DC - Readiness of a vacuum cleaner

Abstract

This paper proposes a way to supply a vacuum cleaner from a DC grid instead from an AC grid. Problems caused by the transition from an AC supply to a DC supply will be discussed, like the high inrush current during turn-on and the arc that occurs when a mechanical switch is used to turn-off. These problems will be solved in a low-cost manner. Therefore, a power MOSFET is used to control the motor of the vacuum cleaner. A simple PWM controller is used to control the MOSFET, thus the motor. This PWM controller limits the inrush current with a current sensing feature which turns the PWM controllers output OFF when the peak-current exceeds the threshold value. Furthermore, the ON/OFF button of the vacuum cleaner is also connected to the PWM controller. Turning off the vacuum cleaner will also turn off the output of the PWM controller. Because of this the motor will gradually slow down, the current is regulated towards zero and this prevents a current arc. A prototype was build inside the housing of the vacuum cleaner to validate the design. The experimental tests prove the functionality of the circuit by testing the control of the motor and current sensing feature. Finally, de result of the tests will be discussed and recommendation for possible improvements or alternative designs will be given.