Energy supply of the Transrapid vehicle

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david
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Joined: 3. Apr 2021, 18:09

Energy supply of the Transrapid vehicle

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This article deals with the energy supply concept of the Transrapid vehicle. A soon to follow second part will explain the energy supply concept of the guideway in more detail.

Introduction
As is well known, there are no overhead lines on the Transrapid. However, the energy requirements for all consumers in the vehicle, including, for example, support/guide magnet modules or lighting in the passenger compartment, must still be met. This article explains how and from where the Transrapid obtains the required energy during regular operation.

Energy supply
During regular operation, the 160 linear generators and busbars or inductive power supply (on newer vehicles such as TR09) are used to supply power to the vehicle.

At about 20 km/h, the linear generators start to generate power. However, at 20 km/h the linear generators generate too little energy. From 30 km/h, the generated energy is already sufficient to meet the energy requirements of low-voltage consumers, including pneumatics, safety circuits and eddy current brake testing. From approx. 70 km/h, the generated energy is sufficient to cover the energy requirements of the levitation carrying magnets. From approx. 100 km/h, the generated energy is sufficient to also cover the energy requirements of the guidance magnets. This means that from 100 km/h, the entire energy requirement of the section is already covered.

Only for the maximum power of the air conditioning and the eddy current brake is the energy at 100 km/h not yet sufficient. However, this in no way means that air conditioning and eddy-current brakes do not work at 100 km/h. They continue to be operated by the nickel cadmium-plated brakes. These are still buffered by the nickel-cadmium batteries in the vehicle.

The eddy current brake is merely the Transrapid's emergency brake, which is installed in the vehicle. Unlike the service brake, which is generated by the linear motor in the guideway, the eddy current brake does not feed energy back into the public grid or braking resistors; on the contrary, the vehicle applies the power for emergency braking on its own.

The energy generated by the linear generators is rectified by several boost converters per section and fed directly into the various on-board networks of the Transrapid.

But before the speed of 100 km/h is reached, an additional energy supply is required.

Additional energy supply
On newer vehicles such as the TR08, TR09 and CRRC 600, additional power supply systems are installed.

Conductor rails are used on the TR08 and CRRC 600. The conductor rails supply the vehicles with 400V direct current. To do this, the vehicle extends its mechanical current collectors at speeds of 0 to 100 km/h, which then make mechanical contact with the track. In this way, the vehicle is supplied with power before the vehicle reaches a speed of 100 km/h. At speeds above 100 km/h, conductor rails are superfluous.

Inductive Power Supply (IPS) is used on the TR09. The system was developed in collaboration with the Technical University of Braunschweig, Germany, to provide a secondary power supply for the vehicle without the need for mechanical contact with the track (as is the case with conductor rails). The system uses 400V AC at a frequency of 20 kHz, which provides non-contact power transfer to the secondary coil in the vehicle. A modified or adapted version of this technology is being pursued by INTIS. INTIS has adapted the system to other electric vehicles so that e-cars, e-buses and e-scooters also benefit from this technology. The advantage is that a very high efficiency is achieved and the charging speed is not shorter compared to cables, in some cases even faster.

It should be noted that the on-board power supply in the Transrapid is buffered by a nickel-cadmium battery. This means that a (short-time) abandonment of busbars or IPS at below 100 km/h does not result in a failure of the system. In the TR06 and TR07, there was no secondary power supply, the vehicles simply recharged their battery through a cable at stops. The systems just mentioned (busbars and IPS) are also necessary in emergencies to back up the vehicle power supply. For the TR06 and TR07, towing exercises were therefore carried out on the TVE with special vehicles that drove to the vehicle and supplied it with power in the event of an emergency. For this purpose, both vehicles (TR06/TR07) had removable flaps at the front, behind which the connections for the power supply were located. From TR08 onwards, towing was no longer necessary, as the conductor rails were installed along the track. In 2005, the IPS system was tested for the first time on the TVE, but not with the TR09, but with the TR08. For this purpose, the appropriate secondary coil was installed in E2 (end section 2) on a TFMM (TragFührMagnetModul). The tests proved that the system works at least as reliably as the mechanical contact to conductor rails, as natively with the TR08. In China, however, CRRC is not using IPS with its latest vehicle because CRRC does not have the licenses for it. It should also be noted that of the 29.9 km SMT track in Shanghai, 23.8 km are equipped with conductor rails. Theoretically, this would increase compatibility with the SMT line for the CRRC 600, except for the incompatible operations control technology (BLT).

The on-board power supply of the Transrapid
Each vehicle section has three different on-board networks. These include four independent 440V (direct current) on-board networks per section, also four independent 24V networks, and also a 230V on-board network. This results in a particularly high level of redundancy, which ensures the safety of the Transrapid, even in the event of power failures.

The 4x 440V on-board power supplies feed the support/guide magnets, eddy current brake and air conditioning systems. As mentioned before, these on-board networks are buffered by a nickel-cadmium battery.

The 4x 24V on-board networks feed the safety-related consumers of the vehicle section, including vehicle control, operations control and communication components. The 24V on-board networks are fed redundantly (multiple fuses) from the 440V on-board network.

The 1x 230V on-board power supply feeds the consumers in the passenger compartment, including passenger information, lighting and, according to today's standards, also (USB) sockets with which passengers can charge their terminal devices. In the CRRC 600, USB sockets are actually installed in the first-class seats to allow charging of a terminal device. This is an AC network with a household frequency of 50 Hz, which is also fed from the 440V on-board network by inverters.

Of course, all on-board networks and battery circuits of the Transrapid are designed to be earth and short-circuit proof. As previously mentioned, these networks are buffered by batteries. Typically, the networks are powered (energized) by the boost converters and linear generators, but they are also powered by an on-board energy source, the batteries.

Due to the high redundancy, a power failure in the whole is therefore impossible. More than 25 million kilometers driven by the system in Shanghai confirm the high redundancy and an MTBF (Mean-Time-Between-Failure) of (for the TR08) at least 35 years.

This explains the energy supply of the Transrapid vehicle. In a soon to follow second part I will also explain the power supply of the tracks, including the drive blocks, track section change procedures, and many more.

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