Middle-high voltage charging system control method based on series digital voltage stabilizer

Abstract

The invention provides a middle-high voltage charging system control method based on a series digital voltage stabilizer, and belongs to the field of middle-high voltage electric vehicle charging stations. An output voltage of the series digital voltage stabilizer is controlled to be matched with a high-voltage cascade H-bridge module to form multi-level alternating current modulation voltage, theswitching frequency of the high-voltage cascaded H-bridge module is reduced, meanwhile, the size and inductance loss of a grid-side filter inductor are effectively reduced, and in cooperation with voltage stabilization control of a rear-stage DC / DC isolation stage of a digital series digital voltage stabilizer, voltage stabilization and balance of all modules of the system are guaranteed, so thesystem stably operates, and meanwhile system operation efficiency is improved.

Description

technical field [0001] The invention relates to the field of medium and high voltage charging systems, in particular to a control method for a medium and high voltage charging system based on series digital voltage stabilizers. Background technique [0002] The medium and high voltage charging system adopts the input series output parallel topology scheme, which reduces the switching frequency and device withstand voltage level of a single module on the AC side, so that the AC side can be directly integrated into the medium and high voltage power grid; the low voltage is obtained through the parallel connection of the output of the subsequent DC / DC stage. The DC bus provides charging loads, avoids the use of traditional power frequency transformers, increases the controllability of the system, reduces the system volume, and effectively improves the power density of the system. It is a favorable topology for low-voltage charging systems; Under the carrier phase-shift modulati...

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Problems solved by technology

[0002] The medium and high voltage charging system adopts the input series output parallel topology scheme, which reduces the switching frequency and device withstand voltage level of a single module on the AC side, so that the AC side can be directly integrated into the medium and high voltage power grid; the low voltage is obtained through the parallel connection of the output of the subsequent DC / DC stage. The DC bus provides charging loads, avoids the use of traditional power frequency transformers, increases the controllability of the system, reduces the system volume, and effectively improves the power density of the system. It is a favorable topology for low-voltage charging systems; Under the carrier phase-shift modulation method, the AC side needs to cascade multiple module units to synthesize a multi-level medium-high voltage AC voltage that meets the requirements, especially under the condition of few modules and low switching frequency, in order to meet the grid-connected standard , a larger grid-side filter inductance is required to meet the conditions, which has a negative impact on the volume, cost and efficiency of the entire system

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