METHOD FOR ACTUATING A BRUSHLESS MOTOR

• US 20160261221A1
• Filed: 10/09/2014
• Published: 09/08/2016
• Est. Priority Date: 10/22/2013
• Status: Active Grant

• Current Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: streich, Christian, Netz, Achim, Stauder, Peter, Kaufmann, Tom
• Granted Patent: US 9,716,462 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F16D 2121/24 using motors
• CPC Class Codes: F16D 65/14 Actuating mechanisms for brakes; Means for initiating operation at a predetermined position brake control systems, parts thereof B60T
• CPC Class Codes: H02M 7/5395 by pulse-width modulation
• CPC Class Codes: H02P 21/04 specially adapted for very low speeds
• CPC Class Codes: H02P 27/085 wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
• CPC Class Codes: H02P 29/50 Reduction of harmonics
• CPC Class Codes: H02P 6/14 Electronic commutators

Abstract

A method for operating an electronically commutated synchronous machine, having a stator with at least two, in particular three, phase windings and a rotor having at least one permanent magnet. A control factor is determined periodically for each phase winding. The time periods during which an upper and lower supply voltage is applied to the phase winding are determined based on the control factor. The electronically commutated synchronous machine is actuated according to space vector modulation. Zero vectors are applied to the phase windings at the beginning and/or end of a period for a switch-off duration. All switches connected to the upper supply voltage or all switches connected to the lower supply voltage are on. The selection of the zero vector is performed in accordance with the phase winding with the greatest, in magnitude, deviation from the average control factor. As disclosed is an actuation circuit and the use thereof.

Claims

1. A method for operating an electronically commutated synchronous machine that comprises a stator having at least two, phase windings and a rotor that comprises at least one permanent magnet, said machine also comprising a control circuit that comprises at least two switches that are allocated to a phase winding, the method comprising:

determining a pulse control factor periodically for each individual phase winding;

determining, based on said pulse control factor, time periods during which the phase winding is influenced by way of the allocated switch either with an upper supply voltage or with a lower supply voltage; and

controlling the electronically commutated synchronous machine in accordance with a method of space vector modulation in which at the beginning and/or end of a period zero vectors are applied to the phase windings for a switch-off time duration,

wherein in each case either all the switches that are connected to the upper supply voltage or all the switches that are connected to the lower supply voltage conduct, and the zero vector is selected in accordance with the phase winding having the greatest deviation from the mean pulse control factor, said mean pulse control factor corresponding to a mean value between the upper supply voltage and lower supply voltage.

2. The method as claimed in claim 1, wherein the switch-off time duration is altered by a pseudo-random value if a predetermined condition is fulfilled.

3. The method as claimed in claim 2, wherein a rotational speed of the electronically commutated synchronous machine is determined and is compared with a rotational speed threshold value, and the predetermined condition is fulfilled and the switch-off time duration is altered by a pseudo-random value if the rotational speed that is determined is smaller than the rotational speed threshold value.

4. The method as claimed in claim 2, wherein the pulse control factor of the individual phase windings are compared, wherein a maximal pulse control deviation is determined as a difference between the largest and the smallest pulse control factor, and the predetermined condition is fulfilled and the switch-off period is altered by a pseudo-random value if the pulse control deviation is below a predetermined deviation threshold value.

5. The method as claimed in claim 2, wherein the pseudo-random value is at least one of calculated with the aid of a mathematic function, determined with the aid of a stored table, and determined in accordance with the lowest value bit of an analog-digital converter that is arranged in the pulse control circuit or is connected to said circuit.

6. The method as claimed in claim 1, wherein a check is performed as to whether the pulse control factor for the phase winding having the greatest deviation from the mean pulse control factor exceeds an upper pulse control threshold value or is below a lower pulse control threshold value, wherein the upper pulse control threshold value is greater than the lower pulse control threshold value, wherein the corresponding phase winding is connected during an entire period to the upper supply voltage if the upper control factor has been exceeded, and is connected to the lower supply voltage if the pulse control factor is below the lower control factor.

7. The method as claimed in claim 6, wherein either only one comparison between the upper threshold value or only one comparison with the lower threshold value is performed, wherein either only one connection of the corresponding phase winding to the upper supply voltage or only one connection of the corresponding phase winding to the lower supply voltage can occur.

8. A control circuit for an electronically commutated synchronous machine comprising:

a stator having at least two, phase windings and

a rotor that comprises at least one permanent magnet,

said control circuit comprising in each case two switches that are allocated in each case to a phase winding, said switches being connected to an upper supply voltage or a lower supply voltage, by a microcontroller that controls the switches in accordance with a method according to claim 1.

9. The control circuit as claimed in claim 8, wherein at least one switch is embodied as a Sense-FET in which at, an additional connector of the semiconductor switch, it is possible to tap a measuring current that is proportional to the power current that is connected, and that the computing unit comprises at least one analog-digital converter that determines the measuring current of a connected Sense-FET across a measuring resistor.

10. An application of a control circuit as claimed in claim 7 in an electronic control device for a brake system of a motor vehicle, wherein the control circuit is connected to an electrohydraulic actuator.

11. The method as claimed in claim 3, wherein the pulse control factor of the individual phase windings are compared, wherein a maximal pulse control deviation is determined as a difference between the largest and the smallest pulse control factor, and the predetermined condition is fulfilled and the switch-off period is altered by a pseudo-random value if the pulse control deviation is below a predetermined deviation threshold value.

12. An application of a control circuit as claimed in claim 8 in an electronic control device for a brake system of a motor vehicle, wherein the control circuit is connected to an electrohydraulic actuator.