Detection method and device for star-sealing contactor for elevator

Abstract

The present invention discloses a method for detecting a closed-star contactor for an elevator. The method comprises placing a current transformer between the closed-star contactor and a permanent magnet synchronous motor. During closed-star slippage, the current transformer is used to detect the three-phase current of the permanent magnet synchronous motor. The detected motor current information is used to determine whether the closed-star contactor is fully closed. When the elevator is unloaded or in standby mode, the method simulates slippage in the event of a brake failure by sliding the vehicle upward. The current information is used to determine whether the closed-star contactor is qualified. This method effectively avoids the problems of ineffective detection or complex detection processes encountered in conventional detection methods. The method is simple and easy to implement and is not affected by encoder failure.

Description

Technical Field

[0001] The present invention relates to the technical field of elevator detection, and in particular to a method and device for detecting a star-sealing contactor for an elevator. Background Art

[0002] With the development of elevator technology, the safety requirements for elevators are becoming increasingly higher. In order to ensure that the elevator can effectively decelerate or limit the elevator's sliding speed, the three-phase input of the motor is usually short-circuited, and the braking force generated by the permanent magnets of the permanent magnet synchronous motor (PM motor) is used to decelerate the elevator or limit the elevator's sliding speed (that is, "star-sealing technology").

[0003] At present, the commonly used star-sealing method in elevator control systems is to use a "star-sealing contactor". A normally closed star-sealing contactor is added between the inverter and the motor to short-circuit the three-phase input of the elevator host.

[0004] Typically, elevator control systems detect the star-sealing function through the auxiliary contacts of the star-sealing contactor. However, if only the star-sealing contactor is detected, and the star-sealing contactor is damaged and not replaced for various reasons or the wiring is manually modified, and the operating signals of other contactors are connected to the detection port, then the monitoring point will not actually detect the operation of the star-sealing contactor. Or if the U, V, or W wire or short-circuit wire connected to the main contact of the star-sealing contactor is removed or the line is interrupted, although the contactor is activated, the star-sealing function does not actually exist.

[0005] Chinese invention patent application publication number CN114415007A discloses a method and device for detecting a grounding contactor for an elevator. This method uses a method to determine if the grounding contactor has passed the test by releasing the brakes (i.e., releasing the brakes and allowing the vehicle to coast) when the elevator is stopped. The method then determines whether the grounding contactor has passed the test by measuring whether the vehicle exceeds a preset speed or acceleration within a preset time. However, obtaining the preset time and speed is complex, and if the encoder fails during detection, the speed or acceleration cannot be determined, posing a risk. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the existing elevator star-sealing contactor detection method, the present invention provides an elevator star-sealing contactor detection method, which simulates the sliding of the elevator when the elevator brake fails by sliding the car upward when the elevator is unloaded and in standby state, and determines whether the star-sealing contactor is qualified based on current information.

[0007] To achieve the above-mentioned object of the invention, the present invention provides a method for detecting a star-closing contactor for an elevator, characterized in that a current transformer is arranged between the star-closing contactor and the permanent magnet synchronous motor, and is used to detect the three-phase current of the permanent magnet synchronous motor during the star-closing and slipping process. By detecting whether there is current during the star-closing and slipping process, it is determined whether the star-closing contactor is completely closed.

[0008] In a preferred embodiment of the present invention, it is determined whether any phase current of the permanent magnet synchronous motor is always zero within a first preset time. If so, it is determined that the star-sealing contactor is abnormal. The electrical frequency or speed of the motor is obtained from the measured motor current within a second preset time, and it is determined whether its electrical frequency or speed is greater than a first preset value. If so, it is determined that the star-sealing contactor is abnormal. If not, it is determined that the star-sealing contactor is normal.

[0009] In a preferred embodiment of the present invention, the star-sealing sliding car is a star-sealing sliding car that simulates the situation of elevator brake failure by sliding upward when the elevator is unloaded and in a standby state.

[0010] In a preferred embodiment of the present invention, the first preset time may be set to 0.5s, and the second preset time is greater than the first preset time, such as 1s.

