Method for operating a circuit arrangement, circuit and motor vehicle

Abstract

The invention relates to a method for operating a circuit arrangement (2) comprising a circuit (3) and an electric machine (4), wherein, upon fulfillment of at least one triggering criterion, the electric machine (4) is switched to freewheeling by the circuit (3), subsequently, a duration is determined on the basis of at least one measured value which describes a change in the stator current in the electric machine (4), wherein the electric machine (4) is operated in freewheeling for the duration and is then switched to active short-circuiting by the circuit (3).

Description

Technical Field

[0001] This invention relates to a method for operating a circuit device including circuitry and a motor, wherein the motor switches to idle mode via the circuitry upon meeting at least one trigger criterion. Furthermore, this invention relates to a circuit and a motor vehicle. Background Technology

[0002] What may be needed in motors is the ability to immediately shut down a motor that is still in operation in the event of a fault in the motor or equipment including the motor. This could occur, for example, when the load decreases, or when equipment including the motor (e.g., a motor vehicle including a motor as a traction engine) is determined to be faulty, for example, due to an accident. Such a shutdown process requires transferring the motor to a safe state, in addition to other electrical components. Various measures can be implemented for this purpose, particularly those that shut off the motor's power supply voltage, prevent torque jumps in the motor, and / or prevent sudden braking torque.

[0003] To achieve a safe operating condition, the motor can be switched to active short-circuit or idling. Which of these methods is appropriate depends on the type of motor, i.e., whether it is an asynchronous or synchronous motor. Different methods for switching a motor to idling or active short-circuit are known from the prior art.

[0004] DE 10 2014 209 887 A1 describes a method for switching the operation of an inverter for an electric drive in a motor vehicle. Here, the motor can be operated by adjusting the inverter to run in an idle operating mode, a short-circuit operating mode, and a clock operating mode. Switching between operating modes is performed based on determined voltage and / or determined current values ​​for the current operating mode, wherein an adjustment process is performed based on the determined voltage and / or determined current values ​​to adjust the current and / or voltage in the motor for a target operating mode.

[0005] Here, during the transition from idling mode to short-circuit operation mode, the inverter's current regulator first operates for a short period using a preset zero current rating, during which the voltage and / or current values ​​for the current operating mode are determined. During this time, the voltage on the motor can gradually decrease to zero, and then the inverter's timing is terminated by switching the inverter to short-circuit operation mode. This compensates for the voltage or current difference between the current and target operating modes and reduces or prevents transient overcurrents or overvoltages.

[0006] DE 10 2013 226 560 A1 discloses a method for better switching a motor from idling to an active short circuit. Here, the switching from idling to an active electrical short circuit is delayed until the voltage at the motor terminals reaches a predetermined value. This allows the switching to be performed based on the rotor position determined by a specific voltage.

[0007] DE 10 2010 039 190 A1 describes a method for operating an inverter-controlled motor in a motor vehicle with an automatically steerable transmission. During generator operation, the motor inputs energy into an energy storage device. In fault conditions, parameters describing the charging state of the energy storage device are detected and compared to a predetermined lower threshold. If the charge falls below this threshold, the inverter switches the motor to an idle mode, and a higher gear ratio is set in the automatically steerable transmission compared to the current gear ratio. This results in a change in the motor's rotational speed, which affects the charging power input into the energy storage device. Summary of the Invention

[0008] The object of this invention is to describe an improved method for operating a circuit device with a motor, which is particularly capable of achieving an improved switching to a motor safety state.

[0009] To achieve this objective, according to the present invention, in the method of the above type, a duration is determined based on at least one measurement describing the change in stator current in the motor, wherein the motor runs idle during the duration and is subsequently switched to active short circuit by a circuit.

[0010] This advantageously enables switching a motor or circuit device to a safe state based on the type-related requirements of the motor, without having to store the motor type in the control device designed to execute the method. By considering the changes in stator current that can be achieved after switching the motor to idling, the motor type or the optimal response for achieving the safe state can be deduced. Furthermore, the parameterization of the motor or circuit control device in the circuit can be eliminated by determining the duration of idling based on the stator current change. Advantageously, the method executed when the triggering criteria are met can therefore be executed in principle identically for different types of motors, where only the determined duration is considered as a variable. This advantageously reduces the complexity of the method and simplifies implementation. Furthermore, it is advantageously possible to always switch the motor to active short-circuit, regardless of the type of motor connected, in which the motor is completely short-circuited.

