FR2808629A1 - Multiple-voltage power supply circuit for motor vehicles, uses inverter supplying transformers to provide different voltage distribution networks - Google Patents

Abstract

The power supply has an alternator (A0) supplying a rectifier (S0), giving DC supply to a 36 volt battery (BATy) for the 36 volt distribution circuit (RDy). The rectifier output also supplies a DC-AC inverter (10) which drives a current loop (BC) that has transformer (S1 - Sn) primaries connected in series. The transformers supply distribution circuits (RD1 - RD2) at different voltages.

Description

The present invention relates, in general, power supply circuits more particularly intended to equip motor vehicles.

More specifically, the invention relates to a power supply circuit of this type, comprising a main source of DC voltage, powered by a rotating machine, and at least first and second auxiliary sources of DC voltage supplied from the main source .

The most common and most widespread electrical circuit architecture to date is composed of an alternator driven by the vehicle engine and feeding a single voltage distribution network, for example 14 volts, a 12 volt battery being mounted buffered on this network.

The electrical energy consuming members feed on this network via distribution boxes equipped with fuses which make it possible to protect the electrical harness by isolating any electricity consuming device that goes into fault, in particular any member affected by A short-circuit.

In such an architecture, the electrical energy consuming members can only communicate with one another via a multiplexed information network, independent of the electrical energy distribution network.

The new situation created by the very rapid growth in the number of electrical components on motor vehicles has recently led some car manufacturers to consider increasing the voltage delivered by the electrical energy distribution circuit, for example by switching it to 42. volts instead of 14 volts.

However, insofar as certain electrical components are by design poorly adapted to such an increase in their supply voltage, and where a specific adaptation of these devices would lead to prohibitive costs, the evolution envisaged requires a priori the use of at least two distribution networks, delivering the electrical energy to two different respective voltages.

The architecture of a power supply circuit conforming to this evolution is for example illustrated in FIG.

Such a circuit typically comprises a rotating machine such as an alternator Ao delivering for example a voltage of 42 volts, this alternator Ao being connected to a rectifier forming a main source Sp of DC voltage, for example delivering a 42 volts DC voltage Vo .

A first auxiliary source Sy, delivering a direct voltage Vy of 42 volts, is directly formed by the main source So, buffered by a BATy battery of 36 volts, for example, this first auxiliary source supplying a first RDy distribution network.

A second auxiliary source Sz, delivering a DC voltage Vz of 14 volts, is constituted by a DC / DC DC / DC converter powered by the main source So whose output is buffered by a BATz battery of 12 volts for example, this second auxiliary source supplying a second RDz distribution network.

Although the known solutions meet some of the needs to be met, these solutions use a single voltage as is the case of the conventional solution, or at least two voltages as is the case of the architecture of Figure 1, they are not without posing various problems.

First of all, the distribution of electrical energy by means of a voltage regulated circuit imposes on each of the consumer organs either to integrate its own DC / DC converter or to be sized to accept the voltage level of power available.

For example, since the computers operate with electronic components that only accept low supply voltages, usually 3 volts or 5 volts, the computers must all integrate DC / DC converters.

Filament lamps, which are however too numerous organs and too low value to integrate such a converter must be sized to be powered by 12 volts. However, this dimensioning requires the choice of relatively thin filaments, whose life is consequently poorly optimized.

Moreover, insofar as these known solutions are designed in such a way that a large variation in the consumption of electrical energy results in a variation of the voltage available on the distribution network, the electrical energy consuming members must themselves - Even be designed to withstand these variations, and therefore meet a strict specifications that increases the cost of manufacture.

On the other hand, to the extent that the known architectures are designed such that a short circuit in any one of the electrical power consuming members could, in the absence of adequate protection, cause a surge current in the wiring harness and the destruction of the latter, it is essential to protect the distribution network by fuses.

Finally, insofar as they require the use of capacitive input stages which naturally act as filters for high frequency signals, these architectures can not be used as physical carriers of information transmission systems. carrier current. The present invention is in this context and aims to provide a power supply circuit for a motor vehicle capable, by its very principle, to solve at least one of the previously mentioned problems.

