The most attractive advantage of the dualbuck topologies is the high reliability. Firstly, without adding the extra dead time, the dualbuck topologies can solve the shoot through problem. Secondly, compared to the traditional H-bridge inverter, the current will not flow through the body diodes of the switches in the dualbuck topologies which mean no reverse recovery problem exists in the MOSFET phase legs. Considering the above two aspects, the dualbuck topologies can achieve high reliability without the shoot through and reverse recovery issues. However, the main drawback of the dualbuck topologies is the low magnetic utilization. In each power delivering and freewheeling modes, the current only flow through half of the inductance, which means the other half of the inductance, is wasted in each working condition. The low utilization of the inductance makes the increasing of the weight and volume for the whole system. To solve this problem, a concept of singleinductordualbuck full bridge inverter  is proposed. The circuit diagram of the inverter is shown in fig.1.
SingleInductor Multiple Output Buck-Boost Converter is modified from SingleInductorDual Output Buck-Boost Converter. Multiple outputs can be obtained by using SIMO converters. A SingleInductor Multiple Output Buck-Boost converter can simultaneously fulfil the requirement for multiple output voltages and the reduction in external components. However, cross regulation among different outputs is most critical issue in SingleInductor Multiple Output converters. It is the main technical challenge of the converter. It is very important to reduce the cross regulation problem. Since it is an intrinsic problem of continuous conduction mode control, we cannot remove it completely but can be reduced  by suitable methods. Some of the methods to reduce the cross regulation are based on time multiplexing control techniques, free-wheeling switching techniques, decoupled control techniques, digital control methods etc. .
In this paper, a double-loop control scheme is used for the buck-boost-inverter control being the most appropriate to cover the wide range of operating points. This control method is based on the averaged continuous-time model of the buck boost topology and has several advantages with special conditions such as nonlinear loads, abrupt load variations and transient short circuit situations . Using the control method the inverter maintains stable operating conditions by means of limiting the inductor current. Because of this ability to keep the system under control even in the situations mentioned earlier, the inverter achieves a very reliable operation . The control block diagram for the proposed buck-boost inverter is shown in Fig. 5. The output voltage reference is compared with the measured output voltage to generate the error signal. The PI2 is for the inner current control loop that should be designed to allow at least 50 º phase-margins and a high bandwidth. The PI1 is dealing with the outer output voltage control loop that should be designed with the same phase-margin and lower bandwidth compared with the inner loop [9, 11].
ABSTRACT: Renewable resources are gaining importance in our day today life because of ever growing demand for energy. In this scenario their is a need to integrate grid with the renewable sources also. This was made possible with the grid tie inverters which is gaining importance nowadays. But the output of these resources are variable in nature. To transfer this kind of dc energy into the grid, a two- or three-stage inverter may be required as the power interface, especially for the VSI-based system. If all the power stages work at high frequency, the efficiency of the inverter will be inevitably affected. In order to decrease the switching frequency, many interesting inverters have been proposed and the basic idea is to ensure that only one of the power stages of the system works at high frequency. In this paper a new type of dc/ac single phase transformer-less inverter topology has been investigated which is a buck and boost converter based inverter, where only one power stage work at high frequency and minimum voltage drop across the inductor is achieved their by improving both reliability and efficiency. In this thesis a novel inverter is investigated for photovoltaic applications. Which is abbreviated as Aalborg inverter. A simulation model of the inverter with photovoltaic source is developed in MATLAB SIMULINK and corresponding modes of operations and performance are verified and grid injected current THD was within the prescribed standards. KEYWORDS: Renewable sources, transformer-less inverter , buck-boost, THD
The power electronic switch of the dual-buck converter S2 is turned ON and S3 is turned OFF. DC capacitor C2 is discharged through S2, S4 , the filter inductor, the utility, S7 , and D3 to form a loop. Both output voltages of the dual-buck converter and five-level inverter are Vdc/2. Mode 2: Fig. 2(b) shows the operation circuit of mode 2. The power electronic switch of the dual-buck converter S2 is turned OFF and S3 is turned ON. DC capacitor C3 is discharged throughD2, S4 , the filter inductor, the utility, S7 , and S3 to form a loop. Both output voltages of the dual-buck converter and five-level inverter are Vdc/2. Mode 3: Fig. 2(c) shows the operation circuit of mode 3. Both power electronic switches S2 and S3 of the dual-buck converter Both power electronic switches S2 and S3 of the dual-buck converter are turned OFF. The current of the filter inductor flows through the utility, S7, D3, D2, and S4 . Both output voltages of the dualbuck converter and five-level inverter are 0. Mode 4: Fig. 3(d) shows the operation circuit of mode 4. Both power electronic switches S2 and S3 of the dual-buck converter are turned ON.DCcapacitorsC2 andC3 are discharged together through S2, S4 , the filter inductor, the utility, S7 , and S3 to form a loop. Both output voltages of the dual-buck converter and five-level inverter are Vdc. Modes 5–8 are the operation modes for the negative half cycle. The operations of the dual-buck converter under modes 5–8 are similar to that under modes 1–4, and the dual-buck converter can also generate three voltage levels Vdc/2, Vdc/2, 0, and Vdc, respectively. However, the operation of the full-bridge inverter is the opposite. The power electronic switches S4 and S7 are in the OFF state, and the power electronic switches S5 and S6 are in the ON state during the negative half-cycle. Therefore, the output voltage of the five-level inverter for modes 5–8 will be −Vdc/2, −Vdc/2, 0, and −Vdc, respectively.
