DE202004011801U1 - Electrical current power production unit for emergency systems with fuel cells has electrical store and control systems and power adjusting units to suit the output - Google Patents

Abstract

An electrical power production unit (10) comprises a power bus and at least two fuel system stacks (14) and electrical energy store (24) and control (28) systems. Power adjusting units connect to the bus with an input voltage and total nominal output and the number of fuel cells connected to the bus and number of adjusting units changes with need.

Description

BACKGROUND THE INVENTION

Field of the Invention

The The invention relates generally to power supply devices an arrangement of fuel cell systems.

description the state of the art

fuel cells are known from the prior art. Put fuel cells a hydrogen-containing fuel stream and an oxygen containing oxidant stream for generating electrical Electricity electrochemically. Fuel cell power plants were in traffic engineering, for mobile as well as for stationary Applications.

conventional Reserve or emergency energy systems include rechargeable battery series Provision of electrical energy when the power grid is insufficient or interrupted. Systems for providing Alternating current (AC) typically have an uninterruptible Uninterruptible power supply (UPS) unit on, which include a UPS switch, a battery charger, and an inverter (and the further power filtering and / or conditioning arrangements may include). Usually leads the network to the load (s) primary energy. If the network is interrupted, leads the battery array of load / loads of energy by the inverter which converts the direct current (DC) input into an AC output. If the primary power supply is available again, loads the battery charger the battery row.

In the battery series are mostly valve-controlled lead acid (valve regulated lead acid (VRLA) batteries. The number and Battery size depends on the required term. Commercially available UPS and other electrical Facilities such as Inverters have different input voltage requirements (e.g. 48, 72 and 96 volts DC, VDC), which is a multiple of the 12th Represent the VDC output of the VRLA battery and its nominal output power is adapted to the corresponding battery series.

Emergency power systems where fuel cell power plants are used also described. One approach is fuel cell modules use where a battery is electrically parallel to the Fuel cell system is switched to provide additional electricity when the load request exceeds the output of the fuel cell stack and to store electricity when the output of the fuel cell stack exceeds the load requirement. The properties of the connections of the module about that similar out trained like the existing VRLA batteries.

fuel cell modules however, are not as commercial in terms of current, voltage, or power levels Arrangements adapted like VRLA battery series. It is desirable to provide a fuel cell power plant that better matches the DC input voltage and the power output of existing electrical reserve facilities, such as. a UPS facility is customized.

DETAILED DESCRIPTION OF THE INVENTION

In The following description explains specific details to the different embodiments the invention completely understandable close. For however, those skilled in the art will understand that the invention is without them Details executed can be. In other examples, known ones with fuel cells, Fuel cell stacks, devices for storing electrical Energy such as Batteries, flywheels and supercapacitors, Reactant delivery systems, temperature control systems and fuel cell systems related Structures not shown or described in detail to avoid that the descriptions of the embodiments of the Invention unnecessarily become indistinct.

In the present description and the appended claims under an "UPS facility" an uninterruptible Power any topology, including passive standby (passive standby), the power line interactive and the double conversion types understood that are defined in the IEC 62040-3 and ENV 50091-3 standards.

1 shows a hybrid fuel cell module 10 that a burden 12 Applies energy for use in an illustrated embodiment of the invention. Weight 12 typically provides the hybrid fuel cell module 10 device to be driven, such as a vehicle, a device, a computer and / or associated peripheral components. During the hybrid fuel cell module 10 typically not as part of the load 12 can be considered, parts of the hybrid fuel cell module 10 , such as the control electronics in some possible embodiments part of the load 12 or the entire load 12 form.

