Motor Current Detection Using Instantaneous and Average Current Separation
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Solution Overview
Problem
In motor devices where the motor and driver are integrated, existing methods for detecting motor current become inaccurate due to the drive current flowing through the same wire as the motor current, making it difficult to obtain precise motor current measurements.
Innovation Solution
A motor current detecting device comprising a first wire for both motor and drive currents, an instantaneous current detecting unit, an average current detecting unit, and a calculation unit that calculates the motor current by subtracting an offset value from the average value of the sum of motor and drive currents, allowing for precise determination of motor current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the motor and driver are integrated into a motor device, then the device structure is simplified, but the motor current measurement accuracy deteriorates because the drive current flows through the same wire as the motor current
Solution Approach 1:
The patent segments the current measurement into two distinct components: instantaneous current detection (capturing both motor and drive currents) and average current detection (capturing primarily motor current). By separating these measurement functions and processing them differently, the system can extract accurate motor current information even when drive current is present in the same wire.
Solution Approach 2:
The patent performs preliminary action by detecting the instantaneous current before the drive current becomes significant, and using this early detection data along with average current data to calculate the motor current. This timing-based separation allows the system to isolate motor current from drive current interference.
2Measurement precision
If the instantaneous value and average value of the sum of motor current and drive current are both used, then the motor current calculation accuracy is improved, but the calculation complexity increases
Solution Approach 1:
The patent applies self-service by using the detected instantaneous and average current values to automatically determine the drive current offset, which is then subtracted from the average value to obtain the motor current. The system uses its own measurement data to perform the correction without requiring external calibration or complex algorithms.
Data Source
AI summary
A motor current detecting device includes a first wire, an instantaneous current detecting unit, an average electric current detecting unit, and a calculation unit. The first wire is configured and arranged to carry flow of a motor current that has been passed through a motor and a drive current that has been passed through a motor drive unit to drive the motor. The instantaneous current detecting unit is configured and arranged to detect an instantaneous value for a sum of the motor current and the drive current flowing on the first wire. The average electric current detecting unit is configured and arranged to detect an average value of the sum of the motor current and the drive current flowing on the first wire. The calculation unit is configured to calculate the motor current on the basis of the instantaneous value and the average value.