Control device for power conversion device

Abstract

A control device for a power conversion device that drives a motor is provided with a calculation device that calculates an output of the motor and calculates a loss change amount due to a change in temperature of the motor. When the ratio of the loss change amount with respect to the output of the motor is less than the allowable torque error ratio of the motor, a first torque estimation value based on the output of the motor and the rotational speed of the motor is used as the torque estimation value of the motor, and in other cases, a second torque estimation value based on the output of the motor and the rotational speed of the motor is used as the torque estimation value of the motor. A second torque estimation value based on the current of the motor and the rotor phase of the motor is used as the torque estimation value of the motor.

Description

Technical Field

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

[0002] A control device is known that estimates the torque of an electric motor using a certain 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. The device switches between a low-speed torque estimating unit and a high-speed torque estimating unit, each capable of performing torque estimation effectively in both the low-speed and high-speed ranges of the motor's angular velocity. The torque estimating unit switches between a low-speed torque estimating unit and a high-speed torque estimating unit according to the motor's angular velocity. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-233199. Summary of the Invention Problems 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 (the value obtained by dividing the difference between the torque command and the torque true value by the torque true value) caused by temperature fluctuations to below an allowable value, and repeated trial and error are required to determine the selection of the torque estimation unit and the switching conditions.

[0005] An object of the present invention is to provide a control device for a power conversion device capable of suppressing a torque error ratio due to the influence of temperature fluctuation to a permissible value or less. Technical means to solve the problem

[0006] According to one embodiment of the present invention, a control device for a power conversion device is a control device for a power conversion device that drives an electric motor, which includes a calculation device that calculates the output of the electric motor and the loss change caused by the temperature change of the electric motor. When the ratio of the loss change to the output of the electric motor is less 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. In other cases, 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. Effects 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 a torque error ratio due to the influence of temperature fluctuation to a permissible value or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1This is a block diagram schematically showing the hardware configuration of the control device according to the first embodiment of the present invention. Figure 2 This is a block diagram for explaining the operation of the control device according to the first embodiment of the present invention. Figure 3 This is a block diagram showing the configuration of a torque command correction unit. Figure 4 This is an explanatory diagram for explaining the correction content of the torque command by the torque command correction unit. Figure 5 This is a block diagram showing the configuration of a vector control unit. Figure 6 This is a flowchart of a control process executed by the control device according to the first embodiment of the present invention. Figure 7 Schematic diagram showing an electric vehicle equipped with a control device according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0009] Reference Figures 1 to 6 , a control device 1 of a power conversion device 3 according to an embodiment of the present invention will be described.

[0010] Figure 1 This is a block diagram schematically showing the hardware structure of the control device 1 of the first embodiment of the present invention. The control device 1 is composed of a computer, which has a computing device 11 such as a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), a non-volatile memory 12 such as a ROM (Read Only Memory), a flash memory, a hard disk drive, a volatile memory 13 such as a so-called RAM (Random Access Memory), an input and output interface 14, and other peripheral circuits. These hardware components work together to run software and realize various functions. In addition, the controller can be composed of either one computer or multiple computers. In addition, as the computing device 11, an ASIC (application specific integrated circuit), an FPGA (Field Programmable Gate Array), etc. can be used.

[0011] The non-volatile memory 12 stores programs that can perform various calculations. Specifically, the non-volatile memory 12 is a storage medium (storage device) that can read the programs that implement the functions of this embodiment. The volatile memory 13 is a storage medium (storage device) that temporarily stores the calculation results performed by the calculation device 11 and the 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 to perform calculations. It then performs prescribed calculations on data obtained from the input / output interface 14, the non-volatile memory 12, and the volatile memory 13 according to 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 drives the motor 4 at a desired torque using the control device 1. The power conversion device 3 drives the motor 4. The torque command input device 2 outputs a torque command (described later) to the control device 1. Based on the torque command input from the torque command input device 2, the control device 1 outputs multiple gate signals g (described later) to the power conversion device 3. The power conversion device 3 drives the motor 4 based on the multiple gate signals g input from the control device 1.

[0013] The 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 calculation device 11. Furthermore, the output section of the input / output interface 14 generates output signals corresponding to the calculation results of the calculation device 11 and outputs these signals to various devices (such as the power conversion device 3).

