Motor Controller Feed-Forward Induced Voltage Compensation

Solution Overview

Problem

Conventional motor driving control methods, particularly the 120-degree conduction method, suffer from reduced speed responsivity due to the neglect of induced voltage in speed control gain design, leading to potential overcurrent issues when attempting to improve speed response.

Innovation Solution

A motor controller is configured with a rotational speed acquirer, a commanded voltage calculator, and a feed-forward compensator that compensates the commanded voltage with a smoothed feed-forward compensation value equal to the induced voltage, improving speed responsivity while preventing overcurrents through smoothing processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the speed control gain is increased to improve speed responsivity, then the speed response becomes faster, but an overcurrent may be caused

Engineering Contradiction:

Improvespeed responsivityVSAvoidovercurrent

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The feed-forward compensator performs preliminary action by calculating and compensating for the induced voltage based on the target rotational speed before the motor actually reaches that speed. This proactive compensation prevents the need for excessive speed control gain, thereby avoiding overcurrent while maintaining fast speed response. The compensation value is calculated in advance using the relationship between rotational speed and induced voltage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring the actual rotational speed and using it to adjust the feed-forward compensation value. The smoothing processing unit processes this feedback information to generate a stable compensation signal that adapts to changing operating conditions, preventing overcurrent while maintaining responsive speed control.

Inventive Principle:

Principle #23Feedback

2Device complexity

If a 120-degree conduction method is used for simple and inexpensive control, then the device complexity is reduced, but the speed responsivity is lowered due to neglecting induced voltage

Engineering Contradiction:

Improvecontrol structure simplicityVSAvoidspeed responsivity

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The feed-forward compensator performs preliminary action by calculating and compensating for the induced voltage based on the target rotational speed before the motor actually reaches that speed. This proactive compensation prevents the need for excessive speed control gain, thereby avoiding overcurrent while maintaining fast speed response. The compensation value is calculated in advance using the relationship between rotational speed and induced voltage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring the actual rotational speed and using it to adjust the feed-forward compensation value. The smoothing processing unit processes this feedback information to generate a stable compensation signal that adapts to changing operating conditions, preventing overcurrent while maintaining responsive speed control.

Inventive Principle:

Principle #23Feedback

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

This approach enhances speed responsivity and suppresses overcurrents, enabling the motor to rapidly follow rotational speed commands while maintaining stable operation and reducing costs.

Implementation Method 1

the generation of an induced voltage (Back_EMF) is ignored

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10873281B2Motor controller and motor control method

Publication Date: 2020.12.22 NIDEC CORP(JP)

AI summary

A motor controller is configured or programmed to include a rotational speed acquirer to acquire an actual rotational speed of a motor including a rotor that includes permanent magnets, a commanded voltage calculator to calculate a commanded voltage to be supplied to the motor based on a difference between the actual rotational speed and a target rotational speed, and a feed-forward compensator to compensate the commanded voltage by an amount equal to an induced voltage in the motor based on the target rotational speed. The feed-forward compensator includes a compensation value calculator to calculate a feed-forward compensation value on which smoothing processing has been performed and an adder to add the feed-forward compensation value to the commanded voltage.