When a car sits idle for a long time, you need to start it at least once a month. The battery supplies the car well with electricity for 4-5 years, then it is not able to properly supply the car with electricity, and is also poorly charged from a generator or portable charger. After extensive experience in assembling welding inverters, I had the idea to make a device for starting an engine based on such devices.
This device can be used with or without a battery installed. With battery inverter power supply It will even be easier to start the engine. I tried to start an 88 horsepower engine without a battery. The experiment was a success, without any breakdowns.
On the inverter you need to set the output voltage to 11.2 V. The starter of the internal combustion engine is designed for this voltage (10-11 V). Inverter power supply, which we assemble has the ability to stabilize the voltage, as well as the function of protection against maximum currents of 224 A, protection against electrical wiring short circuits.
IGBT technology , according to which the electrical circuit of the device was developed, is based on the principle of complete opening and complete closing of powerful transistors that are used in the unit. This makes it possible to minimize losses on IGBT switches in the best possible way.
At the output, it is possible to regulate the current and voltage by changing the width of the power switch control pulses. Since they operate at high frequencies, adjustment must be made at a frequency of 56 kHz. Such idealization of operation is possible only with a stable output frequency, as well as maintaining it at levels at which the power supply operates. In this case, only the width and duration of the voltage will change in the range (0% - 45%) of the pulse width. The remaining 55% is the zero voltage level on the control key.
Inverter unit transformer has a ferrite core. This makes it possible to tune the device at a high frequency of 56 kHz. No eddy currents are created on the metal core.
IGBT transistors have the necessary power and do not create vortex fields around themselves. Why do you need to create such high frequencies in the power supply? The answer is obvious. When using a transformer, the higher the voltage frequency, the fewer turns of winding on the core are needed. Another advantage of the high frequency of operation is the high efficiency of the transformer, which in this case becomes 95%, since the core windings are made of thick wire.
Transformer device, used in the circuit is small in size and very light. Pulse width device (PWM) - creates less losses, stabilizing the voltage, in comparison with analog stabilization elements. In the latter case, power is dissipated in powerful transistors.
Those people who understand a little about radio electronics may notice that the transformer is connected to the power source during clock cycles with two keys. One is connected to the plus, the other to the minus. The electrical circuit based on the Flea Buck principle involves connecting a transformer with one key. Such a connection leads to large power losses (a total of about 10-15% of the total power), since the inductive windings dissipate energy on the resistor. Such power losses are unacceptable for constructing powerful power supplies of several kilowatts.
In the above diagram this defect has been eliminated. The energy release goes through the diodes VD18 and VD19 back into the bridge power supply, which in turn further increases the efficiency of the transformer.
The losses on the additional key are no more than 40 watts. The Flea Buck circuit provides for losses on the resistor that amount to 300-200 watts. The IRG64PC50W transistor, which is used in the electrical circuit of the power supply using IGBT technology, has a fast opening feature. At the same time, the closing speed is much worse, which results in pulsed heating of the crystal at the moment the transistor closes. About 1 kW of energy is released in the form of heat on the walls of the transistor. This power is very high for a transistor, which can lead to overheating.
To reduce this instantaneous power, an additional circuit C16 R24 VD31 is connected between the collector and emitter of the transistor. The same was done with the upper IGBT of the transistor, which reduces the power on the chip at the moment of closing. This implementation leads to an increase in power at the moment the transistor switch opens. But it happens almost instantly.
At the moment the IGBT opens, capacitor C16 is discharged through resistor R24. Charging occurs at the moment the transistor closes through the fast diode VD3. As a consequence of this, the format of the rise in tension is being delayed. While the IGBT is closing, the power released on the transistor switch is reduced.
This change in the electrical circuit does an excellent job of suppressing the resonant surges of the transformer, thereby preventing voltages above 600 volts from passing through the switch.
IGBT is a composite transformer that consists of a field-effect and bipolar transistor with a transition. The field-effect transistor acts here as the main one. In order to control it, rectangular pulses with an amplitude of at least 12 V and no more than 18 V are required. Special optocouplers (HCPL3120 or HCPL3180) are included in this section of the circuit. Possible impulse operating load is 2 A.
An optocoupler works this way. In the event that voltage appears on the optocoupler LED, inputs 1,2,3 and 4 are energized. A powerful current pulse with an amplitude of 15.8 V is instantly formed at the output. The pulse level is limited by resistors R55 and R48.
