FR2936112A1 - Converter device for uninterrupted power supply, has step-up chopper circuits respectively connected to branches and providing output voltages, and inductive unit i.e. inductor, placed between network input and input point of branches - Google Patents

Abstract

The device (41) has branches (7, 10) connected to a network input (2) and deducting branch currents (IP, IN) during positive and negative half cycles of alternating input voltage (VE). The branches are equipped with thyristors (TH1, TH2) controlled by a control unit (13) of power semi-conductors. An inductive unit i.e. inductor (L), permits an impedance match, and step-up chopper circuits (55, 56) are respectively connected to the branches and provide output voltages (VSP, VSN). The unit is placed between the network input and an input point (8) of the branches. An independent claim is also included for uninterrupted power supply, comprising an input network to which an alternating input voltage is applied.

Description

The invention relates to the field of rectifier bridges, in particular those used in high-power uninterruptible power supplies, that is to say power whose power is generally in the form of rectifier bridges. between about 100 and 500 KVA. The invention more particularly relates to a converter device for uninterruptible power supply for converting an AC input voltage applied to a network input of said device into two substantially continuous output voltages, of opposite signs, and available on output lines of said device. , said converter device comprising a first and a second branch connected to said network input and making it possible to take a branch current during alternations respectively positive and negative of the input voltage, the first and the second branch being equipped with thyristors controlled by via control means for controlling said branch currents during transient phases, said converter device further comprising inductive means for impedance matching, and a first and a second elevator type chopper circuit respectively connected to l a first and second branch, and to provide the output voltages. STATE OF THE ART An AC / DC converter circuit according to the prior art is represented in FIG. 1. This converter device 1 comprises a network input 2 on which is applied an alternative, generally sinusoidal, input voltage VE and two referenced outputs. 4 and 5 to provide a positive output voltage VSP and ur.e negative output voltage VSN. These output voltages are generally substantially continuous and the two outputs 4, 5 are connected to capacitors C1, C2 allowing an accumulation of electrical energy. A first branch 7 of the converter circuit connected to the network input 2 makes it possible to draw an IP branch current during positive half-cycles of the input voltage VE.

In the same way, a second branch 10 connected to the network input 2 makes it possible to take a branch current IN during negative half-waves of the input voltage VE. Each of the two branches 7, 10 is equipped with a thyristor TH 1, TH2 controlled by control means 13 for controlling said branch current IP, IN.

Each of the branches 7, 10 is connected to an elevator type chopper circuit to provide the output voltages VSP, VSN. Each chopper circuit comprises a supply input 21, 22 connected to the first or the second branch 7, 10, diodes D1, D2 connected to said supply input 21, 22 and transistors T1, T2 connected to said input supply 21, 22.

In the converter device of FIG. 1, the power semiconductors, that is to say thyristors TH1, TH2, diodes D1, D2 and transistors T1, T2, are mounted in two separate boxes 31, 32 each. branches 7, 10 is equipped with an inductor LI, L2 for performing an impedance matching between the network input 2 and the output 4, 5 associated with said input. These inductances have values that are adapted with respect to the switching frequency of the control pulses applied to the transistors T1, T2. A disadvantage of the assembly of the prior art is that it does not allow optimized use of power components, particularly in terms of integration and energy consumption.

