JP2010233376A - Car - Google Patents

Abstract

A reduction in voltage applied to a motor due to an inverter dead time is more appropriately compensated.
When overmodulation in which the amplitude of a carrier signal in pulse width modulation control is larger than the amplitude of a control phase voltage to be applied to each phase of the motor, each motor voltage with respect to the voltage applied to each phase of the motor The relationship between the voltage / current phase difference that is the current applied to the phase, the number of synchronizations that is the number of triangular wave voltages in the pulse width modulation control in the cycle of the motor control phase voltage, and the correction voltage is a predetermined map. On the other hand, the correction voltage is set by applying the voltage-current phase difference and the synchronization number, and the correction voltage is added to the control voltage to be applied to each phase of the motor based on the target torque of the motor, and the motor phase voltage command is set. To do.
[Selection] Figure 3

Description

  The present invention relates to an automobile.

  Conventionally, as a driving device for an electric motor mounted on this type of automobile, in order to prevent an arm short circuit of a switching element in an inverter switching control using pulse width modulation control so that a target voltage is applied to the electric motor. In consideration of the turn-off time (dead time), there has been proposed one that sets a target voltage of an electric motor (see, for example, Patent Document 1). In this drive device, the ratio of the dead time to the carrier period of the pulse width modulation control is multiplied by the voltage acting on the inverter to calculate the voltage drop applied to the motor due to the dead time, and the calculated voltage drop is used as the amplitude. By setting the target voltage of the motor using a sine wave correction voltage, current ripple due to the correction voltage can be reduced.

JP 2008-060883 A

  However, in the motor drive device described above, when the target voltage of the motor is overmodulated larger than the amplitude of the carrier signal in the pulse width modulation control, the correction voltage that compensates for the voltage drop due to dead time cannot be set appropriately. There is. When the pulse width modulation control is not overmodulation, the switching element of the inverter is turned on / off for each carrier period. On the other hand, when the pulse width modulation control is overmodulation, there is a period during which the inverter switching element is not turned on / off during the carrier period. The effect of dead time is different.

  The main object of the automobile of the present invention is to more appropriately compensate for a decrease in the voltage applied to the motor due to the dead time of the inverter when the pulse width modulation control of the inverter that drives the motor is overmodulated.

  In order to achieve the above-mentioned main object, the automobile of the present invention has taken the following measures.

The automobile of the present invention
It is set based on an electric motor capable of outputting driving power, an inverter capable of driving the electric motor, a battery capable of exchanging electric power with the electric motor via the inverter, and a target torque to be output from the electric motor. Further, a target phase voltage is set by adding a correction voltage corresponding to a dead time for preventing a short circuit of the switching element of the inverter to a control phase voltage to be applied to each phase of the electric motor, and the set target phase voltage Control means for switching control of the inverter so that is applied to each phase of the electric motor by pulse width modulation control,
The control means, when the amplitude of the target phase voltage is overmodulation larger than the amplitude of the carrier signal in the pulse width modulation control, the phase voltage applied to each phase of the motor and the phase applied to each phase of the motor. In a region where the voltage-current phase difference, which is a phase difference with respect to the current, is less than the first phase difference, the voltage-current phase difference tends to increase toward a predetermined voltage as the voltage-current phase difference increases. Regardless of the voltage-current phase difference, in a region where the voltage-current phase difference is greater than the first phase difference and greater than the first phase difference, the voltage-current phase difference is greater than the second phase difference. The larger the voltage-current phase difference, the larger the predetermined voltage, and the larger the control value, which is the ratio of the carrier frequency in the pulse width modulation control to the period of the control phase voltage, is larger. A voltage derived by applying the voltage-current phase difference and the control value to a predetermined map so that the first phase difference and the predetermined voltage are large and the second phase difference is small. Means for setting the correction voltage;
It is characterized by that.

