Inverters

Monday, May 5, 2008

my inverter

taiyedipo@gmail.com

View my inverters and if beautiful,contact the above address for your own design.My inverters are upto standard and they are constructed and designed with the state of the act facilities.Have a nice day.

Michael Oladipo

Friday, May 2, 2008

DC INVERTER FAQ

What is an inverter?
How does an inverter work?
Why are most inverters are 115 volts
What size wire, fuse, or breaker will I need?
What is an inverter?
An inverter changes DC voltage from batteries or solar panels, into standard household AC voltage so that it can be used by common tools and appliances.
Converters: What are sometimes called "converters", especially in the RV world, are actually battery chargers and/or DC power supplies. Why they are called converters in RV's and no place else we have not a clue. A "converter" is basically the opposite of an inverter.
Essentially, it does the opposite of what a battery charger or "converter" does. DC is usable for some small appliances, lights, and pumps, but not much else. Most systems should include an inverter of some type, even if it is just an el-cheapo $29 Walmart thing to run the TV occasionally. Some DC appliances are available, with the exception of lights, fans and pumps there is not a wide selection. Most other 12 volt items we have seen are expensive and/or poorly made compared to their AC cousins. The most common battery voltage inputs for inverters are 12, 24, and 48 volts DC - a few models also available in other voltages.
There is also a special line of inverters called a utility intertie or grid tie, which does not usually use batteries - the solar panels or wind generator feeds directly into the inverter and the inverter output is tied to the grid power. The power produced is either sold back to the power company or (more commonly) offsets a portion of the power used. These inverters usually require a fairly high input voltage - 48 volts or more. Some, like the Sunny Boy, go up to 600 volts DC input.
A few grid tie inverters can also be used with batteries, but there will be some loss in overall efficiency for feeding the grid. How much loss can vary considerably, depending on the inverter and the size and type of batteries. If you need battery backup power for a grid tie system, we recommend the Outback Power inverters, as they have the best efficiency with batteries - you will get about a 5-10% loss. With some older inverters, such as the Xantrex SW series, that can sell back excess power to the grid overall losses can be as high as 50%.
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How does an inverter work?
An inverter takes the DC input and runs it into a pair (or more) of power switching transistors. By rapidly turning these transistors on and off, and feeding opposite sides of a transformer, it makes the transformer think it is getting AC. The transformer changes this "alternating DC" into AC at the output. Depending on the quality and complexity of the inverter, it may put out a square wave, a "quasi-sine" (sometimes called modified sine) wave, or a true sine wave.
Square wave inverters are usually only suitable for running some type of electrical tools and motors and incandescent lights. They are pretty rare nowadays, some of the old 1970's Triplite and a few others, and some old military surplus is about the only place you find it now.
Quasi-sine (modified sine, modified square) wave inverters have more circuitry beyond the simple switching, and put out a wave that looks like a stepped square wave - it is suitable for most standard appliances, but may not work well with some electronics or appliances that electronic heat or speed control, or uses the AC for clocks or a timer.
What May Not Run: Appliances that use electronics to control temperature or timers may have problems with modified sine waves. This includes anything - tool or appliance - that is variable speed, bread makers, some microwaves, some washers and dryers that use electronic timing for cycling. Most computers, TV's and similar items will have no problem. Anything with a motor will use about 20% more power with a modified sine wave than with a true sine wave.
Also, some of the chargers used for battery operated tools (such as Makita) may not shut off when the battery is charged, and should not be used with anything but sine wave inverters unless you are sure they will work. Sine wave inverters put out a wave that is the same as you get from the power company - in fact, it is often better and cleaner. Sine wave inverters can run anything, but are also more expensive than other types. The quality of the "modified sine" (actually modified square wave), Quasi-sine wave, etc. can also vary quite a bit between inverters, and may also vary somewhat with the load. The very bottom end put out a wave that is nothing but a square wave, and is too "dirty" for all but universal motor driven tools, coffee makers, toasters, and other appliances that have only a heating element.
