Motor Terminal Voltage Detection via Dynamic Channel Compensation

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Solution Overview

Problem

Existing methods for detecting terminal voltage in electric motors face challenges due to non-linear properties of measurement channels, leading to inaccurate determination of motor position and speed, and are costly due to the need for high-quality components and active components like operational amplifiers.

Innovation Solution

A method that applies a voltage jump to the measurement channel using existing switching elements to record the dynamic behavior as a step response, determining a correction parameter to compensate for both static and dynamic behavior, allowing for accurate terminal voltage detection without additional components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-quality components and active components like operational amplifiers are used in the measurement channel, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improveterminal voltage detection accuracyVSAvoidmeasurement channel complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measurement channel uses itself to characterize its own non-linear behavior. By applying a known test voltage and measuring the channel's own response, the system automatically determines correction parameters without requiring external calibration equipment or complex active components. This self-characterization approach resolves the contradiction by achieving high measurement precision through software-based correction rather than hardware complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the operating parameters of the measurement channel by applying different test voltages (including negative voltages) to characterize its non-linear behavior. By varying the voltage parameter and measuring the corresponding current response, the system builds a correction model that compensates for non-linearities. This parameter-based approach replaces the need for complex active components with a software correction strategy.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If non-linear elements are included in the measurement channel, then functionality is improved, but measurement precision deteriorates

Engineering Contradiction:
Improvemeasurement channel functionalityVSAvoidterminal voltage accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The invention converts the harmful non-linear behavior of measurement channel elements into a beneficial characteristic. By deliberately characterizing the non-linear current-voltage relationship through test measurements and storing correction parameters, the system transforms what was previously a source of measurement error into a known, compensatable feature. The non-linear elements remain in the circuit for functionality, but their effect is now predictable and correctable through software.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If static behavior correction is applied to the measurement channel, then measurement precision is improved, but dynamic behavior deviations remain uncorrected

Engineering Contradiction:
Improvestatic measurement accuracyVSAvoiddynamic measurement accuracy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention transitions from static correction to dynamic correction by characterizing the measurement channel's behavior under varying voltage conditions. The system applies different voltage levels and measures the corresponding current responses to build a dynamic correction model. This allows the correction parameters to account for time-varying and voltage-dependent non-linearities, improving reliability across both static and dynamic operating conditions.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2593800B1Method or voltage detection system for determining a correction parameter for a measurement channel and for detecting a terminal voltage of an electric motor
Publication Date: 2018.09.26 ROBERT BOSCH GMBH
  • EP2593800B1 patent drawingFigure 1

AI summary

The invention relates to a method for determining a correction parameter for a measurement channel (6) which is connected to a connection terminal (3) of an electric motor (2) in order to measure a terminal voltage (U1, U2), characterized in that - the connection terminal (3) is connected to a first potential via switching elements (T1, T2, T3, T4) for driving the electric motor (2), - after a steady state of the measurement channel (6) has been reached, the connection terminal (3) is connected to a second potential, which differs from the first, by changing over at least one switching element (T1, T2, T3, T4), - the dynamic response of the measurement channel (6) is detected following connection to the second potential, and - the correction parameter for the dynamic response of the measurement channel (6) is determined on the basis of the detected dynamic response of the latter.