Electric drive device, method for controlling an electric drive device

Abstract

An electric drive device which drives a motor by a battery and charges the battery using the motor in a vehicle provided with a motor having a rotor and a stator, and a refrigerant flow path through which a refrigerant for cooling the motor flows, wherein: a flow rate adjustment unit is provided that adjusts the flow rate of the refrigerant to be supplied to the rotor and the stator; and the flow rate adjustment unit switches the flow rate of the refrigerant to be supplied to the rotor and the stator so that the flow rate of the refrigerant supplied to the stator is higher when charging the battery by energizing the coil of the stator while the vehicle is stopped than when charging the battery without energizing the coil of the stator.

Description

Technical Field

[0001] The present invention relates to an electric drive device and a control method for the electric drive device.

Background Art

[0002] In order to shorten the charging time of a battery while the vehicle is stopped, it is necessary to increase the charging voltage of the battery. For example, when two types of voltages, 400V and 800V, coexist for charging facility voltage and battery voltage respectively, to charge an 800V-specification battery with a 400V-specification charging facility, it is necessary to boost the voltage from 400V to 800V. Accordingly, by using a quick charging system with a boost chopper circuit that uses the three-phase lines of the travel motor mounted on the vehicle, the charging time can be shortened. However, when using the quick charging system, the heat generation amount of the motor increases, so it is necessary to increase the flow rate of the coolant supplied to the motor.

[0003] When increasing the flow rate of the coolant supplied to the motor, for example, control is performed to raise the liquid level height of the coolant inside the motor. Regarding this rise in liquid level, for example, the following Patent Document 1 discloses a configuration of a vehicle control device that raises the oil level height inside the motor during decelerating travel, regardless of the state of charge of the rechargeable battery.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the technology described in Patent Document 1, during rapid charging of a battery while the vehicle is stopped, it is necessary to raise the liquid level of the cooling oil in the motor to prevent the temperature of the stator coil from rising due to charging using the motor, thereby preventing burnout of the stator coil. In view of this, the object of the present invention is to provide an electric drive device and a control method for an electric drive device that improve the cooling performance of the stator coil during rapid charging of a battery. [Means for solving the problem]

[0006] An electric drive device and a control method for an electric drive device, comprising a motor having a rotor and a stator, and a refrigerant passage through which a refrigerant for cooling the motor flows, wherein the motor is driven by a battery and the battery is charged using the motor, the device having a flow rate adjustment unit for adjusting the flow rate of the refrigerant supplied to the rotor and the stator, the flow rate adjustment unit switches the flow rate of the refrigerant supplied to the rotor and the stator so that when the battery is charged by energizing the coils of the stator while the vehicle is stopped, the flow rate of the refrigerant supplied to the stator is increased compared to when the battery is charged without energizing the coils of the stator. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an electric drive device and a control method for the electric drive device that improve the reliability of the motor during rapid charging of a battery. [Brief explanation of the drawing]

[0008] [Figure 1] An explanatory diagram of an electric drive device according to one embodiment of the present invention. [Figure 2] Control flow of the electric drive system in Figure 1 [Figure 3] Modified version of Figure 1 [Figure 4] A diagram illustrating the oil-cooled surface inside a motor under control, according to one embodiment of the present invention. [Figure 5] Control flow of the electric drive system in Figure 4 [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. The following description and drawings are illustrative for illustrating the present invention, and have been omitted and simplified as appropriate for clarity of explanation. The present invention can also be carried out in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] The positions, sizes, shapes, and ranges of the components shown in the drawings may not represent their actual positions, sizes, shapes, and ranges in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, and ranges disclosed in the drawings.

[0011] (One embodiment and overall configuration) (Figure 1) The electric drive unit 100 used in the present invention is installed in a vehicle such as an electric vehicle and drives a motor 2 with a battery. When charging this battery, the motor 2 is used to charge it while the vehicle is stopped in order to shorten the charging time. Specifically, while the vehicle is stopped, the electric drive unit 100 receives power from a charging facility such as a commercial AC power supply and charges a high-voltage battery mounted on the vehicle to obtain power to drive the vehicle. In this case, the electric drive unit 100 charges the battery at a voltage higher than the voltage of the charging facility by boosting the voltage using a boost chopper circuit that uses the three-phase wires of the motor 2. This enables rapid charging of the battery while the vehicle is stopped. The boost chopper circuit is composed of, for example, a choke coil, a switching circuit, and a diode.

