CONTROL UNIT FOR AN ELECTRIC MOTOR, IN PARTICULAR FORA FAN MOTOR
The invention provides a control unit for at least one electric motor, wherein the control unit performs open-loop or closed-loop control of the motor speed of the electric motor in such a way that in the case of control values in specific ranges which are typical of a fault when the setpoint value is being predefined, such a fault being, for example, a line break, a voltage failure or a short circuit, the control unit drives the motor with a predefined setpoint value which differs from the current control value.
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The present application is a continuation of U.S. patent application Ser. No. 12/299,426, which was filed on Nov. 30, 2008 which claims the benefit of priority of International Patent Application No. PCT/EP2007/054301, filed on May 3, 2007, which in turn claims priority to German Patent Application No, 20 2006 007 136.9, filed May 4, 2006, The entire text of International Patent Application No. PCT/EP2007/054301 and German Patent Application No. 20 2006 007 136.9 are hereby incorporated herein by reference in their entireties.
DESCRIPTIONThe invention relates to a control unit for an electric motor. Such control units are used to perform open-loop or closed-loop control of the motor speed. In many cases, in particular in fan applications, the motor speed is lowered according to demand in order to reduce the consumption of electric power. In the case of a fan, not only the power demand but also the flow noise are highly dependent on the motor speed, Referring to
In addition to the energy demand, the noise can therefore also be significantly reduced if motor-speed-controlled fan motors are used and if open-loop control of the motor speed and therefore of the air line is performed according to demand. The motor speed of a fan can be influenced in different ways as a function of the types of motor used. In the case of direct current motors, open-loop control of the motor speed is performed by means of the motor voltage. The control unit can predefine the motor voltage with a clocked voltage converter (chopper) or by means of a controlled rectifier, For universal motors, the amplitude of the alternating voltage can be set by means of a phase angle controller. In the case of a brushless motor (also referred to as BLDG or electronically commutated motor, referred to as EC motor), the control unit performs the electronic commutation. The control unit can additionally influence the motor voltage and as a result the motor speed through corresponding clocking of the transistors in the commutation electronics. In the case of asynchronous motors, either the frequency and the amplitude of the motor voltage are predefined with a frequency converter, or in the case of cost-effective systems, in particular in the case of fan drives, only the motor voltage is changed, for example, by means of a phase angle controller (referred to as slip controller).
The desired motor speed is usually defined by means of superimposed open-loop control. The setpoint value of the motor speed is often transmitted with an analogue value (for example 0-10 V) or with a pulse-width-modulated, digital value (PWM).
The present invention is therefore based on the object of configuring the input characteristic of the control unit in such a way that in the case of such a fault the motor continues to operate with a predefined motor speed. In the case of a fault such as a line break or a short circuit in the control line or in the case of the failure of the superimposed controller, the probability is high that the control signal x will record the value 0% or 100%,
According to the invention, the customary input characteristic is therefore changed according to
In one advantageous embodiment, the controller additionally outputs a warning in the case of such a fault. This warning can be output by means of a visual or audible signal, by means of an analogue or digital electronic signal or by means of a commutation bus, for example, CAN bus.
In the figures:
A setpoint value which differs from the maximum (100%) setpoint value of the motor speed can also be used in the event of a fault. In some cases, a reduced motor speed is sufficient for cooling in a normal situation, and the maximum motor speed (100%) is provided only for specific exceptional situations, for example for the failure of one of the fans which operate in parallel.
In order to implement an input characteristic curve according to
In a further refinement of the invention, the input characteristic curve is implemented using an electronic analogue circuit.
F is here the predefined setpoint value for the fault. If this value is, for example, 75%, as in
This circuit can be supplemented with a warning output (W), as illustrated in
Referring to
As one example, a brushless DC motor that incorporates aspects of the invention disclosed herein can be used to spin one or more hard disks in operative relation to at least one read/write head inside of a clean room environment that is manufactured to HIM industry contamination standards. As another example, the motors disclosed herein can be used to move storage media in other information storage devices such as, for example, an optical disk drive, a magneto-optical disk drive, a tape drive or a VCR.
Claims
1-14. (canceled)
15. A cooling fan, comprising:
- a housing;
- a brushless DC motor mounted in the housing;
- a fan wheel operatively engaged with a rotor of the brushless DC motor, wherein the fan wheel is adapted to rotate when the brushless DC motor is operated in order to create a flow of cooling air;
- a motor controller mounted in the housing in a fixed relationship with the brushless DC motor, wherein the motor controller is adapted (a) to cause the rotor and the fan wheel to rotate at a nonzero speed if the magnitude of a control signal is in a range of values associated with a fault condition and (b) to stop rotation of the rotor and the fan wheel if the control signal is between a nonzero first threshold value and a second threshold value greater than the first threshold value.
16. The cooling fan of claim 15, wherein the range of values associated with the fault condition is a range from zero to the first threshold value.
17. The cooling fan of claim 15, wherein the control signal is one of a pulse-width modulated signal and a voltage.
18. The cooling fan of claim 15, wherein control signal is an analog voltage signal.
19. The cooling fan of claim 18, wherein the range of values associated with a fault condition includes a value that represents one of zero volts and a voltage identical to a supply voltage.
20. The cooling fan of claim 15, wherein the control signal is a modulated signal and the range of values associated with a fault includes a value associated with a signal modulated 0% and a value associated with a signal modulated 100%.
21. The cooling fan of claim 15, comprising an analog-to-digital converter adapted to convert an analog control signal into a digital control signal.
22. The cooling fan of claim 15, wherein the first threshold value is one of 0.5 volts and 5% modulation.
23. The cooling fan of claim 22, wherein the second threshold value is one of 1 volt and 10% modulation.
24. The cooling fan of claim 23, comprising a further circuit to generate a warning signal if the control value indicates a fault.
25. The cooling fan of claim 24, wherein the further circuit generates one of a visual warning signal, an audible warning signal, and a combination thereof.
Type: Application
Filed: Jan 31, 2012
Publication Date: May 23, 2013
Applicant: Papst Licensing GmbH & Co. KG (St. Georgen)
Inventor: Andras Lelkes (Bad Durrheim)
Application Number: 13/363,028
International Classification: H02P 6/08 (20060101);