Main Functions SiUS12-81424 Function and Control1. Main FunctionsNote: Check the list of functions applicable to different models.1.1 Frequency PrincipleMain ControlParametersThe compressor is frequency-controlled during normal operation. The target frequency is set by thefollowing 2 parameters coming from the operating indoor unit: The load condition of the operating indoor unit The difference between the room temperature and the set temperatureAdditionalControlParametersThe target frequency is adapted by additional parameters in the following cases: Frequency restrictions Initial settings Forced cooling / heating operationInverter Principle To regulate the capacity, frequency control is needed. The inverter makes it possible to vary therotation speed of the compressor. The following table explains the conversion principle:Drawing ofInverterThe following drawing shows a schematic view of the inverter principle:Phase Description1 The supplied AC power source is converted into the DC power source for the present.2 The DC power source is reconverted into the three phase AC power source with variablefrequency. When the frequency increases, the rotation speed of the compressor increases resultingin increased refrigerant circulation. This leads to a higher amount of heat exchange perunit. When the frequency decreases, the rotation speed of the compressor decreasesresulting in decreased refrigerant circulation. This leads to a lower amount of the heatexchange per unit.50 Hz60 HzRefrigerant circulation rate (high)Amount of heatexchanged air (large)Amount of heatexchanged air (small)ACpowerfreq=constantDCpowerAmount of heatexchanged air (large)Amount of heatexchanged air (small)high flow ffreq=variable capacity=variableRefrigerant circulation rate (low)high speedlow speed(R2812)
