WO2006131255A2

WO2006131255A2 - Method for operating an electric machine and control system therefor

Info

Publication number: WO2006131255A2
Application number: PCT/EP2006/005213
Authority: WO
Inventors: Lothar Rehm; Thomas Von Raumer
Original assignee: Daimlerchrysler Ag
Priority date: 2005-06-07
Filing date: 2006-06-01
Publication date: 2006-12-14
Also published as: WO2006131255A3; DE102005025994A1; DE102005025994B4

Abstract

The invention relates to a method for operating an electric machine comprising an electric control system which is provided with several operational modes of the electric machine and monitors an operational variable of the electric machine and/or the control system. The aim of the invention is to improve recognition of errors and to increase the availability of the electric machine. Said aim is achieved by virtue of the fact that an emergency mode is started when the monitoring detects an error which activates the emergency mode. Also, the method can, independently from the torque requirement of the driver, authorise additional interventions which influence the torque and monitor the errors of said interventions. The inventive control system is connected to two data communication modules (5, 6). The first data communication module (5) retransmits functional messages and can be deactivated by the monitoring unit (4). The second data communication module (6) can be retransmitted in order to reprogram the control unit (3) and/or the monitoring unit (4).

Description

Method for operating an electrical machine and

Drive system for this purpose

The invention relates to a method for operating an electric machine and a drive system for an electric machine.

German Offenlegungsschrift DE 102 51 095 A1 discloses a method for operating an electrical machine with a drive system, wherein an operating variable of the electrical machine and / or the drive system is monitored, and wherein the permissibility of an actual torque of the electric machine is checked and, if not. Admissibility of the actual torque an error reaction is initiated. The permissibility of the actual torque is preferably checked in such a way that an allowable torque is formed from a desired torque and predefined limit values for the desired torque, and that the actual torque is permissible if its deviation from the permissible torque does not exceed a certain amount. The invention can be used to monitor an electrical machine used as a starter / generator in a motor vehicle.

From the not yet disclosed DE 102 004 002 767 a method for operating an electrical machine is known, with a drive system, wherein monitors an operating variable of the electric machine and / or the drive system in which at least one torque mode, a charge mode and a speed mode are provided.

In contrast, the object of the present invention is to improve the detection of errors and to increase the availability of the electrical machine.

This object is achieved according to the invention by the features of the independent claims.

To this end, the method according to the invention for operating an electrical machine provides that a separate emergency mode is started when the monitoring detects an error which requires the activation of an emergency mode.

An error is defined here as a non-fulfillment of a request to a particular unit or unit. Double errors are two errors which occur within a short time window or period and are not causally related to each other. Two single errors that occur outside of this short time window and are also not causally related are called double errors. Advantageously, these types of errors, if they lead to deviations in the desired states, can be detected by the method according to the invention.

A possible error is implausible data. Data is considered plausible if it is up to date and without transmission errors.

Another error occurs when state variables are inadmissible. For this purpose, admissibility checks take place in the monitoring unit. Actual values are then checked, whether they are within the permissible limits assigned to them. The present invention is particularly effective when the fault is a failure or faulty operation of the data network.

Of course, this enumeration of the types of errors is not conclusive, and with the method according to the invention or the device according to the invention, other types of errors, for example, causally related errors, can be detected.

If an error is detected, it is decided whether this error disturbs the proper operation of the electrical machine. Typically, this is the case when the data network has failed or is operating incorrectly, so that no or only erroneous data from the data network is fed to the process.

The data network can for example be based on a CAN bus (Controller Area Network), on MOST (Media Oriented System Technology) or an optical fiber bus, or on a Flex-Ray communication system.

If the proper operation of the electrical machine in the activated operating mode can not be ensured with certainty, an emergency mode is activated. The emergency mode is designed so that critical operating conditions of the electrical machine are excluded. Thus, the electric machine can continue to operate even when a fault occurs. This increases the availability of the electrical machine. This also leads to increased availability of the overall system associated with the electrical machine. Such an overall system may include, for example, in addition to the electric machine, an internal combustion engine, another electric machine and / or a battery. Such an overall system can be designed as a hybrid drive of a vehicle. Also, an oil pump or other actuator may be connected to the electric machine in an overall system.