[0012] Furthermore, the electric drive unit 100 controls the flow of refrigerant to each electrical device in the vehicle. The motor 2, which has an inverter 1, a rotor 2c and a stator 2d, is cooled by a refrigerant passage through which cooling water 3a flows and a refrigerant passage through which cooling oil 3b flows. The cooling water 3a circulates between the inverter 1 and the motor 2 to cool them.

[0013] The cooling of the inverter 1 and motor 2 by the cooling water 3a will now be explained. The EWP7 (Electric Water Pump) cools the inverter 1 by supplying the cooling water 3a to the inverter 1. Subsequently, the cooling water 3a is supplied from the inverter 1 to the motor 2, and in the motor 2, it cools the entire motor 2 by flowing, for example, through the jacket 2a provided on the outer circumference of the motor 2.

[0014] The coolant 3a that has cooled the motor 2 is supplied to the heat exchanger 4, and similarly indirectly cools the coolant oil 3b passing through the heat exchanger 4. The coolant 3a is sent from the heat exchanger 4 to the radiator 6, where it is cooled from a state containing heat absorbed from the motor 2 and the coolant oil 3b to a temperature at which it can properly cool each component. The coolant 3a is sent from the radiator 6 to the EWP 7. This completes the circulation cycle of the coolant 3a in the vehicle.

[0015] Next, we will explain the cooling of the motor 2 with the coolant oil 3b. When rapid charging is performed while the vehicle is stopped, a boost circuit using the motor's three-phase wires is used, and in this case, it is necessary to strengthen the cooling of the stator 2d, which has the stator coil 2b that generates a lot of heat. Therefore, the amount of coolant supplied to the rotor 2c is reduced, and the amount of coolant supplied to the stator 2d is increased by using that reduction as an increase in the amount of coolant supplied to the stator 2d, thereby strengthening the cooling of the stator 2d.

[0016] The specific flow of the coolant 3b will now be explained. The EOP5 (Electric Oil Pump) supplies the coolant 3b to the flow rate adjustment unit 8 via the heat exchanger 4. When the flow rate adjustment unit 8 determines, for example, from instructions from a higher-level control device (not shown) that the vehicle has stopped and rapid battery charging has begun, it adjusts and switches the flow rate of the coolant supplied to the rotor 2c and stator 2d by the motor 2. Specifically, the flow rate adjustment unit 8 switches the supply amount so as to decrease the amount of coolant 3b supplied to the rotor 2c via the shaft 9 and increase the amount of coolant 3b supplied to the stator 2d, which has the stator coil 2b.

[0017] As a result, the flow rate of the coolant supplied to the stator including the stator core and the stator coil 2b is increased compared to the case where the battery is charged without energizing the stator coil 2b, so that while the vehicle is stopped, in parallel with the voltage boost associated with charging the vehicle battery, the cooling of the stator, which generates a large amount of heat during rapid charging, can be improved. In addition, the stator coil 2b can be directly cooled by the cooling oil 3b. Further, the occurrence of burning of the stator coil 2b can be prevented while the battery is being rapidly charged.

[0018] Note that the switching of the flow rate of the cooling oil 3b to the rotor 2c and the stator 2d in the flow rate adjustment unit 8 is determined by, for example, a temperature sensor (not shown) that detects the temperature of the stator 2d of the motor 2, and when the temperature is higher than a predetermined threshold, or when it is determined that the temperature will exceed the predetermined threshold based on a reference for predicting exceeding the predetermined threshold, this can be realized by increasing the flow rate of the cooling oil 3b supplied to the stator 2d and decreasing the flow rate of the cooling oil 3b supplied to the rotor 2c.

