The starting charger allows you to start your car engine in winter. Since starting an internal combustion engine with a dead battery requires a lot of effort and time. The density of the electrolyte noticeably decreases in winter, and the sulfation process occurring inside the battery increases its internal resistance and reduces the starting current of the battery. In addition, in winter, the viscosity of engine oil increases, so the battery requires more starting power. To make it easier to start the engine in winter, you can warm up the oil in the car’s crankcase, start the car from another battery, push start it, or use a car starting charger.
The starting charger for a car consists of a transformer and powerful rectifier diodes. For normal operation of the starting device, an output current of at least 90 amperes and a voltage of 14 volts are required, so the transformer must be powerful enough, at least 800 W.
To make a transformer, it is easiest to use a core from any LATR. The primary winding should be from 265 to 295 turns of wire with a diameter of at least 1.5 mm, preferably 2.0 mm. Winding must be done in three layers. There is good insulation between layers.
After winding the primary winding, we test it by connecting it to the network and measure the no-load current. It should be between 210 - 390 mA. If it is less, then rewind a few turns, and if it is more, then vice versa.
The secondary winding of the transformer consists of two windings and contains 15:18 turns of stranded wire with a cross-section of 6 mm. The windings are wound simultaneously. The voltage at the output of the windings should be about 13 volts.
Wires connecting the device to the battery must be multi-core, with a cross-section of at least 10 mm. The switch must withstand a current of at least 6 Amps.
The starting circuit of a car charger contains a triac voltage regulator, a power transformer, a rectifier with powerful diodes and a starter battery. The charging current is set by the current regulator on the triac and is regulated by variable resistance R2 and depends on the capacity of the battery. The input and output charging circuits contain filter capacitors, which reduce the degree of radio interference during operation of the triac regulator. The triac operates correctly at mains voltages from 180 to 230 V.
The rectifier bridge synchronizes the switching on of the triac in both half-cycles of the mains voltage. In the “Regeneration” mode, only the positive half-cycle of the mains voltage is used, which cleans the battery plates from existing crystallization.
The power transformer was borrowed from the Rubin TV. You can also take the TCA-270 transformer. We leave the primary windings unchanged, but we will redo the secondary windings. To do this, we separate the frames from the core, unwind the secondary windings to the foil of the screens, and in their place wind them with copper wire with a cross-section of 2.0 mm in one layer until the secondary windings are filled. As a result of rewinding, approximately 15 ... 17 V should come out
When adjusting, an internal battery is connected to the starting charger, and the charging current adjustment is tested with resistance R2. Then we check the charging current in charge, start and regeneration modes. If it is no more than 10...12 amperes, then the device is in working condition. When the device is connected to a car battery, the charging current initially increases by about 2-3 times, and after 10 - 30 minutes it decreases. After this, switch SA3 is switched to the “Start” mode, and the car engine starts. If the attempt is unsuccessful, we additionally recharge for 10 - 30 minutes and try again.
The diagram contains: stabilized power supply(diodes VD1-VD4, VD9, VD10, capacitors C1, SZ, resistor R7 and transistor VT2)
synchronization node(transistor VT1, resistors R1/R3/R6, capacitor C4 and elements D1.3 and D1.4, made on the K561TL1 microcircuit);
pulse generator(elements D1.1, D1.2, resistors R2, R4, R5 and capacitor C2);
pulse counter(chip D2K561IE16);
amplifier(transistor VT3, resistors R8 and R9);
power unit(optocoupler thyristor modules VS1 MTO-80, VS2, power diodes V-50 VD5-VD8, shunt R10, instruments - ammeter and voltmeter);
short circuit detection unit(transistor VT4, resistors R11-R14).
The scheme works as follows. When voltage is applied at the output of the bridge (diodes VD1-VD4), a half-wave voltage appears (graph 1 in Fig. 2), which, after passing through the circuit VT1-D1.3.-D1.4, is converted into pulses of positive polarity (graph 2 in Fig. 2). These pulses for counter D2 are a reset signal to the zero state. After the reset pulse disappears, the generator pulses (D1.1, D1.2) are summed up in counter D2 and when the number 64 is reached, a pulse appears at the counter output (pin 6) with a duration of at least 10 generator pulse periods (graph 3, Fig. 2). This pulse opens the thyristor VS1 and voltage appears at the output of the ROM (graph 4 in Fig. 2). To illustrate the limits of voltage regulation, graph 5 of Fig. 2 shows the case of setting almost the full output voltage.
