Device and method for the voltage equalization of a plurality of two-terminal networks, and DC power distribution system
The disclosure is directed to a device for voltage equalization of a plurality of two-terminal networks. The device includes a current-limiting component, and connection pairs, each having a first connection and a second connection for connecting the two-terminal networks. Two or more of the first connections are each connected to an input. In addition, two or more of the first connections are each connected to an output via a second switch. The second connections are connected or switchably connected to a common reference potential. The device sets switching states of switches by means of a control unit and/or by means of voltages applied to the first connections in such a manner that the current-limiting component intakes power in its input and not in its output, and the current-limiting component outputs power from its output and not from its input.
1 . A device for voltage equalization of a plurality of at least two two-terminal networks, comprising:
a current-limiting circuit comprising an input and an output,
at least two connection pairs, each connection pair having a first connection and a second connection configured to connect the at least two two-terminal networks to other elements of the device,
wherein two or more of the first connections are each connected via a first switch or directly to the input of the current-limiting circuit and two or more of the first connections are furthermore each connected via a second switch to the output of the current-limiting circuit, and
wherein the second connections of the at least two connection pairs are connected or switchably connected to a common reference potential,
wherein the device is configured to set switching states of the first switches and of the second switches via a control circuit and/or via voltages applied to the first connections in such a way that:
the current-limiting circuit receives power from one or more of the first connections via one or more of the first switches or the direct connection, but not via one or more of the second switches, and
the current-limiting circuit outputs power to one or more of the first connections via one or more of the second switches, but not via one or more of the first switches,
so that a unidirectional power flow via the current-limiting circuit from the input to the output is effectuated and a reverse power flow from the output to the input is suppressed.
2 . The device according to claim 1 , wherein the device is configured for a voltage equalization of three or more two-terminal networks and, for this purpose, has three or more connection pairs.
3 . The device according to claim 2 , wherein, at least temporarily, at least three of the first connections are simultaneously involved in a power flow via the current-limiting circuit.
4 . The device according to claim 1 , wherein one or more of the first connections are each connected both via a first switch switchably to the input and via a second switch switchably to the output of the current-limiting circuit, whereby one or more bridge branches having branch taps are formed, which are assigned to respective first connections and each have a series circuit of a respective first switch and a respective second switch, and whose branch taps are connected to the first connections assigned thereto.
5 . The device according to claim 1 , wherein at least one of the first switches and/or at least one of the second switches comprises a unidirectional switch.
6 . The device according to claim 1 , wherein at least one of the first switches and/or at least one of the second switches comprises a diode or is formed as a diode.
7 . The device according to claim 1 , wherein at least one of the first switches or one of the second switches comprises a semiconductor switch or an electromechanical switch that is controlled by the control circuit.
8 . The device according to claim 1 , wherein the current-limiting circuit comprises an ohmic resistor, a thermistor, or an actively controllable semiconductor switch, or wherein the current-limiting circuit comprises a series circuit of two different ones of the ohmic resistor, the thermistor, or the actively controllable semiconductor switch.
9 . The device according to claim 1 , wherein the current-limiting circuit comprises a DC/DC converter that steps down from the input to the output.
10 . The device according to claim 1 , further comprising a switching circuit configured to switchably connect two or more of the first connections with low resistance to one another, in response to the control circuit, wherein the control circuit is configured to connect two or more of the first connections with low resistance to one another depending on a voltage prevailing between the respective first connections.
11 . The device according to claim 10 , wherein the switching circuit provides a switchable low-resistance connection of two or more of the first connections of the at least two two-terminal networks to one another via two or more of the first switches controlled by the control circuit, or via two or more of the second switches controlled by the control circuit.
12 . The device according to claim 10 , further comprising a voltage sensor configured to detect a voltage applied to the current-limiting circuit, wherein the control circuit is configured to operate the switching circuit depending on the voltage applied to the current-limiting circuit.
13 . The device according to claim 1 , further comprising one or more third switches controlled by the control circuit, wherein each of the third switches is arranged between a different one of the first connections and a respective first switch assigned thereto, and/or between a different one of the first connections and a respective second switch assigned thereto.
