Rotary Machine Control Reducing Torque Ripple via Phase Current Amplitude Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control systems for rotary machines, such as three-phase motors, fail to correct variations in phase currents, leading to torque ripples due to differences in machine parameters like inductances and magnetic flux linkages.
Innovation Solution
A control system that includes a command-voltage setting module, a current obtaining module, and an amplitude correcting module to adjust AC command voltages based on the magnitudes of AC currents, reducing variations in phase currents and subsequently torque ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control based on peak current value is used, then the control system can maintain a predetermined current amplitude, but variations in phase current amplitudes due to machine parameter differences cannot be corrected, resulting in torque ripples
Solution Approach 1:
The patent implements feedback control by measuring actual phase currents, calculating their amplitudes, and using these measurements to generate correction values that adjust the command voltages. This closed-loop feedback mechanism continuously compensates for amplitude variations caused by machine parameter differences, thereby reducing torque ripples while maintaining stable current control.
Solution Approach 2:
The patent replaces mechanical torque smoothing mechanisms with an electrical control solution. By using amplitude correction of command voltages based on measured current amplitudes, the system achieves torque ripple reduction through electrical means rather than mechanical modifications, improving responsiveness and control precision.
2Ease of manufacture
If machine parameters such as inductances and magnetic flux linkages vary across phases, then the motor can be manufactured with standard tolerances, but phase current amplitude variations occur that cannot be corrected by conventional control systems
Solution Approach 1:
The patent dynamically adjusts the command voltage amplitudes based on measured phase current amplitudes. By changing the voltage parameters in real-time according to actual current conditions, the system compensates for manufacturing variations in inductances and magnetic flux linkages, achieving consistent phase current amplitudes despite standard manufacturing tolerances.
Solution Approach 2:
The patent applies amplitude correction to the command voltages before they are applied to the motor phases. By pre-correcting the voltage amplitudes based on measured current amplitudes, the system proactively compensates for parameter variations before they cause torque ripples, rather than reacting after the problem occurs.
Data Source
AI summary
In a system for controlling a controlled variable of a rotary machine having plural-phase input terminals of the rotary machine in which plural-phase AC power is applied from an AC power applying module to the input terminals, a command-voltage setting module sets, based on a request value for the controlled variable, plural-phase AC command voltages for the plural-phase AC power as a feedforward manipulated variable. A current obtaining module obtains plural-phase AC currents flowing in the respective plural-phase input terminals of the rotary machine. An amplitude correcting module corrects the amplitude of at least one of the plural-phase AC command voltages based on the magnitudes of the plural-phase AC currents.