In one embodiment, a target torque with the value zero is specified in the emergency mode. This avoids the risk of a critical fault control of the electric machine without the electric machine being switched off or short-circuited.

In one embodiment, an operating mode designated as a charging mode is assigned a separate emergency mode which allows only negative target torques. This emergency mode represents a safe charging mode. The charging function remains as far as possible, eliminating the risk of incorrect loading of the electrical machine. This mode can also be used as an emergency mode for the generator mode of the torque mode.

In one embodiment, an operating mode designated as a speed mode is assigned a separate emergency mode. Here, a fixed speed is set as the setpoint speed internally by the control system. Thus, the engine start of an internal combustion engine can also be performed when the control of the electric machine with a normal operating mode is no longer possible without errors. The engine start of the internal combustion engine is typically initiated via a hardware line. In one embodiment, an additional torque-influencing intervention is performed regardless of the driver's torque request. This enables cooperation of the procedure with other methods. In particular, cooperation with an anti-Sudder is envisaged in this context. Shudders are vibrations of the electric machine caused by the torsion of components of the drive train during torque transmission. The electric machine has an internal control that detects these vibrations and generates corresponding compensating moments. This torque-influencing intervention is called antishudder.

In one embodiment, to monitor the torque-influencing engagement, the time integral of the target torque of the torque-influencing engagement of the electric machine is compared with a predefinable upper limit and a predeterminable lower limit and an error of the torque-influencing engagement is detected when the time integral from the desired torque of the torque-influencing engagement through leaves these boundaries enclosed area.

This checks the additional torque-influencing intervention for its plausibility. The time integral of the target torque should be zero on average. It can be positive or negative over a period of time. But if it increases continuously or goes down to negative, the cause must be found in an error that causes a permanent one-sided intervention. Such an error is detected by the method step just described. In one embodiment, the erroneously operating torque-influencing engagement is turned off. In one embodiment, a suitable emergency mode is selected when an error has been detected that requires activation of an emergency mode. Subsequently, the plausibility of the request of the emergency mode is checked. If the request is plausible, the emergency mode is activated. In the case of an implausible request for the emergency mode, a reset of the electrical control system is carried out. This procedure prevents switching to emergency mode for no reason. This increases the extent of the availability of the electrical machine and its associated overall system.

In one embodiment, the activated emergency mode is monitored. This will ensure that the emergency mode is working properly. In addition, it can be monitored when a return to a normal operating mode can take place.

The drive system according to the invention for an electrical machine has a control unit and a monitoring unit, wherein the control unit is connected to two data communication modules. The first data communication module forwards function messages and can be deactivated by the monitoring unit. The second data communication module can forward data for reprogramming the control unit and / or the monitoring unit. Also data for diagnosis, for applications or other can be passed on the second data communication block.

This means that the input for function messages is separate from the input for applications and for the transfer of new software. When transferring new software, the input for function messages can be deactivated. This has the advantage that in this period no false or nonsensical data be transmitted via this input or processes can become unsynchronized. This serves to avoid errors.

The monitoring of the corresponding components or signals and, if appropriate, the initiation of an error reaction or suitable measures takes place independently, i. regardless of a user reaction or, when used in a motor vehicle, regardless of a driver's reaction.

In response to a detected error, different error responses are possible. For example, the electric machine can be put out of operation. Depending on the type of electrical machine, the output stage can be disabled or the electrical machine is short-circuited via the power stage. The user can be informed in the event of a fault by optical or acoustic signals.

A particularly favorable error response is the activation of an emergency mode for operating the electric machine.

If an error occurs, the system can be reset. A reset is understood to mean the transfer of a system to a controlled state. This can be triggered by a software function call (ROM, RAM test, etc.) or by hardware measures such as watchdog, power-on reset, or the like. With a reset, a system that is in a faulty or undefined state can be restored to a permitted and defined state. This increases the availability of the system.

