Non-Isolated Resonant Converter Bootstrap Driving Circuit
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Solution Overview
Problem
Conventional resonant converters require isolation through transformers, which can complicate the design and increase costs, while non-isolated resonant converters lack efficient driving circuits to manage switching devices effectively.
Innovation Solution
A non-isolated resonant switching converter is designed with a transformer, a resonant tank, and multiple switching devices driven by integrated driver ICs. The driver ICs provide controlled driving signals to manage the switching devices, utilizing boot capacitors for power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a transformer is used for voltage conversion, then voltage scaling is achieved, but device complexity and cost increase due to isolation requirements
Solution Approach 1:
The patent extracts the isolation function from the voltage conversion function. By separating the galvanic isolation requirement from the resonant conversion topology, the design uses a standard transformer for isolation while implementing a non-isolated resonant converter topology for efficient power conversion. This allows voltage scaling without the complexity of isolated resonant converter designs.
Solution Approach 2:
The resonant tank circuit serves multiple functions: it provides soft switching for reduced losses, enables voltage scaling through resonance, and works with standard switching devices. The driver circuit integrates multiple control functions in a single IC, managing multiple switching devices simultaneously while providing built-in bootstrap functionality for gate drive voltage generation.
2Loss of energy
If multiple switching devices are used for resonant conversion, then conversion efficiency is improved, but ease of operation deteriorates due to complex driving requirements
Solution Approach 1:
The patent merges multiple driving functions into a single integrated driver IC. The driver circuit controls multiple switching devices (main switch, auxiliary switch, and body diode) simultaneously, integrating bootstrap capacitor control, gate drive voltage generation, and timing synchronization in one component. This simplifies the overall system while maintaining the efficiency benefits of multi-device resonant conversion.
Solution Approach 2:
The driver IC incorporates self-service functionality through integrated bootstrap capacitors that automatically generate the required gate drive voltage during operation. The driver monitors its own power supply status and self-regulates the switching sequence, reducing the need for external control circuitry and simplifying operation.
3Ease of manufacture
If boot capacitors are used for driver power supply, then ease of manufacture is improved, but reliability may worsen due to charging management complexity
Solution Approach 1:
The driver IC incorporates feedback mechanisms to monitor the charge status of bootstrap capacitors and adjust the switching sequence accordingly. The circuit detects when bootstrap capacitors are fully charged and uses this information to timing the activation of switching devices, ensuring reliable operation while maintaining simple manufacturing implementation.
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 configuration allows for efficient operation of non-isolated resonant converters by effectively managing switching devices and power supply, thereby simplifying the design and reducing costs while maintaining high conversion efficiency.
Implementation Method 1
The resonant tank circuit filters the harmonics of the square wave, resulting in a sinusoidal current
Implementation Method 2
A transformer may be employed to scale a voltage presented on the primary winding of the transformer
Implementation Method 3
The rectified output of the rectifier is filtered by an output capacitor to generate the DC output voltage
Data Source
AI summary
A non-isolated resonant switching converter has a transformer, a resonant tank, a first switching device coupled between an input node and the resonant tank, a second switching device coupled between the resonant tank and a secondary winding of the transformer, and a third switching device coupled between the secondary winding and the ground. The third switching device is driven by a first driver, the second switching device is driven by a second driver, and the first switching device is driven by a third driver. When the first and third switching devices are turned on and the second switching device is turned off, a first capacitor used to power the second driver is charged. When the first and third switching devices are turned off and the second switching device is turned on, a second capacitor used to power the third driver is charged by the first capacitor.