DE102008014495A1 - Drive strand controlling method for e.g. hybrid vehicle, involves providing highly prioritized intervention control on electric motor in accordance with input signal that is based on target value - Google Patents

Abstract

The method involves providing a signal (pos) characterizing a position of a transmission selector lever (5) and another signal (pos') characterizing an operating condition of an electric motor (1) and/or a vehicle e.g. hybrid vehicle, by a safety device (4). A release signal or an error signal is generated from the signals by the safety device, and is provided as an input signal (e2) directly into an electric motor control (2). A highly prioritized intervention control is provided on the electric motor in accordance with another input signal (e1) that is based on the target value. An independent claim is also included for a device for controlling a drive strand of a vehicle.

Description

Technical area

The The invention relates to a method and a device for controlling a powertrain of a vehicle with at least one electric motor.

State of the art

From the DE 42 23 216 A1 is a control device for electric motors, which are controlled by an electronic control device via a control amplifier known.

From the control device are at lowering of the supply voltage below a predetermined value or in case of failure of the supply voltage operable Switching means for separating the electric motor and at least one operating emergency functions when the switching means are actuated Part of the control device provided by the supply voltage circuit.

Of the Electric motor is by means of at least one freewheeling diode of the control output stage with supply voltage terminals of the at least one Part of the control device for emergency power supply of the same and connected to the implementation of emergency functions.

Vehicles, powered by electric motor, pure electric vehicles as well as hybrid vehicles are conventionally operated with an accelerator pedal, whose position depicts the torque request of the driver. selector lever for the direction of travel, for idle and park mode are known from vehicles with automatic transmissions. On electric vehicles, which is not necessarily a manual or automatic transmission which is familiar from automatic vehicles Move the selector lever to the direction of travel select and set a park and idle mode.

At Vehicles with electric motors are special safety requirements with regard to the torque output of the electric motor for driving the Vehicle to provide. Error cases where the electric motor an unwanted behavior, in particular an unwanted torque output, realized, must be intercepted safely. The special requirements result, therefore, that electric motors in electric vehicles as even with some hybrid concepts directly on the vehicle output act and thus the power flow can not be interrupted by a clutch is. While the internal combustion engine is assumed can that with a misconduct in the engaged state with the vehicle brake can be brought to a standstill, so is at Electric motors that produce high torque even at low speeds the vehicle brake may not be in the Able to decelerate the vehicle that has been unintentionally driven in the event of a fault. The prior art sees this separate emergency functions, in particular Emergency switch, in front. Sources of error can be sensor errors, Hardware or software error of the controller or setpoint input be.

Object of the invention

Of the Invention is based on the object, a method and an apparatus provide an error case based on the driver and vehicle response recognizes and at the same time a reliable safety function provides an unwanted torque output of the electric motor to prevent.

Solution of the task

The Task is achieved by a method according to claim 1 and a device according to claim 11 solved.

The drive train of a vehicle has at least one electric motor for driving it and a selector lever for selecting at least two different driving modes D, N, P, R. The position signal of the selector lever is applied to a control unit at its input, which determines from this and the position of an accelerator pedal setpoint values for the speed and / or torque of the electric motor and transmitted as input signals to an electric motor drive. The electric motor control implements this via control elements, preferably semiconductor switches, the power supply to the electric machine. In a preferred embodiment, the individual phase currents of an electric motor are controlled via semiconductor switches. The control of the electric machine is carried out by realization of the opening or closing function of the semiconductor switch. According to the invention, the signal of the position of the selector lever and at least one further signal indicative of the operating state of the electric motor and / or of the vehicle are applied parallel to the control unit and functionally separated therefrom of a safety device. The use of the selector lever signal is in addition to the accelerator pedal another possibility for the driver to intervene. For verification of the driver's will, it is therefore particularly suitable. The safety device generates from these signals either a release signal or an error signal, which engages as an input signal directly into the electric motor drive. The direct intervention of the safety device on the hardware of the control or on a hardware-related control unit realizes a higher priority compared to the setpoint control control intervention on the electric motor. The functio nal separation of the safety device should avoid error propagation from the setpoint control. The signal of the selector lever is prioritized higher to allow a direct intervention of the driver in case of failure. Alternatively or in addition to the intervention in the electric motor control, a hardware-related intervention in the power supply of the electric machine is possible. Upon the occurrence of the error signal generated by the safety device, a switching element is actuated, which directly or indirectly influences the power flow to the electric machine. In an advantageous embodiment, the energy supply of the electric machine is interrupted when the error signal occurs. This can be done, for example, by means of a contactor arranged close to the energy store.

through the safety device according to the invention has thus giving the driver the opportunity to change position of the selector lever targeted and directly into the torque output the electric motor so intervene that the power supply the electric motor is defined reduced or interrupted. Of the Actuation of a separate emergency stop switch is therefore not required according to the invention.

