Electric drive device and method for controlling an electric drive device

Abstract

An electric drive device that, in a vehicle having a motor with a rotor and a stator and a coolant passage through which coolant flows to cool the motor, drives the motor by a battery and charges the battery using the motor. The electric drive device includes a flow volume adjusting unit that adjusts a flow volume of coolant to be supplied to the rotor and the stator. In a case where the battery is charged by applying electricity to a coil of the stator while the vehicle is stopped, the flow volume adjusting unit switches the flow volume of coolant to be supplied to the rotor and the stator such that the flow volume of coolant supplied to the stator increases compared to a case where the battery is charged without applying electricity to the coil of the stator.

Description

[Technical field]

[0001] The present invention relates to an electric drive device and a method for controlling the electric drive device. [State of the art]

[0002] To shorten the battery charging time of stopped vehicles, the battery charging voltage must be high. In a case where two types of voltages, such as 400V and 800V, coexist as the charger voltage and the battery voltage, charging a battery with 800V specifications by chargers with 400V specifications requires a boost from 400V to 800V. Accordingly, the charging time can be shortened by using a rapid charging system that uses a boost chopper circuit using a three-phase line of a traction motor equipped in the vehicle. However, in a case where the rapid charging system is used, the amount of heat generated by the engine increases, and thus, there is a need to increase the flow volume of the coolant supplied to the engine.

[0003] For example, in a case where the flow volume of the coolant supplied to the engine is increased, control is performed to increase the liquid level of the coolant in the engine, and with respect to this liquid level increase, for example, PTL 1 below discloses a configuration of a control device of a vehicle that increases an oil level in the engine when deceleration travel is performed, regardless of a charge state of a rechargeable battery. [Citation list][Patent literature]

[0004] [PTL 1] Japanese Patent Application Publication No. 2018-152946 [Summary of the invention][Technical problem]

[0005] In view of the technology disclosed in PTL 1, during rapid charging of a battery in a stopped vehicle, there is a need to increase the liquid level of the cooling oil in the engine to prevent the temperature of a stator coil from rising due to charging using the engine, thus preventing burnout of the stator coil. In view of this, an object of the present invention is to provide an electric drive device and a method for controlling the electric drive device that improve the cooling capabilities of a stator coil during rapid charging of the battery. [Solution to the problem]

[0006] An electric drive device and a method for controlling the electric drive device, which, in a vehicle having a motor with a rotor and a stator and a coolant passage through which coolant flows to cool the motor, drives the motor by a battery and charges the battery using the motor, wherein the electric drive device includes a flow volume adjusting unit that adjusts a flow volume of the coolant to be supplied to the rotor and the stator, wherein, in a case where the battery is charged by applying electricity to a coil of the stator while the vehicle is stopped, the flow volume adjusting unit switches the flow volume of the coolant to be supplied to the rotor and the stator such that the flow volume of the coolant supplied to the stator is reduced compared to a casein which the battery is charged without applying electricity to the stator coil. [Advantageous effects of the invention]

[0007] According to the present invention, an electric drive device and a method for controlling the electric drive device can be provided which improve the reliability of a motor during rapid charging of a battery. [Brief description of the drawings] [ Fig. 1] Fig. 1 is an explanatory diagram of an electric drive device according to an embodiment of the present invention. [ Fig. 2] Fig. 2 is a control sequence of the electric drive device in Fig. 1. [ Fig. 3] Fig. 3 is a modification of Fig. 1. [ Fig. 4] Fig. 4 is a diagram for describing a cooling oil level within an engine controlled according to the embodiment of the present invention. [ Fig. 5] Fig. 5 is a control sequence of the electric drive device in Fig. 4. [Description of embodiments]

[0008] An embodiment of the present invention will be described below with reference to the drawings. The following description and drawings are examples for describing the present embodiment, without any omissions or simplifications being made appropriately for the sake of clarity. The present invention may be embodied in various other forms. The components may be singular or plural unless specifically limited.

