This paper presents a single phase multilevel inverter for using as a voltage harmonic source. First, a single phase multilevel inverter system is presented and the structural parts of the inverter are described. In order to obtain multilevel output voltage waveforms, a switching strategy based on calculating switching angles is explained and an improved formula for determining switching angles is given. Simulation and experimental results of multilevel voltage waveforms are given for 15, 31 and 127 levels. The proposed topology does not only produce output voltages with low THD values. It also produces the required harmonic components on the output voltage. For this purpose, equations for switching angles are constituted and the switching functions are obtained. These angles control the output voltage as well as provide the required specific harmonics. The proposed inverter structure is simulated for various functions with the required harmonic components. The THD values of the output voltage waves are calculated. The simulated functions are also realized by the proposed inverter structure. By using a harmonic analyzer, the harmonic spectrums, which belong to the output voltage forms, are found and the THD values are measured. Simulation and experimental results are given for the specific functions. The proposed topology produces perfectly suitable results for obtaining the specific harmonic components. Therefore, it is possible to use the structure as a voltage harmonic source in various applications.

No abstract

In permanent magnet synchronous motor (PMSM) models, only the stator part is given as an electrical circuit and mechanical equations are used for modelling the mechanical part of the machine. In this study, electrical equivalents of mechanical equations are also obtained and mechanical parameters of a PMSM are expressed as an electrical circuit element. In this way, an exact electrical equivalent circuit is proposed in which both the stator and the mechanical part can be modelled as an electrical circuit for the PMSMs dynamic model. Although PMSM model includes mechanical parameters and variables, the complete model is expressed only in electrical elements and variables. The proposed PMSM circuit was simulated for different load torques in the circuit simulation program. Simulation results show that the proposed circuit operates like a PMSM. Simulation results were verified by another method in the form of solution of the differential equations that constitute the mathematical model of PMSM. Due to the proposed circuit that enables the conversion of mechanical parameters into electrical parameters, PMSM can be modelled and simulated as an electrical circuit with completely electrical elements in a circuit simulation program.

-This paper presents a hybrid motor prototype convenient to modify the magnet and reluctance torques. The rotor of the prototype consists of magnet and reluctance parts, so the generated torque includes both magnet and reluctance torques. A considerable feature of the motor is that the ratio of the magnet and reluctance parts can be modified on the rotor and the rotor hybridization ratio can be varied. Another important point is the mechanical angle between the parts changed by means of the suitable construction of the parts on the rotor shaft. Finite element (FE) analysis was carried out for the proposed motor and static torque measurements were realized. The FE results were compared with the experimental results. Average torque and maximum torque values were obtained and three dimensional 3-D graphs were formed by using the experimental data. It is possible to make different combinations by changing the parts and the angle between the parts due to the proposed motor. So the magnet and reluctance torques are modified and different combinations give different torque behavior.

-In this paper, two rotor configurations including different amount of magnet and reluctance parts are presented. The rotors are constituted by means of a flexible hybrid motor structure. Considerable features of the hybrid structure are that the combination of the magnet and reluctance parts can be suitably modified and the mechanical angle (β) between the parts can also be varied. Two hybrid rotor configurations have been considered in this study. First, finite element (FE) simulations were carried out and the torque behaviors of the motors were predicted. The average torque (T avg ) and maximum torque (T max ) curves were obtained from FE simulations in order to find suitable β. Mathematical model of the motors was formed in terms of a,b,c variables considering the amount of the magnet and reluctance parts on the rotor and simulations were performed. Rotor prototypes, motor drive and drive method were introduced. Torque profiles of the motors were obtained by static torque measurement and loaded tests were also realized. Thus, simulation results were verified by experimental study. There is a good match between predictions and measurements. The proposed motors are operated with electrical 120° mode as a brushless DC motor (BLDC) and torque versus speed characteristics show a compound DC motor characteristic. The motors can be named as brushless DC compound motors.