AC to DC Converter with Current Steering PFC
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional AC to DC power converters with power factor correction (PFC) capabilities suffer from high harmonic input currents and inefficiency, which are not optimal for many applications.
Innovation Solution
The design incorporates a PFC front end with current steering circuitry, such as 3C&6D or 2C&3D networks, and valley filling circuitry, connected to a DC/DC converter that presents pure resistive input impedance, reducing switching losses and harmonic components in the input current waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional PFC circuits are used, then power factor correction is achieved, but input current harmonics are high
Solution Approach 1:
The PFC circuit is divided into multiple independent phases (three-phase configuration), where each phase processes a portion of the input current. This segmentation allows each phase to operate with reduced current stress, resulting in lower harmonic generation per phase while collectively achieving superior power factor correction compared to conventional single-phase designs.
2Loss of energy
If PFC front end is implemented, then power factor is improved, but switching losses increase
Solution Approach 1:
The circuit employs periodic valley-filling switching action where the switch operates only during specific intervals (valley regions) of the AC cycle rather than continuously. This periodic operation reduces the total switching events and duration, thereby minimizing switching losses while still achieving effective power factor correction during the active periods.
Solution Approach 2:
The valley-filling circuit selectively activates switching action only during specific local regions (valley portions) of the input voltage waveform where it is most effective. By concentrating switching activity in these localized time regions rather than uniformly across the entire cycle, the circuit achieves power factor correction with reduced overall switching losses.
3Object-generated harmful factors
If current steering circuitry is added, then harmonic reduction is achieved, but device complexity increases
Solution Approach 1:
The current steering circuitry is integrated with the three-phase PFC structure by combining the valley-filling switch with the existing phase-leg components. The current steering function is achieved by strategically placing switches and diodes within the three-phase bridge configuration, merging multiple functions (PFC, current steering, and phase control) into a unified circuit topology rather than adding separate independent circuits.
Data Source
AI summary
An input current shaping AC to DC converter with PFC front end that reduces input current harmonics is provided. In one embodiment, an AC to DC converter connectable with an alternating current source and operable to output a direct current has a PFC front end followed by a DC/DC converter. The PFC front end reduces harmonic components present in an input current waveform received by the PFC front end from the alternating current source and includes current steering circuitry and, optionally, valley filling circuitry. The DC/DC converter is one that presents pure resistive input impedance to the PFC front end. The DC/DC converter outputs the direct current to a load connected thereto.