Si01-406 Functions of Heat Pump ModelsFunctions and Control 292. Functions of Heat Pump Models2.1 Frequency PrincipleMain ControlParametersThe compressor is frequency-controlled during normal operation. The target frequency is set bythe following 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 operationInverter Principle To regulate the capacity, a frequency control is needed. The inverter makes it possible to varythe rotation 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 an increased refrigerant circulation. This leads to a higher amount of the heatexchange per unit. When the frequency decreases, the rotation speed of the compressor decreasesresulting in a 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)
