UNINTERRUPTED POWER SUPPLY CIRCUIT INCLUDING A STEP-DOWN / STEP-UP VOLTAGE CONVERTER

Abstract

The invention relates to an uninterruptible power supply circuit (100) configured to, in a first mode of operation, supply a second AC power network from a first AC power network (30); and, in a second mode of operation, supply the second AC power network from a DC voltage source (40).Said circuit includes a step-up / step-down voltage converter (110) comprising two input terminals (111, 112) configured to, in the first operating mode, receive between them an alternating voltage (V30) from the first network (30); and, in the second operating mode, receive a direct voltage (V40) from the direct voltage source (40); and two output terminals (121, 122) configured to, in the first and second operating modes, receive between them an alternating voltage (V50) from the second alternating electrical network; said step-up / step-down voltage converter (110) being configured to, in the first operating mode, perform an AC / AC conversion between the first alternating electrical network (30) and the second alternating electrical network.

Description

Title of the invention: UNINTERRUPTED POWER SUPPLY CIRCUIT COMPRISING A STEP-DOWN / STEP-UP VOLTAGE CONVERTER

[0001] The invention relates to an uninterruptible power supply circuit, in particular an uninterruptible power supply circuit configured to supply a second AC power network from a first AC power network, and in the event of failure of the first AC power network, to supply the second AC power network from a DC voltage source.

[0002] Uninterruptible power supplies (UPS) are electrical devices designed to ensure continuity of service in the event of a power outage affecting an electrical system connected to the power grid. By interfacing between the power grid and the system, the uninterruptible power supply can also improve the quality of the power provided by the grid. Systems using UPSs include banks, hospitals, universities, and data centers.

[0003] Typically, a UPS is configured to perform two electrical conversions. In normal operation, the UPS implements an AC-to-AC conversion in which energy drawn from the AC power grid is delivered to the AC power system. In the event of an AC power grid failure, a DC-to-AC conversion is implemented between a DC power source, such as a battery, and the AC power system in order to maintain power to the AC power system.

[0004] There are ranges of uninterruptible power supplies (UPS) that correspond to specific types of AC / AC conversion. For domestic or non-critical applications, voltage- and frequency-dependent (VFD) UPSs are available. These VFDs are characterized by a voltage and frequency delivered to the electrical system that depend on the voltage and frequency supplied by the power grid. These power supplies are generally reserved for applications up to 1500 VA. Voltage-independent (VI) UPSs are also available. These power supplies are characterized by a voltage delivered to the power grid that can be controlled independently of the voltage supplied by the power grid. The VI power supply can control the voltage delivered to the electrical system. The frequency, however, is generally not adjustable. This type of power supply is generally reserved for applications up to 5000 VA, such as for small business computer servers, for example. There are also voltage and frequency independent (VFI) uninterruptible power supplies, in which the voltage and frequency delivered to the electrical system are controllable by the UPS. Such VFI UPSs are generally reserved for applications exceeding 5000 VA.

[0005] An ASI is known, as described in the patent application publication WO2013 / 130054 A1. This UPS operates with independent voltage, based on delta conversion. Such delta conversion uses a transformer with one winding connected in series between the power grid and the system. The voltage across this winding is controlled by an inverter. The transformer winding corrects fluctuations in the power grid. However, DC storage is required for harmonic compensation. Such DC storage is bulky. The UPS's footprint is further impacted by the size and weight of the transformer. Another drawback of this prior art UPS is that transformer control requires monitoring its magnetic flux, which can be complex to implement.Furthermore, while delta conversion previously allowed the use of a converter not designed for nominal AC / AC operation, switching technologies have significantly improved in terms of losses with the emergence of SiC or GaN technologies, making delta conversion less advantageous. Finally, the UPS described in this document has a modular structure that allows it to operate in either voltage independent (VI) or voltage independent (VFI) mode. However, some users may only require the independent voltage functionality, namely a UPS that delivers a voltage independent of the mains supply but maintains the mains frequency.

[0006] Therefore, an independent voltage UPS is sought which has a reduced footprint compared to the prior art.

