Induction Machine Torque Prediction for Load Pattern Control
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Solution Overview
Problem
Induction machines face inefficiencies due to rapid changes in load, leading to overcurrent conditions and significant power consumption when trying to maintain torque delivery.
Innovation Solution
The method predicts a load pattern by determining a torque error using a low pass filter function, identifying a torque increase pulse, and calculating a change delay time and period to increase the flux current ahead of a predicted change time, ensuring efficient torque supply without flux current spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the flux current is increased rapidly to maintain torque delivery during rapid load changes, then the torque supply capability is improved, but the power consumption and overcurrent conditions worsen
Solution Approach 1:
The system performs preliminary action by predicting future load changes using a load pattern predictor that analyzes torque variations and determines change periods. The flux current is adjusted in advance based on predicted load patterns, allowing the induction machine to maintain torque delivery during rapid load changes without requiring sudden, energy-intensive current increases. This proactive approach reduces power consumption by avoiding reactive overcurrent conditions.
2Power
If the flux current is increased rapidly to respond to load changes, then the torque delivery is improved, but overcurrent conditions occur
Solution Approach 1:
The load pattern predictor determines change periods by analyzing multiple torque variations and predicts future load changes. The flux current adjustment is performed in advance based on these predictions, allowing the system to smoothly track load requirements without sudden current spikes. This eliminates overcurrent conditions while maintaining adequate torque delivery capability.
Solution Approach 2:
The system continuously monitors torque variations and uses this feedback to update load pattern predictions. The torque error signal is processed through the load pattern predictor, which adjusts flux current commands based on predicted load behavior. This closed-loop feedback mechanism ensures torque delivery is maintained while preventing overcurrent conditions by adapting to actual load patterns.
3Adaptability or versatility
If conventional control methods are used to handle rapid load changes, then the system responds to load changes, but efficiency is reduced due to flux current spikes
Solution Approach 1:
The load pattern predictor performs preliminary analysis of torque variations to determine change periods and predict future load changes. This allows the flux current to be adjusted smoothly in advance, maintaining adaptability to load changes while eliminating the flux current spikes that cause power loss in conventional control methods.
Data Source
AI summary
For predicting a load pattern, a method determines a torque error from a torque reference modified by a low pass filter function of the torque reference. The torque reference is one of measured from an induction machine energized by a flux current and a torque current and calculated in an induction machine controller. The method determines a torque increase pulse in response to a torque relative variation calculated from the torque error exceeding an increase threshold. In response to detecting the torque increase pulse, the method determines a change delay time from the torque relative variation and the torque increase pulse. The method further determines a change period from at least two torque increase pulses. The method increases the flux current before a change time that is predicted as a function of the change delay time and the change period.