With the parameters of the frequency-setting circuit (resistors R2, R4, R5 and capacitor C2 in Fig. 1), the opening angle of thyristor VS1 lies within 17 (f = 70 kHz) - 160 (f = 7 kHz) electrical degrees, which gives the lower limit of the output voltage about 0.1 times the input value. The frequency of the generator output signals is determined by the expression
f=450/(R 4 +R 5)С 2
,where the dimension f is kHz; R - kOhm; C - nF. If necessary, the ROM can be used to regulate only the AC voltage. To do this, the bridge on diodes VD5-VD8 should be excluded from the circuit (Fig. 1), and the thyristors should be connected back-to-back (in Fig. 1 this is shown by the dashed line).
In this case, using the circuit (Fig. 1), you can regulate the output voltage from 20 to 200 V, but it should be remembered that the output voltage is far from sinusoidal, i.e. Only electric heating devices or incandescent lamps can serve as a consumer. In the latter case, you can sharply increase the service life of the lamps, since they can be turned on smoothly by changing the voltage from 20 to 200 V with resistor R5. Setting up the ROM comes down to adjusting the level of protection against short circuit currents. To do this, remove the jumpers between points A and B (Fig. 1) and temporarily apply +Up voltage to point B. By changing the position of the slider of resistor R14, we determine the voltage level (point C in Fig. 1) at which transistor VT4 opens. The protection response level in amperes can be determined by the formula I>k /R10, where k=Up/Ut.c., Up - supply voltage; Ut.s. - voltage at point C at which VT4 is triggered; R10 - shunt resistance.
In conclusion, we can recommend the procedure for putting the ROM into operation and inform about possible replacements of components, tolerances and manufacturing features: the D1 microcircuit can be replaced with the K561LA7 microcircuit; microcircuit D2 - microcircuit K561IE10, connecting both counters in series; all resistors in the MLT type circuit are 0.125 W, with the exception of resistor R8, which must be at least 1 W; tolerances on all resistors, with the exception of resistor R8, and on all capacitors +30%; the shunt (R10) can be made of nichrome with a total cross-section of at least 6 mm (total diameter about 3 mm, length 1.3-1.5 mm). Put the ROM into operation only in the following sequence: turn off the load, set resistor R5 to the required voltage, turn off the ROM, connect the load and, if necessary, increase the voltage with resistor R5 to the required value.
To solve the problem of starting the engine in winter, we will use an electric starter that will allow motorists to start a cold engine even with a partially charged battery and thereby extend its life.
Calculation. Carrying out an accurate calculation of the magnetic core of the transformer is impractical, since it is under load for a short time, especially since neither the grade nor the technology for rolling the electrical steel of the magnetic core is known. Find the required power of the transformer. The main criterion is the operating current of the electric starter Istart, which is in the range of 70 - 100 A. Electric starter power (W) Rap = 15 Istart. Determine the cross-section of the magnetic circuit (cm 2) S = 0.017 x Rap = 18...25.5 cm2. The electric starter circuit is very simple; you just need to correctly install the transformer windings. To do this, you can use toroidal iron from any LATRA or from an electric motor. For the electric starter, I used the transformer iron of an asynchronous electric motor, which I chose taking into account the cross section. The parameters S = aw must be no less than the calculated ones.
The stator of the electric motor has protruding grooves that were used for laying the windings. When calculating the cross section, do not take them into account. You need to remove them with a simple or special chisel, but you don’t have to remove them (I didn’t remove them). This only affects the consumption of the electrical wires of the primary and secondary windings and the mass of the electric starter. The outer diameter of the magnetic core is in the range of 18 - 28 cm. If the cross-section of the electric motor stator is larger than the calculated one, it will have to be divided into several parts. Using a metal hacksaw, we saw through the outer ties in the grooves and separate the torus of the required cross-section. Use a file to remove sharp corners and protrusions. We carry out insulation work on the finished magnetic circuit using varnished cloth or fabric-based insulating tape.
Now we proceed to the primary winding, the number of turns of which is determined by the formula: n1 = 45 U1/S, where U1 is the voltage of the primary winding, usually U1 = 220 V; S is the cross-sectional area of the magnetic circuit.
