Impedance Matching Device Switching Control
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Solution Overview
Problem
Existing impedance matching devices for high frequency power supplies face instability in matching loads with changing impedances, leading to excessive switching losses and fluctuation due to low capacitance resolution and incorrect threshold settings.
Innovation Solution
An impedance matching device that acquires and calculates impedance or reflection coefficients in real-time, stores these values with corresponding semiconductor switch states, and adjusts switch states to stabilize matching by prohibiting excessive switching when near-optimal conditions are met, using a counting unit to determine when to stop switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the capacitance resolution of the variable capacitor is low, then the device complexity is reduced, but the stability of impedance matching deteriorates
Solution Approach 1:
The patent applies preliminary action by storing the ON/OFF states of semiconductor switches and associated impedance data in advance in a storage unit. When impedance matching is needed, the system retrieves previously stored optimal switch states rather than searching from scratch, preventing excessive switching operations and stabilizing the matching state.
Solution Approach 2:
The patent implements feedback by continuously monitoring the impedance state, comparing it with stored reference data, and adjusting semiconductor switch states based on the comparison results. This closed-loop feedback mechanism ensures stable impedance matching by preventing unnecessary switch state changes when the system is already near optimal.
2Measurement precision
If the threshold value of reflection coefficient is set too small, then the measurement precision is improved, but the productivity deteriorates due to excessive switching operations
Solution Approach 1:
The system pre-stores optimal switch states and corresponding impedance data in the storage unit during a calibration phase. This preliminary preparation allows the system to quickly retrieve optimal states without performing excessive switching operations during actual impedance matching, thus maintaining both precision and productivity.
Solution Approach 2:
The patent uses a threshold value that balances precision and efficiency. Instead of using an extremely small threshold that would cause continuous switching, the system employs a practical threshold combined with stored reference data to achieve sufficient matching precision while avoiding excessive switching operations that would reduce productivity.
3Measurement precision
If semiconductor switches are frequently switched to achieve precise matching, then the measurement precision is improved, but the loss of energy increases due to switching losses
Solution Approach 1:
By pre-storing optimal switch states and their corresponding impedance characteristics in the storage unit, the system avoids frequent switching operations. The stored data allows the system to achieve precise impedance matching by retrieving previously determined optimal states rather than continuously searching for them through repeated switching.
Solution Approach 2:
The feedback mechanism compares current impedance measurements with stored reference data to determine whether switching is actually needed. This feedback control prevents unnecessary switching operations that would cause energy losses, while still achieving precise matching when required by making informed switching decisions.
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
This approach stabilizes impedance matching, reduces switching losses, and prevents intermittent fluctuations by maintaining optimal switch states, ensuring efficient power transfer to loads with changing impedances.
Implementation Method 1
a variable capacitor in which a plurality of series circuits of capacitors and semiconductor switches are connected in parallel
Implementation Method 2
The semiconductor switches are P-Intrinsic-N (PIN) diodes
Data Source
AI summary
An impedance matching device includes: a variable capacitor; a calculation unit that calculates a reflection coefficient on the load side; a storage unit that stores the reflection coefficient calculated within a predetermined period so as to be associated with ON/OFF states of the semiconductor switches; a determination unit that determines ON/OFF states to be taken by the semiconductor switches using a calculation result within the predetermined period; a control unit that turns on or off the semiconductor switches based on the determined ON/OFF states; and a counting unit that counts the number of times the determined ON/OFF states have changed. In a case where the counted number of times is larger than a predetermined number of times, the control unit turns on or off the semiconductor switches so as to match ON/OFF states associated with a reflection coefficient closer to 0, among the stored reflection coefficients, and then prohibits ON/OFF switching.