Electric arrangement and method for controlling of at least two electric motors

An electric arrangement which, for controlling at least two electric motors, has at least one first H-bridge arrangement and a second H-bridge arrangement, is provided. The electric arrangement comprises a first electric motor, which is electrically connected to a first switching element, a second switching element, a third switching element and a fourth switching element in the first H-bridge arrangement. The electric arrangement furthermore comprises a second electric motor, which is arranged in a second bridge branch of the second H-bridge arrangement) and is connected to a third half-bridge via a third motor contact, wherein the third half-bridge comprises a fifth switching element and a sixth switching element.

CROSS-REFERENCE TO A RELATED APPLICATION

This application claims priority to German Patent Application No. 10 2015 220 854.0 filed on Oct. 26, 2015, the entirety of which is incorporated by reference herein.

BACKGROUND

The invention relates to an electric arrangement and to a method for controlling at least two electric motors.

Such an electric arrangement, for controlling at least two electric motors, has at least one first H-bridge arrangement (also referred to as full-bridge arrangement) and a second H-bridge arrangement and comprises a first electric motor, which is electrically connected to a first switching element, a second switching element, a third switching element and a fourth switching element in the first H-bridge arrangement. In this case, the first electric motor is arranged in a first bridge branch of the first H-bridge arrangement. The first electric motor can be for example an adjusting motor of a window winding device of a motor vehicle. In the context of the electric arrangement, for example, said motor can be controlled by means of pulse width modulation and for this purpose can be interconnected with the first, second, third and fourth switching elements in the H-bridge arrangement.

The switching elements can be for example semiconductor transistors, in particular MOSFETs and/or or IGBTs.

In this case, the first electric motor is connected to a first half-bridge via a first motor contact, wherein the first half-bridge comprises the first switching element and the second switching element. In addition, the first electric motor is connected to a second half-bridge via a second motor contact, said second half-bridge comprising the third switching element and the fourth switching element.

Furthermore, the electric arrangement comprises at least one second electric motor arranged in a second bridge branch of the second H-bridge arrangement. In this case, the second electric motor is connected to a third half-bridge via a third motor contact, said third half-bridge comprising a fifth switching element and a sixth switching element.

The second electric motor can be for example a second adjusting motor of a window winding device in a motor vehicle. In this regard, the first adjusting motor can be arranged for example for adjusting a windowpane of a left vehicle door, and the second electric motor can be arranged for adjusting a windowpane of a right vehicle door. Furthermore, the first adjusting motor can be arranged for example for adjusting a windowpane of a front vehicle door, while the second electric motor can be arranged for adjusting a windowpane of a rear vehicle door. In this case, a user may desire to control the two electric motors in such a way that the windowpane at the left or front vehicle door is raised, while the windowpane at the right or rear vehicle door is lowered, or vice versa.

It is known, in an electric arrangement of the type described in the introduction, to provide two separate H-bridge arrangements for controlling the first electric motor, on the one hand, and the second electric motor, on the other hand. Accordingly, the second electric motor is connected by a fourth motor contact to a fourth half-bridge comprising a seventh switching element and an eighth switching element. What is disadvantageous in the case of the previously known solution is that a total of at least eight switching elements are required for controlling two electric motors. It should be taken into consideration here that each switching element firstly per se is associated with costs and weight and secondly takes up valuable structural space, for example on a printed circuit board.

SUMMARY

The invention is based on the object of improving an electric arrangement of the type mentioned in the introduction with regard to its production costs, its weight and/or the required structural space.

This object is achieved according to the invention by means of an electric arrangement as described herein and by means of a method as described herein.

Accordingly, the second electric motor is connected to the first half-bridge via a fourth motor contact in such a way that it is electrically connected to the first switching element, the second switching element, the fifth switching element and the sixth switching element in the second H-bridge arrangement. In this way, the first half-bridge on the one hand together with the second half-bridge forms the first H-bridge arrangement comprising the first electric motor in the first bridge branch, and on the other hand together with the third half-bridge forms the second H-bridge arrangement comprising the second electric motor arranged in the second bridge branch. Consequently, the first half-bridge forms simultaneously in each case a part of the first H-bridge arrangement and of the second H-bridge arrangement.

The electric arrangement according to the invention enables the first electric motor and the second electric motor to be controlled independently. In this case, the electric arrangement manages with a total of only six switching elements, thereby saving two switching elements in comparison with previously known solutions. The production costs of an electric arrangement for independently controlling two electric motors, for example two adjusting motors of a window winding device for a motor vehicle, can be reduced in this way. Moreover, by saving two switching elements, weight can be saved, and valuable structural space, for example on a printed circuit board, can be utilized in a different way or be saved.

In one preferred embodiment of the electric arrangement according to the invention, each of the switching elements is switchable into a closed state and into an open state depending on a respective control signal. In this case, the open state should be understood to mean a state in which the switching element is designed, at least in a forward direction, to block a voltage and to conduct no or substantially no current. By contrast, in the closed state the switching element is able to conduct a current in the forward direction comparatively well.

In particular, the switching elements can comprise at least one semiconductor transistor, for example a MOSFET or some other field effect transistor (FET). In this case, the open state can correspond to a high-impedance state and the closed state can correspond to a comparatively low-impedance state of the MOSFET. A gate voltage present at a gate terminal of the MOSFET as control signal can bring about a switchover from the open state into the closed state, or vice versa. In this case, it is also conceivable for the switching elements to comprise at least one bipolar semiconductor transistor, in particular an IGBT. In this case, too, a switchover from a blocking open state into a conducting closed state of the IGBT, or vice versa, can be brought about by a control signal in the form of a gate voltage.

