Elevator power failure self-rescue brake pipe control method

Abstract

The invention discloses an elevator power failure self-rescue brake pipe control method. When the external power grid is powered off, the frequency converter is firstly switched to a standby mode and enters a power failure self-rescue mode after receiving a power failure cabinet instruction. In the mode, the elevator runs in a low-power generating state, an additional braking resistor and a heat dissipation space are not needed, by arranging a bus voltage loop and a direct-axis current loop and adjusting voltage and current, generating energy is reversely transmitted to a motor coil to be consumed, and an additional driving and detecting loop is not needed. And when the bus voltage reaches a set starting voltage threshold value, the rectification side controls the on-off of the switching tube in a chopping mode according to a set duty ratio, a loop is controlled, the bus voltage is reduced to a bearing range of a brake resistor, and emergency operation is realized. The standby mode is returned according to an instruction after power-off self-rescue is finished, and the operation is cycled after the emergency mode is switched for processing when a fault occurs. The invention can reduce the cost, simplify the structure of the control cabinet, save the space, optimize the energy control, and improve the reliability and economical efficiency of elevator power failure self-rescue.

Description

Technical Field

[0001] The invention relates to the technical field of elevator control, in particular to a method for controlling a power-off self-rescue brake pipe of an elevator. Background Art

[0002] As an indispensable vertical transportation tool in modern buildings, the safety of elevator operation is of vital importance. When the mains voltage is unstable or even out of power, the elevator may stop running, resulting in people being trapped in the elevator, which poses a great safety hazard. To solve this problem, the elevator power failure self-rescue device came into being.

[0003] The existing elevator power outage self-rescue technology has deficiencies in energy processing. When an energy feedback type elevator power outage self-rescue occurs, since the elevator inverter is disconnected from the external power grid, the energy generated by the motor cannot be fed back to the power grid, requiring additional consumption. Figure 1 As shown, the common method at present is to configure a brake pipe for power outage self-rescue in the inverter separately, control the on and off of the brake pipe by the bus voltage, and form a loop with the battery pack and brake resistor to consume the generated energy. However, the bus voltage is usually high (generally between 600V-750V), and the brake resistor specification is small (generally 5Ω / 1000W). If the bus is directly connected to the loop to only control the on or off of the brake pipe, the capacity and volume of the adapted brake resistor will be large, which will increase the volume of the control cabinet and increase the cost. In addition, the high voltage will cause the brake resistor to heat up seriously, resulting in a rapid increase in the temperature rise of the control cabinet, and may even burn the brake resistor, reducing the stability and service life of the components in the control cabinet. Summary of the invention

[0004] The purpose of the present invention is to provide a method for controlling a brake pipe during a power failure of an elevator, so as to solve the problems existing in the prior art such as high cost, large volume of a control cabinet, and severe heating of a brake resistor, and to improve the reliability and economy of the elevator power failure self-rescue system.

[0005] In order to achieve the above object, the present invention is implemented through the following technical scheme: a method for controlling an elevator power failure self-rescue brake pipe, comprising the following steps:

[0006] Operation mode switching:

[0007] When the external power grid fails, the inverter first receives the stop command and switches from the running mode to the standby mode. In the standby mode, the rectifier part stops working and all six switch tubes are in the off state.

[0008] Power outage self-rescue mode starts:

[0009] When receiving the power failure self-rescue mode command from the power failure cabinet, the inverter switches to the power failure self-rescue mode. At this time, the present invention adopts innovative technical means:

[0010] When the elevator is powered off and self-rescued, the elevator is operated in a low-power power generation state and in the power generation direction, without the need for additional brake resistors and energy consumption resistors. Specifically, by properly controlling the operating parameters of the elevator system, the electric energy generated by the elevator during a power outage can be circulated internally in a more controllable manner, avoiding the problem of large-volume brake resistors being required to consume energy in the traditional method because there is nowhere to release the energy, thereby reducing the size of the power supply cabinet, reducing temperature rise, and improving device stability and life.

[0011] At the same time, the outer loop is set as the bus voltage loop and the inner loop is set as the direct-axis current loop to adjust the bus voltage and the motor direct-axis current, so that the generated energy is reversely transmitted to the motor coil and consumed in the form of heat energy, thereby realizing energy feedback to the power supply cabinet of the elevator without the need for additional configuration of drive circuits, detection circuits, etc. Through this dual-loop control method, energy can be accurately managed and consumed, further reducing the size of the power supply cabinet and reducing temperature rise.

