Elevator traction machine current monitoring method and monitoring system

Abstract

The invention discloses a current monitoring method and monitoring system for an elevator traction machine, and the method comprises the following steps: converting the current iac of the traction machine into a voltage signal vi, and amplifying the voltage signal vi to obtain an output signal v1; amplifying the output signal v1 based on the amplification coefficient Kv and biasing the output signal v1 by 2.5 V to obtain an output signal v2; the output signal v2 is compared with the maximum reference value # imgabs0 # and the minimum reference value # imgabs1 #, and the amplification factor Kv of the output signal v2 is adjusted according to the comparison result; and the current value of the elevator traction machine is calculated according to the amplification factor Kv of the output signal v2. According to the invention, the monitoring accuracy of the current of the traction machine can be improved.

Description

Technical Field

[0001] The present invention relates to the field of elevators, and particularly to a method and a monitoring system for monitoring the current of an elevator traction machine. Background Art

[0002] With the rapid development of the urbanization process, elevators of different models and power ratings are widely used in residential communities, commercial buildings, industrial and mining enterprises. Their operating status is directly related to people's life safety. As the power source of an elevator, the safe operation of an elevator traction machine is of utmost importance. In order to ensure the safe operation of an elevator, it is necessary to monitor the current of the elevator traction machine and analyze this current to judge the operating condition of the elevator traction machine.

[0003] On this basis, the existing method for monitoring the current of an elevator traction machine is that a current sensor monitors the elevator traction machine to generate a sampled current, then an amplifier circuit amplifies the sampled current and outputs it, and finally a sampling system calculates according to the output signal to obtain the final current value. However, the defect of this monitoring method is that the current change range of the elevator traction machine during operation is very large, and when the traction machine is in the standby state, the traction machine current is relatively small, resulting in an enhanced noise interference when the amplifier circuit outputs a signal, affecting its monitoring accuracy; when the traction machine is in the full-load state, the output current of the traction machine will increase significantly, and it is easy to cause saturation distortion when the amplifier circuit outputs a voltage, affecting its monitoring accuracy.

[0004] Under the above limitations, the monitoring results of the existing current sensing system for the traction machine current are not accurate. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and a monitoring system for monitoring the current of an elevator traction machine. It can improve the monitoring accuracy of the traction machine current.

[0006] The technical solution of the present invention: A method for monitoring the current of an elevator traction machine includes the following steps:

[0007] ① Convert the traction machine current i ac into a voltage signal v i , and amplify the voltage signal v i to obtain an output signal v1;

[0008] ② Based on the amplification factor K v amplify the output signal v1 and bias it by 2.5V to obtain an output signal v2;

[0009] ③ Compare the output signal v2 with the maximum reference value and the minimum reference value , and adjust the amplification multiple K v of the output signal v2 according to the comparison result;

[0010] ④According to the amplification factor K of the output signal v2 v Calculate the current value of the elevator traction machine.

[0011] In the aforementioned method for monitoring the current of an elevator traction machine, the output signal v2 is calculated according to the formula v2 = 2.5 + K v v1.

[0012] Based on the monitoring system used in the aforementioned method for monitoring the current of an elevator traction machine, it includes a current-to-voltage module, a DC bias circuit, a variable gain amplifier circuit module, and a gain control module;

[0013] The current-to-voltage module includes a shunt resistor and a differential amplifier. The shunt resistor is used to convert the traction machine current i ac into a voltage signal v i , and the differential amplifier is used to amplify the voltage signal v i to obtain an output signal v1;

[0014] The DC bias circuit is used to generate a high-precision 2.5V DC voltage;

[0015] The variable gain amplifier circuit module is used to amplify the output signal v1 and DC bias it by 2.5V to obtain an output signal v2;

[0016] The gain control module includes a signal amplitude discrimination circuit and a gain control logic circuit. The signal amplitude discrimination circuit is used to compare the output signal v2 with the maximum reference value and the minimum reference value and output a signal to the gain control logic circuit according to the comparison result; the gain control logic circuit is used to adjust the gain of the variable gain amplifier circuit module according to the signal output by the signal amplitude discrimination circuit.

