Two-channel brake control circuit

Abstract

The present invention discloses a two-channel brake control circuit, comprising: a main circuit, including a fuse and two switching devices connected in series therewith, each switching device being able to disconnect the output of the main circuit when disconnected; two channels, each channel being used to obtain an external safety signal and output a drive signal according to a preset logic to control the conduction or shutdown of the switching device; a first inspection circuit, being used to diagnose the short-circuit status of each channel and respond according to a preset solution; and a second inspection circuit, being a circuit for detecting the function of the first inspection circuit.

Description

Technical Field

[0001] The present invention relates to the field of elevators, and in particular to a two-channel brake control circuit. Background Art

[0002] Elevator brake control circuits typically use contactors to cut off the brake current. In today's increasingly competitive elevator market, contactors, with their high price and large size, are hindering further improvements in elevator brake control solutions.

[0003] With the update and revision of the national elevator standard, the use of safety circuits to cut off the brake current has been allowed. Therefore, it is necessary to develop safety circuits that comply with national standards for elevator brake control. The implementation of safety circuits can be roughly divided into two technical routes: dual-channel and three-channel. For dual-channel safety circuits, the following are some excerpts from "GB / T 7588.1—2020 Safety Code for Elevator Manufacturing and Installation Part 1: Passenger and Freight Elevators":

[0004] A first check circuit is used to check the same status of each channel. If a different status is detected, the elevator should be stopped. ...The function of the first check circuit should be checked at the latest before restarting the elevator. If the function fails, restarting the elevator should not be possible. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a two-channel brake control circuit which can meet the requirements of elevator specifications for brake control circuits and realize safe control of the brake.

[0006] In order to solve the above technical problems, the present invention discloses a two-channel brake control circuit, comprising:

[0007] A main circuit, comprising a fuse and two switching devices connected in series therewith, wherein each switching device can disconnect the output of the main circuit when disconnected;

[0008] Two channels, each channel is used to obtain an external safety signal and output a drive signal according to a preset logic to control the on or off of the switching device;

[0009] The first inspection circuit is used to diagnose the short circuit status of each channel and respond according to the preset plan;

[0010] The second inspection circuit is a circuit used to detect the function of the first inspection circuit.

[0011] Preferably, the external safety signal includes an elevator safety circuit signal, an elevator main control circuit signal, a first inspection circuit fault signal, and a second inspection circuit fault signal;

[0012] When any of the above signals fails, the main circuit has no output;

[0013] When the first inspection circuit fault signal output by the first inspection circuit is inconsistent with the second inspection circuit fault signal output by the second inspection circuit, the two-channel brake control circuit turns off the drive output.

[0014] Preferably, the first inspection circuit or the second inspection circuit includes:

[0015] Channel diagnostic circuit, used for diagnosing channel short circuit;

[0016] The response logic circuit responds according to a preset solution after the channel diagnosis circuit diagnoses that a channel failure has occurred.

[0017] Preferably, the channel diagnostic circuit includes:

[0018] A switch device conduction detection device that is turned on or off synchronously with the switch device;

[0019] A driving voltage output detection device, wherein when the driving voltage is output, the driving voltage output detection device is turned on;

[0020] The output signal of the channel diagnosis circuit is a low level signal only when the switch device conduction detection device is turned on and the drive voltage output detection device is not turned on.

[0021] Preferably, the preset scheme is:

[0022] When a short circuit fault occurs in any channel, the logic circuit should output the fault and latch it.

[0023] Preferably, the response logic circuit includes:

[0024] two corresponding logic devices, wherein the output signals of the channel diagnostic circuits of the two channels are input to the respective corresponding logic devices;

[0025] a thyristor, configured to receive an output signal of the response logic device;

[0026] Only when the output signals of all channel diagnostic circuits are at a high level, all corresponding logic devices are turned on, and the thyristor will not receive the output drive signal; as long as the output signal of any channel diagnostic circuit is at a low level, the series circuit where the corresponding logic device is located will be disconnected, the thyristor will receive the drive signal and turn on, and the first inspection circuit fault signal will be invalid.

[0027] Preferably, the preset scheme is:

[0028] When short circuit faults occur in two channels at the same time, the output of the logic circuit should be hard shut down.

