Constant voltage driver - stepping motor---------- - - - - -- - - - - -Plus resistance drive step motor winding use coarse wire, coil resistance value Rw is very small, in each phase coil series external resistance R, in order to limit winding through the current is less than the rated current I, winding through the current limiting, the method of series can be used to reduce the power supply voltage and external resistance R of the two methods. Assuming that stepper motor coil inductance L, winding resistance for Rw, electrical time constant for & tau; , plus the resistance R, electrical time constant formula is as follows: & tau; =L/(Rw+R）。 Plus resistance to time constant & tau; Smaller, current rise faster, so that the stepper motor drive pulse frequency quickens, for no external resistance with external resistance R of the comparison of current rising curve, the t1 time, there is no resistance R, current rise to I1, only have a resistance R, current rise to I2, make high speed when the torque is greatly improved; The disadvantage is that copper loss increased. In recent years, using the constant current chopper driver, constant pressure method is not commonly used.
