Abstract—DC brushed motor (abbreviated as DC motor later)
has some outstanding advantages for example cheap and control
easy compared to other types of motor. It has already been
widely used in industrial machines and household appliances. In
many applications of DC motor, the speed of the DC motor is
often a basic required to be measured parameter. To achieve this
purpose, a direct speed measuring method which a speed sensor
with suitable dimension or resolution needs to be coupled with
the axis of DC motor and leads to more complicated mechanical
structure and control circuit should be included in equipment.
Moreover, if the setup place of the speed sensor is insufficient, the
direct speed measuring method is then not allowed to be used.
The current parameter is one of the independent variables of DC
motor. Many important dynamic behaviors of the DC motor will
be characterized by this parameter. In this paper, we will
propose a new speed measurement of DC motor based on a
sensorless speed method. In order to verify the feasibility of our
proposed method, we test and compare the measured motorspeed
values of electric-spray pump by using the conventional
speed measuring method (couple a speed sensor with rotating
axis of DC motor) and the proposed sensorless speed measuring
method, respectively. The experimental measured results show
the method that the speed measurement of DC motor is read and
calculated based on the frequency of ripple component of the
motor current is actually feasible.