The inventive method and the invention Device support the driver's experience with conventional vehicles usual procedure, in case of error for torque reduction to separate the engine power flow and off the forward drive D to idle (selector lever position "N") or to switch to the parking position P. As with electric vehicles a mechanical separation of the power flow does not take place is this function is replaced by the safety device in the event of an error.

According to the invention advantageous the safety device generates an enable or error signal. The Error signal can be requested by the setpoint control Override control of the electric machine. The error signal is prioritized over this. At issue the enable signal becomes the drive signal required by the reference value control generated for the electric machine. The selector lever has at least one forward drive mode D and at least another neutral mode N and / or a parking mode P and / or a reverse drive mode R on. In forward drive mode D the safety device generates an enable signal for the electric motor control, and in neutral mode N or park mode P also depends on the operating state of the electric motor and / or the vehicle opposite the output signal of the setpoint control prioritized higher Error signal generated, the electric motor control due this error signal de-regulates the power supply of the electric motor or interrupts.

According to the invention advantageous before the generation of the error signal is a plausibility check method go through, so not every circuit of the selector lever to N to trigger the error signal and thus to adjust of the electric motor leads. The plausibility check procedure processed in addition to the position of the selector lever at least one of the operating state of the vehicle and / or the electric motor signal indicative of this with the signal of the position of the Selector lever compares and at a detected implausibility generates the error signal.

The Signal about the operating state of the electric motor and / or the signal of the vehicle provide necessary signals for the safety device to the current position of the selector lever with respect desired and realized by the electric motor torque evaluate. For example, assign the signals of the electric motor and the vehicle to one of the selector lever position D corresponding Driving condition, as the safety device indicates the instead the expected selector lever position D applied selector lever position N on a vehicle standstill directed driver request. by virtue of This signal combination generates the safety device at the electric motor control applied error signal, so that the power supply of the electric motor is interrupted. The through the error signal directly affected the hardware-related control the engagement of the electric motor overrides the setpoint control.

The Plausibility check uses alternatively or in combination various measured values of the vehicle and / or electric motor state. One possible signal here is the speed and / or their amount of change, the acceleration. The error signal is then generated when driving in the selector lever position Neutral mode N or Park mode P No reduction in speed or acceleration is determined.

One Another possible signal for plausibility is the Signal of the torque delivered by the electric motor. The error signal is then generated when in selector lever neutral mode N or parking mode P no reduction in torque determined becomes. A direct measurement of the torque output is only possible through additional sensors, therefore takes place According to the invention advantageously a measurement of the Electric motor recorded current, the error signal then is generated when in selector lever neutral mode N or park mode P no reduction of the absorbed current is determined.

According to the invention advantageous can current and / or voltage values of a DC link between Power supply and electric machine are measured, as Measure of the delivered / absorbed torque the power in the DC link is calculated from current and voltage.

According to the invention advantageous For the generation of the error signal, the change of the Selector lever position from forward drive D or reverse drive R in the selector lever positions neutral mode N or park mode P rated and generates an error signal if no plausible change the operating state of the electric motor and / or the vehicle takes place. According to the invention, the error signal becomes advantageous only generated when one of the signal delay and / or Inertia of the reacting electric motor or vehicle oriented delay time no expected plausible Reaction of the vehicle and / or the electric motor takes place. alternative is at an intervention on the electric motor control and at least one switching element switching the power supply a stepped intervention so possible that after expiration a first period of the delay time an intervention on the electric motor control and when reaching a second longer time threshold without plausible reaction of the Vehicle and / or the electric motor engaged by means of a the power supply switching switching element takes place.

The Inventive device for controlling a Powertrain of a vehicle with at least one electric motor has a setpoint control, which is used to determine setpoint values for the speed and / or the torque of the electric motor the position the selector lever and at least one other from the driver evaluable influencing control device. Parallel to this lies functionally separated from the setpoint control a safety device, which the signal of the position of the selector lever and at least another the operating condition of the electric motor and / or vehicle characteristic Signal is applied, one of the safety device from these Signals generated enable or error signal as an input signal directly an electric motor control is applied and the control of the Power flow to the electric machine adjusting switching elements influenced. The direct intervention on the switching elements ensures a Emergency stop function with the selector lever, bypassing the actual setpoint control.

