PSoC Challange "Smart reflow oven"

RE: PSoC Challange "Smart reflow oven"

vitecd — Mon, 10 Nov 2014 08:33:28 GMT

Hello

Can U share code and pin-outs? I like this project and also wants to try using this display.

Thank you [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-01d25e93-3ef9-46c0-ab38-1f1887bd8b84/contentimage_5F00_3.png:16:16]

RE: PSoC Challange "Smart reflow oven"

jvdberg@ieee.org — Sun, 17 Nov 2013 12:13:20 GMT

Hi Linus, Looking at your simple schematic I found some strange things. 1e Is the transistor in the optocoupler capable of driving the coil of the relay? 2e The ground connection is connected to the negative connection of the mains rectifier. This means the 12 Volt and 5 Volt sections of the circuit is connected to the mains voltage. An optocoupler is not necessary; a single transistor can be used to drive the relay. A better solution would be to place the optocoupler in the PWM-signal. The control-circuit then can be isolated from the mains Voltage. Then you need an extra 12 Volt supply connected to the mains side for the driver for the IRFP32N50K Some tips: Check the temperature in the compartment where you intend to install the electronics. It might become very hot there. Thermal insulation and extra access of air might be necessary. To reduce arcing and pitting the relay-contact can be placed before the bridge rectifier. A hardware overtemperature protection can be added to switch off the heater when the control circuit fails.

RE: PSoC Challange "Smart reflow oven"

e14 Contributor — Wed, 06 Nov 2013 11:02:36 GMT

heater control looks very problematic:

1. you will be getting a lot of RF noise when trying to PWM high voltage power line.

2. by using PWM you are also doing way too many on/off transitions on your IGBT which results in a lot of heat and the need for expensive IGBT.

3. bridge is also generating a lot of heat.

doesn't the heater run off AC? if so why not using a simple zero-cross enabled optocoupler + triac?

this would be simple, would save some heat, but still not super efficient.

and if it does need DC or you just want to make it very efficient, then you would be able to solve all 3 issues above by using 2 N-mosfets(4 if DC is needed) like this:

http://1.bp.blogspot.com/-NhkIxnLAraY/Ty2HT74B3cI/AAAAAAAAAEg/kzvyyHG3at4/s1600/ac+main+switch+mosfet+app.JPG

i used similar schematic for a dimmer and it makes basically no heat - if switching on zero cross you should be able to use 2 mosfets with no heatsink at all, saving not only power but space and cooling issues.

Sėkmės [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-01d25e93-3ef9-46c0-ab38-1f1887bd8b84/2806.contentimage_5F00_1.png:16:16]

RE: PSoC Challange "Smart reflow oven"

vsluiter — Sun, 03 Nov 2013 22:38:57 GMT

Hello Linas,

Wouldn't it be possible to drive the display with the PSOC4 / PSOC5? I mean, the other task (temperature control) is so slow that you can probably just do it on interrupt / DMA basis so your display updates will hardly suffer. I'm not at home in display control, but I can't see yet why you would need a very powerful processor; frame rate only needs to be 20Hz, if not lower....

Please convince me [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-01d25e93-3ef9-46c0-ab38-1f1887bd8b84/contentimage_5F00_1.png:16:16]

RE: PSoC Challange "Smart reflow oven"

DAB — Fri, 01 Nov 2013 20:16:47 GMT

Hi Linus,

Have you considered using a noncontact IR thermeter to keep an eye on the overall temperature of the oven?

You could easily set it up to perform an emergency shutdown if the temperature on your board reached undesired temperatures.

It would also allow you more flexibility in both testing the setup and running normal reflow tasks.

Just a thought,

DAB