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Download 3-Phase PM Synchronous Motor Vector Control Using
Transcript
Vector Control Drive Concept 3-phase BLDC Power Stage U_Dc bus Line AC AC PC Master Software UP DOWN 6 PMSM LOAD DC START STOP Quadrature Encoder Temperature Faults Isa Isb Isc PWM SCI SCI Driver GPIO PWM GPIO GPIO Driver PWM Driver Application Control Us_d Current d PI Controller Decoupling FieldWeakening Controller Us_q (Back-EMF feedforward) Speed Controller Current q PI Controller Us_d Is_d QT Driver Sector Us_alpha_comp Us_beta_comp Position & Speed Sensing Us_alpha Inverse Park Transformation d, q -> alpha, beta DCBus Ripple Compensation Forward Park Transformation alpha, beta -> d, q U_dcb Us_beta sin cos theta_actual_el Is_a_comp Is_beta Is_q Us_q ADC Driver Is_a Is_b Is_c Sinus Waveform Modulation Is_q_Req Omega_Req Quad Timer Duty Cycle A Duty Cycle B Duty Cycle C U_dcb Omega_Req Omega_actual_mech PWM Driver Break Control Fault Protection ADC PWM GPIO Driver Is_alpha Forward Clark Transformation a, b, c -> alpha, beta Is_b_comp Is_c_comp Current Sensing Processing Omega_actual_mech 56F80x / 56F8300 plus LMDC Figure 4-1 Drive Concept The control process follows: When the Start command is accepted (using the RUN / STOP Switch or PC master software command), the required speed is calculated according to the UP / DOWN push buttons or PC master software commands. The required speed proceeds through an acceleration / deceleration ramp, and a reference command is put to the speed controller. The actual speed is calculated from the pulses of the Quadrature Encoder. The comparison between the required speed command and the actual measured speed generates a speed error. Based on the error, the speed controller generates a current, Is_qReq, which corresponds to torque. A second part of stator current Is_dReq, which corresponds to flux, is given by the Field-Weakening Controller. Simultaneously, the stator currents Is_a, Is_b, and Is_c are measured and transformed from instantaneous values into the stationary reference frame α, β, and consecutively into the rotary reference frame d-q (Park - Clarke transformation). Based on the errors between required and actual currents in the rotary reference frame, the current controllers generate output voltages Us_q and Us_d (in the rotary reference frame d-q). The voltages Us_q and Us_d are transformed back into the stationary reference frame α, β and, after DCBus ripple elimination, are recalculated to the 3-phase voltage system, which is applied to the motor. 3-Phase PMSM Motor Vector Control, Rev. 3 Freescale Semiconductor Preliminary 21
