CN109586552B

CN109586552B - Power unit, STO method, user interface control device and STO signal processing method

Info

Publication number: CN109586552B
Application number: CN201710912182.3A
Authority: CN
Inventors: 王成月; Y-L·阿莱尔特; P·鲁奥尔特; 谢鉴
Original assignee: Schneider Electric Industries SAS
Current assignee: Schneider Electric Industries SAS
Priority date: 2017-09-29
Filing date: 2017-09-29
Publication date: 2021-05-28
Anticipated expiration: 2037-09-29
Also published as: CN109586552A

Abstract

The present disclosure relates to a power unit, a safe torque off (STO) method, a user interface control device, and a method of processing an STO signal. According to an embodiment of the present disclosure, a power unit includes a semiconductor device and a communication monitoring module. The communication monitoring module is configured to monitor communication data on a communication line in an electrical system and, in response to detecting that the communication data contains information indicative of a safe torque off, to provide information to the semiconductor device for safe torque off. Turn-off signal for torque off. According to the embodiment of the present invention, the STO function is implemented based on communication data monitoring, which has good compatibility with the original system, and at the same time, its implementation method is relatively simple, the implementation cost is low, and effective safety isolation can be achieved.

Description

Power unit, STO method, user interface control device and STO signal processing method

Technical Field

Embodiments of the present disclosure relate to a drive system for driving an electrical device, such as an electric motor, in particular to a power unit, a method for Safe Torque Off (STO), a user interface control device and a method of processing an STO control signal.

Background

To prevent a personal injury accident due to an accidental start of electrical equipment, an STO function has been proposed for products such as a frequency converter, a servo motor driver, and the like. This function can prevent the drive from generating torque in it when, for example, the motor is stopped, thereby enabling the motor to be part of the safety system. The STO function is now becoming more and more necessary and even tends to become the driving standard function.

The STO function is typically present in existing low voltage drive systems. In low voltage drive systems, two or three dedicated lines or printed circuit board traces are typically provided which are used to transmit STO control signals from a user via customer terminals to the power cell in order to control insulated gate transistors IGBT in the power cell, thereby allowing the drive output to be turned off in an emergency, causing, for example, the motor apparatus to shut down. The power unit is a high-voltage frequency converter component which uses power electronic devices to carry out rectification, filtering and inversion. Which typically includes semiconductor devices arranged in a full bridge configuration, such as insulated gate transistors (IGBTs), an STO control signal is provided to the gate of the IGBT to control the IGBT to turn off.

For safety reasons, however, it is necessary to isolate the STO control signals, since the STO signal is triggered by the user on the one hand, and on the other hand will be transmitted to the high voltage area, so that there is a possibility that the user will be exposed to a dangerous high voltage. In low voltage drive systems, such isolation may be achieved by optical coupling.

There is also a need for an STO function in medium voltage drive systems. However, medium voltage drive systems include a significantly increased number of power cells and are more bulky and complex than low voltage drive systems. If the STO function is implemented in the same manner as in the case of the medium voltage drive system, a large number of signal cables may be required to transmit the required STO signal, which makes the system extremely large and complex, and the resulting cost increase is also significant. In addition, it is also difficult to achieve secure isolation optically.

Disclosure of Invention

In view of the above, the present disclosure provides a new solution for safe torque shutdown to overcome or alleviate at least some of the disadvantages of the prior art as described above.

According to one aspect of the present disclosure, a power cell is provided. The power unit may include a semiconductor device and a communication monitoring module. The communication monitoring module is configured to monitor communication data on a communication line in an electrical system and, in response to detecting that information indicative of a safe torque shutdown is included in the communication data, provide a shutdown signal for the safe torque shutdown to the semiconductor device.

According to a second aspect of the present disclosure, a method for safe torque shutdown is provided. The method can comprise the following steps: the method includes monitoring communication data on a communication line in the electrical system, and providing a shutdown signal for safe torque shutdown to a semiconductor device within the power cell in response to detecting information indicative of safe torque shutdown contained in the communication data.

