Parallel Power Converter Control Circuitry Circulating Current Suppression
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Solution Overview
Problem
In parallel power conversion systems, existing technologies face challenges in effectively suppressing circulating currents between converters, which can lead to instability and reduced efficiency in output voltage regulation.
Innovation Solution
A power conversion system comprising a master and slave device configuration, where the master device generates a limited command value and transmits it to the slave device, with both devices adjusting their operation based on adjustment values to modify the secondary-side limit, thereby controlling the power conversion circuitry to suppress circulating currents and optimize output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed secondary-side limit is used for command value limitation, then the control structure is simple, but circulating currents occur between parallel converters and output voltage stability deteriorates
Solution Approach 1:
The patent applies dynamics by making the secondary-side limit adjustable rather than fixed. The control device dynamically modifies the secondary-side limit based on adjustment values received from other parallel-operated converters, allowing the system to adapt to changing operating conditions and suppress circulating currents while maintaining reasonable control structure complexity
Solution Approach 2:
The patent implements feedback by having each control device exchange adjustment values with other devices in the parallel system. Each device receives adjustment values from others, uses them to modify its secondary-side limit, and transmits its own adjustment values to others, creating a closed-loop feedback mechanism that stabilizes output voltage and suppresses circulating currents
2Reliability
If the secondary-side limit is adjusted based on adjustment values from other devices, then circulating currents are suppressed, but communication and coordination between devices are required
Solution Approach 1:
The patent uses adjustment values as intermediaries between parallel converters. Each converter calculates adjustment values based on its local operating conditions and transmits them to other converters. These adjustment values serve as compact information carriers that enable coordinated control without requiring complex direct communication protocols, thus suppressing circulating currents while keeping communication requirements manageable
Data Source
AI summary
A device includes: a first power conversion circuitry configured to convert primary-side power into secondary-side power; and a control circuitry configured to: generate a command value associated with the secondary-side power; calculate a limited command value by modifying the command value so that the command value is equal to or less than a secondary-side limit, wherein the first power conversion circuitry is controlled based on the limited command value; transmit the limited command value to a second power conversion device comprising a second power conversion circuitry connected in parallel to the first power conversion circuitry; receive, from the second power conversion device, information indicating an adjustment value, wherein the adjustment value is added to the limited command value for controlling the second power conversion circuitry; and modify the secondary-side limit based on a difference between a primary-side limit associated with the primary-side power and the adjustment value.