How to operate the drive unit

Abstract

A method for operating a drive unit (1) with an electric motor (2), the drive unit (1) comprising the electric motor (2), an electric circuit (3) for operating the electric motor (2), and a control device (4) for operating the electric circuit (3). The electric motor (2) has at least a stator (5) with at least three coils (6, 7, 8) and a rotor (9) with at least two magnetic poles (10, 11). The electric circuit (3) has at least a first potential terminal (12) and a second potential terminal (13), and the terminals (12) and (13) can be connected to different potentials of a DC voltage source (14). The electric circuit (3) has three half bridges (15, 16, 17) between the potential terminals (12, 13). Each of the coils (6, 7, 8) is conductively connected to one of the half-bridges (15, 16, 17) via a corresponding first connection (18) and to the other of said coils (6, 7, 8) via a corresponding second connection (19).

Description

Technical Field

[0001] The present invention relates to a method for operating a drive unit. The drive unit includes an electric motor, an electric circuit for operating the electric motor, and a control device for operating the electric circuit. The electric motor has at least a stator and a rotor.

Background Art

[0002] Electric motors are used, for example, as traction drives in motor vehicles. In particular, a predetermined torque is supplied by the electric motor. In particular, for electric motors used in this way, it should be ensured that they can operate accurately or that the motor can achieve the desired results during operation.

[0003] Patent Document 1 relates to an abnormality diagnosis device for monitoring an electric motor. In this case, the current waveform or drive frequency of the electric motor is detected and evaluated by frequency analysis.

[0004] Patent Document 2 relates to a diagnosis device for a rotating machine system. This is for diagnosing the state of a rotating machine system. The current waveform and drive frequency during operation of a rotating electric motor are detected to detect a short-circuit current.

[0005] From Patent Document 3, a method for diagnosing an electrical system is known. Here, the motor is short-circuited during operation to evaluate the short-circuit current.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

[0007] Therefore, the object of the present invention is to at least mitigate or solve the technical problems considered in relation to the prior art. In particular, a method for operating a drive unit is proposed. In this method, it is possible to detect and evaluate the state of the drive unit, and various sensors necessary for operating the drive unit are used.

[0008] To achieve this objective, the method described in the features of claim 1 is proposed. Advantageous developments are the subject matter of the dependent claims. The features enumerated in the claims can be combined in technically feasible ways and may be supplemented by the descriptive technical content and photographic details of this specification, which disclose further embodiments of the present invention.

[0009] A method for operating a drive unit equipped with an electric motor is proposed. The drive unit comprises at least an electric motor, an electrical circuit for operating the electric motor, and a control device for operating the electrical circuit. The electric motor has at least a stator having at least three coils and a rotor having at least two magnetic poles. The electrical circuit has at least a first potential terminal and a second potential terminal, which can be connected to different potentials of a DC voltage source. The electrical circuit has three half-bridges between the potential terminals, with each coil conductively connected to one of the half-bridges via a corresponding first connection and conductively connected to the other coil via a corresponding second connection. The electrical circuit has at least three current sensors for measuring the output current conducted via the corresponding first connections.

[0010] This method, a) A step in which the control device (4) determines the first position of the rotor's magnetic poles relative to the stator during rotation, b) A step of generating a voltage signal by an electrical circuit, wherein the voltage signal has only a first phase position identical to the first position, c) A step of measuring the current signal generated by the voltage signal using a current sensor, d) A step of evaluating the current signal using a control device and evaluating the state of the drive unit. This method includes at least the following:

[0011] Dividing the method steps into steps a) to d) as described above (not exhaustively) is primarily intended to facilitate distinction and does not impose any order, dependency, or both. For example, the frequency of the method steps may be varied during the preparation of the drive unit, during the operation of the drive unit, or both. It is also possible for the method steps to overlap in time, at least partially. Method step d) is very preferably performed during step c), or in addition to that, during step b). Steps b) to d) may be conditional and may be performed only if, if necessary, the first position can be determined in step a). Similarly, steps c) and d) may also be conditional and may be performed only if, if necessary, it is possible to measure or evaluate the current signal. Steps a) to d) are performed in the order described.

[0012] In particular, an electric motor has at least one stator and one rotor. The rotor is rotatably positioned relative to the stator. In particular, the rotor has permanent magnets and can therefore be driven by the rotating stator field. An electric motor can be designed in known ways. In particular, the rotor has at least two magnetic poles, but may also have 2*n (n=2, 3, 4, ...) magnetic poles.

[0013] The electrical circuit is designed in a particularly known manner and has a first potential terminal and a second potential terminal for driving an electric motor, and these terminals can be connected to different potentials (e.g., positive and ground) of a DC voltage source. In particular, three half-bridges are provided between the potential terminals, and each coil of the electric motor is electrically conductively connected to one of the half-bridges via a first connection and electrically conductively connected to the other coils via a second connection. In particular, some coils can also be connected to the first connection.

