First Heatpump project - Page 8

WyrTwister · 10-31-14, 05:33 PM

My limited understanding of a mini split DC inverter motor is the motor is really DC , but electronics switch the DC to various poles to produce rotation of the stator .

My experience with VFD's has been with mostly " normal " three phase squirrel cage induction motors . I think the current technology is pulse width modulation to end up with a current that varies in voltage , amperage and frequency .

Different ways of going about producing varying speed and torque . I have seen premium chillers that employ VFD's & three phase motors . They are said to be the " next step up " in energy efficiency . Although there may be something else that is the current latest and greatest ?

God bless
Wyr

PS VFD's are also used in pumps and Air Handler Units , in the HVAC world .

jeff5may · 10-31-14, 09:27 PM

The outdoor unit you have has a very sophisticated control scheme built in. It would probably be worth your while to find a compatible indoor unit.

That is, unless you are a glutton for punishment. If so, there are many ways to attack the unit. If you are lucky, you may be able to directly control the VFD (inverter) built into the outdoor unit.

takyka · 11-01-14, 04:09 AM

In general it's possible to use VFD to drive permanent magnet brushless motor. However it is not ideal and not designed for. You should be very careful with settings. I sucesfully run a BLDC fan (from an all dc inverter AC outdoor unit). with an mitsubishi s500 series VFD. Based on that, I believe it is possible.
In such application, the motor runs like a AC syncron motor. Your main issue is to keep it in sync to the driving frequency in any operating point, but avoid core saturation. As experiment, I would try with the next settings:
-Current limit 1.2 times higher than rated current. (if rotor stalls, excessive current will rise the alarm)
-Starting frequency 0 or as less as possible but not more than 1-2Hz
-minimum frequency ~30Hz (maybe you can get it from users manual)
-Maximum frequency ~80Hz (like above)
-Maximum drive voltage 150V
-V/F pattern linear
-acceleration pattern linear
-acceleration speed ~5s
-deceleratin speed 2-3s

If it runs good, inspect the current (from VFD) at a certain frequency (50Hz) start to lower the max voltage by 10V. (current will go down too) Go down until compressor stalls. Then start to rise the voltage by 10V check for current, and stop before it starts to rise dramaticaly (saturation of core->excessive loss of power).

The next issue will be to control the eev (if you have it). For that I recommend you to buy a relatively cheap, compatible controller like dixell xev22 (I use it with sucess).
Can be, it would be easyer to find a compatible indoor unit and hack that. This way you could use its own electronics. A friend of mine had sucess to replace indoor HX with BPHX without major modification of electronics.

T.

stef110 · 11-01-14, 09:58 AM

Yesterday i had a look on the compressor, and indeed there stand DC motor.
Which will be a BLDC motor. I wont want to run it with a vfd, because it is not made for that i don't want to risk. The niceness would be to find an indoor unit and use that electronics.

The other side is that i love to work with electronic's and it would be awesome if i can create my own BLDC driver for this compressor. Tomorrow i will dismantle the unit a bit more so that i can hopefully read more specs on the compressors data plate.

keep you posted.

stef

theoldwizard1 · 11-01-14, 10:07 AM

Quote:

Originally Posted by stef110

hello, My name is Stef I am 21 years old and i live in the Netherlands.

Stef, just catching up on this thread. I read your blog using Google translate.

Quote:

The idea of this project is to use a regular outdoor unit which has the ability to heat and cool, and connect it to a heat exchanger in the place where normally hangs indoor unit.

What you have done is exactly what I would like to do some day !! I need to re-read this post and your blog it before asking too many already answered question !

Quote:

... My English is not the best in the world so please don't shoot me on that!

Google sure does come up wit some weird translations ! One of my favorites was

"Toen ik vanmorgen wakker werd regende het pijpen stelen,"

Translated to ...

"When I woke up this morning it was raining steal pipes,"

Your spelling corrector must have substitued "stelen" for staal" ! (My family is from Belgium, although I do not speak Dutch/Flemish.)

