Intelligent motor protector and protection method thereof

Abstract

The invention relates to the field of power electronics, in particular to an intelligent motor protector and a protection method thereof. The intelligent motor protector is composed of an input port, a signal and power supply processing unit, a central processing unit, a power control output unit, an output port and a human-computer interaction unit. The signal and power supply processing unit comprises a current signal processing circuit, a voltage signal processing circuit and a power supply module. The central processing unit comprises an analog-to-digital converter, a microprocessor and a storage, wherein a failure protection control signal and electricity-shaking restarting signal output end of the microprocessor is connected onto the output port through the power control output unit. The motor protection method includes steps of voltage and current sampling input, overcurrent and short circuit protection, overload protection, overvoltage protection and electricity-shaking restarting protection. The intelligent motor protector is high in reliability, fast and flexible to control, enables motor protection to reliably act in failure states such as overcurrent, over load and pressure loss of a motor, and can automatically recover operation in the power grid electricity-shaking state.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a motor protection device and a protection method for a low-voltage three-phase asynchronous motor control system. Background technique [0002] Traditional motor protection devices rely on air switches, fuses, and thermal relays as protection components. Among them, the air switch and fuse are used for motor short circuit protection, and the thermal relay is used for motor overload protection. Although the air switch can quickly cut off the short-circuit current, its current judgment ability is not very accurate, and leapfrog tripping accidents often occur, which expands the scope of the accident. The fuse can easily cause the motor to be damaged due to phase-open operation, so it is not an ideal protection component. The thermal relay has single function, low sensitivity, large error and poor stability. All these defects will cause unreliable motor protection, and easily dam...

AI Technical Summary

Problems solved by technology

Although this type of technology can realize overcurrent and phase loss protection, it cannot provide protection against instantaneous fluctuations in three-phase voltage, that is, power grid swaying

Because, when the grid voltage fluctuates instantaneously and the power supply voltage is too low, the AC contactor will trip due to the loss of voltage in the coil, and the motor will suddenly stop running, which will bring economic losses to continuous production enterprises, and even cause safety accidents in the enterprise

In addition, digital logic circuits also have the disadvantages of complex circuit structure, susceptibility to interference, and poor reliability.

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