For it we take copper wire PEV-2 with a diameter of 1.2 mm. We first calculate the total length of the primary winding L1. L1 = (2a + 2b) Ku, where Ku is the stacking coefficient, which is equal to 1.15 - 1.25; a and c are the geometric dimensions of the magnetic circuit (Fig. 2).
Then we wind the wire onto the shuttle and install the winding in bulk. Having connected the leads to the primary winding, we treat it with electrical varnish, dry it and carry out insulation work. Number of turns of the secondary winding n2 = n1 U2/U1, where n2 and n1 are the number of turns of the primary and secondary windings, respectively; U1 and U2 - voltage of the primary and secondary windings (U2 = 15 V).
The winding is made with insulated stranded wire with a cross-section of at least 5.5 mm2. The use of busbar trunking is preferable. Inside the wire we place turn to turn, and on the outside with a small gap - for uniform placement. Its length is determined taking into account the dimensions of the primary winding. We place the finished transformer between two square getinaks plates 1 cm thick and 2 cm wider than the diameter of the wound transformer, having previously drilled holes in the corners for fastening with coupling bolts. On the top plate we place the leads of the primary (insulated) and secondary windings, a diode bridge and a handle for transportation. We connect the outputs of the secondary winding to the diode bridge, and equip the outputs of the latter with M8 wing nuts and mark them “+”, “-”. The starting current of a passenger car is 120 - 140 A. But since the battery and electric starter operate in parallel mode, we take into account the maximum electric starter current of 100 A. Diodes VD1 - VD4 type B50 for a permissible current of 50 A. Although the engine starting time is short, it is advisable to place diodes on radiators. We install any switch S1 with a permissible current of 10 A. The connecting wires between the electric starter and the motor are multi-core, with a diameter of at least 5.5 mm in different colors, and we equip the ends of the output tips with alligator clips.
Start-charger PZU-14-100 |
The diagram of the starting-charger clearly shows that the thyristors are controlled by current pulses of the circuit capacitance C4 - transistors VT5, VT6, VT7 - diodes VD4, VD5. The unlocking phase of the thyristors and the flow of current in the power circuit depend on the rate of increase in voltage across the capacitor C4, that is, on the current through the resistances of the current regulator R23-R25 and through the start bipolar transistor VT3. VT3 turns on in the “start” mode if the voltage on the battery drops below 11 V. The key transistor VT4 turns on the control circuit when properly connected to the battery and protects it when the current is exceeded and the windings overheat. For reliable operation of this circuit, the halves of the secondary winding are required to be as identical as possible; they are usually made by winding them into two wires or by dividing the ends of the “pigtail” in two. The current flowing in the winding is measured by the voltage difference on the loaded and free halves, since they are loaded in turn.
With the onset of the cold season comes the problem of difficulty starting a cold engine. The main load when starting is taken by the starter and battery. To make the life of the battery easier and the engine easier to start, starting devices are used.
A jump starter can be purchased at an auto parts store. Such starting devices are usually combined with a charger and they are called starting-charging devices - this is a plus. The downside of these devices is that the output parameters in the starting mode are very limited and ultimately the battery receives little help; the main load is still taken by the battery.
You can make a starting device for a passenger car yourself. To do this you will need a transformer or a core from a transformer and two diodes. The starting device should be designed for a power of at least 1.4 kW; this power will be enough to start the engine even with a weak battery. First, let's look at the circuit of the simplest starting device, and this device has proven itself very effectively in the life of car enthusiasts.
Let's start from the network side, the power cable. The current consumption of the starting device can be up to 7.5 A. For this current, a PVS 2x1.5 wire is quite sufficient; to ensure a lower voltage drop, it is advisable to use a PVS 2x2.5 wire. Switch S1 need not be installed; if installed, it must be rated for a current of at least 10 A.
Calculation of the output parameters of the starting device
To start the engine starting device should give at least 100 A at a voltage of 10...14 V. From here you can derive the power of the transformer: 14x100 = 1400 W. A starter of this power can start the engine practically without a battery, but it’s still impossible without it. At the initial moment of starting, the starter consumes about 200 A, part of this current will be supplied by the battery. After spinning the crankshaft, the starter consumes 80...100 A, and our self-assembled starting device can already generate this current. For comparison, factory-made starters are capable of delivering about half of this current.
