronous carrier wave having a steady-state asynchronous carrier frequency to a switching phase. During switching control, the first asynchronous carrier wave is changed to the second asynchronous carrier wave, so that at the switching phase, the instantaneous value of the second asynchronous carrier wave matches the instantaneous value of the synchronous carrier wave used in the synchronous pulse width modulation mode, and the sign of the slope of the second asynchronous carrier wave matches the sign of the slope of the synchronous carrier wave. [Effects of the Invention]

[0011] The rotating machine control device according to the present disclosure has the advantage that switching from an asynchronous carrier wave to a synchronous carrier wave can be performed without any constraints on the phase of the asynchronous carrier wave. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a configuration example of a rotating machine control device according to a first embodiment; [Figure 2] FIG. 1 is a diagram showing a configuration example of a voltage applicator included in a rotating machine control device according to a first embodiment; [Figure 3] FIG. 1 is a diagram showing a configuration example of an asynchronous carrier frequency generator included in a rotating machine control device according to a first embodiment; [Figure 4] FIG. 1 is a diagram illustrating the operation of the rotary machine control device according to the first embodiment. [Figure 5]FIG. 1 is a block diagram showing an example of a hardware configuration for realizing the functions of a controller according to a first embodiment. [Figure 6] FIG. 10 is a block diagram showing another example of a hardware configuration for realizing the functions of the controller according to the first embodiment. [Figure 7] FIG. 10 is a diagram showing a configuration example of an asynchronous carrier frequency generator included in a rotating machine control device according to a second embodiment. [Figure 8] FIG. 1 is a first diagram illustrating the operation of a rotary machine control device according to a second embodiment. [Figure 9] FIG. 2 is a second diagram illustrating the operation of the rotary machine control device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Rotating machine control devices according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0014] Embodiment 1 First, a description will be given of the configuration of a rotating machine control device according to Embodiment 1. Fig. 1 is a diagram showing an example of the configuration of a rotating machine control device 1 according to Embodiment 1.

[0015] The rotating machine control device 1 includes a voltage applicator 3 and a controller 4. The voltage applicator 3 is connected to the rotating machine 2 and applies a three-phase voltage v u ,v v ,v w The controller 4 is connected to the voltage applicator 3. The controller 4 has an asynchronous PWM mode and a synchronous PWM mode. As described above, the asynchronous PWM mode is an operation mode in which the carrier frequency, which is the frequency of the carrier wave, is not synchronized with the frequency of the voltage command, and the synchronous PWM mode is an operation mode in which the carrier frequency is synchronized with the frequency of the voltage command. For ease of explanation, hereinafter, the asynchronous PWM method and asynchronous PWM mode may be simply referred to as "asynchronous PWM," and the synchronous PWM method and synchronous PWM mode may be simply referred to as "synchronous PWM."

[0016] The controller 4 generates a PWM pulse v as a PWM signal for controlling the voltage generation operation of the voltage applicator 3 using asynchronous PWM and synchronous PWM. gu ,v gv ,v gw In this paper, the carrier wave used in asynchronous PWM is called the "asynchronous carrier wave," and the carrier wave used in synchronous PWM is called the "synchronous carrier wave."

[0017] The controller 4 includes an asynchronous carrier frequency generator 5, a modulated wave generator 6, a carrier wave generator 7, and a PWM pulse generator 8. The controller 4 performs switching control to switch the operation mode from the asynchronous pulse width modulation mode to the synchronous pulse width modulation mode at any phase. Details of the switching control will be described later.

[0018] The asynchronous carrier frequency generator 5 receives a synchronous PWM mode operation command M SY and the steady-state asynchronous carrier frequency F CAS1 and inverter frequency F INV and the lower limit of the asynchronous carrier frequency F CASL and the upper limit of the asynchronous carrier frequency F CASU and an arbitrary switching phase θ t and the reference phase θ of the asynchronous carrier MAS and an arbitrary switching phase θ from the reference phase of the synchronous carrier wave t Phase difference θ DSY and the number of synchronous pulses P NSY The lower limit of the asynchronous carrier frequency F CASL and the upper limit of the asynchronous carrier frequency F CASU is the steady-state asynchronous carrier frequency F CAS1 In this paper, the lower limit of the asynchronous carrier frequency F CASL is called the "first lower limit frequency", and the upper limit value F CASU is sometimes called the "first upper limit frequency."

[0019] Reference phase θ MAS may be a peak of the asynchronous carrier wave, a valley of the asynchronous carrier wave, or a zero crossing point of the asynchronous carrier wave. MASmay be any phase other than a peak, valley or zero crossing of the asynchronous carrier.

[0020] From now on, the reference phase θ of the asynchronous carrier wave MAS is the peak of the asynchronous carrier wave. Therefore, the reference phase θ of the asynchronous carrier wave MAS is the phase θ of the peak of the asynchronous carrier wave. MAS ". The reference phase of the synchronous carrier wave is expressed as the reference phase θ MAS For example, the reference phase θ MAS If is the crest of the asynchronous carrier wave, the reference phase of the synchronous carrier wave is also set to the crest, and the reference phase θ MAS is the valley of the asynchronous carrier wave, the reference phase of the synchronous carrier wave is also set to the valley. Hereinafter, the reference phase of the synchronous carrier wave will also be referred to as the "phase of the peak of the synchronous carrier wave."

[0021] The asynchronous carrier frequency generator 5 generates these synchronous PWM mode operation commands M SY , the steady-state asynchronous carrier frequency F CAS1 , inverter frequency F INV , the lower limit of the asynchronous carrier frequency F CASL , the upper limit of the asynchronous carrier frequency F CASU , any switching phase θ t , the phase θ of the peak of the asynchronous carrier wave MAS , phase difference θ DSY and the number of synchronous pulses P NSY Based on this, the asynchronous carrier frequency command F CAS Generate.

[0022] The modulated wave generator 6 has the PWM mode M PWM and output voltage phase command θ V and the voltage command V u * ,V v * ,V w * The modulated wave generator 6 is operated in PWM mode M PWM , output voltage phase command θ V and voltage command V u * ,V v* ,V w * Based on the modulated wave v u * ,v v * ,v w * Generate.

[0023] The carrier wave generator 7 has a PWM mode M PWM and output voltage phase command θ V and asynchronous carrier frequency command F CAS The carrier wave generator 7 is operated in PWM mode M PWM , asynchronous carrier frequency command F CAS and output voltage phase command θ V Based on the carrier C u ,C v ,C w Generate.

