JP2500898B2 - Inspection method for abnormality of drive unit of polyphase induction motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for controlling the rotation speed of an induction motor, and more particularly to a multi-phase induction motor capable of itself inspecting whether the drive device normally operates. The present invention relates to a drive device abnormality inspection method.

[0002]

2. Description of the Related Art Among the methods of controlling the rotation speed of an induction motor, one of the most frequently used methods recently is the inverter method, that is, the rotation speed of the motor is controlled by converting the frequency of the input AC. There is a method to do.

In such an inverter drive system, pulse width modulation (PWM) is used.
Modulation method converts a direct current power source into an alternating current power source having a constant frequency and applies it to the induction motor.

In a drive device of such a system, parts, particularly a relatively expensive power transistor, may be damaged by overcurrent. As a method to prevent this in advance, one that controls the power transistors etc. so that they do not operate together, or one that automatically turns off the transistors when the current value flowing in the power transistors exceeds a certain value, etc. There is.

FIG. 4 is a basic circuit diagram of a general inverter drive device. As shown in FIG. 4, the conventional inverter drive device for an induction motor is usually a DC power supply BAT.
1 are connected to three pairs of power transistors Q1 to Q6, diodes D1 to D6 are connected between the emitter and collector terminals of each transistor, and a drive signal U1 is connected to each base terminal. , U
1; V1, V1; W1, W1 are applied.

The connection points of the emitter terminals of the transistors Q1, Q3 and Q5 and the collector terminals of the transistors Q2, Q4 and Q6 are connected to the respective phase windings of the three-phase induction motor M1.

A current detection resistor R1 is further connected to the DC power supply BAT1.

In the device having the above-mentioned structure, the drive signals U1, U1; V1, V1; W1, W1 for each phase
Is applied to the base of the corresponding transistor, the corresponding transistor is turned on, whereby voltages having different phases are applied to the phase winding of the induction motor M1, and the motor is rotated. Come to do.

However, since the transistors forming each transistor pair are connected in series at both ends of the power supply BAT1, the DC power supply BAT1 is disconnected when there is time to turn on these transistors together. This causes the excessive current to flow, which causes the transistor to be damaged.

FIGS. 5A and 5B are waveform diagrams showing the drive signals of the transistors in the inverter drive device.

As shown in FIGS. 5 (A) and 5 (B), in order to solve the above problems, one transistor, for example, the transistor Q1 is changed from an on state to an off state and then kept constant. After the delay time td has passed, another transistor, for example, the transistor Q2 is controlled to operate.

[0012]

However, in the above-described driving method, the overcurrent prevention circuit operates when the transistor drive circuit for driving each transistor has an abnormality at regular time intervals. When it does not operate normally, there is a problem that the transistors and the like are inevitably damaged. In addition, there is a problem in that a fire may occur due to overcurrent.

Therefore, an object of the present invention is to break expensive parts by automatically checking whether the time delay and current detection operations are normally performed in the induction motor driven by the inverter system. Another object of the present invention is to provide an abnormality inspection method for a drive device of a multi-phase induction motor, which is capable of preventing such problems and ensuring safety such as fire prevention.

[0014]

In order to achieve the above-mentioned object, a method for inspecting the presence / absence of an abnormality in a drive unit of a polyphase induction motor according to the present invention comprises a microprocessor for controlling the overall operation of the drive unit and a multiphase induction. A motor, a pair of power transistors connected to each phase winding of a multi-phase induction motor, a transistor drive circuit that drives a transistor according to a pulse signal output from a microprocessor, and a voltage corresponding to a current flowing through the transistor as a reference. The multi-phase induction motor has different phases in each phase winding by providing a current detection unit that outputs a result of the comparison with a voltage to a microprocessor and makes the on / off times of the transistors different. In the drive device of the inverter type multi-phase induction motor that applies voltage, the operation command is input. To determine whether or not to drive the transistor by sequentially outputting pulse signals that do not overlap each other in time to the transistor drive circuit when a driving command is input, and a comparison signal from the current detection unit. At the input stage and when the high level maintenance time of the comparison signal is equal to or longer than a certain time value, it is determined that there is an abnormality in the drive circuit and the operation of the electric motor is not started. When the high level maintenance time is less than a certain time value, it is judged that the drive circuit is in a normal state and the operation of the electric motor is started, whereby the transistor drive circuit is in a normal state before the operation is started. Check if there is.

