Today, when organizing water heating, induction water heaters have become widespread. This demand is ensured by the fact that the device is completely environmentally friendly, does not dry out or burn through the air. The use of such a device can be implemented for instantaneous heating of water or as a heating boiler. You can buy an induction water heater either in a store or make it yourself. It is worth noting that according to technical specifications it will not be inferior to the model you are buying, although it will not look as attractive, but it costs much less.
Using such a device at home allows you to get maximum performance and operational reliability. In this case, the unit does not need to be accompanied by special documentation and permission for installation, for example, as gas boiler. Using an induction heater as a traditional heating boiler, in some cases the use of a pump will not be required. Coolant movement is achieved by convection processes: When heated, water turns into steam.
It is worth noting that an induction water heater has many advantages that set it apart from its competitors.
- The cost of such a device is insignificant.
- It is possible to assemble the heater yourself.
- Doesn't make any extraneous noise. The coil vibrates quite strongly during operation, but it is practically not noticeable.
- Due to constant vibration, dirt and scale do not have time to attach to functional elements, so the device does not require regular cleaning.
- It contains a heat generator, which is very easily sealed. Water, acting as a coolant, is placed in a heating element, due to which energy is transmitted through a magnetic field. It does not require the use of contacts, and therefore seals and various sealing rubber bands, which tend to fail quickly.
- It rarely breaks, since a simple tube is responsible for heating the water, in which there is simply nothing to break or burn out.
By choosing an induction water heater, the owner receives a device with minimal maintenance, since it consists of a small number of components. And they, in turn, very rarely fail.
Operating principle of an induction boiler
But you can’t do without shortcomings. As with any type of technology, they exist.
- High power consumption, which will result in large electricity bills;
- The device gets very hot, and everything around it becomes hot, so you should not touch the device while it is operating.
- The induction water heater has strong heat dissipation, so installation is necessary temperature sensor to prevent overheating of the device, and, accordingly, explosion.
Types of induction water heaters
All devices of this type, which can be made by hand, can be divided into two groups:
- Vortex heaters inductor type, which are most often used in homes to perform heating functions. It is their manufacturing process that will be discussed below.
- Heaters, the design of which implies the use different types electronic components and parts.
While creating vortex induction heater(or VIN for short) with your own hands, the following structural components should be provided:
- an element responsible for converting electricity into high-frequency current;
- an inductor (most often made in the form of a cylindrical element made of copper wire), which, when used, acts as a transformer responsible for the formation of a magnetic field;
- the element that will play the role of heating is located inside the inductor itself.
The VIN works as follows.
- The high frequency current from the converter is transferred to the inductor.
- In the inductor it is formed a magnetic field, which in turn creates vortex flows.
- Heat exchanger under action vortex flows reaches quickly enough high temperature and, accordingly, heats the coolant, which distributes the heat further.
Diagram of a modern water heater
One of the most important components is the induction coil, the manufacture of which should be treated with special care. Copper wire is very carefully wound onto a plastic pipe, and the number of coils should not be less than 100.
From the description presented, we can conclude that making an induction water heater yourself is not difficult.
Manufacturing Features
You can make your own induction heater in two ways. It is worth considering each of them briefly.
Option 1
The simplest device (and it will have high power) can be made based on printed circuit . Among the features of the circuit that will be used in the device, the following points should be highlighted:
- the entire design is, in fact, represented by a multivibrator with high power organization;
- special attention should be paid to resistance, since it is this that will prevent overheating of the transistors;
- the inductor in such a device should be made in the form of a spiral of 6-8 turns of copper wire;
- As a regulator, you can use the corresponding element from the computer power supply and not think about its contraction.
Vortex Induction Heater
Option 2
The basis for making such a device with your own hands is the use of electronic transformer.
The essence of this method of manufacturing an induction water heater is as follows.
- Two pipes should be connected using welding so that they visually resemble a donut. This element will subsequently play the role of both a heating element and a conductor.
- You will need to wind copper wire around the body.
- To ensure high-quality and fast movement of water, 2 pipes are welded into the main body. Water will flow into one of them, and from the second it will flow out into the system itself.
