An electronic ballast circuit detection method

Abstract

The application discloses an electronic star-enclosing loop detection method applied to an elevator control system; the electronic star-enclosing loop comprises a frequency converter and an elevator host, and the frequency converter is connected to the elevator host; the electronic star-enclosing loop detection method comprises the following steps: step 1, under the condition that the elevator is in a stationary state, the elevator control system controls the frequency converter to input a detection current to the elevator host; step 2, under the condition that the detection current reaches a preset current value, the elevator control system controls the frequency converter to perform electronic star-enclosing, thereby forming a freewheeling path between the frequency converter and the elevator host; and step 3, the elevator control system determines an electronic star-enclosing loop detection result based on freewheeling current information of the electronic star-enclosing loop. The application can avoid the missed detection and the false detection of the conventional detection mode, thereby reliably and accurately judging the effectiveness of the electronic star-enclosing loop, and further improving the safety performance of the elevator. The application detects under the stationary state of the elevator, and the detection time is short, thereby not affecting the use of the elevator by passengers.

Description

Technical Field

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

[0002] With the development of elevator technology, the safety requirements for elevators are becoming increasingly stringent. In some usage scenarios, elevator slippage may occur, such as when the elevator's brakes fail to fully engage the traction sheave.

[0003] 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").

[0004] One common method for sealing off elevator control systems is using a "sealed-off contactor." This involves adding a sealed-off contactor between the frequency converter and the PM motor to short-circuit the motor's three-phase input. However, this sealed-off contactor must be selected to withstand the motor current and be able to connect and / or disconnect this current. These contactors are often large and expensive. Furthermore, contactors with moving parts have a limited lifespan and must be replaced after a relatively small number of operations.

[0005] The second commonly used method of star-blocking is to use "electronic star-blocking", which means that while the inverter blocks the drive signal of the upper (lower) bridge arm, it controls the switching transistor of the lower (upper) bridge arm to conduct, thereby short-circuiting the three-phase input of the motor.

[0006] Chinese invention patent application publication number CN105762766 A uses a star-sealing logic unit to generate a lower bridge arm drive pulse from the star-sealing signal and the lower bridge arm control pulse, thereby realizing "electronic star-sealing". During normal operation, its star-sealing signal is always invalid. It automatically monitors the PWM module, driver, IGBT circuit, and the "normally closed failure (always valid, this failure is a safety failure)" of the star-sealing signal in its electronic star-sealing circuit. However, if the star-sealing signal experiences a "normally open failure (always invalid, this failure is a dangerous failure)", the actual star-sealing function does not exist when a stop command is received and a valid star-sealing signal is sent.

[0007] Chinese invention patent application publication number CN115321297A discloses a method for detecting the effectiveness of an elevator electrical braking device, including: step S1, determining whether the elevator is in an unloaded or standby state, and controlling the elevator to run to a preset floor; step S2, controlling the electrical braking device to enter braking mode and opening the brake of the elevator drive host; step S3, detecting the speed of the elevator car or the motor current of the elevator drive host; step S4, determining whether to output a preset fault signal based on the detected speed or current. This detection process requires the brake to be released and the elevator to run, which carries a certain risk, and it requires a series of processes such as "running"—"failure judgment"—"braking"—"re-leveling", which is relatively time-consuming. Summary of the Invention

[0008] To address the above problems, the present invention aims to provide an electronic star-sealing circuit detection method that avoids the shortcomings of traditional detection methods, such as missed detections, false detections, and long detection times. This method can reliably and accurately determine the validity of the electronic star-sealing circuit, thereby improving elevator safety performance.

[0009] To achieve the above-mentioned objectives, the electronic satellite sealing loop detection method of the present invention has the following two methods:

[0010] One method is: an electronic star-sealing circuit detection method, which is applied to an elevator control system; the electronic star-sealing circuit includes a frequency converter and an elevator host, and the frequency converter is connected to the elevator host;

[0011] The electronic satellite sealing loop detection method includes:

[0012] During elevator operation, flags that allow electronic star detection are made based on the elevator's load information, or the current, voltage, power, or torque information output by the frequency converter.

[0013] When the frequency converter receives the stop output command, it performs electronic sealing to form a continuous flow path between the frequency converter and the elevator host.

