Three-phase inverter output open-phase detection and protection method

Abstract

The invention discloses a three-phase inverter output open-phase detection and protection method, which comprises the following steps of S1, normal operation of an inverter: starting the inverter to enable direct current to be introduced into the inverter, converting the direct current into alternating current by the inverter, and meanwhile, presetting a current threshold value for open-phase comparison of the inverter; s2, sampling the three-phase current in real time: sampling the negative value of a lower half part of the three-phase alternating current of the inverter in real time, converting the negative value into a positive value, i.e., taking the absolute value of the three-phase alternating current, then performing low-pass filtering in real time, and converting the three-phase alternating current signal into a direct current signal; S3, judging whether the inverter is lack of phase or not; and S4, implementing inverter open-phase protection. The method is high in open-phase judgment accuracy and not prone to false alarm, meanwhile, the output open phase of any phase inverter can drive the other two phases of inverters to be cut off, a three-phase line can be cut off in time when the open phase of the output end is caused by self faults, and therefore it is guaranteed that the inverter is not damaged.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a detection and protection method for a three-phase inverter output phase loss. Background technique [0002] With the continuous development of the modernization process of society, more and more power electronic products have been applied to people's daily production and life. The inverter is an important application in the power electronics industry. Its main function is to convert direct current into alternating current. , Now widely used variable frequency power supply, inverter power supply is its application. Taking the conversion of direct current into three-phase alternating current as an example (three-phase three-wire system), shore power supply, UPS, etc. are all applications of this function. The characteristic of this kind of power supply is that its output characteristic is a voltage source and there is no N-line output. The load carried by the power sup...

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Problems solved by technology

Taking the conversion of direct current into three-phase alternating current as an example (three-phase three-wire system), shore power supply, UPS, etc. are all applications of this function. The characteristic of this kind of power supply is that its output characteristic is a voltage source and there is no N-line output. The load carried by the power supply can be a balanced load or an unbalanced load. In use, due to an abnormal connection between the power supply and the load, the output of a certain phase will be missing, which is the so-called output phase failure. The lack of phase will cause the load device to fail. If the input voltage is abnormal, it will stop working if it is mild, and it may cause damage to the equipment if it is serious. Therefore, the general power supply will have an output phase loss protection function to protect the safety of the load equipment in this case.

[0003] However, it is inconvenient to detect when the output phase of the existing three-phase inverter is lacking, and it cannot effectively protect the output phase of the three-phase inverter, which is likely to cause phase loss protection failure and low safety factor

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