Series-Pass Power Factor Correction Circuit for Harmonic Reduction
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Solution Overview
Problem
Power electronic systems face reduced power factor and significant harmonic distortion due to current ripples induced by switching converters, which existing correction circuits are unable to fully address, especially when operating at discontinuous conduction mode, leading to increased filter size requirements and reduced power density.
Innovation Solution
A power factor correction circuit utilizing a series-pass device, such as a bipolar junction transistor, controlled by a feedback mechanism that regulates the operating point between active and saturation regions to reduce harmonic distortion and improve power factor, eliminating the need for large passive filters and increasing power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching converters are used for power conversion, then power conversion efficiency is improved, but current ripples are induced causing reduced power factor and significant harmonic distortion
Solution Approach 1:
A series-pass device (transistor) is introduced as an intermediary component between the power source and the switching converter. This mediator actively shapes the input current waveform by controlling the series-pass device's conduction angle and duty cycle, thereby reducing harmonic distortion and improving power factor without compromising the switching converter's efficiency.
Solution Approach 2:
The invention changes the operating parameters of the series-pass device dynamically by adjusting its conduction angle and duty cycle based on the switching converter's operation. This parameter modulation allows the series-pass device to compensate for current ripples and harmonics, resolving the contradiction between efficiency and harmonic distortion.
2Object-generated harmful factors
If correction circuits are placed between power converters and power sources, then power factor is improved, but device complexity increases
Solution Approach 1:
The correction circuit is merged with the existing power conversion system by placing the series-pass device in series with the input of the switching converter. This integration approach combines the power conversion function and the power factor correction function into a single unified circuit, reducing overall system complexity compared to separate correction circuits.
Solution Approach 2:
The invention employs a feedback control mechanism where the operation of the series-pass device is controlled based on the switching converter's status. This feedback approach enables automatic adjustment of the correction circuit parameters, simplifying the control system while maintaining effective power factor correction.
3Object-generated harmful factors
If large passive filters are used to reduce current ripples, then harmonic distortion is reduced, but filter size increases and power density decreases
Solution Approach 1:
The invention replaces traditional large passive mechanical filters with an active electronic correction circuit based on a series-pass device. This substitution eliminates the need for bulky inductors and capacitors, achieving harmonic distortion reduction through active control rather than passive filtering, thereby maintaining high power density.
Solution Approach 2:
Instead of using fixed-parameter passive filters, the invention employs a series-pass device with dynamically adjustable parameters (conduction angle, duty cycle). This allows the correction circuit to adapt to varying operating conditions and effectively reduce harmonics without requiring large fixed-size filter components.
Data Source
AI summary
A power factor correction circuit for a power electronic system includes a series-pass device arranged to control an input characteristic of a power converter, and a control mechanism arranged to control an operation of the series-pass device during a power conversion process. The correction circuit increases a power factor of the power electronic system and/or reduces a harmonic distortion generated by the power converter to an electrical current supplied by a power source in the power electronic system.