[0007] To this end, the invention proposes an uninterruptible power supply circuit configured to, in a first operating mode, supply a second AC power network from a first AC power network; and, in a second operating mode, supply the second AC power network from a DC voltage source, said circuit comprising a step-down / step-up voltage converter including: - two input terminals configured to, in the first operating mode, receive between them an alternating voltage from the first network; and, in the second operating mode, receive a DC voltage from the DC voltage source; and - two output terminals configured to, in the first and second operating modes, receive between them an alternating voltage from the second alternating electrical network; said buck-boost voltage converter being configured to, in the first mode of operation, perform an AC / AC conversion between the first alternating electrical network and the second alternating electrical network.

[0008] Thus, the circuit according to the invention uses a buck-boost voltage converter in the AC / AC conversion between the first electrical network and the second electrical network, which avoids the use of a transformer and reduces the size of the uninterruptible power supply circuit.

[0009] According to one embodiment, the step-down / step-up voltage converter comprises: • a first arm of switches and a second arm of switches, each arm comprising two switches having a common terminal, called the midpoint; • an inductance connected between the midpoints of the first and second switch arms; the extreme terminals of the first arm forming said input terminals of the buck-boost converter, the extreme terminals of the second arm forming said output terminals of the buck-boost converter, an input terminal being configured to be connected to an output terminal during uninterruptible power supply circuit operation.

[0010] According to one embodiment, said step-up voltage converter is configured to, in the second operating mode, perform a DC / AC conversion between the DC voltage source and the second AC power network.

[0011] According to one embodiment, the uninterruptible power supply circuit includes switches, called toggle switches, configured to selectively connect one of the input terminals with a first of the output terminals.

[0012] According to one embodiment, a first switching switch is connected between a first input terminal of the buck-boost voltage converter and the first output terminal of the buck-boost voltage converter; and a second switching switch is connected between a second input terminal of the buck-boost voltage converter and the first output terminal of the buck-boost voltage converter.

[0013] According to one variant, the uninterruptible power supply circuit is configured so that, in the first operating mode, the first switch is closed and the second switch is open.

[0014] According to one variant, the uninterruptible power supply circuit is configured so that, in the first operating mode, a terminal of the first AC electrical network connected to the first input terminal forms a ground of the first AC electrical network; and a terminal of the second AC electrical network connected to the first output terminal forms a ground of the second AC electrical network.

[0015] According to one variant, the uninterruptible power supply circuit is configured such that, in the second operating mode: • on the positive alternation of the alternating voltage of the second electrical network, the first switching switch is closed and the second switching switch is open; and, • on the negative alternation of the alternating voltage of the second electrical network, the first switching switch is open and the second switching switch is closed.

[0016] According to one variant, the uninterruptible power supply circuit is configured to, in a third operating mode, supply the first AC electrical network from the DC voltage source, and such that, in said third operating mode: • on the positive alternation of the alternating voltage of the first electrical network, the first switching switch is closed and the second switching switch is open; and, • on the negative alternation of the alternating voltage of the first electrical network, the first switching switch is open and the second switching switch is closed.

[0017] According to one embodiment, the step-up voltage converter is reversible.

[0018] Other features and advantages of the present invention will become more apparent from the following description in relation to the following attached figures: [Fig.1]: [Fig.1] represents an uninterruptible power supply circuit according to an example of the invention; [Fig.2]: [Fig.2] illustrates a first mode of operation of the circuit represented in [Fig.1]; [Fig.3]: [Fig.3] illustrates part of a second operating mode of the circuit illustrated in [Fig.1]; [Fig.4]: [Fig.4] illustrates another part of the second mode of operation; [Fig.5]: [Fig.5] represents a current flow in the circuit of [Fig.1]; [Fig.6]: [Fig.6] represents current flow in the circuit of [Fig.1]; [Fig.7]: [Fig.7] illustrates a third operating mode of the uninterruptible power supply circuit.

[0019] Figure 1 shows an uninterruptible power supply circuit 100 according to an embodiment of the invention. The power supply circuit 100 can have at least two operating modes to ensure an uninterruptible power supply to a second AC power grid to which it is connected. The second AC power grid belongs, in particular, to an installation for which any interruption in the power supply must be avoided. Such an installation is, for example, a bank, a hospital, a university, or a data center.

[0020] In a first mode of operation, the supply circuit 100 provides a power supply to the second AC power network from a first AC power network 30. The first AC power network 30 is in particular a public power network.

