EP1016208A1

EP1016208A1 - Electronic control for a single-phase synchronous motor, single-phase synchronous motor and process for operating it

Info

Publication number: EP1016208A1
Application number: EP97908165A
Authority: EP
Inventors: Dietmar Kern; Jan Dijkstra
Original assignee: AEG Hausgeraete GmbH
Current assignee: AEG Hausgeraete GmbH
Priority date: 1996-03-06
Filing date: 1997-03-03
Publication date: 2000-07-05
Also published as: WO1997033364A1

Abstract

According to the invention the electronic control has a power section (7) for a single-phase synchronous motor (2) with a permanent magnet rotor, in which there are means (1) for detecting the position of the permanent magnet rotor and means (3, 4, 5, 6, 7) for the control of at least one driving coil depending on the position of the permanent rotor. Thus a single-phase synchronous motor can be reliably started in a given direction of rotation without a commutator and thus powers of up to about 5 kW can be developed with high efficiency. This also facilitates self-synchronisation because the control regulates the windings in accordance with the detected position of the rotor, while it is possible to adapt the motor to an adjustable rated power on the user's side and the current operating conditions via the pulse height and/or width. The means for detecting the rotor position may be optical, magnetic and/or inductive, e.g. a Hall effect sensor.

Description

description

Electronic control for a single-phase synchronous motor, single-phase synchronous motor and method for operating a single-phase synchronous motor

The invention relates to an electronic control with a power unit for a single-phase synchronous motor with a permanent magnet rotor, a single-phase synchronous motor and a method for operating a single-phase synchronous motor.

In a domestic appliance, for example a vacuum cleaner, drive motors are desired which have to be distinguished by their particularly compact construction, high efficiency and increasingly better recyclability. A universal motor usually used for this purpose has the disadvantage that it is comparatively unreliable, less energy-efficient, noisy and only inadequately recyclable.

There are also known synchronous motors used in domestic appliances, but their controllability can only be used with a fixed output (speed) (cf. EP-A-0 682 404, DE-A-42 23 208, DE-A-44 07 850 and DE-A-44 10 005).

CONFIRMATION COPIT The invention is therefore based on the object of specifying an electronic control for a single-phase synchronous motor, a single-phase synchronous motor and a method which is related to that with the synchronous motor achievable efficiency, its noise, its reliability and its costs have a positive effect.

This object is achieved according to the invention by an electronic control with a power unit for a single-phase synchronous motor with a permanent magnet rotor, means for detecting the position of the permanent magnet rotor and means for controlling at least one drive coil depending on the position of the permanent rotor being provided .

In this way it is achieved that a single-phase synchronous motor with a permanent magnet rotor without a commutator starts reliably with a defined direction of rotation and powers of up to about 5 kW can be developed with high efficiency. This also enables self-synchronization because the controller controls (regulates) the windings according to the detected position of the rotor, with the pulse height and / or the pulse width adapting the motor to a user-adjustable target power and the current one Operating conditions are given. The means for detecting the rotor position can be optical, magnetic and / or inductive, such as a Hall sensor. It is particularly important for the correct operation of the single-phase synchronous motor that the permanent magnet rotor starts with a defined direction of rotation, it being comparatively easy to control the permanent magnet rotor when it is in motion. It is more difficult to set the correct, predetermined direction of rotation based on the standing permanent magnet rotor. In order to ensure this, the electronic control is designed in such a way that a means for slowly reversing the polarity of the magnet direction is provided in order to generate a wobble of the permanent magnet rotor. In this way, the rotor is alternately moved in one direction and in the other, so that the control, once it has detected the current direction of rotation of the rotor, the rotor according to its position and its detected direction of rotation to start the single-phase Can control synchronous motor.

Further or alternatively, the electronic control can have a direction of rotation determination device, a speed limiter and / or a current limiter. These measures also contribute to the safe operation of the single-phase synchronous motor.

If the electronic control has a voltage supply device with a rectifier and a speed controller, the power required to operate the single-phase synchronous motor can first be provided by an electrical one AC network can be removed. This power is then rectified and, depending on the power to be provided by the motor, the speed of the motor is regulated by specifying the voltage applied to the stator windings. In this case, the voltage can be specified as a trigonometric function, the effectiveness of which is set on the rotor via the amplitude, frequency and, if appropriate, phase section as a function of the detected rotor position. Alternatively, a pulsed control can also be provided, which is set accordingly via the pulse height and / or the pulse width.

Further advantageous embodiments of the invention can be found in the remaining subclaims.

A synchronous motor according to the invention results from the subject matter of claims 14 and 15.

A method according to the invention for operating the single-phase synchronous motor is specified in patent claims 16 and 17.

Embodiments of the invention are explained in more detail with reference to the drawings.

