Control device for elevators

Abstract

A control device for an elevator is provided, the elevator having a three-phase motor as its traction machine and the three-phase motor being powered by a drive circuit. The control device includes: a capacitor circuit for increasing the braking torque of the three-phase motor by connecting the terminals of the three-phase motor when all terminals of the three-phase motor are connected to them; and a switching device for switching the first and second phase terminals of the three-phase motor between the drive circuit and the capacitor circuit, wherein the third phase terminal of the three-phase motor is fixedly connected to the capacitor circuit.

Description

Technical Field

[0001] This disclosure relates to a control device for an elevator. Background Technology

[0002] In some elevator usage scenarios, slippage may occur, such as when the elevator brake fails to fully engage the traction sheave, or when the brake is manually released during a rescue attempt. Currently, the common method to control elevator slippage speed is to equip the elevator traction machine with a star-connector. However, when the number of magnets in the traction machine is relatively small, the elevator slippage speed may exceed the specified range. Therefore, it has been proposed to limit the elevator slippage speed by configuring a remote brake operation (RBO) system or replacing the traction machine with one that has a larger number of magnets, but both of these methods come at a high economic cost. Summary of the Invention

[0003] In view of the above, this disclosure provides a control device for an elevator, wherein the elevator uses a three-phase motor as its traction machine and the three-phase motor is powered by a drive circuit. The control device includes a capacitor circuit and a switching device. The capacitor circuit is used to connect all phase terminals of the three-phase motor when connected to all phase terminals of the three-phase motor, thereby increasing the braking torque of the three-phase motor. The switching device is used to switch the first and second phase terminals of the three-phase motor between the drive circuit and the capacitor circuit. The third phase terminal of the three-phase motor is fixedly connected to the capacitor circuit.

[0004] In conjunction with aspects of this disclosure, the control device also includes a feedback device. This feedback device is used to generate an indication signal when the first and second phase terminals of the three-phase motor are switched to a capacitor circuit.

[0005] In conjunction with aspects of this disclosure, the switching circuit includes a first switch group and a second switch group. The first switch group is used to switch the first phase terminal of the three-phase motor between the drive circuit and the capacitor circuit. The second switch group is used to switch the second phase terminal of the three-phase motor between the drive circuit and the capacitor circuit. The first and second switch groups are linked.

[0006] In conjunction with aspects of this disclosure, the feedback device includes an indicator switch group for generating an indication signal. The indicator switch group is linked with a first switch group and a second switch group.

[0007] In conjunction with aspects of this disclosure, the first switch group includes a first single-pole double-throw switch. The first single-pole double-throw switch includes a moving contact and two stationary contacts. The moving contact is connected to a first phase terminal of the three-phase motor, and the two stationary contacts are respectively connected to corresponding phase terminals of the capacitor circuit and the drive circuit. The second switch group includes a second single-pole double-throw switch. The second single-pole double-throw switch includes a moving contact and two stationary contacts. The moving contact is connected to a second phase terminal of the three-phase motor, and the two stationary contacts are respectively connected to corresponding phase terminals of the capacitor circuit and the drive circuit.

[0008] In conjunction with aspects of this disclosure, the first switch group includes a first switch and a second switch. The first switch is connected between a first phase terminal of the three-phase motor and a corresponding phase terminal of the drive circuit. The second switch is connected between a first phase terminal of the three-phase motor and a corresponding phase terminal of the capacitor circuit.

[0009] In conjunction with aspects of this disclosure, the second switch group includes a third switch and a fourth switch. The third switch is connected between the second phase terminal of the three-phase motor and the corresponding phase terminal of the drive circuit. The fourth switch is connected between the second phase terminal of the three-phase motor and the corresponding phase terminal of the capacitor circuit.

[0010] In conjunction with aspects of this disclosure, the indicating switch group includes a switch connected to an auxiliary power source and linked with the first switch group and the second switch group. The auxiliary power source is either independent of or associated with the three-phase AC power source in the drive circuit.

[0011] In conjunction with aspects of this disclosure, the indicating switch group includes two switches. These two switches are connected to an additional power supply and are respectively linked to both the first switch group and the second switch group. Furthermore, the two switches are mutually exclusive.

[0012] In conjunction with aspects of this disclosure, the control device also includes a coil. The coil is connected to an additional power supply, and the first switch group, the second switch group, and the indicator switch group all switch in response to the energization and de-energization of the coil.

[0013] In conjunction with aspects of this disclosure, the capacitor circuit includes capacitors connected in a star or delta configuration.

