JP5476795B2 - Control device for electric vehicle - Google Patents

Description

  The present invention relates to a control device for an electric vehicle that travels by transmitting torque generated by an electric motor to wheels, and more particularly to a technique for detecting an abnormal state such as an electric motor or an inverter.

  Conventionally, as a technique for detecting an abnormal state of an electric motor or an inverter in an electric vehicle, for example, a technique described in Patent Document 1 below is known. In the technique described in Patent Document 1, the currents of the U, V, and W phases flowing to the electric motor are detected, the positive integral value and the negative integral value of each phase are calculated based on the detected current, and the positive It is determined whether or not an abnormality has occurred by comparing the current integral value and the negative current integral value.

JP 2004-215328 A

  However, since the technique described in Patent Document 1 is configured to determine whether or not an abnormality has occurred by comparing the integral value in the positive interval and the integral value in the negative interval of the alternating current flowing to the motor, At least one period of each phase current is required. For example, in a situation where the period of one period of each phase current is long, such as when the motor is locked or extremely low speed rotation, the abnormality determination is delayed. There was a problem that the state would continue.

  The present invention was devised in view of the above-described problems of the prior art, and it is effective to appropriately and quickly determine an abnormal state such as an electric motor or an inverter in an electric vehicle and continue the abnormal state. It is an object of the present invention to provide a control device for an electric vehicle that can be prevented.

  The control device for an electric vehicle according to the present invention compares the result of integration calculation of a value obtained by raising the current command value based on the torque command value to the 2N power and the result of integration calculation of the value obtained by raising the actual current supplied to the motor to the 2N power. Alternatively, the integration result of the value obtained by integrating the first torque estimated value estimated based on the current command value with the power of 2N and the second torque estimated value estimated based on the actual current with the power of 2N The above-described problem is solved by determining whether or not an abnormality has occurred by comparing with the calculation result.

  According to the control apparatus for an electric vehicle according to the present invention, it is possible to appropriately and quickly determine an abnormal state such as an electric motor or an inverter in the electric vehicle and effectively prevent the abnormal state from continuing.

1 is an overall configuration diagram showing an outline of a drive system of an electric vehicle to which the present invention is applied. It is a block diagram which shows the principal part of the function structure implement | achieved in a motor controller. It is a flowchart which shows the processing content implemented by the abnormality detection block of a motor controller. It is a figure which shows an example of the calculation result by the abnormality detection block of a motor controller. It is a block diagram which shows the function structure of the motor controller of 2nd Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is an overall configuration diagram showing an outline of a drive system of an electric vehicle to which the present invention is applied. The electric vehicle is equipped with a three-phase AC motor 1 configured as, for example, a permanent magnet type synchronous motor as a travel drive source, and travels by transmitting torque generated by the motor 1 to drive wheels. A battery 3 is connected to the motor 1 via an inverter 2, and DC power from the battery 3 is converted into desired AC power by the inverter 2 and supplied to the motor 1. A relay 4 is provided between the battery 3 and the inverter 2, and when the relay 4 is turned off under the control of the vehicle controller 5, power supply from the battery 3 to the motor 1 is cut off. Further, a smoothing capacitor 6 is connected in parallel between the battery 3 and the inverter 2 to smooth the DC power.

  The inverter 2 has three arms corresponding to the three-phase coils of the motor 1, and each arm is connected in parallel to the smoothing capacitor 6. Each arm is composed of two switching elements such as IGBTs connected in series and a diode connected in parallel to each switching element, and a coil of a corresponding phase of the motor 1 is interposed between the two switching elements. It is connected via a feeder line. The switching element of each arm has a collector connected to the + side of the battery 3 and an emitter connected to the − side, and is on / off controlled by the gate drive circuit 7. The diode of each arm is connected so as to be in the forward direction from the emitter to the collector of the switching element, and prevents current in the reverse direction.