That's all the advice on how to assemble such a heating device with your own hands and provide it in the house high-quality heating and the constant presence of hot water.
Craftsmen have come up with many ways to heat a house. One of them is an induction heater. Like any other, it has its advantages and disadvantages.
Operating principle
The work is based on the Joule-Lenz law, which reflects the direct dependence of the thermal output of the conductor on the voltage electric field. Everyone knows the relationship between magnetism and electricity, which simply cannot exist without the other. If current is applied to the coil high frequency, a magnetic field is formed around it. Its flow will penetrate the conductive core inserted into the coil. The resulting magnetic induction will constantly change in direction and time, which will cause the appearance of eddy currents moving in a vicious circle. And this converts electromagnetic energy into thermal energy. Such is the general outline induction heater diagram.
Induction heaters have proven themselves brilliantly in a wide range of applications. With their help you can carry out surface hardening metal products, ultra-clean, non-contact welding, spot heating and even melting of conductive materials. Industrial inductors are equipped with a powerful transformer capable of supplying large currents to them.
Inductor in everyday life
Since the circuit of such a heater is not complicated, and the efficiency of such a device is very high (up to 98%), the vortex induction heater could not but interest craftsmen.
Very often, many people have the idea of using the induction principle to heat their home. After all, an induction heater is capable of heating water almost instantly. Therefore, there are a number of designs that represent a homemade induction heater.
There are many laws in physics that you can never get around. Energy is not taken from nowhere, and therefore the amount of electricity consumed cannot be less than the thermal energy required.
In other words, if it takes 5 kW/h to heat a room, it will not be possible to do so using only 2 kW/h of electricity, no matter how great the heater design is. If you plan to heat using an inductor, you need to be prepared to increase your electricity bills.
The most popular option among craftsmen is an induction heater made of welding inverter. There are a number of reasons for this:
- The inverter produces current at higher frequencies, which significantly increases the electric field strength, and this has a beneficial effect on heat transfer.
- The welding inverter is capable of supplying high currents. Of all the devices available for household use, the inverter is best suited for use as an induction heater power supply.
Design elements
A do-it-yourself induction heater is made as follows:
- Piece plastic pipe with a wall thickness of at least 3 mm, it is filled with pieces of metal wire. Their length is approximately 5 cm.
- Both edges of this piece of pipe are covered with a metal mesh to hold these pieces in place. The pipe must be completely filled with wire.
- After this, it should be carefully wrapped in thick copper wire- about 90 turns. It is advisable to choose a wire with a diameter of at least 3 mm.
- Using adapters and fittings, the pipe is connected to the heating system, which is then filled with water.
- The ends of the wire are connected to the terminals of the welding inverter.
- It is necessary to ensure compliance with all fire and electrical safety measures.
After turning on the device, the metal pieces of wire will instantly heat up and begin to give off heat to the water passing through them.
It is especially worth emphasizing that the water must circulate continuously.
Otherwise, the temperature of the pipe will rise so much that there is a risk of it melting.
This is one of the most serious disadvantages of such heaters. In case of frequent absence of owners, a system of automatic computer control over the operation of the heater is necessary.
An induction heater is quite suitable for heating, but it has its drawbacks. They are completely fixable with proper attention to detail. this design able to compete with others.
Due to the constant increase in prices for traditional energy resources, country property owners are looking for new options for heating their homes. One of economical options Many people consider induction heaters to be water-based. With the help of this equipment, according to some homeowners, it is possible to heat large rooms. There is enough equipment of this type on sale. high cost. But you can make an induction heater with your own hands if you have some skills similar works. And ready-made diagrams and detailed video process will help the craftsman navigate the stages of work and make his work a little easier.
Working principle of induction heater
Before assembling an induction heater yourself, you must first familiarize yourself with general principle operation of this type of equipment. Such units are in many ways similar to equipment that is equipped with heating elements. They also convert electricity into heat, which is necessary to heat the premises of the house.
