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What's the different between High Frequency and Low Frequency?


HF power inverter have limit for runing appliances with motors ,engines,special light and TV

LF power inverter available for sensitive load,accept generator's energy output,high power factor,and follow our warning label ,it would not have any problems.

Different for 2012 1.0 and 2013 2.0  version low frequency psw inverter.


1. made by alumim housing, fron & back panel made by 2.5cm iron, strong enough to hold this big guy.

2. TURBO POWER AUTO DETECTION:

when you use some motor, enginee, pump, some need 10 times surge power requiry, in this moment, the IC will auto offer more amp come from the battery with 2times stand by power to turn on the heavy appliance, after turn it on, the amp will come to normal voltage & amp.

3. inside big tranformer is made by taiwan factory, material come from japan, that's bring the inverter efficiency come matain to 92% at least.

4. inside mosfet come from brand new from germany & usa, not made in china, that's make sure for long year use, will be no problem & temp can stay at 60C around.

5. included AC power cord for battery charger


--20130326

our economy from the early days of the planned economy gradually transition to a market economy , coupled with our country is a country with a large population , Food is bound to promote the vigorous development of China 's food industry , packaging machinery to improve the rate of food packaging is very key. The rate of food packaging in the United States, Japan and Europe were 90% , 80% and 70% , while China is only 5% , packaging machinery in the modern is great , the food machinery industry in China can be described as "money" way immeasurable .

the founding of 60 years to

our people 's living standards and people's income has undergone earth-shaking changes now put forward higher requirements for the packaging of goods . Where there is a product where there is the packaging, can be said that the development of the packaging industry for the national economy as a whole structure plays an important role in the packaging alone Spark machinery, packaging machinery out widely , widely used in food, pharmaceutical, chemical , etc. various industries .

only from the point of view of food and other light industrial products Grid tie inverter, China 's total exports accounted for more than 1/3 are required to improve the packaging grades , which has brought many opportunities for the development of packaging machinery need a wide range of packaging machinery, food packaging and with the continuous improvement of people's living standards , people 's consumption patterns from subsistence to enjoy the type of transition , so the packaging machinery industry is a sunrise industry power inverter.

At present, China 's packaging machinery industry classification is as follows : filling machine , filling machine , sealing machine , wrapping machine , vacuum packaging machine , inflatable packaging machines , blister packaging machines , labeling machines , dry machine , bag making machine , coder ...

packaging machinery save manpower , labor , food companies should not be overlooked convenience , but also for the people brings a wide range of food packaging , to improve people's visual enjoy the taste . ..



This article is from the: http://www.12vgridtiepowerinverters.com/

a DC power supply, two working conditions, a constant pressure state, in accordance with the characteristics of the constant voltage power supply in the work, a constant current, in accordance with the characteristics of the constant-current power supply in the work. This internal power supply has two control units, one is the regulator of the control unit, in the case of load change, the effort to make the output voltage remains stable, provided that the output current must be less than the pre-set constant value. Actually in the constant-voltage state, the constant current control unit is in the pause state, it does not interfere with the output voltage and output current. When the load resistance is gradually reduced, so that the load current increases to a preset constant value, the constant current control unit starts working, its task is in load resistance continues to decrease in the case, efforts to make the output current at a predetermined The constant current value is maintained, this need that the output voltage decreases as the load resistance decreases, in an extreme case, the load resistance is reduced to zero (short circuit condition), that the output voltage drops to zero to maintain a constant output current. The function of these components are constant current, constant-current components work, constant pressure parts in the resting state, it is no longer intervene in the output voltage level. This has both constant voltage control parts, is called constant voltage constant current power supply and power with constant current control components. The
cite one example: a constant current and constant power by adjusting the voltage regulator and current regulator knob on the panel so power no-load output voltage is set at 100V, constant current value adjustments 1A, power with The change in resistance of the load and automatically change the power state it? Through the above description, we can know that power at a constant voltage when the output current is less than 1A state efforts to maintain the output voltage of 100Vpower inverter, output current varies with the size of the load changes, and the trend is greater than when the current value 1A, the power supply is a constant current working status, the efforts to maintain the output current is 1A, and the output voltage varies with the change in the size of the load. When the output voltage is 100V, the load resistance contact is good for 100 ohm output current contact is good for 1A, the turning point of the power state, power is either constant pressure state, said constant current state. On this specific case, this we can draw the following conclusions: the
① when the load resistance RL = 100 ohmsGrid tie inverter, for constant pressure constant

This article is from the: http://www.12vgridtiepowerinverters.com/

Abstract: This paper introduces an output of 115V, 400Hz power works, given the appropriate circuit schematics and parameters.

