Increased Ripple-Free Torque or Speed in BLDC Motors Operating under Current or Voltage Saturation
The technology
The Canadian Space Agency (CSA) invention presents a novel electronic commutator of BLDC motors with any back-EMF waveform such that the commutator minimizes power dissipation, subject to current and voltage limits of the motor's drivers. When one or more phases reach their voltage and/or current saturation levels, the controller optimally reshapes the stator currents of the remaining phases for continuing accurate, ripple-free torque production -- the controller automatically reshapes the excitation currents in such a way that the motor continues to generate the torque that is requested. A closed-form solution for the optimal phase currents at given angular position, velocity and desired torque, renders the control algorithm suitable for real-time implementation.
This innovation allows the motor to operate above the rated speed and torque that would be achieved without current reshaping. This optimal management of the motor's excitation currents can significantly increase the rated speed or torque of the motor in the face of voltage and current limits of the drivers. Experiments show that the maximum torque capability is boosted by 20% when the phase saturation is considered in the phase current shape function.
In addition, the torque controller can be used as a remedial strategy to compensate for a phase failure by optimally reshaping the currents of the remaining healthy phases for accurate torque production. The control algorithm allows the motor to optimally generate precise torque, even when operating under a phase failure.
Commercial potential
The CSA innovation provides potential for a manufacturer to improve the efficiency of its BLDC motors in motion control systems by minimizing power dissipation.
The technology's ability to provide ripple-free torque in a BLDC motor that is operating, intentionally, with one or more phases in voltage and/or current saturation provides system designers with an opportunity to substantially increase the speed and/or torque from a given BLDC motor.
The business opportunity
The technology is available for license. This control technology will enable manufacturers and developers of electric cars and other electric vehicles to maximize a motor's efficiency, rating torque and rating speed, despite current and voltage limits of an on-board power supply.
The technology will also be of interest to companies that develop and manufacture BLDC motion controllers, drives and/or motors. Market opportunities for the CSA technology are in applications that require BLDC motors with high efficiency, and those that require BLDC motors with reliable (i.e., fault-tolerant) performance.
Technology transfer details
A commercialization license for this technology is available.
The business opportunity may be referred to by its CSA case ID: 51105
Publications
- Aghili, F., "Optimal and Fault-Tolerant Torque Control of Servo Motors Subject to Voltage and Current Limits", Institute of Electrical and Electronics Engineers (IEEE), IEEE Transactions on Control Systems Technology, .
- Aghili, F., "Optimal and Fault-Tolerant Torque Control of Servo Motors Subject to Voltage and Current Limits", Institute of Electrical and Electronics Engineers (IEEE), International Conference on Intelligent Robots and Systems, San Francisco, USA, -.
- Aghili, F., "Fault-Tolerant Torque Control of BLDC Motors", Institute of Electrical and Electronics Engineers (IEEE), IEEE Transactions on Power Electronics, Vol. 26, No.2, pp.355-363, .
Patents
- Canada
- Number: 2790645
- Status: Patent Granted
- Source: Canadian Intellectual Property Office (CIPO)
- United States
- Number: 8,994,308
- Status: Patent Granted
- Source: United States Patent and Trademark Office (USPTO)