Elevator drive unit, elevator system and method for managing regenerative power of an elevator system

Abstract

The invention relates to an elevator drive unit (200) for managing regenerative power of an elevator system (100). The elevator drive unit (200) comprises a first terminal (220a) for connecting the elevator drive unit (200) to a power grid (230), a second terminal (220b) for connecting the elevator drive unit (200) to an elevator hoisting motor (210), a frequency converter (240) for enabling bidirectional power transfer between the power grid (230) and the elevator hoisting motor (210), and a control unit (250). The control unit is configured to obtain an indication representing detection of a special operating condition of the elevator system (100), introduce a non-zero power limit specific to the detected special operating condition of the elevator system (100), and control the frequency converter (240) to limit supply of regenerative power from the elevator hoisting motor (210) to the power grid (230) to the power limit. The invention also relates to an elevator system (100) and a method for managing regenerative power of an elevator system (100).

Description

Technical Field

[0001] This invention relates generally to the technical field of elevators. In particular, this invention relates to elevator drive units. Background Technology

[0002] Modern elevator systems include an elevator drive system configured to drive an elevator car in an elevator shaft between multiple floors based on service requests received from elevator passengers, for example. The elevator drive system includes an elevator hoist motor, such as a permanent magnet motor, and an elevator drive unit for controlling the hoist motor. The elevator drive unit includes power switches, such as insulated-gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), gallium nitride (GaIN) transistors, or silicon carbide (SiC) transistors, arranged, for example, as a frequency converter. The frequency converter may have an AC input terminal connected to a mains power supply and an AC output terminal connected to the elevator hoist motor windings. The frequency converter is operable to convert mains AC voltage (e.g., 50 Hz, 230V) into a variable voltage, i.e., a variable amplitude, variable frequency AC voltage for the elevator hoist motor.

[0003] Modern elevator drive units can selectively operate in either electric or regenerative mode. In electric mode, the elevator drive unit transmits electricity from the power grid to the elevator hoisting motor. In regenerative mode, the elevator drive unit returns regenerative power (such as braking force) from the elevator hoisting motor back to the power grid.

[0004] Under special operating conditions, the regenerative power supplied to the AC power grid may be reduced. One such operating condition is a mains power outage, but it should be understood that other situations may also occur. Typically, elevator drive systems are equipped with an additional brake chopper circuit to handle regenerative power under such special operating conditions. The brake chopper circuit includes a power resistor and a power transistor to control the current through the resistor. Any additional power is dissipated as heat in the power resistor via the brake chopper circuit. Brake chopper circuits can be large, expensive, and difficult to integrate into the elevator drive unit. It can also be a source of additional electromagnetic interference, such as common-mode interference from the building.

[0005] Therefore, further solutions are needed to improve the management of regenerative power in elevator systems. Summary of the Invention

[0006] To provide a basic understanding of some aspects of various embodiments of the invention, a simplified overview is given below. This overview is not a comprehensive summary of the invention. It is neither intended to identify key or essential elements of the invention nor to depict the scope of the invention. The following overview merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplary embodiments of the invention.

[0007] The object of this invention is to provide an elevator drive unit, an elevator system, and a method for managing the regenerative power of the elevator system. Another object of this invention is that the elevator drive unit, elevator system, and method for managing the regenerative power of the elevator system can improve the management of the regenerative power of the elevator system.

[0008] The objective of this invention is achieved by the elevator drive unit, elevator system, and method defined in this specification.

[0009] According to a first aspect, an elevator drive unit for managing regenerative power of an elevator system is provided, wherein the elevator drive unit includes: a first terminal for connecting the elevator drive unit to a power grid; a second terminal for connecting the elevator drive unit to an elevator hoisting motor; a frequency converter for enabling bidirectional power transmission between the power grid and the elevator hoisting motor; and a control unit configured to: obtain an indication indicating a detected special operating condition of the elevator system; introduce a non-zero power limit specific to the detected special operating condition of the elevator system; and control the frequency converter to limit the regenerative power supply from the elevator hoisting motor to the power grid to the power limit.

