Dc Power Source Utilization Engineering Essay

Dc Power Source Utilization Engineering EssayMany industrial applications nourish begun to require gameer(prenominal) government agency apparatus in recent years. Some medium electromotive force motor drives and utility applications require medium potential and megawatt function level. For a medium voltage grid, it is troublesome to connect only one antecedent semiconductor switch directly. As a result, a multilevel tycoon inverter structure has been introduced as an alternative in high part and medium voltage situations. A multilevel inverter is a power electronic device make to synthesize a desired AC voltage from some(prenominal) levels of DC voltages.The concept of multilevel convinceers has been introduced since 1975. The term multilevel began with the trey-level converter. Subsequently, several multilevel converter topologies lead been developed. Plentiful multilevel converter topologies have been proposed during the last dickens decades. Contemporary research ha s engaged novel converter topologies and unique modulation schemes. Moreover, there argon three divergent major multilevel converter structures which be cascaded H-bridges converter with separate dc lineages, diode clamped (neutral-clamped), and flying capacitors (capacitor clamped) 1 Although the diode clamped multilevel inverter is commonly discussed in the literature, there has been considerable interest in the series connected or cascaded H-bridge inverter topologies 2. However, the elementary concept of a multilevel converter to achieve higher power is to use a series of power semiconductor switches with several lower voltage dc ascendants to perform the power conversion by synthesizing a stairway voltage waveform. Capacitors, batteries, and renewable heartiness voltage sources send packing be used as the multiple dc voltage sources 1.multilevel power conversion has sire increasingly popular in recent years due to advantages of high power quality waveforms, low electroma gnetic compatibility (EMC) concerns, low switching losses, and high-voltage capability. The primeval harm of multilevel power conversion technology is the large fleck of semiconductor devices required. This does not yield a significant cost increase since lower-voltage devices whitethorn be used. However, an increase in render drive electrical traffic circlery and more elaborate mechanical layout ar required 3.Project OverviewThis hear allow for involve in the design and construction of a single phase 3-level H-bridge inverter exploitation the IGBTs. An H-bridge is an electronic tour of duty which enables a voltage to be applied across a pervert in either direction. These locomotes allow DC motors to run forwards and backwards. H-bridges atomic number 18 available as integrated circuits, or can be make from separate components.In this single phase H-bridge inverter circuit, the IGBTs ar used as power devices that go away be operated as a switch by applying verify emblem to gate terminal of IGBTs. The insulated gate bipolar transistor or IGBT is a three-terminal power semiconductor device, noted for high efficiency and fast switching.The software program that will be used is MATLAB Simulink. Simulink is a commercial tool for modeling, simulating and analyzing multidomain dynamic systems. Its primary interface is a graphical pulley diagramming tool and a customizable sort out of resolution libraries.The Aims and ObjectivesThe aim of this project is to simulate a single phase 3-level H-bridge inverter (DC to AC converter) using the MATLAB Simulink and constructed it.The objectives of this project are as followsTo investigate the application of H-bridge inverter.To establish using the software, circuits implementation, and troubleshoot for the sternware.To analyze the operation of the single-phase 3-level inverter for software and hardware.CHAPTER 2LITERATURE REVIEWInverterPower electronics converters may be classified into four categori es based on the source and types of the desired siding characteristics as shown in Figure 1.1 belowOUTPUTACDCACINPUTRECTIFIERREGULATORSDCCHOPPERSINVERTERSFigure 2.1 Converter ClassificationDC-to-AC converter is known as inverter. The function of an inverter is to change a DC stimulant voltage to a symmetrical AC issue voltage of desired order and oftenness. The variable output voltage could be fixed or variable at a fixed or variable frequency. Inverter can be build in many output phases which is normally use in practice like single phase inverter and three phase inverter. The implementation