WO2023165709A1

WO2023165709A1 - A power supply arrangement with a backup battery cell arrangement

Info

Publication number: WO2023165709A1
Application number: PCT/EP2022/055583
Authority: WO
Inventors: Stefan SIGNORI
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2022-03-04
Filing date: 2022-03-04
Publication date: 2023-09-07

Abstract

The present disclosure relates to a power supply arrangement (100) comprising an alternating current, AC, input port (101), a full-wave rectifying arrangement (102) connected to the AC input port (101), a charging/discharging handling device (103), a back-up battery cell arrangement (104) connected to the charging/discharging handling device (103), and an output port (105). The full-wave rectifying arrangement (102) is connected to the charging/discharging handling device (103) and to the output port (105). During normal operation, the full-wave rectifying arrangement (102) is adapted to input an AC input current (iA) via the AC input port (101), to output a full-wave rectified output current (iBO) to the output port (105) and to output a full-wave rectified charging current (iBC) to the charging/discharging handling device (103). Furthermore, the charging/discharging handling device (103) is adapted to convert the full-wave rectified charging current (iBC) to a normalized charging current (iBN) adapted for charging the back-up battery cell arrangement (104). During back-up operation, when there is no AC input current available at the AC input port (101), the back-up battery cell arrangement (104) is adapted to output a DC back-up output current (ico) to the output port (105) via the charging/discharging handling device (103).

Description

TITLE

A power supply arrangement with a backup battery cell arrangement

TECHNICAL FIELD

The present disclosure relates to a power supply arrangement comprising an alternating current (AC) input port and a backup battery cell arrangement.

BACKGROUND

Telecom systems’ hardware are mostly power supplied by public (electric) power distributions systems. The normal is to use an alternating current (AC) supply and different countries/regions apply standardized AC voltages; Low Line (100/110/115/127 VAC) or High Line (200/220/230/240 VAC). For maintaining high availability, in particular resistance to power outages, it is possible to use UPS (Uninterruptible Power Supplies) that include AC/DC (AC to direct current) and DC/ AC conversions with added battery devices in between.

For Telecom systems it is common to down-convert the AC voltage to a touch safe -48V DC and adding a -48V battery device. It means, for a normal non-backup operation that normally occurs most of the time, the voltage conversions are always present with resulting power losses. That is a necessary condition in order to obtain -48V power supply.

Server halls trend to be installed with a power supply with higher voltages, for example around 380V. It is obtained by same principles as -48V architecture; Primary conversion from AC to DC (in this case 380V instead of -48V) and added battery bank(s).

The conversion losses are in the same range as for -48V, while the DC distribution side gains possible savings on distribution losses/distribution cables by distributing a higher voltage (lower currents for same power transfer).

A first typical prior art solution is illustrated in Figure 1, where a power supply arrangement 1 is shown during normal operation when power service is available. A mains port 2 supplies a mains AC current to an AC/DC converter 3 that in turn is connected to an output port 4 that supplies a first output current ii₀ to power consuming devices 5 and a first charging current ii_c to a battery arrangement 6. In this example the first output current ii₀ and the first charging current ii_c are associated with a 380V DC voltage, but any DC voltage, such as for example the above - 48V can also be used. The battery arrangement 6 in turn comprises a charger control device 7, a battery management controller 8 and battery cells 9. During normal operation the battery cells 9 are charged, as schematically indicated, and the first output current ii₀ is output to the power consuming devices 5. Control of charging voltage and charging current may be performed by separate charging circuitry comprised in the battery arrangement 6.

During power failure, i.e. in a power backup mode, when no current is supplied to the input port 2, as illustrated in Figure 2, a second output current i2o is supplied to the power consuming devices 5. In this example, the second output current i2o are associated with a 380V DC voltage that is declining as the battery cells 9 are discharged, as schematically indicated. The AC/DC converter 3 blocks the second output current i2o such that all second output current i2o is fed towards the output port 4.

The AC/DC converter 3 secures a stable DC system voltage for power consumers 5 and regulated battery charging, and prevents power from the battery cells 9 to be drained to an AC grid via the mains port 2 during a power outage. However, for most of the time the AC grid is operating and possible back-feeding to the AC grid from batteries is prevented by the AC/DC converter’s blocking effect, but to the cost of the always present conversion losses.

