Control device of power conversion device

Abstract

To provide a control device of a power conversion device capable of suppressing a torque error ratio caused by temperature fluctuations to an allowable value or less.SOLUTION: A power conversion device control device that drives an electric motor is equipped with a calculation device that calculates the output of the electric motor and the amount of loss change due to temperature change of the electric motor, sets a first torque estimation value based on the output of the electric motor and the rotational speed of the electric motor as the torque estimation value of the electric motor when the ratio of the amount of loss change to the output of the electric motor is smaller than the allowable torque error ratio of the electric motor, and otherwise sets a second torque estimation value based on the current of the electric motor and the rotor phase of the electric motor as the torque estimation value of the electric motor.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for a power conversion device. [Background technology]

[0002] There is known a control device that estimates the torque of a motor by some method and controls the motor based on the estimated torque. For example, Patent Document 1 describes a control device for a permanent magnet synchronous motor that switches between a low-speed torque estimator and a high-speed torque estimator according to the angular speed of the motor, and switches between torque estimators that can perform good torque estimation in both low and high angular speed rotational speed ranges of the motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-233199 A Summary of the Invention [Problem to be solved by the invention]

[0004] The control device described in Patent Document 1 does not have a mechanism for suppressing the torque error ratio due to the influence of temperature fluctuations (the difference between the torque command and the true torque value divided by the true torque value) below an allowable value, and it is necessary to determine the selection of the torque estimation unit and the switching conditions by trial and error.

[0005] An object of the present invention is to provide a control device for a power conversion device that can suppress a torque error ratio caused by the influence of temperature fluctuations to an allowable value or less. [Means for solving the problem]

[0006] A control device for a power conversion device according to one embodiment of the present invention is a control device for a power conversion device that drives an electric motor, and is equipped with a calculation device, which calculates the output of the electric motor and calculates a loss change amount due to a temperature change of the electric motor, and if the ratio of the loss change amount to the output of the electric motor is smaller than the allowable torque error ratio of the electric motor, a first torque estimation value based on the output of the electric motor and the rotational speed of the electric motor is used as the torque estimation value of the electric motor, and otherwise a second torque estimation value based on the current of the electric motor and the rotor phase of the electric motor is used as the torque estimation value of the electric motor. Effect of the Invention

[0007] According to the present invention, it is possible to provide a control device for a power conversion device that can suppress the torque error ratio caused by the influence of temperature fluctuation to a tolerable value or less. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram illustrating a hardware configuration of a control device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram for explaining the operation of the control device according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a block diagram showing the configuration of the torque command correction unit. [Figure 4] FIG. 4 is an explanatory diagram for explaining the correction of the torque command by the torque command correcting unit. [Diagram 5] FIG. 5 is a block diagram showing the configuration of the vector control unit. [Figure 6] FIG. 6 is a flowchart of a control process executed by the control device according to the first embodiment. [Figure 7] FIG. 7 is a schematic diagram showing an electric vehicle equipped with a control device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A control device 1 for a power converter 3 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6. FIG.

[0010] FIG. 1 is a block diagram showing a hardware configuration of a control device 1 according to a first embodiment of the present invention. The control device 1 is composed of a computer including an arithmetic device 11 such as a central processing unit (CPU), a micro processing unit (MPU), a digital signal processor (DSP), etc., a non-volatile memory 12 such as a read only memory (ROM), a flash memory, a hard disk drive, etc., a volatile memory 13 called a random access memory (RAM), an input / output interface 14, and other peripheral circuits. These hardware components work together to operate software and realize a plurality of functions. The controller may be composed of one computer or a plurality of computers. The arithmetic device 11 may be an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc.

[0011] The non-volatile memory 12 stores programs capable of executing various calculations. In other words, the non-volatile memory 12 is a storage medium (storage device) capable of reading programs that realize the functions of this embodiment. The volatile memory 13 is a storage medium (storage device) that temporarily stores the results of calculations performed by the calculation device 11 and signals input from the input / output interface 14. The calculation device 11 is a device that loads the programs stored in the non-volatile memory 12 into the volatile memory 13 and executes calculations, and performs predetermined calculation processing on data taken from the input / output interface 14, the non-volatile memory 12, and the volatile memory 13 in accordance with the programs.

