A control circuit based on starting relay

Abstract

The invention discloses a control circuit based on a starting relay. The control circuit comprises the starting relay, a current limiting circuit, a rectifier circuit and a voltage control circuit. Anormally closed contact of the starting relay is electrically connected with a starting capacitor, and the current limiting circuit receives a starting voltage signal for starting the winding output of a compressor. The current limiting circuit outputs the starting voltage signal after current limiting to the rectifier circuit, and the rectifier circuit outputs the starting voltage signal after rectification to the starting relay. An energy storage circuit is further connected between the rectifier circuit and the starting relay, and the voltage control circuit is electrically connected with the energy storage circuit. The control circuit is controlled by an internal electronic circuit, can be applied to a wide voltage range, can adapt to the starting relay used in the case in which the compressor has long shutdown inertia, and can reduce energy consumption and improve product reliability.

Description

【Technical field】 [0001] The invention relates to the technical field of industrial control, in particular to a control circuit based on a starting relay. 【Background technique】 [0002] The starting relay is a special component for starting a compressor using a single-phase asynchronous motor. Its function is to switch on and off the attracting coil and holding coil circuit. In small refrigeration equipment such as refrigerators and air conditioners, refrigeration compressors mostly use single-phase split-phase asynchronous motors. The function of the starting relay is to help the motor start. After the start is completed, the auxiliary winding is automatically disconnected to avoid burning the auxiliary winding coil. . [0003] The starting relays of the existing single-phase power supply refrigeration compressors are all driven by the voltage of the auxiliary coil of the compressor, and are controlled by the principle that the voltage of the auxiliary coil is low when th...

AI Technical Summary

Problems solved by technology

The pull-in voltage of the general starter relay is AC180V to 200V, and the release voltage is AC40V to 110V. Due to the process, the accuracy is relatively poor, and it is suitable for occasions where the grid voltage fluctuation is low and the stability is relatively high.

[0004] However, due to the instability of the power grid, when the compressor is started when the voltage is relatively low, the contacts do not act because the voltage of the power grid is low and cannot reach the pull-in voltage of the start relay coil; The voltage of the starter relay coil will not drop from more than 200 volts to 0 volts at once, and the relay is often released at 80 volts, which will make the contacts of the starter relay live and act, and the above two reasons will cause damage to the starter relay

However, because the coils of the traditional starting relay are directly connected in parallel, its power consumption is also relatively large, and the product generates a relatively large amount of heat during normal use, which reduces the reliability of the starting relay.

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