[0017] In the aforementioned monitoring system, the shunt resistor calculates the voltage signal v according to the formula v i = i ac R shunt to obtain the voltage signal v i , where R shunt is the resistance value of the shunt resistor, and the output signal v1 is calculated by the formula v1 = k DP v i where k DP is the differential gain of the differential amplifier.

[0018] In the aforementioned monitoring system, when the signal amplitude discrimination circuit compares the output signal v2, if the output signal v2 is greater than the maximum reference value Then a rising edge signal is generated. If the output signal v2 is less than the minimum reference value When it is, a falling edge signal is generated. If the output signal v2 is at the minimum reference value and the maximum reference value between, the output level of the signal amplitude discrimination circuit remains unchanged.

[0019] In the aforementioned monitoring system, the adjustment method of the amplification factor control logic circuit is specifically as follows:

[0020] When the amplification factor control logic circuit receives the rising edge signal of the signal amplitude discrimination circuit, it reduces the amplification factor of the variable amplification factor circuit module;

[0021] When the amplification factor control logic circuit receives the falling edge signal of the signal amplitude discrimination circuit, it increases the amplification factor of the variable amplification factor circuit module.

[0022] In the aforementioned monitoring system, a feedback resistor component is provided in the variable amplification factor circuit module, and the amplification factor control logic circuit changes the amplification factor of the variable amplification factor circuit module by adjusting the resistance value of the feedback resistor component.

[0023] In the aforementioned monitoring system, the feedback resistor component includes a plurality of resistors connected in parallel in the variable amplification factor circuit module, and the amplification factor control logic circuit adjusts the feedback resistor component by connecting resistors with different resistance values into the variable amplification factor circuit module.

[0024] Compared with the prior art, by defining the current monitoring method, the present invention can adjust the amplification factor K of the circuit according to the magnitude of the traction machine current i ac so as to effectively prevent the problems of overheating and saturation distortion of the current sensing system of the traction machine caused by excessive traction machine current, realize high-precision measurement of the traction machine current within the entire current range, and improve the monitoring accuracy of the traction machine current. v BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the connection circuit diagram of the amplification factor control logic circuit;

[0026] Figure 2 is the connection circuit diagram of the current-to-voltage module, the DC bias circuit, the variable amplification factor circuit module, and the signal amplitude discrimination circuit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present invention will be further described below with reference to the drawings and embodiments, but it shall not be used as a basis for limiting the present invention.

[0028] Embodiment 1. A method for monitoring the current of an elevator traction machine includes the following steps:​

[0029] ①Convert the traction machine current i ac into a voltage signal v i , and amplify the voltage signal v i to obtain an output signal v1;

[0030] ②Based on the amplification factor K v amplify the output signal v1 and bias it by 2.5V to obtain an output signal v2;

[0031] ③Compare the output signal v2 with the maximum reference value and the minimum reference value , and adjust the amplification factor K v of the output signal v2 according to the comparison result;

[0032] ④Calculate the current value of the elevator traction machine according to the amplification factor K v of the output signal v2.

[0033] In the above-mentioned elevator traction machine current monitoring method, the output signal v2 is calculated according to the formula v2 = 2.5 + K v v1.

[0034] In this embodiment, by limiting the monitoring method of the output signal v2, when the traction machine current i ac is too small, its output signal v2 can be increased by increasing its amplification factor K v ; and when the traction machine current i ac is too large, its output signal v2 can be reduced by reducing its amplification factor K v , so that the output signal of the system is always within a reasonable linear range, effectively preventing the error of the monitoring system during output caused by the traction machine current i ac being too large or too small, and improving its monitoring accuracy.

[0035] Embodiment 2. The monitoring system is configured as shown in Figure 1 and 2 , and is used to implement the elevator traction machine current monitoring method in Embodiment 1. The monitoring system includes a current-to-voltage conversion module, a DC bias circuit, a variable gain amplifier circuit module, and an amplification factor control module;

[0036] The current-to-voltage conversion module includes a shunt resistor R shunt and a differential amplifier U1. The shunt resistor R shunt is connected in series on the elevator traction machine power line and is used to convert the traction machine current i i into a voltage signal v according to the formula v ac = i shunt R ac into a voltage signal vi The differential amplifier U1 is used to amplify the voltage signal v by the formula v1 = k DP v i to obtain the output signal v1, where k i is the differential amplification factor of the differential amplifier; DP

