Method for frequency converter monitoring of operating mode of brake resistor circuit of elevator system and corresponding computer program product and use, voltage profile evaluation device and elevator system

Abstract

A method is provided for frequency converter monitoring of an operating mode of a brake resistor circuit of an elevator system comprising at least one elevator car, at least one frequency converter and at least one electric machine, in which voltage monitoring is performed to identify a voltage change, at least one braking resistor is connected with the frequency converter through an intermediate circuit; according to the invention, in order to monitor the frequency converter, at least one electronic component is activated and / or switched off repeatedly, at least one wrong operating state is detected or at least one normal operating state is determined by evaluating a voltage curve established in response to the activation and / or switching off. Therefore, an additional sensor system can also be omitted. The invention also relates to a corresponding computer program product, to the use of an electrical circuit arrangement interacting with or as part of such a brake resistor circuit, and to a corresponding voltage profile evaluation device and to an elevator system equipped with such a voltage profile evaluation device.

Description

Technical Field

[0001] The invention relates to a method for frequency converter monitoring of the operating mode of a brake resistor circuit of an elevator system, the elevator system comprising at least one elevator car, at least one frequency converter and at least one motor, the at least one motor being connected to at least one brake resistor via a frequency converter with a (DC voltage) intermediate circuit, wherein voltage monitoring is performed to detect voltage changes. The invention further relates to a voltage curve evaluation device provided for this purpose and to an elevator system comprising such a voltage curve evaluation device. Last but not least, the invention also relates to a corresponding computer program product and a corresponding use of an electrotechnical circuit arrangement interacting with or being part of such a brake resistor circuit. The invention relates in particular to a method and a device according to the preamble of the respective independent claim. Background Art

[0002] When designing and operating elevator systems or elevator installations, high safety requirements must be observed, in particular a classification into four levels, where the corresponding (failure) risks can also be weighted based on a probabilistic analysis. In elevator drives where the motor also assumes the braking function, the requirements are particularly high, especially with regard to the safety and robustness of the brake resistor circuit. In particular, in the absence of feedback from the frequency converter, a fault in the brake resistor circuit can lead to dangerous situations, especially in elevator systems. Additional devices such as temperature sensors can monitor the brake resistor and signal some (but not all) faults.

[0003] According to the prior art, for example, the frequency converter is switched off after each stroke and the charging time of the intermediate circuit is controlled before the next stroke. For example, temperature monitoring is also implemented. For example, at least one fuse and / or motor protection switch and / or overcurrent relay is provided.

[0004] The following patents describe methods and devices for functional monitoring of brake resistors or frequency converter systems: EP2672622A1, EP3455931B1.

[0005] Based on the prior art, a need can be felt for particularly robust fault diagnostics and, last but not least, for more practical solutions regarding the implementation of the diagnostics. In particular, there is an interest in improved monitoring that is as robust as possible and can be implemented using simple technical means, while still being able to diagnose or identify a wide range of potential faults. Summary of the invention

[0006] The object of the invention is to provide a method and an evaluation device by means of which faults in a brake resistor circuit of an elevator system can be detected in a manner that is as robust, comprehensive and practical as possible and, last but not least, cost-effective. It is also an object to design such a fault detection in such a way that at least one countermeasure can be implemented in the event of an expected risk or danger. Last but not least, it is an object to design the fault detection in relation to the operating mode of the brake resistor circuit of the elevator system in such a way that the diagnosis can be carried out as immediately as possible or directly in relation to relatively easy to measure operating parameters or variables.

[0007] This object is achieved by a method, by a voltage curve evaluation device and an elevator system, as well as by the use of a computer program product and a corresponding electrotechnical circuit arrangement. Advantageous developments of the invention are explained in detail in the corresponding additional technical solutions. Unless explicitly denied, the features of the exemplary embodiments described below can be combined with each other.

[0008] A method is provided for frequency converter monitoring of the operating mode of a brake resistor circuit of an elevator system, the elevator system comprising at least one elevator car, at least one frequency converter and at least one motor, the at least one motor being connected to the at least one brake resistor via the frequency converter with an intermediate circuit, wherein voltage monitoring is performed to detect (unplanned / planned) voltage changes.

[0009] According to the invention, for monitoring the frequency converter, it is proposed to repeatedly, preferably regularly (intermittently) activate and / or deactivate at least one electronic component acting in or interacting with the brake resistor circuit, wherein the brake resistor circuit is voltage-monitored in dependence on the activation and / or deactivation, wherein by evaluating the voltage curve established in response to the activation and / or deactivation of the at least one electronic component, at least one erroneous operating state is identified or at least one normal operating state is determined. This also allows robust fault monitoring by means of the electronic component, wherein the electronic component is preferably an electronic component of the brake resistor circuit.

