Self-adaptive electromagnetic relay zero-crossing on and off control method

Abstract

The invention discloses a self-adaptive electromagnetic relay zero-crossing on and off control method, which is characterized by adapting to different on and off leads of a relay automatically regardless of harmonic waves of a voltage and vibration of the relay so as to switch on and off zero crossing. The method uses a micro controller, an alternating current power supply zero-crossing detection circuit, a relay contact end voltage tester, a load current zero-passing detector, an electromagnetic relay, a relay stabilized voltage power supply and an on and off control signal. The alternating current power supply zero-crossing detection circuit is used for voltage zero-crossing detection; the relay contact end voltage tester is used for testing the voltages at the two ends of a contact; the load current zero-passing detector is used for current zero-crossing detection; the relay stabilized voltage power supply is used for supplying power to the relay; the relay control contact is connected with a load; the on and off control signal is used for receiving an on and off command; and the controller collects all input signals, stores and computes the signals and controls the relay.

Description

technical field [0001] The invention belongs to the technical field of relay control in the field of control electrical appliances, and relates to an adaptive zero-crossing on-off control method of an electromagnetic relay. Background technique [0002] The electromagnetic relay is a mechanical electromagnetic switch. Its basic principle is that when the coil is energized, the magnetic field it generates will convert the armature from one state to another, making the contacts contact or disconnect, because it is a metal contact point, so the relay has the characteristics of very small on-resistance and very large off-resistance, and can be applied to control high-power loads. Also because the on-off of the electromagnetic relay is mechanical, when the relay is powered on, it takes a certain amount of time for the contacts to switch from one state to another, which is the action time of the relay. The time required for the contact to go from the off state to the on state is ...

AI Technical Summary

Problems solved by technology

Generally, the action time of the relay is 10-120mS, and the time of turning on and off is also different, and there are large individual differences. If it acts randomly, it may generate surge current and arc, which will cause impact on the power grid and affect the relay. life span

Therefore, it is required that the relay can be turned on when the voltage crosses zero and disconnect the load when the load current crosses zero. The control method adopted is to give the relay an early pull-in time, and to control the relay to be turned on in advance before the voltage crosses zero. , which can ensure that when the voltage crosses zero, the contacts just touch, avoiding the surge current; and when disconnecting, also give the relay an early disconnection time before the current zero crossing, and advance the disconnection time before the current zero crosses Control the disconnection of the relay, which can ensure that the contact is just disconnected when the current crosses zero, avoiding arcing; but because the individual pickup and disconnection times of the relays vary greatly, it is impossible to specify a unified time, so simply specify a time is not practical

Utility model patents ZL200920076196.7 and ZL200720042341.0 both provide an electromagnetic relay zero-crossing switch circuit, but because the two patents detect the voltage at both ends of the relay in the form of zero-crossing pulses, there are harmonics in the voltage and the relay has jitter , the real zero-crossing time of the voltage and the real contact time of the contact cannot be detected correctly, so the adaptability is not strong

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