FR3063851A1 - DEVICE FOR SWITCHING AN EXCITATION CURRENT OF AN ELECTRIC MACHINE EQUIPPED WITH A ROTOR - Google Patents

Abstract

A switching device (200) for switching the electric excitation current of an electric machine with an excitation winding (16) and comprising: - a main switching unit (22) having a main switch (22c) for connecting the first terminal (16a) of the excitation winding (16) at the first pole of a voltage source (11), the main unit (22) switching the excitation current of the source (11) to the excitation winding (16), and an auxiliary switching unit (24) with a first auxiliary switch (24d) for connecting the second terminal (16b) of the excitation winding (16) to the first pole of a source voltage auxiliary (34), the second pole of which is connected to the second pole (30) of the voltage source (11).

Description

Holder (s): SEG AUTOMOTIVE GERMANY GMBH.

Extension request (s)

Agent (s): CABINET HERRBURGER.

DEVICE FOR SWITCHING AN EXCITATION CURRENT OF AN ELECTRIC MACHINE EQUIPPED WITH A ROTOR.

FR 3 063 851 - A1 (57) Switching device (200) for switching the electric excitation current of an electric machine with an excitation winding (16) and comprising:

- a main switching unit (22) comprising a main switch (22c) for connecting the first terminal (16a) of the excitation winding (16) to the first pole of a voltage source (11), the unit main (22) switching the excitation current from the source (11) to the excitation winding (16), and an auxiliary switching unit (24) with a first auxiliary switch (24d) for connecting the second terminal ( 16b) from the excitation winding (16) to the first pole of an auxiliary voltage source (34), the second pole of which is connected to the second pole (30) of the voltage source (11).

Field of the invention

The present invention relates to a device for switching the excitation current of an electric machine with an excitation winding, in particular for generators of motor vehicles.

State of the art

Vehicles generally have an on-board network supplied with voltage by an electric machine operating as a generator, for example a synchronous machine with external excitation. To regulate the voltage of the on-board network, the generator excitation current can be controlled or regulated. The generator is generally connected to the on-board network by a rectifier (with diodes and semiconductor switches constituting the rectifier elements). As generators of the type defined above often have a high inductance in the electric field and thus a significant time constant for regulation, it would be desirable to be able to modify the excitation current as quickly as possible if necessary, this is that is, to increase or decrease it. This is why it would be desirable to have a higher voltage as the on-board network voltage. For this, circuits with diodes and transistors have been used which, however, occupy an important place in a generator or circuit regulator compared to the space available, for example, on a chip.

Document US Pat. No. 8,008,895 B2 describes a generator regulator which makes it possible to increase the excitation voltage by applying a negative potential to a terminal of the excitation winding by a capacitor.

Presentation and advantages of the invention

The present invention relates to a switching device for switching an electric excitation current of an electric machine with an excitation winding comprising a main switching unit comprising a main switch for connecting a first terminal of the winding excitation to a first pole of a voltage source, the main switching unit switching the excitation current from the voltage source to the excitation winding, an auxiliary switching unit with a first auxiliary switch for connecting a second terminal of the excitation winding at a first pole of an auxiliary voltage source, a second pole of the auxiliary voltage source being connected to a second pole of the voltage source.

The invention also relates to an electric machine equipped with such a switching device and an on-board network with an electric machine.

The invention switches the excitation current with a main switching unit comprising a main switch connecting the first terminal of the excitation winding to a first pole of the voltage source as well as an auxiliary switching unit with a first auxiliary switch connecting the second terminal of the excitation winding to a first pole of an auxiliary voltage source. The second pole of this auxiliary voltage source is connected to the second pole of the voltage source. This allows the voltage across the excitation winding (excitation voltage) to be varied by the auxiliary voltage source. In particular, to excite more quickly and / or to de-excite more quickly, the voltage of the voltage source itself is increased.

The main switch and / or the auxiliary switch can be made in the form of semiconductor switches such as transistors, field effect transistors, in particular MOSFETs. In addition, the main switching unit and / or the auxiliary switching unit comprise, next to the main switch or the auxiliary switch, also other switches and / or diodes.