[0010] The repeated, preferably regular activation and / or switching off of at least one electronic component interacting with or acting in the braking resistor circuit can be realized here in particular by means of an electrotechnical circuit arrangement which is, for example, integrated into a frequency converter or, for example, integrated into the braking resistor circuit or interacts therewith. The electrotechnical circuit arrangement is provided for repeatedly activating or switching the corresponding electronic component within a predefined time period or at predefined intervals, for example, several milliseconds at a time. The electrotechnical circuit arrangement can also include at least one electronic component. The electrotechnical circuit arrangement can also be configured here to switch the braking resistor, for example, by means of an insulated-gate bipolar transistor (IGBT).

[0011] According to the present disclosure, “electronic components acting in or interacting with a brake resistor circuit” are understood in particular to be electronic components present in a frequency converter or in a brake resistor circuit, in particular a chopper or a soft starter.

[0012] In other words: The invention enables the monitoring of the frequency converter with respect to actual or at least potential (or future expected) faults in the brake resistor circuit of an elevator system. In this case, the brake resistor also has a high / important safety function, in particular when the brake resistor is mainly used for braking the elevator car. In this case, the invention is based on the idea that by using existing devices (such as choppers or chopper transistors or soft starters), actual or potential faults and other problems can be identified without additional sensors or monitoring means. In this way, the safety of the elevator system during operation can also be significantly increased, in particular without additional costs, and even with a significant cost saving potential.

[0013] For example, with the aid of the measures according to the invention, the following faults in the brake resistor circuit can be identified and suitable countermeasures triggered:

[0014] - The chopper transistor is turned on for a long time due to a fault in the chopper drive part or a short circuit in the chopper itself;

[0015] - ground fault in the connection between the chopper and the brake resistor;

[0016] - ground fault in the brake resistor;

[0017] For example: If the frequency converter is switched on but does not drive the connected motor, there is a continuous voltage on the intermediate circuit (chopper transistor is switched off). In particular, the above-mentioned faults lead to a continuous current in the brake resistor, which cannot be detected by the solutions available in the prior art to date. This leads to high temperatures in the brake resistor and its surroundings and, in particular, also to permanent energy losses. In contrast, the present invention makes it possible to identify such faults with good safety or robustness, in particular by means of electronics / components already present in the brake resistor circuit, and also to selectively initiate suitable countermeasures.

[0018] When the elevator is running, in many standard embodiments, the motor is turned on each time the elevator moves and turned off when the elevator stops. When the motor is turned off, the frequency converter usually remains on, especially for contactors related to noise attenuation.

[0019] By means of the measures according to the invention, not only such faults can be detected in a simple and robust manner, but also correspondingly suitable countermeasures can be implemented.

[0020] For example, the invention is implemented in such a way that the chopper is activated at least once regularly for several milliseconds when no load is present. If no fault is present, the intermediate circuit voltage will drop slightly. This voltage drop can be detected by normal DC voltage monitoring and the absence of a fault is signaled. In the event of one of the above-mentioned faults, the brake resistor is permanently switched on completely or partially and the voltage still drops. The additional switching on of the chopper does not lead to a significant voltage drop that would indicate a possible fault.

[0021] For example, the invention is implemented in such a way that the soft starter of the frequency converter is switched off at least once regularly for several milliseconds when no load is applied. If no fault occurs, no energy is emitted from the intermediate circuit. Switching off the soft starter has little effect on the intermediate circuit voltage. In the event of one of the above mentioned faults, the intermediate circuit supplies the braking resistor. When the soft starter is switched off, the intermediate circuit voltage drops due to the power consumption of the unintentionally triggered braking resistor. The DC voltage monitoring detects the voltage drop and evaluates the voltage drop to allow an indication of a possible fault to be generated.

[0022] It will be appreciated that the switching or activation is advantageously set or specified in the 1 to 2 digit millisecond range. Here, for the different electronic components described here, in particular the chopper and the soft starter, the same duration or the same interval can be provided.

