Table of Contents
DAMA-SM-21-003
3.2
Frequency Control
Outline
The compressor frequency is determined according to the difference between the room
thermistor temperature and the target temperature.
*
Only applicable for heat-pump model
Details
For Cooling Only model:
1. Determine command frequency
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
For Heat-pump model:
1. Determine command frequency
1.1 Limiting frequency by drooping function
1.2 Limiting defrost control time
1.3 Forced cooling
1.4 Indoor frequency command
2.
3.
4.
Functions and Control
Upper limit frequency
Command frequency
Initial frequency
Lower limit frequency
PI control
Defrost control*
Command frequency is determined in the following order of priority.
(1) Forced cooling
(2) Indoor frequency command
The minimum value is set as the upper limit frequency among the frequency upper limits of
the following functions:
Compressor protection, input current, discharge pipe temperature, freeze-up protection.
The maximum value is set as the lower limit frequency among the frequency lower limits of
the following function:
Pressure difference upkeep.
There is a certain prohibited frequency such as a power supply frequency.
Command frequency will be determined in the following order of priority.
Input current, discharge pipes, peak cutting, freeze-up protection, dew prevention, fin
thermistor temperature.
Determine upper limit frequency
Set a minimum value as an upper limit frequency among the frequency upper limits of the
following functions:
Compressor protection, input current, discharge pipes, peak cutting, freeze-up protection,
defrost.
Determine lower limit frequency
Set a maximum value as an lower limit frequency among the frequency lower limits of the
following functions:
Four way valve operating compensation, draft prevention, pressure difference upkeep.
Determine prohibited frequency
There is a certain prohibited frequency such as a power supply frequency.
When the shift of the frequency is less than zero (∆F<0) by PI control,
the target frequency is used as the command frequency.
FMAX
Skip control
Limit frequency
Four way valve operating compensation, etc*
FMIN
Control Specification
Dropping function
Input current control, etc.
Upper limit function
Compressor protection function
Target frequency
Lower limit function
33
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