Motor Power Converter Control for Speed and Torque Pulsation
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Solution Overview
Problem
Existing power converter technologies fail to effectively suppress both motor speed and torque pulsations, leading to inaccurate and inefficient control characteristics in compressor systems and similar applications.
Innovation Solution
A power converter with a control unit that calculates torque current commands based on speed reference and estimates, and switches between control modes to suppress either motor speed or torque pulsations, thereby achieving highly accurate and efficient control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a resonant-type filter is used to extract pulsation components for speed control, then motor speed pulsation is suppressed, but torque pulsation is not suppressed
Solution Approach 1:
The control is segmented into two independent pathways: one for speed control (using resonant-type filter) and one for torque control (using low-pass filter). Each pathway processes the torque current command separately to suppress its specific pulsation component, allowing both speed and torque stability to be achieved simultaneously without interference.
Solution Approach 2:
A switching unit acts as an intermediary that selectively applies different filter outputs to the torque current command. The switching unit receives inputs from both the resonant-type filter (for speed pulsation suppression) and the low-pass filter (for torque pulsation suppression), and routes the appropriate signal based on control requirements, enabling dual pulsation suppression functionality.
2Speed
If speed control is prioritized using resonant-type filter output, then speed pulsation is suppressed, but torque pulsation suppression is neglected
Solution Approach 1:
The control system dynamically switches between different filter outputs based on operational requirements. The switching unit can select between the resonant-type filter output (optimized for speed control) and the low-pass filter output (optimized for torque control), or combine them, allowing the system to adapt to varying speed and torque demands while maintaining energy efficiency.
3Device complexity
If a single control mode is used, then the control system is simple, but it cannot suppress both speed and torque pulsations effectively
Solution Approach 1:
The control system achieves multi-functionality by integrating both resonant-type filter and low-pass filter processing pathways within a unified control structure. The switching unit enables the same control system to perform both speed pulsation suppression and torque pulsation suppression functions, making the system versatile without requiring separate independent control systems.
Data Source
AI summary
A power converter having a control unit that controls the output frequency, output voltage, and output current of the motor, wherein the control unit calculates a first torque current command from a deviation between a speed reference point and a speed estimate of the motor, The control unit switches the control mode to either a control mode that suppresses pulsation of the motor speed or a control mode that suppresses pulsation of the motor torque, and calculates a second torque current command from the first torque current command and the switched control mode.