, power inverter ; Keywords: PWM modulation inverter harmonics

1 Introduction

DC 27V to AC 115V, 400Hz power inverter is widely used in troops and ships, there is a larger demand. In view of this situation, we have developed a 800VA single phase static power inverter, the DC power supply with 27V input, and can output a sine wave voltage of 115V, 400Hz. And with 3 sets of the same power supply by an appropriate coupling, under the control of the peripheral circuit can be used as a single three-phase inverter power usage.

Currently, new technologies continue to emerge, there are many ways to constitute a DC / AC inverter. However, taking into account the specific conditions of use as well as the cost and reliability of the power supply with a typical two transform the way that the first level of the use of DC / DC converter, 27V conversion of approximately ± 130V DC high voltage, the second level use of the DC / AC conversion of the DC high voltage is converted to AC output by the feedback regulation of the high voltage direct current of ± 130V to ensure the stability of the AC 115V output. In this way, the simplified circuit debugging and production processes, quality is also easy to control, easy to industrialization.

2 main circuit design

2.1 DC / DC converter regulator

the converter with a push-pull operation, has the advantages of high efficiency, reliable work. As shown in Figure 1, the converter is a low voltage DC power is converted to high voltage DC. The main transformer T1 primary access to the form of a push-pull and secondary because the higher voltage, the full-bridge rectifier, switch S1 and S2 were used four IRF3710 in parallel, effectively reducing the conduction losses. The symbiotic power MOSFET diode as exchange pathway, inhibition across the switch off overvoltage switch off. R2, C3, R3, C4 RC snubber circuit, can further reduce the spike voltage when the MOSFET is turned off. Absorption resistance selection principle,www.12vgridtiepowerinverters.com, can still make the minimum on-time, the voltage on the capacitor discharged, and absorption capacitance try to take a large absorption the resistor-power license within. After the experiment, the absorption of the circuit resistance 5Ω, 5W, absorption capacitance of 0.1μF, 250VDC.

main transformer T1 selects the TDK PQ50/50 cores, has been calculated (formula see Reference 1), the transformer primary to 2 turns, secondary 30 turns. Because the primary current is large, with a thickness of 0.5mm thin copper winding, while using primary and secondary method of alternately wound so that the leakage inductance, skin and proximity effect minimum.

, Grid tie inverter ; filter inductor L1 and L1 'around with a CD-shaped core on the inductance of 1.0mH. On the connection, L1, L1 'is in the form of series inductance, this can increase the inductance, and ensure that the output of dynamic and static characteristics than those in good ± 130V voltage. L2 and L2 'is a group of the auxiliary filter inductor.

actual circuit debugging, it should be noted that the level connected resistive load, and then the second stage DC / AC load, the push-pull converter power tube voltage waveform significantly different. In the second case, the peak voltage power tube off.

2.2 to take advantage of the DC / AC inverter output sine wave

because the power supply is a constant output frequency constant pressure 115V, 400Hz power supply from the system's reliability and practicality, the transform square wave, sine wave output voltage and resonant filtering. The main circuit is shown in Figure 2.

S3, S4 using IRFP460, driver circuit using SKHI21, simple and reliable circuit SKHI21 details see Reference 2. L3 inductance of 6.8mH, CD12.5 × 25 × 60 Core plus air gap wound into a diameter for the � 1.65mm; in order to improve the utilization efficiency of the iron core,power inverter, two windings sharing a core, made of an inductor in series. C7 ~ C10 5.0μF, MKC capacitance of 400VDC; C14 to C16 is a the MKP capacitance of 5.0μF, 250VDC; C11 ~ C13 1μF, MKC capacitance of 400VDC, L6, and C11 ~ C13 composed of the series resonant circuit, mainly for filtering third harmonic, L6 is 4.3mH. The filter circuit simulation circuit simulation software EWB5.1D most optimized parameters of the various components in a certain load conditions, the harmonic distortion can be controlled at around 4%.

3 control circuit design

control circuit is composed of two parts, a drive signal for providing a push-pull boost circuit and the current, voltage feedback control and protection, as shown in Figure 3; another part is the inverter circuit drive protection signal, as shown in Figure 4. In Figure 3, the TL494 core constitute the PWM drive and protection circuit, converting a frequency of 50kHz. 115V output voltage by isolated buck sent to P8, after AD536 taken rms fed TL494 error amplifier A1, as the system's closed-loop voltage control. Push-pull inverter circuit current through the current transformer sampling signal sent by P7 in the control panel into the TL494 error amplifier A2, as the current loop control. The TL494 output drive signal P6 White circuit output to the drive plate is amplified evacuation. Circuit of the system also has a comprehensive protection measures, including:

(1) 115V output overcurrent protection. The output signal of the current transformer via P1 into the comparator U2, the slow start blocked ends (DT) after the judgment comparison into the TL494.

