JP6668933B2 - Car - Google Patents

Description

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

  2. Description of the Related Art Conventionally, an automobile of this type includes an electric motor, and a power conversion device having an inverter circuit that drives the electric motor by switching a plurality of switching elements. There has been proposed a technique in which pulse signals of a plurality of switching elements are generated based on a voltage modulation rate and a voltage phase based on a command to perform switching of the plurality of switching elements (for example, see Patent Document 1). In this vehicle, by generating a pulse signal based on the number of pulses, the modulation factor, and the voltage phase such that the power loss of the power conversion device and the motor is minimized, the loss of the entire drive system including the power conversion device and the motor is reduced. Is being reduced.

JP 2013-162660 A

  However, in the above-described vehicle method, the temperature of the switching elements may be increased by the switching of the switching elements being repeated, and the switching elements may be overheated.

  An object of the present invention is to suppress overheating of a plurality of switching elements of an inverter.

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

The vehicle of the present invention
A motor for traveling,
An inverter that drives the motor by switching a plurality of switching elements;
A battery that exchanges power with the motor via the inverter;
A PWM signal is generated based on a switching angle based on a modulation rate and a voltage phase of a voltage based on a torque command of the motor, and a number of pulses of a predetermined period of an electrical angle of the motor, and a switching pattern at the switching angle. A control device for switching the plurality of switching elements,
A vehicle comprising:
When the temperature of the plurality of switching elements is high, the control device increases the number of the switching angles when the phase current of the motor is within a predetermined range including a value 0, as compared to when the temperature of the plurality of switching elements is low,
That is the gist.

  In the vehicle according to the present invention, a plurality of switching operations are performed based on a switching pattern based on a switching rate and a switching angle based on a voltage modulation rate and a voltage phase based on a motor torque command, and the number of pulses in a predetermined cycle of a motor electrical angle. A plurality of switching elements are switched by generating a PWM signal of the elements. When the temperature of the plurality of switching elements is high, the number of switching angles when the phase current of the motor is within a predetermined range including the value 0 is larger than when the temperature is low. Thus, when the temperature of the plurality of switching elements is high, the number of times of switching of the plurality of switching elements when the absolute value of the phase current of the motor is relatively large is smaller than when the temperature is low. As a result, it is possible to suppress an increase in the temperature of the plurality of switching elements and to suppress overheating. Further, when the temperature of the plurality of switching elements is relatively low, a PWM signal is generated so as to reduce iron loss of the motor, and a PWM signal is generated so as to reduce harmonics of voltage and current. It is possible to reduce iron loss and harmonics of the motor. Here, the “switching angle” means an angle at which a phase voltage of each phase of the motor (switching on / off of a switching element of a corresponding phase among a plurality of switching elements) is switched. “Switching pattern” means a combination of on and off of a plurality of switching elements.

1 is a configuration diagram illustrating an outline of a configuration of an electric vehicle 20 as one embodiment of the present invention. 5 is a flowchart illustrating an example of a pulse pattern setting routine executed by the electronic control unit 50 according to the embodiment. FIG. 11 is an explanatory diagram showing an example of a change in a PWM signal of a U-phase (transistor T11) when the switching element temperature Tsw is equal to or lower than a threshold Tswref. FIG. 11 is an explanatory diagram showing an example of a change in a PWM signal of a U-phase (transistor T11) when the switching element temperature Tsw is higher than a threshold Tswref. FIG. 11 is an explanatory diagram illustrating an example of a high-temperature state pulse pattern PPa of a modified example. It is a block diagram showing the outline of the composition of hybrid car 120 of a modification.

  Next, an embodiment for carrying out the present invention will be described using an embodiment.

  FIG. 1 is a configuration diagram schematically showing the configuration of an electric vehicle 20 as one embodiment of the present invention. As illustrated, the electric vehicle 20 of the embodiment includes a motor 32, an inverter 34, a battery 36, a boost converter 40, and an electronic control unit 50.