[0014] Figure 2 This is a block diagram for explaining the operation of control device 1 according to the first embodiment of the present invention. 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 calculation unit 25, a torque command correction unit 26, a vector control unit 27, and a PWM control unit 28.

[0015] The U-phase, V-phase, and W-phase voltages v of the power converter 3 are supplied to these components. u , v v , v w , U-phase, V-phase, and W-phase currents i of the power conversion device 3 u ,i v ,i w , the frequency ω of the motor 4, and the rotor phase θ of the motor 4. These values ​​are constantly acquired from the power converter 3 and the motor 4 by sensors (not shown) and supplied to various components of the control device 1.

[0016] The motor output calculation unit 21 includes an inner product calculation unit 21a, an addition and 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 output voltage v of the U-phase, V-phase, and W-phase voltages v of the power converter 3 based on the output voltage v of the U-phase, V-phase, and W-phase voltages v of the power converter 3. u , v v , v w , U-phase, V-phase, and W-phase currents i of the power conversion device 3 u ,i v ,i w , and the frequency ω of the motor 4, calculate the output P of the motor 4 out .

[0017] The inner product calculation unit 21a calculates the U-phase, V-phase, and W-phase voltages v of the power conversion device 3. u 、v v 、v w and the U-phase, V-phase, and W-phase currents i of the power converter 3 u 、i v 、i w The inner product of the motor 4 is the input P in The loss calculation unit 21c uses coefficients a and b to calculate the loss of m i n +b" represents the loss P LI That is, the loss P LI is the multiplier i of the current in the motor 4 n and the frequency multiplier ω m Add the offset value b to the product of LI For example, it is eddy current loss or hysteresis loss. According to Steinmetz's experimental formula, if it is eddy current loss, then "m = 2, n = 2", if it is hysteresis loss, then "m = 1, n = 1.6". The coefficients a and b in this case are identified by calibration, for example. As the loss P LI In addition, AC copper loss or mechanical loss can also be considered, both of which are expressed as "aω m i n +b" and the actual measured value are minimized. Calibrate a, b, m, and n. For example, when a sensor capable of measuring loss is mounted on the power converter 3 or the motor 4, the frequency ω of the motor 4 and the U-phase, V-phase, and W-phase currents i of the power converter 3 are adjusted. u 、i v 、i w The loss is measured by changing each of them and searching for a, b, m, and n where the difference from the measured value becomes small.

[0018] In addition, Figure 2 Although only one loss "aω" is shown m i n+ b", but multiple losses can be calculated in the same way. Alternatively, the total loss value can be made equal to "aω m i n +b" is calibrated in such a way that the error is minimized. The motor output calculation unit 21 thus uses part or all of the eddy current loss, hysteresis loss, AC copper loss, and mechanical loss as P. LI The inner product calculation unit 21d calculates the U-phase, V-phase, and W-phase currents i u 、i v 、i w The square of 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 adding and subtracting unit 21b calculates the output P of the motor 4 by the following formula (1): out . P out =P in -P LI -P LR …(1) The formula (1) is established based on the fact that the difference between the input and output to the electric motor 4 is the loss of the electric motor 4 .

[0019] The first torque estimation unit 22 calculates the first torque estimation value τ1 according to the following equation (2). That is, the first torque estimation value τ1 is the output of the motor 4 Pout The value obtained by dividing by the frequency ω (rotation speed) of the electric motor 4. τ1=P out / ω…(2) Formula (2) is based on the output P of the motor 4 out It is the product of torque and frequency.

[0020] The second torque estimating unit 23 includes a three-phase to two-phase converter 23a and a torque model 3b. The second torque estimating unit 23 calculates the torque of the U-phase, V-phase, and W-phase currents i of the power converter 3. u 、i v 、i w The second torque estimation value τ2 is calculated using 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 i of the power converter 3 using the rotor phase θ of the motor 4. u 、i v 、i w Converted to d-axis and q-axis current i d ,i q The second torque estimating unit 23 calculates a second torque estimated value τ2 using a torque model 3b represented by the following equation (3). τ2=P m (K e+(L d -L q )i d )i q …(3) Here, P m is the pole logarithm, K e is the induced electromotive force coefficient, L d is the d-axis inductance, L q That is, the second torque estimation value τ2 is a value obtained by using the rotor phase θ of the motor 4 to calculate the U-phase, V-phase, and W-phase currents i of the motor 4. u 、i v 、i w (Three-phase AC current) is converted into two-phase d-axis and q-axis current i d ,i q , then based on the d-axis and q-axis current i d ,i q , the inductance L of the motor 4 d , L q And the induced electromotive force coefficient K of the motor 4 e And calculated.

