A new sensorless speed control structure for PMSM using reference model

Abstract

Abstract. In the paper a new sensorless control structure for the PMSM drive is presented. Such a structure is especially recommended for speed in the range of single revolutions per second (excluding standstill). The method uses a back EMF observer for position estimation. However, there is no need to estimate the speed. This is a big advantage because of possible irregularity of estimated back EMF in this speed range, which makes the calculation of speed difficult or impossible. The proposed structure is similar to the model following control, but the reference model attempts to track the motor operating point. The main idea is to utilize as a reference a model of the whole drive, including speed and current controllers and motor model. Such a model produces reference voltage for the real inverter. However, an extra unit -called rotator -is needed to provide precise control of direct axis current, which is sensitive to the improper position of the voltage vector. The rotator acts as a kind of compensator for error of position estimation. range. This is confirmed by experimentally obtained waveforms shown in Fig. 1 and Fig. 2. This is the idle speed, using a constant value of reference current on q axis. These waveforms were obtained for a traditional field oriented control (FOC) method of the PMSM (using a similar structure as is shown in Fig. 4), with a cascade control structure using a closed speed control loop (which was disconnected for the test) with inner current control loops containing separate controllers on d and q axes, rotating synchronously with the rotor. The overall structure of control utilizes the sine and cosine of the estimated position and calculated speed value instead of measured values.To obtain smooth output values from the observer, the reference voltage is used instead of measured ones. This simplification gives good results

Apparatus for the Measurement of Electromagnetic Activity of Landslides

“…In the body of the landslide in the vicinity of the slip plane there is considerable mechanical stress on the matter. In the fractions adjacent to the slip plane, a network of microcracks is formed [2]. This phenomenon leads to the release of energy in the form of EM field emissions.…”

“…Landslides, like earthquakes, volcanic eruptions or hurricanes, pose a serious threat to human life and health and the safety of residential or industrial infrastructure [1]. Despite increasingly advanced research into the mechanism of landslide activity resulting in the development of better methods for their stabilization [2] and early warning of possible landslide activity, newer and more effective methods are being sought to predict and monitor their movements. It is important here to know the geological structure of the landslide with the distinction of slip zones in which the displacement of landslide layers occurs.…”

Landslide triggered by small excavation – numerical simulations

“…Main advantage of the strength reduction method is that initial assumption of the stability loss mechanism (shape of the sliding surface, cylindrical or other) is not required -shape and location of the failure surface is a result of the simulation. Back analysis is often used to estimate soil strength parameters (cohesion and friction angle), examples are given in [16][17][18]. However, back analysis problems are often ill-based, so different set of parameters could results in almost this same results.…”

“…Monitoring of the landslide also could be used to judge if a landslide is active and to identify potential stability loss mechanism. For example, terrestrial laser scanning (described in [5]) or inclinometric monitoring [17] could be used.…”

Position Estimation and Compensation Based on a Two-Step Extended Sliding-Mode Observer for a MSFESS

“…The second one is the model estimation method such as the back electromotive force integration method, model reference self-adaption, sliding mode observer, extended Kalman filter and etc. [ 14 , 15 , 16 ]. The back electromotive force integration method has a wide application due to its simplicity and reliability, but this method relies on the motor stator voltage and current information to calculate the vector phase.…”