(2) thermal protection. The system in the main power device are equipped with temperature relay, when the temperature is too high, the corresponding P4 both ends shorted, so that the T12 transmitter output high block PWM pulse output.

(3) DC / AC inverter main circuit overcurrent protection and DC overvoltage protection. Both by the corresponding sensor signal into the control panel, P5 and P21 processing blockade PWM pulse output.

the

Figure 4 shows the circuit, for generating a drive signal of the DC / AC inverter required. The drive signal may be the signal circuit of the present system, is supplied by an external circuit, in order to achieve the parallel output of the system, its conversion via multiplexer U12 (MAX4544) switch automatically when the applied signal, after the circuit composed by the U11,Grid tie inverter, etc. Remedy, U11B-7 to the U12-7 outputs a high level, so that the electronic switching operation, and to achieve the switching of the drive signal from the internal circuit to the external circuit. A drive signal is amplified by U3A and U10E after shaping were sent on the rising edge delay circuit, a delay circuit is composed mainly by R50, C3, D15, the function of the time of the completion of the drive signal on the rising edge plus "dead zone". Thus, to avoid two of the same arm switch occurred "straight-through" phenomenon. The other circuit is mainly used to protect and improve the reliability of the system.

4 Conclusion

the high reliability of power supply, the output waveform distortion, and peak interference SPWM modulation circuit, has been put into production use.

--20130322

April 16 this year, sent a letter to Chinese Vice Premier Hui Liangyu, mechanical industrial packaging food machinery experts Authority five experts suggested that the state focus on deep processing of agricultural technology and equipment to give support. The
Vice Premier Hui Liangyu made important instructions: "This opinion is very good. agricultural product processing industry, especially deep processing, and thus promote the industrialization of agriculture is our strong advocacy and support. processing industry technology and equipment support lag, Wang serious research and advance in conjunction with the relevant parties.
written instructions for implementing the Vice Premier Hui Liangyu, China Machinery Industry Federation, as reported to the National Ministry of Science and Technology approved the 2004 international deep processing of agricultural technology and equipment exhibition held in Beijing Agricultural Exhibition, scheduled from May 17 to 21 in 2004. Agricultural processed food industry key projects for the past two years, the former State Planning Commission, the State Economic and Trade Commission approved more than 220 "," provide "state-of-the-art, the applicable economic, reliable and deep processing of agricultural key technological transformation projects" technology equipment services. the
exhibits is a major scientific and technological achievements of the Eighth China since self-developmentpower inverter, or the introduction of digestion and absorption of foreign technology, including agro-processing machinery, food processing machinery, packaging machinery, plastic printing and packaging machinery. Through the exhibition, major scientific and technological achievements and new product deep processing of agricultural technology and equipment, it is recommended that countries give priority support to the national authorities recommend. The
exhibitions support of the relevant departments of the State Development and Reform Commission, Ministry of Agriculture, Ministry of Science and Technology, the National Food Authority, the State Council Development Research Center. Economic Operation Bureau of National Development and Reform Commission, the Ministry of Agriculture, Bureau of Township Enterprises as support units; China Agricultural Machinery Industry Association and China Packaging Technology Association of Machinery Industry Packaging Technology Branch is responsible for the contractor; Association of Cities in agricultural machinery, light industry machinery, food packaging machinery As the co-organizers of the exhibition. Relevant departments of the Ministry of Agriculture is responsible for organizing the user to visit.
This is the first time to solve the "three rural" issues, agro-processing machinery, grain and oil processing machinery, feed machinery, aquatic products processing machinery, special agricultural products (tea, bee, polyandrum , etc.) the 12 processing machinery, beverage processing machinery, dairy processing machinery, food processing machinery, food manufacturing machinery, packaging machinery, plastic machinery, packaging and decoration printing machinery and other mechanical equipment, unified for the deep processing of agricultural technology and equipment to be exhibited.
During the exhibition, will recommend significant technological achievements of the national agricultural products deep-processing technology and equipmentGrid tie inverter, new products, promote the lag problem solve agricultural product processing industry technology and equipment support, promote and equipment.

This article is from the: http://www.12vgridtiepowerinverters.com/

---20130321


officially started construction after

Asian Heart Network (Reporter Wang Jianlong) May 13, Xinjiang 800 kV HVDC Transmission Project in Xinjiang - Northwest main network networked 750 kV second channel engineering project to obtain NDRC approval . To Hami south Zhengzhou ± 800 kV HVDC Transmission Project power support, Hami region recently identified six major thermal power projects.