The Plausibilisierung the signal takes place in a possible advantageous embodiment by measuring points in the intermediate circuit between Power supply and inverter, with a current sensor arranged here is, a the operating state of the electric machine characterizing Signals the current value to the safety device.

additionally can be inserted in the DC link between the power supply and the inverter Voltage sensor can be arranged, taking the voltage and current In the intermediate circuit calculated power as the operating condition of Electric machine characterizing signal of the safety device is applied.

In An advantageous embodiment includes the vehicle a hybrid drive with at least one electric motor. The output signal the safety device or the plausibility check device can also be used as an input signal to control this the further drive unit, for example an internal combustion engine, abut, so in the case of a higher priority signal on the one hand the power supply for the electric motor by the Electric motor control interrupted and on the other hand at the same time the further drive unit, for example the internal combustion engine, is controlled with a lower torque output.

following An embodiment of the invention will be described.

drawings

It demonstrate:

1 : a schematic diagram of a device according to the invention;

2 : a schematic diagram of an electric motor drive.

In the 1 a schematic diagram of an embodiment of the device according to the invention is shown. An electric motor 1 is via an electric motor control 2 driven. A first input signal e1 of the electric motor drive 2 is from a control unit 3 - the setpoint control - generated. A second input signal e2 is from a safety device 4 that are spatially and functionally separate from the control unit 3 is generated. Both the control unit 3 as well as the safety device 4 is located as an input signal, the position signal pos a selector lever 5 at. In an alternative embodiment, the selector lever signal can be redundant. The control unit 3 then there is a selector lever signal pos', which is equal to the position signal pos in the error-free case, which is the safety device 4 is applied. In this case, in contrast to the representation 1 no connection of the redundantly executed position signals pos, pos'1 provided with each other. The signals can already be in the selector lever 5 be generated by different position sensors, so that already on the hardware side redundant position signals are present, which separately to one of the control unit 3 and the safety device 4 issue. The redundant version allows safe control of the engine 1 , as there is an error-free path for stopping the motor 1 is sufficient.

The control unit 3 generates setpoint values for the torque T and / or for the speed of the electric motor 1 , which to the electric motor control 2 is transmitted. For this setpoint generation are the control unit 3 as input signals next to the position pos of the selector lever 5 the position of the accelerator pedal 6 , the position of the brake pedal 7 and the torque T of the electric motor 1 at. This setpoint generation is known from the prior art and is therefore not described in detail.

The safety device 4 lie as input signals next to the pos position of the selector lever 5 a the output torque T of the electric motor 1 characterizing signal, preferably the signal i, of the electric motor 1 absorbed current, which from a current sensor 8th is detected, for example, in the intermediate circuit between a power supply 11 and the electric motor drive 2 is arranged. Alternatively or additionally, the speed signal v and / or the acceleration signal a of the vehicle is applied. In this embodiment, the current signal i is the operating state of the electric motor 1 distinctive signal. The acceleration signals a and speed signals v represent in this embodiment, the operating condition of the vehicle characterizing signals. Crucial for the evaluation is the position of the selector lever 5 , To implement an emergency function for switching off the electric motor 1 this will be the pos position of the selector lever 5 signal used.

Due to the applied input signals, the safety device generates 4 either a release signal or a compared to the setpoint signal of the control unit 3 higher prioritized error signal for the electric motor control 2 , In the case of the release signal generation as input signal e2 processes the electric motor drive 2 the setpoint signal as the input signal e1 of the control unit 3 ,

In the other case, the electric motor control processes 2 only the higher priority error signal as the input signal e2 of the safety device 4 , so that the setpoint signal as the input signal e2 of the control unit 3 is not considered.

Part of the safety device 4 is the plausibility of the position signal pos before the generation of the error signal.

The signal of the current sensor is used 8th and / or the vehicle acceleration a. The plausibility checker 9 represents a further stage for checking to an unwanted, ie not intended by the driver, shutdown of the electric motor 1 perform.

The Error signal is only generated if in addition to the circuit from position D to N or P no decrease in torque T, which is about a decrease in the absorbed current i can be detected is determined.

