Master-slave parallel inverter output current sharing control method

Abstract

The invention discloses a master-slave parallel inverter output current-sharing control method in the field of inverter parallel control, and the method comprises the steps: carrying out the detectionof an output current fundamental wave and each harmonic wave through an inverter host, and sharing the output current fundamental wave and each harmonic wave to an inverter slave in real time througha high-speed CAN communication bus; enabling the inverter slave to receive output current information shared by the inverter host, synthesizing the output current information into reference current,and enabling the output current to track the reference current in a static error-free manner through current closed-loop PI control, so the current-sharing control of current fundamental waves and harmonic waves of each order is realized. According to the invention, the calculation amount is small, the calculation precision is high, the real-time performance is good, and when a large-capacity nonlinear load is suddenly input into the output end, fundamental waves and harmonic waves of each order can also realize dynamic current sharing; and the control framework is simple, is not influenced bythe difference between the output impedance of the inverters and the line impedance, can realize hot plug and the access or quit of one or more inverters in practical application, and does not influence the operation of the control system.

Description

technical field [0001] The invention relates to the field of inverter parallel control, in particular to a master-slave parallel inverter output current equalization control method. Background technique [0002] The continuous increase of various electrical equipment leads to higher and higher requirements for the capacity and reliability of the power supply method. The AC power supply method of a single inverter can no longer meet the requirements, and the parallel connection technology of inverters is required. In order to make full use of the capacity of the parallel system and maximize the reliability of the parallel system, it is necessary to achieve current sharing among the inverters, so the parallel connection of inverters requires corresponding current sharing control. [0003] Compared with the parallel connection of DC power supplies, the parallel connection of inverters needs to consider the consistency of parameters such as output voltage amplitude, frequency, p...

AI Technical Summary

Problems solved by technology

[0004] The problems in the above inverter parallel control method are: ① There is only one centralized control unit for centralized control. If the control unit fails, the entire inverter parallel system will be in a state of collapse, and redundancy and hot swap cannot be realized, so it is reliable The sensitivity is very low, and this control method is rarely used

②The reliability of master-slave control is heavily dependent on the host, once the host has a problem and stops working, the entire method may be forced to shut down

③The common defect of decentralized logic control and droop control is: the power adjustment method is adopted, so the adjustment lags behind a fundamental wave cycle, and the dynamic performance is poor; the control target is the amplitude and frequency of the reference voltage, that is, at the expense of the inverter amplitude and frequency accuracy to achieve current sharing, which affects the power quality of the output voltage

The disadvantages are that the control method is relatively complicated, the amount of software calculation is large, and the code execution time is long, which seriously restricts the improvement of the system control bandwidth and affects the waveform quality of the output voltage; in addition, the control method should be carried out according to the actual number of inverters running in parallel. Current average value calculation, once one or more inverters are connected or withdrawn, it will affect the current average value control, so hot swapping cannot be realized

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