JPH09205792A - Motor control device - Google Patents

Abstract

(57) [PROBLEMS] To provide a highly efficient motor control device that reduces losses of a motor, an inverter and a converter. SOLUTION: An output switching circuit 6 is provided, a control signal of a motor control circuit is output from one output port, and the control signal is distributed to a converter control circuit 7 and an inverter control circuit 8 by the switching circuit 6, and an inverter circuit 3 is provided. A motor drive device that controls the converter circuit 2 and the motor 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device that combines a power supply device that rectifies an AC power supply and outputs a desired DC voltage and at the same time improves the power factor of the AC power supply, and a motor control device that controls a motor.

[0002]

2. Description of the Related Art Conventionally, in a rectifier circuit for rectifying an AC power source and converting it into a DC power source, a power source circuit for suppressing harmonics of a power source current is combined with a motor drive circuit to provide a motor control device for controlling the speed of a motor. There is a method described in Kaihei 6-105563. This method consists of a power factor correction converter circuit that uses a boost chopper circuit that simultaneously controls the power supply current harmonics and DC voltage control, and an inverter circuit that drives the motor.The DC voltage can be improved when the load is low. The speed of the motor is controlled by using the PAM control in which the speed of the motor is controlled by the PWM control by the inverter circuit and the speed is controlled by the DC voltage control by the converter when the load is high.

[0003]

In the above-mentioned conventional method, the speed control of the motor is performed by two types, that is, the inverter control and the DC voltage control. Therefore, it is necessary to output plural kinds of different outputs, at least two ports for outputting control signals are required, and no consideration has been given to the case where only one output port can be used.

It is an object of the present invention to provide a motor drive device in which a switching circuit is attached to the output of one PWM output port and an inverter circuit and a converter circuit are controlled using one phase of the PWM output to control the motor. .

[0005]

In order to achieve the above object, the present invention controls a DC voltage by utilizing a rectifying circuit and a smoothing circuit for converting an AC power supply into a DC, and an energy storage effect by a switching operation and an inductance. A converter circuit comprising a chopper circuit for performing, an inverter circuit connected to the output of the converter circuit, and a converter control circuit for controlling the switching operation of the chopper circuit,
An inverter control circuit that controls a switching operation of the inverter circuit to drive a motor, a motor control device that includes a motor control circuit and a motor that controls the converter control circuit and the inverter circuit by a control signal, and an output switching circuit, A control signal of the motor control circuit is output from one output port, and the control signal is distributed to the converter control circuit and the inverter control circuit in the switching circuit to control the inverter circuit and the converter circuit.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a converter circuit 2 which uses a rectifier circuit and a step-up chopper circuit to control the waveform shaping of an input current and the magnitude of a DC voltage, and an inverter circuit 3 which converts a DC voltage into an AC power supply of a desired voltage. A motor control device including a control circuit (one-chip microcomputer) 5 for controlling the brushless DC motor 4 according to a speed command, and a switching circuit 6 for outputting a signal output from the microcomputer to the converter circuit 2 and the inverter circuit 3. FIG.

The AC power supply 1 is connected to the converter circuit 2, and is output as a DC voltage through a rectifier circuit in the converter circuit 2 and a boost chopper circuit composed of a reactor, a diode, and a transistor. The step-up chopper circuit in the converter circuit 2 is connected to the output side of the rectifier circuit in the converter circuit 2, and by turning on the transistor, a current is caused to flow in the reactor to accumulate energy, and then the transistor is turned off to turn off the input current. Is forced to flow to the DC side to boost the DC voltage. The boosted DC voltage is supplied to the smoothing capacitor and outputs a stable DC voltage. This step-up chopper circuit improves the power factor by controlling the on / off time ratio of the transistor in a sinusoidal manner, and further can control the DC voltage.

The inverter circuit 3 to which the brushless motor 4 is connected is connected to the smoothing capacitor of the converter circuit 2, pulse-width-modulates the DC voltage supplied from the smoothing capacitor, and AC voltage of arbitrary amplitude and frequency is again obtained. The voltage is converted and supplied to the brushless motor 4 to drive the motor.

