JP6751495B2 - Automobile - Google Patents

Description

The present invention relates to an automobile, and more particularly to an automobile including a motor, an inverter, a battery, and a boost converter.

Conventionally, as a drive control device for an electric motor, the voltage phase is adjusted so that the difference between the output torque of the electric motor and the torque command value becomes 0 when a square wave voltage is applied from the inverter to the electric motor to drive the motor in rotation. Has been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-050689

In an automobile equipped with the above-mentioned drive control device for an electric motor, when a rectangular wave voltage is applied to the electric motor to drive it rotationally, the phase of fluctuation of the output torque of the electric motor and the fluctuation of the input voltage of the inverter due to disturbance from the road surface or the like. In agreement with the phase of, the fluctuation of the input voltage of the inverter promotes (increases) the fluctuation of the output torque of the motor, which may deteriorate the drivability.

The main object of the automobile of the present invention is to suppress deterioration of drivability.

The vehicle of the present invention employs the following means in order to achieve the above-mentioned main object.

The automobile of the present invention is
With the motor connected to the drive wheels
The inverter that drives the motor and
With the battery
A boost converter that exchanges power with voltage conversion between the low-voltage side power line to which the battery is connected and the high-voltage side power line to which the inverter is connected.
A control device that controls the inverter and the boost converter,
A car comprising:
When controlling the inverter in the square wave control mode, the control device uses the boost converter so that the voltage of the high voltage side power line fluctuates in the same period and in the opposite phase with respect to the torque fluctuation of the motor. Control,
The gist is that.

In the automobile of the present invention, when the inverter is controlled by the square wave control mode, the boost converter is controlled so that the voltage of the high voltage side power line fluctuates in the same period and in the opposite phase with respect to the torque fluctuation of the motor. .. By fluctuating the voltage of the high-voltage side power line in this way, it is possible to suppress large fluctuations in the torque of the motor (fluctuations in the torque output to the drive wheels). As a result, deterioration of drivability can be suppressed.

In such an automobile of the present invention, when the control device controls the inverter in the square wave control mode and the rotation fluctuation of the motor is larger than a predetermined fluctuation, the voltage of the high voltage side power line is the motor. The boost converter may be controlled so as to fluctuate in the same period and in the opposite phase with respect to the torque fluctuation of the above. When the rotation fluctuation of the motor is large, it is considered that the torque fluctuation of the motor is large. Therefore, it is of great significance to perform the above-mentioned control.

It is a block diagram which shows the outline of the structure of the electric vehicle 20 which mounts the drive device as one Example of this invention. It is a flowchart which shows an example of the step-up control routine executed by the electronic control unit 50 of an Example. It is explanatory drawing which shows an example of the state of time change of the torque Tm of a motor 32 and the voltage VH of a high voltage side power line 42.

Next, modes for carrying out the present invention will be described using examples.

FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 equipped with a drive device as an embodiment of the present invention. As shown in the figure, the electric vehicle 20 of the embodiment includes a motor 32, an inverter 34, a battery 36, a step-up converter 40, and an electronic control unit 50.

The motor 32 is configured as a synchronous generator motor, and includes a rotor in which a permanent magnet is embedded and a stator in which a three-phase coil is wound. The rotor of the motor 32 is connected to a drive shaft 26 connected to the drive wheels 22a and 22b via a differential gear 24.

The inverter 34 is connected to the motor 32 and is connected to the boost converter 40 via the high voltage side power line 42. The inverter 34 has transistors T11 to T16 as six switching elements and six diodes D11 to D16. Two transistors T11 to T16 are arranged in pairs so as to be on the source side and the sink side with respect to the positive electrode bus and the negative electrode bus of the high voltage side power line 42, respectively. The six diodes D11 to D16 are connected in parallel to the transistors T11 to T16 in opposite directions, respectively. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motor 32 is connected to each of the connection points between the transistors that are a pair of the transistors T11 to T16. Therefore, when a voltage is applied to the inverter 34, the electronic control unit 50 adjusts the ratio of the on-time of the paired transistors T11 to T16, so that a rotating magnetic field is formed in the three-phase coil and the motor. 32 is rotationally driven. Hereinafter, the transistors T11 to T13 may be referred to as an “upper arm”, and the transistors T14 to T16 may be referred to as a “lower arm”. A smoothing capacitor 46 is attached to the positive electrode bus and the negative electrode bus of the high voltage side power line 42.

