FR3056038A1 - VOLTAGE CONVERTER WITH TWO CIRCUITS VOLTAGE CONVERTER CHAINS - Google Patents

Abstract

The voltage converter (100) includes a first isolated voltage converter circuit (102) and a second voltage converter circuit (110) providing an intermediate voltage (VINT) to the first voltage converter circuit (102). The second voltage converter circuit (110) comprises a first inductor (LB1), a second inductor (LB2) and a capacitor (CB1), and is designed, in a first state, for the input terminals (EB1, EB2 ) supply energy to the first inductor (LB1), and for the input terminals (EB1, EB2) and capacitance (CB1) to supply energy to the second inductor (LB2) and to the output terminals (SB1, SB2), and, in a second state, for disconnecting one of the input terminals (EB1, EB2) so that they no longer supply energy, for the first inductance (LB1) to supply energy to the capacitance (CB1), and for the second inductor (LB2) to supply power to the output terminals (SB1, SB2).

Description

TITLE

VOLTAGE CONVERTER WITH TWO CIRCUITS CHAINED VOLTAGE CONVERTER

TECHNICAL AREA

The present invention relates to the field of DC-DC voltage converters.

TECHNOLOGICAL BACKGROUND

The French patent application published under the number FR 3 023 083 A1 describes, in its FIG. 4, a voltage converter comprising:

- a first isolated voltage converter circuit comprising:

- first and second input terminals between which a DC intermediate voltage is intended to be received,

- first and second output terminals between which a continuous output voltage is intended to be supplied,

- a second voltage converter circuit comprising:

- first and second input terminals between which a DC input voltage is intended to be received, the first terminal being intended to be connected to an electrical ground,

- first and second output terminals between which the intermediate voltage is intended to be supplied, the first output terminal being connected to the first input terminal,

- a control system for the second voltage converter circuit designed to:

- receive a reference output voltage,

- measure the output voltage,

- switching the second voltage converter circuit between first and second states according to a cyclic ratio c2, the control system of the second voltage converter circuit being furthermore designed to modify the cyclic ratio ot2 so that the output voltage follows the reference output voltage.

The invention aims to provide an AC voltage converter.

SUMMARY OF THE INVENTION

To this end, a voltage converter is proposed comprising:

- a first isolated voltage converter circuit comprising:

- first and second input terminals between which a DC intermediate voltage is intended to be received,

- first and second output terminals between which a continuous output voltage is intended to be supplied,

- a second voltage converter circuit comprising:

- first and second input terminals between which a continuous input voltage is intended to be received, the first terminal being intended to be connected to an electrical ground,

- first and second output terminals between which the intermediate voltage is intended to be supplied, the first output terminal being connected to the first input terminal,

- a control system for the second voltage converter circuit designed to:

- receive a reference output voltage,

- switching the second voltage converter circuit between first and second states according to a duty cycle a.2 as a function of said reference output voltage (Vs_ref), the voltage converter being characterized in that the second voltage converter circuit comprises a first inductor, a second inductor and a capacitor, and is designed:

in the first state:

- so that the input terminals supply energy to the first inductor,

- so that the input terminals and the capacity supply energy to the second inductor and to the output terminals, in the second state:

- to disconnect one of the input terminals so that they no longer supply energy,

- so that the first inductor supplies energy to the capacitor,

- so that the second inductor supplies energy to the output terminals.

Optionally, the second voltage converter circuit further comprises a first switch, the first switch and the first inductor being connected one after the other, between the input terminals; the capacitance and the second inductor are arranged one after the other, between, on the one hand, a midpoint of the first switch and of the first inductor and, on the other hand, the second output terminal; the second voltage converter circuit further comprises a second switch connected between, on the one hand, a midpoint of the capacitance and of the second inductance and, on the other hand, the first input terminal.

Also optionally, the voltage converter further comprises a control system for the first voltage converter circuit designed to switch the first voltage converter circuit between two states, at a first switching frequency, and the control system for the second. voltage converter circuit switches the second voltage converter circuit to a second switching frequency.

Optionally also, the first and second switching frequencies are different from each other.

