DE102017204091A1 - Switching device for switching an electrical excitation current for an electric machine with a rotor - Google Patents

Abstract

The invention relates to a switching device (200) for switching an electrical exciter current for an electrical machine having a field winding (16), comprising a main switching unit (22) with a main switch (22c) for connecting a first terminal (16a) of the field winding (16) a first pole of a voltage source (11), wherein the main switching unit (22) is adapted to switch an excitation current from the voltage source (11) to the excitation winding (16), a secondary switching unit (24) having a first auxiliary switch (24d) for connecting a second terminal (16b) of the excitation winding (16) having a first pole of an additional voltage source (34), wherein a second pole of the auxiliary voltage source (34) with a second pole (30) of the voltage source (11) is connected.

Description

The present invention relates to a switching device for switching an electrical exciting current for an electric machine with a field winding, in particular for generators for motor vehicles.

State of the art

(Power) vehicles usually have an electrical system, which is powered by a generator operated as electrical machine, for example. A separately excited synchronous machine with voltage. To control the vehicle electrical system voltage while an excitation current of the generator can be controlled or regulated. The generator is usually connected via a rectifier (with diodes or semiconductor switches as rectifier elements) to the electrical system. Because generators of the type described often have a high inductance in the excitation field and thus a high time constant in the control, it is desirable to change the excitation current as needed, as quickly as possible, i. build or dismantle. It is therefore desirable to have higher voltage than a vehicle electrical system voltage available for this purpose. For this purpose, circuits with diodes and transistors can be used, but take in the generator controller or its circuit relatively much space or chip area.

In addition, the reveals US 8,008,895 B2 a generator regulator in which the excitation voltage can be increased by applying a negative potential to a terminal of the excitation winding by means of a capacitor.

Disclosure of the invention

According to the invention, a switching device for switching an electrical excitation current for an electric machine with a field winding with the features of claim 1 is proposed. In another aspect, the invention relates to an electrical machine with a switching device according to the invention and an electrical system with an electrical machine according to the invention. Advantageous embodiments are the subject of the dependent claims and the following description.

The invention uses the measure, for switching the exciter current, a main switching unit with a main switch for connecting a first terminal of the field winding to a first pole of a voltage source and a secondary switching unit with a first sub-switch for connecting a second terminal of the field winding to a first pole of an additional voltage source in which a second pole of the additional voltage source is connected or connectable to a second pole of the voltage source. In this way, the voltage across the excitation winding (exciter voltage) can be varied by means of the additional voltage source, in particular for rapid excitation and / or for rapid de-excitation relative to the voltage of the actual voltage source can be increased.

The main switch and / or the sub-switch can be configured, for example, as a semiconductor switch, such as transistors, such as field effect transistors, in particular MOSFETs. Furthermore, the main switching unit and / or the secondary switching unit may have, in addition to the main switch or the auxiliary switch, further switches and / or diodes.

The invention offers the advantage that a functionality of the switching device can be partitioned for rapid excitation and / or fast de-excitation and in particular can be retrofitted. This means that this functionality does not necessarily have to be coupled to other electrical and / or electronic components, but can be provided separately from these. In other words, the invention offers the advantage that in switching devices which are to be designed for a rapid excitation and / or de-energizing of the rotor, a secondary switching unit for varying the excitation voltage can be provided individually, while for other switching devices which are not suitable for a fast energizing and / or de-energizing the rotor should be provided, can be dispensed with the provision of a secondary switching unit.

This thus offers the advantage that, for example, a conventional switching device can be used as basic switching device in a simple manner and can be improved by providing a secondary switching unit to a switching device according to the invention, which then allows rapid excitation and / or rapid de-energizing.

In this way, the invention offers the advantage that, for example, basic switching devices that are not equipped with a secondary switching unit can be provided and sub-switching units can be provided separately, and only those switching devices are provided with the sub-switching unit, which has special requirements for rapid excitation and or de-energizing.