The vehicle controller 5 is configured as a microcomputer including a CPU, a ROM, and a RAM, for example, and controls the running state of the electric vehicle. Specifically, the vehicle controller 5 calculates a torque command value T ^* for the motor 1 based on an accelerator signal, a brake signal, a shift position signal, etc. according to the driving operation of the vehicle driver, and calculates the calculated torque command value. T ^* is output to the motor controller 10 described later. Further, the vehicle controller 5 stops the operation of the motor controller 10, that is, the operation of the inverter 2, and turns off the relay 4 when an abnormality signal is output as a result of an abnormality determination process described later by the motor controller 10. The power supply to the motor 1 is cut off.

The motor controller 10 is configured as a microcomputer including, for example, a CPU, a ROM, and a RAM, generates a pulse modulation (PWM) signal based on the torque command value T ^* from the vehicle controller 5, and uses the PWM signal as a gate drive circuit. 7 to control the operation of the inverter 2. Further, when performing such control, the motor controller 10 inputs the sensor signal θr from the rotor position sensor 8 and the sensor signals Iu, Iv, Iw from the current sensor 9 as feedback signals and uses them for calculation. . The rotor position sensor 8 detects the rotor position θr of the motor 1. For example, a resolver attached to the motor 1 is used. The current sensor 9 detects currents (actual currents) Iu, Iv, and Iw of each phase supplied from the inverter 2 to the motor 1.

  FIG. 2 is a functional block diagram showing a main part of a functional configuration realized in the motor controller 10. The motor controller 10 of the present embodiment includes an abnormality detection block 30 as a functional block characteristic of the present invention, in addition to the drive control block 20 for generating a PWM signal and controlling the operation of the inverter 2.

  First, the drive control block 20 will be briefly described. The drive control block 20 includes a current command value calculation unit 21, a current control unit 22, a dq / 3 phase conversion unit 23, a PWM signal generation unit 24, a three phase / dq conversion unit 25, and a θ. A (phase) calculation unit 26 and a rotation speed (electrical angular velocity) calculation unit 27 are included.

The current command value calculation unit 21 is based on the torque command value T * calculated by the vehicle controller 10 and the rotation speed ω (rotation speed) of the motor 1 calculated by the rotation number calculation unit 27. A value Id ^* and a q-axis current command value Iq ^* are calculated. Here, the d-axis current is an excitation current component of a three-phase current (Iu, Iv, Iw) flowing through the motor 1, and the q-axis current is a torque current component.

The current control unit 22 is based on a d-axis current command value Id ^* and a q-axis current command value Iq ^* and a d-axis current Id and a q-axis current Iq input from a three-phase / dq conversion unit 25 described later. Then, the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* are calculated. Specifically, the deviation between the current command value and the actual current ^{(Id * -Id), (Iq} * -Iq) were respectively calculated, by performing the PI (proportional-integral) operation on the calculated difference, The d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* are calculated.

The dq / 3-phase conversion unit 23 converts the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* calculated by the current control unit 22 into phases calculated by a later-described θ (phase) calculation unit 26. Based on θ, it is converted into a three-phase AC voltage command value Vu ^* , Vv ^* , Vw ^* . The converted three-phase AC voltage command values Vu ^* , Vv ^* , Vw ^* are output to the PWM signal generator 24.

The PWM signal generation unit 24 generates a PWM signal for controlling the inverter 2 based on the three-phase AC voltage command values Vu ^* , Vv ^* , Vw ^* and a triangular wave signal (carrier signal).

  The three-phase / dq converter 25 converts the sensor signals (Iu, Iv, Iw) of the current sensor 9 into a d-axis current Id and a q-axis current Iq.

  The θ (phase) calculation unit 26 calculates the rotation phase θ based on the sensor signal θr of the rotor position sensor 8.

  The rotation speed calculation unit 27 calculates the rotation speed (electrical angular velocity) ω by differentiating the rotation phase θ.