[0011] Due to the adoption of the above technical solution, the present invention simulates the sliding of the elevator when the brake fails by sliding the car upward, and determines whether the star-sealing contactor is qualified by the current signal, effectively avoiding the problems of ineffective detection or complicated detection process in the common detection method. It is simple and easy to implement and is not affected by encoder failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the electrical principles of a traditional star-sealing contactor, frequency converter, current transformer, and permanent magnet synchronous motor.

[0013] Figure 2 Schematic diagram of the current waveform of the permanent magnet synchronous motor.

[0014] Figure 3 This is a schematic diagram of the electrical principles of the star-sealing contactor, frequency converter, current transformer, and permanent magnet synchronous motor of the present invention. DETAILED DESCRIPTION

[0015] The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0016] See also Figure 1 In the traditional circuit, the current transformers TA1 and TA2 are set in front of the star-sealing contactor, that is, in the U phase and V phase between the star-sealing contactor and the inverter B. It is impossible to judge whether the star-sealing contactor is completely closed by detecting whether there is current when the star-sealing car is slipping.

[0017] See also Figure 3The present invention provides an elevator star-sealing contactor detection device, comprising a frequency converter B, a star-sealing contactor, a permanent magnet synchronous motor PM, current transformers TA1 and TA2, and a detection device (not shown). The star-sealing contactor is directly connected to the output of the frequency converter B, is connected to the permanent magnet synchronous motor via current transformers TA1 and TA2, and is connected to the current transformers TA1 and TA2. The current transformers TA1 and TA2 are arranged in the U phase and the V phase.

[0018] The motor current during the closed-loop phase is detected by current transformers TA1 and TA2, and the fully closed contactor is determined based on the detected motor current information. When the closed-loop contactor is fully closed, current flows through all three phases of the motor. When only two phases of the closed-loop contactor are closed, current flows through only two phases of the motor, with equal magnitude and opposite direction, while the current in the remaining phase is zero. The frequency of the motor current reflects the speed of the permanent magnet synchronous motor. If all three phases or two phases of the closed-loop contactor are disconnected, the current in all three phases is zero.

[0019] The specific detection process is:

[0020] During a first preset time, determine whether any phase current of the permanent magnet synchronous motor remains zero. If so, determine that the star-sealing contactor is abnormal. During a second preset time, determine whether the motor's electrical frequency or speed is greater than a first preset value based on the measured three-phase motor current. If so, determine that the star-sealing contactor is abnormal; if not, determine that the star-sealing contactor is normal. Generally, the first preset time can be set to 0.5s, and the second preset time is greater than the first preset time, such as 2s.

Claims

1. The detection method of the star-sealing contactor for elevator is characterized by: A current transformer is installed between the star-sealing contactor and the permanent magnet synchronous motor. It is used to detect the three-phase current of the permanent magnet synchronous motor during star-sealing and slipping. The motor current information obtained is used to determine whether the star-sealing contactor is fully closed. When the star-sealing contactor is fully closed, all three phases of the motor have current. When only two phases of the star-sealing contactor are closed, only two phases of the motor have current, which is equal in magnitude and opposite in direction, and the current of the other phase is zero. The frequency of the above motor current actually reflects the speed of the permanent magnet synchronous motor. If all three phases of the star-sealing contactor are disconnected or two phases are disconnected, the three-phase current is zero. Determine whether any phase current of the permanent magnet synchronous motor is always zero within a first preset time, and if so, determine that the star-closing contactor is abnormal; Obtaining the electrical frequency or speed of the motor from the measured three-phase motor current within a second preset time, and determining whether the electrical frequency or speed is greater than a first preset value; if so, determining that the star-sealing contactor is abnormal; if not, determining that the star-sealing contactor is normal; The star-sealing sliding car is a sliding car that simulates the star-sealing sliding car under the condition of elevator brake failure by sliding the car upward when the elevator is unloaded and in standby state.

2. The method for detecting a star-sealing contactor for an elevator according to claim 1, wherein: The second preset time is greater than the first preset time.

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