A method for detecting a star-encircled loop

Abstract

The application discloses a star closing loop detection method. In the elevator brake releasing and speed controllable operation, the flag for allowing star closing detection is made according to the load information of the elevator or the current, voltage, power or torque information output by the frequency converter. When the frequency converter receives the stop output instruction and allows the star closing detection, the frequency converter performs electronic star closing to form the freewheeling path between the frequency converter and the elevator main machine. In the case that the elevator main machine is in the freewheeling state based on the freewheeling path, the elevator control system controls the star closing contactor to perform star closing on the elevator main machine. The change of the freewheeling current of the star closing loop before and after the star closing action of the star closing contactor is determined to obtain the star closing loop detection result. The application can avoid the missed detection and false detection of the traditional detection method, and can reliably and accurately determine the effectiveness of the star closing loop.

Description

Technical Field

[0001] This invention relates to the field of elevator testing technology, and more specifically, to a method for testing a star-sealed circuit. Background technology:

[0002] With the development of elevator technology, the safety requirements for elevators are becoming increasingly stringent. In order to ensure that the elevator can effectively slow down or limit its speed, the three-phase input of the motor is usually shorted, and the braking force generated by the permanent magnet of the permanent magnet synchronous motor (PM motor) is used to slow down or limit the speed of the elevator (i.e., "star-sealing technology").

[0003] Currently, the commonly used method for sealing off elevator control systems is to use a "sealed-off contactor". A normally closed sealed-off contactor is added between the frequency converter and the motor to achieve short-circuiting of the three-phase input of the motor.

[0004] Elevator control systems typically detect the star-sealing function through the auxiliary contacts of the star-sealing contactor. However, when only the star-sealing contactor is being detected, if it is damaged and not replaced for various reasons, or if the wiring is altered to connect the operating signals of other contactors to the detection port, then that monitoring point is not actually detecting the operation of the star-sealing contactor. Alternatively, if the U, V, or W lines or jumper wires connected to the main contacts of the star-sealing contactor are removed or the wiring is interrupted, although the contactor may operate, the actual star-sealing function will not be present.

[0005] The elevator sealing contactor detection method and device disclosed in Chinese invention patent application publication number CN114415007A proposes to release the brake (i.e., open the holding brake) when the elevator stops, allowing the elevator to roll away. Whether the speed or acceleration exceeds a preset value within a preset time is used to determine whether the sealing function is qualified. However, this method requires releasing the brake (i.e., releasing the holding brake) to allow the elevator to roll away, which poses certain risks. It also requires determining whether there are people in the car, and obtaining the preset time and preset speed is relatively complex.

[0006] Furthermore, Chinese invention patent application publication number CN114715749A discloses an automatic detection method, system, device, and storage medium for elevator star-sealing function. This automatic detection method is applied to the elevator control system. When a star-sealing function detection command is detected, it acquires the elevator's target service floor information. After controlling the elevator car to run to the target floor corresponding to the target service floor information, the star-sealing module is activated, allowing the elevator car to enter a gliding state. The gliding speed or gliding distance of the elevator car in this gliding state is acquired, and based on the gliding speed or gliding distance, it is determined whether the elevator star-sealing function meets preset requirements. This method also requires releasing the brake (i.e., releasing the brake, opening the holding brake) for gliding, which poses a certain risk. Additionally, the detection time is relatively long, affecting passenger access to the elevator.

[0007] In addition, Chinese invention patent application publication number CN115231404A discloses a method, device, elevator control system, and storage medium for detecting a star-sealing circuit. The method is applied to an elevator control system, which controls and detects the star-sealing circuit. When the elevator is stationary, the elevator control system controls the inverter to turn on the power supply circuit between the power supply and the elevator host, inputting a detection current to the elevator host. When the detection current reaches a preset value, the elevator control system controls the inverter to turn off the power supply circuit between the power supply and the elevator host, forming a freewheeling path between the inverter and the elevator host. With the elevator host in a freewheeling state based on this freewheeling path, the elevator control system controls the star-sealing contactor to star-seale the elevator host. The elevator control system determines the star-sealing circuit detection result based on the change in the freewheeling current of the star-sealing circuit before and after the star-sealing contactor's action. This method reliably and accurately determines the validity of the star-sealing circuit by completely simulating the current effect of the star-sealing circuit before and after the contactor's action, using a non-destructive method. However, this method requires an ON-OFF star-sealing contactor when inputting the detection current, which affects the contactor's lifespan and increases noise during contactor operation. Summary of the Invention:

[0008] To address the above problems, the purpose of this invention is to provide a method for detecting the star-sealing circuit, which avoids the omissions and false positives of traditional detection methods, thereby reliably and accurately determining the validity of the star-sealing circuit and improving elevator safety performance. This invention integrates the detection of the star-sealing circuit into the normal stopping sequence, thus not affecting passenger elevator use, the lifespan of the star-sealing contactor, or increasing noise.

