JP3412526B2 - Motor control device and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect the temperature of a generator in an electric car, without exerting an influence on torque. SOLUTION: This device is provided with an engine 10, a generator 26 and a motor 28. At the time of usual running, power from the engine 10 is distributed to the generator 26, and power obtained by the generator 26 is supplied to the motor 28 to assist its torque. The temperature of the generator 26 is detected, and when the temperature reaches a constant temperature or higher, a controlling CPU 56 controls and decreases the rotational speed of the generator 26.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device and a control method, and more particularly to temperature protection of a generator in an electric vehicle. 2. Description of the Related Art In recent years, research and development of electric vehicles (including a hybrid type combining an engine and a motor) have been actively conducted from the viewpoint of low pollution and energy saving. As an example of such an electric vehicle, the power of an engine is distributed to a drive shaft and a generator using a planetary gear mechanism, a motor is connected to the drive shaft, and the drive shaft is driven by the motor torque during low-speed running. In normal driving, the drive shaft is driven by the torque from the engine, the generator is operated by the engine power to generate power, and the obtained power is supplied to the motor to assist the driving force with the motor torque. Is being developed. In order to operate these motors and generators reliably, temperature control such as cooling is indispensable. For example, in Japanese Patent Application Laid-Open No. 6-98590, the temperature of a motor is measured and the obtained temperature is measured. A technique for reducing a supply current to a motor as compared with a reference value is disclosed. However, when such current control is applied to the above-described electric vehicle as it is, the motor torque decreases in proportion to the current, so that the vehicle speed and acceleration decrease. Alternatively, there is a problem that a decrease in climbing power or the like is caused, which leads to an uncomfortable feeling of driving for the driver. In particular, iron loss is dominant in the temperature rise of the generator, and iron loss is mainly proportional to the first or second power of the rotation speed.
There was an operating point that simply controlling the current value was not effective from the viewpoint of not only torque reduction but also temperature protection. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to reliably prevent an increase in the temperature of a generator motor without lowering the running performance of a vehicle. It is an object of the present invention to provide a control device and a control method that can be used. [0007] In order to achieve the above object, the present invention relates to a power generation motor control device for a vehicle including a driving motor (motor) and a power generation motor (generator). Temperature detecting means for detecting the temperature of the generator motor, and when the detected temperature is equal to or higher than a predetermined temperature,
Have a control means for reduction control the rotational speed of the power generation motor, wherein the power generation motor, the drive wheel is coupled Dora
An engine that drives the drive shaft is connected and the engine
Power is supplied from the gin . As described above, in the present invention, the temperature protection is not performed by reducing the current value of the generator motor (generator), but by reducing the rotation speed of the generator motor. I'm trying. As described above, since the high rotation type motor generator such as iron loss occurs in proportion to 1-2 square of the rotational speed, the iron loss without Rukoto example influence the torque by reducing controlling the rotational speed Prevention and temperature protection can be achieved. In addition, the motor for power generation
The engine that drives the live shaft is connected,
Power can be supplied from the engine. in this case,
Driving force is constant by keeping generator torque constant
Can be maintained. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a hybrid electric vehicle according to the present embodiment. A planetary carrier 20 for supporting a planetary gear 18 of the planetary gear mechanism 16 is connected to the output shaft 12 of the engine 10 via a torsional damper. The sun gear 22 and the ring gear 24 of the planetary gear mechanism 16 are connected to rotors 30 and 32 of a generator motor 26 and a drive motor 28, respectively. The ring gear 24 further includes a power take-out gear 34.
Is connected. The power take-out gear 34 is connected to a differential gear 40 via a chain 36 and a gear train 38.
It is connected to the. The output side of the differential gear 40 is connected to a drive shaft 42 to which driving wheels (not shown) are coupled. The output and the number of revolutions of the engine 10 are controlled by an engine ECU 46 based on environmental conditions such as an operation amount of an accelerator pedal 44, a cooling water temperature, a negative pressure of an intake pipe, and an operating state of a generator 26 and a motor 28. .
The generator 26 and the motor 28 are controlled by a control device 48. The control device 48 includes a battery (secondary battery) 50 that supplies power to the generator 26 and the motor 28 and receives power from these. The exchange of power between the battery 50, the generator 26, and the motor 28
This is performed via the first inverter 52 and the second inverter 54, respectively. The control of the two inverters 52 and 54 is as follows.
The control CPU 56 performs this. This control is performed by the engine ECU 4
6, the operation amount of the accelerator pedal 44, the operation amount of the brake pedal 58, the shift range determined by the shift lever 60, the battery storage state, the rotation angle of the sun gear of the planetary gear mechanism 16, the planetary The determination is performed based on the rotation angle of the carrier and the rotation angle of the ring gear, and also based on the temperature of the generator 26. The rotation angles of the three elements of the planetary gear mechanism 16 are detected by a planetary carrier resolver 62, a sun gear resolver 64, and a ring gear resolver 66, respectively. The temperature of the generator 26 is detected, for example, by providing a temperature sensor on the stator winding. Control CPU 56
Is determined by the above conditions and u of the generator 26 and the motor 28.
Phase, v-phase, and W-phase currents, and currents L1 and L2 supplied or supplied from a battery or the other inverter.
