JP6459363B2 - Electric motor control device - Google Patents

Description

  The present invention relates to a control device for an electric motor.

  2. Description of the Related Art Conventionally, a technology for switching control between a current control mode and a voltage phase control mode in a control system for a rotating electrical machine is known. In the control system described in Patent Document 1, the switching line for switching from the voltage phase control mode to the current phase control mode is set to q higher than the maximum efficiency characteristic line capable of operating the rotating electrical machine at maximum efficiency in consideration of hysteresis for preventing chattering. It is set on the axis side.

JP 2010-81663 A

  However, since the technique of Patent Document 1 cannot be switched at the maximum efficiency characteristic line that is originally desired to be switched, the motor drive in the hysteresis section, that is, the section from the past of the maximum efficiency characteristic line to the return to the maximum efficiency characteristic line again. Efficiency deteriorates compared with the efficiency of motor drive in the maximum efficiency line characteristic line.

  An object of the present invention is to provide a technique capable of quickly switching between a current control mode and a voltage phase control mode without providing a hysteresis section in a predetermined switching line such as a maximum efficiency characteristic line. .

The motor control device according to the present invention includes a control mode switching determination unit that determines switching from the current control mode to the voltage phase control mode or switching from the voltage phase control mode to the current control mode according to a predetermined switching condition. And a mask time measuring unit that continues to measure an elapsed time from when the control mode switching determining unit determines to switch the control mode unless the determination changes, and the time measured by the mask time measuring unit is a predetermined time. It is determined whether or not the above has elapsed. If it is determined that the time measured by the mask time measuring means has exceeded a predetermined time, the current control mode changes to the voltage phase control mode, or the voltage phase control mode changes to the current depending on the determination of the control mode switching determination means. Switch control mode to control mode. The predetermined time is longer than the update period of the voltage command value calculated in the current control mode.

  According to the present invention, without providing a hysteresis interval in the switching threshold (for example, the maximum efficiency characteristic line) determined by a certain index, the elapsed time from when the predetermined determination value is reached to the switching threshold is measured, Since the control mode is switched when the measurement time exceeds a predetermined time, the control mode can be quickly switched before and after the switching threshold determined by a certain index.

FIG. 1 is a block diagram illustrating a configuration of a motor control device according to the first embodiment. FIG. 2 is a flowchart for one control calculation related to the control mode switching determination performed inside the control mode determination unit of the motor control device according to the first embodiment. FIG. 3 is a diagram for explaining the relationship between the transition of the current and voltage with respect to the displacement of the motor rotation speed and the control mode switching timing. FIG. 4 is a block diagram illustrating the configuration of the motor control device according to the second embodiment. FIG. 5 is a block diagram illustrating the configuration of the motor control device according to the third embodiment. FIG. 6 is a flowchart for one control calculation related to the control mode switching determination performed inside the control mode determination unit of the motor control apparatus according to the third embodiment.

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration of a motor control device according to the first embodiment. This motor control device is applied to, for example, an electric vehicle. In addition to an electric vehicle, for example, the present invention can be applied to a hybrid vehicle or a system other than a vehicle.

The current command generator 1 determines the relationship between the torque command value T ^* , the DC voltage V _dc of the battery 7, and the rotation speed N (hereinafter referred to as motor rotation speed) N of the motor 9, and the d-axis current and the q-axis current. The determined table is stored, and the torque command value T ^* , the DC voltage V _dc of the battery 7 and the motor rotation speed N are input, and the d-axis current command value i _d ^* and The q-axis current command value i _q ^* is obtained. The d-axis current and the q-axis current defined in the table are a d-axis current and a q-axis current obtained in advance by experiment or analysis to obtain a desired torque. The current command values i _d ^* and i _q ^* are current command values in the current control mode.

The interference voltage generation unit 2 stores a table that defines the relationship between the torque command value T ^* , the DC voltage V _dc of the battery 7, the motor rotation speed N, and the d-axis and q-axis interference voltages. The command value T ^* , the DC voltage V _dc of the battery 7 and the motor rotation speed N are input, and the d-axis interference voltage V _{d_dcpl} ^* and the q-axis interference voltage V _{q_dcpl} ^* are obtained by referring to the above table.