In accordance with one development, the electric arrangement comprises at least one control unit configured for generating the control signals for the switching elements depending on a desired direction of rotation and/or rotational speed of the first electric motor and/or of the second electric motor. Such a control unit can be a microcontroller, for example, the outputs of which for communicating the control signals are connected in each case to assigned control terminals of the switching elements. By way of example, such a microcontroller can receive signals via signal inputs from operating elements actuated by a user for this purpose, said signals corresponding to a desired direction of rotation and/or rotational speed for each electric motor. Said signals can be translated into corresponding control signals by the microcontroller for controlling the electric motors, in particular by means of pulse width modulation, said control signals being output to the control terminals of the switching elements.

In one preferred embodiment, the first electric motor and/or the second electric motor are/is a DC motor. DC motors are suitable for controlling by means of the H-bridge arrangement according to the invention, in particular by a method of pulse width modulation. Adjusting motors, for example on a window winding device for a motor vehicle, can be embodied as DC motors.

It lies within the scope of the invention that the first electric motor is drivable in one direction of rotation by a current flow from the first motor contact to the second motor contact and in an opposite direction of rotation by a current flow from the second motor contact to the first motor contact. Correspondingly, the second electric motor can be drivable in one direction of rotation by a current flow from the third motor contact to the fourth motor contact and in an opposite direction of rotation by a current flow from the fourth motor contact to the third motor contact. By way of example, a DC motor as first electric motor can be arranged in the electric arrangement according to the invention in such a way it is driven to clockwise rotation by a current flow from the first motor contact to the second motor contact, whereas it is driven to counterclockwise rotation by an opposite current flow from the second motor contact to the first motor contact (or vice versa). The same correspondingly applies to the second electric motor.

In a second aspect of the invention, an electric window winding device for a motor vehicle comprising at least one first adjusting motor for adjusting a first windowpane and at least one second adjusting motor for adjusting a second windowpane is proposed. In this case, the electric window winding device comprises at least one electric arrangement according to the invention comprising the at least one first adjusting motor as first electric motor and comprising the at least one second adjusting motor as second electric motor. By means of the electric arrangement, both adjusting motors can be controlled independently of one another in such a way that, for example, only one of the windowpanes is raised or lowered into a, that both windowpanes are simultaneously raised or lowered into the, or that one of the windowpanes is raised and at the same time the other windowpane is lowered.

A third aspect of the invention relates to a method for controlling at least two electric motors, in particular by means of pulse width modulation. An electric arrangement which, for controlling the electric motors, has at least one first H-bridge arrangement and a second H-bridge arrangement is used in this case. The electric arrangement comprises a first electric motor, which is arranged in a first bridge branch of a first H-bridge arrangement and is electrically connected to a first half-bridge and a second half-bridge in the first H-bridge arrangement. In addition, the electric arrangement comprises a second electric motor, which is arranged in a second bridge branch of a second H-bridge arrangement and is electrically connected to the first half-bridge and a third half-bridge in the second H-bridge arrangement. In this case, the first half-bridge is simultaneously part of the first H-bridge arrangement and of the second H-bridge arrangement. In this case, each of the half-bridges comprises at least two switching elements.

In the method according to the invention, the first electric motor is controlled by the switching of the switching elements of the first half-bridge and of the second half-bridge. Additionally or alternatively, the second electric motor can be controlled by the switching of the switching elements of the first half-bridge and of the third half-bridge.

In particular, an electric arrangement in accordance with the first aspect of the invention and/or in accordance with the second aspect of the invention can be used in the context of the method according to the invention for controlling the electric motors. Accordingly, in the context of this disclosure, features explained in association with the electric arrangement according to the invention or the electric window winding device according to the invention likewise relate to the device used in the method according to the invention, and vice versa.

In one preferred embodiment, the half-bridges can be electrically connected to a first supply terminal and to a second supply terminal. In this way, for example, a supply voltage or the electric motors can be applied between the first supply terminal and the second supply terminal. Furthermore, the half-bridges can be switchable in each case into a first half-bridge position, into a second half-bridge position and into a third half-bridge position. In this case, in the first half-bridge position that one of the switching elements which is arranged within the respective half-bridge in an electric path between the first supply terminal and the respective other one of the switching elements is closed, while the other one of the switching elements is open. By contrast, in the second half-bridge position that one of the switching elements which is arranged within the respective half-bridge in an electric path between the second supply terminal and the respective other one of the switching elements is closed, the other one of the switching elements being open. In the third half-bridge position the switching elements of the respective half-bridge are open. It goes without saying that, in principle, further electrical components, for example diodes or resistors, can be arranged in the relevant electric paths.

In order to control the electric motors, the first half-bridge, in a first switching sequence, can be switched periodically into the first half-bridge position for a first pulse duration and into the second half-bridge position for a second pulse duration. In this case, additionally the second half-bridge and/or the third half-bridge are/is switched depending on the electric motor to be controlled.

In this regard, the second half-bridge, in a second switching sequence, can be switched between the first half-bridge position, the second half-bridge position and/or the third half-bridge position in order to control the first electric motor. In order to control the second electric motor, the third half-bridge, in a third switching sequence, can be switched between the first half-bridge position, the second half-bridge position and/or the third half-bridge position. In this case, the second and third switching sequences can depend on the desired direction of rotation and/or rotational speed of the first and/or second electric motor. The choice of suitable second and third switching sequences enables independent controlling of the first electric motor, on the one hand, and of the second electric motor, on the other hand, with regard to their direction of rotation and rotational speed.

