Phase-locked-loop-free direct power prediction control method for three-phase converter

Abstract

The invention discloses a phase-locked-loop-free direct power prediction control method for a three-phase converter. The method is implemented under a synchronous rotating coordinate system, and no phase-locked loop is needed. According to the fact that a control system is delayed by two beats actually, sampling frequency which is two times of carrier frequency is adopted for reducing influences on prediction accuracy of the output power and current of the next beat and simplifying prediction calculation, complex calculation is not needed, the grid connection power, grid connection current and network voltage value of the next beat can be calculated accurately, control precision is improved, and output of a three-phase converter circuit of the next carrier cycle is obtained through calculation. The control method is simple and easy, fixed-frequency phase-locked-loop-free direct power prediction of the three-phase converter can be achieved, and the method is prone to engineering.

Description

technical field [0001] The invention relates to a direct power prediction control method for a three-phase converter without a phase-locked loop, belonging to the technical field of power electronics. Background technique [0002] The three-phase DC / AC converter has the characteristics of being able to realize AC-DC bidirectional power flow, adjustable power factor, and high sine degree of grid-connected current. In recent years, with the rapid development of distributed generation, it has been widely researched and applied. Its performance It directly affects the power quality of distributed generation. Among many control methods, direct power control (direct power control, DPC) has the advantages of simple control algorithm, adjustable power factor and good dynamic performance. DPC is derived from the direct torque control (DTC) of the motor. DTC does not need to control the current. According to the sector and demand, the voltage vector is selected by the switch table to...

AI Technical Summary

Problems solved by technology

The traditional predictive control is an open-loop prediction, and the predictive control is carried out for a one-shot delay, ignoring the current sampling control cycle including the time to update the duty cycle and the delay of the next control cycle that is active, so it is difficult to accurately predict the next shot output, which in turn affects the control accuracy

[0004] DPC is realized by space vector pulse width modulation (SVPWM), which needs to phase-lock the grid voltage to obtain the grid frequency and phase angle, which increases the difficulty of control and the amount of calculation of the control system, reducing the efficiency

Images