DC-to-DC converter

Abstract

The invention relates to a DC-to-DC converter (102) comprising: - a positive input terminal (PA) and a negative input terminal (NA); - a positive output terminal (PB) and a negative output terminal (NB); - a plurality of branches (Br1, Br2), each comprising a capacitor (C1, C2); - a plurality of interconnection circuits (I1, I2) respectively associated with the branches (Br1, Br2) and each designed to alternately: connect the associated branch (Br1, Br2) between the input terminals (PA, NA) to charge the capacitor (C1, C2) from the positive input terminal (PA) such that the capacitor (C1, C2) has a voltage (VC1, VC2), and connect the associated branch (Br1, Br2), between the output terminals (PB, NB) and after the input terminals (PA, NA), such that the voltage of the capacitor (VC1, VC2) is added to a DC input voltage (VA) present between the input terminals (PA, NA), in order to discharge the capacitor (C1, C2) to the positive output terminal (PB); and - a control device (104) designed to control the interconnection circuits (I1, I2) in a phase-shifted manner.

Description

Description TITLE: DC-DC CONVERTER Technical field of the invention

[0001] The present invention relates to a DC-DC converter and a mobility device comprising such a DC-DC converter.

[0002] A mobility device is, for example, a motorized land vehicle, a train, an aircraft, or a drone. A motorized land vehicle is, for example, a car, a motorcycle, a motorized bicycle, or a motorized wheelchair. Technological background

[0003] A DC-DC converter is known from the prior art, comprising: a positive input terminal and a negative input terminal; a positive output terminal and a negative output terminal; a branch containing a capacitor; and an interconnection circuit designed to alternately: • Connect the branch between the input terminals to charge the capacitor from the positive input terminal so that the capacitor exhibits a voltage, and • connect, between the output terminals, the branch following the input terminals so that the voltage of the capacitor adds to a DC input voltage, to discharge the capacitor towards the positive output terminal; and a control device designed to control the interconnection circuit.

[0004] Thus, in the first configuration, the capacitor can be charged by a DC input voltage source connected between the input terminals. In the second configuration, the capacitor's voltage is added to that of the DC input voltage source to provide current to the positive output terminal, thereby regulating the DC output voltage present between the output terminals to a value higher than the DC input voltage.

[0005] Thus, current is only supplied when the interconnection circuit is in the second configuration and not in the first, which implies significant current oscillations.

[0006] It may therefore be desirable to provide a DC-DC converter which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0007] A DC-DC converter is therefore proposed, comprising: a positive input terminal and a negative input terminal; a positive output terminal and a negative output terminal; several branches, each with a capacitor; and several interconnection circuits, each associated with one of the branches and designed to alternately: • Connect the associated branch between the input terminals to charge the capacitor from the positive input terminal so that the capacitor exhibits a voltage, and • connect, between the output terminals, the branch associated with the sequence of input terminals so that the voltage of the capacitor adds to a DC input voltage present between the input terminals, to discharge the capacitor towards the positive output terminal; and a control device designed to control the interconnection circuits in a phase-shifted manner.

[0008] Thanks to the invention, since the interconnection circuits are controlled in a phase-shifted manner, when one of them is in the first configuration, another is in the second configuration and current is therefore supplied to the positive output terminal.

[0009] The invention may further include one or more of the following optional features, in any technically feasible combination.

[0010] Optionally, each branch includes an inductance in series with the capacitance of the branch in question.

[0011] Optionally, for each interconnection circuit, each alternation between the two configurations is performed at a frequency and according to a duty cycle, and within which the control device is designed, in order to control the DC output voltage, to keep the duty cycle constant but to change the frequency.

[0012] Optionally, the control device is also designed to maintain the alternating frequency above a resonance frequency of each of the branches.

[0013] Optionally, each interconnection circuit also includes two controllable switches connected to each other at a midpoint and together between the input terminals and two other switches connected to each other at a midpoint and together between the positive terminals, and the branch is connected between the midpoints.

[0014] Optionally, the other switches are also diodes conducting towards the positive output terminal.

[0015] Optionally, there are also two, three, or four branches and interconnection circuits.

[0016] Optionally, for each interconnection circuit, each alternation between the two configurations extends over a period, the latter having the same duration, and the periods are offset by the period duration divided by N, N being the number of branches and interconnection circuits.

[0017] A mobility device incorporating a DC-DC converter according to the invention is also proposed. 1 Brief description of the figures

[0018] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: Figure 1 is an electrical diagram of an electrical circuit comprising a DC-DC converter according to the invention, Figure 2 reproduces the electrical diagram of Figure 1, in the case where two interconnection circuits are in a first configuration, Figure 3 reproduces the electrical diagram of Figure 1, in the case where the two interconnection circuits are in a second configuration, Figure 4 is a timing diagram illustrating an example of alternating configuration of the two interconnection circuits, and Figure 5 is a timing diagram illustrating an example of alternating configuration of three interconnection circuits. Detailed description of the invention

[0019] With reference to Figure 1, an electrical circuit 100 according to the invention will now be described.