The one-chip microcomputer 5 outputs a converter start / stop signal to the converter control circuit 7 according to a condition to drive / stop the converter. Also, PW
From the M output port 505, the duty ratio signal output to the inverter control circuit 8 and the corrected DC voltage value output to the converter control circuit 7 are switched and output depending on the condition, and the motor is adjusted so that the rotation speed matches the speed command value. To control. The one-chip microcomputer 5 will be described with reference to FIG.

FIG. 2 shows the configuration of the one-chip microcomputer 5. The one-chip microcomputer 5 calculates a DC voltage command value from a speed detection unit 501 that performs position detection and speed detection, a speed control unit 502 that calculates a duty ratio signal of an inverter, and a duty ratio signal of a speed control circuit 502. Further, a DC voltage control unit 503 for calculating a corrected DC voltage from the DC voltage and the DC voltage command value, which of the inverter duty ratio signal and the corrected DC voltage value is calculated from the speed deviation, the inverter duty ratio signal and the corrected DC voltage value. A switching determination unit 504 that determines whether to output from the PWM output port, and a PWM output port 505 that outputs either the duty ratio signal or the corrected DC voltage signal as a PWM signal according to the result of the switching determination unit.

The speed detector 501 calculates the magnetic pole position from the induced voltage of the brushless motor 4, and the inverter control circuit 8
The position signal is output to. In addition, speed calculation is performed from the calculated position signal and the speed detection value is output to the speed control unit 502.

The speed control unit 502 calculates a flow rate command value from the speed detection value from the speed detection unit 501 and a speed command from the outside so that the speed deviation becomes zero, and outputs the flow rate signal to the inverter control circuit. Output to 8.

The DC voltage controller 503 is a speed controller 502.
Of the DC voltage of the smoothing capacitor of the converter circuit 2 is detected, the DC voltage command value is increased or decreased by a predetermined width from the value of the DC signal, and the DC voltage value and the DC voltage command value are detected. Then, a corrected DC voltage value is calculated from this and output to the PWM output port 505.

The switching determination unit 504 determines which of the inverter duty ratio signal and the corrected DC voltage value is to be output from the PWM output port based on the speed deviation, the inverter duty ratio signal, and the corrected DC voltage value, and outputs the PWM output. The port 505 outputs an inverter duty ratio signal from the speed control unit 502 when the duty ratio is less than 100%, and outputs a corrected DC voltage value from the DC voltage control unit 503 when the duty ratio is 100%.

In FIG. 1, the switching circuit 6 distributes and outputs the control signal output from the PWM output port 505 of the one-chip microcomputer 5 to the inverter control circuit 8 or the converter control circuit 7 according to the result of the switching determination section. .

The switching process of the switching circuit 6 will be described. First, the case where the inverter conduction ratio calculated by the one-chip microcomputer is 100% or less will be described. When the inverter duty ratio is 100% or less, the inverter duty ratio signal is output from the PWM output port 505 to the switching circuit 6. The switching circuit 6 outputs the inverter duty ratio signal to the inverter control circuit 8 and switches the DC voltage value of the smoothing capacitor of the converter circuit 2 to the converter control circuit 7.

Next, when the inverter duty ratio is 100% or more, the corrected DC voltage value Ed 'calculated by the one-chip microcomputer 5 is output from the PWM output port 505 to the switching circuit 6. The switching circuit 6 uses the corrected DC voltage value E
The d'is output to the converter control circuit 7, and the inverter control circuit 8 is switched to output the maximum duty ratio signal. As a result, the flow rate can be maintained at 100%.

The converter control circuit 7 drives and stops the converter operation by the start / stop signal from the one-chip microcomputer, drives the transistors in the converter circuit 2 based on the command value output from the switching circuit 6, and converts the converter operation. Control the input current of the circuit 2 in a sine wave,
The DC voltage is controlled at the same time as the power factor of the power supply is improved. The converter start / stop signal is the one-chip microcomputer 5
When the input power calculated from the voltage and current detection values is equal to or higher than a predetermined value (for example, 350 W), a converter start signal is output to the converter control circuit to start converter control. Outputs a converter stop signal and stops converter control. By having hysteresis in this way, the converter can be stably driven.

The inverter control circuit 8 includes a speed detector 501.
A drive signal is created based on the position detection signal from the drive circuit and the duty ratio signal from the switching circuit, the transistor of the inverter circuit 3 is driven, and the speed of the brushless motor 4 is controlled.