[0024] The PWM pulse generator 8 generates the modulated wave v u * ,v v * ,v w * and carrier wave C u ,C v ,C w The PWM pulse generator 8 receives the modulated wave v u * ,v v * ,v w * and carrier wave C u ,C v ,C w Based on this, a PWM pulse v which is a PWM signal for controlling the voltage applicator 3 is generated. gu ,v gv ,v gw In this paper, the PWM pulses generated by the PWM pulse generator 8 when operating in asynchronous PWM mode are sometimes referred to as "asynchronous PWM pulses," and the PWM pulses generated by the PWM pulse generator 8 when operating in synchronous PWM mode are sometimes referred to as "synchronous PWM pulses."

[0025] The modulated wave v generated by the modulated wave generator 6u * ,v v * ,v w * are three-phase sine waves of u, v, and w phases, respectively. u * ,v v * ,v w * There is a phase difference of 120 degrees between the modulated waves v u * ,v v * ,v w * The amplitude of the voltage command V u * ,V v * ,V w * The voltage command V u * ,V v * ,V w * The magnitude of is 0 to 4 / π, and the maximum value is the fundamental wave amplitude 4 / π obtained when a square wave is expanded into a Fourier series.

[0026] In order to improve the utilization rate of the voltage output from the voltage applicator 3, these modulated waves v u * ,v v * ,v w * Each of the modulated waves v u * ,v v * ,v w * A third harmonic having a frequency three times the modulating wave frequency may be superimposed on the voltage command V u * ,V v * ,V w * When the magnitude of exceeds 1 and drives the rotating machine 2, the voltage v applied to the rotating machine 2 u ,v v ,vw The fundamental voltage and voltage command V are obtained by expanding u * ,V v * ,V w * The modulated wave corresponding to the asynchronous PWM pulse and the modulated wave corresponding to the synchronous PWM pulse may have different third harmonics and correction gains. Therefore, the modulated wave generator 6 may multiply the modulated wave corresponding to the asynchronous PWM pulse and the modulated wave corresponding to the synchronous PWM pulse by a gain that corrects the relationship between the asynchronous PWM pulse and the synchronous PWM pulse. PWM Depending on the PWM pulse, the modulation wave corresponding to the asynchronous PWM pulse and the modulation wave corresponding to the synchronous PWM pulse are switched to generate the modulation wave v u * ,v v * ,v w * Output as

[0027] The carrier wave generator 7 operates in PWM mode M PWM Depending on the ASu ,C ASv ,C ASw and a synchronous carrier wave C corresponding to the synchronous PWM pulse SYu ,C SYv ,C SYw Select either one of the carrier waves C u ,C v ,C w Output as

[0028] The asynchronous carrier wave is output voltage phase command θ V The frequency of the asynchronous carrier wave is determined by the asynchronous carrier wave frequency generator 5 in accordance with the asynchronous carrier wave frequency command F CAS and output to the carrier wave generator 7. The synchronous carrier wave is generated as an output voltage phase command θ V The frequency of the synchronous carrier wave is the inverter frequency F INV The number of synchronous pulses P NSY The carrier wave C u ,C v ,C wThe carrier waves may be of the same phase or may be three-phase carrier waves of different phases. u ,C v ,C w is a unitless signal, and in this paper, it is considered to be a signal whose value changes between minus 1 and plus 1.

[0029] PWM pulse v generated by PWM pulse generator 8 gu ,v gv ,v gw is input to the voltage applicator 3. The voltage applicator 3 generates a PWM pulse v gu ,v gv ,v gw Based on this, the three-phase voltage v applied to the rotating machine 2 u ,v v ,v w Generate.

[0030] The PWM pulse generator 8 generates the modulated wave v output from the modulated wave generator 6. u * ,v v * ,v w * and the carrier wave C output from the carrier wave generator 7 u ,C v ,C w The magnitudes of the modulated wave v and w are compared for the u, v, and w phases. u * is the carrier wave C u If it is greater than 1, it outputs "true" or "1" and modulates the wave v u * is the carrier wave C u In the following cases, "false" or "0" is set to the PWM pulse v gu Similarly, for the v-phase and w-phase, the modulated wave and the carrier wave of each phase are compared in magnitude, and a value ("1" or "0") according to the comparison result is output as a PWM pulse v to the voltage applicator 3. gv ,v gw Output as

[0031] The rotating machine 2 is driven by the three-phase voltage v output from the voltage applicator 3. u ,v v ,v wThe rotating machine 2 may be a synchronous motor (PMSM: Permanent Magnet Synchronous Motor), an induction motor (IM: Induction Motor), or a synchronous reluctance motor (SynRM: Synchronous Reluctance Motor).

[0032] The voltage applicator 3 has, for example, the configuration shown in Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the voltage applicator 3 included in the rotating machine control device 1 according to the first embodiment, and shows an example of the circuit configuration when the voltage applicator 3 is a three-phase PWM inverter.

[0033] The voltage applicator 3 includes a leg 30A in which a semiconductor element UP of the upper arm and a semiconductor element UN of the lower arm are connected in series, a leg 30B in which a semiconductor element VP of the upper arm and a semiconductor element VN of the lower arm are connected in series, and a leg 30C in which a semiconductor element WP of the upper arm and a semiconductor element WN of the lower arm are connected in series.

[0034] The legs 30A to 30C are connected in parallel with each other, and a bus voltage is applied to the legs 30A to 30C through the DC buses 35a and 35b. The voltage applicator 3 converts DC power from a power source 36, which is supplied to the legs 30A to 30C through the DC buses 35a and 35b, into AC power, and supplies the converted AC power to the rotating machine 2 to drive the rotating machine 2.

[0035] 2 illustrates an example in which the semiconductor elements UP, UN, VP, VN, WP, and WN are metal-oxide-semiconductor field-effect transistors (MOSFETs). The semiconductor element UP includes a transistor 30a and a diode 30b connected in anti-parallel to the transistor 30a. The other semiconductor elements UN, VP, VN, WP, and WN have a similar configuration. "Anti-parallel" means that the anode side of the diode 30b is connected to a first terminal corresponding to the source of the MOSFET, and the cathode side of the diode 30b is connected to a second terminal corresponding to the drain of the MOSFET.

[0036] The semiconductor elements UP, UN, VP, VN, WP, and WN may be, for example, insulated gate bipolar transistors (IGBTs) instead of MOSFETs.