One solution to the problem of a few small appliances not working well with modified sine wave inverters is to get a large standard inverter, and a small (such as the Exeltech or Samlex) true sine wave for use only with that equipment. This would also allow you to keep the small appliance (such as an answering machine) powered up without having to run the larger inverter full time.
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Why are most inverters 115 volts?
Most utility connected homes in North America have dual AC voltages - 115 and 230. On a typical home there are three wires coming in - 115-neutral-115. It is 230 volts across the two outside ones. The 115 is used for most things, while 230 is used for water heaters, electric clothes driers, well water pumps, and air conditioning. Since these high-power items are not practical in a solar powered home, they are either not used or are replaced with gas appliances.
Most off-grid homes have little use for 230 volt AC power - but even so many newer ones are wired just like a standard home to meet electrical and building codes. If it IS required, you can "stack" two 115 volt inverters to get 230. The one exception to the above is that many AC well pumps are 230 volt. If the well pump is the only 230 volt item you have, the best choice is probably to get a step up transformer, such as the Xantrex or Outback Power 120 to 240 step up transformer.
There are export versions of most inverters for 100 volts, 105 volts, 205 volts, and 220/230 volts, in both 50 and 60 Hz.
Inverter-Chargers:
Inverters come in two basic types - with and without built in battery chargers. The ones with built in chargers are handy if you charge your batteries from AC, especially for RV's. They are also essential if using an inverter for setting up a UPS system for backup power. But not everyone needs them - and most small inverters under 1000 watts or so are simply not available with a built in charger.
Nearly all inverter-chargers made in the past few years have 3-stage chargers, so you can usually leave them powered up all the time. Nearly all inverters with chargers also have a built in transfer relay - what that means is that if you are running from AC or shore power, the power feeds through the inverter, with some being tapped off for the battery charger. If the AC power goes out, the inverter automatically switches to battery power. In most cases you won't even see a light flicker, it is so fast.
Inverter (and other) Efficiency:
Inverter efficiency is a question we get asked about a lot. The efficiency of an inverter has to do with how well it converts the DC voltage into AC. This usually ranges from 85% to 95%, with 90% being about average.
However, there is more to the story. Efficiency ratings are usually given into a resistive load (basically something like a light bulb or electric heater). When running such things as motors, the efficiency actually breaks down into two parts - the efficiency of the inverter, and the efficiency of the waveform. Waveform efficiency means that most motors and many electronic appliances run better and use less power with a sine wave. Typically, an electric motor (such as a pump or refrigerator) will use from 15% to 20% more power with a modified sine wave than with a true sine wave. When choosing an inverter based on efficiency, you should also consider what you are going to be running.
A 90% efficient modified sine wave inverter is not 90% when running a compressor motor, for example, because electric motors are less efficient. They use about 20% more power on a modified sine wave.
Inverters are also much less efficient when used at the low end of their maximum power. For example, using a 1000 watt inverter to power a 20 watt radio may actually be using 30 to 40 watts from the battery, as the inverter itself is eating up a lot just to run. Most inverters are most efficient in the 30% to 90% power range.
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What size wire, fuse, or breaker will I need?
Inverters have two or three sets of power carrying wires to be concerned about: the wires from the battery to the inverter, the wires from the inverter to the home (or other AC load), and in some cases the wiring from a backup generator or other AC source. The wiring for the AC to the home and from the generator is sized just like you would for AC wiring in a utility connected home. It is usually #10, 12, or 14 standard AC wire. For the small inverters, 800 watts or less, #16 can be used but the mechanical strength of small wire leaves much to be desired.
The wire or cables from the batteries to the inverter are much more critical, and are often undersized. In some cases, the cable may be large enough to carry the "static" load of a motor, but on start up will drop so much voltage in the cable that the inverter will shut down on low voltage cutoff. The same thing can happen with small inverters and TV sets - a TV may only use 100 watts, but the start up surge may be 300 watts for a few seconds. Wire lengths from the battery should always be kept as short as possible, but not so tight that there is a strain on the connections.

