FR2983365A1 - Power supply system for supplying power to battery of electric car, has transistor modulating current intensity of inductor coil so that average value of modulated current intensity is equal to value of reference current - Google Patents

Abstract

The system has a rectifier (RED) rectifying a current supplied from a single phase electrical network, and an inductor (L) receiving the rectified current (IRED) supplied by the rectifier. A conversion stage includes a transistor (TBCK) to pulse width modulate a current (IL) supplied to a coil of the inductor to control the rectified current. The transistor modulates the current intensity of the coil so that the average value of the modulated current intensity is equal to the value of a reference current having the shape of a sinusoid in phase with a rectified input voltage of the system.

Description

The invention relates to a system for transferring electrical energy, and in particular between a single-phase electrical network and a battery. In particular, the system is intended to be integrated in an electric motor vehicle, the traction machine is powered by the battery to be charged via an inverter. In the state of the art, for charging electric vehicle batteries from an electrical network, for example single-phase, two types of chargers are used, namely insulated chargers and uninsulated chargers. The insulated chargers contain an insulating element, for example a transformer which isolates the vehicle power supply network from the electrical network from which the vehicle battery is charged. Thus, common mode disturbances are limited. However, these chargers are expensive and their energy efficiency is low. This is due to the addition of the isolation element which involves an electronic circuit whose topology is more complex. Uninsulated chargers have the main advantages of cost and energy efficiency. An example of this type of uninsulated charger is described in document FR2943188. This charger has the characteristic of being able to be used with a three-phase electrical network or with a single-phase electrical network. It comprises a rectifier stage intended to be connected to a power supply network and an inverter stage intended to be connected to the battery. This charger further comprises means for regulating the average current from the rectifier stage around a current value produced from the maximum current supplied by the supply network and as a function of a coefficient at least equal to one ratio between the maximum voltage rectified by the rectifier stage and the voltage of the battery. It is known from FR2762721 a battery charger from an AC voltage comprising an intermediate inductance and two switches. One of the switches is placed on the electrical network side and the other is located on the battery side. This allows a command of the "buck boost" type according to an Anglo-Saxon term well known to those skilled in the art. That is to say, only one of the switches switches at a time, either on the network side when the network voltage is greater than the battery (buck), or on the battery side when the battery voltage becomes higher than that of the network (boost). Thus, the intermediate inductance is used as storage element of the electrical energy. However, this use involves a voluminous and expensive intermediate inductance. On the other hand, in this charger, all components are dedicated for charging the battery. It is not intended to use for charging electrical components which are initially dedicated for another function, for example traction.

It is known from US5500579, a charging solution that reuses the transistors of the variable speed drive of a DC machine. For this, this solution includes contactors for reconfiguring the load circuit in traction. However, these contactors are very unreliable. In addition, the charging solution plans to reuse components of a DC machine. However, DC machines are very rarely used in electric traction for modern electric motor vehicles. It is known from document DE4107391, a charging means with shared components but which can only work if the rectified voltage of the network is permanently lower than that of the battery. In addition, the charging means described in DE4107391 use contactors. It is known from WO2010089071, a charging solution using a three-phase network. It offers the possibility to reuse the motor coil and a part of the inverter for charging. However, as it stands, this solution does not provide a control mode to reduce the number of components required for the function PFC (power factor correction).

In particular, this document requires a diode D1 at the level of the transistor S making it possible to regulate the current in the winding L. This regulation mode does not allow the use of the charger described in this document on a public power supply network, subject to a jig strict entry. More generally, not to disturb the electrical network, all these charging solutions must draw an intensity that respects a certain harmonic template. In general, this template is defined by a high band whose fundamental is a sinusoidal intensity which is in phase with the voltage of the electrical network. In the state of the art, to regulate the current drawn from the electrical network by following this template, the output current of the rectifier is slaved around a coil current setpoint, this current flowing through the coil.

In view of the foregoing, the invention proposes a simple uninsulated charge solution, which can adjust the charging power and which can charge a battery even if its voltage is lower than that of the power grid. According to one embodiment, an economical charging solution is proposed which makes it possible to reuse components dedicated to other functions. According to one embodiment, there is provided a charging solution which draws on the network a current which follows the current template mentioned above.

