Power Converter Circulating Current Reduction via Carrier Wave Phase Adjustment
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Solution Overview
Problem
Existing power conversion systems face challenges in minimizing circulating currents between parallel-connected power conversion apparatuses, which can lead to inefficiencies and increased energy losses due to phase differences in carrier waves.
Innovation Solution
A power conversion apparatus that generates a carrier wave, synchronizes a pulse signal with it, and adjusts the carrier wave's period based on circulating current monitor values to decrease circulating currents, while also compensating for dead time distortions and optimizing modulation methods to synchronize power conversion effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple power conversion apparatuses are connected in parallel to increase power output capability, then power conversion capacity is improved, but circulating currents occur between the apparatuses causing energy losses
Solution Approach 1:
The control device monitors the circulating current between parallel-connected power conversion apparatuses and dynamically adjusts the carrier wave phase based on this feedback. By continuously detecting the circulating current and modifying the carrier phase accordingly, the system eliminates the harmful circulating currents while maintaining the parallel connection configuration for increased power capacity.
Solution Approach 2:
The invention changes the phase parameter of the carrier wave to eliminate circulating currents. By adjusting the carrier phase difference between parallel-connected apparatuses, the system optimizes the operating parameters to prevent energy losses while preserving the parallel connection architecture for enhanced power output capability.
2Productivity
If carrier wave phases are not synchronized between parallel-connected power conversion apparatuses, then independent operation is maintained, but circulating currents are generated reducing system efficiency
Solution Approach 1:
The control device implements a feedback mechanism that monitors circulating current and automatically adjusts carrier wave phases to achieve synchronization. This feedback-based approach simplifies the synchronization process by eliminating the need for complex predetermined phase coordination between apparatuses, thereby improving system efficiency without excessively increasing control complexity.
Solution Approach 2:
Each power conversion apparatus independently adjusts its own carrier wave phase based on circulating current detection performed by its local control device. This self-service approach allows apparatuses to autonomously synchronize with each other through automatic phase adjustment, reducing the need for external coordination and simplifying the overall synchronization control while enhancing system efficiency.
Data Source
AI summary
A power conversion apparatus connectable in parallel to a second power conversion apparatus includes circuitry that generates a carrier wave, generates a pulse signal synchronized with the carrier wave, generates power that is based on a width of the pulse signal, obtains a monitor value corresponding to a circulating current circulating between the power conversion apparatus and the second power conversion apparatus, and based on the monitor value obtained while the power conversion circuitry is generating driving power, changes a period of the carrier wave to decrease the circulating current.