According to a third aspect of the present disclosure, there is provided a user interface control device, such as a user interface control pad. The user interface control device may include: a processing module configured to receive a control signal from a user of a safe torque shutdown, and the processing module is configured to include information indicative of the safe torque shutdown in communication data for transmission over a communication line in response to the control signal.

According to a fourth aspect of the present disclosure, a method of processing a safe torque off control signal is provided. The method can comprise the following steps: receiving a control signal from a user for safe torque shutdown; and in response to the control signal, including information indicative of safe torque shutdown in the communication data for transmission over the communication line.

According to the embodiment of the disclosure, an STO technical scheme based on communication data monitoring is provided, and an extra cable or line is not needed to support the STO function, so that a system with the STO function can have better compatibility with an original system, and meanwhile, the realization mode is simpler and the realization cost is lower. Moreover, since the STO control information is carried through the communication line instead of using a dedicated line connecting the subscriber and the high voltage part, the information carrying manner itself can isolate the subscriber from the high voltage unsafe part, protecting the subscriber safety.

Drawings

The above and other features of the present disclosure will become more apparent by describing in detail embodiments thereof that are illustrated in the accompanying drawings in which like reference numerals refer to the same or similar parts throughout the drawings. In the drawings:

FIG. 1 schematically illustrates a block diagram of a user interface control device according to one embodiment of the present disclosure;

fig. 2 schematically shows a block diagram of a power cell according to an embodiment of the present disclosure;

FIG. 3 schematically illustrates a block diagram of an example communication monitoring module, according to an embodiment of the present disclosure;

FIG. 4 schematically shows a timing diagram illustrating the generation of the STO control signal according to one embodiment of the present disclosure;

FIG. 5 schematically illustrates a block diagram of another example communication monitoring module, according to an embodiment of the present disclosure;

FIG. 6 schematically illustrates a block diagram of yet another example communication monitoring module, according to an embodiment of this disclosure;

FIG. 7 schematically illustrates a flow chart of a method for processing an STO control signal according to one embodiment of the present disclosure; and

FIG. 8 schematically shows a flow chart of a method for STO according to one embodiment of the present disclosure.

Detailed Description

Hereinafter, various exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the drawings and description relate to preferred embodiments by way of example only. It should be noted that from the following description, alternative embodiments of the structures and methods disclosed herein are readily contemplated and may be employed without departing from the principles of the disclosure as claimed in the present disclosure.

It should be understood that these exemplary embodiments are given solely for the purpose of enabling those skilled in the art to better understand and to practice the present disclosure, and are not intended to limit the scope of the present disclosure in any way. Also in the drawings, optional steps, modules, etc. are shown in dashed boxes for illustrative purposes.

The terms "including," comprising, "and the like, as used herein, are to be construed as open-ended terms, i.e.," including/including but not limited to. The term "based on" is "based, at least in part, on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment". Relevant definitions for other terms will be given in the following description.

As mentioned above, for the medium voltage driving system, the STO function is implemented in the same way as the low voltage driving system, and a large number of signal cables may be required to transmit the required STO signal, which makes the system become extremely large and complex, the cost increase is also significant, and the safety isolation is difficult to implement in a simple way. To address this problem, the present disclosure provides a completely different STO implementation than the low voltage drive system. In the solution provided by this disclosure, it is proposed to carry STO control information over the communication line. According to this scheme, information indicative of STO will be included in the communication data for transmission on the communication line, and an enable signal for STO will be provided to the semiconductor devices (e.g., IGBTs) in the power cells by monitoring the information indicative of STO in the communication data.

Hereinafter, the STO scheme provided according to the present disclosure will be described in detail with reference to fig. 1 to 8. It should be noted, however, that the arrangements shown in the drawings and described below are given for illustrative purposes only and the present disclosure is not limited to the embodiments shown.

