Motor Feedback Control Synchronizing Phase Currents
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Solution Overview
Problem
The accuracy of feedback control in polyphase electric motors is compromised due to the need for multiple A/D conversion units, which increases costs, and the timing differences in current detection data from current sensors, leading to reduced motor drive control accuracy.
Innovation Solution
A feedback control method that performs digital conversion of phase current detection signals sequentially at intervals, correcting pole positions based on a reference time point to synchronize data for fixed/rotating coordinate transformation, allowing for accurate control with a single A/D conversion unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple A/D conversion units are used for simultaneous digital conversion of three-phase current detection signals, then conversion accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by performing sequential digital conversion of three-phase current detection signals in a predetermined order (U-phase, V-phase, W-phase) rather than simultaneous conversion. The pole position correction values are calculated in advance based on the conversion timing, allowing the system to achieve accurate synchronous transformation without requiring multiple A/D conversion units. This resolves the contradiction by maintaining measurement precision through ordered processing while reducing device complexity to a single A/D conversion unit.
2Device complexity
If sequential digital conversion of phase currents is performed with a single A/D unit, then device complexity is reduced, but timing differences cause reduced measurement precision
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the pole position correction values based on the sequential conversion timing of each phase. The correction values are calculated to compensate for the time interval between conversions, effectively synchronizing the current data to a common reference time point. This resolves the contradiction by maintaining measurement precision through parameter adjustment while using only a single A/D conversion unit for sequential processing.
3Measurement precision
If current detection data is corrected for pole position to synchronize timing, then feedback control accuracy is improved, but calculation complexity increases
Solution Approach 1:
The patent applies self-service by having the control device perform the pole position correction calculations automatically as part of its normal operation. The correction values are computed based on the known sequential conversion timing and the motor's rotational speed, integrating the synchronization function into the existing control workflow without requiring external intervention or complex additional processing systems.
Data Source
AI summary
A feedback control method and apparatus for detecting phase currents of three or more phases on fixed coordinates of a polyphase electric motor with current sensors so as to be transformed into detection currents on rotating coordinates by fixed/rotating coordinate transformation and controlling the currents supplied to respective phases of the polyphase electric motor based on the detection currents on the rotating coordinates and target currents on the rotating coordinates.