The invention has the advantage of allowing partitioning and in particular the retrofitting of the functionality of the switching device for faster excitation and / or de-excitation. This means that this functionality is not necessarily coupled to other electrical and / or electronic components but can be provided by them, separately. In other words, the invention has the advantage that in or for switching devices which are designed for rapid excitation and / or de-excitation of the rotor, there is an auxiliary switching unit for individually modifying the voltage. excitation while for other switching devices which are not intended for rapid excitation and / or excitation of the rotor, an auxiliary switching unit is not used.

This solution has the advantage of using in a simple manner, conventional switching devices as a basic switching device and of improving them with an auxiliary switching unit to lead to the switching device according to the invention, which thus allows an excitation. and / or faster de-excitation.

The invention has the advantage that basic switching devices which are not equipped with an auxiliary switching unit can be used and supplemented separately by auxiliary switching units, and that only the switching devices which have to meeting in particular the requirements concerning rapid excitation and / or de-excitation will be equipped with auxiliary switching units.

The invention also has the advantage of allowing, for example, mass production of basic switching devices, uniform, and not designed a priori for rapid excitation and / or de-excitation, which are thus particularly economical to manufacture. and the switching devices which must allow the rapid excitation and / or de-excitation of the rotor, will be equipped with auxiliary switching units, manufactured separately and making it possible to modify the excitation voltage.

Preferably, the auxiliary switching unit is separate or separate from the main switching unit.

Furthermore, the auxiliary switching installation could be carried out in a uniform manner and be combined with main switching installations having different, customer-specific characteristics relating to customer connection terminals and / or other functions.

The invention also has the advantage of minimizing the size of the chip or the size of a basic switching unit because in this basic switching unit there are no components for excitation and / or rapid de-excitation and only, in switching devices designed for rapid excitation and / or de-excitation of the rotor, will have auxiliary switching units with increase in chip size and / or congestion.

In addition, the auxiliary switching unit can be used to limit or cut the excitation current in the rotor if, for example, the main switch remains in a conductive state. The damage to the switching devices and / or the excitation winding and / or other parts of an on-board network possibly connected is thus reduced, and even such damage is avoided, which could be caused by an intensity of current too high and / or applied for too long or by too high voltage. This has the advantage that the auxiliary switching unit allows redundant shutdown. This increases the reliability of the switching device and / or reduces the risk of damage to the switching device itself and to the components connected to it. At the same time, the auxiliary switching unit of this embodiment may be used to provide the function of the main switching unit for regulating the on-board network. In particular, in the case of main switches that remain conductive, one of the auxiliary switches can be controlled in a clocked fashion to regulate the voltage of the on-board network by being connected or cut. This allows the generator to continue (if possible with a time limit) and increase the time available to arrive in a secure state.

For the voltage of the on-board network, it is advantageous to provide as a set value for the auxiliary switching installation, a higher value than for the main switching installation, but which is not greater than the maximum authorized value of the voltage of the on-board network. This prevents the auxiliary switching installation from intervening in the regulation as long as the main switching installation operates correctly.

Preferably, the auxiliary switching source is biased so that the voltage across the excitation winding is greater than the voltage of the voltage source. This solution has the advantage that the excitation voltage or voltage applied between the two terminals of the excitation coil can be increased by the auxiliary voltage source and thus allows a higher excitation current.

Preferably, the auxiliary switching unit has a second auxiliary switch for connecting the second terminal of the excitation winding to the second pole of the voltage source. It is thus possible to regularly energize or de-energize with the voltage unchanged from the voltage source.

Preferably, the auxiliary switching unit is a diode installed between the second terminal of the excitation winding and the first pole of the voltage source. This solution has the advantage of allowing a faster de-excitation of the excitation winding compared to the battery potential, even if no auxiliary external voltage source is connected (even in the event of a fault).

Preferably, the main switching unit and / or the auxiliary unit are in the form of integrated circuits IC (English terminology), in particular as a specific integrated circuit for an ASIC application (English terminology). This allows the main switching unit or the auxiliary switching unit to be made in a more compact and / or more finished manner and thus to be simply installed in the switching device and / or integrated. In particular, in this way it will be possible to have the main switching unit or the auxiliary switching unit, in a compact and nevertheless distinct form.

In principle, the main switching unit and / or the auxiliary switching unit have a discrete structure, i.e. they are made from separate electrical or electronic components, as for example, if the passage resistance of an integrated transistor is too high.