  In the automobile according to the present invention, when the amplitude of the target phase voltage is overmodulation larger than the carrier signal in the pulse width modulation control, the phase voltage applied to each phase of the motor and the phase current applied to each phase of the motor. In a region where the voltage / current phase difference, which is a phase difference, is less than the first phase difference, the voltage / current phase difference tends to increase toward a predetermined voltage as the voltage / current phase difference increases, and the voltage / current phase difference is greater than or equal to the first phase difference. In a region that is greater than the phase difference and less than the second phase difference, regardless of the voltage-current phase difference, in a region where the voltage-current phase difference is greater than or equal to the second phase difference at a predetermined voltage, the voltage-current phase difference increases from the predetermined voltage. As the control value, which is the ratio of the carrier frequency in the pulse width modulation control to the cycle of the control phase voltage, increases, the first phase difference and the predetermined voltage increase and the second phase difference decreases. The voltage derived by applying the voltage-current phase difference and the control value to the predetermined map is set as a correction voltage corresponding to the dead time for preventing the short-circuit of the switching element of the inverter, and this correction voltage is The target phase voltage of the electric motor is set and the inverter is subjected to switching control so that the set target phase voltage is applied to each phase of the electric motor by pulse width modulation control. In this way, when the pulse width modulation control is overmodulation, the voltage-current phase difference and the control value are applied to a predetermined map, and a correction voltage is derived and set according to the inverter dead time. It is possible to more appropriately compensate for a decrease in the voltage applied to the motor due to the dead time.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 as one Example of this invention. 4 is a flowchart illustrating an example of a correction voltage setting routine that is executed by the electronic control unit 50 every predetermined time. It is explanatory drawing which shows an example of the correction voltage setting map.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 as an embodiment of the present invention. As shown in the figure, an electric vehicle 20 according to the embodiment includes a motor 22 having a rotor connected to drive wheels 28a and 28b via a differential gear 26, an inverter 24 for driving the motor 22, and an inverter 24. Phase currents from the battery 30 that exchanges power with the motor 22 and current sensors 22u and 22v that detect phase currents flowing in the U phase and V phase of the three-phase coils (U phase, V phase, and W phase) of the motor 22 And a shift position from a shift position sensor 52 that detects the position of the shift lever, an accelerator opening from an accelerator pedal position sensor 54 that detects the amount of depression of the accelerator pedal, and a brake pedal position sensor 56 that detects the amount of depression of the brake pedal The brake position and the vehicle speed from the vehicle speed sensor 58 are input to Comprising an electronic control unit 50 for controlling the entire vehicle such as motor 24.

  The inverter 24 includes six transistors T1 to T6 and six diodes D1 to D6 connected in parallel to the transistors T1 to T6 in the reverse direction. Each of the six transistors T1 to T6 is arranged in pairs such that a positive side bus connected to the positive electrode of the battery 30 and a negative bus connected to the negative electrode of the battery 30 are on the source side and the sink side. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motor 22 is connected to each connection point between the paired transistors. Therefore, the motor 22 can be driven by controlling the ratio of the on-time of the paired transistors T1 to T6.

