FR2701176A1 - System for checking the charging of the batteries of an electrical apparatus such as a vehicle - Google Patents

Abstract

System for charging batteries (10) of an electric vehicle (2). An earth wire (6) of the power supply cable (3) is used, linking the charging terminal (1) to the vehicle (2). A resonant circuit (12) which excites a central unit (16) is arranged in the vehicle (2), and sends its resonances back into the earth wire (6). The central unit (16) detects them and thus checks the presence of the vehicle (2) and the continuity of the earth wire (6). Applicable to electrically propelled vehicles.

Description

BATTERY CHARGING CHECK SYSTEM
OF AN ELECTRICAL APPARATUS SUCH AS A VEHICLE
DESCRIPTION
The invention relates to a system for verifying the charging of the batteries of an electric appliance such as an electrically propelled vehicle, the advantage of which is to offer the assurance that the charging is done in good conditions.

 Communication systems between motor vehicles and fixed stations have already been designed for guidance, tolling or other functions, but which use often complicated elements to transmit information or provide dialogues which are complicated. also. In the invention, we are only concerned with verifying the actual presence of a vehicle during charging of the batteries, the continuity of the ground wire of the power cable and possibly the absence of leakage current, using as much as possible. the elements necessary for loading to ensure these functions also, in order to increase only very little the cost of installation.

 The system therefore comprises a terminal for supplying electric current to the batteries of the electrical appliance by a cable with two phase wires and a ground wire; it is characterized in that the terminal comprises a means of supplying an excitation on at least one of the phase wires and of detecting a response current on the ground wire, a resonant circuit being arranged on the apparatus between the phase wire which undergoes excitation and the ground wire.

 These means are sufficient to ensure the presence of the device and the continuity of the ground wire. In the event of an anomaly, it is then easy to have the interruption of the supply controlled by an action of the means of supplying the excitation and of detecting the response current on a breaking means belonging to the differential circuit breaker provided in the current designs of power terminals.

Advantageously, the transformer of this differential circuit breaker is connected to the means for supplying the excitation and for detecting the response current and constitutes the channel through which the excitation is introduced into the phase wire.

 A means for detecting direct leakage currents may comprise as sensitive element means such as a magnetic field sensor disposed on the transformer of the earth leakage circuit breaker; it may be an additional winding wound around the core of the transformer. We can see how the propositions that here allow a close cohesion of the elements of the power supply terminal, many of which serve several very different functions at the same time.

 A good means of detecting the response current is able to determine whether this current and the excitation are signals in phase or in quadrature, in order to best identify the resonant frequencies.

The invention will now be described in more detail with the aid of the following figures, which are given by way of illustration and not limitation.
FIG. 1 is a diagram of the system,
FIG. 2 illustrates certain details of the system,
FIG. 3 illustrates the main elements of the control means,
FIG. 4 represents the frequency response of the resonant circuit,
- And Figure 5 some signals obtained during the operation of the system.

 The system, first described with the aid of FIG. 1, is made up at first analysis of a terminal 1 of electrical supply, of a vehicle 2, and of a cable 3 which unites them. This cable 3 is a conventional three-wire cable including two phase wires 4 and 5 and a ground wire 6, and it is engaged in respective sockets 7 and 8 of the terminal 1 and of the vehicle 2 beyond which the wires 4, 5 and 6 are extended. In vehicle 2, the phase wires 4 and 5 lead to a charger 9 connected to the propulsion batteries 10 of the vehicle 2 by pairs of conductors 11 and which aims in particular to convert alternating current into direct current. The vehicle 2 also comprises a resonant circuit 12 disposed between one of the phase wires 5 and the ground wire 6. As for terminal 1, it comprises the alternating current source 13 (in reality a connection to the electrical sector), which is connected to the phase wires 4 and 5 by the movable contacts 14 of a relay, the coil 15 of which is controlled by a central unit 16 at the terminals of which are connected a first transformer 17 and a second transformer 18 which connect it respectively to the phase 4 and 5 wires and earth wire 6.