[0023] The invention offers a high cost saving potential (especially since no additional equipment is required) and also enables a greater number of potential faults to be detected. In other words: when implemented according to the invention, more possible faults can be identified / differentiated / detected. For example, with the aid of the invention, abnormal temperature increases of the brake resistor, such as are associated with the elevator being shut down, can be prevented; last but not least, this also contributes to a very safe operating behavior. Further cost advantages come, for example, from the fact that the costs of, for example, temperature sensors on the brake resistor (sensors, cables, wire end sleeves, clamps, assembly time, etc.) can be reduced or even completely saved.

[0024] For example, the present invention can also be advantageously implemented in the context of at least one of the following scenarios: Figure 2 As shown in:

[0025] Case i): There is a short circuit at the IGBT (especially the collector / emitter);

[0026] Case ii): There is a ground fault related to the brake resistor (especially the dynamic brake resistor (DBR), the IGBT transistor terminal used to switch the brake resistor);

[0027] Case iii): There is a ground fault related to the brake resistor itself (inside the DBR);

[0028] Case iv): There is a ground fault related to the DC+ terminal of the braking resistor (DBR);

[0029] In this case, the present invention provides the advantage of higher operational reliability, especially with respect to case ii. The various scenarios can also be associated with the following operating states summarized by keyword titles: drive operation of the elevator (normal travel, adjustment when the door is open), standby, regeneration operation of the elevator (normal travel, adjustment when the door is open).

[0030] For example, the invention enables safer operation of elevator systems in conjunction with the following boundary conditions and hazards or risks: high load utilization, high braking speeds, high fire protection requirements in traction-based elevator systems.

[0031] The invention may also / will also be implemented in (safety) functions specified by guidelines or standards, for example in connection with the following parts, wherein the monitoring may remain active even during / after the occurrence of one of the considered fault scenarios:

[0032] - Overvoltage and undervoltage monitoring, in particular by the frequency converter itself;

[0033] - Overspeed monitoring by control / regulating device;

[0034] - monitoring of target speed, in particular drag error monitoring, in particular by control comparison of target value and actual value, in particular including hose monitoring, in particular with bridge door safety circuit monitoring;

[0035] -Motor running time monitoring;

[0036] -Electric pre-closing speed limiter;

[0037] - Safety circuit with safe brake shutdown and motor shutdown;

[0038] Last but not least, the invention also allows a very high safety level, in particular in the case of diagnosed faults or in the case of potential faults which could lead to malfunctions of the elevator system, to the safe switching off of safety-related components.

[0039] It is understood that the invention can already be implemented at least substantially within the scope of the embodiments of the switching and evaluation described herein. In other words: in order to be able to implement the invention described herein, no (device-related) modifications or extensions of the proven circuit arrangement are necessarily required. Optionally, the invention described herein can also be implemented in addition to the already existing sensor monitoring, in particular the temperature monitoring associated with the brake resistor. It is further understood that the invention can also be implemented as an alternative or in addition to the following two monitoring options: monitoring the time required to charge the intermediate circuit to full voltage when the frequency converter is switched on (at no load, the frequency converter must be switched off); and / or permanent monitoring of at least the temperature of the brake resistor.

[0040] It should also be understood that the present invention can advantageously be implemented with a drive or motor for an elevator car, which is moved / movable by means of a traction device. Here, a corresponding elevator system can also optionally include an elevator car that is operated without ropes, and can therefore also be designed as a system composed of these different types of drives.

[0041] Last but not least, it is to be understood that the invention can also be advantageously implemented in accordance with already existing standards as well as any future regulations and standards, in particular since for many applications it is considered absolutely necessary to monitor at least the temperature of the brake resistor, but there is no provision for monitoring the temperature by means of a temperature sensor system. The invention enables indirect monitoring of at least the temperature of the brake resistor by reference to (abnormal) voltage variations; in this respect, within the scope of the invention, specific abnormal voltage curve deviations can also be associated with unacceptably high temperatures or correspondingly sharp temperature increases.

[0042] Thus, when a first electronic component is activated, a voltage drop that does not occur in response thereto is diagnosed or defined as a fault, wherein the first electronic component is a chopper transistor that is repeatedly activated, and / or when a second electronic component is turned off, a voltage drop that occurs in response thereto is diagnosed or defined as a fault, wherein the second electronic component is a soft starter of at least one frequency converter that is repeatedly turned off. This also makes it possible to implement functional integration or expansion without installing additional electronic components.

[0043] According to an embodiment, when the first electronic component is activated or switched off, a voltage drop that does not occur in response thereto (no falling voltage curve) is diagnosed / defined as a fault. This embodiment facilitates monitoring or diagnosis, in particular monitoring or diagnosis related to the function of the interface to the intermediate circuit, in particular monitoring or diagnosis related to the switching process of the chopper.

