Vienna-like Three-Level Circuit Control for Zero-Voltage Switching
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Solution Overview
Problem
Conventional methods for controlling Vienna-like three-level circuits cannot achieve zero-voltage turning on of the high-frequency bridge arm switch transistor, resulting in high circuit losses.
Innovation Solution
A method and device that detect the inductor current during AC input voltage cycles and control the freewheeling and main switch transistors to maintain or switch states based on preset current thresholds, ensuring zero-voltage turning on by allowing the inductor current to reverse, thereby reducing circuit losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional inductor current continuous conduction mode control method (CRM) is used, then the control method is simple to implement, but zero-voltage turning on of the high-frequency bridge arm switch transistor cannot be achieved, resulting in high circuit loss
Solution Approach 1:
The patent applies dynamics by transitioning from a static continuous conduction mode to a dynamic control mode that allows the inductor current to reverse. The control method dynamically adjusts the switching states based on the instantaneous current direction, enabling the system to operate in different modes (positive half-cycle and negative half-cycle) to achieve zero-voltage turning on and reduce circuit losses.
Solution Approach 2:
The patent changes the operating parameter of the inductor current from continuous positive current to bidirectional current that can reverse. By allowing the current to reverse during the negative half-cycle and controlling the switching transistors accordingly, the system achieves zero-voltage turning on, thereby reducing switching losses and improving overall efficiency.
2Loss of energy
If the freewheeling and main switch transistors are controlled to maintain or switch states until inductor current reverses, then zero-voltage turning on is achieved, but the control complexity increases
Solution Approach 1:
The patent employs feedback by continuously monitoring the inductor current direction and using this information to control the switching states of the transistors. The control system detects when the current reverses and adjusts the switching accordingly, providing a feedback-based control mechanism that achieves zero-voltage turning on while managing the increased control complexity through systematic current-based feedback signals.
Data Source
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AI summary
A method and a device for controlling a Vienna-like three-level circuit are provided. The method includes: detecting an inductor current of an inductor connected to each operating high-frequency bridge arm in the Vienna-like three-level circuit during a positive half cycle of an AC input voltage; and in a case that a freewheeling switch transistor on the high-frequency bridge arm to which the inductor is connected is in an on state, and a main switch transistor is in an off state, controlling the freewheeling switch transistor to maintain in the on state and the main switch transistor to maintain in the off state if the detected inductor current does not reach a preset negative current, and controlling the freewheeling switch transistor to be turned off and the main switch transistor to be turned on if the detected inductor current reaches the preset negative current.