The device is heated using electrical energy. magnetic field, created in the inductor. It is a coil in the form of a cylinder with a winding. Electricity passing through this coil creates voltage. As a result of the action alternating current vortex flows are formed. Then the energy of the electromagnetic field is taken up by the coolant, which is water. This energy is then generated into heat. In a short time, water with such heating reaches fairly high temperatures.
Induction heater circuit
Induction water heater components
The simplest device for generating heat based on vortex flows is an electrical inductor, which consists of several windings:
- primary;
- secondary.
The primary winding converts electrical energy into eddy currents and then sends a magnetic field to the secondary winding. Next, the created electromagnetic energy is transferred to the coolant, heating it. The secondary winding is both a heating element and the body of an induction boiler. It consists of:
- external winding;
- core;
- electrical insulation;
- thermal insulation.
Induction heater operation
For admission cold water Two pipes are installed into the unit and the hot outlet into the heating system. A pump is built in to circulate the liquid. Overheating of water during operation heating system does not happen, since the liquid constantly circulates - it is supplied cold and hot is discharged. Such water heaters can be installed for heating in almost any room. Due to the design features of the system, weight and dimensions are reduced heating element, and heat transfer increases significantly. The coolant ultimately receives about 97-98% of the energy without significant losses.
Attention! To install an induction heater, there is no need to do any major redesign of the heating system; this unit is simply built into it.
Advantages of induction type units
The undoubted advantages of this type of home heating devices include the following characteristics:
- economical - recycling electrical energy heat transfer occurs almost completely without significant losses;
- ease of use - constant Maintenance units of this type not required;
- compact dimensions - induction water heaters are small in size, they can be installed in the heating system in almost any room;
- quiet operation – this equipment operates quite quietly, no noise occurs during its operation;
- long service life - induction units are durable and can operate smoothly for 30 years or more;
- high environmental friendliness - no harmful emissions occur during operation of the device, a chimney installation and a ventilation system are not required.
Many people believe that induction boilers much more profitable than other home heating options. And compared to equipment equipped with heating elements, the heating time of these units occurs almost twice as fast. Due to the constant circulation and vibration of the liquid, scale does not form in the pipes and inside the device, which greatly facilitates the maintenance and care of the heating system.
Appearance of induction boilers
But this type of device also has some disadvantages. And the main disadvantage is that induction equipment is quite expensive. But you can try to make such a heater for heating your home yourself.
Advice. If you have certain skills and technical knowledge, you can assemble an induction heater for your home with your own hands. But before you begin the process of assembling the device, you must first really evaluate your capabilities and experience in creating such units, since making them is not so easy.
How to assemble an induction heater yourself
The modern market provides enough big choice various models induction type equipment. But in order to save money, you can make such a device yourself. Of course, having decided to make this heater, you need to prepare the appropriate tools for the job and stock up on necessary materials, many of which the owner may already have.
To make a simple heater design, you need to take the following components:
- a piece of plastic pipe with fairly thick walls - this will be used to make the body of the device;
- mesh (metal);
- copper wire;
- wire from of stainless steel with a diameter of up to 7 mm or wire rod.
Homemade induction boiler
To install the heater into the heating system, you will also need a built-in circulation pump and adapters for connecting the device, as well as welding machine and necessary tools.
Induction heater assembly
Work on the manufacture of the heater is carried out in several stages:
- Cut the stainless steel wire into pieces approximately 5-7 mm long. Place a plastic pipe at the bottom metal mesh and fill all the free space inside with cut pieces of wire. Then close the pipe on both sides.
- Next you need to make an induction coil. To do this, carefully wrap the prepared pipe with copper wire at regular intervals. You should get at least 90-100 turns of wire.
- The prepared device can be built anywhere in the heating system. The device is connected to the inverter with an external winding made of copper wire. A circulating pump is built in to pump water. It is imperative to carry out electrical insulation work on the device. Do not forget about the thermal insulation of the heater special material. Without thermal insulation, the efficiency of the system will be significantly lower.
The cost of a homemade induction boiler is quite small. But still, to manufacture it, you need experience in such work, as well as at least a little technical knowledge in this field. If all work is carried out carefully and in accordance with the recommendations, such a device will operate smoothly, with good heat dissipation. It is possible that it will turn out to be somewhat unsightly in appearance, but this will not make the heater function worse.
