Very powerful car charger up to 50 amps. We have already started talking about various battery chargers more than once. This time will be no exception, consider a very powerful charger that can end up delivering up to 600 watts of power with the ability to overclock to 1500 watts.
It is clear that at such high powers one cannot do without a switching power supply, otherwise the dimensions of such a device will be unbearable in weight and size. The circuit is quite simple, shown in the figure below.
Principle of operation in general, it does not differ from other switching power supplies that we considered earlier. The structure of the work is built as follows, the initial mains voltage is filtered, unwanted ripples are removed, then it is straightened and fed to the keys, which form high-frequency pulses corresponding to their control circuit. Further, the pulse transformer lowers the voltage to the required value and is rectified by a conventional bridge rectifier. In general, everything is simple.
In this case, the role of the key management circuit is played by a master oscillator based on the IR2153 chip. The body kit of the microcircuit is shown in the diagram.
IRF740 transistors were used as keys, others can be used, we immediately note that it is the transistors that set the final power of the charger. When using the IRF740, approximately 850 watts of power is guaranteed.
At the input, in addition to the filter, a thermistor is also installed to limit the inrush current. The thermistor should be no more than 5 ohms and rated for current up to 5 A. There is also a slight subtlety in the circuit, because. at the mains voltage input 50 Hz, there are no requirements for diodes, except for the standard ones: there are no reverse voltage (600 V) and current (6-10 A), you can take almost any with the specified parameters.
The second bridge installed at the output has one feature related to the fact that a high-frequency voltage is supplied from the transformer, therefore, in addition to a reverse voltage of at least 25 V and a reverse current of up to 30 A, it is imperative to take ultra-fast diodes. By the way, it is not necessary to use 4 diodes as the first bridge, you can take a ready-made diode assembly from a computer power supply.
It will be much easier to install. Electrolytic capacitors installed after the first bridge must be rated for a voltage of at least 250 V and with a capacity of 470 microfarads, by the way, they can also be taken from a computer power supply. With a transformer, everything is also simple, you can take it from the same computer power supply, which you don’t even need to rewind.
Power switches naturally need to be installed on the heat sink, because. transistors do not have common points; we install them either on different radiators, or we isolate them with mica gaskets.
To facilitate repair work, it is desirable to install the microcircuit in a special case for easy removal and replacement, this will greatly facilitate repair and configuration. To check the device after installation, turn it on in idle mode, i.e. without load. Power keys in this case should not get warm at all. The power of 25 ohm resistors on the gates of field workers is enough to take 0.5 watts.
The resistor installed on the power supply of the IR2153 microcircuit can be taken in the range from 47 kΩ to 60 kΩ with a wattage of at least 5 W, it is a current-limiting resistor for current protection of the microcircuit. Output capacitors must be selected with a voltage of at least 25 V and a capacity of 1000 uF.
I want to immediately draw your attention to the fact that the circuit does not have protection against short circuit, polarity reversal, there is no indication of operation, etc. All these shortcomings can be easily corrected, especially since they have been described on our resource more than once.
And I also want to note one point, if you need to repair the car or fill the air conditioner, then there is no problem. There is a great company that does this on a professional level and at the same time does everything for itself.
Tell in:For a long time I was worried about the topic of how you can use a power supply from a computer as a power amplifier. But remodeling the power supply is still fun, especially a pulsed one with such a dense installation. Although I am accustomed to all kinds of fireworks, I really didn’t want to scare my family, and it’s also dangerous for myself.
In general, the study of the issue led to a fairly simple solution, requiring no special details and almost no adjustment. Collected-turned-works. Yes, and I wanted to practice etching printed circuit boards using photoresist, since recently modern laser printers have become greedy for toner, and the usual laser-ironing technology did not work out. I was very pleased with the result of working with the photoresist - for the experiment, I etched the inscription on the board with a line 0.2 mm thick. And she turned out great! So, enough preludes, I will describe the scheme and the process of assembling and adjusting the power supply.
The power supply is actually very simple, almost all of the parts left after disassembling the not-so-good impulse from the computer are assembled - from those that are not “reported” to. One of these parts is a pulse transformer, which can be used without rewinding in a 12V power supply, or recalculated, which is also very simple, for any voltage, for which I used the Moskatov program.
