US 8,148,928 B2 · Method for starting a brushless sensorless DC motor

Abstract

A method for starting a brushless DC motor. A rotor is aligned with a stator in accordance with a predetermined phase. After alignment, the rotor is positioned in accordance with another phase, two phases are skipped, a timer is set to a first count time, and the rotor is aligned with the stator in accordance with a third phase. Then the timer is restarted and the rotor is aligned with the stator in accordance with a fourth phase. After a first delay, first back electromotive force value is stored. The timer is stopped when the first back electromotive force value substantially equals a peak amplitude of opposite polarity. The timer is updated to a second count time that is substantially equal to a time at which the second timer was stopped. The process is repeated until the rotor has a position and a velocity that are suitable for normal operation.

Claims22

Dependent claims

A method for starting a brushless DC motor, comprising:

setting a value of a variable to a first time;
setting a value of a timer to a third time;
generating a first summed current that flows from a first node to a second node until the third time is greater than the first time, wherein a first portion of the first summed current flows from the second node to a third node and a second portion of the first summed current flows from the second node to a fourth node;
generating a second current that flows from the first node to the second node and to the fourth node;
after a first delay, storing a first back electromotive force value;
generating a first sampled value by sampling the timer at a second time when the first back electromotive force value substantially equals one of a first peak amplitude or a divided value equal to a quotient of the first peak amplitude divided by a first divisor;
and
adjusting the value of the variable towards the first sampled value.

5 more elements

A method for starting a brushless DC motor using at least twelve phases, comprising:

aligning a rotor to a stator, wherein the stator includes first, second, and third inductors, each of the first, second, and third inductors having first and second terminals;
skipping at least one phase of the at least twelve phases;
setting a value of a variable to a first time and a value of a timer to a second time;
applying a source of operating potential to the first terminals of the first and third inductors and applying a first voltage signal to the first terminal of the second inductor in a third phase;
removing the source of operating potential from the first terminal of the third inductor in a fourth phase when the value of the timer is greater than the value of the variable;
after a first delay, storing a first back electromotive force value;
generating a first sampled value by sampling the timer at a second time when the first back electromotive force value substantially equals one of a first peak amplitude or a divided value equal to a quotient of the first peak amplitude divided by a first divisor;
and
adjusting the value of the variable towards the first sampled value.

6 more elements

Dependencies are inferred from the claim text.

Method for starting a brushless sensorless DC motor

Life of this patent

Method for starting a brushless sensorless DC motor

Life of this patent

Abstract

Claims22