JP2008312343A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor capable efficiently cooling a permanent magnet equipped on a rotor and suppressing the generation of irreversible thermal demagnetization caused by heat. <P>SOLUTION: The motor 10 includes a stator 16 having a stator coil 15; a rotor 13 held rotatably on a motor case 18 by a bearing 12; a pump 31 for supplying a cooling oil for cooling the motor 10; a motor 32 for the pump; and a motor control section 25 for controlling the motor. A vehicle control section 26 outputs a command to the motor control section 25, measures the temperature of a stator coil end portion of the motor 10 using a temperature sensor 21, and measures the rotation number of the motor 10. Further, the vehicle control section 26 calculates a motor torque from a drive voltage or a drive current etc. by a motor inverter 22, acquires information about the control state from the motor control section 25 and controls the rotation number of the motor 32 for the pump. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor device, and more particularly to a motor device including means for suppressing temperature rise of a stator, a rotor, and the like accompanying the operation of the motor device.

  In recent years, in a hybrid vehicle, an electric vehicle, a fuel cell vehicle, and the like, in order to improve the running performance of the vehicle, the output of the motor device with a high voltage has been increased. Generally, since the winding used for a motor apparatus has an electrical resistance, it heat | fever-generates from the coil of a stator by operating a motor apparatus. If this heat generation exceeds heat dissipation, the internal temperature of the motor device rises and the life of the motor device cannot be ensured. Therefore, it is necessary to cool the motor device itself to promote heat dissipation.

  Conventionally, various technologies relating to cooling of motor devices have been developed. For example, Patent Document 1 discloses a technique in which lubricating oil that circulates in a motor device to cool the motor device is dropped from an oil passage chamber at the top of the motor case to an end portion of a stator through an oil hole.

  Further, in Patent Document 2, a cooling oil jet port for cooling is provided on the rotating shaft of the motor device so as to face the coil end portion, and cooling oil discharged by a pump is directly applied to the winding portion. Furthermore, a technique for controlling the amount of lubricating oil in accordance with the temperature of the winding portion that changes depending on the driving state of the motor device is disclosed. Since such a technique can mainly cool the stator coil, it is possible to suppress an increase in the electrical resistance of the coil and prevent a change in motor characteristics due to overheating when a large current is supplied.

  However, in a motor device having a permanent magnet on the rotor side, the permanent magnet disposed on the outer periphery of the rotor causes a problem of irreversible thermal demagnetization (hereinafter also referred to as thermal demagnetization) due to heat when the temperature increases. On the other hand, Patent Document 3 discloses a technique for preventing the thermal demagnetization of the permanent magnet incorporated in the rotor by suppressing the rise in the rotor temperature by circulating the cooling oil in the motor device using the centrifugal force of the rotor. Has been.

JP-A-5-122903 JP-A-5-236704 Japanese Patent Laid-Open No. 9-182374

  With the above-described technology, it is difficult to ensure a sufficient amount of cooling oil as a cooling medium when the motor is operating at a low speed, and it is difficult to sufficiently lower the rotor temperature as the low speed operation continues.

  On the other hand, in the prior art, since the main purpose is cooling the stator that generates a large amount of heat, the amount of cooling oil is increased during high motor torque and high motor rotation. However, since the operating region in which the rotor is hot also exists in the low speed region, there is a possibility of thermal demagnetization of the permanent magnet in the low speed region, but this has been dealt with by cooling with a margin.

  Thus, in the conventional cooling method, the supply amount to the stator and the rotor cannot be finely controlled, so unnecessary oil is circulated even in the operation region where cooling is not required. The motor efficiency was reduced by consuming energy.

  Accordingly, an object of the present invention is to provide a motor device capable of efficiently cooling a permanent magnet provided on a rotor of the motor device and suppressing occurrence of irreversible thermal demagnetization due to heat.

  In order to achieve the above object, a motor device according to the present invention includes a stator, a rotor having a permanent magnet, a cooling medium path that supplies a cooling medium to the rotor, and a cooling medium that supplies the cooling medium path. It is characterized by comprising a refrigerant supply means, a state detection means for detecting at least motor torque, and a cooling control means for controlling the supply amount of the refrigerant supply means in accordance with the detected motor torque.

