Sensorless Motor Position Estimation via High-Frequency Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensorless vector control methods for motor rotational position estimation require high computational loads, affecting precision and increasing complexity, especially in low-speed operations where induced voltages are unclear, leading to imprecise direction detection.
Innovation Solution
A method that superimposes a high-frequency measuring voltage on the drive voltage to generate three-phase voltages, extracts frequency components from currents, multiplies these currents to create composite signals, and applies low-pass filtering to acquire filtered signals for precise rotational position estimation without complex reference frame transformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transformation between stationary and rotating reference frames is performed to estimate rotational position, then measurement precision of rotational position is improved, but computational load increases
Solution Approach 1:
The patent extracts only the necessary information (rotational position) directly from the three-phase currents in the stationary reference frame by multiplying current components and applying low-pass filtering. This eliminates the need to perform full coordinate transformations to rotating reference frames, thereby reducing computational load while maintaining measurement precision.
Solution Approach 2:
Instead of transforming currents from stationary to rotating reference frames to extract position information (conventional approach), the patent inverts the approach by directly processing stationary frame currents through multiplication and filtering to obtain position estimates, avoiding the transformation step entirely.
2Measurement precision
If complex observer systems are used to track rotational position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs a self-service mechanism where the multiplication of extracted current components inherently produces signals containing rotational position information. The low-pass filtering automatically extracts the position data without requiring external observer systems or complex tracking algorithms, simplifying the overall system while maintaining precision.
3Ease of operation
If high-frequency voltage injection is applied for sensorless control, then ease of operation is improved, but measurement precision deteriorates in low-speed operations
Solution Approach 1:
The patent changes the processing parameters by multiplying different pairs of extracted current components (ia*ib, ib*ic, ic*ia) and applying low-pass filtering to each product. This parameter transformation approach enhances the extraction of position information from high-frequency injected voltages, improving measurement precision even in low-speed operations where induced voltages are weak.
Data Source
AI summary
A method of estimating a rotational position of a motor having saliency, the method including the steps of a) superimposing, on a drive voltage for the motor, a measuring voltage having a predetermined frequency higher than a frequency of the drive voltage to generate three-phase voltages, and supplying the three-phase voltages to a stationary portion of the motor; b) in parallel with step a), extracting components of the predetermined frequency in three-phase currents flowing in the stationary portion as first, second, and third extracted currents; c) multiplying the first and second extracted currents together to acquire a first composite signal, multiplying the second and third extracted currents together to acquire a second composite signal, and multiplying the first and third extracted currents together to acquire a third composite signal; d) subjecting the first, second, and third composite signals to low-pass filtering to acquire first, second, and third filtered signals, respectively, the low-pass filtering passing low-frequency components including the frequency of the drive voltage; and e) acquiring a rotational position of the rotating portion based on the first, second, and third filtered signals.