International Appliance Manufacturing 2008 - (Page 21) its INVERTERS’ range to lower power levels thus covering the power range of practically all the rangehoods available on the market today. These inverters come in power ranges of 150W to 300W. There is another product for applications up to 60W also targeting residence ventilation. This product family takes advantage of the extensive experience ATech has in designing and manufacturing applicationspecific electronics for 3-phase AC-induction motors, single phase induction motors and Brushless motors (both DC-trapezoidal and AC sinusoidal). At first sight, an inverter – sophisticated technology regarded as expensive – may seem to be too much for a rangehood. However, in order to meet the challenging cost target (a key characteristic of a rangehood inverter), ATech designed the product around a very costeffective microcontroller and applied a proprietary technology for the power part. From the practical point of view, the inverter is an addition to the wiring of the hood. Due to its limited size of approximately 50 cubic centimetres, it is easy to find an area to install the electronic board. The existing serial communication is easily connected to more sophisticated user interfaces of high-end products. As the technology is sensorless, there is no need to change anything on the motor. The inverter technology enables a stepless speed/aspiration setting thus allowing the user to set the exact speed. The results show a significantly improved user experience as this overcomes the most typical dilemma of the few preset speed levels on the majority of today’s rangehoods – to choose between a too noisy setting with excessive aspiration or a noise acceptable setting not providing enough aspiration. ATech’s inverters are being used mostly in combination with PSC motors present in midand high-end products. The use of the inverter allows the rangehood manufacturer to use a single winding motor, which, in practice, means the use of more economical motors in comparison with commonly used 3-winding motors. The advanced driving algorithm also allows the accurate monitoring of the motor performance, which allows implementing advanced status detection. The inverter senses changes in motor load and elaborate this data to identify Consequently, the application of the inverter on an existing product does not bring any major design or purchasing changes to the product. Performances of systems using inverters are predominantly influenced by the motor design. It must be pointed out, however, that the improvements made possible by the use of the inverter are limited, especially if the manufacturing level and the motor design are poor. Additional Benefits In addition to efficiency, the use of the inverter on Shaded Pole AC (SPAC) motors and Permanent Split Capacitor (PSC) motors has other advantages, as well. The use of the inverter can provide nominal aspiration increase using the same motor as the FIELD WEAKENING principle allows the motor speed to increase over its nominal speed. International Appliance Manufacturing 2008 21
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