May 15, the reporter learned from the Hami prefectural administrative office, Hami region of the State Grid Energy the Hami Coal and Electricity Company Dananhu 2 million kilowatts power plant, power generation Guodian Xu mine Hami Co., Ltd. Dananhu 200 million kilowatts power plant, SDIC Hami Energy Development Co., Ltd. 1.32 million kilowatts of power plants, the Hami heavy industry park, Huaneng Xinjiang Energy Development Co., Ltd., 1.32 million kilowatts power plantpower inverter, the Shenhua Lu new Hami Power Limited Dananhu 1.32 million kilowatts of power plants and Henan Coal Chemical Industry Group Hami Investment Limited Dananhu 2 million kilowatts of power plant projects, as Zhengzhou, Hami south to ± 800 kV UHV DC transmission engineering support power. These six projects a total installed capacity of 9.96 million kilowatts, with a total investment of 411 million yuan, the annual generating capacity of up to 500 million degrees or more, is expected to come on stream by 2014Grid tie inverter.

"our 2 million kilowatts Hang Hau coal integration project is a Xinjiang-East power transmission power support project implementation in our company following 600,000 kilowatts power plant project put into operation, the project plan invest 79 billion yuan in October 2014 and December, two units were completed and put into operation, the annual generating capacity of 110 million degrees. tender work our company has completed the design of this project, this project area, water, electricity, Road has been through, we have started construction of infrastructure. "said State Grid Energy the Hami Coal and Electricity Co., Ltd. Application to. DC power supply DC power supply DC power supply high voltage power adjustable power adjustable regulated power supply power switching power supply high-power DC power supply voltage constant current switching power supply communications power adjustable adjustable switching power supply DC power programmable DC power supply DC power supply DC adjustable DC power _ _ power switching power supply high voltage DC power _ constant voltage constant current switching power supply regulated power supply _ _ adjustable power programmable DC power supply _ high-power DC power _ high-power DC regulated power supply _ DC _ high-power adjustable DC power charger DC power supply DC power supply DC power DC regulated power supply charger DC power supply inverter DC power communication power supply DC power supply DC regulated power supply DC regulated power supply DC power supply DC power supply | power DC

reporter inverter learned, the Guodian Xu Mine Hami DC power generation Co., Ltd. Dananhu Power Plant 2 million kilowatts of coal adjustable DC power supply is adjustable regulated power supply | power DC power supply | electrical integration project office temporary main building has been completed, into the plant construction and road projects have been built and have the basic open to traffic conditions, with full construction conditions. SDIC the the Hami Energy Development Co., Ltd. 1.32 million kilowatts of power plant construction projects have completed the three host tender work and office life area foundation once excavation and construction of the temporary building construction and the main plant. Huaneng Xinjiang Energy Development Co., Ltd. Hami heavy industry park power plant 1.32 million kilowatts of coal and electricity integration project in progress related to water, electricity, roads and other preliminary work, three main tender work in progress. Shenhua Lu Hami Power Limited Dananhu power plant 1.32 million kilowatts coal integration project office and living temporary building has been basically completed, plans to start the construction of the recent comprehensive. Henan Coal Chemical Industry Group Hami investment of Limited Dananhu Power Plant 2 million kilowatts pit coal and electricity integration project has completed a feasibility study has been prepared, started construction is planned for the end of June this year.

Hami Prefectural Committee, the Administrative Office of the Deputy Commissioner Zhang said, the Hami region as a the main battlefield bridgehead Xinjiang electric delivery, according to the 2008-2015 Xinjiang Power Grid vision of grid planning report Hami - Zhengzhou and Hami -, Chongqing two ± 800 kV DC line will be built in the "12th Five-Year" around the end, and at the same time built 750 kV substation four, eight 750 kV trunk line, DC Converter Station 2 Block. , Hami will through 750 kV line in Dunhuang, Gansu, Anxi networking to Zhengzhou, Chongqing power transmission line 2 back ± 800.

around the Xinjiang electricity incoming implementation of the strategy, the Hami region there have been 13 large enterprises and groups to carry out the preparatory work of the thermal power project, involving 19 projects, the total scale has reached more than 40 million kilowatts. In accordance with the planning the Xinjiang electricity outgoing ", during the" 12th Five-Year Planning; in Yiwu County Naomaohu layout of the power supply capacity in the of Barkol County Santanghu layout power capacity of 8,000,000 kilowatts in Hami City, the layout of the power capacity of 10 million kilowatts; 2 million kilowatts.

Zhang said that, the Hami region within the fire power projects are being actively pre-construction work, to provide power to support protection for "Xinjiang East power transmission". He believes that when Hami South Zhengzhou ± 800 kV UHV DC transmission project is completed, that is, when the large-scale delivery of the Hami electricity and electric Xinjiang.

This article is from the: http://www.12vgridtiepowerinverters.com/

----20130320


Abstract and required for the design requirements of the grid. Take a voltage source inverter design of photovoltaic power generation and network operation, and 16 micro-disposal device and IGBT power devices improved inverter output waveform.

