Improved detection method for star contactors for elevators

Abstract

The application discloses an improved detection method for an elevator star contactor, which is applied to an elevator control system and characterized in that a star circuit comprises a frequency converter, a star contactor and an elevator host, the frequency converter is connected to the elevator host which is configured with the star contactor; the detection method for the elevator star contactor comprises the steps that the elevator is in a state of loose brake and coasting, and electronic star and contactor star jointly act, and based on current information fed back by the frequency converter, a detection result of the contactor star circuit is determined. According to the detection method, the electronic star always exists in the coasting state, even if the contactor star circuit is abnormal, the coasting speed is low, the coasting distance is short, and there is no safety risk, and the detection time is short.

Description

Technical Field

[0001] This invention relates to the field of elevator testing technology, and more specifically, to an improved method for testing elevator sealing contactors. 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 elevator host.

[0004] Elevator control systems typically detect the star-sealing function through the auxiliary contacts of the star-sealing contactor. However, if only the star-sealing contactor is being monitored, and it is damaged but not replaced for various reasons, or if the wiring has been altered and the operating signals of other contactors are connected to this monitoring port, then this 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 is not present.

[0005] Chinese invention patent application publication number CN114415007A discloses a method and device for detecting a sealing contactor in elevators. It proposes releasing the brake (i.e., releasing the brake, opening the holding brake) when the elevator stops, allowing it to roll forward. Whether the speed or acceleration exceeds a preset value within a preset time is used to determine if the sealing function is qualified. However, this method suffers from the following problems: if the sealing function fails, the speed or acceleration during brake release (i.e., releasing the brake, opening the holding brake) can be too high, resulting in a long rolling distance, posing a certain risk at the top floor. Furthermore, obtaining the preset time and preset speed is complex, and if the encoder fails during detection, the inability to obtain speed or acceleration can lead to danger.

[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 method is applied to the elevator control system. When a star-sealing function detection command is detected, the system acquires the elevator's target service floor information. After controlling the elevator car to reach 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 system acquires the gliding speed or gliding distance of the elevator car in this gliding state and determines whether the elevator star-sealing function meets preset requirements based on the gliding speed or gliding distance. However, this method also suffers from excessively high speeds or accelerations and long gliding distances when the brake is released due to contactor star-sealing function failure. When the car is at the top floor, it needs to be moved to another target service floor. Considering the need to return the car to the floor before the detection after the star-sealing function detection, the detection time is very long, affecting passenger access. Summary of the Invention

[0007] To address the above problems, the present invention provides an improved method for detecting elevator sealing contactors, addressing the shortcomings of existing methods. This method involves electronically sealing the elevator during normal operation or from a standstill. When a sealing current is detected, the contactor is sealed. Changes in the sealing current determine whether the contactor is functioning correctly. Because the elevator remains electronically sealed throughout the detection process, the risks associated with excessive sliding speed or distance when the contactor sealing function fails are avoided. Furthermore, at the top floor, the elevator can slide downwards, reducing the contactor detection time and ensuring uninterrupted passenger use.

[0008] To achieve the above-mentioned objective, the present invention provides an improved method for detecting a sealing contactor for elevators, which is applied to an elevator control system. The method is characterized in that: the sealing circuit includes a frequency converter, a sealing contactor, and an elevator main unit; the frequency converter is connected to the elevator main unit equipped with the sealing contactor; and the method for detecting the sealing contactor for elevators includes:

[0009] The elevator is in a brake-released, slippery state, with the electronic and contactor star-sealing mechanisms working together. Based on the current feedback from the frequency converter (referred to as star-sealing current), the detection result of the contactor star-sealing circuit is determined.

[0010] In one embodiment, the following steps are included:

[0011] Step S210: Electronic star sealing rollout and detection of star sealing current;

[0012] Step S220: If a sealing current is detected in the electronic sealing chute, the sealing contactor is used to seal the sealing chute.

[0013] Step S230: Determine the detection result of the sealing circuit based on the change of the sealing current before and after the sealing contactor is sealed.

[0014] In a preferred embodiment of the present invention, the detection results of the satellite sealing loop include normal detection results and abnormal detection results;

[0015] The normal detection result is determined as follows: if the sealing current meets the preset conditions, the elevator control system determines that the contactor sealing circuit detection result is a normal detection result; the preset conditions include the value of the inverter phase current returning to zero as the sealing contactor's sealing action is performed.