, The opening and closing of the transistors Tr1 to Tr6 and Tr11 to Tr16 of the first and second inverters 52 and 54 are controlled. The operation of the hybrid electric vehicle according to the present embodiment is as follows. First, the engine 10 is stopped in a region where the efficiency of the engine 10 is low, such as at the time of starting or at a low speed, and the electric power from the battery 50 is supplied to the motor 28 so that the motor 28 runs. During normal running, the power of the engine 10 is transmitted to the sun gear 22 via the planetary gear mechanism 16.
And the ring gear 24. As described above, since the power take-out gear 34 is connected to the ring gear 24, the drive shaft is driven by the power distributed from the engine 10. The sun gear 22 is connected to the rotor 30 of the generator 26.
6. The electric power obtained by the power generation in step 6 is supplied to the motor 28 to perform torque assist (the rotor 32 of the motor 28 is connected to the ring gear 24, and when the motor 28 operates, the motor 28 is driven through the ring gear 24). Torque is applied to the drive shaft). At high load, the generator 26
Power from the battery 50 as well as power from the motor 28
To provide additional torque assist. As described above, the generator 26 generates electric power by the distributed power from the engine 10 during normal running and supplies the obtained electric power to the motor 28 to assist the torque. When a rotor having three permanent magnets and a stator formed by winding three-phase coils forming a rotating magnetic field and laminating thin magnetic steel sheets are used, the temperature may increase due to heat due to iron loss, which may cause a problem. There is. Therefore, in the present embodiment, the control CPU 56 monitors the temperature of the generator 26 and, when the temperature of the generator 26 becomes equal to or higher than a certain value, protects the generator 26 from heating by controlling the rotation speed of the generator 26 to decrease. ing. FIG. 2 shows how the control CPU 56 controls the rotation speed of the generator 26. In the figure, the horizontal axis represents the generator 26 detected by the temperature sensor.
The vertical axis represents the control ratio of the rotation speed of the generator 26. Here, the control ratio indicates a degree to which the original command value is reduced, and a control ratio of 100% means that the original command value (required rotation speed) is used as it is as the control value. Is output to the first inverter 52, and the control ratio of 50% means that the rotation speed of 50% of the original command value is used as the control value as the control value of the first inverter 52.
Means to output. Therefore, when the original command speed is N and the control ratio is A (%), the output speed Nm
Is as follows: Nm = N · A / 100 Then, as shown in the figure, the control ratio is 100% up to a certain temperature T1, decreases monotonously between T1 and T2, and becomes 0% at the temperature T2. As described above, the control CPU 56 determines the temperature T1
Up to this time, the generator 26 is driven according to the required number of revolutions to generate power, but when the temperature exceeds T1, the required number of revolutions is monotonously decreased with respect to the temperature. As described above, the iron loss of the generator 26 increases in proportion to the first to the second power of the rotation speed. Therefore, instead of decreasing the current value as in the related art, it is possible to effectively reduce the rotation speed. Temperature rise can be suppressed. When the current is reduced as in the prior art, the torque of the generator 26 decreases in proportion to the current, so that the vehicle speed and the acceleration are reduced.
By reducing the number of revolutions as in the present embodiment, it is possible to prevent a decrease in torque and maintain traveling performance. That is, since the generated torque of the engine 10 is transmitted to the drive shaft as a product of the torque of the generator 26 and the planetary gear ratio, the driving force can be kept constant by keeping the torque of the generator 26 constant. . FIG. 3 shows a typical torque curve of the generator 26 for reference. In the figure, the horizontal axis is the rotation speed, and the vertical axis is the torque. The characteristic is that the torque is almost constant up to the high rotation range, and the torque suddenly decreases when the rotation speed exceeds a certain rotation speed. Accordingly, the required rotational speed is N1, and even if the rotational speed is reduced to N2 in accordance with the control ratio shown in FIG. 2, the torque is substantially constant. Can be achieved. In the conventional temperature protection, as shown by a in the figure, the current value was reduced to reduce the torque to prevent the temperature from rising, and the rotation speed was reduced while maintaining the torque as in the present embodiment. It should be noted that the technique is essentially different from the technique (shown in the figure). As for the motor 28, the current may be reduced to prevent the temperature from rising as in the prior art. Further, in the present embodiment, as shown in FIG. 2, when the temperature exceeds a certain temperature T1, the number of revolutions of the generator is monotonously reduced. However, the method of reduction is arbitrary, for example, a parabola or the like. It is also possible to define a decreasing curve with. The relationship in FIG. 2 may be stored in the memory as a function by the control CPU 56 or may be stored in the memory as a map. As described above, according to the present invention,
The temperature rise of the generator motor (generator) can be reliably prevented without lowering the traveling performance of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an embodiment of the present invention. FIG. 2 is a diagram showing a relationship between a generator temperature and a control ratio. FIG. 3 is a diagram showing torque characteristics of a generator. [Description of Signs] 10 engine, 26 electric motor (generator) for generation, 28 electric motor (motor) for driving, 48 control device.

Claims (1)

(57) [Claim 1] A generator motor control device for a vehicle including a drive motor and a generator motor, comprising: temperature detection means for detecting the temperature of the generator motor; If the temperature that is is equal to or higher than a predetermined temperature, have a, and control means for reduction control the rotational speed of the power generation motor, the power generation motor is de drive wheels are coupled
The engine that drives the live shaft is connected,
An electric motor control device, wherein power is supplied from an engine .