[0021] In a second operating mode, the power supply circuit 100 provides power to the second AC power grid from a DC voltage source 40. Thus, in the event of a failure of the first AC power grid 30, the DC voltage source 40 ensures continuity of power to the second power grid. In particular, this is a temporary power supply, until a robust power source, such as a generator, is brought online. The DC voltage source 40 can be, among other things, a battery, such as a lithium-lead battery, or a supercapacitor. The battery can be housed in a rack within the uninterruptible power supply circuit 100.

[0022] The uninterruptible power supply circuit 100 includes a buck-boost voltage converter 110. Two input terminals 111, 112 of the buck-boost voltage converter 110 are configured, in the first operating mode, to receive an alternating voltage V30 from the first alternating power supply 30. The first alternating power supply 30 is then connected between the two input terminals 111, 112, in particular directly connected between the two input terminals 111, 112. In the second operating mode, the two input terminals 111, 112 of the buck-boost voltage converter 110 receive a direct voltage V40 from the direct voltage source 40. The direct voltage source 40 is then connected between the two input terminals 111, 112, in particular directly connected between the two input terminals 111, 112.The step-down / step-up voltage converter 110 further includes two output terminals 121, 122 which, in the first and second operating modes, receive between them a voltage V50 from the second AC power grid. The . A second alternative electrical network is then connected, in particular directly connected, between the two output terminals 121, 122.

[0023] In the first operating mode, the buck-boost converter 110 performs an AC / AC (alternating / alternating) conversion between the first 30 and the second power grid. Buck-boost voltage converters are well known in the prior art for DC / DC (direct-direct) conversion, but not for AC / AC conversion, particularly in an uninterruptible power supply (UPS). The buck-boost voltage converter 110 makes it possible to implement an uninterruptible power supply in a simple manner. Furthermore, due to its configuration, it can be reused in the DC / AC conversion of the second operating mode.

[0024] In particular, in the first operating mode, the step-down / step-up voltage converter 110 allows the power supply circuit 100 to be voltage-independent, but not frequency-independent. In other words, thanks to the step-down / step-up voltage converter 110, the power supply circuit 100 regulates, in particular, the effective voltage delivered to the second electrical network, so that it can be different from that delivered by the first electrical network 30. Specifically, the step-down / step-up converter 110 converts an alternating voltage V30 from the first alternating electrical network 30 into a second alternating voltage V50, which forms the output voltage delivered to the second alternating electrical network; the frequency delivered by the power supply circuit 100 remains equal to that of the second electrical network 30.

[0025] In particular, the buck-boost voltage converter 100 includes a first switch arm B1 comprising a first switch SI and a second switch Sic. In particular, each switch SI, Sic has two contact terminals. The two switches SI, Sic have a common terminal which constitutes the midpoint of the first arm Bl. The outermost terminals of the first arm B1 form the input terminals 111, 112 of the buck-boost voltage converter 110. In other words, in particular, for each switch SI, Sic, the terminal opposite the midpoint forms an input terminal 111, 112 of the buck-boost voltage converter 110. The buck-boost voltage converter 110 includes, in particular, a second switch arm B2. Similar to the first arm Bl, the second arm B2 comprises a first switch S2 and a second switch S2c.The extreme terminals of the second arm B2 form the output terminals 121, 122 of the buck-boost voltage converter 110. In other words, in particular, for each switch S2, S2c of the second arm B2, the terminal opposite the midpoint of the second arm forms an output terminal 121, 122 of the buck-boost voltage converter 110.

[0026] In particular, the buck-boost voltage converter 110 further comprises an inductor L. The inductor L is connected between the midpoint of the first arm B1 and the midpoint of the second arm B2. In other words, the inductor L has, in particular, two contact terminals: one is connected, in particular directly connected, to the midpoint of the first arm B1; the other is connected, in particular directly connected, to the midpoint of the second arm B2.