DISCLOSURE OF THE INVENTION The invention aims to overcome the drawbacks of the prior art converter devices by proposing a converter device for uninterruptible power supply for converting an AC input voltage applied to a network input of said device into two voltages. substantially continuous output, of opposite signs, and available on output lines of said device, said converter device comprising a first and a second branch connected to said network input and making it possible to take a branch current during alternations respectively positive and negative of the input voltage, the first and the second branch being equipped with thyristors controlled by means of control means for controlling said branch currents during transient phases, said converter device further comprising inductive means for impedance matching as well as a first and a second elevator type chopper circuit connected respectively to the first and second branches, and for supplying the output voltages, said converter device being characterized in that said inductive means are arranged between the network input and an entry point of said branches. Preferably, the inductive means are essentially constituted by an inductance. According to one embodiment, the control means comprise a starting module and control outputs connected to said module for supplying the thyristors, for a predetermined duration, control signals having time-varying initiation angles. . The delay angle at initiation can be variable linearly over time. According to another embodiment, the control means comprise a start module, a control input of a representative signal (a network input current connected to said module and control outputs connected to said module to supply the thyristors for a predetermined period of time, control signals having varying initiation delay angles according to a function of said network input current Preferably each chopper circuit includes a power input connected to the first or second branch, rectifying means connected to said supply input for supplying the output voltage on the output line associated with said circuit, and switching means connected to said supply input. in addition, a switching assistance circuit arranged between the supply input of said circuit and the output line associated with said circuit fired to establish, before a main boot of the switching means, a switching voltage across the switching means substantially equal to zero. Advantageously, the switching aid circuit of each chopper circuit further comprises second inductive means, branch current branching means for establishing a shunt of said current on said second inductive means before the main boot, and energy storage means connected in parallel with said switching means for establishing a resonance of said current in said second inductive means before the main priming. Preferably, the converter device is designed for unidirectional operation. The invention also relates to an uninterruptible power supply comprising a network input to which an AC input voltage is applied, a rectifier connected to said network input, energy storage means connected to said rectifier, an inverter connected to said means. energy storage device comprising a network output for supplying a safe alternating voltage, said power supply being characterized in that the rectifier is a converter device as described above comprising output lines to which said energy storage means are connected . BRIEF DESCRIPTION OF THE FIGURES Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of non-limiting examples, and represented in the appended figures. FIG. 1 represents a converter device according to the prior art. FIG. 2 represents a converter device according to the invention. FIG. 3 represents a converter device according to the invention provided with a switching assistance circuit. FIG. 4 represents an uninterrupted power supply according to the invention. DETAILED DESCRIPTION OF AN EMBODIMENT With reference to FIG. 2, the converter device 41 comprises components already described previously and for which the reference signs (FIG. 1) have been taken up.

In particular, the converter device 41 comprises a network input 2 on which a generally sinusoidal AC input voltage VE is applied, and output lines 4, 5 making it possible to supply two substantially continuous VSP, VSN output voltages and of opposite signs. . Capacitors C1, C2 are arranged between the output lines 4, 5 and a voltage reference. The converter device comprises a first and a second branch 7, 10 connected to the network input 2 and making it possible to take a branch current IP, IN during respectively positive and negative half-waves of the input voltage VE. On each of the branches is mounted a thyristor TH1, TH2 controlled by means of control means 13. The control means 13 make it possible to control the branch currents IP, IN flowing in the branches 7, 10, in particular during the phases transients, especially at start-up. More specifically, each thyristor TH1, TH2 comprises a control input or trigger connected to a control output 43, 44 of the control means 13. To simplify the representations of Figures 1 and 2, only one conductor for each trigger of said thyristors has been represent. The control of each thyristor TH1, TH2 is carried out by sending in the gate of said thyristor, via the control outputs 43, 44, a gate current having predetermined starting delay angles. The delay angle at initiation corresponds to a duration between the beginning of the ignition of the thyristor during the positive or negative alternation, depending on the branch on which the thyristor is arranged, and the end of this alternation. The delay angle at initiation is defined with respect to an origin corresponding to the end of the positive or negative half-wave, as a function of the branch on which the thyristor is arranged. This angle can have a value between 0 and 180 degrees, which allows a priming of the thyristor throughout the duration of the alternation. For example, when the firing delay angle applied to a thyristor is equal to 180 degrees, the thyristor is fired during the whole of the alternation, which corresponds to the operation of a diode. Thyristors TH1, TH2 make it possible, among other things, to control: .the branch current IP, IN during transient phases, in particular when powering up the converter device. For this, the control means 13 comprise a startup module 46 and control outputs 43, 44 connected to said module. The starter module 46 is designed to provide, for a predetermined duration, control signals having variable ignition timing angles according to a predetermined time function, i.e. having pulses whose instants and the duration are variable according to this predetermined function. The variation function of the ignition delay angle is generally adapted, depending on the filtering elements and the characteristics of the network, so that the branch current does not exceed a limit fixed by a specification. For example, the pitch delay angle may be linearly variable in time. This variation can also be non-linear or discrete. With the start module 46 of the control means 13, a preload of the capacitors C1, C2 can be obtained, which limits the inrush current to power up.

