Electric vehicles

Abstract

While the electric vehicle is stopped, the three-phase coils of the three-phase AC motor are protected, while the three-phase AC motor generates more heat. [Solution] The electric vehicle of this disclosure includes a three-phase AC motor having three-phase coils connected at a neutral point and capable of outputting power for driving, a battery, a power control device that adjusts the power from the battery and supplies it to the three-phase AC motor, a heat exchange system capable of transferring heat generated by the three-phase AC motor to the battery, a coil cooling device capable of individually cooling the three-phase coils, and a control device that performs heat generation control while the electric vehicle is stopped, controlling the power control device to cause a DC current to flow through each of the three-phase coils in response to the fulfillment of predetermined conditions, and during the execution of heat generation control, controls the coil cooling device to cool the coil with the largest current flowing through it, and controls the power control device to increase the current with which the largest current flows.

Description

Technical Field

[0004]

[0001] The present disclosure relates to an electric vehicle including a three-phase AC motor having three-phase coils connected at a neutral point and capable of outputting driving power.

Background Art

[0002] Conventionally, a motor control device for controlling an AC motor having m stator coils wound around each of m teeth, one end of each stator coil being connected to an inverter and the other end being connected as a neutral point, is known (see, for example, Patent Document 1). When the temperatures of p stator coils are lower than those of the remaining (m - p) stator coils, this motor control device supplies alternating currents with equal amplitudes to the p stator coils with current phases shifted by 360° / p each, and supplies alternating currents with equal amplitudes to the remaining (m - p) coils with current phases shifted by 360° / (m - p). Thereby, more current can be passed through the stator coils with lower temperatures than through the stator coils with higher temperatures, so that the coil temperatures can be made uniform and the torque of the entire motor can be improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0005] Therefore, the primary objective of this disclosure is to generate more heat in a three-phase AC motor while protecting the three-phase coils of the motor when the electric vehicle is stopped. [Means for solving the problem]

[0006] The electric vehicle of this disclosure includes a three-phase AC motor, a battery, a power control device, a heat exchange system, a coil cooling device, and a control device. The three-phase AC motor has three-phase coils connected at a neutral point and is capable of outputting power for driving. The power control device adjusts the power from the battery and supplies it to the three-phase AC motor. The heat exchange system is capable of transferring the heat generated by the three-phase AC motor to the battery. The coil cooling device is capable of individually cooling the three-phase coils. The control device performs thermal control when the electric vehicle is stopped, controlling the power control device so that a DC current flows through each of the three-phase coils when predetermined conditions are met. Furthermore, while performing thermal control, the control device controls the coil cooling device to cool the coil with the largest current among the three-phase coils, and controls the power control device to increase the current of that largest coil.

[0007] This allows the coil carrying the largest current among the three-phase coils to be cooled by the coil cooling device to prevent burnout, while simultaneously preventing burnout of the remaining coils that do not carry the largest current. At the same time, the current flowing through each coil is increased to promote heat generation in the three-phase AC motor. As a result, while the electric vehicle is stopped, it becomes possible to protect the three-phase coils of the three-phase AC motor while generating more heat in the three-phase AC motor. The heat generated in the three-phase AC motor can then be transferred to the battery via a heat exchange system to warm up the battery.

[0008] Furthermore, the predetermined conditions may be met when the battery temperature is at least below a predetermined temperature. In addition, the battery may be rechargeable by power from an external charging device. The control device may also control the power control device so that the maximum current is an upper limit current that does not burn out coils that are not cooled by the coil cooling device. Furthermore, each of the three-phase coils may be formed hollow, and the coil cooling device may be able to supply refrigerant to each of the three-phase coils individually. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram illustrating the electric vehicle disclosed herein. [Figure 2] This is a schematic diagram showing the stator of a three-phase AC motor of the electric vehicle disclosed herein. [Figure 3] This is a schematic diagram showing the coil cooling system for the electric vehicle of this disclosure. [Figure 4] This diagram illustrates the heat generation control in the electric vehicle described herein. [Figure 5] This flowchart shows the routines executed by the control device of the electric vehicle of this disclosure. [Modes for carrying out the invention]

[0010] Next, with reference to the drawings, embodiments for carrying out the invention of this disclosure will be described.

