JPS61214781A - Regenerative energy discharging circuit of motor - Google Patents

Abstract

PURPOSE:To protect various parts of a motor controller by shortcircuiting a DC power source by an emergency stop when a current amount flowed to a discharge resistor might exceed the allowable power of the resistor, thereby preventing the excess power consumption of the resistor. CONSTITUTION:The current amount flowed to a discharge resistor 3 is monitored by a discharge circuit error detector 9, and if it might exceed the allowable power, a motor is set to an emergency stopping state to protect the resistor 3 against damage or a heat. At this time, the energization of a relay is interrupted on the basis of the detection output, relay contacts 8a-8c are broken, a contact 8d is made, thereby momentarily interrupting 3-phase AC power source input, and a DC power source stored in a capacitor 2 is also momentarily consumed by the resistor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a regenerative energy discharge circuit for a motor such as a servo motor drive amplifier, which has a discharge circuit that also has a discharge function when the power is turned off.

[Prior Art] Figure 2 is a circuit diagram showing a conventional regenerative energy discharge circuit. In the figure, (1) is a diode stack that rectifies the AC power source that is the drive source of the motor, and (2) is a smoothing capacitor. , (3) is the discharge resistance.

(4) is a discharge power transistor, (5) is a DC power supply monitoring circuit, and (6) is a power transistor. 1141 (7) (the illustrated motor is a DC motor), in which a three-phase AC power source is rectified to direct and vt by a diode stack (1), and is rectified by a smoothing capacitor (2) to the motor. A driving DC power source is formed. Using this DC power supply, a motor control circuit (6) drives a motor (7) using a PWM method or the like.

Thus, the electric motor a (7) becomes a generator during deceleration, etc., and returns regenerated energy to the DC power source. However, at this time, the voltage between the terminals of the capacitor (2) increases, and this voltage increase of the DC power supply
), which is undesirable as it causes an overvoltage to the components of the motor control circuit (8).

At this point, this DC power supply voltage is observed by the DC power supply monitoring circuit (5), and while the voltage exceeds a certain level, a discharge command is output and the discharge power transistor (4) is switched to resist the discharge resistance. A current is passed through the resistor (3) to consume the regenerated energy and lower the voltage.
4) and a DC power supply monitoring circuit (5) constitute a discharge circuit that prevents a rise in the DC power supply voltage.

[Problems to be solved by the invention] However, since the conventional discharge circuit is configured as described above, if one circuit malfunctions, current continues to flow through the discharge resistor (3) or heat is generated due to use exceeding the capacity. There were some problems, such as the grilling could be cut.

Further, the conventional DC power source for driving a motor has a long time constant of voltage drop during an emergency stop, and there is a risk that an overcurrent will flow for a long time when a power transistor is short-circuited by 1-'F.

This invention was made in order to solve the problems mentioned in 1. It is possible to detect and prevent malfunction of the discharge circuit, and also to use a discharge resistor to drive the motor in a short time during an emergency stop. This allows the DC power supply to be short-circuited.

[Means for Solving the Problems] The discharge circuit according to the present invention has the advantage that "itt" flowing through the discharge resistor
The weight is monitored, and if there is a possibility that the amount of current exceeds the allowable power of the discharge resistor, an emergency stop is performed and the DC power supply is short-circuited. At the same time, during an emergency stop, the DC power supply can be short-circuited in a short time using the discharge resistor. This is how it was done.

[Function 1] The discharge circuit according to the present invention can prevent excessive power consumption of the discharge resistor, and can short-circuit the DC power supply in a short time during an emergency stop, thereby protecting various parts of the motor control circuit.

[″χ Example] Hereinafter, an example of the present invention will be explained with reference to the drawings.
In the figure, (1) to (5) are the same as the conventional device, and (
9) is a discharge circuit malfunction detection circuit, and (8a) to (8d) are relay contacts that operate based on the detection output of the false detection circuit (9). In the illustrated configuration, the control circuit (8) and the electric motor 41! of FIG. (?) is omitted.

In conventional discharge circuits, current may continue to flow through the discharge resistor (3) due to short circuits in the DC power supply monitoring circuit (5), its output circuit, and the discharge power transistor (4), and the operation of the discharge circuit may be affected. Even if the current is normal, the flowing current (() may exceed the allowable power. Therefore, in the embodiment of the present invention, the amount of current flowing through the discharge resistor (3) is monitored by the discharge circuit malfunction detection circuit (9). If there is a risk of exceeding the allowable power, put the motor in an emergency stop state and turn off the resistor (3).
Protect against destruction, heat generation, etc.

Also, at this time, the excitation of the relay is cut off based on the detection output,
Relay contacts (8a), (8b), and (8c) break, and at the same time, contact (8d) closes, causing the 3-phase AC power supply to instantly disappear, and the DC power stored in the capacitor (2) to drain as well. Since it is instantly consumed by the discharge resistor (3), the motor (7) can be safely stopped even if any malfunction occurs in the components inside the motor control circuit (6). .

[Effects of the Invention] As described above, according to the present invention, malfunctions of the discharge circuit can be prevented and safety is greatly increased. At the same time, selecting a discharge resistor with a relatively small capacity iJ makes it possible to reduce the cost of the device. There is a certain effect.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a discharge circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional discharge circuit. In the figure, (1) is a diode stack, (2) is a smoothing capacitor, (3) is a discharge resistor, (4) is a power transistor for discharge, (6) is a control circuit, (7) is a motor, (8a) to (8d) is the relay contact, (8) is the discharge circuit malfunction detection circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A three-phase AC power source is rectified by a diode stack and converted into a DC power source via a smoothing capacitor. A control circuit controls the supply of drive power to the motor, and also switches a power transistor that forms a series body with a discharge resistor connected in parallel with the smoothing capacitor. A discharge circuit malfunction detection circuit that detects when a current flowing through the discharge resistor exceeds a predetermined value in a regenerative energy discharge circuit for a motor that controls and consumes regenerated energy from the motor by a discharge resistor. A regenerative energy discharge circuit for a motor, comprising: a relay contact that opens a connection between the three-phase AC power source and the diode stack and shorts the power transistor based on the detection signal.