Resonant electrical converter for on-board electric vehicle charger

Abstract

The invention relates to an electrical converter comprising: - a primary conversion stage (100), - a secondary conversion stage (200), and - a resonant network (300) comprising a plurality of resonant assemblies (Epi), the resonant network (300) being configured to electrically isolate the primary conversion stage (100) and the secondary conversion stage (200). The invention also relates to a charger for an electric or hybrid vehicle. The invention further relates to the electric or hybrid vehicle comprising said charger. Figure 1

Description

Title of the invention: Resonant electrical converter for on-board electric vehicle charger Technical field of the invention

[0001] The present invention relates to an electrical converter, in particular a resonant electrical converter, and a charger for an electric or hybrid vehicle comprising the electrical converter.

[0002] The invention further relates to the electric or hybrid vehicle including the charger. State of the art

[0003] It is known in the prior art to use LLC isolated resonant converters for on-board chargers of electric vehicles. These converters provide galvanic isolation between the primary and secondary windings of the transformer, thus ensuring safe operation of the converter and reducing electromagnetic interference.

[0004] However, this galvanic isolation requires the use of bulky transformers, which increases the size and weight of the on-board chargers.

[0005] Furthermore, isolated LLC converters are subject to common-mode leakage current problems. These leakage currents are primarily caused by capacitors integrated in parallel at the converter's input and output, intended to filter electromagnetic interference. These leakage currents can lead to energy losses, electromagnetic interference, and safety problems.

[0006] There is therefore a need for an on-board charger for electric or hybrid vehicles that is compact, economical and has a satisfactory performance.

[0007] Object of the invention

[0008] The present invention aims to provide a solution that addresses all or part of the aforementioned problems.

[0009] This goal can be achieved through the implementation of an electrical converter comprising: - a primary conversion stage comprising n primary switching arms, n being an integer greater than or equal to two, each primary switching arm having a rank i, i being an integer between 1 and n, the primary conversion stage being configured to receive a primary input voltage between a first primary input node and a second input node primary and to generate a primary output voltage of rank i between a primary node of rank i and a primary node of rank higher than i, - a secondary conversion stage comprising n secondary switching arms, each secondary switching arm having a rank i, the secondary conversion stage being configured to receive a secondary input voltage between a secondary node of rank i and a secondary node of rank higher than i, and to generate a secondary output voltage, - a resonant network comprising n resonant sets, each resonant set having a rank i, each resonant assembly of rank i comprising at least one primary capacitor connected between the primary node of rank i and the secondary node of rank i, the resonant network comprising at least one transverse inductor connected between the secondary node of rank i and an intermediate node, the resonant network being configured to electrically isolate the primary conversion stage and the secondary conversion stage.

[0010] The converter may also have one or more of the following characteristics, taken alone or in combination.

[0011] According to one feature, each resonant set of rank i comprises a primary inductance connected in series with the primary capacitor between the primary node of rank i and the secondary node of rank i.

[0012] According to one feature, the primary capacitor is configured to electrically isolate the primary conversion stage and the secondary conversion stage.

[0013] According to one characteristic, the integer n is equal to 3.

[0014] According to one feature, the converter is configured to allow the transfer of electrical energy from the primary conversion stage to the secondary conversion stage and vice versa.

[0015] According to one feature, the converter is configured to be connected, on the one hand, to an external voltage source, for example a charging station, to receive the primary input voltage (Vin), and on the other hand, to a traction battery of an electric or hybrid vehicle to provide said battery with the secondary output voltage (Vout) to recharge said battery.

[0016] The invention further relates to a charger for electric or hybrid vehicles comprising the electrical converter described above.

[0017] According to one characteristic, the charger is onboard in the electric or hybrid vehicle.

[0018] The invention further relates to an electric or hybrid vehicle comprising the charger described above.

[0019] Brief description of the drawings

[0020] Other aspects, objectives, advantages and features of the invention will become clearer upon reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0021] [Fig-1] is an example of an embodiment of an electrical converter according to the invention.

[0022] [Fig.2] presents several examples of a resonant network included in the electrical converter according to the invention.

[0023] [Fig.3] is an example of an embodiment of the electrical converter according to the invention showing values ​​of the different components of the converter.

[0024] [Fig.4] is a graph showing the voltage gain of the converter with respect to the resonant frequency of the converter for different output power values. Detailed description

[0025] In the figures and throughout the description, the same reference numerals represent identical or similar elements. Furthermore, the various elements are not drawn to scale in order to enhance the clarity of the figures. Moreover, the different embodiments and variants are not mutually exclusive and may be combined.

[0026] The invention relates first of all to an electrical converter, an example of an embodiment of which is presented in [Fig.1].

[0027] The electrical converter includes a primary conversion stage 100 comprising a number n of primary switching arms Bpi, n being an integer greater than or equal to two. Each primary switching arm Bpi has a rank i, i being an integer between 1 and n.

[0028] The integer n can be equal to 2, 3, 4 or 5. The integer n can be greater than 5.