If an error occurs only for a meaningless short time, or if there is an error that does not affect the proper operation, then an error response may occur remain under. For example, for a certain time, the last error-free value may replace the current value that is not present because of the error. Only when the error lasts longer than allowed, an error reaction is triggered (debouncing).

In one embodiment of the drive system, the monitoring unit is connected via a data line to the control unit, via which the control unit can pass a reset-disable control command to the monitoring unit to prevent the transmission of a reset control command (from the monitoring unit to the control unit).

If the control unit is re-flashed (this refers to the dubbing of new or updated software), there will be no normal communication with the monitoring unit during this time. This situation could interpret the monitoring unit as an error in the control unit. In response, the monitoring unit would perform a reset of the control unit. This reaction is undesirable. Therefore, it is provided that the control unit can prevent a reset. In the embodiment described above, the control unit for this purpose sends a reset disable control command to the monitoring unit. Such functionality is not critical, as it only restricts the availability of the system acquired by the reset when an error occurs, but can not itself generate errors.

Further advantageous embodiments of the invention will become apparent from the dependent claims and with reference to the drawings. Showing: 1 shows a schematic structure of the apparatus for carrying out the method,

Fig. 2 shows an example of the time course of

Actual torque and the associated limit torques in torque mode and charging mode,

3 shows a representation of the permitted value ranges for the actual torque with the associated limit values in torque mode, charging mode and speed mode,

4 shows a representation of the permitted value ranges for the actual torque with the associated limit values in torque-0 emergency mode, charging emergency mode and VMStart emergency mode.

Fig. 1 shows a possible embodiment of the device according to the invention. In this case, an electric machine 1 is connected via an output stage 2 to a drive system.

Electrical machines 1 find their application in the most diverse fields. Used in a motor vehicle, the electric machine 1, for example, as a starter / generator or as a motor / generator operable. Likewise, the electric machine 1 can be used as the main drive of a motor vehicle, as an additional drive or for driving support of an internal combustion engine provided in the motor vehicle and / or for the energy supply of a vehicle electrical system provided in the motor vehicle.

The electric machine 1 can be designed, for example, as a permanent-magnet machine or as an asynchronous machine. Amplitude, frequency and phase of the phase currents of the electric machine 1 are set via the output stage 2. In one embodiment, the output stage 2 may be integrated in the control unit 3 of the drive system.

The drive system has a control unit 3 and a monitoring unit 4. The control unit 3 is connected to two data communication modules 5, 6, which are connected via a transceiver 7 to a data network 8.

The control unit 3 includes functions for controlling or for operating the electric machine 1. This part can therefore also be referred to as a functional level.

In the control unit 3 there is a monitoring of relevant for operating the electrical machine 1 components, the diagnosis of input and output variables, as well as a control of system reactions when an error occurs, wherein under a system, both the drive system and the electric machine 1 as well the combination of both components is understood.

The control unit 3 has, in particular, a function block in which drive signals for the output stage 2 are formed. These drive signals are supplied to the output stage 2 via unspecified lines.

The monitoring unit 4 is preferably used to monitor the control unit 3 or the functional sequences in the control unit 3. It is the task of the monitoring unit 4 to detect errors.

Further details and embodiments of the control unit 3 and the monitoring unit 4 and the method for Error detection can be found in DE 102 004 002 767 and will therefore not be explained in detail here.

As already described, the control unit 3 is connected to two data communication modules 5, 6, which are connected via a transceiver 7 to a data network 8.

The data communication modules 5, 6 can receive data from the data network 8 and forward it to the control unit 3. Likewise, the data blocks 5, 6 receive data from the control unit 3 and pass it on to the data network 8. The data communication modules 5, 6 can forward all received data or only a specific selection of the received data. In particular, they can filter out the data assigned to them from a common data set. For example, the data block 5 may be provided for the transmission of functional data. In particular, it may be provided to provide a data communication module 6 for the transmission of new software.