[0014] Three half-bridges in the electrical circuit make it possible to generate a three-phase current system or a multi-phase square current, with the phases shifted by 120 degrees from each other. Each output current or phase current is conducted to or applied to a coil via the corresponding first connection. The coils are connected to each other via a second connection, and since the different output currents or phase currents cancel each other out at the so-called star point, no separate or additional return conductors (Ruckleiters) are required to the other potential terminals.

[0015] In particular, in known methods, a half-bridge consists of a device comprising an upper transistor and a lower transistor, through which each potential terminal is connected to the others. Specifically, a diode is connected in parallel with each transistor.

[0016] In particular, each half-bridge comprises at least one upper transistor (high-side transistor) and one lower transistor (low-side transistor) electrically conductively connected to each other. The upper transistor is electrically conductively connected to a first potential terminal, and the lower transistor is electrically conductively connected to a second potential terminal. Each half-bridge has a corresponding first connection between the upper and lower transistors, through which the corresponding coil is connected to the related half-bridge.

[0017] When a voltage signal is applied, a corresponding output current is generated via each of the half - bridges, and this output current is applied, via the corresponding first connection, to the associated coil of the electric motor. The output current that can be generated in such a way is detected in an electrical circuit known to the current sensor, so that it becomes possible to control the electric motor during the operation of the drive unit.

[0018] Compared with known drive units, the proposed method requires, in particular, only one control device appropriately designed for carrying out this method. This control device starts the method and the electrical circuit for generating the voltage signal operates.

[0019] In step a), in particular, the first position of the rotor poles relative to the stator in rotation is determined by the control device. The first position can be determined by known methods. For example, the position sensor of the electric motor may be evaluated.

[0020] [[ID= twelve]]In step b), a voltage signal is generated by the electrical circuit, and this voltage signal has only the same first phase position as the first position. [[ID=十四]]

[0021] Therefore, the phase angle (first phase position) of the voltage or voltage signal is set to correspond to the phase angle (first position) determined in step a).

[0022] [[ID=twenty]]The voltage applied to the electric motor increases the output current of the electrical circuit. The time response and the steady - state final value of the output current are determined here by the electrical time constant of the motor winding of the stator, that is, by the resistance and the inductance. Since the phase angle of the obtained output current corresponds to the first position of the poles, that is, the phase angle of the permanent - magnet flux, no torque is generated in the electric motor here. [[ID=二十二]]

[0023] In step c), the measurement of each current signal (of the output current of the corresponding first connection) generated by the voltage signal is carried out by the current sensor.

[0024] The output current, i.e., the output current that is generated across the corresponding half - bridge and flows towards each coil across the corresponding first connection, is measured by a current sensor that is normally present in the electrical circuit.

[0025] In particular, the measurement of the output current or the current signal is carried out over time or over a time interval or a test period. In particular, this measurement is carried out until a constant - value current signal or a constant - value current intensity is established, or until a constant value can be determined (for example, until it can be determined by calculation when the rise of the current signal is asymptotic).

[0026] In step d), the current signal is evaluated by the control device. For example, it is evaluated with respect to at least the rise of the current signal over time or the test period, or with respect to the value of the current signal reached after a certain time. The rise or the value of this current signal is used, in particular, to evaluate the state of the drive unit 1.

[0027] From the resistance and inductance of the motor winding or the electric motor, as explained above, the relevant parameters of the electric motor can be known. These parameters serve as a reference for the behavior of the rise of the current signal or the behavior of the current signal during the test period.

[0028] In particular, in steps c) and d), the steady - state final value of the current signal resulting from the voltage signal, i.e., the intensity of the current, can be determined or evaluated. In particular, the current signal is formed, for example, by superimposing each current signal or each output current measured at each first connection, and this current signal can be compared with a predefined value stored in the control device. If the deviation from this value is within the defined tolerance range, the entire series of processes consisting of the clock transistor or the half - bridge and their operation, the connected motor, and the measurement of the current signal by the current sensor can be considered to be functioning.

[0029] In particular, in steps c) and d), the rise time of the current signal generated from the voltage signal, i.e., the strength of the current over time, can be determined or evaluated. Specifically, the current signal is formed, for example, by superimposing the current signals or output currents measured at each of the first connections, and this current signal can be compared with a predefined current signal stored in the control device, or with its curve, i.e., rise time.

[0030] If the output current or current signal increases more slowly than the value stored in the control device, this may indicate, for example, that a voltage has been applied incorrectly, or that the position of the permanent magnet or magnetic pole has been measured incorrectly.