The battery 36 is configured as, for example, a lithium ion secondary battery or a nickel hydrogen secondary battery, and is connected to the step-up converter 40 via a low voltage side power line 44. A smoothing capacitor 48 is attached to the positive electrode bus and the negative electrode bus of the low voltage side power line 44.

The boost converter 40 is connected to the high voltage side power line 42 and the low voltage side power line 44. The boost converter 40 has two transistors T31 and T32, two diodes D31 and D32, and a reactor L. The transistor T31 is connected to the positive electrode bus of the high voltage side power line 42. The transistor T32 is connected to the transistor T31 and the negative electrode bus of the high voltage side power line 42 and the low voltage side power line 44. The two diodes D31 and D32 are connected in parallel to the transistors T31 and T32 in opposite directions, respectively. The reactor L is connected to a connection point between the transistors T31 and T32 and a positive electrode bus of the low voltage side power line 44. The boost converter 40 supplies the power of the low voltage side power line 44 to the high voltage side power line 42 with the voltage boost by adjusting the ratio of the on-time of the transistors T31 and T32 by the electronic control unit 50. Or, the power of the high voltage side power line 42 is supplied to the low voltage side power line 44 with the voltage step down.

The electronic control unit 50 is configured as a microprocessor centered on the CPU 52, and includes a ROM 54 for storing a processing program, a RAM 56 for temporarily storing data, and an input / output port in addition to the CPU 52.

Signals from various sensors are input to the electronic control unit 50 via input ports. As signals input to the electronic control unit 50, for example, the rotation position θm from the rotation position detection sensor (for example, resolver) 32a that detects the rotation position of the rotor of the motor 32, and the current flowing through each phase of the motor 32 are detected. The phase currents Iu and Iv from the current sensors 32u and 32v can be mentioned. Further, the voltage VB from the voltage sensor 36a attached between the terminals of the battery 36 and the current IB from the current sensor 36b attached to the output terminal of the battery 36 can also be mentioned. Further, the voltage VH of the capacitor 46 (high voltage side power line 42) from the voltage sensor 46a attached between the terminals of the capacitor 46, and the capacitor 48 (low voltage side) from the voltage sensor 48a attached between the terminals of the capacitor 48. The voltage VL of the power line 44) can also be mentioned. In addition, the ignition signal from the ignition switch 60, the shift position SP from the shift position sensor 62 that detects the operating position of the shift lever 61, and the accelerator opening Acc from the accelerator pedal position sensor 64 that detects the amount of depression of the accelerator pedal 63. , The brake pedal position BP from the brake pedal position sensor 66 that detects the depression amount of the brake pedal 65 can also be mentioned. Further, the vehicle speed V from the vehicle speed sensor 68 can also be mentioned.

Various control signals are output from the electronic control unit 50 via the output port. Examples of the signal output from the electronic control unit 50 include a switching control signal for the transistors T11 to T16 of the inverter 34 and a switching control signal for the transistors T31 and T32 of the boost converter 40.

The electronic control unit 50 calculates the electric angle θe, the angular velocity ωm, and the rotation speed Nm of the motor 32 based on the rotation position θm of the rotor of the motor 32 from the rotation position detection sensor 32a. Further, the electronic control unit 50 calculates the storage ratio SOC of the battery 36 based on the integrated value of the current IB of the battery 36 from the current sensor 36b. Here, the storage ratio SOC is the ratio of the capacity of electric power that can be discharged from the battery 36 to the total capacity of the battery 36.

In the electric vehicle 20 of the embodiment configured in this way, the electronic control unit 50 performs the following traveling control. In the traveling control, the required torque Td * required for the drive shaft 26 is set based on the accelerator opening Acc from the accelerator pedal position sensor 64 and the vehicle speed V from the vehicle speed sensor 68, and the set required torque Td * is used as the motor. The torque command Tm * of 32 is set, and the switching control of the transistors T11 to T16 of the inverter 34 is performed so that the motor 32 is driven by the torque command Tm *. In the traveling control, the electronic control unit 50 controls the step-up converter 40 in addition to controlling the inverter 34. The control of the step-up converter 40 will be described later.