[0012] The control device 1 is connected to a torque command input device 2 and a power conversion device 3. The torque command input device 2 is a device that drives the electric motor 4 at a desired torque using the control device 1. The power conversion device 3 is a device that drives the electric motor 4. The torque command input device 2 outputs a torque command, which will be described later, to the control device 1. The control device 1 outputs a plurality of gate signals g, which will be described later, to the power conversion device 3 based on the torque command input from the torque command input device 2. The power conversion device 3 drives the electric motor 4 based on the plurality of gate signals g, which will be described later, input from the control device 1.

[0013] An input section of the input / output interface 14 converts signals input from various devices (such as the torque command input device 2) into data that can be calculated by the arithmetic device 11. An output section of the input / output interface 14 generates an output signal according to the calculation result by the arithmetic device 11, and outputs the signal to various devices (such as the power conversion device 3).

[0014] 2 is a block diagram for explaining the operation of the control device 1 according to the first embodiment of the present invention. The control device 1 includes a motor output calculation unit 21, a first torque estimation unit 22, a second torque estimation unit 23, a switching unit 24, a loss change amount calculation unit 25, a torque command correction unit 26, a vector control unit 27, and a PWM control unit 28.

[0015] Each of these parts is connected to the U-phase, V-phase, and W-phase voltages v u , v v , v w , the U-phase, V-phase, and W-phase currents of the power converter 3 i u , i v , i w , the frequency ω of the motor 4, and the rotor phase θ of the motor 4. These values ​​are obtained as current values ​​from the power conversion device 3 and the motor 4 by sensors (not shown) and are supplied to each part of the control device 1.

[0016] The motor output calculation unit 21 includes an inner product calculation unit 21a, an addition / subtraction unit 21b, a loss calculation unit 21c, an inner product calculation unit 21d, and a copper loss calculation unit 21e. The motor output calculation unit 21 calculates the U-phase, V-phase, and W-phase voltages vu , v v , v w , the U-phase, V-phase, and W-phase currents of the power converter 3 i u , i v , i w , and the frequency ω of the motor 4, the output P of the motor 4 out Calculate the following.

[0017] The inner product calculation unit 21a calculates the U-phase, V-phase, and W-phase voltages v u , v v , v w and the U-phase, V-phase, and W-phase currents i u , i v , i w The input P of motor 4 is the dot product of in The loss calculation unit 21c calculates "aω m i n + b" LI That is, the loss P LI is the current multiplier of motor 4 i n and the frequency multiplier ω m The loss P LI For example, m is eddy current loss or hysteresis loss. According to Steinmetz's empirical formula, m = 2, n = 2 for eddy current loss and m = 1, n = 1.6 for hysteresis loss. The coefficients a and b are identified by, for example, calibration. Loss P LI Other possible losses include AC copper loss and mechanical loss, both of which are expressed as "aω m i n Calibration is performed by, for example, attaching a sensor capable of measuring losses to the power converter 3, the motor 4, etc., and measuring the frequency ω of the motor 4 and the U-phase, V-phase, and W-phase currents i u , i v , i w The loss is measured while changing each of a, b, m, and n, and the difference with the actual measurement is small.

[0018] In Figure 2, one loss, "aωm i n Although only "aω + b" is presented, multiple losses can be calculated in the same way. Or the total loss value and "aω m i n In this way, the motor output calculation unit 21 can calculate part or all of the eddy current loss, hysteresis loss, AC copper loss, and mechanical loss from P LI The inner product calculation unit 21d calculates the U-phase, V-phase, and W-phase currents i u , i v , i w Squared i 2 The copper loss calculation unit 21e calculates the copper loss "P LR = Ri 2 Here, R is the winding resistance value of the motor 4. The addition / subtraction unit 21b calculates the output P of the motor 4 using the following equation (1): out Calculate the following. P out = P in -P LI -P LR …(1) Equation (1) holds true because the gap between the input and output to the motor 4 is the loss of the motor 4.

