About Inverter Compressor: Starting Current

Click For Summary

Discussion Overview

The discussion revolves around the starting current requirements of inverter compressors in refrigerators, particularly in the context of using solar inverters for off-grid applications. Participants explore the types of motors used in these compressors and the implications for power supply ratings.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that traditional induction motors require approximately 5 times the rated power for starting, suggesting a need for a minimum inverter rating of 1000W for a 200W refrigerator.
  • Another participant speculates that inverter-based drives may have soft start functionality, potentially resulting in lower inrush current, but suggests that induction motors are still likely used due to cost considerations.
  • A participant expresses concern that piston-style compressors may require full torque at zero speed, indicating that an inverter-based fridge could help but may not be designed to handle the necessary energy in the DC link effectively.
  • One participant reiterates the concern about starting torque and current requirements, mentioning that while inverter VFD compressors are becoming more common in energy-efficient appliances, starting issues can still arise.
  • Another participant highlights the historical use of AC induction motors in compressors and notes the transition to inverter technology in modern appliances.

Areas of Agreement / Disagreement

Participants express differing views on the starting current requirements and the types of motors used in inverter compressors. There is no consensus on the exact nature of the starting current or the effectiveness of inverter technology in addressing these issues.

Contextual Notes

Participants acknowledge the complexity of starting current requirements and the potential variations in design and performance among different refrigerator models. Some assumptions about motor types and starting profiles remain unverified.

Who May Find This Useful

Individuals interested in off-grid solar power solutions, appliance design, or energy efficiency in refrigeration may find this discussion relevant.

Anand Sivaram
Messages
90
Reaction score
43
If we would like to go completely off-grid with a Solar inverter:

Normal refrigerators use induction motors for compressors and these induction motors do require around 5x starting current. So, if we use a refrigerator with rated power of 200W, we would require an inverter/power supply rating of minimum 1000W. Otherwise there is chance that the inverter/power supply could trip.

What about refrigerators using modern Inverter Compressors? What type of starting current do they take? What type of motors these Variable Frequency Drive based Inverter Compressors use - Induction or Synchronous AC motors?
 
Engineering news on Phys.org
At a guess you'd think inverter based drive would have softstart functionality, ie lower inrush, as far as machine types go, I'd bet that its still using the very cheap to make induction machine.
 
  • Like
Likes   Reactions: Anand Sivaram and Asymptotic
I am pretty sure that the fridge compressors are piston style, that is part of the issue, the compressor may need full torque at "zero" speed, or it may fail to start. An inverter based fridge MAY help, but all of the energy in this start then needs to be in the DC link - I doubt it was built to do this due to the cost.

Best bet is to ask the manufacturer for a start profile. If you explain your situation properly, and they are a customer focused company they should, eventually, get you the answer.
 
  • Like
Likes   Reactions: Anand Sivaram
Windadct said:
I am pretty sure that the fridge compressors are piston style, that is part of the issue, the compressor may need full torque at "zero" speed, or it may fail to start. An inverter based fridge MAY help, but all of the energy in this start then needs to be in the DC link

It used to be a standard AC induction motor based on/off compressors, but nowadays many of the 5-star energy efficient refrigerators and ACs are using Inverter VFD compressors.
 
Yes - but the starting torque, may still need a large amount of current - ran into this problem in residential AC, it can be done but it is difficult AKA expensive. The starting process, I believe was patented ( in that case).
 

Similar threads

Self excited induction generators and grid connected solar inverters?
  • · Replies 9 ·
Replies
9
Views
2K
Net metering - hybrid solar inverter system question
  • · Replies 9 ·
Replies
9
Views
2K
12V DC Motor in Light Fixture with Dimmer & 12V DC to 110V AC Inverter
  • · Replies 21 ·
Replies
21
Views
3K
Can RCCB trigger falsely when it is in line with induction motors?
  • · Replies 28 ·
Replies
28
Views
4K
Grid tied micro hydro using Pump As Turbine
  • · Replies 7 ·
Replies
7
Views
3K
Connect grid tied solar inverter to DC+ Bus of VFD?
  • · Replies 84 ·
3
Replies
84
Views
18K
Design choices for running an Electric train (and network)?
  • · Replies 6 ·
Replies
6
Views
2K
Relay Control of Induction Motors
  • · Replies 5 ·
Replies
5
Views
2K
Driving three phase induction motor with single phase supply
  • · Replies 3 ·
Replies
3
Views
2K
Engineering Difficulty in Understanding Inverter Terms
  • · Replies 2 ·
Replies
2
Views
1K