TRANSPORT SYSTEM Field of the invention

The object of the invention is a transport system as defined in the preamble of claim 1. This kind of transport system can be, for instance, an elevator system, an escalator system, a travelator system, a crane system or a drum drive elevator system.

Prior art

In fuel cells, a fuel and an oxidant react in the presence of an electrolyte. Electrical energy is produced in the reaction.

The power requirement of a transport system varies according to the loading and the control situation. In an elevator system, for example, the power requirement during acceleration can be transiently over double compared to the power required during even speed.

The application of fuel cells in transport systems is described in the following publications:

Publication TW474893 B presents a transport system for public transit. The system comprises at least one vehicle with an oxygen/hydrogen fuel cell or a zinc/air fuel cell functioning as the energy source.

Publication JP2002326771 presents a fuel cell as the energy source of an elevator motor. Energy can be supplied by means of the fuel cell also during an outage of the electricity network, in which case the system is immune to electricity outages.

Publication JP2004250128 presents an appliance for controlling an elevator to a landing. The apparatus can be disposed in the elevator hoistway. The apparatus comprises a fuel cell as well as a fuel supply arrangement.

Publication JP2005225667 presents a fuel cell as an energy source of an elevator. The fuel cell as well as a first fuel tank is disposed in the counterweight. A second fuel tank is in the elevator hoistway. The water produced as a product of combustion is also stored in the counterweight.

In publication "SimRDH: A Modeling and Simulation Environment With Component Hybrid Dynamic Nets, Elevator Application"; IEEE Transactions on energy conversion, vol. 22, no. 3, September 2007, on page 597, in Fig. 17 presents as a block diagram two different energy stores, of which the first comprises supercapacitors and the second can, according to the text, comprise e.g. a solar panel, a fuel cell or corresponding. According to the publication the energy store comprising supercapacitors is fitted to supply energy to the frequency converter of the elevator motor during motor operation of the elevator motor, as well as to receive energy from the frequency converter during motor braking of the elevator motor.

Purpose of the invention

The purpose of the invention is to solve both the aforementioned problems of prior art as well as the problems presented in the description of the invention below. The invention presents an arrangement in which a fuel cell as well as a temporary storage of electrical energy are fitted in connection with the power supply circuit of the transport system for reducing the variation of the loading of the fuel cell. In this case the invention also discloses an arrangement in which the operation of the transport system can continue normally during malfunctions of the electricity network.

Characteristic features of the invention

The transport system according to the invention is characterized by what is disclosed in the characterization part of claim 1. Other features of the invention are characterized by what is disclosed in the other claims. Some inventive embodiments are also discussed in the descriptive section of the present

application. The inventive content of the application can also be defined differently than in the claims presented below. The inventive content may also consist of several separate inventions, especially if the invention is considered in the light of expressions or implicit sub-tasks or from the point of view of advantages or categories of advantages achieved. In this case, some of the attributes contained in the claims below may be superfluous from the point of view of separate inventive concepts.

In the invention fuel cell refers generally to fuel cells that use different fuels, oxidants and electrolytes. Possible fuel cell types are e.g. a metal hydride fuel cell, an electrogalvanic fuel cell, a DFAFC fuel cell, a zinc-air battery, a microbial fuel cell, a UMFC fuel cell, a reversible fuel cell, a direct borohydride fuel cell, an alkaline fuel cell, a direct methanol fuel cell, a reformed methanol fuel cell, a direct ethanol fuel cell, a formic acid fuel cell, a proton exchange membrane fuel cell, an RFC-redox fuel cell, a phosphoric acid fuel cell, a molten carbonate fuel cell, a TSOFC fuel cell, a protonic ceramic fuel cell, a direct carbon fuel, and a planar solid oxide fuel cell.

Fuel cells can be connected in series, in which case the output voltage increases, as well as in parallel, in which case the current available from the fuel cell increases. This kind of structure, which can comprise one or two or more fuel cells, connected in parallel and/or in series, is called a fuel cell stack in the invention.

