| CPC H02P 21/18 (2016.02) | 5 Claims |
|
1. A fast rotor position estimation method of a permanent magnet motor based on a N-division approach, comprising:
step 1: converting three-phase stator currents of the permanent magnet motor sampled at each period by a coordinate transform to obtain stator currents in a dq two-phase synchronous rotation coordinate system, with which an initial position area of the permanent magnet motor's rotor position is determined;
step 2: establishing a stator current cost model of the permanent magnet motor, wherein a d-axis stator current of the permanent magnet motor in the dq two-phase synchronous rotation coordinate system is inputted into the stator current cost model, and an initial rotor position of the permanent magnet motor is outputted, wherein the initial rotor position of the permanent magnet motor and its initial position region are iteratively optimized by the N-division approach to obtain an estimated rotor position and its final position region, and thereby the rotor position of the permanent magnet motor is quickly estimated,
wherein in step 1:
the three-phase stator currents of the permanent magnet motor sampled at each period is converted by coordinate transform to obtain the stator currents of the permanent magnet motor in the dq two-phase synchronous rotation coordinate system,
wherein A-phase stator currents ia, B-phase stator currents ib and C-phase stator currents ic of the permanent magnet motors are converted by coordinate transform to obtain the a-axis stator currents iα and b-axis stator currents iβ in the ab two-phase stationary coordinate system, respectively,
wherein the d-axis stator current id and q-axis stator current iq in the dq two-phase synchronous rotation coordinate system are obtained by the coordinate transform with a-axis stator current iα and b-axis stator current iβ, and
wherein the initial position region of the permanent magnet motor's rotor position is determined according to the polarity of a-axis stator current iα, b-axis stator current iβ and q-axis stator current iq,
wherein in step 2:
the initial rotor position and its initial position region of the permanent magnet motor are iteratively optimized to obtain the estimated rotor position and its final position region of the permanent magnet motor using the N-division approach, wherein a position region obtained in a current iteration is (1/(N−1)) of a position region obtained in a last iteration, wherein the estimated rotor position obtained by an iteration is as follows:
 where θi is a rotor position estimation value of the permanent magnet motor in the ith iteration, q(i+1)1 and q(i+1)N are the first and Nth rotor position control variables of the permanent magnet motor's rotor position estimation value in the (i+1)th iteration, respectively,
wherein an optimization is completed after M iterations, and a final estimated rotor position of the permanent magnet motor θ(k) is (q(M+1)1+q(M+1)N)/2,
wherein the first and Nth rotor position control variables of the permanent magnet motor's rotor position estimation value in the (i+1)th iteration are:
 where θij is the jth rotor position control variable of the permanent magnet motor in the ith iteration, idij(k) is the d-axis stator current in the dq two-phase synchronous rotation coordinate system of the permanent magnet motor at the kth sample period under the ith rotor position control variable in the ith iteration, iq(k) is the q-axis stator current in the dq two-phase synchronous rotation coordinate system of the permanent magnet motor at the kth sample period,
wherein θij, the ith rotor position control variable of the permanent magnet motor in the ith iteration, is shown as follows:
 where θiN and θi1 are the Nth and first rotor position control variables of the rotor position estimation value for the permanent magnet motor in the ith iteration, respectively.
|