Sensorless PMSM Position Estimation via Vibration Induced Saliency
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Solution Overview
Problem
Existing control methods for permanent magnet synchronous machines (PMSMs) face challenges in estimating rotor position without a sensor, particularly at low speeds, especially for low saliency machines like surface-mounted PMSMs, where traditional methods fail due to lack of significant saliency and interference from measurement noises.
Innovation Solution
The method involves measuring current Iabc across the motor, extracting a filtered current Iabc_inj at a predetermined frequency, and estimating the motor position using vibration-induced saliency, creating pseudo saliency by injecting voltage or current signals to facilitate position estimation without a position sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional sensorless control methods are used for low saliency PMSMs, then the system structure is simplified, but position estimation fails at low speeds due to lack of significant saliency and measurement noise interference
Solution Approach 1:
The patent applies mechanical vibration by injecting high-frequency voltage or current signals into the motor windings, which induces vibratory currents in the rotor. These vibrations create artificial saliency effects that enable position estimation at low speeds without requiring physical position sensors, thus resolving the contradiction between simplified system structure and position estimation accuracy
Solution Approach 2:
The patent changes the operating parameters by injecting high-frequency signals at specific frequencies and amplitudes to create vibration-induced saliency. By modulating the injection signal parameters and processing the resulting current responses, the system achieves accurate position estimation without physical sensors, particularly effective at low speeds where traditional methods fail
2Measurement precision
If a rotor position sensor is installed to achieve accurate position information, then position estimation accuracy is improved, but hardware cost and system complexity increase
Solution Approach 1:
The patent implements self-service by using the motor's own electrical characteristics and vibration responses to generate position information. The control system processes the motor's current responses to injected signals to extract position data, eliminating the need for external position sensors and reducing hardware complexity while maintaining accurate position estimation
Solution Approach 2:
The patent replaces mechanical position sensing systems with an electrical field-based vibration analysis method. By substituting physical sensors with electrical signal injection and response analysis, the system achieves sensorless position estimation, reducing hardware complexity while maintaining measurement precision
3Speed
If high frequency signal injection is applied to create vibration induced saliency, then position estimation at low speeds is enabled, but measurement noise interference increases
Solution Approach 1:
The patent extracts the useful vibration-induced current signals from the noisy background by using band-pass filtering techniques centered at the injection frequency. This extraction process separates the position-information-carrying signals from measurement noise, enabling accurate position estimation at low speeds despite the presence of noise
Solution Approach 2:
The patent employs feedback mechanisms where the estimated position information is continuously refined by comparing expected and actual current responses. This feedback loop helps distinguish genuine vibration-induced saliency signals from random measurement noise, improving position estimation accuracy at low speeds
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 enables reliable sensorless control of PMSMs at low speeds by generating anisotropy artificially, reducing hardware costs and improving system reliability by eliminating the need for a position sensor, while effectively estimating rotor position through computed impedance differences.
Implementation Method 1
creating pseudo saliency by causing a physical vibration in the mechanical system by injecting voltage or current signals
Data Source
AI summary
Technical solutions are described herein for position estimation of permanent magnet synchronous machines through vibration induced saliency. An example permanent magnet synchronous machine (PMSM) includes a motor control system to provide input command to the motor to cause a position of the motor to change. The PMSM further includes a motor position estimation module configured to estimate the position of the motor. The estimation includes measuring a current Iabc across the motor. The estimation further includes extracting a filtered current Iabc_inj at a predetermined frequency from the current Iabc. The estimation further includes estimating the position of the motor based on the filtered current Iabc_inj.