Sensorless Rotor Position Acquisition in PMSM via Induced Potential
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Solution Overview
Problem
In permanent magnet synchronous drive systems, determining the initial rotor position without sensors is challenging, as existing methods either increase system cost or are prone to errors due to environmental factors, and there is a need for accurate real-time rotor position acquisition.
Innovation Solution
A method and device that control the bridge arm switch of the inverter periodically to generate a short-circuit current in the stator winding, using orthogonal transformation to detect the phase angle of the induced potential vector and calculate the rotor position angle based on the phase angle of the induced potential vector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor is installed at the rotor bearing to detect rotor position information, then the rotor position can be detected, but the motor volume and cost increase, and the sensor becomes sensitive to environmental factors such as vibration and humidity
Solution Approach 1:
The patent extracts the position detection function from the rotor-side sensor and relocates it to the stator-side voltage sampling system. By sampling the induced potential at the stator terminals, the system obtains rotor position information without requiring a physical sensor on the rotor, thereby simplifying the motor structure and eliminating sensor-related environmental sensitivity issues.
Solution Approach 2:
The patent uses the induced potential voltage as an intermediary carrier to transmit rotor position information. Instead of directly measuring rotor position with a sensor, the system measures the induced potential at the stator, which contains encoded position information, and decodes it through signal processing algorithms.
2Ease of operation
If direct initiation is performed without knowing the rotor position, then the system can start operation, but strong current and mechanical shock occur, causing overcurrent faults in the converter
Solution Approach 1:
The patent performs preliminary rotor position detection by sampling the induced potential voltage before the converter starts operation. This preliminary action provides the necessary position information in advance, allowing the control system to initialize the motor drive with accurate position data and avoid the strong currents and mechanical shocks that would otherwise occur during direct startup.
3Measurement precision
If a voltage sensor is installed at the stator to sample induced potential in real-time, then rotor position information can be obtained without a rotor sensor, but the system cost still increases
Solution Approach 1:
The patent makes the voltage sampling system serve multiple functions: it is used for both normal voltage monitoring and rotor position detection. By utilizing the existing voltage sampling infrastructure for dual purposes, the system obtains accurate rotor position information without adding dedicated position sensors or additional hardware components.
Solution Approach 2:
The patent enables the motor's own induced potential to serve as the detection signal source for position information. Instead of requiring external sensing hardware, the system uses the motor's inherent electrical characteristics (induced potential during startup) to provide the necessary position data, making the system self-sufficient for position detection.
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 real-time acquisition of the rotor position without sensors, reducing system costs and environmental sensitivity, while minimizing errors associated with inductance and flux linkage parameter inaccuracies.
Implementation Method 1
The permanent magnet synchronous motor has a certain initial speed, which means that an induced potential may be induced on a stator
Data Source
AI summary
A method and device for acquiring a rotor position based on a permanent magnet synchronous drive system. The permanent magnet synchronous drive system includes an inverter and a permanent magnet synchronous motor, wherein the initial speed of the permanent magnet synchronous motor is not zero. The method includes: controlling a bridge arm switch of an inverter periodically; collecting a three-phase current of the permanent magnet synchronous motor at a fixed time within each control period; and after the three-phase current is reversed, sending same to a phase-locked loop system to conduct processing, so as to obtain a phase angle of an induction potential vector, and according to the phase angle of the induction potential vector, acquiring a rotor position angle of the permanent magnet synchronous motor.