Referring first to fig. 1, fig. 1 schematically shows a block diagram of a user interface control device 100 according to an embodiment of the present disclosure. The user interface control device 100 is, for example, a user interface control panel for receiving input from a user and providing system output to the user. The control board may receive power-on and power-off signals from a user (e.g., via a power button by the user), and may also receive an STO control signal from the user. For example, the user may be provided with two STO buttons, either of which can trigger the STO control signal. Here, safety redundancy can be achieved by providing two STO buttons. However, it will be appreciated that it is also possible to provide only one STO button. It should also be noted that it is also possible to implement the STO button as a virtual button on the touch screen, or in the case of two STO buttons, one of which is a virtual button and the other a mechanical button.

The STO control signal from the user can be received by the signal processing module 101. However, unlike the conventional transmission of the STO control signal through a dedicated line, the signal processing module 101 is configured to add information indicating the STO to communication data for transmission on a communication line in response to receiving the STO control signal from a subscriber. In other words, the signal processing module 101 is responsible for converting the control signal indicating the enabling of the STO from the user into the information indicating that the STO needs to be enabled, which is to be transmitted through the communication line as the communication data, contained in the communication data. For example, the information indicating the STO may have a pattern different from that of the general communication data so that it can be recognized.

At the power unit, on the other hand, the communication data on the communication line is monitored to detect information contained therein indicating that STO needs to be enabled. When this information is detected, the power unit will know that the user desires to enable the STO function. Next, a power unit provided in the present disclosure will be described with reference to fig. 2 to 6.

Referring to fig. 2, a block diagram of a power cell 200 according to one embodiment of the present disclosure is shown. As shown in fig. 2, the power unit 200 is a high voltage inverter component that performs rectification, filtering, and inversion using power electronics, and includes a communication monitoring module 201 and a semiconductor device 202. The semiconductor devices 202 are, for example, insulated gate transistors (IGBTs), which may be arranged in a full-bridge configuration. The circuit structure of semiconductor devices arranged in a full-bridge manner in a power cell is known and will not be described herein.

In addition, it should be noted that the following description will be given by taking IGBTs as examples of semiconductor devices, however, it is understood that they may also adopt other types of semiconductor devices, or other topologies. For an IGBT, the voltage applied at the gate of the IGBT may control the IGBT to turn on and off.

The communication monitoring module 201 has an input terminal to which communication data on a communication line is transmitted, which may be configured to monitor the input communication data, and to provide a shut down signal for safe torque shut down to the semiconductor device at an output terminal in response to detecting that information indicating safe torque shut down is contained in the communication data.

The communication monitoring module 201 may be implemented in various ways, such as digitally, or using analog. Hereinafter, for the purpose of explanation, embodiments of the present disclosure are described by way of specific examples.

Referring to fig. 3, an example communication monitoring module 201 'is shown, which communication monitoring module 201' implements communication system monitoring by counting high and low levels of communication data, according to one embodiment of the present disclosure. As shown in fig. 3, the communication monitoring module 201' may include two counters, i.e., a high level counter 2011 and a low level counter 2012. The high level counter 2011 is configured to count a high level in the communication data. The low level counter 2012 is configured to count low levels in the communication data. Clock sources 2013a and 2013b are two clock sources, which respectively provide clock signals for high level counter 2011 and low level counter 2012 so that the two counters count. The high level counter 2011 and the low level counter 2012 can be implemented by using the same counter, but in this case, an inverter is needed to be used before the communication data input end of the low level counter 2012, so as to invert the input data, thereby implementing the counting of the low level.