  The electric vehicle 20 of the embodiment basically travels by drive control described below that is executed by the electronic control unit 50. In the electronic control unit 50, first, a target torque to be output from the motor 22 is set according to the accelerator opening from the accelerator pedal position sensor 54 and the vehicle speed from the vehicle speed sensor 58, and the set target torque and the rotation of the motor 22 are set. A control mode for controlling the inverter 24 is set based on the number of rotations of the motor 22 detected by a sensor (not shown) attached to the child. In the embodiment, the inverter 24 is controlled by pulse width modulation control for setting the ratio of the on-time of the transistors T1 to T6 by comparing the phase voltage command of the motor 22 and the triangular wave voltage (carrier signal). Sine wave control mode for generating a sinusoidal output voltage command value with an amplitude equal to or smaller than the carrier signal amplitude in pulse width modulation control, and a sinusoidal output voltage command with an amplitude exceeding the carrier signal amplitude in pulse width modulation control There is an overmodulation control mode for generating a value, and the sine wave control mode is set when the target torque or the rotational speed of the motor 22 is small, and the overmodulation control mode is set when the target torque or the rotational speed of the motor 22 is large. . Subsequently, the target current to be applied to the d-axis and q-axis of the motor 22 is set based on the target torque of the motor 22, and the feedback control is performed so that the current flowing through the d-axis and q-axis becomes the target current. To set the target voltage to be applied to the d-axis and q-axis, and the control target voltage to be applied to each phase of the three-phase coil of the motor 22 by setting the set target voltage to two-phase to three-phase. Here, the d-axis is the direction of the magnetic flux formed by the permanent magnet of the rotor of the motor 22, and the q-axis is advanced by an electrical angle of π / 2 in the direction in which the motor 22 is normally rotated with respect to the d-axis. Direction. Then, when the transistors T1 to T6 of the inverter 24 are switched on and off, the correction voltage corresponding to the dead time td for preventing both of the paired transistors from being turned on (time for turning off both of the paired transistors) td Vdead is added to the control phase voltage to set the phase voltage command for each phase of the motor 22, and the inverter 24 is switched so that the phase voltage command is applied to each phase of the motor 22 by pulse width modulation control according to the control mode. Control. By such control, it is possible to travel by outputting a target torque from the motor 22. The dead time td is a predetermined time based on the characteristics of the inverter 24 and the like.

  Next, a process for setting the correction voltage Vdead according to the dead time td in the drive control of the electric vehicle 20 according to the embodiment will be described. FIG. 2 is a flowchart showing an example of a correction voltage setting routine executed by the electronic control unit 50 every predetermined time (for example, every several msec). When the correction voltage setting routine is executed, the electronic control unit 50 determines the control mode of the inverter 24 set in the drive control (step S100). When the control mode is the sine wave control mode, the normal correction voltage setting is performed. Processing is executed (step S110), and this routine is terminated. In the normal correction voltage setting process, the voltage (voltage of the battery 30) Vi, the dead time td, the period of the triangular wave voltage (carrier period) tc in the pulse width modulation control, the d axis of the motor 22, q Based on the currents Id and Iq applied to the shaft, the correction voltage Vdead is calculated by the following equation (1). Here, the carrier period tc in the pulse width modulation control is set so as to decrease as the target torque or the rotational speed of the motor 22 increases in a carrier signal setting process (not shown) executed in parallel with this routine. Further, the currents Id and Iq applied to the d-axis and q-axis of the motor 22 are three-phase assuming that the sum of the phase currents applied to the respective phases is 0 from the phase currents from the current sensors 22u and 22v. Calculated by -2 phase conversion. Equation (1) is used to compensate for a drop in voltage applied to each phase of the three-phase coil of the motor 22 due to the dead time td when the transistors T1 to T6 of the inverter 24 are switched on and off for each carrier cycle tc. In the equation (1), the fractional portion including the currents Id and Iq applied to the d-axis and q-axis of the motor 22 is expressed by each phase relative to the voltage applied to each phase of the three-phase coil of the motor 22. A value corresponding to a voltage-current phase difference, which is a phase difference of current applied to. In the sine wave control mode, the above-described drive control is performed using the correction voltage Vdead set in this way, thereby compensating for a decrease in the voltage applied to each phase caused by the dead time td and from the motor 22 to the target torque. Torque close to can be output.