The electric motor control 2 is more detailed in 2 shown. As part of the electric motor control 2 be in a control function 12 Setpoints for switching on and off of the individual strands of an electric motor 1 generated by power lines and by the individual actuators 10 , eg IGBT, implemented. In the 2 are only two stops 10 represented, which are shown by way of example for the control of a strand. The switching position of the executed as a semiconductor switch actuator 10 causes a power supply or their shutdown for the individual windings, so that in this way the output of the torque T can be controlled. If the windings are de-energized, the electric motor 1 no torque T generated. In the event of an error, this represents a safe state. If necessary, this shutdown can also be done as a star short circuit. Intervention of a signal of safety device 4 - Not shown - is shown on the signal e2, this is implemented primarily in front of the signal generated by the setpoint control signal e1. In the embodiment, the control function 12 a driver stage 13 downstream, which ultimately from the setpoints for the single strands, the control signals for the actuator 10 generated. The driver stage 13 is the signal e2, which is a release condition for the control of the actuator 10 represents. If an enable signal is generated by the signal e2, the signal e1 required by the setpoint control is converted. The enable / error signal e2 is the driver stage 13 and, in the case of the presence of the error signal, is implemented prior to the input signal e1 of the setpoint control. In an alternative embodiment is an intervention on the control function 12 possible. A further alternative embodiment provides the intervention near the power supply 11 dar. The energy supply 11 is usually via a switchable connection with the electric motor control 2 or the electric motor 1 connected. The shutdown of the power supply 11 via a switching element 14 , preferably a contactor, which is switched directly or indirectly with the enable / error signal e2. The 2 further shows a schematic representation of a power supply 11 wherein in the intermediate circuit between this and the electric motor drive 2 or the electric motor 1 the current i and the voltage u can be measured, which for the evaluation of the output torque T of the electric motor 1 can be used.

1

electric motor

2

Electric motor control

3

control unit

4

safety device

5

selector lever

6

Accelerator pedal position

7

Brake pedal position

8th

current sensor

9

Plausibilisierungseinrichtung

10

Steller

11

power supply

12

control function

13

driver stage

14

switching element

a

acceleration

D

Forward running mode

R

Reverse drive mode

e1

input

e2

input

i

electricity

N

neutral mode

P

Park mode

T

torque

v

speed

u

Intermediate circuit voltage

pos

signal the position of the selector lever

pos'

signal the position of the selector lever

T1, T2

time constants

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4223216 A1 [0002]

Claims (16)

