Battery charging device and method with voltage sharing function based on immittance network

Abstract

The invention discloses an immittance network-based battery charging device and method with a voltage-sharing function. The immittance network-based battery charging device comprises an inverter circuit, an immittance network and a transformer which are connected in sequence, wherein the primary side of the transformer is connected with the immittance network, the secondary side of the transformer comprises two windings, one winding is connected with a rectifying circuit, the other winding is connected with the voltage-sharing circuit, and the rectifying circuit and the voltage-sharing circuit are respectively connected with the battery pack; when the voltage of each battery unit in the battery pack is balanced, the voltage-sharing circuit does not work, and each battery unit is charged by the rectifying circuit; when the SOCs of the battery units are inconsistent, the voltage-sharing module corresponding to the battery unit with the lowest voltage in the voltage-sharing circuit works, and when the SOCs of the battery units are consistent, the rectifying circuit charges the battery units. According to the device, the current source output characteristic of the immittance network is utilized, the constant-current charging and the constant-voltage charging of the battery pack are realized, a current detection link and a corresponding signal conditioning link are removed, and control is simplified.

Description

technical field [0001] The invention relates to the technical field of power electronic converters, in particular to a battery charging device and method based on a conductance network with a voltage equalizing function. Background technique [0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] At present, whether it is an electric vehicle's on-board charger or a charging pile, it can only charge the entire battery pack. When there is a voltage difference between the battery cells connected in series, the charging device can't do anything about it. [0004] In recent years, battery energy storage has been widely used in electric vehicles / hybrid vehicles, micro-grids based on new energy, etc. In order to achieve high efficiency in the battery charging / discharging process, battery cells are generally connected in series to obtain a higher The output voltage. However...

AI Technical Summary

Problems solved by technology

[0009] The prior art improves the voltage doubler topology of the symmetrical structure, which eliminates the shortcoming of frequent charging and discharging of the battery unit, but the number of diodes and the number of DC blocking capacitors are greatly increased. If the voltage of the battery unit is low (such as 2V lead-acid storage battery), the power loss on the rectifier will exceed 30% of the rated power of the charger

In the modular battery unit voltage equalizer, each battery unit is not directly connected in series, but is connected to the DC bus through a bidirectional converter, so the battery and the load are not directly connected, and the load must be supplied to the load after a bidirectional converter, and its circuit is complex high reliability and low efficiency; in addition, each battery cell module needs to communicate, which further increases the complexity of the system

Images