Motor Driving Device Current Sampling Timing

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Solution Overview

Problem

Existing motor driving devices are unable to accurately detect the current supplied to motors, which hinders reliable motor control.

Innovation Solution

A motor driving device comprising an inverter unit, switching circuit, current sensors, acquisition unit, selection unit, and control unit that acquires and selects data from different data acquisition periods to accurately determine the motor current, thereby enabling precise control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If current sampling is performed at crests of triangular-wave carrier signal, then sampling timing is simplified, but current detection accuracy deteriorates due to transient currents from switching operations

Engineering Contradiction:

Improvesampling timing simplicityVSAvoidcurrent detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent segments the data acquisition process into multiple periods with different lengths. The selection unit divides acquisition periods into a first acquisition period (shorter, excluding switching transient period) and a second acquisition period (longer, including switching transient period), allowing separate processing of data from different time windows to eliminate the contradiction between simple timing and accurate measurement

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent dynamically adjusts the data acquisition strategy by selecting between different acquisition period lengths based on the specific timing conditions. The selection unit determines whether to use the first or second acquisition period data based on comparison with a predetermined threshold, making the system adaptive to different operating conditions rather than using a fixed sampling approach

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If data acquisition period is shortened to exclude switching transient period, then current detection accuracy improves, but data acquisition frequency decreases

Engineering Contradiction:

Improvecurrent detection accuracyVSAvoiddata acquisition frequency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent merges two different data acquisition approaches by maintaining both a first acquisition period (shorter, accurate) and a second acquisition period (longer, higher frequency). The selection unit combines these by choosing appropriate data from either period based on timing conditions, thereby achieving both high accuracy and maintained data acquisition frequency through selective combination of multiple data sources

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11424710B2Motor driving device

Publication Date: 2022.08.23 FANUC LTD

AI summary

A motor driving device includes an acquisition unit configured to acquire multiple pieces of data in data acquisition periods having different lengths; a selection unit configured to select a piece of data from among the multiple pieces of data, based on timing at which a switching circuit switches switching devices; and a control unit configured to control the switching circuit based on the selected data.