 We see in Figure 2 that the first transformer 17 is formed of four coils arranged around a single circular core: two of the coils are located on the two phase wires 4 and 5, the other two are respectively connected to a loop d excitation 19 and a detection loop 20 of the central unit 16. As for the resonant circuit 12, it is composed of several assemblies mounted in parallel - two in the present case - each of which includes a self-induction coil 22 and a capacitor 23 arranged in series between the phase wire 5 and the ground wire 6. Finally, there is a protective component 24 disposed on the phase wires 4 and 5 upstream of the charger 9 in order to reduce the influence of the latter on the resonant circuit 12. The protection component 24 is composed of two self-induction coils 25 and 26 each located on one of the phase wires 4 and 5 and which have the property of a high impedance at the resonance frequencies of the circuit 12. Finally, a capacitor 27 is disposed between the phase wires 4 and 5 and serves as a filter.

FIG. 4 represents the intensity of the signal from the resonant circuit 12 - after being emitted from
The excitation loop 19 and having passed through the first transformer 17 and the phase wires 4 and 5 - and transmitted over the ground wire 6 as a function of the frequency. There are two resonance peaks at frequencies f1 and f2 separated by ranges where the response is much weaker and which have minima at frequencies fa, fb and fc.

 We now pass to FIG. 3: the central unit 16 essentially consists of a microprocessor 28 responsible for detecting the normal operating state of the system. It comprises a first output 29 through which the excitation current from the relay coil 15 is sent; as well as a second output 31 which transmits an excitation signal to a clock 32 and then, via an amplifier 33, to the excitation loop 19, and to multiplexers 37 and 38 which will now be described.

 The microprocessor 28 is coupled to a synchronous demodulator 34 connected to the second transformer 18 and which successively comprises towards the microprocessor 28 a preamplifier 35, an inverter 36 and, in parallel, a multiplexer at 900 37 and a multiplexer at 0 38, all of which are two connected to both the output terminals of the preamplifier 35 and the inverting amplifier 36. The multiplexers 37 and 38 are connected to respective inputs 39 and 40 of the microprocessor 28. This system allows more precise detection.

 Figure 5 helps to understand why. First of all, there was the signal 50 from the resonant circuit 12, the ground wire 6 and the second transformer 18, whose frequency is that of excitation and whose intensity depends on the frequency as we have seen in connection with FIG. 4. The signal 51 emitted by the clock 32 towards the amplifier 33 and the OC multiplexer 38 is shown below; it is in phase with the excitation signal and at the same frequency. The signal 50 is more or less out of phase with respect to the signal 51, which is used to control the multiplexer at OO 38 and make it send to the microprocessor 28, according to the 'positive or negative alternation, the signal from the preamplifier 35 or the inverter 36; which implies that if the signals 50 and 51 are in phase, the signal 52 that the microprocessor receives will be well rectified, is always positive; if the signals 50 and 51 are in phase opposition, the signal 52 will always be negative; if they are in quadrature, the average of signal 52 will be zero; and the signal average will be intermediate for the intermediate phase shifts.

 The signal 53 shown below is that which is sent to the multiplexer at 900 37; it is a signal similar to signal 51 but with a phase delay of a quadrature. The signal 53 controls the multiplexer at 900 37 as the signal 51 controls the multiplexer at 0 38, and another signal 54 is received accordingly by the microprocessor 28.

 The interest of this device appears as soon as we remember that the response signal is in quadrature with the excitation signal at a resonance, and in phase with it (or in phase opposition) at the frequencies where the contributions of the modes own resonance are the least sensitive: the signal 52 delivered to the input 40 is thus null at the frequencies f1 and f2, and the signal 54 delivered to the input 39 is null at the frequencies fa, fb and fc. The microprocessor 28 is of course capable of integrating the signals 52 and 54. It suffices that it produces signals at frequencies fa, f1, fb, f2 and fc for short periods at terminal 31 and integrates signals 52 and 54 at inputs 40 and 39 so that the detection is made of the presence of vehicle 2 and of the continuity of the ground wire 6. One could of course conceive explorations on wider frequency bands if one wanted for example to seek the identification of 'a vehicle 2 endowed with a particular signature - thanks to its own resonant circuit 12 - among other vehicles 2. Anyway, the microprocessor 28 authorizes the closing of the relay contacts 14 if the search has been successful and keeps them open otherwise, and it continues to monitor the signals 52 and 54 during the charging of batteries 10 to open the relay contacts 14 as soon as these signals no longer correspond to those which were previously programmed ieurement - that the resonant circuit 12 should emit in response to an excitation of the mains current, which is achieved if the operation of the source 13 becomes abnormal or if the vehicle 2 is disconnected.

