Field Emission Power Supply Resonant Inverter Control

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Solution Overview

Problem

Existing power supplies for field emission light sources are inefficient and bulky, with voltage multipliers causing voltage spikes that can shorten the lifespan of the light source and limiting dimming capabilities due to size and efficiency issues.

Innovation Solution

A compact power supply with a control unit connected to a resonant inverter and voltage multiplier, using feedback signals to regulate the high voltage and frequency, allowing for smooth dimming and extended lifespan by adjusting the output power and using PWM control to manage voltage spikes, with a configuration that places circuit resonance on the secondary side of the transformer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a voltage multiplier with a large plurality of steps is used to provide high voltage for the field emission light source, then the required high voltage output (2-12 kV) is achieved, but the size of the power supply increases and efficiency decreases

Engineering Contradiction:
Improvehigh voltage outputVSAvoidpower supply size
Core Design Contradiction:
PowerVSVolume of stationary object

Solution Approach 1:

The patent changes the operating parameters of the voltage multiplier by optimizing the number of stages and the capacitance values to reduce voltage spike magnitude while maintaining the required 2-12 kV output. This allows achieving the necessary high voltage without requiring an excessive number of multiplier stages, thereby reducing the power supply size.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The control unit continuously monitors the output voltage and current from the voltage multiplier and adjusts the resonant inverter operating parameters in real-time to minimize voltage spikes. This feedback mechanism enables the system to maintain stable high voltage output while preventing harmful voltage transients, eliminating the need for oversized protective components.

Inventive Principle:
Principle #23Feedback

2Power

If a voltage multiplier with a large plurality of steps is used to provide high voltage, then the required voltage level is achieved, but the efficiency of the power supply decreases

Engineering Contradiction:
Improvehigh voltage outputVSAvoidpower supply efficiency
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent optimizes the voltage multiplier stage parameters and resonant inverter frequency to minimize energy losses. By carefully selecting the operating point and adjusting the resonant frequency, the system achieves high voltage conversion efficiency while maintaining the required 2-12 kV output level.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The control unit uses feedback from voltage and current sensors to dynamically adjust the resonant inverter switching frequency and duty cycle, maximizing power transfer efficiency and minimizing losses in the voltage multiplier stages while maintaining the required high voltage output.

Inventive Principle:
Principle #23Feedback

3Device complexity

If voltage spikes are not controlled in high voltage applications, then the power supply can be simpler, but the lifetime of the field emission light source is effectively limited and may burn out

Engineering Contradiction:
Improvepower supply complexityVSAvoidlight source lifetime
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The control unit continuously monitors the voltage multiplier output and uses feedback control to adjust the resonant inverter parameters, preventing voltage spikes that would damage the light source. This active control approach provides reliable protection without requiring complex passive suppression circuits.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control system proactively adjusts operating parameters before damaging voltage spikes can occur by monitoring trends and preemptively modifying the resonant inverter duty cycle or frequency, preventing light source damage before it happens rather than reacting after damage occurs.

Inventive Principle:
Principle #10Preliminary action

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 provides a compact, efficient power supply that minimizes light output variations, extends the lifespan of the field emission light source, and allows for precise dimming while maintaining electrical efficiency, reducing the risk of voltage spikes and improving power factor.

Implementation Method 1

an LLC resonant inverter (108) comprising a transformer, the resonant inverter connected to the output of the DC-DC converter (106) and configured to provide a pulsating signal at a first frequency having a third voltage level, the third voltage level being higher than the second voltage level

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

a voltage multiplier (110) rectifying the pulsating signal to a direct current at a fourth voltage level, the fourth voltage level being higher than the third voltage level

Methodology Applied
Scientific EffectRectification: Diode

Data Source

PatentEP2798919B1Power supply for a field emission light source
Publication Date: 2020.06.10 LIGHTLAB SWEDEN AB
  • EP2798919B1 patent drawingFigure 1~2
  • EP2798919B1 patent drawingFigure 3a
  • EP2798919B1 patent drawingFigure 3b

AI summary

The present invention relates to a power supply for a field emission light source. The novel power supply allows for a reduction in size as well as allowing for improvements relating to power factor and efficiency. The size reduction further allows the power supply to efficiently be integrated together with the field emission light source forming a lighting device.