Furthermore, the invention offers the advantage that, for example, a mass production of uniform basic switching devices can take place, which, for example, are not designed to allow rapid excitation and / or deenergization and thus can be produced particularly cost-effectively, while such switching devices, which should be suitable for quickly energizing and / or de-energizing the rotor, with separately provided sub-switching units for varying the excitation voltage can be equipped. The secondary switching unit is thus preferably separate or formed separately from the main switching unit.

Furthermore, the secondary switching device can be designed uniformly and combined with main switching devices of different customer-specific characteristics with regard to customer connections and / or functions.

Furthermore, the invention offers the advantage that a chip size or a space requirement for a base switching unit can be minimized, since in the base switching unit no components for rapid excitation and / or de-energizing must be provided, and only in such switching devices, which for rapid excitation and / or de-energize the rotor to be designed by the additional provision of the secondary switching unit chip size and / or the space required are increased.

Furthermore, the secondary switching unit can serve to limit or interrupt the exciting current through the rotor when, for example, the main switch remains in a conducting state. Thus, damage to the switching devices and / or to the excitation winding and / or other parts of a possibly connected electrical system can be reduced or even avoided, which are caused for example by too high and / or too long-lasting current flow or by an excessive voltage can. Thus, this offers the advantage that a redundant shutdown is possible by means of the secondary switching unit. As a result, the reliability of the switching device can be increased and / or the risk of damage to the switching device itself and to components connected thereto can be reduced. At the same time, the secondary switching unit can be used in this embodiment to take over the function of the main switching unit with regard to the regulation of the vehicle electrical system voltage. In particular, one of the sub-switches for controlling the vehicle electrical system voltage can be switched on and off in the event of a continuously conductive main switch. This allows further (possibly temporary) further operation of the generator and increases the time available to reach a safe state.

It is advantageous if the setpoint of the vehicle electrical system voltage for the secondary switching device is set to a higher value than for the main switching device, which is not higher than a maximum permissible vehicle electrical system voltage value. This avoids that the secondary switching device engages in the regulation, as long as the main switching device is functional.

Preferably, the additional voltage source is polarized such that the voltage across the field winding is greater than the voltage of the voltage source. This has the advantage that the excitation voltage or the voltage which is applied between the two ends of the exciter coil can be increased by the additional voltage source and in this way a higher exciter current can be achieved.

Preferably, the secondary switching unit has a second auxiliary switch for connecting the second terminal of the field winding to the second pole of the voltage source. In this way, arousal and de-energizing can also be done regularly with the voltage of the voltage source unchanged.

Preferably, the sub-switching unit has a diode between the second terminal of the field winding and the first pole of the voltage source. This offers the advantage that a rapid de-energizing of the exciter winding against battery potential can take place, even if no external additional voltage source is connected (even in the event of a fault).

Preferably, the main switching unit and / or the sub-switching unit as an integrated circuit IC (English: Integrated Circuit), in particular as an application-specific integrated circuit ASIC (English: Application Specific Integrated Circuit) is formed. As a result, the main switching unit or the secondary switching unit can be provided in compact and / or closed form and can be easily arranged in the switching device and / or integrated into it. In particular, in this way the main switching unit and / or the secondary switching unit can be provided in a compact manner and yet separately from each other.

In principle, however, the main switching unit and / or the sub-switching unit may also have a discrete structure, i. be constructed of individual electrical or electronic components, for example, if the ON resistance of an integrated transistor is too high.

Preferably, the main switching unit and the secondary switching unit are at least partially arranged in a common housing, although this is not absolutely necessary. The arrangement of the main switching unit and the Sub-switching unit in a common housing has the advantage that the switching device can be provided particularly compact and / or as a self-contained unit. For example, the main switching unit and the secondary switching unit can be arranged on a common board. This offers the advantage that an interaction of the main switching unit and the secondary switching unit can be improved, since possibly occurring interference influences an interaction and / or communication of the main switching unit and the secondary switching unit in the switching device and / or can be avoided if this together as close as possible a housing and / or are arranged on a circuit board.

