Conversion of geared DC motor into stepper motor using switching delay time signals

Abstract

In solar tracking system, general stepper motor is used to control the stepwise movement and low speed of solar panel in vertical motion. Degree of rotation is directly proportional to stepwise movement (stepping method) of stepper motor. But it is cumbersome process to hold a solar panel at a particular vertical position depending on the sun’s position using low cost stepper motors. So, geared DC motor is implemented into stepper motor for low-speed applications using Stepping Method (GDCSM). Degree per step movement of geared DC motor is identified using Step angle switching delay time signal (A) of microcontroller. Speed of geared DC motor is controlled by passing fixed time interval between the pulses where the pulses have fixed width. Controlling speed is implemented by using Step delay time signal (D) of microcontroller. Combining effect of switching delay time signals A and D represents the Stepping Method. Stepping method resembles the step movement and controlling speed of the stepper motor. Speed of 10RPM & 30RPM geared DC motors is operated at 10V DC power supply. Microcontroller ATmega 328P with switching delay time signals is used to control the geared DC motors. Performance of 10RPM & 30RPM GDCSM is analyzed with stepper motors in terms of Relative slip degree error per revolution (RES) and acceptable slippage degree tolerance under open loop condition. Change in consuming voltage tolerance (Δ) during rotation of GDCSM is another parameter which is used to maintain the constant actual total step count per revolutions of GDCSM. At 40 ms of step angle delay time (A), 10RPMGDCSM has 120 steps per revolution. At 25 ms of A, 30RPMGDCSM has 55 steps per revolution. Speed of 10RPM & 30RPM GDCSM is controllable up to 2RPM when its RES or acceptable slippage degree tolerance value is less than or equal to 1%. If Δ value of GDCSM is less than or equal to − 0.4%, then it behaves like stepper motor. GDCSM is suitable to hold and control vertical position of solar tracking system with low speed and step movement. Performance of geared DC motor experimentally showed better result than commercial available stepper motors like 28BYJ-48 or STP-43d1027-01.