General Functions SiBE04-10120 Main Function1.3 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 temperatureAdditional ControlParametersThe target frequency is adapted by additional parameters in the following cases: Frequency restrictions Initial settings Forced cooling/heating operationInverter Principle To regulate the capacity, a frequency control is needed. The inverter makes it possible to vary the rotationspeed of the compressor. The following table explains the conversion principle:Drawing of Inverter The 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 variable frequency. When the frequency increases, the rotation speed of the compressor increases resulting in anincreased refrigerant circulation. This leads to a higher amount of the heat exchange per unit. When the frequency decreases, the rotation speed of the compressor decreases resulting in adecreased refrigerant circulation. This leads to a lower amount of the heat exchange per unit.A BCooling 50 class 102 3260 class 96 2871 class 84 28Heating 50 class 108 5460 class 98 4071 class 108 3450 Hz60 HzRefrigerant circulation rate (high)Amount of heatexchanged (large)Amount of heatexchanged (small)ACpowerfreq=constantmax. freq.= A HzDCpowerAmount of heatexchanged (large)Amount of heatexchanged (small)high flow fmin. freq.= B Hzfreq=variable capacity=variableRefrigerant circulation rate (low)high speedlow speed(R1226)SiBE04-101.book Page 20 Monday, October 15, 2001 3:08 PM
