KR19980069662A - Motor control method - Google Patents

Abstract

The control method of the present invention is such that the excessively vibrating current does not flow to the motor, and also the current flowing to the motor is not suddenly reduced.

According to the present invention, when it is necessary to drive the motor at the maximum torque, it generates a PWM signal of a fast cycle with a triangular wave whose cycle is faster than a triangle wave of a normal cycle for PWM control of the motor, and connects a bypass contact while controlling the motor to PWM. And PWM control of the motor with a fast cycle PWM signal while the bypass contact is open even when the motor is PWM controlled from the maximum torque to normal, and the PWM signal has a normal cycle again when the bypass contact is fully opened. When the motor is PWM controlled by the fast cycle PWM signal during the time when the bypass contact is completely connected from the initial stage of connecting the bypass contact by PWM control of the motor, the bypass contact is completely connected. To control the PWM back to normal without excessively vibrating current through the motor To not be reduced, the current flowing to the motor abruptly when to open the contacts for the bypass.

Description

Motor control method

The present invention relates to a control method for controlling the driving of an electric motor, and more particularly, to a control method of an electric motor for controlling the driving of an electric motor mounted on an electric vehicle.

In general, an electric vehicle includes an electric motor, and is driven by driving the electric motor with a charging power supply of a battery.

The electric vehicle does not travel at a constant speed, but should be able to adjust the traveling speed according to the driver's driving operation.

Therefore, the electric vehicle typically performs PWM (Pulse Width Modulation) control to adjust the driving speed of the electric motor.

In some cases, the electric motor provided in the electric vehicle may be driven at the maximum torque.

For example, the electric motor is driven at the maximum torque when the electric vehicle is driven in a stopped state or when climbing an inclined road.

1 is a general driving circuit diagram for controlling driving of an electric motor provided in an electric vehicle. Here, reference numeral 1 denotes a controller for controlling the driving of the motor, and a gate of the field effect transistor 2 which is a chopper switching element is connected to the PWM signal output terminal of the controller 1, and the drain and source of the field effect transistor 2 are connected. Between the bypass contacts 3 connected and opened under the control of the controller 1 are connected.

Reference numeral 4 is a battery provided in an electric vehicle, and the positive terminal of the battery is connected to the connection point of the drain of the field effect transistor 2 and one terminal of the bypass contact 3.

The connection point between the source of the field effect transistor 2 and the other terminal of the bypass contact 3 is connected and opened under the control of the field coil 5 and the armature coil 6 of the electric motor and the controller 1. Connected to the negative terminal of the battery 4 sequentially through the regenerative contact 7 to be detected, and detects a current between the field coil 5 and the armature coil 6 and inputs it to the controller 1. The current detection element 8 is provided.

When the motor is driven by the motor driving circuit of such a configuration, the controller 1 connects the regenerative contact 7 and outputs a PWM signal to the PWM signal output terminal.

The PWM signal output from the controller 1 is applied to the gate of the field effect transistor 2, and the field effect transistor 2 is brought into a conducting state and a blocking state according to the PWM signal output from the controller 1.

When the field effect transistor 2 is turned off, the charging power of the battery 4 is cut off so that it does not flow to the electric motor.

When the field effect transistor 2 is brought into a conductive state, the charging power of the battery 4 sequentially moves the field effect transistor 2, the field coil 5, the armature coil 6, and the regenerative contact 7. This flows to the negative terminal of the battery 4, the motor is driven.

In this state, current flowing through the field coil 5 and the armature coil 6 is detected by the current detecting element 8 and fed back to the controller 1.

Then, the controller 1 calculates an error value by comparing the driving value of the motor and the feedback current value, and generates a PWM signal by comparing the calculated error value with a triangular wave that generates a predetermined period.

That is, the controller 1 generates a triangular wave of a predetermined period as shown in FIG. 2A, and compares the triangular wave and the error value when an error value is calculated in which the driving value of the motor and the feedback current value are calculated. As shown in the figure, a PWM signal is generated.

