CONTROL OF A FAN MOTOR FOR AN IMPROVED EMC BEHAVIOR

Abstract

A method is provided for electrically driving a motor having a plurality of phase windings such that EMC (electromagnetic compatibility) is improved and the running performance of the motor is simultaneously kept constant. At least one of the phase windings is not supplied with a current pulse during a complete revolution of the rotor, or at least one switchable electrical resistor is switched on, for at least one subsequent commutation phase by means of an electrical switching element, if the detected rotor speed is greater than the specified target speed.

Claims

1. A method for electrically driving a motor, in particular a fan motor, having a plurality of phase windings, wherein the motor has means for detecting a rotor speed and/or a rotor position of a rotor of the motor, comprising: applying current pulses alternately to individual phase windings by means of drive electronics of the motor; during a complete revolution of the rotor, not supplying a current pulse to at least one of the phase windings, if a detected rotor speed is greater than a specified target speed.

2. The method according to claim 1, further comprising: constantly detecting the rotor speed; and suspending the power supply on one of the phase windings for a subsequent commutation phase, if the rotor speed is greater than the specified target speed.

3. The method according to claim wherein: no more than half the phase windings are not supplied with a current pulse during the complete revolution of the rotor, if the detected rotor speed is greater than the specified target speed.

4. A method for electrically driving a motor, in particular a fan motor, having a plurality of phase windings, wherein the motor has means for detecting a rotor speed and/or a rotor position of a rotor of the motor, comprising: applying current pulses alternately to individual phase windings by means of drive electronics of the motor; and at least one switchable electrical resistor of the drive electronics is switched on for at least one subsequent commutation phase by means of an electronic switching element of the drive electronics, if the detected rotor speed is greater than a specified target speed.

5. The method according to claim 4, wherein: a state of the electronic switching element is left unchanged during a commutation phase.

6. The method according to claim wherein: a current of the current pulse through the phase winding is reduced by means of the at least one switchable electrical resistor during the at least one subsequent commutation phase for reducing the rotor speed.

7. The method according to claim 4, wherein: the at least one switchable electrical resistor of the drive electronics comprises a plurality of switchable electrical resistors connected in series; and the plurality of switchable electrical resistors are individually switched on and/or short-circuited by means of the electronic switching element as a function of the difference between the determined rotor speed and the specified target speed, thereby regulating the rotor speed.

8. The method according to claim 4, wherein: the current pulse has a maximum current that is applied to at least one of the phase windings during at least one commutation phase when the motor is started.

9. The method according to claim 4, wherein: for rough adjustment of the rotor speed during a complete revolution of the rotor, at least one of the phase windings is not supplied with a current pulse, if the detected rotor speed is greater than the specified target speed; and for fine adjustment of the rotor speed, the at least one switchable electrical resistor is switched on for at least one subsequent commutation phase by means of the electronic switching element, if the detected rotor speed is greater than the specified target speed.

10. A motor, in particular a fan motor, comprising: a plurality of phase windings; means for detecting a rotor speed and/or a rotor position of a rotor of the motor; and drive electronics; wherein the motor is designed for being driven by means of a method according to claim 1.

11. A fan comprising a motor according to claim 10.

12. The method according to claim 7, wherein: the electronic switching element comprises a plurality of electronic switching elements operable to individually switch on and/or short circuit the plurality of switchable electrical resistors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the drawings:

[0027] FIG. 1: shows a circuit diagram for driving electronics of a motor,

[0028] FIG. 2: shows the timing based on a diagram for a method for driving a motor with slot shutdown, and

[0029] FIG. 3: shows a further timing based on a diagram for a method for driving a motor by means of reducing a current using switched on series resistors.

DETAILED DESCRIPTION OF THE INVENTION

[0030] FIG. 1 shows a circuit diagram of driving electronics 10 or a section of the driving electronics 10 for a motor 100. The driving electronics 10 has two substantial circuit portions. A first circuit portion consists of a bridge circuit or an H-bridge, which is integrated into an integrated circuit (IC) 15. A second circuit portion consists of a series circuit of switchable electrical resistors 12, which are switched by means of electronic switching elements 13. The resistor network of the switchable electrical resistors 12 connected in series is connected in series to the H-bridge.

[0031] The H-bridge or the IC 15 is always controlled with full load or with a maximum specified current for driving the motor 100 according to the invention. For fine adjustment, electrical resistors 12 can be switched on by means of the electronic switching elements 13 during individual commutation phases, in order to reduce the effective current of the current pulse 30 through a phase winding 14 of the stator of the motor 100 and thus reduce the rotor speed (T.sub.actual), if it exceeds the specified target speed (T.sub.target).

[0032] A slot interruption can be envisaged for rough adjustment. In this case, the current pulses 30 through phase windings 14 are omitted during individual commutation phases. If the detected rotor speed (T.sub.actual) exceeds the specified target speed (T.sub.target), the current pulse 30 can be applied through a phase winding 14 by means of rough adjustment, for example in a subsequent commutation phase.

[0033] FIG. 2 shows a diagram showing the output signal 31 of the Hall effect sensor and the current path I of the individual current pulses 30 through the phase windings 14. The diagram in FIG. 2 is in this case based on the example of a rough adjustment. For example, the current pulse 30 has been interrupted during the commutation phase t4 in the example shown in FIG. 2. By means of the method for driving the motor 100 it has been determined during the commutation phase t3 that the rotor speed (T.sub.actual) is greater than the specified target speed (T.sub.target), and has thus been decided to omit or interrupt the current pulse 30 in the subsequent slot t4 or in the subsequent commutation phase. As a result of constantly checking the rotor speed (T.sub.actual), it has in turn been determined during the commutation phase t4 that the rotor speed (T.sub.actual) has got closer to the specified target speed (T.sub.target) and the current pulse 30 has therefore been reinstated during the commutation phase t5.

[0034] With regard to the rough adjustment, it should be noted that the method envisages interrupting or omitting the current pulse 30 during a complete revolution of the rotor for as few commutations phases as possible, particularly preferably only during one commutation phase.

[0035] FIG. 3 shows a corresponding diagram showing the outcome resulting from a fine adjustment based on switching on electrical resistors 12. In the example shown in FIG. 3, the effective current through the phase windings has been reduced during the commutation phases t4 and t5 by electronic resistors 12 being switched on by means of the electronic switching elements 13. This reduces the rotor speed (T.sub.actual) by means of fine adjustment. In the example shown in FIG. 3, the electrical resistors 12 have not been closed or short-circuited by means of the electronic switching elements 13 during the commutation phases l to t3.

REFERENCE LIST

[0036] 100 motor [0037] 200 fan [0038] 10 driving electronics [0039] 11 means for detecting the rotor speed [0040] 12 electrical resistor [0041] 13 electronic switching element [0042] 14 phase winding [0043] 15 integrated circuit [0044] 30 current pulse [0045] 31 output signal of the Hall effect sensor [0046] 32 microprocessor