Preferably, the main switching unit and the auxiliary switching unit are housed at least partially in a common housing even if this is not essential. The mon3063851 tage of the main switching unit and the auxiliary switching unit in a common housing offers the advantage of a particularly compact switching device and / or a closed unit. For example, the main switching unit and the auxiliary switching unit can be installed on a common plate which has the advantage of improving the cooperation between the main unit and the auxiliary switching unit because, where appropriate disturbing influences on the interaction and / or communication between the main unit and the auxiliary switching unit will be attenuated and / or avoided in the switching device if these two devices are brought together as far as possible in a housing and / or on a turntable.

Preferably, the switching device has a logic unit for controlling the main switching unit and / or the auxiliary switching unit. As a variant or in addition, the switching device is controlled or regulated by an external logic unit. In particular, such a logic unit controls the semiconductor switches of the switching device.

According to another development, the main switching unit and / or the auxiliary switching unit each have their own logic which controls the main switching unit or the auxiliary switching unit. It is advantageous that the logic units of the main switching unit and the switching unit are connected so that they communicate and avoid or make it possible to avoid regulation or command which would differ and of the disadvantages which would result for the operation of the switching device. To verify the operability and correct operation of the two logic units, it is also possible to provide a main logic unit such as for example a "watchdog" system.

Drawings

The present invention will be described below in more detail using switching devices shown in the accompanying drawings in which:

FIG. 1 shows an on-board network assembly comprising a usual switching device, FIG. 2 shows an on-board network assembly with a switching device according to a preferred embodiment of the invention, FIGS. 3A and 3B show examples of excitation current curves for excitation and de-excitation of an excitation winding.

Description of embodiments of the invention

FIG. 1 shows the technical context of an on-board network circuit 10 with a switching device 20 known according to the state of the art, in particular for a motor vehicle with a voltage source 11 and users or a battery 1.

The voltage source 11 comprises an electric machine or a generator equipped with a stator 12, a rectifier 14 downstream from the stator 12, a rotor with an excitation current 16, in particular driven by the engine of the vehicle as well as a switching device 20 which corresponds to the state of the art (that is to say a field regulator or generator regulator) which predefines the excitation current passing through the excitation winding 16.

The known switching device 20 comprises a main switching unit 22, for example, in the form of an integrated circuit such as an ASIC circuit; in particular it can be a conventional switching unit. The switching device 20 and the main switching unit 22 are characterized by dotted lines surrounding them.

The main switching unit 22 includes a main switch 22c, for example, in the form of a transistor which switches the current flowing through the main switching unit 22 as well as a diode 22a for idling. In other embodiments, the diode 22a and / or the transistor 22c may each be made in the form of a FET and / or MOSFET transistor. In addition, the main switch unit 22 has a logic unit 22b which controls the main switch 22c.

In addition, the main switching unit 22 has a terminal 22d for the first pole of the voltage source 11 and a connection 22g (also called connection DF +) for a pre3063851 mier connection 16a of the excitation winding 16 on the main switch 22c.

The first terminal 16a of the excitation winding 16 presented above is then located for a main switch 22c closed on the battery potential (B +). The second terminal 16b shown below is located according to the second usual embodiment, on the potential of the second pole (ground 30) of the voltage source which is here the ground potential, that is to say (B- ).

To excite the rotor or the excitation winding 16, the main switch 22c can be closed and opened in pulse width modulation; thus, the excitation current from the voltage source 11 passes through the main switch 22c from the excitation winding 16 to ground 30. The amplitude of the excitation current is thus mainly defined by the repetition rate switching in the opening or closing direction of the main switch 22c. In this way, the voltage of the on-board network is regulated to a set value.

FIG. 2 shows a diagram of a switching device 200 according to a preferred embodiment of the invention, in particular of a vehicle with a voltage source 11 and users or a battery 1.

For the description of the elements of the assembly and in particular of the switching device 200 produced like the switching device 20 presented in FIG. 1, reference will be made to the description already made.

The embodiment described above differs in particular from the exemplary embodiment presented in FIG. 1 in that the switching device 200 comprises in addition to the main unit 22 also an auxiliary unit 24.

The auxiliary switching unit 24 has a diode 24a, a logic unit 24b and (in this example) two auxiliary switches 24c, 24d. The auxiliary switch 24d is connected between the second terminal 16b of the excitation current 16 and the first pole of an additional voltage source 34. The second pole of the supply voltage 34 is connected to the second pole (ground 30) of the voltage source 11. The auxiliary voltage source 34 can be made as a DC voltage converter.

