Analysis of starting and synchronization process for line start IPM motors
This paper presents an improved analytical method for determining the synchronizing capability of a line start interior permanent magnet (IPM) synchronous motor. Approximate solution techniques based on average torque analysis for determining the critical slip and maximum inertia are also presented. A dynamic d-q axis model of the motor is developed to investigate the run-up response as well as synchronization capability of line start IPM synchronous motors. The start-up and synchronization performances of a 1hp 208V 4-pole line start IPM motor for various loads have been obtained using MATLAB. Experimental investigations have been also carried out for the same 1 hp IPM motor and test results are presented to support simulation results.
Real time implementation of high performance closed loop embedded control system for interior permanent magnet motors
Aiming at achieving a low cost and precise closed loop speed control of interior permanent magnet synchronous motor (IPMSM), this paper introduces an implementation of cost effective real time embedded control system. Scalar (constant V/f) closed loop speed control strategy was implemented using a conventional PI regulator in conjunction with space vector pulse width modulation (SVPWM) technique. The motor speed has been obtained using incremental shaft encoder with reasonable resolution and price. Due to the necessity of accurate position and current measurements, fast PI controller actions, and digital implementation of SVPWM technique, a suitable digital signal controller (DSC) has been used as the computing and control center. Optimized embedded software was developed using C programming language combined with assembly instructions. Several experimental results show that the proposed drive system has a worthy dynamic response and precise tracking of the speed trajectory in a wide speed range, including zero speed without losing synchronization.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.