The generated PWM signal is output to the PWM signal output terminal to control the field effect transistor 2, whereby the motor is driven at the set drive value.

In driving the motor as described above, when driving the motor to the maximum torque at the time t1, the controller 1 outputs a low potential to the PWM signal output terminal to turn off the field effect transistor 2, The bypass contact 3 is controlled and connected.

Then, the charging power of the battery 4 flows to the negative terminal of the battery 4 sequentially through the bypass contact 3, the field coil 5, the armature coil 6, and the regenerative contact 7. , The motor is driven at maximum torque.

However, the conventional technique described above is to connect the bypass contact 3 after making the field effect transistor 2 shut off when the motor is driven at maximum torque.

Therefore, as shown in FIG. 2C, the current flowing to the motor decreases and increases during the delay period A due to the mechanical delay time as the bypass contact 3 is connected, and the following transient period B In the), excessive current flows momentarily to the motor, and excessively vibrates. In the next normal section C, the normal current flows to the motor to drive the motor to the maximum torque.

When the current flowing in the electric motor flows while vibrating excessively in the vibration section (B), the electric motor is damaged and also affects the driving circuit that controls the driving of the electric motor. There were various problems.

In addition, when the motor is driven to the maximum torque and the PWM control is performed again, the current flowing to the motor is rapidly decreased, which causes the motor to be damaged.

Therefore, an object of the present invention is to control the electric motor to drive the motor to the maximum torque to connect the bypass contacts in the early stage of the PWM signal to control the current flowing to the motor so that the excessively oscillating current does not flow into the motor. To provide.

Another object of the present invention is to control the current flowing to the motor as a PWM signal in the early stage of the PWM control in the early stage of PWM control when driving the motor to the maximum torque again to prevent the current flowing to the motor is sharply reduced. It is to provide a control method of the motor.

The control method of the motor of the present invention for achieving this object determines whether it is necessary to drive the motor at maximum torque while PWM control.

When it is necessary to drive the motor to the maximum torque, it generates a triangular wave with a period shorter than the triangular wave with a normal period for the PWM control of the motor normally, and compares the generated triangular wave with the error value according to the current value flowing to the motor To generate a fast cycle PWM signal.

By outputting the PWM signal of the generated fast cycle, the motor is connected to the bypass contact while continuously controlling the PWM.

And when PWM control to normal again in the state of driving the motor at maximum torque, generate PWM signal of fast cycle again, and open the bypass contact while PWM control the motor, when the bypass contact is completely open The PWM signal with the normal cycle again controls the driving of the motor.

Therefore, according to the present invention, the motor is PWM controlled by the fast cycle PWM signal during the time when the bypass contact is completely connected from the beginning of connecting the bypass contact, and thus the bypass contact is completely connected. In this case, excessively vibrating current does not flow into the electric motor.

In addition, when the bypass contact is opened in order to PWM control the motor to normal again, the current flowing to the motor is not abruptly reduced.

1 is a driving circuit diagram of a general electric motor.

2A to 2C are waveform diagrams for explaining an operation of driving an electric motor by a conventional control method.

3 is a signal flow diagram illustrating a control method of the present invention.

4A to 4C are waveform diagrams for explaining an operation of driving an electric motor by the control method of the present invention.

Explanation of symbols on the main parts of the drawings

1: controller 2: field effect transistor

3: Bypass contact 4: Battery

5: field coil of electric motor 6: armature coil of electric motor

7: Regenerative contact 8: Current detecting element

Hereinafter, with reference to the accompanying drawings will be described in detail the control method of the motor of the present invention.

3 is a signal flowchart showing the operation of the controller 1 according to the control method of the present invention. As shown therein, in step S1, the controller 1 controls the field effect transistor 2 with a PWM signal in a normal period to drive the motor to normal, and in step S2 it is necessary to drive the motor to the maximum torque. Determine if there is.

