CONTROLLER AND CONTROL METHOD FOR ALTERNATING CURRENT CONTACTOR

摘要

A controller for an alternating current contactor. The controller comprises: a filtering and rectification circuit (101, 102), which filters and rectifies external alternating current; an electromagnet component (103), which is driven by the output of the filtering and rectification circuit and performs an attraction, holding or releasing action; a power transistor circuit (104), which is connected to the electromagnet component; and a microcontroller (112), which controls on or off of the power transistor circuit to control the electromagnet component to perform the attraction, holding or releasing action. The controller further comprises: a voltage control loop, which provides a voltage feedback signal to the microcontroller so that the microcontroller generates a control signal according to the voltage feedback signal, wherein the control signal is a PWM control signal having different duty cycles during the attraction and holding of the electromagnet component so that the current does not exceed a predetermined current threshold during the attraction and holding of the electromagnet component; and a current control loop, which provides a current feedback signal to the microcontroller so that the microcontroller turns off the power transistor circuit upon detecting an overcurrent exceeding the current threshold.