A control strategy and modulation method for a four-quadrant converter of a direct-drive permanent magnet electric locomotive

Abstract

The invention belongs to the technical field of electric locomotive traction control, and specifically relates to a control strategy and a modulation method for a four-quadrant converter of a direct-drive permanent magnet electric locomotive. The present invention adopts a double-closed-loop control strategy with intermediate DC bus voltage feedforward, the outer loop is a voltage control loop, and a PI controller is used to control the DC bus voltage; the inner loop is a current control loop, and a PR controller is used to control the AC side current control; when the DC bus voltage exceeds the set threshold, the DC bus feed-forward amount is directly given to solve the problem of unstable output of the PI controller due to bus oscillation; the modulation adopts the SHEPWM strategy, and the present invention is in the SHEPWM pulse generation process Among them, the comparison value method is adopted, compared with the traditional forced method, it can effectively reduce the switching angle action delay, realize SHEPWM pulse generation with high precision, effectively eliminate specific harmonics, and reduce the low-order harmonic content of the network measurement current .

Description

technical field [0001] The invention belongs to the technical field of electric locomotive traction control, and specifically relates to a control strategy and a modulation method for a four-quadrant converter of a direct-drive permanent magnet electric locomotive. Background technique [0002] As the core unit of the electric locomotive traction drive system, the four-quadrant converter provides a stable DC voltage for the inverter unit under the traction condition of the locomotive. Kinetic energy is fed into the power grid to realize bidirectional flow of energy. The traditional single-phase four-quadrant converter adopts the double-closed-loop control method of voltage and current based on PI controller. For high-power occasions, due to the large control inertia, the four-quadrant adjustment speed is slow under the condition of sudden load switching, which is easy to cause intermediate The DC bus oscillates, which in turn leads to bus overvoltage or undervoltage faults;...

AI Technical Summary

Problems solved by technology

The traditional single-phase four-quadrant converter adopts the double-closed-loop control method of voltage and current based on PI controller. For high-power occasions, due to the large control inertia, the four-quadrant adjustment speed is slow under the condition of sudden load switching, which is easy to cause intermediate The DC bus oscillates, which in turn leads to bus overvoltage or undervoltage faults; on the other hand, the switching frequency of the four-quadrant converter is low when it is working, which may cause large harmonics on the grid side of the converter and affect the control performance of the vehicle

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