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  • The principle of operation of a resonant switching power supply. Magnetic resonance energy source

    The principle of operation of a resonant switching power supply. Magnetic resonance energy source

    I usually adhere to the principle that the fewer parts in the diagram, the simpler it is, the more reliable it is. But this case is an exception. Those who have designed and assembled circuits of powerful 12/24-volt to 300-volt step-up converters (for example) know that classical approaches do not work well here. The currents in the low voltage circuits are too high. The use of PWM circuits leads to switching losses, which instantly overheat and disable the power transistors. Internal resistance power switches are a serious obstacle to the use of circuits with a design limiting switching losses, such as bridge and half-bridge circuits.

    The above circuit is based on the separation of the voltage boost function and its stabilization in different stages. With this approach, we get the opportunity to make the most problematic unit - the inverter - work in a resonant mode with minimal losses on the power switches and a rectifier bridge in the high-voltage part of the circuit. And the stabilization of the output voltage is carried out in the block STwhich is built using a simple step-up topology. Now its scheme is not given, there will be a separate article about it. A stable desired voltage is removed from its output.

    Schematic diagram of a resonant voltage converter

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    MICOR technology. A new generation of power supplies based on the resonance phenomenon

    The method using pulse width modulation (PWM) is the answer to the search for a near perfect stabilized power supply. It is known that in a pulsed source the switch is either turned on or off and control is carried out with zero power dissipation, in contrast to a linear stabilizer, where stabilization occurs due to power dissipation in the bushing element. In real-world conditions, PWM gives a reasonable approach to lossless switching at the expense of lower switching frequencies such as 20-40 kHz. If you look at the situation from the other side, you can tell why this frequency range has been popular for so long.

    From the very beginning of PWM stabilization, designers have tried to move towards higher frequencies, since this can reduce the size, weight and cost of the magnetic core and filter capacitors.

    When high frequency there are other advantages to switching. By using higher frequencies, a reduction in radio interference and electromagnetic noise can be expected; less problems with shielding, decoupling, isolation and limiting in the circuit. Faster response can also be expected as well as lower output impedance and ripple magnitude.

    The main obstacle to the use of higher frequencies was the practical difficulty of creating fast and sufficiently powerful switches. Due to the fact that it is impossible to achieve instantaneous switching on and off of the switch, there is voltage on it during switching and at the same time current flows through it. In other words, trapezoidal rather than rectangular oscillations characterize the switching process. This, in turn, results in switching losses that negate the theoretically high efficiency of an ideal switch that instantly turns on, has zero resistance when on, and turns off instantly. In fig. 1 compares PWM and resonant switching mode, which will be discussed in more detail.

    From the above, it is obvious that an ideal switch should not have any voltage drop while it is on. All of this reasoning suggests that high efficiency was an elusive task, especially at high switching frequencies, until progress was made in pulsed semiconductor devices.

    It should also be pointed out that at the same time progress was needed in the development of other devices, such as diodes, transformers and capacitors.

    We must pay tribute to workers in all areas of technology: the switching frequency when using PWM was increased to 500 kHz. However, at higher frequencies, say 150 kHz, it is better to consider another method. So, we come to the resonant mode of operation of the power supply.

    The stabilized power supply using the resonant mode is indeed a big leap forward in technology. Although it must be said that the use of resonance phenomena in inverters, converters and power supplies predates the era of semiconductors. It turned out that when using resonance phenomena, it was often possible to obtain good results.

    For example, in the first televisions, the necessary high voltages for the kinescope were obtained using a radio frequency power source.

    It was a vacuum tube sine wave generator operating at a frequency of 150 to 300 kHz, in which an increase in the alternating voltage was achieved in a resonant radio frequency transformer. As such, similar circuits are still used to generate voltages of at least several hundred thousand volts for various industrial and research purposes. Higher voltages are often achieved through the combined use of a resonant mode of operation and a diode voltage multiplier.

    It has long been known that inverter resonant output circuits stabilize the operation of electric motors and welding equipment. Usually, a coil with a large inductance was included in the break in the wire leading from the DC voltage source to the inverter. In this case, the inverter behaves in relation to the load as a current source, which makes it easier to meet the condition for the existence of resonance phenomena. In this case, it is more correct to call the existing thyristor inverters quasi-resonant: the oscillatory circuit is periodically subjected to shock excitation, but there are no continuous oscillations. Between the excitation pulses, the oscillating circuit transfers the stored energy to the load.

