Electric leakage action protection tester

Abstract

The invention discloses an electric leakage action protection tester, and belongs to the technical field of electric power. Comprising a voltage sampling circuit, a voltage signal processing unit, a voltage signal isolation unit, a first reference voltage module, a relay signal isolation unit, a current output interface, a multi-gear current output unit, a control signal isolation unit, a fault detection unit, a current AD conversion unit, a DA signal generation unit, a second reference voltage module, a main controller and a display screen. The high-precision mA-level alternating-current low-current acquisition circuit solves the technical problems that high-precision multi-gear alternating-current mA-level low current can be output and voltages at the two ends of electric leakage action equipment can be acquired in a grading manner, can output high-precision mA-level alternating current, has three gears of 4mA, 20mA and 100mA, and can be selected according to requirements. The system supports grading real-time voltage acquisition detection and voltage waveform real-time display of electric leakage action equipment, and voltage recording during electric leakage action, greatly reduces manual recording, and is more intelligent and efficient.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a leakage protection tester. Background Art

[0002] There are many devices for leakage protection on the market. These devices need to be tested for leakage protection before leaving the factory. In the past, they were simple tests. However, with the update and continuous upgrading of leakage protection equipment, more rigorous and comprehensive tests are required:

[0003] First, it is necessary to test and record the effective value of the current and the current waveform when the leakage protection mechanism is activated. Second, it is necessary to display the current waveform and current value added by the leakage protection machine in real time. Third, it is necessary to display the voltage waveform and voltage value added at both ends of the leakage protection machine in real time. Fourth, it is necessary to record the voltage waveform and the action current value at both ends of the leakage protection mechanism when it is activated to see whether it meets the requirements of the leakage level and functionality. Therefore, a comprehensive leakage protection mechanism test equipment is needed to complete its detection. 1. Manual operation is required, which is inefficient. 2. It cannot output high-precision multi-speed AC mA-level small current; 3. It cannot collect the voltage at both ends of the leakage action device in a graded manner. 4. It cannot automatically record the action current value and action voltage waveform. Summary of the invention

[0004] The purpose of the present invention is to provide a leakage protection tester, which solves the technical problem of being able to output high-precision multi-level AC mA-level small current and being able to collect the voltage at both ends of the leakage action device in stages.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A leakage protection tester, comprising a voltage sampling circuit, a voltage signal processing unit, a voltage signal isolation unit, a first reference voltage module, a relay signal isolation unit, a current output interface, a multi-speed current output unit, a control signal isolation unit, a fault detection unit, a current AD conversion unit, a DA signal generation unit, a second reference voltage module, a main controller, a display screen, a button group and a power supply module, wherein the display screen and the button group are connected to the main controller;

[0007] The input end of the voltage sampling circuit is connected to the voltage signal input interface, the output end is connected to the voltage signal processing unit, and the control end is connected to the output end of the relay signal isolation unit, and the input end of the relay signal isolation unit is connected to the main controller; the output end of the voltage signal processing unit is connected to the input end of the voltage signal isolation unit, and the output end of the voltage signal isolation unit is connected to the main controller, and the first reference voltage module provides a reference voltage for the voltage signal processing unit;

[0008] The voltage sampling circuit is used to collect the voltage signal of the external voltage source, and after isolating and AD converting the voltage signal through the voltage signal processing unit, it is sent to the main controller; the relay signal isolation unit is used to receive the relay control signal sent by the main controller, and transmit the relay control signal to the voltage sampling circuit, and the voltage sampling circuit is used to control the voltage-dividing relay and electronic switch inside itself according to the relay control signal; the voltage-dividing relay is used to select different voltage-dividing resistor networks in the voltage sampling circuit, and the electronic switch is used to adjust the gain of the amplifier in the voltage sampling circuit; the output end of the multi-speed current output unit is connected to the current output interface, the control end is connected to the output end of the control signal isolation unit, and the input end is connected to the DA signal generating unit The output end and the test end of the element are connected to the input end of the fault detection unit, and the current signal sampling end is connected to the input end of the current AD conversion unit; the multi-speed current output unit is used to output current signals of several different gears; the input end of the control signal isolation unit is connected to the main controller, the output end of the current AD conversion unit is connected to the main controller, and the second reference voltage module provides a reference voltage for the current AD conversion unit; the power supply module supplies power to the voltage sampling circuit, the voltage signal processing unit, the voltage signal isolation unit, the first reference voltage module, the relay signal isolation unit, the current output interface, the multi-speed current output unit, the control signal isolation unit, the fault detection unit, the current AD conversion unit, the DA signal generating unit and the second reference voltage module.