Block diagram of a switching power supply:
The following were used as components:
ir2153 driver - a microcircuit used in pulse converters to power fluorescent lamps, its more modern counterpart is ir2153D and ir2155. In the case of using ir2153D, the VD2 diode can be excluded, since it is already built into the microcircuit. All microcircuits of the 2153 series already have a built-in 15.6V zener diode in the power circuit, so you should not bother too much with the device of a separate voltage regulator to power the driver itself;
VD1 - any rectifier with a reverse voltage of at least 400V;
VD2-VD4 - "high-speed", with a short recovery time (no more than 100ns) for example - SF28; In fact, VD3 and VD4 can be excluded, I did not set them;
as VD4, VD5 - a dual diode from a computer power supply "S16C40" is used - this is a Schottky diode, you can put any other, less powerful one. This winding is needed to power the ir2153 driver after the switching converter starts up. You can exclude both diodes and winding if you do not plan to remove power more than 150W;
Diodes VD7-VD10 - powerful Schottky diodes, for a voltage of at least 100V and a current of at least 10 A, for example - MBR10100, or others;
transistors VT1, VT2 - any powerful field, the output depends on their power, but you should not get carried away here much, as well as remove more than 300W from the unit;
L3 - wound on a ferrite rod and contains 4-5 turns of 0.7mm wire; This chain (L3, C15, R8) can be excluded altogether, it is needed to slightly facilitate the operation of transistors;
The L4 inductor is wound on a ring from the old group stabilization inductor of the same power supply from the computer, and contains 20 turns each, wound with a double wire.
Capacitors at the input can also be supplied with a smaller capacity, their capacity can be roughly selected based on the power output of the power supply, approximately 1-2 microfarads per 1 W of power. Do not get carried away with capacitors and put capacitances greater than 10,000 microfarads on the output of the power supply, as this can lead to a "salute" when turned on, since they require significant current to charge when turned on.
Now a few words about the transformer. The parameters of the pulse transformer are determined in the Moskatov program and correspond to an E-shaped core with the following data: S0 = 1.68 sq. cm; Sc = 1.44 sq. cm; Lav.l. = 86cm; Conversion frequency - 100kHz;
The resulting calculated data:
Winding 1- 27 turns 0.90mm; voltage - 155V; Wound in 2 layers with a wire consisting of 2 cores of 0.45 mm; The first layer - inner contains 14 turns, the second layer - outer contains 13 turns;
winding 2- 2 halves of 3 turns with a wire of 0.5 mm; this is a “self-powered winding” for a voltage of about 16V, it is wound with a wire so that the winding directions are in different directions, the middle point is brought out and connected to the board;
winding 3- 2 halves of 7 turns, wound with the same stranded wire, first - one half in one direction, then through the insulation layer - the second half, in the opposite direction. The ends of the windings are brought out into the "braid" and connected to a common point on the board. The winding is designed for a voltage of about 40V.
In the same way, you can calculate the transformer for any desired voltage. I have assembled 2 such power supplies - one for the amplifier on the TDA7293, the second - for 12V to power all kinds of crafts - is used as a laboratory one.
Power supply for the amplifier for voltage 2x40V:
12V switching power supply:
Power supply assembly in the case:
A photo of testing a switching power supply - that for an amplifier using a load equivalent of several MLT-2 resistors of 10 ohms, included in a different sequence. The goal was to get data on power, voltage drop and voltage difference in the arms +/- 40V. As a result, I got the following parameters:
Power - about 200W (I no longer tried to shoot);
voltage, depending on the load - 37.9-40.1V in the entire range from 0 to 200W
Temperature at maximum power 200W after a test run for half an hour:
transformer - about 70 degrees Celsius, diode radiator without active blowing - about 90 degrees Celsius. With active blowing, it quickly approaches room temperature and practically does not heat up. As a result, the radiator was replaced, and in the following photos the power supply is already with a different radiator.
When developing the power supply, materials from the vegalab and radiokot sites were used, this power supply is described in great detail on the Vega forum, there are also options for a block with short circuit protection, which is not bad. For example, with an accidental short circuit, the track on the board in the secondary circuit instantly burned out
Attention!
The first power supply should be turned on through an incandescent lamp with a power of not more than 40W. When you first turn on the network, it should flash for a short time and go out. It shouldn't glow at all! At the same time, you can check the output voltages and try to lightly load the unit (no more than 20W!). If everything is in order, you can remove the light bulb and start testing.
Homemade chargers have always been and will be in demand, as the number of motorists is growing, and industrial devices are expensive and do not always meet the needs of users. In connection with this trend, this article will consider the option of a charger for a current of up to 50 A and a power of 600 W. The output power, if desired, can be increased by making a small refinement.
