Power-saving circuit for contactor

Abstract

A power-saving circuit for a contactor includes a coil drive circuit, and further includes a rectification and filtering circuit, a PFC circuit, an auxiliary power supply circuit, and a square wave generation circuit. The square wave generation circuit outputs a first square wave signal to the PFC circuit via a first output end according to a set timing sequence, and outputs a second square wave signal and a third square wave signal to the coil drive circuit via a second output end, so as to respectively control duty cycles of a first switch tube in the PFC circuit and a second switch tube in the coil drive circuit. The auxiliary power supply circuit supplies electric energy to the square wave generation circuit during a holding stage of the contactor. The rectification and filtering circuit is used for rectifying an input AC into a pulsating DC, and filtering an input narrow-pulse current into a smooth current to be outputted to the PFC circuit after eliminating higher harmonic components other than a fundamental frequency component of 50 Hz. The PFC circuit receives rectified and filtered electric energy, enables an effective value of the input current to change along with an input voltage, and outputs the input current to the coil drive circuit and the auxiliary power supply circuit. The coil drive circuit is used for controlling the current of a contactor coil. Wherein during a pull-in stage of the contactor, the PFC circuit does not work and the power-saving circuit provides a large current to the contactor coil to pull in; during a transition stage, the PFC circuit starts to work and the power-saving circuit controls the current of the contactor coil to decrease gradually; and during a holding stage of the contactor, the PFC circuit keeps working and the power-saving circuit controls the current of the contactor coil to be kept as a small current required for holding.