The high level counter 2011 provides a high level signal at its output terminal as a counter output signal if the count of high levels reaches a corresponding predetermined threshold; the low level counter 2012 also provides a high level signal at its output terminal as a count indication signal if the count of said low levels reaches a corresponding predetermined threshold. The outputs of the low level counter 2012 and the high level counter 2011 are supplied to the signal generation section 2014. The signal generating part 2014 is configured to provide a shut down signal for safe torque shut down based on the count indication signal of the high level at the output of any one of the high level counter and the low level counter. One example of the signal generating component 2014 is an or gate. The or-gate performs, for example, an or operation on the two counter output signals, and provides a high level signal at its output as a shutdown signal for STO, i.e., an STO enable signal, as long as either one of them is high. The STO signal may be provided to the semiconductor device 202, in particular to the gate of the IGBT, in order to turn the semiconductor device off, thereby performing the STO function.

In addition, the communication monitoring module 201' may also send a signal to a main controller (not shown) of the power unit indicating that the safe torque off function is in an active state. The generated STO control signal may be provided simultaneously to the main controller of the power unit, for example, to inform the main control STO function that is currently enabled and in an active state. Thus, the main controller can stop the processing such as decoding of the communication data.

Furthermore, for the purpose of security isolation, it is also conceivable to provide isolation between the secure part and the non-secure part. For example, it may be considered to add an isolation component 2015, such as a diode or a buffer, on the line from the communication monitoring module to the master controller for notifying that the STO function is in a valid state, so that the signal can only be transmitted in the direction of the signal generation component 2014 to the master controller. Thus, even if the main controller is abnormal, the safety part is not affected.

In addition, it is also conceivable to add an isolation component to the line from the communication data itself to the main controller so as to allow only the transmission of the communication data to the main controller, so that the signal from the main controller does not affect the monitoring result of the communication monitoring module. For example, it is contemplated to add an isolation element 2016, which may also be, for example, a diode, or a buffer, on the line of communication data to the host controller, so that communication data can only be transmitted in the direction to the host controller, without the signal from the host controller having any effect on the safety section.

In addition, a signal indicating that the safety torque off function is in an active state may be further transmitted to the electrical system in which the power unit is located, so as to inform the electrical system that the safety torque off is currently enabled. The transmission of this signal may be transmitted in a similar manner to the signal to the master controller, i.e. from the communication monitoring module 201'; alternatively, after the master controller receives the signal, the master controller may send a signal to the electrical system indicating that the safety torque off function is in an active state. In response to the signal, the electrical system may display or update the STO enabled status, for example, on a display screen or human machine interface, and may stop operations such as processing and sending of communication data.

It is noted that the level required to turn off the semiconductor device may be different for different types of semiconductor devices. Thus, depending on the nature of the semiconductor device, an inverter may be added before the STO control signal enters the gate to properly place the semiconductor device in the desired state. Furthermore, it is also contemplated to employ protection redundancy, i.e., it is contemplated that an additional STO signal may be generated by adding another set of low level counters 2012 and high level counters 2011 to control the semiconductor device. For example, two sets of counters may be used to control the upper and lower arms of the full bridge configuration, respectively. Thus, even if one group of circuits is abnormal, the other group of circuits can still work normally to realize the STO function.

Fig. 4 schematically shows a timing diagram for explaining the operation of the communication monitoring circuit according to one embodiment of the present disclosure. As shown in fig. 4, a clock signal 401 and data 402 are shown, respectively. Clock signal 401 is, for example, a clock signal provided by clock sources 2013a and 2013b to a high level counter and a low level counter. The data 402 is, for example, raw data to be transmitted over a communication line. The data 402 may be counted using a high level counter while the communication data 402 is counted using a low level counter. For example, the communication data 402 may be high-level counted and low-level counted at each rising edge of the clock signal. If the count of any of them reaches a corresponding predetermined threshold, e.g., 8, then an STO enable signal is generated.

In the communication monitoring module shown in fig. 3, both a high level counter and a low level counter are used, so that the power unit can support the application of a plurality of high levels as STO control information as well as the application of a plurality of high levels as STO control information. The STO function may be automatically triggered even when a communication failure at a high level occurs or a communication failure at a low level occurs.

It should be noted that although a specific structure of the communication monitoring circuit is described above, it should be noted that this is merely an example communication monitoring circuit given for illustrative purposes, and other embodiments are possible. Next, two other example communication monitoring circuits will be described with reference to fig. 5 and 6.

