Multi-Motor Pulsed Torque Control for Efficiency and Low NVH
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Solution Overview
Problem
Existing electric machines, such as motors and generators, often operate inefficiently under varying load conditions, particularly in applications like electric vehicles and drones, due to their inability to adapt energy conversion efficiency based on operational demands.
Innovation Solution
Implementing pulsed control methods for multiple electric machines, where machines are intermittently driven at optimal efficiency levels, alternating between 'torque on' and 'zero torque' states, and phase-timing multiple motors to minimize noise, vibration, and harshness (NVH) through coordinated pulsing frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electric machines operate continuously under varying load conditions, then they can meet operational demands, but energy conversion efficiency deteriorates
Solution Approach 1:
The patent applies periodic action by pulsing the electric machine between active and inactive states rather than continuous operation. The controller pulses the electric machine to operate at a first output level during active periods and a second output level (lower than first) during inactive periods, creating a periodic on-off pattern that maintains average output while improving efficiency by eliminating continuous operation at suboptimal efficiency points
Solution Approach 2:
The patent implements dynamics by making the electric machine's output level changeable over time based on operational needs. The system dynamically adjusts between two distinct output levels (first and second output levels) rather than maintaining a fixed continuous output, allowing the machine to adapt its operational state to optimize efficiency while meeting varying load demands
2Productivity
If multiple electric machines are operated simultaneously, then system output is maintained, but noise, vibration, and harshness increase
Solution Approach 1:
The patent reduces NVH by pulsing multiple electric machines in a coordinated periodic manner. Instead of all machines operating continuously, the controller pulses them in sequences where some machines are active while others are inactive, creating periodic operation patterns that reduce continuous vibration and noise sources while maintaining overall system output through load distribution across multiple machines over time
Solution Approach 2:
The patent applies segmentation by dividing the total system output requirement across multiple electric machines rather than relying on a single continuous machine. The controller distributes the load among multiple machines, pulsing them in coordinated fashion so that not all machines operate simultaneously at full capacity, thereby segmenting the NVH generation sources while maintaining aggregate system output
3Productivity
If electric machines operate at high output levels continuously, then productivity is maintained, but thermal balance deteriorates
Solution Approach 1:
The patent maintains thermal balance through periodic operation patterns that cycle between high output (first output level) and lower output (second output level) states. This periodic pulsing creates intervals of reduced thermal generation during the second output level periods, allowing thermal dissipation and preventing continuous heat accumulation that would occur with sustained high-level operation, thereby maintaining acceptable thermal balance while preserving average productivity
Data Source
AI summary
A variety of methods, controllers, and electric machine systems are described that facilitate pulsed control of multiple 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 machines 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.