Power Converter Voltage Stabilization via Bidirectional Switching
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Solution Overview
Problem
Conventional power converters experience significant power loss and efficiency drop due to high conduction and switching losses in switching elements, and require large commercial-frequency transformers for voltage compensation, leading to size and disturbance issues during AC power source fluctuations or failures.
Innovation Solution
A power converter that outputs AC voltage using a single-phase AC power source and a series-connected DC power source, with a bidirectional switch circuit and inverter circuit, allowing voltage levels to be selected and combined to minimize switching losses and eliminate the need for commercial-frequency transformers, by outputting voltages from the DC power source and AC power source to match the AC output voltage command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional power converters use switching elements for AC-DC and DC-AC voltage conversion, then voltage conversion function is achieved, but conduction losses and switching losses increase significantly
Solution Approach 1:
The patent extracts the transformer from the conventional AC-DC-AC conversion system and replaces it with a direct coupling between AC power source and inverter circuit. This eliminates the energy losses associated with transformer conduction and switching operations while maintaining voltage conversion capability through direct AC power source utilization.
Solution Approach 2:
The patent merges the AC power source directly with the inverter circuit, eliminating the intermediate DC conversion stage. The AC power source voltage is directly utilized by the inverter circuit to generate output voltage, combining the functions of rectification, DC-link, and inversion into a single streamlined path that reduces energy losses.
2Reliability
If commercial-frequency transformers are used for voltage compensation, then voltage stabilization is achieved, but device size becomes large
Solution Approach 1:
The patent replaces the mechanical transformer system with an electronic control system. The inverter circuit uses switching elements controlled by a control unit to generate compensated output voltage directly from the AC power source, eliminating the need for heavy commercial-frequency transformers while maintaining voltage stabilization capability.
Solution Approach 2:
The patent changes the operating parameters from commercial-frequency transformer operation to high-frequency switching operation. By using switching elements that operate at higher frequencies, the system achieves voltage compensation without requiring large, heavy transformers designed for lower commercial frequencies.
3Power
If conventional power converters use multiple switching stages, then voltage conversion is achieved, but switching losses increase
Solution Approach 1:
The patent extracts and removes the intermediate DC conversion stage and associated switching elements from the power conversion path. By directly coupling the AC power source with the inverter circuit, the system eliminates redundant switching operations that would generate additional losses while maintaining the essential voltage conversion function.
4Reliability
If voltage compensation is implemented during AC power source fluctuations, then output voltage stability is improved, but system complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the control unit monitors the AC power source voltage and adjusts the inverter circuit switching accordingly. This feedback system automatically compensates for voltage fluctuations without requiring complex manual intervention or additional hardware, maintaining output voltage stability through intelligent control.
Data Source
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Figure 2(a)~2(d)
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AI summary
Provided is a power converter that can supply constant voltage to a load even upon fluctuation of voltage of an AC power source. The power converter comprises: an inverter circuit 4 resulting from connecting in series a switching element Q1 and a switching element Q2, the inverter circuit 4 being connected to both ends of a DC power source series circuit 30 resulting from connecting in series a DC power source Psp and a DC power source Psn; an AC output terminal U that is connected to a connection point of the switching element Q1 and the switching element Q2; an AC output terminal V that is connected to a connection point of the DC power source Psp and the DC power source Psn; a bidirectional switch element S1 one end of which is connected to the AC output terminal U and the other end of which is connected to a terminal R of an AC power source 1; and a bidirectional switch element S2 one end of which is connected to the AC output terminal U and the other end of which is connected to a terminal S of the AC power source 1.