Here, the control of the inverter 34 will be described. Regarding the inverter 34, a sine wave PWM (pulse width modulation) control mode and overmodulation PWM are based on the target operating point (torque command Tm * and rotation speed Nm) of the motor 32 and the voltage VH of the high voltage side power line 42. Either the control mode or the square wave control mode is controlled as the control mode Md. Here, the sinusoidal PWM control mode is a control mode for controlling the inverter 34 so that a pseudo three-phase AC voltage is applied (supplied) to the motor 32, and the overmodulation PWM control mode is a control mode in which the overmodulation voltage is applied. It is a control mode that controls the inverter 34 so that it is applied to the motor 32, and the square wave control mode is a control mode that controls the inverter 34 so that the square wave voltage is applied to the motor 32. The control mode Md of the inverter 34 becomes a sine wave PWM control mode, an overmodulation PWM control mode, and a square wave control mode from the side where the rotation speed Nm of the motor 32 and the torque command Tm * are small to the large side, and the drive voltage. The higher the voltage VH of the system power line 42, the more the boundary between the sinusoidal PWM control mode and the overmodulation PWM control mode and the boundary between the overmodulation PWM control mode and the square wave control mode are the rotation speed Nm of the motor 32 and the torque command Tm *. Is set to move to the larger side. Hereinafter, the rectangular wave control mode will be described. Since the sine wave PWM control mode and the overmodulation PWM control mode do not form the core of the present invention, detailed description thereof will be omitted.

In the square wave control mode, the electronic control unit 50 first uses the electric angle θe of the motor 32, assuming that the total value of the currents flowing in the U phase, V phase, and W phase of the motor 32 is 0, and uses the U phase, Coordinate conversion (three-phase two-phase phase conversion) is performed on the V-phase phase currents Iu and Iv to the d-axis and q-axis currents Id and Iq. Subsequently, the output torque Tmest estimated to be output from the motor 32 is set based on the d-axis and q-axis currents Id and Iq. Then, using the output torque Tm of the motor 32 and the torque command Tm *, the voltage phase command θp * is calculated so that the difference between the output torque Tm and the torque command Tm * is canceled out. When the voltage phase command θp * is calculated in this way, a square wave signal is generated so that the square wave voltage based on the voltage phase command θp * is applied to the motor 32. Then, by outputting the rectangular wave signal to the inverter 34, switching control of the transistors T11 to T16 of the inverter 34 is performed.

Next, the operation of the electric vehicle 20 of the embodiment thus configured, particularly the control of the step-up converter 40 will be described. FIG. 2 is a flowchart showing an example of a boost control routine executed by the electronic control unit 50 of the embodiment. This routine is repeatedly executed every predetermined time (for example, several msec).

When the boost control routine is executed, the CPU 52 of the electronic control unit 50 first determines the rotation speed Nm of the motor 32, the amplitude Am and period tm of the rotation fluctuation, the torque command Tm * of the motor 32, the control mode Md of the inverter 34, and so on. Data such as the voltage VH of the high voltage side power line 42 is input (step S100). Here, the rotation number Nm of the motor 32 is calculated based on the rotation position θm of the rotor of the motor 32 from the rotation position detection sensor 32a. As the amplitude Am and the period tm of the rotation fluctuation of the motor 32, those calculated based on the rotation speed Nm of the motor 32 in the immediately preceding predetermined time (for example, about several hundred msec to 1 second) are input. The torque command Tm * of the motor 32 and the control mode Md of the inverter 34 are input to those set in the above process. As the voltage VH of the high voltage side power line 42, the voltage VH detected by the voltage sensor 46a is input.