of the inverter circuit mustiness to be involved in application of the power devices like SCR, MOSFET, IGBT, GTO, and Forced-Commutated Thyristor which is controlled to turning ON and turning-OFF in its operation as a converter. This inverter generally use PWM control signal for producing an AC output voltage 3.Single Phase H-Bridge Inverter OperationThe H-Bridge Inverter or sometimes cal led Full Bridge consists of four switches ( picture Figure 2.2). A progress converter is required as this system has no means of stepping up the input. Switches S1-S4, and S2-S3 make up two switch pairs. When S1and S4 are on, the output voltage is a positive pulse, and when S2 and S3 are on, the output is a negative pulse. The phase sequence, frequency, output magnitude and harmonics can be controlled through appropriate switching devices, in pairing with other equipment.Figure 2.2 Single phase H-bridge inverterSingle Phase Multilevel H-Bridges InverterThere are two types of multilevel H-bridge inverter that can be selected in this project which are separated dc source and single DC source. These two types have its pros and cons. The advantages of separated DC source areThe number of possible output voltage levels is more than twice the number of dc sources (m = 2s + 1).The series of H-bridges makes for modularized layout and packaging. This will enable the manufacturing process t o be done more quickly and cheaply.while the blemish isSeparate dc sources are required for each of the H-bridges. This will limit its application to products that already have multiple SDCSs readily available.Each H-bridge cell requires an obscure dc source. The isolated sources are typically provided from a transformer/rectifier arrangement, but may be supplied from batteries, capacitors or photovoltaic arrays to add up the output voltages. This topology was patent by Robicon Group in 1996 and is one of the companies standard drive products.2On the other hand, for the single DC source multilevel H-bridge inverter, the advantage of this type of corporation is only one DC supply is used. This will not limit its application to products. And the disadvantage of single DC source is transformer is needed to add up the output voltagesSeparated DC Source Multilevel H-Bridges InverterA single-phase structure of an m-level cascaded inverter is illustrated in Figure 2.3. Each separate dc source (SDCS) is connected to a single-phase full-bridge, or H-bridge, inverter. Each inverter level can generate three different voltage outputs, +Vdc, 0, and -Vdc by connecting the dc source to the ac output by different combinations of the four switches, S1, S2, S3, and S4. To obtain +Vdc, switches S1 and S4 are turned on, whereas -Vdc can be obtained by turning on switches S2 and S3. By turning on S1 and S2 or S3 and S4, the output voltage is 0. The ac outputs of each of the different full-bridge inverter levels are connected in series much(prenominal) that the synthesized voltage waveform is the sum of the inverter outputs. The number of output phase voltage levels m in a cascade inverter is defined by m = 2s+1, where s is the number of separate dc sources 1.Figure 2.3 Single-phase structure of a multilevel cascaded H-bridges inverterAn example phase voltage waveform for a nine-level cascaded inverter and all H-bridge cell output waveforms are shown in Figure 2.4. In this thes is, all dc voltages are assumed to be equal. According to sinusoidal-liked waveform, each H-bridge output waveform must be quarter-symmetric as illustrated by V1 waveform in Figure 2.2. Obviously, no counterbalance harmonic components are available in such a waveform. To minimize THD, all switching angles must be numerically calculated.Figure 2.4 Waveform viewing a nine-level output phase voltage and each H-bridge output voltage.One of the advantages of this structure is the number of possible output voltage levels is more than twice the number of dc sources (m = 2s + 1). The other advantage is the series of H-bridges makes for modularized layout and packaging. This will enable the manufacturing process to be done more quickly and cheaply. On the other hand, the main disadvantage of this topology is that separate dc sources are required for each of the H-bridges. This will limit its application to products that already have multiple SDCSs readily available. The sources are typical ly provided from a transformer/rectifier arrangement, but may be supplied from batteries, capacitors or photovoltaic arrays.Single DC source Multilevel H-Bridges InverterReferred to Zhong Du1, Leon M. Tolbert, John