Next, the abnormality detection block 30 which is a characteristic feature of the present invention will be described. The abnormality detection block 30 includes an LPF 31, a T ^* calculation unit 32, a square calculation unit 33, an integration calculation unit 34, a T calculation unit 35, a square calculation unit 36, an integration calculation unit 37, and an abnormality determination unit 38. The The abnormality detection block 30 includes a d-axis current command value Id * and a q-axis current command value Iq * calculated by the current command value calculation unit 21 of the drive control block 20, and a three-phase / dq conversion unit 25. The d-axis current Id and the q-axis current Iq obtained from the actual currents Iu, Iv, Iw are input. The d-axis current command value Id * and the q-axis current command value Iq * are used for calculation in the T ^* calculation unit 32, the square calculation unit 33, and the integration calculation unit 34, and the d-axis current Id and the q-axis current Iq are , T calculation unit 35, square calculation unit 36, and integration calculation unit 37.

Here, in order to compensate for a response delay of the d-axis current Id and the q-axis current Iq with respect to the d-axis current command value Id * and the q-axis current command value Iq *, a current control block is provided before the T ^* calculation unit 32. LPF (low-pass filter) 31 that is set constant according to the response characteristic of PI control at 20 is provided, and the d-axis current command value Id * and the q-axis current command value Iq * that have passed through the LPF 31 are T ^* calculation unit 32. Is input. Instead of providing the LPF 31, d-axis current Id and q d-axis current command value to match the response of the axis current Iq Id * and q-axis current command value Iq * to T ^* computing unit 32 determined from the actual current You may make it input into.

The T ^* calculation unit 32 performs a torque calculation shown in the following equation (1) based on the input d-axis current command value Id * and q-axis current command value Iq *, and the d-axis current command value Id *. And a first estimated torque value estimated to be output from the motor 1 in correspondence with the q-axis current command value Iq *. Further, it is estimated that the T calculation unit 35 performs the torque calculation shown in the following formula (1) based on the input d-axis current Id and q-axis current Iq, and that the motor 1 is actually outputting. A second estimated torque value is calculated.
Trq = p × φa × Iq + p × (Ld−Lq) × Id × Iq (1)
Ld, Lq, φa: motor constant, p: number of counter electrodes, Trq: torque

The first torque estimated value (T ^* ) calculated by the T ^* calculator 32 is squared by the square calculator 33 and then added (integrated) to the previous value by the integral calculator 34. The second torque estimated value (T) calculated by the T calculation unit 35 is squared by the square calculation unit 36 and then added (integrated) to the previous value by the integration calculation unit 37. Then, the operation result of the integral calculator 34 ∫ (T ^{*) 2} and the computation result ∫ (T) ² of the integral calculator 37 are input to the respective abnormality determining unit 38.

Abnormality determining unit 38, the operation result of the integral calculator 34 ∫ (T ^{*) 2} and result of integral calculation of the arithmetic unit 37 ∫ (T) is compared with ^2, one of the operation results and the other operation result and a predetermined In other words, as shown in the following equation (2), the absolute value of the difference between the integral values ∫ (T ^* ) ² and ∫ (T) ² is a predetermined threshold value Const. Is exceeded, for example, it is determined that some abnormality such as an open failure of the switching element of the inverter 2 or a coil disconnection of the motor 1 has occurred, and an abnormality signal is output.
| ∫ (T ^* ) ² −∫ (T) ² |> Const. ... (2)

  FIG. 3 is a flowchart showing the contents of processing performed by the abnormality detection block 30 of the motor controller 10. In the drive system of the electric vehicle to which the present invention is applied, the rotation speed of the motor 1 is not changing suddenly, that is, the change per unit time of the rotation speed ω calculated by the rotation speed calculation unit 27 of the drive control block 20. When the amount is less than the reference value, the abnormality detection block 30 of the motor controller 10 repeats the series of processes shown in FIG. 3 at predetermined intervals, so that the abnormal state of the motor 1 and the inverter 2 in the electric vehicle can be appropriately and It makes it possible to judge quickly.

  When the flow of FIG. 3 is started, first, in step S10, it is determined whether or not a predetermined integration period has elapsed. This processing may be executed as processing such as counting the integration time with an integration counter and outputting a reset pulse when a predetermined integration time has elapsed. If the predetermined integration time has elapsed, the process proceeds to step S20, and if not, the process proceeds to step S30.

  In step S20, the integration value obtained by the integration calculation up to the previous processing cycle is cleared, and the process proceeds to step S30.