In one variant, in order to control the first electric motor in such a way that it is driven in one direction of rotation, the second half-bridge is switched into its second half-bridge position for a plurality of period durations of the first switching sequence. In addition or as an alternative thereto, the second half-bridge can be switched into its first half-bridge position for a plurality of period durations of the first switching sequence in order to drive the first electric motor in an opposite direction of rotation. Correspondingly, the third half-bridge can be switched into its first half-bridge position for a plurality of period durations of the first switching sequence in order to drive the second electric motor in one direction of rotation, and/or can be switched into its second half-bridge position for a plurality of period durations of the first switching sequence in order to drive the second electric motor in an opposite direction of rotation.

Relative to a predefined first switching sequence of the first half-bridge, a maximum possible rotational speed of the respective electric motor can be achieved with this variant since the respective pulse durations of the first switching sequence are utilized completely as supply phases for the drive of the electric motors.

It is also possible, however, to set a rotational speed independently for each electric motor. For this purpose, for example, in order to drive the first electric motor in one direction of rotation the second half-bridge can be switched periodically into its second half-bridge position, such that the second half-bridge adopts the second half-bridge position at least for a third pulse duration, during which the first half-bridge is in its first half-bridge position. Alternatively or additionally, the second half-bridge, in order to drive the first electric motor in an opposite direction of rotation, can be switched periodically into its first half-bridge position and adopt the latter in each case at least for a fourth pulse duration, during which the first half-bridge is in its second half-bridge position.

Correspondingly, the third half-bridge, in order to drive the second electric motor in one direction of rotation, can be switched periodically into its first half-bridge position, such that the third half-bridge adopts the first half-bridge position in each case at least for a fifth pulse duration, during which the first half-bridge is in its second half-bridge position. Alternatively or additionally, the third half-bridge, in order to drive the second electric motor in an opposite direction of rotation, can be switched periodically into its second half-bridge position and remain in the latter in each case at least for a sixth pulse duration, during which the first half-bridge is in its first half-bridge position.

In order to enable an active freewheeling between the phases in which the respective electric motor is driven by a current flow between the supply terminals, particular precautions can be taken in the context of the second and third switching sequences. If the switching elements are MOSFETs, for example, it may be expedient to switch on individual MOSFETS occasionally, in order that a freewheeling current can flow through them in the reverse direction with the least losses possible.

For this purpose, the second half-bridge and/or the third half-bridge can be switched periodically into the first half-bridge position thereof and adopt the latter while the first half-bridge is in its first half-bridge position. In other words, provision can be made for there to be a temporal overlap between the first half-bridge position of the second half-bridge and/or of the third half-bridge, on the one hand, and the first half-bridge position of the first half-bridge. Alternatively or additionally, the second half-bridge and/or the third half-bridge can be switched periodically into the second half-bridge position thereof and adopt the latter while the first half-bridge is in its second half-bridge position, such that there is a temporal overlap between the second half-bridge position of the second half-bridge and/or of the third half-bridge, on the one hand, and the second half-bridge position of the first half-bridge, on the other hand.

In accordance with one variant, a rotational speed of the first electric motor is controlled by setting a ratio of the third pulse duration and/or of the fourth pulse duration to a period duration of the first switching sequence, wherein additionally or alternatively a rotational speed of the second electric motor can be controlled by setting a ratio of the fifth pulse duration and/or of the sixth pulse duration to the period duration of the first switching sequence. An independent control of the first electric motor and of the second electric motor by means of pulse width modulation is made possible in this way.

Preferably, within the first switching sequence the first pulse duration and the second pulse duration are substantially of the same length. In other words, in one preferred embodiment, a ratio of the first pulse duration to the second pulse duration can be, in particular, in the range of 0.9 to 1.1. In this way, it is possible to ensure in a simple manner that the first switching sequence does not go out of phase with the second and/or third switching sequence.

A ratio of the first pulse duration to a period duration of the first switching sequence and/or a ratio of the second pulse duration to the period duration of the first switching sequence can preferably be in each case in the range of 0.4 to 0.6. In particular, the ratio of the first pulse duration to the period duration of the first switching sequence and/or the ratio of the second pulse duration to the period duration of the first switching sequence can be substantially 0.5. In this way, a supply voltage that is as high as possible is provided for the electric motors on average over time.

It also lies within the scope of the invention that, for switching over the half-bridges from their respective first half-bridge position into their respective second half-bridge position, the respective half-bridge is firstly switched from its first half-bridge position into its third half-bridge position and is subsequently switched from its third half-bridge position into its second half-bridge position. Correspondingly, for switching over the half-bridges from their respective second half-bridge position into their respective first half-bridge position, the respective half-bridge can firstly be switched from its second half-bridge position into its third half-bridge position and subsequently be switched from its third half-bridge position into its first half-bridge position. Half-bridge short circuits can be avoided by means of such a switching offset when switching over between the first half-bridge position and the second half-bridge position, or vice versa.

DETAILED DESCRIPTION

FIG. 1shows a conventional electric arrangement2for controlling two electric motors21,22. In order to enable independent controlling of the electric motors21,22with regard to their direction D1, D2of rotation and/or rotational speed, two separate H-bridge arrangements2-1,2-2are provided in previously known solutions.