Introduction

solar photovoltaic power generation system is important for electricity or power shortages in remote geographical broken as independent power to power household appliances and lighting fixtures. Followed by electricity relaxation environment Contagion increasingly significant, with the utility grid and grid solar power system has been showing increasing competitiveness. Photovoltaic power generation and network operation will be omitted aspects of energy storage - batteries alone break photovoltaic system, thus greatly reducing the protection of the power station. Shorter battery life, eliminating the need for batteries, the life of the power generation system commensurate with the life of the solar cell. Family residential equipment photovoltaic power generation system, flaccid daytime electricity to ease the situation, the progress grid power factors and decreased line losses. Photovoltaic power plants and power generation, the ultimate will replace the customary energy generation. Photovoltaic power generation grid shown in Figure 1. The solar array power passed to the grid by the sinusoidal pulse width modulation inverter, the inverter to feed electricity sent to the grid resolution array power and local sunshine conditions. Inverter with DC - AC conversion function, but also must have the maximum power of the PV array tracking efficacy and various maintenance functions. The inverter shown in Figure 1 of the voltage-type inverter,power inverter. Voltage source inverter skills matured, the hardware required
bought easily. This article will voltage source inverter for further discussion.

1 small photovoltaic grid power stations should have the function

PV power plant and network operation, put forward higher requirements for the inverter. These requirements are as follows


ㄧ request the inverter output sinusoidal current. PV power plant back to the utility grid power required satisfaction grid-delineated indicators, such as the output of the inverter current can not contain a DC component and the high harmonics of the inverter output current is necessary to minimize, on the grid can not cause harmonic infection and so on.

ㄨ requirements of the inverter in the efficient operation of the larger case load and sunshine variations can. Energy from solar photovoltaic power plants, sunshine intensity meteorological changes, which requires the inverter in the sunshine under the premise can efficient operation.

The inverter enables

ㄩ request photovoltaic arrays work at the maximum power point. The power output of the solar cell is related to changes in sunshine, temperature, load, output characteristics with non-linear characteristics [1]. This requires an inverter efficacy of the maximum power point tracking, that no matter how the sunshine, temperature change can take the initiative to adjust to achieve the best run of the array through the inverter.

� inverter using small size, solid advanced features. Household photovoltaic power plants, of its inverter usually installed in the indoor or wall hanging on the wall, both its volume, component limits. In addition, the robustness of the whole machine is also put forward higher requirements. Solar battery life of 20 years, the life of its accessory equipment must also be its proportionate.

� requirements in mains power inverter sunshine state may own supply.

2 sine wave voltage inverter implementation

photovoltaic grid run circuit shown in Figure 2. Up is the output voltage of the inverter, Uu for grid voltage, R is the line resistance, L series reactors, Iz compared feedback grid current. To protect the power factor of feedback, contribute to the current phase must be consistent with the phase of the grid voltage. The same phase reference grid voltage Uu, Iz with Uu, the vector shown in Figure 3. Resistance R two really consistent voltage UR and grid voltage phase the reactor voltage across UL phase is outdated UR90 ì thus able to obtain the phase and amplitude of the UP


where � is the frequency of the utility grid angle. In the actual circuit, the phase, period, and amplitude of UU detected by a voltage sensor. Because R is difficult to obtain in practical systems, and thus the phase of the feedback current Iz must use the current negative feedback to achieve feedback the current Iz phase angle reference phase is the utility grid phase
bit. Readily detected with current transformers Iz, consistent ensure Iz with the grid voltage phase, in order to achieve a power factor of a feedback generation.

apply photovoltaic power grid to run dedicated inverter structure shown in Figure 4. Tube with IGBT inverter main circuit power capacity of 50A, the 600V model 2MBI50N-060. Driver circuit isolation produced by Toshiba TLP250. The inverter master the local microprocessor completed. Master chip INTEL latest inverter or motor drive dedicated 16 microprocessor 87C196MC, the chip in addition to a 16-bit instruction, also has a dedicated pulse width the
modulation (PWM) output port [2 contains a 10-bit A / D converter, an event processing array, two 16-bit timers, and a three-phase waveform generator. Each phase of the three-phase waveform generator can output two can be set to the death zone time PWM signal,Grid tie inverter.