[0031] In permanently excited synchronous machines, often used in traction drives, the electrical time constants parallel (d-axis) and perpendicular (q-axis) to the position of the permanent magnets are usually quite different. In most cases, the d-axis time constant is smaller than the q-axis time constant. This characteristic can also be taken into consideration in the evaluation in step d).

[0032] The proposed method allows for the inspection of at least the course or value of a current signal, particularly using motor monitoring implemented solely in software form (i.e., compared to known drive units without further hardware), and, depending on this course or value, to determine whether the drive unit is in a faulty or OK state.

[0033] If no error is detected in step d), the drive unit can perform its intended operation, for example, by supplying the requested torque with the electric motor. In case of failure, for example, the electric motor can be prevented from operating further so as not to generate any more of the requested torque.

[0034] In particular, in step d), each current signal is evaluated by the control device with respect to the rise time of the current signal, or with respect to the value of the current signal or current strength reached after time, time interval, or test period. In particular, the current signal is measured until a constant value of the current signal or current strength is established.

[0035] In particular, each half-bridge has at least an upper transistor and a lower transistor that are electrically conductively connected to each other. The upper transistor is electrically conductively connected to a first potential terminal, and the lower transistor is electrically conductively connected to a second potential terminal. In particular, each half-bridge has a contact between the upper and lower transistors, and through each contact, the first connection is connected to the corresponding half-bridge.

[0036] In step b), a pulse pattern is selected in which all transistors are clocked in order to generate the voltage signal. Specifically, since the voltage signal is generated as a PWM signal (pulse width modulation signal), the voltage signal is composed of multiple individual signals.

[0037] When all transistors are clocked, the entire electrical circuit can be examined within the framework of this method. In particular, the function of each individual transistor or half-bridge can be examined.

[0038] In particular, the voltage signal has a constant voltage value. Here, "constant" means that the voltage value deviates by no more than 5%, more specifically, by no more than 2%, and preferably by no more than 1%.

[0039] In particular, the rotor has a constant first position at least during step a). Specifically, during step d), changes in the rotor's position are detected and evaluated.

[0040] In particular, the rotor is stationary relative to the stator, i.e., its velocity is zero. If a change in the rotor's position is detected during step b), i.e., if the rotor changes its first position or phase angle as a result of the voltage signal and the current signal generated thereby and applied to the electromechanical unit, it can be concluded that there is a fault in the drive unit.

[0041] In particular, it can detect the following failures in the drive unit and take corrective action as needed. • The actual position of the rotor is different from the first position determined in step a). • At least one transistor or half-bridge in the electrical circuit is not clocking. • At least one of the current sensors is defective, or the current sensor is incorrectly measuring the current signal, preventing the control device from performing control correctly. • The electric motor has a defect, such as a short circuit in one of its terminals.

[0042] In particular, the rotor rotates relative to the stator at least during steps a), b), and c). Specifically, the electrical circuit that intentionally supplies or generates torque does not generate a voltage signal between steps b) and d). Instead, only a voltage signal generated within the framework of this method (where torque should not be generated as much as possible) is applied.

[0043] Therefore, since the voltage signal has only a first phase position identical to the first position of the magnetic pole, no torque is generated by the voltage signal applied within the framework of this method. In particular, it is necessary to assume that the first position determined in step a) is correct.

[0044] In step d), the established value of the current signal can be determined and compared with the value stored in the control device. If the deviation from this value is within a defined tolerance range, the entire process consisting of the clock transistor or half-bridge and their operation, the connected motor, and the measurement of the current signal by the current sensor can be considered to be functioning correctly.

[0045] In particular, this method is initiated if at least one of the following conditions is met: • Restart the drive unit • The rotor is stationary relative to the stator. • The rotor rotates without torque relative to the stator.

[0046] In particular, if the current signal evaluated in step d) is within the acceptable range relative to the reference current signal stored in the control device, the electric motor is started to operate and generate torque. However, if the current signal is outside the acceptable range, the control device generates an error message. In this case, the electric motor will not start, and it will be prevented from using the electric motor to generate torque.

[0047] In particular, the tolerance range may include deviations from the rising edge, final value, or both of the reference current signal stored in the control device. The deviation can be defined, for example, over a specific time while the current signal is rising, or over a specific time while the current signal is being measured, or over the entire time. Specifically, the deviation from the reference current signal may be at most 5%, preferably at most 2%. The acceptable deviation can be determined for each drive unit.

[0048] A further drive unit is proposed. This drive unit comprises at least an electric motor, an electrical circuit for operating the electric motor, and a control device for operating the electrical circuit. The drive unit or control device is designed and configured to carry out the present method.

[0049] Further proposals are made for automotive drivetrains. These drivetrains include the aforementioned drive units, and the electric motor is a traction drive that supplies the driving torque to the drivetrain.