The fuel cell module 10 comprises a fuel cell stack 14 made up of a number of is composed of individual electrically connected fuel cells in series. The fuel cell stack 14 takes like through the arrow 9 is shown reactants such as hydrogen and air via a reactant delivery system 16 on. The reactive feed system 16 can have one or more reactant supply reservoir (s) or source (s) 11 , a reformer (not shown) and / or one or more control element (s), such as, for example, one or more compressor (s), one or more pump (s) and / or one or more valves) 18 or other reactant control elements. The fuel cell stack generates during operation 14 as by the arrow 20 is shown, a reaction product that typically contains water. The fuel cell module 10 can be part of the reaction products 20 or all of the reaction products 20 reuse. For example, as indicated by the arrow 22 shown, some or all of the water to the fuel cell stack 14 are returned to humidify the hydrogen and air at the correct temperature and / or to hydrate the ion exchange membranes (not shown) or the temperature of the fuel cell stack 14 to control.

The fuel cell stack 14 generates a stack voltage V _S through a high voltage bus passing through the positive and negative voltage lines 19a . 19b is formed. The stack current I _S flows from the fuel cell stack 14 to the load via the high-voltage bus 12 , Here, the term "high voltage" denotes the voltage that that of conventional fuel cell stacks 14 to drive loads 12 is generated and the term is used to enable a distinction to be made from other voltages generated by the fuel cell module 10 can be used for control and / or communication (e.g. 5 V). Thus, high voltage does not necessarily mean "high" with respect to other electrical systems.

The hybrid fuel cell module 10 comprises a device for storing electrical energy, such as a supercapacitor and / or a battery 24 who / who via the lines 19a . 19b of the high-voltage bus electrically parallel to the fuel cell stack 14 are switched to the load 12 drive. The rest voltage of the battery 24 is selected to be similar to the full load voltage of the fuel cell stack 14 is. An internal resistance R _{B of} the battery 24 is selected so that it is much smaller than the internal resistance of the fuel cell stack 14 , So the battery works 24 as a buffer that absorbs excess electricity when the fuel cell stack 14 generates more electricity than the load 12 needed, and that of the load 12 Feeds electricity when the fuel cell stack 14 generates less electricity than the load 12 needed. The voltage across the high voltage bus 19a . 19b corresponds to the open circuit voltage of the battery 24 minus the battery discharge current multiplied by the value of the internal resistance R _{B of} the battery 24 , The smaller the internal resistance R _{B of} the battery 24 the smaller the fluctuations in the bus voltage. An optional counter current blocking diode D1 can be electrically between the fuel cell stacks 14 and the battery 24 be switched to prevent power from the battery 24 to the fuel cell stack 14 flows. The fuel cell module 10 may also include other diodes, fuses, or other overvoltage protection elements to avoid short circuit and / or overvoltages.

2 shows a two-dimensional arrangement 68 of fuel cell systems 10 which are arranged in a number of M rows and a number of N columns to the load 12 via the power bus 56 drive. The fuel cell systems 10 are individually with 10 (1.1) - 10 (M, N), where the first number in the bracket is a row position and the second number in the bracket is a column position of the fuel cell module 10 in the two-dimensional arrangement 68 indicates. The ellipses in 3 show that the different rows and columns of the two-dimensional arrangement 68 may include additional fuel cell systems (not explicitly shown).

Each of the fuel cell systems 10 (1.1) - 10 (M, N) is single with the power bus 56 connectable to provide various desired output powers, voltages or currents. The fuel cell systems 10 (1 - M, 1) 10 (1 - M, 2), 10 (1 - M, 3) - 10 (1 - M, N) in each column 1 - M can be connected to one another in an electrical series connection. The fuel cell systems 10 (1.1 - N), 10 (2.1 - N), 10 (3.1 - N) - 10 (M, 1 - N) in each row 1 - N can be connected to one another in an electrical parallel connection. From the 3 and this description will be apparent to those skilled in the art that the two-dimensional arrangement 68 the series connection of the fuel cell systems 10 enables an output power of the power supply system 50 by setting an output voltage. It is also apparent to the person skilled in the art that the two-dimensional arrangement 68 the parallel connection of the fuel cell systems 10 enables to the output power of the power supply system 50 by setting an output current. It is also apparent to the person skilled in the art that the two-dimensional arrangement 68 the series and parallel connection of the fuel cell systems 10 enables to the output power of the power supply system 50 by adjusting both the output current and the output voltage. Thus, for the illustrated embodiment in which each fuel cell system is, for example, 1 kW at 24 Volts and 40 amps generated, a maximum output of N × M kW possible. It is also apparent to the person skilled in the art that the one- and two-dimensional arrangement structures discussed here relate to positions that can be electrically connected to one another and do not necessarily require that the fuel cell systems 10 are physically arranged in rows and / or columns.

