Resonant Converter Controller Circuit Frequency Modulation
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Solution Overview
Problem
The accuracy of control in resonant converters is limited by a predetermined allowable range of output voltages, making it difficult to predict the operation and transition of output voltage, especially due to variations in input voltage and load magnitude.
Innovation Solution
A resonant converter controller circuit that includes oscillating means for generating clock and sawtooth signals, a comparison means for determining drive and pause intervals based on the difference between output and target voltages, and a logical operation means to generate a drive control signal, ensuring precise control of output voltage by adjusting the duty ratio of drive and pause intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hysteresis control is used to control the resonant converter, then the output voltage can be maintained within an allowable range, but the control accuracy is limited and the error between output voltage and target voltage cannot be reduced below a predetermined value
Solution Approach 1:
The patent changes the control parameter from duty ratio modulation to frequency modulation. By modulating the frequency of the drive signal while keeping the duty ratio fixed at 50%, the patent achieves continuous output voltage control without the deadband limitations of hysteresis control. The frequency is adjusted based on the difference between output voltage and target voltage, enabling precise control below the predetermined error threshold.
Solution Approach 2:
The patent introduces dynamic frequency adjustment based on real-time voltage feedback. The oscillating circuit's frequency is dynamically changed according to the voltage difference, allowing the system to adapt to varying load and input voltage conditions. This dynamic control enables the output voltage to track the target voltage continuously, eliminating the static allowable range limitation of hysteresis control.
2Adaptability or versatility
If the duty and period of the drive signal are allowed to change with input voltage and load magnitude, then the resonant converter can adapt to different conditions, but the operation and output voltage transition become difficult to predict
Solution Approach 1:
The patent employs periodic drive signals with fixed duty ratio (50%) and modulated frequency. By maintaining a constant periodic structure while adjusting frequency, the system achieves adaptability to different operating conditions while preserving predictability. The regular periodic nature of the waveform makes the output voltage transitions predictable, unlike arbitrary duty ratio changes.
Solution Approach 2:
The patent implements feedback control where the output voltage is continuously monitored and compared with the target voltage. The frequency of the drive signal is adjusted based on this feedback to maintain accurate voltage regulation. This closed-loop feedback mechanism ensures both adaptability to varying conditions and predictability of operation, as the system responds systematically to voltage deviations.
3Device complexity
If fixed duty ratio control is used, then the control circuit is simplified, but the ability to precisely control output voltage across varying conditions is reduced
Solution Approach 1:
The patent changes the controlled parameter from duty ratio to frequency. By fixing the duty ratio at 50% and modulating the frequency, the control circuit is simplified while maintaining precise voltage control capability. The frequency modulation provides a direct relationship between control signal and output voltage, enabling precise control without complex duty ratio adjustment circuits.
Data Source
AI summary
A resonant converter controller circuit is provided. Each period in drive control has a drive time interval and a pause time interval for driving/pausing the resonant converter. The resonant converter controller circuit includes a first oscillating means for generating a clock signal, a second oscillating means for generating a sawtooth wave signal, a third oscillating means for generating a rectangular wave signal, comparison means for outputting a comparison signal indication the rive time interval, by comparing the sawtooth wave signal with a threshold signal, which is generated based on a difference voltage between an output voltage of the resonant converter and a target voltage, and which indicates a ration of the drive time interval to the pause time interval, and a logical operation means for generating a drive control signal based on the comparison signal and the rectangular wave signal to drive and control the resonant converter.