Permanent Magnet Motor Control With Sensorless Flux Angle Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensorless motor control systems for permanent magnet motors face challenges in accurately estimating operating conditions and transitioning between open loop and closed loop control modes, leading to potential faults and inefficiencies in power factor correction and motor performance.
Innovation Solution
A method and system that utilize an estimator module to evaluate parameters such as total flux linkage derivatives and magnet flux linkages, switching between open loop and closed loop control modes based on convergence criteria, and employing a pulse-width modulation module to control the inverter power module, ensuring efficient motor operation and fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless motor control is used to eliminate position sensors, then device complexity and cost are reduced, but measurement precision of operating conditions deteriorates
Solution Approach 1:
The patent introduces an estimator module as an intermediary component that indirectly determines motor operating conditions (position, speed, flux) by processing electrical measurements (currents, voltages) and motor parameters through mathematical models. This mediator enables sensorless control while maintaining acceptable measurement precision for HVAC applications.
Solution Approach 2:
The patent replaces mechanical position sensors with an electronic estimation system that uses electrical measurements and computational algorithms to determine motor state. This substitution eliminates physical sensors while providing sufficient accuracy for control purposes in permanent magnet motors.
2Ease of operation
If open loop control mode is used during startup, then ease of operation is improved, but reliability of control deteriorates due to potential faults in mode transition
Solution Approach 1:
The patent implements feedback mechanisms where the estimator continuously monitors motor operating conditions and provides information to the controller. This feedback enables the system to detect when the motor has reached sufficient speed for transitioning from open loop to closed loop control, and to detect faults during transitions, thereby improving reliability while maintaining ease of operation.
Solution Approach 2:
The patent performs preliminary actions by starting the motor in open loop mode to bring it to a safe operating speed before engaging closed loop control. This preliminary phase ensures the motor is stable and the estimator has sufficient data before the more complex closed loop operation begins, reducing transition faults.
3Measurement precision
If estimator convergence is monitored to ensure accurate control, then measurement precision is improved, but device complexity increases due to additional evaluation parameters
Solution Approach 1:
The patent applies partial monitoring by evaluating specific key parameters (such as flux linkage derivatives or magnet flux linkages) rather than all possible estimator outputs. This selective evaluation provides sufficient convergence information to ensure accurate control while avoiding the complexity of monitoring every estimator variable.
Data Source
AI summary
A method of operating an electric motor is disclosed. The method includes: determining a d-axis resistance of an electric motor and a Q-axis resistance of the electric motor as a function of a bulk current; determining a d-axis inductance of the electric motor and a Q-axis inductance of the electric motor as a function of the bulk current; generating an estimated flux of the electric motor based on the d-axis resistance of the electric motor, the Q-axis resistance of the electric motor, the d-axis inductance of the electric motor, and the Q-axis inductance of the electric motor; generating an estimated angle of the electric motor based on the estimated flux of the electric motor; and, based on the estimated angle of the electric motor, controlling switching of an inverter that powers the electric motor.