Battery charging does not benefit of having the whole system voltage regulated/adjustable. This is, for many cases, achievable and also arranged close to, or within, the battery arrangement. By way of example, for Lithium Ion (Li-Ion) battery charging, the charger/current limiting device is arranged within the battery arrangement.

This means that there are power losses in the AC/DC converter 3 during normal operation when power service is available. Further, the AC/DC converter 3 adds to cost and complexity, decreasing reliability.

A second typical prior art solution, a so-called Uninterruptible Power Supply (UPS), is illustrated in Figure 3, where a power supply arrangement 10 is shown during normal operation. A mains port 11 supplies a mains AC current directly to an output port 12 and power consuming devices 18 via a transfer line 19 and a transfer switch 13. A battery arrangement 14 is connected to the mains port 11 via an AC/DC converter 15 such that the battery arrangement 14 is charged during normal operation.

During power failure, i.e. in a power backup mode, when no current is supplied to the input part 11, as illustrated in Figure 4, the transfer switch 13 disconnects the mains port 11 from the output port 12 and instead connects the battery arrangement 14 to the output port 12 via a battery switch 16 and a DC/ AC converter 17. Here, there are power losses in the AC/DC converter 15 during normal operation when power service is available. When power service is unavailable, during power failure, the DC/AC converter 17 induces undesired power losses for all consuming devices that could have been fed directly by battery voltage. The transfer switch 13 is a possible point of failure which makes the charging arrangement 10 less reliable over time.

There are different types of UPS: s, for example the transfer line 19 and the switches 13, 16 can be omitted such that losses in the transfer switch 13 are avoided, while there are losses in both converters 15, 17 during normal operation.

For these and many other types of UPS:s, power needs to be converted. This implicates lower system efficiency when supplied from the battery arrangement 14. The energy loss in DC/AC converter 17 must be compensated by a larger battery arrangement 14 for a given energy towards the power consuming devices 18.

It is thus an object of the present disclosure to provide a more efficient, reliable and versatile power supply arrangement that can be used for any voltages, with reduced power loss, smaller size and less expensive components compared to prior art.

SUMMARY

This object is achieved by means of a power supply arrangement comprising an alternating current (AC) input port, a full-wave rectifying arrangement connected to the AC input port, a charging/discharging handling device, a back-up battery cell arrangement connected to the charging/discharging handling device, and an output port. The full-wave rectifying arrangement is connected to the charging/discharging handling device and to the output port. During normal operation, the full-wave rectifying arrangement is adapted to input an AC input current via the AC input port, to output a full-wave rectified output current to the output port and to output a lullwave rectified charging current to the charging/discharging handling device. Furthermore, the charging/discharging handling device is adapted to convert the full-wave rectified charging current to a normalized charging current adapted for charging the back-up battery cell. During back-up operation, when there is no AC input current available at the AC input port, the back-up battery cell arrangement is adapted to output a direct current (DC) back-up output current to the output port via the charging/discharging handling device.

This means that a less costly, smaller and more reliable power supply arrangement is provided than prior art systems and solutions as described initially. Conversion losses will be negligible compared to constant converting AC to 380V/400V converters. For backup comparison with UPS solutions one can use less capacity in the back-up battery cell arrangement since the DC/AC conversion loss is omitted.

Furthermore, the number of components can be reduced compared to prior art solutions, which saves cost and environmental resources. With less components than in existing solutions the total space/weight of the solution will be less and the mean time between failure (MTBF) will be higher resulting in an increased system availability and less maintenance costs.

According to some aspects, the charging/discharging handling device comprises a switch connection that is adapted to by-pass the charging/discharging handling device during back-up operation.

The charging/discharging handling device is thus adapted to admit passage of the DC back-up output current towards the output port during back-up operation via the switch connection. The DC back-up output current is therefore normally the same before and after the charging/discharging handling device although some losses may be incurred by the charging/discharging handling device.

According to some aspects, the charging/discharging handling device is adapted to synchronize the DC back-up output current, during back-up operation.

This means that the charging/discharging handling device is adapted to determine when there is back-up operation and the DC back-up output current should be output.

According to some aspects, the charging/discharging handling device is adapted to detect if the full-wave rectified charging current is absent, and if that is the case, to synchronize the DC backup output current accordingly.

This means that the procedure of determining when there is back-up operation and the DC backup output current should be output can be based on the appearance of the full-wave rectified charging current, such that it can be properly detected that the charging current is absent.