The control means 13 may optionally include a control input 48 of a signal representative of a network input current, said input being connected to the starter module 46. As shown in FIG. 2, the input of FIG. The control 48 is connected to a current sensor 50. In this case, the control signals of thyristors TH1, TH2 have variable start-delay angles according to a function of said network input current. This configuration allows a better regulation of the branch current IP, IN and a better optimization of a duration of starting. The variation of the ignition delay angle may occur throughout the transient phase. At the end of the transient phase, that is to say in steady state, the pulses of the thyristor control signals TH1, TH2 generally have a duration corresponding to a 180 degree initiation delay angle. In steady state, thyristors TH1, TH2 behave like diodes. When the converter device is implemented in a power supply without interruption, it is important to be able to transfer the load of a disturbed network to a battery, and this as quickly as possible to avoid any disturbance of the load. The use of thyristors TH1, TH2 makes it possible to disconnect the converter device when, for example, the input voltage on the network input 2 is disturbed or outside the generally accepted tolerances. For this, it suffices to stop the priming pulses thyristors TH1, TH2. Stopping the control pulses of thyristors TH1, TH2 and transistors T1, T2 generally guarantees a natural and rapid decay of the current in the inductance L and in thyristors TH1, TH2. This decay of the current is reflected in the diode D1, D2 of the chopper circuit, without any action. The zero crossing of the branch currents IP, IN causes the blocking of the thyristors. In general, this decay of the current essentially depends on the instantaneous value of the input voltage VE, the output voltage VS and the value of the inductance L. The use of thyristors allows a fast disconnection of the network. This disconnection is generally about 10 to 20 times faster compared to electromechanical devices using power contactors. The converter device further comprises a first and a second elevator-type chopper circuit 55, 56 respectively connected to the first and second branches 7, 10 and making it possible to supply the output voltages VSP, VSN. Each chopper circuit includes a power input 21, 22 connected to the first or second branch 7, 10, rectifier means connected to said power input 21, 22 to provide the output voltages VSP, VSN, and switching means connected to said supply input 21, 22. The rectifying means of each chopper circuit generally comprise a diode D1, D2. The switching means of each chopper circuit generally comprise a transistor T1, T2, most often of the IGBT type. The converter device comprises inductive means. In the embodiment shown in FIG. 2, these inductive means essentially consist of an inductance L arranged between the network input and the input point 8 of the branches 7, 10. This inductance makes it possible to adapt impedance between the 2 and the output lines 4, 5. The value of this inductance L is adapted to the switching frequency of the control pulses applied to the transistors T1, T2. In addition, because the peak current in each branch 7, 10 is the same as on the network input 2, the size of the inductor, which is proportional to the energy stored by said inductor L, is that is to say, proportional to the square of the intensity of the peak current passing through it, is therefore comparable to that of each of the inductances LI, L2 of the device of FIG. 1. Thus the converter device of FIG. 2 is more optimized from it has a single inductor instead of two inductances of the same size, and this inductance is used on all two alternations of the input voltage VE. Furthermore, in the converter device of FIG. 2, a single current sensor 51 is necessary, compared to the device of FIG. 1 which comprises two sensors 52, 53. The reduction in the number of sensors and the measurement interfaces associated with said sensors can reduce the size and cost of implementation. The use of a single inductor, with respect to the two inductances LI, L2 on the branches of the device of FIG. 1, makes it possible, among other things, to reduce wiring.

An advantage of the converter device shown in FIG. 2 is that the voltage rating of the thyristors TH1, TH2 is reduced compared with that of the thyristors of the converter device represented in FIG. 1. Indeed, in the embodiment of FIG. , the voltage across the thyristors is clamped by the diodes Dl, D2 chopper circuits.

Another advantage of the converter device shown in Figure 2 is that it allows integration of all power semiconductors in the same module or housing 61, and this without additional wiring. Indeed, in the device of FIG. 1, thyristors TH1, TH2 and chopper circuits 55, 56 are separated by inductances LI, L2, which implies the use of two separate boxes or a box with more than terminals to connect the two inductors. This integration makes it possible to minimize the wiring and to optimize the cooling means of the power semiconductors. It is also possible to group together in one and the same module all the control means 13 of the power semiconductors. This integration provides a less expensive solution, especially for power supplies without power interruption greater than 10 kVA. The converter device can be advantageously designed for unidirectional operation, preferably with a switching aid device to reduce losses. As shown in FIG. 3, each chopper circuit 55, 56 of the converter device may comprise a switching aid circuit 71, 72 arranged between the supply input 21, 22 of said chopper circuit and the output line. 4, 5 associated with said circuit. Thanks to this switching assistance circuit, it is possible to establish, before a main ignition of the transistor T1, T2, a switching voltage across said transistor substantially equal to zero.