The auxiliary switch 24c is located between the second terminal 16b of the excitation winding 16 and the second pole (ground 30) of the voltage source 11.

According to another preferred embodiment, it is also possible to produce a corresponding number of auxiliary switches 24c-24d in the main switching unit 24.

Thanks to the two auxiliary switches 24c and 24d for supplying the excitation winding 16 with an excitation current passing through the main switching unit 22, the first terminal 16a of the excitation winding 16 being at a potential positive B +, the second terminal 16b of the excitation winding 16 by switching the auxiliary switch 24c will be to ground or in the sense of the invention, by switching the auxiliary switch 24d to a negative potential opposite to ground, and which is supplied by the auxiliary voltage source 34. Thus, the voltage across the excited excitation winding relative to the battery voltage will be increased so that the excitation operation will be faster. To accelerate the de-excitation, the current is passed against the additional voltage of the auxiliary voltage source 34 (freely) as in freewheeling or a diode 24a against the voltage of the on-board network.

In this way, it is possible to have a particularly dynamic modification of the supply of the excitation winding 16 in order to excite and / or de-excite the excitation coil 16 without however requiring a main switching unit 22 produced specially for this event. . In particular, the main switching unit 22 which is usual, is connected to an auxiliary switching unit 24 to improve the rise in the excitation voltage.

According to a preferred development, the logic units 22b, 24b of the main switching unit 22 and the auxiliary unit 24 are connected to each other and are designed so that their controls and / or their regulation operations are first granted at least partially to achieve synchronous operation. It is also possible to use a logic unit 201 to make plausible ίο and / or monitor the synchronous operation. This is, for example, also reproduced in the switching device.

According to another embodiment, by continuing the switching device according to the logic unit which is suitable in particular in the main switching unit 22 for controlling the main switch 22c and the auxiliary switches 24c, 24d, for example with the switching device comprising its own logic unit which can be installed in particular in the main switch 22c.

In addition, FIG. 2 shows that the auxiliary switching unit 24 is preferably produced in the form of a closed unit, in particular of its own integrated circuit like that, for example the ASIC circuit used separately from the main unit switch 22 and which can be post-equipped or supplemented with a switching unit, separately from the main switching unit 22 and which can have, in a usual switching circuit 20, what occurs only in the units main switching and / or addition.

According to a preferred embodiment, the auxiliary switching unit has the advantageous effect that the auxiliary switches 24c, 24d can at least limit the excitation current in the excitation coil 16. This can in particular be advantageous if in the in the event of a fault and / or damage to the main switch 22c which undergoes this permanently, we want to avoid the uncontrolled passage of current through the excitation coil because the excitation current even for a true current in the excitation coil 16 by the auxiliary switch 24c and / or 24d can be interrupted. In particular, advantageously, the auxiliary switch unit 24 can also serve as a highly developed current regulator for the excitation current and thus as a very high regulator for the remanence voltage of the document as explained above.

FIG. 3A shows the graph of an example of the path plotting the amplitude of the excitation current (vertical axis) through the excitation winding 16 as a function of time (horizontal axis). If there is a command and / or regulation of the excitation current in the usual way, that is to say without the potential on the second connection 16b of the excitation current 16, the amplitude of the excitation develops as shown in curve 110. This corresponds to an excitation current guided by the auxiliary switch 24c. In addition, when the amplitude of the excitation current has an output value 100 and that for the closing of the main switch 22c of the auxiliary switch 24c at this time 102, then the amplitude of the excitation current continuously increases the along curve 110, to a final value 130, given by way of example.

If, on the other hand, the potential is lowered on the second terminal 16b of the excitation winding 16 with the auxiliary voltage source 34, the amplitude of this excitation current increases by the second surface 120. Besides this, the auxiliary switch 24c is open and the auxiliary switch 24d is closed.

Thus, by lowering the potential of the second terminal 16b of the excitation winding 16 when it is excited, there will be a faster and more conductive rise for the amplitude of the excitation current. This allows better dynamics of the excitation current because a significantly faster rise of the excitation current in the useful range (here up to the value 130) corresponds to the usual boxes.