DIY induction heating: video
Induction water heater: photo
Homemade induction heater 4 kW.
Imagine this trick. A man picks up an iron nail and inserts it into a copper loop - an inductor. The nail immediately becomes white hot.
The secret trick is induction heating. An ancient technology, first developed by the Russian electrical engineer Vologdin in 1880, and, unfortunately, still not widespread among home craftsmen.
The copper loop - the inductor - is passed through electricity great strength(hundreds of amperes) and high frequency (tens - hundreds of kHz). As a result, Foucault currents, also of high strength and frequency, are induced in the metal workpiece standing inside or next to the inductor. The high-frequency current in the workpiece under the influence of the skin effect is forced into thin surface layers, as a result of which its density increases sharply. The workpiece layer, through which large currents flow, begins to quickly heat up. The temperature can reach several thousand degrees, which allows you to melt metal at home, invent and create your own unusual alloys; weld and solder metal parts; harden screwdrivers, drills, knives, etc., use the installation in forges and repair shops.
Induction heating allows you to heat electrically conductive materials (any metal, graphite, electrically conductive ceramics) without contact. Directly through the air, through a layer of water, through a glass, wooden or plastic wall, in vacuum chamber or in a chamber with protective gas. At the same time, the workpiece remains perfectly clean, since it does not oxidize in the gas stream, does not touch the dirty surface of the stove, etc.
_________________________________________________________________________
The inverter of Sergei Vladimirovich Kukhtetsky was taken as a basis, developed th at the Institute of Chemistry. Inverter circuit, its detailed description and assembly recommendations are published at: www.icct.ruThe circuit uses modern electronic components, which allows you to assemble a powerful and reliable inverter at home for a low price of about a few thousand rubles (prices for industrial analogues reach tens and hundreds of thousands of rubles).
On the forum induction.listbb.ru jointly with forum members Derba, Phoenix, Jab, Fulyugan, Ostap, -CE- was carried out until operation of the circuit, an additional PLL phase-locked loop board was installed to automatically maintain resonance, high-speed protection against overcurrent was installed (both in case of excess power supply and as a result of breakdown of power mosfets due to their overheating or failure of the control module). Some details have been added to reduce the likelihood of mosfets overheating and control module failure (leading to the appearance of through currents in the power bridge).
Inverter power consumption depending on the inductors used: 1...4 kW.
Current frequency in the inductor: 300 kHz.
Current strength in the inductor: ~400A.
The maximum current consumed from the network with a two-turn inductor is 20A, the consumed voltage is 220V.
The induction heater is equipped with protection that turns off the circuit when the supply voltage is exceeded, when short circuit inductor, when filling the inductor with water.
See diagrams and discussion of improvements on the forum:
induction.listbb.ru and
Video - melting low carbon steel (nuts) in air:
Video - melting high-carbon steel (a ball from a bearing made of ShKh-15 steel):
Video - melting low-carbon steel in protective gas (argon):
Video - heating a steel ball through a layer of water. The possibility of heating a piece of iron through a layer of water is interesting, water electromagnetic field no problem
A powerful high-frequency electromagnetic field pushes iron blanks out of the inductor. On the one hand, this creates problems - it is difficult to heat small workpieces, they are carried away from the inductor and have to be secured somehow (the so-called electromagnetic blast effect).
On the other hand, it is possible to melt metal in a suspended state - (levitation melting, melting in an electromagnetic crucible):
Modification of the inverter for induction heating.
The method of non-contact heating of liquid metal samples with high frequency currents in a vacuum or protective gas is optimal for experiments with small samples of electrically conductive materials.
Industrial high-frequency inverters do not have the characteristics necessary for the experiment ( high power at a high frequency necessary for heating small samples), and therefore was manufactured homemade inverter. The inverter developed by Sergei Kukhtetsky at the Institute of Chemistry and Chemical Technology of the Russian Academy of Sciences was taken as the basis, working as follows.
