Resonant Converter Light Load Efficiency Control
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Solution Overview
Problem
Resonant converters, such as LLC resonant converters, experience low efficiency in light load conditions due to constant driving and switching losses, despite reduced conduction losses, as they operate with open loop control and fixed switching frequency.
Innovation Solution
A resonant converter design that includes a control circuit to generate control signals based on load current, blocking these signals when the load current falls below a light load threshold until the output voltage reaches a preset value, allowing the power stages to enter a sleep mode and reducing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop control with fixed switching frequency is used, then circuit complexity is reduced, but light load efficiency deteriorates
Solution Approach 1:
The control circuit implements dynamic frequency adjustment while maintaining relatively simple circuit architecture. By using a dual-frequency approach with load detection, the system achieves adaptive optimization without requiring complex control algorithms, thus balancing simplicity with efficiency improvement.
Solution Approach 2:
The patent changes the switching frequency parameter based on load conditions detected by the control circuit. This parameter adaptation allows the system to maintain good efficiency across different operating conditions while keeping the control circuit design relatively straightforward, avoiding the need for complex closed-loop control systems.
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 efficiency by minimizing power loss during light load conditions by dynamically controlling the operation of the power stages based on load current, thereby improving overall converter performance.
Implementation Method 1
a LLC resonant net, a transformer and an output power stage, coupled between the input power stage and an output port, to generate an output voltage
Data Source
AI summary
A resonant converter highly improves light load efficiency. The resonant converter blocks control signals which are used to control power switches in an input power stage and an output stage in light load condition until an output voltage drops to a preset value. The input power stage and the output stage are coupled by way of a resonant net and a transformer.