When the voltage on the LED disappears, there is a drop in amplitude, which opens transistor T2 and T4. This creates a higher current level in resistors R48 and R58, and also quickly discharges the capacitor of the IGBT switch.
We assemble the bridge together with optocoupler drivers on the basis of a radiator from a Pentium 4 computer, which has a flat base. Before installing the transistors, you must apply thermal paste to the surface of the radiator.
The radiator must be cut into two parts so that the upper and lower keys do not have electrical contact with each other. The diodes are attached to the radiator with special mica spacers. All power connections are installed using surface-mounted installation. On the power bus you will need to solder 8 pieces of film capacitors of 150 nF each and a maximum voltage of 630 V.
Output winding of power transformer and inductor
Since the output voltages without load reach 50 V, it needed to be rectified using diodes VD19 and VD20. Then the load voltage is supplied to the inductor, with the help of which the voltage is smoothed and divided in half.
When the IGBT transistors are open, the saturation phase of inductor L3 begins. When the IGBT is in the closed state, the inductor discharge phase begins. Discharge occurs through the diode VD22 and VD21 closing the circuit. Thus, the current that flows to the capacitor is rectified.
Stabilization and current limitation with pulse width modulation
2 is the input for voltage amplification, 1 is the amplifier output. The amplifier changes the operating current of the inverter, as well as the pulse width. Discrete changes create a load characteristic depending on the feedback voltage between the power supply and the input of the microcircuit. Pin 2 of the microcircuit maintains a voltage of 2.5 V.
The width of the operating pulse depends on the voltage at input 2 of the microcircuit. The pulse width becomes wider if the voltage is greater than 2.5 V. If the voltage is less than specified, then the width becomes narrower.
The stability of the power supply depends on resistors R2 and R1. If the voltage sags significantly due to high output currents, then it is necessary to increase the resistance of resistor R1.
Sometimes it happens that during the setup process the unit begins to make some buzzing sounds. In this case, it is necessary to adjust the resistor R1 and the capacitances of the capacitors C1 and C2. If even such measures are not able to help, you can try to reduce the number of turns of inductor C3.
The transformer must operate quietly, otherwise the transistors will burn out. Even if all of the above measures did not help, you need to add several 1 µF capacitors to three channels of the power supply.
Power capacitor board 1320 µF
When the power supply is turned on to a network with a voltage of 220 V, a current surge occurs, after which the VD8 diode assembly fails while charging the capacitor. To prevent this effect, you need to install resistor R11. When the capacitors are charged, the timer on the zero transistor will give the command to close the contacts and shunt the relay. Now the required operating current is supplied to the electric bridge with the transformer.
The timer on VT1 opens the contacts of relay K2, which allows the use of the pulse width modulation process.
Block setup
The first step is to apply a voltage of 15 V to the power bridge, ensure the correct operation of the bridge and the installation of the elements. Next, you can power the bridge with mains voltage, in the gap between +310 V, where the 1320 μF capacitors and a capacitor with a capacity of 150 nF are located, and put a 150-200 Watt light bulb. Then we connect the osfilograph to the electrical circuit to the collector-emitter of the lower power switch. You need to make sure that the emissions are located in the normal zone, not higher than 330 V. Next, we set the PWM clock frequency. It is necessary to lower the frequency until a small pulse bend appears on the oscillogram, which indicates oversaturation of the transformer.
The operating clock frequency of the transformer is calculated in this way: first we measure the clock frequency of the transformer oversaturation, divide it by 2 and add the result to the frequency at which the pulse bends.
Then you need to power the bridge through a kettle with a power of 2 kW. We disconnect the PWM voltage feedback, apply an adjustable voltage to resistor R2 at the point where it connects to the zener diode D4 from 5 V to 0, thereby adjusting the circuit current from 30 A to 200 A.
We adjust the voltage to a minimum, closer to 5 V, unsolder capacitor C23, and short-circuit the output of the block. If you hear a ringing, you need to pass the wire in the other direction. We check the phasing of the windings of the power transformer. We connect the oscilloscope to the lower switch and increase the load so that there is no ringing or even a voltage surge above 400 V.
We measure the temperature of the bridge radiator so that the radiator heats up evenly, which indicates high-quality bridges. We connect voltage feedback. We install capacitor C23, measure the voltage so that it is in the range of 11-11.2 V. We load the power source with a small load of 40 watts.
We adjust the quiet operation of the transformer by changing the number of turns of inductor L3. If this does not help, we increase the capacitance of capacitors C1 and C2, or place the PWM board away from the interference of the power transformer.