The transport system according to the invention comprises an electric motor connected to the power supply circuit of the transport system; a fuel cell stack connected to the power supply circuit of the transport system; and also a temporary storage of electrical energy connected to the power supply circuit of the transport system. The power supply circuit of the transport system according to the invention comprises an intermediate circuit power supply appliance of the motor; and also a power supply circuit of the electrification of the transport system. The temporary storage of electrical energy is fitted to supply energy to the power supply circuit of the transport system during motor

operation of the electric motor. The temporary storage of electrical energy is also fitted to receive energy from the power supply circuit of the transport system during motor braking of the electric motor. The power supply circuit of the transport system comprises at least a first controllable switch for controlling the power supply of the fuel cell stack, and the power supply between the fuel cell stack and the power supply circuit of the transport system is fitted to occur with the control of at least the aforementioned first controllable switch. Furthermore power supply circuit of the transport system comprises at least a second controllable switch for controlling the power supply of the temporary storage of electrical energy, and the power supply between the temporary storage of electrical energy and the intermediate circuit of the power supply appliance of the motor is fitted to occur with the control of at least the second controllable switch. The fuel cell stack is fitted to supply power to the power supply circuit of the transport system with essentially an even loading, and during the power supply of the fuel cell stack the temporary storage of electrical energy is fitted to receive varying power from the power supply circuit of the transport system and also to supply varying power to the power supply circuit of the transport system, to level out the variation of the output voltage of the fuel cell stack. In this case the variation of the voltage of the fuel cell stack can be leveled out by controlling the power supply of the temporary storage of electrical energy either as a response to the determined output voltage of the fuel cell stack, or the loading placed on the fuel cell stack by the power supply circuit of the transport system can be determined, and the power supply of the temporary storage of electrical energy can be controlled on the basis of this determined loading or variation of the loading.

The power supply circuit of the transport system refers generally to the apparatuses, connections and conductors needed in the transport system for the power supply.

In one embodiment of the invention the power supply circuit of the transport system is connected to an electricity network, and the transport system comprises a determination of the status of the electricity network. The power

supply from the fuel cell stack to the power supply circuit of the transport system is in this case fitted to start after the determination of the status of the electricity network has detected a malfunction of the electricity network.

In one embodiment of the invention the temporary storage of electrical energy comprises a supercapacitor and/or a lithium-ion battery.

In one embodiment of the invention the operation of the transport system is fitted to occur with limited movement during the power supply of the fuel cell stack.

The switches referred to in the invention can be mechanical switches, such as relays or contactors, or solid-state switches, such as IGBT transistors.

In one embodiment of the invention the transport system is an elevator system. In this case the aforementioned electric motor is an elevator motor. In one embodiment of the invention the traction sheave of the elevator is connected to or integrated into the elevator motor.

The intermediate circuit power supply appliance of the motor mentioned in the invention can be e.g. a frequency converter.

The aforementioned elevator system can be with a machine room or without a machine room, and on the other hand can also be an elevator system with counterweight or without counterweight.

The electric motor mentioned in the invention can be an alternating current motor or a direct current motor. The alternating current motor can be e.g. a squirrel-cage motor or a permanent magnet motor.

Advantages of the invention

With the invention at least one of the following advantages, among others, is achieved:

The fuel cell stack presented in the invention is fitted to supply power to the power supply circuit of a transport system with essentially an even loading. When in this case, in addition to the fuel cell stack, the type of temporary storage of electrical energy by means of which it is possible to supply instantaneous power to the power supply circuit of the transport system as well as to receive power from the power supply circuit of the transport system, is connected to the power supply circuit of the transport system, it is possible to level out the variation of the output voltage of the fuel cell stack. The output voltage of a fuel cell decreases clearly as the loading of the fuel cell increases owing to, among other things, the internal resistance of the cell. When the variation in the loading of a fuel cell stack is thus reduced according to the invention with the control of the temporary storage of electrical energy, the variation in the output voltage of the fuel cell stack also decreases.

For example, a supercapacitor or a lithium-ion battery are suited for use as energy stores in the temporary storage of electrical energy according to the invention, because their ability to supply and to receive instantaneous power is good.

