Switching power supply circuit diagram of new linear motor transportation system

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Overview:
According to the requirements of the new linear motor transportation system, a new switching power supply with two-stage buck structure is designed. The main circuit structure of the system, the device selection process, the control system and control strategy, the protection logic and the simulation model are given. According to the phenomenon of short-time uncoupling on the net side, corresponding preventive measures are proposed. Finally, it is confirmed by experiments that the system works stably and has good performance, which fully meets the requirements of the new linear motor transportation system.

China's Inner Mongolia Autonomous Region has now identified a total coal reserve of more than 700 billion tons, ranking first in the country, and its short-distance transportation mode is still mainly highway. However, this traditional mode of transportation has problems such as low efficiency, high cost and serious environmental pollution, and has increasingly become a key factor restricting the development of Inner Mongolia's coal industry. In this case, the new linear motor transportation system came into being. The new linear motor transportation system adopts linear motor propulsion, which has the advantages of strong climbing ability, small floor space, low construction cost, fast running speed, easy automatic control, no noise, no exhaust gas, low operation and maintenance, and low energy consumption. It is an ideal coal transportation method in the 21st century.

1 New Linear Motor Transportation System The new linear motor transportation system uses a three-phase PWM rectifier to supply 50 Hz, 10 kV AC, and the output bus is connected to the line contact network to provide 1500 V DC for the locomotive. The on-board traction converter converts DC 1 500 V into a three-phase variable voltage AC power with a rated voltage of 530 V, which is supplied to the primary coil of the linear motor to generate a traveling wave magnetic field. The secondary conductor plate is laid between the line rails, directly under the locomotive, and the current is induced in the conductor plate under the action of the traveling wave magnetic field, which interacts with the magnetic field of the primary coil to generate driving force and drive the locomotive to run. The vehicle traction controllers are connected to each other and communicate with the ground command center through the wireless network to control the running state of the locomotive. The overall structure of the new linear motor transportation system is shown in Figure 1.

The on-board switching power supply is responsible for powering all vehicle-mounted equipment such as traction converters, cooling fans, control systems, brake shoe relays, etc., requiring good performance, stability and reliability. Therefore, it is imperative to design a switching power supply that meets the requirements of the new linear motor transportation system.

2 switching power supply design

According to the system design requirements, the switching power supply input voltage is DC1 500 V, the output is DC24 V, and the power is 2 kW. In view of the small power, a higher switching frequency can be selected, which is advantageous for system miniaturization and light weight, improved efficiency, and reduced output harmonics. After analysis and experiment, the initial setting of the switching frequency is 15 kHz.

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