InductionHeater - Revision history

Bas at 11:49, 1 October 2016

2016-10-01T11:49:32Z

← Older revision		Revision as of 11:49, 1 October 2016
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	{{Project		{{Project
	\|Name=InductionHeater		\|Name=InductionHeater
			\|Picture=Hqdefault.jpg
	\|Status=In progress		\|Status=In progress
	\|Contact= smeding		\|Contact= smeding

Smeding: Forgot I revised the transformer ratio, since 60:2 should still work and it's mechanically much easier

2016-09-30T21:14:20Z

Forgot I revised the transformer ratio, since 60:2 should still work and it's mechanically much easier

← Older revision		Revision as of 21:14, 30 September 2016
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	The coupling transformer converts the high-voltage low-current chopped mains waveform to low voltage and high current for the work coil. Using a separate coupling transformer relaxes the requirements on the workpiece coil, so it can be adapted more easily to the workpiece being heated.		The coupling transformer converts the high-voltage low-current chopped mains waveform to low voltage and high current for the work coil. Using a separate coupling transformer relaxes the requirements on the workpiece coil, so it can be adapted more easily to the workpiece being heated.

	It'll be made from four stacked [https://www.aliexpress.com/item/Dark-Gray-Power-Transformers-Ferrite-Toroid-Cores-100mm-x-60mm-x-15mm/689128147.html 100 × 60 × 15 mm ferrite cores] (to provide enough core cross-sectional area for the magnetic field). The primary will consist of ~~120~~ turns of thick litz wire, and the secondary will be 4 turns of 15mm OD copper tubing, giving a winding ratio of 30:1.		It'll be made from four stacked [https://www.aliexpress.com/item/Dark-Gray-Power-Transformers-Ferrite-Toroid-Cores-100mm-x-60mm-x-15mm/689128147.html 100 × 60 × 15 mm ferrite cores] (to provide enough core cross-sectional area for the magnetic field). The primary will consist of 60 turns of thick litz wire, and the secondary will be 2 turns of 15mm OD copper tubing, giving a winding ratio of 30:1.

	== Pledges ==		== Pledges ==

Smeding: First bit of info about the controller and transformer, schematics etc. forthcoming

2016-09-30T19:47:51Z

First bit of info about the controller and transformer, schematics etc. forthcoming

← Older revision		Revision as of 19:47, 30 September 2016
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	* [https://www.youtube.com/watch?v=l7fArOvXhQY https://www.youtube.com/watch?v=l7fArOvXhQY]		* [https://www.youtube.com/watch?v=l7fArOvXhQY https://www.youtube.com/watch?v=l7fArOvXhQY]

	==System design==		== System design ==
	Induction heating works by applying a high-frequency magnetic field to the (conductive) workpiece being heated. Because of the [https://en.wikipedia.org/wiki/Skin_effect skin effect], conduction at these frequencies only occurs in a thin layer on the outside of the workpiece. This acts like the secondary winding of a transformer, allowing current to flow and heating the workpiece through resistive heating.		Induction heating works by applying a high-frequency magnetic field to the (conductive) workpiece being heated. Because of the [https://en.wikipedia.org/wiki/Skin_effect skin effect], conduction at these frequencies only occurs in a thin layer on the outside of the workpiece. This acts like the secondary winding of a transformer, allowing current to flow and heating the workpiece through resistive heating.

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	* The controller monitors relevant currents and voltages, and generates the waveforms that drive the power stage transistors.		* The controller monitors relevant currents and voltages, and generates the waveforms that drive the power stage transistors.

	===Specs===		=== Specs ===
	* Input power: Standard single-phase mains: 230V RMS, 16A max ⇒ 3.5kVA		* Input power: Standard single-phase mains: 230V RMS, 16A max ⇒ 3.5kVA
	* Frequency: 10 kHz - 100 kHz		* Frequency: 10 kHz - 100 kHz
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	* 'Modified square wave' control: variable frequency and duty cycle		* 'Modified square wave' control: variable frequency and duty cycle

	==Power stage==		=== Controller ===
			The controller is based around a [http://www.st.com/content/st_com/en/products/microcontrollers/stm32-32-bit-arm-cortex-mcus/stm32f3-series/stm32f334.html STM32F334] ARM microcontroller. Its job is to generate the drive waveforms for the power stage, and display system status, based on measuring the relevant voltages and currents.