It is easy to guess that this circuit is not with a conventional step-down transformer, otherwise the weight and size of this device would be heavy. As is customary, recently in all equipment, a circuit is used here, which is based on a pulse-width modulator. Such circuits are highly efficient and do not require bulky transformers.
So, let's look at how the electronic circuit works.
The input voltage from the network passes through a filter consisting of chokes and capacitors. This is necessary to eliminate impulse noise that affects the operation of the modulator.
Further, the voltage passes through the rectifier diode bridge and electrolytic capacitors. It should be borne in mind that it is better to put capacitors with a voltage margin, 400 volts, otherwise they can shoot out after a while. This is the main problem with impulses.
The entire further circuit, consisting of powerful IRF 740 transistors, IR 2153 microcircuits and auxiliary elements, form a high-frequency pulse generator. The oscillator frequency is usually above 10 kHz and the human ear does not hear this sound, although a particularly sensitive ear can hear high-frequency beeping.
It is the microcircuit that serves as the control element, and the output stage is transistors that operate on the principle of keys.
Further, the high-frequency alternating voltage is lowered by the transformer to the desired value. The transformer has two secondary windings. The first is used to power the blower fan, and the second is actually for charging the battery. In the blowing circuit, everything is simple, there is one diode, a capacitor and a limiting resistor. The charging circuits have a diode bridge and several high capacity capacitors connected in parallel. The higher the capacitance, the more stable and better the output voltage. If the dimensions of the case allow, you can put capacitors for 4700 microfarads and 50 V. Diodes should also be given special attention, they must be high-frequency and for a current of at least 30 A.
The resistance of 25 ohms in the gate circuit of the field-effect transistor is chosen in the range of 0.5-1 watts. As for the thermistor in the input circuit, its resistance should be 5 ohms, and the current for which it is rated? 5 A.
Power transistors must be installed on aluminum or copper heatsinks. If the radiator plate is common, the transistors are installed through mica gaskets. When using separate radiators, thermal paste is used for better heat dissipation.
At the beginning of the article it was said that it is possible to increase the output current and power. To do this, instead of the transistors indicated in the diagram, you need to put more powerful ones and, accordingly, provide them with a large heat sink. The same applies to the input and output bridge diodes.
I would like to note that many components, such as a transformer, diodes and capacitors, can be taken from an unnecessary computer power supply.
With serviceable parts and proper installation, the device should immediately start working. The output voltage can be measured with a multimeter. If it is within 15 V, then everything is working. In the considered version of the memory, there is no protection against short circuit at the output and wrong polarity. This must be taken into account and be careful. In all other respects, the scheme is quite simple and effective.
Do-it-yourself converter from an uninterruptible power supply: inverter circuit 12 to 220 from a UPS
For car batteries. There are quite a few schemes for such devices - some prefer to assemble them from improvised elements, while others use ready-made blocks, for example, from computers. The power supply of a personal computer can be easily converted into a completely high-quality charger for a car battery. In just a couple of hours, you can make a device in which you can measure the supply voltage and charging current. It is only necessary to add measuring devices to the design.
Main characteristics of chargers
- Transformer - they have a very large weight and dimensions. The reason is that a transformer is used - it has impressive windings and hearts made of electrical steel, which has a lot of weight.
- Impulse about such devices is more positive - the dimensions of the devices are small, the weight is also small.
It is for compactness that consumers have fallen in love with pulse-type chargers. But besides this, they have a higher efficiency in comparison with transformer ones. On sale you can find only this type of impulse circuits. They are generally similar, they differ only in the elements used.
Charger design elements
With the help of a charger, the performance of the battery is restored. The design uses exclusively modern element base. The structure includes the following blocks:
- Pulse transformer.
- Rectifier block.
- stabilizer block.
- Devices for measuring charging current and (or) voltage.
- The main unit that allows you to control the charging process.
All these elements are small. The pulse transformer is small, its windings are wound on ferrite cores.
The simplest designs of pulse chargers for Hyundai car batteries or other brands of cars can be made with just one transistor. The main thing is to make a control circuit for this transistor. All components can be purchased at a radio parts store or removed from PC power supplies, TVs, monitors.
Features of work
According to the principle of operation, all circuits of pulse chargers for car batteries can be divided into the following subgroups:
- Charging the battery voltage, while the current has a constant value.
- The voltage remains constant, but the current gradually decreases during charging.
- The combined method is the combination of the first two.
The most "correct" way is to change the current, not the voltage. It is suitable for most of the batteries. But this is in theory, since chargers can only control the current strength if the output voltage is constant.