[0014] The control device for elevators provided according to this disclosure can increase the braking torque of a three-phase motor to control the elevator's gliding speed within a specified range, and can save costs by switching only two of the three-phase terminals of the three-phase motor. Attached Figure Description

[0015] The aspects, features, and advantages of this disclosure will become clearer and more readily understood from the following description of embodiments of this disclosure in conjunction with the accompanying drawings, wherein:

[0016] Figure 1 A schematic diagram illustrating the control of elevator tread speed according to the prior art;

[0017] Figure 2 A schematic structural diagram of a control device for an elevator according to an embodiment of the present disclosure is shown.

[0018] Figure 3A Show Figure 1 The equivalent circuit of the braking circuit formed in the middle;

[0019] Figure 3B Show Figure 2 The equivalent circuit of the braking circuit formed in the middle;

[0020] Figure 4 Show Figure 1 The braking circuit formed in the middle and Figure 2 A comparison of the braking torque generated by the braking circuit formed in the middle; and

[0021] Figure 5 A schematic structural diagram of a control device for an elevator according to another embodiment of the present disclosure is shown. Detailed Implementation

[0022] The present disclosure will now be described in detail with reference to exemplary embodiments thereof. However, the present disclosure is not limited to the embodiments described herein, which may be implemented in many different forms. The described embodiments are provided only to make the present disclosure thorough and complete, and to fully convey the concept of the present disclosure to those skilled in the art. Features of the various embodiments described may be combined with or substituted for each other, unless expressly excluded or should be excluded based on the context.

[0023] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components.

[0024] In the accompanying drawings, the same reference numerals denote the same or similar structural or functional components, and repeated descriptions of them will be omitted in the following description.

[0025] Figure 1 A schematic diagram illustrating the control of elevator sliding speed according to the prior art is shown.

[0026] Reference Figure 1The three-phase motor M acts as the elevator's traction machine, driving the traction sheave 20 to rotate when energized. The elevator car 40 and counterweight 50 are suspended from both ends of the traction sheave 20 by traction ropes. The mass of the counterweight 50 is less than the mass of the car 40, for example, half the mass of the car 40. The brake 30 mainly includes components such as an electromagnet, brake shoes, and a handbrake (not shown in the figure). When the electromagnet is energized, the brake shoes release the traction sheave 20, allowing it to be driven and rotated by the three-phase motor M. When the electromagnet is de-energized, the brake shoes engage the traction sheave 20, preventing it from rotating. The handbrake of the brake 30 is used to release the brake shoes from the traction sheave 20 when manually pulled down. The drive circuit 10 supplies power to the three-phase motor M and may include components such as a three-phase AC power supply 101, a main contactor 102, and a frequency converter 103. When the drive circuit 10 stops supplying power to the three-phase motor M, the sealing contactor 60 short-circuits each phase terminal of the three-phase motor M.

[0027] Due to wear and aging, the brake 30 may fail to engage the traction sheave 20, causing it to fail to stop rotating and resulting in a slippage. Alternatively, in rescue situations, such as when the elevator is stuck between two floors due to a malfunction, manually pulling the handbrake on brake 30 can release the traction sheave 20, causing a slippage. During a slippage, the unbalanced torque generated by the mass difference between the car 40 and the counterweight 50 causes the car 40 to descend, the traction sheave 20 to rotate, and the three-phase motor M to be forcibly rotated, causing it to operate as a generator and generate an induced voltage E. At this time, the sealing contactor 60 short-circuits the terminals D1, D2, and D3 of the three-phase motor M, and the braking circuit formed between the three-phase motor M and the sealing contactor 60 generates braking torque to counteract the unbalanced torque generated by the mass difference between the car 40 and the counterweight 50.

[0028] When the amount of magnets used in the three-phase motor M, which serves as the elevator traction machine, is relatively small, the braking torque generated by the braking circuit formed between the three-phase motor M and the sealing contactor 60 may be insufficient to counteract the unbalanced torque, causing the elevator's sliding speed to exceed the specified range under certain load configurations.

[0029] The control device for elevators proposed in this disclosure can serve as an alternative to the star-type contactor 60. While keeping the three-phase motor M unchanged, it increases the braking torque to counteract unbalanced torque, thereby limiting the elevator's speed within a specified range. Furthermore, the control device proposed in this disclosure only requires changing the connection of two terminals of the three-phase motor M, unlike the star-type contactor 60 which requires changing the connection of all three terminals of the three-phase motor M. Therefore, a cheaper two-terminal contactor or other simpler electrical components can be used to construct the braking circuit, saving costs.

[0030] Figure 2 A schematic structural diagram of a control device for an elevator according to an embodiment of the present disclosure is shown.

