Sensorless Rotor Position Determination via Induced Voltage Vector Rotation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensorless methods for determining the rotor position in electronically commutated electrical machines are limited by noise issues and are not effective for non-sinusoidal induced voltage curves, restricting their application to machines with sinusoidal voltage profiles.
Innovation Solution
A method that determines the rotor position by calculating the space vector angle of the induced voltage vector, rotating it based on an estimated rotor position, and low-pass filtering to separate the fundamental component from harmonics, allowing for accurate estimation even with non-sinusoidal voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If blanking intervals are provided to measure induced voltage for rotor position determination, then the rotor position can be determined using the back EMF method, but noise development increases during operation
Solution Approach 1:
The patent extracts only the necessary information (rotor position) from the induced voltage signal by using a model-based approach that processes continuous voltage signals without requiring blanking intervals. The observer model separates the useful position information from noise by mathematically modeling the expected induced voltage and comparing it with actual measurements, allowing continuous operation without switching off phase connections.
Solution Approach 2:
The patent changes the approach from direct measurement during blanking intervals to continuous measurement with model-based processing. By transforming the measurement strategy from time-discrete (during blanking) to time-continuous with parameter estimation, the system eliminates the need for blanking intervals while maintaining measurement capability and reducing noise.
2Measurement precision
If the back EMF method is used for sensorless rotor position determination, then rotor position can be determined from induced voltage, but the method is only effective for machines with sinusoidal induced voltage curves
Solution Approach 1:
The patent transforms the induced voltage signal by rotating it with the estimated rotor position to align the fundamental component with the real axis. This parameter transformation (rotation in the complex plane) separates the fundamental sinusoidal component from harmonics, allowing the observer to accurately determine rotor position even when the original induced voltage contains significant harmonic distortion from non-sinusoidal waveforms.
Solution Approach 2:
The patent introduces an intermediary transformation step - rotating the induced voltage vector by the estimated rotor position - that converts the problematic non-sinusoidal signal into a form where the fundamental component can be easily extracted. This intermediary rotation operation acts as a mediator that bridges the gap between non-ideal measured signals and the ideal sinusoidal assumption required for accurate position determination.
3Measurement precision
If phase connections are switched off during blanking intervals to measure induced voltage, then zero crossing detection is possible, but the voltage specification cannot be permanent and noise behavior deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the estimated rotor position from the observer is continuously used to rotate the induced voltage signal for the next measurement cycle. This feedback loop allows the system to maintain accurate position estimation without switching off phase connections, as the model-based approach adapts continuously to the actual rotor position while processing continuous voltage signals.
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 precise sensorless determination of rotor position and rotational speed in electrical machines with non-sinusoidal induced voltage curves, reducing noise and improving the quality of field-oriented control.
Implementation Method 1
the rotor position is determined from the induced voltage in one of the phases of the electrical machine
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for determining an rotor position of a rotary, multi-phase, electrically commutated electrical machine (2), wherein the electrical machine (2) has a plurality of phase conductors (3) to which power can be supplied via phase connections, comprising the following steps: determining (S1, S2) phase voltages and phase currents on phase connections of the electrical machine (2); determining (S6) the induced voltages on the phase connections of the electrical machine (2) from the determined phase voltages and phase currents; and providing the voltage indicator of the induced voltage, determined by the induced voltages, in respect of a Cartesian coordinate system fixed to the stator; characterized in that the space vector angle of the voltage indicator of the induced voltage provided in respect of the Cartesian coordinate system fixed to the stator is rotated by means of calculation by an estimated value of the rotor position (S7); that the rotated voltage indicator is low-pass filtered (S8); and that, based on an angle position of the low-pass filtered, rotated voltage indicator (Uind TPdq *) of the induced voltage, the estimated value of the rotor position is determined for the subsequent calculation cycle.