[0009] The positions, sizes, shapes, areas, etc. of the components illustrated in the drawings may not indicate actual positions, sizes, shapes, areas, etc., in order to facilitate understanding of the invention. Accordingly, the present invention is not necessarily limited to the positions, sizes, shapes, areas, etc., disclosed in the drawings. (Embodiment and overall configuration)(Fig. 1)

[0010] An electric drive device 100 used in the present invention is installed in a vehicle such as an electric vehicle or the like, and a motor 2 is driven by a battery. In a case of charging this battery, charging is performed using the motor 2 to shorten the charging time while the vehicle is stopped. Specifically, the electric drive device 100 receives electric power from charging devices such as, for example, a commercial AC power source or the like and charges a high-voltage battery installed in the vehicle, thereby obtaining electric drive power for the vehicle while the vehicle is stopped.At this time, the electric drive device 100 boosts the voltage through a boost chopper circuit that uses a three-phase line from the motor 2 to charge the battery, which has a higher voltage than the voltage of the charging devices. This enables rapid charging of the battery of the vehicle while stopped. The boost chopper circuit includes, for example, choke coils, switching circuits, and diodes.

[0011] The electric drive device 100 also controls the flow of coolant to the electrical devices with which the vehicle is equipped. The motor 2, which includes an inverter 1, a rotor 2c, and a stator 2d, is cooled by a coolant passage through which cooling water 3a flows and a coolant passage through which cooling oil 3b flows. The cooling water 3a circulates through the inverter 1 and the motor 2, cooling them.

[0012] Cooling of the inverter 1 and the motor 2 by the cooling water 3a will be described. An EWP 7 (Electric Water Pump) cools the inverter 1 by supplying the cooling water 3a to the inverter 1. Next, the cooling water 3a is supplied from the inverter 1 to the motor 2, and at the motor 2, it cools the entire motor 2 by flowing, for example, through a jacket 2a provided on an inner peripheral side of the motor 2.

[0013] The cooling water 3a that has cooled the engine 2 is supplied to a heat exchanger 4 and indirectly cools the cooling oil 3b via the heat exchanger 4 in the same way. The cooling water 3a is supplied from the heat exchanger 4 to a radiator 6 and is cooled by the radiator 6 to a temperature at which the devices can be adequately cooled, starting from a state of maintaining heat absorbed by the engine 2 and heat absorbed by the cooling oil 3b. The cooling water 3a is supplied from the radiator 6 to the EWP 7. This completes a circulation cycle of the cooling water 3a in the vehicle.

[0014] Next, the cooling of the cooling oil 3b to the engine 2 will be described. In a case where fast charging is performed when the vehicle is stopped, a boost circuit using three-phase conduction of the engine is used, but the cooling of the stator 2d, which has the stator coil 2b that generates a large amount of heat at this time, needs to be intensified. Accordingly, the amount of coolant supplied to the rotor 2c is reduced, and the amount of coolant supplied to the stator 2d is increased by a corresponding amount as an increase in the amount of coolant supplied to the stator 2d, thereby intensifying the cooling of the stator 2d.

[0015] A specific coolant flow of the cooling oil 3b will be described. An EOP 5 (Electric Oil Pump: electric oil pump) supplies the cooling oil 3b to a flow volume adjustment unit 8 via the heat exchanger 4. In a case where it is determined that the vehicle has stopped and rapid battery charging has started, based on an instruction from an upper-level control device or the like, for example, which is omitted from the illustration, the flow volume adjustment unit 8 adjusts and switches the flow volume of the coolant to be supplied to the rotor 2c and the stator 2d in the motor 2. Specifically, the flow volume adjustment unit 8 switches the supply amount such that the supply amount of the cooling oil 3b to be supplied to the rotor 2c via a shaft 9 is decreased and the supply amount of the cooling oil 3b to the stator 2d having the stator coil 2b is increased.

[0016] Accordingly, the flow volume of the coolant supplied to the stator 2d, which includes a stator core and the stator coil 2b, increases compared to a case where the battery is charged without applying electricity to the stator coil 2b. Thus, cooling of the stator, whose heat generation amount increases during rapid charging, can be performed along with increasing the voltage associated with charging the vehicle's battery while the vehicle is stopped. In addition, the stator coil 2b can be directly cooled with the cooling oil 3b. Furthermore, burnout of the stator coil 2b during rapid battery charging can be prevented.

[0017] Note that the determination regarding switching the flow volume of the cooling oil 3b to the rotor 2c and the stator 2d is made at the flow volume setting unit 8 based on a temperature sensor or the like (not shown) that detects the temperature of the stator 2d of the motor 2, and can be realized, for example, by increasing the flow volume of the cooling oil 3b to be supplied to the stator 2d and further decreasing the flow volume of the cooling oil 3b supplied to the rotor 2c in a case where the temperature is higher than a predetermined threshold or is judged to have exceeded the threshold by a reference predicting the exceedance of the predetermined threshold.

