Bidirectional Switch Control for DC-AC Power Converter Voltage Stability
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Solution Overview
Problem
Conventional electric power converters experience instability in common mode voltage due to electrical separation between the DC and AC sides, leading to inconsistent DC power source voltages.
Innovation Solution
An electric power converter with a switching unit and a controller that includes bidirectional switches and a second bidirectional switch, allowing for controlled connection and interruption between the DC power source and the switching unit, ensuring stable common mode voltage by preventing high-frequency potential changes from reaching the DC side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the second bidirectional switch is turned off to prevent high-frequency potential changes from reaching the DC power source, then the DC side and AC side become electrically separated, but this causes the common mode voltage of the DC power source to become inconstant
Solution Approach 1:
The patent introduces a third bidirectional switch as an intermediary component connected between the DC power source and the switching unit. This mediator switch, when turned on, provides a path that maintains constant common mode voltage by preventing electrical separation between DC and AC sides, while the second bidirectional switch remains off to block high-frequency potential changes. The intermediary switch thus resolves the contradiction by providing a controlled connection that satisfies both requirements.
2Stability of the object's composition
If the second bidirectional switch is turned on to maintain constant common mode voltage, then the DC side and AC side remain electrically connected, but this allows high-frequency potential changes to reach the DC power source
Solution Approach 1:
The patent employs dynamic control of the third bidirectional switch, which is turned on only during specific intervals when high-frequency potential changes are not present. This dynamic switching strategy maintains constant common mode voltage during safe periods while blocking high-frequency interference during problematic periods, thus resolving the contradiction through time-dependent control.
3Productivity
If the switching unit operates at high frequency to improve power conversion efficiency, then the power conversion speed increases, but this generates high-frequency potential changes that affect the DC power source
Solution Approach 1:
The patent extracts and isolates the high-frequency switching operations to the AC side of the second bidirectional switch, while the DC side maintains a stable, low-frequency connection through the third bidirectional switch. This separation extracts the harmful high-frequency components from the DC power source path while preserving the high-frequency power conversion functionality on the AC side.
Data Source
AI summary
An electric power converter according to an embodiment includes a switching unit, a controller, and a second bidirectional switch. The switching unit includes a plurality of first bidirectional switches disposed between a DC power source and an AC load or between a DC load and an AC power source. The controller controls the switching unit to perform power conversion between DC power and AC power. When turning off the second bidirectional switch disposed on a path between one pole of the DC power source or the DC load and the switching unit, the controller turns on the first bidirectional switch connected between the other pole of the DC power source and the AC load or between the other pole of the DC load and the AC power source.