[0029] Preferably, the response logic circuit includes:

[0030] Three hard-off devices, the main circuit output end, the elevator safety circuit signal, and the elevator main control circuit signal are respectively input into the hard-off devices;

[0031] When the output end of the main circuit is energized, if any input signal of the elevator safety circuit signal or the elevator main control circuit signal is low, the series output circuit will be disconnected to blow the fuse.

[0032] The present invention also discloses a two-channel brake control circuit, comprising:

[0033] A main circuit, comprising a fuse and two switching devices connected in series therewith, wherein each switching device can disconnect the output of the main circuit when disconnected;

[0034] Two channels, each channel is used to obtain an external safety signal and output a drive signal according to a preset logic to control the on or off of the switching device;

[0035] When the opening and closing state of any channel of the first inspection circuit or the second inspection circuit is inconsistent with that of other channels, the first inspection circuit outputs a fault and latches.

[0036] Preferably, the first inspection circuit includes four inspection devices, wherein:

[0037] The first inspection device and the second inspection device are synchronously turned on corresponding to the two switching devices;

[0038] The third inspection device and the fourth inspection device are disconnected synchronously with the two switching devices;

[0039] When the conduction state of any one inspection device is inconsistent with that of other devices, the first inspection circuit turns off the driving outputs of all channels.

[0040] The technical effects of the present invention are as follows:

[0041] A "monitoring circuit" (also referred to as the first checking circuit in this article) is used to check that "no dangerous failure has occurred in any channel". If a dangerous failure (i.e., short circuit) occurs in any channel, a monitoring signal (i.e., fault signal) is output and latched, causing the elevator to stop;

[0042] A "check circuit" (herein referred to as the second check circuit) is used to check the function of the aforementioned "monitoring circuit" (i.e., the first check circuit). This is a mirror circuit of the "monitoring circuit." The second check circuit (i.e., the mirror circuit) operates on the same principle as the first check circuit and independently outputs a check signal. If the check signal from the second check circuit is the same as the check signal output by the first check circuit, the first check circuit is considered to be functioning properly. Otherwise, the first check circuit is considered to be faulty, causing the elevator to stop and become unable to restart. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings herein are intended to illustrate the general characteristics of methods, structures, and / or materials used in certain exemplary embodiments of the present invention, supplementing the descriptions in the specification. However, the drawings herein are schematic diagrams not drawn to scale and may not accurately reflect the precise structure or performance characteristics of any given embodiment. The drawings herein should not be interpreted as defining or limiting the range of values ​​or properties encompassed by the exemplary embodiments of the present invention. The present invention is further described in detail below in conjunction with the drawings and specific embodiments:

[0044] Figure 1 This is a diagram of the overall system architecture of the first embodiment of the present invention;

[0045] Figure 2 Schematic diagram of the main circuit and channels of the first embodiment of the present invention;

[0046] Figure 3-Figure 5 This is a schematic diagram of a first inspection circuit according to a first embodiment of the present invention;

[0047] Figure 6-Figure 8 This is a schematic diagram of a second inspection circuit according to the first embodiment of the present invention;

[0048] Figure 9 Schematic diagram of the main circuit and channels of the second embodiment of the present invention;

[0049] Figure 10-11 This is a schematic diagram of a first inspection circuit and a second inspection circuit according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0050] Example 1

[0051] Table 1 shows the fault response of the brake control circuit of this embodiment.

[0052] Table 1. Failure mode analysis and solutions for dual-channel embodiment 1

[0053] Failure Mode Monitoring output Coping methods Risk Assessment Two channels are normally conducting normal - Safety Two channels are normally shut down normal - Safety One channel is open circuit fault, the rest are normal normal - Safety Two-channel open circuit fault normal - Safety One channel is short-circuited, the rest are normal Fault Locking drive Safety Both channels are short-circuited or incorrectly connected Fault Burnt fuse Safety

[0054] like Figure 1As shown, the system structure of the brake control circuit of this embodiment includes a fuse, two channels, a first inspection circuit, a second inspection circuit for inspecting the function of the first inspection circuit, and a trunk circuit.

