Elevator power regeneration device control method, elevator drive system, and elevator control device

Abstract

To enable effective use of regenerative power while using a small, low-cost power regeneration device. [Solution] An elevator drive system 1 including an inverter 14 that drives a hoisting machine 3 that runs an elevator car and a power regeneration device 10 that is added to the inverter 14 to regenerate regenerative power generated in the hoisting machine 3 to an AC power source 2, comprises a first discrimination unit 18b, a second discrimination unit 18c, and a regeneration control unit 18d. The first discrimination unit 18b discriminates the torque generation direction in the hoisting machine 3 based on a torque command signal. The second discrimination unit 18c discriminates the rotation direction in the hoisting machine 3 based on a rotation speed signal. The regeneration control unit 18d detects that the hoisting machine 3 is in a regenerative state when the torque generation direction and the rotation direction of the hoisting machine 3 are opposite to each other, and activates the power regeneration device 10.

Description

[Technical field]

[0001] The present invention relates to a control method for a power regeneration device added to an inverter that drives a hoist that runs an elevator car, an elevator drive system, and an elevator control device. [Background technology]

[0002] In small to medium capacity elevators (excluding high-speed, large-capacity elevators), when the regenerative state of the hoist that drives the elevator car is detected, the regenerative power generated in the hoist is converted into Joule heat and absorbed by a resistor connected to the DC stage of the inverter that drives the hoist.

[0003] 4 is a diagram showing a configuration example of an elevator drive system 1A that absorbs regenerative power using a resistor 20 connected to the DC stage of the inverter 14. In the elevator drive system 1A, when the hoisting machine 3 enters a regenerative state, the voltage of the DC stage of the inverter 14 increases due to the regenerative power generated in the hoisting machine 3. In the elevator drive system 1A, it is determined whether the hoisting machine 3 is in a regenerative state or in a drive state in which the car is traveling, depending on whether the voltage of the DC stage of the inverter 14 (hereinafter, DC stage voltage) is higher than the rectified voltage of the AC power source 2 by a predetermined value or more.

[0004] The rectified voltage of the AC power source 2 is the output voltage of the converter 12A connected to the AC power source 2. The converter 12A is a power conversion device that converts AC power to DC power. The converter 12A is a rectifier-type power conversion device, specifically a diode rectifier. The DC stage voltage is a voltage that the inverter 14 converts regenerative power from the hoisting machine 3 into DC. In the elevator drive system 1A, when the DC stage voltage drops to a predetermined value after the resistor 20 is connected to the DC stage of the inverter 14, the resistor 20 is disconnected. In the elevator drive system 1A, the regenerative power generated during the elevator travel is absorbed by repeatedly connecting and disconnecting the resistor 20 to the DC stage of the inverter 14.

[0005] In recent years, the demand for energy-saving performance has been increasing against the backdrop of social interest in environmental protection, as represented by the SDGs, and there is a demand for elevators to effectively reuse regenerative power by returning it to the AC power source. One example of a technology for returning regenerative power to the AC power source in elevators is the technology disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-324878 A Summary of the Invention [Problem to be solved by the invention]

[0007] In high-speed, large-capacity elevators that require a large amount of regenerative power, absorbing the regenerative power through resistance would result in excessive heat generation, so traditionally, the regenerative power has been returned to the AC power source using a bidirectional converter that performs bidirectional conversion between AC power and the DC power of the inverter's DC stage.

[0008] FIG. 5 is a diagram showing a configuration example of an elevator drive system 1B including a bidirectional converter 12B. In the elevator drive system 1B, the converter 12B performs power conversion not only during regenerative operation of the elevator but also during driving of the elevator, and supplies power to the DC stage of the inverter 14. For this reason, bidirectional power conversion devices such as the converter 12B are expensive devices that require large AC reactors and harmonic filters, such as PWM (Pulse Width Modulation) current control to shape the AC current output from the AC power source 2 into a sine wave, because they need to handle large power. For this reason, it has been difficult to apply bidirectional power conversion devices to elevators with small and medium capacities.

