Three-Level Switch Circuit Resonant Control for Power Conversion Loss Reduction
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Solution Overview
Problem
Existing power conversion circuits face challenges in simultaneously reducing switching loss, conduction loss, and current switching loss, as these losses often cannot be minimized concurrently.
Innovation Solution
A power conversion circuit with a three-level switch circuit, resonant circuit, transformer, rectifier circuit, and filter circuit is designed, where transistors are controlled to turn on and off in a specific order to achieve zero-voltage switching and minimize conduction losses, using body diodes for current freewheeling and reducing electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional switching control is used in power conversion circuits, then the circuit can operate stably, but switching loss, conduction loss, and current switching loss cannot be reduced simultaneously
Solution Approach 1:
The resonant circuit is activated before the main switching action to pre-charge or pre-discharge the switch voltage, enabling zero-voltage switching. This preliminary action reduces switching loss by ensuring the switch operates at or near zero voltage during turn-on, directly addressing the energy loss problem while maintaining controlled operation
2Productivity
If switching frequency is increased to improve conversion speed, then power conversion efficiency improves, but switching loss and electromagnetic interference increase
Solution Approach 1:
The resonant circuit operates in periodic cycles, alternating between energy storage and energy release phases. This periodic operation allows the main switch to conduct at higher frequencies while the resonant circuit handles the high-frequency current components, enabling fast conversion speed without proportionally increasing switching loss in the main power switch
3Loss of energy
If body diodes are used for current freewheeling, then conduction loss is reduced, but reverse recovery effect causes electromagnetic interference
Solution Approach 1:
The resonant inductor acts as an intermediary element that provides a controlled path for current transition. Instead of relying solely on the body diode's reverse recovery characteristics, the resonant inductor smoothly transfers current between switches, reducing the abrupt current changes that cause electromagnetic interference while maintaining the low conduction loss benefit of body diode operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces switching losses, conduction losses, and current switching losses, enhancing the overall efficiency of the power conversion process.
Implementation Method 1
a resonant circuit, transformer, rectifier circuit and filter circuit are connected in sequence
Implementation Method 2
each of the transistors is connected in parallel to a body diode, and a direction of the body diode is set as follows: the body diode is turned on when the transistor connected in parallel to the body diode is reverse biased
Implementation Method 3
an output end of the resonant circuit is connected to a primary-side winding of the transformer, a secondary-side winding of the transformer is connected to an input end of the rectifier circuit
Data Source
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AI summary
This application discloses a control method of a power conversion circuit, and a related power conversion circuit. The related power conversion circuit includes a three-level switch circuit and a resonant circuit, and the method includes: controlling all transistors in the three-level switch circuit to be turned off, where a body diode of a transistor S1, a body diode of a transistor Q1, and a body diode of a transistor Q2 are all turned on based on a current freewheeling function of the resonant circuit; controlling the S1 to be turned on, to set up a first working state of the power conversion circuit; and after the first working state lasts for a time length T1, controlling the Q1 and the Q2 to be turned on. Implementing embodiments of the present invention helps reduce a switching loss, a conduction loss, and a current switching loss that are in the power conversion circuit.