Single-Stage Matrix Converter Power System
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Solution Overview
Problem
Existing power conversion systems (PCS) face limitations in achieving high-power density, controlling power factor, and regulating current in DC sources/loads, particularly in energy storage applications, due to the use of low-frequency transformers and DC-links which result in increased volume, weight, and reduced service life.
Innovation Solution
A single-stage, high-frequency isolated PCS is developed, utilizing a three-phase-to-single-phase matrix converter with a high-frequency transformer and a full-bridge converter, along with a new space vector modulation scheme to control power factor and current, eliminating the need for a DC-link capacitor and enabling galvanic isolation, thus reducing volume and weight while extending service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a low-frequency transformer is used in the DC-DC conversion stage, then the complexity is reduced and well-known control techniques are available, but the power density is low and the volume is large
Solution Approach 1:
The patent changes the operating frequency parameter of the transformer from low-frequency to high-frequency range. This parameter change enables the use of a high-frequency transformer that provides both high power density and compact size while maintaining the required isolation and control capabilities through advanced modulation techniques
Solution Approach 2:
The patent employs dynamic control strategies including phase-shift control and pulse-width modulation to manage the high-frequency transformer operation. These dynamic control methods enable precise power regulation and adaptability while achieving high power density, resolving the contradiction between complexity reduction and power density improvement
2Ease of operation
If a DC-link is used to decouple the operation of the three-phase VSC from the DC-DC converter, then the operation is decoupled, but the volume increases and capacitor life decreases
Solution Approach 1:
The patent extracts and eliminates the DC-link capacitor from the system by implementing a direct coupling between the three-phase voltage source converter and the high-frequency transformer. This removal of the bulky capacitor reduces system volume and eliminates capacitor aging issues while maintaining operational flexibility through direct power transfer control
Solution Approach 2:
The patent merges the functions of the DC-link and the high-frequency transformer into a unified power conversion stage. The high-frequency transformer provides both the decoupling function previously requiring a DC-link and the isolation function, thereby reducing overall system volume while maintaining ease of operation through integrated control
3Volume of stationary object
If a three-phase-to-single-phase matrix converter is used for direct AC to AC conversion, then the volume is reduced by eliminating the DC-link, but the capability to control power factor and regulate DC current is limited
Solution Approach 1:
The patent enhances the matrix converter to perform multiple functions: direct AC-AC conversion, power factor control, and DC current regulation. By integrating these capabilities into a single volume-compact converter stage coupled with the high-frequency transformer, the system achieves both small size and versatile control functionality
Solution Approach 2:
The patent implements feedback control mechanisms that monitor output parameters and adjust the matrix converter switching patterns accordingly. This feedback enables precise control of power factor and DC current while maintaining the compact volume advantage of the direct AC-AC conversion topology
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
The solution achieves higher power density, longer service life, improved power quality, and safe operation with galvanic isolation, enabling efficient energy storage and supply to sensitive loads with controlled power factor and low current ripple.
Implementation Method 1
A single-stage, high-frequency isolated PCS is developed, utilizing a three-phase-to-single-phase matrix converter with a high-frequency transformer
Data Source
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AI summary
The present application presents a solution that intends to solve the problem of providing a single-stage bidirectional power conversion system (PCS) with a controllable power factor and the capability to regulate the current in the DC side. Disclosed is a single-stage, bidirectional and high- frequency isolated PCS, comprising a high-frequency transformer (HFT), a three-phase-to-single-phase matrix converter (MC), a full-bridge (FB) AC to DC converter, and a control system, where the control system outputs are connected to the switches of the MC and the FB converter. Moreover, the PCS output can also form a DC network for energy supply of several devices. This system converts three-phase AC power input from the network into DC power output that can be used for example to charge an energy storage device or supply a direct current distribution system. It is also possible to convert DC power input into AC power output to supply the network.