Matrix Converter Control for Compact Single-Phase EV Charging
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Solution Overview
Problem
Existing chargers for electric vehicles cannot efficiently utilize single-phase AC power supply due to the need for a DC link capacitor, leading to larger charger sizes.
Innovation Solution
A power conversion device incorporating a three-phase to single-phase matrix converter, an AC-DC converter, a transformer, and a power ripple compensation circuit, with a control mechanism that includes zero voltage periods and adjusted phase difference calculations to handle single-phase AC power, eliminating the need for a DC link capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC link capacitor is used to smooth DC power input, then power conversion stability is improved, but charger size increases
Solution Approach 1:
The patent extracts and removes the DC link capacitor from the power conversion system by implementing a direct AC-AC conversion architecture using a three-phase to single-phase matrix converter connected directly to the AC-DC converter, eliminating the intermediate DC link and its associated capacitor while maintaining power conversion stability through direct coupling and control strategies
Solution Approach 2:
The matrix converter performs multiple functions simultaneously: it converts three-phase AC to single-phase AC, provides power factor correction, and enables direct coupling between AC input and AC-DC converter without requiring a DC link capacitor, thereby reducing charger size while maintaining stability
2Volume of stationary object
If a three-phase to single-phase matrix converter is used to eliminate the DC link capacitor, then charger size is reduced, but compatibility with single-phase AC power supply is lost
Solution Approach 1:
The matrix converter is designed with universal input capability that can accept both three-phase AC power supply and single-phase AC power supply. The converter's switching network and control strategy are configured to handle both input types, enabling the charger to adapt to different power supply environments while maintaining the compact design without a DC link capacitor
Solution Approach 2:
The control system dynamically adjusts the switching patterns and phase difference calculations based on the detected input power supply type (three-phase or single-phase). The control portion changes the calculation method for phase difference values depending on whether the phase difference is longer than the zero voltage period, enabling seamless adaptation to different power supply configurations
3Productivity
If zero voltage periods and dynamic phase difference calculations are implemented, then single-phase AC power conversion efficiency is improved, but control complexity increases
Solution Approach 1:
The control system implements periodic zero voltage periods in the switching pattern where all switches are turned off simultaneously. This periodic action creates intervals with zero voltage across the AC-DC converter input, improving power conversion efficiency by reducing switching losses and enabling better utilization of the power ripple compensation circuit, while the periodic nature simplifies the control logic compared to continuous complex modulation
Solution Approach 2:
The control portion dynamically changes the phase difference parameter between the matrix converter output and AC-DC converter input based on the operating conditions and power supply type. By adjusting this parameter and changing the calculation method depending on whether the phase difference is longer than the zero voltage period, the system optimizes power conversion efficiency while managing control complexity through parameter-based adaptation
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 enables a compact power conversion device capable of efficiently converting single-phase AC power to DC power, reducing charger size and improving efficiency while minimizing heat generation and battery deterioration.
Implementation Method 1
a transformer connected between the three-phase to single-phase matrix converter and the AC-DC converter
Implementation Method 2
a power ripple compensation circuit including an inductor and a capacitor connected in series
Implementation Method 3
a power ripple compensation circuit including an inductor and a capacitor connected in series
Data Source
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AI summary
[Problems to be solved] It is intended to provide a compact power conversion device. [Solution] In a power conversion device 100 including a three-phase to single-phase matrix converter 110; an AC-DC converter 130; a transformer 120; and a power ripple compensation circuit 150, and a control portion 140 for controlling switches S11-S16 of the three-phase to single-phase matrix converter 110 and switches S31-S34 of the AC-DC converter 130, the control portion 140 changes a calculation method for a value of a phase difference δ used when generating a switching pattern for the switches S11-S16 of the three-phase to single-phase matrix converter 220 and the switches S31-S34 of the AC-DC converter 130 depending on whether the phase difference δ is longer than a zero voltage period 2ε or not.