[0010] The control unit can be configured to control the frequency converter to control the motor current, thereby increasing the power loss of the elevator hoisting motor.

[0011] The control unit can be configured to introduce harmonics into the motor current to increase the power loss of the elevator hoisting motor.

[0012] Alternatively or additionally, the control unit may be configured to control a frequency converter to control the elevator hoisting motor, thereby increasing the power loss of the elevator hoisting motor.

[0013] The control unit can be configured to control the frequency converter to control the elevator hoisting motor to operate in a field-weakening mode, thereby increasing the power loss of the elevator hoisting motor.

[0014] The power loss of an elevator hoisting motor may include core loss and / or resistance loss in the elevator hoisting motor.

[0015] Alternatively or additionally, the control unit may be configured to control the frequency converter to increase the power loss of the frequency converter.

[0016] Special operating conditions for elevator systems may include situations where it is necessary to reduce the regenerative power supplied from the elevator hoisting motor to the power grid.

[0017] Alternatively or additionally, special operating conditions of the elevator system may include power grid outages, power grid shortages, backup power supply conditions, elevator car braking conditions, elevator component overheating conditions, and / or smart grid conditions.

[0018] The elevator drive unit may further include a power switch device arranged as a frequency converter, wherein the control unit may be connected to the control pole of the power switch device.

[0019] The frequency converter may include: a rectifier bridge formed by power switching devices, the rectifier bridge including an AC input and a DC output connected to a first terminal; and a motor bridge formed by power switching devices, the motor bridge including an AC output connected to a second terminal and a DC input connected to the DC output of the rectifier bridge via a DC link; wherein a control unit may be connected to the power switching device control poles of the rectifier bridge and the motor bridge, and wherein the control unit may be configured to: control the rectifier bridge by controlling the power switching devices of the rectifier bridge to limit the regenerative power supply from the DC link to the power grid to a power limit, and control the motor bridge to control the motor current to limit the regenerative power supply from the elevator hoist motor to the DC link by increasing the power loss of the elevator hoist motor.

[0020] According to a second aspect, an elevator system is provided, comprising: an elevator control unit, an elevator car configured to travel along an elevator shaft between multiple floors, an elevator hoisting motor for driving the elevator car, and the aforementioned elevator drive unit, wherein the elevator control unit is communicatively connected to the elevator drive unit.

[0021] The elevator control unit can be configured to determine special operating conditions of the elevator system.

[0022] Alternatively or additionally, the elevator control unit may be configured to determine at least one non-zero power limit specific to a particular operating condition.

[0023] According to a third aspect, a method for managing regenerative power in an elevator system is provided, wherein the method includes: determining at least one non-zero power limit specific to a particular operating condition by an elevator control unit; detecting the particular operating condition of the elevator system by the elevator control unit; and limiting the regenerative power supply from the elevator hoisting motor to the power grid by an elevator drive unit to the power limit specific to the detected particular operating condition of the elevator system.

[0024] Various exemplary and non-limiting embodiments of the invention with respect to structure and operation methods, as well as their additional objects and advantages, will be best understood from the following description of specific exemplary and non-limiting embodiments when read in conjunction with the accompanying drawings.

[0025] The verbs “comprising” and “including” are used herein as limitations on disclosure, neither excluding nor requiring the presence of any uncited features. Unless otherwise expressly stated, the features described in the dependent claims may be freely combined with each other. Furthermore, it should be understood that the use of “a” or “an” throughout this document, i.e., the singular form, does not exclude the plural. Attached Figure Description

[0026] In the accompanying drawings, embodiments of the invention are shown by way of example rather than limitation.

[0027] Figure 1 An example of an elevator system is illustrated schematically.

[0028] Figure 2 An example of an elevator drive system is illustrated schematically.

[0029] Figure 3 An example of a method for managing the regenerative power of an elevator system is illustrated schematically.

[0030] Figure 4A An example of a frequency converter in an elevator drive unit is illustrated schematically.

[0031] Figure 4B This schematically illustrates another example of a frequency converter in an elevator drive unit.

[0032] Figure 5 An example of the components of the control unit of an elevator drive unit is shown schematically.

