Short-circuit fault-tolerant control method based on deadbeat current tracking for five-phase permanent magnet motor with sinusoidal back-electromotive force or trapezoidal back-electromotive force

A short-circuit fault-tolerant control method based on a deadbeat current tracking for a five-phase permanent magnet motor with a sinusoidal back-electromotive force (EMF) or a trapezoidal back EMF, comprising the following steps:

• step 1:
• detecting a speed of the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF as a feedback speed ωm of the five-phase permanent magnet motor;
• comparing a given speed ω* with the feedback speed ωm to obtain a speed error er of the five-phase permanent magnet motor;
• calculating, by a proportional integral (PI) controller, a q-axis current of the five-phase permanent magnet motor according to the speed error er;
• and outputting, by the PI controller, a given q-axis current iq;
• step 2:
• compensating a short-circuit current, and analyzing and processing a short-circuit fault as an open-circuit fault;
• step 3:
• reconstructing reduced-order matrixes in a fundamental space and a third harmonic space under a single-phase short-circuit fault respectively;
• step 4:
• ignoring a reluctance torque, and obtaining torque expressions of the five-phase permanent magnet motor under the short-circuit fault in the fundamental space and the third harmonic space through the reduced-order matrixes respectively;
• step 5:
• constructing, for the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF, an expression of an extra torque ripple generated by an interaction of a short-circuit current and a short-circuit back-EMF;
• step 6:
• generating, through the torque expressions in the fundamental space and the third harmonic space, short-circuit suppression currents id1s, iq1s, iz1s, id3s, iq3s and iz3s to offset the extra torque ripple caused by the short-circuit current, wherein id1s, iq1s and iz1s are short-circuit suppression currents in the fundamental space, and id3s, iq3s and iz3s are short-circuit suppression currents in the third harmonic space;
• step 7:
• obtaining, for the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF, open-circuit fault-tolerant reference currents id1o, iq1o, iz1o, id3o, iq3o and iz3o to maintain a smooth output torque, through the given q-axis current iq and the torque expressions in the fundamental space and the third harmonic space under the short-circuit fault, wherein id1o, iq1o and iz1o are open-circuit fault-tolerant reference currents in the fundamental space, and id3o, iq3o and iz3o are open-circuit fault-tolerant reference currents in the third harmonic space;
• step 8:
• transforming the open-circuit fault-tolerant reference currents to maintain the smooth output torque and the short-circuit suppression currents on d1-q1-z1 axes in the fundamental space and d3-q3-z3 axes in the third harmonic space into a natural coordinate system through a coordinate transformation, and superposing the open-circuit fault-tolerant reference currents and the short-circuit suppression currents according to a superposition theorem;
• and transforming the open-circuit fault-tolerant reference currents and the short-circuit suppression currents integrated in the natural coordinate system to the d1-q1-z1 axes through an inverse matrix of a reduced-order transformation matrix in the fundamental space, thereby forming optimal short-circuit fault-tolerant reference currents idr, iqr and izr;
• step 9:
• constructing a discrete model for the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF under the short-circuit fault, and obtaining optimal fault-tolerant reference voltages udr, uqr and uzr under the short-circuit fault through deadbeat model predictive current control;
• and
• step 10:
• inputting the obtained optimal fault-tolerant reference voltages udr, uqr and uzr into a carrier-based pulse width modulation (CPWM) module through the coordinate transformation to obtain switching signals of phases;
• and inputting the obtained switching signals of the phases into an inverter to control the five-phase permanent magnet motor, thereby realizing a short-circuit fault-tolerant control of the five-phase permanent magnet motor.