High-step-down transformation ratio rectifier based on switched capacitor

Abstract

The invention discloses a high-voltage-reduction transformation ratio rectifier based on a switched capacitor. The rectifier comprises a three-phase alternating-current power supply, a filter circuit,a Delta-type connection rectifying circuit, a switched capacitor circuit and a voltage-reduction chopper circuit. Compared with a traditional three-phase rectifier, the topological structure of the invention has the advantages that the direct-current link current can be shared by more switches, so that the conduction loss is reduced, and a high-transformation-ratio voltage reduction function canbe realized at the output end.

Description

technical field [0001] The invention relates to the field of three-phase electric energy conversion, in particular to a high step-down ratio rectifier based on switched capacitors. Background technique [0002] In the basic DC-DC converter, the traditional buck circuit cannot provide a step-down effect with a large transformation ratio, which cannot meet the requirements of many modern applications. Today's integrated circuits get energy from a power supply of less than 5V. In the future, the power supply voltage of microprocessors will be reduced from 3.5V to 1V or even lower to reduce the power loss of modern high-power CPUs. To provide such a high voltage conversion ratio, the basic converter must operate at a limiting duty cycle, less than 0.1 in the step-down converter. Extreme duty cycles can hurt efficiency and hinder transient response. Also, to generate such extreme duty cycles, the control circuit must contain a very fast, expensive comparator. At high switching...

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Problems solved by technology

Extreme duty cycle hurts efficiency and hinders transient response

Also, to generate such extreme duty cycles, the control circuit must contain a very fast, expensive comparator

At high switching frequencies, extreme duty cycles can even lead to failure due to the extremely short conduction times of diodes (self-driving transistors) in boost converters or active transistors in buck converters

Using a transformer in this case will only increase cost, size and loss

In addition, a larger transformer turns ratio increases the voltage stress on the main components, severely affecting efficiency

The current of a traditional three-phase CSR DC link passes through four devices in series, resulting in high conduction loss

Although the conduction loss in the free diode state can be reduced by increasing the free diode (Df), the efficiency is not greatly improved, especially at higher modulation indices

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