[0050] In particular, the control device is mounted, configured, or programmed in such a manner that the drive unit or electrical circuit can operate in accordance with the aforementioned method.

[0051] Furthermore, this method can also be executed by a computer or by the processor of a control unit.

[0052] We further propose a data processing system comprising a processor adapted and configured to perform this method, or to perform some of the steps of the proposed method.

[0053] A computer-readable storage medium can be provided that, when executed by a computer / processor, has instructions that cause the computer / processor to execute this method or instructions that cause the computer / processor to execute at least a part of the steps of the proposed method.

[0054] In particular, the description of this method can be adapted to methods implemented in drive units, drivetrains, or computers, and vice versa.

[0055] In particular, in the claims and descriptions that reiterate these claims, the indefinite articles ("ein," "eine," "einer," "eines") are intended to be understood as they are, not as numerals. Therefore, the terms and elements introduced in response to them should be understood to appear at least once, but especially as many times.

[0056] To avoid any doubt, the ordinal numbers used herein ("first," "second," etc.) are used primarily to distinguish several similar objects, numbers, or steps, and not in any particular way to define any dependencies or order between these objects, numbers, or steps. Where dependencies or order are necessary, this will be explicitly stated herein or will become apparent to those skilled in the art by examining the actual configurations described.

[0057] The present invention and its technical background will be described in more detail below with reference to the figures. It should be noted that the present invention is not intended to be limited by the embodiments described herein. Unless otherwise specified, it is also possible to extract specific features of the technical content described in the figures and combine them with other components and insights obtained from this specification and the figures. The same reference numerals refer to the same object, and therefore, explanations from other figures may also be used in conjunction. The figures are schematic. [Brief explanation of the drawing]

[0058] [Figure 1] This shows the drivetrain of an automobile equipped with a drive unit. [Figure 2] Figure 1 shows a portion of the drive unit and the operation of this method. [Figure 3] Steps a) and b) of this method are shown for when the drive unit is in OK condition. [Figure 4] Steps a) and b) of this method are shown for when the drive unit is in OK condition. [Figure 5] Steps a) and b) of this method are shown for when the drive unit is in a faulty state. [Figure 6] Steps c) and d) of this method are shown for when the drive unit is in a faulty state. [Figure 7] This section compares steps a) and d) of this method when the drive unit is in a faulty state and when it is in an OK state. [Figure 8] The sequence of this method is shown below. [Figure 9] The detailed sequence of this method is shown below. [Modes for carrying out the invention]

[0059] Figure 1 shows the drivetrain 34 of an automobile equipped with a drive unit 1. Figure 2 shows a part of the drive unit 1 in Figure 1 and the operation of this method. Figure 3 shows steps a) and b) of this method when the drive unit 1 is in an OK state. Figure 4 shows steps c) and d) of this method when the drive unit 1 is in an OK state. Figures 1 to 4 will all be explained below.

[0060] The drive unit 1 comprises an electric motor 2, an electrical circuit 3 for operating the electric motor 2, and a control device 4 for operating the electrical circuit 3. The drive unit 1 or the control device 4 is appropriately designed and equipped to perform the method described. The electric motor 2 is a traction drive that supplies driving torque to the drivetrain 34.

[0061] The control device 4 includes a motor actuator 35 and a motor monitoring unit 36. The electrical circuit 3 is connected to the motor actuator 35 and the motor monitoring unit 36 ​​via a safety logic unit 37. The motor actuator 35 can activate the electrical circuit 3 after detecting the state of the drive unit 1, and thus activate the electric motor 2. The motor monitoring unit 36 ​​accesses some of the signals available in the motor actuator 35, thereby revealing a fault in the measuring chain (Messkette). If the motor monitoring unit 36 ​​detects a fault condition in the drive unit 1 within the framework of this method, the safety logic unit 37 can disable the operation of the electric motor 2.

[0062] The electric motor 2 has at least a stator 5 having at least three coils 6, 7, and 8, and a rotor 9 having at least two magnetic poles 10 and 11 (see Figures 3 to 6). The electrical circuit 3 has a first potential terminal 12 and a second potential terminal 13 that can be connected to different potentials of the DC voltage source 14. A DC voltage capacitor 38 is arranged in parallel with the electrical circuit 3.

[0063] The electrical circuit 3 has three half-bridges 15, 16, and 17 between potential terminals 12 and 13. Here, coils 6, 7, and 8 are electrically conductively connected to one of the half-bridges 15, 16, and 17 via a corresponding first connection 18, and electrically conductively connected to the other coils 6, 7, and 8 via a corresponding second connection 19. The electrical circuit 3 has three current sensors 20 for measuring the output current 21 conducted through each of the first connections 18.