[0016] The abnormal detection result is determined by the following method: if the sealing current does not meet the preset conditions, the elevator control system determines that the contactor sealing circuit detection result is an abnormal detection result.

[0017] This invention utilizes electronic sealing during elevator operation or when the elevator is stationary. When a sealing current is detected, the contactor is activated. Changes in the sealing current determine the contactor's functionality. Because the elevator remains electronically sealed throughout the detection process, the risks associated with excessive speed or distance traveled when the contactor's sealing function fails are avoided. Furthermore, at the top floor, downward travel can reduce the contactor's detection time, minimizing disruption to passengers.

[0018] The detection method of the present invention, since the electronic star seal is always present in the slippery state, even if the contactor star seal circuit is abnormal, the slippery speed is very low and the slippery distance is short, so there is no safety risk and the detection time is short. 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 flowcharts illustrating the improved elevator sealing contactor detection method of the present invention.

[0021] Figure 3 This is a schematic diagram of the electronic sealing star follow-up circuit formation in the improved elevator sealing star contactor detection method of the present invention.

[0022] Figure 4 This is a schematic diagram of the contactor sealing method for the elevator sealing contactor of the present invention.

[0023] Figure 5 This is the second flowchart illustrating the improved elevator sealing contactor detection method of the present invention.

[0024] Figure 6This is the third flowchart illustrating the improved elevator sealing contactor detection method of the present invention.

[0025] Figure 7 This is the fourth flowchart illustrating the improved elevator sealing contactor detection method of the present invention. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0027] In one embodiment, such as Figure 2 As shown, an improved method for detecting a sealing contactor in an elevator is provided, which is applied to an elevator control system; the sealing circuit includes a frequency converter, a sealing contactor, and an elevator host, with the frequency converter connected to the elevator host equipped with the sealing contactor.

[0028] The improved contactor sealing contactor detection method for elevators includes: placing the elevator in a brake-released, slippery state with both electronic and contactor sealing working together; and determining the contactor sealing circuit detection result based on the current feedback from the frequency converter (referred to as sealing current). Specifically, this includes:

[0029] Step S210: Run the car under electronic star-sealing condition and detect its star-sealing current;

[0030] Step S220: If a sealing current is detected in the electronic sealing chute, the contactor sealing chute is activated.

[0031] Step S230: Based on the change of the sealing current before and after the sealing contactor is sealed, determine the detection result of the sealing circuit of the contactor.

[0032] like Figure 1 The existing "electronic star-blocking" technology can be achieved by blocking (i.e., rendering ineffective, 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. Because the drive signal of one bridge arm of the frequency converter is continuously blocked, it prevents… Figure 1 The intermediate bus voltage provides driving energy to the elevator host. In this case, the elevator host cannot generate torque other than that combined with braking, so "electronic star-locking" is a safe electrical braking system.

[0033] When the elevator is electronically or via a contactor, the resistors R1, R2, and R3 of each phase winding of the elevator main unit, the inductors L1, L2, and L3 of each phase winding, and the back electromotive forces e1, e2, and e3 generated by the rotation of the elevator main unit form a braking circuit. The braking torque of this circuit exhibits a characteristic of first increasing and then decreasing with the increase of the elevator main unit's rotational speed. This is because as the elevator main unit's rotational speed increases, the generated back electromotive force e increases, the current flowing through the braking circuit increases, and the resulting braking torque also increases. However, because the inductive reactance of the elevator main unit's inductors L1, L2, and L3 also increases with the increase of rotational speed, the ratio of the inductive reactance L1, L2, and L3 to the resistors R1, R2, and R3 in the braking circuit also increases with the increase of rotational speed. This causes the current in the braking circuit to lead the back electromotive force e by 90°, resulting in a decrease in braking torque after a certain rotational speed of the elevator main unit. Therefore, when the brake is released and the elevator car slips, if the mass difference between the elevator car and the counterweight generates an unbalanced force that causes the car to move, the star brake cannot keep the elevator car stationary, even if there is always a star brake current inside the elevator host.

