Method and device for suppressing positioning requirements on a motor pump unit

Abstract

The present invention relates to a method for suppressing control requests in which an electric machine (170) in a motor vehicle, which drives a load unit (172), is controlled by a speed controller (120) with an integral component and a current controller (140). The speed controller (120) generates a control request for the current controller (140) from the difference between a predetermined speed (111) and a measured speed (112) of the electric machine. This control request is suppressed by setting the output of the integral component to zero if the measured speed (112) is below a predetermined speed threshold and the motor vehicle is simultaneously traveling at low speed. Furthermore, a device on which the method can be carried out is presented.

Description

[0001] The present invention relates to a method for suppressing control requests in a speed control system for a motor pump unit. Furthermore, a device is presented on which the method can be implemented.

[0002] A motor pump unit, also abbreviated MPE, is part of a motor vehicle's active chassis. It consists of an electric motor that drives a pump in a hydraulic system and a speed control unit that controls the electric motor via a current regulator. During operation, the vehicle frequently encounters standstill phases or rolling at very low vehicle speeds, during which no control intervention by the MPE is actually necessary.

[0003] The speed control unit of the MPE usually features proportional-integral (PI) control, with an I component integrating the difference between the setpoint and the feedback. Since even small differences, triggered, for example, by sensor noise, repeatedly lead to torque requirements from the current controller when integrated, the electric motor is supplied with a small actuating current. However, due to its small size compared to the higher frictional force present in the motor-pump unit, this ultimately does not result in any rotation in the electric motor, but unnecessarily increases the power consumption of the MPE.

[0004] DE 102 38 657 A1 discloses a vehicle suspension system with a damper and a hydraulic circuit connectable to the damper, wherein a first switching valve is assigned to a first subchamber of the damper and a second switching valve is assigned to a second subchamber of the damper. The volume flow of a hydraulic medium is adjusted by a control device depending on the vehicle's operating conditions.

[0005] From the document DE 36 45 148 C2 a control device for controlling a level of components of a motor vehicle carried by hydropneumatic suspension cylinders is known.

[0006] The document DE 11 2020 001 989 T5 describes an active suspension system of a motor vehicle, wherein the active suspension system can be switched between an active roll control mode and a passive roll control mode, wherein in the passive roll control mode the pump is not controlled.

[0007] The publication US 2018 / 0 326 810 A1 discusses a suspension device in which a pump supplies fluid to an actuator. The pump is controlled based on a road surface displacement detected by a sensor.

[0008] The document DE 10 2018 221 576 A1 describes a method for operating a vibration damper arrangement, wherein a control for a defined actuating force of the vibration damper arrangement is provided.

[0009] Against this background, it is an object of the present invention to present a method for controlling a motor pump unit that reduces unnecessary power consumption when the control requirements are low and there is no actual need to control an active chassis. Furthermore, a device is to be presented with which the method can be implemented.

[0010] To achieve the aforementioned object, a method for suppressing control requests is proposed, in which an electric machine in a motor vehicle, which drives a load unit, is controlled by a speed controller with an integral component and a current controller. The speed controller generates a control request for the current controller from a difference between a predetermined speed and a measured speed of the electric machine. The control request is suppressed by setting an output of the integral component to zero if the measured speed is below a predetermined speed threshold and, at the same time, the motor vehicle is in a low-speed phase.

[0011] The measured speed exhibits measurement-related fluctuations within the range of the measurement uncertainty of a speed-measuring sensor. By integrating even small differences between the specified speed, which may, for example, be zero in a phase without necessary control intervention, and the measured speed of the electric machine, which may also be zero but exhibits minor fluctuations due to the measurement uncertainty of the sensor, control requirements arise. However, these are advantageously suppressed by the method according to the invention, thus further advantageously preventing unnecessary power consumption by the electric machine.

[0012] In one embodiment of the method according to the invention, the electric machine and the load unit are formed by a motor pump unit of an active chassis of the motor vehicle. During operation of the motor vehicle, the active chassis remains switched on by default, even during stationary phases or at low speeds, whereby often no control intervention is necessary. By means of the method according to the invention, unnecessary current supply and power consumption are advantageously avoided, thus reducing the basic power requirement of the motor pump unit.

[0013] In a further embodiment of the method according to the invention, the predetermined speed threshold is formed by a dead band.

[0014] In yet another embodiment of the method according to the invention, the low-speed phase includes a very low vehicle speed or a stationary phase of the motor vehicle. The presence of the low-speed phase is determined by the speed of at least one sensor from the following list falling below predetermined threshold values: speedometer, wheel acceleration sensor, transverse and / or longitudinal vehicle acceleration sensor.

[0015] In a further embodiment of the method according to the invention, the speed controller is formed by a proportional-integral controller.

[0016] Furthermore, a device for suppressing actuation requests is claimed, which in a motor vehicle comprises an electric machine, a load unit, a control unit which has at least one speed controller with an integral component and a current controller, and a sensor for the electric machine, wherein the electric machine drives the load unit and is controlled by the control unit. The speed controller is configured to form an actuation request for the current controller from a difference between a predetermined speed and a measured speed of the electric machine. The control unit is designed to suppress the actuation request by setting an output of the integral component to zero if the measured speed is below a predetermined speed threshold and, at the same time, a low-speed phase of the motor vehicle is present.