In step S30, based on the d-axis current command value Id ^* and the q-axis current command value Iq ^* , the torque calculation shown in the above equation (1) is performed to calculate the first torque estimated value (T ^* ). Then, the first torque estimated value (T ^* ) is squared, and the process proceeds to step S40.

At step S40, by newly adding the squared value of the calculated in step S30 to the square sum of (T ^*) to the previous processing cycle (T ^*), the square integral value of (T ^*) ∫ (T ^* ) Calculate ² and go to step S50.

  In step S50, based on the d-axis current Id and the q-axis current Iq, the torque calculation shown in the above equation (1) is performed to calculate the second torque estimated value (T), and this second torque estimation The value (T) is squared and the process proceeds to step S60.

In step S60, the square value of (T) calculated in step S50 is newly added to the square sum of (T) up to the previous processing cycle, so that the square integral value ∫ (T) ² of (T) is obtained. Calculate and go to step S70.

In step S70, ∫ (T ^* ) ² and ∫ (T) ² calculated in step S40 and step S60 are subtracted and absolute values are compared. The absolute value of these differences is a predetermined threshold value Const. If it is greater than the command value, it is determined that the deviation of the actual value is larger than the command value and that an open failure of the switching element of the inverter 2 or a coil disconnection of the motor 1 has occurred, and the process proceeds to step S80. On the other hand, the absolute value of the difference between ∫ (T ^* ) ² and ∫ (T) ² is the predetermined threshold value Const. If it is smaller than that, it is determined that the state is normal, and the process returns to step S10 to repeat the same processing in the next cycle.

  In step S80, an abnormality signal is output to the vehicle controller 5, and the process in the abnormality detection block 30 ends. When an abnormal signal is output from the motor controller 10 to the vehicle controller 5, the vehicle controller 5 stops the operation of the motor controller 10, that is, the operation of the inverter 2, and turns off the relay 4 to supply power to the motor 1. Shut off.

FIG. 4 shows an example of a calculation result by the abnormality detection block 30 of the motor controller 10, and shows a graph of calculation results before and after the occurrence of an abnormality when an abnormality occurs in the inverter 2. 4A shows the relationship between the torque command value T ^* and the actual torque T, FIG. 4B shows the reset pulse output timing of the integration counter, and FIG. 4C shows the first torque. shows the estimated value (T ^*) the integral value of the square of ∫ (T ^{*) 2} and the relationship between the integrated value ∫ (T) ² of the square of the second torque estimate (T).

As can be seen from FIG. 4, when an abnormality such as an open failure of the switching element of the inverter 2 occurs, the actual torque T greatly fluctuates with respect to the torque command value T *. Also, the square integral of the calculation result ∫ (T ^* ) ² obtained by square integration of the first torque estimated value obtained by calculating the torque from the current command value and the second torque estimated value obtained by calculating the torque from the actual current. Looking at the calculated result ∫ (T) ² , the two are almost the same before the occurrence of the abnormality, but the difference between the two appears remarkably after the occurrence of the abnormality. Therefore, the threshold value Const. Is set to an appropriate value that can discriminate the difference between ∫ (T ^* ) ² and ∫ (T) ² caused by the occurrence of abnormality in advance. Is set, and the difference between the two is the threshold value Const. It is possible to detect an abnormality by checking whether or not the motor exceeds 1, and even when the motor 1 is operating at an extremely low speed, the abnormal state of the motor 1 or the inverter 2 can be determined appropriately and quickly. it can.

In addition, the integration counter reset pulse is output at predetermined intervals, and the integral values ∫ (T ^* ) ² and ∫ (T) ² are cleared at predetermined intervals, so that the difference between the two due to disturbance other than the occurrence of an abnormality can be obtained. It is possible to effectively prevent erroneous detection due to integration. The predetermined time at this time may be set to an optimum time in consideration of the detection time required from the system.

  In addition, the number of revolutions of the motor 1 does not change suddenly, that is, the amount of change in the number of revolutions ω per unit time is less than the reference value (or the rate of change of the rotation speed of the motor 1 per unit time is less than the reference value) By performing the above-described abnormality determination process on the condition as described above, it is possible to effectively prevent a variation due to a torque change from being erroneously detected as abnormal.

