Carrier frequency conversion control method

Abstract

The invention relates to a carrier frequency conversion control method, belonging to the field of power supply technologies. According to the method, the carrier frequency conversion control is realized through the following cycle steps of: storing a mutual restraint relationship table of predetermined current deviation values and carrier frequencies; finding a nearest predetermined current deviation value from the relationship table according to an actually-measured current deviation value, and selecting a carrier frequency corresponding to the predetermined current deviation value; and generating a PWM (Pulse Width Modulation) signal according to the selected carrier frequency, and outputting the PWM signal to a switching device which controls a DC-AC (Direct Current to Alternating Current) inverter so as to enable the actual value of the output current to be close to a target value of the output current. The carrier frequency conversion control method has the remarkable advantages of high response speed, low switching loss, easiness in filter design, and the like.

Description

Technical field [0001] The invention relates to a control method of power supply quality of a power grid, in particular to a carrier frequency conversion control method, belonging to the technical field of power supply. Background technique [0002] The photovoltaic grid-connected system is essentially a parallel operation system of a constant voltage source and a variable current source. [0003] In order not to affect the power supply quality of the power grid, the operating characteristics of the power grid access equipment must be controlled. For power generation equipment, it is necessary to control the output AC current and the grid voltage to be consistent in frequency and phase. At present, the grid-connected current control strategies commonly used are SPWM and hysteresis control. [0004] SPWM control: The command current is compared with the real-time value of the grid-connected current. The current error is processed by the PI regulator and compared with the triangular ...

AI Technical Summary

Problems solved by technology

However, since the width of the hysteresis loop is fixed, and the switching frequency of the power device changes with the change of the instantaneous value of the current, it brings difficulties to the design of the output filter. The filter parameters can only be designed according to the lowest harmonic frequency, which will inevitably reduce the efficiency of the inverter. Output Power Quality

[0006] In short, the existing technology has the problems of slow response speed, poor real-time performance (SPWM control), or high switching loss, unstable frequency, and difficult filter design (current hysteresis control).

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