14 . A method for the voltage equalization of a plurality of at least two two-terminal networks with a device comprising:
a current-limiting circuit comprising an input and an output,
at least two connection pairs, each connection pair having a first connection and a second connection configured to connect the at least two two-terminal networks to other elements of the device,
wherein two or more of the first connections are each connected via a first switch or directly to the input of the current-limiting circuit and two or more of the first connections are furthermore each connected via a second switch to the output of the current-limiting circuit, and
wherein the second connections of the at least two connection pairs are connected or switchably connected to a common reference potential,
wherein the device is configured to set switching states of the first switches and of the second switches via a control circuit and/or via voltages applied to the first connections, the method comprising:
connecting each of the two-terminal networks to a respective one of the connection pairs of the device, provided that they are not already connected, so that two or more of the two-terminal networks are each connected to the input of the current-limiting circuit in a single-terminal manner directly or switchably via a respective one of the first switches, and two or more of the two-terminal networks are each connected to the output of the current-limiting circuit in a single-terminal manner switchably via a respective one of the second switches,
bringing about the voltage equalization by setting switching states of the first switches and of the second switches via the control circuit and/or via voltages applied to the first connections in such a way that
the current-limiting circuit receives power from one or more of the first connections via one or more of the first switches or the direct connection, but not via one or more of the second switches, and
the current-limiting circuit outputs power to one or more of the first connections via one or more of the second switches, but not via one or more of the first switches,
so that a unidirectional power flow via the current-limiting circuit from the input to the output is made possible and a reverse power flow from the output to the input is suppressed.
15 . The method according to claim 14 , wherein two first connections, more than two first connections or all first connections of the two-terminal networks are connected with low resistance to one another via a switching circuit when an absolute value of a voltage applied between the respective first connections reaches or falls below a voltage threshold value.
16 . The method according to claim 14 , wherein two or more power-outputting two-terminal networks with different voltages are connected to the device, wherein power output is facilitated for one of the two-terminal networks whose absolute voltage is maximum, and wherein power outputs for other two-terminal networks are facilitated with a time delay depending on a voltage between a respective first connection assigned thereto and the input of the current-limiting circuit.
17 . The method according to claim 14 , wherein two or more power-consuming two-terminal networks with different voltages are connected to the device, wherein power consumption is facilitated for one two-terminal network whose absolute voltage is minimal, and wherein power consumptions for the other two-terminal networks are facilitated with a time delay depending on a voltage between a respective first connection assigned thereto and the output of the current-limiting circuit.
18 . The method according to claim 14 , further comprising connecting positive terminals of the two-terminal networks to the first connections, and connecting negative terminals of the two-terminal networks to the second connections of the device.
19 . The method according to claim 14 , further comprising connecting negative terminals of the two-terminal networks to the first connections, and connecting positive terminals of the two-terminal networks to the second connections of the device.
20 . A DC power distribution system with voltage-equalizing, connectable two-terminal networks, comprising a device, comprising:
a current-limiting circuit comprising an input and an output,
at least two connection pairs, each connection pair having a first connection and a second connection configured to connect at least two two-terminal networks to other elements of the device,
wherein two or more of the first connections are each connected via a first switch or directly to the input of the current-limiting circuit and two or more of the first connections are furthermore each connected via a second switch to the output of the current-limiting circuit, and
wherein the second connections of the at least two connection pairs are connected or switchably connected to a common reference potential,
wherein the device is configured to set switching states of the first switches and of the second switches via a control circuit and/or via voltages applied to the first connections in such a way that:
the current-limiting circuit receives power from one or more of the first connections via one or more of the first switches or the direct connection, but not via one or more of the second switches, and
the current-limiting circuit outputs power to one or more of the first connections via one or more of the second switches, but not via one or more of the first switches,
so that a unidirectional power flow via the current-limiting circuit from the input to the output is effectuated and a reverse power flow from the output to the input is suppressed.
21 . The DC power distribution system according to claim 20 , wherein at least one of the two-terminal networks comprises one or more of the following:
a DC connection of an inverter having an intermediate circuit capacitance and/or an input capacitance,
an electrolyzer,
a battery,
a DC grid with a capacitance coupled thereto,
a DC output of a rectifier connected to an AC grid, and
a charging cable for an electric vehicle.
22 . The DC power distribution system according to claim 20 , further comprising a power-outputting and non-regenerative two-terminal network, which is directly connected or switchably connected with one of its terminals to the input of the current-limiting circuit and with another of its terminals to the common reference potential.