  The motor 32 is configured as a synchronous generator motor, and includes a rotor in which permanent magnets are 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 to the boost converter 40 via the high-voltage power line 42. The inverter 34 has transistors T11 to T16 as six switching elements and six diodes D11 to D16. The transistors T11 to T16 are arranged in pairs each of which is on the source side and the sink side with respect to the positive and negative buses of the high-voltage power line 42. The six diodes D11 to D16 are respectively connected in parallel to the transistors T11 to T16 in the reverse direction. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motor 32 is connected to each of the connection points of the pair of 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 pair of transistors T11 to T16, thereby forming a rotating magnetic field in the three-phase coil, and 32 is driven to rotate. Hereinafter, the transistors T11 to T13 may be referred to as “upper arm”, and the transistors T14 to T16 may be referred to as “lower arm”. The inverter 34 is provided with a temperature sensor 34a for detecting the temperature of the substrate of the inverter 34. In the embodiment, the temperature of the substrate of the inverter 34 detected by the temperature sensor 34a is used as the switching element temperature Tsw of the transistors T11 to T16. A smoothing capacitor 46 is attached to the positive bus and the negative bus of the high-voltage power line 42.

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

  Boost converter 40 is connected to high-voltage power line 42 and low-voltage power line 44. This 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 bus of the high-voltage power line 42. The transistor T32 is connected to the transistor T31 and the negative bus of the high-voltage power line 42 and the low-voltage power line 44. The two diodes D31 and D32 are connected in parallel in opposite directions to the transistors T31 and T32, respectively. Reactor L is connected to a connection point between transistors T31 and T32 and to a positive bus of low-voltage power line 44. The boost converter 40 supplies the power of the low-voltage power line 44 to the high-voltage 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 power line 42 is supplied to the low-voltage power line 44 with the voltage step-down.

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

  Signals from various sensors are input to the electronic control unit 50 via input ports. The signals input to the electronic control unit 50 include, for example, a rotational position θm from a rotational position detection sensor (for example, a resolver) 32 a that detects the rotational position of the rotor of the motor 32, and a current flowing in each phase of the motor 32. Phase currents Iu and Iv from current sensors 32u and 32v, and switching element temperature Tsw from temperature sensor 34a. Further, a voltage VB from a voltage sensor 36a attached between terminals of the battery 36 and a current IB from a current sensor 36b attached to an output terminal of the battery 36 can also be mentioned. Further, the voltage VH of the capacitor 46 (high-voltage power line 42) from the voltage sensor 46a attached between the terminals of the capacitor 46, and the capacitor 48 (low-voltage system) 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, an ignition signal from an ignition switch 60, a shift position SP from a shift position sensor 62 for detecting the operating position of the shift lever 61, and an accelerator opening Acc from an accelerator pedal position sensor 64 for detecting the amount of depression of an accelerator pedal 63. And a brake pedal position BP from a brake pedal position sensor 66 that detects the amount of depression of the brake pedal 65. Further, the vehicle speed VS from the vehicle speed sensor 68 can also be mentioned.

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

  The electronic control unit 50 calculates the electrical angle θe 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 rate 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 power storage ratio SOC is a ratio of the capacity of the 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 as described above, the electronic control unit 50 performs the following traveling control. In the traveling control, a required torque Td * required for the drive shaft 26 is set based on the accelerator opening Acc and the vehicle speed VS, and the set required torque Td * is set as a torque command Tm * of the motor 32. Are controlled by the torque command Tm * to control the switching of the transistors T11 to T16 of the inverter 34. Further, the target voltage VH * of the high-voltage power line 42 is set so that the motor 32 can be driven by the torque command Tm *, and the boost converter 40 is set so that the voltage VH of the high-voltage power line 42 becomes the target voltage VH *. Of the transistors T31 and T32.