  In the motor device according to the present invention, the state detection means detects the motor rotation speed and the motor torque, and the cooling control means supplies the refrigerant supply means according to the detected rotor rotation speed and the motor torque. It is characterized by controlling.

  Further, in the motor device according to the present invention, the cooling control means controls the supply amount of the refrigerant supply means based on the preset heat generation state of the rotor, the motor rotational speed and the motor torque detected by the state detection means. It is characterized by controlling.

  Furthermore, in the motor device according to the present invention, the state detection means measures at least one of a motor drive voltage and a motor drive current.

  Furthermore, in the motor device according to the present invention, the cooling medium path is given a predetermined angle with respect to the circumferential direction of the rotor in order to send the cooling medium into a plurality of through holes provided in the axial direction of the rotor. A jet port is provided, and when the rotor rotates at a predetermined rotation speed, the cooling medium is sent to the through hole and the rotor wall surface.

  Furthermore, in the motor device according to the present invention, the cooling control means controls a discharge amount of a pump for supplying a cooling medium.

  By using the present invention, even when the permanent magnet generates heat at high motor torque and low rotation, the permanent magnet can be suitably cooled by controlling the supply amount of the cooling oil as the cooling medium. It becomes possible to control the cooling oil amount in the entire operation state of the motor device.

  Further, by using the present invention, it is possible to finely control the supply amount of the cooling oil by predicting the heat generation amount of the magnet. For this reason, in the area | region which does not need cooling, supply amount can be decreased and consumption of useless energy in the circulation of a cooling medium can be suppressed. Further, since at least one of voltage and current is measured, motor torque can be easily detected.

  Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 shows an overall configuration of a motor system 100 including a motor device 10, and an outline is shown using FIG. 1. The motor device 10 cools a stator 16 having a stator coil 15 provided in a motor case 18, a shaft 11 rotatably held by a bearing 12, a rotor 13 assembled to the shaft 11, and the motor device 10. A pump 31 that supplies cooling oil for the pump, a pump motor 32 that drives the pump 31, and a motor control unit 25 that controls the motor device 10 are included.

  The cooling oil for cooling the motor device 10 is pressurized by the pump 31 and the temperature is lowered by an oil cooler (not shown). The cooled cooling oil is divided into, for example, nozzles and bearings by a distributor 33 whose flow rate is adjusted by an orifice or the like. For example, the cooling oil supplied to the bearing 12 is supplied from the bearing oil passage 34 to the bearing 12, passes through the bearing 12, flows on the side surface of the rotor, cools the rotor, and cools the coil end portion of the stator coil 15. The cooling oil supplied to the shaft oil passage 35 passes through the cooling oil passage at the center of the rotor, flows to the axial oil passage 17, cools the inside of the rotor, and is then guided to the rotor side surface to cool the rotor side surface. Later, the coil end is cooled.

  On the other hand, the cooling oil discharged from the nozzle jet port arranged at a predetermined angle is sprayed from the nozzle to the rotor side surface. More specifically, the sprayed cooling oil is sprayed on the rotor side surface and the axial oil passage at an angle forming a speed triangle between the circumferential speed of the rotor and the discharge speed of the cooling oil.

  The motor system 100 includes a battery 24, a boost converter 23 that boosts the voltage (VB) of the battery 24, a motor inverter 22 that drives the motor device 10 using the boosted voltage (VH), and a vehicle control unit that controls the vehicle. 26.

  The vehicle control unit 26 detects an instruction from the driver from the accelerator 41 and the shift switch 42 and outputs the instruction to the motor control unit 25, and measures the temperature of the stator coil end portion of the motor device 10 by the temperature sensor 21. The rotational speed of the motor device 10 is measured by a resolver (not shown). Further, the vehicle control unit 26 calculates motor torque from the drive voltage or drive current from the motor inverter 22 and obtains information on the control status from the motor control unit 25.

