JPH09238407A - Motor driver for motor-driven vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost driver as the speed controller of the traveling and loading/unloading AC motor of a motor-driven vehicle, particularly an automatic truck or a battery forklift. SOLUTION: A motor driver for motor-driven vehicles is composed of a battery 1, an inverter 5, a traveling and loading/unloading AC motor 10, a traveling and loading/unloading motor 8, a contactor 11 which drives the traveling and loading/unloading AC motor 10, a traveling and loading/unloading speed control instruction signal circuit and a microcomputer circuit 27 to which a signal from the signal circuit is inputted and which determines the operations of the inverter 5 and the contactor 11. Control software by which the repetition of the on-state and off-state of the contactor 11 is changed in accordance with the magnitude of the traveling instruction signal from the traveling and loading/ unloading speed control instruction signal circuit is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control device for an electric vehicle, mainly for an automatic carrier or a battery forklift AC motor for traveling and loading and unloading, and relates to an inexpensive drive device using one inverter and one contactor.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 54-40819 discloses a method in which one speed control device is used and two motors (for traveling and cargo handling) are driven using contactors.

This uses a thyristor chopper circuit for time sharing so that a large current does not flow at the time of starting, and the cargo handling motor rotates at the maximum speed and cannot operate at a low speed.

Further, since the DC motor is used, the brush is worn and maintenance is required.

Therefore, although a brushless AC motor is suitable, the price of the inverter is high and it has not been put to practical use.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive drive device for controlling the speed of two AC motors (for traveling and cargo handling).

[0007]

A drive circuit of an AC motor is composed of one inverter and a contactor, and is composed of a circuit for switching the contactor and controlling the inverter according to the magnitude of a traveling speed command signal.

The inverter has three phases (three arms are provided), and the contactor is capable of switching two contacts. One phase of the inverter is connected to two AC motors (for traveling and cargo handling), and the other two phases of the inverter are connected to two AC motors (for traveling and cargo handling) via two contacts of the contactor.

When a cargo handling operation is performed during traveling (or a travel operation is performed during cargo handling), the cargo handling operation is prioritized when the traveling speed command signal is small, and the cargo handling operation is not accepted when the traveling speed command signal is large. , When the traveling speed command signal is in the middle, as the traveling speed command signal increases,
The time required for the cargo handling operation is gradually reduced.

Although the inverter has three phases and the contactor is capable of switching two contacts, a combination of a four-phase inverter and a contactor capable of switching one contact may be used.

The magnitude of the traveling speed command signal determines the switching of the contactor and the operation of the inverter, and the switching of the contactor and the operation of the inverter are changed by monitoring the magnitude of the traveling speed command signal.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings.

FIG. 1 shows a control block diagram.

Connect the breaker 2 from the battery 1,
The switching element Q is connected to the (+) power line 3 and the (-) power line 4.
The inverter 5 composed of 1 to Q6 is connected.

The inverter 5 is a three-phase inverter, which connects the traveling motor 8 and the cargo handling motor 10 from the first phase through the current sensor 6, and the contact 12 of the contactor 11 from the second phase.
Connected to the traveling motor 8 and the cargo handling motor 10 via
From the third phase, the current sensor 7 and the contact 13 of the contactor 11 are connected in series to the traveling motor 8 and the cargo handling motor 10. The traveling motor 8 has a tachometer 9 for detecting the rotation speed.

The (+) power supply line 3 is connected to the multi-power supply circuit 17 for driving the switching element used in the inverter from the constant voltage circuit 16 via the key switch 15.

Further, from the constant voltage circuit 16, terminals b, a, of a control power supply circuit 19 to which a circuit element composed of a three-terminal regulator 18, a resistor R2 and a zener diode Z2 is connected.
Power is supplied from the (-) power supply line 4 to the detection circuit 21 for the current sensor. Also, the terminal a of the control power supply circuit 19,
(-) The power of the control circuit 20 is supplied from the power line 4.

A start switch 22 and a speed command 23 are used to command the speed of the traveling motor 8. To command the speed of the cargo handling motor 10, the start switch 24,
There is a speed command 25.

FIG. 2 is a circuit diagram including the control circuit of FIG.

The output of the detection circuit 21 for the current sensor 6,
The output of the detection circuit 21-1 of the current sensor 7 needs to be detected by the microcomputer circuit 27.

