Induction Machine Current Reference Correction via Torque Segmentation
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Solution Overview
Problem
Conventional position sensorless vector control of induction machines faces instability at low speeds and low torque due to inaccurate magnetic flux estimation, requiring complex calculations for correction factors, which demand high computational power and time.
Innovation Solution
An apparatus that calculates a correction factor based on candidate values to satisfy minimum excitation current conditions for the induction machine, allowing for rapid calculation under rated operating conditions with reduced computational power by setting first and second torque reference sections and adjusting the correction factor proportionally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a correction factor is calculated using complicated equations with various limited conditions to improve magnetic flux estimation accuracy, then the driving stability is improved, but the computational power requirement increases and arithmetic operation time increases
Solution Approach 1:
The patent segments the correction factor calculation into multiple candidate values (first candidate value, second candidate value, third candidate value) corresponding to different operating conditions. Each candidate value satisfies specific limited conditions (rated slip frequency condition, rated voltage condition, rated current condition), allowing the system to select appropriate correction factors without computing all conditions simultaneously, thus reducing computational power while maintaining driving stability.
Solution Approach 2:
The patent performs preliminary calculation of multiple candidate correction factor values before actual operation. These candidate values are pre-calculated based on different operating conditions and stored for quick selection during runtime. This preliminary action eliminates the need for complex real-time calculations, reducing both computational power requirements and arithmetic operation time while ensuring driving stability through accurate magnetic flux estimation.
2Reliability
If a correction factor is calculated using complicated equations with various limited conditions to improve magnetic flux estimation accuracy, then the driving stability is improved, but the arithmetic operation time increases
Solution Approach 1:
The patent divides the correction factor determination into discrete candidate values, each associated with specific operating conditions. During operation, the system segments the decision process into: (1) identifying current operating condition, (2) selecting corresponding candidate correction factor, (3) applying the selected factor. This segmented approach eliminates complex real-time equation solving, dramatically reducing arithmetic operation time while maintaining driving stability through accurate magnetic flux estimation.
Solution Approach 2:
The patent performs preliminary calculation and storage of multiple candidate correction factor values covering various operating conditions before actual motor operation. This preliminary action creates a lookup table of pre-computed values that can be quickly retrieved and applied during runtime, eliminating the need for complex arithmetic operations during critical control periods, thus reducing arithmetic operation time while ensuring driving stability.
3Reliability
If the magnitude of magnetic flux current is varied using a correction factor calculated from complicated equations to improve sensorless torque mode performance, then the unstable driving performance is improved, but the device complexity increases
Solution Approach 1:
The patent segments the complex control algorithm into modular components: (1) identification of operating condition type, (2) selection of corresponding candidate correction factor from pre-calculated sets, (3) application of selected correction factor to magnetic flux current. This modular segmentation simplifies the overall control algorithm structure, making it easier to implement and maintain while improving sensorless torque mode performance through accurate magnetic flux estimation.
Solution Approach 2:
The patent changes the control approach from continuous complex equation solving to discrete parameter selection. Instead of computing correction factors continuously through complicated equations, the system uses parameter changes by selecting from pre-calculated candidate correction factor values based on operating conditions. This parameter-based approach reduces control algorithm complexity while maintaining the ability to vary magnetic flux current magnitude for improved sensorless torque mode performance.
Data Source
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AI summary
The present disclosure relates to an apparatus (100) for correcting a current reference, and more particularly, to an apparatus (100) for correcting a current reference including a calculation unit (110) configured to set a first torque reference section and a second torque reference section using candidate values of a correction factor that corrects the current reference so as to enable the current reference to satisfy rated operating conditions of the induction machine, and calculate the correction factor according to a section, in which the torque reference is included, of the first torque reference section and the second torque reference section, and a correction unit (120) configured to correct the current reference using the correction factor. As described above, in accordance with the present disclosure, a correction factor is calculated from a minimum value among the candidate values of the correction factor satisfying a minimum excitation current condition of the induction machine when the torque reference is included in the first torque reference section, whereas the correction factor is calculated in proportion to the torque reference when the torque reference is included in the second torque reference section so that there is an effect in which the correction factor satisfying the rated operating conditions of the induction machine may be rapidly calculated with low computing power.