[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 uses one of the first torque estimated value τ1 and the second torque estimated value τ2 as the torque estimated value τ est Output. The loss change ratio calculation unit 24a calculates the loss change ΔP of the motor 4 when the temperature changes. L "Relative to the output P of motor 4 out The ratio Δτ L In the following description, the ratio Δτ is L It is called the ratio of loss change Δτ L .

[0022] The comparison unit 24b calculates the ratio Δτ of the loss change amount L The absolute value of |Δτ L | Error rate Δτ from the specified allowable torque MAX For comparison, in absolute value |Δτ L When the value of |is smaller, the flag F is output as Yes, and in other cases it is output as No. The switch 24c outputs the first torque estimated value τ1 when the flag F is Yes, and outputs the second torque estimated value τ2 when it is No, as the torque estimated value τ est .

[0023] The loss variation calculation unit 25 includes an inner product calculation unit 25a and a copper loss variation calculation unit 25b. When the variation of the winding resistance value R during temperature fluctuation (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 variation ΔR, the loss variation calculation unit 25 outputs the "loss variation ΔP of the motor 4 during temperature fluctuation". L =ΔRi 2 ". In other words, the loss change ΔP L = The change in winding resistance R due to the temperature change of the motor 4 ΔR and the square of the current i of the motor 4 2 The winding resistance variation ΔR is a value measured or estimated in advance and stored in the nonvolatile memory 12 or the like, and is read from the nonvolatile memory 12 or the like as needed.

[0024] Figure 3 : is a block diagram showing the configuration of the torque instruction correction unit 26. The torque instruction correction unit 26 is based on the torque estimated value τ est Corrected torque command τ * The corrected value is used as the corrected torque instruction τ ** Output. The torque instruction 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 the torque control. Therefore, the output τ of the low-pass filter 26a is LPF * The torque instruction correction unit 26 converts the output τ of the low-pass filter 26a into LPF * and torque estimated value τ est The difference is input to the PI control unit 26b, and its output is added to the torque command τ * As the correction torque instruction τ ** Output. That is, the corrected torque command τ ** By using the torque estimation value τ est As feedback, the torque command τ * Determined as a two-degree-of-freedom control for feedforward.

[0025] Figure 4 It is used to explain the torque instruction τ by the torque instruction correction unit 26. * An illustration of the revised contents. Figure 4 The horizontal axis represents time, and the vertical axis represents torque value. Figure 4 Before the time t1 shown in FIG. , the torque instruction correction unit 26 is invalidated, and after the time t1, the torque instruction correction unit 26 is validated. Figure 4 On the entire time axis shown, the torque command τ * Keep it constant.

[0026] exist Figure 4 In the figure, the solid line indicates the torque estimated value τ. est (and the actual torque τ of the motor 4), the dotted line represents the corrected torque command τ ** As described above, the torque instruction correction unit 26 is disabled before time t1. Therefore, before time t1, the torque instruction τ * and the corrected torque command τ ** When the torque instruction correction unit 26 is enabled at time t1, the output τ of the low-pass filter 26a is LPF * Greater than the estimated torque value τ est , so the output of the PI control unit 26b is positive, and the corrected torque instruction τ ** As a result, the actual torque τ and the torque estimate τ est This process will continue until the torque error ratio Δτ of 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 is eventually stabilized at zero by the correction performed by the torque command correction unit 26 .

[0027] Figure 5 τ is a block diagram showing the configuration of the vector control unit 27. The vector control unit 27 corrects the torque command τ based on the torque command τ. ** , U-phase, V-phase, and W-phase currents i of the power conversion device 3 u ,i v ,i w , and the rotor phase θ of the motor 4, calculate the U-phase, V-phase, and W-phase voltage instructions v u * , v v * , v w * The vector control unit 27 includes a torque-to-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-to-current command conversion unit 27a converts the corrected torque command τ ** Converted into d-axis and q-axis current instructions i d * ,i q * The three-phase to two-phase converter 27c uses the rotor phase θ of the motor 4 to convert the U-phase, V-phase, and W-phase currents i of the power converter 3 into u ,i v ,i wConverted to d-axis and q-axis current i d ,i q The current control unit 27b is based on the d-axis and q-axis current commands i d * ,i q * And the d-axis and q-axis currents i d ,i q , calculate the d-axis and q-axis voltage instructions v d * , v q * The two-phase to three-phase converter 27d uses the rotor phase θ of the motor 4 to convert the d-axis and q-axis voltage commands v d * , v q * Convert to U phase, V phase, W phase voltage command v u * , v v * , v w * .