The inductor for heating the samples, which is an oscillating circuit coil together with a compensating bank of capacitors, is pumped from an independently operating high-frequency generator.
The generator is made according to a full bridge circuit; its frequency is automatically adjusted to the natural frequency of the oscillatory circuit manually and cannot be changed during operation. The proposed inverter does not have a circuit for protecting power transistors from through currents and a heating power control circuit (Fig. 1).
Fig.1. Block diagram of a simple inverter for induction heating.
Operation of this simple inverter revealed the following problems. As a result of heating the sample, as well as as a result of the movement of the sample in the inductor, a change occurs in the inductance that is part of the oscillatory circuit and a change in its natural frequency. Since the operating frequency of the inverter is set by the generator with a frequency that does not change during operation, a mismatch between the frequencies of the oscillatory circuit and the generator leads to a sharp drop in heating power, vibrations of the workpiece in the inductor, as well as power transistors entering a non-optimal operating mode in capacitive mode, which leads to their failure building.
To solve these problems, the inverter was retrofitted with a PLL phase-locked loop circuit, a high-speed protection circuit for power transistors from overcurrent, and a switching power regulator controlled from a PC. Protection and power control circuits are designed as separate modules and can be used for other tasks.
The PLL circuit consists of a variable frequency oscillator, a current sensor, a voltage sensor, an adjustable delay line, and a control pulse shaper for the power bridge. Current and voltage sensors measure the corresponding values on the oscillating circuit, after which their phases are compared. Zero phase shift means synchronous operation of the oscillatory circuit at its own frequency and the master oscillator. In the event of a phase shift, the master oscillator automatically adjusts the frequency, adjusting it to the natural frequency of the oscillatory circuit (Fig. 2). Electrical diagram of the modified inverter is shown in Fig. 5.
Setting the PLL tracking range, procedure:
It is necessary to determine the natural frequency of the oscillatory circuit, for example, as follows.
1) Remove the matching transformer from the busbars of the oscillatory circuit.
2) Connect an oscilloscope to the buses connecting the inductor to the capacitor bank.
3) Set the oscilloscope to standby mode (single measurement Trigger mode).
4) Briefly touch the busbars of the oscillating circuit with a crown battery. “Bounce” will appear on the screen - the circuit’s own vibrations. If necessary, carry out this procedure several times to obtain a stable picture on the oscilloscope screen.
The period of natural oscillations is measured using the oscilloscope grid, then using the formula f = 1/period, the natural frequency of the oscillatory circuit is calculated.
The PLL operating range is configured as follows.
1) An oscilloscope is connected to the output of the CD4046 PLL oscillator chip.
2) Set the minimum operating frequency of the CD4046 generator. To do this, connect the plus of the 1-volt power supply to pin 9 of the CD4046 microcircuit, and connect the minus of the power supply to the common bus.
3) Set the minimum frequency by rotating the potentiometer on pin 12 of the cd4046 microcircuit to 30 kHz below the natural frequency of the oscillatory circuit (selected experimentally for reliable PLL pickup).
4) Set the maximum operating frequency of the CD4046 generator. To do this, connect the plus of the 4.5 volt power supply to pin 9 of the CD4046 microcircuit, and connect the minus of the power supply to the common bus.
5) By rotating the potentiometer on leg 11 of the CD4046 microcircuit, set the frequency 30 kHz higher than its own.
As a result of the operations performed, the inverter automatically starts picking up the resonance and maintains it during operation.
Fig.2. Block diagram of an induction heating inverter with PLL.
The protection module consists of a current sensor mounted on a shunt, an overcurrent detection circuit with an adjustable response threshold, and a power shutdown circuit. Power is supplied to the inverter through a shunt. At the moment the current exceeds the shunt, an excess voltage drop is detected, which leads to the flip-flopping of the trigger and the supply of a turn-off signal to the power transistor (Fig. 3). The electrical diagram of the protection module is shown in Fig. 6.
Fig.3. Block diagram of the high-speed protection module.
