Electric Motor Control Device Vibration Suppression

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Solution Overview

Problem

Conventional electric motor control devices face a trade-off between settling property and vibration suppression, as increasing acceleration feedback gain improves vibration suppression but deteriorates command follow-up performance, making it difficult to satisfy both simultaneously.

Innovation Solution

An electric motor control device incorporating a feedforward controller, feedback controller, and adder-subtractor that compensates for load acceleration feedback torque in feedforward torque calculations, enhancing vibration suppression while maintaining command follow-up performance by adjusting the load acceleration feedback gain and considering the filtering process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the acceleration feedback gain is increased to suppress vibration, then vibration suppression performance is improved, but command follow-up performance deteriorates causing operation delay and overshoot

Engineering Contradiction:

ImprovevibrationVSAvoidcommand follow-up performance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The control system is segmented into separate feedforward and feedback control paths. The feedforward controller handles command follow-up while the feedback controller handles vibration suppression, allowing independent optimization of each function without mutual interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An acceleration sensor is introduced as an intermediary to detect load acceleration independently. This sensor provides direct feedback about vibration conditions without requiring derivation from position signals, enabling accurate vibration suppression while maintaining command follow-up integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the acceleration feedback gain is set larger to reduce vibration, then settling property improves, but command follow-up performance deteriorates with operation delay and overshoot

Engineering Contradiction:

Improvesettling propertyVSAvoidoperation delay

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The feedforward controller pre-calculates and applies the torque needed for command follow-up before the feedback controller adjusts for vibrations. This preliminary action ensures that command response is not delayed by subsequent vibration compensation adjustments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts control torques by separately processing command-following torque (feedforward) and vibration-suppression torque (feedback). This dynamic separation allows the system to respond to commands immediately while simultaneously suppressing vibrations without mutual interference.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11415948B2Device for controlling electric motor

Publication Date: 2022.08.16 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An electric motor control device includes a feedforward controller, a feedback controller, and an adder-subtractor. The feedforward controller receives a position command signal to specify a target position of a control target load and outputs signals representing a target position, target speed and torque of the electric motor. The feedback controller outputs a feedback torque command signal representing a torque command to perform feedback control in such a manner that an electric motor position signal and a feedforward position command signal coincide with each other. The adder-subtractor subtracts a load acceleration feedback torque signal obtained by multiplying a load acceleration signal representing acceleration of the control target load by a load acceleration feedback gain from a torque command signal obtained by adding a feedforward torque command signal and the feedback torque command signal, and outputs a result of the subtraction as a torque command correction signal.