When the data is input in this way, the basic required voltage VHtagmp as the basic value of the required voltage VHtag of the high voltage side power line 42 is set based on the torque command Tm * of the motor 32 and the rotation speed Nm (step S110). Here, in the embodiment, the basic required voltage VHtagmp is stored in the ROM 54 as a map by predetermining the relationship between the torque command Tm * of the motor 32 and the rotation speed Nm and the basic required voltage VHtagmp of the high voltage side power line 42. When the torque command Tm * of the motor 32 and the rotation speed Nm are given, the basic required voltage VHtagmpm of the corresponding high voltage side power line 42 is derived from this map and set.

Subsequently, it is determined whether or not the control mode Md of the inverter 34 is the square wave control mode (step S120), and the control mode of the inverter 34 is not the square wave control mode, that is, sine wave PWM control or overmodulation PWM control. When it is determined, normal values are set for each of the gains kp, ki, and kd of the proportional term, the integral term, and the differential term used for setting the target voltage VH * of the high voltage side power line 42 (step S140). The basic required voltage VHtagmp of the high voltage side power line 42 is set to the required voltage VHtag (step S150). The normal values of the gains kp, ki, and kd of the proportional term, the integral term, and the differential term are determined in consideration of the specifications of the step-up converter 40 and the like.

Then, based on the gains kp, ki, kd of the proportional term, the integral term, and the differential term, and the required voltage VHtag and the voltage VH of the high voltage side power line 42, the target voltage VH of the high voltage side power line 42 is calculated by the equation (1). * Is set (step S180), switching control of the transistors T31 and T32 of the boost converter 40 is performed using the set target voltage VH * of the high voltage side power line 42 (step S190), and this routine is terminated. Equation (1) is a relational expression of feedback control for canceling the difference between the voltage VH of the high voltage side power line 42 and the target voltage VH *. In the equation (1), the first term, the second term, and the third term on the right side are the proportional term, the integral term, and the differential term of the feedback terms, respectively.

When it is determined in step S120 that the control mode Md of the inverter 34 is the rectangular wave control mode, the amplitude Am of the rotational fluctuation of the motor 32 is compared with the threshold value Amref (step S130). Here, the threshold value Amref is a threshold value used for determining whether or not the amplitude Am of the rotational fluctuation of the motor 32 (the amplitude of the torque fluctuation of the motor 32) is relatively large. Here, the relationship between the rotation fluctuation of the motor 32 and the torque fluctuation will be described. The torque Tm of the motor 32 is the pole pair number P of the motor 32, the voltage VH of the high voltage side power line 42, the voltage phase θp and the modulation factor (value 0.78) in the rectangular wave control mode, the angular velocity ωm of the motor 32, and the magnetic flux (value 0.78). The induced voltage constant) can be obtained by Eq. (2) using φ and the d-axis and q-axis inductances Ld and Lq. In the equation (2), the first term on the right side indicates the magnet torque, and the second term on the right side indicates the reluctance torque. From this equation (2), it can be seen that the torque Tm of the motor 32 decreases as the angular velocity ωm of the motor 32 increases, and the torque Tm of the motor 32 increases as the angular velocity ωm of the motor 32 decreases. Therefore, the larger the amplitude Am of the rotational fluctuation of the motor 32, the larger the amplitude of the torque fluctuation of the motor 32, and the period tm of the rotational fluctuation of the motor 32 and the period of the torque fluctuation become the same (phase of the rotational fluctuation and the torque fluctuation). The phases of are opposite to each other). Generally, when the control mode of the inverter 34 is the square wave control mode, the switching of the transistors T11 to T16 per cycle of the electric angle θe of the motor 32 is compared with the case of the sinusoidal PWM control or the overmodulation PWM control. Since the number of times is small and the controllability of the inverter 34 is low, it is considered that the amplitude Am (amplitude of torque fluctuation) of the rotation fluctuation of the motor 32 tends to increase due to disturbance from the road surface or the like.

When the amplitude Am of the rotation fluctuation of the motor 32 is less than the threshold value Amref in step S130, it is determined that the amplitude Am of the rotation fluctuation of the motor 32 (amplitude of the torque fluctuation of the motor 32) is not so large, and the above steps S140, S150, The processing of S180 and S190 is executed to end this routine.