[0009] To achieve the above-mentioned objective, the present invention provides a method for detecting a sealing loop, which is applied to an elevator control system. The sealing loop includes a frequency converter, a sealing contactor, and an elevator main unit, wherein the frequency converter is connected to the elevator main unit equipped with the sealing contactor; the sealing loop detection method includes:

[0010] During elevator operation with brake release and controllable speed, a flag indicating that the star-sealing detection is allowed is made based on the elevator's load information or the current, voltage, power, or torque information output by the frequency converter.

[0011] When the frequency converter receives a stop output command and allows the star-sealing detection, the frequency converter performs electronic star-sealing to form a continuous flow path between the frequency converter and the elevator host.

[0012] When the elevator main unit is in a continuous flow state based on the continuous flow path, the elevator control system controls the sealing contactor to seal the elevator main unit.

[0013] The elevator control system determines the detection result of the sealing circuit based on the change in the freewheeling current of the sealing circuit before and after the sealing action of the sealing contactor.

[0014] In a preferred embodiment of the present invention, the method further includes: detecting the output current of the frequency converter; and, when the detected current reaches a preset current value, creating a flag that allows for satellite-to-station detection.

[0015] In a preferred embodiment of the present invention, the detection results of the satellite sealing loop include normal detection results and abnormal detection results;

[0016] The normal detection result is determined by the following method: if the freewheeling current meets the preset conditions, the elevator control system determines that the detection result of the sealing circuit is a normal detection result; the preset conditions include the value of the freewheeling current returning to zero as the sealing contactor operates.

[0017] The abnormal detection result is determined by the following method: if the freewheeling current does not meet the preset condition, the elevator control system determines that the star-sealing circuit detection result is an abnormal detection result.

[0018] By employing the above technical solution, this invention avoids the missed detections and false detections common in traditional detection methods, thereby reliably and accurately determining the effectiveness of the star-sealing circuit and improving elevator safety performance. This invention integrates the detection of the star-sealing contactor into the normal stop sequence, thus not affecting passenger elevator use, the lifespan of the star-sealing contactor, or increasing noise. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the connection principle between the frequency converter, the sealing contactor, and the motor.

[0020] Figure 2 This is one of the schematic diagrams of the detection process of the star-sealing loop detection method of the present invention.

[0021] Figure 3a to Figure 3c This is a schematic diagram of the current loop formation before stopping in the star-sealing loop detection method of the present invention.

[0022] Figure 4 This is a schematic diagram of the continuous current loop formation in the star-sealing loop detection method of the present invention.

[0023] Figure 5 This is a schematic diagram of the sealing contactor in the sealing circuit detection method of the present invention.

[0024] Figure 6 This is the second schematic diagram of the detection process of the star-sealing loop detection method of the present invention. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] The sealing loop detection method of the present invention is applied to an elevator control system. See [link to relevant documentation]. Figure 1 Its sealing circuit includes a frequency converter, a sealing contactor and an elevator host, with the frequency converter connected to the elevator host equipped with a sealing contactor.

[0027] See Figure 2 The method for detecting the sealed-off loop includes the following steps:

[0028] Step S210: Detect the output current of the frequency converter during elevator operation with brake release and controllable speed;

[0029] Step S220: When the detection current reaches the preset current value, a flag is made to allow the satellite sealing detection;

[0030] Step S230: When the frequency converter receives a stop output command and allows the star-sealing detection, the frequency converter performs electronic star-sealing to form a continuous flow path between the frequency converter and the elevator host.

[0031] Specifically, Chinese invention patent application publication number 114778991A illustrates the waveform of the elevator host's output torque (which is positively correlated with the inverter's output current) at different stages during elevator operation, and its relationship with load percentage, moment of inertia, acceleration, and deceleration. When the inverter receives a stop output command, its current magnitude is basically the same as when starting at zero speed, high-speed constant speed, and stopping at zero speed, and also has a certain relationship with the current magnitude during acceleration and deceleration. In some examples, when the load is 0% and the elevator is descending (i.e., an empty car with no passengers), the elevator host's output current is approximately 75% of the elevator host's rated current. This can also be increased by injecting an excitation current Id, such as to 100% of the elevator host's rated current.

[0032] like Figure 1 The existing "electronic star-blocking" technology can be achieved by blocking (i.e., invalidating, turning off the controllable switches T1, T2, and T3 (such as IGBTs) of the upper bridge arm of the frequency converter, while keeping the drive signals of the controllable switches T4, T5, and T6 (such as IGBTs) of the lower bridge arm always active, or by blocking the drive signals of the controllable switches T4, T5, and T6 (such as IGBTs) of the lower bridge arm of the frequency converter, while keeping the drive signals of the controllable switches T1, T2, and T3 (such as IGBTs) of the upper bridge arm always active.