[0011] Figure 1 is a schematic diagram showing the electric vehicle 1 of this disclosure. The electric vehicle 1 shown in the figure is an electric vehicle (BEV) that includes a motor generator MG that drives a pair of drive wheels DW, a battery (energy storage device) 2, a power control unit (hereinafter referred to as "PCU") 3, and an electronic control unit (hereinafter referred to as "ECU") 20. However, the electric vehicle 1 may also be a plug-in or non-plug-in hybrid vehicle (PHEV, HEV) that includes an internal combustion engine in addition to the battery 2 and motor generator MG.

[0012] The motor generator MG is a three-phase AC motor (synchronous regenerative motor) including a stator S and a rotor R, and exchanges power with the battery 2 via the PCU 3. The stator S of the motor generator MG includes an annular stator core SC and stator coils Cu (U-phase coil), stator coil Cv (V-phase coil), and stator coil Cw (W-phase coil) as shown in Figure 2 (however, only one of the stator coils Cu, Cv, and Cw is shown in Figure 2).

[0013] The stator core SC of the stator S is formed in an annular shape by, for example, stacking multiple electromagnetic steel sheets formed in a substantially annular shape by press working and connecting them in the stacking direction, or by, for example, press-molding and sintering ferromagnetic powder. The stator core SC includes a central hole SO in which the rotor R is arranged, a plurality of teeth ST extending radially from the annular outer circumference (yoke portion) toward the axis and adjacent to each other at a certain interval in the circumferential direction, and a plurality of slots SS (for example, 48 in this embodiment) formed between adjacent teeth ST. Each of the plurality of slots SS extends radially from the stator core SC and is arranged circumferentially at a certain interval, and opens at the central hole SO in which the rotor R is arranged.

[0014] The stator coils Cu, Cv, and Cw are wound around the stator core SC by passing the coil wire through a plurality of corresponding slots SS on the stator core SC, with the wires offset in the circumferential direction. One end (leader wire) of the stator coils Cu, Cv, and Cw is connected to a corresponding power line (not shown), and the other ends of the stator coils Cu, Cv, and Cw are connected by a star connection (Y connection) to form a neutral point NP. In this embodiment, hollow conductors Wu, Wv, and Ww, for example, with an enamel resin insulating coating formed on their surface, are used as the coil wires forming each of the stator coils Cu, Cv, and Cw (see Figure 3).

[0015] Battery 2 is, for example, a lithium-ion secondary battery or nickel-metal hydride secondary battery having a rated output voltage of approximately 200-800V. PCU3 includes an inverter and a boost converter, and is connected to battery 2 via a positive power line, a negative power line, and a system main relay SMR. The inverter of PCU3 includes, for example, six transistors (switching elements) and six diodes connected in parallel in opposite directions to each transistor, and converts DC power from battery 2 to three-phase AC power and supplies it to the motor generator MG, and also converts three-phase AC power from the motor generator MG to DC power and supplies it to battery 2.

[0016] Furthermore, the electric vehicle 1 includes a charging relay DCR and a charging inlet CI. The charging relay DCR is connected to the neutral point NP of the motor generator MG via a power line and is also connected to the negative side power line between the system main relay SMR and the PCU 3 via a power line. The charging inlet CI is located inside a charging lid (not shown) of the electric vehicle 1 and is connected to the charging relay DCR via a power line. As a result, when both the system main relay SMR and the charging relay DCR are closed, the battery 2 is electrically connected to the charging inlet CI via the motor generator MG and the PCU 3.

[0017] When the charging connector 101 of an external charging device 100, such as a DC type, installed on an external charging facility such as a charging station, is plugged into (connected to) the charging inlet CI, the battery 2 can be charged by power from the external charging device 100. However, the charging relay DCR may be connected to the positive and negative power lines between the system main relay SMR and the PCU 3 via a power line, and the electric vehicle 1 may be equipped with an on-board charging device.

[0018] As shown in Figure 1, the rotor R of the motor generator MG is connected to a pair of drive wheels DW via a reduction mechanism 4, a differential gear DF, and a drive shaft DS. The motor generator MG, the reduction mechanism 4, the differential gear DF, and a portion of each drive shaft DS are housed in a transaxle case 5, forming the transaxle of the electric vehicle 1. An oil reservoir 50 for storing lubricating and cooling oil (lubricating and cooling medium) O is defined in the lower part of the transaxle case 5, and the lubricating and cooling oil O, which is scraped up by the gears included in the reduction mechanism 4 and the differential gear DF, is supplied to the gears and bearings inside the transaxle case 5 via oil passages and oil guides (not shown).

