Parallel Drive Control With Nudge Current Sharing at Low Speed
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Solution Overview
Problem
Existing multi-channel drive systems face challenges in achieving improved dynamic speed response, minimizing steady-state speed error, and ensuring balanced current sharing, especially under low-speed high-torque load conditions.
Innovation Solution
The system employs a central controller that outputs a speed demand and a plurality of power converters arranged in parallel, each with a speed control loop, a torque/current control loop, and a module to modulate the output voltage of an inverter. This architecture includes a 'nudge control' mechanism that calculates local current demands based on speed errors and global current demands, ensuring balanced current sharing and robustness to communication failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple power converters are operated in parallel to meet wide power requirements, then the power capability is improved, but the system complexity increases
Solution Approach 1:
The system divides the power conversion function into multiple independent power converter modules (first power converter, second power converter, etc.), each capable of operating autonomously. This segmentation allows the system to scale power capability by adding modules while maintaining manageable complexity through modular design and standardized control loops in each segment.
Solution Approach 2:
Each power converter module is designed with universal functionality to handle multiple loads through a shared switch matrix. The converters can be dynamically reconfigured to serve different load combinations, making the system adaptable to wide power requirements without proportionally increasing complexity. The control architecture provides multi-functionality through centralized coordination of multiple converters.
2Adaptability or versatility
If a switch matrix is used to reconfigure connections between loads and power converters, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The switch matrix is pre-configured with predetermined connection patterns that correspond to different operational scenarios. Rather than requiring real-time complex switching decisions, the system prepares switching states in advance based on expected load combinations, reducing the complexity of dynamic reconfiguration while maintaining high adaptability.
Solution Approach 2:
The switch matrix acts as an intermediary component that decouples the complexity of load-power converter matching from the converters themselves. It provides a standardized interface layer that handles connection reconfiguration, allowing each power converter to maintain a simplified control architecture while the system as a whole achieves high adaptability through centralized switch management.
3Manufacturing precision
If synchronous reference frame control is used to control parallel motor drives, then the manufacturing precision is improved, but the speed response dynamics worsen
Solution Approach 1:
The control system is segmented into independent control loops for each power converter module, with each loop handling its own current and voltage control. This segmentation allows parallel operation of multiple converters while maintaining precise control through localized feedback loops, avoiding the speed response degradation that would occur with a single centralized synchronous reference frame controller.
Solution Approach 2:
Each power converter incorporates local feedback control loops that measure and regulate output current and voltage independently. This distributed feedback mechanism enables precise control of each module's contribution to the total load, allowing the parallel system to achieve both high precision and fast response by having multiple independent control pathways rather than a single bottlenecked control loop.
Data Source
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AI summary
There is provided herein a system for providing power to one or more loads. The system comprises a central controller (360, 460) configured to output a speed demand for one or more loads; and a plurality of power converters (301, 302, 401, 402) arranged in a parallel configuration with each other and configured to provide power to the one or more loads. Each power converter (301, 302, 401, 402) comprises a speed control loop (310, 410) configured to calculate a local current demand based at least in part on an output speed error between the speed demand of the one or more loads and a measured speed of the one or more loads; a torque/current control loop (320, 420) configured to calculate an output voltage demand based at least in part on the local current demand of its respective speed control loop; and a module (340) configured to modulate the output voltage of an inverter (350) based on the output voltage demand from the torque/current control loop.