[0055] A channel is a pathway through which safety signals flow and ultimately control the output of switching devices. A channel's function is to receive external safety signals (fault signals generated by the safety circuit's internal monitoring circuitry are also considered "external" safety signals and are treated similarly). It then outputs corresponding switching device drive signals to turn on or off the switching devices (in this case, power semiconductors) and control the brake circuit output. Each channel receives the same safety input signal or signals, and any channel can independently shut down the brake circuit output.

[0056] The channel consists of a sensor, logic unit, actuator, and switching device for obtaining external safety signals. When the external safety signal changes, the state of the switching device changes accordingly, thereby achieving control of the safety loop output.

[0057] The sensor receives the external safety signals 41DG and DLB of the elevator trunk circuit and the fault signal (ERROR) generated by the inspection circuit (herein, the first inspection circuit and the second inspection circuit) A and ERROR B ).

[0058] 41DG: Elevator safety circuit signal, generated by the elevator safety circuit. When any safety contact is disconnected, the safety circuit is disconnected, the 41DG signal fails (ie, power is lost), and the main circuit should have no output; when the 41DG signal is valid, the main circuit is inoperative when other conditions are met (DLB, ERROR A and ERROR B The brake will be released only when all signals are normal.

[0059] DLB: The main control circuit signal, generated by the elevator main control circuit. When the elevator needs to run, the elevator controller sends a DLB signal to control the brake. When the DLB signal fails (i.e. power is off), the main circuit should have no output; when the DLB signal is valid, the main circuit will stop when other conditions are met (41DG, ERROR A and ERROR B The brake will be released only when all signals are normal.

[0060] ERROR A :The fault signal output by the first inspection circuit (i.e. the "monitoring circuit" mentioned above). A The signal fails (i.e., power is lost, indicating a fault), and the main circuit should have no output; ERROR AWhen the signal is valid, the trunk circuit meets other conditions (41DG, DLB and ERROR B The brake will be released only when all signals are normal.

[0061] ERROR B :The fault signal output by the second inspection circuit (i.e. the “inspection circuit” mentioned above). B The signal fails (i.e., power is lost, indicating a fault), and the main circuit should have no output; ERROR B When the signal is valid, the trunk circuit meets other conditions (41DG, DLB and ERROR A The brake will be released only when all signals are normal.

[0062] The logic implemented by the logic unit is: if any of the above signals fails, the channel is shut down (by shutting down the drive output of the power switch device of the channel), and then shutting down the safety circuit output. In addition, in this embodiment, each channel receives the same two safety input signals (41DG and DLB), and also receives the monitoring fault signal (ERROR A ), and also receives a check fault signal (ERROR B If any of the above signals fails, the channel will be shut down (by shutting down the drive output of the power switch device of the channel), and then shutting down the safety circuit output.

[0063] The output logic design of the logic unit is shown in Table 2.

[0064] Table 2. Dual-channel embodiment. Channel 1 output logic: Y = A·B·C·D

[0065]

[0066]

[0067] The actuator outputs a drive voltage to the control terminal of the switching device (i.e., the MOSFET gate) based on the signal generated by the logic unit. When the actuator outputs the drive voltage, the switching device will turn on, otherwise it will turn off.

[0068] The switch device is turned on or off according to the driving voltage output by the actuator.

[0069] The actual circuit design of the channel is as follows Figure 2 shown.

[0070] In the main circuit, a fuse FS1 is configured, and the fuse and two power switching devices Q1 and Q2 are connected in series in sequence.

[0071] Figure 2In the figure, BKPW is the positive brake power supply, and BKGND is the negative brake power supply. The power switching device is MOSFET (IGBT or similar devices are also acceptable). Each MOSFET has its own drive circuit and power supply. To simplify the core circuit, auxiliary circuits such as the drive power supply are omitted here.

[0072] Taking channel 1 where the first switch device Q1 is located as an example, 41DG, DLB, ERROR are required. A and ERROR B Only when all four signals are high (valid) and the four optocouplers U1-U4 are turned on simultaneously, will TR1 start to output the Drive1 drive signal. The drive design for other channels is the same as above.

