JPH06121402A - Electric motor car driven by battery - Google Patents

Abstract

PURPOSE:To provide a battery-driven electric motor car wherein excellent cooling of a semiconductor switch and saving of power consumption can be made compatible. CONSTITUTION:A semiconductor switch 3 controls the ON/OFF of a current to a motor 2 for vehicle running from a battery 1 in response to the command value from an accelerator means 6. A temperature detecting means 17 detects the temperature of the semiconductor switch 3. A cooling-device control means 8 controls the ON/OFF of cooling devices 4 and 5. The cooling devices 4 and 5 cool the semiconductor switch based on the operating command from the cooling-device control means 8. The cooling-device control means 8 accelerates the start of the driving of the cooling devices 4 and 5 when the tread angle of the accelerator means 6 is large. As a result, the cooling of the semiconductor switch 3 is accelerated when the accelerator means 6 is largely stepped on, and the large current flows through the semiconductor switch 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery-driven electric vehicle having a cooling device for a semiconductor switch for interrupting motor driving current.

[0002]

2. Description of the Related Art Conventionally, a battery-powered electric vehicle in which a semiconductor switch intermittently controls a current supplied from a battery to a motor for traveling a vehicle in response to an accelerator has been widely known. In order to detect the temperature of the semiconductor switch, a temperature sensor that detects the temperature of the semiconductor switch, a cooling pump that circulates a cooling liquid through the semiconductor switch, and a pump motor that drives the cooling pump are provided. Battery-powered electric vehicles have been proposed for cooling semiconductor switches.

[0003]

However, in the above-described conventional semiconductor switch cooling technique, in order to start cooling after confirming the temperature rise of the semiconductor switch to a predetermined level, for example, when the vehicle is started in a high temperature environment, When a large current is applied to the semiconductor switch when the semiconductor switch is in a temperature state slightly lower than the predetermined pump starting temperature, the temperature of the semiconductor switch rapidly rises. On the other hand, since the temperature sensor that detects the temperature of the semiconductor switch is delayed to some extent from the actual temperature rise of the semiconductor switch, there is a possibility that the cooling pump is driven to cool the semiconductor switch and the temperature of the semiconductor switch becomes too high. there were.

Of course, the excessive temperature rise of the semiconductor switch due to the delay in starting the pump can be absorbed in the allowable temperature range level by setting the starting temperature of the pump to a considerably low temperature. However, a decrease in pump starting temperature causes an increase in power consumption due to an increase in pump driving time, which is a problem that cannot be ignored in a battery-driven electric vehicle that has a large limit in power usage.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a battery-powered electric vehicle capable of both good cooling of a semiconductor switch and saving of power consumption.
Its purpose is.

[0006]

SUMMARY OF THE INVENTION A battery-driven electric vehicle according to the present invention includes a battery, a motor for driving the vehicle, an accelerator means for instructing a vehicle speed, and a battery in response to a command value of the accelerator means. A semiconductor switch for intermittently controlling the current supplied to the motor, a temperature detecting means for detecting the temperature of the semiconductor switch, a cooling device for cooling the semiconductor switch, and the cooling device based on the temperature detected by the temperature detecting means. In a battery-powered electric vehicle including: a cooling device control unit for intermittently controlling the cooling device, the cooling device control unit promotes driving start of the cooling device when the depression angle of the accelerator unit is large.

In a preferred mode, the cooling device control means drives the cooling device in preference to the detected temperature when the depression angle of the accelerator means exceeds a predetermined level.

[0008]

The semiconductor switch intermittently controls the current from the battery to the vehicle driving motor according to the command value of the accelerator means. The temperature detection means detects the temperature of the semiconductor switch, the cooling device control means controls the cooling device intermittently based on the detected temperature, and the cooling device cools the semiconductor switch based on the operation command of the cooling device control means.