The fuel cell stack according to the invention is fitted to supply power also to the power supply circuit of the electrification of the transport system, in which case e.g. the different supervision arrangements, control arrangements and lighting arrangements needed in the transport system also operate during the power supply of the fuel cell stack.

When the power supply circuit of the transport system is connected to an electricity network and the transport system comprises a determination of the status of the electricity network, the power supply of the fuel cell stack can if necessary also be controlled on the basis of the status of the electricity network. The power supply from the fuel cell stack to the power supply circuit of the transport system can in this case be started after the determination of the status of the electricity network has detected a malfunction of the electricity network, in which case the operation of the

transport system can continue normally. This type of malfunction of the electricity network can be e.g. a power outage or an undervoltage situation.

During the power supply of the fuel cell stack, the fuel cell stack supplies power to the power supply circuit of the transport system. In this case the operation of the transport system can be fitted to occur with a limited movement, such as with a limited operating area of the transport appliance, e.g. of the elevator car, or with limited speed or limited acceleration of the transport appliance. Thus the power taken by the transport system during the power supply of the fuel cell stack is reduced, in which case the fuel cell stack can be dimensioned to be of a smaller power output.

According to one embodiment of the invention it is possible to use a fuel cell stack temporarily, such as only during a malfunction of the electricity network.

When the iuel cell stack can be dimensioned to be of a smaller power output, or when the fuel cell stack is used temporarily, such as only during a malfunction of the electricity network, also e.g. the fuel reservoirs of the fuel cell stack can be dimensioned to be smaller. In this case the size of the fuel cell stack is also small, and this kind of fuel cell stack is easy to dispose in connection with a transport system, such as with an elevator system. This is of benefit in so-called elevators without machine rooms, in which the fuel cell stack can be disposed e.g. in the elevator hoistway.

Presentation of drawings

In the following, the invention will be described in more detail by the aid of a few examples of its embodiments with reference to the attached drawings, wherein

Fig. 1 presents one elevator system according to the invention.

Fig. 2 presents a second elevator system according to the invention.

Fig. 3 presents a power supply arrangement of a fuel cell stack in the power supply circuit of a transport system.

Fig. 4 presents a power supply arrangement of a lithium-ion battery in the power supply circuit of a transport system.

Fig. 1 presents an elevator system according to the invention. The elevator system comprises an elevator motor 1 , and also a power supply circuit 2 of the elevator system connected to the elevator motor. A fuel cell stack 3 as well as a temporary storage of electrical energy 4 are connected to the power supply circuit 2 of the elevator system. The temporary storage of electrical energy 4 here comprises a lithium-ion battery. The power supply circuit 2 of the elevator system is connected to the electricity network 5. A supply lead comes from the electricity network to the supply board 16 of the elevator, where the electricity supply is branched. The supply board 16 also comprises a switch arrangement, with which the electricity network 5 is isolated from the power supply circuit 2 of the elevator system during a malfunction of the electricity network, and with which switch arrangement on the other hand the fuel cell stack 3 is connected to supply power in the power supply circuit 2 of the elevator system during the aforementioned malfunction of the electricity network. Electricity is supplied from the supply board to the elevator motor 1 via the intermediate circuit power supply appliance 10 of the motor. Electricity is supplied from the supply board 16 also to the power supply circuit 9 of the electrification of the elevator system. The power supply circuit of the electrification comprises at least the power supply circuit 12 of the lighting of the elevator, the power supply circuit 13 of the safety devices of the elevator, the power supply circuit 14 of the elevator control electronics, and also the power supply circuit 15 of the hoistway electrification. The power supply circuit of the safety devices of the elevator refers to the power supply of the safety devices, such as at least the brake of the elevator machine or the car brake, or of the safety circuits of the elevator. The power supply of the elevator control electronics refers to, among other things, the power supply of the elevator control system, such as of the traffic control, the allocation of