In order to detect the (+) and (-) currents of the alternating current flowing through the motor, from the power supply voltage of the microcomputer circuit 27 (voltage between the terminal a and the (-) power supply line 4 in FIG. 1). It is made small and the zero current of the alternating current is approximately 1/2 of the power supply voltage of the microcomputer circuit 27 so that the (+) current and the (−) current of the alternating current flowing in the motor can be detected.

That is, the output voltage of the detection circuit 21 and the detection circuit 21-1 of the current sensor 7 is set to the resistances R3, R4 and R.
Divide by 8 and R9 and connect to the microcomputer circuit 27.

The pulse signal of the tachometer 9 is connected to the microcomputer circuit 27 via the resistor R7.

The output circuit 28 amplifies a signal for turning on / off the switching element of the inverter 5 by the amplifying element 29 and applies the amplified signal to the gate drive circuit 30 so that the signal can drive the switching element. The disable terminal of the amplifying element 29 is connected to the microcomputer circuit 27 via the resistor R20, and is used to cut off the signal of the gate drive circuit 30 when the start switch 22 is not operating.

The transistor T1 is connected to the contactor 11
Connected to the coil 14. When the transistor T1 becomes conductive, the contact 12 and the contact 13 of the contactor 11 are switched.

FIG. 3 shows the ratio of the operation cycle 1 of the contactor to the time for connecting to the cargo handling motor according to the magnitude of the (traveling) speed command signal.

FIG. 4 shows the operation and suspension of the cargo handling motor when the speed command signal changes with time.

FIG. 5 shows a flowchart of the control block diagram shown in FIG.

The symbols of the flowchart are shown on the left side, and the contents are shown on the right side.

When the vehicle is traveling during the cargo handling operation, the traveling motor is driven first, and when the cargo handling operation is performed during traveling, the cargo handling motor is driven first. {() Is shown. X1, Y1 time}.

The reason why the inverter is operated after the time Z1, Z2 has passed from the switching of the energization of the coil 14 of the contactor 11 is that the operation of the contact is delayed.

The inverter and contactor circuit described above can also be used for running and charging control. This is shown in FIG.

The charging changeover switch 31 is turned on / off, and the transformer 32 is connected to the inverter.

If the current command 33 is provided and the maximum value of the input current is controlled, it can be set so that the contract current is not exceeded when charging at home. By changing the current command to increase the charging current when the current used at home is low at night, charging can be faster.

FIG. 7 shows another control circuit according to the present invention.

The inverter 5-1 has four arms.

The first arm is the traveling motor 8 and the second arm is the traveling motor 8 and the cargo handling motor 10. The third arm is the cargo handling motor 8 and the cargo handling motor 10 via the contact 12-1 of the contactor 11-1. The motor 10 and the fourth arm are connected to the cargo handling motor 10.

The operation of the traveling motor 8 and the cargo handling motor 10 is switched by switching the contact 12-1 without energizing the third arm, that is, the coil 14-1 of the contactor 11-1. When driving the traveling motor 8, the first, second,
Turn on the switching element that constitutes the third arm.
When the cargo handling motor 10 is turned off and driven, the switching elements forming the second, third, and fourth arms are turned on and off.

Contactor 11 or contactor 11-
No. 1 can be made small because only current is passed (not cut off).

[0040]

The number of expensive switching elements used in the inverter can be reduced, and an inexpensive drive device can be provided.

[Brief description of drawings]

FIG. 1 is a control circuit diagram according to the present invention.

FIG. 2 is the control circuit of FIG.

FIG. 3 is a characteristic diagram of a speed command signal and an operation ratio.

FIG. 4 is a characteristic diagram of changes in speed command and operation of a cargo handling motor.

5 is a flowchart of the control shown in FIG.

FIG. 6 is a circuit diagram when used as a charger.

FIG. 7 is another control circuit diagram according to the present invention.

[Explanation of symbols]

1 ... Battery, 5 ... Inverter, 8 ... Traveling motor, 1
0 ... cargo handling motor, 11 ... contactor, 27 ... microcomputer circuit.

Claims (1)

[Claims] 1. A battery, an inverter, a traveling and cargo-handling AC motor, a selection contactor for driving a traveling / cargo-handling motor, a speed control command signal circuit for traveling / cargo handling, and a signal from a signal circuit as input to the inverter or the above selection. In a motor control device consisting of a microcomputer circuit that determines the operation of the contactor, the magnitude of the travel command signal of the speed control command signal circuit for travel / cargo handling is input and the on-operation and on-time repetitive operation of the selected contactor is changed. A motor drive device for an electric vehicle, which has control software.