The current vector controller 3 includes a d-axis current command value i _d ^* and a q-axis current command value i _q ^* , a d-axis current detection value i _d and a q-axis current detection value i _q, and a d-axis interference voltage V _{d_dcpl} ^*. Based on the q-axis interference voltage V _{q_dcpl} ^* , vector current control by known non-interference control and current feedback control is performed to calculate the d-axis voltage command value V _di ^* and the q-axis voltage command value V _qi ^* . The voltage command values V _di ^* and V _qi ^* are voltage command values in the current control mode.

The voltage amplitude generation unit 13 converts the power supply voltage V _dc into a voltage amplitude command value V _a ^* realized by voltage phase control described later.

The torque calculator 15 calculates the magnetic flux φ _a stored in advance, the inductance difference between the d-axis and the q-axis (L _d −L _q ), the d-axis current detection value _id and the q-axis current detection value i _q . Then, the estimated torque value T _cal of the electric motor 9 is calculated by the following equation (1).

In Equation (1), p is the number of pole pairs of the electric motor 9. Further, the inductance difference (L _d −L _q ) between the d axis and the q axis is obtained by the inductance generator 14. Specifically, an offline analysis or experiment is performed in advance, and the torque command value T ^* , the DC voltage V _dc of the battery 7, the motor rotation speed N, and the d-axis and q-axis inductance difference (L _d −L _q ) Are prepared, the torque command value T ^* , the DC voltage V _dc of the battery 7 and the motor rotational speed N are input, and the d-axis and q A shaft inductance difference (L _d −L _q ) is obtained.

The torque controller 16 inputs a difference between the torque command value T ^* and the estimated torque value T _cal and calculates a value obtained by PI amplification by the following equation (2) as a voltage phase command value α ^* . However, a K _p is a proportional gain in formula (2), K _i is an integral gain.

The dq-axis voltage generation unit 17 inputs the voltage amplitude command value V _a ^* obtained by the voltage amplitude generation unit 13 and the voltage phase command value α ^* calculated by the torque controller 16, and the following equation (3) The d-axis voltage command value V _dv ^* and the q-axis voltage command value V _qv ^* are calculated. The voltage command values V _dv ^* and V _qv ^* are voltage command values in the voltage phase control mode.

The current control transition determination unit 20 includes the d-axis current command value i _d ^* and the q-axis current command value i _d ^* obtained by the current command generation unit 1, and the d-axis current detection value i _d and the q-axis current detection value i _q. To determine whether to shift from the voltage phase control mode to the current control mode. When the determination value (for example, the operating point of the rotating electrical machine on the dq axis plane) exceeds a switching threshold (for example, a value based on the maximum efficiency characteristic line) set by a certain index, the voltage phase control mode changes to the current control mode. The control mode switching request is output. Note that the determination value and the switching threshold, which are indices for determining the switching of the control mode, are not limited to these and are set as appropriate.

The voltage phase control transition determination unit 19 inputs the torque command value T ^* , the motor rotation speed N, the DC voltage V _dc of the battery 7, the d-axis voltage command value V _d ^* , and the q-axis voltage command value V _q ^*. Then, the transition determination from the current control mode to the voltage phase control mode is performed. When the determination value (for example, the voltage amplitude calculated from the dq axis voltages V _d and V _q ) exceeds a switching threshold determined by the power supply voltage set by a certain index (for example, the maximum efficiency characteristic line), current control is performed. It is determined that the mode is shifted to the voltage phase control mode, and a control mode switching request is output. Note that the determination value and the switching threshold, which are indices for determining the switching of the control mode, are not limited to these and are set as appropriate.

  The control mode determination unit 21 performs the final control mode switching determination based on the control mode switching request from the current control transition determination unit 20 or the voltage phase control transition determination unit 19. Details of the control calculation related to the switching determination will be described below with reference to FIG.