[0031] Reference Figure 2 According to an embodiment of this disclosure, the control device 70 includes a capacitor circuit 701 and a switching device 702. The capacitor circuit 701 is used to connect all phase terminals of the three-phase motor M when all phase terminals D1, D2, and D3 of the three-phase motor M are connected, thereby increasing the braking torque of the three-phase motor M. The switching device 702 is used to switch the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M between the drive circuit 10 and the capacitor circuit 701. Furthermore, the third phase terminal D3 of the three-phase motor M is fixedly connected to the capacitor circuit 701.

[0032] The working principle of control device 70 is explained below.

[0033] like Figure 2 As shown, the three-phase terminals of the drive circuit 10 are respectively called the u-phase terminal, w-phase terminal and v-phase terminal, which are used to provide three-phase current to the three-phase motor M when connected to the first phase terminal D1, the second phase terminal D2 and the third phase terminal D3 of the three-phase motor M respectively.

[0034] Capacitor circuit 701 includes capacitors C1, C2, and C3 connected, for example, in a star connection, delta connection, or other manner, such as in Figure 2 and will be described in detail below Figure 5 The diagram shows two connection methods: star connection and delta connection. Terminals T1, T2, and T3 of capacitor circuit 701 are used to connect to the first phase terminal D1, the second phase terminal D2, and the third phase terminal D3 of the three-phase motor M, respectively. Terminal T3 is fixedly connected to the third phase terminal D3 of the three-phase motor M.

[0035] The switching device 702 includes a first switch group G1 and a second switch group G2. The first switch group G1 is used to switch the first phase terminal D1 of the three-phase motor M between the u-phase terminal of the drive circuit 10 and the T1 terminal of the capacitor circuit 701. The second switch group G2 is used to switch the second phase terminal D2 of the three-phase motor M between the w-phase terminal of the drive circuit 10 and the T2 terminal of the capacitor circuit 701. The first switch group G1 and the second switch group G2 are linked, that is, they perform the switching action simultaneously.

[0036] The third phase terminal D3 of the three-phase motor M is also connected to the v phase terminal of the drive circuit 10.

[0037] Thus, when the elevator needs to start running, the first switch group G1 in the switching device 702 switches the first phase terminal D1 of the three-phase motor M to the u-phase terminal of the drive circuit 10, while the second switch group G2 switches the second phase terminal D2 to the w-phase terminal of the drive circuit 10, so that all phase terminals D1, D2, and D3 of the three-phase motor M are connected to the drive circuit 10. The drive circuit 10 provides three-phase current to the three-phase motor M to drive it to rotate at a certain speed (e.g., the rated speed), thereby driving the traction sheave 20 to rotate, thus realizing the operation of the elevator. At this time, although the third phase terminal D3 of the three-phase motor M is still connected to the T3 terminal of the capacitor circuit 701, since the remaining T1 and T2 terminals of the capacitor circuit 701 are not connected, a circuit is not formed, and no effect is produced. At this time, the electromagnet in the brake 30 is energized, and the brake shoe releases the traction sheave 20.

[0038] When the elevator needs to stop, the first switch group G1 in the switching device 702 switches the first phase terminal D1 of the three-phase motor M to the T1 terminal of the capacitor circuit 701, while the second switch group G2 switches the second phase terminal D2 of the three-phase motor M to the T2 terminal of the capacitor circuit 701. This connects all phase terminals D1, D2, and D3 of the three-phase motor M to the capacitor circuit 701, thus forming a braking circuit. At this time, although the third phase terminal D3 of the three-phase motor M is still connected to the v-phase terminal of the drive circuit 10, it is not connected to the remaining u-phase and w-phase terminals of the drive circuit 10, so no circuit is formed and no effect is produced. At this time, the electromagnet in the brake 30 is de-energized. If the brake shoe in the brake 30 can hold the traction sheave 20, the traction sheave will not rotate, and the three-phase motor M will also stop rotating due to the disconnection from the drive circuit 10, thus stopping the elevator.

[0039] However, if the brake shoes in brake 30 fail to hold the traction sheave 20 due to aging, wear, or other reasons, causing the elevator to slip, the three-phase motor M will be forced to rotate under the action of the unbalanced torque attributable to the mass difference between the car 40 and the counterweight 50, and its speed will gradually increase due to inertia. At this time, the three-phase motor M operates as a generator, and the induced voltage E generated inside it causes current to flow through the braking circuit, thereby generating braking torque to counteract the unbalanced torque.

[0040] Compared to Figure 1 Compared to the braking circuit consisting of a sealing contactor 60 and a three-phase motor M, the braking circuit consisting of a capacitor circuit 701 in the control device 70 according to an embodiment of the present disclosure and the three-phase motor M can increase the braking torque of the three-phase motor M. The following is in conjunction with... Figure 3A , Figure 3B and Figure 4 Let me describe this.

