JP2017093134A - Automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a voltage applied to a motor from exceeding the withstanding voltage thereof.SOLUTION: A permissible upper limit voltage VHmax of a high-voltage system power line is set so as to be lower when atmospheric pressure Pout is less than given pressure Pout1 than when the atmospheric pressure Pout is equal to or higher than the given pressure Pout1 to control a step-up converter so that the voltage of the high-voltage system power line is adjusted within a range of the permissible upper limit voltage VHmax. Further, a permissible upper limit voltage VHmax is set in a case where a torque instruction of a motor is equal to or less than given torque (Flag F being a value 1) in a zone where the atmospheric pressure Pout is less than given pressure Pout1 so that the permissible upper limit voltage is lower than in the case of the torque instruction being larger than the given torque (Flag F being a value 0).SELECTED DRAWING: Figure 4

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, this type of automobile includes a traveling motor, an inverter that drives the motor, a battery, and a converter that is connected to the battery and the inverter and adjusts a system voltage (input voltage of the inverter). In the configuration, there has been proposed one that controls the converter so that the system voltage is equal to or lower than the system voltage upper limit value (see, for example, Patent Document 1). In this automobile, the system voltage upper limit value is set in consideration of the surge voltage when the vehicle is not at high altitude, and the system voltage upper limit value for traveling at high altitude is set when the vehicle is at high altitude.

JP 2012-186905 A

  As a result of experiments and analysis, the inventor has found that the surge voltage is higher when driving the motor within a predetermined region as a predetermined low torque region and a predetermined rotation speed region than when driving the motor outside the predetermined region. I found it easy to grow. When the atmospheric pressure is relatively low (altitude is relatively high), the motor is driven within a predetermined area because the withstand voltage of the motor (the upper limit voltage that can ensure insulation between the conductors of each phase) becomes low. Then, it discovered that the voltage which acts on a motor with a surge voltage becomes easy to exceed the proof pressure of a motor.

  The main object of the automobile of the present invention is to suppress the voltage acting on the motor from exceeding the breakdown voltage of the motor.

  The automobile of the present invention has taken the following means in order to achieve the main object described above.

The automobile of the present invention
A motor for traveling,
An inverter for driving the motor;
Battery,
A boost converter connected to a first power line to which the battery is connected and a second power line to which the inverter is connected, and for adjusting a voltage of the second power line;
The allowable upper limit voltage of the second power line is set so that the atmospheric pressure is lower than the first predetermined atmospheric pressure when the atmospheric pressure is less than the first predetermined atmospheric pressure, and the voltage of the second power line is Control means for controlling the boost converter so as to be adjusted within a range of an allowable upper limit voltage or less;
A car equipped with
When the atmospheric pressure is less than the second predetermined atmospheric pressure which is equal to or less than the first predetermined atmospheric pressure and the torque of the motor is equal to or smaller than the predetermined torque, the control means is compared with when the torque of the motor is larger than the predetermined torque. Setting the allowable upper limit voltage to be low,
It is characterized by that.

  In this automobile of the present invention, the allowable upper limit voltage of the second power line is set so that the air pressure is lower than the first predetermined air pressure when the air pressure is lower than the first predetermined air pressure, and the second power line is set. The boost converter is controlled so that the voltage of is adjusted within the range of the allowable upper limit voltage or less. When the atmospheric pressure is less than the second predetermined atmospheric pressure below the first predetermined atmospheric pressure and the motor torque is below the predetermined torque, the allowable upper limit voltage is set to be lower than when the motor torque is larger than the predetermined torque. Set. The “motor torque” may be a command value or an output value (estimated value). The “predetermined torque” may be an upper limit torque in a region where the surge voltage is likely to increase (hereinafter referred to as “large surge region”). In the automobile of the present invention, when the atmospheric pressure is less than the second predetermined atmospheric pressure, when the motor torque is equal to or lower than the predetermined torque, the allowable upper limit voltage is made lower than when the motor torque is larger than the predetermined torque. Even when the motor is driven in the large surge region, the voltage acting on the motor due to the surge voltage can be prevented from exceeding the withstand voltage of the motor. Further, when the atmospheric pressure is less than the second predetermined atmospheric pressure, when the motor torque is larger than the predetermined torque, the allowable upper limit voltage is not lowered as much as the motor torque is lower than the predetermined torque. Can be suppressed.