[0037] The DC bias circuit consists of a voltage reference chip TL431 and a current-limiting resistor R11. The two ends of the current-limiting resistor R11 are connected between the power supply VCC and the cathode of the voltage reference chip TL431. The cathode and the reference electrode of the voltage reference chip TL431 are connected together, and the anode is grounded. The reference electrode of the voltage reference chip TL431 is used to generate a high-precision 2.5V DC voltage;

[0038] The variable gain amplifier circuit module is used to amplify the output signal v1 and DC bias it by 2.5V to obtain the output signal v2. The amplification factor K of the variable gain amplifier circuit module v is determined by the magnitude of the traction machine current i ac . The external of the variable gain amplifier circuit module is connected to the sampling system, and the sampling system calculates the current value of the elevator traction machine according to the received output signal v2.

[0039] ​Specifically, the variable magnification circuit module includes resistors R1 - R10, NMOS transistors M1 - M8, and operational amplifier U2, where R1 = R10, R2 = R9, R3 = R8, R4 = R7, R5 = R6. After the resistors R1 - R10 and NMOS transistors M1 - M8 are connected, they form a feedback resistor component. Resistor R1 and NMOS transistor M1 are connected in series between 2.5V and the non-inverting input terminal of operational amplifier U2, and the gate of NMOS transistor M1 is connected to the P0 terminal of bidirectional shift register U7. Resistor R2 and NMOS transistor M2 are connected in series between 2.5V and the non-inverting input terminal of operational amplifier U2, and the gate of NMOS transistor M2 is connected to the P1 terminal of bidirectional shift register U7. Resistor R3 and NMOS transistor M3 are connected in series between 2.5V and the non-inverting input terminal of operational amplifier U2, and the gate of NMOS transistor M3 is connected to the P2 terminal of bidirectional shift register U7. Resistor R4 and NMOS transistor M4 are connected in series between 2.5V and the non-inverting input terminal of operational amplifier U2, and the gate of NMOS transistor M4 is connected to the P3 terminal of bidirectional shift register U7. Resistor R5 is connected between the output terminal of operational amplifier U1 and the non-inverting input terminal of operational amplifier U2. Resistor R6 is connected between the inverting input terminal of operational amplifier U2 and ground. Resistor R7 and NMOS transistor M5 are connected in series between the inverting input terminal of operational amplifier U2 and the output signal v2 of operational amplifier U2, and the gate of NMOS transistor M5 is connected to the P3 terminal of bidirectional shift register U7. Resistor R8 and NMOS transistor M6 are connected in series between the inverting input terminal of operational amplifier U2 and the output signal v2 of operational amplifier U2, and the gate of NMOS transistor M6 is connected to the P2 terminal of bidirectional shift register U7. Resistor R9 and NMOS transistor M7 are connected in series between the inverting input terminal of operational amplifier U2 and the output signal v2 of operational amplifier U2, and the gate of NMOS transistor M7 is connected to the P1 terminal of bidirectional shift register U7. Resistor R10 and NMOS transistor M8 are connected in series between the inverting input terminal of operational amplifier U2 and the output signal v2 of operational amplifier U2, and the gate of NMOS transistor M8 is connected to the P0 terminal of bidirectional shift register U7.

[0040] Through the variable magnification circuit module, the output signal v2 and the output signal v1 satisfy the formula v2 = 2.5 + K v v1; K v is the magnification of the variable magnification circuit module, satisfying the formula

[0041]

[0042] On this basis, different magnifications can be achieved by reasonably selecting the relationship between the resistance values of R1 - R5. For example, if magnifications of 200, 50, 10, and 1 are expected to be achieved, then set R1 = 200R5, R2 = 50R5, R3 = 10R5, and R4 = R5.