which supply to inverter use spaces a lot. Microprocessor important to achieve the grid, real-time detection of the phase, current feedback phase restraint, the PV array maximum power point tracking and real-time sinusoidal pulse width modulation signal occurs, follows the course of their work to the utility grid voltage and phase through the Hall voltage sensor gave microprocessor 's A / D converter, the microprocessor will the phase of the feedback current in phase with the utility grid voltage for comparable sent to the PWM pulse width modulator, the error signal by the PID regulator, which completed the power factor of 1 of electricity feedback process. Microprocessor Another major task is to achieve the maximum power output of the PV array. The PV array output voltage and current resolution be detected and multiplied by the voltage, the electrical propagation sensor array output power, and then to adjust the duty cycle of the PWM output. This duty cycle regulation essentially is to regulate the the
feedback voltage size, in order to achieve maximum power optimization.

be noted from Figure 3, when the Up amplitude variation, feedback will also have a phase angle ヵ between the current and grid voltage must change. Has been achieved because the current phase feedback gripping, thus natural to achieve a decoupling of the phase and amplitude to master, so that the process of the microprocessor processing easier. In addition, the photovoltaic power generation and network operation must also be appropriate, the state utility grid outage. Practices photovoltaic grid system, the end of the inverter in the utility grid outage. Photovoltaic arrays during the day, it can still continue to generate electricity.

how it works when the utility grid power grid side commensurate short-circuit conditions, and network operation inverter will automatically cover overload. When the microprocessor detects the overload, in addition to closed SPWM signal, will disconnect the relay RE, if the PV array at this time energy output, the inverter will be in the running state run separately. When running alone restraint absolutely schematically, is the exchange of a negative feedback of the voltage condition, the microprocessor by detecting the output voltage of the inverter and to be comparable with a reference voltage, usually 220V, and then gripping the duty cycle of the PWM output, the inverter and the regulator run . Of course, running alone conditions the PV array can supply enough power at the time. If the load is too big or poor sunshine premise, the inverter helpless output enough power, the terminal voltage of the PV array that will land, so that the output switch voltage drop into the low pressure to maintain state. When grid power is restored,www.12vgridtiepowerinverters.com, will take the initiative to switch to feedback.

3 thesis

take 16 micro-disposal with high-speed IGBT power module in small capacity photovoltaic power plants to the grid. This article describing the photovoltaic power generation and grid inverter, not only has a higher effectiveness with a small distortion of output current waveform can be run independently, and in the case of the power grid, there is bound to promote the use of vision.

1 Introduction

voltage capacity constraints due to power electronic devices, the traditional two-level inverter commonly used "high - low - high" transformer to step-down and step-up for high-voltage high-power, or the use of multiple small capacity inverse variable unit through a multi-winding transformer to achieve multiple, which makes the system efficiency and reliability of the decline. Thus, it is hoped to achieve a direct high-voltage inverter technology. Series high voltage inverter based power electronic devices directly to high static and dynamic pressure circuit requirements, and high output voltage harmonic content, you need to set the output filter. Cascade multi-level inverter circuit proposed to solve the above problems, made a breakthrough.

cascade multi-level inverter is formed by several basic inverter unit (such as the h-bridge inverter) connected through a series of single-phase or three-phase inverter. Each inverter unit may output a square wave or a stepped wave, the more the level of the step ladder wave, in order to approximate a sinusoidal output voltage of the inverter is formed by the superposition of the output waveform synthesis. Characteristics of this circuit: With the increase in the number of the inverter cascade, the number of the level of the output voltage increases, so that to reduce the harmonic content of the output voltage or current waveform; due to the plurality of inverter units are connected in series to complete the entire inverter task, although the overall output switching frequency becomes high, but the switching frequency of the power devices of each inverter unit is not high, so the power device to withstand the voltage stress as compared with the non-cascade circuit is reduced in the high-pressure applications without the equalizing circuit, while avoiding the problem of the large dv / dt of the motor load caused by insulation, etc.; the failure of one unit, this unit by shorting quit working when the series or parallel connection of the cascade unit, other units still be able to properly work to ensure the normal operation of the system. The modular inverter product packaging, production and manufacture become possible, and easy expansion. In recent years, due to the above-mentioned advantages of cascade multi-level inverter in HP control, no power supply (UPS), AC FACTS (facts) application in the power electronics industry has become in the high-pressure energy conversion of the preferred solution. Therefore cascade multilevel level inverter topology and its control strategy will be very meaningful. In this paper, based on reading literature cascade multilevel level inverter main circuit topology and its control method summarize, in order to provide a reference to the cascade multi-level inverter research.

2 cascade multi-level inverter circuit topology

of

multi-level inverters to achieve the structure generally: diode clamped (diode-clampedinverter), the flying capacitor clamped (flying-capacitorinverter), which has an independent DC power cascade (cascaded-inverters with separate dcsources), multiple multi-winding transformer output type, and so on.

