Frequency converter protection device, frequency converter and air conditioner

Abstract

The invention discloses a frequency converter protection device, a frequency converter and an air conditioner. The frequency converter protection device comprises: a first switch unit and a second switch unit; a first switching branch; a second switch branch circuit, wherein the second switch branch circuit and the first switch branch circuit are connected in parallel between the P+ end and the P- end of the bus; and a self-checking circuit, wherein the detection end of the self-checking circuit outputs a detection signal. After the frequency converter is powered on, the main controller of the frequency converter firstly controls the first switch unit, so that the first normally open contact is closed, and the bus is charged; before bus charging reaches a preset voltage value and a motor is started, controlling a second switch unit to enable a second normally open contact to be closed, enabling the motor to enter a pre-starting stage, and monitoring a detection signal at the same time; when the frequency converter is shut down normally, the motor is stopped firstly, and the relay is disconnected after the current of the relay and the voltage between the normally open contacts are reduced; and when the second coil is abnormal, the relay is disconnected after the frequency converter is shut down. The frequency converter protection device is arranged on the direct current bus side, and pull-in and reliable disconnection of the relay under small current can be achieved.

Description

technical field [0001] The invention relates to the technical field of frequency converters, in particular to a frequency converter protection device, a frequency converter and an air conditioner. Background technique [0002] Frequency converters are widely used in the air-conditioning industry. In order to improve the reliability of the frequency converter itself, the frequency converter usually has an overcurrent protection function, which is used to cut off the current of the frequency converter in a timely and reliable manner when the frequency converter needs to be protected. [0003] If it is desired to reliably disconnect the power supply line of the inverter in any state (especially in the case of high voltage and high current), there are generally two ways to cut off the current of the inverter: 1. On the input power side of the inverter Cut off the current; 2. Cut off the current at the P+ / P- of the DC bus side of the inverter. [0004] The current is cut off on ...

AI Technical Summary

Problems solved by technology

DC600V DC relays are usually very expensive, and are usually disconnected from high-voltage direct current by filling inert gas or direct oil immersion

[0006] The above two protection methods cut off the input power side current / DC bus side current by breaking the AC / DC relay and other actuators, but there is no abnormality detection function of the actuator's own control circuit, so it cannot be found in time. Protection control failure problem

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