FI114694B - Method and apparatus for determining the rotor position of an elevator motor - Google Patents

Abstract

A method and an apparatus for determining the position of the rotor of a synchronous motor (1) used as an elevator motor, in which method an alternating current of a certain frequency is fed into the stator of the motor and the vibration of the machine is measured as a function of the rotor angle, and the position of the rotor (11) is determined by utilizing the said vibration.

Description

114694

METHOD AND EQUIPMENT FOR DETERMINING THE ROTOR POSITION OF A LIFT MOTOR

The present invention relates to a method according to the preamble of claim 1 and to an apparatus according to the preamble of claim 5 for determining the rotor position of an elevator motor.

The torque of the synchronous motor is proportional to the angle difference, i.e. the rotor angle, between the magnetic field of the rotor and the magnetic field of the stator. The torque ίο is maximum when the rotor angle is 90 ° and decreases with the sinusoidal function as the rotor angle changes. The torque curve for elevator drive synchronous motors is a nearly sinusoidal function of the rotor angle. The purpose of the elevator motor control system is to keep the torque at its maximum point.

15

The rotor positioning methods used today are not suitable for flat surface magnet motors, for example, for machine-roomless elevators, placed in a shaft, where the motor inductances Lq and Ld are equal. Known methods for surface magnet motors 20 are based on torque to angle. In elevator operation, they create safety and comfort problems.

:. . One method of determining the rotor position of the elevator synchronous motor rotor J '' · 'is disclosed in WO-A2-02 / 065139, which allows the rotor to be lowered! 25 absolute angular position with rotor stopped by monitoring stator iron saturation. In the method, an alternating current is supplied to the stator, having a given frequency and phase angle, samples of the applied current and the resulting voltage at certain intervals, and calculating the inductance of the stator in question. voltages and currents. Thereafter, the phase angle is incremented a number of times over a 30 360 degree rotation, and the feed, sampling, and counting are repeated to: 'obtain a certain number of calculated stator inductances. The position of the d-, · | · axis relative to the stator is then determined from the minimum of the stator inductance values:. Ko. the method is relatively complex. It is an object of the present invention to overcome the drawbacks of the prior art and to provide a novel arrangement for determining the position of the rotor of a 2 114694 elevator motor without moving the rotor and using relatively low magnetization.

The system according to the invention is mainly based on the feature of the axial motor 5 that it tends to act as a loudspeaker when the rotor and the stator move along the shaft. In the invention, the angular position of the rotor is detected without opening the brake by applying a current of about 50 ... 200 Hz to the motor and measuring the vibration of the machine as a function of the rotor angle.

In detail, the features of the method and apparatus of the invention are set forth in the appended claims.

The invention particularly extends the applications of permanent magnet synchronous motor drives for use in elevators without angular feedback. Furthermore, the arrangement according to the invention is an advantageous way of finding the rotor angle. In addition, the invention is safe because the brakes do not have to be opened and the correct angle is found more reliably than by known methods. In addition, the method of the invention is relatively easy to automate because the elevator does not move, requiring less control and protection.

The invention will now be described in more detail by way of example:. ·, With reference to the accompanying drawing, in which; Figure 1 is a simplified schematic view of the invention

• »i i I

apparatus for determining the rotor angle of the elevator motor.

• *

The apparatus according to Fig. 1 comprises a flat axial synchronous motor having a permanent magnet rotor 11 and a stator 12 driven by a frequency converter 2, which can be located in the elevator shaft and which is driven by a frequency converter 2. The frequency converter is controlled by: a control unit 3.

In the invention, the angular position of the rotor is detected without opening the brake by applying a current of about 50 ... 200 Hz to the motor and measuring the vibration of the machine as a function of the rotor angle 35.

3, 114694

The movement on the shaft is maximum when the stator current is parallel to the d-axis, which means that the stator and rotor have maximum pull and thrust (arrows) but no torque. If the current is parallel to the q axis, the torque will be at its maximum but the thrust and thrust will be at its minimum.

5 When using AC 50 ... 200 Hz, the motor noise varies greatly depending on the position of the rotor. If the frequency is close to the resonant frequency, the variation of the sound amplitude can be tens of dB.

ίο By using acoustic feedback or acceleration feedback, it is possible, for example, to adjust the angle of the resolver. By adding a very simple microphone (speaker) 4 or an accelerometer mounted on the motor body, the adjustments can be automated by looking for the minimum signal. The magnetizing current can be low, even just a few hundred mA, and the motor brake 15 can be kept closed.

The invention allows the maximum torque angle to be found, but its direction cannot be unambiguously indicated. To do this, it is possible to release the brake and check the direction of torque when starting.

20

It will be apparent to one skilled in the art that various embodiments of the invention are not limited to the above example, but may vary; t within the scope of the following claims. Instead of a current signal, a voltage signal can be used, and the direction of the current is estimated by the motor; 25 parameters (resistance, inductance).

»»

Claims (6)

A method for determining the position of the rotor (11) of a synchronous motor (1) operating as a lift motor, in which a method of alternating current or voltage of a certain frequency is measured to the motor stator and the magnitude generated by the input alternating current or voltage. , whereby the position of the rotor is determined, characterized in that the vibrations of the machine as a function of the rotor angle are measured in the method 10 and the position of the rotor (11) is determined by means of the vibrations. 2. A method according to claim 1, characterized in that the vibrations are measured with a microphone arranged at the body of the motor or an accelerometer with which a feedback coupling is created. Method according to claim 1, characterized in that a minimum signal is sought in the method, whereby it is possible, for example, to indicate the maximum torque angle. 20 Method according to Claim 1, characterized in that in the method a maximum signal is sought, whereby it is possible to indicate, for example, the min torque angle, and j | the maximum torque angle is obtained by a phase shift of ·: ··: 90 °. j ·. ··. Apparatus for determining the position of the rotor (11) of a synchronous motor (1) operating as a lift motor, comprising equipment for which an alternating current or voltage of some; Frequency is measured at the motor stator and a unit by which the X: magnitude generated by the input AC or voltage is measured, characterized in that the device comprises means measuring the vibration of the machine as a function of the rotor angle, which vibration is used to determine »» ;;; Position of the rotor (11). 6 114694 6. Device according to claim 5, characterized in that the device is provided with a microphone (4) arranged at the body of the motor or an acceleration sensor which measures the vibrations and with which an feedback coupling is created.