Keep up the good work !

stef110 · 11-04-14, 02:11 PM

This weekend i dismantled the unit so i could clean it up, it probelby was standing some were in a garden it had a hole bunch of sand in it.
I also had a good look a the used components, and right now i am busy trying to investigate how i can control everything. It's gone be a hard job but i want to give it a try. I manage to power up the daikin outdoor circuit board. So i could measure some power lines right now i know the source voltage's of the fan and the inverter. I have to create a 300vdc power supply for the fan motor and inverter. The 4way valve is running on 120vdc and the eev just works on 12vdc.

Yesterday i also picked up a recovery unit suitable for r410a

stef

stef110 · 11-07-14, 12:56 PM

mmm there are some strange things happening on my heatpump.
It happen t a few times now, that the refrigerant that is entering the evaporator (outdoor radiator) doesn't catch any heat. The temperature of de refrigerant that is leaving the evaporator is the same as going in. Compressor uses less power as normal, and output heat is less then normal. On the outdoor unit is no sign of frog or anything. Could this have to do something with the amount of refrigerant in the system. it only happens when it is cold outside.

stef

theoldwizard1 · 11-07-14, 04:09 PM

Quote:

Originally Posted by stef110

The temperature of de refrigerant that is leaving the evaporator is the same as going in.

expansion valve open too far or stuck open ?

jeff5may · 11-07-14, 05:45 PM

how are you controlling the EEV? It sounds as if it is not following the evaporator temperature and pressure like it should.

Do you have service valves for the suction and discharge lines of the compressor? Do you have a liquid line service valve? In all of my homemade units, I install all three so I can check temperatures and pressures of everything once the unit is filled. Without all three, you can only estimate or guess what is happening where.

WAIT A MINUTE! Which one are you talking about? The one that you installed in August, or the one you just picked up?

stef110 · 11-08-14, 01:11 AM

sorry i was not that specific. Indeed i am talking on the already running unit with the capillary tube. I don't have a service valve on the suction side of the compressor.

stef

10-31-14, 09:27 PM	#72
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	The outdoor unit you have has a very sophisticated control scheme built in. It would probably be worth your while to find a compatible indoor unit. That is, unless you are a glutton for punishment. If so, there are many ways to attack the unit. If you are lucky, you may be able to directly control the VFD (inverter) built into the outdoor unit. Last edited by jeff5may; 11-01-14 at 05:45 AM..

11-01-14, 04:09 AM	#73
takyka Helper EcoRenovator Join Date: Jul 2014 Location: Hungary Posts: 34 Thanks: 0 Thanked 16 Times in 10 Posts	In general it's possible to use VFD to drive permanent magnet brushless motor. However it is not ideal and not designed for. You should be very careful with settings. I sucesfully run a BLDC fan (from an all dc inverter AC outdoor unit). with an mitsubishi s500 series VFD. Based on that, I believe it is possible. In such application, the motor runs like a AC syncron motor. Your main issue is to keep it in sync to the driving frequency in any operating point, but avoid core saturation. As experiment, I would try with the next settings: -Current limit 1.2 times higher than rated current. (if rotor stalls, excessive current will rise the alarm) -Starting frequency 0 or as less as possible but not more than 1-2Hz -minimum frequency ~30Hz (maybe you can get it from users manual) -Maximum frequency ~80Hz (like above) -Maximum drive voltage 150V -V/F pattern linear -acceleration pattern linear -acceleration speed ~5s -deceleratin speed 2-3s If it runs good, inspect the current (from VFD) at a certain frequency (50Hz) start to lower the max voltage by 10V. (current will go down too) Go down until compressor stalls. Then start to rise the voltage by 10V check for current, and stop before it starts to rise dramaticaly (saturation of core->excessive loss of power). The next issue will be to control the eev (if you have it). For that I recommend you to buy a relatively cheap, compatible controller like dixell xev22 (I use it with sucess). Can be, it would be easyer to find a compatible indoor unit and hack that. This way you could use its own electronics. A friend of mine had sucess to replace indoor HX with BPHX without major modification of electronics. T. Last edited by takyka; 11-01-14 at 04:13 AM..