Also optionally, the second switching frequency is higher than the first switching frequency.

Also optionally, the control system of the first voltage converter circuit switches the first voltage converter circuit according to a constant duty cycle ai.

Also optionally, the duty cycle ai is 0.5.

Also optionally, the second voltage converter circuit has a conversion ratio of the intermediate voltage with respect to the input voltage depending on the duty cycle a2 and which can be greater than, equal to or less than 1 depending on the duty cycle ai of the second voltage converter circuit.

Also optionally, the first voltage converter circuit comprises:

a first switch, a first capacity and a second switch arranged one after the other, the first capacity being disposed between the two switches,

a first transformer comprising a first primary winding, a second primary winding, a secondary winding and a first magnetic core coupling these three windings, the primary windings being arranged in series between, on the one hand, a midpoint of the first switch and of the first capacity and, on the other hand, the first input terminal,

a second transformer comprising a first primary winding, a second primary winding, a secondary winding and a second magnetic core coupling these three windings, the primary windings being connected in series between, on the one hand, a midpoint of the second switch and of the first capacity and, on the other hand, the second input terminal.

Also optionally, each of the two secondary windings is connected, on one side, to one of the two output terminals and, on the other hand, to the other of the two output terminals through a switch respective.

Also optionally, the first voltage converter circuit comprises two branches each comprising a first switch, a respective one of the two secondary windings and a second switch, and the two secondary windings respectively have two intermediate points connected one to the other.

DESCRIPTION OF THE FIGURES

Figure 1 is an electrical diagram of a voltage converter according to a first embodiment of the invention.

Figures 2 and 3 are electrical diagrams of a first voltage converter circuit of the voltage converter of Figure 1, in first and second states, respectively.

Figures 4 and 5 are electrical diagrams of a second voltage converter circuit of the voltage converter of Figure 1, in first and second states, respectively.

Figure 6 is an electrical circuit of a voltage converter according to a second embodiment of the invention.

DETAILED DESCRIPTION

With reference to FIG. 1, a voltage converter 100 according to a first embodiment of the invention will now be described.

The voltage converter 100 is a DC / DC converter intended to receive a continuous input voltage Ve and designed to supply a continuous output voltage Vs from the input voltage Ve, according to an overall conversion factor A:

The voltage converter 100 includes a first voltage converter circuit 102, which is an isolated DC / DC converter designed to receive an intermediate voltage Vint and to supply the output voltage Vs from the intermediate voltage Vint, according to a first factor of Ai conversion:

The voltage converter circuit 102 is a step-down converter, which means that the conversion factor Ai is less than 1.

The voltage converter circuit 102 firstly comprises a first input terminal Eai and a second input terminal Ea2 intended to receive the intermediate voltage Vint The voltage converter circuit 102 comprises a first switch Qau, a first capacitor Cai and a second switch Qai2 arranged one after the other, on the same branch, with the capacity Cai disposed between the two switches Qau, Qai2.

The voltage converter circuit 102 further comprises first and second transformers T, T ’each having three windings: a first primary winding Laii, Laii · a second primary winding Lai2, Lai2 'and a secondary winding La2i, La2i ·. Each transformer T, T 'further comprises a respective magnetic core (represented by dotted lines) designed to couple the windings Laii, Lai2, La2i, respectively the windings Laii ·, Lai2 ·, La2i ·. It will be noted that the windings Laii, Lai2, La2i are decoupled from the windings Laii ’, Lai2-, La2i ·.

In general, the coupling coefficients between the windings can be different. In the example described, for each transformer T, T ', the coupling coefficient between the first and second primary windings is 1, and the coupling coefficient between the secondary winding and each of the first and second primary windings is N .

Thus, the first primary windings Laii, Laii- are arranged in series between, on the one hand, a midpoint of the switch Qah and of the capacitance Cai and, on the other hand, the input terminal Eai.

Similarly, the second primary windings Lai2, Lai2 · are arranged in series between, on the one hand, a midpoint of the switch Qai2 and of the capacitor Cai and, on the other hand, the input terminal Ea2.