  FIG. 2 shows a rotor magnet heat generation map and a stator heat generation map obtained by actual measurement. In general, since the stator is fixed to the motor case, temperature measurement is easy with a temperature sensor or the like, but since the rotor is rotating, temperature measurement cannot be easily performed. Therefore, in this experiment, an experiment was carried out by specially producing an experimental vehicle that can measure the temperature of the rotor magnet with a slip ring provided on the motor shaft.

  In the contour-line-shaped heat generation amount in the rotor magnet heat generation map of FIG. 2 (D), when the motor torque is high and around 4000 rpm, the high-frequency noise in the PWM control affects the rotor magnet and the heat generation amount increases. In wave control, the amount of heat generation decreases rapidly. Furthermore, discontinuous heat generation characteristics are shown at the inflection point between the PWM control and the rectangular wave control described above.

  The contour heat generation amount in the stator heat generation map of FIG. 2 (C) is almost 10 times that of the rotor magnet heat generation map shown in FIG. 2 (D), and it can be seen that most of the heat generation is from the stator coil.

  In the rotor magnet thermal demagnetization temperature limit map shown in FIG. 3, the thermal demagnetization limit temperature due to the weakening magnetic field generated when the motor device is driven is divided into, for example, five stages from 160 ° C. to 210 ° C. . Because of this limitation, it is necessary to operate the rotor magnet temperature below the thermal demagnetization limit temperature under each operating condition based on the combination of the rotational speed and torque. Furthermore, as described above, although most of the heat generation is in the stator coil, the thermal demagnetization limit temperature occurs at high motor torque and low rotation, and the thermal demagnetization limit temperature decreases as the motor torque increases. Fine cooling control is required.

  FIG. 4 shows a state where the motor device is used at a low motor torque and a low rotational speed, and FIG. 5 shows a state where the motor device is used at a high motor torque and a low rotational speed. FIG. 6 shows the state shown in FIGS. 4 and 5 on the rotor magnet thermal demagnetization temperature limit map. Hereinafter, description will be made with reference to FIGS.

  As shown in FIG. 4, if the motor torque is, for example, 100 Nm or less, the amount of heat generation is about 0.5 kW for rotor magnet heat generation and about 5 kW for stator heat generation. On the other hand, as shown in FIG. 5, when the motor torque is, for example, 200 Nm or more, the heat generation amount is about doubled, the rotor magnet heat generation is about 1 kW, and the stator heat generation is about 10 kW. Furthermore, as shown in FIG. 6, the rotor magnet thermal demagnetization limit temperature decreases as the motor torque becomes higher, so the discharge amount of cooling oil is increased so that the rotor magnet does not undergo thermal demagnetization, It is necessary to promote heat dissipation. Therefore, in the present embodiment, such a situation is detected, and the rotation speed of the pump motor 32 controlled by the motor control unit 25 is increased.

  7, 8, and 9 are diagrams illustrating a structure for efficiently cooling the rotor in a state where the motor is used at a high motor torque and a low rotation. Specifically, FIG. 7 shows the shape of the rotor side surface, FIG. 8 shows the arrangement of the nozzle outlets, and FIG. 9 shows the delivery amount delivered to the axial oil passage due to the change in the cooling oil discharge speed. Show.

  The rotor shown in FIG. 7 has a shaft 11, a permanent magnet 14, an axial oil passage 17, and an oil receiving portion 19 for guiding cooling oil to the axial oil passage 17. By providing the oil receiver 19, it is possible to widen the corresponding rotational speed range of the circumferential speed of the rotor that can be guided to the axial oil passage 17 (for example, 2000 to 8000 rpm).

  As shown in FIG. 8, the motor device is given a predetermined inclination angle (θ degrees) with respect to the circumferential direction of the rotor in order to send the cooling oil to a plurality of axial oil passages provided in the axial direction of the rotor. A spout is provided. By adopting such a structure, when the rotor rotates at, for example, 2000 to 8000 rpm, the cooling oil discharge speed and the tilt angle are set so as to coincide with the peripheral speed of the axial oil passage. Cooling oil is sent to the axial oil passage and the rotor wall surface, and is sent to the rotor wall surface exclusively at other rotational speeds, does not reach the axial oil passage, and is used for cooling the end portion of the stator.