[0009] The present invention has been made in consideration of the above-described problems, and has an object to provide a technique that enables effective use of regenerative power while using a small, low-cost power regeneration device. [Means for solving the problem]

[0010] In order to solve the above problems, the control method for a power regeneration device of an elevator according to the present invention comprises the steps of: A method for controlling a power regeneration device that is added to an inverter that drives a hoist that runs an elevator car in order to regenerate regenerative power generated in the hoist to an AC power source, comprising: A first determination process for determining a torque generation direction in the hoist based on a torque command signal that controls a rotation speed of the hoist; A second determination process of determining a rotation direction of the hoist based on a rotation speed signal representing a rotation speed of the hoist; A regeneration control process for detecting a regeneration state of the hoisting machine based on the torque generation direction determined in the first determination process and the rotation direction determined in the second determination process, and for operating the power regeneration device, The regenerative control process detects that the hoist is in a regenerative state when the torque generation direction determined in the first discrimination process and the rotation direction determined in the second discrimination process are opposite to each other.

[0011] The regenerative control process detects the regenerative state of the hoist and starts operation of the power regenerative device, and then, when the torque generation direction and the rotation direction become the same, continues operation of the power regenerative device if the magnitude of the torque indicated by the torque command signal is less than or equal to a first predetermined value, and stops the power regenerative device if the magnitude of the torque becomes greater than the first predetermined value.

[0012] The regeneration control process can operate the power regeneration device when the rotation speed indicated by the rotation speed signal is equal to or lower than a second predetermined value.

[0013] The elevator drive system of the present invention further comprises: An inverter that drives the hoist that runs the elevator car; A power regeneration device added to the inverter in order to regenerate regenerative power generated in the hoisting machine to an AC power source; A control device; An elevator drive system comprising: The control device includes: A first determination unit that determines a torque generation direction in the hoist based on a torque command signal that controls a rotation speed of the hoist; A second determination unit that determines a rotation direction of the hoist based on a rotation speed signal that indicates a rotation speed of the hoist; a regeneration control unit that detects a regeneration state of the hoisting machine based on the torque generation direction determined by the first determination unit and the rotation direction determined by the second determination unit, and operates the power regeneration device; The regenerative control unit detects that the hoist is in a regenerative state when the torque generation direction determined by the first discrimination unit and the rotation direction determined by the second discrimination unit are opposite to each other.

[0014] The elevator control device of the present invention comprises: A control device that controls a power regeneration device that is added to an inverter that drives a hoist that runs an elevator car in order to regenerate regenerative power generated in the hoist to an AC power source, A first determination unit that determines a torque generation direction in the hoist based on a torque command signal that controls a rotation speed of the hoist; A second determination unit that determines a rotation direction of the hoist based on a rotation speed signal that indicates a rotation speed of the hoist; a regeneration control unit that detects a regeneration state of the hoisting machine based on the torque generation direction determined by the first determination unit and the rotation direction determined by the second determination unit, and operates the power regeneration device; The regenerative control unit detects that the hoist is in a regenerative state when the torque generation direction determined by the first discrimination unit and the rotation direction determined by the second discrimination unit are opposite to each other. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an elevator drive system including a power regeneration device according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an example of a measured waveform in a power conversion device. [Diagram 3] FIG. 3 is a flowchart showing a process flow in the control method for the power regeneration device. [Figure 4] FIG. 4 is a diagram showing a configuration example of an elevator drive system that uses a resistor to absorb regenerative power. [Diagram 5] FIG. 5 is a diagram illustrating a configuration example of an elevator drive system using a bidirectional power converter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The following embodiments are subject to various technically preferable limitations, but the present invention is not limited to the following embodiments.

[0017] FIG. 1 is a diagram showing an example of the configuration of an elevator drive system 1 according to an embodiment of the present invention. In FIG. 1, the same components as those in FIG. 4 are denoted by the same reference numerals. The configuration of the elevator drive system 1 differs from that of the elevator drive system 1A in that a power regeneration device 10 is provided instead of a resistor 20. Note that in FIG. 1, an encoder 16 and a speed control device 18 are shown as components of the elevator drive system 1 in addition to the power regeneration device 10, converter 12A, and inverter 14, but the elevator drive system 1A also has an encoder and a speed control device. In FIG. 4, the encoder and the speed control device are merely omitted. The elevator drive system 1B also has an encoder and a speed control device.

