Ch. Sai Babu

Switching loss characteristics of advanced DPWM methods using space vector based double switching clamping sequences

This paper analyzes the inverter switching loss characteristics of space vector based double switching bus-clamping sequences. The two sequences considered in detail are 0121 and 7212 sequences. Utilizing these two sequences and varying the zero state at a spatial angle α = γ (where γ is between 0° and 60°) an infinite number of advanced discontinuous PWM (ADPWM) methods can be generated. It is a proven fact that, the double switching clamping sequences reduce the steady state line current distortion during high modulation indices significantly compared with the conventional SVPWM (CSVPWM) as well as the existing discontinuous PWM (DPWM) methods. But since in the double switching clamping sequences one of the three phases switches twice in a switching period, thus adding additional switching losses, it is necessary to analyze the PWM methods using these two sequences. Simulation results are presented for concluding the effectiveness of these methods in reducing the inverter switching losses.

Analysis and effect of switching frequency and voltage levels on total harmonic distortion in multilevel inverters

Multilevel converter technology has emerged as a very important alternative in the area of high-power medium-voltage energy control. Several topologies for multilevel inverters have been proposed over the years; the most popular cascaded H-bridge apart from other multilevel inverters is the capability of utilizing different dc voltages on the individual H-bridge cells which results in splitting the power conversion amongst higher-voltage lower-frequency and lower-voltage higher-frequency inverters. Considering the cascaded inverter to be one unit, it can be seen that a higher number of voltage levels are available for a given number of semiconductor devices. In this paper multilevel converters with different voltage levels are considered and simulation results are presented in terms of total harmonic distortion (THD). Finally generalized expression for highest order harmonic based on switching frequency and number of levels is derived.

Switching loss characteristics of advanced DPWM methods using space vector based clamping sequences

This paper analyzes the inverter switching loss characteristics of space vector based discontinuous PWM (bus-clamping) sequences. The discontinuous PWM (DPWM) sequences considered in this paper are 012 and 721 sequences. Utilizing these two sequences and varying the zero state at a spatial angle γ where γ is between 0° and 60°an infinite number of advanced DPWM (ADPWM) methods can be generated. The aim of the paper is to analyze the inverter switching losses of ADPWM methods. Also it will be shown that steady state line current distortion during high modulation indices is reduced significantly compared with the conventional SVPWM (CSVPWM). So, compared with the CSVPWM the proposed ADPWM methods are advantageous both in reducing line current distortion as well as inverter switching losses.

Fuzzy controlled single stage AC/DC converter with PFC to drive LEDs

In this paper Fuzzy Controller bases AC/DC converter is presented to drive LEDs with high power factor. Because of having of advantages of Integrated converters like increased system reliability and reduced number of controlled switches in this paper IBFC(Integrated Buck-Flyback Converter) is considered as a driver circuit to drive LEDs. novel ac-dc IBFC converter combines input current shaping, isolation and better output regulation into a single stage. In this paper Integrated buck-fly-back converter (IBFC) is a single stage AC/DC converter, operating in discontinuous conduction mode (DCM) to achieve high Power factor with fast output voltage regulation. In this paper charge control technique and fuzzy logic control technique has been implemented which has some advantage like mathematical modeling is easy, flexible and fuzzy logic can model nonlinear functions etc., Comparative analysis of conventional PI based voltage controller to fuzzy based voltage controller for 90-230V input, 48V Output and 200W ac-dc converter operating at 100 kHz is presented and MATLAB/SIMULINK is used for implementation and simulation results show the performance improvement of proposed controller.

Minimum Switching Loss ADPWM Algorithm Based DTC Induction Motor Drive Operating at Near Rated Speeds

In this paper a high performance advanced discontinuous PWM (ADPWM) algorithm for direct torque controlled (DTC) induction motor drive is proposed. The proposed ADPWM method uses a special category of DPWM sequences (0121 and 7212), because of which the performance of the drive improves in terms of the inverter switching losses. Also, significant reduction in line current distortion during high speed operations is achieved.