The cross-section of the transformer core, the part where the windings are wound, is calculated by power, for a given power the area is 36 cm 2. The cross-section of the primary winding wire is at least 1.5...2.0 mm 2. It’s good if there is a transformer with similar parameters and an already manufactured primary winding. The secondary winding is completely removed. Then it is necessary to determine the number of turns of the secondary winding. We will do this using the selection method. We wind 10 turns of wire of any diameter, connect the transformer to the network and measure it into the network. We measure the voltage and divide by 10, we get the voltage of one turn. Next, we divide 12 V by the resulting voltage, we get the number of turns of each arm. We remove the temporary winding. The secondary winding is wound with insulated copper wire with a cross-section of 10 mm 2 or with an aluminum cross-section twice as large. If there are no bottom-section wires, they can be wound in several branches, for example, take two copper wires of 6 mm 2 each or four of 2.5 mm 2 each. Next, you need to connect the diodes (you can take them from a welding machine), without biting off the wire, with a margin of 2-3 turns, and measure the output voltage. The no-load voltage, at the rated mains voltage, should not exceed 13.8 V. If the voltage is higher, it is necessary to unwind the secondary winding, rewind at low voltage. When the rated voltage is reached, the leads of the secondary winding are shortened to the required length, and the circuit is assembled to its final state.
Since the output starting device has a current of up to 100 A, the output wires and terminals must be designed for this current, which can be used from a welding machine.
The simplest calculations show that in order for the starting device to work effectively when connected in parallel with the battery, it must provide a current of at least 100 A at a voltage of 10...14 V. In this case, the rated power of the T1 network transformer used (Fig. 1) must be at least 800 W. As is known, the rated operating power of a transformer depends on the cross-sectional area of the magnetic core (iron) at the location of the windings.
The starting device circuit itself is quite simple, but requires the correct manufacture of a network transformer. It is convenient to use toroidal iron from any LATRA - this results in minimal dimensions and weight of the device. The perimeter of the iron cross-section can be from 230 to 280 mm (it differs for different types of autotransformers).
Before winding the windings, it is necessary to round off the sharp edges on the edges of the magnetic circuit with a file, after which we wrap it with varnished cloth or fiberglass.
The primary winding of the transformer contains approximately 260...290 turns of PEV-2 wire with a diameter of 1.5...2.0 mm (the wire can be of any type with varnish insulation). The winding is distributed evenly in three layers, with interlayer insulation. After completing the primary winding, the transformer must be connected to the network and the no-load current must be measured. It should be 200...380 mA. In this case, there will be optimal conditions for transforming power into the secondary circuit. If the current is less, part of the turns must be rewinded; if more, it must be rewinded until the specified value is obtained. It should be taken into account that the relationship between the inductive reactance (and therefore the current in the primary winding) and the number of turns is quadratic - even a slight change in the number of turns will lead to a significant change in the primary winding current.
There should be no heating when the transformer is operating in idle mode. Heating of the winding indicates the presence of interturn short circuits or pressing and short-circuiting of part of the winding through the magnetic core. In this case, the winding will have to be done again.
The secondary winding is wound with insulated stranded copper wire with a cross-section of at least 6 square meters. mm (for example, PVKV type with rubber insulation) and contains two windings of 15 ... 18 turns. The secondary windings are wound simultaneously (with two wires), which makes it easy to obtain their symmetry - the same voltage in both windings, which should be in the range of 12...13.8 V at a rated mains voltage of 220 V. It is better to measure the voltage in the secondary winding temporarily connected to terminals X2, XZ load resistor with a resistance of 5...10 Ohms.
The connection of rectifier diodes shown in the diagram allows the use of metal elements of the starter housing not only for fastening the diodes, but also as a heat sink without dielectric spacers (the “plus” of the diode is connected to the fastening nut).
To connect the starting device parallel to the battery, the connecting wires must be insulated and multi-core (preferably copper), with a cross-section of at least 10 square meters. mm (not to be confused with diameter). At the ends of the wire, after tinning, connecting lugs are soldered.