[0012] When the bus voltage reaches the set start-up voltage threshold, the rectifier side uses chopping to control the switch tubes of the upper and lower bridge arms with a set duty cycle, thereby controlling the on and off of the circuit. In this way, the bus voltage can be temporarily reduced to within the tolerance range of the braking resistor, and the energy generated by the power outage self-rescue can flow to the braking resistor, achieving the purpose of consuming the energy on the bus, allowing the elevator to run at an emergency speed until it stops at the door area, opens the door and releases the passengers, completing the power outage self-rescue.

[0013] Exit the power failure self-rescue mode:

[0014] After the power outage self-rescue is completed, when the inverter receives the power outage self-rescue mode exit command sent by the power outage cabinet, the inverter switches back to standby mode.

[0015] Fault handling mechanism:

[0016] If a frequency conversion fault occurs during the power failure self-rescue process, the inverter will switch from the power failure self-rescue mode to the emergency mode. In the emergency mode, the fault is first handled until the fault is eliminated, and then the above power failure self-rescue mode and standby mode switching process are repeated.

[0017] Detailed control process in power outage self-rescue mode:

[0018] Step 0: When the power failure self-rescue mode is started, first turn off all 6 switch tubes, close the output, and then enter Step 1.

[0019] Step 1: In this step, the bus voltage is monitored in real time. When the bus voltage is detected to exceed the set switch tube start voltage U openWhen the bus voltage U dc Greater than U open When the switch tubes SN and TP are turned on for m cycles and then turned off for n cycles, then Duty = m / (m+n), where m and n can be adjusted according to the different specifications of the brake resistor. By properly adjusting the Duty, the bus voltage can be temporarily reduced within the tolerance range of the small-sized brake resistor. When the bus voltage is detected to be lower than the start voltage U open When the elevator reaches the nearest floor and opens the door to release passengers, it will receive a power failure self-rescue mode exit command and enter Step 2.

[0020] Step 2: In this step, all 6 switch tubes are turned off, the output is closed, the system exits the power failure self-rescue mode and enters the standby mode. If a frequency conversion fault occurs in the power failure self-rescue mode, the system immediately exits the mode and enters the emergency mode to handle the fault. After the fault is eliminated, repeat the above Step 0-Step 2 process.

[0021] The present invention has the following beneficial effects:

[0022] 1. Cost savings

[0023] The present invention directly utilizes the two switch tubes on the upper and lower bridge arms of the original inverter to realize the energy release in the process of power failure self-rescue, without the need for additional brake tubes and matching detection circuits and other components, effectively reducing the hardware cost. At the same time, since no additional brake resistors and energy consumption resistor heat dissipation space related configurations are required, the cost is further reduced.

[0024] 2. Simplified control cabinet

[0025] Since there is no need for additional brake pipes, detection circuits, drive circuits, brake resistors and heat dissipation space related components, the internal structure of the control cabinet is greatly simplified, reducing the possibility of component connection failures, facilitating production, assembly and daily maintenance, improving maintenance efficiency and reducing maintenance costs.

[0026] 3. Space saving

[0027] By adopting the above-mentioned innovative energy processing method, including operating the elevator in a low-power power generation state and dual-loop control to reversely transmit energy to the motor coil for consumption, the need for large-volume braking resistors and related heat dissipation space and additional circuits is avoided, thereby greatly saving space in the control cabinet and helping to optimize the elevator machine room layout.

[0028] 4. Energy control optimization

[0029] The present invention can accurately control the on-off and duty cycle of the switch tube according to the bus voltage conditions, ensure that the bus voltage temporarily drops within the tolerance range of small-sized brake resistors, realize effective consumption and control of energy in the power outage self-rescue process, avoid problems such as overheating of the brake resistor and excessive temperature rise of the control cabinet, and improve the safety and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0031] Figure 1 It is a schematic diagram of a power outage self-rescue control scheme of the prior art;

[0032] Figure 2 Schematic diagram of the system mode mechanism of a method for controlling a power failure self-rescue brake pipe of an elevator according to an embodiment of the present invention;

[0033] Figure 3 It is a schematic diagram of a power failure self-rescue control scheme of a power failure self-rescue brake pipe control method for an elevator according to an embodiment of the present invention;

[0034] Figure 4 The present invention is a flowchart of a power failure self-rescue control method of an elevator power failure self-rescue brake pipe control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The exemplary embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0036] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, upper end, lower end, top, bottom...) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0037] In the present invention, unless otherwise clearly defined and limited, the term "connection" should be understood in a broad sense, for example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features; in addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] The following is combined with Figure 2 To Attachment Figure 4 The present invention is described in further detail.

