Reversible two phase motor controller

摘要

A controller for a bi-directional two phase motor incorporates an anti-dead point circuitry to prevent the motor locking at a dead point when the direction of rotation of the motor is reversed without bringing the motor to a standstill. The anti-dead point circuitry comprises two timers TMR1, TMR2. TMR1 counts down a time period when it is triggered by either a signal from a Hall sensor or by a direction changed signal. Timer 2 times down a preset time period once timer 1 has timed out. During the timing out of timer 2, the motor is switched off. In an alternative embodiment (Fig. 4) by resetting the first timer with a signal from the Hall sensor turning the motor off momentarily should the time taken to complete a revolution exceed a predetermined time period thereby the number of false triggerings by the anti-dead point circuitry is reduced. In a further aspect a two phase bi-directional motor comprising a stator having first and second phase windings, (L1, L2, Fig. 2) a permanent magnet rotor, control circuitry for selectively energizing the phase windings including a Hall sensor (H1) positioned adjacent the permanent magnet rotor for detecting rotation of the rotor, power MOSFETs (DT1, DT2) for connecting the phase windings to a source of power and a direction selection switch, the direction selection switch provides a logical signal indicative of desired direction and this signal is used in the control of the power MOSFETs.