As described above in detail with reference to specific examples, in the drive system for an electric vehicle to which the present invention is applied, the abnormality detection block 30 of the motor controller 10 calculates and calculates the torque from the current command value. The calculation result 演算 (T ^* ) ² obtained by square integration of the estimated torque value of 1 is compared with the calculation result ∫ (T) ² obtained by square integration of the second torque estimate value obtained by calculating the torque from the actual current. These calculation results indicate that the predetermined threshold value Const. Since it is determined that an abnormality has occurred when there is a divergence as described above, an abnormal state of the motor 1 or the inverter 2 can be determined appropriately and quickly. In addition, the abnormality determination by the abnormality detection block 30 can eliminate the influence when the command value or the actual value is negative, so that the abnormality state is determined even when the motor 1 is locked or extremely low. Can do. Thereby, the delay of abnormality determination can be avoided and it can prevent effectively that an abnormal state continues.

  Further, the abnormality determination process by the abnormality detection block 30 of the motor controller 10 is performed on the condition that the amount of change per unit time of the rotational speed ω of the motor 1 is less than the reference value. It is possible to effectively avoid the disadvantage that the electric vehicle is unnecessarily stopped due to erroneous detection of an abnormal state.

Furthermore, since the integral values ∫ (T ^* ) ² and ∫ (T) ² used for abnormality determination are cleared when a predetermined integration time has elapsed, the reliability of abnormality determination is improved, and erroneous detection of abnormal conditions is performed. Therefore, it is possible to effectively avoid the inconvenience that the electric vehicle is stopped unnecessarily.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the configuration of the abnormality detection block of the motor controller 10 is different from that of the first embodiment. Since the outline of the other configurations and processing is the same as that of the first embodiment, the same reference numerals are used for the same configurations as those of the first embodiment, and detailed description thereof is omitted. Only the abnormality detection block 40 characteristic in the embodiment will be described.

  FIG. 5 is a functional block diagram of the motor controller 10 of the present embodiment. In the motor controller 10 of the present embodiment, an abnormality detection block 40 is provided instead of the abnormality detection block 30 described in the first embodiment. The abnormality detection block 40 includes a first torque estimated value (T *) obtained by torque calculation based on the current command value, and a second torque estimated value obtained by torque calculation based on the actual current. There is a feature in that (T) is not square-integrated, but the current command value and the actual current are square-integrated as they are.

  The abnormality detection block 40 includes an LPF 41, a square operation unit 42, an integration operation unit 43, a square operation unit 44, an integration operation unit 45, and an abnormality determination unit 46. The anomaly detection block 40 receives a q-axis current command value Iq * and a q-axis current Iq that are highly correlated with torque from the drive control block 20.

The q-axis current command value Iq * is matched with the response characteristic of the q-axis current Iq by passing through the LPF 41, is squared by the square calculator 42, and is added to the previous value by the integral calculator 43. (Integrated). Further, the q-axis current Iq is squared by the square computing unit 44 and then added (integrated) to the previous value by the integral computing unit 45. Then, the operation result of the integral calculator 43 ∫ and (Iq ^{*) 2} and the operation result ∫ (Iq) ² of the integral calculator 45 are input to the respective abnormality determining unit 46.

Abnormality determination unit 46, the operation result of the integral calculator 43 ∫ (Iq ^{*) 2} and the operation result of the integral calculator 45 ∫ (Iq) is compared with ^2, one of the operation results and the other operation result and a predetermined In other words, as shown in the following equation (3), the absolute value of the difference between the integral values ∫ (Iq ^* ) ² and ∫ (Iq) ² is a predetermined threshold value Const. Is exceeded, for example, it is determined that some abnormality such as an open failure of the switching element of the inverter 2 or a coil disconnection of the motor 1 has occurred, and an abnormality signal is output.
| ∫ (Iq ^* ) ² −∫ (Iq) ² |> Const. ... (2)

As described above, in the motor controller 10 of the present embodiment, in the abnormality detection block 40, the calculation result ∫ (Iq ^* ) ² obtained by square integration of the q-axis current command value Iq ^* and the calculation obtained by square integration of the q-axis current Iq. The result ∫ (Iq) ² is compared, and the result of these calculations is a predetermined threshold value Const. Since it is determined that an abnormality has occurred when there is a divergence as described above, as in the first embodiment, abnormal states such as the motor 1 and the inverter 2 are determined appropriately and quickly, It is possible to effectively prevent the abnormal state from continuing. In the above example, the abnormality detection is performed using the q-axis current component having a large correlation with the torque. However, the abnormality can be similarly detected using the d-axis current component.

