A three-vector model predictive torque control method for three-level permanent magnet synchronous motor

Abstract

The invention discloses a three-vector model predictive torque control method for a three-level permanent magnet synchronous motor. The vector partition method is used to select the voltage vector, and the large vector among the candidate vectors of the three-level inverter is substituted into the value function. In order to determine the first optimal voltage vector, the sector is determined by the position of the first optimal voltage vector, and the second optimal voltage vector is substituted into three non-zero vectors in the sector where the first optimal voltage vector is located The value function is optimized, and the action time of the first optimal voltage vector, the second optimal voltage vector and the zero vector is combined to control the action of the three-level inverter, so that the first optimal voltage vector is optimized 27 times from the original Reduced to 6 times, this optimization process not only takes into account the selection of the two optimal voltage vectors, but also combines their action time to ensure that the selected two optimal voltage vectors can ensure the midpoint potential balance and lower switching frequency.

Description

technical field [0001] The invention relates to torque control of a permanent magnet synchronous motor, in particular to a three-vector model predictive torque control method for a three-level permanent magnet synchronous motor. Background technique [0002] Due to the advantages of simple structure, small size, high power density, high efficiency, and excellent operating performance, permanent magnet synchronous motors have been widely used in recent years, such as: transportation, extreme love single fields, driving fields of vehicles and ships, and as pumps Rotating mechanisms for class, compressors, high-precision servo systems, etc. Therefore, there are more and more studies on the control of permanent magnet synchronous motors. [0003] The existing permanent magnet synchronous motor control multi-purpose model predictive torque control, model predictive torque control is a classic control method in the finite set predictive algorithm, it is very suitable for permanen...

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Problems solved by technology

[0004] Compared with the two-level inverter, the three-level inverter has a smaller switching frequency and a wider range of vector selection. However, the midpoint potential balance problem needs to be considered in practical applications.

[0006] (1) In the existing model predictive control strategy, only one voltage vector with fixed size and direction can be obtained in each control cycle, but the actual reference voltage vector to be tracked is uncertain, so the output voltage vector cannot Effectively makes the feedback torque track the reference torque, which directly leads to large flux pulsation of the permanent magnet synchronous motor, unstable output torque pulsation, and poor steady-state performance of the motor

[0007] (2) There are too many switch states of devices with three-level or more-level topology, the calculation cost is too large, and there are complex redundant vectors, it is difficult to determine the switch sequence combination;

[0008] (3) The value function contains the midpoint potential control item, and the setting of the weight factor becomes more complicated, resulting in low control accuracy and complicated calculation;

[0009] (4) Multi-vector predictive control causes higher switching frequency and increases switching loss

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