[0043] The magnification control module includes a signal amplitude discrimination circuit and a magnification control logic circuit. The signal amplitude discrimination circuit is used to compare the output signal v2 with the maximum reference value and the minimum reference value and output a signal to the magnification control logic circuit according to the comparison result. The magnification control logic circuit is used to adjust the magnification of the variable magnification amplifier circuit module according to the signal output by the signal amplitude discrimination circuit;

[0044] Specifically, the signal amplitude discrimination circuit includes operational amplifier U3, operational amplifier U4, resistor R12, and resistor R13. Operational amplifier U3 is a voltage follower, and the non-inverting input terminal of operational amplifier U3 is connected to the signal v2 at the output terminal of operational amplifier U2. Resistor R12 is connected between the output terminal of operational amplifier U3 and the non-inverting input terminal of operational amplifier U4. Resistor R13 is connected between the non-inverting input terminal of operational amplifier U4 and the output signal v3 of operational amplifier U4. The inverting input terminal of operational amplifier U4 is connected to 2.5V. Among them, resistor R12, resistor R13, and operational amplifier U4 form a hysteresis comparator, and this hysteresis comparator has two voltage comparison reference points, namely the maximum reference value and the minimum reference value respectively satisfying:

[0045]

[0046] When the signal amplitude discrimination circuit compares the output signal v2, if the output signal v2 is greater than the maximum reference value it indicates that the magnification of the current variable magnification amplifier circuit module is too large, and the output signal after the traction machine current i ac is amplified is about to saturate, and the signal amplitude discrimination circuit generates a rising edge signal;

[0047] If the output signal v2 is less than the minimum reference value it indicates that the output signal of the traction machine current i ac after amplification is very small, and the signal amplitude discrimination circuit generates a falling edge signal;

[0048] If the output signal v2 is between the minimum reference value and the maximum reference value the output level of the signal amplitude discrimination circuit remains unchanged.

[0049] The magnification control logic circuit includes two-input AND gates G1 and G2, NOT gates G3 and G4, Schmitt triggers G5 and G6, a two-input OR gate G7, a rising-edge D flip-flop U5, a falling-edge D flip-flop U6, a capacitor C1, a resistor R14, and a bidirectional shift register U7. The model number of the bidirectional shift register is 74LS194. The two inputs of the two-input AND gate G1 are respectively connected to the output signal v3 and the output terminal of the NOT gate G3. The output terminal of the two-input AND gate G1 is connected to the clock pulse terminal CP of the rising-edge D flip-flop U5. The two inputs of the two-input AND gate G2 are respectively connected to the output signal v3 and the output terminal of the NOT gate G4. The output terminal of the two-input AND gate G2 is connected to the clock pulse terminal CP of the falling-edge D flip-flop U6. The input terminal of the NOT gate G3 is connected together with the right-shift serial data input terminal DSR of the bidirectional shift register U7 and the output terminal Q3 of the bidirectional shift register U7. The input terminal of the NOT gate G4 is connected together with the left-shift serial data input terminal DSL of the bidirectional shift register U7 and the output terminal Q0 of the bidirectional shift register U7. The input terminal of G5 is connected together with the output terminal Q of U5 and the working mode setting terminal S1 of U7. The output terminal of the rising-edge D flip-flop G5 is connected to one input terminal of the two-input OR gate G7. The input terminal of the Schmitt trigger G6 is connected together with the output terminal Q of the falling-edge D flip-flop U6 and the working mode setting terminal S0 of the bidirectional shift register U7. The output terminal of the Schmitt trigger G6 is connected to the other input terminal of the two-input OR gate G7. The output terminal of the two-input OR gate G7 is connected together with the clock pulse CP of the bidirectional shift register U7, the reset terminal R of the rising-edge D flip-flop U5, and the reset terminal R of the falling-edge D flip-flop U6. The data input terminal D of the rising-edge D flip-flop U5 is connected to the power supply VCC. The high-level setting terminal S of the rising-edge D flip-flop U5 is connected to the node where the capacitor C1 and the resistor R1 are connected. The data input terminal D of the falling-edge D flip-flop U6 is connected to the power supply VCC. The high-level setting terminal S of the falling-edge D flip-flop U6 is connected to the node where the capacitor C1 and the resistor R1 are connected. The capacitor C1 and the resistor R1 are connected in series between the power supply VCC and GND. The reset terminal MR, the parallel data input terminals D0, and the power terminal of the bidirectional shift register U7 are connected to the power supply VCC. The parallel data input terminals of the bidirectional shift register U7 are D1, D2, and D3. The control signal P0 output from the parallel data output terminal Q0 of the bidirectional shift register U7 is respectively connected to the DSL of the bidirectional shift register U7, the input terminal of the NOT gate G4, the gate of the NMOS transistor M1, and the gate of the NMOS transistor M8. The control signal P1 output from the parallel data output terminal Q1 of the bidirectional shift register U7 is respectively connected to the gate of the NMOS transistor M2 and the gate of the NMOS transistor M7. The control signal P2 output from the parallel data output terminal Q2 of the bidirectional shift register U7 is respectively connected to the gate of the NMOS transistor M3 and the gate of the NMOS transistor M6.The control signal P3 output from the parallel data output terminal Q3 of the bidirectional shift register U7 is respectively connected to the DSR of the bidirectional shift register U7, the input terminal of the NOT gate G3, the gate of the NMOS transistor M4, and the gate of the NMOS transistor M5; the clock pulse input terminal CP of the bidirectional shift register U7 is connected to the output terminal of the two-input OR gate G7; the operation mode control input terminals S1 and S0 of the bidirectional shift register U7 are respectively connected to the output terminals Q of the rising-edge D flip-flop U5 and the falling-edge D flip-flop U6.