Features of charging modes
If the current remains constant, but the voltage changes, then you will get a lot of trouble - the plates inside the battery will crumble, which will lead to its failure. In this case, it will not work to restore the battery, you only have to buy a new one.
The most sparing mode is combined, in which charging occurs first with direct current. At the end of the process, the current changes and the voltage stabilizes. With this, the possibility of boiling the battery is minimized, and gases are also emitted less.
How to choose a charger?
In order for the battery to last as long as possible, it is necessary to choose the right pulse charger for the car battery. The instructions for them indicate all the parameters: charging current, voltage, even circuits are given in some.
Be sure to keep in mind that the charger must produce a current equal to 10% of the total battery capacity. You will also need to consider the following factors:
- Be sure to check with the seller whether a particular model of charger can fully restore the battery to working capacity. The problem is that not all devices are capable of doing this. If your car has a 100Ah battery, and you buy a charger with a maximum current of 6A, then it will obviously not be enough.
- Based on the first point, carefully look at the maximum current the device can produce. It will not be superfluous to pay attention to the voltage - some devices can produce not 12, but 24 Volts.
It is desirable that the charger has an automatic shutdown function when the battery is fully charged. With the help of this function, you will save yourself from unnecessary problems - you will not need to control charging. As soon as the maximum charge is reached, the device will turn itself off.
Certainly during the operation of such devices, problems may arise. To prevent this from happening, you need to follow simple recommendations. The main thing is to ensure that there is a sufficient amount of electrolyte in the battery banks.
If it is low, then add distilled water. Filling with clean electrolyte is not recommended. Be sure to also consider the following:
- The charging voltage. The maximum value must not exceed 14.4 V.
- The magnitude of the current strength - this characteristic can be easily adjusted on impulse chargers for Orion car batteries and the like. To do this, an ammeter and a variable resistor are installed on the front panel.
- Duration of battery charging. In the absence of indicators, it is difficult to understand when the battery is charged and when it is discharged. Connect an ammeter between the charger and the battery - if its readings do not change and are extremely small, then this indicates that the charge has fully recovered.
Whatever charger you use, try not to overdo it - do not keep the battery for more than a day. Otherwise, a short circuit and boiling of the electrolyte may occur.
Homemade devices
As a basis, you can take the circuit of a pulse charger for car batteries "Aida" or similar. Very often, in homemade products, the IR2153 circuit is used. Its difference from all the others that are used to make chargers is that not two capacitors are installed, but one - electrolytic. But such a scheme has one drawback - it can only be used to make low-power devices. But this problem is solved by installing more powerful elements.
In all designs, for example, 8N50 is used. The body of these devices is insulated. Diode bridges for homemade chargers are best used for those installed in personal computer power supplies. In the event that there is no ready-made bridge assembly, you can make it from four semiconductor diodes. It is desirable that they have a reverse current value of more than 10 amperes. But this is for cases when the charger will be used with batteries with a capacity of not more than 70-8-0 Ah.
Charger Power Circuit
In impulse chargers for Bosch and similar car batteries, a resistor is necessarily used in the power circuit circuit to quench the current. If you decide to make a charger yourself, you will need to install a resistor with a resistance of about 18 kOhm. Further along the diagram is a half-wave type rectifier unit. It uses only one semiconductor diode, after which an electrolytic capacitor is installed.
It is necessary in order to cut off the alternating current component. It is advisable to use ceramic or film elements. According to Kirchhoff's laws, substitution schemes are drawn up. In AC mode, the capacitor is replaced in it by a piece of conductor. And when the circuit is running on direct current - a gap. Therefore, in the rectified current after the diode there will be two components: the main one is the direct current, as well as the remnants of the alternating current, they must be removed.
pulse transformer
The design of the pulse charger for car batteries "Koto" uses a special design transformer. For homemade products, you can use ready-made - remove from the power supply of a personal computer. They use transformers, which are ideal for charging circuits - they can create a high level of current.
They also allow you to provide several values of voltage at the output of the charger at once. The diodes that are installed after the transformer must be pulsed, others simply cannot work in the circuit. They will quickly fail when trying to straighten high-frequency current. As a filter element, it is desirable to install several electrolytic capacitors and an RF inductor. It is recommended to use a 5 ohm thermistor to reduce the surge.
By the way, the thermistor can also be found in an old PSU from a computer. Pay attention to the capacitance of the electrolytic capacitor - it must be selected based on the power value of the entire device. For every 1 watt of power, 1 microfarad is required. The operating voltage is at least 400 V. You can use four elements of 100 microfarads each, connected in parallel. With this connection, the capacities are summed up.