[0019] The first torque estimation unit 22 calculates the first torque estimation value τ1 by the following equation (2). out by the frequency ω (rotation speed) of the electric motor 4. τ1 = P out / ω …(2) Equation (2) expresses the output P of motor 4. out is the product of torque and frequency.

[0020] The second torque estimation unit 23 includes a three-phase to two-phase conversion unit 23a and a torque model 3b. The second torque estimation unit 23 estimates the U-phase, V-phase, and W-phase currents i u , i v , i w and the rotor phase θ of the motor 4. The three-phase to two-phase conversion unit 23a converts the U-phase, V-phase, and W-phase currents iu , i v , i w The d-axis and q-axis currents i d , i q The second torque estimation unit 23 calculates the second torque estimated value τ2 by a torque model 3b expressed by the following equation (3). τ2 = P m (K e +(L d -L q )i d )i q …(3) Here, P m is the number of pole pairs, K e is the induced voltage coefficient, L d is the d-axis inductance, L q is the q-axis inductance. In other words, the second torque estimate τ2 is calculated by using the rotor phase θ of the motor 4 to calculate the U-phase, V-phase, and W-phase currents i u , i v , i w (three-phase AC current) to the d-axis and q-axis currents i d , i q Then, the d-axis and q-axis currents i d , i q and the inductance L of motor 4 d , L q and the induced voltage coefficient K of motor 4 e It is a value calculated based on the above.

[0021] The switching unit 24 includes a loss change ratio calculation unit 24a, a comparison unit 24b, and a switch 24c. The switching unit 24 selects either the first torque estimation value τ1 or the second torque estimation value τ2 as the torque estimation value τ est The loss change ratio calculation unit 24a outputs the output P out The change in loss of motor 4 due to temperature fluctuation ΔP L " ratio Δτ L In the following description, this ratio Δτ L The ratio of loss change Δτ L It is called.

[0022] The comparison unit 24b calculates the ratio of the loss change amount Δτ L Absolute value of |ΔτL | and a given allowable torque error ratio Δτ MAX and compare the absolute value |Δτ L If | is smaller, the flag F is output as Yes, and otherwise as No. The switch 24c outputs the first torque estimate value τ1 when the flag F is Yes, and outputs the second torque estimate value τ2 when the flag F is No. est The output is as follows:

[0023] The loss change amount calculation unit 25 includes an inner product calculation unit 25a and a copper loss change amount calculation unit 25b. When the amount of change in the winding resistance value R during temperature change (for example, when the temperature changes from the minimum temperature to the maximum temperature in the specifications of the motor 4) is the winding resistance change ΔR, the loss change amount calculation unit 25 calculates the amount of change in loss of the motor 4 during temperature change ΔP L = ΔRi 2 " is output. In other words, the loss change amount ΔP L is the change in winding resistance R due to the temperature change of the motor 4, ΔR, and the square of the current of the motor 4, i 2 The winding resistance variation ΔR is a value measured or estimated in advance and stored in the non-volatile memory 12 or the like, and is read out from the non-volatile memory 12 or the like as required.

[0024] 3 is a block diagram showing the configuration of the torque command correction unit 26. The torque command correction unit 26 calculates the torque estimation value τ est Based on the torque command τ * The corrected value is used as the correction torque command τ ** The torque command correction unit 26 includes a low-pass filter 26a and a PI control unit 26b. The low-pass filter 26a with a time constant T simulates the response of torque control. Therefore, the output τ LPF * represents an ideal torque response. The torque command correction unit 26 uses the output τ LPF * and the torque estimate τ est The difference between the torque command and the torque command is input to the PI control unit 26b. * Add to the correction torque command τ **That is, the correction torque command τ ** is the torque estimate τ est Feedback, torque command τ * is determined by two-degree-of-freedom control with

[0025] FIG. 4 shows the torque command τ * 4 is an explanatory diagram for explaining the correction content of the torque command τ. The horizontal axis of FIG. 4 indicates time, and the vertical axis indicates a torque value. For the sake of explanation, it is assumed that the torque command correction unit 26 is disabled until time t1 shown in FIG. 4, and that the torque command correction unit 26 is enabled after time t1. In addition, over the entire time axis shown in FIG. 4, the torque command τ * is assumed to be constant.