In one aspect, a power system for a battery is defined from an electrical network comprising: a current rectifier fed from the network; and an inductance coil receiving the rectified current delivered by the rectifier; a first conversion stage comprising a first switching means adapted to modulate in pulse width the current delivered to the coil so as to regulate the rectified current; and means for regulating the current delivered to the coil.

According to a general characteristic, the first switching means is adapted to modulate the intensity of the coil so that the average value of the modulated intensity of the coil is equal to the value of a first current setpoint, said first current setpoint in the form of a sinusoid rectified in phase with the input voltage of the system. Two regulations are thus proposed. A first regulation uses the first conversion stage to regulate the output intensity of the rectifier. The other regulation uses the regulating means to regulate the intensity through the coil. It is thus possible to easily and effectively control the intensity taken from the electrical network. It is thus possible with this power system to easily draw from the power grid an intensity in the template mentioned above using the pulse width modulation.

According to one embodiment, the system comprises a load manager capable of adjusting the amplitude of the first current setpoint according to the needs of the battery. Thus, it is possible to continuously adjust the power delivered by the charger according to the needs of the battery. For example if the temperature of the battery reaches a certain threshold, we will limit the load power. According to one characteristic, the electrical energy transfer system comprises between the inductance coil and an output of the system, a second conversion stage comprising a second switching means adapted to modulate in pulse width the voltage across the second switching means for regulating the output intensity. The second conversion stage allows adjustment of the coil current, which consequently adjusts the current in the battery. In addition, the adjustment of the current of the coil is made according to the voltage of the battery used. It is no longer necessary to limit the use of the charger to batteries whose voltages are higher than that of the electrical network.

According to another characteristic, the second switching means is adapted to modulate the voltage at its terminals by samples so that for each sample the average value of the modulated voltage across the second switching means is equal to the output voltage of the system. . For example, this modulation can be performed by pulse width modulation. According to yet another characteristic, the regulating means comprises means for measuring the intensity of the coil, means for comparing the intensity of the coil with a second current setpoint and control means capable of controlling the voltage. of the coil. Thus, it is possible to regulate the current flowing through the coil. According to an additional characteristic, the second current setpoint has a DC component whose value is dependent on the battery voltage-to-effective voltage ratio at the output of the rectifier, and the power transferred from the network to the battery. The current of the coil is distributed to the rectifier according to a modulation strategy (pulse width modulation type) which follows this current setpoint. This allows to draw the network intensity in the template mentioned above. According to another additional characteristic, the measuring means comprise a means for filtering the intensity of the measured coil.

Thus, short-term fluctuations in coil current can not be taken into account in order to regulate the intensity of the coil. According to one embodiment, each of the first and second conversion stages comprises a diode and the first and second switching means are transistors having an on state or a blocking state. Thus, according to this embodiment, the first and second conversion stages are easily achievable. According to one characteristic, the system comprises an inverter between the output of the system and the coil, said inverter comprising at least one branch, comprising at least one diode and one transistor, the diode and the transistor of the second conversion stage being formed by the diode and the transistor of said at least one branch of the inverter.

Thus, it is not necessary to add components for the second conversion stage. We can reuse those of the inverter. This allows a substantial reduction in the cost of the transfer system. According to an example of application, the electrical network is a single-phase electrical network. According to another embodiment, the battery is connected to an electric traction machine, said electric machine having a stator inductance and said stator inductance is used as a means of filtering the intensity of the coil.

