Method and apparatus for estimating rotor position and for sensorless control of a switched reluctance motor

A discrete rotor position estimation method for a synchronized reluctance motor comprising:

• sensing a d.c.-link voltage Vdc and a phase current Iph;
• calculating a flux-linkage λph of an active phase from the sensed d.c.-link voltage Vdc and the sensed phase current Iph;
• comparing the calculated flux-linkage λph with either two or three reference flux-linkages such as λr1, . . . , corresponding to reference rotor angles θr1, . . . all of them lying between angles corresponding to aligned rotor position and non-aligned rotor position in the synchronized reluctance motor;
• typically obtaining rotor positions θcal1, . . . equal to θr1, . . . based on the comparison results, twice or thrice during the active conduction of a phase when the calculated flux-linkage λph is greater than the reference flux-linkages λr1, . . . .

A discrete rotor position estimation method for a synchronized reluctance motor comprising:

• sensing a d.c.-link voltage Vdc and a phase current Iph;
• calculating a flux-linkage λph of an active phase from the sensed d.c.-link voltage Vdc and the sensed phase current Iph;
• comparing the calculated flux-linkage λph with a reference flux-linkage λr, the reference flux-linkage λr corresponding to a reference angle θr which lies between angles corresponding to aligned rotor position and non-aligned rotor position of the synchronized reluctance motor;
• and
• calculating an estimated rotor position θcal from the calculated flux-linkage λph using either one of the inductance model or the flux linkage model of the active phase, only once during the active conduction of a phase when the calculated flux-linkage λph is greater than the reference flux-linkage λr.

A discrete rotor position estimation method for a synchronized reluctance motor comprising:

• sensing a d.c.-link voltage Vdc and a phase current Iph;
• calculating a flux-linkage λph of an active phase from the sensed d.c.-link voltage Vdc and the sensed phase current Iph;
• comparing the calculated flux-linkage λph with a reference flux-linkage λr, the reference flux-linkage λr corresponding to a reference angle θr which lies between angles corresponding to aligned rotor position and non-aligned rotor position of the synchronized reluctance motor;
• and
• calculating estimated rotor positions either twice or thrice during the active conduction of a phase such as θcal, . . . from the calculated flux-linkage λph using either one of the inductance model or the flux linkage model of the active phase, at every consecutive PWM interrupt when the calculated flux-linkage λph is greater than the reference flux-linkage λr.

An apparatus for estimating discretely a rotor position for a synchronized reluctance motor comprising:

• sensor operable to sense a d.c.-link voltage Vdc and a phase current Iph;
• section operable to calculate a flux-linkage λph of an active phase from the sensed d.c.-link voltage Vdc and the sensed phase current Iph;
• section operable to calculate the reference flux-linkage λr from the polynomial expression in phase current Iph;
• section operable to compare the calculated flux-linkage λph with the reference flux-linkage λr, the reference flux-linkage λr corresponding to a reference angle θr which lies between angles corresponding to aligned rotor position and non-aligned rotor position in the synchronized reluctance motor;
• and
• section operable to obtain an estimated rotor position θcal only once when the calculated flux-linkage λph is greater than the reference flux-linkage λr.

An apparatus for estimating discretely a rotor position for a synchronized reluctance motor comprising:

• sensor operable to sense a d.c.-link voltage Vdc and a phase current Iph;
• section operable to calculate a flux-linkage λph of an active phase from the sensed d.c.-link voltage Vdc and the sensed phase current Iph;
• section operable to calculate reference flux-linkages λr1, . . . from the polynomial expression in phase current Iph;
• section operable to compare the calculated flux-linkage λph with reference flux-linkages λr1, . . . the reference flux-linkages λr1, . . . corresponding respectively to reference angles θr1, . . . which lie between angles corresponding to aligned rotor position and non-aligned rotor position in the synchronized reluctance motor;
• section operable to obtain rotor positions θcal1, . . . based on the comparison result, twice or thrice when the calculated flux-linkage λph is greater than the reference flux-linkages λr1, . . . .

An apparatus for estimating discretely a rotor position for a synchronized reluctance motor comprising:

• sensor operable to sense a d.c.-link voltage Vdc and a phase current Iph;
• section operable to calculate a flux-linkage Xph of an active phase from the sensed d.c.-link voltage Vdc and the sensed phase current Iph;
• section operable to calculate the reference flux-linkage λph from the polynomial expression in phase current section operable to compare the calculated flux-linkage λph with a reference flux-linkage λr, the reference flux-linkage θr corresponding to a reference angle θr which lies between angles corresponding to aligned rotor position and non-aligned rotor position of the synchronized reluctance motor;
• and
• section operable to calculate an estimated rotor position θcal from the calculated flux-linkage λph using either one of the inductance model or the flux linkage model of the active phase, only once when the calculated flux-linkage λph is greater than the reference flux-linkage λr.

An apparatus for estimating discretely a rotor position for a synchronized reluctance motor comprising:

• sensor operable to sense a d.c.-link voltage Vdc and a phase current Iph;
• section operable to calculate a flux-linkage λph of an active phase from the sensed d.c.-link voltage Vdc and the sensed phase current Iph;
• section operable to calculate the reference flux-linkage λr from the polynomial expression in phase current Iph;
• section operable to compare the calculated flux-linkage λph with two or three reference flux-linkages λr1, . . . the reference flux-linkages λr1, . . . respectively corresponding to reference angles θr1, . . . which lie between angles corresponding to aligned rotor position and non-aligned rotor position of the synchronized reluctance motor;
• and
• section operable to calculate estimated rotor positions θcal1, . . . either twice or thricefrom the calculated flux-linkage λph using either one of the inductance model or the flux linkage model of the active phase, at every consecutive PWM interrupt when the calculated flux-linkage λph is greater than the reference flux-linkage λr1, . . . .

An apparatus for estimating discretely a rotor position for a synchronized reluctance motor comprising:

• section operable to detect a phase inductance of the synchronized reluctance motor;
• section operable to identify an minimum region of the phase inductance during turn-on of an active phase;
• section operable to determine a rotor position θapp from the identified minimum region, as an estimated rotor position θcal;
• and
• section operable to obtain the incremental rotor angle Δθ from θapp.