Sensorless PM Motor On-the-Fly Start via Clarke Transform
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Solution Overview
Problem
Existing sensorless motor control techniques for permanent magnet motors face challenges such as increased complexity, cost, and reliability issues due to the need for sensors, which are not suitable for applications with limited electrical entries or immersion in liquids, and struggle with on-the-fly start-ups and rotor position detection without active power converter activation.
Innovation Solution
A sensorless control method using a signal processing unit and rotor position detection unit that applies a beta projection Clarke transform to remove voltage offsets and distortions from motor terminal voltages, allowing for accurate rotor position and speed calculation without additional hardware, enabling on-the-fly start-ups and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors (Hall sensors, encoders, resolvers) are used to detect rotor position, then measurement precision of rotor position is improved, but device complexity increases and reliability decreases
Solution Approach 1:
The motor system uses its own back-EMF voltages as the sensing signal source, eliminating the need for external sensors. The control unit processes the naturally generated voltages from motor phases to extract rotor position information, making the system self-sufficient and sensorless.
Solution Approach 2:
The patent replaces mechanical/electrical sensor systems with an electronic signal processing system that analyzes back-EMF voltages. This substitution eliminates physical sensors, connectors, and wiring while achieving the same rotor position detection function through computational methods.
2Measurement precision
If sensors are used to detect rotor position, then measurement precision is improved, but reliability decreases due to contamination and connection issues
Solution Approach 1:
The system uses its own internally generated back-EMF signals for position detection, eliminating external sensors that are vulnerable to contamination. The sensing function is performed through the motor's natural electromagnetic operation and electronic signal processing.
Solution Approach 2:
The patent extracts the useful sensing information ( rotor position) from the back-EMF voltages that are already present in the motor system during operation. By extracting position information from existing operational signals rather than adding separate sensing hardware, the system improves reliability.
3Measurement precision
If high frequency signal injection methods are used for sensorless control, then rotor position detection is achieved, but electromagnetic coupling issues arise in automotive applications
Solution Approach 1:
The patent changes the operating parameters by using the motor's natural back-EMF frequency range instead of injecting high frequency signals. The control unit processes the voltages at their naturally occurring frequencies, avoiding the electromagnetic interference problems associated with high frequency injection methods.
Solution Approach 2:
The patent converts the naturally occurring back-EMF voltages, which are essential for motor operation, into the sensing signal source. By utilizing these operational voltages for position detection rather than adding separate high frequency injection signals, the system avoids electromagnetic coupling issues while achieving sensorless control.
4Measurement precision
If existing sensorless techniques are used, then rotor position detection is possible, but operational complexity and computational power requirements increase
Solution Approach 1:
The patent extracts rotor position information directly from the back-EMF voltage signals through relatively simple processing operations. By taking out the position information from existing operational voltages rather than implementing complex observer algorithms, the system reduces computational requirements.
Solution Approach 2:
The patent uses a straightforward voltage sampling and processing approach that requires minimal computational resources compared to complex model-based observers. The method achieves adequate position detection with simpler, less computationally intensive operations suitable for cost-effective microcontrollers.
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 provides a reliable, cost-effective, and efficient method for determining rotor position and speed, eliminating the need for sensors and reducing complexity, while ensuring safe motor operation by accurately detecting rotor position and speed without introducing frequency-dependent response delays.
Implementation Method 1
the rotor is forced to spin even if the motor is not powered or controlled... the rotor position and speed, thus risking damage to the motor from dangerous current peaks due to misalignment of the electromotive force of the motor and the voltage generated by the power converter
Data Source
AI summary
A method and apparatus are provided for controlling a sensorless multi-phase permanent magnet (PM) motor by sensing induced motor terminal voltages from the PM motor while the rotor is spinning, generating an input voltage vector signal from the plurality of induced motor terminal voltages, projecting the input voltage vector signal to a transformed voltage vector signal which does not include DC-offset components by using a Clarke transformation without a zero component that is applied to the input voltage vector signal, and estimating an initial rotor position of the rotor from the transformed voltage vector signal, wherein said sensing, projecting, and estimating are performed while a power converter for the sensorless multi-phase PM motor is disabled.