[0026] In Fig. 4, the torque estimate τ est (and the actual torque τ of the electric motor 4) is shown with a solid line, and the correction torque command τ ** As described above, the torque command correction unit 26 is disabled until time t1, so the torque command τ * and the correction torque command τ ** When the torque command correction unit 26 is enabled at time t1, the output τ LPF * is the torque estimate τ est Since the output of the PI control unit 26b is greater than ** As a result, the actual torque τ and the estimated torque τ est also increases, and this continues until the torque error ratio Δτ in the following equation (4) becomes zero. Δτ = (τ ‐ τ * ) / τ * …(4) Therefore, as long as there is no error in the torque estimation, the torque error ratio Δτ will eventually be stabilized at zero through the correction by the torque command corrector 26.

[0027] 5 is a block diagram showing the configuration of the vector control unit 27. The vector control unit 27 controls the correction torque command τ **, the U-phase, V-phase, and W-phase currents of the power converter 3 i u , i v , i w , and the U-phase, V-phase, and W-phase voltage commands v u * , v v * , v w * The vector control unit 27 includes a torque / current command conversion unit 27a, a current control unit 27b, a three-phase to two-phase conversion unit 27c, and a two-phase to three-phase conversion unit 27d.

[0028] The torque-current command converter 27a converts the correction torque command τ ** The d-axis and q-axis current commands i d * , i q * The three-phase to two-phase converter 27c converts the U-phase, V-phase, and W-phase currents i u , i v , i w The d-axis and q-axis currents i d , i q The current control unit 27b converts the d-axis and q-axis current commands i d * , i q * and d-axis and q-axis currents i d , i q Based on this, the d-axis and q-axis voltage commands v d * , v q * The two-phase to three-phase conversion unit 27d calculates the d-axis and q-axis voltage commands v d * , v q * The U-phase, V-phase, and W-phase voltage commands v u * , v v * , v w * Convert to.

[0029] The PWM control unit 28 controls the U-phase, V-phase, and W-phase voltage commands v u * , vv * , v w * Based on this, the power converter 3 is controlled by outputting a plurality of gate signals g (i.e., PWM control signals) to the power converter 3. As a result, the motor 4 is supplied with U-phase, V-phase, and W-phase voltages v u , v v , v w is applied, and the U-phase, V-phase, and W-phase currents i u , i v , i w flows, and an actual torque τ is generated.

[0030] 6 is a flowchart of a control process executed by the control device 1 according to the first embodiment. In step S80, the motor output calculation unit 21 calculates the U-phase, V-phase, and W-phase voltages v u , v v , v w , the U-phase, V-phase, and W-phase currents of the power converter 3 i u , i v , i w , and the frequency ω of the motor 4, the output P of the motor 4 out In step S90, the loss change amount calculation unit 25 calculates the loss change amount ΔP L In step S100, the switching unit 24 calculates the output P of the motor 4 calculated in step S80. out and the loss change amount ΔP of the electric motor 4 during the temperature change calculated in step S90 L Using the loss change ratio Δτ L In step S110, the switching unit 24 calculates the ratio Δτ of the loss change amount calculated in step S100. L Absolute value of |Δτ L | and a given allowable torque error ratio Δτ MAX and determine whether the former is smaller than the latter. L | is the allowable torque error ratio Δτ MAX If so, the process proceeds to step S120.

[0031] In step S120, the first torque estimation unit 22 calculates the first torque estimate value τ1 by the above-mentioned equation (2). In step S130, the switching unit 24 switches the first torque estimate value τ1 calculated in step S120 to the torque estimate value τ est After that, the process proceeds to step S160.

