Arrangement for operating an electric motor in a vehicle

Abstract

The invention relates to an arrangement for operating an electric motor, for example an electric motor for actuating a roof component, in a vehicle. Therein, the electric motor is electrically connected via at least two control lines with a motor control unit. The motor control unit is configured to control the electric motor by means of pulse width modulation. The motor control unit is configured to operate a first one of the two drive lines as an inactive line, and to operate a second one of the two drive lines as an active line during control of the electric motor. A switching module associated with the electric motor is configured to connect a terminal of the pole housing of the electric motor with the drive line which is operated as the inactive line during operation of the electric motor. The invention further relates to an electric motor as well as to a method of operating an electric motor, for example an electric motor for actuating a roof component, in a vehicle.

Claims

1. An Arrangement for operating an electric motor, for actuating a roof component, in a vehicle wherein the electric motor is electrically connected with a motor control unit (20) via at least two drive lines; wherein the motor control unit is configured to control the electric motor by means of pulse width modulation; wherein when the electric motor is controlled, the motor control unit is configured to operate a first drive line of the two drive lines as an inactive line and to operate a second drive line of the two drive lines as an active line; and wherein a switching module associated with the electric motor is configured to connect a terminal of a pole housing of the electric motor with the drive line which is operated as the inactive line.

2. The Arrangement according to claim 1, wherein the electric motor is configured for actuating a roof component of the vehicle.

3. The Arrangement according to claim 2, wherein the electric motor is configured as a DC motor .

4. The Arrangement according to claim 3, wherein the electric motor is provided with a circuit for suppressing a brush fire.

5. The Arrangement according to claim 4, wherein the switching module is integrated in at least one of: a motor circuit board and in a housing of the electric motor.

6. The Arrangement according to claim 5, wherein the switching module comprises a field effect transistor .

7. The Arrangement according to claim 6, wherein the switching module comprises a diode .

8. The Arrangement according to claim 7, wherein the switching module comprises at least one of: a bipolar transistor and a relay.

9. An Electric Motor for a vehicle for actuating a roof component, comprising: at least two terminals for connecting a first and a second drive line; wherein the electric motor is configured to be controlled via the terminals by means of pulse width modulation; wherein when the electric motor is controlled, a first drive line of the two drive lines is operable as an inactive line, and a second drive line of the two drive lines is operable as an active line; and wherein a switching module is associated with the electric motor, the switching module being configured to connect a terminal of the pole housing of the electric motor with the drive line which is operated as the inactive line during operation of the electric motor.

10. A Method of operating an electric motor for actuating a roof component, in a vehicle, comprising: controlling the electric motor (M) by means of pulse width modulation via at least two drive lines; operating, when the electric motor (M) is controlled, a first drive line of the two drive lines as an inactive line, and a second drive line of the two drive lines as an active line; and connecting, by a switching module, a terminal of a pole housing of the electric motor with the drive line which is operated as the inactive line during operation of the electric motor.

11. The Arrangement according to claim 2, wherein the electric motor is configured for moving at least one of: a roof-light and a roof-blind.

12. The Arrangement according to claim 3, wherein the electric motor is configured as a brushless DC motor.

13. The Arrangement according to claim 4, wherein the circuit comprises a capacitive voltage divider.

14. The Arrangement according to claim 6, wherein the switching module comprises a metal-oxide field effect transistor, and wherein a first and a second switching module are provided for the first and second drive lines, respectively.

15. The Arrangement according to claim 7, wherein the switching module comprises a rectifier formed from the diode and a resistor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the following, the invention will be explained in more detail below with reference to the accompanying drawings. Therein:

[0037] FIG. 1 shows an embodiment of the arrangement;

[0038] FIG. 2 shows a detail view of the embodiment of the arrangement; and

[0039] FIG. 3 shows a further detail view of the embodiment of the arrangement.

DETAILED DESCRIPTION

[0040] With reference to FIGS. 1 to 3 an embodiment of the arrangement is detailed.

[0041] In the embodiment, the arrangement 10 comprises a control unit 20. In further embodiments, the control unit does not need to be comprised by the arrangement 10, but may also rather be connected thereto as an external unit.

[0042] A motor circuit board 12 is further provided.

[0043] An electric motor M and a switching module 14 connected thereto are coupled to the motor circuit board 12.

[0044] In this embodiment the electric motor M is configured as a brush motor.