[0041] Figure 3A Show Figure 1 The braking circuit formed in the middle. Figure 3B Show Figure 2 The braking circuit formed in the middle. Figure 4 Show Figure 1 The braking circuit formed in the middle and Figure 2 A comparison of the braking torque generated by the braking circuit formed in the middle.

[0042] Reference Figure 3A According to existing technology, the braking circuit consisting of a sealing contactor 60 and a three-phase motor M includes the resistances R1, R2, and R3 of each phase winding and the inductances L1, L2, and L3 of each phase winding within the three-phase motor M, as well as the induced voltage E generated by the rotation of the three-phase motor M. For this braking circuit, the braking torque exhibits a characteristic of first increasing and then decreasing with the increase of the rotational speed of the three-phase motor M, such as... Figure 4 As shown in curve 2, this is because as the speed of the three-phase motor M increases, the induced voltage E it generates increases, the current flowing through the braking circuit increases, and the resulting braking torque also increases. However, since the inductive reactance of the inductor in the three-phase motor M also increases with the increase of speed, the ratio of inductive reactance to resistance in the braking circuit also increases with the increase of speed. This causes the current in the braking circuit to lag behind the induced voltage E by 90°, resulting in a decrease in braking torque after a certain speed of the three-phase motor M.

[0043] Figure 4 Curve 1 in the diagram represents the unbalanced torque caused by the mass difference between the car 40 and the counterweight 50. For example... Figure 4As shown, due to the relatively small amount of magnets used in the three-phase motor M, the peak value of the braking torque in the braking circuit shown in curve 2 may be less than the unbalanced torque. Since the braking torque of this braking circuit is always less than the unbalanced torque, the speed of the three-phase motor M cannot be controlled, and it rotates faster and faster, making it impossible to limit the elevator's gliding speed within the specified range.

[0044] Reference Figure 3B According to an embodiment of this disclosure, the braking circuit composed of a capacitor circuit 701 and a three-phase motor M includes, in addition to the internal phase winding resistances R1, R2, and R3 and the internal phase winding inductances L1, L2, and L3 of the three-phase motor M, and the voltage E formed by the induced voltage generated by the rotation of the three-phase motor M, each of the capacitors C1, C2, and C3 in the capacitor circuit 701. For this braking circuit, the characteristic of its braking torque variation also exhibits a characteristic of first increasing and then decreasing as the rotational speed of the three-phase motor M increases, such as... Figure 4 As shown in curve 3, the principle is the same as described above and will not be repeated. However, unlike curve 2, the peak braking torque in curve 3 can reach the unbalanced torque. This is because, as... Figure 3B As shown, capacitors C1, C2, and C3 are connected in series with inductors L1, L2, and L3, respectively. The capacitive reactance of capacitors C1, C2, and C3 cancels out the inductive reactance of inductors L1, L2, and L3, thus improving the situation where the current in the braking circuit lags behind the induced voltage E. The braking torque of this braking circuit is at the resonant frequency. The braking torque reaches its peak value at (L is the inductive reactance in the braking circuit, and C is the capacitive reactance in the braking circuit). By selecting appropriate capacitors C1, C2, and C3, the braking torque can be made to reach an unbalanced torque, thereby causing the three-phase motor M to rotate at a constant speed, and the elevator's sliding speed will no longer increase.

[0045] Therefore, the control device 70 for elevators according to the present disclosure can increase the braking torque of the three-phase motor M without changing it, so that the braking torque is sufficient to counteract the unbalanced torque caused by the mass difference between the car 40 and the counterweight 50, thereby limiting the speed of the elevator to a specified range.

[0046] The capacitor circuit 701 in the control device 70 can be implemented in various ways. For example, Figure 2 The capacitor circuit 701 shown includes three capacitors connected in a star configuration. A star connection means that one end of the three capacitors is connected together, while the other ends serve as terminals T1, T2, and T3 of the capacitor circuit 701, respectively. For example, Figure 5The diagram shows a capacitor circuit 701 comprising three capacitors connected in a delta configuration. A delta connection refers to connecting the three capacitors end-to-end, with the three connection points serving as terminals T1, T2, and T3 of the capacitor circuit 701, respectively. In addition, the capacitor circuit 701 can also be configured in various ways, such as including multiple capacitors connected in series or parallel per phase, or including a capacitor and an inductor connected in series per phase, etc., which will not be exhaustive here.

[0047] The switching device 702 in the control device 70 can also be implemented in various ways. Figure 2 China and the following will be described in detail below Figure 5 Two implementations of the switching device 702 are shown, but this does not mean that these are the only two implementations. In addition, other implementations that can achieve the aforementioned functions of the switching device 702 are also possible.

