LLC Resonant Power Regulator Constant Current Control
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Solution Overview
Problem
Existing power regulation systems face challenges in maintaining constant current output, especially under varying load conditions, leading to inefficiencies and potential damage from short-circuits or overloads.
Innovation Solution
An LLC resonant power converter system with a transformer, switch control stage, and a controller that generates switching signals to manage the duty-cycle and inductance, switching between normal resonance and constant-current operating modes to maintain a predetermined output current magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the power regulator operates in normal resonance mode to achieve high efficiency and low switching loss, then power efficiency is improved, but the output current cannot be maintained constant under varying load conditions
Solution Approach 1:
The system dynamically switches between normal resonance mode and constant current mode based on load conditions. The controller monitors output current and adjusts the operating mode accordingly, making the system adaptive rather than static. This resolves the contradiction by allowing the system to optimize for efficiency under light loads while ensuring constant current under varying loads.
Solution Approach 2:
The controller changes the operating parameters of the power regulator by switching between different modes (normal resonance mode with 50% duty cycle and constant current mode with adjusted duty cycle). This parameter change allows the system to maintain constant output current while preserving the efficiency benefits of resonant operation when applicable.
2Reliability
If the duty-cycle is increased to maintain constant output current under heavy loads, then current stability is improved, but power losses increase
Solution Approach 1:
The system uses dynamic mode switching to adjust the duty-cycle appropriately. In normal resonance mode, a fixed 50% duty cycle maintains efficiency. When constant current mode is activated, the duty-cycle is dynamically adjusted only to the extent necessary to maintain current stability, avoiding excessive power losses.
Solution Approach 2:
The controller applies partial action by switching to constant current mode only when necessary (when output current exceeds the reference current), rather than continuously operating in high-duty-cycle mode. This prevents excessive power losses while still maintaining current stability when needed.
3Device complexity
If the system operates without constant current control to maintain simplicity, then device complexity is reduced, but protection against short-circuits and overloads is compromised
Solution Approach 1:
The system implements feedback control by monitoring the output current and comparing it with a reference current. The controller uses this feedback to determine when to switch to constant current mode, providing protection against short-circuits and overloads. This feedback mechanism adds minimal complexity while significantly improving safety.
Solution Approach 2:
The constant current control mode acts as a preliminary protective measure against harmful effects. By detecting current exceeds the reference current and switching modes proactively, the system prevents short-circuit damage and overload conditions before they can cause harm, rather than reacting after damage occurs.
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 system effectively stabilizes and maintains a constant output current, reducing power losses and preventing damage from short-circuits or overloads by adjusting the duty-cycle and inductance, ensuring efficient operation across varying loads.
Implementation Method 1
a resonant tank that conducts an oscillating resonant current based on a power storage interaction between a capacitor and an inductor, such as in a primary inductor of a transformer. The oscillating resonant current can be generated based on the operation of the switches, and can thus induce a current in a secondary inductor of the transformer.
Implementation Method 2
a resonant tank that conducts an oscillating resonant current based on a power storage interaction between a capacitor and an inductor
Data Source
AI summary
One embodiment relates to an LLC resonant power converter system. The system includes a transformer comprising a primary inductor and a secondary inductor and a switch control stage configured to generate a plurality of switching signals having a duty-cycle. The system also includes an input stage comprising the primary inductor and a plurality of switches that are controlled in response to the respective plurality of switching signals to generate a primary resonant current and an output stage comprising the secondary inductor and being configured to conduct an output current through a load based on a secondary resonant current to generate an output voltage. The system further includes a controller configured to limit a magnitude of the output current to a predetermined magnitude in response to variations of the load.