Control device for handling the transfer of electric power

Abstract

Electric power is transferred to an electric load as alternating current over at least two incoming and outgoing lines. At least one line circuit manages at least one parameter of the transferred electric power. A central circuit exchanges data and/or commands with the at least one line circuit over a respective galvanically isolated communication interface, such that a reference potential of the central circuit is floating relative to an earth potential of the at least two incoming and outgoing lines. A respective surge protection capacitor is arranged in parallel with each galvanically isolated communication interface. The surge protection capacitors are configured to accumulate a respective fraction of an electric charge resulting from an undesired overvoltage on one of said incoming lines so as to split up the undesired overvoltage into two or more voltages over the galvanically isolated communication interfaces each of which voltage is smaller than the undesired overvoltage.

Claims

1. A control device for handling the transfer of electric power from an electric power source to an electric load, electric power being supplied in the form of alternating current via at least two incoming lines and being delivered via at least two outgoing lines, the control device comprising: at least one line circuit configured to manage at least one parameter of the electric power being transferred via a particular one of said at least two outgoing lines, a central circuit configured to exchange data and/or commands with the at least one line circuit over a respective galvanically isolated communication interface rendering a reference potential of the central circuit floating relative to an earth potential of the at least two incoming and outgoing lines, a respective surge protection capacitor is arranged in parallel with each of said galvanically isolated communication interfaces, said surge protection capacitors being configured to accumulate a respective fraction of an electric charge resulting from an undesired overvoltage on one of said incoming lines so as to split up the undesired overvoltage into two or more voltages over said galvanically isolated communication interfaces each of which voltage is smaller than the undesired overvoltage.

2. The control device according to claim 1, wherein the surge protection capacitors all have the same value.

3. The control device according to claim 1, wherein each of the surge protection capacitors is communicatively separated from the respective galvanically isolated communication interface in parallel with which it is arranged.

4. The control device according to claim 1, wherein one of the at least one line circuit is a charge control circuit configured to manage charging of at least one battery comprised in the load.

5. The control device according to claim 4, wherein the charge control circuit is connected to a protected earth voltage line associated with the at least two incoming and outgoing lines.

6. The control device according to claim 5, wherein the central circuit is implemented in accordance with the extra-low voltage directive of the European Union.

7. The control device according to claim 4, wherein the central circuit comprises a communication interface arranged to exchange data and/or commands with a remote server.

8. The control device according to claim 7, wherein the communication interface is implemented as a power line communication interface configured to exchange the data and/or commands with the remote server via a subset of the at least two incoming lines.

9. The control device according to claim 7, wherein the communication interface is implemented as a wireless communication interface.

10. The control device according to claim 1, further comprising an overvoltage-protection circuit connected between at least one of the incoming lines and a power supply to the central circuit, which overvoltage-protection circuit is configured to protect the power supply from any overvoltages in said at least one line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is now to be explained more closely by means of preferred embodiments, which are disclosed as examples, and with reference to the attached drawings.

(2) FIG. 1 shows a block diagram over a control device according to a first embodiment of the invention;

(3) FIG. 2 illustrates schematically how the voltage of an incoming spike is divided between the two surge protection capacitors in the design of FIG. 1;

(4) FIG. 3 shows a block diagram over a control device according to a second embodiment of the invention;

(5) FIG. 4 illustrates schematically how the voltage of an incoming spike is divided between the four surge protection capacitors in the design of FIG. 3;

(6) FIG. 5 shows a block diagram over a control device according to a third embodiment of the invention; and

(7) FIG. 6 illustrates schematically how the voltage of an incoming spike is divided between the four surge protection capacitors in the design of FIG. 5.

DETAILED DESCRIPTION

(8) FIG. 1 depicts a block diagram over a control device according to a first embodiment of the invention. The control device handles the transfer of electric power from an electric power source, for example a power grid, to an electric load LD.

(9) The electric power is supplied in the form of alternating current, e.g. 230 V at 50 Hz, via two incoming lines L.sub.IN and N.sub.IN respectively. The electric power is delivered to the load LD via two outgoing lines L.sub.OUT and N.sub.OUT respectively. Moreover, the incoming lines L.sub.IN and N.sub.IN are associated with a protected earth voltage line PE.sub.IN, which is connected to the load LD via a line PE.sub.OUT associated with the incoming and outgoing lines L.sub.OUT and N.sub.OUT. The protected earth voltage line PE.sub.IN/PE.sub.OUT also connected to the control device as will be described below.