state is used to boost voltage with the single-stage power conversion. To overcome the shortcomings of the classical SBI in , a class of quasi-switched boost inverters (qSBIs) are proposed in , . In comparison to the conventional SBI , the qSBI has the following advantages as increasing the boost factor and improving input profiles. Fig. 1(c) shows the single- phase single-stage qSBI . Compared to the single-phase qZSI and boost inverter, the single-phase qSBI uses one less capacitor and one less inductor, but one more switch and one more diode. The single-phase qSBI has all inherent advantages of the single-phase qZSI including continuous input current, shoot- through immunity and buck-boost output voltage with single stage power conversion. The qSBI has the following advantages over the qZSI : uses one less inductor with a higher inductance and one less capacitor with a lower capacitance; has a lower current rating on both switches and diodes; has a higher boost factor with the same equivalent parasitic effect; and has a higher efficiency
interface a low voltage DC source, a high voltage DC source and an AC load simultaneously. The DIDBI allows a low voltage DC source, e.g. low voltage bus, battery and renewable source, to supply power to the AC load directly, even though the voltage of the low voltage DC source is lower than the peak amplitude of the output AC voltage. Therefore, the conversion stages can be reduced to improve the conversion efficiency. In addition, the two DC sources provide multiple voltage levels for the inverter, which is benefit for reducing the switching losses and size/volume of filter inductor. Conventional DIDBI circuit is modified by reducing the circuit components. This modified circuit is successfully simulated using MATLAB R2014a. The simulation results say that the modified DIDBI has reduced 27.12% THD and improved 1.02% efficiency compared to the conventional DIDBI. A multilevel inverter is a power electronic device that is used for high voltage and high power application because of its characteristics of synthesizing a sinusoidal voltage on several DC levels. They produce lower harmonic distortion in the output. The Launch Pad TMS 320 is used for making the switching pulses. For prototype input voltages used are 10V and 20V and the obtained the maximum output voltage of 21.2V.
Cascade H-bridge inverter has been widely used in various applications, especially where separate DC sources naturally exist in the places, such as Photovoltaics, fuel cells, battery energy storage, and electric vehicle drives. The advantages of cascade type inverters include the capability of reaching higher output voltage level by using standard lower voltage devices, and the modular design concept which makes the maintenance less burdensome.. The proposed cascade dualbuckinverter with phase-shift control inherits all the merits of dualbuck type inverters and overcomes some of their drawbacks. Compare to traditional cascade inverters, it has much enhanced system reliability thanks to no shoot-through problems and lower switching loss with the help of using power MOSFETs. With phase-shift control, it theoretically eliminates the inherent current zero-crossing distortion of the single-unit dualbuck type inverter. In addition, phase-shift control and cascade topology can greatly reduce the ripple current or cut down the size of passive components by increasing the equivalent switching frequency. A cascade dualbuckinverter has been designed and tested to demonstrate the feasibility and advantages of the system by comparing single-unit dualbuckinverter, 2-unit and 3-unit cascade dualbuck inverters at the same 1 kW, 120 V ac output conditions. Hybrid PWM technique leads to better performance of the cascade dual-buck full-bridge inverter as compared to cascade H bridge, it provides less output current ripple and harmonics, no zero-crossing distortion, and higher efficiency
Inverters are devices used to convert dc-ac. It can be of voltage source inverters (VSI) and current source inverters (CSI) among them voltage source inverters are commonly used. In conventional voltage source inverters ac output voltage is always less than dc input voltage, it produces buck voltage at the output side. To boost up output voltage, an additional dc-dc boost converter is required in between the input and output side. In practice ac output voltage is desirable to be higher than dc input. Furthermore an unbalanced midpoint voltage problem is also present in the conventional inverters which leads large ripples at the output side, and makes the system unstable. To solve the limited voltage problem we can add a dc-dc boost converter or a step up transformer in the circuit as explained in . Adding a boost converter in the circuit will increase the cost and volume of the circuit. If a step up transformer is used in the circuit the output voltage will be fixed due to the fixed turns ratio of the transformer.