N. Chiasson, and Burak -zpineci thesis entitled A descend Multilevel Inverter Using a Single DC Source, a method is presented showing that a cascade multilevel inverter can be implemented using only a single DC power source and capacitors. Without requiring transformers, the scheme proposed allows the use of a single DC power source for examples a bombardment or a fuel cell stack while the remaining n1 DC sources being capacitors.Figure 2.5 shows the Single DC source Multilevel H-Bridges Inverter. The DC source for the freshman H-bridge (H1) is a DC power source with an output voltage of Vdc, while the DC source for the second H-bridge (H2) is a capacitor voltage to be held at Vdc/2. The output voltage of the first H-bridge is denoted by v1 and the output of the second H-bridge is denoted by v2 so that the output of this two DC source cascade multilevel inverter is v(t) = v1(t)+v2(t). By opening and closing the switches of H1 appropriately, the output voltage v1 can be made equal to Vdc, 0, or Vdc while the output voltage of H2 can be made equal to Vdc/2, 0, or Vdc/2 by opening and closing its switches appropriately.Figure 2.5 Single DC source Multilevel H-Bridges InverterIGBTs Versus MOSFETsThe power MOSFET is a device that is voltage- and not current-controlled. MOSFETs have a positive temperature coefficient, stopping thermal runaway. The on-state-resistance has no theoretical limit, hence on-state losses can be far lower. The MOSFET in addition has a body-drain diode, which is busticularly useful in dealing with limited free wheeling currents. All these advantages and the comparative elimination of the current apparition soon meant that the MOSFET became the device of choice for power switch designs. then(prenominal) in the 1980s the IGBT came along. The IGBT combines the cross between the power MOSFET and a bipolar power transistor (see Figure 2.2). The IGBT has the output switching and conduction characteristics of a bipolar transistor but is voltage-controlled like a MOSFET. In general, this means it has the advantages of high-current handling capability of a bipolar with the ease of control of a MOSFET. However, the IGBT still has the disadvantages of a comparatively large current tail and no body drain diode. Early versions of the IGBT are also prone to latch up, but nowadays, this is pretty well eliminated. Another potential problem with some IGBT types is the negative temperature co-efficient, which could lead to thermal runaway and makes the paralleling of devices hard to effectively achieve. This problem is now being addressed in the latest generations of IGBTs that are based on non-punch through (NPT) technology. This technology has the same basic IGBT structure (see Figure 2.6) but is based on bulk-diffuse d silicon, rather than the epitaxial material that both IGBTs and MOSFETs have historically used 4.Figure 2.6 NPT IGBT cross sectionThe comparisons between MOSFETs and IGBTs are as belowTable 2.1 Comparisons between IGBTs and MOSFETsIGBTsMOSFETsCharacteristicsLow duty cycleLow frequency (Narrow or small line or pack variationsHigh-voltage applications (1000V)5kW output powerOperation at high junction temperature is allowed (100C)Long duty cyclesHigh frequency applications (200kHz)Wide line or burden variationsLow-voltage applications (ApplicationsMotor control Frequency Uninterruptible power supply (UPS) Constant load, typically low frequencyWelding High average current, low frequency (Low-power lighting Low frequency (Switch mode power supplies (SMPS) Hard switching above 200kHzSwitch mode power supplies (SMPS) ZVS below 1000 watts outpouring charging 4Applications of InvertersThere are many application of inverter available today. Some of the applications are as followsDC power source utilizationAn inverter converts the DC electricity from sources such as batteries, solar panels, or fuel cells to AC electricity. The electricity can be at any required voltage in particular it can operate AC equipment designed for mains operation, or rectified to produce DC at any desired voltage.Grid tie inverters can feed energy back into the distribution network because they produce alternating current with the same wave shape and frequency as supplied by the distribution system. They can also switch off automatically in the event of a blackout.Micro-inverters convert direct current from individual solar panels into alternating current for the electric grid. electrical vehicle drivesAdjustable speed motor control inverters are currently used to power the traction motor in some electric locomotives