    From the above, it is clear that the widespread use of the resonant mode of operation began after the creation of specialized control ICs. These ICs freed designers from the glitch problems that inevitably accompany the desire to use the resonant mode at frequencies of several hundred kilohertz or several megahertz, where the small size of the components can lead to a noticeable reduction in size, weight and cost.

    In 2010, our specialists created a number of welding machines for manual arc welding on the resonant system of work: Handy-190, Handy-200, X-350 Storm (Fig. 2).

    Currently, on the basis of this technology, machines are being designed for semi-automatic and automatic welding (Fig. 3).

    Such equipment has a number of technological advantages:

    • almost "ideal" external voltage-current characteristic of the power supply, more elastic and softer arc due to the resonant control structure;
    • confident ignition and comfortable welding for all types of electrodes;
    • significantly higher efficiency (lower power consumption);
    • the possibility of more accurate control of the drop transfer due to the instant (1.5 MHz) response of the control circuit to external disturbances (arcs), and as a consequence - a significant reduction in spatter, stable burning of the welding arc in all spatial positions.

    Figure: 1. Oscillograms showing the difference between PWM (left) and resonant mode (right). With PWM, switching losses occur due to the simultaneous flow of current through the switch and the presence of voltage across it.

    Note that this situation is absent in resonant operation, which uses frequency modulation (FM) to stabilize the voltage.

    Figure: 2. Handy-190 Micor

    Figure: 3. The main circuit of the resonant converter

    This article will focus on the LLC resonant switching power supply (SMPS), for the UMZCH based on the IRS27952 controller (aka IRS27951), a simplified method for calculating all the elements for a given switching power supply will also be described in detail. Immediately I would like to draw your attention to the fact that the process of calculating and manufacturing a resonant SMPS is very complicated and not everyone will be able to cope with it, so it is not recommended to take on the construction of this power supply for inexperienced radio amateurs, correctly assess your strength. Of course, for the manufacture of such a power source, an oscilloscope and a device must be available that can measure capacitance and inductance (LC meter). The calculation method described in the article is simplified, it does not take into account all the nuances and subtleties, but it is enough to build a workable resonant switching power supply. The article will not give a detailed description of the principle of operation of resonant pulse converters, the main emphasis will be on describing the process of calculating and manufacturing a resonant SMPS.

    What are the advantages of a resonant SMPS in comparison with a "classical pulse generator"? The advantages of the resonant mode are low losses and electromagnetic interference (which are much easier to control and filter), lower recovery losses of rectifier diodes, less load on all elements of the power supply, which gives increased reliability and durability relative to "classic SMPS", the ability to work on much higher frequencies without sacrificing efficiency, reliability and cost. And the most important advantage: the resonator is fashionable: D

    • Output power (calculated) \u003d 250W
    • Output power (maximum tested) \u003d 276W
    • Output voltage (in the range from 0W to 276W) \u003d +/- 40V (+/- 0.1V)
    • Efficiency (at an output power of 276W) \u003d 92%

    Oscillograms of the current shape through the primary winding of the resonant transformer (at different values \u200b\u200bof the output power):

    The described SMPS has a soft start, protection against short circuit in the load and stabilization of the output voltage, which precisely maintains the output voltage of the converter at the same level, over the entire range of output powers. When operating at an output power of up to 200W, there is no noticeable heating, not a single element of the power supply. Power keys were not installed on the radiator. With an output power of 276W, the keys become barely perceptibly warm, but the primary winding of the transformer is already noticeably beginning to warm up. Short circuit protection is working properly. When the output of the converter is closed, generation stops, the power supply goes into sleep mode and remains in it until the short circuit is eliminated. After eliminating the short circuit, after a certain time, the power supply automatically restarts and continues to work in normal mode.

    Resonant circuit pulse source power supply based on IRS27952:

    I will not describe in detail the principle of operation of the circuit, I will dwell only on certain points. The initial start-up of the converter occurs through a chain of resistors R16, R10, R7 and R6. Further power supply to the controller is carried out from the self-supply circuit (R14, C8, VD4, VD7). Zener diode VD2 maintains the controller supply voltage at the same level - 16V. I want to draw your attention to the fact that the IRS27952, unlike, for example, IR2153 and IR2161, does not have a built-in zener diode, therefore the use of an external zener diode is strictly necessary, otherwise the controller is guaranteed to fail. Capacitors C3 and C5 smooth out ripple and eliminate noise in the IRS27952 power circuit. Resistor chains R1, R2, R3 and R5, R9, R15 - designed to discharge capacitors after shutdown mains supply converter. Special attention should be paid to the following elements: Rfmin, Rfmax, Rfss, Ct, Css - these are the frequency and time of the setting elements of the converter, their ratings must be calculated for your specific tasks, this will be discussed later. Zener diodes VD10 and VD13 are also selected for the output voltage you need: the total stabilization voltage of the two zener diodes must be equal to the calculated value of the output voltage of one arm, in this case, to obtain an output voltage of +/- 40V, two 20V zener diodes are used. Perhaps this is all that can be said about the circuit, in principle it differs little from any of the pulse converter circuits, made on controllers from International Rectifier (now Infineon). It's time to move on to the calculation.