[0014] The elevator control system determines the detection result of the electronic star-sealing circuit based on the freewheeling current information of the electronic star-sealing circuit.

[0015] 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 electronic star-sealing detection.

[0016] Another method is: an electronic star-sealing circuit detection method applied to an elevator control system; the electronic star-sealing circuit includes a frequency converter and an elevator host, the frequency converter being connected to the elevator host;

[0017] The electronic satellite sealing loop detection method includes the following steps:

[0018] Step 1: When the elevator is stationary, the elevator control system controls the frequency converter to input a detection current to the elevator host.

[0019] Step 2: When the detected current reaches the preset current value, the elevator control system controls the frequency converter to perform electronic star-sealing, forming a continuous current path between the frequency converter and the elevator host.

[0020] Step 3: The elevator control system determines the detection result of the electronic star-sealing circuit based on the freewheeling current information of the electronic star-sealing circuit.

[0021] In one embodiment, the detection of the electronic star-sealing circuit can be achieved in one step by inputting a three-phase detection current into the elevator host.

[0022] In one embodiment, by inputting two-phase detection current to the elevator host, two detections are required to cover the electronic star-sealing circuit.

[0023] In a preferred embodiment of the present invention, the detection results of the satellite sealing loop include normal detection results and abnormal detection results; specifically as follows:

[0024] If the freewheeling current meets the preset conditions, the elevator control system determines that the electronic star-sealing circuit detection result is a normal detection result; the preset conditions include the slope of the freewheeling current falling below a certain threshold, or the freewheeling current being greater than a certain threshold, or the freewheeling time being greater than a certain threshold.

[0025] If the freewheeling current does not meet the preset conditions, the elevator control system determines that the detection result of the sealing circuit is an abnormal detection result.

[0026] 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 electronic star-sealing circuit and improving elevator safety performance. This invention performs detection while the elevator is stationary, resulting in a short detection time and minimizing disruption to passengers' use of the elevator. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the connection principle of a typical electronic satellite constellation.

[0028] Figure 2 This is a schematic flowchart of the first embodiment of the electronic satellite sealing loop detection method of the present invention.

[0029] Figures 3a to 3cThis is a schematic diagram of the current loop formation before stopping in an embodiment of the electronic star-sealing loop detection method of the present invention.

[0030] Figure 4a and Figure 4b This is a schematic diagram of the formation of the electronic star-sealing follow current loop in an embodiment of the electronic star-sealing loop detection method of the present invention.

[0031] Figure 5 This is a schematic diagram of the freewheeling current under conditions of no electron star sealing and with electron star sealing in one embodiment of the present invention.

[0032] Figure 6 This is a flowchart illustrating a method for detecting a sealed-off loop in one embodiment of the present invention.

[0033] Figure 7 This is a schematic flowchart illustrating another embodiment of the present invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] In one embodiment, such as Figure 2 As shown, an electronic star-sealing circuit detection method is provided, which is applied to an elevator control system; the electronic star-sealing circuit includes a frequency converter and an elevator main unit (PM motor); the method includes:

[0036] Step S210: Detect the output current of the frequency converter during elevator operation.

[0037] Step S220: When the detected current reaches a preset current value, a flag is made to allow electronic satellite detection.

[0038] In step S230, when the frequency converter receives the stop output command, the frequency converter performs electronic sealing to form a continuous flow path between the frequency converter and the elevator host.

[0039] Specifically, Chinese invention patent application publication number 114778991A illustrates the waveform of the motor output torque (positively correlated with the inverter output current in a PM motor) 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 related to the current magnitude during starting at zero speed, high-speed constant speed, and stopping at zero speed, and also to the current magnitude during acceleration and deceleration. In some examples, when the load is 0% and the elevator is descending (i.e., empty car, no passengers), the motor output current is approximately 75% of the motor's rated current. This can be increased by injecting an excitation current Id, such as to 100% of the motor's rated current.

[0040] like Figure 1The 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 busbar provides driving energy to the PM motor. In this case, the PM motor 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.