[0073] The functions of the first inspection circuit include three parts: the first part is used to realize the diagnosis of channel short circuit; the second part is mainly the response logic of using the control signal of the switching device to turn off the switching device after the first part diagnoses that the channel has a short circuit fault (i.e. soft shutdown); the third part is used to deal with the scenario where short circuit faults occur in each channel at the same time and / or drive circuit faults occur in each channel at the same time, resulting in the switching device being incorrectly turned on (hard shutdown).

[0074] The diagnostic logic of the first part of the first inspection circuit is: when the switch device is in an unexpected conduction state, the switch device is diagnosed as being in a fault state. The logic is shown in Table 3.

[0075] Table 3. Dual-channel embodiment 1 channel diagnostic logic:

[0076] A B Y <![CDATA[Drive output Drive x > <![CDATA[Switch conduction monitoring Diag x > <![CDATA[Output diagnosis Error xA > 1 output driver 1 switch is on 1Normal X 0 switch off 1Normal 0 turns off the driver 1 switch is on 0 failures

[0077] Note: The subscript "x" in the above table refers to the channel, such as channel 1, channel 2, and similarly in the following.

[0078] The specific circuit design that can realize the logical functions in Table 3 is as follows Figure 3 As shown in Figure 1, the diagnostic circuit needs to detect whether the switch device has a dangerous failure, that is, whether the conduction state is inconsistent with the expected state. Figure 3 Taking the first switch device as an example, its working principle is explained as follows:

[0079] (1) Optocoupler U5, i.e. switch device conduction detection device, is used to detect whether the switch device is conducting:

[0080] When the device is turned on, the potential of D1 is basically the same as the potential of S1, except for the internal resistance R DSON Therefore, when the device is turned on, the U5 optocoupler is also turned on, and vice versa.

[0081] (2) Optocoupler U6, which is a driving voltage output detection device, is used to detect whether the device drives the output:

[0082] When the drive output is on, the drive voltage signal Drive1 has a signal potential that is equal to the drive power supply V g1 Basically the same, the optocoupler U6 is turned on at the same time, and vice versa.

[0083] (3) Only when U5 is on (device is on) and U6 is not on (device gate is not driven), the output signal of the channel diagnostic circuit is Error 1A Only then will a low level signal be output, indicating that the device is diagnosed as a fault. Otherwise, Error 1A Outputs a high-level signal, indicating that the device is diagnosed as normal.

[0084] The diagnostic logic of the second part of the first check circuit is:

[0085] If any channel is diagnosed as faulty, an independent comprehensive fault is output and latched. The logic is shown in Table 4.

[0086] Table 4. Dual-channel embodiment 1 soft shutdown output logic: Y = A·B

[0087]

[0088] The specific circuit design that can realize the logical functions in Table 4 is as follows Figure 4 As shown in Figure 1, the function that the circuit needs to achieve is: when any channel diagnoses a dangerous failure, it immediately shuts down the drive output and latches the fault. The specific implementation circuit is as follows: Figure 4 shown.

[0089] The circuit includes multiple coping logic devices, Figure 4 In the figure, U7 is the first corresponding logic device and U8 is the second corresponding logic device. In this embodiment, the first corresponding logic device and the second corresponding logic device are both optocouplers, but they can also be other devices.

[0090] Only Error 1A -Error 2A When both diagnostic signals are high (channel normal), both optocouplers are turned on and SCR1 will not receive the drive signal; on the contrary, as long as any diagnostic signal is low (channel short circuit), the series circuit where the optocoupler output is located will be disconnected, and the thyristor SCR1 will receive the drive signal. After SCR1 is turned on, ERROR A The signal is continuously pulled low (making ERROR A The signal fails and the drive output of all channels is turned off. Due to the characteristics of thyristor devices, they will not return to the off state until the power is turned off and restarted. Otherwise, the fault signal will continue to be output, thus realizing the fault latch function.

[0091] The diagnostic logic of the third part of the first check circuit is:

[0092] If both channels have a short circuit fault, even if the drive output is turned off, the switch device cannot be turned off; or when the drive circuit of both channels fails and the drive signal is incorrectly given, even if the switch device is not short-circuited, the safety circuit output cannot be cut off.

