Flying capacitor voltage balance control method of 9S-5L-ANPC DAB converter

Abstract

The invention discloses a flying capacitor voltage balance control method of a 9S-5L-ANPCDAB converter, and belongs to the field of multi-level converter control. Comprising the steps that a flying capacitor is pre-charged, so that the voltage of the flying capacitor is not unbalanced; sampling a flying capacitor voltage value in real time; comparing the current sampling voltage value with a flying capacitor stable voltage expected value, if the current sampling voltage value is larger than the flying capacitor stable voltage expected value, subtracting the current delta d from the duty ratio when the alternating current side output voltage is equal to Vdc / 4 and-Vdc / 4, and if the current sampling voltage value is smaller than the current delta d, adding the current delta d to the duty ratio when the alternating current side output voltage is equal to Vdc / 4 and-Vdc / 4, and enabling the action intervals of Vdc / 4 and-Vdc / 4 to meet odd symmetry; and judging whether the sampling voltage after variable duty ratio control exceeds a flying capacitor voltage non-unbalance interval, if the sampling voltage exceeds the non-unbalance interval, negating the current delta d, and otherwise, keeping the current delta d unchanged. The duty ratios of Vdc / 4 and-Vdc / 4 are changed through variable duty ratio control, the flying capacitor voltage is controlled to be an expected value, meanwhile, the symbol of delta d is changed through hysteresis control, and it is guaranteed that a good control effect is still achieved when the circuit operation condition is changed.

Description

technical field [0001] The invention belongs to the field of multi-level DC-DC converter control, and more specifically relates to a flying span of a 9S-5L-ANPCDAB (nine switch tube five-level active neutral point clamping dual active bridge) converter Capacitive voltage balance control method. Background technique [0002] In high-voltage and high-power applications, the DAB converter adopts a multi-level topology. The Five-Level Active Neutral Point Clamp (5L-ANPC) topology reduces voltage stress and provides excellent performance in medium-voltage, high-power applications. Compared with the inverter, when the 5L-ANPC topology is used to construct the DAB converter, the 9S-5L-ANPC circuit needs to be used, and its high-voltage switching tube can realize all soft switching, so it is more suitable for high voltage levels and switching frequencies. application in the case. [0003] Patent CN113078820A provides a balance control method of flying capacitor voltage, the idea ...

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Problems solved by technology

[0004] However, this method has the following shortcomings: the judgment of the sign of Δd in this method is not accurate enough, and Δd is a given value, which remains unchanged during the dynamic adjustment process. When the system changes from one steady state to another, the given value A certain value of Δd may lead to an unbalance of accelerating flying capacitor voltage

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