[0032] On the other hand, in step S110, the absolute value |Δτ L | is the allowable torque error ratio Δτ MAX If so, the process proceeds to step S140. In step S140, the second torque estimation unit 23 calculates the second torque estimation value τ2 by the above-mentioned equation (3). In step S150, the switching unit 24 switches the second torque estimation value τ2 calculated in step S140 to the torque estimation value τ est After that, the process proceeds to step S160.

[0033] In step S160, the torque command correction unit 26 calculates the torque estimation value τ est Based on the torque command τ * The corrected value is used as the correction torque command τ ** In step S170, the vector control unit 27 outputs the correction torque command τ ** , the U-phase, V-phase, and W-phase currents of the power converter 3 i u , i v , i w , and the U-phase, V-phase, and W-phase voltage commands v u * , v v * , v w * In step S180, the PWM control unit 28 calculates the U-phase, V-phase, and W-phase voltage commands v u * , v v * , v w * Based on this, the control circuit 10 outputs a plurality of gate signals g to the power conversion device 3 to control the power conversion device 3.

[0034] As described above, if there is no error in the torque estimation, the torque error ratio Δτ will eventually become zero by the torque command correction unit 26. Since the calculation of the second torque estimation value τ2 by the second torque estimator 23 is affected by a detection error of the rotor phase θ of the electric motor 4, it is desirable to use the first torque estimation value τ1 calculated by the first torque estimator 22 as much as possible. However, the calculation of the first torque estimation value τ1 by the first torque estimator 22 is affected by the copper loss P LR Since the winding resistance value R used in the calculation of is affected by temperature fluctuations, the torque error ratio Δτ does not become zero. In other words, an error occurs in the first torque estimate τ1 due to temperature fluctuations. In other words, a non-zero torque error ratio Δτ occurs in the first torque estimate τ1 due to temperature fluctuations.

[0035] The control device 1 according to the first embodiment uses the switching unit 24 and the loss change amount calculation unit 25 to set the torque error ratio Δτ due to temperature fluctuation to at most the allowable torque error ratio Δτ MAX The principle of this operation is as follows. (Operation principle 1) The comparator 24b and the switch 24c are used to generate "|Δτ L | < Δτ MAX The first torque estimation unit 22 is applied only in the case of ". (Operation Principle 2) The torque error ratio Δτ is expressed by the following equation (5) due to the effect of the torque command corrector 26. Δτ = (τ - τ * ) / τ * = (τ - τ est ) / τ est …(5) Here, in the application range of the first torque estimation unit 22, "τ est = τ1". Furthermore, from the above equations (1) and (2), the following equation (6) holds. τ est = τ1= (P in -P LI -P LR ) / ω …(6) Similarly, the following equation (7) holds true for the actual torque τ. τ = (P in -PLI -P LR -ΔP L ) / ω …(7) By substituting equations (6) and (7) into equation (5), we obtain the following equation (8). Δτ = (-ΔP L ) / (P in -P LI -P LR ) = -ΔP L / P OUT …(8) From the above, we can see that Δτ = -Δτ L "It can be seen that (Operation principle 3) From (1) and (2) above, "|Δτ L | < Δτ MAX "That is, "|Δτ| < Δτ MAX " The first torque estimator 22 is applied only when the torque error ratio Δτ due to temperature fluctuation is equal to or smaller than the allowable torque error ratio Δτ MAX If it does, the torque estimation unit 23 automatically switches to the second torque estimation unit 23. The second torque estimation unit 23 is affected by the detection error of the rotor phase θ of the motor 4, but is not affected by the winding resistance fluctuation ΔR due to temperature fluctuation, and is therefore robust against temperature fluctuations.

[0036] According to the above-described embodiment, the following advantageous effects are obtained.

[0037] (1) The calculation device 11 calculates the output P of the motor 4. out The loss change amount ΔP due to the temperature change of the motor 4 is calculated. L Calculate the output P of motor 4 out Ratio of loss change to Δτ L Absolute value of |Δτ L | is the allowable torque error ratio Δτ of motor 4 MAX If it is smaller than the output P out and the frequency ω (rotation speed) of the electric motor 4 as the torque estimate value τ est In other cases, the U-phase, V-phase, and W-phase currents i u , i v , iw The second torque estimate τ2 based on (the current of the motor 4) and the rotor phase θ of the motor 4 is calculated as the torque estimate τ est In this way, the torque error ratio caused by the influence of temperature fluctuations can be suppressed to a tolerable value or less.