(10) The control device contains first and second line circuits 101 and 120 respectively. The first line circuit 101 is configured to manage at least one parameter of the electric power being transferred via a particular one of the outgoing lines L.sub.OUT and N.sub.OUT. For example, this may involve registering a current magnitude and/or measuring an amount of power delivered to the load LD. The management performed by the first line circuit 101 may further involve connecting/disconnecting the load LD to/from the incoming lines L.sub.IN and N.sub.IN, for instance in response to an external input, e.g. in the form of commands EXT as will be described below with reference to FIGS. 3 and 5.

(11) The second line circuit 120 preferably manages at least one parameter different from the at least one parameter handled by the first line circuit 101. For example, if the electric load LD is a battery of an electric vehicle, the second line circuit 120 may implement a charge control circuit for managing the charging process.

(12) A central circuit 110 in the control device is configured to exchange data and/or commands dc and dc4 with the line circuits 101 and 120 over a respective galvanically isolated communication interface 111 and 324. As a result, the central circuit 110 becomes a “floating island” 130 with respect to voltage potentials. This means that there is no voltage reference, such as earth voltage, linking the voltages in the central circuit 110 to any external voltage levels. In other words, a reference potential of the central circuit 110 is floating relative to an earth potential of the incoming and outgoing lines L.sub.IN, N.sub.IN and L.sub.OUT, N.sub.OUT respectively.

(13) A respective surge protection capacitor 141 and 344 is arranged in parallel with each of the galvanically isolated communication interfaces 111 and 324. The purpose of the surge protection capacitors 141 and 344 is to store electric charges in case of an undesired overvoltage occurring in the power lines.

(14) To this aim, each of the surge protection capacitors 141 and 344 is connected to a zero-volt/earth potential of the circuit concerned. I.e. the surge protection capacitor 141 is connected between the earth potential of the first line circuit 101 and the zerovolt potential of the central circuit 110, and the surge protection capacitor 344 is connected between the zero-volt potential of the central circuit 110 and the earth potential of the second line circuit 120.

(15) Specifically, the surge protection capacitors 141 and 344 are configured to accumulate a respective fraction of an electric charge resulting from an undesired overvoltage, such as a spike V, on an incoming line, say L.sub.IN, so as to split up the undesired overvoltage V into two smaller voltages over the galvanically isolated communication interfaces 111 and 324. Therefore, each surge protection capacitor 141 and 344 must be selected so that it is capable of withstanding the voltage to which it may be exposed. Preferably, the surge protection capacitors 141 and 344 are so-called safety capacitors. Depending on the rating, these capacitors are capable of withstanding 5 kV to 8 kV.

(16) Referring now to FIG. 2, we see a schematic illustration of how the voltage of the undesired overvoltage V is divided between the two surge protection capacitors 141 and 344. This voltage-split up is the result of the central circuit 110 being a “floating island” 130 as described above. Assuming that both the surge protection capacitors 141 and 344 have the same capacitance value C, preferably a rather high value—for example in the order of nF—half the voltage V/2 of the undesired overvoltage V will placed over each surge protection capacitor 141 and 344 respectively. According to the invention, any other mutual size ratio than 1:1 between the capacitor values is conceivable. For example if the risk of voltage spikes is estimated to be higher on one or more lines and/or if particular interfaces are more/less vulnerable to voltage spikes it may be beneficial to use nonsymmetric capacitor values. However, if the risk of voltage spikes is estimated to be essentially the same on both/all lines, it is advantageous that the surge protection capacitors have identical values.

(17) According to one embodiment of the invention, an overvoltage-protection circuit 150 is connected between one of the incoming lines, here exemplified by L.sub.IN, and a power supply 151 to the central circuit 110. Specifically, the power supply 151 implements an AC/DC unit configured to provide the central circuit 110 with suitable direct-current power. The overvoltage-protection circuit 150 is configured to protect the power supply 151 from any overvoltages in the incoming line L.sub.IN.

(18) FIG. 3 shows a block diagram over a control device according to a second embodiment of the invention. Here, all reference numbers, which also occur in, FIG. 1 designate the same components and entities as those described above with reference to FIG. 1.

