Resonant Converter Driver Device for High Power Factor LED Applications
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Solution Overview
Problem
Existing driver devices for LED units face challenges in achieving high efficiency and small size while maintaining high power factors and safety isolation, as current technologies like fly-back converters and resonant converters suffer from low power density, high costs, and limited gain ratios.
Innovation Solution
A driver device utilizing a resonant converter with a switch unit and control unit to control the pulse frequency of the chopped voltage, allowing for Power Factor Correction (PFC) operation by adjusting the input current based on measured input voltage values, thereby leveraging the efficiency and compactness of resonant converters like LLC converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fly-back converters are used for isolated PFC stages, then high gain ratios are achieved, but power density and efficiency are too low
Solution Approach 1:
The patent changes the operating parameters by using a resonant converter instead of a fly-back converter, operating at or near resonance frequency to achieve both high gain ratio and high efficiency simultaneously. The resonant operation allows for soft switching that reduces semiconductor losses while maintaining the required voltage transformation ratio.
2Power
If fly-back converters are used for isolated PFC stages, then high gain ratios are achieved, but power density is too low
Solution Approach 1:
The patent transitions from fly-back converter parameters to resonant converter parameters, operating at resonance frequency to achieve high power density. The resonant operation enables higher switching frequencies and reduced component sizes, thereby increasing power density while maintaining the required gain ratio for PFC operation.
3Loss of energy
If resonant converters are used for isolated PFC stages, then high efficiency is achieved, but device complexity increases due to additional electromagnetic components
Solution Approach 1:
The patent combines the PFC function and isolation function into a single resonant converter stage. By merging these two functions that would traditionally require separate stages, the design achieves high efficiency PFC operation with isolation without requiring additional electromagnetic components, thus reducing overall device complexity.
Solution Approach 2:
The resonant converter is designed to perform multiple functions simultaneously: power factor correction, voltage transformation, and electrical isolation. This multi-functionality eliminates the need for separate dedicated components for each function, reducing the total number of electromagnetic components while maintaining high efficiency.
4Ease of manufacture
If class E converters are used for high power factor operation, then power factor is improved, but voltage stress on power transistor exceeds device limits
Solution Approach 1:
The patent employs resonant vibration at or near the resonant frequency of the LC tank circuit to achieve soft switching conditions. This resonant operation creates a sinusoidal current waveform that naturally limits voltage stress on the power transistor while maintaining high power factor, avoiding the excessive voltage spikes characteristic of class E converters.
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 high-efficiency and compact PFC operation, achieving high power factors with reduced technical effort and cost, by controlling the input current in phase with the input voltage, thus overcoming the limitations of traditional driver devices.
Implementation Method 1
a resonant converter for converting the input voltage to an output voltage
Implementation Method 2
a switch unit adapted to provide a chopped voltage of the input voltage as a drive voltage to the resonant converter, and a control unit connected to the switch unit for controlling a pulse frequency of the chopped voltage
Data Source
AI summary
A driver device (10) for driving a load (22), in particular for driving an LED unit comprising one or more LEDs is presented. The driver device comprises input terminals (12, 14) for connecting the driver device to an electrical power supply (16) for receiving a variable input voltage (V10) from the electrical power supply, a converter unit (25) for converting the input voltage (V10) to an output voltage (V12) including a resonant converter (40) and a switch unit (26), wherein the switch unit is adapted to provide a chopped voltage of the input voltage as a drive voltage (V16) to the resonant converter, and a control unit (34) connected to the switch unit for controlling a pulse frequency (fP) of the chopped voltage, wherein the control unit is adapted to control an input current (I10) drawn from the electrical power supply by controlling the pulse frequency of the chopped voltage on the basis of a measured value of the variable input voltage.