Variable Inductance Electric Drive Control for Stability
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Solution Overview
Problem
Conventional electric machine control units experience unstable operation due to varying inductances Ld and Lq, which affect the control system characteristics, leading to unstable driving of electric machines.
Innovation Solution
An electric drive control apparatus and method that calculate current command values, inductances, interference terms, proportional, and integral terms to adjust voltage command values, ensuring stable operation by accounting for changes in current and inductance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electric machine control units use fixed inductance values Ld and Lq, then the control system characteristics remain constant, but the system cannot adapt to varying driving states
Solution Approach 1:
The patent applies dynamics by making the inductance values Ld and Lq variable rather than fixed. The control unit dynamically adjusts these inductance parameters based on the detected driving state (current magnitude and direction), allowing the control system to adapt to different operating conditions while maintaining stable operation through state-dependent parameter optimization
2Adaptability or versatility
If the inductances Ld and Lq are varied to adapt to different driving states, then the adaptability improves, but the control system characteristics change leading to instability
Solution Approach 1:
The patent applies parameter changes by systematically varying the inductance parameters Ld and Lq based on the driving state. Specifically, different inductance values are selected according to the current magnitude (small current region vs. large current region) and direction (motoring vs. generating), allowing the system to optimize performance for each operating condition while maintaining overall stability through controlled parameter transitions
3Speed
If the control system uses region-based inductance selection, then the responsiveness to current changes improves, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the operating range into distinct regions based on current magnitude (small current region with threshold Ith1 and large current region with threshold Ith2) and current direction (motoring and generating regions). This segmentation allows the control unit to select appropriate inductance values for each region, improving responsiveness to current changes while managing complexity through structured regional classification
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution maintains stable control system characteristics across varying driving states, enhancing the stability and responsiveness of electric machine control units.
Implementation Method 1
the drive motor control unit calculates a d-axis voltage command value and a q-axis voltage command value each represent the target value of the d-axis voltage and the q-axis voltage calculated based on the deviation between the d-axis current and the d-axis current command value, the deviation between the q-axis current and the q-axis current command value, and parameters of the drive motor
Data Source
AI summary
An electric drive control apparatus and method calculates a current command value based on an electric machine target torque that represents a target value of a torque of an electric machine; calculates a current deviation between the current command value and a current applied to the electric machine; calculates a first inductance and a second inductance that each have a different amount of change caused by a change in the current; calculates an interference term based on the first inductance; calculates a proportional term and an integral term based on the current deviation and the second inductance; and calculates a voltage command value based on the interference term, the proportional term and the integral term.