As discussed above, one or more of the fuel cell systems in the present power plant (eg 10 (M + 1)) can serve as a "redundancy" fuel cell system. Compounds (not shown) that make up the series fuel cell systems 10 (eg 10 (3.1) 10 (3.2) 10 (3,3), ... 10 (3, N)) can also be used to provide at least one N + 1 redundancy. The connections prevent the loss of any single fuel cell module 10 in a column impaired ability, the load 12 to supply completely. In addition, the connections can be tapped or can form taps in order to generate the desired potentials on the lines of the voltage buses. As can be seen by the person skilled in the art, the redundancy concept can also be applied to various other systems of the present power plant.

A customizable arrangement of fuel cell modules can be designed in this way be the current, voltage or power level of the fuel cells adapts to existing commercial facilities. The fuel cell modules can be designed so that they are in standard slide-in cabinets or -casing fit that for current Emergency power systems with battery series are used. An advantage this approach is that the electrical facilities of a customer only marginally or not at all need to be modified to supply fuel cells for backup energy use. this leads to to cost and time savings for customers, the fuel cells want to integrate into their products.

Unfortunately the voltage and power outputs fit more commercially available Fuel cell modules are not always good at the input voltage and power output characteristics are more commercially available UPS and other electrical equipment. This is particularly so the case for products that normally have smaller batteries lower amp hour outputs are used in series can be switched to higher voltages at lower current levels to create.

For example, Nexa ^™ fuel cell systems (Ballard Power Systems Inc., Burnaby, CA) provide 1 kW at 24 volts and 40 amps. Nexa ^TM modules can be electrically connected in series to provide an input voltage that is suitable for a given power conversion unit. For example, to provide 48 VDC at 80 amps, four modules can be connected in series and in parallel to serve as a backup device for existing rectifiers that are used in telecommunications emergency power systems.

Commercially available power influencing devices such as inverters and UPS units have input requirements that are multiples of the 12 VDC VRLA battery output. The nominal output of such devices is also designed so that it is adapted to the performance of available battery series that are used for a given application. For example, inverters and UPS devices with a nominal output of 2 kW AC are commercially available that require 72 or 96 VDC input. Three or four Nexa ^TM modules can be electrically connected in series to produce a 72 or 96 VDC output to adapt to these input requirements (additional modules can also be electrically switchable to provide the desired level of redundancy if desired to care). The output capacity of the fuel cell assembly ( 3 or 4 kW), however, does not match the nominal output of the UPS device - in the case of an emergency power generator, which uses the 96 VDC UPS device, half of the available fuel cell output is not used.

The The present fuel cell power plant comprises an arrangement of fuel cell modules connected to a DC bus and at least two UPS devices, Inverters or other power influencing devices (such as e.g. DC / DC converter). The number of series connected to the DC bus Fuel cell modules are chosen to meet the DC input voltage requirements the performance influencing devices is adapted. The number of the performance influencing devices is chosen so that it essentially corresponds to the total nominal power of such units or exceeds the nominal power output of the fuel cell modules. In some applications the fuel cell modules and the performance influencing devices be designed to be placed in a standard slide-in cabinet or a standard housing fit.

The 3A and 3B show two embodiments of the present fuel cell power plant. The power plant 70 comprises an arrangement of four fuel cell modules 10 (e.g. Nexa ^TM fuel cell modules), each of which is 1 provides kW at 24 volts. The fuel cell modules are designed so that they are in a slide-in cabinet 72 fit and electrically connected in series with a 96 VDC bus (not shown). Two 2 kW UPS units 74 are connected in parallel to the DC bus. One control 76 monitors and controls the output of the power plant for the rack 70 , The output of the arrangement of fuel cell modules 10 is related to the input voltage requirement of the UPS equipment 74 adjusted and the total output of the arrangement and both UPS facilities 74 is also adapted to 4 kW. The output of the power plant can thus be effectively doubled by using an additional UPS device.

