inverter vs digital scroll comparison[1]

Number one to the customer !Profitable Growth B3X

LG MULTI V Plus Ⅱ systemVs

Digital scroll system

LG MULTI V Plus Ⅱ systemVs

Digital scroll system


Compression

Cycle

LoadingLoading

UnloadingUnloading

Cycle

Compression

■ Animation

Next Next Next

Fixed rotation(60hz or 50Hz)

• Digital scroll compressor is the constant compressor and refrigerant bypass type.

It means that even on the partial load, Compressor rotates continuously with fixed RPM and

refrigerant just goes back to suction pipe without compression. COP is too low.• However Inverter compressor controls the RPM of motor on the partial load.

Digital scroll System Principle

RefrigerantBy-pass

RefrigerantDischarge


Working principle of PWM (Pulse Width Modulation)

PWM ValvePWM Valve

■ Animation

Next Next Next

By PWM valve’s on/off,

loading and unloading

is controlled.

• Reliability of solenoid valve

• Noise

• Low energy efficiency

in partial load

[ Weak point ]

Digital scroll System Working


- 100% operation : Loading 20s & Unloading 0s



※ Cycle time : 20s

The cycle of Loading / Unloading as shown below repeats according to operation rate.

Efficiency is very low on the partial load because of invalid working.

time

50% Operation90% Operation

20S 20S 20S

18S 18S 18S

2S 2S 2S

Loading : ( 18 sec / 20 sec )

Unloading : ( 2 sec / 20 sec )

time

20S 20S 20S

10S 10S 10S

10S 10S 10S

Loading : ( 10 sec / 20 sec )

Unloading : ( 10 sec / 20 sec )

50% Loss Low efficiency



PWM VALVE

on

PWM VALVE off

Unloading Loading

Cycle time = 20s

PWM VALVE

on

Compression

Unloading means that when engine cycles 2000 RPM, and then suddenly the clutch pedal is released. It is like idling of an engine. You can hear the high level idling noise. In case of digital scroll compressor, high frequency noise occurs during unloading time.

idling of an engine Output of power of Engine idling of an engine

RPM RPM RPM high frequency Noisehigh frequency Noise



S/ValveS/Valve

Off Loading

On Unloading

※ Decreasing Reliability by so many on/off times

Re

liab

ility

On/Off times

Operation of s/valve Reliability of Valve

Reliability

* S/valve must be on/off 1 time in 20 sec except full operation

* During 12hr/day for 2 year operation, s/valve repeats on/off almost 1.6 million times.

* the durability of general valve is 1~2 millions.

Digital scroll System Issues

Owing to the often on/off of solenoid valve, the reliability can be decreased by time.Solenoid valve is a mechanical part. It can be damaged by abrasion or clogging.

Reliability of Solenoid valve


Scroll compressor is a high precision assembly.As repeating on/off of s/valve, upper fixed scroll would repeat as well.As a result, reliability and capability will decrease due to abrasion of equipment.

Fixed ScrollUp and Down

Gap

Digital scroll System Issues

Reliability of compressor


In order to control the cycle of Loading & Unloading, every 2seconds increases until 20 seconds.Total is 11 steps. After all, not linear control, step control.

20%

100%

High LowLoad

Cap

acity

Step controlStep control

Loading : 20 sec

Loading : 0 sec

Loading : 4sec

Loading : sec

Loading : 12 sec

Loading : 16 sec

Linear control(Inverter Comp.)

Basic Comparison Control

System control method


Usually CAC is not operated under full load condition. Operating method under partial load of bypass type scroll compressor




※ Cycle time : 20s

It’s not the direct control

of motor RPM.

0 20 40 60 80 100 120 140 160 180

Capacity (100%)

LGDC Scroll (Inverter)

Bypass type Scroll

Eff

icie

ncy

Operation Range

Basic Comparison Control

Part Load operation method

inverter vs digital scroll comparison[1]

Documents