Pulsed Electric Machine Control for Variable Torque Efficiency
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Solution Overview
Problem
Conventional electric machines experience reduced energy conversion efficiency when operating under varying load conditions, as they often operate away from their most efficient torque and speed ranges, leading to inefficiencies in applications requiring wide-ranging torque and speed variations.
Innovation Solution
Implementing pulsed control of electric machines, where the output alternates between a higher and a lower output level, with the lower level being zero torque, to maintain higher efficiency by operating the machine at or near its most efficient operating point, using power converters like inverters and sigma delta converters to manage the pulsing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electric machine operates continuously to meet varying torque requirements, then the torque output is maintained, but the energy conversion efficiency decreases when operating away from the most efficient operating point
Solution Approach 1:
The patent applies periodic action by pulsing the electric machine on and off in a cyclic manner. The controller intermittently activates the machine at its most efficient operating point rather than running continuously at reduced load, achieving both torque delivery and improved energy efficiency through rhythmic operation cycles
Solution Approach 2:
The system dynamically adjusts between continuous and pulsed operation modes based on real-time operating conditions. The controller monitors torque requirements and seamlessly transitions the machine between different operational states, optimizing efficiency while meeting varying load demands
2Loss of energy
If the electric machine is pulsed to operate at the most efficient operating point, then the energy conversion efficiency is improved, but the output torque varies between high and zero levels
Solution Approach 1:
The controller implements periodic action by pulsing the machine on and off in controlled cycles, maintaining efficiency while managing output variations through rhythmic operation patterns that alternate between active and idle states
Solution Approach 2:
The system employs feedback mechanisms where the controller continuously monitors operating conditions and torque requirements, adjusting the pulsing duty cycle in real-time to maintain stable average torque output while keeping the machine at its most efficient operating point during active periods
3Adaptability or versatility
If the electric machine operates over a wide variety of load conditions, then the application requirements are met, but the energy conversion efficiency drops when operating outside the optimal torque and speed range
Solution Approach 1:
The patent applies periodic action by pulsing the electric machine on and off in a cyclic manner. The controller intermittently activates the machine at its most efficient operating point rather than running continuously at reduced load, achieving both torque delivery and improved energy efficiency through rhythmic operation cycles
Solution Approach 2:
The system dynamically adjusts between continuous and pulsed operation modes based on real-time operating conditions. The controller monitors torque requirements and seamlessly transitions the machine between different operational states, optimizing efficiency while meeting varying load demands
Data Source
AI summary
A variety of 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 a second output level that is lower than the first output level. The output levels are selected such that at least one of the electric machine and a system that includes 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 second output level is zero torque.