An Analysis Of PWM Rectifiers

It is observed that the power factor is maintained closer to unity when the input voltage is reduced from 230V to 110Vrms. Figure 11 (a) and (b) shows the power factor correction of controller for various load condition such as 20% (60W) and 75% (230W). The power factor for the system is found to be 0.84 for light load condition and 0.99 for full load condition. The THD of input current at full load with predominant third and fifth harmonic components are shown in Figure 12(a) and (b).Third harmonics is found to be 4.8% and fifth harmonic component is 4.9% which are well within IEC 61000-3-2 standard during wide range of load variations. The variation in power factor with load is shown graphically in Figure 13(a). It can be inferred from the graph that improved resettable control operates at high power factor for all load condition whereas the conventional PI control has poor power factor under light load conditions. Figure 13(b) shows the comparison between the efficiency of the converter for varying load conditions with the conventional control method and the resettable integrator control. The converter’s efficiency is maintained at 92% for light load conditions and 96% for fully loaded condition with integrator control technique. Thus the improved resettable integrator controller provides a very simple and reliable solution for power factor correction and

Fig. 12 shows the switching loss reduction using the DPWM2O, DPWMLPF2 and GDPWMO sequences in comparison to the conventional SVPWM strategy for 30°-60° power factor angle range. It can be seen that the DPWM2O and DPWMLPF2 sequences provide maximum switching loss reduction only at 30° and 60°, respectively. In other power factors, their loss reduction capability reduces. On the other hand, the GDPWMO strategy reduces switching losses around 50% over the entire range of power factor angle, similar to the analytical results shown in Fig.

Brushless permanent magnet DC motors are being manufactured and used increasingly in everything from home appliances to automobiles due to their inherent advantages. The merits of these motors could be enhanced further according to another design approach method which alters the typically used winding parts for low to medium power range motors. This paper deals with the high power brushless DC motor used for traction in a 48 V golf cart system.

Switching power converters offer an easy way to regulate both the frequency and magnitude of the voltage and current applied to a motor shown in fig(1). As a result much higher efficiency and performance can be achieved by these motor drives with less generated noises[3].

Space Vector PWM (SVPWM) refers to a special switching sequence of the upper three power transistors of a three-phase power inverter. It has been shown to generate less harmonic distortion in the output voltages and or currents applied to the phases of an AC motor and to provide more efficient use of supply voltage compared with sinusoidal modulation technique. The biggest difference from other PWM methods is that the SVPWM uses a vector as a reference. This gives the advantage of a better overview of the system.

Abstract— this paper presents a brief overview of standards for power electronics. All the standards presented in this paper are currently active and are approved by the Institute of Electrical and Electronics Engineer Standards Association (IEEE-SA) and American National Standards Institute (ANSI).

This new technology has replaced many of the old ones, bringing many advantages to the user, for example DC & AC drives, soft stators, UPS, etc. Since this new technology is rapidly gaining in the modern industries, power systems are expected to provide an ideal sinusoidal waveforms for currents and voltages,

Brushless DC motors is a kind of permanent magnate synchronous motor. Permanent magnet synchronous motors are classified on the basis of the wave shape of their induce emf, i.e, sinusoidal and trapezoidal. The sinusoidal type is known as permanent magnet synchronous motor (PMSM); the trapezoidal type goes under the name of PM Brushless dc (BLDC) machine. Table (2.1) shows the difference between (PMSM) and (BLDC) motor.

　　Since the industrial revolution started, the acceleration of technology development never stopped. However, with the development of new technologies, environment is suffering the consequences. The rate of Carbon dioxide is increasing rapidly. To mitigate this pollution, the concept of electric vehicle arose. The electric vehicles contribute in reducing the carbon dioxide emissions[1]. Thus, the use of electric vehicles is getting more popular as time goes by. As a result of that, electric vehicles must be integrated to the electric grid. They will be treated as electric loads, which means that all concepts of power system will be applied on them. Therefore, when electric vehicles are charged, they will cause voltage drop on the distribution feeders. Hence, the presence of voltage regulators might change the voltage response of the system.

AC electrical energy in grid interactive PV system. To achieve direct medium-voltage which is present at grid without using bulky medium-voltage transformer ,cascaded multilevel converters are attracting more and

In general, solar PV module voltage is low, ranging from 30-60V DC. To meet the demand of AC loads, there is a need for inversion as well as a voltage boosting, whereas voltage boosting is dependent on parameters like module voltage, the number of modules, and their connection [7-9]. Thus, it is clear that PCS must have following functionalities, such as voltage boosting (optional), MPPT Tracking and inversion. The voltage boosting stage can be provided by either step-up dc-dc converter or transformer followed by an inverter [10-13]. But placing the transformer to raise the voltage level is not a good solution as it increases the cost, size, and volume of the overall system. Moreover, it lowers the efficiency of the system. Hence transformerless topologies received lot of attention in past few years [9]. Two types of transformerless solutions are suggested in the literature for solar PV power generations, namely a) multi-stage power conversion and b) single stage power conversion [23-24]. Whether it is single stage or multiple stage power conversion the most critical part of a solar PV system is the inverter, which will be discussed in next sections. At present, inverters are the essential cause of breakdown of huge scale PV systems [12]. Moreover, in addition to the quality problems, inverters give restricted power efficiency [7]. Normally, inverter efficiency is around 94% and as the load diminishes the efficiency can

They are distinguished by their structure and their control strategy in order to constrain the shape of the wave of the absorbed currents. They can be divided into three classes: single phase diode rectifier followed by a PFC (Power Factor Correction), rectifier with current injection (composed of a three-phase diode rectifier equipped with a modulation circuit and d A distribution circuit for the injection of currents required in the network), and the Boost PWM Rectifier using a voltage inverter bridge[5][6] [7].

Power electronic converters, especially DC/AC inverters have been extending their range of use in industrial application because they provide better system efficiency, reduced energy consumption and improved quality of power. The output voltage of inverter could be fixed or variable at a fixed or variable frequency and output waveforms are therefore made up of discrete values, producing fast transition

Shen [14] proposed the forward-derived configuration to simplify power-stage configuration. But, it cannot trap the energy in the leakage inductor and is incapable of applying to high output voltage applications. Chih-Lung [15] proposed a multi-input converter (MIC), however the conversion rang is low.

In the present era of advanced technologies, power electronics devices have wide applications. These devices are important for industrial and domestic uses but they generate the power quality problems [1-2].these problems are created on account of these devices