Electric Motor Rotor Position Detection With PLL Offset Compensation
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Solution Overview
Problem
Existing rotor position detection methods are susceptible to fluctuations and disruptions, leading to inaccurate and unreliable results, particularly due to manufacturing tolerances and asymmetries in electric motors, and require significant calculation effort.
Innovation Solution
A rotor position detection method that involves operating the electric motor in short-circuit or freewheel modes to measure electric operating variables, using a phase-locked loop and feedback mechanisms to calculate the rotor position accurately, compensating for manufacturing deviations by determining and correcting the offset angle based on these variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional rotor position detection methods are used, then the system can operate with standard manufacturing tolerances, but the detection is susceptible to fluctuations and disruptions leading to inaccurate results
Solution Approach 1:
The patent applies preliminary action by performing rotor position detection during specific operational phases (start-up, acceleration, deceleration, standstill) before normal operation. This allows the system to establish accurate reference positions and compensation values in advance, making the detection more robust against fluctuations during subsequent operation. The method proactively addresses potential inaccuracies by detecting and compensating for them during controlled phases rather than reacting to errors during critical operation.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring operational parameters (current, voltage, speed) and using this information to adjust and refine rotor position detection. The system compares detected positions with expected positions based on operational state, and applies corrections when deviations are detected. This closed-loop approach significantly improves both measurement precision and reliability by actively compensating for fluctuations and disruptions in real-time.
2Reliability
If conventional rotor position detection methods are used, then the system structure remains simple, but significant calculation effort is required and results are susceptible to disruptions
Solution Approach 1:
The patent applies segmentation by dividing the rotor position detection process into distinct operational phases (start-up detection, acceleration detection, deceleration detection, standstill detection), each with specific calculation methods and parameters. This segmentation allows the system to use optimized, simpler calculations for each phase rather than requiring complex continuous calculations, thereby improving calculation stability while reducing overall computational burden and system complexity.
Solution Approach 2:
The patent utilizes parameter changes by adapting detection parameters and calculation methods according to the operational phase. During different phases (start-up, acceleration, deceleration, standstill), the system adjusts which parameters are measured and how they are processed. This dynamic parameter adaptation improves calculation stability by using appropriate methods for each phase while avoiding unnecessary computational complexity.
3Measurement precision
If rotor position is detected during operation, then the detection can be performed regularly or irregularly, but manufacturing tolerances and asymmetries cause deviations between measured and actual positions
Solution Approach 1:
The patent applies feedback by continuously comparing measured rotor positions with actual positions derived from operational parameters (current vectors, voltage vectors). When deviations are detected due to manufacturing tolerances or asymmetries, the system calculates compensation values and applies them to correct future measurements. This closed-loop feedback mechanism effectively compensates for manufacturing imperfections and improves measurement precision without requiring higher manufacturing precision.
Solution Approach 2:
The patent uses preliminary action by performing detection and compensation during specific operational phases before normal operation begins. During start-up and acceleration phases, the system detects position deviations and establishes compensation values that are then applied during subsequent operation. This proactive approach allows the system to account for manufacturing tolerances and asymmetries in advance, improving measurement accuracy without requiring tighter manufacturing tolerances.
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
Enhances the robustness of rotor position detection, reduces frequency and phase overshoots, and improves precision by minimizing the impact of fluctuations and asymmetries, enabling more efficient motor operation.
Implementation Method 1
using a phase-locked loop and feedback mechanisms to calculate the rotor position accurately
Data Source
AI summary
The disclosure relates to the detection of a rotor position (γEM) of an electric motor which comprises at least one stator, at least one rotor that can be rotated relative to the stator, thereby changing the rotor position (γEM), and at least two motor phases. The rotor position (γEM) is detected on the basis of a rotor position reference value (ψb) which is calculated from electric operating variables of the at least two motor phases, wherein the electric operating variables are applied to a reference system which is fixed to the stator in order to calculate the rotor position reference value (ψb). The disclosure additionally relates to an analysis device and a drive device.