Show:

Fig. 1 is a block diagram of an electronic Control device for a single-phase synchronous motor;

FIG. 2 shows a circuit diagram of a control power stage of the control device according to FIG. 1;

3 shows a voltage supply device of the control device according to FIG. 1;

Fig. 4 is a circuit diagram of a first alternative

Power level of the control device according to Fig. 1; and

Fig. 5 is a circuit diagram of a second alternative

Power level of the control device according to FIG. 1.

1 shows a block diagram of an electronic control device for a single-phase synchronous motor 2. It should be noted here that although a control device is spoken of, because of the technical destination of this control device it should actually and actually be technically correct to speak of a regulation of the single-phase synchronous motor.

The single-phase synchronous motor 2 requires an electronic commutator. This commutator comprises a sensor 1 which is designed as a pulse pickup and which sition of the permanent magnet rotor of the single-phase synchronous motor 2 is detected. The signals from the sensor 1 are fed to a pulse generator and phase shifter device 3 of the control device. Furthermore, a direction of rotation determiner 4, a speed limiter 5 and a current limiter 6 are provided. The output signals of the pulse generator and phase shifter device 3 are fed to a power stage 7, which is followed by the drive coils of the single-phase synchronous motor 2. In this way, the one-phase synchronous motor 2 is reliably started with a defined direction of rotation. The power of such a single-phase synchronous motor 2 is designed up to 5 kW. Furthermore, a self-synchronization of the motor 2 is carried out via the setting of the pulse height and / or pulse width as a function of the detected position of the rotor, so that an adaptation of the motor power to the actual operating conditions, for example in the case of a vacuum cleaner, the change from tile or parquet flooring ¬ on carpets and, on the other hand, to a target performance specified by the user.

The sensor 1 can be designed as a bipolar Hall generator Hall 1 (FIG. 2), which converts the position of the permanent magnet rotor into a high value or a low value, which depends on the polarity of the magnetic field. The driver signal for obtaining a magnetic field is then generated via a driver of power stage 7 so that the permanent magnet rotor on the one hand thrusts into the desired direction of rotation and, on the other hand, a push of appropriate strength.

Alternatively, the direction of rotation signal can also be derived either directly from several or a single drive coil, part of a drive coil or a sensor coil provided separately from the drive coil.

In the exemplary embodiment according to FIG. 2, the driver has a simple NAND gate for this. In addition to the pulse of the Hall generator, this NAND gate also generates a pulse rotated by 180 °. Both pulses are required in order to ensure a safe start in the desired direction of rotation. In a particularly advantageous manner, the direction of rotation is determined by the positioning of the sensor 1 (the Hall generator). In the exemplary embodiment, the sensor 1 is positioned in the direction of rotation in the range from 10 to 30 °, for example approximately 15 °, from the north-south magnetic axis.

Furthermore, a starting aid, a so-called wobble, is provided in the present exemplary embodiment according to FIG. 2. This wobble is necessary if, under certain conditions, the permanent magnet rotor cannot be started. With the help of the wobble, the permanent magnet rotor is made to "wiggle" as a result of a slow reversal of the polarity of the magnet direction. As soon as this wobble movement begins, the actual control circuit, consisting of sensor 1, driver and phase shifter device 3, which take over further control. For this purpose, a pulse transfer circuit then replaces the impulse of the starting aid with a corresponding impulse from the Hall generator.

If the motor has a higher power, the counter-electromotive force generated by the magnetic field can cause a current overload of the power transistors of power stage 7. A so-called current window is determined by means of a second sensor 2, which can also be designed as a Hall generator and which is offset from the first sensor 1 by approximately 100-140 °, preferably 120 ° in the direction of rotation. A currentless time is then provided between the pulses of the Hall generators.

When starting the single-phase synchronous motor 2, an excessively high current may flow. In order to limit this high current, a current limiter 6 is provided which switches two, for example, NAND gates as switches via the driver in such a way that, in the event of an overload, all the power transistors of the power stage 7 are switched off.

The possibilities for actually realizing the detection of the position of the permanent magnet rotor, ie converting the position of the permanent magnet rotor into control signals for the drive coils can be found within the scope of the invention. can also be realized by a variety of other logic circuits. This includes, for example, software implementation with a microprocessor. In this case, it can also be provided, for example, that the microprocessor controls the power stage in such a way that a defined, increased starting torque is achieved to improve the starting behavior. This is possible, for example, by allowing a defined, increased starting current. The microprocessor can accordingly control semiconductor valves arranged in the power stage. Alternatively, an increased starting current can also be generated by the controlled discharge of a capacitor. Due to the short-term increase in the starting current in the range from approximately 100 μs to the millisecond range, it is not necessary to generally oversize the motor for the actual operating state. The increased starting current, for example, is three times the operating current of normal operation. The exact dimensioning depends on the circumstances of the individual case. This increase in starting torque thus achieved is particularly advantageous in applications which require a high starting torque, for example washing machines, dryers, mixers.