[0044] According to an embodiment, when the second electronic component is activated or deactivated, a voltage drop (a falling voltage curve) occurring in response thereto is diagnosed / defined as a fault. This embodiment facilitates monitoring or diagnosis, in particular monitoring or diagnosis related to potential faulty energy output from the intermediate circuit to the brake resistor, in particular monitoring or diagnosis related to the switching process of the soft starter.

[0045] It will be appreciated that the activation or deactivation of the first electronic component can be implemented independently of whether / when the second electronic component is activated or deactivated, and vice versa. In particular, a person skilled in the art can specify for the respective application whether the chopper and / or the soft starter should be activated / deactivated intermittently. Voltage monitoring can be implemented for all three variants (activating / deactivating only the chopper, activating / deactivating only the soft starter, activating / deactivating both the chopper and the soft starter).

[0046] According to one embodiment, a chopper transistor is used as the first electronic component, which chopper transistor is repeatedly activated, in particular for several milliseconds at no load.

[0047] According to one embodiment, a soft starter of at least one frequency converter is used as the second electronic component, which soft starter is repeatedly switched off, in particular for several milliseconds when no load is applied. This also makes it possible to repeatedly check for potential faults in each case without having to implement further sensor systems or similar additional diagnostic devices for this purpose.

[0048] According to one embodiment, in each case, the activation or deactivation is carried out for a number of milliseconds when no load is applied, for example every three minutes or every ten minutes. It has been found that this time period can be sufficient to check the safety of a good operating function. Here, for example, intervals in the range of one or several minutes (for example five minutes or fifteen minutes) are advantageous. The person skilled in the art can decide, depending on the desired embodiment, for example also on further diagnostic schemes (for example temperature measurement), whether it makes sense to switch (or deactivate) / activate repeatedly only after a few minutes, or to choose relatively long intervals (for example a plurality of intervals in the range of two-digit minutes).

[0049] According to one embodiment, the voltage monitoring includes monitoring of the DC voltage, which is advantageously implemented in the intermediate circuit or already provided for this purpose in any case and can also be used advantageously in conjunction with the diagnosis according to the invention.

[0050] For example, at least one frequency converter is a non-feedback frequency converter. Arrangements with a DC voltage intermediate circuit have proven to be particularly useful, in particular in combination with the elevator system and elevator system components described herein. It should be understood that the invention can generally be implemented within the scope of frequency converters, i.e. the corresponding frequency converter type has no restrictive effect on the voltage monitoring described herein.

[0051] According to one embodiment, by evaluating the curve of the voltage, at least one erroneous operating state from the following group is determined and a fault signal associated therewith is generated: permanent conduction of the chopper, in particular due to a chopper driver fault or a short circuit of the chopper, a (faulty) ground fault of the connection between the chopper and the brake resistor, a (faulty) ground fault of the brake resistor. According to the invention, this diagnostic coverage can be ensured by electronic components of the frequency converter or the brake resistor circuit.

[0052] It should be understood that the faults described here can be diagnosed both by (off) switching or activating the chopper and by (off) switching or activating the soft starter. These two processes can also be considered to be of equal importance.

[0053] According to an embodiment, the predefined voltage variation is correlated with the temperature variation of the brake resistor, in particular by correspondingly storing a correlation in a data memory of the voltage curve evaluation device, so that at least indirect monitoring of the temperature of the brake resistor is detected by correlation with the measured voltage variation. In this respect, within the scope of the invention, specific abnormal voltage curve deviations can also be correlated with unacceptably high temperatures or correspondingly sharp temperature increases. Last but not least, this also contributes to the complete exemption of sensor-based temperature monitoring in compliance with any provisions of standards or guidelines.

[0054] The above-mentioned objects are also achieved by a method for controlling / regulating an elevator system based on the method for frequency converter monitoring disclosed herein, wherein, in response to the diagnosis / definition of at least one fault, the elevator system, at least one elevator car of the elevator system or drive-related components (also components related to the braking function) associated with at least one elevator car of the elevator system are switched (switched off) in particular by means of a control / regulatory device of the elevator system. Last but not least, this helps in particular to implement safety measures which are directly related to the operation of the elevator system.

[0055] According to one embodiment, the method is performed when the frequency converter is further turned on and the motor is already turned off (the motor is in standby state or the system is in no-load state), wherein the shutdown is performed in a manner to avoid continuous current in the braking resistor. This can also make the elevator system run more safely.