The inverter in a TV is a device for starting and stable operation of fluorescent lamps for the backlight of an LCD panel. Ensures the constant glow of these light sources for a long time and effectively controls their brightness. It can be made in the form of one or two separate blocks (master/slave), and also located together with the power supply on a single board. If you do it yourself, you need to know the functions it performs.
Tasks of the television inverter:
- conversion of direct voltage 12 - 24 volts into high-voltage alternating voltage
- stabilization and adjustment of lamp current
- backlight brightness adjustment
- providing protection against overloads and short circuits
Electrical circuit of a simple inverter for 2 backlight lamps
The device is implemented on a PWM controller U1 (OZ960), two assemblies of field-effect transistor switches (u1, u2) and high-voltage transformers T1, T2. Through connector CN1, 12 volt power (F1), a power command (ON/OFF), and constant voltage (Dimm) are supplied to adjust the brightness. The protection unit (D2, D4, D5, D6) analyzes the current or voltage at the output of the device and generates overload and feedback voltages (OS) supplied to the PWM. If one of these voltages exceeds the threshold value, the oscillator at U1 is blocked, and the inverter will be in a protection state. The node is blocked when the supply voltage is low, when the supply voltage “drops” when the load is turned on, when the converter is overloaded or there is a short circuit.
Characteristic signs of inverter malfunction
- Backlights do not turn on
- Backlights turn on and off briefly
- Unstable brightness and screen flickering
- The inverter periodically does not turn on after a long period of inactivity
- Uneven screen illumination with a 2-inverter circuit
Features of inverter unit repair
When diagnosing faults related to the correct operation of the inverter, you should first of all make sure that there is no ripple in the supply voltage and that it is stable. Pay attention to the passage of startup commands and backlight brightness control from the motherboard. Eliminate the influence of backlight lamps by using their equivalent in cases where the problem is not clear. Take advantage of the opportunity to remove protection from the inverter during repairs to determine the defective part. Do not forget about a careful visual inspection of the board and what every professional TV technician uses when repairing TVs at home - measuring voltage, resistance, capacitance using special instruments or a tester.
Sometimes, upon careful inspection of the board, you can see “burnt out” parts that need to be replaced. Very often field-effect transistor switches fail, but sometimes replacing them does not always lead to a positive result. The functionality of the unit may be restored for an indefinite period of time, and then the malfunction may occur again. You have eliminated the effect, but not the cause. Therefore, without knowing the intricacies of repairing these devices, you can lose a lot of time and effort to restore them. And, if you have doubts about the success of the matter, call a technician who has already repaired similar devices many times and knows all the “pitfalls and shoals” thanks to his accumulated experience and professional knowledge.
High-voltage transformers are considered the weak link in the inverter units. Operation under high voltage conditions requires special assembly quality of these components and places high demands on the insulation properties. In addition, it should be said that transformers can become noticeably heated during the operation of the backlight. Defects such as a break or inter-turn short circuit of the windings of these parts are commonplace. Diagnostics of these elements can be complicated by the fact that a short circuit or break can only be observed in operating mode, and “diagnosis” of them in a de-energized state will not reveal problems with them. Here, swapping the dubious and serviceable transformer and further analyzing the situation can come to the rescue.
Different TVs use inverters with different numbers of transformers. In small-sized devices, the inverter can contain 2 - 4 transformers; in large-diagonal TVs, especially in previous years, there were up to 20 similar products. Naturally, a large number of them reduces the reliability of the circuit as a whole, so in modern models their use is reduced to a minimum through innovative technical solutions.
A sign of an inverter malfunction in most cases is the absence of an image on the TV screen when there is sound. However, situations are possible when the TV, after trying to turn on, goes back into standby mode or starts flashing the LEDs on the front panel, and in this case no sound appears. The nature of the defect is different, and the source may still be the same inverter unit. Some TV models contain a feedback signal from the inverter to the motherboard processor, indicating malfunctions in its operation. Without receiving confirmation from the inverter that everything is fine with it, the processor changes the TV’s operating mode to standby or displays error messages through LED indicators. For some manufacturers, after a certain number of unsuccessful starts, the system may stop sending a command to turn on the backlight until errors are reset or the memory is cleared.