[0037] A connection point 32 between the semiconductor element UP of the upper arm of leg 30A and the semiconductor element UN of the lower arm is connected to a first phase (e.g., u-phase) of the rotating machine 2, a connection point 33 between the semiconductor element VP of the upper arm of leg 30B and the semiconductor element VN of the lower arm is connected to a second phase (e.g., v-phase) of the rotating machine 2, and a connection point 34 between the semiconductor element WP of the upper arm of leg 30C and the semiconductor element WN of the lower arm is connected to a third phase (e.g., w-phase) of the rotating machine 2. In the voltage applicator 3, the connection points 32, 33, and 34 form AC terminals.

[0038] Here, we will explain the voltage vector output by the voltage applicator 3. The voltage applicator 3 applies a voltage V supplied from the power source 36 through the DC buses 35a and 35b. DC The desired voltage is obtained by PWM-controlling the DC power of the inverter 3 and applied to the rotating machine 2. As mentioned above, the voltage applicator 3 is a three-phase PWM inverter. A three-phase PWM inverter has two semiconductor switching elements, one above the other, for each phase, and operates so that either one of the upper or lower semiconductor switching elements is in the on state. Therefore, a three-phase PWM inverter has 2^3 (=8) switching states.

[0039] FIG. 3 is a diagram showing an example of the configuration of the asynchronous carrier frequency generator 5 included in the rotating machine control device 1 according to the first embodiment.

[0040] The asynchronous carrier frequency generator 5 includes calculators 501, 502, 504, 505, 508, and 509, a decimal separator 503, comparators 506, 510, and 511, a first selector 507, a logical AND calculator 512, and a second selector 513.

[0041] The calculator 501 receives a switching phase θt and the phase θ of the peak of the asynchronous carrier wave MAS The switching phase θ t is the phase when the asynchronous carrier wave used in the asynchronous PWM is switched to the synchronous carrier wave used in the synchronous PWM, and is an arbitrary phase not limited to the three points of the peak, valley, or zero crossing point of the asynchronous carrier wave. t and the phase of the mountain θ MAS Based on this, the phase θ of the peak of the asynchronous carrier wave is calculated by the following equation (1). MAS From switching phase θ t Phase difference θ DAS In this paper, the phase difference θ DAS is sometimes called the "first phase difference."

[0042]

number

[0043] The calculator 502 receives the steady-state asynchronous carrier frequency F CAS1 , inverter frequency F INV , the phase difference θ calculated by equation (1) DAS , and the phase angle of one cycle of the sine wave, 360 degrees, are input. The calculator 502 calculates the steady-state asynchronous carrier frequency F CAS1 , inverter frequency F INV , phase difference θ DAS , and the phase angle of one cycle of the sine wave is 360 degrees, the phase θ of the peak of the asynchronous carrier wave is calculated by the following equation (2). MAS From switching phase θ t Number of asynchronous pulses up to P NDAS Calculate the following.

[0044]

number

[0045] The decimal separator 503 receives the asynchronous pulse number P calculated by the calculator 502. NDAS The decimal separator 503 receives the asynchronous pulse number P NDAS The integer part PNDASI and the decimal part P NDASD and separate into.

[0046]

number

[0047] The calculator 504 calculates the switching phase θ from the phase of the peak of the synchronous carrier wave. t Phase difference θ DSY The phase angle of one cycle of a sine wave is 360 degrees, and the number of synchronous pulses is P NSY The calculator 504 calculates the switching phase θ from the phase of the peak of the synchronous carrier wave. t Phase difference θ DSY The phase angle of one cycle of a sine wave is 360 degrees, and the number of synchronous pulses is P NSY Based on this, the switching phase θ is calculated from the phase of the peak of the synchronous carrier wave by the following equation (4). t Number of asynchronous pulses up to P NDSY Calculate the following.

[0048]

number

[0049] A supplement to equation (4) is as follows. For example, in the case of 15 synchronous pulses, the denominator of equation (4) is 360 / 15 = 20.4 degrees. The peak of the synchronous carrier wave is the phase difference θ DSY is selected so as not to exceed this 20.4 degrees, so the number of synchronization pulses P NSY The value of is greater than or equal to 0 and less than or equal to 1.

[0050] The calculator 505 receives the decimal part P of the asynchronous pulse number. NDASD and the number of asynchronous pulses P NDSY The calculator 505 receives the decimal part P of the asynchronous pulse number. NDASD and the number of asynchronous pulses P NDSY Based on this, the right side of the following equation (5) is calculated: "0.5" on the left side is a threshold value for determining whether the value on the right side is large or small.

[0051]

number

[0052] Comparator 506 receives as input a threshold value of 0.5 and the result of the calculation of the right-hand side of equation (5) calculated by calculator 505. Comparator 506 compares the magnitude of threshold value 0.5 with the value of the right-hand side of equation (5) calculated by calculator 505 using equation (5), and outputs the result of the judgment, either "true" or "false." Comparator 506 outputs "0" if the result of the judgment of equation (5) is "false," and outputs "1" if the result of the judgment of equation (5) is "true."

[0053] The first selector 507 receives the comparison result of the comparator 506, the pulse number "0" and the pulse number "1". If the output of the comparator 506 is "false", the first selector 507 selects the pulse number "0", and if the output of the comparator 506 is "true", the first selector 507 selects the pulse number "1", and the pulse number P NC Output as

[0054] The calculator 508 receives the integer part P of the asynchronous pulse number. NDASI The output of the first selector 507 and the switching phase θ t Number of asynchronous pulses up to P NDSY The calculator 508 calculates the phase θ of the peak of the asynchronous carrier wave. MAS From switching phase θ t The integer part of the number of asynchronous pulses up to P NDASI , the output of the first selector 507, and the switching phase θ t Number of asynchronous pulses up to P NDSY Based on this, the term in parentheses in the following equation (6) is calculated.

[0055]

number

[0056] The calculator 509 receives the inverter frequency F INV The output of the calculator 508, the phase angle of one cycle of the sine wave is 360 degrees, and the phase difference θ DASThe calculator 509 calculates the inverter frequency F INV , the output of the calculator 508, the phase angle of one cycle of the sine wave is 360 degrees, and the phase difference θ DAS Based on this, according to the above equation (6), the asynchronous carrier frequency F CAS2 Calculate the following.

