Switching Power Supply ZVS Control Circuit
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Solution Overview
Problem
Conventional switching power supplies, particularly those employing zero-voltage switching (ZVS) in high voltage environments, face complexity and high manufacturing costs due to the need for intricate driver transformer designs.
Innovation Solution
The proposed switching power supply and ZVS method involve an auxiliary circuit with a fixed turn-on time for the auxiliary switch, controlled by an auxiliary switch control circuit including a driver and timer, which fixes the turn-off time of the main switch, eliminating the need for a complex driver transformer and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ZVS detector IC is used to detect the main switch and drive the driver transformer to switch the auxiliary switch, then zero-voltage switching can be achieved, but the design becomes relatively complex and manufacturing cost increases
Solution Approach 1:
The patent extracts the complex driver transformer and ZVS detector IC from the system, replacing them with a simplified auxiliary switch control circuit that directly controls the auxiliary switch based on fixed timing, eliminating the need for high-voltage detection and complex driving mechanisms while maintaining ZVS functionality
Solution Approach 2:
The patent changes the control parameter from real-time voltage detection to fixed timing control, where the auxiliary switch control circuit determines the turn-on time of the auxiliary switch based on predetermined timing parameters, simplifying the control mechanism while achieving the same ZVS effect
2Reliability
If a conventional ZVS detector IC is used to detect the main switch and drive the driver transformer to switch the auxiliary switch, then zero-voltage switching can be achieved, but manufacturing cost increases
Solution Approach 1:
The patent removes the expensive ZVS detector IC and driver transformer components, replacing them with a cost-effective auxiliary switch control circuit that uses simple timing logic to achieve the same functional outcome, thereby reducing bill of materials cost
Solution Approach 2:
The patent replaces expensive, complex components with simpler, cheaper alternatives that achieve the same purpose, such as using basic timing circuits instead of sophisticated detection and transformation components, reducing overall manufacturing cost
3Reliability
If the turn-on time of the auxiliary switch is fixed through the auxiliary switch control circuit, then the turn-off time of the main switch is also fixed to accomplish ZVS, but this requires precise timing control
Solution Approach 1:
The patent implements preliminary timing setup in the auxiliary switch control circuit, where the turn-on time of the auxiliary switch is predetermined and configured in advance, which automatically determines the turn-off time of the main switch, ensuring precise timing without requiring complex real-time adjustments
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 simplifies the control method, reduces manufacturing costs, and achieves ZVS in both forward and flyback switching power supplies without the complexity of prior art designs.
Implementation Method 1
an auxiliary circuit having an auxiliary capacitor Ca and an auxiliary switch Q2 electrically connected to the auxiliary capacitor Ca in series, a transformer T having a primary side electrically connected to the auxiliary circuit in parallel
Implementation Method 2
a zero-voltage switching (ZVS) detector electrically connected to the first and the control terminals of the main switch
Data Source
AI summary
The provided switching power supply includes an auxiliary circuit having an auxiliary switch and a auxiliary capacitor, a transformer having a primary side coupled to the auxiliary circuit in parallel and a secondary side, an auxiliary switch control circuit coupled to the auxiliary switch and the primary side and fixing a turn-on time of the auxiliary switch, a main switch coupled to the primary side, a ZVS detector coupled to the main switch, a first and a second rectifying switches coupled to the secondary side and a filter circuit coupled to the second rectifying switch in parallel. The provided method includes the steps of: (a) fixing the turn-on time of the auxiliary switch; and (b) generating a fixed turn-off time of the main switch accordingly so as to accomplish ZVS of the main switch.