Speed control of the compressor

[Peter_1]

Further to the thread Cheap Inverter Checker in another section, I have some questions for those having some knowledge of the electronic power PCB's in airco's.

Varying the speed with an industrial VFD is known (like Danfoss, Telemecanique, GE, ..)

We use those often on racks/packs.

More specific, how's the speed controlled in the latest Daikin and Mitsubishi Electric compressors? These are DC compressors, is this right?

On both units, you have a power control module which controls the speed of the compressor. Does someone know what type of signal is given to regulate the speed?

For a test, I want to use an external signal which I control myself connected to the Power PCB to play with the speed of the compressor from a Daikin and a Mitsubishi.
This is not for a common airco application. If I destroy it due to a too high or too low speed, then that's my problem.

On a Daikin VRV, they increase speed to - I think - 250 Hz (so this can't be a DC motor because you vary the voltage to the stator and the rotor)
Is this the same for a Mitsubishi?

Does someone know a link explaining the technique of varying the speed of the compressor on modern compressors?

[Peter_1]

I'm speaking about the smaller units till 7 to 9 kW.

[Peter_1]

Found a general link for the Daikin product http://www.freepatentsonline.com/20060103342.pdf or posted at http://download.yousendit.com/DD9C548A38B65366

[Peter_1]

A schematic of the internal of the compressors should also be fine.

[Peter_1]

For those interested in electronics, a good link http://www.maxim-ic.com/tarticle/article.cfm#2

[Thermatech]

Japan factory enginners try to keep as much technical detail secret to slow down the coppiers in places like china & Korea.
Diakin & Mitsubishi still use 3 phase compressor motor in VRV / VRF products. But the motors are confusingly called D/C motors. But I think that is short for digitally comutated or some such fancy name. The VRF systems still use inverters to generate 3ph to the compressor at veriable hz.
But I think the windings are optamised for inverter slow ramp up start zero to 30 hz. Because if you connect 3ph 50 hz direct to the compressor it draws a massive amps & trips the power supply mcb. But again dont expect to get any technical data for the motor windings unless do dont mind being suspected as industial spy.

[nike123]

Download this RAR and extract. You (and others) wil find there Poverpoint presentation that explain some of yours questions.

http://www.mediafire.com/?6jklhym2mcg

[nike123]

Japan factory enginners try to keep as much technical detail secret to slow down the coppiers in places like china & Korea.
Diakin & Mitsubishi still use 3 phase compressor motor in VRV / VRF products. But the motors are confusingly called D/C motors. But I think that is short for digitally comutated or some such fancy name. The VRF systems still use inverters to generate 3ph to the compressor at veriable hz.

This is not true as you may see from presentation I posted.

But I think the windings are optamised for inverter slow ramp up start zero to 30 hz. Because if you connect 3ph 50 hz direct to the compressor it draws a massive amps & trips the power supply mcb. But again dont expect to get any technical data for the motor windings unless do dont mind being suspected as industial spy.

IPM circuit regulate maximum current, therefore there is no need to "windings optimization". When rotary compressor starts with low frequency, resistance to the turning is little, as a result current is smaller, and how the frequency become larger also resistance to the turning is larger and also current of compressor.

[davidk]

DC is a short form for BLDC (BrushLess DC Motor). These are in fact synchronous motors, but they are called DC because the motor and its inverter act just like a permanent magnet DC motor in which the collector and brushes are replaced by an electronically commutation device (inverter) .
Inside the motor, on the shaft, there are 3 hall sensors which tells the inverter when to commute the current into the appropriate phase. This hall sensors and the inverter replaced the collector.

[hendry]

This is not true as you may see from presentation I posted.



IPM circuit regulate maximum current, therefore there is no need to "windings optimization". When rotary compressor starts with low frequency, resistance to the turning is little, as a result current is smaller, and how the frequency become larger also resistance to the turning is larger and also current of compressor.

i do not agree. they are still very secretive even old technology. most literature is still in japanese eventhough they might have plenty international office. they still keep 1 japanese natiional taking charge of that offices.

[nike123]

i do not agree. they are still very secretive even old technology. most literature is still in japanese eventhough they might have plenty international office. they still keep 1 japanese natiional taking charge of that offices.

Sorry for misunderstanding. I was referring at this part of your statement:

Diakin & Mitsubishi still use 3 phase compressor motor in VRV / VRF products. But the motors are confusingly called D/C motors. But I think that is short for digitally comutated or some such fancy name. The VRF systems still use inverters to generate 3ph to the compressor at veriable hz.