In this case, a first electric motor21is arranged in a first bridge branch2-10of a first H-bridge arrangement2-1in such a way that it is connected to a first half-bridge23via a first motor contact211and to a second half-bridge24via a second motor contact212. The first half-bridge2-1comprises a first switching element231and a second switching element232, wherein the first motor contact211is connected to an electric path between the first switching element231and the second switching element232. Correspondingly, the second half-bridge24comprises a third switching element241and a fourth switching element242, wherein the second motor contact212is connected to an electric path between the third switching element241and the fourth switching element242.

Analogously to the construction of the first H-bridge arrangement2-1, a second electric motor22is electrically connected to a fifth switching element251, a sixth switching element252, a seventh switching element261and an eighth switching element262in a second H-bridge arrangement2-2.

A first supply terminal28and a second supply terminal29are provided in order to provide a supply voltage V for the electric motors21,22. The first supply terminal28is connected to an electric path between the first switching element231and the third switching element241and also to an electric path between the fifth switching element251and the seventh switching element261. The second supply terminal29is connected to an electric path between the second switching element232and the fourth switching element242and also to an electric path between the sixth switching element252and the eighth switching element262. With regard to their linking to the supply terminals28,29, the first H-bridge arrangement2-1and the second H-bridge arrangement2-2are thus connected in parallel.

In the embodiment of a previously known electric arrangement2as illustrated inFIG. 1, the switching elements231,232,241,242,251,252,261,262are MOSFETs, which are switchable into a closed state and into an open state in each case by means of an external gate voltage signal. In this case, the open state corresponds to a high-impedance state in which the respective MOSFET is not or substantially not conductive in a forward direction between a source terminal and a drain terminal and is designed for blocking an external voltage in the forward direction. By contrast, the MOSFETs in their respective closed state exhibit comparatively good conductivity in the forward direction.

By means of suitable switching of the switching elements231,232,241,242,251,252,261,262, the first electric motor21and the second electric motor22can be driven in each case in a desired direction D1, D2of rotation, wherein a rotational speed of the respective electric motor21,22is additionally settable by means of pulse width modulation. By way of example, if a potential V1that is higher than a potential V2present at the second supply terminal29is present at the first supply terminal28, then the first electric motor21is driven by a current flow I1from the first motor contact211to the second motor contact212if the first switching element231and the fourth switching element242are simultaneously closed while the second switching element232and the third switching element241are open. As a result, the first electric motor21can be driven in one direction D1of rotation, for example to clockwise rotation.

In this case, a rotational speed of the first electric motor21rotating clockwise is settable by means of pulse width modulation by virtue of the first switching element231and/or the fourth switching element242being periodically closed and opened. A resulting rotational speed of the first electric motor21rotating clockwise is all the greater, the greater a ratio of a pulse duration during which the first switching element231and/or the fourth switching element242are/is closed to a period duration of the change between the closed state and the open state of the first switching element231and/or of the fourth switching element242.

In order to drive the first electric motor21to counterclockwise rotation, the second switching element232and the third switching element241are closed and opened in each case simultaneously in a periodic alternation, while the first switching element213and the fourth switching element242are open. If the second switching element232and the third switching element241are closed, a second current flow I2from the second motor contact212to the first motor contact211drives the first electric motor21to counterclockwise rotation in an opposite direction D2of rotation. In this case, a rotational speed of the first electric motor21rotating counterclockwise can in turn be set by means of pulse width modulation.

The second electric motor22is controllable independently of the first electric motor21with regard to a desired direction D1, D2of rotation and/or rotational speed in a corresponding manner by suitable switching of the switching elements251,252,261,262of the second H-bridge arrangement2-2.

FIG. 2illustrates an electric arrangement1according to the invention for independently controlling two electric motors11,12. The electric motors11,12can be DC motors, for example, which are used as adjusting motors for a respective windowpane in an electric window winding device of a motor vehicle. In this case, it may be necessary to control the electric motors11,12independently of one another with regard to their direction D1, D2, D3, D4of rotation and/or rotational speed in order to raise and/or lower both windowpanes independently of one another.

The electric arrangement1comprises a first H-bridge arrangement1-1, which substantially corresponds to the first H-bridge arrangement2-1fromFIG. 1. In this regard, a first electric motor11is electrically connected to a first switching element131, a second switching element132, a third switching element141and a fourth switching element142in the first H-bridge arrangement1-1, wherein the first electric motor11is arranged in a first bridge branch1-10of the first H-bridge arrangement1-1. The first electric motor11is connected to a first half-bridge13via a first motor contact111and to a second half-bridge14via a second motor contact112, wherein the first half-bridge13comprises the first switching element131and the second switching element132, and wherein the second half-bridge14comprises the third switching element141and the fourth switching element142. In this case, the first motor contact111is connected to an electric path between the first switching element131and the second switching element132, and the second motor contact112is connected to an electric path between the third switching element141and the fourth switching element142.

Furthermore, a second electric motor12is connected to a third half-bridge15via a third motor contact121, said third half-bridge comprising a fifth switching element151and a sixth switching element152. In this case, the third motor contact121is connected to an electric path between the fifth switching element151and the sixth switching element152. In addition, the second electric motor12is connected to the first half-bridge13via a fourth motor contact122in such a way that it is electrically connected to the first switching element131, the second switching element132, the fifth switching element151and the sixth switching element152in a second H-bridge arrangement1-2. As shown inFIG. 2, the fourth motor contact122for this purpose is connected to an electric path between the first switching element131and the second switching element132.