According to some aspects, the power supply arrangement further comprises a controller device that is adapted to control the charging/discharging handling device.

In this way, charging and discharging as well as battery management can be controlled in an efficient and reliable manner. The controller device may comprise a battery management system (BMS). This object is also achieved by means of electric power systems and methods that are associated with the above advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will now be described more in detail with reference to the appended drawings, where:

Figure 1 schematically shows a first typical prior art power supply arrangement during normal operation;

Figure 2 schematically shows a first typical prior art power supply arrangement during power failure, i.e. in a power backup mode;

Figure 3 schematically shows a second typical prior art power supply arrangement during normal operation;

Figure 4 schematically shows a second typical prior art power supply arrangement during power failure, i.e. in a power backup mode;

Figure 5 schematically shows a power supply arrangement according to the present disclosure during normal operation;

Figure 6 schematically shows a power supply arrangement according to the present disclosure during power failure with back-up operation, i.e. in a power backup mode; and

Figure 7 shows a flowchart for methods according to the present disclosure.

DETAILED DESCRIPTION

Aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings. The different devices, systems, computer programs and methods disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the aspects set forth herein. Like numbers in the drawings refer to like elements throughout.

The terminology used herein is for describing aspects of the disclosure only and is not intended to limit the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. With reference to Figure 5 there is a power supply arrangement 100 according to the present disclosure that during normal operation that comprises an alternating current (AC) input port 101, a full-wave rectifying arrangement 102 connected to the AC input port 101, a charging/discharging handling device 103, a back-up battery cell arrangement 104 connected to the charging/discharging handling device 103, and an output port 105.

The full- wave rectifying arrangement 102 is here illustrated as a full diode bridge, but other configurations are of course conceivable. The full- wave rectifying arrangement 102 is connected to the charging/discharging handling device 103 and to the output port 105. During normal operation, the full-wave rectifying arrangement 102 is adapted to input an AC input current 1A via the AC input port 101, to output a full-wave rectified output current iso to the output port 105 and to output a full-wave rectified charging current iec to the charging/discharging handling device 103. Furthermore, the charging/discharging handling device 103 is adapted to convert the fullwave rectified charging current i BC to a normalized charging current IBN adapted for charging the back-up battery cell arrangement 104,

With reference to Figure 6, during back-up operation when there is no AC input current available at the AC input port 101, the back-up battery cell arrangement 104 is adapted to output a direct current (DC) back-up output current ico to the output port 105 via the charging/discharging handling device 103.

According to some aspects, the output port 105 is connected to one or more power consuming devices 108. Examples of typical power consuming devices are telecom system devices, server hall devices, Radio Access Network (RAN) devices such as Radio receiver/transceivers (RRU:s), Routers, Fronthaul/b ackhaul devices, both microwave and optical devices.

This means that a less costly, smaller and more reliable power supply arrangement is provided than ordinary 380V/400V systems and UPS solutions as described initially.

Conversion losses will be negligible compared to constant converting AC to 380 V/400 V converters. For backup comparison with UPS solutions one can use less capacity in the back-up battery cell arrangement 104 since the DC/ AC conversion loss is omitted.

The present disclosure enables a reduction of the number of components compared to prior art solutions, which saves cost and environmental resources. For example compared to a traditional UPS technology, a need for an inverter DC/ AC is omitted when running in backup mode as the system then will supply the native battery cell arrangement DC voltage. Furthermore, the charging/discharging handling device 103 is dimensioned solely for the needed time and power to recharge and does not need to be dimensioned for both the charging and the full power load of the consumer. The possibility to use a much smaller charging/discharging handling device 103 saves cost and space.

With less components than in existing solutions the total space/weight of the solution will be less and the mean time between failure (MTBF) will be higher resulting in an increased system availability and less maintenance costs.

According to some aspects, the charging/discharging handling device 103 comprises a switch connection 111 (only schematically indicated) that is adapted to by-pass the charging/discharging handling device 103 during back-up operation. The charging/discharging handling device 103 is thus adapted to output the normalized charging current IBN to the back-up battery cell arrangement 104 during normal operation, and to admit passage of the DC back-up output current ico towards the output port 105 during back-up operation via the switch connection 111. The DC back-up output current ico is therefore normally the same before and after the charging/discharging handling device 103 although some losses may be incurred by the charging/discharging handling device 103.