  FIG. 2 is a flowchart for one control calculation related to switching determination between the current control mode and the voltage phase control mode. In step S1, the current control mode is determined. If the current control mode is the current control mode, the process proceeds to step S2. If the current control mode is the voltage phase control mode, the process proceeds to step S4.

  In step S2, it is determined whether or not the transition to the voltage phase control mode is requested. Specifically, the control mode switching request output from the voltage phase control transition determining unit 19 is confirmed. If the output can be confirmed, it is determined that the transition to the voltage phase control mode is requested, and the process proceeds to step S3. Here, for example, a timer provided in the controller having the control mode determination unit 21 is started so that an elapsed time since the transition to the voltage phase control mode is requested can be detected. The elapsed time is used as a determination index in step S3 described later. On the other hand, if the voltage phase control transition determination unit 19 does not output a control mode switching request, it is determined that the transition to the voltage phase control mode is not requested, and the current control mode that is the current control mode is continued. Then, the control calculation for one time is finished.

  In step S3, if the transition to the voltage phase control mode is requested in step S2, whether or not the elapsed time since the transition to the voltage phase control mode is requested is equal to or longer than a predetermined time (hereinafter referred to as a mask time). Determine. If the elapsed time is equal to or longer than the mask time, the control mode is switched from the current control mode to the voltage phase control mode.

  If the elapsed time has not passed the mask time, the current control mode is continued. It should be noted that the above-described timer started after the transition to the voltage phase control mode is requested is not reset until the transition request to the voltage phase control mode from the voltage phase control transition determination unit 19 is resolved. In other words, as long as the transition to the voltage phase control mode continues to be requested, the elapsed time is continuously measured. Since the control calculation according to the flowchart is repeatedly performed, as long as the request for shifting to the voltage phase control mode in the current control mode continues, the elapsed time since the request for shifting to the voltage phase control mode is made in step S3. It is determined whether or not the mask time has elapsed.

  Next, the case where the current control mode is the voltage phase control mode will be described. In step S4, it is determined whether or not a shift to the current control mode is requested. Specifically, the control mode switching request output from the above-described current control transition determination unit 20 is confirmed. If the output can be confirmed, it is determined that the transition to the current control mode is requested, and the process proceeds to step S5. Here, similarly to the processing in step S2, a timer for measuring the elapsed time since the shift to the current control mode is requested is started. On the other hand, if the current control transition determination unit 20 does not output a control mode switching request, the voltage phase control mode that is the current control mode is continued.

  In step S5, when the transition to the current control mode is requested in step S4, it is determined whether or not the elapsed time after the transition to the voltage phase control mode is requested is a predetermined time (mask time) or more. If the elapsed time is equal to or longer than the mask time, the control mode is switched from the voltage phase control mode to the current control mode.

  If the elapsed time has not passed the mask time, the voltage phase control mode is continued. It should be noted that the above-described timer started after the request for shifting to the current control mode is not reset until the request for shifting to the current control mode is resolved. Since the control calculation according to the flowchart is repeatedly performed, as long as the request for transition to the current control mode in the voltage phase control mode continues, the elapsed time from the request for transition to the voltage phase control mode is the mask time in step S4. It is determined whether or not elapses.

  As described above, the control mode determination unit 21 further performs the transition after a request for transition to the control mode is made when the transition determination from the current control mode to the one control mode (steps S2 and S4) is YES. When it is determined that the measured elapsed time is equal to or longer than the mask time as long as the request continues, the control mode switching is determined to be executed. If the control mode transition request has not been made, or the control mode transition request has been made and the elapsed time since the request has been made has not reached the mask time, the current control mode is continued. To do. The control mode selected in this way is output to the control mode switching unit 18.

The control mode switch 18 is input from the control mode determination unit 21 among the voltage command values V _di ^* and V _qi ^* based on the current control mode and the voltage command values V _dv ^* and V _qv ^* based on the voltage phase control mode. A voltage command value corresponding to the control mode is selected and output to the dq axis / UVW phase converter 4 as the d axis voltage command value V _d ^* and the q axis voltage command value V _q ^* .