[0056] The above-mentioned object is also achieved by a computer program product comprising instructions, which, when executed on a computer, cause the computer program product to perform a method for frequency converter monitoring according to the present disclosure on or by means of a computer, in particular the computer program product is arranged to generate a control / regulation specification for an elevator system as a function of the diagnosis of at least one fault in a brake resistor circuit. In other words: it is not only advantageous to monitor by means of the computer program product, but also to generate a control / regulation specification for a control / regulation device in particular for an elevator system. Based on the above-mentioned advantages, this also enables, for example, an improvement of the functional scope described here for systems already installed in the field. It should be understood that the present invention can already be implemented at least substantially within the scope of a computer-implemented embodiment. In other words, device-related expansions / supplements are not necessarily required. Optionally, a temperature measurement can also be additionally taken into account in the evaluation, for example within the scope of a plausibility check or an additional comparison of a plurality of diagnostic results with one another. The corresponding control / regulation specification can also be a fixation that specifies the operating mode of at least one safety device, such as a safety brake.

[0057] The above-mentioned object can also be achieved by using an electrotechnical circuit arrangement, which is configured to repeatedly activate and / or (turn on / off) switch at least one electronic component from the group of a chopper or a chopper transistor and a soft starter device that interacts with or acts in a brake resistor circuit of an elevator system, for monitoring the operating mode of the brake resistor circuit of the elevator system, wherein voltage monitoring is performed with respect to the brake resistor circuit in accordance with the activation and / or switching, wherein at least one erroneous operating state is identified or at least one normal operating state is determined by evaluating a voltage curve established in response to the activation and / or switching of at least one electronic component, in particular in a method for frequency converter monitoring according to the present disclosure. Thus, the above-mentioned advantages can be achieved, in particular with respect to a relatively simple and cost-effectively implemented diagnostic process based on at least partially already existing electronic / electrotechnical components. Here, when a first electronic component is activated, a voltage drop that does not occur in response thereto is diagnosed / defined as a fault, and / or when a second electronic component is switched off, a voltage drop that occurs in response thereto is diagnosed / defined as a fault.

[0058] The above object is also achieved by a voltage curve evaluation device, which is arranged for frequency converter monitoring of the operating mode of a brake resistor circuit of an elevator system, the elevator system comprising at least one elevator car, at least one frequency converter and at least one motor, the at least one motor being connected to the at least one brake resistor via the frequency converter with an intermediate circuit, wherein voltage monitoring is performed to identify (unplanned / planned) voltage changes; wherein the voltage curve evaluation device is arranged to perform voltage monitoring based on repeated, preferably regular (intermittent) activation and / or switching off of at least one electronic component acting in or interacting with the brake resistor circuit, in particular in the case of repeated activation and / or (on / off) switching by means of an electrotechnical circuit arrangement, wherein the voltage curve evaluation device is arranged to identify at least one erroneous operating state or determine at least one normal operating state by evaluating the curve of the voltage, in particular the voltage curve evaluation device is arranged to perform the method for frequency converter monitoring according to the disclosure. This brings about the above advantages, in particular with regard to the appropriate use of at least some already existing electronic / electrotechnical components for (fault) diagnosis purposes. Here, when the first electronic component is activated, a voltage drop that does not occur in response thereto may be diagnosed / defined as a fault, and / or when the second electronic component is turned off, a voltage drop that occurs in response thereto may be diagnosed / defined as a fault.

[0059] According to one embodiment, the electrical circuit arrangement has at least one first electronic component configured as a chopper transistor, which can be repeatedly activated, in particular can be repeatedly activated for several milliseconds when no-load; and / or wherein the electrical circuit arrangement has at least one second electronic component configured as a soft start device of the frequency converter, which can be repeatedly shut down, in particular can be repeatedly shut down for several milliseconds when no-load.

[0060] According to an embodiment, repeated activation and / or (on / off) switching may be performed in such a manner that when a first electronic component is activated or turned off, a voltage drop that does not occur in response thereto may be diagnosed as a fault. Repeated activation (on / off) switching may also be performed in such a manner that when a second electronic component is activated or turned off, a voltage drop that occurs in response thereto may be diagnosed as a fault.

[0061] The above object is also achieved by an elevator system including the voltage curve evaluation device according to the present disclosure, wherein the elevator system includes at least one elevator car, at least one frequency converter and at least one motor, wherein the at least one motor is connected to at least one braking resistor via the frequency converter with an intermediate circuit. In this case in particular, the above advantages can be achieved particularly effectively.

