Electric Motor Torque Control for Vibrational Order Attenuation
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Solution Overview
Problem
Vibrational orders in electric motors, particularly in electric vehicles, cause perceptible vibrations that detract from the occupant experience, with cogging torque and AC production being significant sources of these vibrations.
Innovation Solution
A motor control strategy involving a filter and proportional derivative controller is applied to detect and attenuate specific vibrational orders by combining attenuation signals with torque command signals, using low-pass and notch filtering to generate adjusted torque commands for the electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If vibration attenuation control is applied to reduce perceptible vibrations, then occupant experience is improved, but control system complexity increases
Solution Approach 1:
The patent implements feedback by detecting actual motor vibrations through sensors and using this information to dynamically adjust torque commands. The controller continuously monitors vibration levels and modifies control signals to attenuate specific vibrational orders, creating a closed-loop system that adapts to real-time motor conditions.
Solution Approach 2:
The patent introduces an intermediary vibration attenuation controller that acts as a mediator between the motor controller and the motor. This intermediary component processes torque commands, detects vibrational orders, and modifies control signals to reduce vibrations without directly altering the motor's mechanical structure.
2Object-affected harmful factors
If multiple vibrational orders are attenuated simultaneously, then vibration reduction effectiveness is improved, but computational load increases
Solution Approach 1:
The patent segments the vibration attenuation process by identifying and treating different vibrational orders separately. Each vibrational order is detected and attenuated through distinct control actions, allowing the system to address multiple vibration sources independently rather than attempting to reduce all vibrations simultaneously as a single complex problem.
Solution Approach 2:
The patent applies partial action by selectively attenuating only specific vibrational orders that fall within defined speed ranges, rather than attempting to reduce all possible vibrations across the entire operating spectrum. This approach focuses computational resources on the most problematic vibration frequencies while accepting that other vibrations may remain unattenuated.
3Object-affected harmful factors
If vibration attenuation is applied across all operating conditions, then overall vibration reduction is improved, but energy consumption increases
Solution Approach 1:
The patent implements dynamic control by enabling vibration attenuation only within specific operating speed ranges where vibrations are most problematic. The system dynamically adjusts its attenuation behavior based on real-time motor speed, applying control actions when vibrations exceed acceptable thresholds and reducing or disabling attenuation when operating conditions are favorable, thereby optimizing energy usage.
Solution Approach 2:
The patent applies local quality by targeting vibration attenuation specifically to certain speed ranges and operational conditions rather than uniformly across all operating parameters. The control system identifies problematic vibration zones and concentrates attenuation efforts in those specific regions, allowing other operating conditions to function without additional energy-consuming control interventions.
Data Source
AI summary
In a general aspect, a method can include applying, by a motor controller, a filter to a signal indicating rotational speed of an electric motor to detect an order of vibration of the electric motor to be attenuated. The method can also include providing the filtered signal to a proportional derivative controller, and generating, by the proportional derivative controller, an attenuation signal for attenuating vibration associated with the detected order of vibration. The method can still further include combining the attenuation signal with a torque command signal to produce a combined torque command signal. The torque command signal can indicate an amount of torque requested from the electric motor. The method can further include producing torque with the electric motor based on the combined torque command signal.