Never heard or knew of that one. Won't dropping the voltage due to a SMPS also reduce the motor torque significantly?Hi EL,
Another approach is to use a switch mode power supply (SMPS) and control the output voltage of the SMPS.
As Ian implies, the problem with controlling a motor using a linear technique is power loss. If, for example, you reduced the voltage of a four horse power motor from 12V to 6V, the motor power would drop to one quarter (1HP) and the dissipation in the linear element dropping the voltage would also be 1HP or 750Watts.
With a switching technique, either pulse width modulation or SMPS, the power loss in the element dropping the voltage would theoretically be zero. In practice about 85W would be dissipated in the voltage dropping element.
If you used a simple resistor in series with the motor to control the speed, not only would a lot of power be lost in the resistor but also, due to the relatively high source impedance seem by the motor, the motor torque would be extremely limited.
Yes it will ultimately, but the torque should be normal up to the point where Vin/motor ESR is reached. Obviously if you half the supply volts you quarter the maximum possible torque, all to a first approximation of course.Never heard or knew of that one. Won't dropping the voltage due to a SMPS also reduce the motor torque significantly?