Now we will learn how to make a DIY induction heater that can be used for various projects or just for fun. You can instantly melt steel, aluminum or copper. You can use it for soldering, melting and forging metals. You can use a homemade inductive heater for casting as well.
My tutorial covers the theory, components, and assembly of some of the critical components.
The instructions are large and will cover the basic steps to give you an idea of what goes into a project like this and how to design it without anything exploding.
For the furnace, I built a very accurate, inexpensive cryogenic digital thermometer. By the way, in tests with liquid nitrogen it performed well against branded thermometers.
A few words about safety
Homemade induction boilers are usually not equipped with control and protection systems, which makes them unsafe. Therefore, before turning on the unit, you must make sure that the housing cavity is filled with coolant liquid.
If the polymer body of the heater is subjected to constant heating without being washed with coolant, it will simply melt, sometimes this leads not only to deformation of the heater, but also to its complete damage.
Units of this type are often used for heating and melting metals. The high temperatures generated by an induction heater require careful attention to safety issues
The loss of hot metal filler from the melted body can also be dangerous. In this case, you will have to almost completely dismantle the device and make a new heating element for it.
The connection to the power supply should be made via a separate cable from the panel. Of course, it is necessary to carefully cover all contacts with insulation. The inverter of the welding machine must also be grounded; this is an important point to ensure safety.
In this case, you will need a cable with a cross-section of at least four millimeters. Some experts recommend giving preference to a six-millimeter cable. To prevent overheating of a homemade induction heater due to a lack of water in the system, it is recommended to install an overpressure valve at the inlet of the heater.
An induction heating device takes up relatively little space, but it must be placed at a certain distance from the ceiling, walls, furniture, etc.
A homemade device of this type, not equipped with special protective equipment, is a potentially dangerous object that requires constant monitoring. Therefore, it is worth spending a little more money but purchasing the necessary devices.
At the same time, it doesn’t hurt to estimate the costs; perhaps purchasing a ready-made induction boiler will not cost much more. Industrial devices are usually equipped with all the necessary protection.
Features and step-by-step manufacturing technology of another version of a homemade induction boiler for a heating system are given here.
DIY heater
Sometimes an induction water heater is not suitable for heating; in this case, you can use other heating methods. A popular quick way to heat a room is a heater or duct heater.
To make a heater you will need:
- Several sheets of stainless metal for the body of the device.
- Copper pipe (should be approximately half an inch in diameter) used in the heat exchanger.
- Duct fan powered from a household network.
- Two end valves with couplings or flange connections to integrate the heat exchanger into the space heating system.
- Several springs (usually four are enough) to secure the fan. It is recommended to fasten with springs rather than magnets, for example, because... springs ensure quiet operation.
The process of creating a heater is divided into parts. The first part is marking. On the prepared sheet of metal, you need to mark the dimensions of the body (you will get a marked strip) and the fold lines of the strip. The second part is making the body. The marked strip is cut from the sheet, folded and secured at opposite ends. The front side of the device is made of galvanized sheet; holes are drilled on the front side for air circulation.
The third part is creating a heat exchanger. The copper pipe is closed on one side with a plug, then sand is poured into the pipe and the pipe is bent. After bending, you can get rid of the sand. The fourth part is connecting the heat exchanger. Two holes are made on the side of the heat exchanger for a copper pipe, threads for couplings are made at the ends of the pipe, and a Mayevsky tap is soldered into the upper point of the heating element. Then the heat exchanger is inserted into the housing and screwed with nuts. The fifth part is installing the fan. Holes are drilled in the corners of the case, springs are fixed in them, the fan is placed in the case so that the springs are spaced apart at an equal distance. The sixth part is installing the device. The heater is connected to the heating system using couplings and taps. The heater is placed on the wall, with a gap of 10 cm between the wall and the device. You can make a water heating element with electricity yourself.
Work principles
To assemble an induction boiler with your own hands, you need to study what it consists of and understand the principles of its operation.
The device heats up due to the energy of the electromagnetic field. The coolant takes it over itself and converts it into heat.
The magnetic field is created in an inductor (this is a cylindrical coil with a large number of turns). As electricity passes through it, it creates a voltage around itself. The magnetic flux moves in a closed circle perpendicular to the electric field. Alternating current creates eddy currents and generates energy into heat. Electricity is transferred to the heater without direct contact.
Induction heat is consumed efficiently and economically, so water with this heating method reaches high temperatures in a short period of time. The coolant receives about 97% of the energy.
Induction water heater components
Organizing a heating system in your own home using an induction boiler will not require major redevelopment. It is based on a transformer consisting of primary and secondary windings.
Vortex flows are formed in the primary winding from electrical energy and create an electromagnetic field. It goes to the secondary, which functions as a heater.