  Here, the control of the inverter 34 will be described. In the embodiment, as the control of the inverter 34, any of sine wave PWM (pulse width modulation) control, overmodulation PWM control, and rectangular wave control is executed. The sine wave PWM control is a control for controlling the inverter 34 so that a pseudo three-phase AC voltage is applied (supplied) to the motor 32, and the overmodulation control is such that the overmodulation voltage is applied to the motor 32. The rectangular wave control is control for controlling the inverter 34 so that a rectangular wave voltage is applied to the motor 32. When the sine wave PWM control is executed, when the pulse width modulation voltage based on the sine wave voltage is a pseudo three-phase AC voltage, the modulation rate Rm takes a value of 0 to approximately 0.61, and the sine wave voltage is 3n order ( When the pulse width modulation voltage based on the superimposed voltage obtained by superimposing the (third) harmonic voltage is a pseudo three-phase AC voltage, the modulation rate Rm takes a value of 0 to approximately 0.71. The modulation rate Rm is the ratio of the effective value of the output voltage (the voltage applied to the motor 32) to the input voltage of the inverter 34 (the voltage VH of the high-voltage power line 42). In the embodiment, the pulse width modulation voltage based on the superimposed voltage is set to a pseudo three-phase AC voltage in order to increase the area of the modulation rate Rm in which the sine wave PWM control can be performed. When the rectangular wave control is performed, the modulation rate Rm is approximately 0.78. In the embodiment, based on the above, any one of the sine wave PWM control, the overmodulation PWM control, and the rectangular wave control is executed based on the modulation rate Rm. Hereinafter, the sine wave PWM control will be described. Since the overmodulation control and the rectangular wave control do not form the core of the present invention, detailed description will be omitted.

  In the embodiment, as the sine wave PWM control, in the embodiment, the transistors T11 to T11 are determined based on the voltage modulation rate Rm, the voltage phase θp, and the pulse number Np of a predetermined cycle (for example, a half cycle or one cycle of the electric angle θe of the motor 32). The PWM signal of T16 is generated to switch the transistors T11 to T16. In this case, a PWM signal is generated so as to reduce (for example, minimize) the iron loss of the motor 32, or a harmonic of a voltage or a current (particularly, a low-order harmonic such as the sixth or twelfth rotation of the motor 32). ) Can be reduced (for example, minimized), thereby reducing iron loss and harmonics of the motor 32. In this case, by generating a PWM signal so as to suppress (for example, minimize) the temperature rise of the transistors T11 to T16 due to switching, it is possible to suppress overheating of the transistors T11 to T16.

  Next, an operation of the electric vehicle 20 of the embodiment configured as described above, particularly, an operation when setting a pulse pattern of a PWM signal used for sine wave PWM control will be described. In the embodiment, the normal state pulse pattern PP and the high-temperature state pulse pattern PPa are used as the pulse pattern of the PWM signal, but details of each will be described later. FIG. 2 is a flowchart illustrating an example of a pulse pattern setting routine executed by the electronic control unit 50 according to the embodiment. This routine is repeatedly executed.

  When the pulse pattern setting routine is executed, the CPU 52 of the electronic control unit 50 first inputs data such as the switching element temperature Tsw (step S100). Here, the value detected by the temperature sensor 34a is input as the switching element temperature Tsw.

 When the data is input in this way, the switching element temperature Tsw is compared with a threshold value Tswref (step S110). Here, the threshold value Tswref is determined as a value that is somewhat lower than the allowable upper limit temperature of the transistors T11 to T16.