A voltage supply device of the control device according to FIG. 2 has, as an exemplary embodiment according to FIG. 4, a rectifier, for example a Greatz bridge, and a speed controller which acts as a phase Section control is executed. The Greatz Bridge enables the AC voltage to be easily converted from, for example, 230V to 325V with a ripple. A capacitor is not required for this. This configuration is particularly advantageous since it is inexpensive. Within the scope of the invention, the rectifier can of course also be replaced by diodes or thyristors, which may be controlled by a logic or a microprocessor. The low-voltage supply of this voltage supply device is implemented as a simple emitter follower, the voltage being determined by a Zener diode.

In order to ensure symmetrical activation of the single-phase synchronous motor 2, according to a first variant (FIG. 4) of the power stage 7, first transistors are provided which are activated directly from the voltage supply device. Second transistors are controlled via optocouplers as level shifters.

In a further alternative (FIG. 5), the single-phase synchronous motor 2 is equipped with two coils 21, 22, each of which generates a magnetic direction. As a result, only one transistor is required for each coil, so that there is a particularly cost-effective construction and an efficient circuit. The above statements are not only applicable to a vacuum cleaner, but can be implemented wherever drive powers of up to 5 kW are required. It is thus ensured that such drives are characterized by high efficiency, low noise, high reliability, low costs and very good recyclability due to the simple construction of the motor 2.

Reference list

1. Sensor

2. Single-phase synchronous motor

3. Pulse generator and phase shifter device

4. Direction of rotation determination

5. Speed limiter

6. Current limiter

7th level

8. Driver

9. NAND gate

10. Start-up aid

11. Pulse transfer circuit

12. second sensor 13. / 14. NAND gates

15. Power supply device

16. Rectifier

17. Speed controller

18. first transistors

19. second transistors

20. Optocoupler

21./22. Drive coil 23./24. transistor

Claims

claims

1. Electronic control with a power stage (7) for a single-phase synchronous motor (2) with a permanent magnet rotor, wherein: a) means (1) for detecting the position of the permanent magnet rotor; and b) means (3,4,5,6,7) are provided for controlling at least one drive coil as a function of the position of the permanent magnet rotor.

2. Electronic control according to claim 1, characterized in that the means for detection is a Hall sensor, which is preferably arranged between 0 and 60 ° from the north-south magnetic axis of the drive coil.

3. Electronic control according to claim 1 or 2, characterized in that a means for slowly reversing the magnetic direction is provided for generating a wobble of the permanent magnet rotor.

4. Electronic control according to one of claims 1 to 3, characterized in that a direction of rotation tion device (4), a speed limiter (5) and / or a current limiter (6) are provided.

5. Electronic control according to one of claims 1 to 4, characterized in that a voltage supply device with a rectifier and a speed controller is provided.

6. Electronic control according to claim 5, characterized ge indicates that the rectifier is designed exclusively as a Graetz bridge and delivers a high voltage, from which a lower voltage is derived via an emitter follower and a Zener diode.

7. Electronic control according to one of claims 1 to

6, characterized in that the power stage (7) has first transistors which are driven directly from the voltage supply device and has second transistors which are driven via optocouplers.

8. Electronic control according to one of claims 1 to

7, characterized in that the single-phase synchronous motor (2) has two coils which are driven directly via an associated transistor.

9. Electronic control according to one of claims 1 to

8, characterized in that the control device is designed as a logic circuit.

10. Electronic control according to one of claims 1 to 8, characterized in that the control comprises a microprocessor for controlling the at least one drive spool and optionally further switching elements.

11. Electronic control according to one of claims 1 to 10, characterized in that means for generating and approving an increased starting torque, in particular realized by an increased starting current, are provided.

12. Electronic control according to claim 11, characterized in that the means is a microprocessor which controls the power stage (7) for generating an increased starting current.

13. Electronic control according to claim 11, characterized in that the means is a capacitor, the discharge current of which is supplied to the synchronous motor (2).

14. One-phase synchronous motor with a sensor (1) for detecting the position of the permanent magnet rotor, the sensor (1) in the range of 0 - 60 °, preferably 10 to 30 °, from the north-south magnetic axis of the Drive coil is arranged, and wherein at least one drive coil with respect to the pulse height and / or the pulse width, in particular amplitude and frequency of a periodic control function, in Ab- dependence on the detected position of the rotor can be controlled.

15. A single-phase synchronous motor according to claim 14, wherein a further sensor is arranged offset by 100-140 ° in the direction of rotation to the first sensor (1).

16. Method for operating a single-phase synchronous motor (2), the signals of a sensor (1), which is offset by an angle from the north-south magnetic axis in the direction of rotation of the permanent magnet rotor, are fed to a control device, and wherein the control device generates control signals for at least one drive coil of the single-phase synchronous motor 2, which depend on the position of the permanent magnet rotor.

17. The method according to claim 16, characterized in that a direction signal is derived either directly from several or a single drive coil, part of a drive coil or a sensor coil separated from the drive coil.