Fig. 5 schematically illustrates a block diagram of another example communication monitoring module, according to an embodiment of the present disclosure. As shown in fig. 5, the exemplary communication monitoring module 201 ″ differs from the communication monitoring module 201' shown in fig. 3 only in that it includes a high level counter 2011, and the high level counter 2011 outputs a high level when the count of the high level exceeds a predetermined threshold, and the high level is provided as an STO signal to the semiconductor device to perform STO. Other components in fig. 5, such as clock source 2013a,

isolation components

2015, and 2016, perform similar operations as those shown in fig. 3 to achieve similar functions, and are not described again for simplicity.

Fig. 6 schematically illustrates a block diagram of yet another example communication monitoring module, according to an embodiment of this disclosure. As shown in fig. 6, the example communications monitoring module 201 '"is similar to the communications monitoring module 201" shown in fig. 5, and includes only one counter, but differs from the low counter 2012 included in the communications monitoring module 201' "rather than the high counter 2011. When the count of the low level counter 2012 exceeds a predetermined threshold, a high level is output and supplied to the semiconductor device as an STO signal to perform STO. Other components such as clock source 2013b and

isolation components

2015 and 2016 perform similar operations and achieve similar functions as the components shown in fig. 3 and 5, and are not described again here for simplicity.

According to the embodiment of the disclosure, an STO technical scheme based on communication data monitoring is provided, and an extra cable or line is not needed to support the STO function, so that a system with the STO function can have better compatibility with an original system, and meanwhile, the realization mode is simpler and the realization cost is lower. Moreover, since the STO control information is carried through the communication line instead of using a dedicated line connecting the user and the high voltage part, the information carrying manner itself can isolate the user from the high voltage unsafe part, protecting the user safety.

It should be noted that although in the above description the solution proposed in the present invention is directed to a medium voltage drive system, it can in fact be used in other drive systems, such as low voltage systems.

Next, an embodiment of the method provided in the present disclosure will be described with reference to fig. 7 and 8.

FIG. 7 schematically shows a flow diagram of a method 700 for processing an STO control signal according to one embodiment of the present disclosure. As shown in fig. 7, at step 701, the user interface control board receives a control signal from the user for safe torque off. For example, a user issues an STO control signal via an STO button provided by the system, which STO control signal may be received by the user interface control board. In step 702, the user interface control board, upon receiving the STO control signal, includes information indicating that the safe torque is off in the communication data for transmission over the communication line in response to the control signal. This eliminates the need for dedicated lines for transmitting the STO control signal. For example, the information indicating the STO may have a pattern different from that of the general communication data so that it can be recognized.

FIG. 8 schematically shows a flow chart of a method 800 for STO according to one embodiment of the present disclosure. As shown in fig. 8, at step 801, a communication monitoring module monitors communication data on a communication line in an electrical system. In step 802, the communication monitoring module provides a shutdown signal for safe torque shutdown to a semiconductor device within the power cell in response to detecting that the communication data includes information indicative of safe torque shutdown. The communication monitoring and shutdown signal generation may be implemented in various ways.

In one embodiment according to the present disclosure, a high level in the communication data is counted, wherein if the count of the high level reaches a predetermined threshold, this means that it is detected that the information indicating safe torque shut-off is included in the communication data, thus providing a shut-off signal for safe torque shut-off. This counting may be achieved by a high level counter, which may provide a high level at the output of the counter, which may serve as a control signal for STO, when the count of said high level reaches a predetermined threshold.

In another embodiment according to the present disclosure, a low level in the communication data is counted, wherein if the count of the low level reaches a predetermined threshold, this means that the information indicating that the safe torque is turned off is detected to be included in the communication data. At this point, a shutdown signal for safe torque shutdown may be provided. This counting may be achieved by a low level counter, which when reaching a predetermined threshold value may provide a high level at the output of the counter, which may be used as a control signal for STO.