Recommended Fuses, Breakers, and Wire Sizes for Inverters

200-250

12

20 amp12 to 14
300-5001230-40 amp8 to 10
600-10001250-60 amp6 to 8
110-150012110 amp4 to 6
1100-150012200 amp/175 bkr2/0 to 2
1800-250024110 amp2/0 to 4
1800-250012300 to 400 amp/2504/0
2600-360024200 amp/1752/0
400024400 amp/2504/0
500024400 amp/2504/0
5500

48

200 amp/1752/0



These are the recommended cable sizes for a ten-foot distance from the batteries to the inverter. Note that the larger wire size is the recommended, the smaller wire size is the absolute minimum for safe operation. The sizes recommended are from a combination of maximum wire amperage capacity and voltage drop. You can't go wrong using bigger wire.The fuse and breaker sizes shown are approximate. Since transformer based (Outback Power, Xantrex) inverters usually have a much higher maximum surge rating than electronic based (Samlex, Exeltech, Statpower), they should always use the larger if more than one size is shown. The reason some show a smaller breaker size than fuse size is that breakers do not blow as fast on a temporary surge

The fuse should NEVER be bigger than 125% of the maximum surge power of the inverter. For example, an inverter is rated at 1000 watts, and 1800 watts surge. For a 12 volt inverter, divide 1800 by 12, which gives you 150. 150 x 1.25 = 190 amp. The nearest standard size fuse is 200 amp. You are always safe going to a smaller fuse, but if too small it might blow on heavy loads. DC breakers should be rated for about the maximum amperage draw, as they have a slight time delay on over current.
Which inverter has the best sine wave?
In general, from best down, it is Exeltech, Outback Power, Statpower, Samlex. All are good enough for 99% of all applications, but the Exeltech may be better for low power critical applications, such as recording or studio vans, or noise sensitive medical equipment. For higher power systems that need the best sine wave, either the Outback Power series or the Xantrex SW+ series.

Which is the "best" inverter?
There is no "best" for all purposes. Although the Outback Power & Xantrex are considered by many to be the top of the line, it does not make sense to spend $500 to $3000 when all you need is a little Statpower Prowatt or Exeltech 125 watt sine wave to power up a laptop. The best way to decide on what inverter is best is to work backwards - figure out what you are going to use it for, and then find one that fits those requirements. Also, some inverters have built in chargers, which may be needed in some systems. The Outback & Xantrex sine wave units include software and hardware for remote generator start, alarms, remote control and monitoring, computer data, and other functions - in many applications this is very important. If you are running pumps or other large motors, Xantrex or Outback are the only one we will recommend, even though some others might work.

555 Timer(Astable Multivibrator Circuit)






NE555 is composed of the voltage comparators, the flip-flop and the transistor for the discharge. The composition is simple, but it is excellent one.Three resistors are connected with the inside in series and the power supply voltage(Vcc) is divided in 3. This composition is an excellent point. 1/3 with power supply voltage is applied to the positive input terminal of the comparator (COMP1) and the voltage of 2/3 is applied to the negative terminal of the comparator (COMP2). When the voltage of the trigger terminal(TRIGGER) is less than 1/3 of the power supply voltage, the S terminal of the flip-flop(FF) becomes H level and an FF is set. When the voltage of the threshold terminal(THRESHOLD) is more than 2/3 of the power supply voltage, the R terminal of the FF becomes H level and an FF is reset.
The oscillation operation explanation
I will explain the circuit operation below. The condition immediately after the turning on



Immediately after a power supply voltage is supplied, as for the FF, the Q becomes H and becomes L condition. Because is the L, TR is in the OFF condition and the electric current flows through the resistor of Ra and the Rb at the capacitor (C). Immediately after a power supply voltage is supplied, the electric charge isn't stagnant in capacitor(C). So the voltage of the X point starts from 0V. Because the X point is lower than V1 of COMP1, the S terminal of the FF becomes the H condition. With this, the Q becomes H, becomes L condition but they are in the condition already. On the other hand, because the COMP2 (+) terminal is lower than V2, the output of COMP2 becomes the L and the FF is stable in this condition.

Output's reverse (1)



When the voltage of the X point crosses V1 of COMP1, the output of COMP1 becomes L. However, this change doesn't change the condition of the FF. The output of COMP2 becomes the H condition when the voltage of the X point rises more and reaches V2 of COMP2. With this, the R terminal of the FF becomes H and the output state of the FF reverses. The Q becomes the L condition and becomes the H condition. At this time, OUT changes into the L from H. Because became the H condition, TR becomes the ON condition. Because the interface of Ra and the Rb becomes the grounded condition, the electric current which was flowing through C so far through Ra and the Rb gets not to flow through capacitor(C). The electric charge which was stagnant in capacitor(C) begins the discharge through the Rb and TR. Voltage of the X point begins to go down with this discharge. Because voltage of the X point goes down, the voltage of the COMP2 (+) terminal becomes less than V2 and the R terminal of the FF changes into the L condition from H. This change doesn't change the condition of the FF.It is only in a little time that the R terminal of the FF becomes the H condition.