2.1 multi-level inverter circuit

(1) full-bridge inverter circuit

full-bridge inverter main circuit diagram is shown in Figure 1. Control the different ways it can have a number of modes, common work:


two level: S1 (D1) and the S4 (D4) is turned on, while the s2 and s3 off, UAB = VDC; Conversely, s2 (d2), and S3 (D3) conduction,power inverter, while s1 and S4 off , uab =-vdc; three-level: S1 (d1) and the S4 (D4) is conducting, UAB = VDC; S2 and s3 conduction, UAB = VDC; S1 (d1) and s2 (d2), conduction or s3 (d3) and s4 (d4), conduction, uab = 0.

improve Figure 1 can be obtained 5-level single-phase bridge inverter circuit [17], as shown in Figure 2. And compared to Figure 1, a capacitor, so that the load level of the output number 5: VDC and-VDC, 0, + VDC / 2,-VDC / 2. s5 deadline when working with single-phase full-bridge inverter circuit, output three level; s5 and s4 (d4) conduction uab = vdc / 2; s5 and s2 (d2) conduction, uab =-vdc / 2.


(2) diode clamped multi-level inverter circuit

German scholar holtz

1977 first proposed the the auxiliary switch tube neutral point clamped three-level inverter main circuit, in 1980 Japan a · nabae development proposed diode clamping inverter circuit. Figure 3 (a) is a diode clamp inverter circuit having two capacitors and can output a phase voltage of the three level.


u-phase operation of the output phase voltage level

S11 and S12 (or d11 and d12) pass, S41 and s42 off the UO potential difference between VDC / 2;

-pass

S41 and S42 (or d41 and d42), S11 and s12 off the potential difference between the UO-VDC / 2;

s12 and s41 conduction, s11 and s42 is turned off,www.12vgridtiepowerinverters.com, the the UO potential difference between 0;

s12 and s41 are not simultaneously turned on;

u "0, S12 and d1 conduction;

u "0, S41 and d4 conduction.

the

Bhagwat and stefanovic in 1983 further three-level generalized to the multi-level structure. The diode clamp multi-level conversion circuit is characterized by the use of the plurality of diodes of the corresponding switching device to be clamped, while taking advantage of the different switch combinations required for the output level. For an n-level circuit, the DC side is n-1 capacitors and can output the phase voltage of the n-level, the line voltage to a level of (2n-1), Figure 3 (b) is a diode clamped level converting circuit topology. Obviously more output level, the smaller the total harmonic distortion of the output voltage and output current. Diode clamp structure of significant advantages: is the use of the diode clamp to solve the equalizing power devices connected in series, and suitable for a high-voltage applications.

shortcomings

Although the switching device is clamped in the voltage vdc / (n-1), but the diodes have to bear multiple vdc / (n-1) reverse voltage; diode reverse voltage switch devices, multi-tube series, when the series number is large, increasing the difficulty of implementation of the actual system; When inverters transmission active power will be formed, since the charging time of the respective capacitances different from unbalanced capacitor voltage,Grid tie inverter.

(3) fly cross-the capacitive clamp type inverter circuit

1992, t · a · maynard and h · foch, proposed the structure shown in Figure 4 (a), the flying capacitor clamping type inverter circuit, which is characterized by using the clamp capacitor instead Figure 3 the clamping diode, DC capacitor unchanged, its working principle is similar to the diode clamp inverter. To output more level shall be extended in accordance with Figure 4 (b) as shown in stacked connection. Therefore also referred to as the unit multilayer the inverter (imbricatedcell multilevelinverter) [19]. The same n-level inverter output n-level phase voltage, line voltage (2n-1) level. Flying capacitor clamped inverter with respect to the advantages of diode clamp inverter:


synthesis in voltage, the switching state selection for greater flexibility; through different combination of switches on the same level, due to the introduction of the capacitor, the DC bus voltage to maintain a balanced; can control the active and The reactive power flow, and therefore can be used for HVDC.

disadvantages are: each bridge arm of the inverter, the number of capacitors with the number of output level increases, coupled on the DC side of the large capacitance so that the system is high cost and package difficult; followed by the control method is very complex, to implement It is difficult; and capacitor voltage imbalance.

2.2 cascade multi-level inverter circuit

independent DC power a cascade-type inverter

having the plurality of inverter units are linked together,power inverter, so that the number of the level of the inverter output voltage increases, so that the output waveform of the harmonic content is reduced, the switch by The withstand voltage stress is reduced. The characteristics of this structure is easy to modular design,Grid tie inverter, easy expansion; major drawback is that the isolated DC power to each unit.

(1) The basic the cascade inverter circuit

Cascade

basic cascaded inverter circuit is independent DC power inverter. Wherein each unit of the DC power supply may be the same or may be different, but the topological structure of the inverter unit is the same type. If the series is connected to the inverter bridge, at least an independent DC power supply voltage and the other bridge, said to such a multi-level inverter is asymmetric, otherwise symmetric [12] [13] [14] ( vdc1 = vdc2 = vdc3), shown in Figure 5 (a) below. Asymmetric inverter is generally lower than the symmetric type level of the output number (the same structure and progression).