[0033] Figure 6 An example of a component of an elevator control unit is shown schematically. Detailed Implementation

[0034] Figure 1 An example of an elevator system 100 is schematically shown. The elevator system 100 includes an elevator car 102, an elevator control unit 110, and an elevator drive system 120. The elevator car 102 is configured to travel along an elevator shaft 104 between multiple floors 106a-106n. The elevator control unit 110 is configured to at least partially control the operation of the elevator system 100. The elevator control unit 110 may be located, for example, in a machine room (for clarity, ...). Figure 1(Not shown in the diagram) or in one of the floors 106a-106n of the elevator system 100. The elevator drive system 120 is configured to drive the elevator car 102 between multiple floors 106a-106n in the elevator shaft 104 according to service requests received, for example, from elevator passengers. The elevator drive system 120 includes an elevator drive unit 200 and an elevator hoisting motor 210 for driving the elevator car 102. The elevator drive unit 200 is configured to control the elevator hoisting motor 210. The elevator motor 210 may be, for example, a permanent magnet motor. An elevator control unit 110 may be communicatively connected, i.e., coupled to the elevator drive unit 200. Communication between the elevator drive unit 200 and the elevator control unit 110 may be based on one or more known wired or wireless communication technologies. The elevator control unit 110 may command the elevator drive unit 200 to control the elevator hoisting motor 210 to move the elevator car 102 along the elevator shaft 104. Elevator system 100 may also include one or more other elevator-related entities, such as safety circuits and devices, elevator door systems, etc. For clarity, Figure 1 It is not shown in the document.

[0035] Figure 2 An example of an elevator drive system 120, including an elevator drive unit 200 and an elevator hoisting motor 210, is schematically shown. The elevator drive unit 200 includes a first terminal 220a, such as an AC input terminal, for connecting the elevator drive unit 200 to a power grid 230; a second terminal 220b, such as an AC output terminal, for connecting the elevator drive unit 200 to the elevator hoisting motor 210, for example, to the windings of the elevator hoisting motor 210; a frequency converter 240; and a control unit 250. The frequency converter 240 enables bidirectional power transfer between the power grid 230 and the elevator hoisting motor 210. The frequency converter 240 is operable to convert AC mains voltage (e.g., 50 Hz, 230V voltage) into AC voltage with variable amplitude and variable frequency for the elevator hoisting motor 210. The drive unit 200 may include power switching devices 480a, 480b arranged as the frequency converter 240. In other words, the frequency converter 240 can be formed, i.e., configured, by the power switching devices 480a, 480b. The control unit 250 of the elevator drive unit 200 can be connected to the control electrode of the power switching devices 480a and 480b. The power switching devices 480a and 480b can be, for example, insulated-gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), gallium nitride (GaIN) transistors, or silicon carbide (SiC) transistors. For clarity, the power switching devices 480a and 480b are not shown in the diagram. Figure 2 As shown in the image.

[0036] Figure 3An example of a method for managing (i.e. processing) the regenerative power of elevator system 100 is illustrated schematically. Figure 3 The example method is illustrated schematically in the form of a flowchart.

[0037] In step 310, the elevator control unit 110 determines at least one non-zero power limit specific to a particular operating condition. The elevator control unit 110 may provide the determined at least one special operating condition-specific power limit to the control unit 250 of the elevator drive unit 200. The expression "specific to a particular operating condition" in the context of power limits means that throughout the application, the power limit can be specific to each particular operating condition, i.e., determined according to the particular operating condition. The expression "non-zero" in the context of power limits means that throughout the application, the power limit can be any positive power value, but not zero. Special operating conditions of the elevator system 100 may include situations requiring a reduction in regenerative power supplied from the elevator hoist motor 210 to the power grid 230. Special operating conditions of the elevator system 100 may include, for example, but not limited to, power grid power outages, power grid power shortages, backup power (e.g., generator power) situations, braking of the elevator car 102, overheating of elevator components (e.g., overheating of the elevator hoist motor 210 or elevator drive unit 200), and / or smart grid situations, i.e., receiving information about a particular operating condition from the power company. However, it should be understood that other special operating conditions may also arise, and at least one operation-specific non-zero power limit may be determined for said other special operating conditions. According to examples, a first power limit may be determined (i.e., allocated) for power grid interruption, power grid shortage, or backup power conditions, and a second power limit, for example, higher than the first power limit, may be determined for power grid operability conditions (e.g., braking of elevator car 102). In the latter case, the second power limit may be used, for example, to limit power peaks, such as those occurring during regeneration, such as braking the elevator car 102 when it begins to decelerate from its nominal speed towards the destination floor.

