Patent EP-3809578-A1 (EP)
Title: Method for starting a synchronous motor
Inventor: KALYGIN ANDREY
IPC: H02P1/04
Filed: 2019-10-15
Abstract: The invention relates to a method (600) for starting a synchronous motor (102). The synchronous motor (102) comprises a rotor (112) for creating a first magnetic field and a stator (108) with stator windings (110) connected to an electrical energy converter (104) for converting a supply voltage ( V   cc ) into a stator voltage ( V   sx   , V   sy ,  V   sz ) to be applied to the stator windings (110) to create a rotating second magnetic field interacting with the first magnetic field. The method (600) comprises the following steps: applying (610) reference stator voltages ([          V   sx     *                       V   sy     *                       V   sz     *             ]) to the stator windings (110), wherein the reference stator voltages ([          V   sx     *                       V   sy     *                       V   sz     *             ]) are determined from a reference current vector ([          i   sd     *   *                       i   sq     *   *             ]) and a reference rotor speed (          ω   r     *   *             ); measuring (620) stator currents ( i   sx ,  i   sy ) in the stator windings (110); calculating (630) an estimated rotor speed (ω̃   r   ) and an estimated rotor position (θ̃   r   ) of the rotor (112) from the applied stator voltages ( V   sx , V sy , V sz ) and the measured stator currents ( i   sx ,  i   sy ); calculating (640) a speed error ( ω e   ) by subtracting the estimated rotor speed (ω̃   r   ) from the reference rotor speed (          ω   r     *   *             ); determining (650) a reference torque producing current component (          i   sq     *   *             ) from the speed error ( ω e   ) and modifying the reference current vector            i   sd     *   *             i   sq     *   *                with the reference torque producing current component (          i   sq     *   *             ); calculating (660) a position error ( θ e   ) by subtracting the estimated rotor position (θ̃   r   ) from a reference rotor position (          θ   r     *             ), wherein the reference rotor position (          θ   r     *             ) is determined from the reference rotor speed (          ω   r     *   *             ) and a reference rotor speed correction ( ω c   ), wherein the reference rotor speed correction ( ω c   ) increases and decreases with the position error ( θ e   ); correcting (670) the reference current vector            i   sd     *   *               i     sq     *   *                by transforming the reference current vector            i   sd     *   *               i     sq     *   *                into a corrected reference current vector            i   sd     *               i     sq     *                by the position error ( θ   e ), wherein a rotating coordinate system (dq) of the corrected reference current vector            i   sd     *               i     sq     *                is aligned with the estimated rotor position (θ̃   r   ); determining (680) switching signals ( s   1   , s   2   , s   3 ) for the electrical energy converter (104) from the reference stator voltages            V   sx     *               V     sy     *               V     sz     *                and applying the switching signals ( s   1 ,  s   2   , s   3 ) to the electrical energy converter (104).