Electric Machine Control Calibration for Rotor Angle Direction

Solution Overview

Problem

Existing electrical drive systems face challenges in accurately determining the rotor angle and direction of rotation, leading to potential safety issues such as incorrect direction of rotation and unintended vehicle movement due to incorrect rotor offset angles and phase sequence determination.

Innovation Solution

A method and device for calibrating the control of an electrical machine by applying an electrical test signal with a predetermined direction in the dq coordinate system, allowing for the determination of the rotor's direction of rotation and orientation of the dq coordinate system, even when the exact orientation is unknown, and compensating for rotor offset angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If sensorless drive systems are used to reduce system costs and improve robustness, then the quantity of components is reduced, but the measurement precision of rotor angle deteriorates

Engineering Contradiction:

Improvequantity of componentsVSAvoidmeasurement precision of rotor angle

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical angle sensors with a sensorless measurement method that uses electrical test signals and anisotropy detection to determine rotor position and dq coordinate system orientation, thereby eliminating physical sensors while maintaining measurement capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary measurement approach using high-frequency test signals and anisotropy detection as a mediator between the electrical machine and the control system, enabling indirect but accurate determination of rotor position without direct mechanical sensing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the rotor offset angle is determined with insufficient accuracy, then the ease of operation is improved, but the reliability of rotation direction determination deteriorates

Engineering Contradiction:

Improveease of operationVSAvoidreliability of rotation direction determination

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent performs preliminary calibration actions by applying test signals in specific directions before normal operation to determine the correct dq coordinate system orientation and rotor offset angle, ensuring reliable rotation direction determination is established in advance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by measuring the rotor angle change in response to test signals and using this information to verify or correct the assumed dq coordinate system orientation, thereby ensuring reliable determination of rotation direction

Inventive Principle:

Principle #23Feedback

3Device complexity

If the dq coordinate system orientation is not precisely known, then the device complexity is reduced, but the manufacturing precision of control calibration deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidmanufacturing precision of control calibration

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary calibration actions by applying test signals in specific directions before normal operation to determine the correct dq coordinate system orientation and rotor offset angle, ensuring reliable rotation direction determination is established in advance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by measuring the rotor angle change in response to test signals and using this information to verify or correct the assumed dq coordinate system orientation, thereby ensuring reliable determination of rotation direction

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

Enables precise calibration of the control system, preventing incorrect rotation and ensuring accurate movement control of electrical machines, particularly in vehicles, by reliably determining the dq coordinate system orientation and compensating for rotor offset angles.

Implementation Method 1

an electrical machine (6) ... is controlled by a controller (5). The signal generator (2) generates an electrical test signal, which is applied to the electric machine (6) by the controller (5)

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the anisotropy of the electric machine can be determined. For example, the position and angle dependence of the electric machine can be determined using high-frequency excitation

Methodology Applied

Scientific EffectAnisotropy measurement: Anisotropy

Data Source

PatentEP4052367B1Method and device for calibrating the control of an electric machine

Publication Date: 2025.09.17 ROBERT BOSCH GMBH

Figure 1~2

AI summary

The invention relates to a method for calibrating the control of an electrical machine, comprising the steps of: applying at least one electrical test signal having a specified direction in a d-q coordinate system to the electrical machine; measuring the change in the rotor angle of a rotor of the electrical machine according to the applied at least one electrical test signal; and calibrating the control of the electrical machine, the control being carried out using the d-q coordinate system, and the orientation of the d-q coordinate system being determined on the basis of the measured change in the rotor angle of the rotor of the electrical machine.