[0011] In particular, if a specific situation arises requiring the motor to be switched to a safe state, or if information describing this situation appears in the control device designed to perform the method, then at least one trigger criterion must be met to first switch the motor to idling and then, after a duration determined according to the stator current change, switch to an active short circuit. Different types of trigger criterions or information are conceivable in principle, and may also depend, in particular, on the type of equipment equipped with circuitry. Therefore, not only in the case of a fault condition in the circuitry, but also in the case of a fault condition in the equipment including the circuitry, the switching of the motor to a safe state can be triggered by at least one trigger criterion.

[0012] In this context, the idling of a motor describes a state in which energy can be input from the motor to other components of the circuit or circuitry, particularly energy storage devices connected to the circuit. An active short circuit refers to a short circuit in the motor, especially in the multi-phase stator windings.

[0013] According to the invention, a longer duration can be determined for a higher stator current change (associated with an asynchronous motor design) compared to a smaller stator current change (associated with the motor being designed as a synchronous motor). The values ​​for the higher and lower stator current changes can be stored in a control device designed to perform the method, for example, according to limit values ​​for the stator current change and / or according to one or more association rules, which assign a duration to each determined stator current change. Thus, a higher stator current change can be a stator current change above the limit value, and a lower stator current change can be a stator current change below the limit value or another limit value. The lower stator current change can here, for example, be associated with a motor designed as a separately excited synchronous motor or a permanent magnet synchronous motor.

[0014] In a preferred embodiment of the invention, a duration between 100 ms and 1 s, particularly between 250 ms and 750 ms, may be specified for the stator current variation associated with an asynchronous motor, and / or a duration between 50 μs and 250 μs, particularly between 75 μs and 125 μs, may be specified for the stator current variation associated with a synchronous motor.

[0015] Upon meeting at least one trigger criterion, the motor first switches to idling via the circuit. In an asynchronous motor, the stator current and consequently the induced voltage decrease very rapidly, for example, within a range of approximately 100 μs. If this is the case, then idling must be maintained for a longer period, especially until the current in the rotor is completely or at least partially reduced. In this case, a high stator current change occurs due to the rapid decrease in stator current. The complete or at least partial reduction of the rotor current can occur within a time range of several hundred ms, thus advantageously allowing the motor to continue running in idling for this period. For this purpose, a duration between 100 ms and 1 s, particularly between 250 ms and 750 ms, can be determined during which the motor continues to run in idling. After this duration has elapsed, the motor can switch to active short-circuiting and remain there. Here, active short-circuiting represents a particularly continuous safe state for the motor.

[0016] With smaller stator current changes, the stator current decreases more slowly, which is particularly evident in permanent magnet synchronous motors or separately excited synchronous motors. These types of machines can, in principle, achieve a direct transition to active short circuit, thus keeping the energy feedback during idling as low as possible. A short hold before switching to active short circuit proves advantageous in synchronous motors, especially for permanent magnet motors, to reduce the load on the magnets during motor turn-off. However, a short time period is sufficient in this regard; therefore, a duration between 50 μs and 250 μs, particularly between 50 μs and 125 μs, is adequate for smaller stator current changes. Subsequently, a switch to active short circuit can also be made, thus placing the motor in a particularly continuous safe state.

[0017] According to the present invention, if the stator current drops to at least 50% of its value within 100 μs when the motor is switched to idling, then the stator current change is considered a high stator current change; and if the stator current drops to at most 80% of its value within 100 μs when the motor is switched to idling, then the stator current change is considered a low stator current change. If the stator current drops to 50% or less within 100 μs when the motor is initially switched to idling, then a high stator current change occurs accordingly. If the stator current remains at 80% or greater within 100 μs when the motor is switched to idling, then a low stator current change can occur accordingly.

[0018] For example, at the point when the motor is switched to idling, and taking into account at least one measurement detected during idling, the stator current change can be determined using at least one measurement of the stator current. Extrapolation of multiple measurements (each describing the stator current) determined after switching to idling also allows for the determination of the stator current change. Other methods can also be used to determine the stator current change.

