Paralleled Electrical Drives With Bus-Free Torque Balancing
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Solution Overview
Problem
Mechanically paralleled electrical drive systems face challenges in achieving balanced torque production without introducing additional single points of failure, particularly in position control applications, as existing methods like intercommunication buses complicate the system architecture and reduce fault tolerance.
Innovation Solution
A control loop system that uses position sensors and controllers to calculate current demands for each motor based on position errors and feedback signals, incorporating a 'discharge term' that adjusts dynamically with the current demand, allowing motors to balance torque production without explicit communication, thereby reducing the risk of single failure points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If intercommunication buses are used between paralleled motor drives to achieve torque balancing, then torque production balance is improved, but system reliability deteriorates due to introduction of single points of failure
Solution Approach 1:
The patent removes the intercommunication bus from the system architecture, extracting the problematic single point of failure while retaining torque balancing capability through independent local control. Each motor drive operates autonomously using its own position sensor feedback, eliminating the need for inter-drive communication infrastructure.
Solution Approach 2:
Each motor drive serves itself by independently measuring position through its own position sensor and adjusting its current demand accordingly. The system achieves collective torque balancing through individual self-regulation rather than centralized coordination, with each drive responding to its own feedback signal.
2Reliability
If multiple communication buses are used to provide redundancy, then system reliability is improved, but device complexity increases
Solution Approach 1:
The patent completely removes communication buses from the system, extracting the source of complexity while maintaining reliability through alternative means. The solution demonstrates that reliable operation can be achieved without any intercommunication infrastructure by using independent local feedback loops.
Solution Approach 2:
Each motor drive independently determines its own operating parameters based on local position feedback, eliminating the need for complex communication protocols and message passing between drives. The system achieves coordination through physical coupling of the load rather than electronic communication.
3Ease of operation
If position control is implemented without discharge term feedback, then control simplicity is maintained, but torque balancing between motors deteriorates
Solution Approach 1:
The patent introduces a discharge term feedback mechanism that subtracts a portion of the measured position feedback from the position error signal. This feedback modification creates a stabilizing effect that promotes torque balancing between paralleled motors while maintaining relatively simple control implementation.
Solution Approach 2:
The discharge term modifies the effective position error parameter by subtracting a fraction of the position feedback, changing the control parameter dynamics to achieve torque balancing. This parameter transformation allows the system to self-regulate torque distribution without complex control algorithms.
Data Source
AI summary
A system includes a mechanical load, a first electrical motor and associated motor drive and a second electrical motor and associated motor drive. The first electrical motor and the second electrical motor being configured to drive the mechanical load in parallel. Each electrical motor and associated motor drive have a respective position sensor configured to measure the output position of the mechanical load; and each motor drive comprises a respective controller configured to output a current demand for its associated motor based on a position error between a desired output position of the mechanical load and the measured output position of the mechanical load from its respective position sensor, and a feedback signal of its output current demand.