JPS61135395A - Self-diagnosing circuit of motor drive circuit - Google Patents

Abstract

PURPOSE:To effectively prevent a motor from abnormally heating by detecting a defect and an erroneous operation by a microprocessor to interrupt a power source supply. CONSTITUTION:A motor is overheated by a defect and an erroneous operation of rotation in case that, even if a motor stop signal is output to a transistor 11 by a microprocessor 14, an emitter and a collector become a shortcircuited state due to the defect of the transistor 11, a current is flowed to a motor winding 13 connected with the transistor 11 and the state of a signal line fed through a diode 12 provided at the junction of the transistor 11 and the motor winding 12 is low level. This state is read in the microprocessor 14 and output to the transistor 11, and the logic calculation with the state is executed, a stop signal is newly output from the result to the transistor 11 and a breaking circuit 15 to discover the defect and to prevent the overheat.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a self-diagnosis circuit for a motor drive circuit, which is widely used in general industry and is used to quickly detect abnormalities such as motor overheating and burnout. It is something.

(Constitution of Conventional Example and its Problems) Phenomena caused by failure or malfunction of the motor drive circuit include overheating and burnout of the motor.

This affects not only the motor alone, but also the entire device in which it is installed. One way to prevent this is to use a temperature sensor embedded inside the motor. A diagram of this circuit configuration is shown in FIG.

In the figure, 1 is a motor drive transistor, 2 is a motor winding, 3 is a cutoff circuit, and 4 is a temperature sensor. In this system, when a temperature sensor 4 detects abnormal heat generation of the motor reaches a certain temperature, a cutoff circuit 3 cuts off the current.

However, this configuration has the disadvantage that it takes time and effort to assemble the motor, resulting in high costs, and that accurate detection cannot be achieved due to the accuracy or failure of the temperature sensor.

Next, a method for detecting overheating of the motor without using the temperature sensor 4 is shown in FIG.

In the figure, a current detection resistor 5 and a current detection circuit 6 inserted in series with the motor winding 2 detect the current, and compare and determine the magnitude of the current value other than when waiting for startup.

This method detects abnormal heat generation in the motor and prevents it using the cutoff circuit 3. This method is often used for closed loop control, etc., but it has the disadvantage of increasing costs because it requires a current detection circuit.

(Objective of the Invention) The object of the present invention is to eliminate the conventional drawbacks, eliminate the need to provide a detection element inside the motor, and provide a very simple detection circuit.
It is an object of the present invention to provide a circuit that reliably prevents abnormal heat generation of a motor.

(Structure of the Invention) A self-diagnosis circuit for a motor drive circuit of the present invention includes a motor drive transistor, a motor winding connected to the collector of this transistor, and a diode connected to a junction between the transistor and the motor winding. The motor is equipped with a signal line leading to the microprocessor via the microprocessor, and a cutoff circuit that cuts off the power supply to the motor windings based on the signal from the microprocessor.

(Explanation of Examples) An embodiment of the present invention will be described based on FIG.

In the figure, 11 is a motor drive transistor, 12
13 is a diode, 13 is a motor winding, 14 is a microprocessor, and 15 is a cutoff circuit, showing n-phase components.

The operation of this embodiment configured as described above will be explained by taking one phase as an example.

The motor overheats due to circuit failure or malfunction, even though the microprocessor 14 outputs a motor stop signal to the transistor 11.

Due to the failure of the transistor 11, the emitter and collector parts become short-circuited, current flows through the motor winding 13 connected to the transistor 11, and a signal passes through the diode 12 provided at the junction between the transistor 11 and the motor winding 13. This is the case when the line status is low level. diode 1
This state is read into the microprocessor 14 through the signal line via 2, performs a theoretical calculation with the state output to the transistor 11, and based on the result, outputs a new stop signal to the transistor 11 and the cutoff circuit 15. death,
Detect failures and prevent overheating.

The signal from the signal line connected to the collector of the transistor 11 is processed on the program of the microprocessor 14, but the read timing is always monitored at regular intervals using interrupts on the program, etc.
The status check can be performed reliably in a very short time.

In this embodiment, the motor drive transistor 11 uses a PNP type, but it may also be an NPN type.
Further, there is no problem in the circuit configuration even if an inverting circuit is used in the portion of the diode 12.

(Effects of the Invention) According to the present invention, there is no need to provide a detection element inside the motor, and by directly using the signals of the motor drive element, a circuit can be constructed easily and at low cost, and therefore reliability can be improved. It has great practical effects, such as increased performance.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an abnormal heat generation detection circuit for a motor using a conventional temperature sensor, Fig. 2 is a block diagram of an abnormal heat generation detection circuit for a motor using the same detection resistor, and Fig. 3 is an embodiment of the present invention. FIG. 3 is a self-diagnosis circuit diagram of a motor drive circuit. 1.11...Motor drive transistor, 2,1
3... Motor winding, 3,15... Breaking circuit, 4.
...Temperature sensor, 5...Current detection resistor, 6...
Current detection circuit, 12... diode, 14... microprocessor. Patent applicant Matsushita Electric Industrial Co., Ltd. Figure 1 Figure 2 Figure 3 ■ n Rejected

Claims (1)

[Claims] A motor drive transistor, a motor winding connected to the collector of the transistor, a signal line leading to the microprocessor via a diode connected to the junction of the transistor and the motor winding, and a signal from the microprocessor. A self-diagnosis circuit for a motor drive circuit, comprising: a cutoff circuit that cuts off power supply to the motor windings.