Multi-Source Power Conversion Vector Control
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Solution Overview
Problem
Existing motor drive systems face inefficiencies when transferring power among multiple sources due to poor power factors, requiring higher voltages and resulting in reduced efficiency.
Innovation Solution
A power conversion system and method that includes a control unit to compute and manage output voltage command values for multiple voltage sources, ensuring efficient power transfer by optimizing voltage vectors and current vectors to minimize voltage requirements and maximize power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If voltage command values are divided according to power distribution ratios among multiple power sources, then power transfer control is achieved, but power factors deteriorate and efficiency declines
Solution Approach 1:
The invention changes the control parameter from simple power distribution ratios to vector-based voltage commands with optimized phase angles. By adjusting the phase angle between voltage and current vectors, the system maintains unity power factor while achieving power transfer, thus resolving the contradiction between power transfer control and efficiency
Solution Approach 2:
The invention combines multiple voltage sources with different characteristics (fuel cell and secondary battery) into a composite power system, where each source operates at optimized voltage and phase angles. This composite approach allows simultaneous achievement of power transfer control and high efficiency by leveraging the strengths of each power source
2Power
If larger voltage is applied to supply given current under poor power factor conditions, then current supply is maintained, but voltage requirements increase and efficiency reduces
Solution Approach 1:
The invention changes the voltage command from scalar magnitude control to vector control with optimized phase angle. By maintaining the voltage vector in phase with the current vector (unity power factor), the system supplies the required current at minimum voltage, eliminating the need for larger voltages that would otherwise be required under poor power factor conditions
Data Source
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AI summary
A power conversion system includes first and second voltage sources for driving a multiple-phase AC motor and a control unit. The control unit is configured to compute first and second output voltage command values used to drive the multiple-phase AC motor based on a first output voltage command vector corresponding to the voltage source that is charged and a second output voltage command vector corresponding to the voltage source that is discharged. The first and second output voltage command vectors are determined so that a resultant vector of the first and second output voltage command vectors is coincident with a motor voltage command vector corresponding to a motor voltage command value, and a motor current command vector corresponding to the motor current command value is positioned within an included angle formed between the second output voltage command vector and a negative vector of the first output voltage command vector.