Multi-Phase Power Conversion System for Power Factor Correction
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Solution Overview
Problem
Current power conversion systems for multi-phase generators face challenges in controlling the power factor effectively, especially with unstable wind power sources, leading to inefficiencies and complex control mechanisms.
Innovation Solution
A power conversion system comprising a multi-phase power conversion unit and a control unit with an outer control loop, discontinuous current limiter, and inner control loop that converts generator voltages to DC voltage and current, allowing for power factor correction by controlling generator currents to linearly follow generator voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If passive full-bridge rectifier is used, then conversion losses are minimal and efficiency is maximal, but power factor control capability is lost and ripple torque causes vibration and noises
Solution Approach 1:
The patent divides the power conversion system into multiple independent single-phase power conversion units (first, second, and third power conversion units) instead of using a single three-phase rectifier. Each unit processes one phase independently with its own switch and inductor, converting the three-phase input to a unified DC output. This segmentation allows each phase to be controlled independently, eliminating the ripple torque issues while maintaining simple control structures.
2Ease of operation
If active rectifying converter with six active switches is used, then full-voltage power and power factor control are achieved, but control complexity and power losses increase
Solution Approach 1:
The patent segments the complex three-phase active rectifier into three simpler single-phase power conversion units. Each unit contains only one active switch and one inductor, dramatically reducing the total component count and control complexity while maintaining the ability to control power factor through independent phase control.
Solution Approach 2:
The patent employs discontinuous conduction mode where each single-phase power conversion unit operates in periodic cycles of switching on and off. The switches are controlled to conduct during specific intervals when their respective phase voltages are positive or negative, creating a periodic action pattern that simplifies control while achieving power factor correction.
3Power
If active rectifying converter with six active switches is used, then full-voltage power conversion is achieved, but power losses increase
Solution Approach 1:
By segmenting the system into three independent single-phase units rather than one complex three-phase unit, the patent reduces the number of active switches from six to three, directly reducing switching losses and control overhead while maintaining full-voltage power conversion capability through the multi-phase configuration.
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 system achieves low-loss, simple-control power factor correction, enhancing control robustness for unstable power sources and enabling broader applications with flexible multi-phase power conversion.
Implementation Method 1
The multi-phase power conversion unit receives a plurality of generator voltages and a plurality of generator currents generated from the multi-phase generator, and converts the generator voltages to output a DC voltage and a DC current
Data Source
AI summary
A power conversion system of a multi-phase generator used to provide a power factor correction for a multi-phase generator. The power conversion system of the multi-phase generator includes a multi-phase power conversion unit and a control unit. The multi-phase power conversion unit receives a plurality of generator voltages and a plurality of generator currents generated from the multi-phase generator, and converts the generator voltages into a DC voltage and a DC current. The control unit controls the generator currents to linearly follow the generator voltages, therefore the power factor correction for the multi-phase generator is achieved.