[0041] 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 PM motor), and since the motor voltage is generated by PWM modulation of the bus voltage Ud, the instantaneous current path can be... Figure 3a (T1, T5, T6) or Figure 3b (T1, D2, T6) or Figure 3c (T1, D2, D3) or Figure 4a 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 4a As shown, the waveform of the freewheeling current in the star-sealed system is as follows: Figure 5 52 shown.

[0042] It should be noted that, under the premise that T1, T2, and T3 are off, the main controller outputs a valid star-blocking signal in Chinese invention patent application publication number CN105762766A. If the normally open star-blocking signal fails due to hardware malfunction, all switching transistors of the frequency converter will be shut down. Figure 4b The freewheeling current in its star-sealed circuit will be injected into the bus PN through a diode. Since the bus voltage Ud is approximately 540V during normal power supply (elevator power supply is three-phase 380V), the freewheeling time of the star-sealed current is significantly shortened. Figure 5 Curve 51.

[0043] The flag that allows electronic star 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.

[0044] In step S240, the elevator control system determines the detection result of the electronic star-sealing circuit based on the freewheeling current information of the electronic star-sealing circuit.

[0045] contrast Figure 5 Curves 51 and 52 can be used to determine the electronic star-sealing circuit detection results based on the slope of the freewheeling current decrease or whether the freewheeling current quickly returns to zero and other current-related information.

[0046] In one embodiment, the satellite sealing loop detection results include normal detection results and abnormal detection results; the method includes:

[0047] If the freewheeling current meets the preset conditions, the elevator control system determines that the star-sealing circuit detection result is a normal detection result; the preset conditions include that the rate of decline of the freewheeling current is lower than a certain threshold, or that the freewheeling current does not return to zero quickly.

[0048] If the freewheeling current does not meet the preset conditions, the elevator control system determines that the star-sealing circuit detection result is an abnormal detection result.

[0049] It should be noted that if the detected freewheeling current is small enough, the freewheeling current can be considered to be zero. For example, if the freewheeling current is less than a preset zero threshold (the preset zero threshold can be close to zero but not zero), the freewheeling current is considered to be zero.

[0050] It should be further explained that, Figure 5 The values ​​t1 and t3 in the equation are related to the electrical time constant of the elevator motor. The smaller the electrical time constant, the smaller t1 and t3 are. In addition, t1 is also related to the bus voltage. The higher the bus voltage, the smaller t1 is.

[0051] In some examples, such as Figure 6 As shown, first, it is determined whether the elevator is running. If it is running, the output current of the frequency converter is detected. It is then determined whether the output current has reached a predetermined value A. If the output current reaches the predetermined value A, the flag for allowing electronic star-sealing detection is set. When the frequency converter receives a stop output command, it performs electronic star-sealing. When electronic star-sealing detection is allowed, a timer is started. It is then determined whether the output current rapidly returns to zero before the timer reaches a predetermined value B. If so, the flag for allowing electronic star-sealing detection is cleared, and an abnormal electronic star-sealing function message is output. If the output current does not rapidly return to zero before the timer reaches the predetermined value B, the flag for allowing star-sealing detection is cleared, and an abnormal star-sealing contactor function message is output.

[0052] In another embodiment, such as Figure 7 As shown, an electronic star-sealing circuit detection method is provided, which is applied to an elevator control system; the electronic star-sealing circuit includes a frequency converter and an elevator main unit, wherein the frequency converter is connected to the elevator main unit; the method includes:

[0053] Step 710: When the elevator is stationary, the elevator control system controls the frequency converter to input a detection current to the elevator host.

[0054] Specifically, the star-sealing circuit detection checks whether the star-sealing circuit is effective during the electronic star-sealing process. This can be performed when the elevator is stationary, i.e., when the elevator brake is not engaged. In some examples, PWM control (T1-T6 are all complementary PWM control with dead time, or T1 is always on while T5 / T6 are PWM controlled, or T1 is PWM controlled while T5 / T6 are always on, or T1 / T5 / T6 are consistent PWM controlled, etc.) can be used to ensure that the input detection current is positive for the U-phase current and negative for the V and W-phase currents (the phase current of the inverter is positive when it flows to the PM motor).

[0055] Step 720: When the detected current reaches the preset current value, the elevator control system controls the frequency converter to perform electronic star-sealing, forming a continuous flow path between the frequency converter and the elevator host.