[0057] In addition, the asynchronous carrier frequency F CAS2 The inverter frequency F used to calculate INV , the steady-state asynchronous carrier frequency F CAS1 and the phase θ of the peak of the asynchronous carrier wave that is the basis of the output of the calculator 501. MAS is a signal whose value changes from moment to moment. Therefore, two calculation modes are possible. In the first calculation mode, the calculator 509 calculates the synchronous PWM mode operation command M SY The inverter frequency F whose value does not change from the time of rising to the start of synchronous PWM mode INV , asynchronous carrier frequency F CAS1 and phase θ MAS Using the asynchronous carrier frequency F CAS2 That is, in this calculation mode, the synchronous PWM mode operation command M SY The inverter frequency F INV , asynchronous carrier frequency F CAS1 and the phase of the mountain θ MAS Using the asynchronous carrier frequency F CAS2 In the second calculation mode, the calculator 509 calculates the synchronous PWM mode operation command M SY The inverter frequency F, which changes from time to time from the rising edge to the start of synchronous PWM mode, INV , asynchronous carrier frequency F CAS1 and phase θ MAS Using the asynchronous carrier frequency F CAS2In the rotating machine control device 1 according to the first embodiment, any of these calculation modes may be used. When the first calculation mode is used, it is possible to reduce the processing load on the asynchronous carrier frequency generator 5. Furthermore, when the second calculation mode is used, it is possible to more smoothly switch from the asynchronous carrier wave to the synchronous carrier wave.

[0058] Asynchronous carrier frequency F CAS2 is the calculated value of the asynchronous carrier frequency to smoothly switch from the asynchronous carrier to the synchronous carrier. In this paper, the steady-state asynchronous carrier frequency F CAS1 The asynchronous carrier wave having the asynchronous carrier frequency F calculated by the calculator 509 is called the "first asynchronous carrier wave." CAS2 The asynchronous carrier that can be generated by this is sometimes called the "second asynchronous carrier." In this definition, the steady-state asynchronous carrier frequency F CAS1 is the "frequency of the first asynchronous carrier wave" and is the asynchronous carrier frequency F calculated by the calculator 509. CAS2 is the "frequency of the second asynchronous carrier wave." In this paper, the asynchronous carrier frequency F CAS2 The calculated value is sometimes called the "first frequency."

[0059] The comparator 510 receives the lower limit F of the asynchronous carrier frequency. CASL and the asynchronous carrier frequency F CAS2 and the asynchronous carrier frequency F CAS2 and the upper limit of the asynchronous carrier frequency F CASU is entered.

[0060] The comparators 510 and 511 perform the calculation of the following equation (7).

[0061]

number

[0062] Comparator 510 detects the asynchronous carrier frequency F CAS2 is the lower limit of the asynchronous carrier frequency F CASLIf it is greater than the asynchronous carrier frequency F, it outputs "true". CAS2 is the lower limit of the asynchronous carrier frequency F CASL The comparator 510 outputs "false" in the following cases: CAS2 is the lower limit of the asynchronous carrier frequency F CASL In the above cases, "true" is output, and the asynchronous carrier frequency F CAS2 is the lower limit of the asynchronous carrier frequency F CASL If it is less than the limit, "false" may be output.

[0063] Also, the comparator 511 detects the asynchronous carrier frequency F CAS2 is the upper limit of the asynchronous carrier frequency F CASU Outputs "true" when the asynchronous carrier frequency F CAS2 is the upper limit of the asynchronous carrier frequency F CASU In the above cases, the comparator 511 outputs "false." CAS2 is the upper limit of the asynchronous carrier frequency F CASU Outputs "true" in the following cases and outputs the asynchronous carrier frequency F CAS2 is the upper limit of the asynchronous carrier frequency F CASU If it is greater, it may output "false."

[0064] The logical product calculator 512 receives a synchronous PWM mode operation command M SY The comparison result of the comparator 510 and the comparison result of the comparator 511 are input. SY is a signal that is "false" when operating in asynchronous PWM mode, and is "true" when switching from asynchronous PWM mode to synchronous PWM mode and when operating in synchronous PWM mode. SY If the comparison result of the comparator 510 and the comparison result of the comparator 511 are both "true", it outputs "true" and issues a synchronous PWM mode operation command M SY If at least one of the comparison results of the comparators 510 and 511 is "false", it outputs "false".

[0065] The second selector 513 receives the result of the AND operation from the AND operator 512 and the steady-state asynchronous carrier frequency F CAS1 and the calculated value of the asynchronous carrier frequency, F CAS2 If the output of the AND operator 512 is "false", the second selector 513 selects the asynchronous carrier frequency F CAS1 Select the asynchronous carrier frequency command F CAS If the output of the AND operator 512 is "true", the asynchronous carrier frequency F CAS2 Select the asynchronous carrier frequency command F CAS Output as

[0066] The asynchronous carrier frequency generator 5 has a switching phase θ t Asynchronous carrier frequency F to smoothly switch from asynchronous carrier to synchronous carrier CAS2 After calculating, or asynchronous carrier frequency F CAS2 During the calculation process, if the calculation result of the logical product calculator 512 is "false", or if the calculation result of the logical product calculator 512 is "false", the switching phase θ t 120 degrees is added to the switching phase θ t The addition process of 120 degrees to the calculated asynchronous carrier frequency F CAS2 is too large and the upper limit of the asynchronous carrier frequency F CASU If the calculated asynchronous carrier frequency F CAS2 is too small to reach the lower limit of the asynchronous carrier frequency, F CASL In such a case, the switching phase θ t By adding 120 degrees to the calculated asynchronous carrier frequency F CAS2 is the lower limit F CASL and upper limit F CASU The reason why the phase to be added is set to 120 degrees is because at each 120-degree phase shift, the relationship between the three-phase voltage waveforms between the u, v, and w phases is the same as before the 120-degree phase shift.

[0067] Next, the operation of the rotating machine control device 1 according to the first embodiment will be described using specific waveform examples. FIG. 4 is a diagram for explaining the operation of the rotating machine control device 1 according to the first embodiment. Specifically, in FIG. 4, from the top, the asynchronous carrier frequency command F CAS , asynchronous carrier C ASu and synchronous carrier C SYu , and the output voltage phase command θ V and switching phase θ t In the middle part of Figure 4, an example of the waveform of the asynchronous carrier C ASu The waveform of is shown by a solid line, and the synchronous carrier C SYu The waveform of the output voltage phase command θ V The value varies between 0 and 360 degrees, and if it exceeds 360 degrees it is reset to 0 degrees.

[0068] In Figure 4, the synchronous PWM mode operation command M SY After the command is issued, at time t1, the output of the AND operator 512 in FIG. 3 becomes "true", and the asynchronous carrier frequency F CAS2 is selected, and the asynchronous carrier frequency command F CAS is the steady-state asynchronous carrier frequency F CAS1 From the above, the asynchronous carrier frequency F calculated by the calculator 509 is CAS2 The figure shows how the display switches to the

[0069] After time t1, asynchronous carrier C ASu The frequency of the asynchronous carrier frequency F CAS2 and the output voltage phase command θ V is the switching phase θ t At time t2, the asynchronous carrier C ASu The instantaneous value and sign of the slope of and the synchronous carrier C SYu The instantaneous value and the sign of the gradient of the output voltage phase command θ V is the switching phase θ t At time t2, the asynchronous carrier C ASu Synchronous carrier C SYu By switching to this, it is possible to suppress current oscillations when the operation mode is switched.