[0062] In the design and operation of elevator systems, high safety requirements must be observed, in particular in elevator drives in which the motor also assumes a braking function, for example with regard to the safety of a brake resistor circuit. A method for frequency converter monitoring of an operating mode of a brake resistor circuit of an elevator system is provided, the elevator system comprising at least one elevator car, at least one frequency converter and at least one motor, the at least one motor being connected to at least one brake resistor via a frequency converter with an intermediate circuit, wherein voltage monitoring is performed to identify voltage changes; according to the invention, for frequency converter monitoring, at least one electronic component acting in the brake resistor circuit or interacting with the brake resistor circuit is repeatedly activated and / or switched off, wherein at least one erroneous operating state is identified or at least one normal operating state is determined by evaluating a voltage curve established in response to the activation and / or switching off of the at least one electronic component. Thus, additional sensor systems can also be omitted. The invention also relates to a corresponding computer program product, the use of an electrotechnical circuit arrangement interacting with or being part of such a brake resistor circuit, and a corresponding voltage curve evaluation device and an elevator system equipped with the voltage curve evaluation device. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In the following drawings, the present invention will be described in more detail, wherein for reference numerals not explicitly described in the corresponding drawings, reference will be made to other drawings. In the schematic diagram, respectively:

[0064] Figure 1 In a circuit arrangement for carrying out a method for monitoring a frequency converter according to an embodiment, there is an arrangement of a brake resistor circuit;

[0065] Figure 2 exist Figure 1 Potential sources of failure in the arrangement;

[0066] Figure 3 A component of an elevator system configured to perform a method for frequency converter monitoring according to an embodiment;

[0067] Figure 4 Steps for executing a method for frequency converter monitoring and their interaction with components according to an embodiment. DETAILED DESCRIPTION

[0068] The present invention is first explained with reference to all reference numerals and drawings. Features or aspects of the present invention are discussed in conjunction with the corresponding drawings.

[0069] An elevator system 100 is provided, which comprises at least one elevator car 101, which can be moved by at least one motor 3, wherein the motor 3 is connected to at least one brake resistor 4 or brake resistor circuit 1 via a frequency converter 2 with an intermediate circuit 5. At least one electronic component 10 associated with the brake resistor circuit and / or the frequency converter can be activated (in particular can be switched on / off intermittently) in such a way that voltage monitoring can be performed with respect to the brake resistor circuit in accordance with the activation and / or switching off, wherein by evaluating the voltage curve established in response to the activation and / or switching off of the at least one electronic component, at least one faulty operating state can be identified or at least one normal operating state can be determined. The at least one electronic component 10 can be provided as part of an electrotechnical circuit arrangement 40, or the corresponding switching function can be retrofitted to the corresponding electronic component 10. The at least one electronic component 10 advantageously comprises at least one chopper 10a (chopper transistor, chopper driver part) for the brake resistor and / or at least one soft starter 10b for the frequency converter, optionally at least these two components. The voltage monitoring described here can be performed with the aid of the voltage curve evaluation device 20 and can also be recorded locally or on a central server, for example by storing the voltage measurement values ​​in a system-specific manner (preferably wirelessly) on the central server. This facilitates system-specific maintenance and inspections, for example, in the case of elevator systems with a large number of motors. The voltage curve evaluation device 20 can include a DC voltage monitoring unit 21 associated with the intermediate circuit 5. The control / regulator 30 of the elevator system 100 can also generate control signals in particular as a function of the measured voltage values, or the system can be triggered accordingly, for example switched off.

[0070] In this case, according to an embodiment of the present invention, a method for frequency converter monitoring associated with a fault-free operating mode of a brake resistor circuit of an elevator system can be implemented essentially based on four steps: a first step S1: repeatedly activating or deactivating at least one electronic component that (inter)acts in / with the brake resistor circuit; a second step S2, voltage monitoring by voltage curve evaluation, in particular comprising a step S2a, diagnosing a fault in response to activation of the chopper without a voltage drop in the intermediate circuit, and / or comprising a step S2b, diagnosing a fault in response to a shutdown of the soft starter with a voltage drop in the intermediate circuit; a third step S3 generating a fault signal; a fourth step S4 (deactivating) switching at least one component associated with the drive;

[0071] exist Figure 1 , a brake resistor circuit 1 is shown, wherein a frequency converter with an intermediate circuit connects at least one brake resistor 4 to a motor. The electrical circuit arrangement 40 described here comprises at least one electronic component from the group of a chopper (transistor) and a soft starter that can be repeatedly activated / deactivated.