[0018] The encoder 16 is, for example, a rotary encoder, and detects the rotation speed of the hoisting machine 3. The encoder 16 outputs a rotation speed signal (speed feedback signal) representing the detected rotation speed to the speed control device 18. In addition to the rotation speed signal, a speed command specifying the rotation speed of the hoisting machine 3 is provided to the speed control device 18. The speed control device 18 generates a torque command signal specifying the output torque of the hoisting machine 3 so that the rotation speed represented by the rotation speed signal follows the rotation speed represented by the speed command, and provides it to the inverter 14. In the elevator drive system 1, the AC power supplied from the AC power source 2 is converted to DC power by rectification by the converter 12A, and is supplied to the DC stage of the inverter 14. The inverter 14 converts the DC power supplied from the converter 12A into AC power in accordance with the torque command signal and supplies it to the hoisting machine 3, thereby controlling the rotation direction, rotation speed, and output torque of the hoisting machine 3.

[0019] The power regeneration device 10 is connected to the AC power source 2 and the DC stage of the inverter 14, similar to the converter 12A. In the elevator drive system 1, regenerative power flowing from the hoist 3 to the DC stage of the inverter 14 is regenerated to the AC power source 2 by the power regeneration device 10 connected to the DC stage of the inverter 14. In this way, the power regeneration device 10 is added to the inverter 14 that obtains a DC stage voltage by a diode rectifier (converter 12A), and is a device that regenerates the regenerative power to the AC power source side. Details will be described later, but according to this embodiment, it is possible to realize highly efficient power regeneration at a low cost.

[0020] Unlike converter 12B, which is a bidirectional power conversion device, power regeneration device 10 does not employ current control using PWM control, and performs power regeneration by switching semiconductor elements every 60 degrees of electrical angle of AC power source 2 so that regenerative current from the DC stage of inverter 14 flows to the phase with the largest line voltage of AC power source 2. In a mode in which power regeneration is performed by switching semiconductor elements every 60 degrees of electrical angle of AC power source 2, switching loss of the semiconductor elements is negligible because PWM control is not performed, and heat loss of the semiconductor elements can be significantly reduced, thereby enabling the power regeneration device 10 to be made smaller.

[0021] Although detailed illustration is omitted in Fig. 1, an AC reactor for suppressing the peak value of the regenerative current is provided between the AC power source 2 and the power regeneration device 10. The voltage applied to the AC reactor during power regeneration is the difference voltage between the DC stage voltage of the inverter 14 and a voltage near the peak value of the line voltage of the AC power source 2, and remains a relatively small applied voltage. For this reason, the inductance value of the AC reactor may be small, and the size of the AC reactor body can also be reduced.

[0022] For these reasons, the power regeneration device 10 is smaller in size and cheaper in price than conventional bidirectional power conversion devices.

[0023] In the conventional bidirectional power conversion device, the regenerative state is detected when the DC stage voltage of the inverter 14 becomes higher than the rectified voltage of the AC power source 2 by a predetermined value or more, as in the above-mentioned absorption of regenerative power by the resistor 20, and the regenerative operation is started. However, in the regenerative state detection method based on the DC stage voltage of the inverter 14 and the rectified voltage of the AC power source 2, the voltage difference between the power source voltage and the DC stage voltage at the start of the regenerative operation is large, and an inrush current occurs when the power regenerative device starts to operate. FIG. 2 is an actual measurement waveform diagram showing the occurrence of an inrush current at the start of the operation of the power regenerative device. Since the semiconductor element used in the power regenerative device needs to have a tolerance against this inrush current, the semiconductor element needs to be selected with a margin, which becomes an obstacle to miniaturization and cost reduction of the device.