Advantageously, the switching assistance circuit 71, 72 of each chopper circuit 55, 56 furthermore comprises second inductive means 73, 74, branch branch derivation means 75, 76 for establishing a current bypass. input to said second inductive means prior to main priming, and energy storage means 77, 78 connected in parallel to said switching means for resonating said current in said second inductive means prior to the main priming . The switching assistance circuits of the converter device may be identical to those described in the French patent application entitled converter device and uninterrupted power supply equipped with said device >> filed today by the applicant. The converter device described above can be used in an uninterruptible power supply 101 such as that shown in Figure 4. This uninterruptible power supply comprises a network input 102 to which is applied a variable input voltage of a first three-phase network. The uninterruptible power supply comprises a rectifier 103 of the type described above, said rectifier being connected between, on one side, the supply input 102 and, on the other side, two output lines 104 or bus of substantially continuous voltage. The uninterruptible power supply comprises an inverter 106 connected between the output lines 104 and a network output 107 for supplying a safe three-phase AC voltage to a load 108. The DC voltage bus 104 is also connected to a battery 109 by the Via a DC / DC converter 110. As can be seen in FIG. 4, static contactors 111 and 112 make it possible to select between the network input 102 of the first three-phase network and a network input 113 of a second three-phase network. . Thus, it is possible to feed the load via the first secure network by the uninterruptible power supply 101, and possibly switch to the second network.

Claims (10)

REVENDICATIONS1. Converter device (41) for uninterruptible power supply for converting an AC input voltage (VE) applied to a network input (2) of said device into two substantially continuous output voltages (VSP, VSN) of opposite sign, and available on output lines (4, 5) of said device, said converter device comprising a first and a second branch (7, 10) connected to said network input and making it possible to take a branch current (IP, IN) during alternations respectively positive and negative of the input voltage, the first and second branches being equipped with thyristors (TH1, TH2) controlled by means of control means (13) for controlling said branch currents (IP, IN) during transient phases, said converter device further comprising inductive means for impedance matching, and a first and a second chopper circuit (55, 56) of elevation type connected respectively to the first and second branches (7, 10), and for supplying the output voltages (VSP, VSN), characterized in that said inductive means are arranged between the network input (2) and a point of entry (8) of said branches. 2. Device according to claim 1, characterized in that the inductive means are essentially constituted by an inductance (L). 3. Device according to one of claims 1 or 2, characterized in that the control means (13) comprise a starting module (46) and control outputs (43, 44) connected to said module to provide the thyristors ( TH1, TH2), for a predetermined duration, control signals having time-varying ignition delay angles. 4. Device according to claim 3, characterized in that the ignition delay angle is variable linearly over time. 1030 5. Device according to one of claims 1 or 2, characterized in that the control means (13) comprise a starting module (4E)), a control input (48) of a signal representative of a current network input connected to said module and control outputs (43, 44) connected to said module for providing the thyristors (TH1, TH2), for a predetermined duration, control signals having variable starting delay angles according to a function of said network input current. 6. Device according to one of claims 1 to 5, characterized in that each chopper circuit (55, 56) comprises a supply input (21, 22) connected to the first or the second branch (7, 10). rectifying means connected to said supply input for providing the output voltage (VS) on the output line associated with said circuit, and switching means connected to said supply input. 7. Device according to claim 6, characterized in that each chopper circuit (55, 56) further comprises a switching aid circuit (71, 72) arranged between the supply input (21, 22). ) of said circuit and the output line (4, 5) associated with said circuit to establish, before a main ignition of the switching means, a switching voltage across the switching means substantially equal to zero. 8. Device according to claim 7, characterized in that the circuit for assisting the switching (71, 72) of each chopper circuit (55, 56) further comprises second inductive means (73, 74), branch current branching means (75, 76) for setting a bypass of said current on said second inductive means before the main priming, and energy storage means (77, 78) mounted in parallel to said switching means for establishing a resonance of said current in said second inductive means before the main priming. 9. Device according to one of claims 1 to 8, characterized in that it is designed for unidirectional operation. An uninterruptible power supply (101) comprising a network input (102) to which an AC input voltage (VE) is applied, a rectifier (103) connected to said network input, energy storage means (109). ) connected to said rectifier, an inverter (106) connected to said energy storage means having a network output (107) for providing a safe alternating voltage, characterized in that the rectifier (103) is a device according to one of the preceding claims having output lines (104) to which said energy storage means (109) are connected.