The second H-bridge arrangement1-2, in the second bridge branch1-20of which the second electric motor12is arranged, accordingly shares the first half-bridge13with the first H-bridge arrangement1-1, which supplies the first electric motor11. In other words, the first half-bridge13on the one hand together with the second half-bridge14and the first bridge branch1-10forms the first H-bridge arrangement1-1, and on the other hand together with the third half-bridge15and the second bridge branch1-20forms the second H-bridge arrangement1-2. Overall, therefore, two functional H-bridge arrangements1-1,1-2(reference sign1-2is absent inFIGS. 2 and 3) are provided, by means of which the first electric motor11and the second electric motor12are controllable independently of one another.

In this case, the electric arrangement1according to the invention manages with only six different switching elements131,132,141,142,151,152and thus saves two switching elements in comparison with the previously known solution shown inFIG. 1. The production costs of an electric arrangement1for independently controlling two electric motors11,12for example two adjusting motors of a window winding device for a motor vehicle, can be reduced in this way. Moreover, by saving two switching elements, weight can be saved, and valuable structural space, for example on a printed circuit board, can be utilized in a different way.

In the exemplary embodiment inFIG. 2, the switching elements131,132,141,142,151,152are MOSFETs. In further embodiments, the switching elements133,132,141,142,151,152can comprise other semiconductor transistors, for example bipolar transistors and, in particular, IGBTs. Preferably, each of the switching elements131,132,141,142,151,152is switchable into a closed state and into an open state depending on a respective control signal VG1, VG2, VG3, VG4, VG5, VG6.

FIG. 3shows the electric arrangement fromFIG. 2, wherein provision is additionally made of a control unit3for generating the control signals VG1, VG2, VG3, VG4, VG5, VG6for the switching elements131,132,141,142,151,152. The control unit3can be a microcontroller, for example, which provides the control signals VG1, VG2, VG3, VG4, VG5, VG6depending on a respective desired direction D1, D2, D3, D4of rotation and/or rotational speed for each electric motor11,12. In this case, the control unit3can calculate the control signals VG1, VG2, VG3, VG4, VG5, VG6for example from input signals generated by at least one operating element of an electric window winding device.

By way of example, the first electric motor11can be an adjusting motor for adjusting a first windowpane at a first vehicle door and the second electric motor12can be an adjusting motor for adjusting a second windowpane at a second vehicle door. In this case, by means of one or more operating elements arranged for example in the interior of the motor vehicle, a user can control the adjusting motors11,12independently of one another via the electric arrangement1. By way of example, the first adjusting motor11can be driven in the direction D1of rotation and thereby raise the first windowpane. Alternatively, the first adjusting motor11can be driven in the opposite direction D2of rotation in order to lower the first windowpane. In this case, the first electric motor11can be driven in the direction D1of rotation by a current flow I1from the first motor contact111to the second motor contact112, and it can be driven in the opposite direction D2of rotation by an opposite current flow I2from the second motor contact112to the first motor contact111. The first electric motor11and/or the second electric motor12can be for example a DC motor.

At the same time as the driving of the first electric motor11in the direction D1of rotation and/or or in the opposite direction D2of rotation, the second electric motor12, for example for lowering the windowpane, can be driven in one direction D3of rotation by a current flow I3from the third motor contact121to the fourth motor contact122. As an alternative thereto, the second electric motor12, for example for raising the second windowpane, can be driven in an opposite direction D4of rotation by a current flow I4from the fourth motor contact122to the third motor contact121.

In this case, the electric arrangement1also enables a rotational speed of the respective electric motor11,12to be set independently by means of pulse width modulation.

The independent controlling of the two electric motors11,12by means of the electric arrangement fromFIGS. 2 and 3is described in greater detail below.

The half-bridges11,12,13of the electric arrangement1are switchable in each case into a first half-bridge position13-1,14-1,15-1, into a second half-bridge position13-2,14-2,15-2and into a third half-bridge position13-2,14-2,15-2. In this case, in the first half-bridge position13-1,14-1,15-1that one of the switching elements131,141,151which is arranged within the respective half-bridge13,14,15in an electric path between the first supply terminal18and the respective other one of the switching elements132,142,152is closed and the other one of the switching elements132,142,152is open.

A supply voltage V for the electric motors11,12can be applied via a first supply terminal18and a second supply terminal19, between which the half-bridges13,14,15are arranged in a parallel connection. By way of example, a potential V1present at the first supply terminal18can be higher than second potential V2present at the second supply terminal19. In this regard, the first supply terminal18can be connected to a positive pole of an automobile battery, for example, and the second supply terminal V2can contact ground, for example. A difference between the first potential V1and the second potential V2forms the supply voltage V.

In this case, the first switching element131, the third switching element141and the fifth switching element151, which are arranged in the respective half-bridge13,14,15on a side facing the first supply terminal18and facing away from the second supply terminal19, function as high-side switching elements. By contrast, the second switching element132, the fourth switching element142and the sixth switching element152, which are arranged on a side of the respective half-bridge13,14,15that faces away from the first supply terminal18and faces the second supply terminal19, function as low-side switching elements. In this case, the switching elements131,132,141,142,151,152, which are embodied as MOSFETs in the exemplary embodiment, are configured and arranged in the half-bridges13,14,15in such a way that in their respective open state they can block the supply voltage V and in their respective closed state they can conduct a current in a forward direction from the first supply terminal18to the second supply terminal19.

