Digital Power Factor Correction Controller for Poly-Phase AC to DC Conversion
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Solution Overview
Problem
Existing power conversion technologies face challenges in efficiently converting poly-phase AC to DC while maintaining a near-unity power factor, requiring large components and significant filtering, and lacking effective digital solutions for soft-start applications.
Innovation Solution
A digital power factor correction (DPFC) controller using Field Programmable Gate Arrays (FPGAs) with pulse width modulation (PWM) and full-wave rectification, employing a sine-squared modulation scheme to reduce harmonic currents and minimize filtering requirements, achieving efficient AC to DC conversion with reduced component size and soft-start capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional rectifier circuits are used for AC to DC conversion, then power factor correction is achieved, but large components and significant filtering are required
Solution Approach 1:
The patent replaces conventional analog power factor correction circuits with a digital signal processing approach using an FPGA. The digital controller implements PWM generation and synchronization functions that previously required large analog components, thereby achieving power factor correction with significantly reduced component size and filtering requirements.
Solution Approach 2:
The patent changes the operating parameters of the rectifier by using digital PWM modulation to control the switching devices. By varying the duty cycle and timing of the PWM signals based on the instantaneous input voltage, the system achieves unity power factor without requiring large passive components for filtering and energy storage.
2Object-generated harmful factors
If digital power factor correction is implemented, then harmonic currents are reduced and filtering needs are minimized, but device complexity increases
Solution Approach 1:
The FPGA-based controller performs multiple functions including PWM generation, input voltage synchronization, soft-start control, and harmonic reduction all within a single integrated device. This multi-functionality reduces the need for separate control circuits and minimizes overall system complexity despite the advanced capabilities provided.
3Reliability
If soft-start capability is added to the converter, then reliability is improved, but device complexity increases
Solution Approach 1:
The controller implements a soft-start function that gradually increases the output power from zero to the desired level during startup. This preliminary controlled action prevents inrush current and protects the system from transient stress, improving reliability without requiring additional hardware beyond the digital controller.
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 enables efficient conversion of AC to DC with low harmonic currents, reduced filtering needs, and support for soft-start applications, maintaining a near-unity power factor and minimizing component size, thus addressing the inefficiencies and complexity of existing technologies.
Implementation Method 1
providing one or more pulse width modulator (PWM) multipliers per phase, a full wave rectifier for each phase, which presents a half sine wave bump, which is then multiplied by replica of a sine wave
Data Source
AI summary
The method and apparatus described herein uses modern digital logic that is used to meet the need by controlling Switch-Mode Power System (SMPS) components to produce efficient conversion of the AC input source to a DC output load, maintain a near-unity Power Factor Control (PFC), require relatively small components for energy storage and filtering, as well as support a form of soft-start load application to a Poly-Phase AC source.