Digital adaptive sensorless commutational drive controller for a brushless DC motor

A brushless DC motor controller that comprises:

• a set of comparators each configured to determine a voltage polarity on a respective winding of a stator;
• and
• a clocked digital circuit configured to receive polarity signals from the comparators, configured to detect in the polarity signals zero crossings having expected crossing directions, and configured to determine a commutational sequence for energizing windings on the stator based at least in part on zero crossings, but only those zero crossings having the expected crossing directions,
• wherein the clocked digital circuit samples a polarity signal before a lockout period and compares the sample to the polarity signal after the lockout ends, and wherein the clocked digital circuit generates a zero crossing indication if the sample does not match the polarity signal after the lockout ends.

A brushless DC motor controller that comprises:

• a set of comparators each configured to determine a voltage polarity on a respective winding of a stator;
• and
• a clocked digital circuit configured to receive polarity signals from the comparators, configured to detect in the polarity signals zero crossing having expected crossing directions, and configured to determine a commutational sequence for energizing windings on the stator based at least in part on zero crossings, but only those zero crossings having the expected crossing directions, wherein the clocked digital circuit includes:
• a first counter configured to count a number of cycles of a clock signal between detected zero crossings of the polarity signals;
• and
• a second counter configured to receive a count from the first counter and to count down from said count at approximately twice the rate of the clock signal, and
• wherein the clocked digital circuit is configured to advance the commutational sequence when the second counter rolls over.

A brushless DC motor controller that comprises:

• a set of comparators each configured to determine a voltage polarity on a respective winding of a stator;
• and
• a clocked digital circuit configured to receive polarity signals from the comparators, configured to detect in the polarity signals zero crossings having expected crossing directions, and configured to determine a commutational sequence for energizing windings on the stator based at least in part on zero crossings, but only those zero crossings having the expected crossing directions,
• wherein the clocked digital circuit accepts one or more limit inputs and is configured to inhibit advancement of the commutational sequence in a direction associated with the limit signal.

A method of driving windings in a DC motor, the method comprising:

• receiving with a clocked digital circuit, polarity signals indicative of whether voltages on windings of the DC motor exceed a threshold voltage, wherein the clocked digital circuit is configured to operate in temperatures exceeding 150° C.;
• measuring intervals between transitions of the polarity signals in predicted directions;
• and
• advancing a commutation state at a delay of some fraction of measured intervals after transitions of the polarity signals.

An integrated device that comprises:

• a processor core;
• and
• an integrated motor controller coupled to the processor core by an internal bus,
• wherein the integrated motor controller is configured to receive signals indicative of back EMF polarity on undriven windings of a DC motor to perform directional zero crossing detection, wherein the integrated motor controller determines a commutational sequence based on those zero crossings that only occur in anticipated directions, and
• wherein the integrated motor controller includes one or more limit inputs configured to halt advancement of a commutational sequence in a predetermined direction.