[0017] In one embodiment of the device according to the invention, the electric machine and the load unit are formed by a motor pump unit of an active chassis of the motor vehicle.

[0018] In a further embodiment of the device according to the invention, the predetermined speed threshold is formed by a dead band.

[0019] In yet another embodiment of the device according to the invention, the low-speed phase comprises a very low vehicle speed or a stationary phase of the motor vehicle. The presence of the low-speed phase is determined by the speed of at least one sensor from the following list falling below predetermined threshold values: speedometer, wheel acceleration sensor, transverse and / or longitudinal vehicle acceleration sensor.

[0020] In a further embodiment of the device according to the invention, the speed controller is formed by a proportional-integral controller.

[0021] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0022] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0023] The characters are described coherently and comprehensively. Fig. 1 shows schematically a control of a motor pump unit in an embodiment of the method according to the invention. Fig. 2 graphically shows a desired force curve for the motor pump unit in a further embodiment of the method according to the invention.

[0024] In Fig. 1 shows a control scheme 100 of a motor pump unit in one embodiment of the method according to the invention. A sensor 180 supplies rotor position values ​​to an electric machine 170, which together with a load unit (pump) 172 - coupled via a converter 171 arranged therebetween - forms a motor pump unit, to a signal processing unit 190. Due to an intrinsic measurement uncertainty of the sensor 180, slightly fluctuating speeds are converted by the signal processing unit as the actual angular frequency ω ist 112 is reported to a speed difference generator 110 of the control system. The speed difference generator 110 extracts the actual angular frequency ω ist 112 from a target angular frequency ω soll 111 and supplies a result to a speed controller 120, which generates a corresponding set current value i soll 131 to a current value difference generator 130. According to the invention, the target current value i soll131 is set to zero by the speed controller 120 if one of the measured actual angular frequencies ω ist 112 corresponding speed is below a predetermined speed threshold and at the same time a low-speed phase of the motor vehicle is present. The current value difference generator 130 subtracts from the target current value i soll 131 an actual current value i ist 132 and feeds a result to a current regulator 140. In the embodiment shown, a pulse-controlled inverter 150 with a power section 160 is connected to the current regulator 140, whereby a corresponding current is supplied to the electrical machine 170.

[0025] In Fig.2 graphically shows a target current value curve 200 in a further embodiment of the method according to the invention. While a current axis 202 is shown as the y-axis, a time curve 201 is shown as the x-axis. In a standstill phase 211, no actual control request takes place. A target current value 210 calculated by the speed controller 120 does not exceed a value of a dead band 213, which is why the target current value i passed on to the current value difference generator 130 soll 131 is set to zero. During a subsequent run with control request 212, the calculated target current value 210 clearly exceeds the dead band and thus corresponds to the target current value i passed on to the current value difference generator 130. soll 131.

Claims

[1] Method for suppressing control requests, in which, in a motor vehicle, an electrical machine (170) which drives a load unit (172) is controlled by a speed controller (120) with an integral component and a current controller (140), in which a control request (212) for the current controller (140) is formed by the speed controller (120) from a difference between a predetermined speed (111) and a measured speed (112) of the electrical machine, in which the control request (212) is suppressed by setting (121) an output of the integral component to zero if the measured speed (112) is below a predetermined speed threshold and, at the same time, a low-speed phase of the motor vehicle is present. [2] Method according to claim 1, wherein the electric machine (170) and the load unit (172) are formed by a motor pump unit of an active chassis of the motor vehicle. [3] Method according to one of the preceding claims, in which the predetermined speed threshold is formed by a dead band (213). [4] Method according to one of the preceding claims, in which the low-speed phase comprises a very low vehicle speed or a standstill phase (211) of the motor vehicle and the presence of the low-speed phase is determined by at least one sensor from the following list falling below predetermined threshold values: speedometer, wheel acceleration sensor, vehicle acceleration sensor in the transverse direction and / or longitudinal direction. [5] Method according to one of the preceding claims, wherein the speed controller (120) is formed by a proportional-integral controller. [6] A device for suppressing actuating requests, which in a motor vehicle comprises an electric machine (170), a load unit (172), a control unit having at least one speed controller (120) with an integral component and a current controller (140), and a sensor (180) for the electric machine (170), wherein the electric machine (170) drives the load unit (172) and is controlled by the control unit, wherein the speed controller (120) is configured to form an actuating request (212) for the current controller (140) from a difference between a predetermined speed (111) and a measured speed (112) of the electric machine (170), wherein the control unit is designed to suppress the actuating request (212) by setting an output of the integral component to zero (121),if the measured speed (112) is below a predetermined speed threshold and at the same time a low-speed phase of the motor vehicle is present., [7] Device according to claim 6, wherein the electric machine (170) and the load unit (172) are formed by a motor pump unit of an active chassis of the motor vehicle. [8] Device according to one of claims 6 or 7, wherein the predetermined speed threshold is formed by a dead band (213). [9] Device according to one of claims 6 to 8, wherein the low-speed phase comprises a very low vehicle speed or a standstill phase (211) of the motor vehicle and the presence of the low-speed phase is determined by falling below predetermined threshold values ​​of at least one sensor from the following list: speedometer, wheel acceleration sensor, vehicle acceleration sensor in the transverse direction and / or longitudinal direction. [10] Device according to one of claims 6 to 9, wherein the speed controller (120) is formed by a proportional-integral controller.

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