US 2008/0157707 A1 · Electric Motor And Method Of Controllling Said Motor

Abstract

The invention relates to a sensorless electric motor and a method of controlling such an electric motor, which motor comprises a permanently magnetic rotor, a stator having at least one winding, and a power stage for influencing the current flowing through the winding. As a function of a predetermined commutation duration (T_K), a commutation period is defined, during which period the direction of the magnetic field generated by current flow through the winding is not modified, during which period a commutation completion operation (107) and a commutation initiation operation (109) take place, and which period starts at a first commutation instant (t_KN) and ends at a second commutation instant (t_KN+1); preferably, commutation timing is adjusted, based upon a value of induced voltage picked up at a currently non-energized one of the winding strands, during a plateau portion (108) of a winding voltage trace, located temporally between commutation instants.

Claims25

Dependent claims

A method of controlling an electric motor (10), which motor comprises

a permanently magnetic rotor (12),
a stator (14) having a winding (15), and
a power stage (40, 60) which influences the current (I1, I2) flowing through the winding (15),
which method comprises the steps of:
A) as a function of a desired commutation duration (T_K), defining a commutation period during which period the direction of a magnetic field generated by current flow through the winding is not modified, during which period a commutation completion operation (107) and a commutation initiation operation (109) take place, said commutation period starting at a first commutation instant (t_KN) and ending at a second commutation instant (t_KN1);
B) temporally outside the commutation completion operation and the commutation initiation operation, the winding (15) at least at times experiences a substantially constant current flow, and sensing a voltage signal (U1, U2) dependent on a voltage (U1_ind, U2_ind) induced in the winding (15);
and
C) modifying the commutation duration (T_K) as a function of the sensed voltage signal (U1, U2) in order to adapt said duration to the rotation speed of the rotor (12).

5 more elements

An electric motor which adjusts commutation timing based upon detected values of voltages induced in a motor winding, which motor comprises:

a permanently magnetic rotor (12),
a stator (14) having a winding arrangement (15),
at least one power stage (40, 60) which influences the current (I1, I2) flowing through the winding arrangement (15),
a voltage sensing apparatus (86, 90) for sensing a voltage signal (U1, U2) dependent on the voltage induced in the winding arrangement (15),
a target current value specifying apparatus (36) to which the voltage signal (U1, U2) is delivered, and which generates therefrom a target current value signal (I_SOLL1, I_SOLL2) controlling operation of the electric motor,
and a current regulation apparatus (48, 68) to which the target current value signal is delivered, and which influences the power stage (40, 60) in such a way that current (I1, I2) flowing through the winding arrangement (15) is a function of the target current value signal.

3 more elements

Dependencies are inferred from the claim text.

Electric Motor And Method Of Controllling Said Motor

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Electric Motor And Method Of Controllling Said Motor

Life of this patent

Abstract

Claims25