Feedforward Control of Multiphase PMDC Motors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control schemes for multiphase permanent magnet direct current (PMDC) motors with multiple winding sets are not extendable due to inductive coupling between winding sets, differing from single winding motors in current and torque control behavior, requiring an accurate model for feedforward torque and current control.
Innovation Solution
A system and method for controlling multiphase PMDC motors that determine voltage commands for each winding set based on input torque command signals and back-EMF drop voltages, using a mathematical model to generate output torque, allowing for selective control of the motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If existing control schemes are extended to multiphase PMDC motors, then device complexity is reduced, but control precision deteriorates due to inductive coupling between winding sets
Solution Approach 1:
The control scheme is segmented to handle each winding set independently with individual voltage commands while accounting for inter-winding coupling effects. The mathematical model divides the multiphase system into manageable components that can be controlled separately yet coordinate together to achieve precise torque control.
2Device complexity
If feedforward control is implemented without accurate modeling, then device complexity is reduced, but reliability deteriorates due to instability and noise
Solution Approach 1:
An accurate mathematical model of the multiphase PMDC motor is developed beforehand to capture the inductive coupling effects and nonlinear characteristics. This preliminary modeling action enables the feedforward controller to predict and compensate for system behaviors, ensuring stable and noise-free operation without requiring complex real-time adjustments.
3Measurement precision
If current sensors are used for feedback control, then control precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses position or velocity sensors as intermediaries to indirectly obtain current information through the mathematical model. Instead of directly measuring current with current sensors, the system uses readily available position or velocity sensor data combined with the motor model to calculate equivalent current commands, eliminating the need for separate current measurement circuitry.
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
Enables accurate feedforward torque and current control of multiphase PMDC motors, reducing instability and noise, and providing fault-tolerant operation by using position or velocity sensors, eliminating the need for current sensors and enhancing control precision.
Implementation Method 1
Permanent magnet direct current (PMDC) motors are widely employed for motion control applications
Implementation Method 2
determine, for a first winding set of the PMDC motor, a first voltage command based on a first input torque command signal and a back-EMF drop voltage of the first winding set
Data Source
AI summary
Systems and methods, for controlling an output torque of a permanent magnet direct current (PMDC) machine includes a PMDC motor that includes a plurality of winding sets and a controller. The PMDC motor is configured to generate the output torque. The controller is configured to: determine, for a first winding set of the PMDC motor, a first voltage command based on a first input torque command signal and a back-EMF drop voltage of the first winding set; determine, for a second winding set of the PMDC motor, a second voltage command based on a second input torque command signal; and selectively control the PMDC motor according to the first voltage command and the second voltage command.