[0050] The adjustment method of the magnification control logic circuit is specifically as follows:

[0051] When the magnification control logic circuit receives the rising-edge signal from the signal amplitude discrimination circuit, the magnification K of the variable magnification amplifier circuit module is decreased v ;

[0052] When the magnification control logic circuit receives the falling-edge signal from the signal amplitude discrimination circuit, the magnification K of the variable magnification amplifier circuit module is increased v 。

[0053] The working principle of the present invention: When the elevator system is powered on, the monitoring circuit starts to power on and work. The capacitor C1 and resistor R14 circuit connected in series between the power supply VCC and GND starts to charge the capacitor C1. A high-level pulse appears at the high-level setting terminal S of the rising-edge D flip-flop U5 and the falling-edge D flip-flop U6. The output terminals Q of the rising-edge D flip-flop U5 and the falling-edge D flip-flop U6 are at high level, and further make the operation mode control input terminals S1 and S0 of the bidirectional shift register U7 both at high level, and U7 works in the parallel input mode.

[0054] After a short delay by the Schmitt trigger G3 and the Schmitt trigger G4, the high-level output of the rising-edge D flip-flop U5 and the falling-edge D flip-flop U6 is input to the input terminals of the two-input OR gate G7. The output of the two-input OR gate G7 produces a rising edge, and further makes a rising edge appear at the CP terminal of the bidirectional shift register U7. The states of the output terminals Q3-Q0 of the bidirectional shift register U7 are initialized to the levels of the input terminals D3-D0, that is, the initialization state of Q3-Q0 is 0001. At the same time, the high level at the output terminal of the two-input OR gate G7 resets the output terminal Q of the rising-edge D flip-flop U5 and the falling-edge D flip-flop U6 to low level. The control input terminals S1 and S0 of the bidirectional shift register U7 are both at low level, and the bidirectional shift register U7 works in the hold mode. After a short delay by the NOT gate G3 and the NOT gate G4, a falling edge appears at the CP terminal of the bidirectional shift register U7, and the initialization process of the bidirectional shift register U7 ends.

[0055] The purpose of initializing the bidirectional shift register U7 is to initialize the outputs Q3 to Q0 of the bidirectional shift register U7 to 0001, so that when the circuit is powered on, P0 is at a high level, the NMOS transistors M1 and M8 are turned on, and the resistors R1 and R10 are connected to the variable multiple amplification circuit module, ensuring that the amplification factor of the variable multiple amplification circuit module is maximized.

[0056] After power-on initialization, when the elevator starts to run, the traction machine current i ac begins to rise, and the output signal v2 of the variable multiple amplification circuit module begins to increase. When the output signal v2 is greater than the maximum reference value , a rising edge signal appears at the output signal v3, and the output Q of the rising edge D flip-flop U5 becomes high level. At this time, the states of the control terminals S1 and S0 of the bidirectional shift register U7 are 10, and the bidirectional shift register U7 operates in the left shift state. Since the DSL of the bidirectional shift register U7 is connected to the Q0 of the bidirectional shift register U7, the bidirectional shift register U7 operates in the cyclic left shift mode.