To this end, the circuit of the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that it comprises a primary stage and at least first and second secondary modules constituting respectively the first and second auxiliary sources, in that the primary stage comprises a primary AC generator supplied by the main source, a current loop in which the alternating current produced by the primary generator circulates, and at least first and second windings connected in series in the current loop and constituting respective primary windings of corresponding first and second transformers, and in that each secondary module comprises a secondary winding of the corresponding transformer and a current-voltage converter connected to this secondary winding, this current-voltage converter being specific to producing a DC output voltage from the alternating current flowing in the secondary winding.

Each secondary module can be sized so that its output voltage is adapted to the type of organs that feeds this module.

The dimensioning of the electrical energy consuming members is therefore no longer under the constraint of an imposed supply voltage, but must only meet the concern of optimizing its cost in relation to its function.

On the other hand, since the network is designed for AC power, it does not filter the high frequency signals, and can therefore be used as the physical medium of a carrier current information transmission system.

In the preferred embodiment of the invention, the AC primary generator comprises a current regulator capable of controlling in amplitude the current flowing in the current loop, and each secondary module comprises a voltage regulator.

Thanks to the independence thus introduced between the overall load of the circuit and the individual load of the different secondary modules, the load variations of such a module have no effect on the other modules, whose output voltage is thus protected from any variation. .

In addition, insofar as the current in the current loop, that is to say in the beam passing through the vehicle, is regulated in the primary stage, the risk that a short circuit in a consumer device electrical energy can cause an over-current that would burn the beam is radically discarded.

The AC primary generator comprises, for example, a resonant circuit connected in series in the current loop and maintained in oscillations by pumping electrical charges taken at a determined frequency on a charge storage circuit connected to the main source of DC voltage and can itself include one or more capacitors.

For this purpose, the AC primary generator may comprise a transistor bridge and a pilot circuit, the transistor bridge being connected to the charge storage circuit and to the resonant circuit for transferring to the resonant circuit the electrical charges taken from the storage circuit. of charge, and each pair of transistor transistor transistors adopting a cyclically variable conduction state, controlled by an output signal at the determined frequency of the driver circuit. The pilot circuit may itself comprise a voltage-frequency converter, controlled by a control voltage dependent on the DC voltage of the main source, for outputting the output signal at the determined frequency, the current regulator comprising in turn a feedback loop adapted to change the control voltage of the voltage-frequency converter as a function of the current flowing in the current loop.

Under these conditions, the voltage regulator advantageously provided in each secondary module is designed to be able to regulate in amplitude the DC output voltage of the current-voltage converter.

This current-voltage converter may for example comprise a rectifier bridge connected to the secondary winding of the transformer, and a capacitive circuit connected to the secondary winding by an electrical connection through the rectifier bridge, this bridge rectifier charging this capacitive circuit.

In this case, the voltage regulator may comprise a threshold detector comparing the charging voltage of the capacitive circuit with a predetermined voltage value, and a switching means controlled by the threshold detector for selectively short-circuiting the secondary winding, and correspondingly interrupting the energy transfer between the secondary winding and the capacitive circuit, when the charging voltage of this capacitive circuit reaches the predetermined voltage value.

The power supply circuit according to the invention develops more particularly its advantages in the case where the first and second transformers have respective transformation ratios which differ from one another, the different secondary modules can thus feed more groups. or less important organs consuming electrical energy at different voltages. Other features and advantages of the invention will emerge clearly from the description which is given below, indicatively and in no way limiting, with reference to the accompanying drawings, in which - Figure 1 is a diagram showing a known architecture of feeding circuit, this figure having already been described in the preamble above; FIG. 2 is a general schematic view of the structure of a circuit according to the present invention; - Figure 3 is a diagram showing more particularly the primary stage of a circuit according to the present invention; and - Figure 4 is a diagram showing more particularly a secondary module of a circuit according to the present invention.