[0019] In a preferred embodiment of the invention, multiple measurements from at least one stator current sensor, particularly at least one phase current sensor, can be used as measurements describing changes in stator current. This has the advantage that sensors can be used, which are always configured for motor operation. For example, such sensors can be used in motor regulation methods, so that the current measurements typically occur at the time when trigger criteria are met during motor operation, and therefore also at the time when the motor switches to idling. Furthermore, these measurements can also be determined after switching to idling, thus making it easy to determine changes in stator current.

[0020] According to the invention, the inverter, especially a multiphase pulse inverter, can be used as a circuit device. This advantageously enables the operation of the motor during engine operation via the circuit device. However, it is also possible in principle to implement this method using another type of circuit capable of switching the motor to idling and active short circuit.

[0021] In a three-phase pulse inverter, for example, connected to a three-phase motor, the inverter can be switched to idle mode by disconnecting all its switching elements, allowing power to be fed back via freewheeling diodes connected in parallel with the switching elements. In an active short circuit, three corresponding upper or three lower switching elements in the three half-bridges can be switched on, while the other switching elements are correspondingly disabled, thus achieving a short circuit to the motor or its stator windings.

[0022] According to the invention, the occurrence of a fault condition in the circuitry and / or in a device including the circuitry can be specified as a trigger criterion to be met. This device is particularly a motor vehicle in which an electric motor serves as a traction motor. The traction motor can be in both engine operation and generator operation during normal operation; in engine operation, the motor vehicle is driven by the engine; in generator operation, it charges, for example, the motor vehicle's electrically connected traction energy storage device.

[0023] According to the present invention, a reduction in the load on the motor and / or a collision detected by equipment designed for a motor vehicle can be used as a fault condition. For example, the satisfaction of a triggering criterion can be verified by a control device designed to perform the method, wherein one or more pieces of information transmitted to the control device can be considered as a basis for this. For example, when accident information describing a motor vehicle accident is transmitted to the control device, the triggering criterion may be satisfied. Additionally, or in addition to the accident information, other information describing other fault conditions can also be considered, which similarly leads to the satisfaction of at least one triggering criterion and thus causes the motor to be switched to a safe state.

[0024] According to the circuit specifications of the present invention, the circuit includes a control device, wherein the circuit is connected to or can be connected to a motor, and the control device is designed to perform the method according to the present invention.

[0025] According to the provisions of the present invention, the motor vehicle includes a circuit device having a motor and a circuit according to the present invention, wherein the circuit is connected to the motor.

[0026] All the advantages and design schemes described above with respect to the method according to the invention are applicable accordingly to the circuits according to the invention and the electric motor vehicles according to the invention, and vice versa. Attached Figure Description

[0027] Further advantages and details of the invention will become apparent from the embodiments described below and from the accompanying drawings. These drawings are schematic and illustrate:

[0028] Figure 1 An embodiment of an electric motor vehicle according to the present invention is shown.

[0029] Figure 2 A circuit arrangement having an embodiment of the circuit according to the invention is shown, and

[0030] Figure 3 A block diagram illustrating an embodiment of the method according to the present invention is shown. Detailed Implementation

[0031] exist Figure 1 An embodiment of a motor vehicle 1 is shown. The motor vehicle 1 includes an electrical device 2, which includes a circuit 3 and a motor 4. In addition, the electrical device 2 includes an energy storage device 5, which is connected to the motor 4 via the circuit 3.

[0032] Motor 4 forms the traction engine of vehicle 1 and operates via energy storage 5, which is designed as a traction battery. For this purpose, circuit 3 is connected between energy storage 5 and motor 4; this circuit is designed as an inverter, specifically a three-phase pulse inverter. Therefore, the direct current from energy storage 5 can be converted into three-phase alternating current via circuit 3 for the operation of motor 4. During generator operation of motor 4, i.e., during the recovery operation of vehicle 1, the alternating current generated by motor 4 can be correspondingly converted into direct current to charge energy storage 5.

[0033] The circuit device 3 also includes a control device 6, which is designed to execute the methods used to operate the circuit device 2 so as to switch the motor 4 to a safe state in the event of a malfunction. Here, the switching of the motor 4 is performed by other components of the circuit 3.

[0034] Figure 2 An embodiment of circuit 3 is shown. Circuit 3 is designed as a three-phase pulse inverter and includes six switching elements S1–S6. Freewheeling diodes D1–D6 are connected in parallel with the switching elements S1–S6 respectively.