[0024] If the above-mentioned predetermined value is set small, the inrush current will be small, but a false detection of the regenerative state will occur due to a temporary drop in the power supply voltage or a distortion in the voltage waveform. In that case, as described below, the operation of the power regenerative device will continue until the elevator operation ends. It is difficult to set the above-mentioned predetermined value to a sufficiently small value to avoid such false detection. In order to suppress the inrush current in a situation where the voltage difference between the power supply voltage and the DC stage voltage at the start of regenerative operation is large, the inductance value of the AC reactor installed between the AC power supply 2 and the power regenerative device 10 should be increased, but this will result in an increase in the size of the reactor.

[0025] In addition, once the power regenerative device starts regenerative operation, the DC stage voltage is fixed near the rectified voltage of the AC power supply, so the end of the regenerative state cannot be detected based on the DC stage voltage. As a result, if the regenerative state is detected at some point after the elevator starts operating and the power regenerative device starts operating, the power regenerative device will continue to operate until the elevator stops operating, even if it returns to a driving state after that.

[0026] As a method for determining whether the elevator continues to regenerate after the power regeneration device starts operating or has returned to a driving state, it is possible to stop the operation of the power regeneration device every certain time to check the state. However, if the operation of the power regeneration device is stopped every certain time, an inrush current will be generated every time the device restarts operation while the regeneration state continues, and there is a concern that this will cause deterioration of semiconductor elements that are being made smaller.

[0027] For the above reasons, when a power regeneration device, which is smaller than a bidirectional power conversion device, is applied to an elevator, it has been common to adopt a configuration in which the power regeneration device is operated at all times during elevator operation, regardless of whether the elevator is in drive or regeneration mode. However, in this operating method, the power regeneration device is operated even during elevator drive operation, when the power regeneration device can be stopped, resulting in a state in which a part of the power supplied from the AC power source 2 to the DC stage of the inverter 14 via the converter 12A is returned to the AC power source by the power regeneration device 10. This leads to an increase in the circulating current between the power regeneration device 10 and the inverter 14, which causes unnecessary power consumption in the semiconductor conversion part within the device, and is an obstacle to miniaturization of the power regeneration device.

[0028] In order to solve the above problems, this embodiment employs a configuration in which the regenerative state of the hoisting machine 3 is detected based on a torque command signal and a rotation speed signal, and the speed control device 18 executes control to stop the power regenerative device 10 during drive operation, while also starting the operation of the power regenerative device 10 while preventing the occurrence of inrush current even during regenerative operation. In other words, the speed control device 18 also serves as a control device that controls the operation of the power regenerative device 10. Of the components of the elevator drive system 1, the power regenerative device 10, the converter 12A, the inverter 14, and the encoder 16 are not particularly different from those in conventional elevator drive systems, so detailed explanations will be omitted and the following description will focus on the speed control device 18.

[0029] The speed control device 18 is, for example, a PLC (Programmable Logic Controller). The speed control device 18 operates according to a control program PR1 installed in advance, thereby functioning as a speed control unit 18a, a first discrimination unit 18b, a second discrimination unit 18c, and a regeneration control unit 18d. That is, each of the speed control unit 18a, the first discrimination unit 18b, the second discrimination unit 18c, and the regeneration control unit 18d shown in FIG. 1 is a software module realized by operating a computer such as a PLC according to the control program PR1. The functions of each of the speed control unit 18a, the first discrimination unit 18b, the second discrimination unit 18c, and the regeneration control unit 18d are as follows.

[0030] The speed control unit 18a generates a torque command signal so that the speed feedback follows the speed command. The first discrimination unit 18b discriminates the torque generation direction in the hoist 3 based on the torque command signal generated by the speed control unit 18a. The second discrimination unit 18c discriminates the rotation direction in the hoist 3 based on the rotation speed signal provided by the encoder 16. The regeneration control unit 18d detects the regenerative state of the hoist 3 based on the torque generation direction discriminated by the first discrimination unit 18b and the rotation direction discriminated by the second discrimination unit 18c, and operates the power regeneration device 10. In this embodiment, the regeneration control unit 18d detects that the hoist 3 is in a regenerative state when the torque generation direction discriminated by the first discrimination unit 18b and the rotation direction discriminated by the second discrimination unit 18c are opposite to each other.

