To ensure that the battery power supply meets emergency power supply needs in case of high-speed train failure, including emergency lighting, emergency display, maintenance power, communication and control, etc; It should also meet the requirement that when a faulty high-speed train is rescued, the faulty high-speed train should wait for rescue for 5 hours (considering necessary loads) and 1 hour for coupling and braking tests on the basis of the 2-hour emergency power supply mentioned above, and start the self generating function after the rescue operation begins. The management of battery load plays an important role in the operation of high-speed trains, continuously improving the overall operational safety of high-speed trains. This paper has certain guiding significance for the operation of high-speed trains.

Keywords: EMU battery load management

To ensure that the battery power supply meets the emergency power supply requirements in the event of a failure of the high-speed train, emergency ventilation should be maintained for at least 90 minutes, and the remaining emergency power can be maintained for 2 hours, including emergency lighting, emergency display, maintenance power, communication and control, etc; It should also meet the requirement that when a faulty high-speed train is rescued, the faulty high-speed train should wait for rescue for 5 hours (considering necessary loads) and 1 hour for coupling and braking tests on the basis of the 2-hour emergency power supply mentioned above, and start the self generating function after the rescue operation begins. Perform battery load management.

I. Overview

The low-voltage load power supply system of the high-speed train is mainly composed of a charger and a battery, which are respectively arranged under the TC01 and TC08 cars. There are a total of 4 sets of 200AH lithium battery batteries installed in the entire train, with a capacity of 800AH. The low-voltage power supply bus is divided into three circuits, BN1, BN2, and BD. BN1 and BN2 busbars belong to intermittent power supply busbars, which are controlled on and off by the driver's cabin battery knob; The BD bus belongs to the uninterrupted power supply bus. Low voltage load management is controlled by TCMS and managed in four stages: 0-5 minutes, 5-30 minutes, 30-90 minutes, and 90-120 minutes. After 120 minutes, according to the requirements, the battery will be powered off and support BD bus power supply, emergency lighting, and other work for 5 hours. The drag mode load will work for 1 hour, and the self generating load will work for 15 minutes. When the charger stops working and the TCMS network detects that the battery capacity is below 30%, the undervoltage protection relay is triggered to achieve primary protection of the battery. If the battery needs to continue discharging, the control short-circuit device in the TC01 and TC08 vehicle electrical cabinets should be disconnected. If the battery level is below 10%, the battery management system BMS controls the main contactor of the battery to disconnect, achieving the second level protection of the battery.

2、 Emergency time prediction

During the rescue process of the high-speed train, the BP rescue conversion device needs continuous power supply to ensure that the braking system function of the high-speed train is available. Based on the analysis of real cases of high-speed train rescue in the early stage, the longest waiting time for rescue is no more than 8 hours. Therefore, with 8 hours as the upper limit of the waiting time for the rescue of the high-speed train, the battery needs to have the following power supply capabilities, and the operating conditions are as follows:

① Normal discharge for 0-2 hours, ensuring that emergency lighting and train broadcasting systems can be maintained for 2 hours, and emergency ventilation can be maintained for 1.5 hours;

② After 2 hours, turn off the battery, and the direct load (BD) such as the brake control module and emergency lighting should work normally for 5 hours, waiting for locomotive rescue;

③ After the rescue locomotive arrives, the high-speed train enters drag mode, the safety loop CIR、 The tail lights and other loads start, and the rescue locomotive undergoes a coupling test. The battery needs to be discharged for 1 hour;

④ After the rescue locomotive is started, it accelerates to over 50km/h, and the high-speed train can start its self generating function. The acceleration time is about 15 minutes, and the medium voltage power supply of the train is normal. The battery enters the charging state.

According to the above requirements, when a malfunction occurs in the high-speed train and rescue occurs, the maximum discharge time of the battery is 2+5+1+0.25=8.25 hours, and the battery enters the charging state after 8.25 hours.

According to statistics, there are a total of 135 low-voltage loads in the entire train, 44 loads related to self generation function, 2 loads controlled by network DO (TCU, charger control unit), and 42 loads not controlled by network DO; There are a total of 91 loads unrelated to self generation function, 31 loads controlled by network DO, and 60 loads not controlled by network DO. Among the 60 loads, 6 only consume electricity during operation, and 54 continuously consume electricity (including 5 onboard train control equipment). The plan to add a one key start function for self generating electricity is as follows:

(1) Hardware aspect

Add a self generating one key start function knob to the driver's cab fault control panel. Add 3-6 one key start control relays with 8 pairs of contacts per vehicle to cut off power supply to 54 loads unrelated to self generation. Each vehicle has added 2 switches in the driver's cab, including the load switch and the emergency lighting switch for rescue. Arrange the switch panel on the right side of the driver's cab cabinet.