In another embodiment according to the present disclosure, the high level and the low level in the communication data may be counted separately, wherein if the count of either of the high voltage and the low voltage reaches a respective predetermined threshold, this means that it is detected that the information indicating safe torque shut-off is included in the communication data. At this point, a shutdown signal for safe torque shutdown may be provided. This high level counting may be achieved by a high level counter, which may provide a high level at the output of the counter when the high level counting reaches a predetermined threshold. This low level counting may be achieved by a low level counter which provides a high level at the output of the counter when the count of said low level reaches a predetermined threshold. Then, a shut-off signal for safe torque shut-off may be provided based on the count indication signal of high level at the output of either of the high level counter and the low level counter. For example, an or operation may be performed on the outputs of the high level counter and the low level counter, i.e., either one of the outputs is high, then a high level is output, or the result of the or operation will be the control signal for STO.

In one embodiment according to the present disclosure, a signal indicating that the safety torque off function is in an active state may be further sent to the main controller of the power unit at step 803. The generated STO control signal may be provided simultaneously to the main controller of the power unit, for example, to inform the main control STO function that is currently enabled and in an active state. Thus, the main controller can stop the processing such as decoding of the communication data.

In one embodiment according to the present disclosure, sending information to the electrical system indicating that the safe torque off function is in an active state to inform the electrical system that the safe torque off is currently enabled may also be included at step 804. The electrical system may display or update the STO enabled status, for example, on a display screen or human machine interface, and may stop encoding and transmitting of communication data, for example.

In an embodiment according to the present disclosure, the method may further include, at step 805: isolating a safe portion within the power unit for achieving safe torque shutdown from other unsafe portions in the power unit. The isolation is achieved by any one of a buffer and a diode. For example, it can be considered that a separation part 2015 is added to a line to the main controller for notifying that the STO function is in a valid state so that a signal can be transmitted only in the direction from the signal generation part 2014 to the main controller, and thus, there is no influence on the safety part even when an abnormality occurs in the main controller. In addition, it is also conceivable to add an isolation component to the line from the communication data itself to the main controller so as to allow only the transmission of the communication data to the main controller, so that the signal from the main controller does not affect the monitoring result of the communication monitoring module.

It should be noted that the embodiments of the present disclosure can be realized in hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic; the software portions may be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or specially designed hardware.

It will be appreciated by those skilled in the art that the above described method and apparatus, some of which may be implemented using code embodied in processor control code, may be provided, for example, on a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as read only memory (firmware) or a data carrier such as an optical or electronic signal carrier.

The apparatus and its components of the present embodiment may be implemented by hardware circuits such as a very large scale integrated circuit or a gate array, a semiconductor such as a logic chip or a transistor, or a programmable hardware device such as a field programmable gate array or a programmable logic device, or may be implemented by software executed by various types of processors, or may be implemented by a combination of the above hardware circuits and software, for example, by firmware.

While the present disclosure has been described with reference to presently contemplated embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments. On the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A power cell, comprising:

semiconductor device, and

a communication monitoring module configured to monitor communication data on a communication line in an electrical system, and in response to detecting that information indicating a safe torque-off from a user is included in the communication data, provide a shut-off signal for the safe torque-off to the semiconductor device and simultaneously transmit a signal indicating that a safe torque-off function is in an active state to a main controller of the power unit, wherein the information indicating that the safe torque-off includes at least one of a high level signal and a low level signal whose number reaches a respective predetermined threshold, and the signal indicating that the safe torque-off function is in the active state indicates that the main controller of the power unit stops operating on the communication data.

2. The power unit of claim 1, wherein the communication monitoring module is further configured to:

transmitting information indicating that a safe torque off function is in an active state to the electrical system to instruct the electrical system to stop operating on the communication data.

3. The power unit of claim 1 or 2, wherein the communication monitoring module comprises a high level counter configured to count high levels in the communication data,

wherein the high level counter provides a shutdown signal at its output for safe torque shutdown if the count of high levels reaches a predetermined threshold.