Video - activation of the high-speed protection module:
The switching power regulator is made according to the circuit of a step-down PWM converter. Power regulation is carried out by changing the duty cycle of the control PWM signal. The control signal is generated by the STM32F767 microcontroller (a ready-made debug board with a built-in USB programmer). Power control parameters are set from a computer via the USB interface included in any PC, this decision allows you to synchronize data collection and control of the experimental setup (the block diagram is shown in Fig. 4).
Fig.4. Block diagram of a switching power regulator.
The microcontroller program provides both manual (pedal, encoder knob) and remote control power regulator (using a PC), smooth start and stop, stabilization of output power by current or voltage, indication of device operation. The electrical circuit of the pulse power regulator is shown in Fig. 7.
Fig.5. Inverter circuit for induction heating of samples with phase-locked loop.
Fig.6. Electrical circuit of a universal high-speed current breaker for protecting an induction heating installation.
Fig.7. Electrical circuit of a universal pulse power regulator.
When a person is faced with the need to heat a metal object, fire always comes to mind. Fire is an old-fashioned, inefficient and slow way to heat metal. It spends the lion's share of energy on heat, and smoke always comes from the fire. How great it would be if all these problems could be avoided.
Today I will show you how to assemble an induction heater with your own hands with a ZVS driver. This device heats most metals using a ZVS driver and the power of electromagnetism. Such a heater is highly efficient, does not produce smoke, and heating such small metal products as, say, a paper clip is a matter of a few seconds. The video shows the heater in action, but the instructions are different.
Step 1: Operating principle
Many of you are now wondering – what is this ZVS driver? This is a highly efficient transformer capable of creating a powerful electromagnetic field that heats the metal, the basis of our heater.
To make it clear how our device works, I will talk about key points. First important point— 24 V power supply. The voltage should be 24 V with a maximum current of 10 A. I will have two lead acid batteries connected in series. They power the ZVS driver board. The transformer supplies a steady current to the coil, inside which the object to be heated is placed. Constantly changing the direction of the current creates an alternating magnetic field. It creates eddy currents inside the metal, mainly of high frequency. Due to these currents and the low resistance of the metal, heat is generated. According to Ohm's law, the current strength transformed into heat in a circuit with active resistance will be P=I^2*R.
The metal that makes up the object you want to heat is very important. Iron-based alloys have higher magnetic permeability and can use more magnetic field energy. Because of this, they heat up faster. Aluminum has low magnetic permeability and therefore takes longer to heat up. And objects with high resistance and low magnetic permeability, such as a finger, will not heat up at all. The resistance of the material is very important. The higher the resistance, the weaker the current will pass through the material, and the correspondingly less heat will be generated. The lower the resistance, the stronger the current will be, and according to Ohm's law, the less voltage loss. It's a little complicated, but due to the relationship between resistance and power output, maximum power output is achieved when resistance is 0.
The ZVS transformer is the most complex part of the device, I will explain how it works. When the current is turned on, it flows through two induction chokes to both ends of the coil. Chokes are needed to ensure that the device does not produce too much current. Next, the current flows through 2 470 Ohm resistors to the gates of the MOS transistors.
Due to the fact that there are no ideal components, one transistor will turn on before the other. When this happens, it takes over all the incoming current from the second transistor. He will also short the second one to the ground. Because of this, not only will current flow through the coil to the ground, but also through the fast diode the gate of the second transistor will discharge, thereby blocking it. Due to the fact that a capacitor is connected in parallel to the coil, an oscillatory circuit is created. Due to the resulting resonance, the current will change its direction and the voltage will drop to 0V. At this moment, the gate of the first transistor discharges through the diode to the gate of the second transistor, blocking it. This cycle repeats thousands of times per second.
The 10K resistor is supposed to reduce excess gate charge on the transistor by acting as a capacitor, and the Zener diode is supposed to keep the transistors' gate voltage at 12V or lower to keep them from blowing up. This transformer is a high frequency voltage converter that allows metal objects to heat up.
It's time to assemble the heater.
Step 2: Materials
To assemble a heater, you need few materials, and most of them, fortunately, can be found for free. If you saw somewhere lying around just like that cathode ray tube, go and pick her up. It contains most of the parts needed for the heater. If you want more quality parts, buy them at an electrical parts store.