According to some aspects, the charging/discharging handling device 103 is adapted to synchronize the DC back-up output current ico during back-up operation. Determination of when there is back-up operation and the DC back-up output current ico should be output can be based on the appearance of the full-wave rectified charging current iec such that it can be properly detected that the charging current i BC is absent.

Therefore, according to some aspects, the charging/discharging handling device 103 is adapted to detect if the full-wave rectified charging current i BC is absent, and if that is the case, to synchronize the DC back-up output current ico accordingly.

This can be made by measuring the absolute voltage and using a micro circuit for controlling the switch, or a comparator with integration over time, to distinguish a normal zero voltage crossing from abnormal voltage outage/power down. It could also be realized by a gate driver for the switch that is a low-pass filtered comparator with the relative voltage difference, where an internal battery cell voltage is compared with a charging voltage 5; in normal operation it is the full wave rectified sine-wave.

AC is here supplied to the AC input port 101 directly from an AC grid 110, and the a full-wave rectified output current iso, IBC is used directly as primary power source for the power consuming devices 108 and the charging/discharging handling device 103 when used for charging the backup battery cell arrangement 104.

A current blocking mechanism, protecting power drain to the AC grid 110 via the input port 101 is required during back-up operation and can according to some aspects be made in accordance with the battery, internally or externally, with a passive or active diode bridge and possibly in series with a line filter, maintaining EMC performance. According to some aspects, the power supply arrangement 100 further comprises an input filter 106.

According to some aspects, the power supply arrangement 100 further comprises a controller device 107 that is adapted to control the charging/discharging handling device 103. According to some aspects, the controller device 107 comprises a battery management system 109 (BMS).

The charging/discharging handling device 103 is adapted for full wave rectified AC instead of DC, and the BMS 109 needs to be configured to connect the back-up battery cell arrangement 104 when backup is needed, during back-up operation. The controller device 107 is adapted to monitor and control when to enter backup operation and to secure that power is supplied to the power consuming devices 108.

By sensing network quality and controlling the different operation modes, the controller device 107 can provide a smooth transition between the operation modes, from the normal operation to back-up operation and back to normal operation when power is restored at the AC grid 110.

According to some aspects, the controller device 107 with the BMS 109 also serves as an interface, and as a means for securing equal and safe charging and discharging including balancing for multiple battery cells in the battery cell arrangement 104.

The present disclosure also relates to an electric power system 200 comprising the power supply arrangement 100 according to the above and at least one power consuming device 108 that is electrically connected to the output port 105 of the power supply arrangement 100. Each power consuming device 108 is adapted to input electrical power in the form of alternating current (AC) full-wave rectified current, and direct current (DC) via the output port 105.

Generally, using the power supply arrangement 100 for supplying power consuming devices 108 requires the power consuming devices 108 to be arranged in such way that the different operation modes/voltages of the power supply arrangement 100 are compatible with the design premises. A normal design in an AC supplied power consumer 108 comprises a converter topology called PFC boost converter. The essence of that is that it rectifies an AC voltage to be DC and boosts the voltage to a higher potential.

Since the primary circuits of a PFC boost converter usually comprise a full of half diode bridge used to convert the supplied power to DC, the PFC boost converter is natively handling also full wave rectified AC, and a criterion is that comparable DC voltage should be compatible/comparable with the voltage/current dimensioning of the components used. That criterion is unintentionally fulfilled for many cases with existing PFC boost converters for the combination of either High- line AC or full-wave rectified High-Line AC or 380VDC ranges, in principle not excluding other nearby voltage ranges. To secure a fully compatible application with the new arrangement the power consumers 108 may additionally be designed and/or certified for all these operating modes. For example, a design might need to be additionally hardware/software (HW/SW) optimized for its working modes and tested. A design might also require additional safety approval certification to proven reliable and legal to use.

A major advantage conferred by the present disclosure thus relate to the fact that the power supply arrangement 100 in many cases are directly compatible with power consuming devices 108 without requiring modifications.

With reference to Figure 7, the present disclosure also relates to a method in a power supply arrangement 100 comprising an alternating current, AC, input port 101, a full-wave rectifying arrangement 102 connected to the AC input port 101, a charging/discharging handling device 103, a back-up battery cell arrangement 104 connected to the charging/discharging handling device 103, and an output port 105. The full-wave rectifying arrangement 102 is connected to the charging/discharging handling device 103 and to the output port 105.

