Rotary Electric Machine Torque Modulation for Partial Load Efficiency
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Solution Overview
Problem
Rotary electric machines experience significant drive-cycle losses under partial load conditions due to motor core losses, necessitating operational schemes that enhance efficiency by reducing these losses.
Innovation Solution
A control system for multi-phase rotary electric machines that determines a modulated torque command based on peak torque per loss and second torque parameters, allowing the machine to operate efficiently by adjusting torque levels and control periods to minimize power loss, using an inverter and sensors to monitor and control the machine's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the electric machine operates under partial load conditions, then the machine can meet varying torque demands, but motor core losses increase significantly reducing efficiency
Solution Approach 1:
The control system implements periodic torque modulation by alternating between peak torque per loss parameter operation and second torque parameter operation over defined subperiods within a control period. This periodic switching allows the machine to maintain average torque equivalence while reducing motor core losses during partial load conditions, directly resolving the contradiction between adaptability and energy loss.
Solution Approach 2:
The system dynamically changes operational parameters by determining a modulated torque command based on the peak torque per loss parameter and second torque parameter. This parameter modulation approach allows the electric machine to operate at different torque levels periodically, maintaining adaptability to torque demands while significantly reducing motor core losses through optimized parameter selection.
2Loss of energy
If the machine operates at peak efficiency points, then power loss is minimized, but the average torque output may not match the commanded torque
Solution Approach 1:
The control system uses periodic action by dividing the control period into first and second subperiods. During the first subperiod, the machine operates at the peak torque per loss parameter to minimize power loss. During the second subperiod, it operates at the second torque parameter. The duration of each subperiod is calculated to ensure the average torque over the complete control period equals the commanded torque, thus resolving the contradiction between minimizing power loss and maintaining required torque output.
Solution Approach 2:
The system dynamically adjusts the torque command modulated based on the relationship between peak torque per loss parameter and second torque parameter. This dynamic modulation ensures that while operating at efficient points during subperiods, the time-averaged torque output precisely matches the commanded torque requirement, resolving the contradiction between power loss minimization and torque productivity.
3Loss of energy
If the control system uses complex torque modulation schemes, then efficiency under partial load improves, but the control system complexity increases
Solution Approach 1:
The control system implements efficiency improvement through parameter changes by calculating a modulated torque command based on two key parameters: peak torque per loss parameter and second torque parameter. This approach reduces drive-cycle losses through mathematical parameter optimization rather than complex hardware modifications, achieving efficiency improvement with relatively straightforward control logic that computes and applies parameter-based torque modulation.
Data Source
AI summary
A method and system for controlling and regulating operation of a multi-phase rotary electric machine in a manner that minimizes power loss under partial load conditions is described. This includes an instruction set that is executable to determine a torque command and a rotational speed of the electric machine, determine a peak torque per loss parameter for the electric machine based upon the rotational speed, and determine a second torque parameter for the electric machine based upon the rotational speed. A modulated torque command for controlling the electric machine is determined based upon the peak torque per loss parameter and the second torque parameter, wherein the electric machine generates an average torque that is equivalent to the torque command when operating in response to the modulated torque command. The inverter is controlled to operate the electric machine based upon the modulated torque command.