Dual-Motor Resolver Offset Learning Without Torque Loss

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Solution Overview

Problem

Resolver offset learning in electric vehicles during vehicle operation leads to a sense of heterogeneity due to zero torque output, causing vehicle backward movement and limiting the conditions under which precise motor torque control can be achieved.

Innovation Solution

A method of controlling motor torque where the torque reduction generated by a drive motor during resolver offset learning is compensated by another drive motor, ensuring that driver request torque is maintained and resolver offset learning is performed stably, even during vehicle operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If resolver offset learning is performed during vehicle running with zero torque output, then measurement precision of motor electric angle is improved, but driver request torque satisfaction deteriorates causing sense of heterogeneity

Engineering Contradiction:

Improveresolver offset learning precisionVSAvoiddriver request torque satisfaction

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent combines the operations of two drive motors (main drive motor and auxiliary drive motor) to perform resolver offset learning. While one motor performs learning with zero torque output, the other motor compensates by providing the required torque to satisfy driver demand, merging their functions to resolve the contradiction between measurement precision and operational smoothness

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The auxiliary drive motor acts as an intermediary that compensates for the torque reduction caused by the learning drive motor's zero torque output. This intermediary motor ensures that the total torque output meets driver request torque while allowing the learning motor to operate in zero torque condition for accurate offset learning

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If resolver offset learning is performed during coasting, then measurement precision is improved, but vehicle stability deteriorates due to backward movement

Engineering Contradiction:

Improveresolver offset learning precisionVSAvoidvehicle stability

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent merges the torque output of main and auxiliary drive motors to maintain total regeneration torque during coasting. When one motor performs offset learning with zero torque, the other motor compensates to maintain overall vehicle stability and prevent backward movement

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The non-learning drive motor serves as an intermediary that compensates for the torque reduction during coasting. It maintains the total regeneration torque level by providing additional torque output, preventing vehicle instability and backward movement while allowing the learning motor to operate in zero torque condition

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If resolver offset learning is performed with limited conditions, then ease of operation is maintained, but productivity of offset learning deteriorates

Engineering Contradiction:

Improveoperation smoothnessVSAvoidoffset learning frequency

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent combines the capabilities of two drive motors to expand the conditions under which offset learning can be performed. By having one motor handle learning while the other compensates for torque requirements, the system can perform learning more frequently and under diverse driving conditions without compromising operational smoothness

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system implements multi-functionality where each drive motor can alternatively perform either normal torque output or resolver offset learning. This universality allows offset learning to be performed under various driving conditions (acceleration, coasting, deceleration) by dynamically assigning which motor performs learning, thereby increasing learning productivity while maintaining ease of operation

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11820355B2Method of controlling motor torque for learning resolver offset of electric vehicle

Publication Date: 2023.11.21 HYUNDAI MOTOR CO LTD

AI summary

A method of controlling motor torque for learning a resolver offset of an electric vehicle includes steps of: determining whether a condition for offset learning mounted to a main drive motor and to an auxiliary drive motor is satisfied; controlling an output torque of a learning drive motor, which includes a resolver to perform the offset learning among the main drive motor and the auxiliary drive motor to a zero torque, when the condition for performing the offset learning is satisfied; increasing an output torque of a non-learning drive motor, which includes a resolver not performing the offset learning among the main drive motor and the auxiliary drive motor by a torque reduction amount, when the learning drive motor outputs zero torque; and performing the offset learning of the resolver mounted to the learning drive motor.