Brushed DC Motor Speed-Torque Control for Load Torque Compensation
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Solution Overview
Problem
Existing brushed DC motor control systems fail to effectively account for high load and friction torques, particularly in applications like vehicle power steering systems, leading to undesirable vibrations and noise.
Innovation Solution
A method and system that incorporates load and friction torques into the speed-to-torque controller, using modified proportional, derivative, and position-dependent torque components, along with feedforward gains, to enhance control precision and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional speed control is used for brushed DC motors in power steering systems, then the control structure remains simple, but vibrations and noise occur due to high load and friction torques
Solution Approach 1:
The controller proactively compensates for load torque and friction torque before they cause vibrations and noise. By calculating and applying compensation signals based on motor position and speed, the system prevents harmful effects rather than reacting to them, thereby reducing vibrations and noise while maintaining a relatively simple control structure
Solution Approach 2:
The controller uses feedback from motor position and speed sensors to continuously adjust the compensation signals for load torque and friction torque. This closed-loop feedback mechanism enables the system to adapt to changing operating conditions and effectively suppress vibrations and noise without requiring overly complex control architecture
2Measurement precision
If load and friction torques are not accounted for in the controller, then the control system remains simple, but speed control precision deteriorates under varying load conditions
Solution Approach 1:
The controller pre-calculates compensation signals for load torque and friction torque based on motor position and speed, applying these corrections before they affect speed control precision. This proactive approach maintains accurate speed control under varying load conditions without requiring a fundamentally complex control structure
Solution Approach 2:
The controller dynamically adjusts compensation parameters based on motor position and speed, adapting to different operating conditions. By changing these parameters in real-time, the system maintains high speed control precision across varying loads while keeping the overall control structure manageable
3Stability of the object's composition
If modified torque components with feedforward gains are implemented, then control stability improves under position-dependent loads, but the control algorithm becomes more complex
Solution Approach 1:
The controller pre-calculates compensation signals for position-dependent load torque and friction torque using feedforward gains, applying these corrections before disturbances affect control stability. This approach enhances stability under varying positional loads while maintaining a relatively straightforward control algorithm structure
Solution Approach 2:
The controller uses position and speed-dependent parameters with feedforward gains to adapt to changing load conditions. By dynamically adjusting these parameters based on motor state, the system achieves improved control stability under position-dependent loads without requiring an overly complex control algorithm
Data Source
AI summary
Technical solutions are described for controlling a brushed direct current (DC) motor, including: determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining a torque command signal based on the speed difference signal; determining a voltage command based on the torque command signal; and applying a DC voltage to the brushed DC motor based on the voltage command. Determining the torque command signal based on the speed difference signal further includes at least one of: determining a modified proportional torque component including a feedforward gain term times the speed command signal, with the torque command signal including the modified proportional torque component; and/or determining a modified derivative torque component including a time derivative of the motor speed of the brushed DC motor, with the torque command signal including the modified derivative torque component.