In case Cl of normal operation, the method comprises inputting SI 00 an AC input current 1A via the AC input port 101 to the full-wave rectifying arrangement 102, outputting S200 a full-wave rectified output current iso to the output port 105, outputting S300 a full-wave rectified charging current iec to the charging/discharging handling device 103, and converting S400 the full-wave rectified charging current i BC to a normalized charging current IBN adapted for charging the backup battery cell arrangement 104.

In case C2 of back-up operation when there is no AC input current available at the AC input port 101, the method comprises outputting S500 a DC back-up output current ico to the output port 105 via the charging/discharging handling device 103. The present disclosure is not limited to the above, but may vary freely within the scope of the appended claims. For example, the battery cell arrangement 104 may comprise any number of battery cells, and any suitable battery technology may be applied. According to some aspects, the battery cell arrangement 104 is based on Li-Ion technology or on fuel cell technology. The term battery cell arrangement should therefore be interpreted in a broad term, according to some aspects as an arrangement that is adapted to store energy in a suitable form that can be converted to electric energy.

Claims

1. A power supply arrangement (100) comprising an alternating current, AC, input port (101), a lull-wave rectifying arrangement (102) connected to the AC input port (101), a charging/discharging handling device (103), a back-up battery cell arrangement (104) connected to the charging/discharging handling device (103), and an output port (105), where the full-wave rectifying arrangement (102) is connected to the charging/discharging handling device (103) and to the output port (105), where, during normal operation

- the full-wave rectifying arrangement (102) is adapted to input an AC input current (1A) via the AC input port (101), to output a full-wave rectified output current (iso) to the output port (105) and to output a full-wave rectified charging current (iec) to the charging/discharging handling device (103), and

- the charging/discharging handling device (103) is adapted to convert the full-wave rectified charging current (i BC) to a normalized charging current (IBN) adapted for charging the backup battery cell arrangement (104), and where, during back-up operation, when there is no AC input current available at the AC input port (101),

- the back-up battery cell arrangement (104) is adapted to output a direct current, DC, backup output current (ico) to the output port (105) via the charging/discharging handling device (103).

2. The power supply arrangement (100) according to claim 1, wherein the charging/discharging handling device (103) comprises a switch connection (111) that is adapted to by-pass the charging/discharging handling device (103) during back-up operation.

3. The power supply arrangement (100) according to any one of the claims 1 or 2, wherein the charging/discharging handling device (103) is adapted to synchronize the DC backup output current (ico) during back-up operation.

4. The power supply arrangement (100) according to claim 3, wherein the charging/discharging handling device (103) is adapted to detect if the full-wave rectified charging current (isc) is absent, and if that is the case, to synchronize the DC back-up output current (ico) accordingly.

5. The power supply arrangement (100) according to any one of the previous claims, wherein the power supply arrangement (100) further comprises an input filter (106).

6. The power supply arrangement (100) according to any one of the previous claims, wherein the power supply arrangement (100) further comprises a controller device (107) that is adapted to control the charging/discharging handling device (103).

7. An electric power system (200) comprising the power supply arrangement (100) according to any one of the claims 1-6 and at least one power consuming device (108) that is electrically connected to the output port (105) of the power supply arrangement (100), where each power consuming device (108) is adapted to input electrical power in the form of alternating current, AC, full-wave rectified current, and direct current, DC, via the output port (105).

8. A method in a power supply arrangement (100) comprising an alternating current, AC, input port (101), a full- wave rectifying arrangement (102) connected to the AC input port (101), a charging/discharging handling device (103), a back-up battery cell arrangement (104) connected to the charging/discharging handling device (103), and an output port (105), where the full-wave rectifying arrangement (102) is connected to the charging/discharging handling device (103) and to the output port (105), where, in case (Cl) of normal operation, the method comprises inputting (SI 00) an AC input current (1A) via the AC input port (101 to the full-wave rectifying arrangement (102); outputting (S200) a full-wave rectified output current (iso) to the output port (105); outputting (S300) a full-wave rectified charging current (iec) to the charging/discharging handling device (103); and converting (S400) the full-wave rectified charging current (iec) to a normalized charging current (IBN) adapted for charging the back-up battery cell arrangement (104); and where, in case (C2) of back-up operation when there is no AC input current available at the AC input port (101), the method comprises outputting (S500) a direct current, DC, back-up output current (ico) to the output port (105) via the charging/discharging handling device (103).