Thus, this filtering means is added to the coil and it is possible to filter the coil current before it is delivered to the battery without any additional cost since part of the stator inductance used is normally dedicated to the machine. electric. According to another example of application, for an inverse topology (as described in FIG. 6) in which the output of the system is connected to a photovoltaic generator which supplies a direct current, it is possible to generate power in the alternative network from a continuous source. This would apply, for example, to the connection of photovoltaic panels to the network via this type of converter. Other advantages and characteristics of the invention will appear on examining the detailed description of embodiments, in no way limiting, and the attached drawings, in which: FIG. 1 schematically illustrates an uninsulated loader according to a first Embodiment of the Invention - Figure 2 schematically illustrates a non-insulated loader according to a second embodiment of the invention; - Figure 3 schematically illustrates the components of an input filter; FIG. 4 schematically illustrates the current regulation of the charger coil of FIG. 1; FIG. 5 schematically illustrates a charger according to the invention connected to an electrical machine; FIG. 6 illustrates a charger according to FIG. The invention operates as a generator on an AC network from a DC source. FIG. 1 represents a charger for a single-phase electrical network according to the invention. This charger is for example intended to be incorporated into a motor vehicle. It allows the charging of the battery used to power the traction machine of the vehicle, this battery being used to power the traction machine. This charger comprises successively an input E comprising two input terminals intended to be connected to a single-phase power RES (to which is added a ground not shown), an input filter FIE, a differential capacitance Cdiff, a rectifier RED, a transistor TBCK, a diode D1, a coil L, a transistor TBST, a diode D2 and an output S comprising two output terminals intended to be connected to a battery BAT. The current IL through the coil is controlled by a first regulating means shown in Figure 4 acting on the voltage VL across the coil. The diode D1 and the transistor TBCK form a first conversion stage. Diode D2 and transistor TBST form a second conversion stage. The operation of the first conversion stage is explained below. The current IRED at the output of the rectifier is directly derived from the switching of the current IL by the transistor TBCK. Indeed, if the transistor TBCK is blocked then the current IRED is zero whereas if the transistor TBCK is passing then the current IRED is equal to the current of the coil IL. This switching is controlled by a switching control means CM1 of the transistor TBCK and is carried out in pulse width modulation. More precisely, for each modulation period of the first conversion stage, the current IL is compared with a setpoint C IRED. Where: C IRED = abs (VRES) - A, equation in which "abs" corresponds to the absolute value operation and A is a coefficient that expresses the amplitude of the network current to be absorbed. The coefficient A comes directly from a requested power demand.

Depending on the relative value of the current IL and the setpoint C IRED, a time is determined within the modulation period during which the transistor must be on. For example, if the set point C IRED is equal to 40 amperes and the current IL is equal to 100 amps, then in the case where the modulation period is equal to 20 microseconds, the duration during which the transistor TBCK is conducting is: 20. 40% = 8 microseconds. The control means then switches into an on state of the TBCK transistor during this time. In other words, the current IL is modulated so that the average value of the rectifier output current IRED is equal to C IRED. This operation is repeated for each of the modulation periods of the first successive conversion stage. As an exemplary embodiment, the first modulation period of the first conversion stage has a value of 20 microseconds. Any other value could be chosen, preferably less than one second (International System Unit). Preferably, the duration during which the transistor must be on is in the middle of the modulation period of the first conversion stage.

At the end of the successive switching of the transistor TBCK, we obtain "IRED = alphaBCK. IL ", with alphaBCK, the duty cycle applied to transistor BCK. Preferably, the setpoint C IRED is chosen so that the current delivered by the IRES network follows the previously mentioned template. For this reason, since the current IRED is equal to the absolute value of the current of the IRES network (neglecting the impedance of the input filter FIE), it suffices that the setpoint C IRED follows a sinusoid rectified in phase with the voltage provided by the VRES network. According to one embodiment, the charger further comprises a charge manager GC capable of continuously adjusting the amplitude of the current setpoint C IRED according to the needs of the traction battery. For example, the GC manager adjusts the amplitude of the setpoint C IRED as a function of the temperature or the charge level of the battery. The operation of the second conversion stage formed by the transistor TBST and the diode D2 is explained below. The value of the voltage VL across the coil is known because it is fixed by the first regulation means (FIG. 4). The value of the voltage VRED output of the rectifier is also known because in first approximation it is equal to the absolute value of the voltage of the VRES network where it can easily be measured by a voltage sensor at the output of the rectifier RED. Finally, the voltage VKN at the terminals of the diode D1 is equal to the voltage VRED when the transistor TBCK is on and is zero when TBCK is off. It is therefore possible to deduce, by mesh law, the value of the voltage VBST across the terminals of the transistor TBST by the relation: VBST = -VL + VKN in which VKN denotes the voltage across the diode D1. The IBAT current supplied to the battery BAT is directly derived from the switching of the voltage VBST by the transistor TBST. When the transistor TBST is on, then the current IBAT is zero, when the transistor TBST is blocked then the current IBAT is equal to the current of the coil IL. The switching of the transistor TBST is controlled by a switching control means CM2 of the transistor TBST and is carried out in pulse width modulation. This switching is similar to that of the first conversion stage. With the difference that in the second conversion stage, it is the voltage VBST which is modulated in pulse width while in the first conversion stage it is the current IL which is modulated in pulse width. For each modulation period of the second conversion stage, the voltage VBST is compared with the measured voltage VBAT across the battery. According to their relative value, a duration is determined within the modulation period during which the transistor TBST must be on so that the average voltage VBST during the modulation period is equal to VBAT. The control means then ensures switching in an on state of the TBST transistor during this time. In other words, the voltage VBST is modulated so that its average value is equal to VBAT (neglecting the voltage drop due to the resistance of the coil L).

