Pulsed Electric Machine Control for Variable-Load 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 'sweet spot' due to the need to handle a wide range of torque and speed requirements in applications like automotive and other mobility systems.
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 improve efficiency by operating the machine at more efficient energy conversion levels, using power converters like inverters and sigma delta converters to manage the pulsing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the electric machine operates continuously to meet varying torque and speed requirements, then the machine can handle a wide range of operating conditions, but the energy conversion efficiency decreases as the machine operates away from its optimal 'sweet spot'
Solution Approach 1:
The patent applies periodic action by pulsing the electric machine on and off in a cyclic manner. Instead of continuous operation, the machine is activated in periodic bursts to deliver required torque, allowing it to operate at or near optimal efficiency points during active periods while remaining inactive during off periods, thereby reducing overall energy loss across the full operating range
Solution Approach 2:
The patent implements dynamics by making the machine operation flexible and adaptive through variable duty cycles. The control system dynamically adjusts the proportion of time the machine is on versus off based on real-time torque and speed requirements, enabling the system to maintain adaptability to varying loads while optimizing efficiency by keeping the machine in its sweet spot during active operation
2Loss of energy
If the electric machine is pulsed to operate at higher efficiency levels, then energy conversion efficiency improves, but the machine cannot continuously deliver maximum torque output
Solution Approach 1:
The patent applies partial action by operating the machine at less than 100% duty cycle - it is on only part of the time rather than continuously. During the on periods, the machine operates at or near optimal torque levels for maximum efficiency, while during off periods it delivers zero torque. This partial operation strategy achieves better overall efficiency while still meeting the average torque requirements through proper duty cycle management
Data Source
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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.