[0048] One implementation of the switching device 702 is as follows: Figure 2 As shown, the first switch group G1 includes a first single-pole double-throw switch S1, and the second switch group G2 includes a second single-pole double-throw switch S2. The first single-pole double-throw switch S1 includes one moving contact and two stationary contacts. The moving contact is connected to the first phase terminal D1 of the three-phase motor M, and the two stationary contacts are respectively connected to the corresponding phase terminal (i.e., terminal T1) of the capacitor circuit 701 and the corresponding phase terminal (i.e., phase u) of the drive circuit. The second single-pole double-throw switch S2 also includes one moving contact and two stationary contacts. The moving contact is connected to the second phase terminal D2 of the three-phase motor M, and the two stationary contacts are respectively connected to the corresponding phase terminal (i.e., terminal T2) of the capacitor circuit 701 and the corresponding phase terminal (i.e., phase w) of the drive circuit. The first single-pole double-throw switch S1 and the second single-pole double-throw switch S2 are linked, meaning they perform switching actions simultaneously.

[0049] In this implementation, when the elevator needs to start, the moving contact of the first single-pole double-throw switch S1 switches to the stationary contact connected to the u-phase terminal of the drive circuit, thereby switching the first phase terminal D1 of the three-phase motor M to the u-phase terminal of the drive circuit 10. Simultaneously, the moving contact of the second single-pole double-throw switch S2 switches to the stationary contact connected to the w-phase terminal of the drive circuit, thereby switching the second phase terminal D2 of the three-phase motor M to the w-phase terminal of the drive circuit 10. Thus, all phase terminals D1, D2, and D3 of the three-phase motor M are connected to the drive circuit 10 and disconnected from the capacitor circuit 701. The drive circuit 10 provides three-phase current to the three-phase motor M, which drives the traction sheave 20 to rotate at a certain speed (e.g., rated speed), and the elevator starts operating.

[0050] Conversely, when the elevator needs to stop, the moving contact of the first single-pole double-throw switch S1 switches to the stationary contact connected to terminal T1 of capacitor circuit 701, thereby switching the first phase terminal D1 of the three-phase motor M to terminal T1 of capacitor circuit 701. Simultaneously, the moving contact of the second single-pole double-throw switch S2 switches to the stationary contact connected to terminal T2 of capacitor circuit 701, thereby switching the second phase terminal D2 of the three-phase motor M to terminal T2 of capacitor circuit 701. Thus, all phase terminals D1, D2, and D3 of the three-phase motor M are connected to capacitor circuit 701 to form a braking circuit and disconnected from drive circuit 10. When the brake pads can hold the traction sheave 20, the braking circuit is inactive due to the lack of current flow; when the brake pads cannot hold the traction sheave 20 or the handbrake is manually pulled to release the traction sheave 20, causing the elevator to slip, the braking circuit generates braking torque to limit the elevator's speed.

[0051] Another implementation of the switching device 702 is, as follows: Figure 5 As shown, the first switch group G1 includes a first switch S11 and a second switch S12, and the second switch group G2 includes a third switch S21 and a fourth switch S22. The first switch S11 is connected between the first phase terminal D1 of the three-phase motor M and the corresponding phase terminal (i.e., the u-phase terminal) of the drive circuit 10. The second switch S12 is connected between the first phase terminal D1 of the three-phase motor M and the corresponding phase terminal (i.e., the T1 terminal) of the capacitor circuit 701. The third switch S21 is connected between the second phase terminal D2 of the three-phase motor M and the corresponding phase terminal (i.e., the w-phase terminal) of the drive circuit 10. The fourth switch S22 is connected between the second phase terminal D2 of the three-phase motor M and the corresponding phase terminal (i.e., the T2 terminal) of the capacitor circuit 701. Furthermore, the first switch S11, the second switch S12, the third switch S21, and the fourth switch S22 are linked, meaning they perform switching actions simultaneously.

[0052] In this alternative implementation, when the elevator needs to start, the first switch S11 closes to connect the first phase terminal D1 of the three-phase motor M to the u-phase terminal of the drive circuit 10, and the second switch S12 opens to disconnect the first phase terminal D1 of the three-phase motor M from the T1 terminal of the capacitor circuit 701. Simultaneously, the third switch S21 closes to connect the second phase terminal D2 of the three-phase motor M to the w-phase terminal of the drive circuit 10, and the fourth switch S22 opens to disconnect the second phase terminal D2 of the three-phase motor M from the T2 terminal of the capacitor circuit 701. Thus, each phase terminal D1, D2, and D3 of the three-phase motor M is connected to the drive circuit 10 and disconnected from the capacitor circuit 701. The drive circuit 10 provides three-phase current to the three-phase motor M, driving the traction sheave 20 to rotate at a certain speed (e.g., rated speed), and the elevator starts operating.