  As described above, the first and second embodiments have been described as specific application examples of the present invention. However, the technical scope of the present invention is not limited to the contents disclosed as the above-described embodiments. Of course, various modifications, changes, alternative techniques, and the like that can be easily derived are included. For example, in the first and second embodiments described above, abnormality determination is performed by comparing the square-integrated calculation result, but the calculation result integrated after 2N power (N is a natural number) is compared and abnormal. Even if the determination is performed, the same effect can be obtained.

1 Motor 8 Rotor Position Sensor 9 Current Sensor 10 Motor Controller 30 Abnormality Detection Block 31 LPF
32 T ^* operation unit 33 square operation unit 34 integral operation unit 35 T operation unit 36 square operation unit 37 integral operation unit 38 abnormality determination unit 40 abnormality detection block 41 LPF
42 Square operation unit 43 Integration operation unit 44 Square operation unit 45 Integration operation unit 46 Abnormality determination unit

Claims (6)

In a control device for an electric vehicle that travels by transmitting torque generated by an electric motor to wheels,
Current command value calculation means for calculating a command value of a current supplied to the electric motor based on a torque command value corresponding to a request of the vehicle driver;
An actual current detecting means for detecting an actual current supplied to the electric motor;
Current command value integrating means for integrating after the current command value calculated by the current command value calculating means is raised to the 2Nth power (N is a natural number);
An actual current value integrating means for integrating after the actual current value detected by the actual current detecting means is raised to the 2Nth power (N is a natural number);
Comparing the calculation result of the current command value integration means with the calculation result of the actual current value integration means, an abnormality occurs when one calculation result and the other calculation result are more than a predetermined value And an abnormality determination means for determining that there is a control device for an electric vehicle. In a control device for an electric vehicle that travels by transmitting torque generated by an electric motor to wheels,
Current command value calculation means for calculating a command value of a current supplied to the electric motor based on a torque command value corresponding to a request of the vehicle driver;
First torque estimating means for calculating a first torque estimated value estimated to be output from the electric motor based on the current command value calculated by the current command value calculating means;
An actual current detecting means for detecting an actual current supplied to the electric motor;
Second torque estimating means for calculating a second torque estimated value that is estimated to be actually output from the electric motor based on the actual current value detected by the actual current detecting means;
First torque integrating means for integrating after the first torque estimated value calculated by the first torque estimating means is raised to the 2Nth power (N is a natural number);
Second torque integrating means for integrating after the second torque estimated value calculated by the second torque estimating means is multiplied by 2N (N is a natural number);
When the calculation result of the first torque integration means and the calculation result of the second torque integration means are compared, an abnormality occurs when one calculation result and the other calculation result are more than a predetermined value apart. And an abnormality determination means for determining that there is a control device for an electric vehicle. A rotation speed calculating means for calculating the rotation speed of the electric motor;
The control apparatus for an electric vehicle according to claim 1, wherein the abnormality determination unit determines the abnormality when a change amount per unit time of the rotation speed of the electric motor is less than a reference value. 2. The control apparatus for an electric vehicle according to claim 1 , wherein the current command value integration unit and the actual current value integration unit clear the integration value every time a predetermined period elapses.   The control apparatus for an electric vehicle according to claim 2, wherein the first torque integrating means and the second torque integrating means clear an integrated value every time a predetermined period elapses. Of claims 1 to 5, further comprising a response delay compensating means for compensating the response delay of the actual current detected by the actual current detection means with respect to the current command value calculated by the current command value calculating means The control apparatus of the electric vehicle as described in any one.

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