Here, the setting of the mask time will be described. As described above, since the transition of the control mode is performed after the lapse of the mask time after reaching the switching threshold based on an index with a predetermined determination value, the shorter the mask time is, the shorter the control mode is switched. preferable. However, if switching chattering occurs when the update period of the voltage command values V _di ^* and V _qi ^{* in} the current control mode and the update period of the voltage command values V _dv ^* and V _qv ^{* in} the voltage phase control mode are shorter than That is, when the control mode is shifted a plurality of times in a cycle shorter than the voltage command value update cycle, the response cannot follow the target value, resulting in current disturbance and the like, and stable control cannot be performed. Accordingly, the mask time is set to be larger than the update cycle of the voltage command values V _di ^* and V _qi ^{* in} the current control mode and the update cycle of the voltage command values V _dv ^* and V _qv ^{* in} the voltage phase control mode. Thereby, even when switching chattering occurs, the response can follow the target value, so that stable control can be performed without disturbing the current.

  On the other hand, if the mask time is excessively increased, the operating point related to the control mode switching is accompanied and the control becomes slow. Therefore, by setting the upper limit value of the mask time based on the time constant of the torque response, it becomes possible to quickly switch the control mode without the operating point stagnating. The mask time in the present embodiment is set to 5 times or less of the time constant of the torque response in consideration of the followability to the torque response.

  Next, the control mode switching timing and the transition of voltage and current when the rotational speed increases and decreases while the torque command value is constant will be described with reference to FIG.

  FIG. 3 is a relationship diagram of current and voltage transitions with respect to displacement of the rotational speed and control mode switching timing. As shown in the figure, the current control mode is applied in the low rotation region. As the motor rotation speed N increases, the voltage amplitude at the motor input end increases accordingly. When the determination value based on the voltage amplitude reaches a threshold value for shifting to voltage phase control, the mode shifts to the voltage phase control mode (switching point a). In addition, when the rotational speed decreases and the determination value based on the current amplitude reaches a threshold value for shifting to current control, the mode shifts to the current control mode (switching point b). As can be seen from the fact that the rotational speed N, the voltage amplitude Va, and the current amplitude Ia are the same at the switching point a and the switching point b, the switching point a and the switching point b according to the control mode switching timing of this embodiment. As long as the conditions such as the power supply voltage and the magnet temperature of the motor are the same.

  The above is the main configuration of the first embodiment. Here, main differences between the present embodiment and the prior art will be described. In the prior art, when switching between current control and voltage phase control, it is necessary to provide a switching threshold determined based on a certain index (for example, motor drive efficiency) with a hysteresis region for preventing chattering. For this reason, for example, when the operating point related to the current value or voltage value that serves as an index for switching determination is stagnant in the hysteresis region, it is not possible to immediately switch at the point where switching is originally intended. I had to move on. On the other hand, since the switching threshold in this embodiment can avoid chattering by setting the mask time, it is not necessary to have a hysteresis region. Therefore, even if the operating point is conventional, the control mode can be switched immediately after a predetermined mask time has elapsed after reaching the switching threshold defined by a certain index even if the operating point is stagnant in the hysteresis region. Therefore, more efficient and stable control can be performed.

  As described above, according to the first embodiment, the current control mode for controlling the applied voltage to the motor so as to follow the current command value, and the voltage phase control for controlling the applied voltage to the motor by performing feedback operation on the voltage phase. In the motor control device that switches the control mode to and from the mode, the switching from the current control mode to the voltage phase control mode or the switching from the voltage phase control mode to the current control mode is determined according to a predetermined switching condition. To do. Then, the elapsed time from when it is determined to switch the control mode is continuously measured as long as the determination does not change, and it is determined whether or not the measured time has exceeded a predetermined time. If it is determined that the elapsed time from the time when it is determined to switch the control mode has exceeded a predetermined time, the current control mode is changed to the voltage phase control mode or the voltage based on the determination according to the predetermined switching condition described above. The control mode is switched from the phase control mode to the current control mode. As a result, after reaching a switching threshold determined by a certain index as a switching determination index, the control mode can be switched quickly before and after the switching threshold.

