Synchronous Reluctance Machine Restart Using Voltage Vector Estimation
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Solution Overview
Problem
Existing synchronous reluctance machine systems face challenges in restarting after a power failure without causing overcurrent and braking torque, especially due to unknown inductance values and varying machine parameters.
Innovation Solution
A control system that detects power restoration events and performs a 'flying restart' by estimating rotor speed and position using voltage vectors with fixed duty cycles, eliminating DC-offset currents, and gradually increasing stator voltage to prevent inrush currents, without requiring inductance data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional restart methods are used after power failure, then the machine can be restarted, but overcurrent and braking torque occur due to unknown inductance values and varying machine parameters
Solution Approach 1:
The system performs preliminary actions by detecting power restoration events and estimating rotor speed and position before applying full voltage. Voltage vectors with fixed duty cycles are applied first to eliminate DC-offset currents, and stator voltage is gradually increased from zero to rated value. This preliminary preparation eliminates overcurrent and braking torque during restart while maintaining reliability.
2Measurement precision
If inductance data is used for control, then precise control can be achieved, but the system becomes complex and requires accurate machine parameters which are unknown after power failure
Solution Approach 1:
The control system performs self-service by estimating rotor speed and position using only voltage vectors with fixed duty cycles and current measurements. The system eliminates the need for inductance data or accurate machine parameters by using a self-contained estimation method that works with varying parameters, thereby maintaining control precision without increasing system complexity.
3Productivity
If full voltage is applied immediately after power restoration, then restart is faster, but inrush currents occur due to unknown rotor position and speed
Solution Approach 1:
The system applies dynamics by gradually increasing stator voltage from zero to rated value based on estimated rotor speed and position. Instead of applying full voltage immediately, the voltage is ramped up dynamically, allowing the system to achieve fast restart while preventing inrush currents through controlled voltage application.
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 successful restart of synchronous reluctance machines without overcurrent and braking torque, accurately estimating rotor speed and position, and stabilizing operation without knowledge of inductance values.
Implementation Method 1
a flux being generated from the voltage pulses as a result of the magnetically anisotropic rotor core
Implementation Method 2
the rotor has a magnetically anisotropic rotor core
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Unique systems, methods, techniques and apparatuses of a synchronous reluctance machine (SynRM) control are disclosed. One exemplary embodiment is a control device structured to operate a converter coupled to a synchronous reluctance machine and receive measurements of current. The device comprises a converter controller structured to detect a power supply restoration, operate the converter so as to transmit a series voltage vectors relative to the stationary reference frame to the stator of the synchronous reluctance machine, receive current measurements following the transmission of each of the voltage vectors, estimate the rotor position using the characteristics of the voltage vector and the received current measurements corresponding to at least one voltage vector, estimate the rotor speed using the characteristics of the voltage vectors and the received current measurements corresponding to at least two voltage vectors, and operate the converter so as to apply voltage to the stator.