In addition, before starting the operation of the electric motor, a step of turning on / off one of the transistors to intermittently supply a current to one phase winding of the electric motor, and a current detection unit operating from the start point of turning on the transistor. And the step of counting the time value until the stop, and comparing the counted time value with a preset time value etc., and when they match each other, it is determined that the current detection unit is in a normal state. The operation of the electric motor is started, and on the other hand, when they do not coincide with each other, a step of judging that the current detection unit is in an abnormal state and stopping the operation of the electric motor is further provided. Inspect whether the detector is in a normal state.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for inspecting an abnormality of a driving device for a polyphase induction motor according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an overall circuit diagram of an inverter drive device to which the abnormality presence / absence inspection method of the present invention is applied.

As shown in FIG. 1, a driving device for a multi-phase (hereinafter, referred to as three-phase) induction motor drive device inputs a microprocessor 1 for controlling the operation of the entire system and an operation command. Key input unit 2, power supply unit 3, peripheral circuit unit 4, and display unit 5 for displaying the operating state
And power transistors Q11 to Q16 and diodes D11 to D1 for applying the DC power supply BAT11 to the respective phase windings of the electric motor 7 with mutually different phases.
6, a motor drive unit 6 including a transistor drive unit 6, a transistor drive unit 8 for controlling ON / OFF of the transistors Q11 to Q16 of the electric mechanism drive unit 6, a power supply unit 9 for supplying power to the transistor drive unit 8, and the DC power supply. It is composed of an instantaneous current detection unit 10 that detects an instantaneous current by a voltage across a resistor R11 connected in series with a BAT11.

In the inverter drive device thus constructed, when a drive command is input from the key input unit 2 to the microprocessor 1, the transistor drive unit 8 operates under the control of the microprocessor 1 and the amplified PWM is generated. Drive signals U1, U1; V1, V1; W1, W1 are output and P
Transistors Q11 to Q16 of the motor drive unit 6 based on the WM drive signals U1, U1; V1, V1; W1, W1
Is turned on, the DC power supply BAT11 is applied to the three-phase induction motor 7 with three-phase AC currents of U-phase, V-phase and W-phase,
The three-phase induction motor 7 is driven.

Further, in response to the driving of the three-phase induction motor 7, a voltage difference is generated across the resistor R11, and the instantaneous current detector 1
At 0, it is compared to a constant reference voltage.

The instantaneous current detector 10 outputs the result of such comparison to the microprocessor 1, and the microprocessor 1 outputs a PWM drive signal to the transistor driver 8 according to such a comparison signal. . That is, if it is determined that an overcurrent flows here, a low-level PWM drive signal is output and the operation of the electric motor 7 is stopped.

2 (A) to 2 (C) are waveform charts for explaining the method for inspecting the abnormality of the drive unit for the electric motor 7 according to the present invention, and FIG. 3 shows the electric motor drive unit according to the present invention. It is the flowchart which showed the abnormality presence inspection method.

As shown in FIG. 3, in the abnormality checking method of the present invention, first, in step 11, the key input unit 2 is operated.
It is determined whether a driving command for the electric motor 7 has been input through.

If a driving command is input, it is checked whether the transistor driver 8 normally performs the time delay td operation through steps 11 to 17 without immediately driving the electric motor 7. .

That is, PWs that do not mutually overlap in time
The M drive signal is sequentially output to the transistor drive circuit 8 to sequentially drive the transistors Q11 to Q17.

In this way, each U phase, V phase,
For the W phase, it is checked whether the transistors Q11 to Q16 operate while maintaining the predetermined time delay td.

At this time, whether or not the normal operation is possible is determined by the width of time during which the instantaneous current detector 10 outputs a high level signal.

That is, if the time at which the instantaneous time current detector 10 outputs the high level signal becomes longer than the set time value, the microprocessor 1 determines that the drive circuit 8 is abnormal and operates the electric motor 7. Will not start.

Next, it is judged in step 20 whether the instantaneous current detector 10 operates normally.