[0070] Fig. 5 is a block diagram showing an example of a hardware configuration for realizing the functions of controller 4 in embodiment 1. When realizing the functions of controller 4 in embodiment 1, as shown in Fig. 5, the configuration can include processor 300 that performs calculations, memory 302 that stores programs read by processor 300, and interface 304 that inputs and outputs signals.

[0071] The processor 300 is an example of a computing means. The processor 300 may be a computing means called a microprocessor, a microcomputer, a microcontroller, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). Examples of the memory 302 include non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), and EEPROM (registered trademark) (Electrically EPROM), as well as magnetic disks, flexible disks, optical disks, compact disks, minidisks, and DVDs (Digital Versatile Discs).

[0072] The memory 302 stores a program that executes the functions of the controller 4 in the first embodiment. The processor 300 exchanges necessary information via the interface 304, executes the program stored in the memory 302, and refers to the table stored in the memory 302, thereby performing the above-mentioned processing. The calculation results by the processor 300 can be stored in the memory 302.

[0073] Furthermore, when realizing the functions of the controller 4 in the first embodiment, the configuration shown in Fig. 6 may be used. Fig. 6 is a block diagram showing another example of a hardware configuration for realizing the functions of the controller 4 in the first embodiment. In Fig. 6, the processor 300 and memory 302 shown in Fig. 5 are replaced with a processing circuit 303. The processing circuit 303 may be a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Information input to the processing circuit 303 and information output from the processing circuit 303 can be exchanged via an interface 304.

[0074] It is also possible that some of the processing in the controller 4 is performed by the processing circuit 303, and the processing that is not performed by the processing circuit 303 is performed by the processor 300 and the memory 302.

[0075] As described above, in the rotating machine control device according to the first embodiment, the controller that controls the voltage generation operation of the voltage applicator performs switching control to switch the operation mode from the asynchronous PWM mode to the synchronous PWM mode at an arbitrary switching phase. In the switching control, the first asynchronous carrier wave used in the asynchronous pulse-width modulation mode is changed to the second asynchronous carrier wave. The controller calculates the frequency of the second asynchronous carrier wave to change the first asynchronous carrier wave used in the asynchronous pulse-width modulation mode to the second asynchronous carrier wave based on a first phase difference from the reference phase of the first asynchronous carrier wave having the asynchronous carrier frequency in a steady state to the switching phase. During the switching control, by changing the first asynchronous carrier wave to the second asynchronous carrier wave, the instantaneous value of the second asynchronous carrier wave matches the instantaneous value of the synchronous carrier wave used in the synchronous pulse-width modulation mode at the switching phase, and the sign of the slope of the second asynchronous carrier wave matches the sign of the slope of the synchronous carrier wave. According to the switching control of the first embodiment, at any switching phase, the first asynchronous carrier wave used in the asynchronous PWM mode can be switched to the synchronous carrier wave used in the synchronous PWM mode. This makes it possible to suppress current oscillations that may occur when switching from the asynchronous PWM mode to the synchronous PWM mode. Furthermore, by using the switching control of the first embodiment, it becomes possible to switch from the asynchronous carrier wave to the synchronous carrier wave without any restrictions on the phase of the asynchronous carrier wave.

[0076] Furthermore, in the rotating machine control device according to the first embodiment, when the calculated value of the frequency of the second asynchronous carrier wave is the first frequency, the controller may repeat calculations so that the first frequency falls between a first upper limit frequency determined based on the frequency of the first asynchronous carrier wave and a first lower limit frequency determined based on the frequency of the first asynchronous carrier wave. Furthermore, if the first frequency does not fall between the first upper limit frequency and the first lower limit frequency, the controller may add 120 degrees to the switching phase and repeat the process of adding 120 degrees to the switching phase so that the first frequency falls between the first upper limit frequency and the first lower limit frequency. Performing such calculations enables the switching from the asynchronous carrier wave to the synchronous carrier wave to be completed in a shorter time.

[0077] Embodiment 2 Fig. 7 is a diagram showing an example of the configuration of an asynchronous carrier frequency generator 5a included in a rotating machine control device 1a according to a second embodiment. Although not shown, for convenience of explanation, the rotating machine control device according to the second embodiment will be referred to as a "rotating machine control device 1a" to distinguish it from the rotating machine control device 1 according to the first embodiment. The rotating machine control device 1a according to the second embodiment has a configuration in which the asynchronous carrier frequency generator 5 of the rotating machine control device 1 according to the first embodiment (see Figs. 1 and 3) is replaced with an asynchronous carrier frequency generator 5a shown in Fig. 7. The components other than the asynchronous carrier frequency generator 5a are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0078] The asynchronous carrier frequency generator 5a includes calculators 501, 502, 504, 505, 508, 509, and 514, a decimal separator 503, comparators 506, 510a, 511a, 515, and 516, a first selector 507, logical product calculators 512 and 517, a second selector 513a, a third selector 518, a limited range reducer 519, and a pseudorandom frequency generator 520. The calculators 501, 502, 504, 505, 508, and 509, the decimal separator 503, the comparator 506, the first selector 507, and the logical product calculator 512 are the same as the calculators 501, 502, 504, 505, 508, and 509, the decimal separator 503, the comparator 506, the first selector 507, and the logical product calculator 512 according to the first embodiment, and therefore will not be described here.

[0079] The calculator 514 receives the inverter frequency F INV and the number of synchronous pulses P NSY and the switching phase θ from the phase of the peak of the synchronous carrier wave t Phase difference θ DSY and the phase θ of the peak of the asynchronous carrier wave MAS From switching phase θ t Phase difference θ DAS The calculator 514 receives the inverter frequency F INV , the number of synchronous pulses P NSY , and the phase difference θ DSY ,θ DAS Based on this, the interrupt frequency F of the asynchronous carrier is calculated by the following equation (8). CAS2 ' is calculated.

[0080]

number

[0081] The comparator 515 receives the lower limit F of the asynchronous carrier frequency. CASL and the asynchronous carrier interrupt frequency F CAS2 ' and the asynchronous carrier interrupt frequency F CAS2 ' and the upper limit of the asynchronous carrier frequency F CASU is entered.