and diesel-electric locomotive locomotives as well as some battery electric vehicles and hybrid electric highway vehicles such as the Toyota Prius. Various improvements in inve rter technology are being developed specifically for electric vehicle applications. In vehicles with regenerative braking, the inverter also takes power from the motor (now acting as a generator) and stores it in the batteries.Uninterruptible power suppliesAn uninterruptible power supply (UPS) uses batteries and an inverter to supply AC power when main power is not available. When main power is restored, a rectifier is used to supply DC power to reload the batteries.Variable-frequency drivesA variable-frequency drive controls the operating speed of an AC motor by controlling the frequency and voltage of the power supplied to the motor. An inverter provides the controlled power. In most cases, the variable-frequency drive includes a rectifier so that DC power for the inverter can be provided from main AC power. Since an inverter is the key component, variable-frequency drives are sometimes called inverter drives or just inverters.Induction heatingInverters convert low frequency main AC power to a higher frequency for use in induction heating. To do this, AC power is first rectified to provide DC power. The inverter then changes the DC power to high frequency AC power.CHAPTER 3METHODOLOGYIntroductionThis chapter exposes the proposed method of this project to built single phase multilevel H-bridge inverter. This project can be divided into two main parts of study which are software and hardware implementation. For the software part, the software used is PIC24 Compiler that used to do the programming for the microcontroller part and MATLAB to do the simulation of the inverter circuit before implemented it in hardware. In addition, genus Proteus 7 paid is also used to simulate the driver circuit before do the hardware. The summary of the project is shown in Figure 3.1.Software let on Prepared(Microcontroller)Hardware Part PreparedTroubleshootingInterfacingResultFigure 3.1 The project summaryDesign of the H-Bridge Inverter SystemThe H-Bridge inverter system can be divided into three main stages that were constructed. It is consists ofMicrocontrollerPower electronics driverPower electronics inverterEach part was treated as a separate functional block system. Figure 3.2 below shows the block diagram of how each stage of the inverter system are organized. Power electronic driver circuit and microcontroller stage is the low voltage side and power electronics inverter circuit is the high voltage side.DC Voltage InputAC OutputPower Electronics Inverter CircuitMicrocontrollerPower Electronic Driver CircuitFigure 3.2 The block diagram of the inverter systemMicrocontrollerMicrocontroller is a computer-on-a-chip optimised to control electronic devices. The microcontroller chip used for this project is PIC16F877A. In this project, microcontroller is used to develop the triggering signal for the IGBTs and interfacing to the single phase inverter circuit as a control signal for the gate driver.To implement the microcontroller part, the program for trigge ring the IGBTs was compose in assembly language using the PIC C Compiler. It is written in the text editor or notepad called as source code. It also can be written directly in the PIC C Compiler. Then the file saved is *file.c file. by and by the program is successfully compiled, the *file.hex file was generated. The hex file was tested by doing the simulation in the Proteus 7 Professional to see the output generated from the program. After got the correct output, the *file.hex file then was uploaded in the PIC16F877A using the PIC programmer. The process of implementing the microcontroller is shown in Figure 3.3. This microcontroller part is the first part that was implemented in hardware.Figure 3.3 The process of implementing the microcontrollerPower Electronics DriverA driver is an electronic component used to control another circuit or other component, such as a high-power transistor. Unlike the bipolar transistor, which is current driven, IGBTs, with their insulated gates, ar e voltage driven. It is allows user to speed up or behind down the switching speeds according to the requirements of the application.The control circuitry supplied low current driving signals that are referenced to controller-ground. A logic one signal was applied to its gate with respect to its source to turn on an IGBT switch, and this signal needs to restrain sufficient power. These requirements can not be met by the