  In the automobile of the present invention, the control means may be configured such that when the atmospheric pressure is less than the second predetermined atmospheric pressure, the torque of the motor is equal to or lower than the predetermined torque and the rotational speed of the motor is equal to or lower than the predetermined rotational speed. The allowable upper limit voltage is lower than when the torque is larger than the predetermined torque and when the torque of the motor is equal to or lower than the predetermined torque and the rotational speed of the motor is larger than the predetermined rotational speed. May be set. Here, the “predetermined number of revolutions” can be the upper limit number of revolutions in the large surge region. By so doing, it is possible to narrow the region where the allowable upper limit voltage is further lowered.

  In the automobile of the present invention, the control means is configured such that when the atmospheric pressure is less than the second predetermined atmospheric pressure, the torque of the motor is equal to or lower than the predetermined torque and the rotational speed of the motor is equal to or lower than the first predetermined rotational speed. 2 When the rotational speed is equal to or higher than the predetermined rotational speed, the torque of the motor is greater than the predetermined torque, and the torque of the motor is equal to or lower than the predetermined torque and the rotational speed of the motor is higher than the first predetermined rotational speed. The allowable upper limit voltage may be set to be lower than when it is larger or smaller than the second predetermined rotation speed. Here, as the “first predetermined rotation speed” and the “second predetermined rotation speed”, the upper limit rotation speed and the lower limit rotation speed of the large surge region can be used, respectively. By so doing, the region where the allowable upper limit voltage is lowered can be made narrower.

  In the automobile of the present invention, the control means controls the inverter in a pulse width modulation control mode or a rectangular wave control mode, and further, the control means controls the motor when the atmospheric pressure is less than the second predetermined atmospheric pressure. When the torque is less than the predetermined torque and the inverter is controlled in the pulse width modulation control mode, the torque of the motor is greater than the predetermined torque, and the torque of the motor is less than the predetermined torque and the inverter The allowable upper limit voltage may be set so as to be lower than when the control is performed in the rectangular wave control mode. The inventor has found that the surge voltage tends to increase when the motor torque is small and the inverter is controlled in the pulse width modulation control mode (particularly, the overmodulation control mode). Therefore, by setting the allowable upper limit voltage in this way, it is possible to narrow the region where the allowable upper limit voltage is further lowered.

  In the automobile of the present invention, the control means controls the inverter in any one of a sine wave control mode, an overmodulation control mode, and a rectangular wave control mode, and further, the control means has an atmospheric pressure of the second predetermined atmospheric pressure. When the motor torque is less than the predetermined torque and the inverter is controlled in the overmodulation control mode, the motor torque is greater than the predetermined torque, and the motor torque is the predetermined torque. The allowable upper limit voltage may be set to be lower than torque and lower than when the inverter is controlled in the sine wave control mode or the rectangular wave control mode. By so doing, the region where the allowable upper limit voltage is lowered can be made narrower.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 as one Example of this invention. It is a flowchart which shows an example of the allowable upper limit voltage setting routine performed by ECU50 of an Example. It is explanatory drawing which shows an example of a large surge area | region and a restriction | limiting area | region. It is explanatory drawing which shows an example of the map for an allowable upper limit voltage setting. It is explanatory drawing which shows an example of the restriction | limiting area | region of a modification. It is explanatory drawing which shows an example of the restriction | limiting area | region of a modification. It is explanatory drawing which shows an example of the restriction | limiting area | region of a modification. It is explanatory drawing which shows an example of the restriction | limiting area | region of a modification. It is explanatory drawing which shows an example of the map for the allowable upper limit voltage setting of a modification. It is explanatory drawing which shows an example of the map for the allowable upper limit voltage setting of a modification. It is explanatory drawing which shows an example of the map for the allowable upper limit voltage setting of a modification.

  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. The electric vehicle 20 according to the embodiment includes a motor 32, an inverter 34, a battery 36, a boost converter 40, and an electronic control unit (hereinafter referred to as ECU) 50, as illustrated.

  The motor 32 is configured as a synchronous generator motor, and includes a rotor in which a permanent magnet is embedded and a stator around which a three-phase coil is wound. The rotation shaft of the motor 32 is connected to a drive shaft 26 connected to the drive wheels 22 a and 22 b via a drive shaft (axle) 23 and a differential gear 24.