[0082] The comparators 515 and 516 perform the calculation of the following equation (9).

[0083]

number

[0084] Comparator 515 detects the asynchronous carrier interrupt frequency F CAS2 ' is the lower limit of the asynchronous carrier frequency F CASL If it is greater than 1, it outputs "true" and the asynchronous carrier interrupt frequency F CAS2 ' is the lower limit of the asynchronous carrier frequency F CASL The comparator 515 outputs "false" in the following cases: CAS2 ' is the lower limit of the asynchronous carrier frequency F CASL In the above cases, "true" is output, and the asynchronous carrier wave interrupt frequency F CAS2 ' is the lower limit of the asynchronous carrier frequency F CASL If it is less than the limit, "false" may be output.

[0085] Also, the comparator 516 detects the asynchronous carrier interrupt frequency F CAS2 ' is the upper limit of the asynchronous carrier frequency F CASU If the frequency is less than F, the asynchronous carrier wave interrupt frequency F CAS2 ' is the upper limit of the asynchronous carrier frequency F CASU In the above cases, the comparator 516 outputs "false."CAS2 ' is the upper limit of the asynchronous carrier frequency F CASU In the following cases, "true" is output and the asynchronous carrier interrupt frequency F CAS2 ' is the upper limit of the asynchronous carrier frequency F CASU If it is greater, it may output "false."

[0086] The logical product calculator 517 receives a synchronous PWM mode operation command M SY The comparison result of the comparator 515 and the comparison result of the comparator 516 are input. SY is a signal that is "false" when operating in asynchronous PWM mode, and is "true" when switching from asynchronous PWM mode to synchronous PWM mode and when operating in synchronous PWM mode. SY If the comparison result of the comparator 515 and the comparison result of the comparator 516 are both "true", "true" is output, and a synchronous PWM mode operation command M SY If at least one of the comparison results of comparators 515 and 516 is "false", it outputs "false". The calculation result of logical AND operator 517 is input to third selector 518.

[0087] The limit range reducer 519 includes the steady-state asynchronous carrier frequency F CAS1 and the lower limit of the asynchronous carrier frequency F CASL and the upper limit of the asynchronous carrier frequency F CASU The limit range reducer 519 receives the asynchronous carrier frequency F CAS1 The lower limit of the asynchronous carrier frequency F CASL and the upper limit of the asynchronous carrier frequency F CASU The width of the asynchronous carrier frequency is reduced, for example, by half, to the lower limit F CASL ' and the upper limit of the reduced asynchronous carrier frequency F CASU For example, the steady-state asynchronous carrier frequency F CAS1 is 5000Hz, the lower limit of the asynchronous carrier frequency F CASL is 4500Hz, the upper limit of the asynchronous carrier frequency F CASUis 5500Hz, the lower limit of the reduced asynchronous carrier frequency F CASL ' to 4750Hz, the upper limit of the reduced asynchronous carrier frequency F CASU From these definitions, the lower limit of the reduced asynchronous carrier frequency F CASL ' is the lower limit of the asynchronous carrier frequency F CASL The upper limit of the asynchronous carrier frequency, F, is larger (higher) than CASU ' is the upper limit of the asynchronous carrier frequency F CASU In this paper, the lower limit of the asynchronous carrier frequency, F CASL ' is called the "second lower limit frequency", and the upper limit value F CASU ' is sometimes called the "second upper limit frequency."

[0088] The comparator 510a receives the lower limit F of the reduced asynchronous carrier frequency. CASL ' and the asynchronous carrier frequency F CAS2 and the asynchronous carrier frequency F CAS2 and the reduced upper limit of the asynchronous carrier frequency F CASU ' is entered.

[0089] The asynchronous carrier frequency F input to the comparators 510a and 511a is CAS2 The value calculated using either the first or second calculation mode described in the first embodiment is input to the comparators 510a and 511a. CAS2 is the synchronous PWM mode operation command M SY The inverter frequency F INV , asynchronous carrier frequency F CAS1 and the phase θ of the peak of the asynchronous carrier wave MAS Alternatively, the value may be calculated using the synchronous PWM mode operation command M SY The inverter frequency F changes from the time of rising to the start of synchronous PWM mode. INV , asynchronous carrier frequency F CAS1 and the phase θ of the peak of the asynchronous carrier wave MAS It may also be a value calculated using

[0090] Comparators 510a and 511a perform the same calculation as in equation (7) above.

[0091] Comparator 510a detects the asynchronous carrier frequency F CAS2 The lower limit of the asynchronous carrier frequency F CASL 'If it is greater than 'true', it outputs the asynchronous carrier frequency F CAS2 The lower limit of the asynchronous carrier frequency F CASL 'FALSE' is output in the following cases: The comparator 510a outputs "false" when the asynchronous carrier frequency F CAS2 The lower limit of the asynchronous carrier frequency F CASL 'If the above is true, output "true" and set the asynchronous carrier frequency F CAS2 The lower limit of the asynchronous carrier frequency F CASL If it is less than ', it may output "false".

[0092] Also, the comparator 511a detects the asynchronous carrier frequency F CAS2 The upper limit of the asynchronous carrier frequency F CASU ', output "true" when it is less than the asynchronous carrier frequency F CAS2 The upper limit of the asynchronous carrier frequency F CASU In the above cases, the comparator 511a outputs "false." CAS2 The upper limit of the asynchronous carrier frequency F CASU 'Outputs "true" in the following cases, and asynchronous carrier frequency F CAS2 The upper limit of the asynchronous carrier frequency F CASU 'If it is greater than ', it may output "false".

[0093] The pseudorandom frequency generator 520 includes a stationary asynchronous carrier frequency F CAS1 and the calculated value of the asynchronous carrier frequency, F CAS2 and the lower limit of the asynchronous carrier frequency F CASL and the upper limit of the asynchronous carrier frequency F CASUThe pseudorandom frequency generator 520 generates a stationary asynchronous carrier frequency F CAS1 and the asynchronous carrier frequency F CAS2 A size comparison is made between .