If it is not necessary to drive the motor to maximum torque in step S2, the controller 1 returns to step S1 to continue driving the motor to normal.

When it is necessary to drive the motor to the maximum torque in the step S2, the controller 1 inputs the current value detected by the current detecting element 8 in step S3, and is input in step S4. Generates a PWM signal according to the current value.

That is, when the controller 1 PWM-controls the motor to normal in the normal section I as shown in FIG. 4A and drives the motor to maximum torque at time t11, the controller 1 performs a triangular wave of a fast cycle. To generate a fast cycle PWM signal as shown in FIG. 4B by comparing the generated triangular wave of the fast cycle with the current value detected by the current detection element 8, and outputting the generated fast cycle PWM signal. The switching operation of the field effect transistor 2 is controlled.

In the next step S5, the bypass contact 3 is connected.

Then, as shown in FIG. 4C, the current flowing to the motor in the delay period II from the time t11 to the time t12 at which the bypass contact 3 is completely connected is controlled by a fast cycle PWM signal. Slightly reduced.

Therefore, in the transient section III from the time t12 to the time t13 when the bypass contact 3 is completely connected, the vibration width of the current flowing to the motor is reduced, and in a short time, Inrush the motor to run at maximum torque.

After the time t12 at which the bypass contact 3 is completely connected, the generation of the PWM signal is stopped in step S6, and it is determined whether the maximum torque is continuously required in step S7.

When the maximum torque is not required in step S7, the controller 1 generates a PWM signal according to the current value of the motor detected by the current detection element 8 in step S8.

That is, when the maximum torque of the motor is not required at time t14, as shown in FIG. 4A, the current flowing through the motor is compared with the fast-period triangular wave to generate the fast cycle PWM signal shown in FIG. A fast cycle PWM signal is output to the field effect transistor 2 to control the switching operation.

Then, the bypass contact 3 is opened in step S9.

Then, the electric current flows in the motor during the delay period V in which the bypass contact 3 is opened, and in the next vibration period VI, the fast cycle PWM signal output by the controller 1. The current flowing by vibrates.

Thus, since the maximum torque of the motor is not required, the bypass contact point 3 is opened, and at a time t16 at a time t16 in a state where the current flowing to the motor vibrates by the PWM signal of a fast cycle, The output of the PWM signal is stopped, and the flow returns to step S1 to control the current flowing to the motor normally.

Then, in the normal section after the time t16, the current flowing to the motor by the PWM signal in the normal period is gradually reduced to operate normally.

As described above, the present invention connects and opens the bypass contact while controlling the current flowing to the motor by a PWM signal of a fast cycle when the motor is driven normally when the maximum torque of the motor is required or driven at the maximum torque. Therefore, the current flowing into the motor does not vibrate excessively or is excessively reduced, and thus it does not strain the motor, thereby extending its service life and controlling the operation of the motor. .

Claims (3)

The first step of determining whether the maximum torque is required while PWM control the current flowing through the motor, and the bypass contact for generating the maximum torque while continuing to PWM control the motor when the maximum torque is required in the first step A second step of connecting; a third step of determining whether the maximum torque is not required when the motor is driven at the maximum torque in the second step; and a third step of determining that the maximum torque is not required in the third step. A fourth process of opening the bypass contact while continuously controlling the flowing current, and a fifth process of continuously controlling the current flowing into the motor when the bypass contact is completed in the fourth process. Motor control method characterized in that. The control method according to claim 1, wherein the second process connects the bypass contact while PWM controlling the motor with a PWM signal of a cycle faster than a steady state. The method of claim 1, wherein the third process opens the bypass contact while PWM controlling the motor with a PWM signal of a cycle faster than the normal state, and the fifth process is normal when the opening of the bypass contact is completed. Motor control method characterized in that the PWM control by the PWM signal of the cycle.