METHOD FOR DETERMINING THE INDUCTANCES OF A PERMANENT MAGNET SYNCHRONOUS MACHINE

• US 20110101900A1
• Filed: 06/23/2009
• Published: 05/05/2011
• Est. Priority Date: 07/01/2008
• Status: Active Grant

• Current Assignee: Schneider Toshiba Inverter Europe SAS (Toshiba Corporation)
• Original Assignee: Schneider Toshiba Inverter Europe SAS (Toshiba Corporation)
• Inventors: Basic, Duro, Capitaneanu, Stefan, Malrait, Francois
• Granted Patent: US 8,519,650 B2
• Time in Patent Office: Days
• US Class Current: 318/400.09
• CPC Class Codes: H02P 21/14 Estimation or adaptation of machine parameters, e.g. flux, current or voltage
• CPC Class Codes: H02P 2203/01 Motor rotor position determination based on the detected or calculated phase inductance, e.g. for a Switched Reluctance Motor
• CPC Class Codes: H02P 2207/05 Synchronous machines, e.g. with permanent magnets or DC excitation
• CPC Class Codes: H02P 27/08 with pulse width modulation
• CPC Class Codes: H02P 6/185 using inductance sensing, e.g. pulse excitation
• CPC Class Codes: H02P 6/186 using difference of inductance or reluctance between the phases

Abstract

The invention relates to a control method implemented in a variable speed drive for determining the inductances (Ld, Lq) of a permanent magnet synchronous machine comprising three phases (a, b, c), each oriented along a direction, a stator, and a rotor. For each phase, one after the other, said method includes steps of: applying, along the direction of the phase (a, b, c), a voltage vector (V1, V3, V5) in the positive direction and a voltage vector (V2, V4, V6) in the negative direction for a predetermined duration; measuring the current obtained in the phase after applying the voltage vectors in both directions; determining an angle (θ_r) for the position of the rotor in relation to the stator based on the measured current; and determining the flow (Ld) and torque (Lq) inductances of the machine based on the predetermined angle (θ_r).

Claims

1. A control method implemented in a variable speed drive for determining the flux and torque inductances of a permanent magnet synchronous machine comprising three phases, each oriented in a direction, a stator and a rotor, said method comprising steps of:

applying, in the direction of each phase of a voltage vector in a positive direction and of a voltage vector in a negative direction for a predetermined duration,

measuring a current response in each phase after applying the voltage vectors in the two directions, the current response comprising, for each phase, a positive peak and a negative peak,

determining an angle for the position of the rotor in relation to the stator based on the asymmetries between the positive peaks and the negative peaks of the current responses measured in all the phases,

determining the flux and torque inductances of the machine as a function of the determined angle.

2. The method as claimed in claim 1, wherein, for each phase, the voltage vector applied in the positive direction and the voltage vector applied in the negative direction have one and the same norm.

3. The method as claimed in claim 1, wherein, for a phase, applying the voltage vector in the positive direction and of the voltage vector in the negative direction entails applying a voltage sequence comprising a positive voltage pulse of a predetermined pulse width, followed by a negative voltage pulse having two times the predetermined pulse width, followed by a positive voltage pulse of the predetermined pulse width.

4. The method as claimed in claim 3, wherein measuring the current response comprises measuring a positive current peak and a negative current peak and further comprising recovering, for each phase and at the same instants, two distinct current values on the positive current peak, in its upward phase and two distinct current values on the negative current peak, in its downward phase.

5. The method as claimed in claim 4, further comprising determining the following values:

6. The method as claimed in claim 5, wherein the angle is determined on the basis of the following relations:

Δ

I_diff=Δ

Ia_diff+Δ

Ib_diffe<sup>j2π

/3</sup>+Δ

Ic_diffe<sup>j4π

/3</sup>etθ

_r=arctan(Δ

I_diff)

7. The method as claimed in claim 6, wherein the flux and torque inductances of the machine are determined on the basis of the following relations:

8. A variable speed drive comprising a PWM-type inverter for supplying a pulsed voltage to a permanent magnet three-phase synchronous machine, said drive being configured to perform the method defined in claim 1.