How does Induction Heating Work? || DIY Induction Heater Circuit

The Basics of Induction Heating

Induction heating is a technique used to heat up objects by creating an electromagnetic field around them. This field induces eddy currents, which are electrical currents that flow within the object. The movement of these eddy currents generates heat due to the resistance of the material.

When a conductor, such as a wire or a metal loop, is placed inside a coil, an alternating current flows through it. If the conductor is stationary, the input current does not increase and there is no noticeable effect on the finger inside the coil. However, if the conductor is moved within the coil, the input current increases due to the creation of eddy currents.

In this experiment, a metal conductor form was used as a loop, and it was placed inside the coil. According to the law of electromagnetic induction, a small voltage across the conductor could be measured. When the loop was closed, creating a short circuit, a noticeable increase in input current occurred due to the flow of current through the inductor.

The experiment also showed that different materials have varying effects on eddy currents and heating. Aluminum, brass, and iron were tested with a coil and observed as follows: The aluminum increased the input current by 900 milliamps and reached a temperature of 47 degrees Celsius after 40 seconds. Brass produced an increase in current by one amp and reached a temperature of 48 degrees Celsius, which is around 10 degrees higher than the aluminum piece. Iron lowered the input voltage to such an extent that it had to be increased with additional power supply channels.

The reason for this variation can be attributed to the different properties of each material. Aluminum has a relatively low resistance and does not generate as many eddy currents compared to brass, which possesses higher resistance. Brass also generates more eddy currents than aluminum due to its higher resistance. Iron, being ferromagnetic, is able to retain magnetism and generate additional heat through hysteresis losses.

Creating an Induction Heater

The principles of induction heating can be applied to create a simple heater using a few components. This experiment used silver and copper wire for the coil, a resistor-based circuit as a coolant, and a MOSFET with Zener diodes for protection.

First, a timer was added to the experiment to measure the temperature increase over time. The aluminum piece reached 47 degrees Celsius after 40 seconds, while the brass reached 48 degrees Celsius. These temperatures are indicative of the heating effect caused by eddy currents generated within each material.

The experiment showed that different materials respond differently to induction heating. Aluminum and brass produce noticeable increases in current due to their relatively low resistance and high conductivity, whereas iron generates significant heat through its ferromagnetic properties and hysteresis losses.

A Simple Induction Heater Schematic

To build an induction heater circuit, one would need the following components: silver or copper wire for the coil, a resistor-based circuit as a coolant, Zener diodes for protection, a MOSFET with a fast discharge capability, and capacitors that can handle excessive voltage. The coil is typically made from 2 millimeter thick enamel-coated copper wire, which is wound around a 20 millimeter plastic pipe to create the desired resonance frequency.

The entire circuit was connected and tested using a power supply with a maximum voltage of 12 volts and a current limit of 3 amps. Since the experiment did not require protection from high voltages above the MOSFET's limits, Zener diodes were omitted. However, it is recommended to use Zener diodes for higher input voltages to prevent damage to the components.

The fast discharge capability of the capacitor and the MOSFET ensured that the gate was safely discharged in a fast manner. When the circuit was powered up, the induction heater successfully created heat within the metal conductor, demonstrating the principles of electromagnetic induction and eddy currents.

Conclusion

Induction heating is an effective technique for heating objects by creating electromagnetic fields around them. Different materials respond differently to this effect, with some producing more eddy currents and thus generating more heat than others. The experiment demonstrated the properties of aluminum, brass, and iron when used as conductors in a coil, highlighting their varying effects on eddy currents and heating.

The simple induction heater circuit built using silver and copper wire for the coil, a resistor-based circuit, Zener diodes for protection, and other components successfully demonstrates the principles of electromagnetic induction. The experiment serves as an introduction to the world of electromagnetic theory and can inspire further exploration into this fascinating field.

