Switched capacitor type modular high-step-down-ratio direct-current power supply and control method thereof

Abstract

The invention discloses a switched capacitor type modular direct-current power supply with a high step-down ratio and a control method thereof. The power supply comprises an upper modular cascade circuit group string, a lower modular cascade circuit group string, a load and an input source. The upper modular cascade circuit group string and the lower modular cascade circuit group string respectively comprise i upper sub-module circuits and j lower sub-module circuits, and all the sub-module circuits are non-isolated three-port switched capacitor resonant circuits with input and output capacitors connected in series. The power supply is a high-step-down-ratio direct-current power supply with high-voltage direct current input and low-voltage direct current output formed through modular cascading, and the combination modes between modules comprise upper module group string cascading, lower module group string cascading and mixed cascading of the upper module group string and the lower module group string. The power supply can be flexibly expanded according to voltage and power level requirements, does not need a voltage or current detection device, and is low in cost, simple in topology, easy to control and high in flexibility. The scheme is suitable for being applied to a low-power power supply in a medium-voltage or high-voltage direct-current input occasion.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a switched capacitor type modularized high step-down ratio DC power supply and a control method thereof. Background technique [0002] For occasions where the auxiliary power supply is obtained directly from the medium-voltage DC bus, how to make the auxiliary power supply in the medium-voltage DC system realize high step-down ratio operation and high-voltage isolation in a simple, compact and low-cost way is an important issue in the medium-voltage DC system. difficult issues. [0003] The voltage level of existing commercial power semiconductor devices is limited, the highest is only 6.5kV, which cannot be directly used in medium-voltage DC systems. Therefore, power electronic converters directly connected to the medium-voltage DC side must use semiconductor device series technology, or use modular Power supply cascading technology, and solve the problem of voltage e...

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Problems solved by technology

[0009] In view of the above, in order to solve the limitation of the applicable voltage level existing in the prior art, the requirements for drive and output isolation are high, the control strategy is complicated, and the hard shutdown during Insufficient self-capacity, the present invention provides a switched capacitor type modular high-step-down ratio DC power supply, which is obtained by cascading and combining standardized sub-module circuits, and two switch tubes in each sub-module circuit are connected in series. The single switch tube bears low pressure, and the circuit topology of each sub-module is transformed from the basic series resonant circuit. The power supply can adjust the number of cascaded modules according to the input voltage level, with good flexibility and strong expandability

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