  The inverter 34 is connected to the boost converter 40 via the high voltage system power line 42. The inverter 34 includes six transistors T11 to T16 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 power line 42, respectively. 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 connection point between the transistors T11 to T16 as a pair. Therefore, when the voltage is applied to the inverter 34, the ECU 50 adjusts the ratio of the on-time of the paired transistors T11 to T16, thereby forming a rotating magnetic field in the three-phase coil and rotating the motor 32. Driven. A smoothing capacitor 46 is attached to the positive and negative buses of the high voltage system power line 42.

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

  Boost converter 40 is connected to high voltage system power line 42 and battery 36. Boost converter 40 includes 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 system power line 42. The transistor T32 is connected to the transistor T31 and the negative buses of the high voltage system power line 42 and the low voltage system power line 44. The two diodes D31 and D32 are respectively connected in parallel to the transistors T31 and T32 in the reverse direction. The reactor L is connected to a connection point between the transistors T31 and T32 and a positive bus of the low voltage system power line 44. The boost converter 40 supplies the power of the low voltage system power line 44 to the high voltage system power line 42 with voltage boost, by adjusting the on-time ratio of the transistors T31 and T32 by the ECU 50. The power of the high voltage system power line 42 is supplied to the low voltage system power line 44 with voltage step-down.

  Although not shown, the ECU 50 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU.

Signals from various sensors are input to the ECU 50 via input ports. Examples of the signal input to the ECU 50 include the following.
The rotational position θm from the rotational position detection sensor 32a that detects the rotational position of the rotor of the motor 32
The phase currents Iu and Iv of the U phase and V phase of the motor 32 from the current sensors 32u and 32v attached to the power line connecting the motor 32 and the inverter 34.
A battery voltage Vb from a voltage sensor attached between the terminals of the battery 36
Battery current Ib from a current sensor attached to the output terminal of battery 36
A battery temperature Tb from a temperature sensor attached to the battery 36
The voltage VH of the capacitor 46 (high voltage system power line 42) from the voltage sensor 46a attached between the terminals of the capacitor 46.
The voltage VL of the capacitor 48 (low voltage system power line 44) from the voltage sensor 48a attached between the terminals of the capacitor 48.
-Ignition signal from the ignition switch 60-Shift position SP from the shift position sensor 62 that detects the operation position of the shift lever 61
Accelerator opening degree Acc from the accelerator pedal position sensor 64 that detects the depression amount of the accelerator pedal 63
-Brake pedal position BP from the brake pedal position sensor 66 that detects the amount of depression of the brake pedal 65
・ Vehicle speed V from the vehicle speed sensor 68
・ Atmospheric pressure Pout from atmospheric pressure sensor 69

Various control signals are output from the ECU 50 via an output port. Examples of the signal output from the ECU 50 include the following.
Switching control signal to transistors T11 to T16 of inverter 34 Switching control signal to transistors T31 and T32 of boost converter 40

  The ECU 50 calculates the electrical angle θe and the rotational speed Nm of the motor 32 based on the rotational position θm of the rotor of the motor 32 detected by the rotational position detection sensor 32a. Further, the ECU 50 calculates the storage ratio SOC of the battery 36 based on the integrated value of the battery current Ib detected by the current sensor. Here, the storage ratio SOC is the ratio of the capacity of power that can be discharged from the battery 50 to the total capacity of the battery 36.

  In the electric vehicle 20 of the embodiment thus configured, the ECU 50 sets the required torque Td * required for traveling based on the accelerator opening Acc from the accelerator pedal position sensor 64 and the vehicle speed V from the vehicle speed sensor 68. To do. Subsequently, the required torque Td * is limited (upper limit guard) by the torque limit Tmax of the motor 32, and the torque command Tm * of the motor 32 is set. Here, the torque limit Tmax of the motor 32 is an upper limit of the torque that may be output from the motor 32 at the voltage VH of the high voltage system power line 42 and the rotational speed Nm of the motor 32. In the embodiment, the torque limit Tmax of the motor 32 is determined in advance and stored as a map of the relationship between the voltage VH of the high voltage system power line 42 and the rotational speed Nm of the motor 32 and the torque limit Tmax of the motor 32. Given the voltage VH of the high voltage system power line 42 and the rotational speed Nm of the motor 32, the torque limit Tmax of the corresponding motor 32 is derived from this map and set. Then, 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 *.

