Constant Current Power Factor Correction Circuit
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Solution Overview
Problem
Existing power factor correction techniques are designed for constant voltage systems and cannot be effectively applied to constant current systems, such as those used in airfield lighting, where consistent brightness across multiple light fixtures requires a constant current power source.
Innovation Solution
A constant current power factor correction circuit that includes an input capacitor, a rectifier bridge, and a switching device controlled by a controller to match the input voltage waveform to the input current waveform, ensuring the voltage is in phase with the current and improving energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional voltage-based power factor correction circuitry is used, then power factor correction can be achieved in constant voltage systems, but it cannot be applied to constant current systems such as airfield lighting systems
Solution Approach 1:
The patent changes the fundamental operating parameter from voltage-based control to current-based control. The PFC circuit is redesigned to accept a constant current input source and uses current sensing and control mechanisms rather than voltage sensing, enabling adaptation to constant current systems while maintaining power factor correction functionality
Solution Approach 2:
The patent inverts the traditional PFC approach by making the input current waveform follow the input voltage waveform, rather than making the input voltage follow a reference. This is achieved by using a current-controlled switch that modulates the current drawn from the constant current source based on the voltage waveform, thereby achieving power factor correction in constant current systems
2Illumination intensity
If constant current power supply is used to provide consistent brightness across multiple light fixtures, then brightness uniformity is improved, but power factor correction cannot be implemented
Solution Approach 1:
The patent changes the control parameter from voltage to current, designing a PFC circuit that operates with a constant current input source. The circuit uses current sensing and a current-controlled switch to achieve power factor correction while maintaining the constant current requirement for uniform lighting across multiple fixtures
Solution Approach 2:
The patent implements feedback control by sensing the input voltage waveform and using it to control the switching of the current draw from the constant current source. This feedback mechanism ensures that the current waveform follows the voltage waveform, achieving power factor correction and improved energy efficiency while maintaining consistent brightness
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 effectively matches the voltage waveform to the input current waveform, enhancing energy efficiency and prolonging the life of the electric power system in constant current-based systems like airfield lighting.
Implementation Method 1
a rectifier bridge configured to receive the input current and full-wave rectify the input current
Implementation Method 2
an input capacitor configured to receive an input current from a constant current source and produce an input voltage
Implementation Method 3
a switching device coupled to the controller, wherein the switching device is switchable between a first state and a second state. When the switching device is in the first state, the input capacitor is charged from the input current and the input voltage rises, and when the switching device is in the second state, the input capacitor is drained and the input voltage drops
Data Source
AI summary
The present disclosure provides techniques for power factor correction on a constant current system. In an example embodiment, the present disclosure provides a power factor correction circuit which receives a constant current power input. The power factor correction circuit provides an input voltage tuned to match the phase of the input current. The input voltage is tuned via charging and draining an input capacitor by a switching device. The switching device is driven on a duty cycle synchronously associated with the input current waveform.