AC-AC Converter with Segmented Half-Bridge Circuits
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Solution Overview
Problem
Existing AC-AC converters face challenges in reducing switching loss and inductor size due to high conduction and switching losses, especially when dealing with voltage fluctuations and power interruptions.
Innovation Solution
The configuration includes a forward converter and a reverse converter with anti-parallel diodes connected semiconductor switches, capacitors in series, and bidirectional switches to minimize inductor loss and switching loss by controlling semiconductor switch operations based on input voltage levels, allowing direct AC input to AC output when within a specified range and stepping voltages up or down when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional AC-AC converter circuits with multiple semiconductor switches are used, then voltage regulation capability is improved, but switching loss increases
Solution Approach 1:
The converter circuit is divided into two independent half-bridge circuits: a rectifier circuit for AC-DC conversion and an inverter circuit for DC-AC conversion. Each circuit operates semi-independently with its own semiconductor switches (IGBTs 5-6 for rectifier, IGBTs 7-8 for inverter), allowing separate control and optimization of switching operations to reduce overall switching loss while maintaining voltage regulation capability.
Solution Approach 2:
The semiconductor switches are controlled to operate in periodic switching cycles, where IGBTs 5-6 switch during rectification phases and IGBTs 7-8 switch during inversion phases. This periodic switching allows the circuit to alternate between rectifier and inverter modes, achieving voltage regulation through timed switching actions rather than continuous high-frequency switching of all switches.
2Adaptability or versatility
If conventional AC-AC converter circuits with multiple semiconductor switches are used, then voltage regulation capability is improved, but device complexity increases
Solution Approach 1:
The complex AC-AC conversion function is segmented into two simpler half-bridge circuits: rectifier circuit (AC-DC) and inverter circuit (DC-AC). Each half-bridge circuit uses only two semiconductor switches instead of four, reducing the total switch count while maintaining the ability to regulate output voltage through coordinated operation of the two circuits.
Solution Approach 2:
The two half-bridge circuits share common DC bus capacitors (9 and 10) and can operate in different modes (rectifier mode or inverter mode) depending on the operating phase. This multi-functionality allows the same hardware structure to perform both AC-DC rectification and DC-AC inversion, reducing overall device complexity compared to dedicated separate circuits.
3Adaptability or versatility
If inductors are used in AC-AC converter circuits, then voltage regulation is improved, but inductor size and loss increase
Solution Approach 1:
The circuit design extracts and eliminates the need for large power inductors typically required in conventional AC-AC converters. Instead of using inductors for energy storage and voltage regulation, the patent relies on the switching action of semiconductor switches and the capacitive energy storage in DC bus capacitors (9 and 10) to achieve voltage regulation, thereby removing the source of inductor losses.
Solution Approach 2:
The patent substitutes magnetic energy storage (inductors) with electronic switching control. Rather than relying on inductor magnetic fields to regulate voltage, the system uses controlled switching of semiconductor devices and capacitive energy transfer to achieve the same voltage regulation function, eliminating inductor-related copper losses and core 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
This configuration reduces switching loss and inductor size by minimizing inductor loss and allowing efficient voltage regulation, maintaining stability and reducing power system size while maintaining low disturbance in output.
Implementation Method 1
a bidirectional switch is connected between the one end of an alternating current input and a series connection point inside the second semiconductor switch series circuit
Implementation Method 2
semiconductor switches, to each of which a diode is connected in anti-parallel, are connected in series
Implementation Method 3
a first inductor is connected between one end of an alternating current input and a series connection point inside the first semiconductor switch series circuit
Implementation Method 4
a capacitor series circuit wherein capacitors are connected in series are connected in parallel
Data Source
AI summary
An AC-AC converter includes a first semiconductor switch series circuit, a second semiconductor switch series circuit, and a capacitor series circuit are connected in parallel. A first inductor is connected between one end of an alternating current input and a series connection point of the first semiconductor switch series circuit. A bidirectional switch is connected between the one end of the alternating current input and a series connection point of the second semiconductor switch series circuit. A second inductor is connected between the series connection point of the second semiconductor switch series circuit and one end of an alternating current output. A series connection point of the capacitor series circuit is connected to the other end of the alternating current input and the other end of the alternating current output.