Rotary Machine Back-EMF Demodulation for Sensorless Rotor Position
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Solution Overview
Problem
Existing rotary machines require a complete measurement chain for rotor position detection, which includes additional sensors and space, making them cumbersome and inefficient.
Innovation Solution
The rotary machine employs magnetic field sensors designed as motor coils to detect rotor position without additional sensors, using the existing machine structure, and a demodulator unit to process signals for rotor position detection, allowing for sensorless rotor position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors are used for rotor position detection, then measurement accuracy is improved, but device complexity and space requirements increase
Solution Approach 1:
The motor coils are designed to serve dual functions: generating the magnetic field necessary for motor operation and simultaneously acting as magnetic field sensors for rotor position detection. By measuring the back-EMF voltages induced in these coils, the system obtains rotor position information without requiring separate sensing components, thus eliminating additional hardware while maintaining measurement capability
Solution Approach 2:
The motor's own coils and magnetic field generation system are utilized to provide the sensing function. The back-EMF signals naturally generated during motor operation contain rotor position information, which is extracted and processed to enable sensorless control. This self-service approach eliminates the need for external sensors and simplifies the overall system architecture
2Measurement precision
If additional sensors are installed for rotor position detection, then measurement precision is improved, but the space required in the machine structure increases
Solution Approach 1:
The motor coils perform both their primary function of generating magnetic fields for motor operation and the secondary function of serving as sensors for rotor position detection. This multi-functionality eliminates the need for separate sensor components and their associated mounting spaces, thereby reducing the overall space requirements while maintaining detection precision
Solution Approach 2:
The sensing function is merged with the existing motor coil structure. Instead of adding separate sensors that would require additional space, the system combines the sensing capability into the coils already present in the motor, utilizing the same physical components for both actuation and sensing purposes
3Reliability
If a complete measurement chain with additional sensors is used, then rotor position detection reliability is improved, but ease of manufacture deteriorates
Solution Approach 1:
The motor coils are designed to serve dual functions: generating the magnetic field necessary for motor operation and simultaneously acting as magnetic field sensors for rotor position detection. By measuring the back-EMF voltages induced in these coils, the system obtains rotor position information without requiring separate sensing components, thus eliminating additional hardware while maintaining measurement capability
Solution Approach 2:
The motor's own coils and magnetic field generation system are utilized to provide the sensing function. The back-EMF signals naturally generated during motor operation contain rotor position information, which is extracted and processed to enable sensorless control. This self-service approach eliminates the need for external sensors and simplifies the overall system architecture
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 approach eliminates the need for additional sensors, simplifies the measurement process, and reduces space requirements while maintaining accurate rotor position detection, thereby enhancing the efficiency and compactness of the system.
Implementation Method 1
at least one measuring device (1), which is designed to detect magnetic field changes with the aid of the aforementioned magnetic field sensors (12)
Implementation Method 2
a rotor (11), which is designed to generate one or more electrical signals (101, 102, 103, 104, 105, 106, 107, 110) in each case with one or more constant magnetic source voltages and with one or more of the magnetic field sensors (12)
Data Source
AI summary
The invention relates to a rotary machine comprising a stator and a rotatably mounted rotor, with one or more magnetic field sensors arranged stationary relative to the stator at a radial distance from a stationary axis, at least one measuring device which configured to detect magnetic field changes with the aid of the aforementioned magnetic field sensors, a rotor which is configured to generate one or more electrical signals in each case, said signals having signal components which correspond to the rotor rotation frequency and to the distance between magnetic field sensor and rotor in each case, wherein a demodulator unit carries out a demodulation of signals generated by or derived from the magnetic field sensors, such that a signal is generated which corresponds to the distance between the rotor and the magnetic field sensor.