During the transmission of new software by the data communication module 6, it makes sense for security reasons to deactivate the data communication module 5. For this purpose, the connection between the transciever 7 and the data communication module 5 has a switch 13 which can interrupt the transmission of data in the direction of the transciever 7 and the data network 8. Via a data line 9, the control of the switch 13 can be carried out by the monitoring unit 4. Task of the switch 13 is to prevent meaningless or incorrect data from being passed on to the data network 8. The switch 13 can also be integrated into the data communication module 5 (eg as a software solution). Other equivalent solutions are possible. Control unit 3 and monitoring unit 4 are connected via a communication path 11 with each other. This communication path 11 transmits data from the control unit 3 to the monitoring unit 4 and vice versa.

The control unit 3 and the monitoring unit 4 are connected via a reset path 12 with each other. About this reset path 12, a reset command from the

Monitoring unit 4 are passed to the control unit 3.

The control unit 3 and the monitoring unit 4 are connected to one another via a reset-disable path 10. Via this reset-disable path 10, the control unit 3 can send a reset-disable command to the monitoring unit 4 and thus prevent the transmission of a reset command from the monitoring unit 4 to the control unit 3.

Both the control unit 3 and the monitoring unit 4 have their own shutdown path 14, 15 for switching off the output stage 2.

The control system may be associated with a further monitoring level, not shown, which tests by a question / answer principle the proper functioning of the control system or the control unit 3 or the monitoring unit 4. Should an error occur, the triggering of corresponding system reactions or error measures preferably takes place independently of the control unit 3, independently of the monitoring unit 4 and independently of the output stage 2. For power supply of the drive system and the electric machine 1 is not shown Strombzw. Voltage source provided.

The control of the electric machine 1 via the Ansteuersystem .. In this case, the electric machine 1 can be operated in different modes. For example, a torque mode, and a charging mode may be provided. This has the advantage that the electric machine 1 can be set exactly to the behavior desired by the consumer. Of course, other modes can be provided. FIG. 2 shows an example of the time profile of the actual torque in torque mode and charging mode and the associated limit torques. The time is shown on the x-axis and the moment on the y-axis. In the example shown, the electric machine 1 starts at time zero with a moment zero. The electric machine 1 is in torque mode. In torque mode, the electric machine 1 in the engine operation (positive target torque Mmax) or in the generator mode (negative target torque Mmax) can be operated.

First, the torque mode is operated in the example shown in the engine operation. The setpoint Mmax is first raised from 0 Nm to 10 Nm and later to 100 Nm. Subsequently, Mmax is lowered from 100 Nm to 50 Nm. Starting from Mmax = 50 Nm, the torque mode of the electric machine changes from engine operation to generator operation. For this purpose, a setpoint value of -100 Nm is specified for generator operation.

The change of the setpoint value Mmax takes place without transition as a step function. The actual torque M_act adapts to the target value Mmax, approaching Mmax asymptotically. This results in the change of Mmax = 100 Nm to Mmax = 50 Nm and in the change of Mmax = 50 Nm to Mmax = -100 Nm, that M_ist is above Mmax while approaching the new setpoint (50 Nm or -100 Nm).

The permissible limit values Mmax_z and Mmin_z adapt to the setpoint Mmax. When the setpoint Mmax is increased, the upper limit value Mmax_z also jumps to a higher value. If the setpoint value Mmax is lowered, the upper limit value Mmax_z approaches its new value asymptotically so that it always remains at a distance above M_act. Mmax_ z is therefore always larger than Mmax. When the set value Mmax transits to negative values in the generator mode of the torque mode, the upper limit Mmax_z approaches a fixed low positive value (for example, 5 Nm).

The lower limit Mmin_z assumes a fixed low negative value (e.g., -5 Nm) as long as the torque mode is in engine operation. In generator mode, the lower limit Mmin_z assumes a value at a specified distance below the Mmax. Mmin_z jumps down when the new set value Mmax is more negative than the previous set value Mmax. If the setpoint Mmax goes from a negative value to a smaller negative setpoint Mmax (or a positive setpoint Mmax), then Mmin_z asymptotically approaches the new limit Mmin_z. Mmin_z always lies at a distance below Mmax.