In the respective first half-bridge position13-1,14-1,15-1, the high-side switching elements131,141,151are closed, whereas the low-side switching elements132,142,152are open. By contrast, in the second half-bridge position, that one of the switching elements132,142,152which is arranged within the respective half-bridge13,14,15in an electric path between the second supply terminal19and the respective other one of the switching elements131,141,151is closed, the other one of the switching elements131,141,151being open. In the exemplary embodiment, therefore, the respective low-side switching element132,142,152is closed in the second half-bridge position13-2,14-2,15-2, whereas the respective high-side switching element131,141,151is open in the second half-bridge position13-2,14-2,15-2.

In the third half-bridge position13-3,14-3,15-3, both the high-side switching elements131,141,151and the low-side switching elements132,142,152of the respective half-bridge13,14,15are open. Consequently, each of the half-bridges13,14,15in its third half-bridge position13-3,14-3,15-3overall is in a high-impedance state.

FIGS. 4A-4Hillustrate different switching sequences S1, S2, S3for the three half-bridges13,14,15, with which the two electric motors11,12can be controlled independently of one another in order to bring about the above-described behavior with regard to the respective direction D1, D2, D3, D4of rotation and/or the respective rotational speed. Here in each case there is a time t on an abscissa and the associated half-bridge position13-1,13-2,13-3,14-1,14-2,14-3,15-1,15-2,15-3on an ordinate. The switching sequences S1, S2, S3can be realized for example by means of corresponding sequences of control signals VG1, VG2, VG3, VG4, VG5, VG6for the switching elements131,132,133,134,135,136which are provided by the control unit3.

As illustrated inFIG. 4A, the first half-bridge13, in a first switching sequence S1, is switched periodically into the first half-bridge position13-1for a pulse duration P1and into the second half-bridge position13-1for a second pulse duration P2. In this case, a period duration T extending from the instant t1to the instant t9inFIG. 4Acan correspond for example to a frequency of a few kilohertz.

In the exemplary embodiment illustrated, the first half-bridge13, after the first pulse duration P1, is not directly switched from its first half-bridge position13-1into its second half-bridge position13-2. Firstly, a switchover from the first half-bridge position13-1into the high-impedance third half-bridge position13-3takes place at the instant t4. It is only at an instant t5that a switchover from the third half-bridge position13-3into the second half-bridge position13-2takes place. The comparatively short switching offset between the instants t4and t5in which the first half-bridge13adopts its high-impedance third half-bridge position13-3is provided in order to avoid a half-bridge short circuit. If exactly simultaneous opening of the first switching element131,132and closing of the second switching element132were provided, then in practice there would be the risk of both switching elements131,132of the first half-bridge13being momentarily closed at the same time. A corresponding switching offset is provided between the instants t8and t9when switching over the first half-bridge13from its second half-bridge position13-2into its first half-bridge position13-1.

The first pulse duration P1and the second pulse duration P2are substantially of the same length in accordance with the exemplary embodiment inFIG. 4A, such that the first half-bridge13is in its first half-bridge position13-1and in its second half-bridge position13-2for approximately the same length of time during each period duration T. By way of example, a ratio of the first pulse duration P1to the second pulse duration P2can be in the range of 0.9 to 1.1. In this case, a ratio of the first pulse duration P1to the period duration T and a ratio of the second pulse duration P2to the period duration T can be in each case for example in the range of 0.4 to 0.6. In this case, the first half-bridge13is in the first half-bridge position13-1approximately for one half of each period duration T and in the second half-bridge position13-2approximately for the other half of each period duration T.

At the same time as the first switching sequence S1of the first half-bridge13, for controlling the first electric motor lithe second half-bridge14in a second switching sequence S2and/or for controlling the second electric motor12the third half-bridge15in a third switching sequence S3can be switched between the respective first half-bridge position14-1,15-1, the respective second half-bridge position14-2,15-2and/or the respective third half-bridge position14-3,15-3. Possible switching sequences S2, S3for the second half-bridge14and the third half-bridge15are illustrated by way of example inFIGS. 4B to 4H.

In the case of the second switching sequence S2shown inFIG. 4B, the second half-bridge14is switched from its high-impedance third half-bridge position14-3into its second half-bridge position14-2at the instant t1and remains in the second half-bridge position14-2over the entire period duration T. In particular, the second half-bridge14can remain in its second half-bridge position14-2for a plurality of period durations T of the first switching sequence S1(not illustrated). Between the instants t1and t4and, if appropriate, between corresponding instants in the subsequent periods of the first switching sequence S1, the first switching element131as high-side switching element and the fourth switching element142as low-side switching element are simultaneously closed for the first pulse duration P1. In this case, owing to the supply voltage V, a current flow I1from the first motor contact111to the second motor contact112drives the first electric motor11in the direction D1of rotation. By contrast, the first switching element131is open from the instant t4to the instant t9, wherein the third switching element141also remains open without change, such that the first electric motor11is isolated from the high-side potential V1and is not driven by a current flow from the first supply terminal18to the second supply terminal19.