This operation is repeated for each of the modulation periods of the second conversion stage succeeding one another. As an exemplary embodiment, the modulation period of the second conversion stage is 20 microseconds. Any other value could be chosen, preferably less than one second (International System Unit). Preferably, the duration during which the transistor TBST must be on is in the middle of the modulation period. At the end of the successive switching of the transistor TBST, we obtain: VBST = (1-alphaBST). VBAT and IBAT = (1-alphaBST). IL, with alphaBST, the duty cycle applied to the TBST transistor. FIG. 2 represents a charger for a single-phase electrical network according to a second embodiment of the invention. In the system of FIG. 2, the input E, the input filter FIE, the differential capacitance Cdiff, the rectifier RED, the transistor TBCK, the diode D1, the coil L, the transistor TBST, the diode D2 are found in the system of FIG. and an output S comprising two output terminals intended to be connected to a BAT battery. Moreover, the operating principle of the first and second conversion stages is identical to that explained for FIG. 1. The charger of FIG. 2 differs from that of FIG. 1 in that the diode D2 and the transistor TBST used by FIG. the second conversion stage are normally dedicated to an OND UPS. The OND inverter is generally polyphase. For example, in the case of an inverter intended to supply a three-phase traction machine, the inverter is three-phase and comprises three branches and a capacitance Cond which allows a battery-side filtering of the current IL. According to an embodiment well known to those skilled in the art, each of these branches comprises two transistors each being in parallel with a diode. Among the diodes and transistors of the first branch of the OND inverter, the diode D2 and the transistor TBST will be used to produce the second conversion stage previously described. Figure 3 illustrates an embodiment of the FIE filter. The FIE filter comprises a CT connector, a common mode inductance TRIE between the phase and the neutral, two capacitors CIE1 and CIE2 between the earth and the neutral and between the earth and the phase respectively, and on the branch of the phase a coil LEL in parallel with RIE resistance. The FIE filter in combination with the capacitance Cdiff (FIG. 1) allows the network side: a filtering in differential mode to eliminate the harmonics due to the switching of the TBCK transistor, in particular. a common mode filtering to limit the current in the ground wire resulting from the switching of parasitic capacitances (traction machine, battery), the chassis of the electric vehicle being connected to the ground.

Figure 4 shows the IL current regulating means of the coil L of the charger. The set point C IL is compared with the current IL measured and filtered, the measurement of the current IL being carried out by a sensor and the filtering by MF filtering means.

Depending on the difference between these two values, a regulator MC adjusts the voltage VL across the coil L. The regulating means is therefore a control loop, since the voltage VL influences the current IL.

According to one embodiment, the current setpoint C IL has a DC component whose value is dependent on the battery voltage VBAT ratio on effective voltage at the output of the rectifier VRED eff, and the power transferred from the network to the battery. Figure 5 shows a charger for an electrical network according to the invention. In the system of FIG. 5, the input E, the input filter FIE, the differential capacitance Cdiff, the rectifier RED, the transistor TBCK, the diode D1, the coil L, the transistor TBST, the diode D2 are found in the system of FIG. , the OND inverter and an output S comprising two output terminals intended to be connected to a battery BAT. Moreover, the operating principle of the first and second conversion stages is identical to that explained for FIG. 1. The charger of FIG. 5 differs from that of FIG. 2 in that it comprises an electric three-phase traction machine. EMAIL. The MEL machine has three arms, each corresponding to one phase. Each of the arms of the electric machine has a stator inductance. According to this embodiment, the stator inductance MF2 of one of the arms of the MEL machine is used as a filtering means which is added to the coil L. This gives a filtered coil intensity to be applied, after passing through the second conversion stage, BAT battery. Figure 6 illustrates a charger according to the invention connected to a continuous source. In the system of FIG. 6, the input E, the input filter FIE, the differential capacitance Cdiff, the rectifier RED, the transistor TBCK, the diode D1, the coil L, the transistor TBST, the diode D2 are found in the system of FIG. and an output S comprising two output terminals. Moreover, the operating principle of the first and second conversion stages is identical to that explained for FIG.