[0029] The PWM control unit 28 generates the voltage commands v for the U-phase, V-phase, and W-phase voltages. u * , v v * , v w * , outputs multiple gate signals g (i.e. PWM control signals) to the power converter 3, thereby controlling the power converter 3. As a result, U-phase, V-phase, and W-phase voltages v are applied to the motor 4. u , v v , v w , current i flowing through U phase, V phase, and W phase u ,i v ,i w , generating actual torque τ.

[0030] Figure 6 Flowchart of the control process executed by the control device 1 of the first embodiment. In step S80, the motor output calculation unit 21 calculates the motor output based on the U-phase, V-phase, and W-phase voltages v of the power conversion device 3. u , v v , v w , U-phase, V-phase, and W-phase currents i of the power conversion device 3 u ,i v ,i w , and the frequency ω of the motor 4, calculate the output P of the motor 4 out In step S90, the loss variation calculation unit 25 calculates the loss variation ΔP of the motor 4 when the temperature changes. LIn step S100, the switching unit 24 uses the output P of the motor 4 calculated in step S80. out and the loss variation ΔP of the motor 4 during temperature fluctuation calculated in step S90 L , calculate the ratio of loss change Δτ L In step S110, the switching unit 24 sets the loss change ratio Δτ calculated in step S100 to L The absolute value of |Δτ L | Error rate Δτ from the specified allowable torque MAX Compare and determine whether the former is less than the latter. If the absolute value |Δτ L | Smaller than the allowable torque error rate Δτ MAX , the processing enters step S120.

[0031] In step S120, the first torque estimation unit 22 calculates the first torque estimation value τ1 using the aforementioned equation (2). In step S130, the switching unit 24 uses the first torque estimation value τ1 calculated in step S120 as the torque estimation value τ. est Output. After that, the process proceeds to step S160.

[0032] On the other hand, in step S110, if the absolute value |Δτ L ∣ is the allowable torque error ratio Δτ MAX If the above is true, the process proceeds to step S140. In step S140, the second torque estimation unit 23 calculates the second torque estimation value τ2 using the aforementioned equation (3). In step S150, the switching unit 24 uses the second torque estimation value τ2 calculated in step S140 as the torque estimation value τ est Output. After that, the process proceeds to step S160.

[0033] In step S160, the torque instruction correction unit 26 corrects the torque command based on the torque estimated value τ outputted in step S120 or step S140. est Corrected torque command τ * The corrected value is used as the corrected torque instruction τ ** In step S170, the vector control unit 27 corrects the torque command τ outputted in step S160 based on the torque command τ. ** , U-phase, V-phase, and W-phase currents i of the power conversion device 3 u ,i v ,i w , and the rotor phase θ of the motor 4, calculate the U-phase, V-phase, and W-phase voltage instructions v u * , v v * , v w *In step S180, the PWM control unit 28 generates the voltage commands v for the U phase, V phase, and W phase calculated in step S170. u * , v v * , v w * , outputs multiple gate signals g to the power conversion device 3, thereby controlling 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 be reduced to zero by the torque command correction unit 26. The calculation of the second torque estimated value τ2 by the second torque estimating unit 23 is affected by the detection error of the rotor phase θ of the motor 4. Therefore, it is preferable to use the first torque estimated value τ1 calculated by the first torque estimating unit 22 as much as possible. However, the calculation of the first torque estimated value τ1 by the first torque estimating unit 22 is affected by the detection error of the rotor phase θ of the motor 4. LR The winding resistance value R used during the calculation is affected by temperature fluctuations, so the torque error ratio Δτ does not become zero. In other words, the first torque estimate τ1 will contain an error due to temperature fluctuations. In other words, the first torque estimate τ1 will contain a non-zero torque error ratio Δτ due to temperature fluctuations.