(19) In FIG. 3, electric power is transferred from an electric power source the electric load LD via in total five incoming lines L.sub.1IN, L.sub.2IN, L.sub.3IN, N.sub.IN and PE.sub.IN and five outgoing lines L.sub.1OUT, L.sub.2OUT) L.sub.3OUT and PE.sub.OUT. Under error-free conditions, no currents will be fed via the PE.sub.IN/PE.sub.OUT lines; and if the load is symmetric, no currents will be fed via the N.sub.IN/N.sub.OUT lines either. Thus, depending on the conditions, the lines L.sub.1IN, L.sub.2IN L.sub.3IN and N.sub.IN/N.sub.OUT are involved in the actual transfer of electric power. Here, the electric power is supplied in the form of alternating current in three separate phases, e.g. at 50 Hz with each 230 V phase voltage to earth, i.e. with 400 V between any two of the phase lines.

(20) The control device contains a central circuit 310 and line circuits 301, 302, 303 and 320. Analogous to the first embodiment shown in FIG. 1, each of the line circuits 301, 302, 303 and 320 is configured to manage at least one parameter of the electric power being transferred via a particular one of the outgoing lines L.sub.1OUT, L.sub.2OUT, L.sub.3OUT and PE.sub.OUT respectively.

(21) The management performed by the line circuits 301, 302 and 303 may relate to one or more first parameters, such as repeatedly registering current values and/or measuring power consumption of the load LD and/or performing switching operations, e.g. connecting and disconnecting the electric load LD to/from the power lines. The line circuit 320, however, may perform a task different from those effected in the line circuits 301, 302 and 303. For example, if the electric load LD is a battery of an electric vehicle, the line circuit 320 may implement a charge control circuit for managing the charging process. In any case, the line circuit 320 is connected to the protected earth voltage line PE.sub.IN/PE.sub.OUT.

(22) The central circuit 310 is configured to exchange data and/or commands dc1, dc2, dc3 and dc4 with the line circuits 301, 302, 303 and 320 over a respective galvanically isolated communication interface 311, 312, 313 and 324. Thus, the central circuit 310 may effect actions with respect to the line circuits 301, 302, 303 and 320, such as switching operations, and/or readout measured parameters, such as current magnitude and/or power consumption. Analogous to the above, the galvanically isolated communication interfaces 311, 312, 313 and 324 render a reference potential of the central circuit 310 floating relative to an earth potential of the at least two incoming and outgoing lines L.sub.1IN, L.sub.2IN, L.sub.3IN, N.sub.IN and PE.sub.IN and L.sub.1OUT, L.sub.2OUT, L.sub.3OUT and PE.sub.OUT respectively.

(23) Furthermore, a respective surge protection capacitor 341, 342, 343 and 344 is arranged in parallel with each galvanically isolated communication interface 311, 312, 313 and 324. The surge protection capacitors 341, 342, 343 and 344 are configured to accumulate a respective fraction of an electric charge resulting from an undesired overvoltage V on one of the incoming lines L.sub.1IN, L.sub.2IN, L.sub.3IN or PE.sub.IN, so as to split up the undesired overvoltage V. Here, however, provided that all the surge protection capacitors 341, 342, 343 and 344 have the same value C, the voltage is divided into the fractions 3V/4 and V/4 respectively over the galvanically isolated communication interfaces 311, 312, 313 and 324 and via the associated the surge protection capacitors 341, 342, 343 and 344 respectively as illustrated in FIG. 4. Nevertheless, of course, each voltage fraction is smaller than the undesired overvoltage V. For example, if the undesired overvoltage V amounts to 4 kV, none of the fractions exceeds 3 kV, or in the general case 75% of the overvoltage V magnitude. This is the result of the three-to-four relationship between the lines, the equal capacitor values and the fact that the central circuit 310 represents a “floating island” from a voltage perspective.

(24) According to one embodiment of the invention, the central circuit 310 contains a communication interface 315 arranged to exchange data and/or commands EXT with a remote server. Here, the communication interface is implemented as a wireless communication interface 315, for example a radio interface according the Bluetooth, BLE (Bluetooth Low Energy) and/or the IEEE 802.11 (or so-called WiFi) standard.