[0033] Because the drive signal of one arm of the inverter is constantly blocked, it prevents... Figure 1The intermediate bus voltage provides driving energy to the elevator host. Under these conditions, the elevator host cannot generate torque other than that combined with braking; therefore, "electronic star-sealing" is a safe form of electrical braking. During electronic star-sealing, due to the freewheeling effect of the elevator host coil, freewheeling current can be achieved through the freewheeling circuit formed by the elevator host, the inverter's freewheeling diode, and the controllable switch. The freewheeling current in the star-sealing circuit gradually decreases from its initial value.

[0034] In some examples, if the inverter's U-phase current is positive and the V and W-phase currents are negative when the inverter receives a stop output command (the inverter's phase current is positive when flowing towards the elevator host), since the elevator host's voltage is generated by PWM modulation of the bus voltage Ud, the instantaneous current path can be as shown in Figure 3a (through T1, T5, T6) or Figure 3b (T1, D2, T6) or... Figure 3c (T1, D2, D3) or Figure 4 As shown in (D4, T5, T6). When the controllable switches T1, T2, and T3 of the upper bridge arm of the frequency converter are turned off, and the controllable switches T4, T5, and T6 of the lower bridge arm of the frequency converter are turned on, the freewheeling path becomes... Figure 4 As shown.

[0035] The flag for allowing the sealing detection, made by steps S210 and S220, can also be made based on the elevator's load information (weight), or the voltage, power, or torque output by the frequency converter.

[0036] In step S240, when the elevator host is in a continuous flow state based on the continuous flow path, the elevator control system controls the sealing contactor to seal the elevator host.

[0037] Specifically, the elevator main unit relies on the inverter's freewheeling diodes D1, D2, D3, D4, D5, D6 and controllable switching transistors T1, T2, T3, T4, T5, T6 for freewheeling time, which is often only tens to hundreds of milliseconds. During this continuous freewheeling period, the main contact KM2 of the sealing contactor must be closed; otherwise, the test will fail. In addition, the sealing action of the sealing contactor has an error of about 10 milliseconds. Therefore, the electronic sealing of the inverter needs to be coordinated with the elevator control system's control of the sealing contactor to seal the elevator main unit, so that the sealing action of the sealing contactor can be achieved when the elevator main unit is in a freewheeling state.

[0038] In some examples, the elevator control system can control the frequency converter to perform electronic sealing after a time T1 following the sealing action of the sealing contactor driven by the elevator control system. For example, the range of time T1 can be 0ms to 15ms, and a value of 5ms is recommended for T1.

[0039] It should be noted that in step S230, if all switching transistors are turned off, or in Figure 3c When only the upper arm switch is turned off, the bus voltage Ud is introduced into the freewheeling circuit, which greatly shortens the freewheeling time and causes the test to fail.

[0040] Step S250: The elevator control system determines the detection result of the sealing circuit based on the change of the freewheeling current of the sealing circuit before and after the sealing action of the sealing contactor.

[0041] Specifically, after the frequency converter performs electronic sealing, the sealing contactor seals the elevator main unit; the elevator control system determines the sealing circuit result based on the change in the freewheeling current generated by the elevator main unit's coil before and after the sealing contactor's sealing action. For example... Figure 5 As shown, the dashed line represents the freewheeling current after the main contact KM2 of the sealing contactor is closed. (Comparison) Figure 4 and Figure 5 If the star-sealing circuit is normal, after the star-sealing contactor successfully completes the star-sealing action, the freewheeling current no longer flows through the inverter, but only through the elevator host and the star-sealing contactor. The elevator control system can determine the star-sealing circuit detection result based on the change in the freewheeling current of the star-sealing circuit before and after the star-sealing contactor's action. If the change in the freewheeling current before and after the star-sealing action satisfies the above rule, the star-sealing circuit is normal and can achieve effective star-sealing; otherwise, the star-sealing circuit is abnormal and cannot achieve effective star-sealing. The freewheeling current of the star-sealing circuit can include the phase current at the output terminal of the inverter when the elevator host is in a freewheeling state. By detecting the phase current at the output terminal of the inverter, if the star-sealing circuit is effective, the phase current value at the output terminal of the inverter will return to zero with the star-sealing contactor's action; if the star-sealing circuit is ineffective, the phase current value at the output terminal of the inverter will not exhibit this phenomenon. The star-sealing circuit detection result can be determined based on the change in the phase current value at the output terminal of the inverter.

[0042] The above-mentioned satellite sealing circuit test results include normal test results and abnormal test results;

[0043] Normal test results are determined as follows: if the freewheeling current meets the preset conditions, the elevator control system determines that the star-sealing circuit test result is a normal test result; the preset conditions include the value of the freewheeling current returning to zero as the star-sealing contactor operates.

