EcoRenovator - View Single Post - DIY dehumidifier/air conditioner/heat pump water heater

NiHaoMike · 06-09-13, 11:18 PM

I installed OpenFOAM on my PC to try to simulate the ejector, but there sure is quite a learning curve! (I'm definitely going to ask some friends who have studied chemical or mechanical engineering.)

The pump does have to work with potable water, as does the heat exchanger. I just looked up the ECM pumps and they're not that much more expensive than the conventional ones, probably break even or better after considering the cost of an inverter. What I'm not sure about is whether or not they're easily hackable to allow speed control from a microcontroller. Looks like my best bet is to get one of the solar pumps and then emulate a solar panel.

I'm also not sure exactly what variant of ECM technology they use, since from my experience with computer fans, it makes a pretty big difference. My old Nidec ECM fan, once considered the most advanced fan available, is completely blown away by a new Delta. Nidec's original ECM technology is just a 5 level drive (very easy to implement in an 8 bit microcontroller) and makes a very distinctive buzz even at low speeds. Delta's Cindy Wu sensorless FOC and Nidec's new ECM technology (the two work in a very similar manner, both use 32 bit DSPs) drive sine waves to the motor at low speed and trapezoidal waves at high speed, as well as measure the voltages and currents coming back from the motor in order to get the phase just right.

For your information, I got curious and decided to scope a Delta fan with Cindy Wu sensorless FOC. Top trace is the phase to ground voltage, bottom trace is the neutral to ground voltage. (Unfortunately, I wasn't able to take it apart far enough to see the control logic. The real magic is going to be in the code inside the microcontroller anyways...) Modern ECM motors sure are complex! (As for a Delta fan being Y wired, that's just ironic...)

Here's a Delta fan someone else took apart, but it's much different from the one I have. Also there are the pictures inside a Sanyo fan and a (newer) Nidec. The interesting part is that the Sanyo has a resolver whereas the Deltas and Nidecs don't.
Pictures of A Dead Delta Fan and It's Internal Parts █ NO 56K-TONS OF PICS █ - Overclockers Forums

06-09-13, 11:18 PM	#4
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	I installed OpenFOAM on my PC to try to simulate the ejector, but there sure is quite a learning curve! (I'm definitely going to ask some friends who have studied chemical or mechanical engineering.) The pump does have to work with potable water, as does the heat exchanger. I just looked up the ECM pumps and they're not that much more expensive than the conventional ones, probably break even or better after considering the cost of an inverter. What I'm not sure about is whether or not they're easily hackable to allow speed control from a microcontroller. Looks like my best bet is to get one of the solar pumps and then emulate a solar panel. I'm also not sure exactly what variant of ECM technology they use, since from my experience with computer fans, it makes a pretty big difference. My old Nidec ECM fan, once considered the most advanced fan available, is completely blown away by a new Delta. Nidec's original ECM technology is just a 5 level drive (very easy to implement in an 8 bit microcontroller) and makes a very distinctive buzz even at low speeds. Delta's Cindy Wu sensorless FOC and Nidec's new ECM technology (the two work in a very similar manner, both use 32 bit DSPs) drive sine waves to the motor at low speed and trapezoidal waves at high speed, as well as measure the voltages and currents coming back from the motor in order to get the phase just right. For your information, I got curious and decided to scope a Delta fan with Cindy Wu sensorless FOC. Top trace is the phase to ground voltage, bottom trace is the neutral to ground voltage. (Unfortunately, I wasn't able to take it apart far enough to see the control logic. The real magic is going to be in the code inside the microcontroller anyways...) Modern ECM motors sure are complex! (As for a Delta fan being Y wired, that's just ironic...) Here's a Delta fan someone else took apart, but it's much different from the one I have. Also there are the pictures inside a Sanyo fan and a (newer) Nidec. The interesting part is that the Sanyo has a resolver whereas the Deltas and Nidecs don't. Pictures of A Dead Delta Fan and It's Internal Parts █ NO 56K-TONS OF PICS █ - Overclockers Forums __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...