Further, the cooling device control means promotes the driving start of the cooling device when the depression angle of the accelerator means is large. As a result, cooling of the semiconductor switch is promoted when the accelerator means is stepped on greatly and a large current flows through the semiconductor switch.

[0010]

As described above, in the battery-powered electric vehicle of the present invention, when the accelerator pedal has a small pedaling angle, the cooling device is controlled in accordance with the temperature of the semiconductor switch, and when the accelerator pedal has a large pedaling angle. Since the structure that promotes the start of cooling of the semiconductor switch is adopted, it is possible to prevent the temperature of the semiconductor switch from excessively rising when the accelerator pedal angle is large.

Further, in order to prevent the temperature of the semiconductor switch from excessively rising when the accelerator pedal angle is large, it is not necessary to lower the operation start temperature of the cooling device that operates according to the temperature of the semiconductor switch. It is possible to reduce the operating time of the cooling device and save valuable power. Further, when the cooling is preferentially started at the time of the large accelerator pedal depression regardless of the detected temperature, the cooling can be started at the same time as the large heat generation of the semiconductor switch, and the excessive temperature rise can be effectively prevented. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic sectional view of an embodiment of a battery-driven electric vehicle of the present invention. In this battery-driven electric vehicle, 1 is a battery, 2 is a traveling drive motor (hereinafter referred to as a motor), and 3 is a current control unit that controls a current supplied from the battery 1 to the motor 2. The current control unit 3 has, for example, a power transistor with a grounded emitter (a semiconductor switch according to the invention (not shown)) built in, and the collector of this power transistor is connected to the high-level terminal of the battery 1 through the motor 2. . Further, the current controller 3 has a built-in temperature detector (here, a thermal switch) 17 (see FIG. 2) for detecting the temperature of the power transistor.

Reference numeral 4 is a pump which is driven by a motor 41 (see FIG. 2) to circulate a cooling liquid, and 5 is an electric fan 51 (see FIG. 2).
(Refer to FIG. 4) Built-in radiator, and 4 and 5 constitute cooling means in the present invention. Reference numeral 6 denotes an accelerator (accelerator means in the present invention), and the accelerator 6 has a built-in resolver (not shown) that outputs an analog signal voltage proportional to the pedaling angle. 7 is a speed reducer, which is a motor 2
The speed of rotation is reduced and transmitted to the front wheels. Reference numeral 8 denotes a controller (cooling device control means in the present invention) which receives input signals from the accelerator 6 and the temperature detector 17 and drives and controls the motor 2, the pump 4, and the electric fan 51. The controller 8 has a built-in microcomputer (not shown) that controls the rotation speed of the motor 2.

The basic operation of this device will be described. When the accelerator 6 is stepped on, the resolver outputs an analog angle signal proportional to the stepped angle to a microcomputer in the controller 8 and an A / D converter ( (Not shown)
Converts A / D conversion of the input analog angle signal, CPU
(Not shown). The CPU searches a duty ratio corresponding to the input digital angle signal from a map built in the memory, and outputs a pulse signal of a predetermined frequency having the searched duty ratio through an amplifier (not shown) to the base of the power transistor. Apply to. As a result, the controller 8 adjusts the duty ratio of the current supplied to the motor 2 in proportion to the input accelerator pedal depression angle. In this way, the motor 2 generates a rotational force according to the supplied electric power, and the speed reducer 7
The wheels 9 are rotated via. As a result, the accelerator 6
Electric power is supplied to the motor 2 according to the stepping angle of the vehicle to control the speed of the vehicle. From the above description, it is understood that the motor drive current is supplied to the current control unit 3, in particular, its power transistor in proportion to the depression angle of the accelerator 6, and the heat generation of the power transistor is approximately proportional to the depression angle of the accelerator 6. It

The characteristic points of this embodiment will be described below. When the pump 4 and the electric fan 51 are activated, the cooling liquid is pump 4, the current controller 3, the motor 2, the radiator 5, and the pump 4.
The current controller 3 and the motor 2 are circulated through the path indicated by the arrow in FIG. Hereinafter, the main part of the controller 8 is shown in the circuit diagram of FIG.

