InductionHeater: Difference between revisions

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(Page rewrite with actual BOM!)
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   {{Project
   {{Project
   |Name=InductionHeater
   |Name=InductionHeater
   |Status=Initializing
   |Status=In progress
   |Contact= smeding, gori
   |Contact= smeding, gori
   }}
   }}


Idea is to make a 3kW induction spool to smelt metals and heat steel for forging.
We're working on an induction heater that can be used to heat anything conductive to high temperatures. The plan is to try to use it for forging steel and melting aluminium.
For examples see :
 
Here are some examples of what a device like this is capable of:
* [http://www.youtube.com/watch?v=0HdbKKvOiWU]
* [http://www.youtube.com/watch?v=0HdbKKvOiWU]
* [http://www.youtube.com/watch?v=l7fArOvXhQY]
* [http://www.youtube.com/watch?v=l7fArOvXhQY]
==Specs==
* Input power: 3.5kVA, standard single-phase mains
* Frequency: 10 - 100 kHz


==Inverter circuit==
==Inverter circuit==
 
The basic power system looks as follows:
Smeding came up with the following circuit:


[[File:Induction_heater_system.png|800px]]
[[File:Induction_heater_system.png|800px]]


Values of all components are to follow shortly.
230V mains input is rectified, then filtered slightly and chopped up into a variable-frequency square wave (or modified sine wave) using an H-bridge made of IGBTs. This is fed into a coupling transformer, which turns this high voltage, (relatively) low-current waveform into a higher-current, lower-voltage one more suitable for the system. This is connected to a series-resonant circuit comprised of the heating coil and a tank capacitor.


The resonant frequency changes depending on workpiece geometry, coil geometry, workpiece temperature, etc. etc. so this needs to be tracked by a controller.


'''WARNING: THIS IS OUTDATED AND WILL BE REPLACED LATER'''
The secondary side of the transformer dissipates a lot of power (there are potentially hundreds of ampères flowing there, so fairly large ohmic losses) and will need to be water-cooled to prevent it from getting too hot.


The accompanying BOM looks something like this:
== BOM ==
Some of the components have already been scrounged together. Thanks to benadski for acquiring an induction cooktop that contained many useful parts!


{|class="wikitable"
{|class="wikitable"
!Component
!Component
!cost
!Cost
!Comments
|-
|-
|Bridge rectifier
|Bridge rectifier
|€2.56
|
|Salvaged from cooktop
|-
|-
|switching transistor
|inverter IGBTs
|€22.92
|
|Salvaged from cooktop
|-
|-
|Tank capacitors
|Tank capacitors
|20.50
|
|Salvaged from cooktop
|-
|-
|DC link filter capacitor
|DC link filter capacitor
|€23.14
|
|Salvaged from cooktop
|-
|-
|Gate driver
|Gate drive transformers
|€7.06
|
|Salvaged from cooktop
|-
|-
|Couple transformer Toroid
|Coupling transformer core(s)
|€20 (est.)
|€42
|http://www.aliexpress.com/item/100mm-x-65mm-x-20mm-Ferrite-Rings-Toroid-for-Filters-Coils/879528762.html, we need 3 of these for enough core area
|-
|-
|Gate drive transormer toroid
|Litz wire for transformer primary
|€3
|
|Salvaged from cooktop
|-
|-
|Estimate for components killed (see below)
|Copper tubing, 15mm OD * 5m
|€60
|€30
|Conservative estimate from hardware store -- can probably do better. Will need more than 5m for larger work coil.
|-
|-
|'''Total'''
|Copper pipe compression couplings 15mm * 2
|€160
|€12
|}
|Can probably do better
 
Based on [http://local.roysmeding.nl/3kW_BOM.png Smedings estimate]
Obviously, some parts may die a gruesome death during construction and testing. Worst case estimate is that the switching transistor and the driver will die twice, adding an amount of €60 to the BOM before we have a working machine.
 
 
 
==Additional hardware==
 
 
In addition to the inverter circuit, at least the following things are needed to make a working induction heater
{|class="wikitable"
!Component
!cost
!Possible sources
!requirements
|-
|-
|Coil 1 small diameter for smelting
|Water cooling pump
|€ 15 ?
|€5
|Gas tubing, car brake tubing
|Cheap brushless water pumps abound on eBay; e.g. http://www.ebay.com/itm/321431156285
|Copper. Sufficient copper area to handle the current. Sufficient inner area + diameter to allow for effective cooling
|-
|-
|Coil 2 large diameter, 30cm for forging, between 5 and  10m
|Water cooling connections
|€ 25 - 50
|?
|Gas tubing, 15 mm  car brake tubing
|Need to find best solution
|Copper. Sufficient copper area to handle the current. Sufficient inner area + diameter to allow for effective cooling
|-
|-
 
