Parallel Motor Drive Control Using Distributed Voltage References
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Solution Overview
Problem
Existing electronic control architectures for power converters face challenges in scalability, flexibility, and complexity when paralleling multiple power converters, particularly in multiplexed systems, due to issues with circulating currents and the need for central controller reconfiguration.
Innovation Solution
A distributed control system with local current control loops and a central controller, where each power converter scales its local voltage reference based on output current values, sharing these with the central controller to regulate output currents, allowing modular and scalable operation without reconfiguration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple power converters are connected in parallel to power large loads, then the power capability is improved, but circulating currents increase and control complexity increases
Solution Approach 1:
The control system is segmented into distributed local controllers within each power converter unit, with each controller independently managing its own converter. This segmentation eliminates the need for a complex centralized control system while maintaining parallel operation capability, thus improving power capability without proportionally increasing control complexity
Solution Approach 2:
The control architecture implements equipotentiality by ensuring all distributed controllers operate from a common DC bus voltage reference. This allows parallel-connected power converters to share the load equally without complex coordination, as each converter naturally operates at the same electrical potential level, simplifying the overall control structure
2Weight of moving object
If a multiplexed power converter architecture is used to reduce weight, then the weight is reduced, but the adaptability to different load configurations decreases
Solution Approach 1:
Each power converter unit is designed as a universal module capable of operating in multiple configurations - it can power a single load independently or combine with other units in parallel to power larger loads. This multi-functionality is achieved through standardized interfaces and a control architecture that automatically adapts to the number of active converters, maintaining versatility while reducing overall system weight through the multiplexed approach
3Adaptability or versatility
If distributed control architecture is used to improve scalability, then the scalability is improved, but the measurement precision of circulating currents worsens
Solution Approach 1:
The measurement of circulating currents is extracted from the distributed local controllers and performed by a separate dedicated measurement system. This allows the distributed control architecture to maintain its scalability advantages while the specialized measurement system provides high-precision circulating current detection, as the measurement function is separated from the control functions
Data Source
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AI summary
There is provided a system for providing power to one or more loads. The system comprises a plurality of power converters, wherein each power converter is configured to be arranged in a parallel configuration with one or more additional power converters so as to provide power to the one or more loads, and a central controller configured to receive a plurality of local voltage reference values from each of the power converters, output a global voltage reference value based on the local voltage reference values, and transmit the global voltage reference value to each of the power converters. Each power converter comprises: an inverter for receiving an input voltage and converting this to an output voltage having one or more associated output current(s); a control loop configured to output a local voltage reference value for transmission to the central controller, wherein the local voltage reference value is based at least in part on the output current value(s) of the inverter; and a module configured to modulate the output voltage of the inverter using one or more modulation schemes, wherein the modulation module receives as an input the global voltage reference value and is configured to regulate the output current(s) of the inverter based on the global voltage reference value.