[0040] Reference Figures 2 to 4 , a method for controlling an elevator power failure self-rescue brake pipe, comprising the following steps:

[0041] (I) Hardware configuration

[0042] Frequency Converter

[0043] The elevator frequency converter involved in the present invention comprises a rectifier part and an inverter part. The rectifier part has multiple switch tubes (such as the switch tubes on the CNV control board), and the inverter part also has multiple switch tubes (such as the switch tubes on the INV control board). These switch tubes play a key role in different modes of elevator operation.

[0044] The inverter is connected to a battery pack (BAT) to provide the necessary power for the elevator operation during a power outage.

[0045] The frequency converter is also connected to a braking resistor for consuming the energy generated by the motor during the elevator's power outage self-rescue process (in the present invention, due to the use of a new energy processing method, the specifications and usage of the braking resistor are different from the traditional method).

[0046] Power outage cabinet

[0047] The power outage cabinet is connected to the inverter for communication and is used to send control instructions such as elevator stop instructions, power outage self-rescue mode instructions, and power outage self-rescue mode exit instructions to the inverter when the external power grid fails.

[0048] (II) Specific operation process

[0049] 1. Initial operating status

[0050] Under normal mains power supply, the elevator operates normally, the inverter is in operation mode, the rectifier and inverter parts operate normally, and the switch tubes on the CNV control board and the INV control board convert and control the electric energy to drive the elevator host to operate.

[0051] 2. Power outage detection and mode switching

[0052] When the external power grid fails, the detection circuit of the inverter quickly detects the power failure, and the inverter immediately receives the elevator stop command and starts to switch from the running mode to the standby mode. During this process, the rectifier part stops working and all 6 switch tubes on the CNV control board are in the off state.

[0053] 3. Enter the power outage self-rescue mode

[0054] When the power outage cabinet detects a power outage in the power grid, it sends a power outage self-rescue mode command to the inverter. After receiving the command, the inverter switches to the power outage self-rescue mode. At this time, the following innovative operations are adopted:

[0055] The elevator enters a low-power power generation state and runs in the power generation direction: by accurately setting the relevant control parameters in the elevator system (such as the torque and speed of the motor), the elevator can work in a low-power power generation state during a power outage. In this process, by optimizing the power transmission and power conversion mechanism of the elevator system, it is avoided to generate too much energy that cannot be handled, so there is no need to configure additional braking resistors and energy consumption resistors for heat dissipation.

[0056] Dual-loop control realizes reverse transmission and consumption of energy: by setting the outer loop as the bus voltage loop and the inner loop as the direct-axis current loop, the control chip and related circuits in the inverter are used to accurately adjust the bus voltage and the motor direct-axis current. Specifically, the bus voltage loop monitors the bus voltage in real time and transmits the voltage deviation signal to the direct-axis current loop of the inner loop. The direct-axis current loop accurately controls the motor direct-axis current based on the received signal, so that the generated energy is reversely transmitted to the motor coil and consumed in the form of heat energy. This dual-loop control mechanism realizes efficient management and precise control of energy without the need for additional configuration of drive circuits, detection circuits, etc.

[0057] At the same time, the inverter forms a loop with the internal switch tube SN, brake resistor, switch tube TP and bus (such as Figure 3 When the bus voltage reaches the set threshold, the inverter rectifier side controls the switch tubes of the upper and lower bridge arms by chopping to control the on and off of the circuit. The specific control process is as follows:

[0058] Step 0 Specific operation: When receiving the power failure self-rescue mode command, the inverter immediately turns off all 6 switch tubes and turns off the output at the same time. This step ensures that the system is in a stable and safe initial state before entering the next control step, and then enters Step 1.

[0059] Step 1Specific operations:

[0060] Bus voltage monitoring: The voltage detection module inside the inverter continuously measures the bus voltage with high precision.

