ECM Motor Self-Calibration via Current and Acceleration

Solution Overview

Problem

Existing calibration methods for electronically commutated motors (ECMs) in HVAC systems are complex and time-consuming, requiring specialized facilities and equipment, especially when the motor and drive are separately purchased or need to be recalibrated due to wear or replacement.

Innovation Solution

A control system and method that dynamically calibrates the motor by defining a reference speed, measuring currents and angular acceleration at specific operating points, and estimating a calibration coefficient to determine torque, allowing for on-site calibration without a test fixture or controlled environment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional calibration methods are used for ECM motors, then measurement precision can be achieved, but device complexity and time consumption increase significantly

Engineering Contradiction:

Improvecalibration accuracyVSAvoidcalibration system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The motor calibration system performs self-calibration by using its own operational data (current, speed, voltage) to determine calibration coefficients. The control unit executes calibration routines where the motor operates at different speeds and the system measures electrical parameters to calculate calibration coefficients without requiring external test fixtures or specialized equipment.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces mechanical test fixtures and physical measurement equipment with electrical measurements and computational algorithms. Instead of using mechanical dynamometers or test benches to measure motor torque and performance, the system uses electrical current, voltage, and speed measurements combined with mathematical models to determine calibration coefficients.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If traditional calibration methods are used for ECM motors, then measurement precision can be achieved, but loss of time increases due to complex procedures

Engineering Contradiction:

Improvecalibration accuracyVSAvoidcalibration time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The motor calibration system performs self-calibration by using its own operational data (current, speed, voltage) to determine calibration coefficients. The control unit executes calibration routines where the motor operates at different speeds and the system measures electrical parameters to calculate calibration coefficients without requiring external test fixtures or specialized equipment.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system performs preliminary calibration actions by operating the motor at predetermined speeds and collecting electrical parameter data before final calibration coefficient determination. The control unit prepares calibration data by having the motor run through specific operational sequences, storing current, voltage, and speed measurements for subsequent coefficient calculation.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If on-site calibration is implemented without test fixtures, then ease of operation improves, but measurement precision may be compromised

Engineering Contradiction:

Improvecalibration accessibilityVSAvoidcalibration accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical test fixtures and physical measurement equipment with electrical measurements and computational algorithms. Instead of using mechanical dynamometers or test benches to measure motor torque and performance, the system uses electrical current, voltage, and speed measurements combined with mathematical models to determine calibration coefficients.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The calibration system uses feedback from measured electrical parameters (current, voltage, speed) to iteratively determine and refine calibration coefficients. The control unit continuously monitors motor operation during calibration routines and adjusts coefficient calculations based on actual measured data, ensuring accuracy despite the simplified on-site setup.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10855211B2Self-calibration of ECM motor and variable frequency drive inferred torque

Publication Date: 2020.12.01 TRANE INTERNATIONAL INC

AI summary

A method for calibrating a motor is provided. The method includes defining a reference speed for operating the motor; operating the motor until a first operating point at which the motor reaches the reference speed; measuring a first current of the motor and an angular acceleration associated with the first current at the first operating point; operating the motor until a second operating point at which the motor reaches the reference speed; measuring a second current of the motor at the second operating point; and estimating a calibration coefficient for calibrating the motor based at least on the first current, the second current, and the angular acceleration associated with the first current.