Zero-crossing pulse counting open-phase detection circuit

Abstract

A zero-crossing pulse counting open-phase detection circuit is characterized in that a three-phase power supply is connected to a conversion module, the conversion module is connected to a counting end of a counting module through an optocoupler, the counting end is respectively connected to a charging resistor and a base electrode of a PNP triode, the other end of the charging resistor is connected to an emitting electrode of the PNP triode, and the emitting electrode of the PNP triode is further connected with a grid electrode of a field effect transistor and is grounded through a charging capacitor. The charging end of the charging capacitor is also connected with the emitting electrode of the PNP triode, and the charging time constant of the charging capacitor and the charging resistor is larger than or equal to 20 ms. The three-phase half-sine wave of the optocoupler is output to the charging capacitor for charging, the charging capacitor can be fully charged only when the counting end outputs three half-sine waves within a period of 20 ms, and the charging capacitor is discharged and the alarm module is triggered if an open-phase fault occurs, the open-phase current of the counting end crosses zero and the charging period cannot reach a charging time constant. At the moment, even if the three-phase motor causes interference voltage, enough charging current cannot be formed, so that the possibility that the induction voltage interferes with the detection module is prevented, and the accuracy of open-phase detection is improved.

Description

technical field [0001] The invention belongs to the technical field of circuit phase loss detection, and in particular relates to a zero-crossing pulse counting phase loss detection circuit. Background technique [0002] The lack of phase state of the three-phase circuit system is one of the common faults. The phenomenon is that one of the three phases cannot work, resulting in abnormal conditions such as vibration, weak rotation, or loud noise of the motor. If there is no protection device, it is easy to cause the motor, Controllers and other devices were burned. When monitoring the lack of phase fault, the existing technology often uses the optocoupler device in the three-phase phase loss detection circuit for real-time voltage detection. For example, in the case of a three-phase motor with a phase loss, the motor will continue to run for a period of time. During this process, the continuous operation of the motor will be equivalent to the function of a generator and gene...

AI Technical Summary

Problems solved by technology

[0002] The lack of phase state of the three-phase circuit system is one of the common faults. The phenomenon is that one of the three phases cannot work, resulting in abnormal conditions such as vibration, weak rotation, or loud noise of the motor. If there is no protection device, it is easy to cause the motor, The controller and other devices were burned

When monitoring the lack of phase fault, the existing technology often uses the optocoupler device in the three-phase phase loss detection circuit for real-time voltage detection. For example, in the case of a three-phase motor with a phase loss, the motor will continue to run for a period of time. During this process, the continuous operation of the motor will be equivalent to the function of a generator and generate an induced electromotive force for the phase loss winding, resulting in The open-phase winding generates electricity and outputs voltage by itself, which interferes with the voltage detection circuit and causes false alarm accidents

Accidents of device burnout caused by the missing defect of the three-phase phase-loss voltage detection module emerge in endlessly. Therefore, a new technical solution is needed to solve the problem.

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