[0038] (2) The calculation device 11 calculates the U-phase, V-phase, and W-phase voltages v u , v v , v w and the U-phase, V-phase, and W-phase currents i u , i v , i w (output of the power converter 3) and the input P of the motor 4 in The input P of the motor 4 in Loss P of motor 4 LI The output P of motor 4 is calculated by subtracting out In this way, the output P of the motor 4 is calculated by taking into account the loss of the motor 4 such as copper loss. out can be calculated.

[0039] (3) The calculation device 11 calculates the current multiplier i of the electric motor 4. n and the frequency multiplier ω m The product aω m i n The loss change amount ΔP is calculated based on the value obtained by adding the offset value b to L In this way, the copper loss, which accounts for a large part of the influence of temperature fluctuations, can be calculated with a simple calculation. Since only a simple calculation is required, the amount of calculation is reduced, and power consumption can be reduced.

[0040] (4) The calculation device 11 calculates the winding resistance variation ΔR, which is the amount of change in the winding resistance R due to the temperature change of the motor 4, and the square of the current of the motor 4 i 2 The product of this and the loss change ΔP L In this way, the loss change amount ΔP L can be calculated with a low amount of calculation.

[0041] (5) The arithmetic unit 11 calculates the output P of the motor 4. outThe first torque estimation value τ1 is determined by dividing the above by the frequency ω (rotation speed) of the electric motor 4. By doing so, when the temperature does not fluctuate significantly, the first torque estimator 22 can stably obtain a highly accurate torque estimation value.

[0042] (6) The calculation device 11 calculates the U-phase, V-phase, and W-phase currents i u , i v , i w (three-phase AC current) to the d-axis and q-axis currents i d , i q and converts the d-axis and q-axis currents i d , i q and the d-axis inductance L of motor 4 d and the q-axis inductance L q and the induced voltage coefficient K of motor 4 e The second torque estimation unit 23 calculates the second torque estimation value τ2 based on the above. Since this is done, when the temperature fluctuation is severe, the second torque estimation unit 23 can stably obtain a highly accurate torque estimation value.

[0043] (7) The arithmetic unit 11 calculates the torque command τ * The torque estimate τ of motor 4 est The torque command τ ** Based on this, the gate signal g (PWM control signal) is output to the power conversion device 3. Since this is done, the power conversion device 3 can be stably controlled to a desired torque.

[0044] (8) The calculation device 11 calculates the torque estimate τ est Feedback, torque command τ * In this way, even when the first torque estimator 22 and the second torque estimator 23 are switched, the estimation result does not become unstable, and high estimation accuracy can be steadily maintained.

[0045] A control device according to a second embodiment of the present invention will be described with reference to Fig. 7. Note that configurations that are the same as or equivalent to those described in the first embodiment are given the same reference symbols, and differences will be mainly described.

[0046] 7 is a schematic diagram showing an electric vehicle 200 equipped with a control device 100 according to the second embodiment. The electric vehicle 200 is an electric vehicle using an electric motor 4 as a drive source. That is, the electric vehicle 200 has four electric motors 4, and each electric motor 4 is connected to the axle of four wheels 201 equipped on the electric vehicle 200. For each of the four electric motors 4, a corresponding control device 100 and power conversion device 3 are provided.

[0047] The electric vehicle 200 is equipped with a control device (hereinafter, also referred to as an electric vehicle control device) 202 that controls each part of the electric vehicle 200. The electric vehicle control device 202 corresponds to the torque command input device 2 described in the first embodiment. That is, the electric vehicle control device 202 receives a torque command τ1 for accelerating and decelerating the electric vehicle 200. * , τ * , τ3 * , and τ * to each of the four control devices 100. Since the electric vehicle 200 is operated under a wide range of conditions from low speed to high speed, the temperature of the electric motor 4 is constantly fluctuating. MAX Therefore, the electric vehicle 200 can be accelerated and decelerated stably.