[0064] In known methods, half-bridges 15, 16, and 17 consist of a device comprising an upper transistor 27 and a lower transistor 28, through which potential terminals 12 and 13 are connected to each other. In each of the half-bridges 15, 16, and 17, the upper transistor 27 and the lower transistor 28 are electrically conductively connected to each other. The upper transistor 27 is electrically conductively connected to the first potential terminal 12, and the lower transistor 28 is electrically conductively connected to the second potential terminal 13. Each of the half-bridges 15, 16, and 17 has a corresponding first connection 18 between the upper transistor 27 and the lower transistor 28, through which the corresponding coils 6, 7, and 8 are connected to the related half-bridges 15, 16, and 17. Each of the first connections 18 is connected to the corresponding half-bridges 15, 16, and 17 via contacts 29.

[0065] When a voltage signal 23 is applied, a corresponding output current 21 is generated through the half-bridges 15, 16, and 17, respectively, and this output current is applied to the associated coils 6, 7, and 8 of the electric motor 2 via the corresponding first connection 18. The output current 21 that can be generated in this manner is detected by the current sensor 20 in the electrical circuit 3, so that the electric motor 2 can be controlled while the drive unit 1 is operating.

[0066] In step a), the control device 4 determines the first rotational position 22 of the magnetic poles 10 and 11 of the rotor 9 relative to the stator 5 (see Figure 3). The first position 22 can be determined by known methods. For example, a known position sensor of the electric motor 2 (not shown here) may be evaluated.

[0067] In step b), a voltage signal 23 is generated by the electrical circuit 3 (see the upper left diagram in Figure 2 and the lower diagram in Figure 3; the vertical axis is voltage 39 and the horizontal axis is time 26). The voltage signal 23 has the same first phase position 24 as the first position 22 (see the upper diagram in Figure 3).

[0068] In step b), a pulse pattern is selected that clocks all transistors 27 and 28 in order to generate the voltage signal 23. Since the voltage signal 23 is generated as a PWM signal (pulse width modulation signal), the voltage signal 23 is composed of multiple individual signals.

[0069] Figure 3 (and Figures 4, 5, and 6) shows a coordinate system fixed to the stator, having a first axis 43 and a second axis 44, and a coordinate system fixed to the rotor, having a third axis 45 and a fourth axis 46. The third and fourth axes 45 and 46 rotate with respect to the first and second axes 43 and 44, together with the magnetic poles 10 and 11.

[0070] Therefore, the phase angle of the voltage or voltage signal 23 (first phase position 24) is set to correspond to the phase angle (first position 22) determined in step a) (see the top of Figure 3).

[0071] The voltage 39 applied to the electric motor 2 increases the output current 21 of the electrical circuit 3 (see the lower diagram in Figure 4; the vertical axis represents current 47, and the horizontal axis represents time 26). The time response and the final steady-state value 40 of the output current 21 are determined here by the electrical time constant of the motor winding of the stator 9, i.e., by the resistance 41 and inductance 42. Since the phase angle of the obtained output current 21 corresponds to the first position 22 of the magnetic poles 10 and 11, i.e., the phase angle of the permanent magnet flux (see Figure 4), no torque is generated in the electric motor 2 here.

[0072] In step c), the current sensor 20 measures each current signal 25 (of the output current 21 of the corresponding first connection 18) generated by the voltage signal 23.

[0073] The output current 21, that is, the output current 21 generated across the corresponding half-bridges 15, 16, and 17 and flowing through the corresponding first connection 18 toward the coils 6, 7, and 8, is measured by a current sensor 20 that is normally present in the electrical circuit 3.

[0074] The output current 21 or current signal 25 (the entire current signal 25) is measured over time 26, time intervals, or the test period. This measurement is performed until a constant (final) value 40 of the current signal 25 or a constant (final) value 40 of the current strength is established, or until a constant value can be determined (for example, until it can be determined by calculation when the rising edge of the current signal 25 is asymptotic).

[0075] In step d), the current signal 25 is evaluated by the control device 4. For example, it is evaluated with respect to at least the rising edge of the current signal 25 over time 26 or the test period, or with respect to the final value 40 of the current signal 25 reached after a certain time. This rising edge or final value 40 of the current signal 25 is used to evaluate the state of the drive unit 1.

[0076] The motor windings or the resistance 41 and inductance 42 of the electric motor 2 reveal the relevant parameters of the electric motor 2. These parameters serve as a reference for the rising edge behavior of the current signal 25 or the behavior of the current signal 25 during the test period.

