Three-level buck convertor

Abstract

The invention relates to a three-level buck convertor, which comprises an input voltage source, a voltage division capacitor circuit, a clamping circuit, a switch transformed circuit and a output filter circuit, wherein voltage division is carried out on the input voltage source by the voltage division capacitor circuit so that the voltage loaded by each capacitor is half of the input voltage; the clamping circuit comprises two clamping diodes and a clamping capacitor, which is used for ensuring the voltage at two ends of the clamping capacitor is half of the input voltage; the switch transformed circuit and the output filter circuit are used for switching and filtering the input voltage so as to obtain relative constant output voltage. The topological structure of the three-level voltage division convertor of the invention can easily realize automatic balance of the clamping capacitor without an additional control circuit. The invention has easy circuit and strong reliability of the system.

Description

technical field [0001] The invention relates to a DC-DC converter, more specifically to a non-isolated three-level step-down converter. Background technique [0002] Due to the increasingly widespread use of portable mobile communication devices, in order to reduce the size of portable electronic products and prolong the service life of the devices, how to realize high-efficiency, high-step-down DC-DC converters has become a research focus in the field of power electronics technology, and is also a communication A hotspot of competition in power and consumer electronics. [0003] Conventional non-isolated buck converters such as figure 1 shown. The converter is composed of a power switch tube S1, a synchronous rectifier tube Q1, a filter inductor L and an output capacitor Co. The circuit structure is simple and the control is convenient. Since the voltage gain of the converter is only determined by the duty cycle of the power switch, in high step-down conversion applicat...

AI Technical Summary

Problems solved by technology

However, due to the differences in circuit parameters, including the difference between the rising edge and falling edge of the power switching device, and the delay of the driving signal, there must be a certain difference in the duty cycle of the two switching tubes.

Due to the inconsistency of the duty cycle, the charge and discharge of the clamp capacitor are different in one switching cycle, making it difficult to stabilize the voltage of the clamp capacitor at half of the input voltage.

Conventional capacitor-clamped three-level step-down converters can only ensure the voltage balance on the clamp capacitor by sampling the voltage on the clamp capacitor and adding an additional control circuit, which increases the control complexity

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