[0034] When using electronic star-shaped switching, if the controllable switches T1, T2, and T3 of the upper bridge arm of the frequency converter are turned off, while the controllable switches T4, T5, and T6 of the lower bridge arm are turned on, it should be noted that, as referenced... Figure 1 Only when the phase current of the elevator host is negative (the phase current of the elevator host is positive if it flows towards the elevator host), that is, when the phase current flows from the elevator host to the frequency converter, will the controllable switches T4, T5, and T6 of the lower bridge arm be controlled by the phase drive signal corresponding to the phase current. When the phase current is positive, even if the phase drive signal corresponding to the phase current is valid, T4, T5, and T6 will not be turned on, and the current will flow to the motor through the diodes D4, D5, and D6 connected in anti-parallel to T4, T5, and T6. For example, when the U-phase current of the frequency converter is positive and the V and W-phase currents are negative, the current path of the star-sealed circuit is as follows. Figure 3 As shown, T5, T6, and D4 form a "short circuit" in the elevator main machine winding. Under the action of the back EMF of the elevator main machine, a sinusoidal star-sealing braking current is generated in the star-sealing circuit.

[0035] When a sealing current is detected in the electronic sealing chock, the sealing contactor activates the sealing function on the elevator main unit. The elevator control system determines the sealing circuit result based on the change in sealing current flow before and after the sealing contactor's activation. Figure 4 As shown, the dashed line represents the star-sealing current after the main contact KM2 of the star-sealing contactor is closed. (Comparison) Figure 3 and Figure 4If the contactor's star-sealing circuit is normal, after the star-sealing contactor successfully completes its star-sealing action, the star-sealing current no longer flows through the frequency converter, but only through the elevator host and the star-sealing contactor. The elevator control system can determine the contactor's star-sealing circuit detection result based on the change in the star-sealing current before and after the star-sealing contactor's action. If the change in the star-sealing current before and after the star-sealing action conforms to the above pattern, it can be determined that the contactor's star-sealing circuit is normal and can achieve effective star-sealing; otherwise, the contactor's star-sealing circuit is abnormal and cannot achieve effective star-sealing. The star-sealing current of the star-sealing circuit can include the phase current at the output terminal of the frequency converter when the elevator host is in the star-sealing state. By detecting the phase current at the output terminal of the frequency converter, if the contactor's star-sealing circuit is effective, the phase current value at the output terminal of the frequency converter will return to zero with the star-sealing action of the contactor; if the contactor's star-sealing circuit is ineffective, the phase current value at the output terminal of the frequency converter will not exhibit the above phenomenon. The contactor's star-sealing circuit detection result can be determined based on the change in the phase current value at the output terminal of the frequency converter.

[0036] In one embodiment, the contactor star-sealing circuit detection result includes normal detection result and abnormal detection result; the method includes:

[0037] If the sealing current meets the preset conditions, the elevator control system determines that the contactor sealing circuit detection result is a normal detection result; the preset conditions include the value of the inverter phase current returning to zero as the sealing contactor operates.

[0038] If the sealing current does not meet the preset conditions, the elevator control system determines that the contactor sealing circuit detection result is an abnormal detection result.

[0039] Specifically, such as Figure 4 As shown, the dashed line represents the star-sealing current after the main contact KM2 of the star-sealing contactor is closed. (Comparison) Figure 3 and Figure 4 If the contactor sealing circuit is normal, the phase current at the inverter output terminal is not zero before the contactor sealing action (i.e., under electronic sealing). 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 sealing current to no longer flow through the inverter. The elevator control system can determine the contactor sealing circuit detection result based on 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 phase current at the inverter output terminal before and after the contactor sealing action meets the above preset conditions, it can be determined that the contactor sealing circuit is normal and can achieve effective sealing; otherwise, the contactor sealing circuit is abnormal and cannot achieve effective sealing. It should be noted that if the detected phase current is small enough, it can be considered that the phase current is zero. For example, if the phase current is less than the preset zero threshold (the preset zero threshold can be close to zero but not zero), the phase current is considered to be zero.

[0040] Because the electronic star-sealing circuit is always active during the slippage process, when the contactor star-sealing circuit malfunctions, braking can be applied through the electronic star-sealing circuit, thus maintaining the elevator speed at a very low star-sealing braking speed.