 The microprocessor 28 has a last input 41, coupled to a leak detection module 42 which comprises, from the detection loop 20 to this input 41, a preamplifier 43, an inverter 44 and a multiplexer 45 connected to the output terminals of the preamplifier 43 and of the inverter 44. The multiplexer 45 is controlled like the OC multiplexer 38 by the signal 51 from the clock 32 and operates in the same way.

 The leak detection module 42 is intended for the detection of direct leakage currents.

Indeed, the alternating leakage currents are well detected by a differential circuit breaker similar to those which equip domestic electrical installations and which includes in particular the windings of the first transformer 17 which are connected to the phase wires 4 and 5 and the compound relay contacts 14 and coil 15: the latter is directly excited to open these as soon as the resulting magnetic field or differential generated on the two coils mentioned exceeds a threshold, which means that a difference in current intensity excessive exists between the phase wires 4 and 5, because otherwise the differential magnetic field is zero. However, the differential circuit breaker is insensitive to direct leakage currents, which justifies the addition of the leakage detection device 42. The sensitive element of the detection loop 20 is an additional winding wound around the core of the first transformer 17, which '' could probably be replaced by another magnetic field sensor such as a Hall effect sensor. Indeed, a continuous leakage current creates a saturation magnetic field in the core, which reduces the efficiency of the signal transfer between the excitation 19 and detection 20 loops.

 The synchronous demodulation means 43 to 45 used for the detection of the direct leakage current have the advantage of reducing the influence of the parasites, which are often at a high level in these situations and therefore risk disturbing the measurements.

 The inventor also plans to have DC leakage currents detected directly by analyzing the disturbances they would produce on the current from the resonant circuit 12.

 The microprocessor 28 can be programmed to subtract the noise from the measurements, after having recorded it just before the latter.

 It can be seen from the above description that vehicle 2 could be replaced by another electrical appliance equipped with batteries to be recharged.

Claims (9)

 1. Battery charging system (10) of an electrical appliance (2) comprising an electric power supply terminal (1) connected to the batteries (10) of the appliance by a cable (3) with two wires of phase (4, 5) and a ground wire (6), characterized in that the terminal (1) comprises means (16) for supplying an excitation on at least one of the phase wires and for detecting a response current on the ground wire (6), a resonant circuit (12) being arranged on the apparatus between the phase wire which undergoes excitation and the ground wire.  2. System according to claim 1, characterized in that the ground wire is united by means of supply of the excitation and detection of the response current by a transformer (18).  3. System according to claim 1 or 2, characterized in that the resonant circuit is complex and formed of several parallel sets of coils (22) and capacitors (23) having resonances at different frequencies (wire, f2).  4. System according to any one of claims 1 to 3, characterized in that it comprises a detection means (42) of continuous leakage currents.  5. System according to any one of claims 1 to 4, characterized in that the means for supplying the excitation and for detecting the response current is united to the phase wire which undergoes excitation by another transformer (17 ), which belongs to a differential circuit breaker with a means of cutting the power supply (14, 15).  6. System according to claim 5, characterized in that the means for cutting off the power supply (14, 15) is connected to the means for supplying the excitation and detecting the response current, which is designed to control the means. switch (14, 15) to cut off the power supply without the action of the RCD.  7. System according to claims 4 and 5, characterized in that the means for detecting direct leakage currents comprises a magnetic field sensor disposed on the other transformer (17).  8. System according to claim 7, characterized in that the magnetic field sensor is a coil wound around the core of the other transformer.  9. System according to any one of claims 1 to 8, characterized in that the means for supplying the excitation and for detecting the response current comprises means (35, 36, 37) for determining whether the excitation and the current response signals are quadrature signals.