[0048] The following modified examples are also within the scope of the present invention, and it is possible to combine the configurations shown in the modified examples with the configurations described in the above-mentioned embodiments, to combine the configurations described in the different embodiments above, or to combine the configurations described in the different modified examples below.

[0049] <Variation 1> The operation of the torque command correction unit 26 may be different from that described in FIG. est This is the correction torque command τ **Even in this case, it is possible to steadily estimate torque with high accuracy. However, there is a risk that the output will oscillate when switching between the first torque estimating section 22 and the second torque estimating section 23, and become unstable in a transient state. <Variation 2> Input P of motor 4 in may be obtained by the product of the input to the power conversion device 3 and the power conversion efficiency by the power conversion device 3, instead of the dot product of the U-phase, V-phase, and W-phase voltages vu, vv, and vw of the power conversion device 3 and the U-phase, V-phase, and W-phase currents iu, iv, and iw of the power conversion device 3.

[0050] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0051] 1,100...control device, 2...torque command input device, 3...power conversion device, 4...electric motor, 11...arithmetic device, 12...non-volatile memory, 13...volatile memory, 14...input / output interface, 21...electric motor output calculation unit, 22...first torque estimator, 23...second torque estimator, 24...switching unit, 25...loss change amount calculation unit, 26...torque command correction unit, 27...vector control unit, 28...PWM control unit, 200...electric vehicle, 201...wheel, 202...electric vehicle control device

Claims

1. A control device for a power conversion device that drives an electric motor, A computing device is provided, The computing device includes: Calculating the output of the electric motor; A loss change amount due to a temperature change of the electric motor is calculated. When a ratio of the loss change amount to the output of the motor is smaller than an allowable torque error ratio of the motor, a first torque estimation value based on the output of the motor and the rotation speed of the motor is set as the torque estimation value of the motor, and otherwise, a second torque estimation value based on the current of the motor and the rotor phase of the motor is set as the torque estimation value of the motor. A control device for a power conversion device.

2. The control device for a power conversion device according to claim 1, The calculation device sets the product of the input and the conversion efficiency of the power conversion device or the output of the power conversion device as the input to the electric motor, and sets a value obtained by subtracting a loss of the electric motor from the input to the electric motor as the output of the electric motor. A control device for a power conversion device.

3. The power conversion device control device according to claim 2, The calculation device calculates the loss change amount based on a value obtained by adding an offset value to a product of a multiplier of a current of the motor and a multiplier of a frequency of the motor. A control device for a power conversion device.

4. The control device for a power conversion device according to claim 1, the calculation device determines the amount of loss change as a product of an amount of change in winding resistance value due to a temperature change of the motor and a square of a current of the motor; A control device for a power conversion device.

5. The control device for a power conversion device according to claim 1, The calculation device sets a value obtained by dividing an output of the electric motor by a rotation speed of the electric motor as the first torque estimation value. A control device for a power conversion device.

6. The control device for a power conversion device according to claim 1, the calculation device performs three-phase to two-phase conversion of a three-phase AC current of the motor into d-axis and q-axis currents using a rotor phase of the motor, and calculates the second torque estimation value based on the d-axis and q-axis currents, an inductance of the motor, and an induced voltage coefficient of the motor. A control device for a power conversion device.

7. The control device for a power conversion device according to claim 1, The arithmetic device corrects a torque command input to the control device based on a torque estimate value of the electric motor, and outputs a PWM control signal to the power conversion device based on the corrected torque command. A control device for a power conversion device.

8. The control device for a power conversion device according to claim 7, The arithmetic device is a two-degree-of-freedom control system in which the torque estimation value is fed back and the torque command is fed forward. A control device for a power conversion device.

9. The control device for a power conversion device according to claim 1, A torque command is input from a control device of an electric vehicle using the electric motor as a drive source. A control device for a power conversion device.

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