Power Conversion Module Resonant Branch for Soft Switching
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Solution Overview
Problem
Traditional Solid-State Transformers (SSTs) face challenges with high switching losses and low system operating frequency due to hard switching in the continuous current control mode.
Innovation Solution
The power conversion module includes a first and second power unit, an interconnecting branch with a resonant capacitor and switching unit, and a resonant inductor. This configuration allows for soft switching by controlling the switching unit to generate a current opposite to the input current, reducing switching losses and increasing operating frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hard switching is used in continuous current control mode, then the power conversion module can operate continuously, but switching losses increase and operating frequency decreases
Solution Approach 1:
The patent applies resonant switching by introducing a resonant inductor and resonant capacitor to create an LC resonant circuit. The switching unit generates resonant current that oscillates at a specific frequency, enabling the main switches to turn on and off during voltage zero-crossing points. This resonant vibration approach reduces switching losses while maintaining high operating frequency, directly resolving the technical contradiction between energy loss and productivity.
Solution Approach 2:
The patent changes the switching mode from hard switching to soft switching by controlling the switching unit to generate current in opposite direction before main switch turn-on. This parameter change in switching strategy, combined with adjusting the resonant circuit parameters (inductor and capacitor values), enables the system to operate at higher frequencies with reduced switching losses.
2Loss of energy
If soft switching is implemented using traditional methods, then switching losses are reduced, but the system complexity increases
Solution Approach 1:
The patent merges the soft switching function into the existing bridge arm structure by adding the switching unit and resonant components directly to the power conversion module. The switching unit is integrated with the bridge arm switches, and the resonant inductor and capacitor are combined into a unified resonant circuit that works across all switching operations, reducing overall system complexity compared to separate soft switching circuits for each switch.
Solution Approach 2:
The resonant circuit and switching unit serve multiple functions simultaneously: they provide soft switching for all main switches in the bridge arm, generate resonant current for zero-voltage switching, and maintain continuous current control. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in system complexity while achieving reduced switching losses.
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
The proposed solution achieves reduced switching losses and increased system operating frequency, improving efficiency and power density while enabling soft switching in the power conversion module.
Implementation Method 1
The interconnecting branch includes a resonant capacitor and a switching unit that are electrically connected to each other. The resonant inductor is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm, or in series with the resonant capacitor.
Implementation Method 2
the switching unit is controlled to cause the current flowing through the branch connecting the midpoint of the first bridge arm and the midpoint of the second bridge arm to be in the opposite direction of the current flowing through the first side of the first power unit before one of the switches in the first bridge arm and the second bridge arm is turned on, so as to realize a soft turn-on of the switch
Data Source
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AI summary
The present disclosure relates to a power conversion module, a control method, and a power conversion system. An interconnecting branch is connected between a first power unit and a second power unit. The interconnecting branch includes a resonant capacitor and a switching unit that are electrically connected. The resonant inductor is connected between the midpoint of a first bridge arm and the midpoint of a second bridge arm, or in series with the resonant capacitor. In the present disclosure, by controlling the on and off of the interconnecting branch, a current opposite to the power grid current is generated on the branch connecting the first bridge arm and the second bridge arm, thereby realizing the soft switching of the switching transistors of the power conversion module.