This component generates heat and transfers it to the water in the home's heating system.
The secondary winding is the boiler body. It includes elements such as:
- external winding;
- core;
- electrical insulation;
- thermal insulation.
To supply cold water to the device and remove warm water to the heating system, two pipes are installed to the water heater. The lower one is mounted on the inlet section, and the upper one on the hot water outlet part.
The heat created by the boiler is transferred to the coolant. Most often it is water, since it can quickly absorb heat. Due to the built-in pump, hot water enters the heating system through the pipe. The liquid constantly circulates, so overheating of the equipment is not possible. Cooled water is supplied and hot water is discharged.
When circulating, the heating fluid vibrates, which prevents scale from depositing inside the pipes. An induction water heater can be installed in any room, since no noise is created during operation.
Description
A typical heating element includes the following components:
- A heating element in the form of a rod or metal tube.
- An inductor is a copper wire that frames a coil in turns. During operation, it acts as a generator.
- Alternator. A separate design where standard current is converted into a high frequency value.
In practice, induction units have been used recently. Theoretical studies are much ahead. This can be explained by one obstacle - obtaining high frequency magnetic fields. The fact is that using low-frequency settings is considered ineffective. As soon as high-frequency current generators appeared, the problem was solved.
HDTV generators have passed their evolutionary period; from lamp ones to modern models based on IGBT. Now they are more efficient, lighter in weight and smaller in size. Their frequency limitation is 100 kHz due to dynamic losses of transistors.
What to make a storage tank from
Before making a water heater, you need to decide on the design features of the future boiler. Most often, this is a storage tank with a heating element installed inside it, which is responsible for heating the water.
For a storage tank, it is better to choose containers made of corrosion-resistant metal. The most suitable options: stainless or enameled steel, high-quality plastic, aluminum. You can also use iron tanks, but they will have to be pre-treated with a special protective compound that minimizes the formation of rust. Otherwise, the water passing through such a heating device may not be suitable for domestic needs.
For homemade storage water heaters, a variety of containers are used; a gas cylinder can be noted as an example. This is a fairly convenient tank in size, shape and strength.
1600 Watt simple induction heater circuit
The presented scheme should be considered rather as an experimental option. However, this option is quite workable. The main advantages of the scheme:
- relative simplicity,
- availability of parts,
- ease of assembly.
The induction heater circuit (picture below) operates on the “double half-bridge” principle, supplemented by four insulated gate power transistors from the IGBT series (STGW30NC60W). The transistors are controlled by the IR2153 chip (self-clocked half-bridge driver).
A schematically presented simplified low-power induction heater, the design of which allows for use in private households
A double half-bridge can provide the same power as a full bridge, but a clocked half-bridge gate driver is simpler to design and therefore easier to use. Powerful dual diode type STTH200L06TV1 (2x 120A) works as an antiparallel diode circuit.
Much lower power diodes (30A) will be quite sufficient. If you intend to use IGBT series transistors with built-in diodes (for example, STGW30NC60WD), this option can be abandoned.
The operating frequency of the resonance is adjusted using a potentiometer. The presence of resonance is determined by the highest brightness of the LEDs.
Electronic components of a simple do-it-yourself induction heater: 1 - Powerful double diode type STTH200L06TV1; 2 – transistor with built-in diodes type STGW30NC60WD
Of course, there is always the possibility of building a more complex driver. In general, the optimal solution seems to be to use automatic tuning. This is usually used in the circuits of professional induction heaters, but the current circuit, in the case of such modernization, clearly loses the simplicity factor.
Frequency adjustment, inductor, power
The induction heater circuit provides for frequency adjustment in the range of approximately 110 - 210 kHz. However, the control circuit requires an auxiliary voltage of 14-15V, obtained from a small adapter (the switch allows a switched version or a regular one).
The output of the induction heater circuit is connected to the operating circuit of the coil through matching inductor L1 and an isolating transformer. The choke has 4 turns of wire on a core with a diameter of 23 cm, the insulating transformer consists of 12 turns of two-core cable wound on a core with a diameter of 14 cm.
The output power of an induction heater with the specified parameters is about 1600 W. Meanwhile, the possibility of increasing power to higher values is not excluded.
Experimental design of an induction heater, made with your own hands at home. The efficiency of the device is quite high, despite the low power
The working coil of the induction heater is made of wire with a diameter of 3.3 mm. The best material for the coil seems to be a copper pipe, for which it is possible to use a simple water cooling system. The inductor has:
- 6 turns of winding,
- diameter 24 mm,
- height 23 mm.
For this element of the circuit, a characteristic phenomenon seems to be significant heating as the installation operates in active mode. This point should be taken into account when choosing material for manufacturing.