[0029] Advantageously, if n=3, the electrical converter is suitable for use on a three-phase electrical network.

[0030] For example, in [Fig. 1], n is equal to 3 and the primary stage 100 comprises three primary switching arms Bpi, Bp2, Bp3. The primary switching arm Bpi has a rank i=1, the primary switching arm Bp2 has a rank i=2, and the primary switching arm Bp3 has a rank i=3.

[0031] The primary conversion stage 100 can receive a primary input voltage Vin between a first primary input node inl and a second primary input node in2. The primary input voltage Vin can, for example, be a DC voltage and come from a voltage source external to the converter, for example a charging station, particularly for motor vehicles.

[0032] The primary conversion stage 100 can generate a primary output voltage Vai of rank i between a primary node of rank i Ai and a primary node of rank higher than i. In the case of [Fig.1], the primary output voltage Vai can be between the node Ai and the node Ai+1 or between Ai+1 and Ai+2 or between Ai and Ai+2.

[0033] The electrical converter also includes a secondary conversion stage 200 comprising n secondary switching arms B si, each secondary switching arm B si having a rank i.

[0034] For example, in [Fig.1], the secondary stage 200 comprises three primary switching arms Bs1, Bs2, Bs3. The secondary switching arm Bs1 has a rank i=1, the primary switching arm Bs2 has a rank i=2, and the primary switching arm Bs3 has a rank i=3.

[0035] The secondary conversion stage 200 can receive a secondary input voltage Vbi between a secondary node of rank i Bi and a secondary node of rank higher than i. In the case of [Fig.1], the secondary input voltage Vbi can be between node Bi and node Bi+1 or between Bi+1 and Bi+2 or between Bi and Bi+2.

[0036] The secondary conversion stage 200 can generate a secondary output voltage Vout. The secondary output voltage Vout can be a DC voltage intended to recharge the battery of an electric or hybrid vehicle.

[0037] The electrical converter also includes a resonant network 300 comprising n resonant sets Epi, each resonant set Epi having a rank i. In the case of [Fig.1], the resonant network comprises three resonant sets Cpl, Lpl, Cp2, Lp2, Cp3, Lp3.

[0038] Each resonant set of rank i includes at least one primary capacitor Cpi connected between the primary node of rank i Ai and the secondary node of rank i Bi.

[0039] Advantageously, the resonant network 300 makes it possible to ensure smooth switching of the converter and thus reduce switching losses.

[0040] The resonant network 300 includes at least one transverse inductance Lbi connected between the secondary node of rank i Bi and an intermediate node X.

[0041] Advantageously, at least one transverse inductance Lbi allows the secondary output voltage Vout to be raised relative to the primary input voltage.

[0042] Alternatively, at least one transverse inductance Lbi can allow the secondary output voltage Vout to be lowered relative to the primary input voltage Vin.

[0043] According to one possibility, each transverse inductance Lbi can have an infinite value. In other words, each transverse inductance Lbi can behave like an open circuit.

[0044] The resonant network 300 electrically isolates the primary conversion stage 100 and the secondary conversion stage 200. In particular, the primary capacitor Cpi can electrically isolate the primary conversion stage 100 and the secondary conversion stage 200.

[0045] Advantageously, the fact that the resonant network 300 and in particular the primary capacitor Cpi provides electrical isolation ensures safe operation while reducing the size and cost of the converter.

[0046] The primary capacitor Cpi can limit a leakage current value to a maximum value of 10 mA.

[0047] According to one possibility, each resonant set of rank i can include a primary inductance Lpi connected in series with the primary capacitor Cpi between the primary node of rank i Ai and the secondary node of rank i Bi as is the case in [Fig.1].

[0048] Examples of the resonant network 300 comprising the primary inductance Lpi connected in series with the primary capacitor Cpi for n=2, n=3, n=4 and n=5 are shown in [Fig.2].

[0049] Advantageously, the converter allows the secondary output voltage Vout to be raised relative to the primary input voltage Vin or vice versa.

[0050] Fig. 3 presents an example of an embodiment of the converter of Fig. 1 showing the values ​​of the different components.

[0051] In the example of [Fig.3], the primary input voltage Vin is 650V and the secondary output voltage Vout is 800V.

[0052] The operation of the converter is described below:

[0053] The Qpi switches of the primary stage 100 and the Qsi switches of the secondary stage 200 can be MOSFET or IGBT type transistors.

[0054] The Qpi switches of the primary stage 100 are initiated and blocked in a synchronized manner to allow the transfer of energy between the input and output of the primary stage 100.

[0055] The inductances Lpi and the capacitors Cpi form a resonant circuit which determines the resonant frequency of the converter.

[0056] The resonance frequency can be determined according to the following formula:

[0057] [Math.l] f = -r=^= Zn-^LpiCpi

[0058] In the example shown in [Fig.3], the inductances Lpi, Lsi have a value of 7pH and the capacitors Cpi, Csi have a value of 10 nF and the resonance frequency is about 600 kHz.