[0053] Conversely, when the elevator needs to be stopped, the first switch S11 opens to disconnect the first phase terminal D1 of the three-phase motor M from the u-phase terminal of the drive circuit 10, and the second switch S12 closes to connect the first phase terminal D1 of the three-phase motor M to the T1 terminal of the capacitor circuit 701. Simultaneously, the third switch S21 opens to disconnect the second phase terminal D2 of the three-phase motor M from the w-phase terminal of the drive circuit 10, and the fourth switch S22 closes to connect the second phase terminal D2 of the three-phase motor M to the T2 terminal of the capacitor circuit 701. Thus, each phase terminal D1, D2, and D3 of the three-phase motor M is connected to the capacitor circuit 701 to form a braking circuit and disconnected from the drive circuit 10. When the brake pads can hold the traction sheave 20, the braking circuit is inactive because no current flows; when the brake pads cannot hold the traction sheave 20 or the handbrake is manually pulled to release the traction sheave 20, causing the elevator to slip, the braking circuit generates braking torque to limit the elevator's slip speed.

[0054] In the above two embodiments or other embodiments, the first switch group G1 and the second switch group G2 of the switching device 702 can also be implemented using contactors. However, compared with... Figure 1 Unlike the sealing contactor 60 shown, in this embodiment, the third phase terminal D3 of the three-phase motor M is fixedly connected to the capacitor circuit 701. Only the first phase terminal D1 and the second phase terminal D2 of the three phase terminals need to be switched. Therefore, a two-terminal contactor can be used to implement the first switching group G1 and the second switching group G2. Since a two-terminal contactor is much cheaper than a three-terminal contactor, cost savings can be achieved.

[0055] Figure 5 This is a schematic structural diagram of a control device according to another embodiment of the present disclosure.

[0056] To prevent the elevator's normal operation from being affected by the three-phase motor M being connected to both the drive circuit 10 and the capacitor circuit 701, it is necessary to check whether the switching positions of the first switch group G1 and the second switch group G2 in the switching device 702 are correct before and after the elevator starts. Therefore, according to another embodiment of the present disclosure, the control device 70' adds a feedback device 703 to the control device 70 described above.

[0057] Feedback device 703 generates an indication signal when the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M are switched to the capacitor circuit 701. For example, before the elevator starts running, the indication signal can be used to determine whether each phase terminal of the three-phase motor M is connected to the capacitor circuit 701 and disconnected from the drive circuit 10, thus determining whether the elevator can start running. After the elevator starts running, the disappearance of the indication signal can be used to determine whether each phase terminal of the three-phase motor M is connected to the drive circuit 10 and disconnected from the capacitor circuit 701, thus determining whether the elevator has been started correctly.

[0058] The indication signal can have various forms of expression, such as visual, auditory, or other easily perceptible forms. For example, the illumination and extinguishing states of the light-emitting element or the sound-emitting element can be used to indicate whether the first phase terminal D1 and the second phase terminal D2 have been switched to the capacitor circuit 701.

[0059] The feedback device 703 can be implemented in various ways. For example, the feedback device 703 can include an indicator switch group G3 for generating an indication signal. This indicator switch group G3 is linked to the first switch group G1 and the second switch group G2 in the switching device 702, that is, they switch simultaneously. When the first switch group G1 and the second switch group G2 switch to switch the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M to the T1 and T2 terminals of the capacitor circuit, respectively, the indicator switch group G3 also switches, thereby generating an indication signal.

[0060] The indicator switch group G3 can be implemented in various ways. For example, Figure 5 The diagram shows two implementations of the indicator switch group G3, but this does not mean that these are the only two implementations; other methods that can achieve equivalent functions are also possible.

[0061] One implementation of the indicator switch group G3 is as follows: Figure 5 As shown, this includes a fifth switch S31. The fifth switch S31 is linked with the first switch group G1 (shown as the first switch S11 and the second switch S12 in the figure) and the second switch group G2 (e.g., shown as the third switch S21 and the fourth switch S22 in the figure) (i.e., they perform switching actions simultaneously, such as...). Figure 5(As shown by the dashed line), and the fifth switch S31 is connected to an auxiliary power supply 80. This auxiliary power supply 80 can be a power supply independent of the three-phase AC power supply 101 in the drive circuit 10, or a power supply associated with the three-phase AC power supply 101 in the drive circuit 10 (e.g., a power supply derived from it). For example, a light-emitting element LE1 can be connected in series in the circuit of the fifth switch S31. The light-emitting element LE1 illuminates in response to the closing of the fifth switch S31 and extinguishes in response to the opening of the fifth switch S31.