[0038] In step 320, the elevator control unit 110 detects a special operating condition of the elevator system 100. The detected special operating condition may fall under the category of operating conditions for which a non-zero power limit specific to the special operating condition was determined in step 310. In response to the detection of the special operating condition, the elevator control unit 110 provides an indication to the control unit 250 of the elevator drive unit 200 indicating that a special operating condition of the elevator system 100 has been detected. The control unit 250 of the elevator drive unit 200 receives (i.e., obtains from) the indication indicating that a special operating condition of the elevator system 100 has been detected. In response to receiving this indication, the control unit 250 of the elevator drive unit 200 introduces a power limit specific to the detected special operating condition of the elevator system 100. In other words, the control unit 250 of the elevator drive unit 200 operates in a limited power mode in response to receiving the indication from the elevator control unit 250 indicating that a special operating condition of the elevator system 100 has been detected.

[0039] In step 330, the control unit 250 of the elevator drive unit 200 controls the frequency converter 240 to limit the regenerative power supply from the elevator hoisting motor 210 to the power grid 230 to a power limit specific to the detected special operating condition of the elevator system 100. In other words, the control unit 250 of the elevator drive unit 200 controls the frequency converter 240 such that the regenerative power supply from the elevator hoisting motor 210 to the power grid 230 is limited to a power limit specific to the detected special operating condition of the elevator system 100. In other words, the regenerative power from the elevator hoisting motor 210 to the power grid 230 is not allowed to exceed the power limit specific to the detected special operating condition of the elevator system 100. This allows at least a portion of the regenerative power to be dissipated as heat in the elevator hoisting motor 210. Therefore, a separate brake chopper circuit is not required to handle the additional regenerative power. The control unit 250 of the elevator drive unit 200 can control (i.e., cause) the frequency converter 240 to limit the supply of regenerative power from the elevator hoisting motor 210 to the power grid 230 to a power limit specific to a particular operating condition of the detected elevator system 100 by controlling the power switching devices 480a, 480b. The limitation of the regenerative power supply in step 330 can be applied to the entire elevator operation or at least a portion of the elevator operation, for example, depending on the detected particular operating condition.

[0040] According to the example, step 330, controlling the frequency converter 240 may include the control unit 250 of the elevator drive unit 200 controlling the frequency converter 240 to control the motor current to increase the power loss of the elevator hoisting motor 210. The power loss may include core losses and / or resistive losses of the elevator hoisting motor 210, for example, in the windings of the elevator hoisting motor 210. The control unit 250 of the elevator drive unit 200 may, for example, introduce harmonics into the motor current to increase the power loss of the elevator hoisting motor 210, such as core losses.

[0041] According to another example, the control of the frequency converter 240 in step 330 may alternatively or additionally include the control unit 250 of the elevator drive unit 200 controlling the frequency converter 240 to control the elevator hoisting motor 210 to increase the power loss of the elevator hoisting motor 210. The control unit 250 of the elevator drive unit 200 may, for example, control the frequency converter 240 to control the elevator hoisting motor 210 to operate in a field-weakening mode, thereby increasing the power loss of the elevator hoisting motor 210. In field-weakening mode, the magnetizing shaft current component is directed to the elevator hoisting motor 210, causing it to weaken the magnetization of the magnetizing shaft (i.e., the d-axis), such as the magnetization caused by the permanent magnets of a permanent magnet motor. In field-weakening mode, the elevator hoisting motor 210 can operate above its rated speed, but is not necessarily required to operate above the rated speed. Typically, field-weakening mode can be used for operation above the rated speed, but even when used at the rated speed, field-weakening mode may increase the motor current, which leads to increased resistive losses in the windings of the elevator hoisting motor 210, and thus increases the power loss in the elevator hoisting motor 210.

