Method for controlling a brake system

Patent metadata

Field	Value
Publication number	US-10604127-B2
Application number	US-201615357612-A
Country	US
Kind code	B2
Filing date	Nov 21, 2016
Priority date	May 21, 2014
Publication date	Mar 31, 2020
Grant date	Mar 31, 2020

Abstract

A brake system comprises a cylinder-piston unit movable by an electromechanical actuator. Wheel brakes associated with at least one axle can be supplied with braking pressure via the hydraulic pressure chamber. The electromechanical actuator comprises a rotation-translation transmission and an electronically commutated synchronous machine having a stator with at least two phase windings, a rotor comprising at least one permanent magnet and at least one rotor position sensor. A torque-forming current and/or a magnetic field attenuating current are adjusted in a co-ordinate system which is fixed relative to the rotor. Voltages in the co-ordinate system are detected to serve as control variables and are transformed into a voltage phasor, which indicates for each phase winding of the stator, a voltage to be applied, and a set value for the magnetic field attenuating current is limited to a maximum value being determined from a predetermined characteristic map.

First claim

What is claimed is:

1. A method of operating a brake system for motor vehicles with an electrically controllable pressure supply device comprising:
supplying brake pressure to a plurality of hydraulic wheel brakes from a hydraulic pressure chamber;
displacing a piston within the hydraulic pressure chamber with an electromechanical actuator, wherein the electromechanical actuator comprises a rotation-translation gearbox and an electrical machine, wherein the electrical machine is an electronically commutated synchronous machine having a stator with at least two phase windings and a rotor comprising at least one permanent magnet as well as at least one rotor position sensor;
regulating at least one of a torque-forming current and a magnetic field attenuation current in a coordinate system that is fixed relative to the rotor;
transforming voltages in the coordinate system into control variables using a measured rotor position, wherein the control variables are a voltage vector that gives a voltage to be applied for each phase winding of the stator;
determining a measured revolution rate of the rotor from a first predetermined characteristic field; and
limiting a target for the magnetic field attenuation current to a maximum value according to the measured revolution rate and to not fall below a minimum value that is predetermined according to the measured revolution rate; and
determining a target value for the magnetic field attenuation current according to the measured revolution rate of the rotor from the first predetermined characteristic field.

2. The method of claim 1 , wherein there are three phase windings.

3. The method of claim 1 , further comprising adapting the target value for the magnetic field attenuation current using a ratio between a reference voltage and a current supply voltage.

4. The method of claim 1 , further comprising limiting a target value for the torque-forming current to a maximum value of the torque-forming current according to the measured revolution rate of the rotor.

5. The method of claim 4 , wherein the target value for the magnetic field attenuation current and the maximum value of the torque-forming current are predetermined so that a predetermined limit value for a total current of the magnetic field attenuation current and the torque-forming current is not exceeded and that the torque of the electronically commutated synchronous machine is at a maximum while complying with the limit value for the total current.

6. The method of claim 1 , wherein the limiting is carried out after the target value for the magnetic field attenuation current has been determined according to a difference between the magnitude of a predetermined maximum voltage, which corresponds to a current supply voltage minus a predetermined voltage interval, and the magnitude of a voltage vector formed by the torque-forming voltage and the magnetic field attenuation voltage, wherein the regulation of said difference is carried out.

7. The method of claim 6 , wherein the regulation of the difference between the magnitude of a predetermined maximum voltage and the magnitude of a voltage vector formed from the torque-forming voltage and the magnetic field attenuation voltage is carried out when the magnitude of the voltage vector is less than a predetermined minimum value, wherein pre-control of the target value for the magnetic field attenuation current is carried out by predetermining the maximum permissible field attenuation current.

8. The method of claim 1 , further comprising determining a target value for the torque-forming current according to a deviation between a target revolution Rate and the measured revolution rate of the rotor, and limiting the target value for the torque-forming current to a maximum value according to a target value for at least one of the magnetic field attenuation current, a maximum permissible total current, and a maximum permissible motor torque.

9. The method of claim 1 , wherein a torque-forming voltage in the coordinate system that is fixed relative to the rotor is determined according to the difference between a target value for the torque-forming current and a measured torque-forming current, and limiting the torque-forming voltage according to a difference between the magnitude of a predetermined maximum voltage and the magnitude of a magnetic field attenuation voltage.

10. The method of claim 1 , wherein the predetermined maximum voltage is a supply voltage.

11. The method of claim 1 , wherein a magnetic field attenuation voltage in the coordinate system that is fixed relative to the rotor is determined according to the difference between a target value for the magnetic field attenuation current and a measured magnetic field attenuation current.

12. The method of claim 1 , further comprising determining a measured torque-forming current and a measured magnetic field attenuation current in the coordinate system that is fixed relative to the rotor from measured currents through the phase windings of the rotor using the measured rotor position.

13. The method of claim 1 , further comprising adapting the target value for the magnetic field attenuation current using at least one of a measured rotor temperature, a measured stator temperature, and a current supply voltage.

14. The method of claim 1 , supplying the phase windings of the stator with current from a pulse width modulation circuit, wherein a voltage to be applied to a phase winding of the stator is converted into a degree of actuation of the corresponding pulse width modulation circuit.

15. The method of claim 14 , further comprising adapting the degree of actuation according to a ratio of a reference voltage and a current supply voltage.

16. The method of claim 15 , wherein the current supply voltage is a measured intermediate circuit voltage of the pulse width modulation circuit.

17. An electronic control unit for a brake system, comprising:
an actuation circuit for an electronically commutated synchronous machine;
a computation unit and semiconducting switch elements disposed in at least one pulse width circuit associated with each phase of a stator for the machine;
wherein a maximum value for a magnetic field attenuation current is determined using pairs of values of measured revolution rates and associated maximum values read out from a non-volatile memory;
wherein a measured revolution rate of the rotor is from a first predetermined characteristic field;
wherein a target value for the magnetic field attenuation current is limited to a maximum value according to the measured revolution rate and is limited to not fall below a minimum value that is predetermined according to the measured revolution rate; and
wherein the target value for the magnetic field attenuation current according to the measured revolution rate of the rotor from the first predetermined characteristic field.

18. The electronic control unit of claim 17 , wherein the at least one bridge circuit is a pulse width modulation circuit associated with each phase of the stator.

19. A brake system comprising:
an electrically controllable pressure supply circuit;
a cylinder-piston arrangement with a hydraulic pressure chamber and a piston displaceable by an electromechanical actuator;
a plurality of hydraulic wheel brakes that are associated with at least one axle of the vehicle and that can be supplied with brake pressure by the hydraulic pressure chamber;
a sensor for detecting braking intention;
wherein the electromechanical actuator comprises a rotation-translation ge

Assignees

• Continental Teves Ag & Co Ohg

Inventors

• Kaufmann Tom
• Stauder Peter

Classifications

• B60T8/326 Primary

  Hydraulic systems · CPC title

• B60T2220/04

  Pedal travel sensor, stroke sensor; Sensing brake request · CPC title

• B60L7/24 Primary

  with additional mechanical or electromagnetic braking · CPC title

• B60T8/4081

  Systems with stroke simulating devices for driver input (B60T8/4077 takes precedence) · CPC title

• H02P6/08 Primary

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title