The inverter is a complex electronic device, which can cause some difficulties when repairing it yourself. These blocks for TVs with diagonals from 26 inches and above are “tied” to a specific LCD panel and, according to manufacturers, are a single device (together with the T-con block). It is very rare to find electronic circuits for these products, and never for a matrix controller. Therefore, even a professional, when diagnosing this equipment, has to recall the experience of repairing similar devices, be guided by the general principles of their circuit design solutions and use the database of datasheets for backlight driver microcircuits and key transistors. If you decide to repair the inverter yourself, but something goes wrong,
The type of power supply, as already noted, is switching. This solution dramatically reduces the weight and size of the structure, but works no worse than the ordinary network transformer we are used to. The circuit is assembled on a powerful IR2153 driver. If the microcircuit is in a DIP package, then a diode must be installed. As for the diode, please note that it is not an ordinary one, but an ultra-fast one, since the operating frequency of the generator is tens of kilohertz and ordinary rectifier diodes will not work here.
In my case, the entire circuit was assembled in bulk, since I assembled it only to test its functionality. I barely had to adjust the circuit and it immediately started working like a Swiss watch.
Transformer— it is advisable to take a ready-made one, from a computer power supply (literally any one will do, I took a transformer with a pigtail from an ATX 350 watt power supply). At the output of the transformer, you can use a rectifier made of SCHOTTTKY diodes (can also be found in computer power supplies), or any fast and ultra-fast diodes with a current of 10 Amps or more, you can also use our KD213A.
Connect the circuit to the network through a 220 Volt 100 watt incandescent lamp; in my case, all the tests were done with a 12-220 inverter with short-circuit and overload protection, and only after fine tuning I decided to connect it to the 220 Volt network.
How should the assembled circuit work?
- The keys are cold, without an output load (even with an output load of 50 watts, my keys remained icy).
- The microcircuit should not overheat during operation.
- Each capacitor should have a voltage of about 150 Volts, although the nominal value of this voltage may deviate by 10-15 Volts.
- The circuit should operate silently.
- The microcircuit's power resistor (47k) should overheat slightly during operation; a slight overheating of the snubber resistor (100 Ohm) is also possible.
The main problems that arise after assembly
Problem 1. We assembled a circuit; when connected, the control light that is connected to the output of the transformer blinks, and the circuit itself makes strange sounds.
Solution. Most likely there is not enough voltage to power the microcircuit, try reducing the resistance of the 47k resistor to 45, if that doesn’t help, then to 40 and so on (in 2-3kOhm steps) until the circuit works normally.
Problem 2. We assembled a circuit; when power is applied, nothing heats up or explodes, but the voltage and current at the transformer output are negligible (almost zero)
Solution. Replace the 400V 1uF capacitor with a 2mH inductor.
Problem 3. One of the electrolytes gets very hot.
Solution. Most likely it is not working, replace it with a new one and at the same time check the diode rectifier, maybe it is because of the non-working rectifier that the capacitor receives a change.
The switching power supply on the ir2153 can be used to power powerful, high-quality amplifiers, or used as a charger for powerful lead batteries, or as a power supply - all at your discretion.
The power of the unit can reach up to 400 watts, for this you will need to use a 450-watt ATX transformer and replace the electrolytic capacitors with 470 µF - and that’s it!
In general, you can assemble a switching power supply with your own hands for only $10-12, and that’s if you take all the components from a radio store, but every radio amateur has more than half of the radio components used in the circuit.
I decided to dedicate a separate article to the manufacture of a DC AC step-up voltage converter for 220V. This, of course, is remotely related to the topic of LED spotlights and lamps, but such a mobile power source is widely used at home and in the car.
- 1. Assembly options
- 2. Voltage converter design
- 3. Sine wave
- 4. Example of converter filling
- 5. Assembly from UPS
- 6. Assembly from ready-made blocks
- 7. Radio constructors
- 8. Power converter circuits
Assembly options
There are 3 optimal ways to make a 12 to 220 inverter with your own hands:
- assembly from ready-made blocks or radio constructors;
- manufacturing from an uninterruptible power supply;
- use of amateur radio circuits.
From the Chinese you can find good radio constructors and ready-made blocks for assembling DC to AC 220V converters. In terms of price, this method will be the most expensive, but it requires the least amount of time.
The second method is to upgrade an uninterruptible power supply (UPS), which without a battery is sold in large quantities on Avito and costs from 100 to 300 rubles.
The most difficult option is assembly from scratch; you can’t do it without amateur radio experience. We will have to make printed circuit boards, select components, a lot of work.
Voltage converter design
Let's consider the design of a conventional step-up voltage converter from 12 to 220. The operating principle for all modern inverters will be the same. The high-frequency PWM controller sets the operating mode, frequency and amplitude. The power part is made of powerful transistors, the heat from which is transferred to the device body.