  FIG. 9 shows the relationship between the jetting speed and the amount of cooling oil delivered. The circumferential rotational speed of the rotor is proportional to the rotational speed of the rotor, and at a discharge speed of “medium”, a large amount of cooling oil is sent to the axial oil passage due to the relationship of the speed triangle, and the rotor is cooled. Further, when the discharge speed is “small” or “large”, it is sent exclusively to the side surface of the rotor to cool the stator coil end portion.

  As described above, in the motor device according to this embodiment, by controlling the discharge amount of the cooling oil, at the time of low motor torque, by reducing the discharge amount, the stator is not fed into the axial oil passage. Can be cooled directly. For this reason, fine control becomes possible and it becomes possible to suppress the circulation of useless cooling oil. Needless to say, the above-described tilt angle of the nozzle outlet needs to be set appropriately depending on the rotor diameter, the rotational speed, the cooling oil discharge speed, and the like.

1 is an overall configuration diagram of a motor system including a motor device according to an embodiment of the present invention. It is the stator heat_generation | fever map figure and rotor magnet heat_generation | fever map figure of the motor apparatus by actual measurement. It is a rotor magnet thermal demagnetization temperature limit map figure concerning the embodiment of the present invention. It is explanatory drawing explaining the state which used the motor apparatus which concerns on embodiment of this invention with low motor torque and low rotation speed. It is explanatory drawing explaining the state which used the motor apparatus which concerns on embodiment of this invention with high motor torque and low rotation speed. It is explanatory drawing explaining the rotor magnet thermal demagnetization temperature limit at the time of making it operate | move on different operating conditions in the motor apparatus which concerns on embodiment of this invention. It is explanatory drawing explaining the rotor side surface of the rotor which concerns on embodiment of this invention. It is explanatory drawing explaining arrangement | positioning of the jet nozzle which concerns on embodiment of this invention. It is a characteristic view which shows the characteristic of the sending amount of the cooling oil which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Motor apparatus, 11 Shaft, 12 Bearing, 13 Rotor, 14 Permanent magnet, 15 Stator coil, 16 Stator, 17 Axial oil passage, 18 Motor case, 19 Oil receiver, 21 Temperature sensor, 22 Motor inverter, 23 Boost converter , 24 battery, 25 motor control unit, 26 vehicle control unit, 31 pump, 32 motor for pump, 33 distributor, 34 bearing oil passage, 35 shaft oil passage, 41 accelerator, 42 shift switch, 100 motor system.

Claims (6)

A stator and a rotor having permanent magnets;
A cooling medium path for supplying the cooling medium to the rotor;
Refrigerant supply means for supplying a cooling medium to the cooling medium path;
State detecting means for detecting at least motor torque;
Cooling control means for controlling the supply amount of the refrigerant supply means in accordance with the detected motor torque;
A motor device comprising: The motor device according to claim 1,
The state detection means detects the motor speed and the motor torque,
The cooling control means controls the supply amount of the refrigerant supply means in accordance with the detected rotor rotational speed and motor torque. The motor device according to claim 2,
The cooling control means controls the supply amount of the refrigerant supply means based on a preset heat generation state of the rotor, and the motor rotation speed and motor torque detected by the state detection means. The motor device according to any one of claims 1 to 3,
The state detection means measures at least one of a motor drive voltage and a motor drive current. The motor device according to claim 1,
The cooling medium passage is provided with a jet outlet having a predetermined angle with respect to the circumferential direction of the rotor in order to send the cooling medium to a plurality of through holes provided in the axial direction of the rotor. When the motor rotates, the cooling medium is sent to the through hole and the rotor wall surface. The motor device according to any one of claims 1 to 3,
The cooling control means controls a discharge amount of a pump for supplying a cooling medium.

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