[0027] Thanks to the switches SI, Sic, S2, S2c, the buck-boost voltage converter 110 performs a conversion by storing energy in the inductor L, which allows the voltage between the input and output to be raised or lowered. Thus, the uninterruptible power supply circuit 100 makes it possible, in the first operating mode, to supply power between a first and a second AC power network having, for example, one of the following voltage pairs: 115Vac / 230Vac, 230Vac / 115Vac, 115Vac / 115Vac, or 230Vac / 230Vac. For this purpose, an input terminal 111 of the buck-boost voltage converter 110 is connected to an output terminal 121 of the buck-boost voltage converter 110, as will be explained later in relation to [Fig. 2].

[0028] In particular, in the second operating mode, the buck-boost voltage converter 110 performs the DC / AC conversion between the DC voltage source 40 and the second AC power supply. Specifically, an input terminal 111 of the buck-boost converter 110 is then connected to an output terminal 121 of the buck-boost converter 110. Such a DC / AC conversion by the buck-boost voltage converter 110 is made possible, in particular, by switches T1, T2, known as switching switches. These switching switches T1, T2 allow one of the input terminals 111, 112 to be selectively connected to a first output terminal 121. In doing so, the switches T1, T2 determine the polarity of the power source that is connected to the first output terminal 121.In particular, in the second operating mode, switches T1 and T2 allow the polarity of the DC voltage source 40 to be successively reversed so as to deliver a positive or negative AC voltage at the output of the uninterruptible power supply (UPS) circuit 100. Thus, the buck-boost voltage converter 110 can be used in both the first and second operating modes. This sharing of electrical components between the AC / AC conversion circuit and the DC / AC conversion circuit reduces costs and increases the power density of the UPS 100 compared to prior art. Furthermore, in the second operating mode, the buck-boost voltage converter 110 allows, in particular, control of the frequency of the AC voltage delivered at the output. Thus, the frequency of the output AC voltage can be variable.

[0029] In particular, a first toggle switch T1 is connected between a first input terminal 111 of the buck-boost voltage converter 110 and the first output terminal 121 of the buck-boost voltage converter 110; and a second toggle switch T2 is connected between a second input terminal 112 of the buck-boost converter 110 and the first output terminal 121 of the buck-boost voltage converter 110. With this configuration, the switches T1 and T2 allow for a simple change, in the second operating mode, of the polarity of the voltage source 40 at the input terminals 111 and 112 of the buck-boost voltage converter 110 for implementing DC / AC conversion. Preferably, the switches T1 and T2 are in complementary states. That is, they are not open or closed at the same time.

[0030] In particular, the first output terminal 121 is connected, in particular directly connected, to a negative terminal of the second alternative electrical network; and the second output terminal 122 is connected, in particular directly connected, to a positive terminal of the second alternative electrical network.

[0031] The uninterruptible power supply circuit 100 may further include a first capacitor 132 at the interface between the uninterruptible power supply circuit 100 and the first AC power network 30 or the DC voltage source 40; and a second capacitor 134 between the uninterruptible power supply circuit 100 and the second AC power network. Thus, the first capacitor 132 can be connected between the input terminals 111, 112. The second capacitor 134 can be connected between the output terminals 121, 122.

[0032] The first operating mode of the power supply circuit 100 will now be described in more detail with reference to [Fig. 2]. [Fig. 2] shows in its upper part a waveform of the voltage VL across the inductor L and a waveform of the current IL across the inductor L. The electrical diagrams in the lower part each represent the state of the uninterruptible power supply circuit 100 and the current flowing through it in a section I, II, III, IV of a switching period T of the switches SI, Sic, S2, S2c of the buck-boost voltage converter 110.

[0033] In particular, in the first operating mode, the first switch T1 is closed and the second switch T2 is open. Specifically, the first input terminal 111 is then connected to a negative terminal of the first AC electrical network 30; and the second input terminal 112 is then connected to a positive terminal of the first AC electrical network 30.

[0034] In particular, the negative terminal of the first AC electrical network 30 connected to the first input terminal 111 forms a ground of the first AC electrical network 30; and the negative terminal of the second AC electrical network connected The first output terminal 121 forms a ground for the second AC power grid. Thus, a connection between the grounds of the first power grid 30 and the second power grid is easily obtained. Such a connection (also known as "Neutral Passing Through") can be advantageous in uninterruptible power supplies (UPS). In particular, such a connection is required by certain standards for uninterruptible power supplies.

