Solar tracking system is used to track the position of sun
in order to get the maximum energy by aligned the solar
panel perpendicular to the incidence sunlight [1, 2, 3, 12, 13].
Solar panels need to move along with the direction of
sunlight during the tracking process. A DC motor driver is
needed to control the directions as well as the turning speed
of the solar panel. The maximum torque of the DC motor
decides the total amount of solar panels can be mounted on
the tracking system. The common limitation of the DC motor
driver is the speed is fixed and the default torque is set to
maximum. Logically, it is not preferable to set the motor in
high turning speed since Sun tracking is a slow process.
While setting the motor to operate at maximum torque causes
the system to consume the highest amount of power
constantly, regardless of the amount of load attached. It will
bring significant impact on the efficiency of the system, since
the energy consumed by the system is generated by the solar
panel itself. Research has been done that DC-DC buck
converter is used to step down the voltage in order to reduce
the turning speed of solar panel [4].
Fig.1. Block diagram of motor driver
However, the system reported has single speed only
without torque control. System proposed by V. Gupta
managed to control the torque by changing the duty cycle of
Pulse Width Modulation (PWM) signal that feed into the
low-side switching elements of the H-bridge circuit [5]. The
proposed DC motor driver shows that it is possible to make
both speed and torque adjustable. It brings great advantage to
the solar tracking system as the tracking speed can be
optimized according to the tracking condition. Moreover,
power consumption of the tracking system can be reduced
greatly since the DC motor driver supplies the amount of
torque just sufficient to move solar panels attached. An
addition current limiting circuit has been added in the motor
driver in order to limit the maximum amount of current that
can flow through the DC motor to avoid motor stall. Fig. 1
shows the block diagram of the proposed DC motor driver.