  Here, the control of the inverter 34 will be described. In the embodiment, the inverter 34 is performed by the ECU 50 in any one of the sine wave control mode, the overmodulation control mode, and the rectangular wave control mode. The sine wave control mode is a pulse width modulation (PWM) control mode in which the on-time ratio of the transistors T11 to T16 is adjusted by comparing the voltage command of the motor 32 and the carrier wave (triangular wave) voltage. This is a control mode in which a pseudo three-phase AC voltage obtained by converting an amplitude sinusoidal voltage command is supplied to the motor 32. The overmodulation control mode is a control mode in which an overmodulation voltage obtained by converting a sinusoidal voltage command having a larger amplitude than the amplitude of the triangular wave voltage is supplied to the motor 32 in the pulse width modulation control mode. The rectangular wave control mode is a control mode for supplying a rectangular wave voltage to the motor 32. In the sine wave control mode, the modulation factor (voltage utilization factor) Rm is in the range of value 0 to value Rref1 (about 0.61). In the overmodulation control mode, the modulation factor Rm is in the range of the value Rref1 (about 0.61) to the value Rref2 (about 0.78). In the rectangular wave control mode, the modulation factor Rm is constant at a value Rref2 (about 0.78). The modulation factor Rm is the ratio of the effective value of the output voltage (voltage acting on the motor 32) to the input voltage of the inverter 34.

  In the embodiment, the control mode of the inverter 34 is determined by setting the relationship between the torque command Tm * and the rotational speed Nm of the motor 32, the target voltage VH * of the high voltage system power line 42, and the control mode of the inverter 34 in advance. When the torque command Tm * and the rotation speed Nm of the motor 32 and the voltage VH of the high-voltage system power line 42 are given as a map for use in a ROM (not shown), the control mode of the corresponding inverter 34 is determined from this map. Derived and set. The control mode of the inverter 34 is determined so that the torque command Tm * and the rotational speed Nm of the motor 32 are changed to a sine wave control mode, an overmodulation control mode, and a rectangular wave control mode from the smaller absolute value side to the larger absolute value side. . The control mode of the inverter 34 is such that the higher the target voltage VH * of the high-voltage power line 42 is, the boundary (switching line) between the rectangular wave control mode and the overmodulation control mode, and the overmodulation control mode and sine wave control mode. Is defined such that the rotational speed Nm of the motor 32 and the torque command Tm * are shifted to the larger absolute value side.

  Further, the ECU 50 sets an allowable upper limit voltage VHmax of the high voltage system power line 42. The setting process of the allowable upper limit voltage VHmax will be described later. Subsequently, the target voltage VH * of the high voltage system power line 42 is set based on the torque command Tm * and the rotation speed Nm of the motor 32 and the allowable upper limit voltage VHmax of the high voltage system power line 42. In the embodiment, the target voltage VH * of the high voltage system power line 42 is the torque command Tm * and the rotational speed Nm of the motor 32, the allowable upper limit voltage VHmax of the high voltage system power line 42, and the target voltage of the high voltage system power line 42. A relationship with VH * is determined in advance and stored in a ROM (not shown) as a map. When a torque command Tm * and a rotational speed Nm of the motor 32 and an allowable upper limit voltage VHmax of the high voltage system power line 42 are given, The target voltage VH * of the corresponding high voltage system power line 42 is derived from the map and set. In the embodiment, the target voltage VH * of the high voltage system power line 42 is set in consideration of the efficiency of the entire vehicle within the range of the allowable upper limit voltage VHmax of the high voltage system power line 42. When the target voltage VH * of the high voltage system power line 42 is thus set, the switching control of the transistors T31 and T32 of the boost converter 40 is performed so that the voltage VH of the high voltage system power line 42 becomes the target voltage VH *.

  Next, the operation of the electric vehicle 20 of the embodiment thus configured, particularly the setting process of the allowable upper limit voltage VHmax of the high voltage system power line 42 will be described. FIG. 2 is a flowchart illustrating an example of an allowable upper limit voltage setting routine executed by the ECU 50 of the embodiment. This routine is executed repeatedly.

  When the allowable upper limit voltage setting routine is executed, the ECU 50 first inputs data such as the torque command Tm * of the motor 32, the rotation speed Nm, and the atmospheric pressure Pout (step S100). Here, as the torque command Tm * of the motor 32, a value set by the above-described control is input. As the rotational speed Nm of the motor 32, a value calculated based on the rotational position θm of the rotor of the motor 32 detected by the rotational position detection sensor 32a is input. As the atmospheric pressure Pout, a value detected by the atmospheric pressure sensor 69 is input.