  If the switching element temperature Tsw is equal to or lower than the threshold value Tswref, the normal state pulse pattern PP is set (step S120), and the routine ends. Here, the normal state pulse pattern PP is a combination of the pulse type PT and the pulse number Np in the PWM control. In the embodiment, as the pulse type PT, a type PWMa that generates a PWM signal so as to reduce (for example, minimize) iron loss of the motor 32 or a harmonic (particularly, a lower harmonic) of a voltage or a current is reduced. A type PWMb that generates a PWM signal so as to minimize (for example, minimize) is used. In order to reduce the total loss of the motor 32 and the inverter 34, the pulse number Np is set to be smaller when the modulation rate Rm is large than when it is small. Therefore, when the switching element temperature Tsw is equal to or lower than the threshold value Tswref, iron loss of the motor 32 or harmonics of voltage and current can be reduced. FIG. 3 shows an example of how the PWM signal of the U phase (transistor T11) changes when the switching element temperature Tsw is equal to or lower than the threshold value Tswref. In FIG. 3, the type PWMa is used as the pulse type PT. Thereby, iron loss of the motor 32 can be reduced.

  On the other hand, when the switching element temperature Tsw is higher than the threshold value Tswref, the high-temperature state pulse pattern PPa is set (Step S130), and this routine ends. Here, the high-temperature state pulse pattern PPa is a combination of the pulse type PT and the pulse number Np in the PWM control, like the normal state pulse pattern PP. In the embodiment, the type PWMc that generates a PWM signal so as to suppress (for example, minimize) the temperature rise of the transistors T11 to T16 is used as the pulse type PT. In the case of the type PWMc, as compared with the type PWMa or the type PWMb, the switching angle (motor) when the phase current of each phase of the motor 32 is within a predetermined range including the value 0 (a range in which the temperatures of the transistors T11 to T16 do not become so large). The number of angles for switching the phase voltages of the 32 phases is increased. Therefore, when the switching element temperature Tsw is higher than the threshold value Tswref, the number of times of switching of the transistors T11 to T16 when the absolute value of the phase current of the motor 32 is relatively large is smaller than when the switching element temperature Tsw is equal to or lower than the threshold value Tswref. The number of pulses Np is the same as in the normal state pulse pattern PP. Therefore, when the absolute value of the phase current of the motor 32 is relatively large, the number of times of switching of the transistors T11 to T16 can be reduced, and the temperature of the transistors T11 to T16 (switching element temperature Tsw) is suppressed from rising. Accordingly, overheating of the transistors T11 to T16 can be suppressed. FIG. 4 shows an example of how the PWM signal of the U-phase (transistor T11) changes when the switching element temperature Tsw is higher than the threshold value Tswref. In FIG. 4, the type PWMc is used as the pulse type PT. Thereby, overheating of the transistors T11 to T16 can be suppressed.

  In the electric vehicle 20 of the embodiment described above, the normal state pulse pattern PP is set when the switching element temperature Tsw is equal to or lower than the threshold Tswref, and the high-temperature state pulse pattern PPa is set when the switching element temperature Tsw is higher than the threshold Tswref. . Accordingly, when the switching element temperature Tsw is equal to or lower than the threshold value Tswref, a PWM signal is generated so as to reduce iron loss of the motor 32, and a PWM signal is generated so as to reduce voltage and current harmonics. Accordingly, it is possible to reduce iron loss and harmonics of the motor 32. When the switching element temperature Tsw is higher than the threshold value Tswref, the number of switching angles when the phase current of each phase of the motor 32 is within a predetermined range including the value 0 becomes relatively large, and the temperature rise of the transistors T11 to T16 is suppressed. And overheating can be suppressed.

