Dual-active bridge DC converter direct power control method based on energy closed loop

Abstract

The present invention discloses a dual-active bridge DC converter direct power control method based on energy closed loop, and is suitable for the field of large-power bidirectional direct current conversion. Aiming at the dynamic response problem of a bidirectional full-bridge direct current converter, on the basis of single phase-shifting control, according to an output energy balance equation,an output voltage Uout is sampled and then squared to construct an output capacitance energy closed loop, the size of a phase-shifting angle is obtained through the direct power based on the dual-active bridge direct current converter power transmission model to generate switching control signals so as to achieve rapid regulation of the output voltage of the dual-active bridge DC converter. The method provided by the invention can effectively improve the dynamic response speed of the output voltage when a load is suddenly changed, only needs to sample the output voltage, and is low in cost, not sensitive to model parameters and easy for design and engineering implementation.

Description

technical field [0001] The invention belongs to the technical field of energy transmission of a bidirectional DC converter in electrical engineering, and in particular relates to a direct power control method for a dual active bridge DC converter based on an energy closed loop. Background technique [0002] Since the Dual Active Bridge (DAB) DC converter was proposed as an alternative to the high-power DC-DC converter, it has the advantages of electrical isolation, high power density, bidirectional flow of energy, up-down voltage conversion, and easy module The advantages of cascading are widely used in high-voltage, high-power, bidirectional DC energy conversion systems such as electric vehicles, distributed power generation, power electronic transformers, and locomotive electric traction systems. [0003] In order to adapt to the complex and changeable operating conditions in the above-mentioned industrial applications, the DAB as a DC voltage power conversion unit needs t...

AI Technical Summary

Problems solved by technology

The traditional closed-loop single phase-shift control method of output voltage based on PI regulator is difficult to meet the relevant dynamic response performance requirements. Therefore, many scholars at home and abroad have conducted extensive research on the improvement of the dynamic response speed of DAB converters.

[0004] The methods for improving the dynamic response speed of DAB can be roughly divided into three categories: the first category is to speed up the current response speed and improve the dynamic response performance by introducing current feedback or feedforward, such as the literature "Segaran D, Holmes D, Holmes G.Enhanced load step response for a bidirectional DCDC converter[J].IEEETransactions on Power Electronics,2013,28(1):371-379."("Bidirectional DCDC Converter Load Step Fast Response Method"—2013 IEEE Power Electronics Journal) The proposed method of sampling load current and introducing load current feed-forward speeds up the dynamic response speed of DAB, but increases the sampling of load current and increases the cost of the system; the second type is to establish a small signal model and The time-averaged equivalent model, which is brought into relevant parameters to directly calculate the phase shift angle, thereby controlling the output power to quickly reach a given value, speeds up the dynamic response speed of DAB, such as the Chinese invention patent "A DC-DC Converter Applied to Full-Bridge Isolation The direct power control method of "(public number: CN105141136A) proposes to obtain the power given value through the voltage outer loop PI closed loop, and complete the direct power control in combination with the power transmission model of DAB, to speed up the dynamic response performance of DAB, but the voltage outer loop PI The closed-loop output is used as the power given value, the physical meaning is not clear, which is not conducive to the parameter design of the PI regulator and the improvement of the dynamic performance in the full power range; the third category is the control method that combines the first two methods, such as the Chinese invention patent "Load Current Feedforward Control Method for Improving the Dynamic Response of Full-Bridge Isolated DC-DC Converter Output Voltage" (public number:

[0005] CN105048821B) proposes a combination of DAB power transmission model, while introducing load current feed-forward method to improve the dynamic response performance of DAB, but also increases the system cost due to current sampling

[0006] The above analysis shows that although the existing methods can effectively improve the dynamic response speed of DAB to a certain extent, they all have their own shortcomings. Therefore, it is necessary to further explore the improvement of DAB dynamic performance.

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