Rotor Position Detection via Star Point Potential
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the position of a rotor in an electrical machine require tapping into electrical variables within the machine, which is not feasible in all scenarios.
Innovation Solution
A method that determines the rotor position by measuring changes in the time derivative of currents through energization inputs caused by switching states with a DC voltage or voltage zero point, using measurable currents and voltages outside the machine, and calculating the sums of voltage components across phase strands before and after the switching state change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage vectors are applied to energization inputs and currents are measured to determine rotor position, then rotor position can be determined, but electrical variables within the machine must be accessed which is not feasible in all scenarios
Solution Approach 1:
The patent uses the star point potential as an intermediary measurement point. Instead of directly measuring currents within the machine or applying voltage vectors, the method measures the potential at the star point which indirectly reflects rotor position information. This intermediary approach allows position determination without direct access to internal electrical variables.
Solution Approach 2:
The patent replaces direct electrical measurement methods with a potential-based measurement approach. By measuring voltage potential at the star point instead of currents or fluxes, the system achieves rotor position determination through a different physical quantity that is more accessible externally.
2Ease of operation
If currents and voltages are measured outside the machine, then no intervention in the machine is required, but the measurement signal must be derived from external measurements only
Solution Approach 1:
The method uses the machine's own operational characteristics (currents and voltages during normal PWM operation) to generate the measurement signal. The star point potential naturally arises during normal operation, and by utilizing this existing signal, the system achieves position determination without additional sensors or machine modifications.
Solution Approach 2:
The patent exploits changes in electrical parameters (current derivatives and voltage components) during PWM switching transitions. By analyzing how these parameters change during controlled switching events, the method extracts rotor position information from normal operational signals without requiring separate measurement systems.
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 rotor position determination without intervening in the electrical machine, using measurable signals from outside the machine, and provides a representative measurement signal based on instantaneous inductance of phase strands, allowing for precise position calculation without altering the machine's operation.
Implementation Method 1
The change Δİ can be determined, for example, with the help of a measuring transformer, whose secondary winding supplies a voltage signal that corresponds to the voltage jump during the changeover
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for determining the position of the rotor of an electric machine (4) having multiple phases (1, 2, 3) in relation to the stator. According to the invention, the change ?I in the time derivative I of the current I flowing through at least one of the power inputs (1', 2', 3') is determined, said change ?I being caused by a change ?U in the potential U on at least one of the power inputs (1', 2', 3') of the electric machine (4), and a measurement signal that is representative of a position of the rotor is determined from multiple simultaneously or successively determined changes ?I.