(2) hybrid cascade inverter circuit

output level, reducing the number of isolated power each unit circuit structure can not be exactly the same series unit itself can be a multi-level inverter, such as a diode clamp inverter or flying capacitor

--20130319

April 16 this year, sent a letter to Chinese Vice Premier Hui Liangyu, mechanical industrial packaging food machinery experts Authority five experts suggested that the state focus on deep processing of agricultural technology and equipment to give support. The
Vice Premier Hui Liangyu made important instructions: "This opinion is very good. agricultural product processing industry, especially deep processing, and thus promote the industrialization of agriculture is our strong advocacy and support. processing industry technology and equipment support lag, Wang serious research and advance in conjunction with the relevant parties.
written instructions for implementing the Vice Premier Hui Liangyuhttp://www.12vgridtiepowerinverters.com/ProductProfile/PSW3000-48-110, China Machinery Industry Federation, as reported to the National Ministry of Science and Technology approved the 2004 international deep processing of agricultural technology and equipment exhibition held in Beijing Agricultural Exhibition, scheduled from May 17 to 21 in 2004. Agricultural processed food industry key projects for the past two years, the former State Planning Commission, the State Economic and Trade Commission approved more than 220 "," provide "state-of-the-art, the applicable economic, reliable and deep processing of agricultural key technological transformation projects" technology equipment services. the
exhibits is a major scientific and technological achievements of the Eighth China since self-developmentpower inverter, or the introduction of digestion and absorption of foreign technology, including agro-processing machinery, food processing machinery, packaging machinery, plastic printing and packaging machinery. Through the exhibition, major scientific and technological achievements and new product deep processing of agricultural technology and equipment, it is recommended that countries give priority support to the national authorities recommend. The
exhibitions support of the relevant departments of the State Development and Reform Commission, Ministry of Agriculture, Ministry of Science and Technology, the National Food Authority, the State Council Development Research Center. Economic Operation Bureau of National Development and Reform Commission, the Ministry of Agriculture, Bureau of Township Enterprises as support units; China Agricultural Machinery Industry Association and China Packaging Technology Association of Machinery Industry Packaging Technology Branch is responsible for the contractor; Association of Cities in agricultural machinery, light industry machinery, food packaging machinery As the co-organizers of the exhibition. Relevant departments of the Ministry of Agriculture is responsible for organizing the user to visit.
This is the first time to solve the "three rural" issues, agro-processing machinery, grain and oil processing machinery, feed machinery, aquatic products processing machinery, special agricultural products (tea, bee, polyandrum , etc.) the 12 processing machinery, beverage processing machinery, dairy processing machinery, food processing machinery, food manufacturing machinery, packaging machinery, plastic machinery, packaging and decoration printing machinery and other mechanical equipment, unified for the deep processing of agricultural technology and equipment to be exhibited.
During the exhibition, will recommend significant technological achievements of the national agricultural products deep-processing technology and equipmentGrid tie inverter, new products, promote the lag problem solve agricultural product processing industry technology and equipment support, promote and equipment.

This article is from the: http://www.12vgridtiepowerinverters.com/

--20130318

inverter enterprises gradually gained international recognition
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reports can know , along with the change of the entire PV industry development trend , the development situation of the PV inverter market is also developing the dramatic changes in the reform .

in the next few years , and dare the international market or the development situation of China's domestic market , advanced new inverter manufacturers Sort significant changes . Forecasts of the experts also said that in 2014 when the manufacturer of the world 's top ten production and today's situation , there is a great difference , will produce more and more Chinese enterprises .

you topcoat enterprise recognized by the national market slowly

The experts said

authority , and forecast to 2016 , when the total number of goods produced by inverters worldwide will reach 60GW, the size of the market will reach $ 10 billion . The experts also said that originally led by manufacturers in order of position will change power inverter, the key is determined by the new market development .

and solar related parts of the comparison , the occupied domestic product of the number of inverters international market weight is still relatively small . The experts believe that the domestic production the inverter and international brand inverters produce quality difference is slowly smaller . From the overall situation in each power inverter segment stationary characteristics of the inverter , the domestic production of poor conversion efficiency has made significant improvement Grid tie inverter. Inverter downstream user survey concluded some authority , a growing number of Europe , the Americas , users began to identify with our manufacturing inverter .

However , the experts said , the market occupied by how much to expand the market , not only just the inverter product itself , but also need to rely on corporate branding and market investment efforts . Therefore, future domestic inverter industry in this regard , but also to strengthen .


This article is from the: http://www.12vgridtiepowerinverters.com/
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