[0077] Therefore, in steps c) and d), the steady-state final value 40 of the current signal 25 generated from the voltage signal 23, i.e., the strength of the current, can be determined or evaluated. The current signal 25 is formed, for example, by superimposing each current signal 25 or each output current 21 measured at each of the first connections 18, and this current signal 25 can be compared with a predefined value stored in the control device 4. If the deviation from this value is within the defined tolerance range 31, the entire process consisting of the clock transistors 27, 28 or half-bridges 15, 16, 17 and their operation, the connected motor 2, and the measurement of the current signal 25 by the current sensor 20 can be considered to be functioning.

[0078] The proposed method allows for the inspection of at least the elapsed or (final) value 40 of the current signal 25 using motor monitoring implemented solely in software form (i.e., compared to a known drive unit 1 without further hardware), and determines whether the drive unit 1 is in a faulty or OK state based on this elapsed or (final) value 40.

[0079] If no error is detected in step d), the drive unit 1 can perform its intended operation, for example, by supplying the requested torque to the electric motor 2. In case of failure, for example, the electric motor 2 can be prevented from operating further so as not to generate any more of the requested torque.

[0080] Figure 5 shows steps a) and b) of this method when drive unit 1 is in a faulty state. Figure 6 shows steps c) and d) of this method when drive unit 1 is in a faulty state. Both Figures 5 and 6 will be explained below. Refer to the explanations of Figures 1 to 4.

[0081] Figure 5 shows that the phase angle (first phase position 24) of the voltage or voltage signal 23 is shifted from the first position 22. For example, the first position 22 in rotation of the magnetic poles 10 and 11 of the rotor 9 relative to the stator 5 is determined by the control device 3, which is performed in conjunction with step a), and therefore an error occurs here.

[0082] If a change in rotor position is detected during step b), that is, if the rotor changes its first position or phase angle as a result of the voltage signal and the current signal generated thereby and applied to the electromechanical unit, it can be concluded that there is a fault in the drive unit.

[0083] In step c), the current sensor 20 measures each current signal 25 (of the output current 21 of the corresponding first connection 18) generated by the voltage signal 23.

[0084] In step d), the current signal 25 is evaluated by the control device 4. For example, it is evaluated with respect to at least the rising edge of the current signal 25 over time 26 or the test period, or with respect to the final value 40 of the current signal 25 reached after a certain time. This rising edge or final value 40 of the current signal 25 is used to evaluate the state of the drive unit 1.

[0085] Here, it can be seen that the output current 21 or current signal 25 increases more slowly than the value stored in the control device 4. As already explained, this may indicate that the voltage 39 was applied incorrectly, or the voltage signal 23 was generated incorrectly, or the first position 22 of the permanent magnet or magnetic poles 10, 11 was measured incorrectly.

[0086] Figure 7 shows a comparison of steps a) to d) of this method when drive unit 1 is in a faulty state and when it is in an OK state.

[0087] In the figure above, the signal value 48 is plotted on the vertical axis and time 26 is plotted on the horizontal axis. The method described above is started by a first trigger signal 49. This method is terminated by a second trigger signal 49, or by the voltage signal 23 generated in step b).

[0088] In the second figure from the top, voltage 39 is plotted on the vertical axis and time 26 is plotted on the horizontal axis. The method is started when activated by a trigger signal 49, and in step a), the first positions 22 of the magnetic poles 10 and 11 are determined. In step b), a voltage signal 23 of the first phase position 24 is generated. The voltage signal 23 has a constant voltage value 30 over time 26.

[0089] In the third figure from the top, the current (47) is plotted on the vertical axis, and time (26) is plotted on the horizontal axis.

[0090] The voltage signal 23 generated in step b) and the voltage 39 applied to the electric motor 2 thereby increase the output current 21 of the electrical circuit 3. The time response and steady-state final value 40 of the output current 21 are determined here by the electrical time constant of the motor winding of the stator 9, i.e., by the resistance 41 and inductance 42.

[0091] The third figure from the top shows the first elapsed time 50 and the second elapsed time 51 of the rising edge of the current signal 25 of the output current 21 measured in step c).

[0092] The first elapsed time 50 shows the startup and final value 40 of the drive unit when there are no malfunctions or the condition is OK.

[0093] The second step, 51, shows the startup and final value 40 of the drive unit in the case of a malfunction.

[0094] In steps c) and d), the steady-state final value 40 of the current signal 25 generated from the voltage signal 23, i.e., the current strength, is determined or evaluated. The current signal 25 is formed, for example, by superimposing each current signal 25 or each output current 21 measured at each of the first connections 18, and this current signal 25 can be compared with a predefined value stored in the control device 4. If the deviation from this value is within the defined tolerance range 31, the entire process consisting of the clock transistors 27, 28 or half-bridges 15, 16, 17 and their operation, the connected motor 2, and the measurement of the current signal 25 by the current sensor 20 can be considered to be functioning. (See first elapsed time 50).