Between the instants t4and t9, however, as a result of self-induction at the first electric motor11the current flow I1from the first motor contact111to the second motor contact112can be maintained at least partially as freewheeling current. In this case, the freewheeling current can flow in the clockwise direction in the circuit through the first bridge branch1-10, through the fourth switching element142, through the second switching element132, and from there back to the first bridge branch1-10. In this case, the freewheeling current flows through the second switching element132in a reverse direction. This can be made possible for example by an intrinsic backward diode of the MOSFET132. In other embodiments, particularly if the switching elements131,132,141,142,151,152are IGBTs, in order to enable a freewheeling current separate freewheeling diodes can be provided which are respectively connected in antiparallel with one of the switching elements131,132,141,142,151,152, and so a forward direction of the respective freewheeling diode corresponds to a reverse direction of the respective switching element131,132,141,142,151,152.

The second switching element132is closed from the instant t5to the instant t8, such that an n-channel is formed owing to the gate voltage VG2in the MOSFET132. In this way, for the pulse duration P2an active freewheeling is made possible in which the freewheeling current through the second switching element132does not have to overcome a threshold voltage of the intrinsic backward diode and hence can flow through in the reverse direction with lower losses than is the case between the instants t4and t5or between the instants t8and t9.

As a result, through a combination of the first switching sequence S1in accordance withFIG. 4Aand the second switching sequence S2in accordance withFIG. 4B, the first electric motor11is driven in the direction D1of rotation by the current flow I1substantially for half of the time.

FIG. 4Cshows an alternative second switching sequence S2, in which the second half-bridge14is switched from its third half-bridge position14-3into its first half-bridge position14-1at the instant t1and subsequently remains in the first half-bridge position14-1at least over the entire period duration T. The low-side switching elements132,142of the first half-bridge13and of the second half-bridge14are open between the instant t1and the instant t5, such the first electric motor11is isolated from the low-side potential V2and accordingly is not driven by a current flow from the first supply terminal18to the second supply terminal19. By contrast, the second switching element132and the third switching element141are simultaneously closed during the second pulse duration P2, i.e. between the instant t5and the instant t8, such that the first electric motor11is driven in the opposite direction D2of rotation by a current flow I2between the second motor contact112and the first motor contact111. The driving of the first electric motor11in the opposite direction D2of rotation is carried out here periodically with the period duration T in each case for the second pulse duration P2.

Between the second pulses P2, a freewheeling current can in each case circulate in the clockwise direction through the first bridge branch1-10, the first switching element131and the third switching element141. The closing of the first switching element131for the pulse duration P1here in each case enables an active freewheeling.

FIGS. 4D and 4Eshow two possible third switching sequences S3for the third half-bridge15, which are to be understood entirely analogously to the second switching sequences S2for the second half-bridge14as explained above with reference toFIGS. 4B and 4C.

In this regard, the third half-bridge15is switched into its second half-bridge position15-2for a plurality of period durations T in the case of a combination of the first switching sequence S1in accordance withFIG. 4Awith the third switching sequence S3in accordance withFIG. 4D. Between the instants t1and t4and between the respective corresponding instants of the subsequent periods (not illustrated) of the first switching sequence S1, the first switching element131and the sixth switching element152are simultaneously closed, such that the current flow I4from the fourth motor contact122to the third motor contact121drives the second electric motor12actively in the opposite direction D4of rotation for the pulse duration P1, i.e. approximately for half of each period duration T. Between the instants t4and t9and between the corresponding instants of the subsequent periods, a freewheeling current here can circulate in the clockwise direction through the second bridge branch1-20, through the sixth switching element152and—in the reverse direction—through the second switching element132. An active freewheeling can take place here between the instants t5and t8and between corresponding instants in the subsequent periods in each case for the second pulse duration P2.

As an alternative thereto, in accordance withFIG. 4E, for controlling the second electric motor12in such a way that it is driven in the direction D3of rotation, the third half-bridge15is switched into its first half-bridge position15-1for a plurality of period durations T. The second switching element132and the fifth switching element151are simultaneously closed here between the instants t5and t8and between corresponding instants in the subsequent periods of the first switching sequence S1in each case for the second pulse duration P2, such that a current flow I3from the third motor contact121to the fourth motor contact122drives the second electric motor12in the direction D3of rotation. Between these phases a freewheeling current can circulate in the clockwise direction through the second bridge branch1-20, in the reverse direction through the first switching element131and the fifth switching element151, an active freewheeling being made possible in each case for the first pulse duration P1by the closing of the first switching element113.

The second and third switching sequences S2, S3according toFIGS. 4B to 4Ebring about—relative to a predefined first switching sequence S1in accordance withFIG. 4A—operation of the electric motors11,12in their respective direction D1, D2, D3, D4of rotation with a maximum possible rotational speed, since the respective pulse durations P1, P2are utilized completely as supply phases for the drive of the electric motors11,12.

In order to set a respective rotational speed of the electric motors11,12, a method of pulse width modulation can be applied for the second switching sequence S2and/or for the third switching sequence S3. This is shown by way of example inFIGS. 4F to 4H.

In the case of the second switching sequence S2in accordance withFIG. 4F, the second half-bridge14is switched into its second half-bridge position14-2periodically during each first pulse duration P1of the first switching sequence S1for a third pulse duration P3. In this case, the third pulse duration P3is shorter than the first pulse duration P1. In the exemplary embodiment shown inFIG. 4F, the third pulse duration P3between the instants t1and t2, and between the instants t9and t10, is approximately of half the length of the first pulse duration P1of the first switching sequence S1. During the third pulse duration P3, the first electric motor11is driven in each case actively in the direction D1of rotation by a current flow I1, as described above with reference toFIG. 4B. After the third pulse duration P3has elapsed, at the instant t2and respectively at the instant t10(and at corresponding instants in the subsequent periods) the second half-bridge14is switched over into its high-impedance third half-bridge position14-3. Shortly afterward, at the instant t3and t11, respectively, a switchover into the first half-bridge position14-1is now effected. In this case, a switching offset between the instants t2and t3(and between the instants t10and t11, etc.) serves for avoiding a half-bridge short circuit, as explained above with reference to the first switching sequence S1.