Every car enthusiast at least once in his life has encountered a problem when his vehicle does not start for some reason. The inability to start the engine may be due to the inoperability of certain components, and sometimes the problem is simply a dead battery. Below you can find out how to choose the right starting charger for a car battery and how you can make it yourself.
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Step-by-step guide to choosing a ROM
Today in Russian auto stores you can find many different pre-start devices from different manufacturers. Each of them is characterized by the presence of certain functions, power, and other features. To choose the right starting charger for your car battery, you need to follow a few simple recommendations.
Briefly about them:
- Functions. First of all, you need to decide whether you really need to buy a jump starter charger with a motor starting function. If you understand that you need such a function, then the choice must be built directly from the ROM. If you just need a charger that will allow you to charge your car battery, then the best option would be to choose a regular charger. Such a device will be enough for these purposes, especially since its cost will be significantly lower compared to ROM.
- Characteristics of starting current. Next, having decided on the device, you need to pay attention to the inrush current characteristics. This indicator is selected depending on the starting current of the battery installed on the car. It should be noted that the starting currents of cars with diesel engines differ significantly from the current indicators in gasoline cars. Often you can find ROMs on sale that do not allow you to regulate the current value, but have the function of accelerated or normal charging mode. It must be taken into account that the accelerated mode is carried out with a higher current, accordingly, the car battery can be charged more quickly. However, experts do not recommend using this mode often, as this will affect the service life of the battery.
As for the normal mode, it is carried out with a lower current, but such charging takes longer. Thanks to the operation of the normal mode, sulfate is completely dissolved on the plates, and accordingly, this will have a good effect on the battery capacity. It must be taken into account that the starting current depends on the battery capacity, which determines the ability of the battery to produce maximum current for thirty seconds. In any case, the characteristics of the purchased device must fully correspond to the characteristics of the battery in the car. - Device type. The next step is to decide on the type of ROM for your vehicle. You can find both standalone and networked models on sale. As you understand, autonomous options can function without being connected to the network; they do not require electricity, since they are equipped with a built-in powerful battery. As for the network options, they can only function from the network. This means that their operation is only possible near the house or in the garage, and only if there is electricity in it.
- Availability of additional functionality and control devices is an important point. So that the driver can always know how the charging process is carried out, experts recommend buying devices equipped with built-in voltmeters or ammeters. Today, most of the model options allow for the process of desulfation of the car battery. When the battery is in operation, insoluble lead crystals form on its internal elements, which can result in a short circuit inside the battery cans. In order to remove this plaque and increase the service life of the device, such crystals can be destroyed as a result of exposure to current.
It is also necessary to consider that modern vehicles typically use lead-acid or gel devices. Lead-acid is much more common, so most jump starters you find on sale are designed to work only with lead-acid. As for gel batteries, not all ROMs are suitable for charging such batteries. - Temperature selection is an important point. Any launcher has a certain operating mode; you need to familiarize yourself with this characteristic before choosing a device. The temperature regime determines at what temperatures the device can start the engine. If the problem with starting the engine in your case is relevant in the winter season, then this characteristic cannot be ignored.
Before choosing a device, you need to consider that the device is being purchased for a long time. Even if today you own a small car with a 60 Ah battery, perhaps in a few years you will have a more powerful car with a more powerful battery. Therefore, in order to purchase the ROM correctly, it is advisable to take the device with a reserve. If you buy a device designed for a current of 15 amperes, this will make it possible to charge even the most powerful batteries.
Whatever ROM you choose, you must take into account that, unlike traditional ROMs, these devices operate with high currents. Therefore, during operation it is always necessary to observe safety precautions - the wires are always connected strictly - plus to plus, minus to minus.
DIY instructions
If necessary, you can easily assemble a starting charger for a car at home with your own hands. This will save money, but to assemble it yourself you need to have certain skills. If you have them, then we offer detailed instructions (the author of the video is Anton Buryy).
Materials and equipment
So, if you want to make a starting battery charger with your own hands, then first of all you need to make sure that you have everything at hand.
We are talking about the following materials and tools:
- a working soldering iron with all consumables;
- textolite tiles;
- transformer, you will need a step-down device;
- a small fan, can be used from the computer power supply or from the PC case;
- high voltage cable, cross-section should be 2-2.5 millimeters;
- You will also need wires with which the ROM will be connected to the battery; these wires must be equipped with special clamps.
