Three-Phase Single-Phase Matrix Converter High-Frequency Conversion
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Solution Overview
Problem
Existing three-phase AC to single-phase AC conversion technologies face challenges in accurately converting high-frequency single-phase AC power with reduced waveform disturbance, particularly in applications like contactless power supply for electric vehicles, due to the need for large capacitors and reactors which increase device size and complexity.
Innovation Solution
A three-phase/single-phase matrix converter that employs a bidirectional switch circuit and a control unit generating specific carrier waveform patterns to perform virtual AC/DC and DC/AC conversions, ensuring accurate high-frequency single-phase AC output by managing voltage phases and interline voltage generation sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rectifier and smoothing capacitor are used to convert three-phase AC to single-phase AC, then DC voltage stability is improved, but device size increases due to large capacitor and reactor requirements
Solution Approach 1:
The patent extracts and eliminates the smoothing capacitor and input reactor from the conventional AC-DC-AC conversion system. By directly converting three-phase AC to single-phase AC through matrix conversion, the components responsible for voltage stabilization (capacitor) and current smoothing (reactor) are removed, thereby reducing device size while maintaining conversion functionality.
Solution Approach 2:
The patent merges the AC-DC conversion and DC-AC conversion functions into a single direct AC-AC matrix conversion process. The bidirectional switch circuit performs both conversion stages simultaneously, eliminating the need for separate capacitor-based DC link and reactor-based input filtering, thus reducing overall device volume.
2Volume of stationary object
If a matrix converter with bidirectional switches is used to directly convert three-phase AC to single-phase AC, then device size is reduced, but waveform accuracy deteriorates at high frequencies
Solution Approach 1:
The patent implements dynamic carrier waveform pattern selection based on the operating mode. The control unit dynamically switches between different carrier waveform patterns (first pattern for normal operation, second pattern for high-frequency operation) to optimize waveform accuracy across different frequency ranges while maintaining the compact matrix converter structure.
Solution Approach 2:
The patent changes the carrier waveform pattern parameter according to the operating mode. By detecting the current mode and selecting the appropriate carrier waveform pattern, the system adapts its conversion characteristics to maintain high waveform accuracy at high frequencies while preserving the size benefits of direct matrix conversion.
3Speed
If high-frequency single-phase AC conversion is performed using conventional methods, then conversion capability is achieved, but waveform disturbance increases
Solution Approach 1:
The patent performs preliminary selection of the appropriate carrier waveform pattern before executing the conversion. The control unit detects the operating mode in advance and pre-selects the optimal carrier waveform pattern, enabling the matrix converter to perform high-frequency conversion with minimal waveform disturbance by being prepared in advance with the correct conversion parameters.
Data Source
AI summary
A configuration for the object includes: a bidirectional switch circuit which turns ON/OFF supply of input three-phase AC power to a load LD; and a control unit which performs virtual AC/DC conversion processing in which a plurality of interline voltage generation sections selecting two phases among the input three-phase AC power are obtained according to a plurality of modes classified according to a magnitude relationship between voltages of respective phases in the input three-phase AC power within a predetermined switching cycle and generates a switching pattern of the bidirectional switch circuit so as to perform virtual DC/AC conversion processing corresponding to the plurality of interline voltage generation sections from a second carrier waveform pattern according to the plurality of modes and a U-phase control signal and a V-phase control signal corresponding to a phase of an output side.