Extended Kalman Filter Based Speed Sensorless PMSM Control with Load Reconstruction

Abstract

Permanent magnet synchronous motor drives Permanent magnet synchronous motorThe Permanent Magnet Synchronous Motor is a rotating electric machine where the stator is a classic three phase coils like that of an induction motor and the permanent magnets are located on the rotor surface. A PMSM provides rotation at a fixed speed in synchronization with the frequency of the power source, regardless of the fluctuation of the load or line voltage. The motor runs at a fixed speed synchronous with mains frequency, at any torque up to the motor's operating limit. The PMSM consist stator windings and rotor permanent magnets sinusoidally distributed so Field Oriented Control can be used (Vas, 1990). From a control point of view, FOC is transfer and extension of DC motor control theory into PMSM. The basic concept is control by a excitation field and armature field-current (Vas, 1990). This type of machines are extensively used in servo drives for low power machine tool, e.g. robots, positioning devices etc. They are receiving increased attention by possibility to use in the region of larger power e.g. electricity generation. The following requirements for servo drives must be served:• high possible power to weight ratio, • large torque to inertia ratio -high acceleration possible, • smooth torque in wide speed -small pulsation of speed, • full torque at zero speed -stand still working, • high speed operation, • compact design and small size. New types of Permanent Magnet materials offer the ability to design electromagnetic energy converters with complicated shapes. Permanent magnets can be sticked or inserted to the small rotor. Rare-earth magnets are mostly used in modern drive. It can be obtained air-gap flux density in range of 1 T. PMSM are used in high-accuracy direct-drive applications mainly due to their advantages. Compared to conventional DC motors, they have no brushes or mechanical commutators, which eliminates the problems due to mechanical wear of the moving parts. In addition, the better heat dissipation characteristic and ability to operate at high speed render them superior to the PMSM drives. Vector control scheme of PMSMThe control scheme of PMSM is relative simple, proposed scheme is presented on Figure 2. www.intechopen.com The field-oriented controller is based on a current-controlled voltage source inverter structure (Vas, 1990;Janiszewski 2004;Terorde, 2002). The current control loops are arranged in the 2-phase synchronously rotating rotor reference frame d-q aligned with rotor flux (also rotor position g), while the rotor position and speed detection operates in the 2-phase stationary reference frame α . The dq-phase arrangement PMSM machine is similar to DC machine in operation. The excitation flux (Ψf) is frozen to the direct axis of the rotor and is associated with d axis. Equivalent of armature current in DC machine is associated with current in q axis. There is also assumed that the effect of any magnetic saturation is neglected during working and thus for modelling purposes the permanent ma...

Simplified Sensorless Current Predictive Control of Synchronous Reluctance Motor Using Online Parameter Estimation

“…To design the EKF for estimation of the position and speed of the rotor, stator currents, load torque, and SynRM parameters , the state-space model representation of the SynRM is presented in dq frame. In contrast, the inputs currents and voltages fed into EKF are in αβ frame and rotating frame transformation is applied in the measurement matrix [37]. The load torque, stator resistance, and stator inductances are also taken as state variable, which are presumed to be constant over a small interval of sampling time T s .…”

Extended Kalman Filter Based Speed Sensorless PMSM Control with Load Reconstruction

“…Typical variables that are chosen as states are voltages and currents for electrical systems, position, speed and torque for mechanical. Basing on described balanced equations (1,2,5,6), we can write down similar to (Barut, 2004;Janiszewski, 2005Janiszewski, , 2006Terorde & Belmans, 2002) as the state-space vector:…”

“…Standard approaches defined state vector of observer restricted to sensorless control for motor only, like speed and position (Bolognani et al, 2003;Dhaouadi et al, 1991). There are often situation in which we want to obtain other types of state estimates, which can be helpful to whole robot system controllers like load torque (Janiszewski, 2006;Terorde & Belmans, 2002;Zhu et al, 2000;). In the most practical tasks information about forces acted in particular arm axis should be necessary to know.…”

Study of sensorless control algorithms for a permanent magnet synchronous motor vector control drive

“…Encoders also need an available shaft end which can constitute a drawback for small-sized machines. In view of these limitations involving the mechanical sensors, various studies have been carried out to replace these mechanical sensors with the sensorless algorithm(s) while ensuring the best performances of the machine [5], [6], [7], [4], [8], [9], [10], [11], [12]. These studies have investigated different methods of the vector control without sensor.…”