[0095] In the second curve 51, it can be seen that the output current 21 or current signal 25 increases more slowly than the value stored in the control device 4 (see the first curve 50 or tolerance region 31). As already explained, this may indicate that the voltage 39 was applied incorrectly, or the voltage signal 23 was generated incorrectly, or the first position 22 of the permanent magnet or magnetic poles 10, 11 was measured incorrectly.

[0096] In the figure below, the first positions 22 of magnetic poles 10 and 11 are plotted on the vertical axis, and time 26 is plotted on the horizontal axis. Here, the third elapsed time 52 of the first position 22, which corresponds to the first elapsed time 50, and the fourth elapsed time 53 of the first position 22, which corresponds to the second elapsed time 51, are shown.

[0097] In the third step 52, a voltage signal 23 is applied to generate a current signal 25, and it can be seen from this third step 52 that there is no change in the first position 22. Therefore, when this method is performed, the phase angle of the obtained output current 21 corresponds to the first position 22 of the magnetic poles 10 and 11, i.e., the phase angle of the permanent magnet flux, and thus no torque is generated in the electric motor 2.

[0098] From the fourth step 53, it can be seen that the first position 22 changes when a voltage signal 23 is applied to generate a current signal 25. During step d), this change in the first position 22, i.e., the position of the rotor 9, can be detected and evaluated.

[0099] The change in the first position 22 occurs, for example, when the first position 22 of the permanent magnet or magnetic poles 10, 11 in step a) is mismeasured, or when the first phase position 24 of the voltage signal 23 generated in step b) is shifted from the first position 22.

[0100] In the evaluation of at least one of the second progress 51 and the fourth progress 53, it can be concluded that the drive unit 1 is in a faulty state.

[0101] Figure 8 shows the sequence of this method. Figure 9 shows the detailed sequence of this method. Figure 8 shows positions A to G in the sequence. Figure 9 shows positions C to G in more detail. Both Figure 8 and Figure 9 will be explained below.

[0102] At position A, it is determined whether the switch on the drive unit 1 to be checked is off. At position B, it is determined whether there is a start signal to start drive unit 1. If there is no start signal, the sequence is specified to return to position A. If there is a start signal, at position C, drive unit 1 is started.

[0103] Figure 9 shows that the first step is to check whether the control device 4 is ready to operate. If it is ready to operate, check whether the DC voltage source 14 is supplying sufficient DC link voltage. If it is not ready to operate, check again whether the control device 4 is ready to operate. If the DC link voltage is sufficient, at position D, check the electric motor 2 to determine whether the rotor 9 is stationary.

[0104] For this purpose, for example, the position of the transmission shifter lever and the vehicle speed, i.e., parameter 56, may be checked. If this check is successful, the first position 22 of the magnetic poles 10 and 11 can be determined by evaluating the position sensor 55. By determining the first position 22, it is possible to check whether the rotor 9 is stationary.

[0105] If the rotor 9 is not stationary, this method is performed with the rotor 9 rotating at position E below. For this reason, the electrical circuit 3 that intentionally supplies or generates torque does not generate a voltage signal between steps b) and d), but instead only the voltage signal 23 generated during this method (where torque should not be generated as much as possible) is applied. In response to this, a voltage signal 23 is generated, but its first phase position 24 is always the same as the first position 22, that is, it rotates at the first position 22.

[0106] When the rotor 9 is stationary, this method is performed at position E with the rotor 9 stationary. For this reason, a voltage signal 23 is generated at the same first phase position 24 as the first position 22.

[0107] At position E, the current signal 25 is measured and evaluated. First, it is checked whether the current signal 25 reaches the final value 40 stored in the control device 4, or whether the current signal 25 corresponds to the reference current signal 32 stored in the control device 4 with respect to its rise time and final value 40. It is also checked whether the elapsed values ​​50 and 51 of the current signal 25 or the output current 21 are within the allowable range 31. Furthermore, it is checked whether torque is generated in the electric motor 2 by applying the voltage signal 23.

[0108] If one of these checks is negative, i.e., not occurring, perform further diagnostics 54. For example, if it is necessary to repeat the additional diagnostics more than five times, determine that there is a fault in drive unit 1. Otherwise, check again whether rotor 9 is stationary.