  On the other hand, when the control mode is the overmodulation control mode, an overmodulation correction voltage setting process is executed (step S120), and this routine is terminated. In the overmodulation correction voltage setting process, the voltage / current phase difference, which is the phase difference of the current applied to each phase with respect to the voltage applied to each phase of the three-phase coil of the motor 22, and the cycle of the control phase voltage of the motor 22. The correction voltage Vdead is set based on the number of synchronizations that is the number of triangular waves of the triangular wave voltage in the pulse width modulation control in FIG. Here, the voltage / current phase difference can be calculated based on the phase voltage command of the motor 22 and the phase current from the current sensors 22u and 22v. For example, the positive / negative in a predetermined phase of the phase voltage command is inverted. The calculation can be performed by dividing the difference between the time and the time when the detected phase current is inverted by the period of the phase voltage command. Further, the period of the control phase voltage of the motor 22 can be calculated based on the time when the control phase voltage becomes larger than the value 0 or the time when the phase voltage becomes smaller than the value 0, or based on the rotational speed of the motor 22. Specifically, the correction voltage Vdead when the control mode is the overmodulation control mode is illustrated in the electronic control unit 50 as a correction voltage setting map in which the relationship among the voltage / current phase difference, the synchronization number, and the correction voltage Vdead is determined in advance. In the storage area, the correction voltage Vdead corresponding to the stored map is derived and set from the stored map when the voltage-current phase difference and the synchronization number are given. FIG. 3 shows an example of the correction voltage setting map. In the figure, the solid line indicates the correction voltage Vdead when the synchronization number is relatively small, and the alternate long and short dash line indicates the correction voltage Vdead when the synchronization number is relatively large. As shown in the figure, the correction voltage Vdead is set so as to increase toward the predetermined voltage Vd as the voltage / current phase difference increases in a region where the voltage / current phase difference is less than the first phase difference θL. In a region where the phase difference is greater than or equal to the first phase difference θL and greater than the first phase difference θL and less than the second phase difference θH, a predetermined voltage Vd is set regardless of the voltage / current phase difference, and the voltage / current phase difference is equal to the second phase difference θH. In a region where the phase difference θH is equal to or larger than the predetermined voltage Vd, the voltage / current phase difference is set to increase. Further, when the number of synchronizations is large (one-dot chain line in the figure), the first phase difference θL and the predetermined voltage Vd are larger than those when the number of synchronizations is small (solid line in the figure) (in the figure, θL2> θL1, Vd2> Vd1), and the second phase difference θH tends to be small (θH2 <θH1 in the figure). Such a map can be determined in advance by an experiment for detecting a current with respect to a voltage applied to each phase of the motor 22 for each voltage-current phase difference or the number of synchronizations.

  Considering that the control mode is the sine wave control mode, the amplitude of the phase voltage command of the motor 22 is smaller than the amplitude of the carrier signal in the pulse width modulation control, and the transistors T1 to T6 of the inverter 24 are turned on / off for each carrier cycle tc. Is switched. On the other hand, when the control mode is the overmodulation control mode, the amplitude of the phase voltage command of the motor 22 is larger than the amplitude of the carrier signal in the pulse width modulation control, and the transistors T1 to T6 of the inverter 24 are turned on / off during the carrier period tc. There will be a period during which cannot be switched. Therefore, in the overmodulation control mode, the influence of the dead time is eliminated during a predetermined period, and the correction voltage Vdead cannot be calculated as in the sine wave control mode. Therefore, in the embodiment, in the overmodulation control mode, the correction voltage is applied by applying the voltage / current phase difference and the synchronization number to a map in which the relationship between the voltage / current phase difference, the synchronization number, and the correction voltage Vdead is predetermined. Vdead was derived and set. Thereby, even in the overmodulation control mode, a decrease in the voltage applied to the motor 22 due to the dead time td can be more appropriately compensated, and a torque closer to the target torque can be output from the motor 22. In addition, as a result, when the control mode is changed from the sine wave control mode to the overmodulation control mode, the phase voltage command of the motor 22 changes greatly, and the current applied to each phase of the motor 22 is disturbed. It is possible to prevent the torque output from the motor 22 from changing suddenly.