The voltage converter circuit 102 further comprises a first output terminal Sai and a second output terminal Sa2 intended to supply the output voltage Vs. The output terminal Sai is connected to a first electrical ground 104.

The voltage converter circuit 102 further includes a third switch Qa2i and a fourth switch Qa22.

Each secondary winding La2i, La21- is connected between the output terminals Sai, Sa2 through a respective one among the switches Qa2i, Qa22.

The voltage converter circuit 102 further comprises a second capacitor Ca2 connected between the output terminals Sai, Sa2 in order to smooth the output voltage Vs.

Thus, a load Ç can be connected between the output terminals Sai, Sa2 to be supplied electrically at the output voltage Vs. The load Ç comprises for example a battery to be recharged

Thanks to the fact that the voltage converter circuit 102 comprises two branches, one with the first primary windings Laii, Laiv, the other with the second windings La2i, La2i ', the capacity Ca2 is not traversed by the current of only one of the branches at a time, and not by the current received by the input terminal Ea2.

Transformers T, T ’have galvanic isolation distances creating galvanic isolation between the primary and secondary. Thus, the transformers T, T ’form an insulation barrier 106 dividing the voltage converter circuit 102 into two parts Pi, P2. In particular, the electrical grounds 104,112 are isolated.

The switches Qah, Qai2, Qa2i, Qa22 each include, for example, a transistor, such as a MOSFET (from the English "Metal Oxide Semiconductor Field Effect Transistor"). Alternatively, each of a part of the switches Qah, Qai2, Qa2i, Qa22 could be formed by a diode, the state of which would be imposed by the state of the other controllable switches.

The voltage converter 100 further comprises a first control system 108 of the voltage converter circuit 102.

The control system 108 is designed to control the switches Qah, Qai2, Qa2i, Qa22 in order to switch the voltage converter circuit 102 between a first state where the switches Qah, Qa2i are closed while the switches Qai2, Qa22 are open, and a second state where the switches Qah, Qa2i are open while the switches Qai2, Qa22 are closed.

The control system 108 is designed to switch the voltage converter circuit 102 to a first frequency Fi corresponding to a first period Ti:

During each period Ti, the two states succeed each other according to a first duty cycle ai. Thus, the first state is maintained for a time αι · Τι, while the second state is maintained for a time (l-ai) -Ti.

As will be explained below, the conversion factor Ai depends on the duty cycle ai. In the example described, the conversion factor Ai is substantially equal to:

Ai = 2 N a! (1 - ai) where N is the conversion coefficient between the secondary winding and each of the primary windings.

In the example described, the control system 108 is designed to switch the voltage converter circuit 102 with a constant duty cycle ai, preferably equal to 0.5.

The voltage converter 100 further comprises a second voltage converter circuit 110, which is a DC / DC converter intended to receive the input voltage Ve and designed to supply the intermediate voltage Vint to the first voltage converter circuit 102 from the input voltage Ve, according to a second conversion factor A2:

The voltage converter circuit 110 is a step-up / step-down converter, which means that the factor A2 can be less than, equal to or greater than 1.

The voltage converter circuit 110 firstly comprises a first input terminal Ebi intended to be connected to a second electrical ground 112, different from the first electrical ground 104, and a second input terminal Eb2 intended to be connected to a DC voltage source 114 for receiving the input voltage Ve.

The voltage converter circuit 110 further comprises a first switch Qbi having a first side connected to the first input terminal Eia.

The voltage converter circuit 110 further comprises a first inductor Lbi connected between a second side of the switch Qbi and the input terminal Ebi.

The voltage converter circuit 110 further comprises a first capacitor Cbi having a first side connected to a midpoint of the switch Qbi and of the inductance Lbi.

The voltage converter circuit 110 further comprises a second inductor Lb2 having a first side connected between the capacitor Cbi.

The voltage converter circuit 110 further comprises a second switch Qb2 connected between, on the one hand, a midpoint of the capacitor Cbi and of the inductance Lb2 and, on the other hand, the input terminal Ebi.

The voltage converter circuit 110 further comprises a first output terminal Sbi connected to the input terminal Ebi and a second output terminal Sb2 connected to a second side of the inductance Lb2. The output terminals Sbi, Sb2 are connected respectively to the input terminals Eai, Ea2 of the voltage converter circuit 102 to supply the latter with the intermediate voltage Vint.