[0031] Moreover, the speed control device 18 operating according to the control program PR1 generates a torque command signal so as to make the speed feedback follow the speed command, and repeatedly executes a regenerative control method whose processing flow is shown in the flowchart of Fig. 3, for example, at a period of several msec. As shown in Fig. 3, this regenerative control method includes a first discrimination process SA110, a second discrimination process SA120, and a regenerative control process SA130.

[0032] In the first discrimination process SA110, the speed control device 18 functions as a first discrimination unit 18b. In the first discrimination process SA110, the speed control device 18 discriminates the torque generation direction in the hoist 3 based on the torque command signal generated by the speed control unit 18a. In the second discrimination process SA120, the speed control device 18 functions as a second discrimination unit 18c. In the second discrimination process SA120, the speed control device 18 discriminates the rotation direction in the hoist 3 based on the rotation speed signal provided from the encoder 16. In this embodiment, the second discrimination process SA120 is executed following the first discrimination process SA110, but the second discrimination process SA120 may be executed prior to the first discrimination process SA110.

[0033] In the regeneration control process SA130, the speed control device 18 functions as a regeneration control unit 18d. In the regeneration control process SA130, the speed control device 18 detects the regeneration state of the hoisting machine 3 based on the torque generation direction determined in the first discrimination process SA110 and the rotation direction determined in the second discrimination process SA120, and operates the power regeneration device 10. More specifically, in the regeneration control process SA130, the speed control device 18 detects that the hoisting machine 3 is in a regenerative state when the torque generation direction determined in the first discrimination process SA110 and the rotation direction determined in the second discrimination process SA120 are opposite to each other.

[0034] In this embodiment, the reason for detecting the regenerative state of the hoist 3 based on the torque command signal and the rotation speed signal is as follows. The inverter 14 controls the torque generated by the hoist 3 in response to the torque command signal. This torque control is performed by so-called vector control, and the accuracy of the torque control is sufficiently high. Specifically, the control response delay is very small, less than a few msec. Therefore, no particular problem occurs even if the magnitude and direction of the actual torque generated by the hoist 3 are determined based on the torque command signal. In addition, the rotation speed of the hoist 3 can be obtained with high accuracy with a time delay of less than a few msec by processing the rotation speed signal output from the encoder 16 in the speed control device 18.

[0035] According to this embodiment, since it is possible to detect that the hoisting machine 3 is in a regenerative state at the time when the hoisting machine 3 starts generating regenerative power, the power regenerative device 10 can be operated before the DC stage voltage of the inverter 14 starts to rise. Since the DC stage voltage at the start of this operation is at approximately the same level as the rectified voltage of the AC power source 2, the occurrence of an inrush current is prevented in advance. Also, even if the hoisting machine 3 ends the regenerative state and transitions to a driving state during elevator operation, the torque direction of the hoisting machine 3 determined from the torque command signal is reversed, so that the power regenerative device 10 can be stopped without delay. Therefore, according to this embodiment, an increase in the circulating current between the inverter 14 and the power regenerative device 10 can be avoided.

[0036] In the speed control device 18, the torque command signal includes "fluctuations" due to the speed control, and when the torque command signal continues to run near zero, the power regenerative device 10 frequently starts and stops its operation due to the influence of this "fluctuation," which disrupts the current waveform of the AC power source 2. Therefore, even if the direction of the torque generated by the hoist 3, which is determined from the torque command signal, matches the rotation direction of the hoist 3 after the power regenerative device 10 starts operating, the regenerative control unit 18d may continue to operate the power regenerative device 10 until the level of the torque command signal exceeds a first predetermined value in the same direction as the rotation direction of the hoist 3. As a result, when the torque command signal continues to run near zero, the operation of the power regenerative device 10 continues only during light load driving, and adverse effects on the AC power source 2 side are avoided. In this case, the generation of circulating current flowing between the inverter 14 and the power regenerative device 10 is suppressed to a small amount due to the light load.