control circuit. Figure 3.5 shows a diagram of how signals need to be applied to IGBT switches for effective operation.Figure 3.4 Control signals need to be applied to the gate with respect to the sourceThe driver chose is IR2110 which is a dual driver. The IR2110 High Voltage Bridge Driver is a power integrated circuit that is designed to drive two insulated gate devices. The typical inter-group communication of the driver is shown in Figure 3.5. The two channels of the IR2110 are completely independent of one another. The HO output is controlled by the HIN input, and the LO output is controlled by the LIN input. The two inputs of the IR2110 are logically coupled to the shutdown (SD) pin through an AND gate. If HIN and LIN both go high, then the IR2110 will be shut down until one or both inputs go low. This measure helps prevent the catastrophic situation where both Q1 and Q2 turn on at the same time and short circuit the input source. 5Figure 3.5 Typical connection of IR2110 High Voltage Bridge DriverIsolation using the optocouplerAn optocoupler or sometimes refer to as optoisolator allows two circuits to flip-flop signals yet remain electrically isolated. This is usually accomplished by using light to relay the signal. The standard optocoupler circuits design uses a LED shining on a phototransistor. The signal is applied to the LED, which then shines on the transistor in the ic. The optocoupler circuit is shown in Figure 3.6 below. In this project, the optocoupler is used as the source and computer address are at very different voltage l evels, where the source is the microprocessor which is operating from 5V DC but it being used to control the IGBTs which is switching at higher voltage. In such situations the link between the two must be an isolated one, to protect the microprocessor from overvoltage damage. The optocouplers can be used with following advantages for driving high side IGBT in any topologyThey can be used to give a very high isolation voltageSignals from DC to several MHz can be handled by opto-couplers.They can be easily interfaced to Microcomputers or other controller ICs or any PWM IC.Figure 3.6 Optocoupler circuitThe circuit of low side voltage which consists of PIC, driver and optocoupler was first constructed in the Proteus 7 Professional to see the output generated to be compared with the hardware results. The circuit is as in Figure 3.7 below.Figure 3.7 Low side voltage simulationPower Electronic InverterThe power electronics inverter part is the main part of the system. This is because this circuit will perform the conversion from DC to AC. The circuit consists of four IGBT that act as a switch, DC source and also the load. Figure 3.8 shows a diagram of the H-Bridge power electronics inverter stage.Figure 3.8 H-Bridge power electronics inverter stage.But for this project, the inverter circuit used is the 3-level H-bridge inverter circuit. The circuit was first constructed in the MATLAB as in Figure 3.9 and the simulation of the circuit was done to see the result of simulation.Figure 3.9 3-level H-bridge inverter circuit constructed in MATLABThe block parameter for the IGBTs was set as in Figure 3.10. The switching frequency used for this circuit is 50Hz. So, the spot of waveform can be calculated as belowSwitching frequency, f = N / PfFundamental period, Pf = 1 / f fundamental = 1/ 50 = 0.02sFigue 3.10 The block parameter setting for the IGBTsIn addition, the phase delay or switching times of the IGBTs were also set. Table 3.1 below shows the switching time of the IGB Ts. After the simulation was success, the circuit of single 3-level H-bridge inverter was constructed.Table 3.1 The switching time of the IGBTsIGBTsSwitching TimeIGBT 1 and IGBT 310 ms ()IGBT 2 and IGBT 40 ms (0 )IGBT 5 and IGBT 77 ms (/7)IGBT 6 and IGBT 83 ms (/3)For the switch, IRGB10B60KDPBF IGBT was selected for this design. It is very important to choose the correct switches for the inverter circuit because the mathematical operation of the design is directly depends on this. This IGBT was chosen because it has ultra fast recovery diode along, it offered benchmark efficiency for motor control and excellent current sharing in parallel operation. In addition the IGBT was selected as they are able withstand the power rating of the inverter. Table 3.2 shows some of the features of the selected IGBT.Table 3.2 The features of IRGB10B60KDPBF IGBTCharacteristicsValue feed to Source Voltage (Vds)600VDrain Current (Id)12ARise Time20nsFall Time23nsShort Circuit Capability10sFigure 3.4 3 -level H-bridge inverter circuit