Preferably, the switching device has a logic unit which is set up to control the main switching unit and / or the secondary switching unit. Alternatively or additionally, the switching device may be configured to be controlled by an external logic unit. In particular, such a logic unit can be set up to control semiconductor switches present in the switching device.

According to a further preferred embodiment, the main switching unit and / or the secondary switching unit each have their own logic unit, which is set up to control the main switching unit or the secondary switching unit. It may be advantageous that the logic units of the main switching unit and the secondary switching unit are connected to each other so that they can communicate with each other to avoid or prevent a different control or regulation and resulting disadvantages for the function of the switching device. For a check of the operability and the correct operation of the two logic units, a higher-order logic unit, such as e.g. a watchdog, be provided.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

The invention is illustrated schematically by means of embodiments in the drawings and will be described below with reference to the drawings.

list of figures

• 1 shows a circuit diagram of a vehicle electrical system with a conventional switching device.
• 2 shows a circuit diagram of a vehicle electrical system with a switching device according to a preferred embodiment of the invention.
• 3A and 3B show exemplary courses of the excitation current when energizing and de-energizing the exciter winding.

Embodiments of the invention

1 shows as a technological background a circuit diagram of a vehicle electrical system 10 with a conventional switching device 20 as known from the prior art, in particular a (power) vehicle, with a voltage source 11 and consumers or battery 1 ,

The voltage source 11 has an electric machine or a generator with a stand 12 , one the stand 12 downstream rectifier 14 , a runner with excitation winding 16 , which can be driven in particular by an engine of the vehicle, and a non-inventive switching device 20 (so-called field controller or generator controller) for specifying an exciter current through the exciter winding 16 on.

The conventional switching device 20 has a main switching unit 22 on, for example in the form of an integrated circuit, such as ASIC, which may be in particular a conventional switching unit. The switching device 20 and the main switching unit 22 are each indicated by circumferential dashed lines.

The main switching unit 22 has a main switch 22c formed as a transistor, for example, by means of which the current flowing through the main switching unit 22 current can be switched, and a diode 22a for the freewheel up. In other embodiments, the diode 22a and / or the transistor 22c each also be designed as FET and / or MOSFET. In addition, the main switching unit points 22 a logic unit 22b on, by means of which the main switch 22c can be controlled.

Furthermore, the main switching unit 22 a connection 22d for a first pole of the voltage source 11 and a connection 22g (also referred to as DF +) for a first connection 16a the excitation winding 16 on, passing through the main switch 22c can be connected.

At the first port shown above 16a the excitation winding 16 is then included closed main switch 22c Battery potential (B +) on. The second port shown below 16b is according to the shown, conventional embodiment on the potential of the second pole (mass 30 ) of the voltage source, in this case to ground potential (or B-).

To excite the runner or the excitation winding 16 For example, the main switch 22c may be closed and opened in pulse width modulated fashion, thereby providing an excitation current from the voltage source 11 via the main switch 22c through the excitation winding 16 to mass 30 flows. The height of the excitation current is essentially determined by the sampling rate of switching the main switch on and off 22c certainly. In this way, the vehicle electrical system voltage can be regulated to a desired value.

2 shows a circuit diagram of a vehicle electrical system 100 with a switching device 200 according to a preferred embodiment of the invention, in particular a (power) vehicle, with a voltage source 11 and consumers or battery 1 ,

With regard to the description of the elements of the circuit diagram and in particular the switching device 200 which also in the in 1 shown conventional switching device 20 are trained, reference is made to the description there.

In the 2 shown preferred embodiment differs in particular from the in 1 shown in the example that the switching device 200 in addition to the main switching unit 22 a secondary switching unit 24 having.