[0018] The cooling oil 3b that has cooled the rotor 2c and the stator 2d returns to the EOP 5. By passing through the heat exchanger 4 in a case where the cooling oil 3b is supplied from the EOP 5 back to the engine 2, the heat of the cooling oil 3b is indirectly dissipated to the cooling water 3a passed through the heat exchanger 4 in the same way, whereby the temperature of the cooling oil 3b can be returned to a temperature capable of adequately cooling the engine 2.

[0019] It should be noted that the description is made on the assumption that, of a first passage through which the cooling water 3a flows and a second passage through which the cooling oil 3b flows, the first passage through which the cooling water 3a flows is allowed to flow first to cool the engine 2 and cool the cooling oil 3b at the heat exchanger 4 at the same time, but this is not limitative, and either passage may be allowed to flow first. (Fig. 2)

[0020] A control flow of the refrigerant flow volume of the electric drive device 100 according to the present invention will be described. In step S1, a determination is made as to whether or not vehicle rapid charging has started. If it is determined that vehicle rapid charging has started, the flow proceeds to step S2. If rapid charging is not started, the flow ends.

[0021] In step S2, it is determined whether cooling of the stator coil 2b is necessary in conjunction with starting fast charging. If it is determined that cooling of the stator coil 2b is necessary during fast charging, the flow proceeds to step S3. If it is unnecessary, the flow ends.

[0022] In step S3, the cooling amount of the stator 2d having the stator coil 2b is increased to directly cool the stator coil 2b by the cooling oil 3b, and the current ends.

[0023] Thus, not only the cooling amount of the stator 2d is increased during fast charging, but the cooling amount of the rotor 2c is reduced, thereby suppressing unnecessary driving of the oil and water pump, and the electric power consumption of the battery can be suppressed. (Modification)(Fig. 3)

[0024] The present invention can also be applied to a case of cooling the motor 2 by the cooling oil 3b alone, without using the cooling water 3a. In this case, the cooling water 3a cools the inverter 1 via the radiator 6 and the EWP 7, but does not flow through the motor 2 and circulates through other electrical devices not shown, cooling them. Meanwhile, the flow of the cooling oil 3b that cools the motor 2 is the same as in Fig. 1. Also in this arrangement, the cooling oil 3b is indirectly cooled by the cooling water 3a via the heat exchanger 4 and can thus be lowered to a temperature at which the motor 2 can be adequately cooled, and sufficient cooling can be performed even without the cooling water 3a flowing through the motor 2, and accordingly, burnout of the stator coil 2b during rapid charging can be prevented.

[0025] It should be noted that when the engine 2 is cooled by oil cooling by the cooling oil 3b alone, the circulation of the cooling oil 3b may be started after the circulation of the cooling water 3a to the heat exchanger 4 is started, or the circulation of the cooling water 3a may be started after the circulation of the cooling oil 3b is started, or both may be started at the same time. (Fig. 4)

[0026] Fig. Figure 4(a) is a cross-sectional view of the engine 2 in the radial direction, illustrating the manner in which the liquid level rises within the engine, and Fig. 4(b) is a cross-sectional view of Fig. 4(a) in the axial direction. In the engine 2, the vehicle is stopped for rapid charging, and the rotation of the rotor 2c is also stopped. When the rotor 2c is rotated in a state where the cooling oil 3b is present in the engine 2, there is a risk that the cooling oil 3b will intrude into a gap between the stator 2d and the rotor 2c. Accordingly, in order to prevent the cooling oil 3b from intruding into the gap portion, the vehicle has a structure in which the transmission of the driving force is interrupted, so that the driving power for traveling is not transmitted to a traction shaft (drive shaft). Accordingly, the increase of the liquid level of the cooling oil 3b in the engine 2 can be surely realized, and also the cooling oil 3b can be circulated to the engine 2 by the rotation of the rotor 2c after the quick charging, whereby the heat transfer between the cooling oil 3b, the rotor 2c and the stator 2d can be promoted.

[0027] In a case where further cooling of the stator 2d is necessary, the flow volume adjustment unit 8 ( Fig. 1) performs oil cooling of the stator 2d and further raises the cooling oil 3b, which comes into direct contact with the stator coil 2b, from a liquid level 3c to a liquid level 3d. Accordingly, the cooling efficiency of the stator 2d is increased.