[0035] Switching elements S1–S6 form three half-bridges 7, 8, and 9, wherein the first half-bridge 7 is formed by switching elements S1 and S4, the second half-bridge 8 is formed by switching elements S2 and S5, and the third half-bridge 9 is formed by switching elements S3 and S6. The control device 6 is connected to control connectors of the switching elements S1–S6, for example designed as transistors, wherein the corresponding connections are not shown for clarity.

[0036] Circuit 3 may also include an intermediate circuit capacitor 10 and other circuit elements. The bridging points of half-bridges 7, 8, and 9 are connected to the stator windings of motor 4, which is designed as a three-phase motor. Connectors in circuit 3, indicated by HV+ and HV-, are connected to the energy storage device 5. Stator current sensors 10 are assigned to phases U, V, and W as measuring devices, through which measured values ​​describing the stator current or stator current changes in motor 4 can be determined. Measuring device 11 is connected to control device 6 and transmits the determined measured values ​​to control device 6. Control device 6 can be designed to operate as an engine and / or a generator according to the driving requirements of motor vehicle 1 during normal motor operation.

[0037] The control device 6 is also designed to transfer the motor 4 to a safe state in the event of a fault. To this end, the control device 6 can evaluate one or more trigger criteria, wherein the occurrence of a fault condition in the circuit device 2 and / or the vehicle 1 is described accordingly by satisfying one of the trigger criteria. In particular, the control device 6 can continuously verify whether the trigger criteria are met. For this purpose, the control device 6 can evaluate one or more additional pieces of information, such as information transmitted to the control device 6 via a communication connection (not shown) of the vehicle 1, for example, a data bus, through which multiple control units of the vehicle 1 communicate with each other.

[0038] Figure 3 A method for operating circuit device 2 is described, which enables the transfer of motor 4 to a safe state. Advantageously, this can be performed independently of the machine type of motor 4.

[0039] In step S1, at least one trigger criterion is continuously checked to see if it is met. In the next step S2, when the trigger criterion is met, the motor 4 switches to idle mode via circuit 3. For this purpose, the six switching elements S1–S6 are disconnected respectively, so that electrical energy can be fed back to the energy storage 5 through the motor 4. For this purpose, the current generated by the motor 4 can flow through the freewheeling diodes D1–D6 of circuit 3.

[0040] During or after switching motor 4 to idling, at least one stator current change in motor 4 is determined in step S3. For this purpose, in particular, the measured value of the phase current of motor 4 described by sensor device 11 can be determined. Additionally or alternatively, measured values ​​of the stator current, such as those stored in control device 6, can also be considered, and thus, in particular, the stator current at the time point when triggering criteria are met and / or at the time motor 4 switches to idling, to determine the extent of the stator current change in motor 4 after switching to idling.

[0041] The magnitude of the stator current change can, in principle, indicate the machine type of motor 4 without needing to store that machine type in the control device 6. Here, a higher stator current change might, for example, be related to motor 4 being designed as an asynchronous motor, while a lower stator current change might be related to motor designing as a synchronous motor, such as a separately excited or permanent magnet synchronous motor. To determine whether a particular stator current change is higher or lower, for example, limit values ​​stored in the control device 6 can be considered. The rate of change of stator current can also be compared, either before switching motor 4 to idling or directly during switching.

[0042] If the stator current drops to at least 50% of its value within 100 μs when the motor 4 switches to idling, then the stator current change can be particularly understood as a relatively high stator current change. If the stator current drops to at most 80% of its value within 100 μs when the motor 4 switches to idling, then the stator current change can be correspondingly understood as a relatively low stator current change. Additionally or alternatively, the stator current change can also be determined by the rate of change of the stator current, especially during the idling period of the motor 4, wherein the absolute stator current change can be determined, for example, by extrapolation using the control device 6.

[0043] After determining the stator current change, in step S4, the duration is determined based on the determined stator current change. In the case of a higher stator current change associated with an asynchronous motor, a duration between 100 ms and 1 s, particularly between 250 ms and 750 ms, can be determined. In the case of a lower stator current change associated with, for example, a synchronous motor, a duration between 50 μs and 250 μs, particularly between 75 μs and 125 μs, can be determined.

[0044] In step S5, the process waits until the determined duration ends, during which time motor 4 remains idle. Then, in step S6, the motor is switched to active short-circuit mode. The time period of step S5 depends on the determined duration, and therefore on the stator current change, and thus indirectly on the type or structure of motor 4.

