CLLC Resonant Converter On-Time Control for Wide Voltage Range
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Solution Overview
Problem
Conventional CLLC resonant converters experience inefficiencies due to significant changes in switching frequency, leading to increased decoupling time intervals and circulating currents, which affect efficiency and output voltage range.
Innovation Solution
A resonant converter with a switch on-time control mechanism that modulates on-times and switching frequencies of primary and secondary-side switch circuits, allowing operation in half-bridge and secondary-side delay conduction modes to extend power transmission time and increase output voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the switching frequency is significantly changed to realize a wide output voltage range and high voltage gain, then the output voltage range is improved, but the decoupling time interval is increased and circulating current increases
Solution Approach 1:
The patent applies dynamics by making the switching frequency adaptive rather than fixed. The control circuit dynamically adjusts the switching frequency based on real-time feedback from voltage and current sensors, allowing the system to optimize performance across different operating conditions while avoiding excessive circulating currents.
Solution Approach 2:
The patent changes the parameter of switching frequency from a significantly varied range to a moderately adjusted range around the resonant frequency. By combining moderate frequency adjustment with pulse-width modulation (PWM) of the switching duty cycle, the system achieves wide output voltage range without the harmful effects of extreme frequency deviations.
2Power
If the switching frequency is significantly changed to achieve high voltage gain, then the voltage gain is improved, but the difference between resonant frequency and switching frequency is increased
Solution Approach 1:
The patent utilizes periodic resonant oscillations at or near the natural resonant frequency of the LC circuit. By synchronizing the switching action with the resonant period and using PWM to control energy transfer, the system achieves high voltage gain through constructive resonance rather than through large frequency deviations.
Solution Approach 2:
The patent changes the approach from varying frequency significantly to varying the duty cycle of switching at a frequency close to resonance. This parameter change in control strategy allows high voltage gain through extended on-time of the switching elements while maintaining frequency proximity to resonance.
3Power
If the decoupling time interval is increased due to frequency deviation, then the voltage gain is improved, but the circulating current flowing through switch components is increased
Solution Approach 1:
The patent implements feedback control by continuously monitoring the output voltage and current, and using this information to adjust the switching duty cycle and frequency. The feedback mechanism detects when circulating current becomes excessive and automatically adjusts the switching parameters to reduce it, while maintaining the required voltage gain through duty cycle modulation.
Solution Approach 2:
The resonant circuit naturally provides self-regulation of circulating current through its resonant properties. By operating at or near the resonant frequency, the circuit's inherent impedance characteristics automatically limit circulating currents without requiring active intervention, while the control system only needs to adjust the duty cycle to achieve the desired output voltage.
4Adaptability or versatility
If the switching frequency is modulated to adjust output voltage, then the output voltage adjustment is improved, but the efficiency is affected due to loss of resonant energy
Solution Approach 1:
The patent applies dynamics by using real-time feedback to continuously optimize the switching duty cycle and frequency. The control circuit dynamically adjusts parameters to maintain operation at or near resonant conditions, minimizing energy loss while providing flexible output voltage adjustment through adaptive PWM control.
Solution Approach 2:
The patent changes the primary control parameter from significant frequency variation to duty cycle modulation at a frequency close to resonance. This parameter change reduces resonant energy loss because the circuit operates closer to its natural resonant frequency, while still achieving wide output voltage range through PWM of the switching elements.
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
The solution enables efficient power transmission and a wide output voltage range by reducing operational frequency range and increasing peak resonant current, maintaining efficiency even when operating beyond resonant frequency.
Implementation Method 1
A primary-side of the transformer is connected to the primary-side resonant circuit. A secondary-side of the transformer is connected to the secondary-side resonant circuit.
Implementation Method 2
The resonant converter having a switch on-time control mechanism. The resonant converter includes a primary-side switch circuit, a primary-side resonant circuit, a secondary-side switch circuit, a secondary-side resonant circuit
Data Source
AI summary
A resonant converter having a switch on-time control mechanism is provided. The resonant converter includes a primary-side switch circuit, a primary-side resonant circuit, a secondary-side switch circuit, a secondary-side resonant circuit, a transformer and a control circuit. In the resonant converter, the control circuit controls on-times and switching frequencies of the primary-side switch circuit and the secondary-side switch circuit to extend time within which power is transmitted from an input power source, the primary-side switch circuit, the primary-side resonant circuit and the transformer to the secondary-side resonant circuit, and stored in the secondary-side resonant circuit. As a result, the secondary-side resonant circuit is able to supply more power to a load.