[0020] The electrical circuit 100 includes first of all a DC input voltage source SA designed to provide a DC input voltage VA.

[0021] The electrical circuit 100 further includes a load Z designed to be powered by a DC output voltage VB higher than the DC input voltage VA. The load Z may, for example, include another DC voltage source.

[0022] The electrical circuit 100 further includes a DC-DC converter 102 designed to convert the input DC voltage VA into the output DC voltage VB.

[0023] The DC-DC converter 102 thus comprises, firstly, a positive input terminal PA and a negative input terminal NA, between which the input DC voltage source SA is intended to be connected to provide the voltage 2 continuous input VA. Preferably, the DC-DC converter 102 has an input capacitance CE between the input terminals PA, NA.

[0024] The DC-DC converter 102 further includes a positive output terminal PB and a negative output terminal NB between which the load Z is intended to be connected to receive the DC output voltage VB. Preferably, the DC-DC converter 102 includes an output capacitor CS between the output terminals PB and NB.

[0025] The DC-DC converter 102 further comprises several branches Br1, Br2, each containing a capacitor C1, C2. Preferably, each branch Br1, Br2 also includes an inductor L1, L2 in series with the capacitor C1, C2 of that branch. This creates resonance between the capacitor C1, C2 and the inductor L1, L2, at a resonant frequency F1, F2: F1 = 1A / L1C1 and F2 = 1A / L2C2. The inductor L1, L2 also allows current to flow through the capacitor C1, C2. Preferably, the capacitors C1, C2 have the same value, as do the inductors L1, L2.

[0026] The DC-DC converter 102 also includes several interconnection circuits 11, I2 respectively associated with branches Br1, Br2. Each of the interconnection circuits 11, I2 is designed to alternatively connect the branch according to two configurations which will be detailed later.

[0027] For example, as in the illustrated example, each interconnection circuit 11, I2 has two controllable switches Q1 A, Q1 B and Q2 A Q2 B connected to each other at a midpoint M1, M2 and together between the input terminals PA, NA, and two switches connected to each other at a midpoint M'1, M'2 and together between the positive terminals PA, PB. These latter switches are, for example, as in the illustrated example, diodes D1 A , D1 B and D2 A , D2 B passing towards the positive output terminal PB. The branch Br 1 , Br2 is then connected between the midpoints M1 , M'1 and M2 , M'2.

[0028] Each switch is preferably semiconductor, such as a metal-oxide-semiconductor field-effect transistor (MOSFET), a silicon metal-oxide-semiconductor field-effect transistor (SiMOSFET), or a silicon carbide metal-oxide-semiconductor field-effect transistor. 3 Semiconductor Field Effect Transistor (also known as SiC MOSFET) or an Insulated Gate Bipolar Transistor (also known as IGBT) or a Gallium Nitride Field Effect Transistor (also known as GaN FET).

[0029] The DC-DC converter 102 then includes a control device 104 designed to control the interconnection circuits 11, I2 so that each alternates between its two configurations, in a phase-shifted manner as will be detailed later. For example, as in the illustrated example, the control device 104 is designed to control the switchable switches Q1A, Q1B and Q2A, Q2B.

[0030] Referring to Figure 2, the interconnection circuits 11, I2 are shown in their first configuration. In this configuration, the interconnection circuit 11, I2 connects the branch Br1, Br2 between the input terminals PA, NA to charge the capacitor C1, C2 from the positive input terminal PA so that the capacitor C1, C2 has a voltage VC1, VC2. For example, as in the illustrated example, the controllable switch Q1B is closed, while the controllable switch Q1A is open. Thus, diode D1 c , D2 Cis conducting, while diode D1 D , D2 D is blocked.

[0031] Referring to Figure 3, the interconnection circuits 11, I2 are shown in their second configuration. In this configuration, the interconnection circuit 11, I2 connects the branch Br1, Br2 following the input terminals PA, NA so that the voltage VC1, VC2 of the capacitor C1, C2 is added to the input voltage VA. Furthermore, the input terminals PA, NA and the branch Br1, Br2 are connected between the output terminals PB, NB to discharge the capacitor C1, C2 to the positive output terminal PB.

[0032] Referring to Figure 4, the control device 104 is designed to control the interconnection circuits 11, I2 to alternate each of them between the first and second configurations. This control is phase-shifted, meaning that the alternation in time between the two configurations is offset from one interconnection circuit 11, I2 to the other. Thus, there are time intervals during which one of the interconnection circuits 11, I2 is in the first configuration, while another of the interconnection circuits 11, I2 is in the second configuration. 4. The second configuration. This allows for a reduction of current ripple at the output of the input voltage source SA and in the output capacitor CS.