As shown in Figure 1, the power supply circuit of the invention, which is more particularly designed to equip a motor vehicle, essentially comprises a main source So of continuous voltage Vo, powered by a rotating machine such as an alternator Ao, and a plurality of auxiliary voltage sources, denoted Sl, S2, Sn_1, and Sn, fed from the main source So, and delivering respective DC voltages denoted by V1, V2, Vn_1, and Vn for supplying power supply networks. respective distributions RD1, RD2, RDn_1, and RDn.

As in the architecture illustrated in FIG. 1, one of the auxiliary sources, denoted Sy and delivering a direct voltage Vy, can be directly formed by the main source So, buffered by a battery BATy, to supply a first distribution network RDy.

The circuit of the invention differs essentially in that it comprises a primary stage 1 (FIG. 3) and a plurality of secondary modules such as S1 and S2 (FIG. 2) each of which constitutes one of the auxiliary sources.

More precisely, the primary stage 1 comprises a primary current generator 10 (FIGS. 2 and 3), which is powered by the main source So and which delivers an alternating current I1, a current loop BC (FIGS. 2 and 3) in FIG. which circulates the alternating current I1 produced by the primary generator 10, and a plurality of windings, such as E11 and E12, connected in series in the current loop BC, each winding constituting the primary winding of a corresponding transformer, such as than T1 and T2.

According to a second specific aspect of the invention, each secondary module such as S1 and S2 comprises a winding, such as E21 and E22, forming the secondary winding of the corresponding transformer T1, T2, and a current-voltage converter CCV connected to it. secondary winding E21, E22, Finally, according to a third specific aspect of the invention, the current-voltage converter CCV is able to produce a DC output voltage, such as V1 and V2, from the alternating current such as I21 and I22. which circulates in the secondary winding such as E21 and E22.

As shown in FIG. 3, which represents the preferred embodiment of the circuit of the invention, the primary generator 10 of alternating current comprises a current regulator 11 which makes it possible to control in amplitude the current I1 flowing in the current loop BC , which will be further detailed later.

This AC primary generator 10 also comprises a resonant circuit 12, a bridge of transistors 13 and a pilot circuit 14, the resonant circuit 12 consisting for example of a capacitor C12 and an inductor L12, connected in series with one another. the current loop BC. The transistor bridge 13 comprises two pairs of opposite transistors, namely the pair 131, 133, and the pair 132, 134.

The bridge of transistors 13 is connected, by the nodes common to transistors 131, 132 on the one hand, and 133, 134 on the other hand, to the terminals of a charge storage circuit, for example constituted by one or more capacitors Q.

This capacitance Q is permanently charged to the voltage Vo by the main source of DC voltage So, to which it is connected.

The bridge of transistors 13 is also connected, by the nodes common to transistors 131, 134 on the one hand, and 132, 133 on the other hand, to the current loop BC and in particular to the series resonant circuit 12.

The driver circuit 14 delivers an output signal S14, having two phases alternately, @ 1 and @ 2, clocked at a frequency Fc and respectively applied to the pairs of transistors 131, 133, and 132, 134 to control the conduction state of these pairs of transistors.

As long as the frequency Fc is not too different from the resonant circuit resonance frequency 12, the latter is thus maintained in oscillations by the electric charges that the bridge of transistors 13, at the frequency Fc and with a polarity alternating, by pumping them at constant polarity of the charge storage circuit Q.

The current I1 which is installed in the loop BC is thus a sinusoidal alternating current, or practically sinusoidal, whose frequency can for example be chosen around 70 kHz.

As will be readily understood by those skilled in the art, the resonant circuit 12 could be simplified by suppressing the capacitance C12 and thus reduce itself to an inductance, such as L12, whose oscillations would be maintained by appropriate control of the transistors of the bridge 13 .

Although more advantageous economically, this variant however offers only lower technical performance than the illustrated solution insofar as it generates significant losses.

As shown in FIG. 3, the driver circuit 14 comprises a voltage-frequency converter CVF controlled by a control voltage Vc.