  In the electric vehicle 20 of the embodiment, as the pulse pattern of the PWM signal, the normal state pulse pattern PP is used when the switching element temperature Tsw is equal to or lower than the threshold Tswref, and the high temperature state pulse pattern PPa is used when the switching element temperature Tsw is higher than the threshold Tswref. However, when the switching element temperature Tsw is equal to or lower than the threshold Tswref, the normal state pulse pattern PP is used as the pulse pattern of the PWM signal. When it is higher than Tswref1, the high-temperature state pulse pattern PPa may be used. Here, the threshold value Tswref1 is a value higher than the threshold value Tswref, and the high-temperature state pulse pattern PPb generates the PWM signal so that the reduction of the iron loss of the motor 32 and the suppression of the temperature rise of the transistors T11 to T16 are compatible to some extent. And the number of pulses Np. By using such a pulse pattern of the PWM signal, when the switching element temperature Tsw is higher than the threshold value Tswref, the temperature rise of the transistors T11 to T16 can be suppressed, and overheating can be suppressed. As the pulse pattern of the PWM signal, the normal state pulse pattern PP may be used when the switching element temperature Tsw is equal to or lower than the threshold value Tswref, and the high temperature state pulse pattern PPc may be used when the switching element temperature Tsw is higher than the threshold value Tswref. Here, the high-temperature state pulse pattern PPc is a ratio of the number of switching angles when the phase current of each phase of the motor 32 is within a predetermined range including a value 0 to the number of pulses Np as shown in FIG. When Tsw is high, it is higher than when it is low. More specifically, it is a combination of a pulse type PT for generating a PWM signal and the number of pulses Np so as to become higher as the switching element temperature Tsw becomes higher. By using such a pulse pattern of the PWM signal, when the switching element temperature Tsw is higher than the threshold value Tswref, it is possible to more appropriately suppress the temperature rise of the transistors T11 to T16 according to the switching element temperature Tsw, and to prevent overheating. It can be suppressed more appropriately.

  In the electric vehicle 20 of the embodiment, the boost converter 40 is provided between the battery 36 and the inverter 34. However, the boost converter 40 may not be provided.

  The electric vehicle 20 of the embodiment has a configuration including the motor 32, the inverter 34, and the battery 36. However, as shown in a hybrid vehicle 120 of a modified example in FIG. 6, a configuration may be provided that includes an engine 122, a planetary gear 124, a motor 132, and an inverter 134 in addition to the motor 32 and the inverter 34. Here, a motor 132 is connected to the sun gear of the planetary gear 124, the engine 122 is connected to the carrier, and the drive shaft 26 and the motor 32 are connected to the ring gear. The inverter 134 is connected to the motor 132 and to the high-voltage power line 42.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of "Means for Solving the Problems" 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”, and the electronic control unit 50 corresponds to the “control device”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of the means for solving the problem is as follows. This is merely an example for specifically describing a mode for carrying out the invention, and thus does not limit the elements of the invention described in the section of “Means for Solving the Problems”. That is, the interpretation of the invention described in the section of the means for solving the problem should be interpreted based on the description of the section, and the embodiment is not limited to the invention described in the section of the means for solving the problem. This is only a specific example.

  As described above, the embodiments for carrying out the present invention have been described using the embodiments. However, the present invention is not limited to these embodiments at all, and various forms may be provided without departing from the gist of the present invention. Of course, it can be implemented.

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

  Reference Signs List 20 electric vehicle, 22a, 22b drive wheel, 24 differential gear, 26 drive shaft, 32, 132 motor, 32a rotation position detection sensor, 32u, 32v, 36b current sensor, 34, 134 inverter, 34a temperature sensor, 36 battery, 36a , 46a, 48a Voltage sensor, 40 boost converter, 42 high voltage system power line, 44 low voltage system power line, 46, 48 capacitor, 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, 120 hybrid vehicle, 122 Engine, 124 planetary gear, D11-D16, D31, D32 diode, L reactor, T11-T16, T31, T32 transistor.

Claims (1)

A motor for traveling,
An inverter that drives the motor by switching a plurality of switching elements;
A battery that exchanges power with the motor via the inverter;
A PWM signal is generated based on a switching angle based on a modulation rate and a voltage phase of a voltage based on a torque command of the motor, and a number of pulses of a predetermined period of an electrical angle of the motor, and a switching pattern at the switching angle. A control device for switching the plurality of switching elements,
A vehicle comprising:
When the temperature of the plurality of switching elements is high, the control device increases the number of the switching angles when the phase current of the motor is within a predetermined range including a value 0, as compared to when the temperature of the plurality of switching elements is low,
Car.

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