Multi-zone burst modulation for resonant converters
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Solution Overview
Problem
Resonant switched mode power converters, such as LLC converters, face challenges in reducing power consumption at no load or low load conditions and minimizing audible noise and mechanical resonance, which affect efficiency and noise emission.
Innovation Solution
Implementing a multi-zone burst control mechanism that adjusts the burst frequency below the audible noise frequency and transformer mechanical resonance range, transitioning through modes such as intermediate burst, light load burst, and super light load burst based on load conditions to optimize energy transfer and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional PWM or PFM control is used in resonant converters, then output regulation is achieved, but power loss increases and efficiency decreases at no load or low load conditions
Solution Approach 1:
The patent implements burst mode control where the converter operates in periodic cycles of active switching followed by idle periods. At no load or low load conditions, the converter enters burst mode where switching occurs only during 'on' periods separated by 'off' periods, reducing average power consumption and improving efficiency compared to continuous PWM or PFM operation
Solution Approach 2:
The patent dynamically transitions between different operating modes (full mode, intermediate burst mode, light load burst mode, super light load burst mode) based on load conditions. The controller adjusts switching frequency and duty cycle in real-time, enabling the system to optimize efficiency across varying load conditions rather than operating in a fixed mode
2Volume of moving object
If high switching frequency is used in resonant converters, then smaller magnetic elements can be utilized, but audible noise and mechanical resonance increase
Solution Approach 1:
The patent changes the switching frequency parameter dynamically based on operating mode. In full mode, higher switching frequencies are used to enable smaller magnetic elements. In burst modes, the switching frequency is adjusted to operate below the audible noise range and mechanical resonance frequency of the transformer, reducing noise while maintaining compact design through careful parameter selection
Solution Approach 2:
By implementing periodic burst mode operation, the patent reduces the average switching activity. The converter switches at high frequency during brief 'on' periods but remains idle during extended 'off' periods, reducing overall acoustic noise and mechanical vibration while still enabling the use of smaller magnetic components during active switching
3Loss of energy
If burst mode control is implemented to reduce power loss, then efficiency improves at light load, but audible noise and mechanical resonance may increase
Solution Approach 1:
The patent carefully selects and adjusts the switching frequency parameter in burst modes to operate below the mechanical resonance frequency of the transformer. By controlling the switching frequency to be lower than the resonance frequency during burst operation, the patent reduces mechanical vibration and audible noise while maintaining the efficiency benefits of burst mode control
Solution Approach 2:
The patent employs a control loop that monitors operating conditions and adjusts switching parameters accordingly. The controller receives feedback about load conditions and adjusts the switching frequency and duty cycle to maintain efficient operation while avoiding mechanical resonance and audible noise, creating a self-regulating system that balances efficiency and noise reduction
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 enhances power converter efficiency by minimizing power loss and noise emission, ensuring efficient operation across varying load conditions while maintaining low audible noise and mechanical resonance.
Implementation Method 1
resonant switched mode power converters, which utilizes a resonant inductance-capacitance (LC) circuit as part of the power conversion process
Implementation Method 2
a mechanical resonance frequency range of the energy transfer element of the power converter, and above an audible noise frequency
Data Source
AI summary
A power converter controller includes a control loop clock generator to generate a switching frequency signal responsive to a burst load threshold, a power signal, and a load signal. A switching frequency of the switching frequency signal is above a resonance range of an energy transfer element. A burst control circuit generates a burst on signal and a burst off signal in response to a feedback signal and a burst enable signal to operate the controller in a plurality of burst modes. A burst frequency of the burst on signal or the burst off signal is less than the resonance range of the energy transfer element. A request transmitter circuit generates a request signal responsive to the switching frequency signal, the burst on signal, and the burst off signal to control switching of a switching circuit.