  When the data is input in this way, the torque command Tm * of the motor 32 is compared with the predetermined torque Tm1, so that the target drive point (torque command Tm * and the rotational speed Nm) of the motor 32 is within the limited region including the large surge region. (Step S110), when the target drive point of the motor 32 is outside the limit region, the flag F is set to 0 (step S120), and when the target drive point of the motor 32 is within the limit region, A value 0 is set in the flag F (step S130). Here, the large surge region is a region that the inventor has discovered through experiments and analysis, and the surge voltage is likely to increase as compared with the outside of the large surge region when the motor 32 is driven. Further, the restriction region is a region that restricts (lowers) the allowable upper limit voltage VHmax as compared to outside the restriction region when the atmospheric pressure is relatively low (when the altitude is relatively high).

  FIG. 3 is an explanatory diagram illustrating an example of a large surge region and a limited region. In FIG. 3, the large surge region is a region where the torque command Tm * of the motor 32 is equal to or less than the predetermined torque Tm1, and the rotation speed Nm of the motor 32 is equal to or greater than the predetermined rotation speed Nm1 and equal to or less than the predetermined rotation speed Nm2. Further, the limited region is a region where the torque command Tm * of the motor 32 is equal to or less than the predetermined torque Tm1. For example, 8Nm, 10Nm, 12Nm, or the like can be used as the predetermined torque Tm1. As the predetermined rotational speed Nm1, 7500 rpm, 7600 rpm, 7700 rpm, or the like can be used. As the predetermined rotational speed Nm2, 7900 rpm, 800 rpm, 8100 rpm, or the like can be used.

  When the torque of the motor 32 is small, since the current flowing through the motor 32 is small, the direction of the current is easily reversed. Further, when controlling the inverter 34 in the overmodulation control mode, compared to when controlling the inverter 34 in the sine wave control mode or the rectangular wave control mode, in a specific phase range in one cycle of the electrical angle of the motor 32, The switching interval of the transistors T11 to T16 of the inverter 34 is shortened. In particular, when the modulation factor Rm is high (for example, about 0.76 to 0.78), the switching interval of the transistors T11 to T16 in this specific phase range becomes shorter. For these reasons, the surge voltage is likely to increase in the large surge region. For example, the predetermined torque Tm1 is set as an upper limit of a torque range in which the direction of the current flowing through the motor 32 is assumed to be easily reversed. Further, the predetermined rotation speeds Nm1 and Nm2 are set, for example, as lower and upper limits of a rotation speed range that is assumed to control the inverter 34 in the overmodulation control mode.

  When the flag F is thus set, the allowable upper limit voltage VHmax of the high voltage system power line 42 is set based on the atmospheric pressure Pout and the flag F (step S140). Here, the allowable upper limit voltage VHmax of the high voltage system power line 42 is determined in consideration of a margin on the negative side with respect to the withstand voltage of the motor 32 (upper limit voltage that can ensure insulation between the conductors of each phase). In the embodiment, the allowable upper limit voltage VHmax of the high voltage system power line 42 is illustrated as an allowable upper limit voltage setting map in which the relationship between the atmospheric pressure Pout and the flag F and the allowable upper limit voltage VHmax of the high voltage system power line 42 is determined in advance. When the atmospheric pressure Pout and the flag F are given, the allowable upper limit voltage VHmax of the corresponding high voltage system power line 42 is derived from this map and set. An example of the allowable upper limit voltage setting map is shown in FIG.

  In FIG. 4, the predetermined atmospheric pressure Pout1 can be, for example, 89 kPa, 90 kPa, 91 kPa, or the like (atmospheric pressure when the altitude is about 1000 m). The predetermined atmospheric pressure Pout2 can be set to 57 kPa, 58 kPa, 59 kPa, or the like, for example. The predetermined voltage VHmax1 can be set to 640V, 650V, 660V, or the like, for example. The predetermined voltage VHmax2 can be set to 480V, 485V, 490V, or the like, for example. The predetermined voltage VHmax3 can be set to 405V, 410V, 415V, or the like, for example.