Output's reverse (2)


Because TR becomes ON, as for the electric charge of capacitor(C), it continues the discharge and the voltage of the X point falls. When the voltage of the X point becomes equal to or less than V1 of COMP1, the output of COMP1 becomes the H condition and the S terminal of the FF becomes the H condition. This changes the Q of the FF to H and changes into the L condition. Because became the L condition, TR becomes the OFF condition and the discharge from capacitor(C) stops. The electric current flows through Ra and the Rb again in capacitor(C) and the electric charge begins to store up. When the electric charge begins to store up in capacitor(C), voltage of the X point begins to go up and the output of COMP1 becomes the L condition immediately. After that, it repeats this operation and the signal of the square wave is output.When charging (accumulating the electric charge) capacitor(C), the electric current flows through Ra and the Rb and in case of the discharge (missing the electric charge), it passes only the Rb. So, the time of the charging and the time of the discharge are different. By making the Rb compared with Ra big, the difference of both becomes small but can not make the same at all. To make the same, it is good if Ra is 0 ohm, but in the case, Vcc is directly connected with TR and TR has broken. Don't make Ra = 0 ohm absolutely. If doing the ratio of Ra and the Rb by several times, in case of the practical use, there is not a problem.

sine/cosine wave inverter circuit

Sine/cosine wave inverter circuit
I introduce the oscillator which outputs the Sine wave and the Cosine wave at the same time using the operational amplifier.Because the distortion was big at the circuit to have been introducing before, I improved at the circuit with little distortion.The circuit this time combines the integration circuit and the inverter by the operational amplifier.The 90 degree phase is shifted about the sine wave and the cosine wave. The sine wave is the signal to be 90 degree delayed from the cosine wave.
In case of C=C1=C2, R=R4=R5, the oscillation frequency can be calculated by the following formula.
The example of the circuit which was made this time is shown below.=

F=1/(2 x 3.14 x 0.001 x 10-6 x 15 x 103)
=1/(0.0942 x 10-3)
=10.62 x 103
=10.62 KHz
The frequency in the actual circuit was to 10.585 KHz be.




Waveform generated as one seen from the oscilloscope

Sine Wave Oscillator




Sine wave oscillator
I introduce the sine wave oscillator which used the operational amplifier in this page.The Wien bridge sine wave oscillator to introduce is the oscillator which works in the oscillation by returning(positive feedback) the oscillation output to the input.Because there are few parts, the Wien bridge oscillator is the often used circuit.The point of this circuit is the negative feedback circuit to make the oscillation operation be stable. The circuit to be using this time changes the resistance value of the Field Effect-type Transistor(FET) at the d.c. voltage which rectified the oscillation output in the full wave and is making the oscillation operation be stable. The sine wave oscillator is the oscillator which is difficult to make because the distortion of the oscillation signal occurs compared with the square wave oscillator, the triangular wave oscillator.
In case of C=C1=C2, R=R1=R2, the oscillation frequency can be calculated by the following formula.
The example of the circuit which was made this time is shown below.
f
=
1/(2 x 3.14 x 0.01 x 10-6 x 15 x 103)
=
1/(0.942 x 10-3)
=
1.062 x 103
=
1,062 HzThe frequency in the actual circuit was to 900 Hz be.You can change the frequency when you change C1, C2, R1 and R2 of the circuit diagram. In the relation of the balance at the bridge, you had better make C1=C2, R1=R2.Even if it is different little, it is possible to oscillate.
I am explaining the following contents in the page of the explanation.
The sine wave is what?
The principle of the oscillator
The principle of the Wien bridge oscillation circuit
The amplitude control of the Wien bridge oscillation
Pattern drawing Operation explanation

inverter using IC 4069UB

DC/AC inverter (2)
On this page, I will explain DC/AC invertor with center-tapless transformer.As for the DC/AC invertor with center-tap transformer, refer to "DC/AC invertor (1)".The invertor that I made this time uses power MOS FET as swtching device. I assum that this unit is used with the battery of car. So, the input voltage is +12V DC. The output voltage is AC 100V. However, input and output voltages aren't limited to this. You can use any voltage. They depend on the transformer to use. The wave form of the output is square wave. In my experience, it is usable with a lot of home electronics equipment. The electric power which is possible to handle is decided by the transformer to use. This time, I am using the transformer with 12V-10A(secondary side). So, it is possible to handle 120VA(about 100W).I was asked about 220V output from some readers. The output voltage of the inverter is decided only in the transformer. You can use the transformer with 220V as for primary(input) and 12V as for secondary(output). At my circuit, primary and secondary should be used oppositely. Then, you will be able to get AC220V from DC12V.
FUSE must be put, because the excessive input current flows when the oscillator stops.

