Power storage system for a rail-guided vehicle

The invention relates to an energy storage system for a track-guided vehicle, with at least one electrical energy storage device and at least one electrochemical energy storage device being connected via at least one converter to a supply line and to a drive unit for the vehicle.

An energy storage system such as this is known from the prior German patent application 10 2007 032 776. Two DC/DC controllers are used as converters there. The energy interchange between the drive unit and the energy storage devices of the energy storage system is controlled and/or regulated by an energy management unit.

EP 1 424 494 A1 discloses a diesel-electric drive system which, as energy storage devices, has both an electrical energy storage device, for example an ultracap, and an electrochemical energy storage device, for example a nickel-cadmium battery. In what is known, these two energy storage devices are connected to one another via a so-called step-down converter. The electrical energy storage device is connected directly to the intermediate circuit of a converter.

In order to allow the two existing energy storage devices to be used optimally for operation of the drive unit, a complex energy management unit has been required until now.

The invention is based on the object of specifying an energy storage system for a track-guided vehicle, in which different energy storage devices, for example an electrochemical battery and/or an ultracap, can be operated completely independently of one another.

According to the invention, the object is achieved in that individual phases of the converter can be operated as independent direct-current controllers for independent charging and discharging of different energy storage devices.

Converters are known per se and, for example, are connected upstream of the drive motors in rail vehicles.

When a conventional converter is used to connect different energy storage devices to the drive unit, this surprisingly results in the advantage that different energy storage devices, for example ultracaps and electrochemical batteries, can be operated completely independently of one another using simpler means than in the past. Different voltages are possible on the energy storage devices, or else different charging and/or discharging characteristics for the energy storage devices, as well as different energy storage device power levels. Only one commercially available converter is required, possibly with modified software, in order to replace the previously required converters with an energy management unit.

The dependent claims specify advantageous developments and refinements of the invention.

One example of an electrical energy storage device is a double-layer capacitor or a superconducting energy storage device. One example of an electrochemical energy storage device is a nickel-metal-hydride battery. By way of example, chopper inductors, one or more control or regulating units and various switching devices are connected to the energy storage devices.

The electrical energy storage device is, for example, an ultracap, and the electrochemical energy storage device is, for example, a battery.

By way of example, the converter is a polyphase pulse-controlled inverter. Each phase therein can be operated independently as a direct-current controller, using suitable software. This is therefore particular highly suitable for providing a dedicated chopper for each of the energy storage devices.

For example, the converter has three phases and each of the three phases is used as the chopper for regulating the charging and discharging processes. Even three separate energy storage devices or two energy storage devices, in which two phases are operated in parallel in the case of one energy storage device in order to increase the power, or just one energy storage device, in which three phases are operated in parallel in order to increase the power, can be connected to a three-phase pulse-controlled inverter.

By way of example, the energy storage system comprises a single-phase or polyphase converter with or without integrated or additive braking controller or overvoltage limiter, one and/or more electrical energy storage devices, for example based on double-layer capacitors, one and/or more electrochemical energy storage devices, for example based on nickel-metal-hydride batteries, a corresponding number of chopper inductors, one or more control/regulator units and various switching devices.

The energy storage system is connected to the intermediate circuit of the drive system, for example without an inductor or via one or more inductors. The energy storage system may also be connected via one or more inductors directly to the power supply system voltage.

This combination of an electrical energy storage device and an electrochemical energy storage device with a conventional converter makes it possible to optimally exploit the advantages of the systems, specifically the specific power of the electrical stores and the high specific energy content of electrochemical energy storage devices, in conjunction with the commercially available converter technology.

Furthermore, this hybrid energy storage system can easily be integrated in new vehicles, and can also be integrated retrospectively in existing, older vehicles. The life in particular of the electrochemical energy storage device is considerably increased by the combined method of operation.

The single FIGURE of the drawing is a schematic and block diagram of the energy storage system according to the invention.

The drawing shows a supply line 1 , with this supply line 1 being connected to drive units 3 . The drive units 3 may contain at least one power supply system inductor, which is not shown, in the respective supply line. The supply line 1 is also connected to an energy storage system 4 . The energy storage system 4 may contain at least one power supply system inductor, which is not shown, in the respective supply line. In the energy storage system 4 , the supply line 1 is connected to the intermediate circuit of a pulse-controlled inverter 5 , which is also connected at ground point 6 . An electrochemical energy storage device 7 is connected to one phase of the pulse-controlled inverter 5 . An ultracap 8 is connected as an electrical energy storage device to another phase of the pulse-controlled inverter 5 . Both the electrochemical energy storage device 7 and the ultracap 8 are connected to the ground point 6 . Inductors 9 , 10 as well as optional switches 11 , 12 or fuses are arranged in the connecting lines between the two energy storage devices and the pulse-controlled inverter 5 . A switch 13 is also optionally located in the supply line 1 , upstream of the energy storage system 4 .

The pulse-controlled inverter 5 in the illustrated circuit is used as a reliable chopper for the electrochemical energy storage device 7 and for the ultracap 8 .