[0093] To address this particular scenario, the brake control circuit of the present invention incorporates an automatic fusing function. This function shuts down the output by blowing a fuse (a circuit breaker is also possible, but this article uses a fuse as an example). This method can be considered a hard shutdown. Because a blown fuse requires on-site replacement, this function is only triggered in the most extreme circumstances.

[0094] The logic of hard shutdown is as follows:

[0095] a) The fault output of the soft shutdown function cannot trigger this function. For example, if only one or two channels are short-circuited, it will only lock the drive output and will not blow the fuse;

[0096] b) Executed only when the final output RLB signal is inconsistent with the safety input signal 41DG / DLB.

[0097] Table 5. Hard shutdown logic:

[0098] A B C Y Enter 41DG Enter DLB Output RLB Fuse blown 1Normal 1Normal 1 conduction 0 No melting 0 exceptions X 1 conduction 1 fuse X 0 exceptions 1 conduction 1 fuse X X 0 failures 0 No melting

[0099] The specific circuit design that can realize the logical functions in Table 5 is as follows Figure 5 As shown, when the main circuit output signal RLB is inconsistent with the elevator safety circuit signal 41DG and the elevator main control circuit signal DLB, the hard shutdown circuit will burn the fuse to deal with the extreme situation of both channels being short-circuited or all being falsely connected.

[0100] Figure 5 When the main circuit output terminal RLB is powered, the first hard-off device U9 is turned on. At this time, if any input signal of 41DG or DLB is low, the second hard-off device U 10 and the third hard-off device U 11 The series output loop will be disconnected, and SCR2 will be driven by BKPW through the output terminal of U9. The resistor must be configured as a power resistor to blow the fuse.

[0101] The function of the second inspection circuit is the same as that of the first inspection circuit, and will not be described in detail here. Figure 6-Figure 8 The signals in the figure are named with subscripts A / B. A Output signal of the first inspection circuit, ERROR B This is the output signal of the second check circuit. If the two signals are inconsistent, the device will not be turned on.

[0102] Example 2

[0103] The system architecture of the brake control circuit of this embodiment is as follows Figure 9 The fault response is shown in Table 6.

[0104] Table 6. Failure mode analysis and solutions for dual-channel embodiment 2

[0105] Failure Mode Monitoring output Coping methods Risk Assessment Two channels are normally conducting normal - Safety Two channels are normally shut down normal - Safety One channel is open circuit fault, the rest are normal Fault Locking drive Safety Two-channel open circuit fault normal - Safety One channel is short-circuited, the rest are normal Fault Locking drive Safety Both channels are short-circuited or incorrectly connected Fault Burnt fuse Safety

[0106] This embodiment is similar to embodiment 1, and only the differences are described below.

[0107] The soft switching logic of the first inspection circuit of this embodiment is: if the opening and closing state of any channel is inconsistent with that of other channels, a fault is output and latched, as shown in Table 7.

[0108] Table 7. Soft shutdown output logic for dual-channel embodiment 2:

[0109]

[0110]

[0111] Accordingly, the circuit design is as follows Figure 10 shown.

[0112] The first inspection circuit includes a first inspection device U 12 , the second inspection device U 13 , the third inspection device U 14 , and the fourth inspection device U 15 In this embodiment, the above-mentioned monitoring response devices are all optocouplers. Of course, other devices can also be selected.

[0113] When both MOSFETs Q1-Q2 are turned on, the drain D and source S potentials of each device are almost the same, so the optocoupler U 12 ~U 13 All are turned on, and the base of TR3 is connected to U 12 ~U 13 The output current is turned on, SCR5 is turned off, ERROR A Output high level (indicates normal status);

[0114] When both MOSFETs Q1-Q2 are turned off, the drain D and source S of each device are disconnected, so the optocoupler U 14 ~U 15 All are turned off, and the base of TR3 is connected to U 14 ~U 15 The output circuit is turned on, SCR5 is turned off, ERRORA Output high level (indicating normal status).

[0115] When the conduction state of any device is inconsistent with that of other devices, TR3 will not be able to conduct. At this time, SCR5 will receive the driving signal and ERROR will be displayed after SCR5 conducts. A The signal is continuously pulled low (turning off the driver output of all channels). The fault latch function is implemented.

