Switching Converter Valley Control for Zero-Voltage Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switching converters face inefficiencies due to hard switching when the input voltage approaches the output voltage, resulting in significant switching loss, as the voltage across the power switch cannot decrease to zero, leading to suboptimal performance in certain conditions.
Innovation Solution
A control circuit and method for a switching converter that includes a compensating circuit and a sync switch control circuit, which generate signals to control the sync switch, allowing zero-voltage switching by turning on the sync switch at a valley of the voltage across it and turning it off after a specific time period, thereby reducing switching loss and improving efficiency, especially in discontinuous conduction mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional zero-voltage switching control is used, then switching loss is reduced under normal conditions, but switching loss increases significantly when input voltage approaches output voltage
Solution Approach 1:
The patent implements dynamic switching control by detecting whether the switching converter operates in CCM or DCM and adapting the sync switch control strategy accordingly. In CCM, the sync switch is turned off when inductor current reaches zero, while in DCM, it is turned off after a predetermined time period from the valley of the sync switch voltage, enabling optimal performance across different operating conditions
Solution Approach 2:
The control method changes the timing parameter for turning off the sync switch based on the operating mode. In CCM, the turn-off timing is tied to inductor current zero-crossing, while in DCM, it is tied to a fixed time delay from the voltage valley, allowing the system to adapt to different voltage conditions and maintain low switching loss
2Loss of energy
If the sync switch is turned on at the valley of its voltage, then zero-voltage switching is achieved, but the control complexity increases
Solution Approach 1:
The control circuit automatically detects the valley of the sync switch voltage and uses this detection to trigger the turn-on command, enabling the system to achieve zero-voltage switching without requiring external intervention or complex additional circuitry. The system self-regulates based on its own voltage characteristics
Data Source
AI summary
A control method for a switching converter with a main switch and a sync switch and converting an AC (alternating current) input voltage into an output voltage. The control method includes the following steps. 1) Determining whether the switching converter works in DCM or CRM. 2) When the switching converter works in CRM, turning off the sync switch when a first time period started from the time when an inductor current decreases to zero expires. 3) Turning on the main switch at a valley of a voltage across the main switch. And 4) turning off the main switch when an on time of the main switch reaches a second time period, where the second time period is related to the first time period.