WEBVTTKind: captionsLanguage: enI recently found this rather interesting induction heater circuit for cheap on eBay by simply adding a helical coil to its upper terminal and applying 12 volts to its input terminal I can place a metal object inside the coil and the sufficiently heated up to a point to work close rats and just like that I can start cutting through things will be hot exacto knife because sadly this is the kind of content way too many people enjoy watching but how does this induction heating and the circuit actually work can we build worn by ourselves and which materials can be heated up let's find out first off I used my multimeter to track the circuit paths of the PCB eeeh in order to find out how the components are connected to one another the reverse engineered circuit diagram only features a handful of components and is awfully similar to the circuits that I created for my DIY al-qaeda projects the only difference is that instead of a center tapped coil with one constant current source this new circuit used a more common coil without a tapped center but with two constant current sources this way after powering the induction heater as sine portage and current is created at the output of the circuits and thus the coil creates a changing sinusoidal magnetic fields now if I stick my finger inside the coil the input current does not increase and I feel nothing differently about my finger except that the coil slowly heats up due to the flowing current but if I take a metal conductor form a loop it's and place it inside the coil we can measure a small voltage across its according to the law of electromagnetic induction if we now close the loop we basically created a short circuits and thus a current will flow through the inductor which is also noticeable by the increase of the input current since the coolant circuit for this arrangement is just a resistor based on the dimensions of the conductor we can assume that the generator teat is proportional to the resistance and the flowing current and now that we understand the basics of induction heating for a piece of wire as a loop we can apply this knowledge to three different metals which are brought in to a small shape before hand here we cut aluminum brass and ayran after placing the aluminum inside the coil the input current increased by nine hundred milliamps because this time does not just want current path inside this material but thousands of them which therefore increased the overall current flow such currents are also called eddy currents and are usually undesirable since they represent a power loss that is also why the iron copper transformer usually consists of isolated plates instead of one complete piece of metal but let's focus on the aluminum and let's add a timer to the experiments after 40 seconds inside the coil the material reach a temperature of 47 degrees Celsius so let's see what the brass can Excel this temperature this time the material increased the input current by one amp and after 30 seconds reached temperature of 48 degree Celsius that is around 10 degrees more than the aluminum piece and actually not as surprising since brass possesses a higher resistance last but not least we cut iron which after placing it inside the coil lowered the input voltage to such an extent that I had no choice but to put the two channels of my power supply in parallel and tried it again but even with twice the current it was not enough so I was forced to only insert the tip of the material which already increased the input current by four amps after 30 seconds inside the coil the tip of the iron easily reach a temperature of 160 degrees Celsius which is quite a big difference compared to the other two the reason for that is for one is higher resistance but also it's ferromagnetic characteristic which means it can stick to a magnets and can also be magnetized through a magnetic fields the process of magnetizing and demagnetizing happens inside the coil and thus creates another kind of power loss known as the hysteresis loss and that is basically the reason why ferromagnetic materials heat up a lot faster than other materials and thus a favored where it comes to something like inductive cooking at the end let's gather a couple of components and see whether we can build such a circuit by ourselves according to this simple schematic I connected all components to one another Hoover put of silver copper wire in midair since I will be using a maximum voltage of 12 volts and the current limit of 3 amps I do not necessarily need Zener diodes to protect the gates from voltages above its limits and pulldown resistors to prevent latch ups but it is definitely recommended for higher input voltages it is also important to use a fast diode to discharge the gate in a fast manner a MOSFET with a higher maximum drain to source voltage than the resonance voltage and the capacitor which can handle the excessive voltage and current as well but those vemma mkp capacitors are usually a safe bet the last mandatory component is the coil itself for that I use 2 millimeter thick enamel copper wire which I want around the 20 millimeter plastic pipe for around 10 turns after removing the insulation from its and soldering them to the circuits and powering it all up we successfully created our own induction heater that can transfer enough energy to let metal clorets now if you have more questions about the utilized circuits then definitely check out my a lighter projects and the previous Hecht episode about the CCFL inverter if you liked this episode and maybe learn something new as well then don't forget to like share and subscribe stay creative and I will