[0019] Furthermore, in the electric vehicle 1, a strainer 6, a heat exchanger (cooler) 7, and an electric oil pump 8 are arranged inside the transaxle case 5. The strainer 6 is fixed inside the oil reservoir 50, for example, with a suction port located at the bottom that opens downwards. The suction port of the electric oil pump 8 is connected to the oil outlet of the strainer 6 via the heat exchanger 7. The lubricating and cooling oil O discharged from the outlet of the electric oil pump 8 is supplied to the inside of the rotor R of the motor generator MG via oil passages and oil guides (not shown), and from inside the rotor R it is also supplied to the stator S (coil end) and bearings around the motor generator MG. After passing through the objects to be lubricated and cooled, such as the motor generator MG, the lubricating and cooling oil O flows down into the oil reservoir 50.

[0020] In this embodiment, a part of the stator S of the motor generator MG, that is, a part (lower part) of the stator core SC and a part of the stator coils Cu, Cv, and Cw are immersed (oil-immersed) in the lubricating and cooling oil O stored in the oil storage portion 50 as shown in FIG. 2. The oil immersion rate (the number of slots SS through which the conductors Wu, Wv, or Ww are inserted) indicating the degree of immersion of the stator coils Cu, Cv, and Cw in the lubricating and cooling oil O stored in the oil storage portion 50 is determined according to the mounting state of the stator S (motor generator MG) to the transaxle case 5. And the oil immersion rate of any one of the stator coils Cu, Cv, and Cw (in this embodiment, for example, the stator coil Cu) becomes higher than the other two.

[0021] Further, the electric vehicle 1 includes a heat exchange system 10 capable of transferring the heat generated by the motor generator MG or the like in the transaxle case 5 to the battery 2, and a coil cooling device 15 capable of cooling the three-phase stator coils Cu, Cv, and Cw of the motor generator MG (stator S) individually. The heat exchange system 10 includes a heat exchanger 7 in the transaxle case 5, a heat exchanger 11 provided in the PCU 3 (inside the PCU case), a heat exchanger 12 provided in the battery 2 (inside the battery case), and an electric circulation pump 14 for circulating a heat medium (coolant) among the heat exchangers 7, 11, and 12. By operating the circulation pump 14, the heat medium that has taken heat from the motor generator MG and the PCU 3 in the heat exchangers 7 and 11 can be supplied to the heat exchanger 12, and the heat can be released from the heat medium to the battery 2 in the heat exchanger 12.

[0022] As shown in Fig. 3, the coil cooling device 15 includes an electric oil pump 8 in the transaxle case 5, a plurality (three) of oil jets 16u, 16v, 16w, and a plurality (three) of on-off valves 17u, 17v, 17w. The oil inlets of each of the oil jets 16u, 16v, 16w are connected to the discharge port of the electric oil pump 8 via the corresponding on-off valve 17u, 17v or 17w. Further, the oil injection ports of each of the oil jets 16u, 16v, 16w communicate with the inside (oil passage) of the conductors Wu, Wv or Ww of the stator coils Cu, Cv or Cw via relay pipes. Each of the oil jets 16u, 16v, 16w ejects (supplies) lubricating and cooling oil O from the oil injection port into the corresponding conductor Wu, Wv or Ww when the pressure of the lubricating and cooling oil O discharged from the electric oil pump 8 and supplied to the oil inlet is equal to or higher than a predetermined pressure in a state where the corresponding on-off valve 17u, 17v or 17w is open. Note that the oil jets 16u, 16v, 16w may be omitted from the coil cooling device 15, and each of the above relay pipes may be connected to the discharge port of the electric oil pump 8 via the on-off valve 17u, 17v or 17w.

[0023] The ECU 20 includes a computer having a CPU, ROM, RAM, input / output interfaces, etc., various drive circuits, various logic ICs, etc., and controls (switching control) the inverter and boost converter of the PCU 3. Further, the ECU 20 acquires the accelerator opening Acc indicating the depression amount of the accelerator pedal detected by an accelerator pedal position sensor (not shown), the vehicle speed V detected by a vehicle speed sensor (not shown), the rotational position of the rotor R of the motor generator MG detected by a rotational position sensor (resolver) 21, the phase currents Iu, Iv, Iw flowing through the stator coils Cu, Cv, Cw detected by current sensors 22u, 22v, 22w, etc. Furthermore, the ECU 20 acquires from a battery electronic control unit (hereinafter referred to as "battery ECU") 25 that manages the battery 2, the SOC (charge rate) of the battery 2 calculated by the battery ECU 25, the allowable charge power Win (negative value) and the allowable discharge power Wout (positive value), the temperature (representative temperature) Tb of the battery 2 detected by a temperature sensor (not shown), etc.