[0028] Regarding the stator coil 2b, which becomes hot during rapid charging, the temperature of the stator coil 2b is detected, for example, by a sensor or the like, which is omitted from the illustration. In a case where the temperature change per unit time is higher than a predetermined reference at this detected temperature, it is determined that adequate cooling is insufficient, and it is determined to raise the liquid level of the cooling oil 3b within the engine 2. Thus, the liquid level within the engine 2 is raised, whereby the cooling of the engine 2 during rapid charging can be improved. (Fig. 5)

[0029] A control sequence of the electric drive device 100 according to the present invention in Fig.4 will be described. In step S11, the electric drive device 100 determines whether or not rapid charging of the vehicle has started. If it is determined that rapid charging has started, the flow proceeds to step S12. If rapid charging is not started, the flow ends.

[0030] In step S12, it is determined whether cooling of the stator coil 2b is necessary during rapid charging. If it is determined that cooling is necessary, the flow proceeds to step S13. In step S13, the flow volume of the cooling oil 3b supplied to the stator 2d is increased to directly cool the stator coil 2b with the cooling oil 3b.

[0031] In step S14, a determination is made as to whether raising the liquid level of the cooling oil 3b within the engine 2 is necessary. If raising the liquid level within the engine 2 is unnecessary, the flow ends. In a case where it is determined that raising the liquid level within the engine 2 is necessary, the liquid level of the cooling oil 3b within the engine 2 is further increased in step S15, and the flow ends.

[0032] While the cooling of the motor 2 and the inverter 1 by water cooling and oil cooling has been described above in the present invention, the cooling of the inverter 1 and the motor 2 can be realized by water cooling alone.

[0033] According to the above-described embodiment of the present invention, the following operations and advantages can be achieved. (1) An electric drive device that, in a vehicle having a motor 2 with a rotor 2c and a stator and a coolant passage through which coolant flows to cool the motor 2, drives the motor 2 by a battery and charges the battery using the motor 2, the electric drive device including a flow volume adjustment unit 8 that adjusts a flow volume of the coolant to be supplied to the rotor 2c and the stator. In a case where the battery is charged by applying electricity to a coil 2b of the stator while the vehicle is stopped, the flow volume adjustment unit 8 switches the flow volume of the coolant to be supplied to the rotor 2c and the stator such that the flow volume of the coolant supplied to the stator increases compared to a case where the battery is charged without applying electricity to the coil 2b of the stator.Thus, the electric drive device 100 can be provided which improves the reliability of the motor 2 at the time of rapid charging of the battery. (2) A temperature sensor that detects a temperature of the stator is further included. When the temperature of the stator detected by the temperature sensor exceeds a predetermined threshold, the flow volume adjustment unit 8 increases the flow volume of the coolant to be supplied to the stator. Thus, burnout of the stator coil 2b during rapid battery charging can be prevented. (3) A temperature sensor that detects a temperature of the stator is further included. When the temperature of the stator detected by the temperature sensor exceeds a predetermined threshold, the flow volume adjustment unit 8 reduces the flow volume of the coolant to be supplied to the rotor 2c. Thus, burnout of the stator coil 2b during rapid battery charging can be prevented. (4) The flow volume adjustment unit 8 switches the flow volume of the coolant to be supplied to the rotor 2c and the stator so that a filling level of the coolant in the motor 2 is higher. Thus, further cooling of the stator coil 2b can be handled. (5) The coolant includes cooling water 3a and cooling oil 3b, and the cooling water 3a is forced to flow through a coolant passage formed on a peripheral side further outward than the stator. Thus, it is possible to prevent, for example, burnout of the stator coil 2b in a case of cooling the motor 2 by water cooling alone. (6) The coolant includes cooling water 3a and cooling oil 3b, and the electric drive device includes a first passage through which the cooling water 3a flows to cool the motor 2 and an electric device other than the motor 2, and a second passage through which the cooling oil 3b flows to cool the motor 2. At this time, one of the cooling water 3a to flow through the first passage and the cooling oil 3b to flow through the second passage is caused to flow first. Thus, regardless of which passage is given priority, cooling of the motor 2 contributes to the cooling of the motor 2 during rapid charging. (7) The coolant includes cooling water 3a and cooling oil 3b, and the electric drive device includes a first passage through which the cooling water 3a flows to cool the motor 2 and an electric device other than the motor 2, and a second passage through which the cooling oil 3b flows to cool the motor 2. The cooling water 3a to flow through the first passage is caused to flow first before the cooling oil 3b to flow through the second passage. Thus, even if the second passage is given priority over the first passage, the cooling of the motor 2 can be contributed during rapid charging. (8) A method for controlling an electric drive device that uses a battery to charge and drive the motor 2 in a vehicle that cools a motor 2 having a rotor 2c and a stator by coolant, the method including, in a case where the battery is charged by applying electricity to a coil of the stator while the vehicle is stopped, switching a flow volume of the coolant to be supplied to the rotor 2c and the stator such that the flow volume of the coolant supplied to the stator increases compared to a case where the battery is charged without applying electricity to the stator coil 2b. Using such a control method enables improved reliability of the motor 2 to be realized at the time of rapid charging of the battery.