In FIG. 2, the high level power supply line Vcc extending from the high level terminal of the battery 1 is grounded through a resistor r1 and a thermal switch (temperature detecting means in the present invention) 17. The thermal switch 17 is a normally closed switch that opens at a predetermined temperature. Also, between Vcc and ground,
A limit switch LS, which conducts at a predetermined depression angle of the accelerator 6, a resistor r2, and a resistor r3 are sequentially connected in series. The connection point between the resistor r1 and the thermal switch 17 is connected to the anode of the diode D, and the cathode of the diode D is connected to the connection point of the resistors r2 and r3.
At the connection point between the resistors r2 and r3, the base of the transistor Tr whose emitter is grounded is the base current limiting resistor r
4 and its collector is connected to Vcc through the exciting coil of the electromagnetic relay R. One end of the normally open contact of the electromagnetic relay R is connected to Vcc, the other end is connected to one input end of the motor 41 that drives the pump 4, and one input end of the electric fan 51, and the other input end is grounded. ing.

The operation of the controller 8 will be described below.
If the depression angle of the accelerator 6 does not exceed the predetermined value and the temperature detected by the switch 17 does not exceed the predetermined temperature, the limit switch L
S is a cutoff state, thermal switch 17 is a conduction state, transistor 11 is in a cutoff state because the base potential is 0, the exciting coil of relay R is not energized, and the normally open contact of relay R is It is opened, the motor 41 and the electric fan 51 are not energized, and the pump 4 remains stopped.

When the pedal depression angle of the accelerator 6 exceeds a predetermined value and the detected temperature does not exceed the predetermined temperature, both the limit switch LS and the thermal switch 17 become conductive. At this time, the divided voltage of the battery 1 divided by the resistors r2 and r3 is applied to the base of the transistor Tr through the base current limiting resistor r4, the transistor Tr becomes conductive, and the normally open contact of the relay R is closed. The motor 41 and the electric fan 51 are energized to start the pump 4.

As a result, the cooling liquid is sent to the current controller 3 and the motor 2, and these are liquid-cooled. When the depression angle of the accelerator 6 exceeds a predetermined value and the detected temperature exceeds a predetermined value, the limit switch LS is turned on and the thermal switch 17 is turned off. The transistor Tr is turned on, and liquid cooling is performed as described above.

When the pedal depression amount of the accelerator 6 does not exceed the predetermined value and the detected temperature exceeds the predetermined value, both the limit switch LS and the thermal switch 17 are turned off. A voltage divided by the resistors r1 and r3 is applied to the base of the transistor Tr, the transistor Tr is turned on, and liquid cooling is performed as described above. As a result, the thermal switch 1
Regardless of whether the accelerator pedal 7 is activated or inactivated, if the pedal depression angle of the accelerator pedal 6 exceeds a predetermined level, the pump 4 and the electric fan 51 are preferentially activated to prevent the temperature of the current controller 3, especially the power transistor thereof from overheating. Ascension is suppressed. (Embodiment 2) Another embodiment is shown in FIG.

In this embodiment, the circuit upstream of the base current limiting resistor r4 in FIG. 2 is represented by resistors r5 and r6, a posistor P (temperature detecting means in the present invention), and a variable resistor r.
x is changed to a comparator C. The variable resistor rx is installed so that its resistance value changes according to the stepping angle of the accelerator 6, and the posistor P is arranged close to the power transistor and its resistance value increases as its temperature rises.