[0024] When the electric vehicle 1 is running, the ECU 20 calculates the electrical angle θe and rotational speed Nm of the motor generator MG (rotor R) based on the rotational position of the rotor R. Furthermore, based on the accelerator opening Acc and vehicle speed V, the ECU 20 sets a torque command Tm* to the motor generator MG according to the required torque for the running of the electric vehicle 1, within the range of the battery 2's allowable charging power Win and allowable discharge power Wout, and controls the inverter (multiple transistors) of the PCU 3 by switching based on the torque command Tm*. In addition, when the electric vehicle 1 is braking, the ECU 20 controls the PCU 3 so that the motor generator MG outputs its share of the regenerative braking torque (torque command Tm*) to a pair of drive wheels DW within the range of the battery 2's allowable charging power Win and allowable discharge power Wout.

[0025] When controlling the switching of the inverter (multiple transistors) of PCU3, ECU20 performs a coordinate transformation (3-phase to 2-phase transformation) on the phase currents Iu, Iv, and Iw based on the separately calculated electrical angle θe to calculate the d-axis and q-axis currents Id and Iq. Next, ECU20 sets the d-axis and q-axis current commands Id* and Iq* based on the torque command Tm*, and calculates the d-axis and q-axis voltage commands Vd* and Vq* so that the difference between the current commands Id* and Iq* and the currents Id and Iq is canceled out by current feedback control. Furthermore, ECU20 performs a coordinate transformation (2-phase to 3-phase transformation) on the d-axis and q-axis voltage commands Vd* and Vq* based on the electrical angle θe to three-phase voltage commands Vu*, Vv*, and Vw*. Then, by comparing the voltage commands Vu*, Vv*, Vw* with the carrier wave (triangular wave), PWM signals are generated for multiple transistors in the inverter, and these transistors are switched on and off using the generated PWM signals.

[0026] Furthermore, when charging the battery 2 with power (DC power) from the external charging device 100, the ECU 20 controls the opening and closing of the charging relay DCR, and also causes each phase of the three-phase stator coils Cu, Cv, and Cw of the motor generator MG and the inverter of the PCU 3 to function as a multi-phase boost converter. As a result, by switching control of multiple transistors in the inverter, the power (DC power) supplied to the charging inlet CI is boosted by the multi-phase boost converter, and the battery 2 is charged with the boosted power.

[0027] Furthermore, the ECU 20 controls the electric oil pump 8 in the transaxle case 5 and the circulation pump 14 of the heat exchange system 10, as well as the on / off valves 17u, 17v, and 17w of the coil cooling device 15. In addition, the ECU 20 performs thermal control to warm up the battery 2 as needed while the electric vehicle 1 is stopped, and also controls the electric oil pump 8 in the transaxle case 5 and the circulation pump 14 of the heat exchange system 10. As shown in Figure 4, the thermal control involves flowing a DC current through each stator coil Cu, Cv, and Cw of the motor generator MG, and controlling the inverter of the PCU 3 so that the total current flowing through the three-phase stator coils Cu, Cv, and Cw becomes zero. By performing this thermal control, each stator coil Cu, Cv, and Cw of the motor generator MG generates heat, and the heat from the motor generator MG is transferred to the battery 2 via the lubricating cooling oil O and the heat transfer medium of the heat exchange system 10, thereby warming up the battery 2. Furthermore, a heat generation switch 23 is connected to the ECU 20, and the driver of the electric vehicle 1 can operate the heat generation switch 23 to allow or prohibit the execution of heat generation control. The ECU 20 sets the heat generation flag to "1" when the heat generation switch 23 is ON, and sets the heat generation flag to "0" when the heat generation switch 23 is OFF. Note that the functions of the ECU 20 may be distributed among multiple electronic control devices.

[0028] Next, with reference to Figure 5, the operation related to the heat generation control of the electric vehicle 1 will be explained. Figure 5 is a flowchart showing a routine that is started by the ECU 20 at predetermined time intervals while the electric vehicle 1 is running.