The voltage Vc, which depends on the direct voltage Vo of the main source So, is moreover controlled by the current regulator 11 whose role is to adapt the frequency Fc as a function of the current I1 flowing in the current loop BC.

More specifically, the current regulator 11 comprises a feedback loop symbolically represented by a DC voltage converter <B> 111 </ B> and by an amplifier 112 whose feedback input receives, from the converter 111, a voltage increasing with the amplitude of the alternating current I1 flowing in the current loop BC.

With this arrangement, the pumping frequency of electric charges Fc is regulated to give the amplitude of the alternating current I1 the desired value, which can also depend on the electrical energy demand of the entire circuit.

The current-voltage converter CCV of each secondary module, such as S1 or S2 (FIGS. 3 and 4), comprises a rectifier bridge PR connected to the secondary winding, such as E21 or E22 of the corresponding transformer, T1 or T2, and a capacitive circuit K.

The capacitive circuit K is connected to the secondary winding of the corresponding transformer through the rectifier bridge PR, which ensures the charging of this capacitive circuit K constant polarity. Each secondary module (FIG. 4) furthermore comprises a RGV voltage regulator whose role is to regulate in amplitude the DC output voltage, such as V1 or V2, delivered by the current-voltage converter CCV.

For example, the voltage regulator RGV is functionally constituted by a switch J which is controlled by a threshold detector DS.

The function of the threshold detector DS is to compare the charging voltage of the capacitive circuit K with a set voltage value supplied to it, such as V51, and to control the switch J in order to connect, for a flow of energy, the capacitive circuit K to the secondary winding of the corresponding transformer, through the bridge PR, when the charging voltage of this capacitive circuit K is less than the set value VS1, and so as to isolate, vis-à-vis -vis the energy flow, the capacitive circuit K of the secondary winding by short-circuiting it, when the charging voltage of this capacitive circuit K reaches the set value Vsl, the bridge PR being blocking and thus avoiding the discharge of the capacitive circuit K through the switch J closed.

As will be readily understood by those skilled in the art, the previously described arrangement of functions can be implemented by circuits of various structures.

In particular, in the case where the rectifying bridge PR is not formed or not entirely formed of diodes, contrary to what is usually the case, but at least partially consists of two transistors connected in series between the terminals of the winding secondary of the corresponding transformer, on either side of a terminal of the capacitive circuit K and operating a synchronous rectification at the frequency of the primary current, the switch J can consist of these two transistors, whose simultaneous switching to the passing state fulfills the function of closing this switch J.

In the spirit of the invention, the various secondary modules are used to supply various families of electrical energy consumption members, grouped at least according to their technology, their energy needs, and possibly their location in the field. vehicle.

For example, a 100 volt module can be provided at the front of the vehicle to power the discharge lamps; another module of 7 volts can be provided at the front of the vehicle to power the filament lamps and under hood computers; a third module of 14 volts can be provided in the passenger compartment of the vehicle to power medium power organs such as the Hi-Fi system, etc.

Given this diversity, it is in practice useful to ensure that the respective transformation ratios of the various transformers associated with the different secondary modules, that is to say the ratios of the number of turns of the primary and secondary windings of these processors differ from each other, at least some of them.

Thus, if the number of turns of the primary and secondary windings of the transformer T1 associated with the module S1 are respectively N11 and N21, and if the number of turns of the primary and secondary windings of the transformer T2 associated with the module S2 are respectively N12 and N22, For example, the ratios N11 / N21 and N12 / N22 are different from one another.

The circuit of the invention, which authorizes the use of power cables as a carrier medium for information transmission by power line, significantly optimizes the wiring of the vehicle.

In addition, by the possibility it offers to communicate to the primary stage, by carrier current, information relating to the global demand for electrical energy, the circuit of the invention opens the prospect of allowing optimization of its instantaneous efficiency. , the primary current can indeed be regulated to the correct value to deliver exactly the required power at the maximum voltage, without excess and therefore without unnecessary losses.

