Sensorless Electric Motor Control via Flux Observer
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Solution Overview
Problem
Traditional electric motor control systems in automobiles require costly feedback devices and position sensors, increasing complexity and cost, especially in high-volume applications like electric vehicles, necessitating a method for sensorless control to reduce costs and parts.
Innovation Solution
A method and system for sensorless control of electric motors that calculates flux values based on signals with multiple cycles, using a processor to estimate rotor position and speed without feedback devices, utilizing a digitally controlled flux observer and pulse width modulation signals to time flux and back electromotive force measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback devices or position sensors are used to provide speed and position information, then control accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent extracts and eliminates the position sensor and feedback device from the motor control system. Instead of using external sensors to measure rotor position and speed, the system uses sensorless control algorithms that estimate these parameters from available electrical measurements (voltages and currents), thereby removing the problematic components while maintaining control functionality
Solution Approach 2:
The patent introduces an intermediary estimation mechanism (flux observer and coordinate transformation algorithms) that mediates between the available electrical measurements and the required rotor position/speed information. This intermediary computational approach replaces direct physical sensing, allowing the system to derive position and speed data without sensors
2Measurement precision
If feedback devices and associated interface circuits are added, then measurement accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the expensive feedback devices and interface circuits from the system. By using sensorless control that relies on computational estimation rather than physical sensors, the manufacturing cost is significantly reduced while still providing the necessary position and speed information for vector control
Solution Approach 2:
The patent creates a virtual copy of the sensor functionality through computational algorithms. Instead of using physical sensors to directly measure position and speed, the system creates estimated values through mathematical models and algorithms that replicate the information that sensors would provide, thereby avoiding the cost of actual sensing hardware
3Reliability
If position sensors and wiring harnesses are included, then control reliability is improved, but assembly complexity and time increase
Solution Approach 1:
The patent extracts and eliminates the position sensor and its associated wiring harness from the motor control system. This removal eliminates the assembly steps required to install these components and reduces the overall system complexity, while the sensorless control algorithm maintains control reliability through computational estimation of rotor position and speed
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
This approach reduces costs and complexity by eliminating the need for position sensors, providing accurate rotor position and speed estimation, enhancing system stability and performance across a wide range of operating speeds, while maintaining system stability and efficiency.
Implementation Method 1
The objective of the position sensorless control is to obtain the rotor position information utilizing electromagnetic characteristics of an AC machine
Data Source
AI summary
Methods and systems for controlling an electric motor are provided. A signal comprising at least first and second cycles is provided to the electric motor. A first flux value for the electric motor associated with the first cycle of the signal is calculated. A second flux value for the electric motor associated with the second cycle of the signal is calculated based on the first flux value.