A fuse is installed at the input to protect the car battery from short circuits. A thermal sensor is attached next to the transistors, which monitors their heating. If the 12v-220v inverter overheats, an active cooling system consisting of one or more fans is turned on. In budget models, the fan can work constantly, and not just under high load.
Power transistors at the output
Sine wave
The signal shape at the output of a car inverter is generated by a high-frequency generator. A sine wave can be of two types:
- modified sine wave;
- pure sine wave, pure sine wave.
Not every electrical device can work with a modified sine wave, which has a rectangular shape. Some components change their operating mode, they can heat up and start to get dirty. You can get something similar if you dim an LED lamp whose brightness is not adjustable. The crackling and flashing starts.
Expensive DC AC step-up voltage converters 12V-220V have a pure sine wave output. They cost much more, but electrical appliances work great with it.
Example of converter filling
Assembly from UPS
In order not to invent anything and not to buy ready-made modules, you can try a computer uninterruptible power supply, abbreviated as UPS. They are designed for 300-600W. I have an Ippon with 6 sockets, 2 monitors, 1 system unit, 1 TV, 3 surveillance cameras, a video surveillance management system are connected. I periodically switch it to operating mode by disconnecting the 220 from the network so that the battery is discharged, otherwise the service life will be greatly reduced.
Electrician colleagues connected a regular car acid battery to an uninterruptible power supply, it worked perfectly for 6 hours continuously, and they watched football in the country. The UPS usually has a built-in gel battery diagnostic system that detects its low capacity. How it will react to the automobile is unknown, although the main difference is gel instead of acid.
UPS filling
The only problem is that the UPS may not like surges in the car network when the engine is running. For a real radio amateur, this problem is solved. Can only be used with the engine turned off.
Mostly UPSs are designed for short-term operation when 220V in the outlet disappears. For long-term continuous operation, it is highly advisable to install active cooling. Ventilation is useful for a stationary option and for a car inverter.
Like all devices, it will behave unpredictably when starting the engine with a connected load. The car's starter draws a lot of volts, at best it will go into protection as if the battery fails. At worst, there will be surges in the 220V output, the sine wave will be distorted.
Assembly from ready-made blocks
To assemble a stationary or automotive 12v 220v inverter with your own hands, you can use ready-made blocks that are sold on eBay or from the Chinese. This will save time on board manufacturing, soldering and final setup. It is enough to add a housing and wires with crocodiles to them.
You can also purchase a radio kit, which is equipped with all radio components; all that remains is to solder it.
Approximate price for autumn 2016:
- 300W – 400rub;
- 500W – 700rub;
- 1000W – 1500rub;
- 2000W – 1700rub;
- 3000W - 2500 rub.
To search on Aliexpress, enter the query in the search bar “inverter 220 diy”. The abbreviation "DIY" stands for "do-it-yourself assembly."
500W board, output 160, 220, 380 volts
Radio constructors
A radio kit costs less than a ready-made board. The most complex elements may already be on the board. Once assembled, it requires virtually no setup, which requires an oscilloscope. The range of radio component parameters and ratings are well chosen. Sometimes they put spare parts in a bag, in case you tear off the leg due to inexperience.
Power converter circuits
A powerful inverter is mainly used to connect construction power tools during the construction of a summer house or hacienda. A low-power 500-watt voltage converter differs from a powerful 5,000-10,000-watt converter in the number of transformers and power transistors at the output. Therefore, the manufacturing complexity and price are almost the same; transistors are inexpensive. The power is optimally 3000 W, you can connect a drill, grinder and other tools.
I will show several inverter circuits from 12, 24, 36 to 220V. It is not recommended to install these in a passenger car; you can accidentally damage the electrics. The circuit design of DC AC converters 12 to 220 is simple, a master oscillator and a power section. The generator is made on the popular TL494 or analogues.
A large number of booster circuits from 12v to 220v for DIY production can be found at the link
http://cxema.my1.ru/publ/istochniki_pitanija/preobrazovateli_naprjazhenija/101-4
In total there are about 140 circuits, half of them are boost converters from 12, 24 to 220V. Powers from 50 to 5000 watts.
After assembly, you will need to adjust the entire circuit using an oscilloscope; it is advisable to have experience working with high-voltage circuits.
To assemble a powerful 2500 Watt inverter you will need 16 transistors and 4 suitable transformers. The cost of the product will be considerable, comparable to the cost of a similar radio designer. The advantage of such costs will be a pure sine output.
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