[0042] According to another example, the control of the frequency converter 240 in step 330 may alternatively or additionally include the control unit 250 controlling the frequency converter 240 to increase the power loss of the frequency converter 240. The power loss of the frequency converter 240 may include, for example, the power loss of filter components of the frequency converter 240 (e.g., line filters, motor-side DU / Dt filters) and / or the power loss of the fans of the frequency converter 240. The fans of the frequency converter 240 may be used for convection cooling of the power switching devices 480a, 480b of the frequency converter 240. The fan speed is controllable, and when the fans are running at full speed, they may consume even several kilowatts of additional power. For clarity, in Figure 4A and 4B The fan is not shown.

[0043] Figure 4A A simple example of the frequency converter 240 of the elevator drive unit 200 is shown schematically. Figure 4AThe example frequency converter 240 includes a rectifier bridge 410 formed by power switching device 480a and a motor bridge, i.e., an inverter bridge 430, formed by power switching device 480b. The rectifier bridge 410 includes an AC input 440 connected to a first terminal 220a and a DC output 450. The motor bridge 430 includes an AC output 460 connected to a second terminal 220b and a DC input 470 connected to the DC output 450 of the rectifier bridge 410 via a DC link 420. For clarity, power switching devices 480a and 480b are not shown in the diagram. Figure 4A As shown in the image. Figure 4B Another example of the frequency converter 240 of the elevator drive unit 200 is shown. Figure 4B In the example, a non-limiting example is shown of the power switching device 480a forming the rectifier bridge 410, the power switching device 480b forming the motor bridge 430, and the DC link 420. In other aspects, Figure 4B The example frequency converter 240 is similar to Figure 4A Example frequency converter 240. DC link 420 may include, for example, capacitor 490 or a set of capacitors connected in parallel with high voltage bus 495a and low voltage bus 495b. The power switching device 480a of rectifier bridge 410 and the power switching device 480b of motor bridge 430 may be, for example, IGBT, MOSFET, gain transistor or SiC transistor, as described above. Control unit 250 of elevator drive unit 200 is connected to the control terminal of power switching device 480a of rectifier bridge 410 and the control terminal of power switching device 480b of motor bridge 430. For clarity, Figure 4B The first terminal 220a, the second terminal 220b, the AC input 440, the AC output 460, the DC output 450, and the DC input 470 are not shown.

[0044] When the elevator drive unit 200 is implemented using the example frequency converter 240 of Figure 4, the control steps 330 discussed above may include control by the control unit 250 of the elevator drive unit 200, i.e., causing the rectifier bridge 410 to limit the regenerative power supply from the DC link 420 to the power motor 230 to a power limit by controlling the power switching device 480a of the rectifier bridge 410, and the control unit 250 of the elevator drive unit 200 to control the motor current of the motor bridge 430 to limit the regenerative power supply from the elevator hoisting motor 210 to the DC link 420 by increasing the power loss of the elevator hoisting motor 210. This means that the limited power grid power (P) mains ) corresponds to regeneration power (P) reg Subtract 210 (P) from the elevator hoisting motor lm The power loss caused by ) and the internal power loss of the motor bridge (P) lmb) and the internal power loss of the rectifier bridge (P lrb In other words, the power output of a constrained power grid can be defined by the following equation:

[0045] P mains = P reg – P lm – P lmb – P lrb (1)

[0046] The elevator drive system 120 may also include an additional brake chopper circuit, which can be used to dissipate additional regenerative power that the elevator drive system 100 does not handle as described above, for example, due to overheating issues of the elevator hoisting motor 210. The elevator drive system 120 may also include other loads or power consumption, such as energy storage devices (e.g., batteries, supercapacitors, etc.).