When the amplitude Am of the rotational fluctuation of the motor 32 is equal to or greater than the threshold Amref in step S130, it is determined that the amplitude Am of the rotational fluctuation of the motor 32 (the amplitude of the torque fluctuation of the motor 32) is relatively large, and the phase of the rotational fluctuation of the motor 32. And, based on the period tm, the correction voltage ΔVH for correcting the basic required voltage VHtagtp of the high voltage side power line 42 and the gains kp, ki, kd of the proportional term, the integral term, and the differential term in the feedback control are set. (Step S160), the required voltage VHtag is set by adding the correction voltage ΔVH to the basic required voltage VHtagmp of the high voltage side power line 42 (step S170). Then, the processing of steps S180 and S190 described above is executed to end this routine.

Here, the correction voltage ΔVH and the gains kp, ki, and kd of the proportional term, the integral term, and the differential term are the phase and period tm of the rotational fluctuation of the motor 32 and the correction voltage ΔVH and the proportional term, the integral term, in the embodiment. The relationship between the gains kp, ki, and kd of the differential term is determined in advance by experiments and analysis, stored in the ROM 54 as a map, and when the phase and period tm of the rotational fluctuation of the motor 32 are given, it corresponds from this map. The correction voltage ΔVH and the gains kp, ki, and kd of the proportional term, the integral term, and the differential term were derived and set. The correction voltage ΔVH and the gain kp of the proportional term are such that the target voltage VH * of the high voltage side power line 42 obtained by the equation (1) has the same cycle as the rotation fluctuation cycle (torque fluctuation cycle) of the motor 32 and the motor 32. (Amplitude in which the torque fluctuation of the motor 32 is sufficiently suppressed when the phase of the torque fluctuation of the motor 32 and the phase of the fluctuation of the voltage VH of the high voltage side power line 42 are opposite to each other). It was decided to set it so that it fluctuates. Further, regarding the gains ki and kd of the integration term and the differential term, in the equation (1), when the gain ki of the integration term is increased, the phase of fluctuation of the target voltage VH * of the high voltage side power line 42 is delayed and the gain of the differential term is increased. Considering that when kd is increased, the fluctuation phase of the target voltage VH * of the high voltage side power line 42 advances, the fluctuation phase of the target voltage VH * of the high voltage side power line 42 is the phase of the torque fluctuation of the motor 32. It was set to be in opposite phase to. Using the correction voltage ΔVH set in this way and the gains kp, ki, and kd of the proportional term, the integral term, and the differential term, the target voltage VH * of the high voltage side power line 42 is set to control the boost converter 40. As a result, the voltage VH of the high voltage side power line 42 fluctuates in the same cycle as the cycle of the torque fluctuation of the motor 32 and in the phase opposite to the phase of the torque fluctuation of the motor 32. As a result, when the torque Tm of the motor 32 or the voltage VH of the high voltage side power line 42 fluctuates due to disturbance from the road surface, the torque fluctuation of the motor 32 (fluctuation of the torque output to the drive wheels 22a and 22b) is caused. It can be suppressed from becoming large. As a result, deterioration of drivability can be suppressed.

FIG. 3 is an explanatory diagram showing an example of a time change between the torque Tm of the motor 32 and the voltage VH of the high voltage side power line 42. In the figure, the solid line shows the state of the example, and the broken line shows the state of the comparative example. Here, as a comparative example, even when the control mode Md of the inverter 34 is the rectangular wave control mode and the amplitude Am of the rotational fluctuation of the motor 32 is equal to or greater than the threshold Amref, the gains kp and ki of the proportional term, the integral term, and the differential term are used. A case where a normal value is set for each of ， kd and the basic required voltage VHtag of the high voltage side power line 42 is set to the required voltage VHtag (processing of steps S140 and S150 is executed) is considered. In the case of the comparative example, the phase of the torque fluctuation of the motor 32 and the phase of the voltage fluctuation of the high voltage side power line 42 match due to disturbance from the road surface, and the voltage fluctuation of the high voltage side power line 42 causes the motor 32 to match. Torque fluctuations are encouraged (increased) and drivability may deteriorate. On the other hand, in the embodiment, when the amplitude Am of the rotational fluctuation of the motor 32 becomes equal to or higher than the threshold Amref, the voltage VH of the high voltage side power line 42 has the same period and the opposite phase to the torque fluctuation of the motor 32. Therefore, it is possible to prevent the torque fluctuation of the motor 32 (the fluctuation of the torque output to the drive wheels 22a and 22b) from becoming large. As a result, deterioration of drivability can be suppressed.