FIG. 3 is a flow chart showing an embodiment of the speed control process executed by the one-chip microcomputer shown in FIG.
The procedure for creating the DC voltage command value is shown. Process 511
Then, the speed deviation is calculated from the speed command given from the outside of the one-chip microcomputer and the speed detection value, and in step 512, the inverter conduction ratio is calculated so that the speed deviation becomes 0. It is judged whether the rate is 100% or more. 10
When it exceeds 0%, the routine proceeds to step 514, where it is determined whether the motor is accelerating, and when it is accelerating, the DC voltage command value Ed * is increased by 1 V at step 516, and the routine proceeds to step 519. If it is not accelerating, the DC voltage command value Ed * is used as it is for processing 5
Correction is made at 19.

When the inverter duty ratio is less than 100%, it is determined in step 515 whether the motor is decelerating. If it is in deceleration, the DC voltage command value Ed * is reduced by approximately 1 V in step 518, and the process proceeds to step 519. If the vehicle is not decelerating, the DC voltage command value Ed * is used as it is for correction in step 519.

In step 519, the corrected DC voltage value Ed 'is calculated from the DC voltage command value Ed * and the DC voltage value Ed, and in step 520 the corrected DC voltage value Ed' is output to the converter control circuit 8.

Here, although the DC voltage value is corrected, in the converter control circuit 7, the reference voltage Vr corresponding to the DC voltage command value is a fixed value, and the setting of the DC voltage changes the voltage division ratio of the detection resistor. Therefore, it is difficult to change the DC voltage according to the DC voltage command value created according to the rotation speed of the motor. Therefore, the microcomputer corrected the DC voltage value according to the DC voltage command value and then output it to the converter control circuit. This correction is set so that when the DC voltage value matches the DC voltage command value, a value equal to the reference voltage value Vr (1.55 V) inside the converter control circuit is output. As a result, the DC voltage can be controlled according to the DC voltage command value.

As described above, since the DC voltage control is performed by a method of increasing / decreasing the DC voltage command value Ed * from the duty ratio command value by a predetermined width, it is possible to perform the DC voltage control at a low load and a high load as in the conventional case. Speed control can be easily performed without performing two types of speed control. The DC voltage command value Ed * has an upper limit value and a lower limit value, and the maximum DC voltage command value is 3
The minimum DC voltage command value is set to 50V and 150V, and PWM control is performed below 150V.

The motor control operation will be described with reference to FIG. FIG.
Is a graph in which the horizontal axis represents the number of revolutions, the vertical axis represents the DC voltage, and the duty factor of the inverter, and is a diagram showing the DC voltage and duty factor with respect to the number of revolutions when the load is constant.

At low rotations such as when the motor is started, PWM control is performed at the conduction ratio calculated by the speed calculation unit, and the minimum voltage command value (DC voltage command value 150V) is output to the converter circuit. Here, when the input power is 350 W or more,
The one-chip microcomputer outputs a converter start signal to the converter control circuit to drive the converter. When the rotation speed is increased, the DC voltage is low in the controlled DC voltage state, so the conduction ratio reaches 100%, and it becomes impossible to further increase the rotation speed of the motor. Then, it is judged from the speed deviation whether acceleration or deceleration is in progress,
During acceleration and when the inverter duty ratio is 100%, the DC voltage command value Ed * is increased by 1V, and the corrected DC voltage value Ed 'is output from the PWM output port. The switching circuit 6 outputs the corrected DC voltage value Ed 'to the converter control circuit, and switches the signal to the inverter control circuit so as to output a conduction ratio of 100%. Then, the DC voltage increases, and the conduction ratio command value becomes 100% or less. Further, when the rotation speed of the motor is increased, the flow rate command value becomes 100%, and during acceleration, the DC voltage command value Ed * is increased. The DC voltage increases until it reaches 350 V, and the upper limit value is set so that it will not be output any more. By repeating the above operation, the DC voltage is increased as the number of revolutions increases, the conduction ratio is kept at 100%, and the motor speed can be controlled.

Next, the case where the motor is decelerated will be described.

