Sensorless Synchronization of Synchronous Reluctance Machines
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Solution Overview
Problem
Synchronous reluctance electric machines face challenges in controlling speed transients, particularly after power cut-offs or external dynamic stresses, leading to synchronism difficulties, high acoustic noise, and increased maintenance and manufacturing costs due to the reliance on external sensors.
Innovation Solution
A sensorless control method for synchronous reluctance electric machines involves applying a control voltage with specific amplitude and duration to induce an electric current with a harmonic spectrum that changes with the frequency differential, allowing for synchronization and noise reduction without external sensors, using a combination of control voltage adjustments and phase-lock loop algorithms to restore power and maintain inertial rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external sensors are used to detect angular position or rotation speed, then synchronization accuracy is improved, but reliability deteriorates due to mechanical wear and frequent failures
Solution Approach 1:
The patent removes external sensors from the system entirely, extracting the sensing function from mechanical components and implementing it through sensorless control algorithms that estimate rotor position and speed using electrical measurements and mathematical models
Solution Approach 2:
The patent replaces mechanical sensing systems with electronic/software-based sensing, substituting physical sensors that have mechanical wear parts with algorithmic approaches that compute position and speed from electrical signals, thereby eliminating mechanical failure modes
2Measurement precision
If very high superimposed voltages and currents are applied to determine rotation speed in synchronous machines, then measurement capability is improved, but acoustic noise increases significantly
Solution Approach 1:
The patent changes the parameters of the injected voltage signals, using optimized amplitude and frequency values that are sufficient for accurate position and speed estimation without being high enough to generate excessive acoustic noise, thereby finding an optimal parameter set that balances measurement accuracy with noise reduction
3Device complexity
If sensorless control methods are used to synchronize rotating masses, then device complexity is reduced, but synchronization time increases to several seconds
Solution Approach 1:
The patent performs preliminary actions during the voltage application phase by collecting electrical measurements and pre-computing position and speed estimates using mathematical models before full synchronization is required, thereby reducing the actual synchronization time when power is restored
4Measurement precision
If external sensors are installed on the drive shaft, then rotation detection capability is improved, but manufacturing costs and maintenance costs increase
Solution Approach 1:
The patent removes external sensors from the system entirely, extracting the sensing function from mechanical components and implementing it through sensorless control algorithms that estimate rotor position and speed using electrical measurements and mathematical models
Solution Approach 2:
The patent uses inexpensive electrical measurements and software algorithms instead of expensive mechanical sensors, replacing costly hardware components with cheap computational methods that have no physical wear parts
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 efficiently controls synchronous reluctance electric machines during transients, reducing noise, lowering maintenance and manufacturing costs, and improving overall efficiency by eliminating the need for external sensors and minimizing acoustic noise, while maintaining compact machine designs and simplified inverter complexity.
Implementation Method 1
applying a control voltage with predetermined amplitude and duration to the terminals, after the transients, which voltage induces an electric current in the machine
Data Source
Figure 1a~1k
Figure 2
Figure 3
AI summary
A method of synchronizing a synchronous reluctance electric machine wherein the machine has no speed and/or residual magnetization voltage sensor and comprises power terminals and rotating masses whose mechanical rotation frequency (fΜ) is subjected to speed transients caused by power cut-off conditions. The method comprises at least one step of a) applying a control voltage (Vc) with predetermined amplitude (vc) and duration (Tc) to the terminals after the transients and one step of b) detecting the electric current induced (Ii) by the control voltage (Vc), the current induced (Ii) by the voltage (Vc) having a harmonic spectrum (S) variable according to the frequency differential between the frequency of the control voltage (fc) and the mechanical rotation frequency (fΜ) of the rotating masses, to restore power and synchronous rotation control of the machine (E).