  As shown in FIG. 4, when the flag F is 0 (when the target drive point of the motor 32 is outside the restricted region), the predetermined voltage VHmax1 is set to the allowable upper limit voltage VHmax in the region where the atmospheric pressure Pout is equal to or higher than the predetermined atmospheric pressure Pout1. It was supposed to be set. In addition, when the flag F is a value of 0, in a region where the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1 and higher than the predetermined atmospheric pressure Pout2, specifically, the atmospheric pressure Pout is lower than when the atmospheric pressure Pout is low. The allowable upper limit voltage VHmax is set so as to decrease linearly from the predetermined voltage VHmax1 toward the predetermined voltage VHmax2 as Pout decreases. Further, when the flag F is 0, the predetermined voltage VHmax2 is set to the allowable upper limit voltage VHmax in the region where the atmospheric pressure Pout is equal to or less than the predetermined atmospheric pressure Pout2.

  When the flag F is 1 (when the target drive point of the motor 32 is in the restricted region), the allowable upper limit voltage VHmax is set in the region where the atmospheric pressure Pout is equal to or greater than the predetermined atmospheric pressure Pout1, as in the case where the flag F is 0. The predetermined voltage VHmax1 is set. Further, when the flag F is a value 1, the region where the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1 and higher than the predetermined atmospheric pressure Pout2 is lower than when the atmospheric pressure Pout is low and higher than when the flag F is 0. Specifically, the allowable upper limit voltage VHmax is set so that the lower the atmospheric pressure Pout, the lower the predetermined voltage VHmax1 linearly from the predetermined voltage VHmax1 toward the predetermined voltage VHmax3 lower than the predetermined voltage VHmax2. . Further, when the flag F is 1, the predetermined voltage VHmax3 is set to the allowable upper limit voltage VHmax in the region where the atmospheric pressure Pout is equal to or less than the predetermined atmospheric pressure Pout2.

  As described above, the inventor has discovered that when the motor 32 is driven in the large surge region, the surge voltage is likely to be larger than when the motor 32 is driven outside the large surge region. When the atmospheric pressure Pout is lower than the predetermined atmospheric pressure Pout3 (for example, 69 kPa, 70 kPa, 71 kPa, etc. (such as atmospheric pressure when the altitude is about 3000 m)) lower than the predetermined atmospheric pressure Pout1, the pressure resistance of the motor 32 is lowered. It was discovered that when the motor 32 is driven in the large surge region, the voltage acting on the motor 32 due to the surge voltage tends to exceed the withstand voltage of the motor 32. Based on this, in the embodiment, when the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1, it is determined that the atmospheric pressure is relatively low (the altitude is relatively high), and when the flag F is 1 (the target drive point of the motor 32 is The allowable upper limit voltage VHmax of the high voltage system power line 42 is set to be lower than when the flag F is 0 (when the target drive point of the motor 32 is out of the limit area). did. Thereby, even when the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout3 and the motor 32 is driven in the large surge region, the voltage acting on the motor 32 by the surge voltage can be prevented from exceeding the withstand voltage of the motor 32. As a result, it is possible to allow the switching speed of the transistors T11 to T16 of the inverter 34 to be higher, so that the switching speed can be further increased and energy efficiency can be further improved. Further, when the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1, and the torque command Tm * of the motor 32 is larger than the predetermined torque Tm1, the allowable upper limit voltage VHmax is not lowered as much as the torque command Tm * is equal to or lower than the predetermined torque Tm1. It is possible to suppress a decrease in the output of the motor 32 and thus a decrease in running performance.

  The following can also be said. In the comparative example in which the uniform allowable upper limit voltage VHmax is set regardless of whether the flag F is 0 or 1, the motor 32 is driven even when the motor 32 is driven in the large surge region when the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout3. In order to ensure insulation between the conductors of the respective phases, it is necessary to design the thickness of the conductor film of each phase of the motor 32 in consideration of the surge voltage at this time. For this reason, when considering the case where the atmospheric pressure Pout is equal to or higher than the predetermined atmospheric pressure Pout3 or the case where the motor 32 is driven outside the large surge region, the thickness of the conductive film of each phase is designed to an excessive value. In the embodiment, in the region where the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1, when the flag F is a value 1, the allowable upper limit voltage VHmax of the high voltage system power line 42 is made lower than when the flag F is a value 0. Therefore, when considering the case where the atmospheric pressure Pout is equal to or higher than the predetermined atmospheric pressure Pout3 or when driving the motor 32 outside the large surge region, it is not necessary to design the thickness of the conductive film of each phase to an excessive value. It is possible to reduce the cost by reducing the thickness of the coating of the phase conducting wire as compared with the comparative example.

