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Power Source of Sinusoidal Voltage and Variable Frequency

A problem encountered in practice is related to the generation of sinusoidal electrical voltage with variable frequency. Generating a variable frequency voltage can be used in different applications as well as in the testing of asynchronous motors. As is known the speed of asynchronous motors depends on the frequency of the power supply to maintain a roughly constant torque. Power voltage value depends on the asynchronous motor type. The power source proposed in the paper is based on two large blocks, namely: a DC/DC convertor and an inverter stage. The DC/DC convertor can generate an output DC voltage of 310V or lower from an input DC voltage of 12 V. The output voltage of the DC/DC converter can be applied then to the inverter power stage obtaining in this case a sinusoidal voltage with amplitude close to 310 V and adjustable frequency. The circuit described in the paper was developed to be used in the learning process of the students that follow study programs in the field of electronics engineering.