AC Motor Control Voltage Saturation Handling
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Solution Overview
Problem
Existing AC motor control apparatuses face issues with voltage saturation due to dimension differences between winding groups, leading to reduced output torque and increased noise in electric power steering systems, as they cannot utilize voltage commands up to saturation voltage effectively and often result in unstable control due to excessive current ripple.
Innovation Solution
A control apparatus for AC rotary machines that includes a current detection unit, sum voltage calculation, differential voltage calculation, and a voltage saturation determination unit to adjust voltage commands and reduce gain in saturated axes, ensuring voltage commands can be used up to saturation voltage in each winding group, even with dimension differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If voltage saturation determination is implemented to adjust voltage commands in AC rotary machine control, then voltage commands can be utilized up to saturation voltage effectively, but control complexity increases due to additional determination and adjustment mechanisms
Solution Approach 1:
The control apparatus determines whether voltage saturation has occurred before final voltage command generation. By performing saturation determination in advance and preparing adjusted voltage commands accordingly, the system ensures optimal voltage utilization without causing torque reduction or instability, while organizing complex control logic in a structured sequence
Solution Approach 2:
The control apparatus continuously monitors voltage saturation status and adjusts voltage commands based on real-time saturation determination. This feedback mechanism allows the system to adapt voltage commands dynamically, ensuring they are utilized up to saturation voltage effectively while maintaining stable control and preventing torque ripple
2Stability of the object's composition
If gain reduction is applied in voltage saturation determination, then control stability improves, but response speed decreases due to reduced control gain
Solution Approach 1:
The control apparatus dynamically adjusts control gain based on voltage saturation status. When saturation is detected, gain reduction is applied to improve stability; when saturation is not present, normal gain is maintained to ensure fast response. This dynamic adjustment resolves the contradiction by adapting control parameters to real-time operating conditions
3Reliability
If voltage commands are limited by saturation voltage, then overvoltage protection is achieved, but output torque is reduced due to inability to utilize full voltage range
Solution Approach 1:
The control apparatus changes voltage command parameters based on saturation determination. When voltage saturation is determined, the system adjusts voltage commands to operate within saturation limits while optimizing other parameters to maintain output torque. This parameter adaptation allows the system to achieve overvoltage protection without significant torque loss
Data Source
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AI summary
This invention is concerning obtaining a control apparatus and a control method for an AC rotary machine, with which a voltage command can be used up to a saturation voltage in each group of windings even when dimension differences exist between the groups of windings. A voltage saturation determination unit determines whether or not voltage saturation has occurred in a first winding group or a second winding group on the basis of at least one of a voltage and a current relating to the first winding group and the second winding group, and when determination is made that voltage saturation has occurred in either the first winding group or the second winding group, generates a voltage saturation determination signal for reducing a gain of at least one axial direction component on a rotational two-axis coordinate system.