You will need:
Step 3: Tools
For this project you will need:
Step 4: Cooling the FETs
In this device, the transistors turn off at a voltage of 0 V and do not heat up very much. But if you want the heater to run longer than one minute, you need to remove heat from the transistors. I made one common heat sink for both transistors. Make sure that the metal gates do not touch the absorber, otherwise the MOS transistors will short out and explode. I used a computer heatsink and it already had a stripe on it silicone sealant. To check the insulation, touch the middle leg of each MOS transistor (gate) with a multimeter; if the multimeter beeps, then the transistors are not isolated.
Step 5: Capacitor Bank
Capacitors become very hot due to the current constantly passing through them. Our heater needs a capacitor value of 0.47 µF. Therefore, we need to combine all the capacitors into a block, this way we will get the required capacitance and the heat dissipation area will increase. The capacitor voltage rating must be higher than 400 V to account for inductive voltage peaks in the resonant circuit. I made two rings of copper wire, to which I soldered 10 0.047 uF capacitors in parallel to each other. Thus, I received a capacitor bank with a total capacity of 0.47 µF with excellent air cooling. I will install it parallel to the working spiral.
Step 6: Working Spiral
This is the part of the device in which the magnetic field is created. The spiral is made of copper wire - it is very important that copper is used. At first I used a steel coil for heating, and the device did not work very well. Without workload it consumed 14 A! For comparison, after replacing the coil with a copper one, the device began to consume only 3 A. I think that eddy currents arose in the steel coil due to the iron content, and it was also subjected to induction heating. I'm not sure if this is the reason, but this explanation seems to me the most logical.
For the spiral, take copper wire large section and make 9 turns on a piece of PVC pipe.
Step 7: Chain Assembly
I did a lot of trial and error until I got the chain right. The biggest difficulties were with the power source and the coil. I took a 55A 12V switching power supply. I think this power supply supplied too high an initial current to the ZVS driver, causing the MOS transistors to explode. Perhaps additional inductors would have fixed this, but I decided to simply replace the power supply with lead-acid batteries.
Then I struggled with the reel. As I already said, the steel coil was not suitable. Due to the high current consumption of the steel coil, several more transistors exploded. In total, 6 transistors exploded. Well, they learn from mistakes.
I have rebuilt the heater many times, but here I will tell you how I assembled the best version of it.
Step 8: Assembling the device
To assemble the ZVS driver, you need to follow the attached diagram. First I took a Zener diode and connected it to a 10K resistor. This pair of parts can be immediately soldered between the drain and source of the MOS transistor. Make sure the Zener diode is facing the drain. Then solder the MOS transistors to the breadboard with contact holes. On bottom side of the breadboard, solder two fast diodes between the gate and drain of each transistor.
Make sure the white line is facing the shutter (Fig. 2). Then connect the positive from your power supply to the drains of both transistors through a 2,220 ohm resistor. Ground both sources. Solder the working coil and the capacitor bank parallel to each other, then solder each end to a different gate. Finally, apply current to the gates of the transistors through 2 50 μH inductors. They may have a toroidal core with 10 turns of wire. Your circuit is now ready to use.
Step 9: Mounting to Base
In order for all the parts of your induction heater to hold together, they need a base. I took it for this wooden block A 5*10 cm board with an electrical circuit, a capacitor bank and a working coil were glued with hot melt adhesive. I think the unit looks cool.
Step 10: Functionality Check
To turn your heater on, simply connect it to a power source. Then place the item you need to heat in the middle of the working coil. It should start to warm up. My heater heated the paperclip to a red glow in 10 seconds. Objects larger than nails took about 30 seconds to heat up. During the heating process, the current consumption increased by approximately 2 A. This heater can be used for more than just entertainment.
After use, the device does not produce soot or smoke, it even affects isolated metal objects, for example, gas absorbers in vacuum tubes. The device is also safe for humans - nothing will happen to your finger if you place it in the center of the working spiral. However, you can get burned by an object that has been heated.
Thank you for reading!