A steady-state minimum loss control method and system for a linear induction motor

Abstract

The invention discloses a method and a system for controlling steady state minimum loss of a linear induction motor. The method comprises the steps of firstly, collecting the primary currents iA and iB as well as the speed v2 of the linear induction motor, and obtaining a secondary angular frequency omega r by means of v2; using a direct magnetic field orientation method to obtain the secondary flux linkage amplitude psi dr and flux linkage angle theta 1 of the motor by means of the iA, the iB and the omega r, and using coordinate transformation to obtain primary d-axis current ids and primary q-axis current iqs by means of the theta 1, the iA and the iB; obtaining electromagnetic thrust F in combination with a voltage equation and a flux linkage equation; obtaining an optimal flux linkage value psi <*> dr based on the F and the omega r, comparing the psi dr, the omega r, the ids and the iqs respectively with the corresponding psi <*> dr, omega <*> r, the i <*> ds and the i <*> qs, and then carrying out PI adjustment to obtain primary d-axis current controlled quantity i <*> ds, primary q-axis current controlled quantity i <*> qs, primary d-axis voltage controlled quantity u <*> ds and primary q-axis voltage controlled quantity u <*> qs; then, carrying out coordinate transformation and space vector pulse width modulation (SVPWM), and controlling an inverter to drive the linear induction motor to operate. The method and the system can rapidly calculate the optimal flux linkage needed by the minimum loss control for the linear induction motor in an online way, thus reducing the motor loss under different working conditions and increasing the motor operating efficiency.

Description

technical field [0001] The invention belongs to the technical field of linear induction motors, and more specifically relates to a method and system for controlling steady-state minimum loss of linear induction motors. Background technique [0002] Linear induction motors can generate direct thrust without mechanical transmission structure, and have the advantages of simple structure, large acceleration and deceleration, small mechanical loss, and less maintenance, so they are widely used in industrial fields, such as urban rail transit, servo systems, conveyor belts, etc. . [0003] However, due to the special structure of the primary disconnection and the unequal width of the primary and secondary, the linear induction motor has longitudinal edge effects and transverse edge effects (collectively referred to as edge effects) during operation. The edge effect will lead to drastic changes in motor parameters, deterioration of operating performance, increase in loss, and decr...

AI Technical Summary

Problems solved by technology

Affected by the edge effect, the parameters of the linear induction motor change complicatedly, and there is serious coupling between the parameters, so it is difficult to obtain an accurate loss model

For linear induction motors, there is currently no relatively comprehensive and practical loss model and minimum loss control method

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