In the electric vehicle 20 of the above-described embodiment, when the control mode Md of the inverter 34 is the square wave control mode and the amplitude Am of the rotation fluctuation of the motor 32 is equal to or greater than the threshold Amref, the voltage VH of the high voltage side power line 42 is the motor. The boost converter 40 is controlled so as to fluctuate in the same period and in the opposite phase with respect to the torque fluctuation of 32. As a result, it is possible to prevent the torque fluctuation of the motor 32 (the fluctuation of the torque output to the drive wheels 22a and 22b) from becoming large. As a result, deterioration of drivability can be suppressed.

In the electric vehicle 20 of the embodiment, when the control mode Md of the inverter 34 is the square wave control mode and the amplitude Am of the rotation fluctuation of the motor 32 is equal to or greater than the threshold Amref, the voltage VH of the high voltage side power line 42 is the torque of the motor 32. The boost converter 40 is controlled so as to fluctuate in the same period and in the opposite phase with respect to the fluctuation. However, when the control mode Md of the inverter 34 is the rectangular wave control mode, the voltage VH of the high voltage side power line 42 with respect to the torque fluctuation of the motor 32 even when the amplitude Am of the rotation fluctuation of the motor 32 is less than the threshold Amref. The boost converter 40 may be controlled so as to fluctuate in the same period and in opposite phases.

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 will be described. In the embodiment, the motor 32 corresponds to the "motor", the inverter 34 corresponds to the "inverter", the battery 36 corresponds to the "battery", the boost converter 40 corresponds to the "boost converter", and the boost in FIG. The electronic control unit 50 that executes the control routine and controls the inverter 34 corresponds to the “control device”.

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. This is an example for specifically explaining the mode for carrying out the invention, and does not limit the elements of the invention described in the column of means for solving the problem. That is, the interpretation of the invention described in the column of means for solving the problem should be performed based on the description in the column, and the examples are the inventions described in the column of means for solving the problem. It is just a concrete example.

Although the embodiments for carrying out the present invention have been described above with reference to examples, the present invention is not limited to these examples, and various embodiments are used without departing from the gist of the present invention. Of course, it can be done.

INDUSTRIAL APPLICABILITY The present invention can be used in the automobile manufacturing industry and the like.

20 electric vehicle, 22a, 22b drive wheel, 24 differential gear, 26 drive shaft, 32 motor, 32a rotation position detection sensor, 32u, 32v, 36b current sensor, 34 inverter, 36 battery, 36a, 46a, 48a voltage sensor, 40 Boost converter, 42 high voltage side power line, 44 low voltage side power line, 46,48 capacitors, 50 electronic control unit, 52 CPU, 54 ROM, 56 RAM, 60 ignition switch, 61 shift lever, 62 shift position sensor, 63 Accelerator pedal, 64 Accelerator pedal position sensor, 65 Brake pedal, 66 Brake pedal position sensor, 68 Vehicle speed sensor, D11 to D16, D31, D32 diode, L reactor, T11 to T16, T31, T32 transistor.

Claims (1)

With the motor connected to the drive wheels
The inverter that drives the motor and
With the battery
A boost converter that exchanges power with voltage conversion between the low-voltage side power line to which the battery is connected and the high-voltage side power line to which the inverter is connected.
A control device that controls the inverter and the boost converter,
A car comprising:
When controlling the inverter in the rectangular wave control mode, the control device is the same for the torque fluctuation of the motor based on the torque command and the rotation speed of the motor and the phase and period of the rotation fluctuation of the motor. The target voltage of the high voltage side power line is set so as to fluctuate periodically and in opposite phase, and the boost converter is controlled using the target voltage .
Automobile.

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