[0047] Figure 5An example of components of the control unit 250 of the elevator drive unit 200 is schematically shown. The control unit 250 may include a processing unit 510 containing one or more processors, a storage unit 520 containing one or more memories, a communication interface unit 530 containing one or more communication devices, and possibly a user interface (UI) unit 540. The aforementioned components may be communicatively connected to each other, for example, via an internal bus. The storage unit 520 may store and maintain portions of a computer program (code) 525 and any other data. The computer program 525 may include instructions that, when executed by the processing unit 510 of the control unit 250 of the elevator drive unit 200, cause the processing unit 510, and thus the control unit 250, to perform desired tasks, such as one or more of the aforementioned method steps and / or the operation of the control unit 250 of the elevator drive unit 200. Therefore, the processing unit 510 may be configured to access the storage unit 520 and retrieve and store any information therefrom. For clarity, "processor" here refers to any unit suitable for processing information and controlling the operation of the control unit 250 of the elevator drive unit 200, as well as other tasks. These operations can also be implemented using a microcontroller solution with embedded software. Similarly, storage unit 520 is not limited to a specific type of memory, but any type of memory suitable for storing the described information segments can be applied in the context of this invention. Communication interface unit 530 provides one or more communication interfaces for communicating with any other unit, such as frequency converter 240, elevator control unit 110, and / or any other unit. User interface unit 540 may include one or more input / output (I / O) devices, such as buttons, keyboard, touch screen, microphone, speaker, display, etc., for receiving user input and output information. Computer program 525 may be a computer program product, which may be contained in a tangible, non-volatile (non-transitory) computer-readable medium carrying computer program code 525 implemented therein for use with a computer, namely the control unit 250 of elevator drive unit 200.

[0048] Figure 6Examples of components of an elevator control unit 110 are schematically shown. The elevator control unit 110 may include a processing unit 610 containing one or more processors, a storage unit 620 containing one or more memories, a communication interface unit 630 containing one or more communication devices, and possibly a user interface (UI) unit 640. The aforementioned components may be communicatively connected to each other, for example, via an internal bus. The storage unit 620 may store and maintain portions of a computer program (code) 625 and any other data. The computer program 625 may include instructions that, when executed by the processing unit 610 of the elevator control unit 110, cause the processing unit 610, and thus the elevator control unit 110, to perform desired tasks, such as one or more of the aforementioned method steps and / or the aforementioned operations of the elevator control unit 110. Therefore, the processing unit 610 may be configured to access the storage unit 620 and retrieve and store any information in the storage unit 620. For clarity, the term "processor" here refers to any unit suitable for processing information and controlling the operation of the elevator control unit 110 and other tasks. These operations may also be implemented using a microcontroller solution with embedded software. Similarly, storage unit 620 is not limited to a specific type of memory, but any type of memory suitable for storing the described information fragments can be applied in the context of this application. Communication interface unit 630 provides one or more communication interfaces for communicating with any other unit, such as elevator drive unit 200, control unit 250 of elevator drive unit 200, and / or any other unit. User interface unit 640 may include one or more input / output (I / O) devices, such as buttons, keyboards, touchscreens, microphones, speakers, displays, etc., for receiving user input and output information. Computer program 625 may be a computer program product, which may be contained in a tangible, non-volatile (non-transitory) computer-readable medium carrying embedded computer program code 625 for use with a computer (i.e., elevator control unit 110).

[0049] The specific examples provided in the description above should not be construed as limiting the applicability and / or interpretation of the appended claims. Unless otherwise expressly stated, the list and groups of examples provided in the description above are not exhaustive.

Claims

1. An elevator drive unit (200) for managing the regenerative power of an elevator system (100), the elevator drive unit (200) comprising: The first terminal (220a) is used to connect the elevator drive unit (200) to the power grid (230); The second terminal (220b) is used to connect the elevator drive unit (200) to the elevator hoisting motor (210); A frequency converter (240) is used to enable bidirectional power transfer between the power grid (230) and the elevator hoisting motor (210); and Control unit (250), configured as follows: An indication is obtained representing one of the various special operating conditions detected in the elevator system (100). Introducing a non-zero power limit for a specific operating condition of the detected elevator system (100), and The frequency converter (240) is controlled to limit the regenerative power supply from the elevator hoisting motor (210) to the power grid (230) to a power limit.