The power plant 80 comprises an arrangement of three fuel cell modules 10 (e.g. Nexa ^TM fuel cell modules), each of which provides 1 kW at 24 V and is electrically connected in series with a 72 VDC bus (not shown), three 1.5 kW inverters connected in parallel with the DC bus, and a charging device 84 for charging the fuel cell modules 10 assigned batteries and / or supercapacitors. The inverters 82 are switchable in parallel to the DC bus to provide an n + 1 redundant 3.0 kW AC output.

The use of multiple performance control units extends the compatibility of the fuel cell module assemblies with a wider range of performance control products and emergency power applications. Not only does this allow the power plant output to better match the fuel cell module output, it can also improve reliability by adding redundancies to the power plant. In the present context, the output of the power plant and the fuel cell output do not have to be the same in order to match each other; the output of the arrangement may exceed and still match the nominal output of the performance control devices by 10% or the like. For example, the 4 kW power output from the UPS facility 74 still to the output of the arrangement in the in the 3A and 3B illustrated power plant 70 fit if this were 4400 W.

Although this is in the 3A and 3B is not shown, it is further understood by those skilled in the art that additional fuel cell modules 10 electrical in the arrangements of the power plants 70 and 80 can be switched to provide for any desired module redundancy level as described above. In applications where the power plant provides alternating current, the phase of the AC output voltage of individual inverters or UPS devices can be controlled to provide single, multi-phase or auxiliary phase AC power as desired. For example, the power plant 80 be designed to provide 3 kW 120 VAC single phase current or 208 VAC three phase current.

The disclosed embodiments provide a "building block" or "component" approach to manufacturing power supply systems that enables a manufacturer to build very diverse power supply systems from some or even just one basic type) of a fuel cell module 10 manufacture. In addition, the output of the power supply device can be adapted to the fuel cell module output using commercially available power influencing devices. This approach can reduce design, manufacturing, and inventory costs, as well as provide redundancy to extend the mean failure margin of the resulting end-user product (ie, the power system). This approach can also simplify maintenance and repair and reduce costs.

Generally can the present power plant in an emergency power system for a number of applications that use the following applications include, but are not limited to:

• 1. Network server units: LAN / WAN systems, such as e.g. Network nodes and routers.
• 2. Communication: cable television (community antenna television, CATV), radio, telecommunications storage systems and / or servers, wireless base stations, microwave amplifier stations, radar targeting systems.
• 3. Computer rooms: Small and medium sized Server, large enterprise server, Data storage systems, network computer blocks, internet data centers.
• 4. Desktop / workstations: stand-alone PCs, workstations and computer peripherals.
• 5. Industrial / commercial: process control systems, medical Plants, laboratory instruments, traffic control systems, security systems, Commercial equipment.

The The present power plant and the operating procedure constitute a system ready, which is smaller and lighter than conventional power supply systems, where VRLA batteries are used. The present power plant worries about it in addition for an "immediate" operation with individual Fuel cell systems that "in Operation switchable "(" hot swappable ").

Claims (2)

Power plant for generating electricity comprising: an arrangement of fuel cell systems, the arrangement having a composite power output and comprising: a power bus and at least two fuel cell systems, each fuel cell system comprising a fuel cell stack, a device for storing electrical energy connected in parallel with the fuel cell stack and a device for controlling a current flow from the fuel cell stack to the device for storing electrical energy and the power bus, each fuel cell system having an output voltage and a power output, characterized in that the power plant further comprises: at least two power influencing units, each unit being electrically connected to the power bus and wherein the power influencing units have an input voltage and a total nominal power output, the number of fuels electrically connected to the power bus cell systems is selected so that it is adapted to the input voltage of the power influencing units and the number of power influencing units is selected such that it is adapted to the total nominal power output or exceeds the power output of the arrangement. Power plant according to claim 1, wherein the output voltage 24 volt direct voltage (VDC) and the power output of the fuel cell systems Is 1 kW.