The + input terminal of the comparator C is connected to Vcc through a resistor R5 and to the ground line through a posistor P. The negative input terminal of the comparator C is connected to Vcc through a resistor R6 and to the ground line through a variable resistor rx. When the pedaling angle of the accelerator 6 increases, the resistance value of the variable resistor rx decreases, and when the pedaling angle decreases, the resistance value increases. Therefore, when the depression angle of the accelerator 6 increases, the resistance value of the variable resistor rx decreases accordingly, and the potential of the negative input terminal of the comparator C decreases. A voltage obtained by dividing the battery 1 by the resistor r5 and the posistor P is generated at the + input terminal of the comparator C. Since the resistance value of the posistor P increases as the temperature rises, the potential of the + input terminal of the comparator C rises as the temperature rises.

As a result, when the depression angle of the accelerator 6 increases, the voltage (threshold voltage) at the + input end of the comparator C decreases, and even when the potential at the + input end is low (the temperature of the power transistor is low). It is easy for the comparator to go high. As a result, if the detected temperature is high to some extent and the depression angle of the accelerator 6 is slightly increased, the comparator C outputs a high level, the transistor Tr is turned on, and liquid cooling is started.

Further, when the detected temperature is low to some extent, the comparator C can be operated only by slightly increasing the pedaling angle of the accelerator 6.
Does not output a high level, and the comparator C outputs a high level only when the depression angle of the accelerator 6 greatly increases, the transistor Tr is turned on, and liquid cooling is started.
Therefore, according to the present embodiment, it is possible to continuously change the liquid cooling start temperature in association with the amount of depression of the accelerator 6 and to start the liquid cooling even when the accelerator 6 has a large depression at a very low temperature. 1
It can be delayed more than in the case of 1, and reduction of power consumption can be realized. (Embodiment 3) Another embodiment is shown in FIG.

In this embodiment, in FIG. 3, a variable resistor rx is formed by a multi-stage changeover switch SW and a large number of different parallel resistors R which connect each selection contact of the multi-stage changeover switch SW and a resistor r6 in parallel. It has been replaced. The multi-stage changeover switch SW is, for example, a rotary switch, and is arranged so as to rotate in proportion to the depression of the accelerator 6.

By doing so, the resistance value of the parallel resistance R can be reduced stepwise in proportion to the stepping angle of the accelerator 6, and the same effect as that of the second embodiment can be obtained. In the above embodiment, the motor 41 and the electric fan 51 are separately driven without being driven in parallel, and the pump 4 is driven according to the depression angle of the accelerator 6 to detect the temperature when the temperature rises and exceeds a predetermined value. The electric fan 51 may be driven by the output of the means.

Further, in the second and third embodiments, the cooling capacity can be changed by changing the power supplied to the cooling means continuously or stepwise by the output of the temperature detecting means.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of a battery-powered electric vehicle of the present invention.

FIG. 2 is a circuit diagram of the controller of FIG.

FIG. 3 is a circuit diagram of a controller according to a second embodiment.

FIG. 4 is a circuit diagram of a controller according to a third embodiment.

[Explanation of symbols]

1 ... Battery, 2 ... Motor, 3 ... Current control section (semiconductor switch), 4 ... Pump (cooling device), 5 ... Radiator (cooling device), 6 ... Accelerator (accelerating means), 8 ... ... Controller (cooling device control means), 17
… Thermal switch (temperature detection means).

Claims (2)

[Claims] 1. A battery, a motor for driving a vehicle, accelerator means for commanding a vehicle speed, and a semiconductor switch for intermittently controlling a current supplied from the battery to the motor in response to a command value of the accelerator means. A battery drive including temperature detection means for detecting the temperature of the semiconductor switch, a cooling device for cooling the semiconductor switch, and cooling device control means for intermittently controlling the cooling device based on the temperature detected by the temperature detection means In the electric vehicle, the cooling device control means promotes driving start of the cooling device when the depression angle of the accelerator means is large, and the battery driving electric vehicle. 2. The battery-driven electric vehicle according to claim 1, wherein the cooling device control means drives the cooling device with priority over the detected temperature when the pedaling angle of the accelerator means exceeds a predetermined level.