Further, according to the first embodiment, the mask time is longer than the update period of the d-axis voltage command value V _di ^* and the q-axis voltage command value V _qi ^{* in} the current control mode. As a result, even when switching chattering occurs in the switching line related to the transition from the current control mode to the voltage phase control mode, the control mode is switched after the mask time longer than the update period of the voltage command value has elapsed. The response follows the value, and stable control is possible without disturbing the current.

Further, according to the first embodiment, the mask time is longer than the update period of the voltage command values V _dv ^* and V _qv ^* in the voltage phase control mode. Thereby, even when switching chattering occurs in the switching line related to the transition from the voltage phase control mode to the current control mode, the control mode is switched after the mask time longer than the update period of the voltage command value, The response follows the target value, and stable control is possible without disturbing the current.

  Further, according to the first embodiment, the mask time is set based on the time constant of the torque response. As a result, the mask time is set within the time considering the torque response without being excessively long, so that even in situations where switching frequently occurs, the control mode can be set without stagnation of the operating point. You can switch quickly.

(Second Embodiment)
FIG. 4 is a block diagram illustrating the configuration of the motor control device according to the second embodiment. With reference to the block diagram according to the first embodiment shown in FIG. 1, the input of the d-axis current detection value _id and the q-axis current detection value _iq is added to the control mode determination unit 21 in this embodiment. Has been. In the present embodiment, as the current vector norm calculated based on the dq-axis current according to the d-axis current detection value i _d and the q-axis current detection value i _q is large, increases the mask time. In driving an AC motor, the influence of current disturbance increases as the dq-axis current during control mode transition increases. Therefore, by detecting the dq-axis current when the control mode switching determination is requested and increasing the mask time as the current increases, current responsiveness can be improved and current disturbance can be suppressed.

  As described above, according to the second embodiment, the mask time is the current detection value when the current control transition determination unit 20 requests control mode switching and when the voltage phase control transition determination unit 19 requests control mode switching. The larger the value, the larger the setting. Thereby, the current responsiveness is improved, and the disturbance of the current can be suppressed.

(Third embodiment)
FIG. 5 is a block diagram illustrating the configuration of the motor control device according to the third embodiment. Based on the block diagram according to the first embodiment shown in FIG. 1, in this embodiment, the control mode determination unit 21 determines whether to shift to voltage phase control, which is output from the voltage phase control transition determination unit 19. An input of a deviation V ′ between the threshold value and the current determination value and a deviation I ′ output from the current control shift determination unit 20 between the shift determination threshold value for current control and the current determination value are added. In the present embodiment, when the voltage deviation V ′ or the current deviation I ′ is equal to or larger than a predetermined set value, the control mode is forcibly switched even within the mask time. The control flow will be described with reference to FIG.

  FIG. 6 is a flowchart for one control calculation of the control mode determination unit 21 in the third embodiment. The control calculation flow in the first embodiment differs from the processing after NO determination in step S3 during current control and the processing after NO determination in step S5 during voltage phase control.

  In the current control mode, if the elapsed time since the shift to the voltage phase control mode is requested does not reach the mask time (NO in step S3), the process proceeds to step S6.

  In step S6, the voltage deviation V 'described above is compared with a predetermined set value. If the voltage deviation V ′ is greater than or equal to a predetermined set value, the transition to the voltage phase control mode is forcibly executed even before the mask time has elapsed.

  Similarly, also in the voltage phase control mode, when the elapsed time since the shift to the current control mode is requested does not reach the mask time (NO in step S5), the process proceeds to step S7.

  In step S7, the above-described current deviation I 'is compared with a predetermined set value. If the current deviation I 'is greater than or equal to a predetermined set value, the transition to the current control mode is forcibly executed even before the mask time has elapsed.

  Thus, in this embodiment, even if the elapsed time from the control mode transition request is before the mask time has elapsed, if the voltage deviation V ′ or the current deviation I ′ is greater than or equal to a predetermined value, the control mode is forcibly controlled. To migrate. By doing so, a sudden load change caused by shifting the control mode in a state where the voltage deviation V ′ and the current deviation I ′, which are deviations between the control mode threshold and the current detection value, are larger than predetermined values. It becomes possible to suppress the torque shock at the time.