Claims (10)

<U> CLAIMS </ U> A power supply circuit for a motor vehicle comprising a main source (So) of DC voltage, powered by a rotating machine (AD), and at least first and second auxiliary sources (S1, S2) of voltage continuous (V1, V2) fed from the main source (So), characterized in that it comprises a primary stage (1) and at least first and second secondary modules (S1, S2) respectively constituting the first and second auxiliary sources, in that the primary stage (1) comprises a primary generator (10) of alternating current (I1) fed by the main source, a current loop (BC) in which the alternating current (I1) produced by the primary generator (10), and at least first and second windings (E11, E12) connected in series in the current loop (BC) and constituting respective primary windings of corresponding first and second transformers (T1, T 2), and in that each secondary module (S1, S2) comprises a secondary winding (E21, E22) of the corresponding transformer (T1, T2) and a current-voltage converter (CCV) connected to this secondary winding (E21, E22). ), this current-voltage converter (CCV) being adapted to produce a DC output voltage (V1, V2) from the alternating current (I21, I22) flowing in the secondary winding (E21, E22) ' Power supply circuit according to Claim 1, characterized in that the AC primary generator (10) comprises a current regulator (11) capable of controlling in amplitude the current (I1) flowing in the current loop ( BC). Power supply circuit according to one of Claims 1 and 2, characterized in that the AC primary generator (10) comprises a resonant circuit (12) connected in series in the current loop (BC) and maintained in oscillation by pumping electrical charges taken at a determined frequency (Fc) on a charge storage circuit (Q) connected to the main source (Sa) of DC voltage. The power supply circuit according to any of the preceding claims combined with claim 3, characterized in that the AC primary generator (10) comprises a transistor bridge (13) and a driver circuit (14), the transistor bridge (13) being connected to the charge storage circuit (Q) and the resonant circuit (12) for transferring to the resonant circuit (12) the electrical charges taken from the charge storage circuit (Q), and each pair transistors (131,133; 132,134) of the transistor bridge (13) adopting a cyclically variable conduction state controlled by an output signal (S14) of the driver circuit (14) having the determined frequency (Fc). 5. Power supply circuit according to claims 2 and 4, characterized in that the driver circuit (14) comprises a voltage-frequency converter (CVF), controlled by a control voltage (Vc) depending on the DC voltage (Vo). ) of the main source (So), for outputting the output signal (S14) at the determined frequency (Fc), and in that the current regulator (11) comprises a feedback loop (11, 112) suitable for modifying the control voltage (Vc) of the voltage-frequency converter (CVF) as a function of the current (II) flowing in the current loop (BC). 6. Power supply circuit according to any one of the preceding claims, characterized in that each secondary module (S1, S2) comprises a voltage regulator (RGV) adapted to regulate in amplitude the DC output voltage (V1, V2). ) of the current-voltage converter (CCV). Electrical supply circuit according to one of the preceding claims in combination with claim 6, characterized in that the current-voltage converter (CCV) comprises a rectifier bridge (PR) connected to the secondary winding (E21, E22). ) of the transformer (T11 T2), and a capacitive circuit (K) connected to the secondary winding (E21, E22) by an electrical connection through the bridge rectifier (PR), this bridge rectifier (PR) charging this capacitive circuit ( K). Electrical supply circuit according to one of the preceding claims in combination with claim 7, characterized in that the voltage regulator (RGV) comprises a threshold detector (DS) comparing the charging voltage of the capacitive circuit (K ) at a predetermined voltage value (V51, V52), and switching means (J) controlled by the threshold detector (DS) for selectively short-circuiting the secondary winding (E21, E22) when the charging voltage of the Capacitive circuit (K) reaches the predetermined voltage value (V511 V52) 9. Power supply circuit according to any one of the preceding claims, characterized in that the first and second transformers (T11 T2) have respective transformation ratios (N11 / N21; N12 / N22), which differ from each other. the other. 10. Power supply circuit according to any one of the preceding claims combined with claim 3, characterized in that the charge storage circuit (Q) comprises at least one capacitor.