The invention relates to a switch module for a power supply network and a power supply network comprising at least one switch module.
Particularly in vehicles of future technologies redundancy of the electrical power supply is required in several subsystems. Obvious applications are safety critical systems like brakes, steering, etc. There are also other systems which influence the real time behaviour of the vehicle such as chassis control and the like, powertrain components such as valves etc., electrically controlled gearboxes and the like. Some of today's mechanical components may completely rely on electronic control. An electrical failure can lead to a mechanical breakdown.
It is known in the art that a typical automotive electrical power supply network is provided with a star configuration or a daisy-chain configuration. A short circuit in any point of such configurations shuts down the complete network downstream the nearest fuse to the short circuit.
It is also known to provide electrical power supply networks featuring a ring configuration. For providing redundancy several solutions are known in the art. There are completely separated redundant systems with different communication, power supply, sensors and actuators. The redundant systems meet in a mechanical domain or in some cases in a magnetically domain in an electrical actuator with multiple windings. Although the redundancy can be easily analysed the solution is very expensive for volume production, e.g. in vehicle manufacturing.
A simple solution for each unit in the power supply network is provided by using local energy backup. However, the energy resources are limited, it is expensive to build supervision of energy storage in each node and the management of selected energy sources is necessary.
Another solution is to use dual supply to each node (dual star network supply). Thus, two independent supply networks are available. However, dual harness and management of selected energy sources is necessary.
The U.S. Pat. No. 6,552,442 B1 discloses a power supply network with a ring configuration. For each load a tap controller is provided which is composed of an intelligent control node and two controllable power dividers and a controllable conductor protector such as a circuit breaker. The control node controls both power dividers and the conductor protector. For proper functioning of the two controllable power dividers a communication with the intelligent control node is a necessary condition.
EP 1759929 A1 discloses a power supply system for a vehicle, wherein each load is connected to an electrical power supply network. The loads are connected to the power feed via a switch which is controlled by a control unit. Each switch is connected to a communication bus. The switch disconnects the load from the power feed in case of an abnormal current.
It is desirable to provide an improved electrical power supply network which is redundant if a switch fails. It is also desirable to provide an improved switch module for an electrical power supply network. It is also desirable to provide a method for operating the switch module.
A switch module provided for connecting at least two conductor segments of an electrical power supply network is proposed, the electrical power supply network comprising one or more power sources and one or more electrical loads. A switch is provided with a dedicated control unit for controlling the switch. By providing the switch with a dedicated control unit for this particular switch, an autonomous operation of the switch can be achieved as well as a redundant operation of the respective electrical power supply switch. By way of example, in a typical ring configuration of an electrical power supply network known in the art two switches are provided with one common control module for the two switches. If the controller breaks, the load inevitably looses power. By preferably providing two preferred autonomous switch modules according to the invention for one load redundancy of supplying power to the load is possible even if one of the controllers fails. A communication between individual switch modules within a plurality of switch modules is not mandatory as the switch units operate autonomously. The load can be an electric device, an electric motor or the like. The switch itself can be a relay, a semiconductor switch built with bipolar or MOSFET transistors or what is appropriate as switch in a particular switch module for a desired electrical power supply network.
Each control unit comprises a selection unit for selecting a state of operation of the switch coupled to the respective control unit. The selection unit can be implemented as software or hardware or a combination of software and hardware. Particularly, the control unit can comprise a current and a voltage supervision and a state machine. A state machine can be best understood as a model of behaviour composed of a finite number of states, transitions between those states and actions.
Other than the prior art, the switch can operate autonomously and hence does not need a connection to a communication bus for being operative. Thus, the control unit can decide autonomously which operation state of the switch, e.g. an “on” operation state with the switch closed or an “off operation state with the switch open has to be applied. Due to the autonomous operation the switch module, by way of example in an electrical power supply network, does not rely on communication to other switch modules (nodes) or a main computer, particularly not for a real time behaviour of the switch module. The decisions on the state of operation of the switch can be taken by the particular state machine of the switch. In certain cases, however, communication can be advantageously used for setting parameters and supervision of the switch modules. Advantageously, the switch module can comprise at least one communication unit for communicating at least with one or more switch modules and/or a power management system. For instance, a feed back about a power failure and a probable location of the failure can be given to such a power management system. Preferably this at least one communication unit can be integrated in the control unit. The communication unit can be coupled to a data bus system or the like.
Optionally it is possible that each switch module comprises an “intelligent” local power management system instead of a central power management system. These local power management systems can form a grid of intelligent computers which dynamically collaborate in managing the power distribution etc. of the whole system (“distributed intelligence”). The system can be autarkic without any central station. By employing such a distributed system redundancy and safety of the system can be improved further.
Preferably, the state of operation of the switch is selectable depending on one or more operating parameters of the electrical power supply network.
The autonomous switch module enables to build a simple and low cost redundant power supply system. Circular power supply systems yield redundancy without having a double power supply system. The autonomous switch makes the selection process of power supply line robust and easy to analyse, which is important for critical systems.