From the generator mode of the torque mode, the electric machine 1 and its drive system change into the charging mode in the example shown in FIG. 2.

In charge mode, a setpoint voltage Usoll is specified, which is to be converted by an actual voltage Uist. For this purpose, a correspondingly suitable negative moment M_act must be generated become. From the data network 8, a minimum torque Mmin is specified, which serves as the lower limit value for the actual torque M_act. Like Mmax in torque mode, Mmin changes its value without transition in load mode. In the present example, the setpoint for the torque is a Mmin of -50 Nm.

The M_ist approaches asymptotically from the previous M_act of -100 Nm in FIG. 2 to the new nominal value of -50 Nm.

Mmin_z approaches asymptotically the new limit Mmin_z. Mmin_z is always at a distance below Mmin.

When switching from torque mode to the charging mode Mmax changes from a variable default value to a fixed upper limit, which is approximately 10 Nm in the example shown. The change takes place as a jump. Likewise, Mmax_z jumps to a fixed value which is above Mmax_z and in the example shown is approximately 20 Nm.

The following table shows the control variables of the different operating modes:

The torque control of the operating modes is shown in FIG.

In torque mode, the moment M_ist is to be regulated. For this purpose, a setpoint Mmax is specified by the data network. Mmax is then considered admissible if it is less than or equal to the upper permissible limit value Mmax_z and greater than or equal to the lower permissible limit value Mmin_z. In this case, the torque mode distinguishes between a motor operation of the electric machine and a generator operation of the electric machine.

In motor operation of the torque mode, a positive actual torque M_act is to be generated. Accordingly, a positive setpoint torque Mmax is specified. This target torque Mmax may be in the range between the positive upper limit Mmax_z and the slightly negative lower limit Mmin_z.

In the generator mode of the torque mode should be generated by braking the electric machine power. Thus, a negative actual torque M_act must be generated. Accordingly, a negative target torque Mmax is specified. This target torque Mmax may be in the range between the slightly positive upper limit Mmax_z and the lower negative limit Mmin_z move.

In the charging mode, the electric machine 1 is controlled so that an effective charge of a battery can be achieved. The variable to be controlled is the voltage Uist. It is controlled by the coming from the data network 8 target voltage Usoll. The moment M_act is set in the loading mode so that it is possible to reach üist = Usoll. Default for the moment M_ist is Mmin, which comes from the data network 8. The allowable limits for M_ist are set by Mmin_z, Mmax_z and Mlim. M_ist should preferably be in the range between Mmin_z (better Mmin) and Mlim. A value between Mlim and Mmax_z is only allowed for a specified limited amount of time.

In speed mode, the speed is the amount that should be kept constant or varied according to the wishes of the consumer. The variable to be controlled is the speed of the electric machine Nist. It is controlled via the setpoint speed Nsetpoint coming from the data network 8. The specification for the limits of the moment M_act are Mmin and Mmax.

If Nset is greater than or equal to Nist then Mmax is the maximum allowable limit for M_act and a speed governor should set a positive torque setpoint Msetpoint. In this case, a positive value for the upper limit Mmax_z and a slightly negative value for the lower limit Mmin_z are given.

If Nset is less than Nist, Mmin is the minimum allowable limit for M_act and a speed governor should set a negative torque setpoint Msetpoint. In this case, there will be a slightly positive value for the upper one Limit Mmax_z and a negative value for the lower limit Mmin_z specified.

In the event of a failure of the data network 8, control variables can no longer be supplied externally to the control system. In order to ensure safe operation of the electric machine, albeit to a limited extent, in the event of a failure of the data network 8, emergency modes are provided.

4, the emergency modes are shown. In the emergency modes, the setpoints and the tolerance limits are specified internally. Thus, the electric machine 1 can be operated even in the event of failure of the data network 8.

