JPS5942522B2 - Motor control device for electric cars - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor control circuit that uses a bypass conductor and a chopper circuit for electricity such as a battery/freight lift, and more particularly to a motor control circuit that is provided with a circuit that controls the input of a bypass conductor.

Japanese Patent Laid-Open No. 47-44013 discloses a method of controlling a chopper circuit that uses a bypass conductor for electric vehicles.

Conventionally, with the accelerator depressed to the maximum, when the current flow rate of the chopper circuit reaches a certain specified value or more, the bypass conductor is turned on after a slight delay to short-circuit the chopper circuit and rotate the motor at full speed. method was adopted. For example, in a battery forklift, a conduction rate of about 30% is used as this specified value. This means that the minimum conduction rate when the chopper circuit is operating is 30.
%, and it is necessary to insert a bypass conductor at this time as well. However, when driving on a flat road, the current flow rate before the bypass conductor is turned on is generally small and in this state, if the bypass conductor is suddenly turned on and the motor is made to rotate at full speed, the speed changes will be large, resulting in poor drivability.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a motor control circuit that can turn on a bypass conductor without impairing drivability both when traveling on a flat road and when climbing a hill.

A feature of the present invention is that a means is provided for switching the specified value of the conduction rate when driving on a flat road and when going up a hill, so that when driving on a flat road, the bypass conductor is turned on at a specified value of the conduction rate that is higher than when driving on a hill. That's what I did.

Embodiments of the present invention will be described in detail below with reference to the drawings. 1st
In the figure, from the output power line 1 to the motor 2 and the chopper circuit 3
Connect the series circuit of (→Connect to power line 4.

A diode D1 is connected in parallel with the motor 2. The chopper circuit 3 is repeatedly turned on and off by the trigger circuit 5 whose frequency changes depending on the amount of accelerator depression, and the speed of the motor 2 is changed by changing the conduction rate (ratio of the chopper conduction time to the period). There is. A voltage adjustment circuit 6 generates a one-shot voltage from the output power line 1 and supplies it to the constant voltage line T. A diode D2 and a resistor R are connected in series from the connection point between the chopper circuit 3 and the motor 2 to the base of the transistor TR. Its emitter is connected to the power line 4, and its collector is connected to the constant voltage line 7 via a resistor R2.Resistors R3 and R4 are connected in series from the collector to the power line 4.Resistance A capacitor C1 is connected in parallel with the capacitor R4.
The connection point between the capacitor C1 and the resistors R3 and R4 is connected to the non-inverting input terminal of the operational amplifier 16 via the resistor R8. A constant voltage from constant voltage line 7 is connected to resistor R5.
, R6 is connected to the inverting input terminal of the operational amplifier 16 via a resistor R7. Resistor R7, R8, R
9 and the operational amplifier 16 constitute a comparator circuit. A resistor RlO is connected in parallel to the capacitor C1 via a switch 12. The switch 12 is closed when the vehicle is running on a flat road, and is opened when the vehicle is pitched. The output voltage of the operational amplifier 16 is also applied to the capacitor C2 via the resistor Rll.
to charge.

A voltage obtained by dividing the constant voltage from the constant voltage line 7 by resistors Rl2 and Rl3 is applied to the inverting input terminal of the operational amplifier 17 via the resistor Rl4. On the other hand, the voltage of capacitor C2 is applied to the non-inverting input terminal of operational amplifier 17 via resistor 15. A circuit composed of an operational amplifier 17 and resistors Rl4, Rl5, and Rl6 represents a comparator, whose output is connected to the base of the transistor TR2 via the resistor Rl7, its emitter is connected to the power line 4, and its collector is connected to the pie bus conductor. The accelerator full-open detection circuit 8 is a circuit that has high impedance (open) when the accelerator is fully open and low impedance (short circuit) in other states, and is connected in parallel to the collector and emitter of the transistor TRl. In the figure, it is shown as a switch.Now, when the accelerator is not fully opened and the chopper circuit 3 is non-conductive, the base current flows to the transistor TRl via the motor 2, but since the transistor TRl is short-circuited by the detection circuit 8. , the collector is at a low potential.

Next, when the accelerator is fully opened, the accelerator fully open detection circuit 8, which had short-circuited the transistor TRl, becomes high impedance (open), and the collector potential of the transistor TRl is low when the chopper circuit 3 is non-conducting, and low when it is conductive. It gets expensive. That is, the transistor TRl operates in opposite phase to the chopper circuit 3. Capacitor C1 is transistor TR
Since the capacitor C1 is charged during the non-conducting period and discharged during the conducting period, as the conduction rate of the chopper circuit 3 increases, and therefore the conduction rate of the transistor TRl decreases, the amount of charge in the capacitor C1 decreases. When the voltage at the terminal of the capacitor C increases as a result, the output potential of the operational amplifier 16 becomes high level.