(2) In terms of software

Add self generating switch status collection to the lead vehicle and make corresponding operation records. Add redundant DO points to each vehicle, and when the charging units of the entire train are not working and the self generating mode is enabled, control the one key start relay to operate. After any charger starts working, it will automatically restore power supply to 54 related loads.

3、 Battery load management

When there is no output from all the charging units of the high-speed train, the high-speed train defaults to directly entering the "battery management mode". When the DC load needs to work for a long time, it can be achieved by operating the HMI screen maintenance screen to "exit battery management mode".

2. Load control

When the network detects that there is no output from all the chargers in the train, TCMS starts timing:

0-30 minutes: No driver or mechanic is required to perform any operations during this stage.

31-90 minutes: A pop-up screen prompts manual disconnection of ATP, DMS, EOAS, and LKJ equipment power supply.

91-120 minutes: A pop-up screen prompts to turn off the battery and remove the main control key.

121-420 minutes:

(1) Operate the "Battery Undervoltage" knob to the "Red Dot" position, and change the battery (alkaline) undervoltage protection value from 95V to 83V;

(2) Operate the "load cut-off" knob to the "red dot" position. The network will cut off loads unrelated to self generation and only retain loads related to self generation.

421-480 minutes: Rescue coupling operation phase

481-495 minutes: The rescue march begins.

4、 Working conditions of various DC loads under battery management mode

0-2 minutes, battery ON position: All DC loads are working normally without any load shedding.

3-30 minutes, battery ON position:

The vehicle issues instructions to cut off 115 line loads such as the interior and exterior information display, sanding control unit, water boiler control unit, wireless internet system, seat signal lights, seat information display, seat information display system host, VIP seat control power supply, semi-active control device host, passenger compartment interior and exterior doors, mechanical hook heating, electric hook heating, normal lighting in the passenger compartment, entertainment system host and equipment, passenger compartment sockets, TV loads, etc; At the same time, the network control emergency ventilation is activated.

31-90 minutes, battery ON position:

TCMS issues instructions to cut off the 103B and 103C line loads, including the brake control device (BN line load), video surveillance server, water supply and sanitation, whether there is a display in the toilet, no smoking signs, wind whistle solenoid valve, automatic phase separation device, electrical energy monitoring system, and axle temperature host.

91-120 minutes, battery ON position: TCMS issues a command to turn off emergency ventilation.

121-420 minutes, battery OFF position:

After turning off the battery, only the 102 line load is retained: brake control device (BD line load), battery voltmeter, driver's cab telephone, onboard radio, external lighting, rescue emergency lighting, distribution cabinet lighting, driver's cab lighting, auxiliary air compressor and other loads.

Battery OFF position:

After the main control is put into operation, only 102 line loads are retained: brake control device (BD line load), battery voltmeter, driver's cab telephone, onboard radio, external lighting, emergency rescue lighting, distribution cabinet lighting, driver's cab lighting, auxiliary air compressor load, safety loop, BP rescue device and other loads.

481-495 minutes, battery ON position: Keep the load related to self generation working.

5、 Conclusion

In summary, the battery power supply of the high-speed train can meet the power supply needs of the high-speed train under special working conditions, including emergency lighting, emergency display, maintenance power, communication and control, etc; It should also meet the requirement that when a faulty high-speed train is rescued, the faulty high-speed train should wait for rescue for 5 hours (considering necessary loads) and 1 hour for coupling and braking tests on the basis of the 2-hour emergency power supply mentioned above, and start the self generating function after the rescue operation begins. Lithium ion batteries are equipped with a battery management system that can collect battery voltage and temperature in a timely manner. The battery management system is equipped with multiple layers of fault warning protection for the battery, with certain redundancy design in protection measures. Reliable protection and anti loosening design in the electrical connection part can effectively prevent safety accidents from occurring. Optimizing the battery load management of high-speed trains provides a good method reference for the design ideas of related vehicle models in the future, and reflects that the load management aspect described in this article is worth promoting.