[0094]

number

[0095] If the result of the determination in equation (10) is "true", the pseudorandom frequency generator 520 generates the asynchronous carrier frequency F CAS2 , the lower limit of the asynchronous carrier frequency F CASL and the upper limit of the asynchronous carrier frequency F CASU Based on this, the pseudorandom frequency F is calculated by the following equation (11): CAS2R and output to the third selector 518. In this paper, the pseudo-random frequency F CAS2R The calculated value is converted to the first frequency, the asynchronous carrier frequency F CAS2 It is sometimes called the "second frequency" to distinguish it from the

[0096]

number

[0097] Equation (11) is the pseudorandom frequency F CAS2R and the upper limit of the asynchronous carrier frequency F CASU The average period calculated by the arithmetic mean of the sum of the periods, which are the reciprocals of each of these, is the asynchronous carrier frequency F CAS2 The pseudorandom frequency F is generated based on the relationship that the period is equal to the reciprocal of CAS2R In other words, the asynchronous carrier frequency F CAS2 is the pseudorandom frequency F CAS2R and the upper limit of the asynchronous carrier frequency F CASU is in a harmonic mean relationship with

[0098] If the result of the determination in equation (10) is "true", the asynchronous carrier frequency F CAS2 and the pseudorandom frequency F calculated by equation (11) CAS2R and the upper limit of the asynchronous carrier frequency F CASU In this case, the frequency of the second asynchronous carrier wave is spread pseudo-randomly, so that even-numbered harmonics that may occur when the second asynchronous carrier wave is output can be reduced.

[0099] If the result of the determination in equation (10) is "false", the pseudorandom frequency generator 520 generates the asynchronous carrier frequency F CAS2 , the lower limit of the asynchronous carrier frequency F CASL and the upper limit of the asynchronous carrier frequency F CASU Based on this, the pseudorandom frequency F is calculated by the following equation (12): CAS2R and outputs the result to the third selector 518.

[0100]

number

[0101] Equation (12) is the pseudorandom frequency F CAS2R and the lower limit of the asynchronous carrier frequency F CASL The arithmetic mean of the sum of the periods, which are the reciprocals of CAS2 The pseudorandom frequency F is generated based on the relationship that the period is equal to the reciprocal of CAS2R In other words, the asynchronous carrier frequency F CAS2 is the pseudorandom frequency F CAS2R and the lower limit of the asynchronous carrier frequency F CASL is in a harmonic mean relationship with

[0102] If the result of the determination in equation (10) is "false", the asynchronous carrier frequency F CAS2 and the pseudorandom frequency F calculated by equation (12) CAS2Rand the lower limit of the asynchronous carrier frequency F CASL In this case, the frequency of the second asynchronous carrier wave is spread pseudo-randomly, so that even-numbered harmonics that may occur when the second asynchronous carrier wave is output can be reduced.

[0103] The above-described method for spreading the frequency of the second asynchronous carrier wave is merely an example, and the present invention is not limited to this example. CAS2 Instead of outputting a pseudo-random frequency F CAS2R and the upper limit of the asynchronous carrier frequency F CASU and alternately output, or a pseudo-random frequency F CAS2R and the lower limit of the asynchronous carrier frequency F CASL Alternatively, the frequency may be spread using asynchronous carrier waves of a plurality of frequencies so that the average value of the period does not change.

[0104] The third selector 518 receives the result of the AND operation from the AND operator 517 and the pseudo-random frequency F CAS2R and the asynchronous carrier interrupt frequency F CAS2 If the output of the AND operator 517 is "false", the third selector 518 selects the pseudo-random frequency F CAS2R If the output of the AND operator 517 is "true", the interrupt frequency F of the asynchronous carrier wave is selected and output. CAS2 Select and output.

[0105] The second selector 513a receives the result of the AND operation from the AND operator 512 and the steady-state asynchronous carrier frequency F CAS1 and the output of the third selector 518. If the output of the AND operator 512 is "false", the second selector 513a selects the steady-state asynchronous carrier frequency F CAS1 Select the asynchronous carrier frequency command F CAS If the output of the AND operator 512 is "true", the output of the third selector 518 is selected to output the asynchronous carrier frequency command F CAS Output as

[0106] The operation of the second selector 513a will be explained in more detail. In FIG. 7, when the second selector 513a is about to switch from the asynchronous PWM mode to the synchronous PWM mode based on the calculation result of the AND operator 512, the synchronous PWM mode operation command M SY Since the second selector 513a selects the output of the third selector 518, the third selector 518 selects the interrupt frequency F of the asynchronous carrier wave when the calculation result of the calculator 514 falls within a specific frequency range by the comparators 515 and 516. CAS2 As described above, the calculator 514 calculates the asynchronous carrier interrupt frequency F CAS2 This equation (8) includes the first phase difference θ DAS The concept of calculation is to find the frequency at which the asynchronous carrier wave and the synchronous carrier wave overlap within one period. DAS is the switching phase θ t When the time comes within one cycle of CAS2 The condition that ' is recalculated is guaranteed.

[0107] Next, the operation of the rotating machine control device 1a according to the second embodiment will be described using specific waveform examples. Fig. 8 is a first diagram for explaining the operation of the rotating machine control device 1a according to the second embodiment. The types of waveforms and the order of waveforms are the same as those in Fig. 4, and therefore the description will be omitted.

[0108] In Figure 8, the synchronous PWM mode operation command M SY After the command is issued, at time t1, the output of the AND operator 512 in FIG. 7 becomes "true", the output of the third selector 518 is selected by the second selector 513a in FIG. 7, and the asynchronous carrier frequency command F CAS is the steady-state asynchronous carrier frequency F CAS1 , the asynchronous carrier frequency F output from the pseudorandom frequency generator 520. CAS2 , pseudorandom frequency F CAS2R or the lower limit of the asynchronous carrier frequency F CASLSpecifically, at time t5, the pseudo-random frequency F calculated by equation (12) is CAS2R is output, and at time t6, the lower limit of the asynchronous carrier frequency F CASL In Figure 8, F CAS2 =4800Hz, F CASL = 4500Hz, then from equation (12), F CAS2R This can be calculated as =(4800×4500) / (2×4500-4800)=5143Hz.

[0109] In addition, in FIG. 8, the upper limit value F CASU (e.g., 5500 Hz) and the lower limit of the asynchronous carrier frequency F CASL The range between (for example, 4500 Hz) and (for example, 4500 Hz) is the range of asynchronous carrier frequencies that are not reduced. On the other hand, the upper limit F CASU ' (e.g., 5250Hz) and the lower limit of the reduced asynchronous carrier frequency F CASL The range between ' and ' (e.g., 4750 Hz) is the range of asynchronous carrier frequencies restricted for pseudo-random use.

