Bidirectional Switch Control for Wireless Power Commutation
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Solution Overview
Problem
Matrix converters based on hybrid commutation face challenges such as high costs and large size due to the need for current sensors for high-speed zero-cross point detection, and suffer from total harmonic distortion and commutation failures due to errors in voltage and current commutation.
Innovation Solution
An electronic circuit that controls bidirectional switches for wireless power transmission, employing a hybrid commutation method that switches between voltage and current commutation based on output AC signal levels and current levels, without requiring a high-frequency current sensor, by using a reference signal with a frequency higher than the output AC signal to determine optimal commutation times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current sensor is used for high-speed and high-accuracy detection of zero-cross point in voltage commutation, then commutation accuracy is improved, but device cost and size increase
Solution Approach 1:
The patent extracts the current sensing function from a dedicated current sensor and implements it through voltage detection across the bidirectional switch. By measuring the voltage drop across the switch during conduction, the system determines current direction and zero-cross points without requiring an external current sensor, thereby reducing device complexity and cost while maintaining measurement precision.
Solution Approach 2:
The bidirectional switch serves multiple functions: power switching, current sensing, and zero-cross detection. The same switch component that controls power flow also provides the sensing mechanism by detecting voltage drops during conduction, eliminating the need for separate sensing components and reducing overall device complexity.
2Productivity
If voltage commutation is frequently performed, then power transmission efficiency is improved, but total harmonic distortion of input current increases due to commutation errors
Solution Approach 1:
The system continuously monitors the voltage across each bidirectional switch to detect current direction changes and zero-cross points in real-time. This feedback mechanism enables the control unit to accurately determine the optimal commutation timing, ensuring that commutation occurs at the precise moment when input voltage and current are in the correct quadrant, thereby minimizing harmonic distortion while maintaining high transmission efficiency.
Solution Approach 2:
The control unit performs preliminary detection of current direction and zero-cross points using the voltage across the switches before executing commutation. By detecting the upcoming zero-cross point in advance through voltage monitoring, the system prepares for commutation at the optimal moment, preventing commutation errors and reducing harmonic distortion before they can occur.
3Reliability
If hybrid commutation is used to avoid commutation failure, then reliability is improved, but control complexity increases due to compensation requirements
Solution Approach 1:
The bidirectional switches automatically provide the sensing function needed for reliable commutation by generating detectable voltage drops during conduction. The system uses its own operational characteristics (voltage across the switch during current flow) to enable accurate zero-cross detection and commutation control, eliminating the need for external sensing components and simplifying the overall control architecture while maintaining high reliability.
Data Source
AI summary
An electronic circuit to receive input AC signals having different phases, and to control bidirectional switches corresponding to phases to generate, based on input AC signals having the phases, output AC signals having the phases and having a frequency different from a frequency of the input AC signals, the electronic circuit has reference signal circuitry to generate a reference signal having a frequency higher than the frequency of the output AC signals, and a commutation circuitry to control switching between voltage commutation and current commutation, wherein, in the voltage commutation, the commutation circuitry switches the bidirectional switches corresponding to the phases in sequence based on a voltage level of the output AC signals of the phases before and after a time point when an amplitude of the reference signal becomes a specific amplitude value, and in the current commutation, the commutation circuitry switches the bidirectional switches in parallel.