[0072] exist Figure 2 It is shown in Figure 1 Exemplary potential sources of failure in the arrangement shown:

[0073] Case i): short circuit at the IGBT;

[0074] Case ii): Ground fault related to the brake resistor IGBT terminal;

[0075] Case iii): Ground fault related to the brake resistor itself;

[0076] Case iv): Ground fault related to terminal DC+ of the brake resistor;

[0077] For example, an IGBT can be used as a transistor for switching a brake resistor (DBR dynamic brake resistor). An IGBT can be part of a circuit arrangement described herein. Here, DC+ is understood to be the positive pole of the intermediate circuit (ground potential: approximately +50% of the intermediate circuit voltage), and DC- is understood to be the negative pole of the intermediate circuit (ground potential: approximately -50% of the intermediate circuit voltage).

[0078] exist Figure 3 1 shows an elevator system 100 in which an elevator car 101 moved / movable by means of a traction device can be driven and braked by means of at least one motor 3. The elevator system can optionally include an elevator car that is operated without ropes and an elevator car that is moved by means of a traction device and can therefore also be designed as a system composed of these different types of drive devices.

[0079] exist Figure 4 An exemplary correlation between the steps of the method described herein and the components of the elevator system is shown in . In conjunction with step S3, a fault signal Sf may be generated and sent / transmitted accordingly, and in conjunction with step S4, a control signal Sc may be generated and sent / transmitted accordingly.

[0080] Reference numerals list

[0081] 1Brake resistor circuit

[0082] 2Inverter

[0083] 3 Motor

[0084] 4Brake resistor

[0085] 5Intermediate circuit

[0086] 10 Electronic components that interact with the brake resistor circuit

[0087] 10A Chopper for Braking Resistor

[0088] 10b Soft start device for frequency converter

[0089] 20 Voltage curve evaluation device

[0090] 21 DC voltage monitoring unit

[0091] 30 Control / regulation device

[0092] 40 Electrical circuit layout

[0093] 100 Elevator System

[0094] 101 Elevator Car

[0095] Sf fault signal

[0096] Sc control signal

[0097] S1 repeatedly activates or deactivates at least one electronic component in / interacting with the brake resistor circuit

[0098] S2 Voltage monitoring by voltage curve evaluation

[0099] S2a responds to the activation of the chopper and diagnoses faults without voltage drop in the intermediate circuit

[0100] S2b responds to the soft starter switching off and diagnoses faults in the event of a voltage drop in the intermediate circuit

[0101] S3 generates a fault signal

[0102] S4 switches (or turns off) at least one drive-related component.

Claims

1. A method for frequency converter monitoring of an operating mode of a brake resistor circuit (1) of an elevator system (100), the elevator system (100) comprising at least one elevator car (101), at least one frequency converter (2) and at least one motor (3), the at least one motor (3) being connected to at least one brake resistor (4) via a frequency converter having an intermediate circuit (5), wherein: Conduct voltage monitoring to identify voltage changes; wherein, for monitoring the frequency converter, at least one electronic component (10, 10a, 10b) acting in the brake resistor circuit (1) or interacting with the brake resistor circuit (1) is repeatedly activated and / or deactivated, wherein the brake resistor circuit (1) is voltage-monitored in dependence on the activation and / or deactivation, wherein at least one erroneous operating state is identified or at least one normal operating state is determined by evaluating a voltage curve established in response to the activation and / or deactivation of the at least one electronic component (10); wherein, when a first electronic component is activated, a voltage drop that does not occur in response thereto is diagnosed / defined as a fault, wherein the first electronic component is a chopper transistor that is repeatedly activated, and / or wherein, when a second electronic component is turned off, a voltage drop that occurs in response thereto is diagnosed / defined as a fault, wherein the second electronic component is a soft start device of at least one inverter that is repeatedly turned off.

2. The method according to claim 1, wherein: The first electronic component is repeatedly activated for several milliseconds when not loaded; and / or the second electronic component is repeatedly turned off for several milliseconds when not loaded.

3. The method according to claim 1, wherein: At no load, they are activated or deactivated for a few milliseconds respectively.

4. The method according to claim 1, wherein: Voltage monitoring includes DC voltage monitoring.

5. The method according to claim 1, wherein: By evaluating the curve of the voltage, at least one erroneous operating state from the following group is determined and a fault signal associated therewith is generated: a permanent conduction of the chopper, in particular due to a chopper driver fault or a short circuit of the chopper; a ground fault of the connection between the chopper and the brake resistor; and a ground fault of the brake resistor.