The state machine can be implemented in several different ways, e.g. in software or in hardware or in a combination of both. A very simple implementation for instance, which is particularly useful for a dual star network, is to have two diodes (one for each supply-line), in combination with one or more fuses or other current limiting devices.
According to an advantageous development of the invention, the switch module can comprise at least one programmable unit for setting operating parameters of each switch. Preferably this at least one programmable unit can be integrated in the control unit.
Preferably, a current sensor and/or a voltage sensor can be coupled to each switch. The current can be detected on either side of the switch. The voltage is advantageously detected on both side of the switch. A minimum voltage can be set for each switch. A high degree of safety can be achieved if two voltage sensors are provided, one at each side of the switch, additionally to a current sensor. If the safety requirements are lower, a less number of sensors can be used. If the detected voltage is above the minimum voltage, the power supply network is considered as working properly, if the detected voltage is below the minimum voltage, a failure is recognized by the control unit and the state of operation of the switch is set accordingly. In this case, the voltage limit is set to a value that if the actual voltage is equal to or below this limit, the voltage is considered to be too low. Alternatively, it is possible to set a voltage limit in a way that in case the actual voltage is above or equal to the limit the power supply network is considered as working properly and if the actual voltage is below the voltage limit, a failure is recognized.
Proposed is also a method for operating a switch module connecting at least two conductor segments of an electrical power supply network, the electrical power supply network being powered by one or more power sources and supplying one or more electrical loads. A state of operation of a switch is controlled by a dedicated control unit provided for the switch.
Preferably, the state of operation of the switch can be selected depending on operating parameters of the switch and/or operating parameters of the electrical power supply network. Particularly, the switch can be operated depending on an electrical current through the switch and an electrical voltage on both sides of the switch.
According to another aspect of the invention, an electrical power supply network is proposed, comprising one or more power sources and one or more electrical loads and comprising at least one switch module which is provided for electrically connecting and disconnecting at least two conductor segments.
The electrical power supply network can be arranged in a star configuration of power distribution, in a double star configuration of power distribution, in a ring configuration of power distribution, or in a combination of two or more of the said configurations of power distribution.
Preferably, a first and a second autonomous switch module can be provided for each load particularly in the ring configuration of power distribution.
According to a preferred embodiment, the switch module can be arranged outside an electric load which is coupled to the electrical circuit.
According to another preferred embodiment, the switch module can be integrated into an electric load. It is also possible to combine these two embodiments, wherein at least one load in the electrical power supply network comprising at least one autonomous switch module is provided with an integrated autonomous switch module.
According to another aspect of the invention, a vehicle comprises an electrical power supply network which comprises at least one autonomous switch module. The vehicle can for instance be an electric vehicle or a hybrid vehicle comprising e.g. an electric motor and a combustion engine which both provide energy for propulsion of the vehicle. The preferred autonomous switch module is particularly useful for providing a redundant automotive power supply. Expediently, the particular vehicle can feature a ring configuration of power distribution. Favourably, a power supply redundancy can be achieved particularly for control units, actuators and/or sensors. Many vehicular systems which are used for supporting the driver or which are used for increasing the vehicle safety and the driving comfort rely on such electrical components.
The vehicle can be a landborne vehicle or a seaborne vehicle, such as a ship or submarine, or an airborne vehicle, such as an airplane or a space vehicle. The term “landborne vehicle” comprises for instance passenger cars, busses, trucks, motorbikes, trains, construction equipment and the like, particularly wheeled and crawler excavators (diggers), articulated haulers (such as dumpers, dump trucks), scraper haulers, wheel loaders, pipelayers, demolition equipment, waste handlers, motor graders, pavers, compactors, milling equipment, tack distributors, road wideners, material-transfer vehicles and a range of compact equipment such as mini loaders, mini excavators, backhoe loaders and skidsteer loaders.
According to another aspect of the invention, a working machine comprises an electrical power supply network which comprises at least one autonomous switch module. The working machine can for instance be a stationary electric working machine or a stationary hybrid working machine comprising e.g. an electric motor and a combustion engine which both provide energy for moving one or more tools of the working machine. The preferred autonomous switch module is particularly useful for providing a redundant power supply. Expediently, the particular working machine can feature a ring configuration of power distribution. Favourably, a power supply redundancy can be achieved particularly for control units, actuators and/or sensors. Many working machine systems which are used for supporting the operator or which are used for increasing the working machine safety and the operating comfort rely on such electrical components.
According to another aspect of the invention, an energy supply facility comprises an electrical power supply network which comprises at least one autonomous switch module. The energy supply facility can for instance be a stationary energy supply facility or a mobile energy supply facility which provides energy for a multitude of users such as households or industrial plants. The preferred autonomous switch module is particularly useful for providing a redundant power supply. Expediently, the particular energy supply facility can feature a ring configuration of power distribution. Favourably, a power supply redundancy can be achieved. Particularly, the energy supply facility can be an emergency backup generator.
The present invention together with the above-mentioned and other objects and advantages may best be understood from the following detailed description of the embodiments, but not restricted to the embodiments, wherein is shown schematically:
a-6e simulation results for voltage characteristics of the loads implemented in the electrical power supply network of
In the drawings, equal or similar elements are referred to by equal reference numerals. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. Moreover, the drawings are intended to depict only typical embodiments of the invention and therefore should not be considered as limiting the scope of the invention.