  As described above, according to the third embodiment, the switching from the current control mode to the voltage phase control mode or the switching from the voltage phase control mode to the current control mode is compared with the predetermined switching threshold value and the predetermined determination value. When determining according to the switching condition based on the above, it is determined that the voltage phase control transition determination unit 19 or the current control transition determination unit 20 switches the control mode, and the voltage deviation V ′ or the current deviation I ′ is a predetermined value. If it is greater than the predetermined time, the control mode is switched even if the mask elapsed time has not exceeded the predetermined time. Thereby, since the shift of the control mode in the state where the deviation between the threshold value related to the control mode shift and the current determination value is excessively large is avoided, the torque shock at the time of sudden load change can be suppressed.

  The present invention is not limited to the embodiment described above.

18 ... Control mode switching device (control mode switching means)
19 ... Voltage phase control transition determining section (control mode switching determining means)
20 ... Current control transition determination unit (control mode switching determination means)
21 ... Control mode determination unit (control mode switching means, mask time measurement means, mask time elapsed determination means)

Claims (6)

An electric motor that switches a control mode between a current control mode that controls the voltage applied to the motor so as to follow the current command value and a voltage phase control mode that controls the voltage applied to the motor by feedback operation of the voltage phase. In the control device of
Control mode switching determination means for determining switching from the current control mode to the voltage phase control mode or switching from the voltage phase control mode to the current control mode according to a predetermined switching condition;
Mask time measuring means that continues to measure the elapsed time from when the control mode switching determining means determines to switch the control mode, as long as the determination does not change,
Mask time elapse determining means for determining whether or not the time measured by the mask time measuring means has exceeded a predetermined time; and
When it is determined that the time measured by the mask time measuring unit has exceeded the predetermined time, the voltage phase control mode is changed from the current control mode, depending on the determination by the control mode switching determination unit, or e Bei a control mode changeover means from voltage phase control mode switches the control mode to the current control mode, and
The predetermined time is greater than the update period of the voltage command value calculated in the current control mode,
An electric motor control device. The predetermined time is greater than the update period of the voltage command value calculated in the voltage phase control mode,
The motor controller according to claim 1, characterized in that. An electric motor that switches a control mode between a current control mode that controls the voltage applied to the motor so as to follow the current command value and a voltage phase control mode that controls the voltage applied to the motor by feedback operation of the voltage phase. In the control device of
Control mode switching determination means for determining switching from the current control mode to the voltage phase control mode or switching from the voltage phase control mode to the current control mode according to a predetermined switching condition;
Mask time measuring means that continues to measure the elapsed time from when the control mode switching determining means determines to switch the control mode, as long as the determination does not change,
Mask time elapse determining means for determining whether or not the time measured by the mask time measuring means has exceeded a predetermined time; and
When it is determined that the time measured by the mask time measuring unit has exceeded the predetermined time, the voltage phase control mode is changed from the current control mode, depending on the determination by the control mode switching determination unit, or Control mode switching means for switching the control mode from the voltage phase control mode to the current control mode,
The predetermined time is greater than the update period of the voltage command value calculated in the voltage phase control mode,
An electric motor control device. Setting the predetermined time based on a time constant of torque response;
The motor control device according to claim 1, wherein the motor control device is a motor control device. The predetermined time is set to be larger as the value of the current flowing through the electric motor is larger when the control mode switching determination unit determines to switch the control mode.
The motor control device according to claim 1, wherein the motor control device is a motor control device. The control mode switching determination means switches the current control mode to the voltage phase control mode or switches from the voltage phase control mode to the current control mode with a predetermined switching threshold and a predetermined determination value. When judging according to the switching condition based on the comparison,
The control mode switching unit determines that the control mode switching determination unit switches the control mode, and when a deviation between the predetermined switching threshold and the predetermined determination value reaches a predetermined set value or more. The control mode is switched even if the time measured by the mask time measuring means has not passed the predetermined time.
The motor control device according to claim 1, wherein the motor control device is a motor control device.

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