A low voltage sensorless Switched Reluctance Motor drive using flux linkage method

Abstract

The inherent vulnerability to mechanical failures, extra cost, and size associated with external position sensors such as optical encoders and Hall sensors has motivated many researchers to develop sensorless control techniques for SRM drives. In this paper a flux linkage method and dual layer controller is developed to estimate rotor position and speed of a low-voltage Switched Reluctance Motor (SRM) drive. The basic concept of this application is that of a sensorless speed closed loop with an inner current loop using flux linkage position estimation. The voltage drop on the power devices is more significant in case of low voltage then in case of the high voltage drive. This voltage drop needs to be considered in the algorithm. Simulations and real-time experimental results given in this paper shows that the proposed position estimation method can provide accurate and continuous position information over a wide range of speeds, even in low speed applications. To ensure a sure operation, a start up algorithm is also included. The proposed method was implemented and tested by using a digital signal processor 56F807EVM from Freescale Semiconductor Company and an 8/6 switched reluctance motor coupled with a brushless DC motor as load. The software has been developed in C language.

Sensorless control of double-sided linear switched reluctance motor based on simplified flux linkage method

“…Due to the complex electromagnetic characteristics of SRM, the winding resistance is not equal to ratio of voltage to current, and the internal resistance cannot be obtained directly. It can be seen from the formula (1) that after the phase is demagnetized, and the integral flux linkage values also should be 0Wb when the current value is reduced to 0A [11] .However, the actual flux linkage value is not 0Wbbecause the stored resistance are different from the actual resistance. The feedback regulator is used to correct the resistance of the winding until that the integral flux linkage value is 0Wb when the current is 0A.…”

Type-V Exponential Regression for Online Sensorless Position Estimation of Switched Reluctance Motor

“…Sensorless methods for starting and running of SRM motors have been studied in great length [7]- [26]. They usually involve injecting voltage pulses to the motor and, by measuring the resultant phase currents and, sometimes together with calculated flux linkage, either the positions or the best phases to turn on are then estimated [8], [11]- [13], [20]- [22]. Ahmed et al [8] describe a method that injects voltage pulses to the phases, and with a torque lookup table based on premeasured motor magnetic characteristics, controls the speed of the motor.…”

“…Using a mapping factor calculated with these flux linkage curves, the rotor position is estimated. In [22], flux linkage from the active phase is calculated and, by comparing this value with a reference, determines the commutation position. This reference value is chosen based on premeasured inductance characteristic of the motor.…”

Sensorless position estimation of switched reluctance motor at startup using quadratic polynomial regression

“…A bi-cubic polynomial function found by regression techniques is used to estimate the torque at different rotor positions and currents in [3]. Sensorless methods for starting and running of SRMs have also been investigated in many literatures [1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17]. They usually involve injecting voltage pulses to the motor, and by measuring the resultant phase currents and sometimes together with calculated flux linkage, these methods estimate the positions or just determine the best phases to turn on [4,5,8,10,[14][15][16].…”

“…Sensorless methods for starting and running of SRMs have also been investigated in many literatures [1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17]. They usually involve injecting voltage pulses to the motor, and by measuring the resultant phase currents and sometimes together with calculated flux linkage, these methods estimate the positions or just determine the best phases to turn on [4,5,8,10,[14][15][16]. Some of these methods rely on premeasured flux-current characteristic of the motor and determine the position of the phases by their inductance values [16,18], whereas the other methods compare the magnitudes of the phase currents and by inferring the inductance from this info, determine the best starting phase [8,17].…”