Zero Voltage Switching Power Converter with Bi-directional Switch
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Solution Overview
Problem
Existing power converter technologies face challenges in achieving zero voltage switching (ZVS) across a wide range of load and input voltage conditions, leading to increased switching losses as switching frequency increases, and previous solutions either require frequency adjustments or are not applicable to various converter topologies.
Innovation Solution
The implementation of a bi-directional switch and magnetically coupled electric coils allows for zero voltage switching by controlling the current flow to maintain a short circuit condition across the electric coil, ensuring zero voltage switching without additional bandwidth constraints, and recycling energy to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switching frequency is increased to reduce power supply size and improve dynamic response, then productivity and speed are improved, but switching losses increase due to finite switching transient duration and non-zero voltage across switches
Solution Approach 1:
The circuit performs preliminary action by pre-charging the switch capacitance through the electric coil current before the switch is turned on. This ensures that when the switch closes, the voltage across it is already at or near zero, eliminating switching losses without requiring frequency adjustment. The bi-directional switch and associated circuitry prepare the voltage condition in advance of the main switching event.
2Loss of energy
If zero voltage switching is achieved by adjusting operating frequency with reduced load, then switching losses are reduced, but the peak to peak current in the electric coil becomes independent of load and large current circulates between input and output
Solution Approach 1:
The invention introduces a bi-directional switch as an intermediary element that decouples the zero voltage switching condition from the electric coil current magnitude. This intermediary allows the main power switch to achieve ZVS through controlled current paths without being directly dependent on the electric coil's peak-to-peak current, thereby preventing large circulating currents while maintaining reduced switching losses.
3Loss of energy
If zero voltage switching is achieved through specific clamp phase arrangement and timing, then switching losses are reduced, but the solution is not applicable to a broad range of converters
Solution Approach 1:
The invention achieves universality by designing a zero voltage switching circuit with a bi-directional switch and capacitor that can be integrated into multiple converter topologies including forward, push-pull, half-bridge, and full-bridge converters. The circuit's ability to source or sink current bidirectionally and its placement across the electric coil make it adaptable to various converter architectures without requiring topology-specific modifications, thereby reducing switching losses across a broad range of converters.
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 enables zero voltage switching across a wide range of load and input conditions, reducing switching losses and maintaining efficiency by recycling energy, thus allowing for smaller power supplies with faster dynamic response.
Implementation Method 1
magnetically coupled electric coils allows for zero voltage switching by controlling the current flow
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A power converter constituted of: a control circuitry; a first electric coil; a first electronically controlled switch associated with the first electric coil and responsive to the control circuitry, the first electronically controlled switch arranged to charge the first electric coil responsive to a closed state of the first electronically switch; and a second electronically controlled switch arranged to present a substantially short circuit across the first electric coil when the second electronically controlled switch is closed, the second electronically controlled switch responsive to the control circuitry and not arranged to either charge or discharge the first electric coil.