2. The elevator drive unit (200) according to claim 1, wherein, The control unit (250) is configured to control the frequency converter (240) to control the motor current, thereby increasing the power loss of the elevator hoisting motor (210).

3. The elevator drive unit (200) according to claim 2, wherein, The control unit (250) is configured to introduce harmonics into the motor current to increase the power loss of the elevator hoisting motor (210).

4. The elevator drive unit (200) according to any one of the preceding claims, wherein, The control unit (250) is configured to control the frequency converter (240) to control the elevator hoisting motor (210) to increase the power loss of the elevator hoisting motor (210).

5. The elevator drive unit (200) according to claim 4, wherein, The control unit (250) is configured to control the frequency converter (240) to control the elevator hoisting motor (210) to operate in a weak magnetic mode, thereby increasing the power loss of the elevator hoisting motor (210).

6. The elevator drive unit (200) according to claim 2, wherein, The power loss of the elevator hoisting motor (210) includes the core loss and / or resistance loss in the elevator hoisting motor (210).

7. The elevator drive unit (200) according to any one of claims 1 to 3, wherein, The control unit (250) is configured to control the frequency converter (240) to increase the power loss of the frequency converter (240).

8. The elevator drive unit (200) according to any one of claims 1 to 3, wherein, Several special operating conditions of the elevator system (100) include situations where it is necessary to reduce the regenerative power supplied from the elevator hoisting motor (210) to the power grid (230).

9. The elevator drive unit (200) according to any one of claims 1 to 3, wherein, The elevator system (100) has several special operating conditions, including power grid outage, power grid shortage, backup power supply, braking of the elevator car (102) of the elevator system (100), overheating of elevator components, and / or smart grid conditions.

10. The elevator drive unit (200) according to any one of claims 1 to 3, comprising a power switching device (480a, 480b) arranged as a frequency converter (240), wherein a control unit (250) is connected to the control pole of the power switching device (480a, 480b).

11. The elevator drive unit (200) according to any one of claims 1 to 3, wherein, The frequency converter (240) includes: A rectifier bridge (410) formed by a power switching device (480a) includes an AC input (440) and a DC output (450) connected to a first terminal (220a); and The motor bridge (430) is formed by the power switching device (480b), and the motor bridge (430) includes an AC output (460) connected to the second terminal (220b) and a DC input (470) connected to the DC output (450) of the rectifier bridge (410) via the DC link (420). The control unit (250) is connected to the control terminals of the power switching devices (480a, 480b) of the rectifier bridge (410) and the motor bridge (430), and The control unit (250) is configured to: The rectifier bridge (410) is controlled by a power switching device (480a) to limit the supply of regenerative power from the DC link (420) to the power grid (230) to a power limit. The motor bridge (430) controls the motor current, thereby limiting the regenerative power supply from the elevator hoist motor (210) to the DC link (420) by increasing the power loss of the elevator hoist motor (210).

12. An elevator system (100), comprising: Elevator control unit (110), An elevator car (102) is configured to travel along an elevator shaft (104) between multiple floors (106a-106n). The elevator hoisting motor (210) used to drive the elevator car (102), and The elevator drive unit (200) according to any one of the preceding claims, wherein the elevator control unit (110) is communicatively connected to the elevator drive unit (200).

13. The elevator system (100) according to claim 12, wherein, The elevator control unit (110) is configured to determine special operating conditions of the elevator system (100).

14. The elevator system (100) according to claim 12 or 13, wherein, The elevator control unit (110) is configured to determine at least one non-zero power limit specific to a particular operating condition.

15. A method for managing the regenerative power of an elevator system (100), the method comprising: The elevator control unit (110) determines (310) at least one non-zero power limit specific to a particular operating condition; A special operating condition in which the elevator control unit (110) detects (320) various special operating conditions of the elevator system (100); and The elevator drive unit (200) limits the regenerative power supply from the elevator hoisting motor (210) to the power grid (230) to the power limit for a specific operating condition of the elevator system (100) being tested.

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