[0019] The cooling oil 3b that has cooled the rotor 2c and the stator 2d returns to the EOP 5. When the cooling oil 3b is supplied from the EOP 5 to the motor 2 again, the heat of the cooling oil 3b is indirectly dissipated to the cooling water 3a that also passes through the heat exchanger 4 by way of the heat exchanger 4, so that the temperature of the cooling oil 3b that can appropriately cool the motor 2 can be restored.

[0020] Note that the description has been made on the premise that, of the first flow path through which the cooling water 3a flows and the second flow path through which the cooling oil 3b flows, the first flow path through which the cooling water 3a flows is passed first for the purpose of cooling the cooling oil 3b in the heat exchanger 4 simultaneously with cooling the motor 2, but the present invention is not limited to this, and either flow path may be passed first.

[0021] (Figure 2) The control flow of the refrigerant flow rate of the electric drive unit 100 of the present invention will now be described. In step S1, it is determined whether the vehicle has started rapid charging. If it is determined that rapid charging has started, the process proceeds to step S2. If rapid charging has not started, the process ends.

[0022] In step S2, it is determined whether cooling of the stator coil 2b is necessary when rapid charging begins. If it is determined that cooling of the stator coil 2b is necessary during rapid charging, the process proceeds to step S3. If it is not necessary, the process ends.

[0023] In step S3, the stator coil 2b is directly cooled by the cooling oil 3b, so the amount of cooling for the stator 2d having the stator coil 2b is increased, and the flow is terminated.

[0024] This method not only increases the cooling amount of the stator 2d during rapid charging, but also reduces the cooling amount of the rotor 2c, thereby suppressing unnecessary operation of the oil pump and water pump and reducing battery power consumption.

[0025] (modified version) (Figure 3) The present invention can also be applied when the motor 2 is cooled using only cooling oil 3b without using cooling water 3a. In this case, the cooling water 3a cools the inverter 1 via the radiator 6 and EWP 7, but does not pass through the motor 2, instead circulating through other electrical devices (not shown) to cool it. On the other hand, the flow of cooling oil 3b that cools the motor 2 is the same as in Figure 1. Even in this case, the cooling water 3a can be reduced to a temperature that is sufficient to adequately cool the motor 2 by indirectly cooling the cooling oil 3b via the heat exchanger 4. Therefore, sufficient cooling can be achieved without circulating cooling water 3a through the motor 2, thus preventing burnout of the stator coil 2b during rapid charging.

[0026] Furthermore, when cooling the motor 2 using only oil cooling with cooling oil 3b, it is acceptable to start the circulation of cooling oil 3b after starting the circulation of cooling water 3a to the heat exchanger 4, start the circulation of cooling oil 3b after starting the circulation of cooling water 3a, or start them simultaneously.

[0027] (Figure 4) Figure 4(a) is a radial cross-sectional view of motor 2 showing the rise in the liquid level inside the motor, and Figure 4(b) is an axial cross-sectional view of Figure 4(a). In motor 2, the vehicle is stopped for rapid charging, and the rotation of rotor 2c is also stopped. If the rotor 2c is rotated while coolant 3b is present inside motor 2, there is a risk that the coolant 3b will enter the gap between stator 2d and rotor 2c. Therefore, in order to prevent the coolant 3b from entering the gap, the vehicle has a structure that disconnects the power transmission so as not to transmit power for driving to the drive shaft. This allows for a safe rise in the liquid level of coolant 3b inside motor 2, and the rotation of rotor 2c after rapid charging circulates the coolant 3b inside motor 2, thereby promoting heat transfer between the coolant 3b, rotor 2c, and stator 2d.

[0028] The flow rate adjustment unit 8 (Figure 1) oil-cools the stator 2d and increases the amount of cooling oil 3b, which is in direct contact with the stator coil 2b, from liquid level 3c to liquid level 3d when further cooling of the stator 2d is required. This increases the cooling efficiency of the stator 2d.

[0029] For the stator coil 2b, which becomes hot during rapid charging, the temperature of the stator coil 2b is detected by a sensor (not shown), for example. If the temperature change per unit time of this detected temperature is higher than a predetermined standard, it is determined that adequate cooling is insufficient, and the liquid level of the cooling oil 3b inside the motor 2 is determined to be rising. By raising the liquid level inside the motor 2, the cooling of the motor 2 during rapid charging can be improved.