[0062] In this embodiment, the feedback device 703 generates an indication signal, i.e., the light-emitting element LE1 is turned off, when the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M are switched to the capacitor circuit 701. Thus, before the elevator starts running, by checking that the light-emitting element LE1 is off, it is determined that the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M have been switched to the capacitor circuit 701, thereby determining that the elevator can start running. When the elevator starts running, the first switch S11, the second switch S12, the third switch S21, the fourth switch S22, and the fifth switch S31 simultaneously perform switching operations. After the elevator starts running, by detecting that the light-emitting element LE1 is lit, it is determined that the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M have been switched to the u-phase terminal and w-phase terminal of the drive circuit 10, respectively, thereby determining that the elevator has been correctly started running.

[0063] Another implementation of the indicator switch group G3 includes a sixth switch S32 in addition to the fifth switch S31 as described above. The sixth switch S32 is linked with the first switch group G1, the second switch group G2, and the fifth switch S31 (i.e., they perform switching actions simultaneously, such as...). Figure 5 (As shown by the dashed line), and the sixth switch S32 is mutually exclusive with the fifth switch S31 (i.e., its open or closed state is opposite to that of the fifth switch S32). The sixth switch S32 is connected to the auxiliary power supply 80. A light-emitting element LE2 can also be connected in series in the circuit of the sixth switch S32. The light-emitting element LE2 is in the light-emitting state in response to the closing of the sixth switch S32, and in the extinguished state in response to the opening of the sixth switch S32.

[0064] In this alternative embodiment, the feedback device 703 generates an indication signal when the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M are switched to the capacitor circuit 701, i.e., the light-emitting element LE1 is off and the light-emitting element LE2 is lit. Thus, before the elevator starts running, by detecting that the light-emitting element LE1 is off and the light-emitting element LE2 is lit, it is determined that the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M have been switched to the capacitor circuit 701, thereby determining that the elevator can be started. During elevator startup, the first switch S11, the second switch S12, the third switch S21, the fourth switch S22, the fifth switch S31, and the sixth switch S32 simultaneously perform switching operations. After the elevator starts running, by detecting that the light-emitting element LE1 is lit and the light-emitting element LE2 is off, it is determined that the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M have been switched to the u-phase terminal and w-phase terminal of the drive circuit 10, respectively, thereby determining that the elevator has been correctly started.

[0065] Thus, by using the feedback device 703, the connection between each phase terminal of the three-phase motor M and the capacitor circuit can be checked before and after the elevator starts running, ensuring the normal operation of the elevator.

[0066] The linkage between the first switch group G1, the second switch group G2, and the indicator switch group G3 can be implemented in various ways. Figure 5 The diagram shows how this linkage can be achieved via coil A1, but it is not intended to be limiting; other ways to achieve the equivalent function are also possible.

[0067] Reference Figure 5Coil A1 is also powered by auxiliary power supply 80. Each switch in the first switch group G1, the second switch group G2, and the indicating switch group G3 is mechanically or electrically associated with coil A1, so that these switches perform switching actions in response to the energization and de-energization of coil A1. Thus, before the elevator starts running, coil A1 is not powered by auxiliary power supply 80 (the power supply from auxiliary power supply 80 to coil A1 can be controlled by the elevator control cabinet). In switching device 702, the first switch S11 and the third switch S21 are in the open state, the second switch S12 and the fourth switch S22 are in the closed state, the fifth switch S31 in feedback device 703 is in the open state, and the sixth switch S32 is in the closed state. At this time, it is determined that the elevator can be started by checking that the light-emitting element LE1 is off and the light-emitting element LE2 is lit. Then, the auxiliary power supply 80 supplies power to coil A1, causing the first switch S11 and the third switch S21 in the switching device 702 to close, and the second switch S12 and the fourth switch S22 to open. Simultaneously, the fifth switch S31 in the feedback device 703 closes, and the sixth switch S32 opens, thus starting the elevator. Then, it is confirmed that the elevator has been correctly started by checking that the light-emitting element LE1 is lit and the light-emitting element LE2 is off.

[0068] The control devices 70 and 70' for elevators described above, according to embodiments of the present disclosure, compensate for the inductive effect of the three-phase motor M by adding a capacitor of a certain size to each phase of the braking circuit of the three-phase motor M. This ensures that the braking torque generated by the braking circuit is sufficient to counteract the unbalanced torque caused by the mass difference between the car 40 and the counterweight 50, thereby controlling the elevator's gliding speed within a specified range. Furthermore, the control devices 70 and 70', through the feedback device 703, can check the connection positions of each phase terminal of the three-phase motor M before and after elevator startup to ensure that the elevator is started correctly. In addition, the control devices 70 and 70' fix the third phase terminal D3 of the three-phase motor M to the capacitor circuit 701, so that only the first phase terminal D1 and the second phase terminal D2 of the three-phase motor M need to be switched, which saves costs compared to the three-terminal star-connected contactor 60 used in the prior art.

