Motor Current Regulator Reducing Harmonic Distortion

Solution Overview

Problem

Motor controllers face challenges in reducing harmonic distortion in current waveforms, particularly at frequencies above their bandwidth, due to modulation routines and motor design features, leading to undesirable current components and distortion.

Innovation Solution

A current regulator system that transforms feedback signals into both fundamental and harmonic frequency reference frames, using notch filters to attenuate harmonic components, allowing independent regulation in each frame and combining outputs to reduce harmonic distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a single-frequency current regulator is used, then the device complexity is low, but the harmonic distortion reduction capability is insufficient

Engineering Contradiction:

Improveharmonic distortionVSAvoidregulator structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The current regulator is divided into multiple independent frequency-specific regulators, each targeting a specific frequency range (fundamental frequency and harmonic frequencies). Each regulator processes current feedback signals at its designated frequency independently, allowing for precise harmonic distortion reduction without requiring complex interactions between frequency components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system transitions from single-frequency regulation to multi-frequency regulation by adding the frequency dimension. Multiple current regulators operate simultaneously at different frequencies (fundamental and harmonic), effectively regulating current across a broader frequency spectrum and reducing harmonic distortion components that a single regulator cannot address.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If multiple frequency-specific current regulators are used, then the harmonic distortion reduction capability is improved, but the device complexity increases

Engineering Contradiction:

Improveharmonic distortionVSAvoidregulator structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The current regulator is divided into multiple independent frequency-specific regulators, each targeting a specific frequency range (fundamental frequency and harmonic frequencies). Each regulator processes current feedback signals at its designated frequency independently, allowing for precise harmonic distortion reduction without requiring complex interactions between frequency components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each frequency-specific current regulator is designed with a universal structure that can be applied to different frequency ranges. The regulators use similar control mechanisms and feedback processing methods, allowing the system to handle multiple frequencies with consistent, proven technology rather than requiring entirely different approaches for each frequency component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Speed

If the regulator bandwidth is increased, then the frequency range covered is broader, but the precision of current regulation at specific frequencies decreases

Engineering Contradiction:

Improvefrequency response rangeVSAvoidcurrent regulation precision

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The current regulator is divided into multiple independent frequency-specific regulators, each targeting a specific frequency range (fundamental frequency and harmonic frequencies). Each regulator processes current feedback signals at its designated frequency independently, allowing for precise harmonic distortion reduction without requiring complex interactions between frequency components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically allocates regulation resources by using multiple specialized regulators that can be independently tuned and optimized for their specific frequency ranges. This dynamic approach allows each regulator to maintain high precision at its target frequency while collectively covering a broad frequency spectrum, rather than using a single static regulator with compromised performance.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10483902B1System and method for reducing current harmonic distortion in a motor controller

Publication Date: 2019.11.19 ROCKWELL AUTOMATION TECH INC

AI summary

A current regulator for a motor controller reduces distortion of the current output to a motor. Feedback signals corresponding to the current present on the motor are transformed into a fundamental and a harmonic reference frame. Notch filters in each reference frame attenuate components of the current feedback signal from the other reference frame. Current regulators in each reference frame receive the filtered current feedback signal in the corresponding reference frame and generate an output signal that is used to regulate the output current to the motor to the desired level of current in the corresponding reference frame. The output signal from the regulator in the harmonic reference frame is transformed to the fundamental reference frame, and the output of the two regulators are combined in a common reference frame to generate a reference signal corresponding to the required voltage output to the motor to achieve desired operation.