Resonant Capacitor Module
The resonant capacitor is made in the form of a battery of small capacitors (the module is assembled from 23 small capacitors). The total battery capacity is 2.3 μF. The design allows the use of capacitors with a capacity of 100 nF (~ 275V, MKP polypropylene, class X2).
This type of capacitor is not intended for purposes such as use in an induction heater circuit. However, as practice has shown, the noted type of capacitor elements is quite satisfactory for operating at a resonant frequency of 160 kHz. It is recommended to use an EMI filter.
Electromagnetic radiation filter. Approximately this is recommended for use in the design of an induction heater in order to minimize interference
The adjustable transformer can be replaced with a “soft” start circuit. For example, we can recommend using a simple current limiter circuit:
- heaters,
- halogen lamps,
- other devices,
with a power of about 1 kW, connected in series with the induction heater when first turned on.
Safety Warning
When making an induction heater according to the presented circuit, you should remember: the circuit of the induction heating circuit is connected to the electrical network and is under high voltage. It is highly recommended to use an insulated stem potentiometer in the design.
High-frequency electromagnetic fields carry harmful potential that can damage electronic devices and storage media. The presented circuit, given the simplicity of implementation, carries significant electromagnetic interference. This factor can lead to various emergency consequences:
- electric shock,
- burns,
- fires.
Therefore, before deciding to build and experiment with an induction heater, complete safety for the end user and others should be ensured.
Video: induction heater using a welding inverter
The video presented above is a demonstration of the functionality of the device for heating metal. This device was made by converting a welding inverter, and as the author notes, it works quite effectively:
Advantages and disadvantages of the device
There are a lot of “advantages” of a vortex induction heater. This is a simple circuit for self-production, increased reliability, high efficiency, relatively low energy costs, long service life, low probability of breakdowns, etc.
The productivity of the device can be significant; units of this type are successfully used in the metallurgical industry. In terms of heating rate of the coolant, devices of this type confidently compete with traditional electric boilers; the water temperature in the system quickly reaches the required level.
During operation of the induction boiler, the heater vibrates slightly. This vibration shakes off limescale and other possible contaminants from the walls of the metal pipe, so such a device rarely needs to be cleaned. Of course, the heating system should be protected from these contaminants using a mechanical filter.
An induction coil heats the metal (pipe or pieces of wire) placed inside it using high frequency eddy currents, no contact required
Constant contact with water minimizes the likelihood of the heater burning out, which is a fairly common problem for traditional boilers with heating elements. Despite the vibration, the boiler operates extremely quietly; additional sound insulation at the installation site is not required.
Another good thing about induction boilers is that they almost never leak, unless the system is installed correctly. This is a very valuable quality for electric heating, as it eliminates or significantly reduces the likelihood of dangerous situations occurring.
The absence of leaks is due to the non-contact method of transferring thermal energy to the heater. Using the technology described above, the coolant can be heated almost to a vapor state.
This provides sufficient thermal convection to encourage efficient movement of coolant through the pipes. In most cases, the heating system will not have to be equipped with a circulation pump, although it all depends on the features and design of the specific heating system.
Sometimes a circulation pump is necessary. Installing the device is relatively easy. Although this will require some skills in installing electrical appliances and heating pipes. But this convenient and reliable device has a number of disadvantages that should also be taken into account.
For example, a boiler heats not only the coolant, but also the entire working space surrounding it. It is necessary to allocate a separate room for such a unit and remove all foreign objects from it. For a person, staying in close proximity to a working boiler for a long time can also be unsafe.
Induction heaters require electric current to operate. Both homemade and factory-made equipment are connected to a household AC network
The device requires electricity to operate. In areas where there is no free access to this benefit of civilization, an induction boiler will be useless. And even where there are frequent power outages, it will demonstrate low efficiency. If the device is handled carelessly, an explosion may occur.
If you overheat the coolant, it will turn into steam. As a result, the pressure in the system will increase sharply, which the pipes simply cannot withstand and will burst. Therefore, for normal operation of the system, the device should be equipped with at least a pressure gauge, and even better - an emergency shutdown device, a thermostat, etc.
All this can significantly increase the cost of a homemade induction boiler. Although the device is considered virtually silent, this is not always the case. Some models may still produce some noise for various reasons. For a device made independently, the likelihood of such an outcome increases.
There are practically no wearing components in the design of both factory-made and home-made induction heaters. They last a long time and work flawlessly
Step-by-step guide to making a heater
All work on the manufacture of an induction heater is divided into several stages, during each of which one of the main parts is processed.
Next, we will talk in detail about how to assemble an induction heater for a car service with your own hands, using all the above kits.