Afterward, the second half-bridge14remains in its first half-bridge position14-1until the end of the first pulse duration P1. In the phase between the instants t2and t4, a freewheeling current can circulate in the counterclockwise direction through the first bridge branch1-10, the third switching element141and the first switching element131. Between the instants t3and t4, the closed third switching element141here can enable an active freewheeling. Afterward, i.e. at the instant t4, the second half-bridge14(with a switching offset between the instants t4and t5) is switched into its third half-bridge position14-3for the rest of the period duration T. Alternatively, the second half-bridge14, as illustrated inFIG. 4H, can be switched into its second half-bridge position14-2at the instant t5in order to enable an active freewheeling through the second bridge branch1-20, the fourth switching element142and the second switching element132during the second pulse duration P2.

The rotational speed of the first electric motor11can be controlled by setting a ratio of the third pulse duration P3of the second switching sequence S2to the period duration T of the first switching sequence S1in a range of from 0 to the ratio between the first pulse duration P1and the period duration T. In this case, the rotational speed of the first electric motor11is all the greater, the greater the ratio of the third pulse duration P3to the period duration T since on average over time over a plurality of period durations T the current flow I1is substantially proportional to the ratio of the third pulse duration P3to the period duration T.

In order to drive the first electric motor11in the opposite direction D2of rotation, in a further variant of the second switching sequence S2(not illustrated), the second half-bridge14can be switched periodically into its first half-bridge position14-1in such a way that the second half-bridge14adopts the first half-bridge position14-1at least for a fourth pulse duration P4, during which the first half-bridge13is in its second half-bridge position13-2. In this case, the first electric motor11is driven in the opposite direction D2of rotation for the fourth pulse duration P4by a current flow I2from the second motor contact112to the first motor contact111. Details of the functioning of the drive here are to be understood entirely analogously to the description given above with reference to the drive in the first direction D1of rotation. In this case, the rotational speed of the first electric motor11can in turn be controlled by setting a ratio of the fourth pulse duration P4to the period duration T.

FIG. 4Gshows an excerpt from a third switching sequence S3for driving the second electric motor12in the direction D3of rotation. Here the third half-bridge15is switched into its first half-bridge position15-1periodically in each case for a fifth pulse duration P5, while the first half-bridge13is in its second half-bridge position13-2for the first pulse duration P2. The second electric motor12is driven in the direction D3of rotation in each case for the fifth pulse duration P5, i.e. for example between the instants t5and t6, by the current flow I3from the third motor contact121to the fourth motor contact122.

Between the instants t6and t8the second electric motor2can drive a freewheeling current in the counterclockwise direction through the second bridge branch1-20, the second switching element132and the sixth switching element152, wherein an active freewheeling is made possible by the closed sixth switching element152from the instant t7to the instant t8. In one variant (not illustrated), an active freewheeling can also be made possible during the subsequent first pulse duration P1by the switching of the third half-bridge15into its first half-bridge position15-1.

In order to drive the second electric motor12in the opposite direction D4of rotation, in a further variant of the third switching sequence S3(not illustrated), the third half-bridge can be switched periodically into its second half-bridge position15-2, such that the third half-bridge15adopts the second half-bridge position15-2at least for a sixth pulse duration P6, during which the first half-bridge13is in its first half-bridge position13-1. In this case, the second electric motor12is driven in the opposite direction D4of rotation for the sixth pulse duration P6by a current flow I4from the fourth motor contact122to the third motor contact121. In this case, the rotational speed of the second electric motor12can be controlled by setting a ratio of the sixth pulse duration P6to the period duration T.

The above-described second switching sequences S2for the second half-bridge14, on the one hand, and third switching sequences S3for the third half-bridge15, on the other hand, can be used sequentially or simultaneously in order to drive the first electric motor11and the second electric motor12successively or simultaneously with a desired rotational speed in a desired direction D1, D2, D3, D4of rotation.

It lies within the scope of the invention that the electric arrangement1, over and above the first electric motor11and the second electric motor12, can comprise further electric motors with an assigned further half-bridge in each case. The further half-bridges can in each case comprise at least two further switching elements. Here each of the further electric motors can be arranged in each case in a further bridge branch which together with the first half-bridge13and the further half-bridge assigned to the further electric motor forms a further H-bridge arrangement. In this case, a respective one of the further electric motors can be controlled analogously to the above-described method by the switching of the first and/or second switching element131,132of the first half-bridge13and of the further switching elements of the respectively assigned further half-bridge. In this way, by means of the electric arrangement1it is also possible to drive more than two electric motors simultaneously with in each case a desired rotational speed in a desired direction of rotation in each case.

In particular, in a window winding device for a motor vehicle, at a left front windowpane, at a right front windowpane, at a left rear windowpane and at a right rear windowpane, it is possible to arrange a respective electric motor as adjusting motor for adjusting the respective windowpane. The four electric motors can be arranged in the above-described manner in an electric arrangement1according to the invention. By means of the electric arrangement1, the four adjusting motors can be controlled independently of one another for raising or lowering the respective windowpane.

LIST OF REFERENCE SIGNS