Electric Machine Pulsed Control for Variable-Load Efficiency
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Solution Overview
Problem
Existing electric machines operate inefficiently under varying load conditions, as they often deviate from their most efficient operating range, particularly in applications requiring wide variations in torque and speed.
Innovation Solution
Implementing pulsed control of electric machines, intermittently driving them between a first output level and zero torque to maintain efficiency, using power converters like inverters and sigma delta converters to manage the pulsing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric machine operates continuously to meet varying load conditions, then the torque and speed requirements are satisfied, but the energy conversion efficiency drops significantly when operating outside the sweet spot
Solution Approach 1:
The patent applies periodic action by pulsing the electric machine on and off rather than operating continuously. The controller pulses the machine between an on-state (operating near the sweet spot for high efficiency) and an off-state (zero torque), creating a periodic operation pattern that maintains overall system efficiency while meeting varying load requirements through duty cycle modulation.
2Use of energy by moving object
If the electric machine is pulsed between on and off states, then energy conversion efficiency is improved, but the output torque and power delivery may become discontinuous
Solution Approach 1:
The patent applies dynamics by making the machine operation dynamic rather than static. The controller dynamically adjusts the duty cycle of the pulsed operation based on the desired torque output, continuously varying the on/off timing to match the load requirements. This dynamic control ensures that the average torque output matches the demand while maintaining high efficiency during the on-states.
Solution Approach 2:
The patent applies feedback by using the desired torque output as a control input to the pulse controller, which adjusts the duty cycle accordingly. The system continuously monitors the torque requirements and adjusts the pulsing pattern to deliver the appropriate average torque while maximizing efficiency, creating a closed-loop control system.
Data Source
AI summary
Methods, controllers and electric machine systems are described that facilitate pulsed control of electric machines (e.g., electric motors and generators) to improve the machine's energy conversion efficiency. Under selected operating conditions, the electric machine is intermittently driven (pulsed). The pulsed operation causes the output of the electric machine to alternate between a first output level and an off state. The output levels are selected such that the electric machine has a higher energy conversion efficiency during the pulsed operation than the electric machine would have when operated at a third output level that would be required to drive the electric machine in a continuous manner to deliver the desired output. In some embodiments, the power converter it turned off during at least portions of the time that the electric machine is pulsed off.