    Calculation of the resonant circuit. To calculate, we need a program ResonantSMPS from the package, authorship of the Old Man. I must say right away that the calculation method described below is simplified and an experienced eye will be able to find some omissions in it, this was done intentionally, in order to simplify the calculation as much as possible, so that the maximum number of unprepared radio amateurs could repeat this resonant SMPS. And so, open the program and enter the initial data:

    At the first stage, we enter all the initial data as in the screenshot above (further we will correct them). All you need to choose yourself is the output voltage. In the window opposite "Rated voltage, V", enter the voltage you need. For example, if you need a bipolar output voltage +/- 40V, then enter 80V (80V \u003d 40V + 40V). I repeat: it is necessary to select the ratings of the VD10 and VD13 zener diodes, so that their total stabilization voltage is approximately equal to the required output voltage of the SMPS (voltage of one arm). That is, if you need an output voltage of +/- 40V, then you need to use two zener diodes of 20V each, if you need, for example, +/- 35V, then a VD10 Zener diode for 30V and a VD13 Zener diode for 5.1V. The rated current is calculated from the required output power of the power supply and voltage. Suppose we want to get an SMPS with an output power of 200W, which means we need to divide the desired 200W by the rated voltage, in our case 200W / 80V and we get the rated current \u003d 2.5A - we enter this value into the corresponding window of the program. Direct drop across diodes is 1V. If you know the exact value of the voltage drop across the diode, then indicate it, but in any case, you can indicate the direct drop across the diodes is equal to one volt, this will hardly affect the accuracy of the calculation, all the more so. Next, select the type of rectification - bridge. And we enter the desired diameters of the wires with which you will wind the transformer. The diameter of the wire should not be more than 0.5 mm, it is better to use a thinner wire and wind it in several cores. After that, we select a suitable core:

    I used an ETD29 core and therefore on the board the seat is made for this type and size of the core, for any other core you will have to adjust the PCB. And you need to choose such a core so that it fits in terms of overall power and the entire winding fits on its frame. After selecting the core, press the "Calculate" button and see what we have done:

    Immediately you need to set the minimum possible value of the non-magnetic gap, equal to that offered by the program (in my case, 0.67mm) and press the "calculate" button again. After that, we look at only one line - this is the "capacity of the resonant capacitor". In order to simplify our life and not waste our time and effort on the selection of a non-standard capacitance from several series-parallel connected capacitors, we change the value of the resonant frequency in the corresponding window of the program, so that the capacitance of the resonant capacitor is equal to some standard value of the capacitance. In my case, the capacitance of the resonant capacitor turned out to be 28nF, the closest standard value is 33nF, and we will strive for this value.

    When manipulating the resonant frequency, the gap should always be set to the minimum or very close to the minimum value that the program offers. I recommend choosing the resonant frequency in the range 85 - 150 kHz .. In my case, the resonant frequency corresponding to the "convenient" resonant capacitance is 90 kHz. All the most important numbers that you need to remember, write down, screen, that will be needed in the future:

    You will need the values \u200b\u200bin red boxes when winding the transformer. I want to draw your attention to the fact that the number of turns of the secondary winding corresponds to the entered value of the output voltage - 80V. If we want to get a power supply with a bipolar output voltage of +/- 40V, it is necessary to wind not one, but two secondary windings, in this case two windings of 12-13 turns each (we divide the resulting 25 turns by two). For further calculations, we need to look at the transfer characteristic (for this, you need to click on the corresponding button in the upper left corner of the program window):

    Remember the values \u200b\u200bFmin and Fmax. We have them equal: Fmin \u003d 54kHz, Fmax \u003d 87kHz. We will need these values \u200b\u200bfor further calculations.