[0045] To switch motor 4 to an active short circuit, switching elements S1–S3 can be opened and switching elements S4–S6 closed, for example. Alternatively, switching elements S1–S3 can be closed and switching elements S4–S6 opened. Regardless of the machine type of the motor, this state represents the desired safe state of motor 4.

[0046] The varying durations of idling in step S5 can satisfy different requirements of motor 4 without needing to store machine type and / or other parameters in control device 6. Due to the longer idling time in motor 4, for example, designed as an asynchronous motor, a significant reduction in stator current can be achieved. Since this rotor current does not occur in permanent magnet synchronous motors, or the rotor current in separately excited motors can be switched off independently, there is no need for a longer idling time in this type of motor, allowing for a significantly faster switch to active short circuit. Therefore, in synchronous or separately excited motors, it is advantageous to minimize the feedback of electrical energy entering energy storage 5.

[0047] This method enables responses to different types of fault conditions in the circuit device 2 and / or the vehicle 1, and causes the motor 4 to transition to a safe state, particularly an active short circuit in the motor 4. Here, a reduction in load can be considered, for example, a fault condition of the motor 4. Furthermore, a detected collision between the vehicle 1 and another object can also represent a possible fault condition, making it necessary to meet triggering criteria and thus transition the motor 4 to a safe state.

[0048] In addition to transferring motor 4 to a safe state, further safety measures can be taken, such as electrically isolating energy storage device 5 from circuit 3 and / or other components of vehicle 1 via an additional switching device (not shown). It is possible that switching motor 4 to idling and / or active short circuit cannot be achieved by circuit device 3 designed as an inverter, but rather by providing an electrical switching device in circuit device 2 for this purpose.

Claims

1. A method for operating a circuit device (2) comprising a circuit (3) and a motor (4), wherein, When at least one trigger criterion is met, the motor (4) is switched to idle by circuit (3), and then a duration is determined based on at least one measurement describing the stator current change in the motor (4), during which the motor (4) runs in idle and is then switched to active short circuit by circuit (3), wherein the inverter is used as circuit (3) to switch to idle by disconnecting all switching elements of the inverter, thereby feeding back electrical energy through freewheeling diodes connected in parallel with the switching elements, wherein a longer duration is determined in the case of a higher stator current change associated with the design of the motor (4) as an asynchronous motor compared to a lower stator current change associated with the design of the motor (4) as a synchronous motor.

2. The method according to claim 1, characterized in that, The duration is determined to be between 100 ms and 1 s in the case of stator current variation associated with an asynchronous motor, and / or between 50 µs and 250 µs in the case of stator current variation associated with a synchronous motor.

3. The method according to claim 2, characterized in that, The duration was determined to be between 250 ms and 750 ms in the case of stator current variation associated with the asynchronous motor.

4. The method according to claim 2, characterized in that, In the case of stator current variation associated with synchronous motors, the duration is determined to be between 75µs and 125µs.

5. The method according to any one of claims 1 to 4, characterized in that, If the stator current drops to at least 50% of its value within 100µs when the motor (4) is switched to idle, then the stator current change is considered a high stator current change. If the stator current drops to at most 80% of its value within 100µs when the motor (4) is switched to idle, then the stator current change is considered a low stator current change.

6. The method according to any one of claims 1 to 4, characterized in that, Multiple measurements from at least one stator current sensor (10) are used as measurements to describe changes in stator current.

7. The method according to claim 6, characterized in that, Multiple measurements from at least one phase current sensor are used as measurements to describe changes in stator current.

8. The method according to any one of claims 1 to 4, characterized in that, The inverter is a multiphase pulse inverter.

9. The method according to any one of claims 1 to 4, characterized in that, The occurrence of a fault condition in the circuit device (2) and / or in the equipment including the circuit device (2) is used as the trigger criterion for satisfaction.

10. The method according to claim 9, characterized in that, The load on the motor (4) is reduced and / or the detected collision of the equipment designed for the motor vehicle (1) is used as a fault condition.

11. A circuit comprising a control device (6), wherein, The circuit (3) is connected to the motor (4), and the control device (6) is designed to perform the method according to any one of claims 1 to 10.

12. A motor vehicle comprising a circuit device (2) having an electric motor (4) and a circuit (3) according to claim 11, the circuit being connected to the electric motor (4).

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