MTPA based method for parameterless and position-sensorless control of a permanent magnet synchronous motor

A maximum-torque-per-ampere (MTPA) based control method for a parameterless and position-sensorless control of a permanent magnet synchronous motor, the method comprising:

• 1) calculating a target dr-axis current value Idr and a target qr-axis current value Iqr of a target current vector {right arrow over (Idq)} in a (dr, qr) rotor reference frame by using a target current value Idq of the target current vector {right arrow over (Idq)} and a preset current-rotor angle γ;
• wherein the preset current-rotor angle γ is an angle between the target current vector {right arrow over (Idq)} and the qr-axis of the (dr, qr) rotor reference frame;
• the (dr, qr) rotor reference frame is a first (d, q) rotating reference frame that is rotating in synchronism with the rotating magnetic field, and the rotor position is aligned with the dr-axis of the (dr, qr) rotor reference frame;
• the target current value Idq is input by a user or obtained by using the real-time phase current values Ia, Ib, and Ic of a real-time current vector {right arrow over (Iabc)};
• and the preset current-rotor angle γ is input by the user;
• 2) looking up a target voltage-rotor angle α or a target voltage-current angle β through a MTPA look-up table by referring to the target dr-axis current value Idr and the target qr-axis current value Iqr;
• wherein the target voltage-rotor angle α is measured between the dv-axis of α (dv, qv) voltage reference frame and the dr-axis of the (dr, qr) rotor reference frame;
• the (dv, qv) voltage reference frame is a second (d, q) rotating reference frame that is rotating in synchronism with the rotating magnetic field, and a target voltage vector {right arrow over (Vdq)} is aligned with the qv-axis of the (dv, qv) voltage reference frame;
• the target voltage-current angle β is measured between the target voltage vector {right arrow over (Vdq)} and the target current vector {right arrow over (Idq)};
• and the MTPA look-up table is obtained in the MTPA mode and comprises correspondences between the target dr-axis current value Idr, the target qr-axis current value Iqr, the preset current-rotor angle γ, the target voltage-rotor angle α, and the target voltage-current angle β;
• 3) calculating a PI error Δ by using the target dr-axis current value Idr, the target qr-axis current value Iqr, the target voltage-rotor angle α, the target voltage-current angle β, and the real-time phase current values Ia, Ib, and Ic;
• and obtaining a target voltage value Vdq of the target voltage vector {right arrow over (Vdq)} by regulating the PI error Δ through a PI controller;
• 4) obtaining a target voltage angle θv of the target voltage vector {right arrow over (Vdq)}, wherein the target voltage angle θv is measured between the target voltage vector {right arrow over (Vdq)} and the A-axis of the orthogonal (A, B) stationary reference frame;
• the target voltage angle θv is obtained by using the target dr-axis current value Idr, the target qr-axis current value Iqr, the target voltage-rotor angle α, and the real-time phase current values Ia, Ib, and Ic, or obtained by using a given rotating speed value Spd of the rotor;
• and
• 5) calculating a target A-axis voltage value VA and a target B-axis voltage value VB in the orthogonal (A, B) stationary reference frame by using the target voltage value Vdq and the target voltage angle θv through the inverse Park transmission, converting the target A-axis voltage VA and the target B-axis voltage VB into target phase voltage values Va, Vb, and Vc, and modulating PWM signals of the inverter by using the target voltage values Va, Vb, and Vc, for regulating the real-time phase current values Ia, Ib, and Ic.