A DC motor is used to spin a DVD inside a DVD player The mot

A DC motor is used to spin a DVD inside a DVD player. The motor is rated e 12V, 6000RPM. Reading a DVD requires that the rotation rate vary from 570 RPM (when reading data near the edge of the disc) to 1600 RPM (when reading data from m the center of the disc). If you wish to control the speed of the DVD through pulse wid modulation, what is the range of duty cycles that you must run the motor at to match the specs for the DVD system?

Solution

Ans) Voltage proportional to speed in DC motor

so for 12 V------6000 RPM

for 570 RPM voltage required is (12/6000)*570=1.14 V

so Voltage V1=1.14 V

Duty ratio=V1/V=1.14/12=0.095=9.5%

----------------------------------------------------------------------------------

for 1600 RPM voltage required is (12/6000)*1600=3.2 V

so Voltage V2=3.2 V

Duty ratio=V2/V=3.2/12=0.27=27%

------------------------------------------------------------

so range of duty cycle is from 9.5%(0.095) to 27% (0.27) for speed range of 570 to 1600 RPM