Power Converter Control for ZVS Turn-On and Output Precharge
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Solution Overview
Problem
Existing power converters struggle to achieve zero voltage switching (ZVS) turn on without additional auxiliary components, while also protecting connected devices from inrush currents by precharging output capacitors.
Innovation Solution
A voltage output circuit comprising a power converter and a controller, which increases current through a first transistor to reach a desired output voltage, then turns off the transistor to zero the drain-to-source voltage of a second transistor, allowing it to turn on in ZVS mode, and precharges an output capacitor to protect connected devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If additional auxiliary components are added to achieve ZVS turn on, then switching power loss is reduced, but device complexity increases
Solution Approach 1:
The patent employs the self-service principle by utilizing the converter's own transformer leakage inductance and output capacitor to achieve ZVS turn-on conditions. The controller monitors the voltage across the semiconductor switch and detects when it reaches zero, then triggers the turn-on event. This eliminates the need for external auxiliary components like active clamps or resonant inductors, as the converter's inherent components perform the soft-switching function.
2Object-affected harmful factors
If output capacitor is precharged to protect connected devices, then inrush current is limited, but additional control circuitry is required
Solution Approach 1:
The patent merges the precharge function with the main power conversion operation by using the same semiconductor switch and transformer components. The controller integrates precharge detection and main power transfer control into a single control loop, monitoring the voltage across the switch to determine both precharge completion and ZVS turn-on timing. This unified approach eliminates the need for separate precharge circuitry and reduces overall system complexity.
3Productivity
If current through first transistor is increased to achieve desired output voltage, then power conversion efficiency increases, but switching losses increase without ZVS
Solution Approach 1:
The patent implements feedback control by continuously monitoring the voltage across the semiconductor switch and using this information to determine the optimal turn-on timing. The controller detects when the switch voltage reaches zero (indicating the transformer has transferred sufficient energy to charge the output capacitor) and triggers the turn-on event at this precise moment. This feedback mechanism ensures ZVS conditions are met while maintaining high power conversion efficiency.
Data Source
AI summary
A voltage output circuit and methods for operating voltage output circuits are disclosed. In some embodiments, a voltage output circuit comprises a power converter and a power converter controller, and is configured to provide a desired output voltage for charging an output. In some embodiments, the power converter comprises a first transistor and a second transistor. By using the power converter controller to control the power converter, a current through the first transistor may be increased until it reaches a value corresponding to the desired output voltage. When the value is reached, the first transistor may be turned off to cause a drain-to-source voltage of the second transistor to become zero. When the drain-to-source voltage of the second transistor becomes zero, the second transistor turns on, and an output of the power converter is charged to the desired output voltage.