Electric Machine Pulsed Control With Notch Filtering for NVH
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Solution Overview
Problem
Electric machines, such as motors and generators, often operate at varying efficiency levels due to changing load conditions, leading to reduced energy conversion efficiency, particularly in electric vehicles where a significant portion of the drive cycle is spent outside the most efficient operating ranges, limiting the vehicle's range on a given battery charge.
Innovation Solution
Implementing pulsed control methods for electric machines, utilizing cubic or higher-order pulse transition torque profiles and notch filters to manage noise, vibration, and harshness (NVH) issues, while optimizing transitions to maintain energy efficiency by alternating between high and low output levels, thereby extending the operating range of electric vehicles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric machine operates continuously at a fixed output level to meet average demand, then the operation is simple and stable, but the energy conversion efficiency is reduced because the machine cannot maintain operation in the high efficiency operating range
Solution Approach 1:
The patent applies periodic pulsed operation where the electric machine alternates between high output level (first output level) and low output level (second output level) to deliver the desired average output. This periodic switching enables the machine to spend more time in the high efficiency operating range while still meeting the average demand requirement, thereby improving overall energy conversion efficiency without requiring fundamental changes to the machine structure
Solution Approach 2:
The patent implements dynamic control of the electric machine output by transitioning between different output levels based on operational requirements. The transition profile generator dynamically adjusts the output level timing and duration to optimize efficiency while meeting demand, transforming the static continuous operation into a dynamic pulsed operation that adapts to efficiency optimization goals
2Use of energy by moving object
If pulsed operation is implemented to improve energy efficiency, then the machine can operate more time in high efficiency range, but noise, vibration, and harshness (NVH) issues are exacerbated
Solution Approach 1:
The patent applies beforehand cushioning by using transition profiles (such as cubic or higher-order profiles) that smoothly ramp the output level changes rather than abrupt switching. This cushioning of transitions reduces mechanical shocks and vibrations that would otherwise be generated by sudden start-stop pulsed operation, thereby mitigating NVH issues while preserving the energy efficiency benefits of pulsed operation
Solution Approach 2:
The patent changes the temporal parameters of the pulsed operation by controlling the duration, frequency, and transition smoothness of the output level changes. By optimizing these parameters, the system achieves energy efficiency improvement while keeping the pulsed operation frequencies and transition rates below thresholds that would generate excessive noise and vibration
3Use of energy by moving object
If the electric machine operates at varying output levels to maintain efficiency, then energy efficiency is improved, but the control system complexity increases due to transition management
Solution Approach 1:
The patent segments the control function into distinct modules: a pulsed operation generator that creates the basic pulse pattern, a transition profile generator that manages the smoothing transitions, and a notch filter controller that handles NVH compensation. This segmentation allows each module to perform its specific function independently, making the overall complex control system more manageable and implementable
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The pulsed control approach enhances energy conversion efficiency by maintaining a greater proportion of operation within the most efficient torque and speed ranges, reducing NVH concerns, and increasing the range of electric vehicles on a single battery charge.
Implementation Method 1
the vehicle has at least one resonance frequency
Implementation Method 2
At least one notch filter at the at least one resonance frequency of the vehicle is provided
Data Source
AI summary
A method of controlling operation of at least a first electric machine of at least one electric machine on board a vehicle, wherein the vehicle has at least one resonance frequency is provided. A pulsed operation of the first electric machine is directed to deliver a desired average output, wherein the pulsed operation causes the first electric machine to alternate between a first output level that is greater than the desired average output and a second output level that is less than the desired average output. At least some transitions between the first output level and the second output level are controlled. At least one notch filter at the at least one resonance frequency of the vehicle is provided.