Of course, in addition to this, you must have all the necessary radio components, as well as elements for fastening.
Device assembly process
Now let's move directly to the issue of assembling a starting charging device with our own hands in accordance with the diagram. There can be many schemes; you can find dozens of different schemes on the Internet. We bring to your attention one of the simplest schemes that will allow you to assemble it yourself.
- Do-it-yourself assembly of the device is carried out on a PCB tile that you have prepared in advance; its size must be appropriate. One of the most basic and largest elements of a starting battery charger is the transformer, so we will start with it. In the PCB tile, using a drill, you need to drill holes of the required sizes into which fasteners and wiring will be installed.
- Rectifier diodes can get very hot during operation, so you need to think about proper cooling for them in advance. For example, special iron cooling elements (so-called jackets) can be used for these purposes. Sometimes installing metal jackets may not be enough to provide cooling for the rectifier diodes. In this case, you will need the same fan that you removed from the old computer case or power supply. If there is no such fan, then you can use heat removal devices from the computer processor, a radiator. In order for a home-made starting charger to remove heat, the case must be equipped with appropriate heat-dissipating blinds in advance.
- According to many car enthusiasts, a home-made starting battery charger does not necessarily need to be installed in the case. But if you have already assembled the device, is it really difficult to equip it with a housing? Moreover, it is the case that allows you to protect the battery charger from various external influences, which is especially important if you plan to carry the device with you in the car. Moreover, when working with ROM, the driver will be protected from the effects of current, and this is important.
- To equip the case, you can use a box of appropriate sizes. For example, this could be a case from an old desktop computer. You will have to modify it a little, but in the end you will get a full-fledged starting charger made by yourself. In addition, all indicators and switches, as well as other control components, can be mounted on the front of the computer case. Learn more about how to make an adjustable ROM with your own hands from the video. The author of the video, valeriyvalki, states that even a person who does not have knowledge in the field of radio electronics can cope with such a task.
Of course, if you decide to start such an important process, then you will want the device that is made for you to last a long time and to be able to rely on it at any time. Achieving this can sometimes be difficult, especially if you have no experience in making such devices and this is your first time encountering it.
So, in order to do everything correctly with your own hands, you need to take into account some recommendations, we will talk about them further:
- Firstly, you need to take a responsible approach to choosing a transformer. You need to choose a device that has a good power reserve. If the device is more powerful, then during operation, when charging the vehicle battery, it will heat up less. Accordingly, the service life of such a device will be longer. If in the future you suddenly decide to upgrade your ROM, making it more functional and, accordingly, more energy-consuming, then more power will also be to your advantage. Thanks to the high power, you don't have to buy a new transformer or reassemble it. Remember that the transformer is one of the main components of any ROM. You also need to take into account that the transformer itself must be of high quality; if you see that its condition is deplorable, then it is better not to use such an element for making ROM. Otherwise, you may even damage your car battery.
- An equally important component of any ROM circuit is the high voltage wires. When purchasing such wires, you need to make a choice in favor of elements characterized by excellent insulation. First of all, insulation is an excellent protection for wiring from possible external influences. In addition, high voltage cables will not be as tangled as regular wires, and this will greatly simplify the ROM assembly procedure.
- If you have a problem choosing cables for charging and connecting to the battery, then this problem can be solved. You can build such wires yourself by cutting off a certain part of the insulating layer on the cable, in particular, at the point of connection to the ROM and battery. You can use a soft copper wire as a cable; of course, it must have excellent insulation, which will avoid possible problems. When you have to force the engine to start, a cable with a poor cross-section will begin to heat up quickly, and accordingly, the insulation may also begin to lose its characteristics. As a result, this may cause a short circuit. Therefore, immediately make sure that the cables for starting the motor are removable; in this case, using the device will be more convenient.
- Please ensure that the fan that will perform the cooling function is operational. Cooling during operation of the starter is very important. If the ROM is not cooled properly, it will overheat during operation, which can lead to certain problems.
- If this is your first time encountering the issue of arranging such a system, then it is advisable to make the diagram as simple as possible. Connecting too complex circuits can confuse you, and if some actions are performed incorrectly, this can lead to a short circuit, which will negatively affect the battery's condition as a whole. If you doubt that you will be able to perform all the steps correctly and end up with a device that you can use, then the best option would be to buy a new ROM.