[0029] When the execution timing for the routine in Figure 5 arrives, the ECU 20 acquires the rotational speed Nm of the motor generator MG, the temperature Tb of the battery 2, and the value of the heat generation flag (step S100). Next, the ECU 20 determines whether the electric vehicle 1 is stopped or not based on the rotational speed Nm of the motor generator MG acquired in step S100 (step S110). In step S110, the ECU 20 determines that the electric vehicle 1 is stopped when the rotational speed Nm is zero, and determines that the electric vehicle 1 is not stopped when the rotational speed Nm is not zero. If the rotational speed Nm is not zero and the electric vehicle 1 is not stopped (step S110: NO), the ECU 20 terminates the routine in Figure 5 at that point. Note that the processing in step S110 may also determine whether the electric vehicle 1 is stopped or not based on the vehicle speed V, the detected value of the rotational position sensor 21, or the slope of the U-phase, V-phase, and W-phase carrier waves, etc.

[0030] If the electric vehicle 1 is stopped (step S110: YES), the ECU 20 determines whether the execution conditions for the heat generation control are met based on the temperature Tb of the battery 2 and the value of the heat generation flag obtained in step S100 (step S120). In step S120, the ECU 20 determines that the execution conditions for the heat generation control are met if the temperature Tb of the battery 2 is less than or equal to a predetermined heat generation execution temperature (for example, 0°C) and the heat generation switch 23 is turned on and the heat generation flag is set to "1". Also in step S120, the ECU 20 determines that the execution conditions for the heat generation control are not met if the temperature Tb of the battery 2 is above the heat generation execution temperature or if the heat generation switch 23 is turned off and the heat generation flag is set to "0". If the execution conditions for the heat generation control are not met (step S120: NO), the ECU 20 terminates the routine in Figure 5 at that point.

[0031] If the conditions for executing heat generation control are met (step S120: YES), the ECU 20 controls the PCU 3 (inverter) to flow a predetermined relatively low DC current Iref (Arms) to one of the stator coils Cu, Cv, and Cw, thereby starting heat generation control (step S130). The DC current Iref is a constant value smaller than the upper limit current Ilim (Arms), which is a current that is acquired in advance as a current that does not burn out the stator coil Cu, Cv, Cw (conductors Wu, Wv, Ww). In other words, it is a constant value smaller than the upper limit current Ilim (positive value) that does not burn out the stator coil Cu, Cv, Cw when the stator coil Cu, Cv, Cw is not cooled by the lubricating cooling oil O stored in the oil reservoir 50, the lubricating cooling oil O from the electric oil pump 8, or the lubricating cooling oil O from the coil cooling device 15. When a DC current Iref flows through one of the stator coils Cu, Cv, or Cw, approximately equal currents will flow through the remaining two coils so that the total current of the three phases becomes zero.

[0032] After starting the heat generation control in step S130, the ECU 20 acquires the phase currents Iu, Iv, and Iw detected by the current sensors 22u, 22v, and 22w, and identifies the stator coil Cu, Cv, and Cw through which the current with the largest absolute value flows based on the acquired phase currents Iu, Iv, and Iw (step S140). Note that the process in step S140 may instead identify the stator coil Cu, Cv, and Cw through which the current with the largest absolute value flows based on the amplitude of the carrier waves of the U-phase, V-phase, and W-phase, instead of the phase currents Iu, Iv, and Iw.

[0033] Next, the ECU 20 controls the coil cooling device 15 to cool only the stator coil Cu, Cv, or Cw, which has the largest absolute value current identified in step S140, and also activates the circulation pump 14 of the heat exchange system 10 (step S150). Furthermore, in step S150, the ECU 20 controls the PCU 3 (inverter) to match the absolute value of the current flowing through the stator coil Cu, Cv, or Cw, identified in step S140, to the upper limit current Ilim mentioned above, thereby continuing the heat generation control.

