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Guys,
I need some help in understanding IPM circuits and how they control a DC Inverter Compressor. Im familiar with all the circuits, but cant seem to nail down the sequence of operation once DC Voltage gets to the IPM. and how it affects compressor speed. I would like to be able to troubleshoot the compressor and the IPM circuit to determine which is at fault. I would love to find some books on the subject. Any ideas please.
As said in the other thread, the system controls what the IPM does, and that's not released publically, as they are all company secrets, but it depends on discharge temp, air temps and coil temps and inside temp setpoint by end user.Quote:
Originally Posted by Husky250
You don't need that to troubleshoot a IPM or compressor anyway, all you need to know is whether the IPM or compressor is faulty.
To test a faulty compressor, you need a very accurate milli-ohm meter to measure windings. To test it's electrical insulation you need a megger tester.
The inside of the IPM is attached, common failures of these are the diodes shown, so you need to test them with the diode function on you mulimeter. Also by measuring the voltage output across the IPM outputs when the compressor is starting to see if they're balanced.
But if you buy a inverter tester that many manufacturers sell, you can test the IPM without measuring all the diodes, plus have the ability to check the controller "firing order" so to speak
Thank you the information. I guess I will purchase one of the testers. I didnt have much luck checking voltage across the IPM. I could get the unit to start, but before the meter would read the unit would fault out. I guess from the compressor not being connected. Im brand new to this concept of controls of compressor speed and capacity. I look forward to learning all I can!
you can check the voltage with the compressor still connected.
You didn't say you had a troublesome unit, just that you wanted more general information.
But anyway, you do have enough time to check voltages, as the normally try to run for a while them give up, then try again 3 min later, and repeat the cycle again before they give up. But like I said, you need a good meter that records min max, as the start up voltages aren't constant, they fluctuate a lot, so you will never know if they are even unless your multimeter records min-max.
But yes, an inverter checker plugged in instead of the compressor is the easiest way to diagnose, and the most foolproof. Other ways depend on the equipment, and as each one is different, "tricks of the trade" for that brand and general inverter experience are required.
If an IPM is faulty, do not plug in a new one without doing an insulation test with a megger. A megger tester is mandatory in testing the compressor. A compressor can short out enough to blow an IPM but not show a fault with a normal mulimeter.
Thank you for the insight, Im starting to learn the sequence. I figure its the best way to learn these types of controls. I would rather learn the right way than just change parts until it runs. My unit is just a test unit. I currently have a complete condenser. Connected to it I only have wiring and a Indoor board and transformer. All coil thermistors are in place, with a wired remote to turn it on. No Indoor coil at all. This unit will never run in the field, only intended to test and learn. This system was scrap so I thought I would wire it up and learn. With the information you helped me with it will be alot easier!
Another dumb question......Why are the terminals marked U-V-W?
Hello husky well its a silly thought have you tried to run the comp without the IPM inline,
wire it DOL through a overload contactor ? maybe you cant do that seeing as its a dc intverter comp ?
also maybe the IPM has a reverse phase protection so it tries to start but doesnt show the fault up ? just a suggestion, also have you made sure that all three phases neutral and a good earth are there.
good luck declan
I think it is just how those engineers chose to label the three phases from an inverter.Quote:
Another dumb question......Why are the terminals marked U-V-W?
I was wondering about that. I've always been told when you reverse any two legs on a three phase motor it reverses the rotation of the motor. Does it do the same on the inverter system thats running a simulated three phase?
Star 882 I see you are in the US.....What state?
Yes.Quote:
I was wondering about that. I've always been told when you reverse any two legs on a three phase motor it reverses the rotation of the motor. Does it do the same on the inverter system thats running a simulated three phase?
Texas.Quote:
Star 882 I see you are in the US.....What state?
On both, AC and DC, you shouldn't reverse the legs of motor, because they are either rotary or scrolls and cannot work in reverse.Quote:
Originally Posted by Husky250
There is actually a two capacity compressor that uses two cylinders, a 3 phase motor, and a single phase inverter along with a single phase power supply. The crankshaft is designed such that one of the pistons only reciprocates when it is running in one direction. The inverter is referenced to one of the supply lines and outputs a waveform out of phase with the incoming AC such that one phase is supplied direct from line, another from the inverter, and the third between the inverter and line. A logic signal to the inverter can change the phase order, thereby changing the direction of rotation and therefore the capacity of the compressor.Quote:
On both, AC and DC, you shouldn't reverse the legs of motor, because they are either rotary or scrolls and cannot work in reverse.
Thanks to everyone!
What is make of that compressor? Do you have any link or technical description?Quote:
Originally Posted by star882
Inverter: Conversion from DC to AC.Quote:
Originally Posted by Husky250
This should help in your understanding about inverter circuit. Please refer to the attached file:
guys what do think of the difference in power consumption and savings of those AC and DC Inverters?
which is more efficient and a cost saver?
thank you very much