Video “Production of a starter-charger at home”
You can learn more about developing a circuit and creating a ROM with your own hands using improvised means from the video below (the author of the video is Evseenko Technology).
Sorry, there are no surveys available at this time.Hello all readers. Today we will consider the option of building a powerful switching power supply that provides an output current of up to 60 Amps at a voltage of 12 Volts, but this is far from the limit; if desired, you can pump out currents of up to 100 Amps, this will give you an excellent starting and charger.
The circuit is a typical push-pull half-bridge network, step-down switching power supply, this is the full name of our block. our favorite microcircuit IR2153 is used as a master oscillator. The output is supplemented with a driver, essentially a regular repeater based on complementary pairs BD139/140. Such a driver can control several pairs of output switches, which will make it possible to remove more power, but in our case there is only one pair of output transistors. 
In my case, powerful n-channel field-effect transistors of type 20N60 with a current of 20 Amperes are used, the maximum operating voltage for these switches is 600 volts, they can be replaced with 18N60, IRF740 or similar, although I don’t really like the 740s because of the upper voltage limit of everything at 400 volts, but they will work. The more popular IRFP460 are also suitable, but the board is designed for keys in the TO-220 package. 
A unipolar rectifier with a middle point is assembled in the output part, in general, to save the transformer window, I advise you to install a regular diode bridge, but I didn’t have any powerful diodes, instead I found Schottky assemblies in a TO-247 package of type MBR 6045, with a current of 60 Amps, and installed them , to increase the current through the rectifier, I connected three diodes in parallel, so our rectifier can easily pass currents up to 90 Amperes, a completely normal question arises - there are 3 diodes, each 60 Amperes, why 90? The fact is that these are Schottky assemblies, in one case there are 2 diodes of 30 amperes each connected with a common cathode. If anyone doesn’t know, these diodes are from the same family as the output diodes in computer power supplies, only their currents are much higher. 
Let's take a superficial look at the principle of operation, although I think for many everyone is clear. 
When the unit is connected to a 220 Volt network through the R1/R2/R3 chain and the diode bridge, the main input electrolytes C4/C5 are smoothly charged, their capacity depends on the power of the power supply, ideally a capacitance of 1 μF per 1 watt of power is selected, but some variation is possible in one direction or another, capacitors must be designed for a voltage of at least 400 Volts. 
Through resistor p5, power is supplied to the pulse generator. Over time, the voltage on the capacitors increases, the supply voltage for the ir2153 microcircuit also increases, and as soon as it reaches a value of 10-15 Volts, the microcircuit starts up and begins to generate control pulses, which are amplified by the driver and supplied to the gates of the field-effect transistors, the latter will operate at a given frequency, which depends on the resistance of resistor r6 and the capacitance of capacitor c8.
Of course, voltage appears on the secondary windings of the transformer, and as soon as it is of sufficient magnitude, the composite transistor KT973 opens, through the open transition of which power is supplied to the relay winding, as a result of which the relay will operate and close contact S1 and the mains voltage will already be supplied to the circuit not through resistors R1, R2, R3 and on the relay contacts.. 
This is called a soft start system, more precisely a delay when turning on, by the way, the relay response time can be adjusted by selecting a capacitor C20, the larger the capacitance, the longer the delay. 
By the way, at the moment the first relay operates, the second one also operates; before it operates, one end of the transformer’s network winding was connected to the main power supply through resistor R13. 
Now the device is already operating in normal mode, and the unit can be overclocked to full power.
In addition to powering the soft start circuit, the 12 Volt low-current output can power a cooler to cool the circuit.
The system is equipped with a short circuit protection function at the output. Let's consider the principle of its operation.
R11/R12 acts as a current sensor; in the event of a short circuit or overload, a voltage drop of sufficient magnitude is formed across them to open the low-power thyristor T1; when it opens, it short-circuits the plus supply for the generator microcircuit to ground, so the microcircuit is not supplied with supply voltage and it stops working. Power is supplied to the thyristor not directly, but through an LED; the latter will light when the thyristor is open, indicating the presence of a short circuit. 
In the archive, the printed circuit board is slightly different, designed to receive bipolar voltage, but I think converting the output part to unipolar voltage will not be difficult.
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That's all, I was with you as always - Aka Kasyan
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