11-07-14, 05:45 PM	#79
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	how are you controlling the EEV? It sounds as if it is not following the evaporator temperature and pressure like it should. Do you have service valves for the suction and discharge lines of the compressor? Do you have a liquid line service valve? In all of my homemade units, I install all three so I can check temperatures and pressures of everything once the unit is filled. Without all three, you can only estimate or guess what is happening where. WAIT A MINUTE! Which one are you talking about? The one that you installed in August, or the one you just picked up? Last edited by jeff5may; 11-07-14 at 06:12 PM.. Reason: HMMMM

10-31-14, 05:33 PM	#71
WyrTwister Master EcoRenovator Join Date: Jun 2013 Location: USA Posts: 543 Thanks: 6 Thanked 44 Times in 38 Posts	My limited understanding of a mini split DC inverter motor is the motor is really DC , but electronics switch the DC to various poles to produce rotation of the stator . My experience with VFD's has been with mostly " normal " three phase squirrel cage induction motors . I think the current technology is pulse width modulation to end up with a current that varies in voltage , amperage and frequency . Different ways of going about producing varying speed and torque . I have seen premium chillers that employ VFD's & three phase motors . They are said to be the " next step up " in energy efficiency . Although there may be something else that is the current latest and greatest ? God bless Wyr PS VFD's are also used in pumps and Air Handler Units , in the HVAC world .

11-01-14, 09:58 AM	#74
stef110 Helper EcoRenovator Join Date: May 2014 Location: Holland Posts: 58 Thanks: 6 Thanked 3 Times in 3 Posts	Yesterday i had a look on the compressor, and indeed there stand DC motor. Which will be a BLDC motor. I wont want to run it with a vfd, because it is not made for that i don't want to risk. The niceness would be to find an indoor unit and use that electronics. The other side is that i love to work with electronic's and it would be awesome if i can create my own BLDC driver for this compressor. Tomorrow i will dismantle the unit a bit more so that i can hopefully read more specs on the compressors data plate. keep you posted. stef

11-04-14, 02:11 PM	#76
stef110 Helper EcoRenovator Join Date: May 2014 Location: Holland Posts: 58 Thanks: 6 Thanked 3 Times in 3 Posts	This weekend i dismantled the unit so i could clean it up, it probelby was standing some were in a garden it had a hole bunch of sand in it. I also had a good look a the used components, and right now i am busy trying to investigate how i can control everything. It's gone be a hard job but i want to give it a try. I manage to power up the daikin outdoor circuit board. So i could measure some power lines right now i know the source voltage's of the fan and the inverter. I have to create a 300vdc power supply for the fan motor and inverter. The 4way valve is running on 120vdc and the eev just works on 12vdc. Yesterday i also picked up a recovery unit suitable for r410a stef

11-07-14, 12:56 PM	#77
stef110 Helper EcoRenovator Join Date: May 2014 Location: Holland Posts: 58 Thanks: 6 Thanked 3 Times in 3 Posts	mmm there are some strange things happening on my heatpump. It happen t a few times now, that the refrigerant that is entering the evaporator (outdoor radiator) doesn't catch any heat. The temperature of de refrigerant that is leaving the evaporator is the same as going in. Compressor uses less power as normal, and output heat is less then normal. On the outdoor unit is no sign of frog or anything. Could this have to do something with the amount of refrigerant in the system. it only happens when it is cold outside. stef

11-08-14, 01:11 AM	#80
stef110 Helper EcoRenovator Join Date: May 2014 Location: Holland Posts: 58 Thanks: 6 Thanked 3 Times in 3 Posts	sorry i was not that specific. Indeed i am talking on the already running unit with the capillary tube. I don't have a service valve on the suction side of the compressor. stef