elevator calls, the landing display appliances and the landing call appliances as well as of the control panels of the car. The power supply circuit 2 of the elevator system comprises at least a first controllable switch 7 for controlling the power supply of the fuel cell stack 3. The power supply between the fuel cell stack 3 and the supply board 16 is fitted to occur with the control of at least the first controllable switch 7. The power supply between the fuel cell stack 3 and the supply board 16 can in this case be permitted and on the other also be prevented by controlling at least the aforementioned controllable switch 7. The electricity supply of the fuel cell stack 3 branches in the supply board 16, so that power can be supplied if necessary with the fuel cell stack from the supply board 16 to the intermediate circuit power supply appliance 10 as well as to the power supply circuit 9 of the electrification of the elevator system. The power supply circuit 2 of the elevator system also comprises a second controllable switch 8. The power supply between the temporary storage of electrical energy 4 and the intermediate circuit of the power supply appliance 10 of the motor is fitted to occur with the control of at least the aforementioned second controllable switch 8. The control 17 of the power supply of the temporary storage of electrical energy determines the operating status of the elevator motor by means of the electrical magnitudes of the power supply appliance 10 of the motor. When it detects that the elevator motor is taking power from the intermediate circuit power supply appliance 10 of the motor during motor operation, the aforementioned control 17 of the power supply controls at least the switch 8 such that power is transmitted from the temporary storage of electrical energy 4 to the intermediate circuit 11 of the power supply appliance of the motor. When it detects that the elevator motor is returning power to the power supply appliance 10 of the motor during motor braking, the control 17 of the power supply controls at least the switch 8 such that power is transmitted from the intermediate circuit 11 of the power supply appliance of the motor to the temporary storage of electrical energy 4. The transport system also comprises a determination 6 of the status of the electrical network. The status of the electricity network is determined, and when a malfunction of the electricity network is detected, such as a power outage or a reduction of the supply

voltage, the power supply from the fuel cell stack 3 to the power supply circuit 2 of the transport system is started by controlling at least the first controllable switch 7, as described above. Driving with the elevator car during the power supply of the fuel cell stack with limited speed and limited acceleration is also possible, if it is desired to limit the power taken by the elevator system. This is not necessarily, however, needed when/if the fuel cell stack has been dimensioned according to the power requirement during normal operation of the elevator system.

Fig. 2 presents another elevator system according to the invention. Here the power supply to the power supply circuit 9 of the electrification of the elevator system occurs via a power source 21 that is separate to the intermediate circuit

11 of the power supply appliance of the motor. Also the fuel cell stack 3 is in this case connected to the intermediate circuit 11 of the power supply appliance of the motor such that the power supply between the fuel cell stack 3 and the power supply circuit 9 of the electrification of the elevator system is fitted to occur via the intermediate circuit 11 with the control of at least the first controllable switch 7.

Fig. 3 presents a power supply arrangement of a fuel cell stack 3 in the power supply circuit 2 of a transport system. The positive 3 and the negative 3' pole of the output voltage of the fuel cell stack are connected to an H-bridge 18. With the H-bridge 18 the poles of the primary winding of the transformer 20 are connected in turn to the positive 3 and the negative 3' voltage potential, in which case alternating voltage is produced in the secondary winding in the transformer. In this case the power supply between the fuel cell stack 3 and the power supply circuit 9 of the electrification of the transport system is fitted to occur with the control of at least the aforementioned first controllable switch 7, when the secondary winding of the transformer 20 is connected to the phases 9 and 9' of the power supply circuit. An overvoltage protector 19 is also here connected to the secondary winding of the transformer.

Fig. 4 presents a power supply arrangement of a lithium-ion battery 4 functioning as a temporary storage of electrical energy in the power supply circuit 2 of a transport system. A choke is connected to the positive pole of the lithium-ion battery 4. The negative pole of the lithium-ion battery is connected to the negative intermediate circuit busbar 11 ' of the power supply appliance of the motor. The other pole of the choke is connected between two controllable switches that are connected in series. The lithium-ion battery is discharged or charged via the choke with the controllable switches such that the power supply between the lithium-ion battery 4 and the intermediate circuit 11 , 11' of the power supply appliance of the motor is occurs with the control of at least the aforementioned second controllable switch 8. In this case power supply between the intermediate circuit 11 , 11' of the power supply appliance of the motor and the lithium-ion battery 4 is possible in both directions.

The invention is not limited solely to the embodiments described above, but instead many variations are possible within the scope of the inventive concept defined by the claims below.