Here a dc/dc converter is used to converter dc voltage into a suitable value and then converted to ac. There are two stages in these inverters the dc - dc conversion and inverting stage. A traditional two-stage dual mode time sharing inverter is shown in Fig.1 (a). In this topology only a single power stage works at high frequency at a time. This has the advantage that the switching power losses can be reduced. The main drawback of this inverter is that during boost stage over-filtering takes place. The filter used in this is the CL-CL filter.
switch S2 .As shown in Fig.1, the two topologies share common grounds between Vin and vo, and thus they can minimize the possible ground leakage current problem effectively when they are used for PV inverter. However, as depicted in Fig1(c), their attainable maximum voltage gain is limited to 1, which means that they are not suitable for applications where input voltage is low. In order to overcome the limitations of Fig.1 while maintaining the doubly ground features, a three- switch three-state single-phase Z-source inverter (TSTS-ZSI) was introduced in. Fig.2 shows the boost-based TSTS-ZSI and buck-boost based TSTS-ZSI, respectively. The inverters can have higher voltage gain than 1, and they comprise three switches, three capacitors, and three inductors. Although higher voltage gain is obtained, the three inductors (L1, L2, and L3) in the TSTS-ZSI make the circuit a bit bulky and heavy. In addition, the switch signals of the inverter are all different and relatively complicated.
This paper has proposed a modified cascaded dualbuckinverter, absence of split capacitors leads to increased reliability of the inverter and also Integrated Dual Output Buck Boost converter. This converter having advantages of step up/step down dc- ac converter includes system reliability, reduction of size of components and there by acquiring less mass for the whole converter. The dualbuck type inverters are still VSI, but with the unique topology and operation, they do not have the shoot-through worries, which lead to greatly enhanced reliability. With phase-shifted PWM fed to different cascade units, zero crossing distortion is eliminated. The phase-shift control increases the equivalent switching frequency by N times that of single-unit inverter, which leads to lower current ripple. Those converters are capable of obtaining maximum power from solar cells by themselves. This could be well verified from the simulation results. The converter gives an efficiency of 89.95%.To proposed with Renewable energy source are more economical .The converter behavior has been simulated in PSCAD/IEMTDC, the output voltage of inverter for both presence and absence of inductance, respectively showed.
Fig. 2 shows the circuit configuration of the five-level inverter applied to a photovoltaic power generation system. As can be seen, it is configured by a solar cell array, a dc–dc converter, a five-level inverter, two switches, and a digital signal processor (DSP)-based controller. Switches SW1 and SW2 are placed between the five-level inverter and the utility, and they are used to disconnect the photovoltaic power generation system from the utility when islanding operation occurs. The load is placed between switches SW1 and SW2. The output of the solar cell array is connected to the input port of the dc–dc converter. The output port of the dc–dc converter is connected to the five-level inverter. The dc–dc converter is a boost converter, and it performs the functions of maximum power point tracking (MPPT) and boosting the output voltage of the solar cell array. This five-level inverter is configured by two dc capacitors, a dualbuck converter, a full-bridge inverter, and a filter. The dual-buck converter is configured by two buck converters. The two dc capacitors perform as energy buffers between the dc–dc converter and the five-level inverter. The output of the dual-buck converter is connected to the full-bridge inverter to convert the dc voltage to ac voltage. An inductor is placed at the output of the full bridge inverter to form as a filter inductor for filtering out the high-frequency switching harmonic generated by the dual-buck converter.
The Fig.1 shows a Dual-buck full-bridge PV inverter. It is very reliable as it will eliminate the reverse recovery problems, dead time and shoot-through. This dualbuck full bridge inverter is proposed so that the properties and advantages of power MOSFETs can be utilized. The size of the passive components, resistive nature of the conduction voltage drops, lower switching losses, instant switching speed are all the benefits of power MOSFETs. As seen from Fig.1, it has unidirectional inductor current and works for positive and negative half cycle current. But it has a drawback that four separate inductors are required. (B. F. Chen, 2012; Henry Benedict Massawe et al., 2013; Zhilei Yao et al., 2009; Ahmed Abdalrahman et al., 2012; S. K. Chowdhury and M. A. Razzak, 2013; Marco Liserre et al., 2005).