[0035] Specifically, the switches SI, Sic, S2, S2c are switched with a switching frequency corresponding to the switching period T. The ratio between the input voltage V30 and the output voltage V50 is, in particular, a function of the duty cycle α of the opening of the switches SI, Sic, S2, S2c of the buck-boost voltage converter 110.

[0036] An example of switching the switches will be described below. In the first part I, lasting aT of the switching period T, the first switch SI of the first arm B1 is open and the second switch Sic of the arm is closed; and the first switch S2 of the second arm B2 is open and the second switch S2c of the arm is closed. The voltage VL across the inductor L is then equal to that V30 of the first electrical network 30. The current IL flowing through the inductor gradually increases. The energy from the first electrical network 30 is then stored in the inductor L.

[0037] In an optional second part II lasting (|3 / 2)T of the switching period T, the first switch S1 of the first arm B1 is closed and the second switch Sic of the arm is open; and the first switch S2 of the second arm B2 is open and the second switch S2c of the arm is closed. This part II is a freewheeling stage that allows for the dissipation of any residual charges and prevents breakage of the switches during the changeover between the first phase I and a third part III.

[0038] In the third part III, lasting (la-[3]T of the switching period T, the first switch SI of the first arm B1 is closed and the second switch Sic of the arm is open; and the first switch S2 of the second arm B2 is closed and the second switch S2c of the arm is open. The energy accumulated in the inductor L during the first part I is discharged to the second AC power grid. The voltage VL across the inductor L is then equal to that V50 of the second power grid. The current IL flowing through the inductor gradually decreases.

[0039] In an optional fourth part IV of a duration (|3 / 2)T of the switching period T, the first switch S1 of the first arm B1 is closed and the second switch Sic of the arm is open; and the first switch S2 of the second arm B2 is open and the second switch S2c of the arm is closed. This part II is a freewheeling step to mitigate irregularities in the transition to the third part III to a first part I of the following switching period T. The voltage VL across the inductor L is then zero. The current IL flowing through the inductor remains essentially stable.

[0040] In [Fig. 2], the arrows in the electrical circuits indicate the direction of the current. The directions indicated correspond to a positive half-cycle of the first alternating current network. During the negative half-cycle, the currents are in the opposite direction.

[0041] The second mode of operation of the power supply circuit 100 will now be described in more detail with reference to Figures 3 and 4. In particular, in the second mode of operation, the first input terminal 111 is connected, in particular directly connected, to a negative terminal of the DC voltage source 40; and the second input terminal 112 is connected, in particular directly connected, to a positive terminal of the DC voltage source 40.

[0042] As in the first operating mode, the DC / AC conversion in the second operating mode relies in particular on the accumulation of energy in the inductor L, which allows the voltage between the input and output to be raised or lowered, and thus generates an alternating output voltage. Thanks to the switching switches T1, T2, the buck-boost voltage converter 110 can deliver an alternating output signal with a positive half-cycle and a negative half-cycle.Indeed, switches T1, T2 allow the DC voltage source 40 to be connected to the buck-boost converter 110 with a first polarity during a positive half-cycle of the AC voltage V50 from the second electrical network; and switches T1, T2 allow the DC voltage source 40 to be connected to the buck-boost converter 110 with a second polarity, the opposite of the first, during a negative half-cycle of the AC voltage V50 from the second electrical network.

[0043] In particular, as illustrated for example in [Fig. 3], on the negative half-cycle of the AC voltage V50 from the second power grid, the first switch T1 is open and the second switch T2 is closed. Thus, the second input terminal 112 is connected to the first output terminal 121. In particular, the positive terminal of the voltage source 40 is connected to the negative terminal of the second AC power grid. The switches S1, S1, S2, S2c of the buck-boost voltage converter 110 are then controlled according to a switching frequency, notably in a manner similar to the first operating mode, to deliver the negative half-cycle of the voltage V50 from the second AC power grid.

