LLC Power Converter Control for Multiple Output Voltages
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Solution Overview
Problem
Existing power converter designs, particularly those using the LLC topology, struggle to efficiently provide multiple output voltages due to their optimal efficiency at resonant frequency points, which requires stable input and output voltages.
Innovation Solution
The power converter incorporates a primary-side rectifying/filtering circuit, a DC converter, a DC-DC converter, a primary-side controller, a secondary-side rectifying controller, and a secondary-side feedback controller to dynamically adjust and control the conversion process, allowing operation in half-bridge or full-bridge topologies and flexible output voltage generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If LLC topology is used to operate at resonant frequency for zero voltage switching, then power conversion efficiency is improved and magnetic component size is reduced, but the ability to provide multiple output voltages is limited
Solution Approach 1:
The patent applies dynamics by making the circuit topology configurable between half-bridge and full-bridge modes, and by dynamically adjusting the operating frequency away from the fixed resonant frequency. This allows the system to adapt to different output voltage requirements while maintaining efficient operation through controlled frequency deviation and topology switching.
Solution Approach 2:
The patent changes key operating parameters including switching frequency (operating away from resonant frequency), circuit topology (half-bridge vs full-bridge), and duty cycle to provide multiple output voltages. By adjusting these parameters, the system can deliver different voltage levels (e.g., 12V, 24V, 48V) while maintaining power conversion efficiency.
2Reliability
If stable input and output voltages are maintained at resonant frequency point, then power conversion efficiency is improved, but flexibility in output voltage generation is reduced
Solution Approach 1:
The system maintains stability through dynamic control mechanisms that adjust switching parameters and topology based on desired output voltage. The controller dynamically modifies duty cycle and switching frequency while transitioning between half-bridge and full-bridge modes, ensuring stable operation across multiple voltage outputs without being constrained to a fixed resonant frequency.
3Ease of operation
If LLC topology operates at fixed resonant frequency, then zero voltage switching is achieved, but the size of magnetic components cannot be optimized for multiple voltage outputs
Solution Approach 1:
The patent changes the operating frequency parameter away from the fixed resonant frequency to enable multiple output voltages. By operating at adjustable frequencies and switching between topologies, the system maintains soft switching benefits while allowing magnetic components to be optimized for a broader voltage range, reducing their size and improving overall system efficiency.
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 design enables the power converter to efficiently operate across a wider range of output voltages by using different winding turns ratios of the inductors, thereby improving power conversion efficiency and reducing the need for large capacitors, which is beneficial for miniaturized systems.
Implementation Method 1
The primary-side rectifying/filtering circuit receives an input voltage, and rectifies and filters the input voltage into an adjusted input voltage
Implementation Method 2
The primary-side rectifying/filtering circuit receives an input voltage, and rectifies and filters the input voltage into an adjusted input voltage
Implementation Method 3
The DC converter is coupled to the primary-side rectifying/filtering circuit, and receives the adjusted input voltage
Implementation Method 4
The secondary-side rectifying controller is coupled to the DC-DC converter, and provides a third control signal to control the DC-DC converter to convert the DC input voltage into a conversion voltage to supply power to a load
Implementation Method 5
LLC has the characteristic of zero voltage switching, which enables the power supply products to operate at higher frequencies, thereby reducing the size of the magnetic components
Data Source
AI summary
A power converter includes a primary-side rectifying/filtering circuit, a DC converter, a DC/DC converter, a primary-side controller, a secondary-side rectifying controller, and a secondary-side feedback controller. The primary-side rectifying/filtering circuit receives an input voltage, and rectifies and filters the input voltage into an adjusted input voltage. The DC converter receives the adjusted input voltage. The primary-side controller provides a first control signal to control the DC converter to convert the adjusted input voltage into a DC input voltage, and provides a second control signal to control the DC-DC converter. The secondary-side rectifying controller provides a third control signal to control the DC-DC converter to convert the DC input voltage into a conversion voltage to supply power to a load according to a gain condition. The secondary-side feedback controller receives a power demand signal provided by the load to control the primary-side controller and the secondary-side rectifying controller.