As shown in Fig.2 (a), the power stage of SIDO buck-boost PFC converter consists of a diode bridge Dbridge, a input filter consists of Lf and Cf, three switch networks consists of Q1, Q2 and Q3 and their corresponding sense resistors Rs1, Rs2 and Rs3, two freewheeling diodes D1 and D2, a time-multiplexing inductor L and two output filter capacitors C1 and C2. Q2 and Q3 are the time-multiplexing control switches of each output. When Q2 is turned on and Q3 is turned off, converter transfer power to output A, and when Q2 is turned off and Q3 is turned on, converter transfer power to output B.
Abstract- This invention relates to a dualbuck converter used to reduce an unregulated high input voltage without a ground reference to a regulated output voltage. This is accomplished by coupling the inductors of two independent buck converters. The input voltage is split across the dualbuck converter and the midpoint is balanced by coupling the inductors and switching the two switches at the same time. The inductors are wound on a single core, with the windings magnetically coupled, to form a new coupled inductor. A low cost, multiple output buck converter is provided using a singleinductor, a single pulse width modulator integrated circuit, and two MOSFETs plus one additional MOSFET and capacitor for each voltage output. A kind of novel dualbuckinverter with series connected diodes and singleinductor is introduced. The novel inverter retains the dualbuck topologies’ advantage of high reliability and can make full use of the inductance. In order to improve the magnetic utilization of the dualbuckinverter, a kind of singleinductordualbuck topology was proposed in. Compared with the traditional full bridge inverter, two extra switches are applied in the proposed topology. The novel topology has the following advantages: firstly, retains the advantages of the traditional dualbuck inverters, secondly, makes full use of the inductance, thirdly, the proposed inverter saves two switches compared to the traditional singleinductor topology, which makes a lower conducting loss and a simpler controlling strategy. In this project additional fuel cell is integrated with PV system to increase the generation capability.
In a DC-AC framework, a few issues may debilitate the unwavering quality of the entire framework, for example, the shoot through issue and the disappointment of turnaround recuperation. A few techniques are proposed to enhance the unwavering quality of the converters. The double buck inverters can take care of the above issues without including dead time however the double buck topology has a principle disadvantage of low attractive usage which expands the volume and weight of the framework. This paper right off the bat outlines the conventional double buck topologies including a sort of singleinductor double buckinverter which can make full utilization of the inductance. At that point a technique to enhance the unwavering quality of the MOSFET inverter is proposed. A sort of novel double buckinverter with arrangement associated diodes and singleinductor is presented. The novel inverter holds the double buck topologies' favorable position of high dependability and can make full utilization of the inductance. Additionally, contrasted with the customary singleinductor double buck topology, the controlling methodology of the proposed inverter is less complex. At long last, the reenactment and exploratory outcomes checked the hypothetical examination.
Abstract The electric vehicle inverter requires an induction motor drive with a high output of voltage and current to reduce the number of batteries used and in turn reduce the vehicle’s weight. In this paper compared two single Phase Buck- Boost Inverter (SPBBI), that is between the SPBBI conventional topology with SPBBI new topology uses a buffer inductor. The results of comparison are expected that the new inverter topology can strengthen the voltage greater than the conventional inverter topology. The inverter’s components of capacitor and inductor were reconfigured. The circuit was simulated for various carrier and signal frequencies with various load. The simulation results of the proposed topology compared with the simulation results of conventional topologies commonly used in a variety of frequency and load values. It is shown that the output voltage and current can be strengthened significantly, with a value of more than five times of the output voltage compared to the conventional inverter. The new inverter topology is useful to be implemented for the electric vehicle.
ABSTRACT— This paper presents a system in which a wind driven Permanent Magnet DC Generator (PMDC) feeds power to grid through a Buck-Boost converter. The output voltage of the PMDC is variable in nature due to non-uniform wind velocities. The fluctuating output is regulated and kept constant by means of a buck-boost converter. The buck-boost converter is provided with a closed loop feedback control, which is designed using a PID controller. In this converter, the output voltage is continuously sensed and duty ratio of the switch is varied to maintain a constant DC output voltage. This converter output is stored in a battery and converted to single phase ac using a diode clamped multilevel inverter. The power converters together with independent control systems can effectively improve the output voltage and frequency of the wind driven PMDC generator feeding power to grid. The proposed system is validated through 24V PMDC machine.
In this Photovoltaic based Single Phase Grid Connected and three phase grid connected Transformer less Inverter is performance is tested. A high reliability and efficiency inverter for transformer less PV grid- connected power generation systems is presented in this paper. Ultra high efficiency can be achieved over a wide output power range by reliably employing super junction MOSFETs for all switches since their body diodes are never activated and no shoot-through issue leads to greatly enhanced reliability. Low ac output current distortion is achieved because dead time is not needed at PWM switching commutation instants and grid-cycle zero-crossing instants. The higher operating frequencies with high efficiency enables reduced cooling requirements and results in system cost savings by shrinking passive components.