Likewise, the invention also has an advantage for de-excitation of the excitation coil as shown in FIG. 3B. Curve 210 shows the evolution of the excitation current as a function of time. When the excitation current is appropriately controlled by the main switch 22c. This corresponds to a dry run through the auxiliary switch 24c. The amplitude of the excitation current corresponds to the final value 204 (= 130) and when the main switch 22c is opened (the auxiliary switch 24c remains closed) there will be an instant 202 with a current passing through the diode 22a, freely up to the start value 230 (= 100).

To have a rapid excitation 220 if the idling will be done according to a first alternative for the switch 24d closed and the switch 24c open with respect to the reduced potential (this increases the idling voltage) applied to the second terminal 16b of the excitation winding 16 or according to a second advantageous alternative, the switch 24d open and the switch 24c open are connected by the diode 24a against the potential of the first pole of the voltage source 11 (B +). The curve in this case follows the line 220.

Thus by lowering the potential on the second terminal 16b of the excitation winding 16, there will be a significantly faster or steeper fall in the amplitude of the excitation current. This allows in particular a better dynamics of the excitation current because there will be a significantly faster fall of the excitation current than in the usual cases.

NOMENCLATURE OF MAIN ELEMENTS

10 Embedded network 11 Voltage source 5 12 Stator 14 Rectifier 16 Excitation winding 16a First connection 16b Second connection 10 20 Known switching device 22 Main switching unit 22b Logical unit 22c Main switch 22d Thick headed 15 22g Thick headed 24 Auxiliary unit / auxiliary switch 24a Freewheeling diode 24b Logical unit 24c Main switch 20 24c, 24d Auxiliary switch 25 Excitation switch 30 Second pole (mass) 34 Additional voltage source 102 Main switch 25 200 Switching device 201 Logical unit

Claims (13)

1 °) Switching device (200) for switching an electric excitation current of an electric machine with an excitation winding (16) comprising: a main switching unit (22) comprising a main switch (22c) for connecting the first terminal (16a) of the excitation winding (16) to the first pole of a voltage source (11), the main unit switch (22) switching the excitation current from the voltage source (11) to the excitation winding (16), an auxiliary switching unit (24) with a first auxiliary switch (24d) for connecting the second terminal (16b) of the excitation winding (16) at the first pole of an auxiliary voltage source (34), a second pole of the auxiliary voltage source (34) being connected to a second pole (30) of the voltage source (11). 2 °) switching device (200) according to claim 1, characterized in that the auxiliary voltage source (34) is polarized so that the voltage across the excitation winding is greater than the voltage of the source tension (11). 3) switching device (200) according to one of claims 1 or 2, characterized in that the auxiliary switching unit (24) comprises a second auxiliary switch (24c) for connecting the second terminal (16b) of the 'excitation winding (16) at the second pole (30) of the voltage source (11). 4 °) switching device (200) according to one of the preceding claims, characterized in that the auxiliary switching unit (24) comprises a diode (24a) between the second terminal (16b) of the excitation winding (16) and the first pole of the voltage source (11). 5 °) switching device (200) according to one of the preceding claims, characterized in that the main switching unit (22) and / or the auxiliary switching unit (24) regulate the excitation current and / or the output voltage of the electric machine. 6 °) Switching device (200) according to one of the preceding claims, characterized in that the auxiliary switching unit (24) is in the form of an integrated circuit. 7 °) Switching device (200) according to one of the preceding claims, characterized in that the auxiliary switching unit (24) is produced separately from the main switching unit (22). 8 °) Switching device (200) according to any one of the preceding claims, characterized in that the main switching unit (22) and the auxiliary switching unit (24) are housed in a common housing. 9 °) Switching device (200) according to any one of the preceding claims, characterized in that the main switching unit (20) and the auxiliary switching unit (24) each have their own logic unit (22b, 24b) for controlling the main switching unit (20) and the auxiliary switching unit (24). 10 °) switching device (200) according to claim 9, 5 characterized in that the logic units (22b, 24b) of the main switching unit (20) and the auxiliary switching unit (24) are connected so as to transmit the data. 10 11 °) Switching device (200) according to claims 9 or 10, characterized in that the logic units (22b, 24b) of the main switching unit (20) and the auxiliary switching unit (24) are monitored by a main logic unit (201). 12 °) Electric machine comprising a switching device (200) according to one of the preceding claims. 13 °) On-board network (100) comprising an electric machine according to claim 12. 1/3