[0034] In other words, in step S150, the ECU 20 opens the on-off valves 17u, 17v, or 17w corresponding to the stator coil Cu, Cv, or Cw through which the current with the largest absolute value is flowing. It also controls the electric oil pump 8 so that the discharge pressure reaches the predetermined pressure, and controls the circulation pump 14 to circulate the heat transfer medium between the heat exchangers 7, 11, and 12. Furthermore, in step S150, the ECU 20 increases the d-axis and q-axis current commands Id*, Iq* according to the difference between the DC current Iref and the upper limit current Ilim, and controls the PCU 3 (inverter) based on these current commands Id*, Iq*. This allows more heat to be generated in the motor generator MG, i.e., the three-phase stator coils Cu, Cv, and Cw. Furthermore, the heat generated by the motor generator MG is recovered by the lubricating coolant O discharged from the electric oil pump 8 and the lubricating coolant O supplied to the corresponding stator coils Cu, Cv, or Cw from the coil cooling device 15, and then transferred from the lubricating coolant O to the coolant in the heat exchange system 10 in the heat exchanger 7. The coolant then passes through the heat exchanger 11 of the PCU 3 and is pumped under pressure to the heat exchanger 12 of the battery 2. As a result, the heat generated by the motor generator MG and PCU 3 is transferred to the battery 2 via the coolant, making it possible to warm up the battery 2 properly.

[0035] After the processing in step S150, the ECU 20 obtains the rotational speed Nm of the motor generator MG, the temperature Tb of the battery 2, and the value of the heat generation flag (step S160), and determines whether or not to stop the heat generation control based on the obtained values ​​of rotational speed Nm, temperature Tb, and heat generation flag (step S170). The ECU 20 determines that the heat generation control should be continued if the rotational speed Nm is zero and the electric vehicle 1 is stopped, the temperature Tb of the battery 2 is slightly higher than the heat generation execution temperature but below the heat generation stop temperature, and the heat generation switch 23 is ON and the heat generation flag is set to "1" (step S170: NO). In this case, the ECU 20 executes the processing in steps S150-S170 again. Note that the processing in step S170 may also determine whether or not the vehicle is stopped based on the vehicle speed V, the detected value of the rotational position sensor 21, or the slope of the U-phase, V-phase, and W-phase carrier waves.

[0036] Furthermore, the ECU 20 determines that the heat generation control should be stopped if the rotational speed Nm is not zero and the electric vehicle 1 is starting, if the temperature Tb of the battery 2 is above the heat generation stop temperature, or if the heat generation switch 23 is off and the heat generation flag is set to "0" (step S170: YES). In these cases, the ECU 20 stops the electric oil pump 8 and the circulation pump 14 and closes the on / off valves 17u, 17v or 17w to stop cooling by the coil cooling device 15 and the circulation of coolant (step S180). In addition, the ECU 20 stops the heat generation control in step S180 and terminates the routine in Figure 5.

[0037] As described above, the electric vehicle 1 includes a motor generator MG, a battery 2, a PCU 3 (inverter), a heat exchange system 10, a coil cooling device 15, and an ECU 20 as a control device. The motor generator MG has three phase stator coils Cu, Cv, and Cw connected at a neutral point NP and is capable of outputting power for driving. The PCU 3 (inverter) adjusts the power from the battery 2 and supplies it to the motor generator MG. The heat exchange system 10 is capable of transferring the heat generated by the motor generator MG to the battery 2. The coil cooling device 15 is capable of individually cooling the three phase stator coils Cu, Cv, and Cw. When the electric vehicle 1 is stopped (step S110: YES), the ECU 20 performs heat generation control, controlling the PCU 3 (inverter) so that a DC current flows through each of the three phase stator coils Cu, Cv, and Cw in accordance with the fulfillment of heat generation execution conditions (predetermined conditions) (step S120: YES, S130). Furthermore, during the execution of heat generation control, the ECU20 controls the coil cooling device 15 to cool the stator coil Cu, Cv, and Cw through which the current with the largest absolute value among the three-phase stator coils Cu, Cv, and Cw flows, and also controls the PCU3 (inverter) to increase the current with the largest absolute value (increase the absolute value) (steps S140-S160, S170: NO).

[0038] This allows the coil cooling device 15 to cool the stator coil Cu, Cv, or Cw carrying the largest absolute current among the three-phase stator coils Cu, Cv, and Cw, thereby preventing burnout of the stator coil Cu, etc., while also preventing burnout of the remaining stator coils Cv, Cw, etc., that do not carry the largest current. At the same time, it is possible to increase the current (absolute value) flowing through each stator coil Cu, Cv, and Cw, thereby promoting heat generation in the motor generator MG. As a result, while the electric vehicle 1 is stopped, it becomes possible to generate more heat in the motor generator MG while protecting the three-phase stator coils Cu, Cv, and Cw of the motor generator MG. Then, in the electric vehicle 1, the heat generated in the motor generator MG can be transferred to the battery 2 via the heat exchange system 10 to warm up the battery 2.

