DC to DC Converter Active Clamping Circuit
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Solution Overview
Problem
Traditional DC to DC converters face limitations in power converting efficiency and stability due to surge voltage and switching losses, especially when dealing with varying load conditions and input voltages, which affects the circuit's reliability and efficiency.
Innovation Solution
A DC to DC converting circuit is designed with a transforming unit, bridge rectifier, clamping unit, and active switches to actively clamp surge voltages, utilizing an auxiliary switch and clamping capacitor to feed back energy and reduce power loss, thereby improving efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional full-bridge or half-bridge DC to DC converter is used, then voltage conversion function is achieved, but surge voltage is generated between drain electrode and source electrode due to inductance loss and switch imbalance, decreasing circuit stability and reliability
Solution Approach 1:
The patent introduces a clamping circuit as an intermediary component between the bridge rectifier and the transforming unit. This clamping circuit includes a clamping capacitor and a clamping switch that actively clamp the surge voltage generated during switching transitions. The clamping circuit absorbs the harmful surge voltage through the capacitor while the clamping switch controls the discharge path, thereby protecting the main switches from voltage spikes and improving circuit reliability without affecting the voltage conversion function.
2Loss of energy
If switching frequency is increased to reduce switching loss, then zero voltage switching condition is achieved, but larger frequency range is required for tuning output of large load and output cannot be well tuned in zero load condition
Solution Approach 1:
The patent employs dynamic control of the clamping switch timing based on real-time detection of switching conditions and load status. The control circuit adjusts the clamping switch turn-on moment dynamically - turning it on earlier when load is heavy to assist with voltage clamping during high current transitions, and adjusting timing when load is light to maintain proper voltage conversion. This dynamic adaptation allows the circuit to maintain efficient zero voltage switching across the full load range while preserving output tuning capability.
3Reliability
If operation cycle and parameters are tuned to achieve holding time period in low input voltage condition, then voltage stability is improved, but power converting efficiency is sacrificed
Solution Approach 1:
The patent implements a feedback control mechanism where the control circuit continuously monitors the input voltage level and the output voltage status. When low input voltage is detected, the control circuit automatically adjusts the operation cycle and duty ratio of the main switches to maintain proper voltage conversion and holding time period. Simultaneously, the clamping circuit is activated to manage surge voltage during these adjusted switching cycles. This feedback-based adaptive control allows the circuit to maintain voltage stability across varying input conditions while minimizing efficiency loss by optimizing switching parameters rather than using fixed conservative settings.
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 effectively reduces surge voltage and enhances power converting efficiency by using active clamping technology to manage switching losses and maintain circuit stability across varying load conditions.
Implementation Method 1
a clamping capacitor coupled between the auxiliary switch and the ground terminal
Implementation Method 2
a transforming unit with a primary winding and a secondary winding
Data Source
AI summary
The invention provides a DC to DC converting circuit, comprising: a transforming unit with a primary winding and a secondary winding; a bridge rectifier unit coupled to an input voltage, having a first output terminal and a second output terminal coupled to both side of the primary winding respectively; a first switch coupled between the input voltage and the first output terminal; a second switch coupled between the first output terminal and a ground terminal; a third switch coupled between the input voltage and the second output terminal; and a fourth switch coupled between the second output terminal and the ground terminal; an output unit paralleled to the secondary winding; and a clamping unit coupled to the input voltage and paralleled to the bridge rectifier unit, having an auxiliary switch coupled to the input voltage; and a clamping capacitor coupled between the auxiliary switch and the ground terminal; wherein the auxiliary switch is turned on when operation statuses of the first switch and the fourth switch or the second switch and the third switch are changed.