A remote digital control soft starter for AC power supply and its control method

Abstract

The invention discloses a remote numerically controlled soft starter for an AC power supply, which comprises a zero-crossing detection circuit, a control circuit, and a power switch circuit. The input end of the zero-crossing detection circuit is connected with the phase line input and the neutral line input of the AC power supply, and is used to detect the zero point position of the AC sine wave voltage on the phase line input of the AC power supply, and convert the detected zero point position to the zero-crossing detection pulse signal form is sent to the control circuit. The control circuit is connected with the power switch circuit, and is used to start timing according to the rising edge of the zero-crossing detection pulse signal from the zero-crossing detection circuit when the external enable signal is in the enabled state, and when the timing reaches the timing value, the timing is sent to the power switch. The circuit outputs the silicon controlled rectifier turn-on pulse, and the count value gradually decreases, so that the voltage output by the power switch circuit gradually increases. When the timing value decreases to 0, the control circuit continuously outputs a high-level signal to the power switch circuit, so that the power switch circuit is in a continuous open state, and the soft start process is completed.

Description

technical field [0001] The invention belongs to the field of single-phase or three-phase AC power supply, and more specifically relates to a remote numerically controlled soft starter for AC power supply and a control method thereof. Background technique [0002] Usually, single-phase or three-phase AC power is connected to the load through the power switch. When the power switch is turned on, the instantaneous current injected into the load is usually much greater than the steady-state operating current, that is, a surge current is generated. The surge current will not only make the Damage to AC switches, fuses, EMI filters, etc. will also cause interference to the grid power supply, triggering the power protection equipment to turn on, resulting in power outages, or interfering with the normal operation of other equipment. At the moment when the power is turned on, the inrush current generated by the load exceeds the normal operating current by dozens of times, and the inr...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the above defects or improvement needs of the prior art, the present invention provides a remote digital control soft starter for AC power supply and its control method. The need for different soft-start times, the need for waiting time when restarting repeatedly, the inability to realize switching through remote input, the use of high-power devices lead to additional power consumption and heat dissipation problems, and the use of relays, transformers and other technical problems with large volume and limited life

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