|Water cooling radiator
|heat exchanger
|?
|€15 ?
|Car engine radiator goes €10 - €20 on Marktplaats. Possibly from scrapyard?
|Car junkyard
|Unsure how much heat needs to be removed and at what temperatures. Worst Case would be 3 kW. A car radiator is probably good (cheap, sufficient power and an integrated fan)
|-
|-
|Pump
|Gate driver *4
|€20
|€5
|Possibly a pump from a domestic heater (CV). Buy for around €20 on Marktplaats
|e.g. http://nl.farnell.com/microchip/tc4420coa/ic-driver-mosfet-6a-smd-soic8/dp/1292283
|Have to check whether or not normal sizes create sufficient flow through  small diameter coil tubing
|-
|-
|Electrical connections and wiring
|Control electronics
|€ 20
|€10
|Battery connections form scrapped cars?
|Microcontroller, displays, assorted resistors&capacitors
|How much current do we expect, and how long do the wires have to be? how do we connect these to the coil tubing (Earth blocks?
|-
|Tubes and other cooling connectors
|15€
|
|
|-
|...
|
|
|
|-
|'''Total cost'''
|€ 85 (incomplete)
|}
 
==Total cost==
 
{|class="wikitable"
!
!cost
|-
|Inverter
|€160
|-
|Hardware
|€85
|-
|-
|'''Total'''
|'''Total'''
|€245
|€104
|}
|}


Now we need financing.  The current total is '''€245''', and that isn't complete so far (although it may get close)
== Pledges ==


Pledges:
So far, the following has been pledged:
* [[Gori]]: 50 euro
* [[Gori]]: 50 euro
* [[Flok]]: 10 euro
* [[Flok]]: 10 euro
Line 135: Line 103:
* [[bertrik]]: €10
* [[bertrik]]: €10
* Semafoor: €20 (more if the project is better defined)
* Semafoor: €20 (more if the project is better defined)
Total pledges: €160

Revision as of 02:17, 1 October 2014

Project InductionHeater
Status In progress
Contact smeding, gori
Last Update 2014-10-01

We're working on an induction heater that can be used to heat anything conductive to high temperatures. The plan is to try to use it for forging steel and melting aluminium.

Here are some examples of what a device like this is capable of:

Specs

  • Input power: 3.5kVA, standard single-phase mains
  • Frequency: 10 - 100 kHz

Inverter circuit

The basic power system looks as follows:

Induction heater system.png

230V mains input is rectified, then filtered slightly and chopped up into a variable-frequency square wave (or modified sine wave) using an H-bridge made of IGBTs. This is fed into a coupling transformer, which turns this high voltage, (relatively) low-current waveform into a higher-current, lower-voltage one more suitable for the system. This is connected to a series-resonant circuit comprised of the heating coil and a tank capacitor.

The resonant frequency changes depending on workpiece geometry, coil geometry, workpiece temperature, etc. etc. so this needs to be tracked by a controller.

The secondary side of the transformer dissipates a lot of power (there are potentially hundreds of ampères flowing there, so fairly large ohmic losses) and will need to be water-cooled to prevent it from getting too hot.

BOM

Some of the components have already been scrounged together. Thanks to benadski for acquiring an induction cooktop that contained many useful parts!

Component Cost Comments
Bridge rectifier Salvaged from cooktop
inverter IGBTs Salvaged from cooktop
Tank capacitors Salvaged from cooktop
DC link filter capacitor Salvaged from cooktop
Gate drive transformers Salvaged from cooktop
Coupling transformer core(s) €42 http://www.aliexpress.com/item/100mm-x-65mm-x-20mm-Ferrite-Rings-Toroid-for-Filters-Coils/879528762.html, we need 3 of these for enough core area
Litz wire for transformer primary Salvaged from cooktop
Copper tubing, 15mm OD * 5m €30 Conservative estimate from hardware store -- can probably do better. Will need more than 5m for larger work coil.
Copper pipe compression couplings 15mm * 2 €12 Can probably do better
Water cooling pump €5 Cheap brushless water pumps abound on eBay; e.g. http://www.ebay.com/itm/321431156285
Water cooling connections ? Need to find best solution
Water cooling radiator ? Car engine radiator goes €10 - €20 on Marktplaats. Possibly from scrapyard?
Gate driver *4 €5 e.g. http://nl.farnell.com/microchip/tc4420coa/ic-driver-mosfet-6a-smd-soic8/dp/1292283
Control electronics €10 Microcontroller, displays, assorted resistors&capacitors
Total €104

Pledges

So far, the following has been pledged:

  • Gori: 50 euro
  • Flok: 10 euro
  • Walter: 50 евра
  • FooBar: €20
  • bertrik: €10
  • Semafoor: €20 (more if the project is better defined)

Total pledges: €160

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