JPS62110401A - Control device of travelling drive source motor for electric motor car - Google Patents

Abstract

PURPOSE:To make it possible for an electric motor car to get over the gig road level or to climb up a short steep slope by increasing a maximum value of current for a specified time when the command value comes to maximum. CONSTITUTION:When a driving current from a battery 12 to a motor 10 reaches a current Imax set up by a maximum current setting circuit 32, the driving current of the motor 10 is limited to a current value Imax for some time due to the action of a current limiting circuit 30. When the delay time T1 of an on-delay timer 50 elapses from that moment (interpreting that a larger output is demanded as the accelerating pedal is being continuously pressed), the set voltage of a divider 54 is added to the maximum current setting circuit 32 for a specified period. As a result, the driving current of the motor 10 is increased to the current Ipeak, more powerful than the maximum current Imax to which is has been limited so far.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a device for controlling a motor used as a driving source for an electric vehicle.

(Background of the Invention) Regarding this type of device, Nl5SAN Service Bulletin No. 383@ (published in June 1976), introduction of 1-manufactured battery forklifts UBO2 type and CYBO2 type vehicles, etc. are known. An example of a conventional circuit is shown in the figure.

The DC series motor 10 shown in FIG. 2 is used as a driving source for the forklift, and is supplied with driving current from a battery 12.

The drive current is controlled by a chopper 16 constituted by a thyristor 14, and conduction control of the thyristor 14 is performed by a phase shifter 1B.

The phase shifter 18 is supplied with a control signal from the motor 11 control circuit 20, and the motor control circuit 20 is supplied with the output voltage of the variable resistor 22.

The amount of depression of the accelerator pedal of the lift-o-lift is detected by the variable resistor 22, and the motor control circuit 20 has a current detector 24 which detects the driving current of the motor 10.
A control signal corresponding to the difference between the output voltage of the variable resistor 22 and the output voltage of the variable resistor 22 is obtained.

As a result, the drive current supplied to the motor 10 is controlled according to the amount of depression of the accelerator pedal of the forklift.

Here, on the output side of the variable resistor 22, a current limiting circuit 30 configured as a high voltage priority circuit including diodes 26 and 28 is inserted.

The anodes of these diodes 26 and 28 are commonly connected to the input of the motor control circuit 20, the output voltage of the variable resistor 22 is connected to the cathode of the diode 26, and the upper limit current setting circuit 32 is connected to the cathode of the diode 28. The set upper limit current setting voltage is supplied.

Therefore, the output voltage of the variable resistor 22 is limited by the upper limit current setting voltage of the upper limit current setting circuit 32, and as a result, the drive current supplied from the battery 12 to the motor 10 is limited, and the motor 10 and chopper are prevented from overcurrent. 16 main circuits are protected.

However, in this conventional device, the upper limit value of the drive current of the motor 10 set by the upper limit current setting circuit 32 is set to a somewhat lower value in order to protect the motor 10 and the main circuit of the chopper 6 from heat generation due to long-term energization. Therefore, when the forklift truck climbs a short steep slope or climbs over a fairly large level difference, a problem arises in that the torque generated by the motor 10 is insufficient.

(Object of the invention) The present invention has been made in view of the above-mentioned conventional problems, and
The purpose is to create a driving drive motor for electric vehicles that can generate torque that allows electric cars to climb short, steep slopes, or overcome large steps. The purpose of this invention is to provide a control device.

(Structure of the Invention) In order to achieve the above object, the present invention includes a motor current control means for controlling a drive current supplied to a motor, which is a driving source for an electric vehicle, to a command value, and a drive current that is equal to or less than an upper limit value. The present invention is characterized by comprising: motor current limiting means for limiting the motor current; and upper limit increasing means for increasing the upper limit value over a predetermined period when the command value reaches a maximum.

(Description of Embodiments) Hereinafter, preferred embodiments of the apparatus according to the present invention will be described based on the drawings.

In FIG. 1, a battery 12 is connected to a DC series motor 10.
field (the direction of the drive current supplied to the a winding 34 is switched by the forward contactor 36 and the backward contactor 38, and thereby the direction of the torque generated in the armature 40 of the motor 10 is changed. The forklift is switched between forward and backward movement.A diode 42 is connected in parallel to the motor 10.

The drive current supplied to this motor 10 is controlled by a chopper 16 according to the output voltage of a variable resistor 22.
For this control, the output voltage of the variable resistor 22 is passed through the diode 26 of the current limiting circuit 30 to the motor control circuit 20.
subtractor 44.