DSP based current controlled single stage single phase integrated converter with external compensating signal for Class-C & Class-D appliances

Abstract Design and implementation of a current controlled single stage single phase integrated AC/DC isolated Power Factor Correction (PFC) converter is presented in this paper. With the integrated topology reduces the number control switches. The proposed converter has the advantage of low bulk capacitor voltage and only single control switch hence reduce in complexity in control and cost. Sub-harmonic oscillations which are produced in conventional current controller. By adding an external compensating signal effect of oscillations are reduced and performance of the converter is improved. The proposed scheme is implemented in real time by TMS320F2812 digital signal processor (DSP) board. The performance of converter is verified both experimentally and by simulation at different load and line conditions. The proposed converter is designed for 90–230 V, 50 Hz AC input, 48 V DC output and operating at 100 kHz switching frequency. The Experimental results shows that the DSP-based fuzzy controlled single phase single switch integrated PFC converter achieve high power factor and satisfies IEC-61000-3-2 and other European input current harmonic limits for Class-C & Class-D applications.

FPGA controlled five level soft switching full bridge DC-DC converter for high power applications

Abstract The objective of the paper is to develop soft switching for the novel five level full bridge DC-DC converter for high power applications. The use of conventional DC-DC converter is likely to decrease the efficiency because of the hard switching, which generates losses during the switch on/off. This paper mainly deals with the development of zero voltage and zero current switching for five level full bridge DC-DC converter. The proposed topology will provide five level DC-DC output voltage, thereby the size of filter in both input and out sides will get reduced as compared to the existing topologies. By increasing the voltage levels, the stress across each switch and DC filter in the rectifier side will get reduced. Only eight switches are used for generating five levels in the proposed converter topology which reduces cost and also total switching losses, thus improves the overall efficiency of a system and it is very much suitable for high power DC-DC applications. The control signals for the proposed converter are developed from the Field Programmable Gate Array. The simulation and experimental results are presented for prototype model of 500 W.

Analysis and performance evaluation of Hysteresis based Modified Carrier LS-PWM modulated SCHB-MLI

Over the different Modulation Techniques, Pulse Width Modulation is one of the major renowned modulation strategy, because the pulses are generated based on reference signal and the reference signal is sinusoidal. So many modifications are made in this strategy since PWM era starts in the area of Power Electronics, the modifications are like with the reference or carrier. This paper also discussed about the analysis with performance parameters when the carrier is modified with the impact of Hysteresis Band structures. The Hysteresis based Modified Carrier is abridged towards the origin of actual carrier, this type of carrier is supports to reduce the switching losses in trail and bad edges of pulse train and also reduce the total harmonic distortions from the converter output signal. The lower switching losses and better harmonic profile elevates the inverter performance, in this paper Symmetrical Cascaded H-Bridge Multilevel Inverter is analyzed with the proposed Hysteresis based Modified Carrier associated to Level Shift Pulse Width Modulation.

State of the art Hybrid multilevel topologies for PV-Grid applications

This paper evaluates different types of Hybrid multilevel topologies and is compared based on the number of components and output performance. The algorithms for obtaining the dc voltage values are briefed. Comparative analysis elicits the proposed topology for the better reduction of harmonics and reduced number of components such as dc voltage sources and switches in Hybrid multilevel inverter topologies. The proposed hybrid multilevel inverter is evaluated by connecting to grid through a filter and thus Output with reduced harmonic content is obtained. The performance of the proposed topology is demonstrated by implementing the PV-Grid application for 49-levels. Numerical and graphical results are obtained for the precise parameters and in addition leakage current is also reduced in PV grid applications.

Analysis and design of Peak Current controlled IBFC for high power factor and tight voltage regulation

The control technique presented in this paper -Peak Current Mode Control is a simplified power factor correction (PFC) technique for single stage AC/DC converters, By using low cost standard PWM control ICs implementation becomes easy for this controller. In this paper Integrated buck-fly back converter (IBFC) is a single stage AC/DC converter, operating in discontinuous conduction mode (DCM) to achieve high Power factor with fast output voltage regulation. Comparative analysis of Peak current mode controller to hysteresis current controller for 90-230V input, 48V Output and 200W ac-dc converter operating at 100 kHz is presented and MATLAB/SIMULINK is used for implementation and simulation results show the performance improvement of proposed controller.