Control method for improving light-load efficiency of DAB-type DC-DC converter

Abstract

The invention provides a control method for improving the light-load efficiency of a DAB-type DC-DC converter and belongs to the technical field of modulation of bidirectional isolation DC-DC converter power switch tubes. Switch tubes on a diagonal of a full bridge at a side generate phase shift when a driving pulse is controlled so as to output a three-level voltage waveform. A full bridge at the other side is not required to be subjected to any phase shift control. The control method comprises two control modes. In the first mode, phase shift is performed on a bridge at an input side but is not performed on a bridge at an output side. In the second mode, phase shift is performed on the bridge at the output side but is not performed on the bridge at the input side. The control method is suitable for converter small-medium power output, greatly reduces the peak value and the effective value of the current flowing through a transformer, an inductor, and a switch device, effectively decreases device stress, greatly reduces system reactive power and system loss, and improves system efficiency.

Description

technical field [0001] The invention relates to the technical field of modulation of a power switch tube of a bidirectional isolated DC-DC converter, in particular to a control method for improving the light-load efficiency of a DAB type DC-DC converter. Background technique [0002] DAB type DC-DC converter is widely used in uninterruptible power supply (UPS), clean energy conversion system and electric vehicle lithium battery charging and discharging equipment due to its high power density, soft switching characteristics, symmetrical structure, and small number of components. Its basic topology is as figure 1 As shown, the full bridge B1 on the primary side is connected to the full bridge B2 on the secondary side through a transformer T. Each full bridge is composed of 4 controllable switches and anti-parallel diodes. The transformer ensures electrical isolation. The transformation ratio of the primary side and the secondary side is n :1, L is the transformer leakage indu...

AI Technical Summary

Problems solved by technology

[0005] 1. The peak current I flowing through the transformer, inductor and switching device peak and current rms value I rms Larger, the stress on the related devices increases, and the cost of the device increases

[0006] 2. The voltage at both ends of the inductor is large, the maximum rise rate of the inductor current is large, and the external electromagnetic interference to the system increases, resulting in a decrease in system reliability

[0007] 3. Current peak I peak and current rms value I rms And the reactive power of the converter is too large, causing the system loss to increase and the system efficiency to be low

[0008] The current dual-phase-shift control method solves the above problems under the premise of ensuring power output by controlling two phase-shift angle variables, but the dual-phase-shift control method needs to control two phase-shift angle variables, which requires a large amount of calculation and complicated control methods , not easy for feedback adjustment and engineering implementation

Images