see you next timeI recently found this rather interesting induction heater circuit for cheap on eBay by simply adding a helical coil to its upper terminal and applying 12 volts to its input terminal I can place a metal object inside the coil and the sufficiently heated up to a point to work close rats and just like that I can start cutting through things will be hot exacto knife because sadly this is the kind of content way too many people enjoy watching but how does this induction heating and the circuit actually work can we build worn by ourselves and which materials can be heated up let's find out first off I used my multimeter to track the circuit paths of the PCB eeeh in order to find out how the components are connected to one another the reverse engineered circuit diagram only features a handful of components and is awfully similar to the circuits that I created for my DIY al-qaeda projects the only difference is that instead of a center tapped coil with one constant current source this new circuit used a more common coil without a tapped center but with two constant current sources this way after powering the induction heater as sine portage and current is created at the output of the circuits and thus the coil creates a changing sinusoidal magnetic fields now if I stick my finger inside the coil the input current does not increase and I feel nothing differently about my finger except that the coil slowly heats up due to the flowing current but if I take a metal conductor form a loop it's and place it inside the coil we can measure a small voltage across its according to the law of electromagnetic induction if we now close the loop we basically created a short circuits and thus a current will flow through the inductor which is also noticeable by the increase of the input current since the coolant circuit for this arrangement is just a resistor based on the dimensions of the conductor we can assume that the generator teat is proportional to the resistance and the flowing current and now that we understand the basics of induction heating for a piece of wire as a loop we can apply this knowledge to three different metals which are brought in to a small shape before hand here we cut aluminum brass and ayran after placing the aluminum inside the coil the input current increased by nine hundred milliamps because this time does not just want current path inside this material but thousands of them which therefore increased the overall current flow such currents are also called eddy currents and are usually undesirable since they represent a power loss that is also why the iron copper transformer usually consists of isolated plates instead of one complete piece of metal but let's focus on the aluminum and let's add a timer to the experiments after 40 seconds inside the coil the material reach a temperature of 47 degrees Celsius so let's see what the brass can Excel this temperature this time the material increased the input current by one amp and after 30 seconds reached temperature of 48 degree Celsius that is around 10 degrees more than the aluminum piece and actually not as surprising since brass possesses a higher resistance last but not least we cut iron which after placing it inside the coil lowered the input voltage to such an extent that I had no choice but to put the two channels of my power supply in parallel and tried it again but even with twice the current it was not enough so I was forced to only insert the tip of the material which already increased the input current by four amps after 30 seconds inside the coil the tip of the iron easily reach a temperature of 160 degrees Celsius which is quite a big difference compared to the other two the reason for that is for one is higher resistance but also it's ferromagnetic characteristic which means it can stick to a magnets and can also be magnetized through a magnetic fields the process of magnetizing and demagnetizing happens inside the coil and thus creates another kind of power loss known as the hysteresis loss and that is basically the reason why ferromagnetic materials heat up a lot faster than other materials and thus a favored where it comes to something like inductive cooking at the end let's gather a couple of components and see whether we can build such a circuit by ourselves according to this simple schematic I connected all components to one another Hoover put of silver copper wire in midair since I will be using a maximum voltage of 12 volts and the current limit of 3 amps I do not necessarily need Zener diodes to protect the gates from voltages above its limits and pulldown resistors to prevent latch ups but it is definitely recommended for higher input voltages it is also important to use a fast diode to discharge the gate in a fast manner a MOSFET with a higher maximum drain to source voltage than the resonance voltage and the capacitor which can handle the excessive voltage and current as well but those vemma mkp capacitors are usually a safe bet the last mandatory component is the coil itself for that I use 2 millimeter thick enamel copper wire which I want around the 20 millimeter plastic pipe for around 10 turns after removing the insulation from its and soldering them to the circuits and powering it all up we successfully created our own induction heater that can transfer enough energy to let metal clorets now if you have more questions about the utilized circuits then definitely check out my a lighter projects and the previous Hecht episode about the CCFL inverter if you liked this episode and maybe learn something new as well then don't forget to like share and subscribe stay creative and I will see you next time