[0037] When the elevator starts or lands on the floor, the rotation direction of the hoisting machine 3 may be reversed for a short time. The phenomenon of the rotation direction of the hoisting machine 3 being reversed for a short time is caused by a deviation in the starting compensation torque or a transient response of the speed control. As described above, due to the phenomenon of the rotation direction of the hoisting machine 3 being reversed for a short time, starting and stopping the power regeneration device 10 in a short time may disturb the current waveform of the AC power source 2. Therefore, during low-speed operation in which the rotation speed of the hoisting machine 3 is equal to or lower than the second predetermined value, the regeneration control unit 18d may continue the operation of the power regeneration device 10 regardless of whether the hoisting machine 3 is in a driving state or a regenerative state. This suppresses disturbance of the current waveform of the AC power source 2 and stabilizes the AC current. Note that, during low-speed operation, both the driving power and the regenerative power of the elevator are small, and the generation of circulating current is slight.

[0038] As described above, according to this embodiment, unnecessary operation of the power regeneration device 10 added to the inverter 14 included in the elevator drive system 1 that controls the drive of the elevator is eliminated when driving the elevator, and the occurrence of inrush current when the power regeneration device 10 starts operating is avoided. This makes it possible to suppress the temperature rise of the semiconductor elements in the power regeneration device 10 and reduce the current burden, making it possible to reduce the size and cost of the power regeneration device 10. This makes it possible to reduce the size and cost of the entire elevator drive system 1 including the power regeneration device 10.

[0039] The above description is for the purpose of explaining the present invention, and should not be interpreted as limiting the invention described in the claims or restricting the scope. In addition, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

[0040] The above-described embodiment may be modified as follows.

[0041] For example, in the above embodiment, the control program PR1 is pre-installed in the speed control device 18, but the control program PR1 may be manufactured or sold separately. Specific modes of providing the control program PR1 when the control program PR1 is manufactured or sold separately include a mode in which the control program PR1 is written to a computer-readable recording medium such as a flash ROM (Read Only Memory) and distributed, or a mode in which the control program PR1 is distributed by downloading via a telecommunications line such as the Internet. By rewriting the control program of the speed control device in an existing elevator drive system with the control program PR1 distributed in these modes, it becomes possible to operate the existing elevator drive system as the elevator drive system of the present invention.

[0042] In addition, the speed control unit 18a, the first discrimination unit 18b, the second discrimination unit 18c, and the regenerative control unit 18d in the above embodiment are all software modules. However, any one or more of the speed control unit 18a, the first discrimination unit 18b, the second discrimination unit 18c, and the regenerative control unit 18d may be hardware modules such as ASICs, or all of them may be hardware modules. Even if any one or more of the speed control unit 18a, the first discrimination unit 18b, the second discrimination unit 18c, and the regenerative control unit 18d, or all of them are hardware modules, the same effects as those of the above embodiment are achieved.

[0043] In the above embodiment, the speed control device 18 also serves as a control device that controls the operation of the power regeneration device 10. However, a control device that controls the operation of the power regeneration device 10 may be provided separately from the speed control device that controls the rotational speed of the hoist 3. In this case, the control device may include a first discrimination unit 18b, a second discrimination unit 18c, and a regeneration control unit 18d, and may execute the control method shown in Fig. 3. This control device may also be manufactured and sold separately. [Explanation of symbols]

[0044] 1 Elevator drive system 2 AC power supply 3 Hoisting machine 10 Power regeneration device 12A Converter 14 Inverter 16 Encoders 18 Speed ​​control device 18a Speed ​​control section 18b 1st discrimination part 18c 2nd discrimination part 18d Regenerative control unit PR1 control program