The switch module 10 comprises a switch 12 and a control unit 20 for controlling the switch 12. A current sensor 14 on one of the two sides of the switch 12, a first voltage sensor 16 on one side of the switch 12 (hereinafter called the “a” side) and another voltage sensor 18 on the other side of the switch 12 (hereinafter called the “b” side) are arranged for sensing the electrical current through the switch 12 and the voltage on each side the of the switch 12.
The switch module 10 is implemented as an autonomous component and can be implemented with or without communication to other switch modules (not shown) and/or power management systems (not shown). The autonomous switch module 10 is controlled by a state machine with preset limits, e.g. a current limit and/or a voltage limit, and timings for the performance of the switch module 10.
For diagnostic purposes and adaptation to varying conditions present in the electrical power supply network to which the switch module 10 is coupled, the autonomous switch module 10 can be connected to a supervision function, e.g. via a network and the like. For such purposes at least one communication unit (not shown) is provided in the switch module 10.
The state machine comprised in the control unit 20 operates the switch 12 based on voltage and current information collected by the current sensor 14 and the voltage sensors 16 and 18. Preferably, the control unit 20 comprises a selection unit for selecting a state of operation of the switch 12 coupled to the control unit 20.
The state of operation of the switch 12 is selected by the state machine depending on one or more operating parameters of the electrical power supply network (not shown).
Preferably, the switch module 10 can be integrated in the network, separate from the load. However, the switch module 10 can be integrated in a load 105, as indicated in
Each load 110, 112, 114 is provided with two switch modules 10a, 10b, 10c, 10d, 10e, 10f configured as described in
As indicated in
The circles labelled with parameters “Start”, “Va_Ok”, “VbJDk”, “over_current”, “low_voltage”, “supply_b_to_a”, “supply_a_to_b”, “S8”, “S9” represent states of the state machine, whereas the lines with arrows connecting the circles indicate transitions from one state to another, wherein the arrows indicate the direction from which state to which state the transition occurs. Each transition arrow is referred to with a transition condition such as the transition “var_vb>v_on” between a state represented by circle “Start” and another state represented by circle “vb_Ok”.
The following transitions and states are depicted in
1. Transitions:
2. States:
The example in
Referring now back to the example embodiment in
At a time t=0 the electric power supply network 100 operates correctly without any fault. The autonomous switch modules 10a, 10b . . . 10e, 10f select the power supply 104, 106 as voltage source providing the highest voltage individually for each load 110, 112, 114. At a time t=3.5 s thereafter a short circuit occurs. The short circuit is represented by switch element 130, which can be simulated by closing the switch 130 for a certain time period, for instance δt=0.5 seconds.
The circuit is a simulation of a small system with two power supplies and three loads. At a time t=0 s there are no faults in the system. The autonomous switch modules 10a . . . 10f select the voltage source 104 or 106 with the highest voltage individually for each load 110, 112, 114. At time t=0, only the output voltage 106a of voltage source 106 is above the minimum level set by parameters as can be seen in
Just before the fault occurs, the autonomous switches 12 in the respective switch modules 10a . . . 10f have the following states:
At the time when the short circuit occurs (t=3.5 seconds), the switch module 10c detects an over current as well as switch module 10d. Timeout periods are set with respect to switch positions from the voltage sources 104, 106 to ensure that the switch of the switch module 10a . . . 10f closest to the fault (simulated by switch 130) is opened. “Timeout” means that a condition has been valid for a minimum time (time out period). As a result of the timeout delays the switch of switch module 10c is opened first, and the current has decreased before the timeout period has come to its end for the switch of the switch module 10d.
Just after the fault has occurred, the autonomous switch modules 10a . . . 10f have the following states:
As mentioned above, results of a simulation of voltage characteristics over a time period of δt=5 seconds are shown in
The voltage characteristic 130a of the fault 130 is shown in the lowest
For an electrical power supply network, particularly with a ring configuration this results in an improved performance and safety of the electrical power supply. For instance, the electrical power supply network with a ring configuration can be implemented in a vehicle on-board power supply thus yielding a redundant power supply for electrical loads such as actuators, sensors, electric motors, lamps, control units etc. in the vehicle. For instance, vehicle lights such as brake lights have to fulfil special safety requirements which can be supported by such a redundant electrical power supply network as described above.
In another embodiment, the electrical power supply network with a ring configuration can be implemented in a working machine on-board power supply thus yielding a redundant power supply for electrical loads such as actuators, sensors, electric motors, lamps, control units etc. in the working machine.
In yet another embodiment, the electrical power supply network with a ring configuration can be implemented in a power supply facility thus yielding a redundant power supply for electrical loads of a multitude of user such as buildings or industrial sites. Particularly, the energy supply facility can be an emergency backup generator providing a fail-safe power supply which is active when a main power supply fails.
Number | Date | Country | Kind |
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PCT/SE2008/000354 | May 2008 | SE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/SE2009/000268 | 5/26/2009 | WO | 00 | 10/20/2010 |