Method for controlling a drive train of a vehicle with at least one electric motor ( 1 ) for driving the vehicle, which is a selector lever ( 5 ) for the selection of at least two different driving modes (D, N), wherein the position (pos) of the selector lever ( 5 ) characterizing signal of a control unit ( 3 ) is applied to the input and these setpoints for the speed and / or torque (T) of the electric motor ( 1 ) and as input signals (e1) to an electric motor control ( 2 ), characterized in that in addition to the control unit ( 3 ) and functionally separate from this one safety device ( 4 ) that the position (pos) of the selector lever ( 5 ) characterizing signal and at least one further the operating state of the electric motor ( 1 ) and / or the vehicle characterizing signal, wherein the safety device ( 4 ) generates either an enable signal or an error signal from these signals, which as input signal (e2) directly into the electric motor drive ( 2 ) and / or on a switching the power supply switching element ( 14 ) engages and a higher-priority control action on the electric motor compared to the input signal (e1) based on the reference value determination ( 1 ) causes. Method according to claim 1, characterized in that the selector lever ( 5 ) comprises at least two driving modes, consisting of a forward driving mode (D) and a neutral mode (N), wherein the safety device ( 4 ) in the forward drive mode (D) an enable signal for the electric motor drive ( 2 ) and in neutral mode (N) depending on the operating state of the electric motor ( 1 ) and / or of the vehicle relative to the output signal of the control unit ( 3 ) higher prioritized error signal compared to the input signal (e1) generated, the electric motor control ( 2 ) and / or a switching element switching the power supply ( 14 ) due to this error signal, the power supply of the electric motor ( 1 ) stops or interrupts. Method according to Claim 2, characterized in that the selector lever ( 5 ) as further driving modes comprises a reverse driving mode (R) and a parking mode (P), wherein the safety device ( 4 ) in the forward drive mode (D) and in the reverse drive mode (R) an enable signal for the electric motor drive ( 2 ) and in neutral mode (N) depending on the operating state of the electric motor ( 1 ) and / or of the vehicle relative to the output signal of the control unit ( 3 ) higher prioritized error signal compared to the input signal (e1) generated, the electric motor control ( 2 ) and / or a switching element switching the power supply ( 14 ) due to this error signal, the power supply of the electric motor ( 1 ) stops or interrupts. Method according to one of the preceding claims, characterized in that before the generation of the error signal, a plausibility check procedure is run through, wherein the plausibility check method in addition to the position (pos) of the selector lever ( 5 ) at least one of the operating state of the vehicle and / or the electric motor ( 1 ) characterizing signal with the signal of the position (pos) of the selector lever ( 5 ) compares and generates the error signal with a recognized implausibility. Method according to one of the preceding claims, characterized in that the signal of the operating state of the Vehicle the speed (v) and / or their change amount the Acceleration (a), the error signal is then generated when in neutral position (N) or park mode (P) no reduction in speed (v) or acceleration (a) is determined. Method according to at least one of the preceding claims, characterized in that the signal of the operating state of the electric motor ( 1 ) is the torque output by this (T), wherein the error signal is generated when in the selector lever neutral mode (N) or parking mode (P) no reduction of the torque (T) is determined. Method according to at least one of claims 1-4, characterized in that the signal of the operating state of the electric motor ( 1 ) is the current absorbed by this (i), wherein the error signal is generated when in the selector lever neutral mode (N) or parking mode (P) no reduction of the absorbed current is determined. Method according to at least one of the preceding claims, characterized in that the error signal is only generated when switching from the selector lever position for forward drive (D) or reverse (R) in the selector lever neutral mode (N) or parking mode (P) and none plausible change of the operating state of the electric motor ( 1 ) and / or of the vehicle. A method according to claim 8, characterized in that the error signal is only generated if no plausible change in the operating state of the electric motor ( 1 ) and / or the vehicle after a change of the selector lever position from forward drive (D) or reverse drive (R) to the selector lever positions neutral mode (N) or park mode (P) at the end of a signal propagation time and / or inertia of the reacting electric motor ( 1 ) or vehicle-oriented delay time. Method according to Claim 9, characterized in that when the fault signal is applied to the electric motor drive ( 2 ) and at least one switching element switching the power supply ( 14 ) a stepped engagement is performed such that after a first period of time (T1) of the delay time an intervention on the electric motor control and after a second compared to the first time period (T1) longer period (T2) without plausible reaction of the vehicle and / or of the electric motor ( 1 ) an intervention by means of the power supply switching switching element ( 14 ) he follows. Device for controlling a drive train of a vehicle with at least one electric motor ( 1 ), which by means of an electric motor control ( 2 ) is controllable, for driving the vehicle, which is a selector lever ( 5 ) for different driving modes (D, N, P, R), wherein at the output of the selector lever ( 5 ) is present a signal indicative of its position (pos), the device is further provided with a control unit ( 3 ) for determining setpoint values for the rotational speed and / or the torque (T) of the electric motor ( 1 ), wherein this the position (pos) of the selector lever ( 5 ) and at least one further controllable by the driver control device for the requested torque (T) and / or the speed of the control units as an input signal (e1) for the electric motor control ( 2 ), characterized in that the device has an additional parallel to the control unit ( 3 ) and functionally separate therefrom arranged safety device ( 4 ), which receives the signal of the position (pos) of the selector lever ( 5 ) and at least one further the operating state of the electric motor ( 1 ) and / or the vehicle characterizing signal is present at the input, wherein one of the safety device ( 4 ) generated from these signals enable or error signal as an input signal (e2) directly an electric motor control ( 2 ) which influences the activation of the switching elements which put the power flow to the electric machine and / or a switching element ( 14 ) which influences the power flow to the electric machine. Apparatus according to claim 11, characterized in that the release or error signal as an input signal (e2) of a driver stage ( 13 ) is present at the output of the control signals for the actuator ( 10 ) be generated. Apparatus according to claim 11-12, characterized in that in the intermediate circuit between the power supply and inverter, a current sensor ( 8th ) whose signal is indicative of the operating state of the electric machine signal of the safety device ( 4 ) is present. Device according to Claim 13, characterized in that a voltage sensor is arranged in the intermediate circuit between the power supply and the converter, the power calculated from the voltage (u) and current (i) in the intermediate circuit being the signal indicating the operating state of the electric machine ( 4 ) is present. Apparatus according to claim 11-14, characterized in that at the output of the selector lever ( 5 ) two redundant position-identifying signals (pos, pos') are present, these separated from each other once -pos'- the control unit ( 3 ) and in the other case -pos- the safety device ( 4 ) issue. Apparatus according to claim 15, characterized in that the at the output of the selector lever ( 5 ), whose position characterizing signals (pos, pos') originate from different position sensors.