| 摘要 |
The circulating pump of a radiator system is operated at a speed which is dependent on the heating power in order to avoid consuming unnecessary energy when the radiators are turned down. The pump drive contains a converter which is supplied from the supply network and has a pulse-controlled invertor supplying an asynchronous machine. A constant, frequency-independent binary curve shape which is pulse-width modulated with a high-frequency sampling voltage is specified for the pulse-controlled invertor output voltage. In the case of the selected curve shapes (Fig. 3), the harmonics which are caused by the binary curve shape are in a region where they have no significant influence either on the losses in the invertor and the machine which are caused by harmonics or on the development of noise in the radiator system. A sampling frequency of over 5 kHz is required for the pulse-width modulation, which is possible as a result of the use of power transistors as the invertor switches. <IMAGE>
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