[0059] Advantageously, the converter operates in soft switching, which minimizes switching losses.

[0060] Each transverse inductance has a value of 4.2 pH.

[0061] The resonant network 300 generates, from the primary output voltage Vai, a secondary input voltage Vbi for the secondary stage 200.

[0062] The Qsi switches of the secondary stage 200 are activated and deactivated synchronously to allow rectification of the secondary input voltage Vbi and generation of a continuous secondary output voltage Vout.

[0063] Depending on the secondary output voltage Vout, which can be, for example, the vehicle battery voltage, the switching frequency of transistors Qpi and Qsi is adjusted to ensure the voltage gain as shown in [Fig. 4]. For example, for a primary input voltage Vin of 650V and a secondary output voltage Vout of 800V, the gain is approximately 1.23, which implies a switching frequency of transistors Qpi, Qsi of approximately 570kHz.

[0064] In the example described above, the electrical converter converts the direct current primary input voltage Vin into a direct current secondary output voltage Vout intended to recharge the battery of a motor vehicle. In this case, the primary stage 100 acts as an inverter and the secondary stage 200 is an electrical rectifier.

[0065] However, the converter is also configured to convert the secondary DC output voltage Vout into the primary DC input voltage Vin. In this case, the secondary stage 200 is an electrical inverter and the primary stage 100 is an electrical rectifier.

[0066] Thus, the converter can be configured to allow the transfer of electrical energy from the primary conversion stage 100 to the secondary conversion stage 200 and vice versa. In other words, the converter can be bidirectional.

[0067] The converter can be connected to a charging station on the one hand to receive the primary input voltage Vin and to a traction battery of an electric or hybrid vehicle on the other hand to supply said battery with the secondary output voltage Vout.

[0068] The invention further relates to a charger for an electric or hybrid vehicle comprising the converter as described above. The charger may be an on-board charger in the electric or hybrid vehicle, for example, an OBC (On-Board Charger). The charger converts a direct current voltage from an external source into a direct current voltage for charging the vehicle's battery. The vehicle may, in particular, be a motor vehicle.

[0069] Advantageously, the electrical converter according to the invention does not include a transformer, so the on-board charger including the converter is therefore more compact and less expensive than an on-board charger including a transformer.

[0070] Advantageously, the on-board charger comprising the converter according to the invention has a better power efficiency compared to a charger comprising a transformer.

[0071] The invention also relates to an electric or hybrid vehicle comprising the charger described above.

Claims

Demands

1. Electrical converter comprising: - a primary conversion stage (100) comprising a number n of primary switching arms (Bpi), n being an integer greater than or equal to two, each primary switching arm (Bpi) having a rank i, i being an integer between 1 and n, the primary conversion stage (100) being configured to receive a primary input voltage (Vin) between a first primary input node (in1) and a second primary input node (in2) and to generate a primary output voltage (Vai) of rank i between a primary node of rank i (Ai) and a primary node of rank greater than i, - a secondary conversion stage (200) comprising n secondary switching arms (Bsi), each secondary switching arm (Bsi) having a rank i, the secondary conversion stage (200) being configured to receive a secondary input voltage (Vbi) between a secondary node of rank i (Bi) and a secondary node of rank higher than i, and to generate a secondary output voltage (Vout), - a resonant network (300) comprising n resonant assemblies (Epi), each resonant assembly (Epi) having a rank i, each resonant assembly of rank i comprising at least one primary capacitor (Cpi) connected between the primary node of rank i (Ai) and the secondary node of rank i (Bi), the resonant network (300) comprising at least one transverse inductance (Lbi) connected between the secondary node of rank i (Bi) and an intermediate node (X),the resonant network (300) being configured to electrically isolate the primary conversion stage (100) and the secondary conversion stage (200).

2. Electrical converter according to claim 1 in which each resonant set (Epi) of rank i comprises a primary inductance (Lpi) connected in series with the primary capacitor (Cpi) between the primary node of rank i (Ai) and the secondary node of rank i (Bi).

3. Converter according to any one of the preceding claims in which the primary capacitor (Cpi) is configured to electrically isolate the primary conversion stage (100) and the secondary conversion stage (200).

4. Converter according to any one of the preceding claims in which the integer n is equal to 3.

5. Converter according to any one of the preceding claims in which said converter is configured to allow a transfer of electrical energy from the primary conversion stage (100) to the secondary conversion stage (200) and vice versa.

6. Converter according to any one of the preceding claims wherein said converter is configured to be connected, on the one hand, to an external voltage source, for example a charging station, to receive the primary input voltage (Vin), and on the other hand, to a traction battery of an electric or hybrid vehicle to provide said battery with the secondary output voltage (Vout) to recharge said battery.

7. Charger for electric or hybrid vehicle comprising the electric converter according to one of the preceding claims.

8. Charger according to claim 7 wherein the charger is mounted in the electric or hybrid vehicle.

9. Electric or hybrid vehicle including the charger according to one of claims 7 or 8.

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