Claims

1. A control method for an elevator drive system that receives AC power from an AC power source and controls a hoist that runs a car, comprising: The elevator drive system includes: a converter for converting AC power from the AC power source into DC power; an inverter that converts DC power supplied from the converter into AC power and supplies the AC power to the hoist; a power regeneration device connected between the inverter and the AC power source, The control method includes: a first determination process for determining a torque generation direction in the hoist based on a torque command signal for controlling a rotation speed of the hoist; A second determination process of determining a rotation direction of the hoist based on a rotation speed signal representing a rotation speed of the hoist; a regeneration control process for detecting a regeneration state of the hoisting machine based on the torque generation direction determined in the first determination process and the rotation direction determined in the second determination process, and for operating the power regeneration device, In the regenerative control process, when the torque generation direction determined in the first determination process and the rotation direction determined in the second determination process are opposite to each other, it is detected that the hoist is in a regenerative state, During low-speed operation in which the rotational speed indicated by the rotational speed signal is equal to or lower than a second predetermined value, regardless of whether the hoisting machine is in a regenerative state or not, the power regeneration device is operated to return a portion of the power supplied from the AC power source via the converter to the inverter as a circulating current by the power regeneration device again to the AC power source; During operation in which the rotation speed indicated by the rotation speed signal is higher than a second predetermined value, when the hoisting machine is in a regenerative state, the power regeneration device is operated so as to regenerate regenerative power generated in the hoisting machine to the AC power supply. A control method for an elevator drive system added to an inverter that drives the hoisting machine.

2. The regeneration control process detects the regeneration state of the hoist and starts the operation of the power regeneration device, and then, when the torque generation direction and the rotation direction become the same, continues the operation of the power regeneration device if the magnitude of the torque indicated by the torque command signal is equal to or smaller than a first predetermined value, and stops the power regeneration device if the magnitude of the torque becomes greater than the first predetermined value.

2. The method for controlling an elevator drive system according to claim 1.

3. An elevator drive system for a hoist that receives AC power from an AC power source to run a car, a converter for converting AC power from the AC power source into DC power; an inverter that converts DC power supplied from the converter into AC power and supplies the AC power to the hoist; a power regeneration device connected between the inverter and the AC power source; A control device; An elevator drive system comprising: The control device includes: A first determination unit that determines a torque generation direction in the hoist based on a torque command signal that controls a rotation speed of the hoist; A second determination unit that determines a rotation direction of the hoist based on a rotation speed signal that indicates a rotation speed of the hoist; a regeneration control unit that detects a regeneration state of the hoisting machine based on the torque generation direction determined by the first determination unit and the rotation direction determined by the second determination unit, and operates the power regeneration device; The regeneration control unit detects that the hoist is in a regenerative state when a torque generation direction determined by the first determination unit and a rotation direction determined by the second determination unit are opposite to each other, During low-speed operation in which the rotational speed indicated by the rotational speed signal is equal to or lower than a second predetermined value, regardless of whether the hoisting machine is in a regenerative state or not, the power regeneration device is operated to return a portion of the power supplied from the AC power source via the converter to the inverter as a circulating current by the power regeneration device again to the AC power source; During operation in which the rotation speed indicated by the rotation speed signal is higher than a second predetermined value, when the hoisting machine is in a regenerative state, the power regeneration device is operated so as to regenerate regenerative power generated in the hoisting machine to the AC power supply. Elevator drive system.

4. A control device for an elevator drive system that receives AC power from an AC power source and controls a hoist that runs a car, The elevator drive system includes: a converter for converting AC power from the AC power source into DC power; an inverter that converts DC power supplied from the converter into AC power and supplies the AC power to the hoist; a power regeneration device connected between the inverter and the AC power source; The control device, The control device includes: A first determination unit that determines a torque generation direction in the hoist based on a torque command signal that controls a rotation speed of the hoist; A second determination unit that determines a rotation direction of the hoist based on a rotation speed signal that indicates a rotation speed of the hoist; a regeneration control unit that detects a regeneration state of the hoisting machine based on the torque generation direction determined by the first determination unit and the rotation direction determined by the second determination unit, and operates the power regeneration device; The regeneration control unit detects that the hoist is in a regenerative state when a torque generation direction determined by the first determination unit and a rotation direction determined by the second determination unit are opposite to each other, During low-speed operation in which the rotational speed indicated by the rotational speed signal is equal to or lower than a second predetermined value, regardless of whether the hoisting machine is in a regenerative state or not, the power regeneration device is operated to return a portion of the power supplied from the AC power source via the converter to the inverter as a circulating current by the power regeneration device again to the AC power source; During operation in which the rotation speed indicated by the rotation speed signal is higher than a second predetermined value, when the hoisting machine is in a regenerative state, the power regeneration device is operated so as to regenerate regenerative power generated in the hoisting machine to the AC power supply. Elevator control device.

Images