(25) Preferably, to obtain convenient supply of power to the central circuit 310, the central circuit 310 is provided a power supply 351, e.g. in the form of an AC/DC converter. The power supply 351, in turn, is connected between one of the incoming phase lines, say L.sub.1IN and the incoming zero line N.sub.IN. To prevent surges and similar kinds of overvoltages from damaging the AC/DC converter, this power connection is made via an overvoltage-protection circuit 350. The overvoltage-protection circuit 350 may for example include an avalanche/Zener diode, a gas-filled/discharge tube, a metal oxide varistor, a transient-voltage-suppression diode and/or a thyrsitor-surge-protection device.

(26) According to one embodiment of the invention, an overvoltage-protection circuit 350 is connected between two of the incoming lines, here exemplified by the phase line L.sub.1IN and the zero line N.sub.IN, and a power supply 351 to the central circuit 310. The power supply 351 contains an AC/DC unit providing the central circuit 310 with suitable direct-current power. The overvoltage-protection circuit is configured to protect the power supply 351 from any overvoltages in the phase line L.sub.1IN or the zero line N.sub.IN.

(27) FIG. 5 shows a block diagram over a control device for handling the transfer of electric power from an electric power source to an electric load LD according to a third embodiment of the invention. Here, all reference numbers, which also occur in FIG. 1 or 3, designate the same components and entities as those, described above with reference to FIGS. 1 and 3 respectively.

(28) In FIG. 5, the control device contains line circuits 301, 302, 303 and 120 respectively and a central circuit 510. The electric power is supplied in the form of alternating current via five incoming lines, namely L.sub.1IN, L.sub.2IN, L.sub.3IN, N.sub.IN and PE.sub.IN, and is delivered to the load LD in the form of alternating current via five outgoing lines L.sub.1OUT, L.sub.2OUT, L.sub.3OUT, N.sub.OUT and PE.sub.OUT. Analogous to the second embodiment shown in FIG. 3, the electric power is supplied in the form of alternating current in three separate phases, e.g. at 50 Hz with each 230 V phase voltage to earth, i.e. with 400 V between any two of the phase lines.

(29) The central circuit 510 is configured to exchange data and/or commands dc1, dc2, dc3 and dc4 with the line circuits 301, 302, 303 and 320 over a respective galvanically isolated communication interface 311, 312, 313 and 324.

(30) As a result, a reference potential of the central circuit 510 becomes floating relative to an earth potential of the incoming and outgoing lines, i.e. the central circuit 510 is a “floating island” 530 from a voltage point-of-view. A respective surge protection capacitor 341, 342, 343 and 344 is arranged in parallel with each of the galvanically isolated communication interfaces 311, 312, 313 and 324. The surge protection capacitors 341, 342, 343 and 344 are configured to accumulate a respective fraction of an electric charge resulting from an undesired overvoltage V on one of the incoming lines, say L.sub.1IN, so as to split up the undesired overvoltage V into voltage fractions 3V/4 and V/4 over the galvanically isolated communication interfaces as illustrated in FIG. 6. This presumes that all the surge protection capacitors 341, 342, 343 and 344 have the same value C, which is preferable if the risk of voltage spikes is estimated to be essentially the same on all the lines L.sub.1IN, L.sub.2IN, L.sub.3IN, N.sub.IN, PE.sub.IN, L.sub.1OUT, L.sub.20uT, L.sub.3OUT, N.sub.OUT and PE.sub.OUT.

(31) Analogous to the second embodiment described above with reference to FIGS. 3 and 4, each of the voltage fractions 3V/4 and V/4 is smaller than the undesired overvoltage V. Consequently, the voltage-breakdown requirements on the galvanically isolated communication interfaces can be mitigated by 25%.

(32) In further analogy to the first embodiment described above with reference to FIG. 1, an overvoltage-protection circuit 150 may connected between one of the incoming lines L.sub.IN and a power supply 351 to the central circuit 110. Here, such the overvoltage-protection circuit 150 is also connected to a power supply 134 to the line circuit 120. Each of said power supplies 351 and 134 implements an AC/DC unit configured to provide the central circuit 110 and the line circuit 120 respectively with appropriate direct-current power. The overvoltage-protection circuit 150 is configured to protect both the power supplies 351 and 134 from any overvoltages in the incoming line L.sub.IN.

(33) The term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components. However, the term does not preclude the presence or addition of one or more additional features, integers, steps or components or groups thereof.

(34) The invention is not restricted to the described embodiments in the figures, but may be varied freely within the scope of the claims.