The voltage converter circuit 110 further comprises a second capacitor Cb2 connected between the two output terminals Sbi, Sb2 to smooth the intermediate voltage Vint.

The voltage converter 100 further comprises a second control system 116 of the voltage converter circuit 110.

The control system 116 is designed to control the switches Qbi, Qb2 to switch the voltage converter circuit 110 between a first state where the switch Qbi is closed while the switch Qb2 is open, and a second state where the Qbi switch is open while Qb2 switch is closed.

The control system 116 is designed to switch the voltage converter circuit 110 to a second frequency F2 corresponding to a second period T2:

The frequencies Fi, F2 can be identical or different. Preferably, they are different. More preferably, the switching frequency F2 of the voltage converter circuit 110 is greater than the switching frequency Fi of the voltage converter circuit 102.

During each period T2, the two states succeed each other according to a second duty cycle (X2. Thus, the first state is maintained for a time 0C2-T2, while the second state is maintained for a time (1-α2) · Τ2.

As will be explained below, the conversion factor A2 depends on the duty cycle Œ2. In the example described, the conversion factor A2 is substantially worth:

"2 (1 - a ₂ )

The control system 116 is further designed to receive a reference output voltage Vs_ref and to measure the output voltage Vs.

The control system 116 is further designed to modify the duty cycle 0C2 so that the output voltage Vs follows the reference output voltage Vs_ref.

With reference to FIGS. 2 and 3, the operation of the voltage converter circuit 102 will now be described.

With reference to FIG. 2, when the voltage converter circuit 102 is in its first state, energy is directly transferred from the input terminals Eai, Ea2 to the output terminals Sai, Sa2 through the transformer T ' . In addition, the secondary winding La2i is disconnected so that the primary windings Lau, Lai2 form inductances charged from the input terminals Eai, Ea2.

With reference to FIG. 3, when the voltage converter circuit 102 is in its second state, energy is directly transferred from the input terminals Eai, Ea2 to the output terminals Sai, Sa2 through the transformer T. In addition, the secondary winding La2i- is disconnected so that the primary windings Laiv, Lai2 · form inductances charged from the input terminals Eai, Ea2 The charging of the primary windings Lau, Lai2 makes it easier to switch the switches to 0V Qah, Qai2. More precisely, these latter have, by construction, parallel capacities (not shown). Thus, when one of the switches Qah, Qai2 is open, this parallel capacity is charged. The closing of the switch is generally preceded by a dead time during which the two switches Qah, Qai2 are open. During this dead time, the energy stored in the primary windings of the branch in parallel with the switch about to be closed allows the parallel capacity of this switch to be discharged. The energy stored in the primary windings is preferably greater than that stored in the parallel capacity to allow the discharge of the latter. Thus, the switch can be closed with zero voltage across its terminals.

As indicated above, the duty cycle ai is preferably 0.5. Thus, there is a balancing of the windings Laii, Lai2, La2i and the windings Laii ', Lai2 ·, La2i ·· More precisely, the branches of the primary Laii, Laii' and Lai2, Lai2 'are traversed on average by the same current , so that the primary windings have the same aging.

In addition, the voltage converter circuit 102 supplies a current at the output, more particularly at the output of the transformers T, T ′ which is substantially continuous and therefore has ripples which are weak because the ripples of the currents in inductors. the transformers T, T's are compensated.

Thus, the switches Qa2i, Qa22 are traversed on average and in steady state by the same current when they are closed and undergo the same maximum voltage when they are open. However, the switches Qa2i, Qa22 have respective reverse diodes (for example, intrinsically), not shown, undergoing the maximum voltages which depend on the duty cycle ai. More precisely, the maximum voltage Vi for the reverse diode of the switch Qa2i is substantially worth:

The maximum voltage V2 for the reverse diode of the switch Qa22 is substantially worth:

Thus, with a duty cycle ai equal to 0.5, the voltage maximums Vi, V2 are equal, and the aging of the diodes is the same.

