Motor Drive Sampling Adjustment for Current Detection Consistency
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Solution Overview
Problem
The difference in response characteristics between current detection circuits with varying current detectors and A/D converters affects motor controllability, as different detectors (shunt resistors or Hall elements) and models have distinct response times, leading to inconsistencies in current detection values and motor control performance.
Innovation Solution
A motor drive device incorporates a sampling adjustment unit that adjusts the sampling operation of the A/D converter based on the response time of the current detector, ensuring consistent digital data output regardless of the detector's response speed, by delaying or advancing the sampling timing for successive approximation A/D converters or adjusting the sampling interval for ΔΣ modulation A/D converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different current detectors (shunt resistors or Hall elements) with varying response times are used in current detection circuits, then the adaptability and versatility of the motor drive device is improved, but the measurement precision and consistency of current detection values deteriorate
Solution Approach 1:
The patent changes the sampling timing parameter of the A/D converter based on the response time characteristics of different current detectors. By adjusting when the sampling occurs relative to the detector's response cycle, the system compensates for variations in detector response times, ensuring consistent current detection values across different detector types while maintaining adaptability.
2Device complexity
If the sampling timing of the A/D converter is fixed, then the device complexity is reduced, but the measurement precision of current detection values deteriorates due to varying detector response times
Solution Approach 1:
The patent introduces dynamic adjustment of the sampling timing based on the response time characteristics of the current detector. The sampling timing is no longer fixed but adapts dynamically to match the detector's response characteristics, thereby maintaining measurement precision without significantly increasing system complexity.
3Speed
If latest current detectors with shorter response times are used to improve motor controllability, then the speed of current detection is improved, but the reliability of consistent performance across different detector models deteriorates
Solution Approach 1:
The patent adjusts the sampling timing parameter according to the response time of each current detector model. This parameter change compensates for the varying response speeds of different detectors, ensuring that the sampling captures accurate current values regardless of the detector's response time, thereby maintaining reliable and consistent motor control performance.
Data Source
AI summary
A motor drive device includes a power conversion unit configured to supply a drive current to a motor, a current detector configured to detect a current flowing from the power conversion unit into the motor, an A/D converter configured to convert the current detected by the current detector into digital data and outputs the digital data, a motor control unit configured to control the drive current supplied from the power conversion unit to the motor, using the digital data output from the A/D converter, and a sampling adjustment unit configured to adjust a sampling operation of the A/D converter performed for the current detected by the current detector, in accordance with the response time taken after the current detector detects the current until the A/D converter outputs the digital data of the current.