[0035] The control device 1 of the first embodiment suppresses the torque error rate Δτ caused by temperature fluctuation to a maximum of the allowable torque error rate Δτ by using the switching unit 24 and the loss change amount calculation unit 25. MAX The operating principle is as follows. (Operation Principle 1) By comparing the comparator 24b and the switch 24c, only when “|Δτ L ∣<Δτ MAX ”, the first torque estimating unit 22 is applied. (Operation Principle 2) The torque error rate Δτ is expressed by the following equation (5) due to the effect of the torque command correction unit 26. Δτ=(τ-τ * ) / τ * =(τ-τ est ) / τ est …(5) Here, within the applicable range of the first torque estimating unit 22, “τ est =τ1". In addition, the following equation (6) is established from the above equations (1) and (2). τ est =τ1=(P in -P LI -P LR ) / ω…(6) Similarly, regarding the actual torque τ, the following equation (7) holds. τ=(P in -P LI -P LR -ΔP L ) / ω…(7) Substituting equations (6) and (7) into equation (5), we can obtain the following equation (8). Δτ=(-ΔP L ) / (P in -P LI -P LR )=-ΔP L / P OUT …(8) From the above, we can know that "Δτ=-Δτ L ”. (Operation Principle 3) From (1) and (2) above, it can be seen that only in “|Δτ L ∣<Δτ MAX ” That is, “∣Δτ∣<Δτ MAX ”, the first torque estimating unit 22 is applied. Therefore, when the first torque estimating unit 22 is applied, the torque error ratio Δτ caused by temperature change does not exceed the allowable torque error ratio Δτ MAX If it exceeds, the second torque estimating unit 23 is automatically switched. Although the second torque estimating unit 23 is affected by the detection error of the rotor phase θ of the motor 4, it is not affected by the winding resistance variation ΔR caused by temperature variation and is robust to temperature variation.

[0036] According to the above-described embodiment, the following effects can be obtained.

[0037] (1) The calculation device 11 calculates the output P of the motor 4 out Calculate the loss change ΔP caused by the temperature change of the motor 4 L , the loss variation relative to the output P of the motor 4 out The ratio Δτ L The absolute value of |Δτ L | Smaller than the permissible torque error ratio Δτ of the motor 4 MAX In the case of the motor 4, the output P out The first torque estimation value τ1 of the frequency ω (rotation speed) of the motor 4 is used as the torque estimation value τ of the motor 4. est In other cases, the U-phase, V-phase, and W-phase currents i u ,i v ,i w The second torque estimated value τ2 of the motor 4 is obtained by calculating the current of the motor 4 and the rotor phase θ. estThis can suppress the torque error ratio caused by temperature fluctuations to below the allowable value.

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

[0039] (3) The calculation device 11 calculates the multiplier i based on the current of the motor 4 n and the frequency multiplier ω m The product of aω m i n Add the offset value b to the resulting value to calculate the loss change ΔP L This allows for simple calculations to be used to calculate the copper loss, which accounts for the majority of the temperature fluctuations. This reduces the amount of calculations required and thus reduces power consumption.

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

[0041] (5) The calculation device 11 calculates the output P of the motor 4 out The value obtained by dividing by the frequency ω (rotational speed) of the electric motor 4 is used as the first torque estimated value τ1. In this way, when the temperature does not fluctuate significantly, the first torque estimating unit 22 can stably obtain a highly accurate torque estimated value.

[0042] (6) The calculation device 11 uses the rotor phase θ of the motor 4 to calculate the U-phase, V-phase, and W-phase currents i of the power conversion device 3 of the motor 4. u ,i v ,i w (Three-phase AC current) is converted into two-phase d-axis and q-axis current i d ,iq , and based on the d-axis and q-axis current i d ,i q , d-axis inductance L of motor 4 d and q-axis inductance L q , and the induced electromotive force coefficient K of the motor 4 e Thus, even when the temperature fluctuates drastically, the second torque estimating unit 23 can stably obtain a highly accurate torque estimation value.

[0043] (7) The calculation device 11 calculates the torque estimated value τ of the electric motor 4 based on the torque estimated value τ of the electric motor 4. est Correction of the torque command τ input to the control device 1 * , and based on the corrected torque instruction τ ** The gate signal g (PWM control signal) is output to the power conversion device 3. In this way, the power conversion device 3 can be stably controlled to obtain a desired torque.