			=== Power stage ===
	[[File:Induction_heater_power_stage_schematic.png\|1280px\|The power stage schematic.]]		[[File:Induction_heater_power_stage_schematic.png\|1280px\|The power stage schematic.]]

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	[[File:Induction_heater_power_stage_board_layout.png\|512px\|The power stage board layout.]]		[[File:Induction_heater_power_stage_board_layout.png\|512px\|The power stage board layout.]]
	[[File:Induction_heater_power_stage_board_assembled.jpg\|768px\|The assembled power stage board.]]		[[File:Induction_heater_power_stage_board_assembled.jpg\|768px\|The assembled power stage board.]]

			=== Coupling transformer ===
			The coupling transformer converts the high-voltage low-current chopped mains waveform to low voltage and high current for the work coil. Using a separate coupling transformer relaxes the requirements on the workpiece coil, so it can be adapted more easily to the workpiece being heated.

			It'll be made from four stacked [https://www.aliexpress.com/item/Dark-Gray-Power-Transformers-Ferrite-Toroid-Cores-100mm-x-60mm-x-15mm/689128147.html 100 × 60 × 15 mm ferrite cores] (to provide enough core cross-sectional area for the magnetic field). The primary will consist of 120 turns of thick litz wire, and the secondary will be 4 turns of 15mm OD copper tubing, giving a winding ratio of 30:1.

	== Pledges ==		== Pledges ==

Smeding: Narrower images

2016-09-30T18:40:37Z

Narrower images

← Older revision		Revision as of 18:40, 30 September 2016
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	==Power stage==		==Power stage==
	[[File:Induction_heater_power_stage_schematic.png]]		[[File:Induction_heater_power_stage_schematic.png\|1280px\|The power stage schematic.]]

	Shown above is the schematic for the power stage. Mains voltage enters on the top left, where it is rectified and filtered to get approximately 325 V DC. Then, four IGBTs (IGBT1H, -1L, -2H, and -2L) form an H-bridge that generates the 10-100 kHz 'modified square wave' for the transformer.		Shown above is the schematic for the power stage. Mains voltage enters on the top left, where it is rectified and filtered to get approximately 325 V DC. Then, four IGBTs (IGBT1H, -1L, -2H, and -2L) form an H-bridge that generates the 10-100 kHz 'modified square wave' for the transformer.
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	The IGBTs are driven via gate-drive transformers (GDT1 and GDT2) so that the control circuitry can be isolated from the high-voltage side. These transformers in turn are driven by high-current MOSFET drivers (IC1H, -1L, -2H, and -2L), which receive their signals from the controller.		The IGBTs are driven via gate-drive transformers (GDT1 and GDT2) so that the control circuitry can be isolated from the high-voltage side. These transformers in turn are driven by high-current MOSFET drivers (IC1H, -1L, -2H, and -2L), which receive their signals from the controller.

	[[File:~~Induction_heater_power_stage_board_assembled~~.~~jpg~~]]		[[File:Induction_heater_power_stage_board_layout.png\|512px\|The power stage board layout.]]
	[[File:~~Induction_heater_power_stage_board_layout~~.~~png~~]]		[[File:Induction_heater_power_stage_board_assembled.jpg\|768px\|The assembled power stage board.]]