    Calculation of the ratings of the strapping IRS27952. At the very end of this article, you need to download the file NominaliObvyazki.xlsx... You need Microsoft Excel to open it. Open the file and see the following:

    It remains only to enter our Fmin and Fmax obtained above and get all the ratings of the IRS27952 strapping. The only thing we need to choose is the capacitance Ct, which sets the amount of dead time. On the good, this would require a rather complex calculation, which must be performed based on the parameters of the keys used, but since we have a simplified calculation, I recommend simply using Ct capacitors, a capacitor with a capacity of 390-470pF. This capacity and the corresponding dead time will be enough not to go into hard switching mode when using most popular switches, such as IRF740, STP10NK60, STF13NM60 and 2SK3568 indicated in the diagram. The optimal soft start duration is 0.1 sec, you can set a longer duration up to 0.3 sec, it no longer makes sense (with the output capacitance of the SMPS capacitors up to 10000mkF). We enter our Fmin and Fmax and get:

    All strapping ratings (except for the soft start capacitor capacity) are automatically rounded to the nearest standard values. Here you can also see the actual values \u200b\u200bof the minimum, maximum frequencies and soft-start frequencies, which will be obtained with the applied standard strapping ratings. The capacity of the soft start capacitor is drawn from several capacitors, ceramic SMD and electrolytic, for this there is enough space on the PCB. At this point, the calculation can be considered complete.

    Resonant circuit implementation. The resonant circuit includes: a resonant transformer, a resonant capacitor and an additional resonant choke (if necessary). We already know the value of the resonant capacitance. The resonant capacitor must be a film capacitor, such as CBB21 or CBB81, CL21 is also allowed (but not recommended). The capacitor voltage must be at least 630V, better than 1000V. This is due to the fact that the maximum allowable voltage across the capacitor depends on the frequency of the current through the capacitor, a 400V capacitor will not live long. And now the most interesting thing is the resonant transformer. We have all the necessary initial data for winding it. How to wind? There are several options. The first option: wind it like a normal transformer - we wind the primary to the entire width of the frame, then we wind the secondary to the entire width of the frame (or vice versa, first the secondary, then the primary). The second option: wind the secondary to the entire width of the frame, and the primary to half or a third of the frame width (or vice versa - to the primary to the entire width, and the secondary to half or a third of the frame width). And the third option is to use sectional winding when the primary and secondary windings are completely separated. This will require either a special sectioned frame or you will have to make such a frame yourself, dividing the frame with a plastic partition.

    Why is this and what does it give? The first option is the simplest, but gives the minimum leakage inductance. The second option is very inconvenient in winding, it gives an average leakage inductance. The third option gives the highest and most predictable leakage inductance, in addition, the most convenient way to wind. You can choose any of the options. After you have decided on the winding option and wound the required number of turns of the primary and secondary windings, you need to change the resulting dissipation inductance of the primary winding of the resulting transformer. For this you need to assemble a transformer. At this stage, it is not necessary to glue parts of the core and introduce a gap (the leakage inductance does not depend on the size of the gap, its presence or absence), it is enough to temporarily tighten the core with electrical tape. It is necessary, using soldering, to reliably close all the terminals of the secondary winding with each other and measure the inductance of the primary winding. The resulting inductance value will be the leakage inductance of the primary winding of the transformer. Let's say you have a dissipation inductance of 50μH. Let's compare the resulting value with the calculated Lr value, which you calculated above:

    It didn't work out! We need 94 μH, but we got 50 μH. What to do? The main thing is not to panic! This happens, you will definitely have it, and this is absolutely normal. An additional resonant choke will help us to eliminate this discrepancy. But, if you haven't forgotten yet, I wrote a little higher about three options for winding a transformer ?! So, the first method gives the lowest dissipation inductance and using it, you are guaranteed to need an additional choke. The second option gives an average dissipation inductance and you will most likely need a choke anyway, but not with such a large inductance as with the first option. But in the case of using the third option, it is possible to immediately obtain the required dissipation inductance of the primary winding of the transformer, without using an additional resonant choke. The required leakage inductance, with the third winding option, is obtained by the correct choice of the ratio of the winding width of the primary and secondary windings. It is even possible that you are lucky and you can guess with the width of the winding of the primary and secondary, and immediately get the required leakage inductance (as I did). But if you are unlucky and the measured leakage inductance and the required calculated value do not match, then you need to use an additional resonant choke. The inductance of the choke should be equal to: the calculated value of Lr minus the resulting real value of the leakage inductance of the primary winding. In our case: 94μH-50μH \u003d 44μH - this should be the inductance of the additional resonant choke, which is shown as Lr in the diagram and on the board. What to wind on? It is most correct to wind on a ring made of material -2 or -14, such rings look as follows:

    For winding a resonant choke, it is also allowed to use ferrite rings (green or blue), but always with a gap. The size of the gap is freely selectable. No gap is required for rings made of material -2 and -14. It is necessary to wind the resonant choke with the same wires and the same number of cores as the primary winding of the transformer. The number of turns should be such as to obtain the required inductance value, in our case 44μH. And when the choke (if it was necessary) and the resonant transformer are wound, it is necessary to adjust the inductance of its primary winding to the calculated value. Above, we have already calculated what the total inductance of the primary winding of the transformer should be. If the real leakage inductance coincided with the calculated value of the resonant inductance and an additional resonant inductor was not needed, then the inductance of the primary winding, by selecting the size of the gap in the transformer core, is adjusted to the calculated value:

    That is, it is necessary to gradually increase the gap between the parts of the transformer core until the measured inductance of the primary winding of the transformer becomes equal to our calculated value - 524 μH. But this is only if an additional resonant choke is not used. If an additional inductor is present, then the inductance of this additional inductor must be subtracted from the calculated value of the total inductance of the primary winding. In our case, it turns out 524mkH-44mkH \u003d 480mkH, this is exactly what the inductance of the primary winding of our transformer should turn out to be. The primary inductance is measured with the secondary windings open. After reaching the required value of the inductance of the primary winding of the transformer, the transformer and the resonant choke can be considered ready, and the calculation is over.

    How to make sure that everything worked out, that the resulting SMPS is really a resonator? It is necessary with the help of an oscilloscope to watch the shape of the current through the primary winding of the transformer. To do this, in the presence of an additional resonant choke, a temporary test winding of 2-3 turns of a thin wire is wound around it, loaded onto a 330-750 Ohm resistor, and an oscilloscope is connected to this winding. The current waveform should be sinusoidal or close to sinusoidal (something like the one shown in my oscillograms above). If there is no resonant choke, then a current transformer is temporarily installed in its place. It is a ferrite ring with a winding containing 40-50 turns of a thin wire, loaded on a 330-750 Ohm resistor, to which an oscilloscope is connected and a second winding of one turn, which is turned on in place of a resonant choke.

    A few pictures:




    At the end of the article, I want to thank the IRS27952 microcircuits and other SMD elements provided for the experiments!

    Thanks for your attention!

    List of radioelements

    Designation A type Denomination amount NoteScoreMy notebook
    LLC Resonant SMPS based on IRS27952
    R6 Resistor

    0 ohm

    1 SMD1206 Into notepad
    R4, R11, R13 Resistor

    4.7 Ohm

    3 SMD1206 Into notepad
    R8, R12 Resistor

    22 ohm

    2 SMD1206 Into notepad
    R17 Resistor

    750 Ohm

    1 SMD1206 Into notepad
    R18, R19 Resistor

    24 kΩ

    2 SMD1206 Into notepad
    R1, R2, R3, R5, R9, R15 Resistor

    120 kΩ

    6 SMD1206 Into notepad
    R7, R10, R16 Resistor

    270 k Ohm

    3 SMD1206 Into notepad
    R14 Resistor

    4.7 Ohm

    1 Output, 0.25W Into notepad
    Rfmin Resistor* 1 SMD1206 Into notepad
    Rfss Resistor* 1 SMD1206 Into notepad
    Rfmax Resistor* 1 Output, 0.25W Into notepad
    C2 Film capacitor100 nF1 CL21, 400V Into notepad
    C4, C7 Anti-interference film capacitor100 nF2 X2, 275V Into notepad
    C8 Ceramic capacitor1 nF1 630 / 1000V Into notepad
    C6, C5 Ceramic capacitor100 nF2 SMD1206, 50V Into notepad
    C11, C12, C13, C14, C15, C16 Ceramic capacitor1 μF6 SMD1206, 50V Into notepad
    C3 10 μF1 25V Into notepad
    C1 Electrolytic capacitor220 uF1 400V

    Principle to your attention a device with an efficiency higher than 100%, you will say that this is a fake and everything is not real, but this is not true. The device is assembled on domestic parts. There is one feature in the transformer design, the transformer is W-shaped with a gap in the middle, but there is a neodymium magnet in the gap, which sets the initial impulse to the coil feedback... The take-off coils can be wound in any direction, but at the same time jewelry accuracy is needed in their winding, they must have the same inductance. If this is not observed, then there will be no resonance, a voltmeter connected in parallel to the battery will inform you about this. I did not find a special application in this design, but you can connect a light source in the form of incandescent lamps.