[0061] Switch control: When the bus voltage is detected to exceed the set switch on voltage U open When the inverter control chip controls the on and off of the switch tubes SN and TP according to the preset duty cycle Duty. For example, assuming that m=3 and n=2 are set according to the current brake resistor specifications, when the bus voltage U dc Greater than U open When the control chip turns on the switch tubes SN and TP for 3 cycles, and then turns them off for 2 cycles, and the cycle repeats. The duty ratio Duty = 3 / (3+2) = 0.6. Through this chopping control method, the bus voltage can be temporarily reduced to within the tolerance range of the small-sized brake resistor.

[0062] Fault judgment: During this process, the inverter fault detection module continuously monitors whether there is a frequency conversion fault. If the bus voltage is lower than the start voltage U open When the elevator reaches the nearest floor and opens the door to release passengers, it will receive a power failure self-rescue mode exit command and enter Step 2.

[0063] Step 2 Specific operation: After the inverter receives the exit command of the power failure self-rescue mode, it turns off all 6 switch tubes and the output. The system successfully exits the power failure self-rescue mode and enters the standby mode.

[0064] 4. Troubleshooting

[0065] If the inverter fault detection module detects a frequency conversion fault during the power outage self-rescue process, the inverter will immediately switch from the power outage self-rescue mode to the emergency mode. In the emergency mode, the elevator control system will start the fault handling program to diagnose and handle the fault. For example, the internal fault diagnosis algorithm is used to determine whether it is a switch tube fault or other circuit fault, and take corresponding repair measures, such as trying to restart the faulty component or switching to the backup circuit. After the fault is eliminated, the above power outage self-rescue mode and standby mode switching process are repeated to ensure that the elevator can continue to operate safely.

[0066] The present invention has the following beneficial effects:

[0067] 1. Cost savings

[0068] The present invention directly utilizes the two switch tubes on the upper and lower bridge arms of the original inverter to realize the energy release in the process of power failure self-rescue, without the need for additional brake tubes and matching detection circuits and other components, effectively reducing the hardware cost. At the same time, since no additional brake resistors and energy consumption resistor heat dissipation space related configurations are required, the cost is further reduced.

[0069] 2. Simplified control cabinet

[0070] Since there is no need for additional brake pipes, detection circuits, drive circuits, brake resistors and heat dissipation space related components, the internal structure of the control cabinet is greatly simplified, reducing the possibility of component connection failures, facilitating production, assembly and daily maintenance, improving maintenance efficiency and reducing maintenance costs.

[0071] 3. Space saving

[0072] By adopting the above-mentioned innovative energy processing method, including operating the elevator in a low-power power generation state and dual-loop control to reversely transmit energy to the motor coil for consumption, the need for large-volume braking resistors and related heat dissipation space and additional circuits is avoided, thereby greatly saving space in the control cabinet and helping to optimize the elevator machine room layout.

[0073] 4. Energy control optimization

[0074] The present invention can accurately control the on-off and duty cycle of the switch tube according to the bus voltage conditions, ensure that the bus voltage temporarily drops within the tolerance range of small-sized brake resistors, realize effective consumption and control of energy in the power outage self-rescue process, avoid problems such as overheating of the brake resistor and excessive temperature rise of the control cabinet, and improve the safety and reliability of the system.

[0075] Specifically, the implementation cases of the present invention are:

[0076] 1. Application Scenarios

[0077] A commercial office building is equipped with multiple passenger elevators, one of which adopts the power failure self-rescue brake pipe control method of the present invention. The office building has a large flow of people, the elevators are frequently used, and the safety and reliability of the elevator operation are required to be high.

[0078] 2. Hardware Installation

[0079] Frequency Converter

[0080] The frequency converter used in the elevator is configured according to the requirements of the present invention, and the switch tubes of the rectifier part (CNV control board) and the inverter part (INV control board) are installed normally and connected reliably. The frequency converter is connected to the elevator host to ensure that the operation of the elevator can be controlled normally.

[0081] The battery pack (BAT) uses high-capacity, stable-performance lead-acid batteries, which can meet the energy required for the elevator to run at emergency speed to the nearest floor to open the door in the event of a power outage. The battery pack is correctly connected to the inverter and has a reliable charge and discharge management system to ensure that it can be charged when the mains power is normal and can supply power in time when there is a power outage.

[0082] The braking resistor uses a smaller resistor (for example, 3Ω / 800W) according to the requirements of the present invention, and is installed near the inverter to facilitate connection with the internal circuit of the inverter to form an energy consumption loop (in the present invention, due to the new energy processing method, the use of the braking resistor is different from the traditional one).

