PCB Shielding for Uniform Voltage in HV Doubler Strings
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Solution Overview
Problem
In high voltage DC power supplies, non-uniform voltage distribution across capacitors and diodes due to stray capacitance leads to voltage stress, potentially causing premature component failure, and existing solutions are costly and complex to implement.
Innovation Solution
The use of shields with specific dimensions and placements on a printed circuit board to compensate for stray capacitance, ensuring a more uniform voltage distribution across capacitors and diodes by capacitive coupling, thereby reducing voltage stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage doubler circuit uses multiple capacitors and diodes in series to achieve high voltage output, then cost is reduced and component ratings are lowered, but non-uniform voltage distribution occurs across components due to stray capacitance
Solution Approach 1:
A compensation capacitor is introduced as an intermediary component connected in parallel with selected capacitors in the series string. This compensation capacitor specifically targets and counteracts the stray capacitance effects, redistributing voltage more uniformly across all capacitors and diodes without requiring complex circuit reconfiguration or additional active control elements.
2Reliability
If shields are added to improve voltage uniformity, then component lifespan is extended, but device complexity and manufacturing cost increase
Solution Approach 1:
The harmful effect of stray capacitance is extracted and isolated by introducing a dedicated compensation capacitor that specifically addresses the voltage distribution issue. This approach separates the voltage uniformity function from the main power processing components, allowing the shields and compensation elements to be added as discrete, manageable additions rather than requiring complete system redesign.
3Stress or pressure
If compensation capacitor is added to equalize voltage distribution, then voltage stress on components is reduced, but device complexity increases
Solution Approach 1:
The compensation capacitor is strategically placed in parallel with specific capacitors in the series string based on their position and the local voltage distribution requirements. This localized approach targets the specific areas where voltage stress is highest due to stray capacitance effects, providing precise stress reduction without adding compensation elements throughout the entire circuit.
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 achieves a nearly linear voltage distribution across components, reducing voltage stress by up to 25% and extending the lifespan of high voltage power supply components.
Implementation Method 1
ensuring a more uniform voltage distribution across capacitors and diodes by capacitive coupling
Data Source
AI summary
A high voltage power supply is disclosed. The high voltage power supply comprises a primary winding and one or more secondary windings. In one embodiment, a single secondary winding is used and the high voltage doubler circuit comprises a capacitor string and a diode string. In another embodiment, a plurality of secondary windings are used and the high voltage doubler circuit comprises a plurality of low voltage doubler circuits arranged in series. To create a more uniform distribution of voltage across the capacitors in the high voltage doubler circuit, one or more shields are disposed on the printed circuit board. In certain embodiments, a high voltage shield is disposed at the high voltage output and a low voltage shield is disposed at the low voltage end of the high voltage doubler circuit. One or more intermediate shields may be disposed in the high voltage doubler circuit.