With reference to FIGS. 4 and 5, the operation of the voltage converter circuit 110 will now be described.

With reference to FIG. 4, when the voltage converter circuit 110 is in its first state, the inductance Lbi and the inductance Lb2 are charged from the input terminal Eb2. Thus, the inductance Lb2 supplies an increasing current to the output terminal Sb2.

With reference to FIG. 5, when the voltage converter circuit 110 is in the second state, the input terminal Eb2 so that it no longer supplies energy. In addition, the inductor Lbi discharges into the capacitor Cbi while the inductor Lb2 discharges into the second output terminal Sb2. Thus, the inductance Lb2 supplies a decreasing current to the output terminal Sb2.

Thus, the Lbi inductor and the Qbi switch form a serial chopper ("buck converter" in English).

With reference to FIG. 6, a voltage converter 600 according to a second embodiment of the invention will now be described.

The voltage converter 600 is identical to the voltage converter 100, except that the switches Qa2i, Qa22 in FIG. 1 are split in order to halve the voltage experienced when they are opened.

More precisely, the switch Qa2i in FIG. 1 is split into two switches Qa2ia, Qa2ib. To allow this duplication, the secondary winding La21 'of Figure 1 is also split and has two parts of secondary winding La2i-a, La2ib. The switch Qa2i and the secondary winding part La21’a are arranged in series in a first branch. The Qa2ib switch and the secondary winding part La21’b are arranged in series in a second branch. The first and second branches are connected between the output terminals Sai, Sa2 and each other at a first midpoint.

Furthermore, the switch Qa22 in FIG. 1 is split into two switches Qa22a, Qa22b. To allow this duplication, the secondary winding La2i of FIG. 1 is also split and comprises two parts of secondary winding La2ia, La2ib. The Qa22a switch and the La2ia secondary winding are arranged in series in a third branch. The Qa2ib switch and the La2ib secondary winding are arranged in series in a fourth branch. The third and fourth branches are connected between the output terminals Sai, Sa2 and to each other at a second midpoint, connected to the first midpoint.

In operation, in the first state, the switches Qa2ia, Qazib are closed while the switches Qa22a, Qa22b are open. A direct transfer of energy then takes place from the windings Laii ·, Lai2 ’to the windings La2ia, La2ib- In addition, energy is stored in the windings Laii, Lai2.

Conversely, in the second state, the switches Qa22a, Qa22b are closed while the switches Qa2ia, Qa2ib are open. A direct transfer of energy then takes place from the windings Laii, Lai2 to the windings La2ia, La2ib. In addition, energy is stored in the windings Laii-, Lai2 ·.

The present invention is not limited to the embodiments described above, but is on the contrary defined by the claims which follow. It will in fact be apparent to those skilled in the art that modifications can be made to it.

Furthermore, the terms used in the claims must not be understood as limited to the elements of the embodiments described above, but must on the contrary be understood as covering all the equivalent elements which the person skilled in the art can deduce from his knowledge. general.

Claims (11)