The charger of FIG. 6 differs from that of FIG. 1 in that the output S is connected to a DC voltage source GEN which supplies an IGEN current and whose voltage at its terminals is VGEN. Thus, at the input of the system it is no longer an IRES debit current but a supplied current IRESF. The operating principle of the two conversion stages is identical to that illustrated in the preceding figures by taking IRESF = -IRES and IGEN = -IBAT. It is possible with this system to transfer electrical energy from a continuous source to the power grid. For example, the continuous source is a GEN photo generator. According to the invention, it is proposed to precisely adjust the IRES intensity of the network a double regulation, the intensity IL and the intensity IRED. A command was thus made which acts on the two cyclic ratios alphaBST and alphaBCK to respectively control the IBAT current supplied to the battery and the current IRED taken from the network. The only constraint lies on the intensity IL which must be greater than IRED and IGEN or IBAT. According to the invention, a number of weak sensors is also used since it is necessary to measure only three values: the voltage VRES, the voltage VGEN or VBAT and the current IL.

Claims (12)

REVENDICATIONS1. A battery power system (BAT) from an electrical network (RES) comprising: - a rectifier (RED) of current supplied from the network; an inductance coil (L) receiving the rectified current delivered by the rectifier; a first conversion stage comprising a first switching means (TBCK) adapted to modulate in pulse width the current delivered to the coil (IL) so as to regulate the rectified current (IRED); and a means for regulating the current delivered to the coil (IL), characterized in that the first switching means (TBCK) is adapted to modulate the intensity of the coil (IL) so that the average value of the modulated intensity of the coil is equal to the value of a first current setpoint (C IRED), said first current setpoint (C IRED) having the shape of a sinusoid rectified in phase with the input voltage of the system. 2. System according to claim 1, comprising a load manager (GC) capable of adjusting the amplitude of the first current setpoint (C IRED) according to the needs of the battery (BAT). 3. System according to claim 1 or 2, comprising between the inductor (L) and an output of the system (S), a second conversion stage comprising a second switching means (TBST) adapted to modulate in width of pulse the voltage across the second switching means (TBST) so as to regulate the output intensity (IBAT, IGEN). 4. System according to claim 3, wherein the second switching means (TBST) is adapted to modulate the voltage (VBST) at its terminals by samples, so that for each sample, the average value of the voltage modulated at the terminals. the second switching means (TBST) is equal to the output voltage of the system (VBAT, VGEN). 5. System according to any one of claims 1 to 4, wherein the regulating means comprises means for measuring the intensity of the coil, means for comparing the intensity of the coil with a second current setpoint. (C IL) and control means (MC) capable of controlling the coil voltage (VL). 6. System according to claim 5, wherein the second current setpoint (C IL) has a DC component whose value is dependent on the battery voltage ratio (VBAT) on the output voltage of the rectifier (VRED eff), and the power transferred from the network (RES) to the battery (BAT). 7. System according to claim 5 or 6, wherein the measuring means comprise a filtering means (MF) of the intensity of the measured coil. 8. System according to any one of claims 3 to 7, wherein each of the first and second conversion stages comprises a diode (D1, D2) and the first and second switching means (TBCK, TBST) are transistors having a passing state or a blocking state. 9. System according to claim 8, comprising an undulator (OND) between the output of the system (S) and the coil (L), said inverter comprising at least one branch comprising at least one diode (D2) and a transistor (TBST). , the diode (D2) and the transistor (TBST) of the second conversion stage being formed by the diode (D2) and the transistor (TBST) of said at least one branch of the inverter (OND). 10. System according to any one of claims 1 to 9, wherein the network is a single-phase electrical network (RES). 11. System according to any one of claims 1 to 10, wherein the battery (BAT) is connected to an electric traction machine (MEL), said electric machine having a stator inductance (MF2) and said stator inductance is used as means of filtering the intensity of the coil. 12. System according to any one of claims 1 to 9, wherein the output of the system is connected to a photovoltaic generator (GEN) which supplies a direct current (IGEN).