[0056] Specifically, as the detection current in the sealing circuit increases until it reaches a preset current value, such as the rated current for the elevator host, the elevator control system controls the frequency converter to perform electronic sealing.

[0057] It should be noted that in step 720, the detection current reaching the preset current value can also be replaced by the inverter's output voltage or output power reaching the preset value.

[0058] During the electronic star sealing process, due to the freewheeling effect of the elevator host coil, the freewheeling current can be achieved through the freewheeling diode and controllable switch tube formed by the elevator host, the inverter, and the freewheeling current in the star sealing circuit gradually decreases from the initial current value.

[0059] In some examples, when the detected current is positive for phase U and negative for phases V and W, the elevator main unit's voltage is modulated by PWM using the bus voltage Ud (T1-T6 are all complementary PWM control with dead time, or T1 is always on while T5 / T6 are PWM controlled, or T1 is PWM controlled while T5 / T6 are always on, or T1 / T5 / T6 are consistently PWM controlled, etc.). Therefore, the instantaneous current path can be... Figure 3a or Figure 3b or Figure 3c or Figure 4a or Figure 4b As shown in Figure 4(a). It should be noted that during electronic star-sealing, i.e., when the controllable switches T1, T2, and T3 of the upper bridge arm of the inverter are turned off, and the controllable switches T4, T5, and T6 of the lower bridge arm are turned on, the freewheeling path becomes as shown in Figure 4(a). The star-sealing freewheeling current waveform is as follows: Figure 5 52 shown.

[0060] Step 730: The elevator control system determines the electronic star-sealing circuit detection result based on the freewheeling current information of the electronic star-sealing circuit. This step is the same as step S240, and can be referred to the description in the foregoing embodiment, and will not be repeated below.

[0061] It should be noted that in step 710, by inputting three-phase detection current to the elevator host, the detection of the star-sealing circuit can be achieved in one step; by inputting two-phase detection current to the elevator host, two detections are required to cover the star-sealing circuit.

[0062] 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 an electronic star-sealing circuit, applied to an elevator control system; the electronic star-sealing circuit includes a frequency converter and an elevator main unit, the frequency converter being connected to the elevator main unit; characterized in that, The electronic satellite sealing loop detection method includes: During elevator operation, flags that allow electronic star detection are 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, the frequency converter performs electronic sealing to form a continuous flow path between the frequency converter and the elevator host. The elevator control system determines the detection result of the electronic star-sealing circuit based on the freewheeling current information of the electronic star-sealing circuit. The detection results of the satellite sealing circuit include normal detection results and abnormal detection results; as detailed below: If the freewheeling current meets the preset conditions, the elevator control system determines that the electronic star-sealing circuit detection result is a normal detection result; the preset conditions include the slope of the freewheeling current falling below a certain threshold, or the freewheeling current being greater than a certain threshold, or the freewheeling time being greater than a certain threshold. If the freewheeling current does not meet the preset conditions, the elevator control system determines that the detection result of the sealing circuit is an abnormal detection result.

2. An electronic star-sealing circuit detection method, applied to an elevator control system; the electronic star-sealing circuit includes a frequency converter and an elevator main unit, the frequency converter being connected to the elevator main unit; The electronic satellite sealing loop detection method includes the following steps: Step 1: When the elevator is stationary, the elevator control system controls the frequency converter to input a detection current to the elevator host. Step 2: When the detected current reaches the preset current value, the elevator control system controls the frequency converter to perform electronic star-sealing, forming a continuous current path between the frequency converter and the elevator host. Step 3: The elevator control system determines the detection result of the electronic star-sealing circuit based on the freewheeling current information of the electronic star-sealing circuit; The detection results of the satellite sealing circuit include normal detection results and abnormal detection results; as detailed below: If the freewheeling current meets the preset conditions, the elevator control system determines that the electronic star-sealing circuit detection result is a normal detection result; the preset conditions include the slope of the freewheeling current falling below a certain threshold, or the freewheeling current being greater than a certain threshold, or the freewheeling time being greater than a certain threshold. If the freewheeling current does not meet the preset conditions, the elevator control system determines that the detection result of the sealing circuit is an abnormal detection result.

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