An OC gate current limiting circuit which breaks through the traditional way, limits the motor current directly without detection and protects the motor current directly by hardware circuit is proposed based on the traditional limiting method which monitors the motor current and then limits it for motor protection by Holtz and magnet ring. The voltage drop produced by letting the preset maximal current pass through the switch is taken as the reference voltage, and letting the real current pass through the switch is taken as the comparing voltage value. When the real current is greater than the preset maximal current and the comparing voltage is greater than the reference voltage, the OC gate circuit will shut off the signal control circuit which generates the control signal of the switch. Otherwise, when the real current is less than the preset maximal current, the switch works normally. Therefore, it can quickly limit the current to the preset maximal current when the current surges over the preset maximal current. The results show that the circuit has the characteristics of short response time, high control precision and low cost, etc.%针对传统的以霍尔加磁环对电机电流进行检测再保护的电流限制的方法,提出了OC门硬件限流电路,该电路突破了传统的思路,不对电流进行采样,直接通过硬件电路对电机电流进行限制保护,即以设定的最大电流通过开关管所产生的压降作为OC门电路的参考值,以实际电流通过开关管所产生的压降作为比较值与参考值进行比较.当实际电流大于设定的最大电流时,OC门电路的输出关闭驱动开关管的控制电路,从而关断开关管,反之,当实际电流小于最大电流时,开关管正常工作,从而实现了对过电流进行快速的限制保护,确保了保护电路中的电流不会超过设定的最大电流.应用结果表明,该电路具有响应时间短,控制精度高,成本低等特点.所以其具有较高的应用推广价值.
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