As shown in FIG. 2, one transistor, for example, the base terminal of the transistor Q12 is connected to the base terminal of FIG.
When a drive pulse as shown in (A) is applied, a current will flow through one phase winding of the electric motor 7, for example, a U-phase winding, and both ends of the resistor R11 are shown in FIG. 2 (B). As described above, the voltage that linearly increases with the passage of time is displayed, but the instantaneous current detection unit 10 changes the voltage across the resistor R11 to a value higher than the reference voltage VS as shown in FIG. A high level signal as shown is output to the microprocessor 1.

Therefore, the time value and the like from the ON start point of the transistor Q12 to the momentary current detecting section 10 operating and stopping are counted, and the time value and the like thus counted are preset in the microprocessor 1. By comparing with the value or the like, it is possible to determine whether the instantaneous current detection unit 10 is in a normal state.

That is, if the counted value and the preset time value match, the instantaneous current detector 10 determines that the current is normal, and starts the operation of the electric motor 7. On the other hand, if they do not match, The instantaneous current detection unit 10 determines that it is in an abnormal state and does not start the operation of the electric motor 7.

Further, the drive circuit 8 and the instantaneous current detector 10
Is in an abnormal state, an alarm or the like is given through the display unit 5 so that the user can know the abnormal state.

[0034]

As described above, according to the method for inspecting a drive unit abnormality of a multi-phase induction motor of the present invention, the drive unit is automatically inspected for abnormality before starting each operation. Prevents expensive parts from being damaged, and
It is possible to prevent a safety accident such as a fire.

[Brief description of drawings]

FIG. 1 is an overall circuit diagram of an inverter type multi-phase induction motor driving device to which an abnormality checking method of the present invention is applied.

FIG. 2 is a waveform diagram for explaining an abnormality presence / absence inspection method based on the present invention.

FIG. 3 is a flowchart showing an abnormality presence / absence inspection method according to the present invention.

FIG. 4 is a basic circuit diagram of a drive device for a conventional multi-phase induction motor.

FIG. 5 is a waveform diagram showing a PWM drive signal of a drive device for a multi-phase induction motor.

[Explanation of symbols]

 1 Microprocessor 2 Key input part 3, 9 Power supply part 4 Peripheral circuit part 5 Display part 6 Electric motor drive part 7 Electric motor 8 Transistor drive circuit 10 Instantaneous current detection part Q11-Q16 Current transistor

Claims (3)

(57) [Claims] 1. A microprocessor for controlling the overall operation of a drive device, a polyphase induction motor, and a pair of power transistors connected to each phase winding of the polyphase induction motor,
A transistor drive circuit for driving a transistor according to a pulse signal output in the microprocessor; and a current detection unit for comparing a voltage corresponding to a current flowing through the transistor with a reference voltage and outputting the result to the microprocessor. In the drive device of the inverter type multi-phase induction motor that applies voltages having different phases to each phase winding of the multi-phase induction motor by changing the on / off times of the transistors, the operation command is input. Whether the driving command is input, sequentially outputting control pulse signals that do not overlap each other in time to the transistor drive circuit to drive the transistor, and the current detection unit Receiving the input of the comparison signal from the When the time is equal to or more than a certain time value, it is determined that there is an abnormality in the drive circuit and the operation of the electric motor is not started, and when the high level maintenance time of the comparison signal is less than the certain time value, the drive circuit is And a step of starting the operation of the electric motor after determining that the electric motor is in a normal state. 2. A step of turning on / off one of the transistors to intermittently supply a current to one phase winding of the motor before starting the operation of the motor, and the current from an on-start point of the transistor. The step of counting the time value until the detection section operates and stops, and the counted time value is compared with a preset time value, and when they match each other, the current detection section is in a normal state. And starting the operation of the electric motor, and deciding that the current detection unit is in an abnormal state when the electric currents do not coincide with each other, and stopping the operation. A method for inspecting whether or not there is an abnormality in the driving device of the multi-phase induction motor described. 3. The multi-phase induction device according to claim 1, further comprising a step of issuing an alarm when it is determined that the drive circuit and the current detection unit are in an abnormal state. Inspection method for abnormality of drive unit of electric motor.