Multi-Winding Brushless Motor Controller Torque Redistribution
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Solution Overview
Problem
Conventional multi-winding brushless motor controllers struggle with torque ripple and accuracy due to current and voltage limitations, especially when windings fail, leading to reduced motor performance and efficiency.
Innovation Solution
A controller that uses sensors to detect failure modes in windings and dynamically redistributes drive currents to healthy windings, optimizing torque production by reshaping drive current waveforms within voltage and current limits, employing a method that involves monitoring motor output and demand, and using a processor to compute optimal current distributions based on motor models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If sinusoidal current waveforms are used to excite windings for smooth motor operation, then motor operation smoothness is improved, but torque ripple occurs due to non-ideal motor characteristics
Solution Approach 1:
The patent pre-shapes the drive current waveforms to compensate for non-ideal motor characteristics. Instead of using simple sinusoidal waveforms, the controller applies modified current waveforms that account for the motor's actual electromagnetic characteristics, thereby eliminating torque ripple while maintaining smooth operation.
2Reliability
If drive circuits are designed with voltage and current limits to protect motor components, then component reliability is improved, but torque production deteriorates when limits are reached during high torque or speed operation
Solution Approach 1:
The patent pre-calculates and stores optimal drive current waveforms that satisfy both voltage and current constraints before motor operation. When the motor operates at high torque or speed, the controller retrieves pre-computed waveforms that maximally utilize the available voltage and current headroom, thereby maintaining torque production while respecting component limits.
3Reliability
If a winding fails completely or partially, then system reliability deteriorates, but the patent enables continuous operation by redistributing torque to healthy windings
Solution Approach 1:
The patent continuously monitors the performance of each winding and detects failures through feedback from back-emf voltage measurements and current sensors. When a winding failure is detected, the controller immediately redistributes the torque demand to healthy windings by recalculating optimal current waveforms, enabling continuous operation without interruption.
Solution Approach 2:
When a winding fails, the patent effectively discards the faulty winding from active service and recovers full motor functionality by redistributing its torque burden to healthy windings. The system dynamically reconfigures to utilize only functional windings, maintaining operational capability despite component failure.
4Reliability
If multiple sensors and complex control algorithms are implemented to detect failures and redistribute currents, then fault tolerance is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-diagnosing control system that uses the motor's own operational parameters (back-emf voltages, phase currents) to detect winding failures. The controller automatically identifies faulty windings and redistributes torque without external intervention, achieving fault tolerance through self-monitoring and self-correction mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances torque accuracy and increases motor speed and torque capacity by effectively managing current and voltage limits, ensuring continuous and precise torque production even under winding failures, thereby improving motor performance and efficiency.
Implementation Method 1
Some failure modes are monitored in accordance with the art, having regard to back-emf voltage
Implementation Method 2
The controller is coupled by respective drive circuits to the windings. While most multi-winding brushless motors incorporate the windings in the stator, it is possible, though usually inconvenient, to locate windings in the rotor, and its logically possible to include windings on both the stator and rotor.
Data Source
AI summary
A technique for controlling drive currents to respective windings of a multi-winding brushless motor comprises monitoring an output of the motor and a demand of the motor, determining whether a failure mode has occurred, the failure mode being an instantaneous complete or partial failure to generate demanded output; and, upon detection of a failure mode on a first winding, distributing a demand contribution that is not being produced by the first winding to one or more of the windings that are not in a failure mode. The demand may be torque demand, and the failure modes may include winding failure, and voltage and/or current saturation. Improved torque output is generated by the redistribution of demand among phases in the event of a failure mode.