The sub-switching unit 24 has a diode 24a , a logic unit 24b and - in the example shown - two sub-switches 24c and 24d on. This is the sub-switch 24d between the second port 16b the excitation winding 16 and a first pole of a booster voltage source 34 arranged. A second pole of the additional voltage source 34 is with the second pole (mass 30 ) of the voltage source 11 connected. The additional voltage source 34 can be configured for example as a DC-DC converter.

The sub-switch 24c is between the second port 16b the excitation winding 16 and the second pole (ground 30 ) of the voltage source 11 arranged.

According to other preferred embodiments may also have a different number of secondary switches 24c respectively. 24d in the sub-switching unit 24 be educated.

By means of the two auxiliary switches 24c and 24d can be achieved that when energizing the exciter winding 16 with excitation current through the main switching unit 22 , where the first connection 16a the excitation winding 16 positive potential B +, the second connection 16b the excitation winding 16 when switching the sub-switch 24c on earth or - in the sense of the invention - when switching the sub-switch 24d is at a negative to ground potential, which of the additional voltage source 34 provided. As a result, the voltage across the exciter winding when excited relative to the battery voltage can be increased, so that the excitation process takes place more quickly. To speed up the de-energizing, the current runs against the additional voltage of the additional voltage source 34 free (analogous to a freewheel via diode 24a against the vehicle electrical system voltage).

In this way, a particularly dynamic change in the energization of the exciter coil 16 to excite and / or de-energize the exciter coil 16 be achieved without the need for a specially trained main switching unit 22 must be provided. In particular, a conventional main switching unit 22 with a secondary switching unit 24 be connected in order to achieve an exciter voltage increase.

According to the preferred embodiment, the logic units 22b and 24b the main switching unit 22 and the sub switching unit 24 data transmitting connected to each other and set up so that their control and / or control operations are at least partially matched to achieve a synchronous operation. It can also (optionally) have a higher-level logic unit 201 be provided for plausibility and / or monitoring of the synchronous operation. This is for example also arranged within the switching device.

According to other embodiments, for example, the switching device may also be formed with a single logic unit, which in particular in the main switching unit 22 can be arranged to order the main switch or 22c and the one or more auxiliary switches 24c and 24d to control.

Furthermore, in 2 recognizable that the secondary switching unit 24 preferably as a self-contained unit, preferably as a separate integrated circuit, such as ASIC, separate from the main switching unit 22 can be provided and thereby, for example, in a conventional switching device 20 which sometimes has only one main switching unit, can be retrofitted or added.

In addition, the sub-switching unit according to the preferred embodiment has the advantageous effect that the sub-switches 24c and 24d at least partially a current limit of the excitation current through the excitation coil 16 can effect. This can be advantageous in particular if, in the event of a fault and / or damage to the main switch 22c in which this constantly conducts, an uncontrollable current flow through the excitation coil can be avoided, since the current flow or the excitation current through the exciter coil 16 through the auxiliary switch 24c and or 24d can be interrupted. Particularly advantageous is the secondary switching unit 24 Also serve as a full power regulator for the excitation current and thus as a full-fledged controller for the vehicle electrical system voltage, as already stated above.

3A shows in a graph an exemplary plot of the course of an amplitude of the excitation current (vertical axis) through the exciter winding 16 against time (horizontal axis). Is a control and / or regulation of the excitation current in a conventional manner, ie without the potential at the second terminal 16b the excitation winding 16 lower, the amplitude of the excitation current runs as with a curve 110 shown. This corresponds to a field current through the sub-switch 24c , First, the amplitude of the excitation current has an output value 100 on, and closing the main switch 22c and the sub-switch 24c at a time 102 Then, the amplitude of the excitation current continuously increases along 110 to an exemplary end value 130 at.

On the other hand, the potential at the second connection 16b the excitation winding 16 by means of the additional voltage source 34 lowered, the amplitude of the excitation current follows the steeper curve 120 , There are auxiliary switches 24c opened and sub-switch 24d closed.