1. Voltage converter (100) comprising: - a first voltage converter circuit (102) isolated and comprising: - first and second input terminals (Eai, Εας) between which a DC intermediate voltage (Vint) is intended to be received, - first and second output terminals (Sai, Sa2) between which a continuous output voltage (Vs) is intended to be supplied, - a second voltage converter circuit (110) comprising: - first and second input terminals (Ebi, Εβς) between which a continuous input voltage (Ve) is intended to be received, the first input terminal (Ebi) being intended to be connected to an electrical ground ( 112), - first and second output terminals (Sbi, Sb2) between which the intermediate voltage (Vint) is intended to be supplied, the first output terminal (Sbi) being connected to the first input terminal (Ebi), - a control system (116) of the second voltage converter circuit (110) designed to: - receive a reference output voltage (Vs_ref), - switching the second voltage converter circuit (110) between first and second states according to a cyclic ratio ct2, as a function of said reference output voltage (Vs.ref), the voltage converter (100) being characterized in that that the second voltage converter circuit (110) comprises a first inductance (Lbi), a second inductance (Lb2) and a capacitor (Cbi), and is designed: in the first state: - so that the input terminals (Ebi, Eb2) supply energy to the first inductor (Lbi), - so that the input terminals (Ebi, Εβς) and the capacity (Cbi) supply energy to the second inductor (Lb2) and to the output terminals (Sbi, Sb2), in the second state: - to disconnect one of the input terminals (Ebi, Eb2) so that they no longer supply energy, - so that the first inductor (Lbi) supplies energy to the capacity (Cbi), - so that the second inductor (Lb2) supplies energy to the output terminals (Sbi, Sb2). 2. Voltage converter (100) according to claim 1, in which the second voltage converter circuit (110) further comprises a first switch (Qbi), the first switch (Qbi) and the first inductor (Lbi) being connected to one after the other, between the input terminals (Ebi, Eb2), in which the capacitor (Cbi) and the second inductor (Lb2) are arranged one after the other, between , on the one hand, a midpoint of the first switch (Qbi) and of the first inductor (Lbi) and, on the other hand, the second output terminal (Sb2), in which the second voltage converter circuit (110) further comprises a second switch (Qb2) connected between, on the one hand, a midpoint of the capacitor (Cbi) and of the second inductor (Lb2) and, on the other hand, the first input terminal (Ebi) . 3. Voltage converter (100) according to claim 1 or 2, further comprising a control system (108) of the first voltage converter circuit (102) designed to switch the first voltage converter circuit (102) between two states , at a first switching frequency (F1), and in which the control system (116] of the second voltage converter circuit (110) switches the second voltage converter circuit (110] to a second switching frequency (F2) . 4. Voltage converter (100) according to claim 3, wherein the first and second switching frequencies (Fi, F2) are different from each other. 5. Voltage converter (100) according to claim 4, in which the second switching frequency (F2) is greater than the first switching frequency (Fi). 6. Voltage converter (100) according to claim 3, wherein the control system (108) of the first voltage converter circuit (102) switches the first voltage converter circuit (102) in a constant duty cycle ai. 7. Voltage converter (100) according to claim 6, wherein the duty cycle ai is 0.5. 8. Voltage converter (100) according to any one of claims 1 to 7, wherein the second voltage converter circuit (110) has a conversion ratio of the intermediate voltage (Vint) relative to the input voltage (Ve) dependent on the duty cycle a2 and may be greater than, equal to or less than 1 depending on the duty cycle a2 of the second voltage converter circuit (110). 9. Voltage converter (100) according to any one of claims 1 to 8, in which the first voltage converter circuit (102) comprises: a first switch (Qaii), a first capacity (Cai) and a second switch (Qai2) arranged one after the other, the first capacity (Cai) being disposed between the two switches (Qaii, Οαις), - a first transformer (T) comprising a first primary winding (Laii), a second primary winding (Lai2), a secondary winding (La2i) and a first magnetic core coupling these three windings (Laii, Lai2, La2i), - a second transformer (T '] comprising a first primary winding (Laii ·), a second primary winding (Lai2 ·), a secondary winding (La2i) and a second magnetic core coupling these three windings (Laii ·, Lai2 ·, La2i ), the first primary windings (Laii, Laii) being arranged in series between, on the one hand, a midpoint of the first switch Qah and of the first capacitor (Cai) and, on the other hand, the first input terminal (Eai), and the second primary windings (Lai2, Lai2 ') being arranged in series between, on the one hand, a midpoint of the second switch (Qai2) and of the first capacitor (Cai) and, on the other hand, the second input terminal (Ea2). 10. Voltage converter (100) according to claim 9, in which each of the two secondary windings (La2i, La2i) is connected, on one side, to one of the two output terminals (Sa2) and, of a on the other side, to the other of the two output terminals (SA1) through a respective switch (Qa2i, Qa22). 11. Voltage converter (100) according to claim 9, wherein the first voltage converter circuit (102) comprises two branches each comprising a first switch (Qa22a, Qa2ia), one respective of the two secondary windings (La2i, La2i ) and a second switch (Qa22b, Qa2ib), and in which the two secondary windings (La2i, La2i) respectively have two intermediate points connected to each other. 1/4