[0110] 8, at time t7, the output of the AND operator 517 in FIG. 7 becomes "true", and the third selector 518 in FIG. 7 selects the asynchronous carrier frequency F CAS2 is the interrupt frequency F CAS2 In the second embodiment, the first phase difference θ DAS is the switching phase θ t When the frequency is within one cycle, i.e., within 360 degrees, the upper limit F of the asynchronous carrier frequency, which is the original frequency range, is reached. CASU and the lower limit of the asynchronous carrier frequency F CASL and the asynchronous carrier frequency F CAS2 is recalculated. This results in the asynchronous carrier frequency F CAS2 From the calculation of, for example, the inverter frequency F INV , output voltage phase command θ V Even if there is a change in the inverter frequency F INV , output voltage phase command θV Based on the asynchronous carrier frequency F CAS2 As a result, the switching from the asynchronous carrier to the synchronous carrier is performed at the switching phase θ t This can be done smoothly and accurately.

[0111] Note that Figure 8 shows the interrupt frequency F calculated at time t7. CAS2 ' is the upper limit of the asynchronous carrier frequency F CASU ', the lower limit of the asynchronous carrier frequency, F CASL ' is used as an example, but is not limited to this example. CAS2 9. FIG. 9 is a second diagram illustrating the operation of the rotating machine control device 1a according to the second embodiment. As shown in FIG. 9, the interrupt frequency F CAS2 ' is the upper limit of the reduced asynchronous carrier frequency F CASU ' and the lower limit of the asynchronous carrier frequency F CASL ' and may be a value outside the range.

[0112] As described above, according to the rotating machine control device of the second embodiment, the frequency of the second asynchronous carrier wave is changed so as to alternate between the first frequency, the second frequency, and a second upper limit frequency that is higher than the first frequency and lower than the first upper limit frequency, or a second lower limit frequency that is lower than the first frequency and higher than the first lower limit frequency. The second frequency is calculated based on the relationship that an average period calculated by taking the arithmetic mean of the sum of periods that are the reciprocals of the second frequency and the first upper limit frequency is equal to a period that is the reciprocal of the first frequency. Alternatively, the second frequency is calculated based on the relationship that an average period calculated by taking the arithmetic mean of the sum of periods that are the reciprocals of the second frequency and the first lower limit frequency is equal to a period that is the reciprocal of the first frequency. By using the control method of the second embodiment, the frequency of the second asynchronous carrier wave is spread pseudo-randomly, thereby making it possible to reduce even-hour harmonics that may occur when the second asynchronous carrier wave is output.

[0113] Furthermore, in the rotating machine control device according to the second embodiment, the controller operates to recalculate the frequency of the second asynchronous carrier wave when the first phase difference falls within one cycle of the switching phase. This control calculation recalculates the frequency of the second asynchronous carrier wave based on the inverter frequency and output voltage phase after the change, even if there has been a fluctuation in the inverter frequency and output voltage phase since the calculation of the first frequency. This makes it possible to switch from the asynchronous carrier wave to the synchronous carrier wave smoothly and accurately at the switching phase.

[0114] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention. [Explanation of symbols]

[0115] 1,1a Rotating machine control device, 2 Rotating machine, 3 Voltage applicator, 4 Controller, 5,5a Asynchronous carrier frequency generator, 6 Modulation wave generator, 7 Carrier wave generator, 8 PWM pulse generator, 30a Transistor, 30b Diode, 30A, 30B, 30C Leg, 32, 33, 34 Connection point, 35a, 35b DC bus, 36 Power source, 300 Processor, 302 Memory, 303 Processing circuit, 304 Interface, 501, 502, 504, 505, 508, 509, 514 Arithmetic unit, 503 Decimal separator, 506, 510, 510a, 511, 511a, 515, 516 Comparator, 507 First selector, 512, 517 Logical AND operator, 513, 513a second selector, 518 third selector, 519 limit range reducer, 520 pseudorandom frequency generator.

Claims

1. a voltage applicator that generates a three-phase voltage to be applied to the rotating machine; a controller for controlling a voltage generating operation by the voltage applicator in an asynchronous pulse width modulation mode, which is an operation mode of a pulse width modulation method in which a carrier frequency is not synchronized with a voltage command frequency, and a synchronous pulse width modulation mode, which is an operation mode of a pulse width modulation method in which a carrier frequency is synchronized with a voltage command frequency; Equipped with the controller performs switching control to switch the operation mode from the asynchronous pulse width modulation mode to the synchronous pulse width modulation mode at an arbitrary switching phase; the controller calculates a frequency of a second asynchronous carrier wave to change the first asynchronous carrier wave being used in the asynchronous pulse width modulation mode to a second asynchronous carrier wave based on a first phase difference from a reference phase of a first asynchronous carrier wave having a steady-state asynchronous carrier wave frequency to the switching phase; During the switching control, by changing the first asynchronous carrier wave to the second asynchronous carrier wave, an instantaneous value of the second asynchronous carrier wave and an instantaneous value of the synchronous carrier wave used in the synchronous pulse width modulation mode match at the switching phase, and the sign of the slope of the second asynchronous carrier wave and the sign of the slope of the synchronous carrier wave match. A rotating machine control device characterized by:

2. When the calculated value of the frequency of the second asynchronous carrier wave is a first frequency, the controller repeats calculations so that the first frequency falls between a first upper limit frequency determined based on the frequency of the first asynchronous carrier wave and a first lower limit frequency determined based on the frequency of the first asynchronous carrier wave; The first frequency is commanded as the frequency of the second asynchronous carrier wave when the first frequency is within a range between the first lower limit frequency and the first upper limit frequency. The rotating machine control device according to claim 1 .

3. When the first frequency does not fall between the first upper limit frequency and the first lower limit frequency, the controller adds 120 degrees to the switching phase, and repeats the process of adding 120 degrees to the switching phase so that the first frequency falls between the first upper limit frequency and the first lower limit frequency.

3. The rotating machine control device according to claim 2.

4. During the switching control, the frequency of the second asynchronous carrier wave is changed so as to alternately vary among the first frequency, the second frequency, and a second upper limit frequency that is higher than the first frequency and lower than the first upper limit frequency, or a second lower limit frequency that is lower than the first frequency and higher than the first lower limit frequency, The second frequency is calculated based on a relationship in which an average period obtained by taking an arithmetic mean of the sum of periods that are reciprocals of the second frequency and the first upper limit frequency is equal to a period that is the reciprocal of the first frequency, or The second frequency is calculated based on the relationship that an average period calculated by the arithmetic mean of the sum of periods that are reciprocals of the second frequency and the first lower limit frequency is equal to a period that is the reciprocal of the first frequency.

4. The rotating machine control device according to claim 2 or 3.

5. When the first phase difference is within one period of the switching phase, The controller recalculates the frequency of the second asynchronous carrier.

5. The rotating machine control device according to claim 4.

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