This subtracter 44 subtracts the detected voltage of the current detector 24 from the output voltage of the variable resistor 22 to obtain a voltage corresponding to the difference between them, and this voltage is sent to the phase shifter 18 via an amplifier 46. It is supplied as a control signal.

Here, the output voltage of the current detector (DC current transformer) 24 is supplied to a comparator 48, and this comparator 48 detects when the drive current of the motor 10 exceeds the upper limit current set by the upper limit current setting circuit 32. A comparative signal is obtained.

The comparison signal is supplied to a one-shot timer 52 via an on-delay timer 50, and its output is supplied to a divider 54.

Roughly, in the divider 54, a preset voltage is obtained from the output of the one-shot timer 52, and the set voltage is supplied to the adder 56.

The adder 56 is supplied with the upper limit current setting voltage of the upper limit current setting circuit 32, and the set voltage and the divider 54
The added voltage with the set voltage is supplied to the cathode of the diode 28 of the current limiting circuit 30.

This embodiment has the above configuration, and its operation will be explained below.

When a forklift truck equipped with this device climbs over a large step or climbs a steep and short slope, its accelerator pedal is fully opened at time t1 in FIG. 3 (A>).

As a result, the drive current supplied from the battery 12 to the motor 10 is controlled to increase according to the characteristic 100 in FIG. ), current limit circuit 3
0, the drive current of the motor 10 is once limited to the current value Imax as shown by the characteristic 100.

At this time t2, the comparison signal of the comparator 48 rises as shown by the characteristic 102 in FIG. When this happens (it is determined that a larger output is required due to the fact that the accelerator pedal is continuously depressed), the output of the on-delay timer 50 changes at that time, as shown by characteristic 104 in FIG. 3(C). It rises at t3, and from this point on, the one-shot timer 52
The output rises over a period T2 from time t3 to time t4.

During the output rising period T2 of the one-shot timer 52, the set voltage of the divider 54 is added to the upper limit current set voltage of the upper limit current setting circuit 32 by the adder 56, and as a result, the motor 10, which had been limited to the upper limit current Imax, The drive current is increased over a period T2 to a current 1 peak greater than this.

Therefore, the torque of the motor 10 increases over the period T2, and as a result, a forklift using this as a traveling drive source can overcome large steps or climb steep and short slopes.

As explained above, according to this embodiment, when the drive current of the motor 10 reaches the limit current ■tnax by fully opening the accelerator and the predetermined period T1 has elapsed, the drive current is increased to the set value ipeak over the period T2. Therefore, motor 10
, the heat capacity limit in the main circuit of the chopper 16 is utilized as much as possible to temporarily obtain a large motor torque.

Therefore, forklifts using this as a driving source can overcome large steps or climb short steep slopes.

Incidentally, since the drive current of the motor 10 is increased by a predetermined amount and the increase is limited to the period T2, the motor 10. The main circuit of the chopper 16 will not be affected.

(Effects of the Invention) As explained above, according to the present invention, the motor drive current is temporarily increased to a current larger than the limit current during full acceleration, so the increased motor torque is used to generate electricity. It may be possible for a car to overcome large steps and even climb short steep slopes. This is extremely suitable for vehicle operation.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a preferred embodiment of the device according to the present invention, FIG. 2 is a circuit diagram showing the configuration of a conventional device, and FIG.
FIG. 3 is an explanatory diagram of the operation of the embodiment. 10... DC series motor 16... Chopper 18... Phase shifter 20... Motor control circuit 22... Variable resistor 24... Current detector 30... Current limiting circuit 32. ... Upper limit current setting circuit 48 ... Comparator 50 ... On-delay timer 52 ... One-shot timer 54 ... Divider 56 ... Adder Patent applicant Nissan Motor Co., Ltd. Agent Patent attorney Kazu 1) Figure 113

Claims (2)

[Claims] (1) Motor current control means for controlling the drive current supplied to the motor, which is the driving source for the electric vehicle, to a command value; and motor current limit means for limiting the drive current to a maximum value or less; A control device for a travel drive source motor for an electric vehicle, comprising: upper limit increasing means for increasing the upper limit value over a predetermined period when . (2) The electric vehicle according to claim 1, wherein the upper limit value increasing means increases the upper limit value over a predetermined period when the drive current reaches the upper limit value. Control device for travel drive source motor.