[0044] The abnormal detection result is determined by the following method: if the freewheeling current does not meet the preset condition, the elevator control system determines that the detection result of the sealing circuit is an abnormal detection result.

[0045] Specifically, such as Figure 5 As shown, the dashed line represents the freewheeling current after the main contact KM2 of the sealing contactor is closed. (Comparison) Figure 4 and Figure 5 If the contactor sealing circuit is normal, the freewheeling current at the inverter output terminal is not zero before the contactor sealing action. After the sealing contactor successfully completes the sealing action, the elevator main unit is short-circuited by the three phases of the sealing contactor, causing the freewheeling current to no longer flow through the inverter. The elevator control system can determine the sealing circuit detection result by checking whether the phase current at the inverter output terminal meets the condition that its value suddenly returns to zero with the sealing action of the sealing contactor. If the change in the freewheeling current at the inverter output terminal before and after the sealing action meets the above preset conditions, the sealing circuit is considered normal and effective sealing can be achieved; otherwise, the sealing circuit is abnormal and effective sealing cannot be achieved. It should be noted that if the detected freewheeling current is sufficiently small, it can be considered that the freewheeling current has returned to zero. For example, if the freewheeling current is less than the preset zeroing threshold (the preset zeroing threshold can be close to zero but not zero), the freewheeling current is considered to have returned to zero.

[0046] In some examples, such as Figure 6 As shown, firstly, it is determined whether the elevator is in operation with the brake released and the speed controllable. If it is, the output current of the frequency converter is detected; it is then determined whether the output current reaches the predetermined value A; if the output current reaches the predetermined value A, a flag is set to allow contactor sealing detection; when the frequency converter receives a stop output command, it is determined whether contactor sealing detection is allowed; if the frequency converter receives a stop output command and sealing detection is allowed, the frequency converter performs electronic sealing, driving the sealing contactor to engage (considering that the action time of the sealing contactor is greater than the action time of the frequency converter, in order to ensure the sealing contactor is in the continuous flow path). When operating in freewheeling mode, the sealing contactor can be activated first, followed by electronic sealing; start the timer; determine whether the output current rapidly returns to zero before the timer reaches the predetermined value B. If so, turn off all controllable switches T1, T2, T3, T4, T5, and T6, clear the sealing detection flag, and output a normal sealing contactor function message; if the output current does not rapidly return to zero before the timer reaches the predetermined value B, turn off all controllable switches T1, T2, T3, T4, T5, and T6, clear the sealing detection flag, and output a abnormal sealing contactor function message.

[0047] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these are only examples of one driving phase sequence. In actual control, there can be multiple phase sequences and current forms, and they are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the steps or stages of other steps.

Claims

1. A method for detecting a sealed-loop circuit, applied to an elevator control system, characterized in that, The sealing circuit includes a frequency converter, a sealing contactor, and an elevator main unit, wherein the frequency converter is connected to the elevator main unit equipped with the sealing contactor; the sealing circuit detection method includes: During elevator operation with brake release and controllable speed, a flag indicating that the star-sealing detection is allowed is made based on the elevator's load information or the current, voltage, power, or torque information output by the frequency converter. When the frequency converter receives a stop output command and allows the star-sealing detection, the frequency converter performs electronic star-sealing to form a continuous flow path between the frequency converter and the elevator host. When the elevator main unit is in a continuous flow state based on the continuous flow path, the elevator control system controls the sealing contactor to seal the elevator main unit. The elevator control system determines the detection result of the sealing circuit based on the change in the freewheeling current of the sealing circuit before and after the sealing action of the sealing contactor; The electronic star-blocking includes: blocking the drive signal of the controllable switch of the upper bridge arm of the frequency converter, i.e., turning off the controllable switch, while keeping the drive signal of the controllable switch of the lower bridge arm always effective; or blocking the drive signal of the controllable switch of the lower bridge arm of the frequency converter, while keeping the drive signal of the controllable switch of the upper bridge arm always effective.

2. The method for detecting a sealed-off loop as described in claim 1, characterized in that, include: The output current of the frequency converter is detected; when the detected current reaches a preset current value, a flag is set to allow the satellite detection.

3. The method for detecting a sealed-off loop as described in claim 1, characterized in that, The detection results of the satellite sealing circuit include normal detection results and abnormal detection results; The normal detection result is determined by the following method: if the freewheeling current meets the preset conditions, the elevator control system determines that the sealing circuit detection result is a normal detection result; the preset conditions include the value of the freewheeling current returning to zero as the sealing contactor operates; the abnormal detection result is determined by the following method: if the freewheeling current does not meet the preset conditions, the elevator control system determines that the sealing circuit detection result is an abnormal detection result.

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