EC Motor Commutation Control Using Field-Weakening Current

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Solution Overview

Problem

Existing technologies fail to effectively avoid or significantly reduce commutation angle errors in EC engines, which can lead to engine instability and failure.

Innovation Solution

A regulatory device is implemented to reduce commutation angle errors by using a field-weakening current component (FSK) that counteracts the magnetic field of the permanent magnet, thereby improving engine control and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If field-oriented control is used to control the EC motor, then the motor control precision is improved, but commutation angle error occurs leading to instability

Engineering Contradiction:
Improve rotor position detection precisionVSAvoidmotor operation stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the actual rotor position is continuously monitored and compared with the detected rotor position. The commutation angle error is calculated from this comparison and fed back to the control system. The control system then adjusts the commutation timing based on this feedback to compensate for the error, thereby maintaining stable motor operation while preserving precise field-oriented control.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If commutation offset correction is applied, then the rotor position accuracy is improved, but the commutation angle error persists due to field-weakening current

Engineering Contradiction:
Improverotor position accuracyVSAvoidcommutation angle error
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent addresses the commutation angle error caused by field-weakening current by dynamically adjusting control parameters. Specifically, the control system modifies the commutation timing and current control parameters in response to detected commutation angle errors. This parameter adjustment compensates for the phase shift introduced by field-weakening current, thereby maintaining both rotor position accuracy and eliminating commutation angle error.

Inventive Principle:
Principle #35Parameter changes

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 proposed solution effectively reduces or avoids commutation angle errors, enhancing the stability and operational reliability of EC engines by improving the engine control system through the use of a field-weakening current component.

Implementation Method 1

A regulatory device is implemented to reduce commutation angle errors by using a field-weakening current component (FSK) that counteracts the magnetic field of the permanent magnet

Methodology Applied
Scientific EffectElectromagnetic field generation: Electromagnetic Induction

Data Source

PatentEP3896840B1Control device and method for reducing commutation angle error in an ec motor
Publication Date: 2025.04.30 EBM PAPST MULFINGEN GMBH & CO KG
  • EP3896840B1 patent drawingFigure 1~2
  • EP3896840B1 patent drawingFigure 3~4
  • EP3896840B1 patent drawingFigure 5~6

AI summary

The invention relates to a control device (1) designed to reduce the commutation angle error ε of a three-phase (u,v,w) EC motor (2.2) connected via a star connection, the three phases (u,v,w) of which are commutated via a motor controller (3), comprising a rotor position detection (4) to detect the relative angular position of the rotor by means of the star point potential at the star point of the star connection, and a control loop (10) which is designed to impress a field-weakening current component on the motor controller (3) to reduce the commutation angle error ε.