Sensorless Rotor Position Estimation Using Induced Voltage Deviation
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Solution Overview
Problem
Existing sensorless methods for determining the rotor position in electronically commutated electrical machines are limited by their reliance on sinusoidal induced voltage curves and suffer from increased noise and reduced accuracy with non-sinusoidal curves, restricting their application to specific types of electrical machines.
Innovation Solution
A method and device that estimate the rotor position and speed by calculating deviations in induced voltage using a non-linear estimator, which corrects and filters errors through a model simulation, allowing for accurate determination even with non-sinusoidal voltage curves, and includes a linearization block to back-calculate the estimated rotor position and speed into an estimated induced voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the back EMF method is used to determine rotor position from induced voltage, then rotor position can be determined without sensors, but the method is limited to machines with sinusoidal induced voltage curves and requires blanking intervals that increase noise
Solution Approach 1:
The patent transforms the induced voltage curve from non-sinusoidal to sinusoidal by applying coordinate transformation and filtering operations. The estimator processes the measured induced voltage through mathematical transformations that extract the fundamental sinusoidal component, enabling accurate rotor position determination regardless of the original voltage waveform shape.
Solution Approach 2:
The patent introduces an estimator as an intermediary component between the measured induced voltage and the rotor position determination. This estimator acts as a mediator that processes the raw voltage signals through coordinate transformation and filtering, converting complex non-sinusoidal waveforms into accurate rotor position information without requiring the original waveform to be sinusoidal.
2Measurement precision
If blanking intervals are provided to measure induced voltage, then rotor position can be determined, but noise development increases during operation
Solution Approach 1:
The patent enables continuous measurement of induced voltage without requiring blanking intervals. By processing the voltage signals continuously through the estimator with coordinate transformation and filtering, the system maintains accurate rotor position determination while avoiding the noise-generating interruptions that characterize traditional back EMF methods.
Solution Approach 2:
The patent replaces the mechanical switching required for blanking intervals with a mathematical processing system. Instead of physically interrupting current flow to measure voltage, the estimator uses coordinate transformation and filtering algorithms to extract rotor position information from continuous voltage measurements, eliminating the noise associated with switching operations.
3Object-generated harmful factors
If a permanent voltage specification without blanking intervals is used, then noise behavior is improved, but rotor position determination becomes impossible with traditional back EMF method
Solution Approach 1:
The estimator serves as an intermediary that enables rotor position determination from continuous voltage specifications without blanking intervals. It processes the uninterrupted voltage signals through coordinate transformation and filtering, extracting accurate rotor position information while maintaining the low-noise benefits of continuous operation.
Solution Approach 2:
The patent transforms the measurement approach by changing from direct induced voltage measurement (requiring blanking) to estimating rotor position from the fundamental components of continuous voltage signals. The coordinate transformation and filtering operations extract the necessary position information from the permanent voltage specification without requiring interruptions.
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 sensorless determination of rotor position and speed in electrical machines with non-sinusoidal induced voltage curves, reducing noise and improving operational quality by correcting estimation errors and filtering distortions.
Implementation Method 1
determining an induced voltage in coils of the electrical machine from one or more machine currents and machine voltages
Data Source
Figure 1~2
AI summary
The invention relates to a method for the sensorless determination of a rotor position (φel) for operating an electronically commutated electric motor (2), comprising the following steps: determining an induced voltage (Uind) in coils of the electric motor (2) from one or more motor currents and motor voltages; and estimating the rotor position (φel) and/or speed information (ωel) from a deviation (ΔUind) of the inducted voltage (Uind) from an estimated induced voltage (Ûind).