[0039] Furthermore, in the electric vehicle 1, the heat generation execution condition is met when the temperature Tb of the battery 2 is at least below a predetermined heat generation execution temperature (specified temperature) (step S120). This makes it possible to warm up the battery 2 using the time the electric vehicle 1 is stopped, thereby protecting the battery 2 and suppressing the prolonged charging time of the battery 2.

[0040] Furthermore, the battery 2 can be charged using power from the external charging device 100 of the external charging facility. This allows the battery 2 to be heated up before charging by the external charging device 100 begins, using the time the electric vehicle 1 is stopped before arriving at the external charging facility, thereby suppressing the prolonged charging time at the external charging facility.

[0041] Furthermore, the ECU20 controls the PCU3 (inverter) so that the absolute value of the maximum current is the upper limit current Ilim, which prevents burnout of the stator coils Cv, Cw, etc., that are not cooled by the coil cooling device 15 (step S150). This makes it possible to increase the maximum current (increase the absolute value) while more reliably preventing burnout of all three-phase stator coils Cu, Cv, and Cw.

[0042] Furthermore, in the electric vehicle 1, each of the conductors Wu, Wv, and Ww forming the three-phase stator coils Cu, Cv, and Cw is formed hollow, and the coil cooling device 15 can supply refrigerant individually to the interior of each of the three-phase stator coils Cu, Cv, and Cw. This makes it possible to cool the three-phase stator coils Cu, Cv, and Cw individually. However, the coil cooling device 15 may also be capable of supplying refrigerant to each of the three-phase stator coils Cu, Cv, and Cw in the slots SS of the stator core SC corresponding to each of the three-phase stator coils Cu, Cv, and Cw.

[0043] Furthermore, the invention disclosed herein is not limited in any way to the embodiments described above, and it goes without saying that various modifications can be made within the scope of this disclosure. Moreover, the embodiments described above are merely one specific form of the invention described in the summary of the invention, and do not limit the elements of the invention described in the summary of the invention. [Industrial applicability]

[0044] The invention disclosed herein can be used in industries such as the electric vehicle manufacturing industry. [Explanation of symbols]

[0045] 1 Electric vehicle, 2 Battery, 3 Power control unit (PCU), 4 Reduction mechanism, 5 Transaxle case, 50 Oil reservoir, 6 Strainer, 7, 11, 12 Heat exchanger, 8 Electric oil pump, 10 Heat exchange system, 14 Circulation pump, 15 Coil cooling device, 16u, 16v, 16w Oil jet, 17u, 17v, 17w On / off valve, 20 Electronic control unit (ECU), 21 Rotational position sensor, 22u, 22v, 22w Current sensor, 23 Heat generation switch, 25 Battery electronic control unit (Battery ECU), 100 External charging device, Cu, Cv, Cw Stator coil, MG Motor generator, NP Neutral point, O Lubricating coolant, R Rotor, S Stator, SC Stator core, SS Slot.

Claims

1. An electric vehicle comprising a three-phase AC motor having three-phase coils connected at a neutral point and capable of outputting power for driving, a battery, and a power control device that adjusts the power from the battery and supplies it to the three-phase AC motor, A heat exchange system capable of transferring heat generated by the three-phase AC motor to the battery, A coil cooling device capable of individually cooling the three-phase coils, A control device that, while the electric vehicle is stopped, performs heat generation control by controlling the power control device so that a direct current flows through each of the three-phase coils in accordance with the fulfillment of predetermined conditions, and controls the coil cooling device to cool the coil with the largest current among the three-phase coils while the heat generation control is being performed, and controls the power control device so that the largest current increases, An electric vehicle equipped with [a specific feature / equipment].

2. In the electric vehicle according to claim 1, The aforementioned predetermined condition is met when the temperature of the battery is at least below a predetermined temperature in an electric vehicle.

3. In the electric vehicle according to claim 1 or 2, The aforementioned battery is an electric vehicle that can be charged by power from an external charging facility.

4. In the electric vehicle according to claim 1 or 2, The control device is an electric vehicle that controls the power control device so that the maximum current is the upper limit current that does not burn out the coil that is not cooled by the coil cooling device.

5. In the electric vehicle according to claim 1 or 2, Each of the three-phase coils is formed hollow, and the coil cooling device is capable of supplying a refrigerant to each of the three-phase coils individually in an electric vehicle.

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