Invertor size for a refrigerator

rkentzel wrote:

Perhaps you should post a few model numbers of those supposed "three phase" home fridges?

I would only expect that type of "technology" in an extreme "high end" close to commercial type fridge. Certainly not going to happen in ANY household fridge sold at most normal consumer outlets like Home Depot, Lowes and such.

Well your wrong GE Samsung, LG, Kitchen Aid, Whirlpol,Frigidaire. I am not going to post model numbers to many. One poster has shown he or she owns a GE momnogram with inverter 3 phase compressor. I have replaced several inverter boards on some Samsungs due to defective capacitors.

The power supplies like what would be used to drive a heavy duty three phase motor drive USE the exact same principles as any other switching power supply.

First, the 120V AC is rectified through a full wave bridge rectifier, that is brute force filtered with some healthy capacitors (470 mf at 400V DC) which produces 160-170V DC unfiltered and unregulated voltage (has some 120hz ripple).

Second, the DC voltage is then chopped at high frequency then run through a high frequency transformer, then rectified and final filtering.

Third, the now filtered voltage goes to the "three phase" motor drive outputs which often are nothing more than PWM SQUARE WAVES.

YOUR overall "feeling" that a three phase motor drive can not be run on a good quality MSW inverter is an OPINION not based on facts but because you "replaced" "bad caps" on some drive boards.

"Bad caps" happen in ANY electronic items and can not solely blamed by the use of a MSW inverter. In fact 100% of the UPS units on the market ARE MSW and have been since the 1990s.

Computer power supplies are switching power supplies and are not damaged by the use of MSW nor are they damaged by square wave inverters (yep, the early computer UPS units were in fact SQUARE WAVE output, I personally repaired the early UPS units back in the day).

Not to mention many people tend to gravitate to the CHEAPEST inverter which may not have enough surge capacity available to reliably start a motor under load.

I should also point out that MANY if not all RV manufacturers which offer 120V home fridges in fact USE MSW inverters to power those fridges. However they are not using $29 1000W MSW inverters...