A three-level bidirectional charging and discharging circuit

Abstract

The invention relates to a charge and discharge circuit and especially relates to a three-level bidirectional charge and discharge circuit. The three-level bidirectional charge and discharge circuit comprises a power grid voltage end; a PWM rectifier comprising a first output end and a second output end, wherein a first bus capacitor and a second bus capacitor are connected in series between the first output end and the second output end; and a first charge branch, a second charge branch, a first discharge branch and a second discharge branch, wherein under a charge or discharge state, when battery voltages are higher than one half of bus voltages or lower than one half of the bus voltages, the first charge branch and the second charge branch are controllably conducted so as to adjust a balance between the bus voltages and the battery voltages. According to the invention, conduction of the charge and discharge circuit can be controllably adjusted through a control circuit, the balance between the bus voltages and the battery voltages can be adjusted, and the direction of a positive and negative bus voltage difference is controlled in a phase shift mode, more importantly, single-phase output ripples can be reduced, and an inductive current frequency multiplication function is realized.

Description

technical field [0001] The invention relates to a charging and discharging circuit, in particular to a three-level bidirectional charging and discharging circuit. Background technique [0002] The traditional two-level circuit adopts dual PWM control technology, which is composed of a PWM rectifier and an inverter, and the PWM rectifier is used to realize the bidirectional flow of energy. In addition, through the method of multi-channel parallel connection and software phase-shift control of the bus voltage, the output power of large current and low ripple can be realized. However, compared with the single-phase output ripple, this traditional two-level bidirectional charging and discharging circuit is still relatively large, and the charging and discharging voltage adjustment range is relatively small, which is not conducive to the stability of the system. Therefore, the present invention proposes a three-level bidirectional charging and discharging circuit for the above e...

AI Technical Summary

Problems solved by technology

However, compared with the single-phase output ripple, this traditional two-level bidirectional charging and discharging circuit is still relatively large, and the charging and discharging voltage adjustment range is relatively small, which is not conducive to the stability of the system.

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