[0109] At position F, it is checked whether an error is detected. If no error is detected, the drive unit 1 can perform its intended use, for example, to generate torque with the electric motor 2 according to position G. If a fault is detected, the drive unit 1 transitions to a safe state within the framework of position G, and its intended use is disabled. An error message 33 may be generated. [Explanation of symbols]

[0110] 1 Drive Unit 2 motors 3. Electrical Circuits 4. Control Devices 5 Stator 6. The first coil 7. The second coil 8. The third coil 9 rotors 10. The first magnetic pole 11. The second magnetic pole 12 First potential terminal 13. Second potential terminal 14 DC voltage source 15. First Half Bridge 16. Second Half Bridge 17. The Third Half Bridge 18. First connection 19. Second connection 20 Current Sensors 21 Output current 22 First position 23 Voltage signal 24 First phase position 25 Current signal 26 hours 27 Upper transistor 28 Lower transistor 29 contacts 30 Voltage Value 31 Tolerance range 32 Reference current signal 33 Error Messages 34 Drivetrain 35 Motor Actuator 36 Motor Monitoring Unit 37 Safety Logic 38 DC voltage capacitor 39 Voltage 40 Final value 41 Resistors 42 Inductance 43. The first axis 44. The second axis 45 The Third Axis 46 The Fourth Axis 47 Current 48 Signal Value 49 Trigger signal 50. First progress 51. Second course of events 52 Third course 53. The fourth course of events 54 Diagnosis 55 Position Encoder 56 parameters

Claims

1. A method for operating a drive unit (1) comprising an electric motor (2), comprising the steps of: The drive unit (1) the electric motor (2); an electric circuit (3) for operating the electric motor (2); a control device (4) for operating said electric circuit (3); Equipped with The electric motor (2) a stator (5) having at least three coils (6, 7, 8); a rotor (9) having at least two magnetic poles (10, 11); At least have The electric circuit (3) includes at least a first electric potential terminal (12) and a second electric potential terminal (13), The terminals (12) and (13) can be connected to different potentials of a DC voltage source (14); The electric circuit (3) has three half bridges (15, 16, 17) between the potential terminals (12, 13), Each of the coils (6, 7, 8) conductively connected to one of the half-bridges (15, 16, 17) via a corresponding first connection (18); conductively connected to the other of said coils (6, 7, 8) via a corresponding second connection (19); the electrical circuit (3) has at least three current sensors (20) for measuring output currents (21) conducted through the corresponding first wire connections (18); The method comprises: a) a first position (22) in rotation of the magnetic poles (10, 11) of the rotor (9) relative to the stator (5) is determined by the control device (4); b) generating a voltage signal (23) by said electrical circuit (3), The voltage signal (23) has only a first phase position (24) that is identical to the first position (22). Steps and c) measuring a current signal (25) of the output current (21) generated by said voltage signal (23) by a current sensor (20); d) evaluating the current signal (25) by the control device (4) with respect to the rise of the current signal (25) over a time period (26) and evaluating the state of the drive unit (1); The method includes at least the following.

2. 10. The method of claim 1, In step d), on the rising edge of said current signal (25) over a time period (26), or For the value of said current signal (25) reached after a time period (26), The control device (4) at least evaluates the current signal (25), method.

3. The method according to any one of claims 1 to 2, Each half bridge (15, 16, 17) has at least an upper transistor (27) and a lower transistor (28) electrically conductively connected to each other; The upper transistor (27) is electrically conductively connected to the first potential terminal (12); the lower transistor (28) is electrically conductively connected to the second potential terminal (13); Each half bridge (15, 16, 17) has a contact (29) between the upper transistor (27) and the lower transistor (28); via each of said contacts, said first connection (18) is connected to a corresponding one of said half-bridges (15, 16, 17); Step b) selects a pulse pattern for clocking all transistors (27, 28) to generate said voltage signal (23); method.

4. The method according to any one of claims 1 to 3, The voltage signal (23) has a constant voltage value (30). method.

5. The method according to any one of claims 1 to 4, the rotor (9) has a constant first position (22) at least during step a), During step d), the change in the position of the rotor (9) is detected and evaluated. method.

6. The method according to any one of claims 1 to 4, The rotor (9) rotates relative to the stator (5) at least during steps a), b) and c). method.

7. The method according to any one of claims 1 to 6, The method comprises: i. restarting the drive unit (1); ii. The rotor (9) is stationary relative to the stator (5); iii. The rotor (9) rotates without torque relative to the stator (5); is initiated if at least one of method.

8. The method according to any one of claims 1 to 7, If the current signal (25) evaluated in step d) is within an acceptable range (31) relative to a reference current signal (32) stored in the control device (4), The electric motor (2) is started to operate and generate torque; If the current signal (25) is outside the tolerance region (31), an error message (33) is generated by the control device (4); method.

9. A drive unit (1), an electric motor (2); an electric circuit (3) for operating the electric motor (2); a control device (4) for operating said electric circuit (3); At least prepare, Designed and configured to carry out the method according to any one of claims 1 to 8, Drive unit (1).

10. A drive train (34) for a motor vehicle comprising at least a drive unit (1) according to claim 9, the electric motor (2) is a traction drive that provides the drive torque of the drive train (34); Drivetrain (34).

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