  Further, in the embodiment, when the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1, and the target drive point of the motor 32 is within the restricted region, the target drive point is within the large surge region even if the target drive point is outside the large surge region. As in the case, the allowable upper limit voltage VHmax is set (lower than when the target drive point is outside the limit region). As a result, even when the rotational speed Nm of the motor 32 is repeatedly increased or decreased near the predetermined rotational speed Nm1 or near the predetermined rotational speed Nm2, fluctuations in the allowable upper limit voltage VHmax of the high voltage power line 42 can be suppressed. Variations in the voltage VH of the voltage system power line 42 and, in turn, variations in the torque Tm of the motor 32 can be suppressed. Note that the limited region is a region where the torque command Tm * of the motor 32 is equal to or less than the predetermined torque Tm1, and therefore it is considered that the possibility of affecting the running performance is sufficiently low even if the allowable upper limit voltage VHmax is lowered. .

  In the electric vehicle 20 of the embodiment described above, the allowable upper limit voltage VHmax of the high voltage system power line 42 is set to be lower when the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1 as compared to when the atmospheric pressure Pout is equal to or higher than the predetermined atmospheric pressure Pout1. The voltage step-up converter 40 is controlled so that the voltage VH of the high-voltage power line 42 is adjusted within the allowable upper limit voltage VHmax. In a region where the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1, when the torque command Tm * of the motor 32 is equal to or less than the predetermined torque Tm1 (when the target drive point of the motor 32 is within the restricted region including the large surge region), the motor The allowable upper limit voltage VHmax is set to be lower than when the torque command Tm * of 32 is larger than the predetermined torque Tm1 (when the target drive point of the motor 32 is outside the limit region). Thereby, even when the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout3 and the motor 32 is driven in the large surge region, the voltage acting on the motor 32 by the surge voltage can be prevented from exceeding the withstand voltage of the motor 32. Further, when the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1, and the torque command Tm * of the motor 32 is larger than the predetermined torque Tm1, the allowable upper limit voltage VHmax is not lowered as much as the torque command Tm * is equal to or lower than the predetermined torque Tm1. It is possible to suppress a decrease in the output of the motor 32 and thus a decrease in running performance.

  In the electric vehicle 20 of the example, as shown in FIG. 3, the limited region is a region where the torque command Tm * of the motor 32 is equal to or less than the predetermined torque Tm1. However, as shown in FIG. 5, the limited region may be a region where the torque command Tm * of the motor 32 is equal to or smaller than the predetermined torque Tm1 and the rotational speed Nm of the motor 32 is equal to or smaller than the predetermined rotational speed Nm2. Further, as shown in FIG. 6, the limited region is a region where the torque command Tm * of the motor 32 is equal to or less than the predetermined torque Tm1, and the rotational speed Nm of the motor 32 is equal to or higher than the predetermined rotational speed Nm1 and equal to or lower than the predetermined rotational speed Nm2. It may be the same region as the large surge region. In these cases, a region where the allowable upper limit voltage VHmax of the high voltage system power line 42 is more restricted (a region where the allowable upper limit voltage VHmax is lower than outside the restricted region) can be made narrower.

  In the electric vehicle 20 of the example, as shown in FIG. 3, the limited region is a region where the torque command Tm * of the motor 32 is equal to or less than the predetermined torque Tm1. However, as shown in FIG. 7, the limited region may be a region where the torque command Tm * of the motor 32 is equal to or less than the predetermined torque Tm1 and the inverter 34 is controlled in the sine wave control mode or the overmodulation control mode. Further, as shown in FIG. 8, the torque command Tm * of the motor 32 may be a predetermined torque Tm1 or less and the inverter 34 may be controlled in the overmodulation control mode. These are based on the fact that the inventors found that the torque of the motor 32 is small and the surge voltage tends to increase when the inverter 34 is controlled in the overmodulation control mode.

  In the electric vehicle 20 of the embodiment, as shown in FIG. 4, when the flag F is 1 (when the target drive point of the motor 32 is in the restricted region), the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1 and the predetermined atmospheric pressure. In the region higher than Pout2, the allowable upper limit voltage VHmax is set so that the lower the atmospheric pressure Pout is, the lower it is linearly from the predetermined voltage VHmax1 toward the predetermined voltage VHmax3. The predetermined voltage VHmax3 is set to the voltage VHmax. However, as shown in FIG. 9, when the flag F is a value 1, in a region where the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1, the predetermined upper limit voltage VHmax may be set to the predetermined voltage VHmax3.