  According to the electric vehicle 20 of the embodiment described above, when the overmodulation mode is set, the voltage-current phase difference that is the current applied to each phase of the motor 22 with respect to the voltage applied to each phase of the motor 22 The voltage-current phase difference and the synchronization number with respect to a map in which the relationship between the number of triangles of the triangular wave voltage of the pulse width modulation control in the period of the control phase voltage of the motor 22 and the correction voltage Vdead is predetermined. Is applied to set the correction voltage Vdead, so that a decrease in the voltage applied to the motor 22 due to the dead time td of the inverter 24 in the overmodulation mode can be compensated more appropriately.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, when the motor 22 corresponds to “motor”, the inverter 24 corresponds to “inverter”, the battery 30 corresponds to “battery”, and the overmodulation mode is set, each phase of the motor 22 is set. In the region where the voltage / current phase difference, which is the current applied to each phase of the motor 22 with respect to the applied voltage, is less than the first phase difference θL, the correction voltage increases toward the predetermined voltage Vd as the voltage / current phase difference increases. Due to the tendency, in a region where the voltage-current phase difference is greater than or equal to the first phase difference θL and less than the second phase difference θH, the voltage-current phase difference is greater than or equal to the second phase difference VH at a predetermined voltage Vd regardless of the voltage-current phase difference. In the region, the larger the voltage-current phase difference, the larger the predetermined voltage Vd, and the larger the synchronization number, which is the number of triangular waves of the triangular wave voltage of the pulse width modulation control in the cycle of the control phase voltage of the motor 22. When the number of synchronizations is small, the first phase difference VL and the predetermined voltage Vd become larger and the second phase difference VH tends to become smaller as compared with the case where the number of synchronizations is small. The target torque to be output from the motor 22 is set and set according to the process of setting the correction voltage Vdead by applying the synchronization number, the accelerator opening from the accelerator pedal position sensor 54, and the vehicle speed from the vehicle speed sensor 58. The control mode for controlling the inverter 24 is set based on the target torque and the rotation speed of the motor 22, and the target current to be applied to the d-axis and q-axis of the motor 22 is set based on the target torque of the motor 22. The target voltage to be applied to the d-axis and q-axis is set by feedback control so that the current flowing in the d-axis and q-axis becomes the target current. The control voltage is set by adding the correction voltage Vdead to the control phase voltage to be applied to each phase of the three-phase coil of the motor 22 obtained by converting the target voltage into two-phase to three-phase, and setting the phase voltage command for each phase of the motor 22 The electronic control unit 50 that executes the switching control of the inverter 24 so that the phase voltage command is applied to each phase of the motor 22 by the pulse width modulation control according to the “control means”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the automobile manufacturing industry.

  20 electric vehicle, 22 motor, 22u, 22v current sensor, 24 inverter, 26 differential gear, 28a, 28b drive wheel, 30 battery, 50 electronic control unit, 52 shift position sensor, 54 accelerator pedal position sensor, 56 brake pedal position sensor , 58 Vehicle speed sensor, D1-D6 diode, T1-T6 transistor.

Claims (1)

It is set based on an electric motor capable of outputting driving power, an inverter capable of driving the electric motor, a battery capable of exchanging electric power with the electric motor via the inverter, and a target torque to be output from the electric motor. Further, a target phase voltage is set by adding a correction voltage corresponding to a dead time for preventing a short circuit of the switching element of the inverter to a control phase voltage to be applied to each phase of the electric motor, and the set target phase voltage Control means for switching control of the inverter so that is applied to each phase of the electric motor by pulse width modulation control,
The control means, when the amplitude of the target phase voltage is overmodulation larger than the amplitude of the carrier signal in the pulse width modulation control, the phase voltage applied to each phase of the motor and the phase applied to each phase of the motor. In a region where the voltage-current phase difference, which is a phase difference with respect to the current, is less than the first phase difference, the voltage-current phase difference tends to increase toward a predetermined voltage as the voltage-current phase difference increases. Regardless of the voltage-current phase difference, in a region where the voltage-current phase difference is greater than the first phase difference and greater than the first phase difference, the voltage-current phase difference is greater than the second phase difference. The larger the voltage-current phase difference, the larger the predetermined voltage, and the larger the control value, which is the ratio of the carrier frequency in the pulse width modulation control to the period of the control phase voltage, is larger. A voltage derived by applying the voltage-current phase difference and the control value to a predetermined map so that the first phase difference and the predetermined voltage are large and the second phase difference is small. Means for setting the correction voltage;
A car characterized by that.

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