Swisens AG as a startup company, develops and produces measuring instruments to
determine the air quality in real-time applications. The measuring stations are exposed
to the daily weather conditions and must be air-conditioned. The actuators are operated
in on-off mode, which causes strong vibrations and noise emissions.
Within the scope of this diploma thesis, a concept for variable speed control of singlephase
induction motors (SPIM) should be developed and subsequently validated and
verified. The prototype should also provide a simple communication interface which can
be used for data transfer with an external device.
The following bachelor thesis describes the development of the concept for the manufactured
prototype and provides test results for verification and validation.
The presented controller-board combines a line filter and a Power Factor Correction
(PFC) in the input stage. The output stage is characterized by eight half-bridge circuits
which can be used individually for the variable speed control of the SPIM’s. In addition, a
filter is located at the output of the inverter stage to reduce voltage pulses. An algorithm
is presented to generate the switching signals on the Microcontroller Unit (MCU) and
control the gate drivers. The implemented RS485 interface can be used for data exchange
with an external device.
The developed prototype can be used to test the air conditioning unit with variable
speed control and offers a useful starting point for further development steps.