Now, if you think about when he pitches, switch 12 is open.
The charging/discharging time constant of capacitor C1 is determined by resistors R2, R3, and R4.
Determined by the value of capacitor C1. Therefore, when the chopper conductivity exceeds a certain specified value determined by the charging/discharging time constant, the amount of charge in the capacitor C1 increases. Since the output voltage of the operational amplifier 16 also charges the capacitor C2 via the resistor Rll, the voltage at the non-inverting input terminal of the operational amplifier 17 becomes larger than the voltage at the inverting input terminal after a slight time delay. The output level becomes high level, transistor TR2 becomes conductive, coil 10 of pie bus conductor 9 is excited, and its contact 11 is closed. As a result, the electric motor 2 is rotated fully. When the accelerator is returned from the fully open position, the transistor TRl is short-circuited, so the capacitor C1 is discharged, and the output of the operational amplifier 16 becomes low level. The charge in the capacitor C2 is immediately discharged through the diode D3, and the transistor TR2 becomes non-conductive. Contact 11 of pie bus conductor 9 is therefore open.

As a result, the motor 2 rotates in accordance with the current flow rate of the chopper circuit 3. Next, since the switch 12 is closed when driving on a flat road, the resistor RIO is connected in parallel with the resistor R4, so the charging/discharging time constant of the capacitor C1 changes, and the chopper conductivity changes to the standard value at the time of riding. If the value is not greater than the value, capacitor C1 will not be charged, and therefore operational amplifier 16 will not be charged.
output does not reach high level.

As described above, the charging/discharging time constant can be changed by operating the switch 12, so when driving on a flat road, the pie bus conductor is turned on at a higher conduction rate than when climbing, so it is possible to change the charging/discharging time constant by operating the switch 12. The pie bus conductor is not suddenly turned on due to the speed, and drivability is improved.

Another embodiment of the invention is shown in FIG.

Portions common to FIG. 1 are omitted in FIG. Further, the same symbols as in FIG. 1 represent the same functional parts. 13 is an oscillation circuit, 14 is an on-trigger circuit, and 15 is an off-trigger circuit.

TR3 and TR4 indicate transistors. Operational amplifier 17
When the output of the transistor TR4 becomes high level and the switch 12 is closed, the transistor TR4 becomes conductive, stopping the operation of the off-trigger circuit 15 and making the chopper circuit fully conductive.

After a predetermined time determined by the time constant of resistor Rl8 and capacitor C3, transistor TR3 becomes conductive to lock oscillation circuit 13 and stop the operation of on-trigger 14.
The time constants of the resistor Rl8 and the capacitor C3 are selected so that this operation is performed within the time (approximately 50 milliseconds) from when the transistor TR2 operates until the contact 11 of the bypass conductor 9 is closed. As a result, the chopper circuit 3 first becomes fully conductive, and then the pie bus conductor becomes fully conductive, which further eliminates speed changes and further improves drivability. However, in this case, even if you release the accelerator immediately when the output level of the operational amplifier 17 changes from a low level to a high level, the
It is necessary to connect a resistor (not shown) in series with diode D3 of FIG. 1 to ensure that the 0 millisecond operational amplifier 17 continues to operate and operates the pie bus conductor.
As described above, according to the present invention, motor control with good drivability can be obtained by changing the conduction rate at which the pie bus conductor is turned on when traveling on a flat road and when climbing a hill.

Furthermore, the charging time of capacitor C1 in Fig. 1 becomes shorter as the conduction rate increases, so if this effect is utilized, the piezoelectric conductor closes quickly when the conduction rate is large, improving driveability. It also has the effect of improving the level.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of one embodiment of the present invention, and FIG. 2 is a circuit diagram of main parts of another embodiment. 2...Electric motor, 3...Chopper circuit,
5...Trigger circuit, 8...Accelerator full open detection circuit, 9...Pybus conductor, 12
...Flat road driving/mounting detection switch.

Claims (1)

[Claims] 1 A regulation in which the speed of a DC motor is controlled by a chopper circuit whose conduction rate can be changed according to the amount of accelerator depression, and a bypass contactor is provided in parallel with the chopper circuit, so that the chopper conduction rate is maintained when the accelerator is depressed to the maximum. In the motor control device for an electric vehicle, the bypass contactor is turned on to short-circuit the chopper circuit when the voltage exceeds a specified value, and the specified value changing means is configured to switch the specified value between when traveling on a flat road and when climbing a hill. A motor control device for an electric vehicle, characterized in that: