Overcurrent protective device for DC brush motor

Abstract

The present invention discloses a DC brush motor overcurrent protection device, which consists of a micro controller, a bridge drive circuit and an executive circuit. The pulse width modulation output port of the micro controller is communicated with the pulse width modulation receiving port of the bridge drive circuit; the output signal control port of the bridge drive circuit is connected with the executive circuit; the bottom end of the executive circuit connects a current sampling resistor R5 to the ground and a pressure detection point is formed by the connecting point of the executive circuit and the current sampling resistor R5; one line of a pressure signal of the pressure detection point is connected with the input terminal of a hysteresis comparator and the other line of the pressure signal is connected with the input terminal of a proportional amplifier; the output terminal of the hysteresis comparator is connected with DIS terminal of the bridge drive circuit; the output terminal of the proportional amplifier is connected with the analog-digital conversion sampling port of the micro controller. The DC brush motor overcurrent protection device introduces software to detect the current of a main circuit on the basis of hardware protection and sets up relevant parameters of the software so as to achieve effective and reasonable protection of an electronic power tube and a motor when the circuit is in overcurrent.

Description

technical field [0001] The invention relates to a motor overcurrent protection technology, in particular to an overcurrent protection device for a DC brushed motor. Background technique [0002] In the application field of overcurrent protection of brushed DC motor control circuit, it is common practice to connect one or several parallel power resistors in series between the source of the switching tube of the lower bridge arm of the executive circuit and the ground, and the resistance value depends on the current from several milliohms ranging from a few euros. The voltage signal is taken from the connection between the resistor and the source of the switch tube and then processed and sent to the microcontroller or other hardware circuits. When it is detected that the voltage signal at this point is higher than a certain set value, the control circuit responds to the set action to implement circuit overcurrent protection. . Under normal circumstances, this detection signa...

AI Technical Summary

Problems solved by technology

But there is such a shortcoming in the hardware circuit: it can only simply judge whether the overcurrent

However, the current detection resistor of this circuit is connected to the power supply terminal. If the power supply voltage fluctuates frequently and the fluctuation range is large, it will cause false output of the alarm level.

Moreover, this overcurrent protection only has the hardware protection function. When the motor is blocked or under heavy load, the current impact-rapid drop-the phenomenon of frequent start and stop of the impact for a long time, this phenomenon is likely to cause the power switch tube and the motor permanent damage to

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