[0030] (Figure 5) The control flow of the electric drive unit 100 of the present invention shown in Figure 4 will be explained. In step S11, the electric drive unit 100 determines whether the vehicle has started rapid charging. If it determines that rapid charging has started, it proceeds to step S12. If rapid charging has not started, the flow ends.

[0031] In step S12, it is determined whether cooling of the stator coil 2b is necessary during rapid charging, and if it is determined that it is necessary, the process proceeds to step S13. In step S13, the flow rate of the cooling oil 3b supplied to the stator 2d is increased in order to directly cool the stator coil 2b with the cooling oil 3b.

[0032] In step S14, it is determined whether it is necessary to raise the liquid level of the cooling oil 3b inside the motor 2. If it is not necessary to raise the liquid level inside the motor 2, the flow is terminated. If it is determined that it is necessary to raise the liquid level inside the motor 2, in step S15 the liquid level of the cooling oil 3b is raised further inside the motor 2 and the flow is terminated.

[0033] In this invention, the cooling of the motor 2 and inverter 1 by water cooling and oil cooling has been described above, but the cooling of the inverter 1 and motor 2 may also be achieved by water cooling alone.

[0034] According to the embodiments of the present invention described above, the following effects and advantages are achieved.

[0035] (1) An electric drive device for a vehicle comprising a motor 2 having a rotor 2c and a stator, and a refrigerant passage through which a refrigerant for cooling the motor 2 flows, wherein the motor 2 is driven by a battery and the battery is charged using the motor 2, and the electric drive device has a flow rate adjustment unit 8 that adjusts the flow rate of the refrigerant supplied to the rotor 2c and the stator. The flow rate adjustment unit 8 switches the flow rate of the refrigerant supplied to the rotor 2c and the stator so that when the battery is charged by energizing the stator coil 2b while the vehicle is stopped, the flow rate of the refrigerant supplied to the stator is increased compared to when the battery is charged without energizing the stator coil 2b. In this way, an electric drive device 100 can be provided that improves the reliability of the motor 2 in rapid charging of the battery.

[0036] (2) Equipped with a temperature sensor for detecting the temperature of the stator, the flow rate adjustment unit 8 increases the flow rate of refrigerant supplied to the stator when the temperature of the stator detected by the temperature sensor is greater than a predetermined threshold. This prevents burnout of the stator coil 2b during rapid charging of the battery.

[0037] (3) Equipped with a temperature sensor for detecting the temperature of the stator, the flow rate adjustment unit 8 reduces the flow rate of refrigerant supplied to the rotor 2c when the temperature of the stator detected by the temperature sensor is greater than a predetermined threshold. This prevents burnout of the stator coil 2b during rapid charging of the battery.

[0038] (4) The flow rate adjustment unit 8 switches the flow rate of the refrigerant supplied to the rotor 2c and stator so that the refrigerant filling height in the motor 2 is increased. This allows for further cooling of the stator coil 2b.

[0039] (5) The refrigerant comprises cooling water 3a and cooling oil 3b, and the cooling water 3a is circulated through a refrigerant flow path formed on the outer circumference of the stator. This prevents burnout of the stator coil 2b when the motor 2 is cooled by water cooling alone.

[0040] (6) The refrigerant includes cooling water 3a and cooling oil 3b, and comprises a first flow path through which cooling water 3a flows to cool the motor 2 and electrical equipment other than the motor 2, and a second flow path through which cooling oil 3b flows to cool the motor 2. At this time, either the cooling water 3a flowing through the first flow path or the cooling oil 3b flowing through the second flow path is allowed to flow first. In this way, regardless of which flow path is prioritized, it contributes to cooling the motor 2 during rapid charging.

[0041] (7) The refrigerant comprises cooling water 3a and cooling oil 3b, and includes a first flow path through which cooling water 3a flows to cool the motor 2 and electrical equipment other than the motor 2, and a second flow path through which cooling oil 3b flows to cool the motor 2. The cooling water 3a flowing through the first flow path is allowed to flow before the cooling oil 3b flowing through the second flow path. In this way, even if the second flow path is given priority over the first flow path, it contributes to cooling the motor 2 during rapid charging.