[0083] Power outage cabinet

[0084] The power outage cabinet is installed in the elevator room and is connected to the inverter through a dedicated communication cable to ensure that various control instructions can be sent to the inverter in a timely and accurate manner when the external power grid fails.

[0085] 3. Operation process

[0086] 1. Normal operation

[0087] During normal working hours, the mains supply is normal and the elevator operates normally under the control of the inverter. The elevator can respond to passengers' calls quickly and smoothly and run efficiently between floors. The switch tubes of the rectifier and inverter parts of the inverter are turned on and off in an orderly manner according to the control signal to realize the conversion of electric energy and the drive of the motor.

[0088] 2. Power outage

[0089] On a certain weekday afternoon, the office building suddenly suffered a power outage from the external power grid.

[0090] Mode Switching

[0091] The inverter immediately detects the power outage and quickly switches from the running mode to the standby mode after receiving the elevator stop command. At this time, all six switch tubes on the CNV control board of the rectifier part are turned off, and the elevator stops normal operation, but still maintains the basic power supply (provided by the battery pack) such as lighting in the car.

[0092] Entering power outage self-rescue mode

[0093] After the power outage cabinet detects a power outage in the power grid, it sends a power outage self-rescue mode command to the inverter in a very short time (e.g. 1-2 seconds). After receiving the command, the inverter switches to the power outage self-rescue mode and uses the following operations:

[0094] The elevator enters a low-power power generation state and runs in the power generation direction: The control parameters of the elevator motor are adjusted through the inverter to make the elevator enter a low-power power generation state. In this process, the elevator system can convert the potential energy of the car and counterweight into electrical energy and process it internally in the form of low-power power generation. There is no need for additional braking resistors to consume a lot of energy, nor is there a need to configure heat dissipation space for the braking resistor.

[0095] Dual-loop control realizes reverse transmission and consumption of energy: The inverter is controlled by the outer bus voltage loop and the inner direct-axis current loop. The bus voltage loop monitors the bus voltage in real time, and when the bus voltage fluctuates, the deviation signal is transmitted to the direct-axis current loop. The direct-axis current loop adjusts the motor direct-axis current according to the signal, so that the energy generated by power generation is reversely transmitted to the motor coil and consumed inside the motor in the form of heat energy. In this way, there is no need to configure additional drive circuits and detection circuits to process the power generation energy.

[0096] Assuming that the bus voltage is 700V at this time, when the bus voltage reaches the set threshold (for example, 650V), the inverter rectifier side starts to control the switch tubes of the upper and lower bridge arms in a chopping manner.

[0097] In Step 0, the inverter turns off all six switches and closes the output.

[0098] Enter Step 1. When the bus voltage exceeds the set switch on voltage U open (Assume U open =600V), m=4, n=3 are set according to the brake resistor specifications, the control chip turns on the switch tubes SN and TP for 4 cycles, and then turns off for 3 cycles, and the duty cycle Duty=4 / (4+3)≈0.57. In this way, the bus voltage gradually decreases to the range that the brake resistor can withstand (for example, 400V), and the elevator starts running at an emergency speed (for example, 0.2m / s).

[0099] The elevator continuously monitors the bus voltage and its own operating status during operation. When the elevator runs to the nearest floor (for example, the 3rd floor) and opens the door to release the passengers, the inverter receives a command to exit the power failure self-rescue mode.

[0100] Exit power failure self-rescue mode

[0101] The inverter enters Step 2, turns off all 6 switch tubes, closes the output, successfully exits the power outage self-rescue mode and enters the standby mode. The entire power outage self-rescue process is completed smoothly, ensuring the safety of the passengers.

[0102] 4. Fault handling simulation

[0103] In another power outage test, assume that during the power outage self-rescue process, a switch tube of the inverter fails (such as a short circuit failure).

[0104] Fault detection and switching

[0105] The fault detection module of the frequency converter detects the frequency conversion fault in a very short time (for example, 0.5 seconds) and immediately switches from the power failure self-rescue mode to the emergency mode.

[0106] Troubleshooting

[0107] In emergency mode, the elevator control system starts the fault handling procedure. After determining that the switch tube is faulty through the internal diagnostic program, the control system attempts to cut off the circuit where the faulty switch tube is located and switch to the backup circuit (if any). If there is no backup circuit, the fault code is displayed to notify the maintenance personnel to come for repair.