[0069] The block diagrams of circuits, devices, apparatuses, equipment, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that connections, arrangements, or configurations must be made in the manner shown in the block diagrams. As those skilled in the art will recognize, these circuits, devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner that achieves the desired purpose.

[0070] Those skilled in the art should understand that the specific embodiments described above are merely examples and not limitations. Various modifications, combinations, partial combinations, and substitutions can be made to the embodiments of this disclosure according to design requirements and other factors, as long as they are within the scope of the appended claims or their equivalents, and thus fall within the scope of the rights to be protected by this disclosure.

Claims

1. A control device for an elevator, the elevator having a three-phase motor as its traction machine and the three-phase motor being powered by a drive circuit, the control device comprising: A capacitor circuit is used to connect the terminals of the three-phase motor when all terminals of the three-phase motor are connected, thereby increasing the braking torque of the three-phase motor. as well as A switching device is used to switch the first phase terminal and the second phase terminal of the three-phase motor between the drive circuit and the capacitor circuit. The third phase terminal of the three-phase motor is fixedly connected to the capacitor circuit, and the third phase terminal is also connected to the drive circuit. When the elevator needs to be started, the switching device simultaneously switches the first phase terminal and the second phase terminal of the three-phase motor to the drive circuit, so that the first phase terminal, the second phase terminal and the third phase terminal are all connected to the drive circuit; When the elevator needs to stop running, the switching device simultaneously switches the first phase terminal and the second phase terminal of the three-phase motor to the capacitor circuit, so that the first phase terminal, the second phase terminal and the third phase terminal are all connected to the capacitor circuit, thereby forming a braking circuit; The switching of the first phase terminal and the second phase terminal of the three-phase motor is linked.

2. The control device according to claim 1, further comprising: A feedback device is used to generate an indication signal when the first and second phase terminals of the three-phase motor are switched to the capacitor circuit.

3. The control device according to claim 2, wherein the switching device comprises: The first switching group is used to switch the first phase terminal of the three-phase motor between the drive circuit and the capacitor circuit; and The second switching group is used to switch the second phase terminal of the three-phase motor between the drive circuit and the capacitor circuit. The first switch group and the second switch group are linked.

4. The control device according to claim 3, wherein the feedback device comprises: Indicator switch group, used to generate indicator signals, The indicator switch group is linked with the first switch group and the second switch group.

5. The control device according to claim 3, wherein: The first switch group includes a first single-pole double-throw switch, which includes a moving contact and two stationary contacts. The moving contact is connected to the first phase terminal of the three-phase motor, and the two stationary contacts are respectively connected to the corresponding phase terminal of the capacitor circuit and the corresponding phase terminal of the drive circuit. The second switch group includes a second single-pole double-throw switch, which includes a moving contact and two stationary contacts. The moving contact is connected to the second phase terminal of the three-phase motor, and the two stationary contacts are respectively connected to the corresponding phase terminal of the capacitor circuit and the corresponding phase terminal of the drive circuit.

6. The control device according to claim 3, wherein: The first switch group includes a first switch and a second switch. The first switch is connected between the first phase terminal of the three-phase motor and the corresponding phase terminal of the drive circuit, and the second switch is connected between the first phase terminal of the three-phase motor and the corresponding phase terminal of the capacitor circuit. The second switch group includes a third switch and a fourth switch. The third switch is connected between the second phase terminal of the three-phase motor and the corresponding phase terminal of the drive circuit, and the fourth switch is connected between the second phase terminal of the three-phase motor and the corresponding phase terminal of the capacitor circuit.

7. The control device according to claim 4, wherein: The indicator switch group includes a switch connected to an additional power source and is linked to the first switch group and the second switch group. The additional power supply is either independent of or connected to the three-phase AC power supply in the drive circuit.

8. The control device according to claim 4, wherein: The indicator switch group includes two switches, each connected to an auxiliary power source and linked to both the first switch group and the second switch group, respectively. Furthermore, the two switches are mutually exclusive. The additional power supply is either independent of or connected to the three-phase AC power supply in the drive circuit.

9. The control device according to claim 4, further comprising: A coil, connected to an additional power source, wherein the first switch group, the second switch group, and the indicating switch group all switch in response to the energization and de-energization of the coil. The additional power supply is either independent of or connected to the three-phase AC power supply in the drive circuit.

10. The control device according to claim 1, wherein: The capacitor circuit includes capacitors connected in a star or delta configuration.

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