[0044] (8) The calculation device 11 is a torque estimated value τ est As feedback, torque command τ * As a feedforward two-degree-of-freedom control system, even if the first torque estimating unit 22 and the second torque estimating unit 23 are switched, the estimation result does not become unstable, and high estimation accuracy can be maintained in a steady state.

[0045] Reference Figure 7 , a control device according to a second embodiment of the present invention will be described. Configurations identical or corresponding to those described in the first embodiment are denoted by the same reference numerals, and the description will focus on differences.

[0046] Figure 7 This is a schematic diagram showing an electric vehicle 200 equipped with a control device 100 according to the second embodiment. Electric vehicle 200 is driven by an electric motor 4. Specifically, electric vehicle 200 includes four electric motors 4, each of which is connected to an axle of four wheels 201 provided on electric vehicle 200. Each of the four electric motors 4 is provided with a corresponding control device 100 and a power conversion device 3.

[0047] The electric vehicle 200 includes a control device (hereinafter also referred to as the electric vehicle control device) 202 for controlling various parts 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 converts the torque command τ1 used to accelerate or decelerate the electric vehicle 200 into a torque command τ1. * , τ2 * , τ3 * , and τ4 *, which is output to each of the four control devices 100. Since the electric vehicle 200 is driven under a wide range of conditions from low speed to high speed, the temperature of the motor 4 will continue to fluctuate. However, the control device 100 of the second embodiment can suppress the torque error ratio Δτ to the allowable torque error ratio Δτ. MAX Therefore, the electric vehicle 200 can be accelerated and decelerated stably.

[0048] The following modifications also fall within the scope of the present invention, and the configurations shown in the modifications may be combined with the configurations described in the above embodiments, or the configurations described in the above different embodiments may be combined, or the configurations described in the following different modifications may be combined.

[0049] <Variation 1> The operation of the torque instruction correction unit 26 can also be Figure 3 For example, the torque estimation value τ may be est Directly used as the correction torque instruction τ ** Even in this case, torque estimation can be performed with good accuracy in a steady state. However, when the first torque estimating unit 22 and the second torque estimating unit 23 are switched, the output may oscillate, and there is a risk of transient instability.

[0050] <Variation 2> Input P of motor 4 in , it is also possible not to pass through the U-phase, V-phase, and W-phase voltages v of the power conversion device 3 u , v v , v w and the U-phase, V-phase, and W-phase currents i of the power converter 3 u ,i v ,i w It is not the inner product of the power conversion device 3, but is obtained by multiplying the input of the power conversion device 3 by the power conversion efficiency of the power conversion device 3.

[0051] While the embodiments of the present invention have been described above, the above embodiments merely illustrate a part of application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. Explanation of symbols

[0052] 1, 100...control device, 2...torque command input device, 3...power conversion device, 4...motor, 11...calculation device, 12...non-volatile memory, 13...volatile memory, 14...input / output interface, 21...motor output calculation unit, 22...first torque estimation unit, 23...second torque estimation unit, 24...switching unit, 25...loss change 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 for driving an electric motor, characterized in that: Possessing a computing device, the computing device, Calculate the output of the motor, Calculate the loss change caused by the temperature change of the motor, When the ratio of the loss change to the output of the motor is less than the allowable torque error ratio of the motor, a first torque estimation value based on the output of the motor and the speed of the motor is used as the torque estimation value of the motor. In other cases, a second torque estimation value based on the current of the motor and the rotor phase of the motor is used as the torque estimation value of the motor.

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

3. The control device for the power conversion device according to claim 2, wherein: 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.

4. The control device for the power conversion device according to claim 1, wherein: The calculation device uses the product of a change in winding resistance value due to a temperature change of the motor and a square of a current of the motor as the loss change.

5. The control device for the power conversion device according to claim 1, wherein: The calculation device divides the output of the electric motor by the rotational speed of the electric motor as the first torque estimated value.

6. The control device for the power conversion device according to claim 1, wherein: The calculation device converts the three-phase AC current of the motor into d-axis and q-axis currents by performing three-phase-to-two-phase conversion using the rotor phase of the motor, and calculates the second torque estimation value based on the d-axis and q-axis currents, the inductance of the motor, and the induced electromotive force coefficient of the motor.

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

8. The control device for the power conversion device according to claim 7, wherein: The calculation device is a two-degree-of-freedom control system that uses the torque estimate value as feedback and the torque command as feedforward.

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

Images