Circuit drawingof DC/AC inverter (2)




Circuit explanation of DC/AC inverter (2)

The square wave oscillatorThis is the square wave oscillator which used a CMOS-type logic inverters. I use the word "logic inverter" to avoid confusion with the DC/AC inverter. The output of the oscillator is connected with the drive circuit through the logic inverters. The antiphase signal of the alternating current is created using the logic inverter, too. Connect the input of the logic inverters not to be using with the grounding to avoid bad influence.As for the operation of the oscillator which used logic inverters, refer to "Square wave oscillator (2)".I chose resistance and capacitor for the oscillator in the following value. I calculated that it was possible to set to 50 Hz or 60 Hz with the variable resistor. Because there is an error of the part in the actual circuit, it is a reference value.
Minimum frequency
F= 1/( 2.2 x C x R )
= 1/( 2.2 x 2.2 x 10-6 x 4.2 x 103 )
= 1/( 20.328 x 10-3 )
= 49.2 Hz

Maximum frequency
F= 1/( 2.2 x C x R )
= 1/( 2.2 x 2.2 x 10-6 x 2.2 x 103 )
= 1/( 10.648 x 10-3 )
= 93.9 Hz

In the measurement result in the actual circuit,the minimum frequency was 43.6 Hz and the maximum frequency was to 76.6 Hz be.
The FET drive circuitBecause the output of the oscillator is the TTL of 0V to 5V, it is converted into the amplitude of vibration of 0V to 12V to drive an FET with this circuit. It is not a special circuit.

The power MOS FET switching circuitThis is the switching circuit which is the main circuit of the DC/AC inverter this time. I used C-MOS FET circuit by power MOS FET. Two sets of C-MOS FET circuits are used and are controlled by the antiphase.
In case of the input of TR3 and TR4 are L level and the input of TR5 and TR6 are H level, TR3 and TR6 become ON condition and TR4 and TR5 become OFF condition. Therefore, the electric current flows through the direction of A to B to the secondary coil(12V side) of the transformer.When the input level is opposite, TR3 and TR6 become OFF condition and TR4 and TR5 become ON condition. Therefore, the electric current which flows through the transformer becomes contrary to the case of the above.Either above-mentioned condition is continued when the oscillator stops. Therefore, the big electric current flows on the secondary side of the transformer. The fuse must be put to protect.Refer to "The operation principle of C-MOS FET" about MOS FET and the C-MOS circuit.
The +5V power circuitThis is the circuit which is used 3 terminal regulator for +5V. It is OK with the 100mA type because it is only to drive IC1.

Multivibrator

A-stable multivibrator(TR type)
I will introduce the a-stable multivibrator circuit which used two transistors.The a-stable multivibrator is the circuit which repeats the high level (H) condition and the low level (L) condition alternately.‚hIn case of the transistor type, the voltage (Vcc) of the power supply can be comparatively freely set compared with the IC type. Also, it is possible to assemble compactly compared with the IC type when considering the power circuit and so on, too.However, because VEB is a maximum of 5V in the case of a transistor called 2SC1815 used this time, as supply voltage, it's to 5V. For details, please look at circuit explanation.


Calculation of the blink periodfor A-stable multivibrator (TR type)
The period which repeats a blink is fixed by the value of capacitor (Cx) and resistor (Rx), and capacitor (Cy) and resistor (Ry). The half period time (t) is possible to calculate by the following formula. The half period is the time which is made H condition or an L condition.It uses a calculation formula on the side of TR1 as an example.t : second, Cx : Farad, Rx : ohmA repeat period is decided by the combination of Cx and Rx, and Cy and Ry.In case of Cx, Cy=47 µF, Rx, Ry=22 k-ohm, it is as follows.
The time that TR1 becomes OFF condition (t1)
t1= 0.69 * Cx * Rx= 0.69 * 47 * 10-6 * 22 * 103= 0.713 secondsTR2(t2) is similar. The frequency (f)
F= 1 / ( t1+t2 ) = 1 / ( 0.7 + 0.7 )= 0.71 Hz
The measurement frequency of the circuit which was made this time was to 0.78 Hz be.The error with the calculation value is for the error of the part and the characteristic of the transistor and so on. The measurement value of Cx, Cy was to approximately 47 µF be. The measurement value of Rx and Ry was to about 20 k-ohm be. When calculating with this value, the frequency becomes about 0.77 Hz. The calculation value and the measurement value are an near value.Don't expect a correct period with this circuit. The period changes with the temperature around. So, this circuit isn't possible to use for the circuit with strict period.

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