4. The power unit of claim 1 or 2, wherein the communication monitoring module comprises a low level counter configured to count low levels in the communication data,

wherein the low level counter provides a shutdown signal at its output for safe torque shutdown if the count of low levels reaches a predetermined threshold.

5. The power unit of claim 1 or 2, wherein the communication monitoring module comprises:

a high level counter configured to count a high level in the communication data and provide a counter indication signal of a high level if the count of the high level reaches a predetermined threshold;

a low level counter configured to count a low level in the communication data and provide a counter indication signal of a high level if the count of the low level reaches a predetermined threshold; and

a signal generating part configured to provide a shut-off signal for safe torque shut-off based on a count indication signal of a high level at an output of any one of the high level counter and the low level counter.

6. The power cell of claim 1 or 2, further comprising:

at least one isolation component configured to isolate a safe portion within the power unit for achieving a safe torque shutdown from other unsafe portions in the power unit.

7. The power cell of claim 6, wherein the at least one isolation device comprises any one of a snubber and a diode.

8. A method for safe torque shutdown, comprising:

monitoring communication data on a communication line in an electrical system;

in response to detecting that the communication data includes information indicating a safe torque-off from a user, providing a shut-off signal for the safe torque-off to a semiconductor device within the power unit and simultaneously sending a signal indicating that a safe torque-off function is in an active state to a main controller of the power unit, wherein the information indicating the safe torque-off includes at least one of high-level signals and low-level signals whose number reaches a respective predetermined threshold, and the signal indicating that the safe torque-off function is in the active state indicates that the main controller of the power unit stops operating on the communication data.

9. The method of claim 8, further comprising:

10. The method of claim 8 or 9, wherein the monitoring communication data on a communication line in an electrical system comprises: counting high levels in the communication data,

wherein a shut down signal for safe torque shut down is provided if the count of high levels reaches a predetermined threshold.

11. The method of claim 8 or 9, wherein the monitoring communication data on a communication line in an electrical system comprises: counting low levels in the communication data,

wherein a shut down signal for safe torque shut down is provided if the count of low levels reaches a predetermined threshold.

12. The method of claim 8 or 9, wherein the monitoring communication data on a communication line in an electrical system comprises: high and low levels in the communication data are counted separately,

providing a counter indication signal of a high level if the count of the high level reaches a predetermined threshold;

providing a counter indication signal of a high level if the count of the low level reaches a predetermined threshold;

wherein a shutdown signal for safe torque shutdown is provided in response to a count indication signal of a high level at an output of either of the high level counter and the low level counter.

13. The method of claim 8 or 9, further comprising:

isolating a safe portion within the power unit for achieving safe torque shutdown from other unsafe portions in the power unit.

14. The method of claim 13, wherein the isolation is achieved by any one of a buffer and a diode.

15. A user interface control device comprising:

a processing module configured to receive a control signal of safe torque off from a user, and the processing module is configured to, in response to the control signal, include information indicating the safe torque off in communication data to transmit through the communication line, wherein the information indicating the safe torque off includes at least one of a high level signal and a low level signal whose number reaches a respective predetermined threshold, based on which information a signal indicating that a safe torque off function is in an active state can be produced, the signal may indicate that at least one of a main controller of the power unit and an electrical system stops operating the communication data.

16. A method of processing a safe torque off control signal, comprising:

receiving a control signal from a user for safe torque shutdown; and

in response to the control signal, including information indicative of a safe torque shutdown in the communication data for transmission over the communication line, wherein the information indicative of a safe torque shutdown includes at least one of a high level signal and a low level signal in a number that reaches a respective predetermined threshold, a signal indicative of a safe torque shutdown function being in an active state being producible based on the information indicative of a safe torque shutdown, the signal being indicative of at least one of a main controller and an electrical system of the power unit ceasing operation of the communication data.