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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
Number one to the customer !Profitable Growth B3X
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
Number one to the customer !Profitable Growth B3X
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
Number one to the customer !Profitable Growth B3X
- 100% operation : Loading 20s & Unloading 0s
- 90% operation : Loading 18s & Unloading 2s
- 50% operation : Loading 10s & Unloading 10s
※ 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
Digital scroll System Working
Number one to the customer !Profitable Growth B3X
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
Digital scroll System Working
Number one to the customer !Profitable Growth B3X
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
Number one to the customer !Profitable Growth B3X
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
Number one to the customer !Profitable Growth B3X
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
Number one to the customer !Profitable Growth B3X
Usually CAC is not operated under full load condition. Operating method under partial load of bypass type scroll compressor
- 90% operation : Loading 18s & Unloading 2s
- 50% operation : Loading 10s & Unloading 10s
- 30% operation : Loading 6s & Unloading 14s
※ 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