[0041] In some examples, such as Figure 5 As shown, firstly, the main contacts of the sealing contactor are disconnected, and the elevator operates with controlled speed and brake release. Then, electronic sealing is performed to determine if a sealing braking current is detected. If a sealing braking current is detected (indicating that the elevator host's speed has reached the point where its back electromotive force generates current in the braking circuit), the contactor is sealed. If no current is detected, the system waits. If a sealing current is detected during electronic sealing, the sealing contactor seals the elevator host. The elevator control system can determine the contactor sealing circuit detection result by checking whether the phase current at the inverter's output terminal suddenly returns to zero upon the sealing action of the sealing contactor.

[0042] If the empty car is on the top floor, this method can be used, i.e., the test is performed during the downward movement, thereby shortening the test time and minimizing the impact on passengers. Furthermore, the above-mentioned contactor star circuit test can be performed when the elevator is in an empty or standby state.

[0043] In some examples, such as Figure 6 As shown, it is similar to Figure 5 The only difference is that the electronic sealing starts from a standstill, and then the car rolls off the brakes. This can be used when the car is not on the top floor. It should be noted that the parts that are the same as or corresponding to those in the foregoing embodiments can be referred to the description of the foregoing embodiments, and will not be repeated below.

[0044] In some examples, such as Figure 7 As shown, the elevator is in a brake-released slippage state with both electronic and contactor star-sealing working together. The detection result of the contactor star-sealing circuit is determined based on the presence or absence of star-sealing current.

[0045] 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. An improved method for detecting a sealing star contactor used in elevators, applied to an elevator control system, characterized in that: The sealing circuit includes a frequency converter, a sealing contactor, and an elevator main unit. The frequency converter is connected to the elevator main unit equipped with the sealing contactor. The elevator sealing contactor detection method includes placing the elevator in a brake-released, runaway state with both electronic sealing and contactor sealing working together. The elevator sealing contactor detection method includes the following steps: Step S210: Electronic star sealing rollout and detection of star sealing current; Step S220: If a sealing current is detected in the electronic sealing chute, the sealing contactor is used to seal the sealing chute. Step S330: Determine the detection result of the sealing circuit based on the change of the sealing current before and after the sealing contactor is sealed; 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 improved method for detecting a sealing contactor for elevators 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 test result is determined as follows: if the sealing current meets the preset conditions, the elevator control system determines that the contactor sealing circuit test result is a normal test result; the preset conditions include the value of the inverter phase current returning to zero as the sealing contactor seals; The abnormal detection result is determined by the following method: if the sealing current does not meet the preset conditions, the elevator control system determines that the contactor sealing circuit detection result is an abnormal detection result.

3. An improved method for detecting a sealing contactor used in elevators, applied to an elevator control system, characterized in that: The sealing circuit includes a frequency converter, a sealing contactor, and an elevator main unit. The frequency converter is connected to the elevator main unit equipped with the sealing contactor. Its characteristic is that: When the normally closed contact of the sealing contactor is in the closed state, forming a contactor sealing circuit, the elevator is controlled to enter the brake release and slippage state, and the electronic sealing is activated at the same time, so that the electronic sealing circuit and the contactor sealing circuit work together. During the brake release and slippage process, the detection result of the contactor's star-sealing circuit is determined based on the presence or absence of the star-sealing current detected by the frequency converter. When the elevator is in a slippery state with the brakes released and both the electronic and contactor sealing currents are activated, the detection result of the contactor sealing circuit is determined based on the presence or absence of the sealing current. "Based on the presence or absence of the star-sealing current detected by the frequency converter, the detection result of the star-sealing circuit of the contactor is determined" specifically as follows: If the inverter does not detect the star-sealing current, it is determined that the contactor star-sealing circuit is normal; at this time, the star-sealing current flows through the contactor star-sealing circuit. If the inverter detects the star-sealing current, it determines that the contactor star-sealing circuit is abnormal. At this time, because the impedance of the contactor star-sealing circuit is abnormal, the star-sealing current is forced to flow through the electronic star-sealing circuit and is detected by the inverter. 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.

4. The method as described in claim 1 or 3, characterized in that, The detection method is activated when the elevator is in an unoccupied, standby state.

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