Matrix Converter Mode Transition Control
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Solution Overview
Problem
Conventional matrix converters experience voltage use rate fluctuations and shock in output electric current when switching between PWM control and direct grid connection modes, leading to inefficiencies and potential damage.
Innovation Solution
A matrix converter with a control unit that selectively executes PWM control and direct combination modes, including voltage increase and follow-up controls, to manage frequency and phase differences, optimizing the transition between modes to reduce current shocks and improve voltage use efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If PWM control is stopped and direct combination control is executed when output frequency coincides with AC power supply frequency, then voltage use rate is improved and switching loss is reduced, but voltage use rate changes sharply causing shock in output electric current
Solution Approach 1:
The control unit performs preliminary actions by executing voltage increase control and follow-up control before transitioning to direct combination mode. The voltage increase control gradually increases output voltage to match AC power supply voltage, and the follow-up control adjusts output voltage phase to follow the AC power supply phase, preparing the system for smooth mode transition and preventing current shocks.
Solution Approach 2:
The control unit dynamically adjusts control parameters during mode transition. It determines frequency coincidence, voltage coincidence, and phase coincidence conditions dynamically, and selectively executes different control modes (voltage increase control, follow-up control, or direct combination control) based on the current state, enabling smooth and adaptive transition between PWM and direct combination modes.
2Productivity
If direct combination control is executed to improve voltage use rate, then switching loss of bidirectional switches is reduced, but voltage use rate changes sharply during switching between PWM and direct combination control
Solution Approach 1:
Before executing direct combination control, the control unit performs preliminary voltage increase control to gradually increase output voltage to match AC power supply voltage, and follow-up control to adjust phase alignment. This preliminary preparation prevents sharp changes in voltage use rate during the transition to direct combination mode.
Solution Approach 2:
The control unit continuously monitors and determines frequency coincidence, voltage coincidence, and phase coincidence conditions between output voltage and AC power supply. Based on this feedback information, it selectively executes appropriate control modes, ensuring stable and controlled changes in voltage use rate during mode transitions.
Data Source
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AI summary
A matrix converter includes: a power conversion unit configured to couple an AC power supply and a load together; and a control unit configured to selectively execute: a first control mode in which the control unit is configured to perform power conversion between the AC power supply and the load; and a second control mode in which the control unit is configured to directly combine the AC power supply with the load. The control unit is configured to: increase the output voltage and cause a phase of the output voltage follow up a voltage phase of the AC power supply in a case where a difference between a frequency of an output voltage from the power conversion unit to the load and a frequency of the AC power supply becomes within a predetermined range.