Power Moving Panel BLDC Position Tracking Without Sensors

Solution Overview

Problem

Existing power moving panel systems in vehicles, such as sunroofs, require position sensors to determine the rotational position of the motor shaft, which increases system cost and complexity.

Innovation Solution

A power moving panel system that uses a BLDC motor, a motor phase comparator circuit, and a microcontroller to determine the rotational position of the rotatable shaft based on zero crossing occurrences of back electromotive force (BEMF) signals without using position sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If position sensors are used to determine rotational position of the motor shaft, then measurement precision is improved, but device complexity and system cost increase

Engineering Contradiction:

Improverotational position measurementVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The motor system uses its own back electromotive force (BEMF) signals to determine rotor position, eliminating the need for external position sensors. The BEMF signals naturally generated during motor operation are processed by the controller to extract position information, making the system self-sufficient and removing additional components.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces mechanical position sensors with an electrical signal processing approach. Instead of using physical sensors to detect rotor position, the system uses electrical BEMF signals and compares their phases to determine position, substituting a mechanical sensing system with an electrical field-based solution.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If position sensors are used to determine rotational position of the motor shaft, then measurement precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improverotational position measurementVSAvoidsystem cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The motor system uses its own back electromotive force (BEMF) signals to determine rotor position, eliminating the need for external position sensors. The BEMF signals naturally generated during motor operation are processed by the controller to extract position information, making the system self-sufficient and removing additional components.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces expensive position sensors with a cost-effective signal processing method using existing BEMF signals. By utilizing already-present electrical signals and simple comparison circuitry, the system achieves accurate position measurement without investing in costly sensor hardware.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If position sensors are used to determine rotational position of the motor shaft, then measurement precision is improved, but the number of components increases

Engineering Contradiction:

Improverotational position measurementVSAvoidnumber of components

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The motor system uses its own back electromotive force (BEMF) signals to determine rotor position, eliminating the need for external position sensors. The BEMF signals naturally generated during motor operation are processed by the controller to extract position information, making the system self-sufficient and removing additional components.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The BEMF signals serve dual purposes: they are both the electrical signals needed for motor control and the position information source. This multi-functionality eliminates the need for separate position sensing components, as the same electrical signals provide both control and measurement functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 tracking of the motor's rotor position without sensors, reducing system costs and simplifying design while maintaining anti-pinch protection and automatic panel control as per FMVSS No. 118.

Implementation Method 1

a first back electromotive force (BEMF), a second BEMF, and a third BEMF produced in response to driving the motor

Methodology Applied

Scientific EffectBack electromotive force (BEMF): Electromagnetic Induction

Data Source

PatentEP4554082A1Power moving panel system

Publication Date: 2025.05.14 INTEVA PRODUCTS LLC

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AI summary

A power moving panel system includes a motor system, a motor phase comparator circuit, and a microcontroller. The motor system includes a BLDC motor and a rotatable shaft configured to rotate in response to driving the BLDC motor. The motor system is configured to adjust a position of a moveable part in response to rotating the rotatable shaft. The motor phase comparator circuit is configured to determine a plurality of zero crossing occurrences of a first, second, and third BEMFs, produced in response to driving the motor. The microcontroller is in signal communication with the motor phase comparator circuit, and is configured to determine a rotational position of the rotatable shaft based on the counting of each zero crossing occurrence corresponding to each of the first, second, and third BEMFs. Accordingly, the microcontroller determines the position of the moveable part based on the rotational position of the rotatable shaft.