  In the electric vehicle 20 of the embodiment, as shown in FIG. 4, when the flag F is a value 1, in the region where the atmospheric pressure Pout is equal to or higher than the predetermined atmospheric pressure Pout1, the same value as that when the flag F is 0 is set to a high voltage. The allowable upper limit voltage VHmax of the system power line 42 is set, and in a region where the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout1, a lower value than the flag F is 0 is set to the allowable upper limit voltage VHmax of the high voltage system power line 42. It was supposed to be set. However, as shown in FIGS. 10 and 11, when the flag F has a value 1, the flag F has a value 0 in a region where the atmospheric pressure Pout is equal to or higher than the predetermined atmospheric pressure Pout3 between the predetermined atmospheric pressure Pout1 and the predetermined atmospheric pressure Pout2. Is set to the allowable upper limit voltage VHmax of the high voltage system power line 42, and in a region where the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout3, a value lower than that when the flag F is 0 is set to the high voltage system. The allowable upper limit voltage VHmax of the power line 42 may be set. Specifically, as shown in FIG. 10, when the flag F is a value 1, in a region where the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout3 and higher than the predetermined atmospheric pressure Pout2, the lower the atmospheric pressure Pout, the more linear the direction toward the predetermined voltage VHmax3. The allowable upper limit voltage VHmax may be set so as to be low, and the predetermined voltage VHmax3 may be set as the allowable upper limit voltage VHmax in a region where the atmospheric pressure Pout is equal to or lower than the predetermined atmospheric pressure Pout2. Further, as shown in FIG. 11, when the flag F is a value 1, in a region where the atmospheric pressure Pout is less than the predetermined atmospheric pressure Pout3, the predetermined upper limit voltage VHmax may be set to the predetermined voltage VHmax3.

  In the electric vehicle 20 of the embodiment, the allowable upper limit voltage VHmax of the high voltage system power line 42 is set according to whether or not the target drive point of the motor 32 is within the restricted region. However, instead of the target drive point of the motor 32, the allowable upper limit voltage VHmax of the high voltage system power line 42 is set depending on whether or not the drive point (torque Tm and rotation speed Nm) of the motor 32 is within the restricted region. It is good also as what to do. Here, the torque Tm of the motor 32 is estimated based on the d-axis and q-axis currents Id and Iq based on the U-phase and V-phase currents Iu and Iv of the motor 30 from the current sensors 32u and 32v. Also good.

  In the embodiment, the electric vehicle 20 includes the motor 32, the inverter 34, the battery 36, and the boost converter 40. However, in addition to the motor 32, the inverter 34, the battery 36, and the boost converter 40, a configuration of a hybrid vehicle that includes a traveling engine may be employed. Further, in addition to the motor 32, the inverter 34, the battery 36, and the boost converter 40, a configuration of a fuel cell vehicle including a fuel cell connected via a second boost converter may be adopted.

  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, the motor 32 corresponds to “motor”, the inverter 34 corresponds to “inverter”, the battery 36 corresponds to “battery”, the boost converter 40 corresponds to “boost converter”, and the ECU 50 controls “control”. It corresponds to “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, 22a, 22b drive wheel, 23 drive shaft, 24 differential gear, 26 drive shaft, 32 motor, 32a rotational position detection sensor, 32u, 32v current sensor, 34 inverter, 36 battery, 40 boost converter, 42 high voltage System power line, 44 low voltage system power line, 46, 48 capacitor, 46a, 48a voltage sensor, 50 electronic control unit (ECU), 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, 69 Air pressure sensor, D11 to D16, D31, D32 Diode, L reactor, T11 to T16, 31, T32 transistor.

Claims (1)

A motor for traveling,
An inverter for driving the motor;
Battery,
A boost converter connected to a first power line to which the battery is connected and a second power line to which the inverter is connected, and for adjusting a voltage of the second power line;
The allowable upper limit voltage of the second power line is set so that the atmospheric pressure is lower than the first predetermined atmospheric pressure when the atmospheric pressure is less than the first predetermined atmospheric pressure, and the voltage of the second power line is Control means for controlling the boost converter so as to be adjusted within a range of an allowable upper limit voltage or less;
A car equipped with
When the atmospheric pressure is less than the second predetermined atmospheric pressure which is equal to or less than the first predetermined atmospheric pressure and the torque of the motor is equal to or smaller than the predetermined torque, the control means is compared with when the torque of the motor is larger than the predetermined torque. Setting the allowable upper limit voltage to be low,
A car characterized by that.

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