Thus, by lowering the potential at the second port 16b the excitation winding 16 When exciting a significantly faster or steeper increase in the amplitude of the excitation current can be achieved. As a result, an improved dynamics of the excitation current can be achieved, since a significantly faster increase of the excitation current in the usable range (here to value 130 ) can be achieved than in conventional cases.

Similarly, the invention also provides an advantage in deenergizing the exciting coil as in 3B shown. The curve 210 shows a course of the excitation current with respect to the time when the excitation current in the conventional manner only with the main switch 22c is controlled. This corresponds to a freewheel through the auxiliary switch 24c , First, the amplitude of the excitation current has the final value 204 (= 130) on and when opening the main switch 22c (Sub-switch 24c stays closed) at a time 202 the current runs over the diode 22a free until the start value 230 (= 100) is reached.

If a fast de-energizing along 220 is desired, the freewheel can according to a first alternative with the switch closed 24d and opened switch 24c against the reduced potential (this increases the free-wheeling voltage) at the second terminal 16b the excitation winding 16 or according to a second alternative with the switch open 24d and opened switch 24c via the diode 24a against the potential of the first pole of the voltage source 11 (B +). The curve follows the course in these cases 220 ,

Thus, by lowering the potential at the second port 16b the excitation winding 16 When Entregen a significantly faster or steeper drop in the amplitude of the excitation current can be achieved. As a result, an improved dynamics of the exciting current can be achieved, since a much faster drop in the excitation current can be achieved than in conventional cases.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US Pat. No. 8008895 B2

Claims (13)

A switching device (200) for switching an electrical excitation current for an electric machine having a field winding (16), comprising: - A main switching unit (22) having a main switch (22c) for connecting a first terminal (16a) of the excitation winding (16) to a first pole of a voltage source (11), wherein the main switching unit (22) is adapted to an excitation current from the voltage source (11) to the exciter winding (16) to switch; a secondary switching unit (24) having a first auxiliary switch (24d) for connecting a second terminal (16b) of the excitation winding (16) to a first pole of an additional voltage source (34), a second pole of the auxiliary voltage source (34) being connected to a second pole (16). 30) of the voltage source (11) is connected. Switching device (200) after Claim 1 wherein the auxiliary voltage source (34) is poled such that the voltage across the field winding is greater than the voltage of the voltage source (11). Switching device (200) after Claim 1 or 2 in that the secondary switching unit (24) has a second auxiliary switch (24b) for connecting the second terminal (16b) of the exciter winding (16) to the second pole (30) of the voltage source (11). Switching device (200) according to one of the preceding claims, wherein the secondary switching unit (24) has a diode (24a) between the second terminal (16b) of the excitation winding (16) and the first pole of the voltage source (11). Switching device (200) according to one of the preceding claims, wherein the main switching unit (22) and / or the secondary switching unit (24) are adapted to control the excitation current and / or an output voltage of the electric machine. Switching device (200) according to one of the preceding claims, wherein the secondary switching unit (24) is designed as an integrated circuit. Switching device (200) according to one of the preceding claims, wherein the secondary switching unit (24) is formed separately from the main switching unit (22). Switching device (200) according to one of the preceding claims, wherein the main switching unit (22) and the secondary switching unit (24) are arranged in a common housing. Switching device (200) according to one of the preceding claims, wherein the main switching unit (20) and the sub-switching unit (24) each have their own logic unit (22b, 24b) which is adapted to the main switching unit (20) and the sub-switching unit (24) control, exhibit. Switching device (200) after Claim 9 , wherein the logic units (22b, 24b) of the main switching unit (20) and the sub-switching unit (24) are data transmitting connected. Switching device (200) after Claim 9 or 10 in which the logic units (22b, 24b) of the main switching unit (20) and the sub-switching unit (24) are monitored by a superordinate logic unit (201). Electric machine with a switching device (200) according to one of the preceding claims. Electrical system (100) with an electric machine after Claim 12 ,

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