[0044] More particularly in the negative alternation, as illustrated for example in [Fig. 5], in a first part of a duration aT of the switching period T, the first switch SI of the first arm B1 is closed and the second switch Sic The first arm is open; and the first switch S2 of the second arm B2 is open and the second switch S2c of the arm is closed. The energy from the DC voltage source 40 then accumulates in the inductor L. In particular, as illustrated for example in [Fig. 6], in a successive portion of a duration (la)T of the switching period T, the first switch S1 of the first arm B1 is open and the second switch S1 of the arm is closed; and the first switch S2 of the second arm B2 is closed and the second switch S2c of the arm is open. The energy accumulated in the inductor L during the first phase illustrated in [Fig. 5] is discharged into the second electrical network. An optional freewheeling portion, in which the second switch S1 of the first arm B1 and the second switch S2c of the second arm B2 are closed, can be inserted between the portions illustrated in Figures 5 and 6.

[0045] In particular, as illustrated for example in [Fig. 4], on the positive half-cycle of the alternating voltage V50 of the second electrical network, the first switch T1 is closed and the second switch T2 is open. Thus, the first input terminal 111 is connected to the first output terminal 121. In particular, the negative terminal of the voltage source 40 is connected to the negative terminal of the second alternating electrical network. The switches S1, S1, S2, S2c of the buck-boost voltage converter 110 are then controlled according to a switching frequency, notably in a manner similar to the first operating mode, to deliver the positive half-cycle of the voltage V50 of the second alternating electrical network.

[0046] Referring again to [Fig. 1], the uninterruptible power supply circuit 100 switches in particular from the first to the second operating mode and vice versa by means of a set of switches RI, R2, R3.

[0047] In particular, two switches RI, R2 allow the first AC power supply 30 to be connected to the uninterruptible power supply 100 in the first configuration. In the second configuration, the switches RI, R2 disconnect the first power supply 30. For this purpose, a first switch RI is preferably connected between the first input terminal 111 of the buck-boost voltage converter 110 and a first terminal of the first power supply 30. A second switch R2 is preferably connected between the second input terminal 112 of the buck-boost voltage converter 110 and a second terminal of the first power supply 30. These two switches RI, R2 are specifically configured to open or close simultaneously.

[0048] In particular, the switch set further includes a third switch R3 which, in the first configuration, disconnects the DC voltage source 40 from the buck-boost voltage converter 110; and in the second configuration, connects the DC voltage source 40 to the buck-boost voltage converter In particular, the first terminal of the voltage source 40 is connected to the first input terminal 111; and the third switch R3 is connected between the second terminal of the DC voltage source 40 and the second input terminal 112. The set of switches R1, R2, R3 could have a different configuration. For example, one switch could be connected between the first terminal of the voltage source 40 and the first input terminal 111. The switches R1, R2, R3 are, in particular, relays, controlled specifically by a control unit of the uninterruptible power supply circuit 100.

[0049] Because they switch at the switching frequency, the switches SI, Sic, S2, S2c of the buck-boost voltage converter 110 are preferably made using a technology that supports high frequencies, such as GaN or SiC. The switching frequency is, for example, between 50 kHz and 100 kHz. It can be lower or higher depending on the switch technology and the value of the inductance L.

[0050] In particular, the switching switches T1, T2 operate at relatively lower frequencies. Specifically, in the second operating mode, the switching switches T1, T2 operate at a frequency between 50 and 60 Hz. The switching frequency of the switching switches can be lower or higher, for example, on the order of a few kilohertz, depending on the frequency of the alternating voltage delivered at the output of the buck-boost voltage converter 110. In particular, the switching switches T1, T2 are made of silicon technology, specifically of the MOSFET type.

[0051] Preferably, the buck-boost voltage converter 110 is reversible. It can then transmit power from the input terminals 111, 112 to the output terminals 121, 122, or from the output terminals 121, 122 to the input terminals 111, 112. For this purpose, the switches SI, Sic, S2, S2c of arms Bl, B2 are, in particular, bidirectional in both current and voltage. The switches SI, Sic, S2, S2c are then, for example, of GaN technology, in particular HEMT GaN. The bidirectionality of a switch SI, Sic, S2, S2c of the buck-boost voltage converter 110 can be achieved by combining transistors, in particular SiC MOSFET transistors. The second switching switch T2, in particular the two switching switches T1, T2, can be bidirectional. The transistor Tl can be a MOSFET transistor.