In moment 0-emergency mode, the moment M_act is set to zero. For this purpose, the internal limits Mmax_z and Mmin_z are specified internally. M_ist is considered admissible if it is less than or equal to the upper permissible limit value Mmax_z and greater than or equal to the lower permissible limit value Mmin_z.

In charging emergency mode, the electric machine 1 is controlled so that a charge of a battery is possible. The variable to be controlled is the voltage Uist. It is controlled by an internally specified setpoint voltage Usoll_int. The moment M_ist should preferably be negative. Therefore, M_ist should preferably be in the range between Mmin and Mmax. The permissible upper limits for M_ist are defined by Mmin_z and Mmax_z.

The speed mode is needed especially for starting an internal combustion engine. To ensure this function even if the data network 8 fails is a Emergency mode is provided, which is referred to below as VMStart emergency mode.

In VMStart emergency mode, the speed of the electric machine Nist is the quantity to be controlled. It is controlled by the internally specified setpoint speed Nset_int. The setpoint for the moment M_act is limited by Mmin and Mmax.

The setpoint value for the moment M_actually preferably corresponds to Mmin or Mmax.

If Nist is less than or equal to Nset_int, then Mmax is the setpoint for M_act. In this case, a positive value for the upper limit Mmax_z and a slightly negative value for the lower limit Mmin_z are given internally.

If Nist is greater than Nset_int, then Mmin is the setpoint for M_ist. In this case, a slightly positive value for the upper limit Mmax_z and a negative value for the lower limit Mmin_z are given internally.

Claims

claims

Anspruch [en] A method for operating an electrical machine having an electrical drive system with a control unit (3) and an independent monitoring unit (4), which has a plurality of operating modes of the electrical

Machine provides and monitoring of an operating variable of the electric machine and / or the drive system performs, characterized in that an emergency mode is started when the monitoring unit (4) detects an error that requires the activation of an emergency mode.

2. The method according to claim 1, characterized in that in the emergency mode, a desired torque is set with the value zero.

3. The method according to any one of claims 1 or 2, characterized in that a charging mode designated as an operating mode is assigned a separate emergency mode, which allows only negative target torques.

4. The method according to any one of claims 1 to 3, characterized in that a designated as a speed mode operating mode is assigned a separate emergency mode for the start of an internal combustion engine.

5. A method for operating an electrical machine (1) with an electrical drive system with a control unit (3) and an independent monitoring unit (4), which performs a monitoring of an operating variable of the electric machine (1) and / or the drive system, wherein regardless of the torque request of the driver, an additional torque-influencing intervention is performed, characterized in that

- To monitor the torque-influencing engagement, the time integral of the target torque of the torque-influencing engagement with a predetermined upper limit and a predetermined lower limit is compared, and

- If one of these limits is exceeded by the target torque-time integral of the torque-influencing engagement an error of the torque-influencing engagement is detected.

6. The method according to any one of claims 1 to 5, characterized in that

a suitable emergency mode is selected when an error has been detected which requires the activation of an emergency mode,

- the plausibility of the request for the emergency mode is checked,

- if the request is plausible, the emergency mode is activated, - If an implausible request of the emergency mode, a reset of the electrical control system is performed.

7. The method according to any one of claims 1 to 6, characterized in that a monitoring of the activated emergency mode takes place.

8. control system for an electrical machine (1), with a control unit (3) and a control unit independent of this (4), characterized in that a data line (12) is provided, via which the monitoring unit (4) the control command for a Reset to the control unit (3) can pass.

9. Control system according to claim 8, wherein the control unit (3) with two data communication modules (5, 6) is connected, characterized in that

- the first data communication module (5) forwards function messages and can be deactivated by the monitoring unit (4), and

- The second data communication module (6) can forward data for reprogramming the control unit (3) and / or the monitoring unit (4).

10. Control system according to claim 8, characterized in that the monitoring unit (4) via a data line (10) to the control unit (3) is connected, via which the control unit (3) a reset-disable control command to the monitoring unit (4) can pass on.