	== Pledges ==		== Pledges ==

Smeding: Start of overhaul: power stage documentation

2016-09-30T18:35:00Z

Start of overhaul: power stage documentation

@@ Line 2: / Line 2: @@
     |Name=InductionHeater
     |Status=In progress
-    |Contact= smeding, gori
+    |Contact= smeding
    }}
@@ Line 11: / Line 11: @@
 * [https://www.youtube.com/watch?v=l7fArOvXhQY https://www.youtube.com/watch?v=l7fArOvXhQY]
-==Specs==
+==System design==
-* Input power: 3.5kVA, standard single-phase mains
+Induction heating works by applying a high-frequency magnetic field to the (conductive) workpiece being heated. Because of the [https://en.wikipedia.org/wiki/Skin_effect skin effect], conduction at these frequencies only occurs in a thin layer on the outside of the workpiece. This acts like the secondary winding of a transformer, allowing current to flow and heating the workpiece through resistive heating.
-==Inverter circuit==
+The design consists of the following parts:
-The basic power system looks as follows:
+* The power stage rectifies mains voltage, which is then chopped into a high-frequency 'modified square wave' with variable duty cycle and frequency.
-[[File:Induction_heater_system.png|800px]]
+===Specs===
-V 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.
+==Power stage==
-The resonant frequency changes depending on workpiece geometry, coil geometry, workpiece temperature, etc. etc. so this needs to be tracked by a controller.
+Shown above is the schematic for the power stage. Mains voltage enters on the top left, where it is rectified and filtered to get approximately 325 V DC. Then, four IGBTs (IGBT1H, -1L, -2H, and -2L) form an H-bridge that generates the 10-100 kHz 'modified square wave' for the transformer.
-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 IGBTs are driven via gate-drive transformers (GDT1 and GDT2) so that the control circuitry can be isolated from the high-voltage side. These transformers in turn are driven by high-current MOSFET drivers (IC1H, -1L, -2H, and -2L), which receive their signals from the controller.
-== BOM ==
+[[File:Induction_heater_power_stage_board_assembled.jpg]]
-Some of the components have already been scrounged together. Thanks to benadski for acquiring an induction cooktop that contained many useful parts!
+[[File:Induction_heater_power_stage_board_layout.png]]
 == Pledges ==

FooBar at 18:03, 21 October 2014

2014-10-21T18:03:49Z

← Older revision		Revision as of 18:03, 21 October 2014
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	* [[Flok]]: 10 euro		* [[Flok]]: 10 euro
	* Walter: 50 евра		* Walter: 50 евра
	* FooBar: €20		* FooBar: €20 cash betaald
	* [[bertrik]]: €10		* [[bertrik]]: €10
	* Semafoor: €20		* Semafoor: €20
	* [[Morphje]]: EUR 10 (and driving to the hardware store ~~if needed~~)		* [[Morphje]]: EUR 10 (and driving to the hardware store once)

	Total pledges: €170		Total pledges: €170

Semafoor at 09:46, 16 October 2014

2014-10-16T09:46:58Z

← Older revision		Revision as of 09:46, 16 October 2014
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	* FooBar: €20		* FooBar: €20
	* [[bertrik]]: €10		* [[bertrik]]: €10
	* Semafoor: €20 ~~(more if the project is better defined)~~		* Semafoor: €20
	* [[Morphje]]: EUR 10 (and driving to the hardware store if needed)		* [[Morphje]]: EUR 10 (and driving to the hardware store if needed)

	Total pledges: ~~€160~~		Total pledges: €170

Morphje: /* Pledges */

2014-10-14T14:37:05Z

Pledges

← Older revision		Revision as of 14:37, 14 October 2014
Line 103:		Line 103:
	* [[bertrik]]: €10		* [[bertrik]]: €10
	* Semafoor: €20 (more if the project is better defined)		* Semafoor: €20 (more if the project is better defined)
	* [[~~User:~~Morphje]]: EUR 10 (and driving to the hardware store if needed)		* [[Morphje]]: EUR 10 (and driving to the hardware store if needed)

	Total pledges: €160		Total pledges: €160

Morphje: /* Pledges */

2014-10-14T14:35:17Z

Pledges

← Older revision		Revision as of 14:35, 14 October 2014
Line 103:		Line 103:
	* [[bertrik]]: €10		* [[bertrik]]: €10
	* Semafoor: €20 (more if the project is better defined)		* Semafoor: €20 (more if the project is better defined)
	* [[Morphje]]: EUR 10 (and driving to the hardware store if needed)		* [[User:Morphje]]: EUR 10 (and driving to the hardware store if needed)

	Total pledges: €160		Total pledges: €160

Morphje at 14:33, 14 October 2014

2014-10-14T14:33:36Z

← Older revision		Revision as of 14:33, 14 October 2014
Line 103:		Line 103:
	* [[bertrik]]: €10		* [[bertrik]]: €10
	* Semafoor: €20 (more if the project is better defined)		* Semafoor: €20 (more if the project is better defined)
			* [[Morphje]]: EUR 10 (and driving to the hardware store if needed)

	Total pledges: €160		Total pledges: €160