[0042] (8) A control method for an electric drive system that uses a battery to charge and drive the motor 2 in a vehicle in which a motor 2 having a rotor 2c and a stator is cooled by a refrigerant, wherein when the battery is charged by energizing the stator coil while the vehicle is stopped, the flow rate of the refrigerant supplied to the stator is switched so that the flow rate of the refrigerant supplied to the stator is increased compared to when the battery is charged without energizing the stator coil 2b. By adopting such a control method, the reliability of the motor 2 in rapid charging of the battery can be improved.

[0043] It should be noted that the present invention is not limited to the embodiments described above, and various modifications and combinations of other configurations can be made without departing from the spirit of the invention. Furthermore, the present invention is not limited to having all the configurations described in the embodiments described above, and may also include configurations in which some of those configurations are omitted. [Explanation of Symbols]

[0044] 1 Inverter 2 motors 2a Jacket 2b Stator coil 2c rotor 2D stata 3 Refrigerant 3a Cooling water 3b Cooling oil 3c Liquid level 3d Liquid level height after rise 4 Heat exchanger 5 EOP 6. Radiator 7 EWP 8 Flow rate adjustment section 9 shafts 100 Electric drive unit

Claims

1. An electric drive device for a vehicle comprising a motor having a rotor and a stator, and a refrigerant passage through which a refrigerant for cooling the motor flows, wherein the motor is driven by a battery and the battery is charged using the motor, It has a flow rate adjustment unit that adjusts the flow rate of the refrigerant supplied to the rotor and the stator, The flow rate adjustment unit switches the flow rate of the refrigerant supplied to the rotor and stator so that when the stator coil is energized to charge the battery while the vehicle is stopped, the flow rate of the refrigerant supplied to the stator is increased compared to when the battery is charged without energizing the stator coil. Electric drive system.

2. An electric drive device according to claim 1, The system includes a temperature sensor for detecting the temperature of the stator, The flow rate adjustment unit increases the flow rate of the refrigerant supplied to the stator when the temperature of the stator detected by the temperature sensor is greater than a predetermined threshold. Electric drive system.

3. An electric drive device according to claim 1, The system includes a temperature sensor for detecting the temperature of the stator, The flow rate adjustment unit reduces the flow rate of the refrigerant supplied to the rotor when the temperature of the stator detected by the temperature sensor is greater than a predetermined threshold. Electric drive system.

4. An electric drive device according to claim 1, The flow rate adjustment unit switches the flow rate of the refrigerant supplied to the rotor and stator so that the refrigerant filling height in the motor increases. Electric drive system.

5. An electric drive device according to claim 1, The refrigerant includes cooling water and cooling oil. The cooling water is circulated through a refrigerant flow path formed on the outer circumference of the stator. Electric drive system.

6. An electric drive device according to claim 1, The refrigerant includes cooling water and cooling oil. The device comprises a first channel through which cooling water flows to cool the motor and other electrical devices, and a second channel through which cooling oil flows to cool the motor. Either the cooling water flowing through the first channel or the cooling oil flowing through the second channel is allowed to flow first. Electric drive system.

7. An electric drive device according to claim 1, The refrigerant includes cooling water and cooling oil. The device comprises a first channel through which cooling water flows to cool the motor and other electrical devices, and a second channel through which cooling oil flows to cool the motor. The cooling water flowing through the first channel is to flow before the cooling oil flowing through the second channel. Electric drive system.

8. A control method for an electric drive system in a vehicle in which a motor having a rotor and stator is cooled by a refrigerant, wherein a battery is used to charge and drive the motor, When the battery is charged by energizing the stator coil while the vehicle is stopped, the flow rate of the refrigerant supplied to the rotor and stator is switched so that the flow rate of the refrigerant supplied to the stator is increased compared to when the battery is charged without energizing the stator coil. A method for controlling an electric drive device.

Images