6. The method according to claim 1, wherein: The predefined voltage variation is correlated to a temperature variation of the brake resistor, such that at least indirect monitoring of the temperature of the brake resistor can be detected by correlation with the measured voltage variation.

7. A method for controlling / regulating an elevator system (100) based on the method for frequency converter monitoring according to any one of claims 1 to 6, wherein: In response to the diagnosis / definition of at least one fault, the elevator system (100), at least one elevator car (101) of the elevator system or a drive-related component associated with the at least one elevator car of the elevator system is switched, in particular by means of a control / regulatory device (30) of the elevator system.

8. The method according to claim 7, wherein: The method is carried out when the frequency converter (2) is further switched on and the electric machine (3) has been switched off, wherein the switching off is carried out in such a way that a continuous current in the braking resistor is avoided.

9. A computer program product comprising instructions which, when executed on a computer, cause the computer program product to perform a method according to any one of claims 1 to 6 on the computer, in particular the computer program product being arranged to generate control / regulation specifications for an elevator system (100) depending on the diagnosis of at least one fault in a brake resistor circuit.

10. Use of an electrotechnical circuit arrangement (40) arranged for repeatedly activating and / or switching at least one electronic component (10, 10a, 10b) from the group of a chopper (10a) and a soft starter (10b) interacting with or acting in a brake resistor circuit (1) of an elevator system (100) for monitoring an operating mode of the brake resistor circuit (1) of the elevator system (100), wherein: Voltage monitoring of the brake resistor circuit is performed in response to activation and / or switching, wherein at least one erroneous operating state is identified or at least one normal operating state is determined by evaluating a voltage curve established in response to activation and / or switching of at least one electronic component (10), in particular in a method according to any one of claims 1 to 6, wherein when a first electronic component is activated, a voltage drop that does not occur in response thereto is diagnosed / defined as a fault, and / or wherein when a second electronic component is switched off, a voltage drop that occurs in response thereto is diagnosed / defined as a fault.

11. A voltage curve evaluation device (20), the voltage curve evaluation device (20) being configured for frequency converter monitoring of an operating mode of a brake resistor circuit (1) of an elevator system (100), the elevator system (100) comprising at least one elevator car (101), at least one frequency converter (2) and at least one motor (3), the at least one motor (3) being connected to at least one brake resistor (4) via a frequency converter having an intermediate circuit (5), wherein: Voltage monitoring is performed to identify voltage changes; wherein the voltage curve evaluation device (20) is arranged to perform voltage monitoring based on repeated, preferably regular activation and / or switching off of at least one electronic component (10) acting in the brake resistor circuit or interacting with the brake resistor circuit, in particular when repeated activation and / or switching between on and off is performed by means of an electrotechnical circuit arrangement, wherein the voltage curve evaluation device (20) is arranged to identify at least one erroneous operating state or determine at least one normal operating state by evaluating the curve of the voltage, in particular the voltage curve evaluation device, the voltage curve evaluation device (20) being arranged to perform a method for frequency converter monitoring according to any one of claims 1 to 6, wherein when a first electronic component is activated, a voltage drop that does not occur in response to this is diagnosed / defined as a fault, and / or wherein when a second electronic component is switched off, a voltage drop that occurs in response to this is diagnosed / defined as a fault.

12. The voltage curve evaluation device according to claim 11, wherein: The electrical circuit arrangement has at least one first electronic component configured as a chopper transistor, which can be repeatedly activated, in particular for several milliseconds when no-load; and / or wherein the electrical circuit arrangement has at least one second electronic component configured as a soft start device of the frequency converter, which can be repeatedly shut down, in particular for several milliseconds when no-load.

13. The voltage curve evaluation device according to claim 11 or 12, wherein: Repeated activation and / or switching between on and off is performed in such a way that when the first electronic component is activated or turned off, a voltage drop that does not occur in response thereto is diagnosed as a fault, and / or wherein repeated activation or switching between on and off is performed in such a way that when the second electronic component is activated or turned off, a voltage drop that occurs in response thereto is diagnosed as a fault.

14. An elevator system (100), comprising a voltage curve evaluation device (20) according to any one of claims 11 to 13, wherein: The elevator system comprises at least one elevator car (101), at least one frequency converter (2) and at least one motor (3), which is connected to at least one braking resistor (4) of the elevator system via the frequency converter having an intermediate circuit (5).

Images