Resonant Power Converter Current Synthesizing Module
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Solution Overview
Problem
Resonant converters face challenges in obtaining accurate output current information due to sinusoidal current shapes with harmonics, making it difficult to sense current from the primary side and requiring complex computations to derive the average output current.
Innovation Solution
A resonant power converter with a current synthesizing method that includes a sensing circuit, peak hold circuit, and calculation unit to generate a synthesized output current based on resonant capacitor voltage, switching frequency, input voltage, and resonant capacitance, preventing output current from being affected by noise or harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensing is performed from the primary side in resonant converters, then the output current information can be obtained, but the measurement precision is poor due to sinusoidal current shape with harmonics
Solution Approach 1:
The patent introduces an intermediary approach by sensing the resonant capacitor voltage (which has a clear triangular waveform) instead of directly sensing the complicated sinusoidal resonant current. This intermediary measurement is then used to calculate the output current, avoiding the direct measurement problems while maintaining accuracy.
Solution Approach 2:
The patent replaces direct current sensing (electrical measurement) with voltage sensing across the resonant capacitor, followed by computational derivation. This substitution transforms a difficult current measurement problem into a more manageable voltage measurement plus calculation process.
2Measurement precision
If complex computation is used to derive average output current from peak value, then the output current information can be obtained, but the device complexity increases
Solution Approach 1:
The patent uses the resonant capacitor voltage as an intermediary parameter that has a simple triangular waveform, making it easy to measure and process. This intermediary simplifies the computation required to derive output current information compared to working directly with the sinusoidal resonant current waveform.
3Measurement precision
If direct current sensing is performed in resonant converters, then the output current can be measured, but the measurement is affected by noise and harmonics
Solution Approach 1:
The patent introduces the resonant capacitor voltage as an intermediary measurement that is less susceptible to noise and harmonics. The triangular waveform of the capacitor voltage provides a cleaner signal that can be more accurately measured and processed to derive the output current information.
Solution Approach 2:
The patent converts the potentially harmful effect of harmonics in the resonant current into a benefit by measuring the resonant capacitor voltage instead. The voltage waveform across the capacitor provides a cleaner, more measurable signal that avoids the harmonics problem while still providing the necessary information to calculate output current.
Data Source
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AI summary
A resonant power converter and a current synthesizing method therefor are provided. The resonant power converter includes a switch circuit (12), a resonant tank (13), a transformer (14), a rectifier circuit (15), and a current synthesizing module (20). The switch circuit (12) receives an input voltage (Vin) from an input source (11), and the rectifier circuit (15) outputs an output voltage (Vout) to a load (17). The current synthesizing module (20) includes a sensing circuit (21), a peak hold circuit (22), and a calculation unit (24). The sensing circuit (21) is configured to sense a resonant capacitor voltage (Vcr) on a resonant capacitor of the resonant tank (13). The peak hold circuit (22) is configured to receive the resonant capacitor voltage (Vcr) and acquires a peak value (Vcr_ph) thereof. The calculation unit (24) is configured to receive the peak value (Vcr_ph), a switching frequency (Fsw), the input voltage (Vin), the output voltage (Vout), and a resonant capacitance (Cr) of the resonant power converter and generate a synthesized output current (lout) accordingly.