[0108] After the maintenance personnel arrive, they replace the faulty switch tube and restart the elevator control system. The elevator control system re-executes the power failure self-rescue mode and standby mode switching process to ensure that the elevator can resume normal power failure self-rescue function after the fault is eliminated.

[0109] Through this implementation case, it can be seen that the power outage self-rescue brake pipe control method of the present invention can effectively cope with elevator power outages in practical applications, ensure the safe operation of the elevator during power outages, and reasonably handle faults when they occur, and has significant advantages in hardware cost and control cabinet space utilization.

[0110] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for controlling a brake pipe during a power outage of an elevator, characterized in that: The following steps are involved: Step S1: When the external power grid fails and the frequency converter receives a stop command, it switches from the running mode to the standby mode, so that the rectifier part stops working and all six switch tubes are in the off state; Step S2, when receiving the power failure self-rescue mode command sent by the power failure cabinet, the frequency converter switches from the standby mode to the power failure self-rescue mode, by making the elevator work in a low-power power generation state and running in the power generation direction, while setting the outer loop as the bus voltage loop and the inner loop as the direct-axis current loop, adjusting the bus voltage and the motor direct-axis current, so that the generated energy is reversely transmitted to the motor coil and consumed in the form of heat energy. When the bus voltage reaches the set start-up voltage threshold, the rectifier side controls the on-off of the circuit by chopping the switch tubes of the upper and lower bridge arms with a set duty cycle, so that the bus voltage is temporarily reduced within the tolerance range of the brake resistor, so as to consume the energy on the bus to realize the emergency operation of the elevator; Step S3: When the power outage self-rescue mode is completed and the inverter receives the power outage self-rescue mode exit instruction sent by the power outage cabinet, the inverter switches to the standby mode; Step S4: If a frequency conversion fault occurs during the power outage self-rescue process, the frequency converter switches from the power outage self-rescue mode to the emergency mode to handle the fault. After the fault is eliminated, the above power outage self-rescue mode and standby mode switching process are repeated.

2. The elevator power failure self-rescue brake pipe control method according to claim 1 is characterized in that: In the power outage self-rescue mode, the control process includes: In step 0, turn off all 6 switch tubes and close the output before entering step 1; In step 1, when the bus voltage is detected to exceed the set switch tube turn-on voltage U open , the switch tubes SN and TP are turned on and off with the set duty cycle Duty, and the other switch tubes are turned off, where the duty cycle Duty = m / (m+n), m is the bus voltage U dc Greater than U open The number of cycles when the switch tubes SN and TP are turned on, and n is the number of cycles when they are turned off. The values ​​of m and n can be adjusted according to the brake resistors of different specifications. When the bus voltage is detected to be lower than the start voltage U open When the power failure mode is exited, all six switch tubes are turned off and the output is closed. After the elevator reaches the nearest floor during self-rescue operation, opens the door to release passengers, and receives the power failure self-rescue mode exit command, it enters step 2. In step 2, all six switch tubes are turned off and the output is closed, exiting the power failure self-rescue mode and entering the standby mode.

3. The elevator power failure self-rescue brake pipe control method according to claim 2 is characterized in that: If a frequency conversion fault occurs in the power failure self-rescue mode, the mode is immediately exited and the emergency mode is entered to handle the fault. After the fault is eliminated, the step 0-step 2 process is repeated.

4. The elevator power failure self-rescue brake pipe control method according to claim 1 is characterized in that: The control process of making the elevator work in a low-power power generation state and in a power generation direction includes accurately setting the parameters of the torque and speed of the elevator motor to convert the potential energy of the car and the counterweight into electrical energy and process it in the form of low-power power generation within the elevator system.

5. The elevator power failure self-rescue brake pipe control method according to claim 1 is characterized in that: In the control mode in which the outer loop is the bus voltage loop and the inner loop is the direct-axis current loop, the bus voltage loop monitors the bus voltage in real time and transmits the voltage deviation signal to the direct-axis current loop of the inner loop. The direct-axis current loop accurately controls the direct-axis current of the motor according to the received signal, so that the generated energy is reversely transmitted to the motor coil and consumed in the form of heat energy.

6. The elevator power failure self-rescue brake pipe control method according to claim 1, characterized in that: The chopping mode controls the switch tube to consume large energy by using a small-sized brake resistor, and adapts the bus voltage to the tolerance range of the small-sized brake resistor by adjusting the duty cycle Duty.

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