Rotor Position Detection Using Test Current Vectors
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Solution Overview
Problem
Existing methods for determining the rotor position of synchronous machines are complex and may not be reliable in environments with vibrations or noise, and they often require additional components like position encoders.
Innovation Solution
A method involving the application of test current vectors with the same magnitude but different angles to a synchronous machine, determining the physical response variable proportional to the q component, and calculating the first harmonic to find the rotor position at the zero crossing with a positive derivative, which is independent of saturation properties and can be performed with minimal movement and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex measurement methods based on inductance measurements or electromotive counterforce are used, then rotor position can be determined without position encoder, but the measurement precision and reliability deteriorate in environments with vibrations or noise
Solution Approach 1:
The patent replaces complex electrical measurement systems (inductance measurements, electromotive counterforce measurements) with a simplified method based on applying test current vectors and measuring the resulting rotor acceleration. This substitution uses direct mechanical response measurement instead of indirect electrical parameter analysis, thereby improving both reliability and precision in振动 environments.
Solution Approach 2:
The patent changes the measurement parameter from indirect electrical parameters (inductance, electromotive force) to direct mechanical parameters (acceleration, position change). By measuring the rotor's mechanical response to known test current vectors, the system achieves more reliable and precise position determination that is less susceptible to vibrations and noise.
2Measurement precision
If additional position encoder components are used, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent enables the synchronous machine to determine its own rotor position using its existing components (stator windings, rotor, converter unit) without requiring external position encoders. The machine uses itself as the measurement object by applying test current vectors to its own stator windings and measuring the resulting rotor response, thereby eliminating additional components while maintaining high measurement precision.
Solution Approach 2:
The patent makes the converter unit serve multiple functions: it not only controls the main operation of the synchronous machine but also applies test current vectors for rotor position determination. This multi-functionality eliminates the need for separate position sensing hardware, reducing device complexity while maintaining measurement precision.
3Reliability
If large current vectors are applied to achieve defined rotor deflection, then measurement reliability improves, but energy consumption and mechanical stress increase
Solution Approach 1:
The patent applies only the minimum necessary current vector magnitude required to produce a measurable rotor response. Instead of using large current vectors that would guarantee definitive rotor deflection, the method uses optimized current vectors that are sufficient to generate detectable acceleration and position changes, thereby reducing energy consumption while maintaining measurement reliability.
Solution Approach 2:
The patent uses periodic application of test current vectors at specific angles to the rotor d,q coordinate system. By applying currents in a structured periodic sequence and measuring the resulting periodic rotor response, the system achieves reliable position determination through signal averaging and harmonic analysis, reducing the need for excessively large individual current pulses.
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
This method provides a precise, reliable, and universally applicable solution for determining the rotor position, independent of saturation properties and environmental disturbances, with minimal noise and movement, and can be used with or without a brake, and is suitable for various synchronous machine types.
Implementation Method 1
Applying a number of test current vectors to the synchronous machine, which all have the same current magnitude and which each have a different angle in relation to a rotor-related d,q coordinate system, determining values of a physical response variable of the rotor that is proportional to the q component of the test current vectors
Data Source
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AI summary
The method involves subjecting (101) the synchronous machine with test current vectors having the same current value and different angles in relation to rotor. The acceleration of rotor proportional to a q-component of the test current vectors, is determined (102). The first harmonic of the determined values is evaluated (103) as a function of the angle of vector. The position of the rotor with respect to the stator of synchronous machine is determined (104) such that zero crossover of the first harmonic with a positive first derivative corresponds to position of rotor. Independent claims are included for the following: (1) processing unit for determining position of rotor with respect to stator of synchronous machine; (2) device for measuring the absolute position of the rotor; and (3) control unit for a synchronous machine.