[0116] The function of the second inspection circuit is the same as that of the first inspection circuit, and will not be described in detail here. Figure 11 When naming the signals in the figure, they are distinguished by the subscripts A / B. A Output signal of the first inspection circuit, ERROR B Output signal for the second inspection circuit.

[0117] In addition, it should be understood that, although the terms "first," "second," etc. may be used herein to describe different elements, parameters, components, regions, layers, and / or parts, these elements, parameters, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, parameter, component, region, layer, or part from another element, parameter, component, region, layer, or part. Therefore, without departing from the teachings of exemplary embodiments of the present invention, the first element, parameter, component, region, layer, or part discussed below may also be referred to as a second element, parameter, component, region, layer, or part.

Claims

1. A two-channel brake control circuit, characterized in that: include: A main circuit, comprising a fuse and two switching devices connected in series therewith, wherein each switching device can disconnect the output of the main circuit when disconnected; Two channels, each channel is used to obtain an external safety signal and output a drive signal according to a preset logic to control the on or off of the switching device; The first inspection circuit is used to diagnose the short circuit status of each channel and respond according to the preset plan; A second inspection circuit for detecting a circuit functioning as the first inspection circuit; The external safety signal includes an elevator safety circuit signal, an elevator main control circuit signal, a first inspection circuit fault signal, and a second inspection circuit fault signal; When any of the above signals fails, the main circuit has no output; When the first inspection circuit fault signal output by the first inspection circuit is inconsistent with the second inspection circuit fault signal output by the second inspection circuit, the two-channel brake control circuit shuts off the drive output; The first inspection circuit or the second inspection circuit includes: Channel diagnostic circuit, used for diagnosing channel short circuit; The response logic circuit responds according to a preset solution after the channel diagnosis circuit diagnoses that a channel fault has occurred. The channel consists of sensors, logic units, actuators and switching devices used to obtain external safety signals.

2. The two-channel brake control circuit according to claim 1, characterized in that: Channel diagnostic circuitry includes: A switch device conduction detection device that is turned on or off synchronously with the switch device; A driving voltage output detection device, wherein when the driving voltage is output, the driving voltage output detection device is turned on; The output signal of the channel diagnosis circuit is a low level signal only when the switch device conduction detection device is turned on and the drive voltage output detection device is not turned on.

3. The two-channel brake control circuit according to claim 2, characterized in that: The preset scheme is: When a short circuit fault occurs in any channel, the logic circuit should output the fault and latch it.

4. The two-channel brake control circuit according to claim 3, characterized in that: The response logic circuit includes: two corresponding logic devices, wherein the output signals of the channel diagnostic circuits of the two channels are input to the respective corresponding logic devices; a thyristor, configured to receive an output signal of the response logic device; Only when the output signals of all channel diagnostic circuits are at a high level, all corresponding logic devices are turned on, and the thyristor will not receive the output drive signal; as long as the output signal of any channel diagnostic circuit is at a low level, the series circuit where the corresponding logic device is located will be disconnected, the thyristor will receive the drive signal and turn on, and the first inspection circuit fault signal will be invalid.

5. The two-channel brake control circuit according to claim 1, characterized in that: The preset scheme is: When short circuit faults occur in two channels at the same time, the output of the logic circuit should be hard shut down.

6. The two-channel brake control circuit according to claim 5, characterized in that: The response logic circuit includes: Three hard-off devices, the main circuit output end, the elevator safety circuit signal, and the elevator main control circuit signal are respectively input into the hard-off devices; When the output end of the main circuit is energized, if any input signal of the elevator safety circuit signal or the elevator main control circuit signal is low, the series output circuit will be disconnected to blow the fuse.

7. The two-channel brake control circuit according to claim 1, characterized in that: The first inspection circuit includes four inspection devices, wherein: The first inspection device and the second inspection device are synchronously turned on corresponding to the two switching devices; The third inspection device and the fourth inspection device are disconnected synchronously with the two switching devices; When the conduction state of any one inspection device is inconsistent with that of other devices, the first inspection circuit turns off the driving outputs of all channels.

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