[0057] After the high level of the output Q of the rising edge D flip-flop U5 passes through the delay of the Schmitt trigger G5, a rising edge appears at the clock pulse terminal CP of the bidirectional shift register U7, shifting the level state of the DSL pin into the output Q0 of the bidirectional shift register U7. At this time, the states of P3 to P0 are 0010, controlling the NMOS transistors M2 and M7 to turn on, and the NMOS transistors M1 and M8 to turn off. The resistors R2 and R9 are connected to the variable multiple amplification circuit module, reducing the amplification factor of the circuit, causing its output signal v2 to decrease, and simultaneously resetting the output Q of the rising edge D flip-flop U5 to low level. After that, if the current i ac of the elevator traction machine continues to increase during operation, causing the output signal v2 to be greater than the maximum reference value again , the foregoing process is repeated, and the states of P3 to Q0 become 0100, controlling the NMOS transistors M3 and M6 to turn on, and the NMOS transistors M2 and M7 to turn off. The resistors R3 and R8 are connected to the variable multiple amplification circuit module, reducing the amplification factor of the circuit again, causing its output signal v2 to decrease again, and resetting the output Q of the rising edge D flip-flop U5 to low level again.

[0058] With the above cooperation, when the traction machine current i ac increases to make the output current v2 greater than the maximum reference value , the high level is shifted one bit to the left among Q3 to Q0, switching the on-off states of the corresponding NMOS transistors, reducing the feedback resistor of the variable multiple amplification circuit module, and the circuit amplification factor K vDecrease to ensure that the output current v2 does not exceed the maximum output voltage and enter the saturation distortion state. Repeat the above process until the state of P3~Q0 becomes 1000, the current amplification factor is the smallest, and the corresponding current works within the maximum range. When P3~Q0 is 1000, the output of the NOT gate G3 is at a low level, the two-input AND gate G1 is locked, and the CP terminal of the rising-edge D flip-flop U5 is locked at a low level, and P3~Q0 maintains the 1000 state, avoiding the elevator working in an abnormal short circuit or severe overload When the output signal v3 has a rising-edge signal, triggering the cyclic left shift of P3~Q0 causes an illegal state where P3~Q0 is 0000.

[0059] Assume that the current state of P3~Q0 becomes 1000. When the elevator traction machine is running, its traction machine current i ac decreases so that the output signal v2 is less than the minimum reference value At this time, the output signal v3 has a falling-edge signal, and the output terminal Q of the falling-edge D flip-flop U6 becomes high level. At this time, the control terminals S1 and S0 of the bidirectional shift register U7 are in the state of 01, and the bidirectional shift register U7 works in the right-shift state. Since the DSR of the bidirectional shift register U7 is connected to the Q3 of the bidirectional shift register U7, the bidirectional shift register U7 works in the cyclic right-shift mode. After the high level of the output terminal Q of the falling-edge D flip-flop U6 passes through the delay of the Schmitt trigger G6, a rising edge appears at the clock pulse terminal CP of the bidirectional shift register U7, and the level state of the DSR pin is shifted right into the output terminal Q3 of the bidirectional shift register U7. At this time, the state of P3~P0 is 0100, controlling the NMOS transistors M3 and M6 to conduct, and the NMOS transistors M4 and M5 to turn off. The resistors R3 and R8 are connected to the variable gain amplifier circuit module to increase the amplification factor of the circuit, increase its output signal v2, and at the same time reset the output terminal Q of the falling-edge D flip-flop U6 to a low level.

[0060] After that, if the traction machine current i during the operation of the elevator traction machine ac continues to decrease so that the output signal v2 is less than the minimum reference value again At this time, repeat the foregoing process, the state of P3~Q0 becomes 0010, controlling the NMOS transistors M2 and M7 to conduct, the NMOS transistors M3 and M6 to turn off, and the resistors R2 and R9 to be connected to the variable gain amplifier circuit module, increasing the amplification factor of the circuit again, its output signal v2 increases again, and the output terminal Q of the falling-edge D flip-flop U6 is reset to a low level again.