If the number of rotations of the motor is reduced by a deceleration command while the motor is rotating at a high rotation speed, the flow rate of the inverter calculated by the one-chip microcomputer decreases to 100%.
Less than. Then, it is determined from the speed deviation whether the vehicle is accelerating or decelerating. If the vehicle is decelerating, the DC voltage command value Ed * is lowered by approximately 1V. The switching circuit 6 is
The corrected DC voltage value Ed 'which is lowered by about 1 V is output to the converter control circuit, and the converter circuit lowers the DC voltage. Then, the conduction ratio of the inverter increases to a value close to 100%. In addition, the flow rate of the inverter is reduced to 100
When it becomes less than%, the above operation is repeated until the DC voltage becomes 150V. When the DC voltage becomes 150 V, the switching circuit outputs the inverter duty ratio signal to the inverter control circuit, switches the DC voltage lower limit value to the converter control circuit, and starts PWM control. Also,
When the input power becomes 300 W or less, the one-chip microcomputer outputs a converter stop signal to the converter control circuit to stop the converter. By repeating the above operation, the conduction ratio can be always maintained at 100%, and the DC voltage can be maintained close to the voltage required by the motor.

In this control method, the DC voltage command value is calculated from the duty ratio, and the switching circuit can output the duty ratio signal of the inverter and the corrected DC voltage signal to the inverter control circuit and the converter control circuit. Therefore, it is possible to control the inverter circuit and the converter circuit using one PWM output port to control the motor.

[0031]

According to the present invention, two control signals can be output by attaching a switching circuit to one output port,
It is possible to control the motor by controlling the inverter circuit and converter circuit using a microcomputer with few output ports.

In addition, PWM can be performed with a simple speed control circuit.
It is possible to output a signal and a DC voltage control signal, control the speed of the motor, reduce the loss of the motor, the inverter and the converter, and drive the motor efficiently.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a motor control device according to a first embodiment of the present invention.

FIG. 2 is an internal block diagram of the one-chip microcomputer according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a speed control process according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of the operation of the motor control device according to the first embodiment of the present invention.

[Explanation of Codes] 1 ... AC power supply, 2 ... Converter circuit, 3 ... Inverter circuit, 4 ... Motor, 5 ... One-chip microcomputer, 6 ... Switching circuit, 7 ... Converter control circuit, 8 ... Inverter control circuit, 501 ... Speed Detection unit, 502 ... Speed control unit, 50
3 ... DC voltage control unit, 504 ... Switching determination unit, 505
… PWM output port.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Tahara 7-1, 1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Makoto Ishii Oita-machi, Shimotsuga-gun, Tochigi Prefecture 800 Tomita Address, Tochigi Headquarters, Hitachi, Ltd. (72) Inventor Yuhachi Takakura 800 Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Prefecture Tochigi Headquarters, Hitachi, Ltd.

Claims (4)

[Claims] 1. A converter circuit comprising a rectifier circuit and a smoothing circuit for converting an AC power supply into a direct current, a chopper circuit for controlling a DC voltage by utilizing an energy storage effect by a switching operation and an inductance, and an output of the converter circuit. An inverter circuit connected to, a converter control circuit for controlling the switching operation of the chopper circuit,
An output switching circuit in a motor drive device including an inverter control circuit that controls a switching operation of the inverter circuit to drive a motor, a motor control circuit that controls the converter control circuit and the inverter control circuit by a control signal, and a motor. The control signal of the motor control circuit is output from one output port, the control signal is distributed to the converter control circuit and the inverter control circuit by the switching circuit, and the inverter circuit and the converter circuit are controlled. Then, the motor control device is characterized in that the motor is controlled. 2. The motor control device according to claim 1, further comprising a DC voltage control unit for increasing or decreasing the control signal of the converter control circuit by a predetermined value when the control signal of the inverter control circuit reaches a predetermined value. 3. The converter control circuit according to claim 1, wherein when the input power is a predetermined value or more, a converter start signal is output to the converter control circuit to drive the converter, and when the input power is a predetermined value or less, the converter control circuit. A motor control device having a converter operation determination circuit that outputs a converter stop signal to the converter and stops the converter. 4. The motor control device according to claim 3, wherein a hysteresis is provided at a predetermined value of the input power.