[0034] It should be noted that the present invention is not limited to the above embodiment, and various other modifications and other configurations can be combined without departing from the spirit thereof. Furthermore, the present invention is not limited to arrangements including all the configurations described in the above embodiment, and also includes arrangements in which some of the configurations are omitted. [List of reference symbols] 1 inverter 2 engines 2a Coat 2b Stator coil 2c rotor 2d stator 3 Coolant 3a Cooling water 3b Cooling oil 3c Liquid level 3d liquid level after the rise 4 heat exchangers 5 EOP 6 coolers 7 EWP 8 Flow volume adjustment unit 9 Wave 100 Electric drive device QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2018-152946

[0004]

Claims

[1] An electric drive device which, in a vehicle having a motor with a rotor and a stator and a coolant passage through which coolant flows to cool the motor, drives the motor by a battery and charges the battery using the motor, the electric drive device comprising: a flow volume adjusting unit that adjusts a flow volume of the coolant to be supplied to the rotor and the stator, wherein in a case where the battery is charged by applying electricity to a coil of the stator while the vehicle is stopped, the flow volume adjusting unit switches the flow volume of the coolant to be supplied to the rotor and the stator such that the flow volume of the coolant supplied to the stator increases compared to a case where the battery is charged without applying electricity to the coil of the stator. [2] Electric drive device according to claim 1, further comprising: a temperature sensor that detects a temperature of the stator, wherein in a case where the temperature of the stator detected by the temperature sensor is greater than a predetermined threshold, the flow volume adjusting unit increases the flow volume of the coolant to be supplied to the stator. [3] Electric drive device according to claim 1, further comprising: a temperature sensor that detects a temperature of the stator, wherein in a case where the temperature of the stator detected by the temperature sensor is greater than a predetermined threshold, the flow volume adjusting unit reduces the flow volume of the coolant to be supplied to the rotor. [4] The electric drive device according to claim 1, wherein the flow volume adjusting unit switches the flow volume of the coolant to be supplied to the rotor and the stator such that a filling level of the coolant in the motor is higher. [5] Electric drive device according to claim 1, wherein the coolant contains cooling water and cooling oil, and the cooling water is caused to flow through a coolant channel which is formed on a circumferential side further out than the stator. [6] The electric drive device according to claim 1, wherein the coolant includes cooling water and cooling oil, the electric drive device further comprising a first passage through which the cooling water for cooling the motor and an electric device other than the motor flows, and a second passage through which the cooling oil for cooling the motor flows, wherein one of the cooling water to flow through the first passage and the cooling oil to flow through the second passage is first caused to flow. [7] Electric drive device according to claim 1, wherein the coolant contains cooling water and cooling oil, wherein the electric drive device further comprises a first channel through which the cooling water for cooling the motor and an electric device other than the motor flows, and a second channel through which the cooling oil for cooling the motor flows, wherein the cooling water to be flowed through the first channel is first caused to flow before the cooling oil is to flow through the second channel. [8] A method of controlling an electric drive device which, in a vehicle which cools a motor having a rotor and a stator by coolant, uses a battery to charge and drive the motor, the method comprising: in a case where the battery is charged by applying electricity to a coil of the stator while the vehicle is stopped, switching a flow volume of the coolant to be supplied to the rotor and the stator such that the flow volume of the coolant supplied to the stator increases compared to a case where the battery is charged without applying electricity to the coil of the stator.

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