US 8,076,898 B2 · Method of brushless DC motor control and its application

Abstract

The invention relates to electric engineering, in particular to methods for controlling an ac electronic motor. The inventive control method consists in starting and rotating a rotor upon EMF signals in current-free sections of an armature winding, in converting the EMF signals into discrete logical level signals by a normalizer, in detecting switching points by means of a microcontroller and in displacing said points according to a load current quantity, the rotor speed of rotation and the inductance of the armature winding sections, wherein the switching points are calculated and displaced with respect to bridging times of the free sections EMF whose voltage levels are different from zero. The inventive device is characterized in that it comprises a reference level displacing unit (26), which is arranged in the normalizer between a divider 22 and a comparator unit (23) and which consists of a current sensor (27), a voltage sensor (27), two adders (29, 30) and an inverter (31).

Claims7

Dependent claims

A method of controlling a three phase motor wherein each phase of the motor is driven from first and second power terminals by a respective switch arrangement comprising:

a first switch and a first reverse diode connected in parallel between the first power terminal and a motor phase and a second switch and a second reverse diode connected in parallel between the second power terminal and the motor phase, the method comprising:
operating the first switch so as to disconnect the motor phase from the first power terminal while the motor phase is disconnected from the second power terminal;
determining a first time when a back-EMF of the motor phase crosses a non-zero reference back-EMF voltage level, which first time is earlier than a second time when the back-EMF next crosses a zero voltage level;
using the first time to determine a third time later than the first time;
and
operating the second switch so as to connect the motor phase to the second power terminal at the third time.

3 more elements

Dependencies are inferred from the claim text.

Method of brushless DC motor control and its application

Life of this patent

Method of brushless DC motor control and its application

Life of this patent

Abstract

Claims7