[0033] For example, for each interconnection circuit 11, I2, each alternation between the two configurations spans a period P1, P2, each of which has the same duration P. During each period P1, P2, the interconnection circuit 11, I2 is in the first configuration, then in the second configuration, according to a duty cycle, that is, the duration of each configuration within the period P1, P2. In the illustrated example, the duty cycle is 0.5. The configuration alternation is thus performed at a frequency F equal to the inverse of the period duration P.

[0034] The control device 104 is designed, for example, to control the output voltage VB, to keep the duty cycle constant but to modify the frequency F. The latter is preferably kept above the resonance frequency F1, F2 of each of the branches Br1, Br2.

[0035] Thus, in the case of two interconnection circuits 11, I2, as in the illustrated example, the periods P1, P2 are preferably offset by 180°, that is to say by half the duration of period P: P / 2.

[0036] With reference to Figure 5, in the case of three interconnection circuits, the periods P1, P2, P3 are preferably offset by 120°, i.e. by one third of the duration of period P: P / 3.

[0037] In general, in the case of N interconnection circuits, the periods P1 ...PN are preferably offset by 3607N, that is, by the duration of period P divided by N.

[0038] In conclusion, it is clear that a DC-DC converter such as the one described above makes it possible to reduce current oscillations.

[0039] It should also be noted that the invention is not limited to the embodiments described above. Indeed, it will be apparent to those skilled in the art that various modifications can be made to the embodiments described above, in light of the information just disclosed to them.

[0040] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiments set forth in this description, but shall be interpreted to include all equivalents that are foreseeable by a person skilled in the art. 5 by applying his general knowledge to the implementation of the teaching that has just been disclosed to him.

Claims

6 Demands [1] DC-DC converter (102) comprising: a positive input terminal (PA) and a negative input terminal (NA); a positive output terminal (PB) and a negative output terminal (NB); several branches (Br1, Br2) each comprising a capacitor (C1, C2); several interconnection circuits (I1, I2) respectively associated with the branches (Br1, Br2) and each designed to alternately: • Connect the associated branch (Br1, Br2) between the input terminals (PA, NA) to charge the capacitor (C1, C2) from the positive input terminal (PA) so that the capacitor (C1, C2) has a voltage (VC1, VC2), and • connect, between the output terminals (PB, NB), the branch (Br1, Br2) associated with the sequence of input terminals (PA, NA) so that the voltage of the capacitance (VC1, VC2) adds to a DC input voltage (VA) present between the input terminals (PA, NA), to discharge the capacitance (C1, C2) towards the positive output terminal (PB); and a control device (104) designed to control the interconnection circuits (11, I2) in a phase-shifted manner. [2] DC-DC converter (102) according to claim 1, wherein each branch (Br 1 , Br2) has an inductance (L1 , L2) in series with the capacitance (C1 , C2) of the branch (Br1 , Br2) considered. [3] DC-DC converter (102) according to claim 1 or 2, wherein, for each interconnection circuit (11, I2), each alternation between the two configurations is carried out at a frequency and according to a duty cycle, and wherein the control device (104) is designed, in order to control a DC output voltage (VB) present between the output terminals (PB, NB), to keep the duty cycle constant but to change the frequency. [4] DC-DC converter (102) according to claims 2 and 3 taken together, wherein the control device (104) is designed to maintain the alternating frequency above a resonance frequency of each of the branches (Br1, Br2). 7 [5] DC-DC converter (102) according to any one of claims 1 to 4, wherein each interconnection circuit (11, I2) comprises two controllable switches (Q1 A , Q1 B, Q2 A Q2B ) connected to each other at a midpoint (M1, M2) and together between the input terminals (PA, NA) and two other switches (D1 A , D1 B , D2 A , D2 B ) connected to each other at a midpoint (M'1 , M'2) and together between the positive terminals (PA, PB), and in which the branch (Br1 , Br2) is connected between the midpoints (M1 , M'1 , M2 , M'2). [6] DC-DC converter (102) according to claim 5, wherein the other switches are diodes (D1 A , D1 B , D2 A , D2 B ) passing towards the positive output terminal (PB). [7] DC-DC converter (102) according to any one of claims 1 to 6, wherein the branches (Br1, Br2) and the interconnection circuits (11, I2) are two, three, or four in number. [8] DC-DC converter (102) according to any one of claims 1 to 7, wherein, for each interconnection circuit (11, I2), each alternation between the two configurations extends over a period (P1, P2; P1, P2, P3), the latter having the same duration (P), and wherein the periods (P1, P2; P1, P2, P3) are offset by the duration of period (P) divided by N, N being the number of branches (Br1, Br2) and interconnection circuits (11, I2). [9] Mobility device comprising a DC-DC converter (100) according to any one of claims 1 to 8.

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