[0052] The uninterruptible power supply circuit 100 may have a third operating mode, for example illustrated in [Fig. 7]. In this third operating mode, the DC voltage source 40 supplies the first AC power network 30. For this purpose, the uninterruptible power supply circuit 100 may include additional switches, in particular relays, to Connect the terminals of the DC voltage source 40 to the output terminals 121 and 122 of the buck-boost voltage converter 110. Specifically, thanks to its power reversibility, the buck-boost voltage converter 110 can send power from the DC voltage source 40 to the first AC power grid 30. The buck-boost voltage converter 110 then operates similarly to that in the second operating mode. On the positive half-cycle of the AC voltage V30 from the first power grid 30, the first switch T1 is closed and the second switch T2 is open. On the negative half-cycle of the AC voltage V30 from the first power grid 30, the first switch T1 is open and the second switch T2 is closed.

Claims

Demands

1. Uninterruptible power supply circuit (100) configured to, in a first operating mode, supply a second AC power network from a first AC power network (30); and, in a second operating mode, supply the second AC power network from a DC voltage source (40), said circuit comprising a buck-boost voltage converter (110) including: - two input terminals (111, 112) configured to, in the first operating mode, receive between them an AC voltage (V30) from the first network (30); and, in the second operating mode, receive a DC voltage (V40) from the DC voltage source (40); and - two output terminals (121, 122) configured to, in both the first and second operating modes, receive between them an AC voltage (V50) from the second AC power network;said buck-boost voltage converter (110) being configured to, in the first mode of operation, perform an AC / AC conversion between the first alternating electrical network (30) and the second alternating electrical network, the circuit comprising switches (T1, T2), called toggle switches, configured to selectively connect one of the input terminals (111, 112) with a first (121) of the output terminals, in which a first toggle switch (T1) is connected between a first input terminal (111) of the buck-boost voltage converter (110) and the first output terminal (121) of the buck-boost voltage converter (110); and a second toggle switch (T2) is connected between a second input terminal (112) of the buck-boost voltage converter (110) and the first output terminal (121) of the buck-boost voltage converter (110).

2. Uninterruptible power supply circuit (100) according to claim 1, wherein the buck-boost voltage converter (110) comprises: - a first arm of switches (B1) and a second arm of switches (B2), each arm comprising two switches having a common terminal, called the midpoint; - an inductance (L) connected between the midpoints of the first and second arms of switches (B1, B2); the extreme terminals of the first arm (B1) forming the said input terminals (111, 112) of the buck-boost converter (110), the extreme terminals of the second arm (B2) forming the said output terminals (121, 122) of the buck-boost converter (110), an input terminal (111, 112) being configured to be connected to an output terminal (121) during operation of the uninterruptible power supply circuit (100).

3. Uninterruptible power supply circuit (100) according to any one of the preceding claims, wherein said buck-boost voltage converter (110) is configured to, in the second operating mode, perform DC / AC conversion between the DC voltage source (40) and the second AC power network.

4. Uninterruptible power supply circuit (100) according to claim 3, configured such that, in the first operating mode, the first switch (T1) is closed and the second switch (T2) is open.

5. Uninterruptible power supply circuit (100) according to claim 4, configured such that, in the first mode of operation, a terminal of the first AC power network (30) connected to the first input terminal (111) forms a ground of the first AC power network (30); and a terminal of the second AC power network connected to the first output terminal (121) forms a ground of the second AC power network.

6. Uninterruptible power supply circuit (100) according to any one of claims 3 to 5, configured such that, in the second operating mode: - on the positive half-cycle of the alternating voltage (V50) of the second electrical network, the first switching switch (T1) is closed and the second switching switch (T2) is open; and, - on the negative half-cycle of the alternating voltage (V50) of the second electrical network, the first basic switch

7.

8. element (T1) is open and the second basic element switch (T2) is closed. Uninterruptible power supply circuit (100) according to any one of claims 3 to 6, configured to, in a third operating mode, supply the first AC power network (30) from the DC voltage source (40), and such that, in said third operating mode: - on the positive alternation of the alternating voltage (V30) of the first electrical network (30), the first switching switch (T1) is closed and the second basic switching switch (T2) is open; and, - on the negative alternation of the alternating voltage (V30) of the first electrical network (30), the first switching switch (T1) is open and the second switching switch (T2) is closed. Uninterruptible power supply circuit (100) according to any one of the preceding claims, wherein the buck-boost voltage converter (110) is reversible.