[0045] According to further embodiments, the electric motor may be configured as the BLDC motor.

[0046] The motor board 12 further comprises terminals 12a, 12b, which are configured as supply terminals. It means that electric voltage is supplied via terminals 12a, 12b for operating the electric motor M. Furthermore, auxiliary signals may be provided, which are, however, not relevant in the following description.

[0047] In the embodiment, the motor circuit board, the electric motor M and the switching module 14 are arranged within a same housing, or are otherwise arranged integrated with each other. The terminals 12a, 12b are in this case accessible from the exterior, or can be connected with external units.

[0048] The terminals 12a, 12b are each connected with one of two drive lines A, B.

[0049] The control unit 20 generates signals for operating the electric motor M via pulse width modulation (PWM). Thereby, the signals are transmitted over a drive line A as an “active line” while the other drive line B is operated in this case as an “inactive line”.

[0050] The choice of the active and inactive line, respectively, is determined depending on the direction of rotation in which the electric motor M is operated. The respectively other drive line B operated as an inactive line is connected to ground, i.e., it is grounded.

[0051] In the embodiment, the electric motor M comprises a circuit for suppressing the brush fire during operation. This circuit comprises, according to the embodiment, a capacitive voltage divider 18 having each one capacitor per terminal. This voltage divider is connected with a pole housing of the electric motor via a pole housing terminal 15. The pole housing is thus arranged between the two drive lines and is continuously held at half the voltage level of the PWM signal.

[0052] In an embodiment, in which the electric motor is configured as a BLDC motor, further circuits may be implemented, which may lead to electromagnetic interference or which damp such interference.

[0053] In the arrangement 10 of the embodiment, the switching module 14 is provided in order to connect the pole housing automatically with that drive line A, B, which is operated as an inactive line.

[0054] Expressed more generally, an active PWM detector is provided in this regard, namely detection circuit 17. The detection circuit 17 is connected with the drive lines A, B and serves to detect, which drive line A, B is currently operated as the inactive line. In dependence from the result of the detection, a switching device, such as a semiconductor switch 16, is controlled in order to connect the pole housing terminal 15 with the inactive line.

[0055] Such a circuit is shown in a specific embodiment in FIG. 3. Since the circuit is arranged symmetrically, just one half of it is provided with reference numerals. The other half is arranged likewise and is also shown in FIG. 3.

[0056] In the embodiment, a diode D.sub.1 and a capacitor C.sub.1 jointly form a rectifier. The rectifier is coupled with the first drive line A. A resistor R.sub.1 arranged between the diode D.sub.1 and the capacitor C.sub.1 thereby serves to limit a current. Moreover, there is provided a further resistor R.sub.2 via which the capacitor C.sub.1 may be discharged.

[0057] Between the resistor R.sub.1 and the capacitor C.sub.1 there is provided a connection with the gate-input of a semiconductor switch T.sub.1 arranged in the second drive line B.

[0058] In a first case, in which the first drive line A is operated as the active line during PWM control of the electric motor M, the gate of the semiconductor switch T.sub.1 is at the voltage level provided via drive line A. In a common PWM control, this corresponds to about 12 V.

[0059] According to further embodiments, other voltage levels may be provided.

[0060] A transistor of the semiconductor switch T.sub.1 is thus switched into the conductive state and the pole housing terminal 15 is consequently connected with the drive line B via a further capacitor C.sub.2 and a further resistor R.sub.3, wherein the drive line B is operated in this case as the inactive line.

[0061] At the same time the connection between the pole housing terminal 15 and the drive line A is disconnected in this case, since in the symmetrically arranged branch, the gate of the transistor provided therein is not supplied with a gate voltage in this case.

[0062] The further capacitor C.sub.2 in the connection between the drive line B and the pole housing terminal 15 serves to avoid possibly occurring short currents. The upstream resistor R.sub.3 serves to damp optionally occurring oscillations, which may be generated between the interference suppression capacitors and the supply line.

TABLE-US-00001 List of Reference Numerals 10 arrangement 12 motor circuit board 12a, 12b terminal 14 switching module 15 pole housing terminal 16 semiconductor switch 17 detection circuit 18 capacitive voltage divider 20 control unit A drive line B drive line C.sub.1, C.sub.2 capacitor D.sub.1 diode M electric motor R.sub.1, R.sub.2, R.sub.3 resistor T.sub.1 semiconductor switch, MOSFET