基于PWM的拖车电磁制动器控制系统设计与仿真

Design and simulation of the electromagnetic brake control system based on PWM technique for semi-trailer

采用电磁制动器的拖车,制动时拖车制动需要与主车制动相互协调。为了有效合理地控制电磁制动器所需的制动力大小,设计了适合拖车电磁制动器的控制系统。通过脉宽调制(PWM)信号来控制加到电磁体上固定工作频率工作电压的脉宽宽度,从而控制制动力的大小,PWM信号由驾驶员制动激励信号与主车减速信号共同控制,产生一个匹配的制动力,实现主、拖车同步有效地制动。此外,当电磁体因磨损等原因产生局部短路或全部短路时,流过电磁体电流超过预定值,控制器会使PWM信号脉宽减小直至消失,从而保护硬件电路不因过流而烧毁。仿真结果表明,所设计的系统达到了电磁制动器制动控制的要求。

The electromagnetic brake of semitrailer needs a mutual coordination of the maincar brake. To effectively control the required brake force, a control system is designed to match the e lectromagnetic brake. Based on Pulse Width Modulation （PWM） technique, the designed system of the electromagnet controls the pulse width of working voltage with the constant working frequency. PWM signal is determined by the brake excitation and maincar deceleration to calculate the matc hing bake force in order to brake synchronously the maincar and trailer. In addition, when the local or overall shortcircuit is created by the electromagnet wearing and the current of electromagnet ex ceeds the predetermined value, the designed circuit decreases the circuit from overloading. The simulating results show the designed of electromagnetic brake. pulse width to zero to protect the system can meet the requirement