    Technical characteristics at resonance:
    Efficiency above 100%
    Reverse current 163-167 milliamperes (I don't know how this happens, but the battery is charging)
    Consumption current 141 milliamps (it turns out that 20 milliamperes is free energy and goes to charge the battery)

    Red wire coil L1
    Green wire coil L2
    The black wire is the pickup coil

    Customization

    From my own experience, I was convinced that the L1 coil, wound with the same wire, is more easily tuned to resonance with L2, creating more current than is consumed. As I understand it, ferromagnetic resonance is created, which feeds the load and charges the battery with a high current. To adjust the resonance, there must be two identical coils or one; when the device is on, they move under the load of a lamp in the form of incandescent (in my case, a 12 Volt 5 W lamp). To set up, connect a voltmeter in parallel with the battery and start moving the coils (y). At resonance, the battery voltage should start to rise. Upon reaching a certain threshold, the battery will stop charging and discharging. A large radiator must be installed on the transistor. In the case of two coils, everything is more complicated, since it is necessary to wind them so that the inductances practically do not differ, with different loads the location of the right and left coils will change. If you do not follow these tuning rules, then resonance may not occur, and we will get a simple boost converter with high efficiency. The parameters of the coils I have are 1: 3, that is, L1 8 turns, L2 24 turns, both with the same wire section. L1 rolls over L2. Removable coils no matter what wire, but I have 1.5mm.

    Photo

    Ready device in a resonance-free state (coils are connected in series)

    Self-feeding test from a removable coil through a diode. (Result: failure, works 14 seconds with fading)

    Resonance state on one coil without self-supply through the diode. The experiment was successful, with the battery connected, the converter worked for 37 hours and 40 minutes, without loss of voltage on the battery at the beginning of the experiment, the battery voltage was 7.15 volts, by the end of 7.60 volts. This experience has proven that the converter is capable of delivering efficiency above 100%. For the load I used a 12 Volt 5 W incandescent lamp. I refused to try to use other devices, since the magnetic field around the device is very strong and creates interference within a radius of one and a half meters, the radio stops working within a radius of 10 meters.

    List of radioelements

    Designation A type Denomination amount NoteScoreMy notebook
    VT1 Bipolar transistor

    KT819A

    1 KT805 Into notepad
    C1 Capacitor0.1 uF1 Into notepad
    C2 Electrolytic capacitor50 uF 25 v1 Into notepad
    R1 Resistor

    2.2 k Ohm

    1 Into notepad
    R2 Resistor

    62 Ohm

    1 Into notepad
    Bat1 Battery12 Volts1

    This high voltage source was made a long time ago, but I found it on the shelf and decided to describe it. This is almost an ordinary half-bridge (in the network there are huge pile) on the IR2153 except for a few points.

    Firstly, the line transformer here operates at a resonant frequency, which means that it produces a very high voltage. In order for the lineman not to break through, it cannot be turned on without load! I think we need to make a protective spark gap.

    Secondly, “heavy” transistors (stw29nk50, such were) are used quite unusual for such circuits at a fairly high frequency - about 120 kHz. In order to enable the IR2153 to control them, buffers are introduced. In general, the IR2153 is unloaded as soon as possible. External voltage stabilization, external buffers. The life of mikruhi turned into a fairy tale)

    Thirdly, the IR2153 powers itself after launch. The heating of the resistor R4 is greatly reduced, and it can give more current to the gates. Another advantage of this approach is that if you short-circuit the source outputs for a long time, the ir2153 power drops below the UVLO threshold, it turns off, and periodically turns on from the network resistor. Thus, the probability of drift from K.Z. is approximately zero.

    Scheme (clickable)

    The number of turns in the primary is 45, in the IR power winding - 4.

    The transistors are placed on the top of the radiator.

    Assembled circuit

    The writer himself did not want to fit into the case, so I had to file the case a little, and to make it look beautiful, I made a red cap with a big exclamation mark, I didn't have enough talent to draw a lightning bolt))

    Power consumption - 120W, K.Z. withstands load without problems.

    Video

    My brother, it seems, is already used to the fact that I take his camera away in order to shoot vidushniki of my handicrafts. Therefore, behold:

    Why is the arc so dead? When it appears, the half-bridge goes out of resonance, and, because of this, the output power decreases. The power can always be increased by lowering the operating frequency and reducing the number of turns. Fortunately, transistors allow you to do this.