[0061] With the above cooperation, when the traction machine current i of the amplification factor control module ac decreases to make the output signal v2 less than the minimum reference value When it is, the high level is shifted one bit to the right among Q3~Q0, the on-off states of the corresponding NMOS transistors are switched, the feedback resistance of the variable magnification circuit module increases, and the circuit magnification increases, ensuring that the minimum output voltage of the output signal v2 does not enter the cut-off distortion state. Repeat the above process until the state of P3~Q0 becomes 0001, and the current magnification is the largest, corresponding to the elevator working in standby or no-load. When P3~Q0 is 0001, the output of the NOT gate G4 is at a low level, the two-input AND gate G2 is locked, the CP terminal of the falling-edge D flip-flop U6 is locked at a low level, and P3~Q0 maintains the 0001 state, avoiding the occurrence of a falling-edge signal in the output signal v3 when the circuit is interfered, and then triggering the cyclic right shift of P3~Q0 to cause the illegal state of P3~Q0 being 0000.

Claims

1. A method for monitoring the current of an elevator traction machine, characterized in that, It includes the following steps: ①Convert the traction machine current i ac into a voltage signal v i , and amplify the voltage signal v i to obtain an output signal v1; ②Based on the amplification factor K v Amplify and bias the output signal v1 by 2.5V to obtain the output signal v2; ③ Compare the output signal v2 with the maximum reference value and the minimum reference value and adjust the amplification factor K of the output signal v2 according to the comparison result v ; ④According to the amplification factor K of the output signal v2 v The current value of the elevator traction machine is calculated.

2. The elevator traction machine current monitoring method according to claim 1, characterized in that: The output signal v2 is calculated according to the formula v2 = 2.5 + K v v1 3. A monitoring system used for the elevator traction machine current monitoring method according to claim 1 or 2, characterized in that: It includes a current-to-voltage module, a DC bias circuit, a variable gain amplifier circuit module, and a gain control module; The current-to-voltage module includes a shunt resistor and a differential amplifier. The shunt resistor is used to convert the traction machine current i ac into a voltage signal v i . The differential amplifier is used to amplify the voltage signal v i to obtain an output signal v 1 ; The DC bias circuit is used to generate a high-precision 2.5V DC voltage; The variable gain amplifier circuit module is used to amplify the output signal v1 and apply a 2.5V DC bias to obtain the output signal v2; The magnification control module includes a signal amplitude discrimination circuit and a magnification control logic circuit. The signal amplitude discrimination circuit is configured to compare the output signal v2 with the maximum reference value and the minimum reference value , and output a signal to the magnification control logic circuit according to the comparison result. The magnification control logic circuit is configured to adjust the magnification of the variable magnification amplifier circuit module according to the signal output by the signal amplitude discrimination circuit.

4. The monitoring system according to claim 3, characterized in that: The shunt resistor calculates the voltage signal v according to the formula i = i ac R shunt to obtain the voltage signal v i , where R shunt is the resistance value of the shunt resistor, and the output signal v1 is calculated by the formula v1 = k DP v i , where k DP is the differential amplification factor of the differential amplifier.

5. The monitoring system according to claim 3, wherein: When the signal amplitude discrimination circuit compares the output signal v2, if the output signal v2 is greater than the maximum reference value a rising edge signal is generated. If the output signal v2 is less than the minimum reference value a falling edge signal is generated. If the output signal v2 is between the minimum reference value and the maximum reference value the output level of the signal amplitude discrimination circuit remains unchanged.

6. The monitoring system according to claim 3, wherein The adjustment method of the gain control logic circuit is specifically as follows: When the gain control logic circuit receives the rising edge signal of the signal amplitude discrimination circuit, it reduces the gain of the variable gain amplifier circuit module; When the gain control logic circuit receives the falling edge signal of the signal amplitude discrimination circuit, it increases the gain of the variable gain amplifier circuit module.

7. The monitoring system according to claim 6, characterized in that: A feedback resistor component is provided in the variable gain amplifier circuit module, and the gain control logic circuit changes the gain of the variable gain amplifier circuit module by adjusting the resistance value of the feedback resistor component.

8. The monitoring system according to claim 7, characterized in that: The feedback resistor component includes a plurality of resistors connected in parallel in the variable gain amplifier circuit module, and the gain control logic circuit adjusts the feedback resistor component by connecting resistors with different resistance values into the variable gain amplifier circuit module.

Images