[0009] Preferably, the power supply module includes a 15V power supply module, a 5V power supply module, a first 3.3V power supply module and a second 3.3V power supply module, the input end of the 15V power supply module is connected to an external +13.5V power supply and -13.5V power supply, and the output end outputs +15V power supply and -15V power supply; the input end of the 5V power supply module is connected to +15V power supply and -15V power supply, and the output end outputs 5V power supply; the input end of the first 3.3V power supply module is connected to a 5V power supply, and the output end outputs a 3.3VCC power supply, and the input end of the second 3.3V power supply module is connected to a 5V power supply, and the output end outputs a M3.3V power supply.

[0010] Preferably, the voltage sampling circuit includes a buffer U1, a signal input interface J1, a voltage-dividing channel selection circuit, an amplifying isolation circuit, a differential amplifying circuit, a controllable gain amplifying circuit and an electronic switch U10, wherein the input end of the buffer U1 is connected to the X1 / 2I signal outputted by the output end of the relay signal isolation unit, and the output end outputs the X1 / 2 signal; the signal input interface J1 is used to connect the voltage signal of an external voltage source; the input end of the voltage-dividing channel selection circuit is connected to the signal input interface J1, the control end is connected to the X1 / 2 signal, and the output end is connected to the input end of the amplifying isolation circuit, the output end of the amplifying isolation circuit is connected to the input end of the differential amplifying circuit, the output end of the differential amplifying circuit is connected to the input end of the controllable gain amplifying circuit, the output end of the controllable gain amplifying circuit outputs the FBSIN signal and is connected to the input end of the voltage signal processing unit; the X5 signal outputted by the output end of the relay signal isolation unit is connected to the gain control end of the controllable gain amplifying circuit; the gain control end of the controllable gain amplifying circuit and the input end of the buffer U1 constitute the control end of the voltage sampling circuit.

[0011] Preferably, the voltage signal processing unit includes an isolated voltage amplifier circuit and an AD module U13, the input end of the isolated voltage amplifier circuit constitutes the input end of the voltage signal processing unit, the output end is connected to the input end of the AD module U13, and the output end of the AD module U13 constitutes the output end of the voltage signal processing unit; the first reference voltage module provides reference voltages for the isolated voltage amplifier circuit and the AD module U13 respectively; the voltage signal isolation unit includes an isolator U9 and a resistor R17, the input end of the isolator U9 constitutes the input end of the voltage signal isolation unit, the input end of the isolator U9 is connected to the output end of the AD module U13, and the output end is connected to a group of IO ports of the main controller through the resistor R17; the connection end of the resistor R17 and the main controller constitutes the output end of the voltage signal isolation unit; the relay signal isolation unit includes an isolator U8 and a resistor R16, the input end of the isolator U8 is connected to the main controller through the resistor R16, the output end of the isolator U8 constitutes the output end of the relay signal isolation unit, and the connection end of the resistor R16 and the main controller constitutes the input end of the relay signal isolation unit.

[0012] Preferably, the control signal isolation unit includes a drive register U23, a filter unit, a resistor R67, an isolator U21 and a resistor R51, the output end of the drive register U23 constitutes the output end of the control signal isolation unit, the input end of the drive register U23 is connected to the output end of the filter unit, the input end of the filter unit is connected to the output end of the isolator U21 through the resistor R67, and the input end of the isolator U21 is connected to a group of IO ports of the main controller through the resistor R51; the output end of the filter unit also outputs a / 1595 signal; the output end of the drive register U23 outputs CTL1 signal, CTL2 signal, CTL3 signal and / EN signal respectively; the multi-speed current output unit includes a relay group unit , current sampling unit, transformer TI1, power amplifier unit, power amplifier enabling unit and DA signal amplitude control unit; the control end of the multi-speed current output unit includes control end A and control end B; the control end of the relay group unit constitutes the control end A of the multi-speed current output unit, and the output end constitutes the output end of the multi-speed current output unit; the relay group unit includes 3 relay groups, and the coil control ends of the 3 relay groups constitute the control end of the relay group unit, and the coil control ends of the 3 relay groups are all controlled in parallel through parallel signals, and the parallel signals are composed of CTL1 signal, CTL2 signal and CTL3 signal; in the 3 relay groups, the common contacts of each relay group are connected together to form a total of 3 common Output end, these three common output ends constitute the output end of the relay group unit, the normally open contacts of each group of relays constitute the relay input end of the group, a total of 3 relay input ends, these three relay input ends constitute the input end of the relay group unit; one relay input end is connected to the 3rd, 4th and 5th pins of the transformer TI1, and its corresponding common output end is connected to the current output interface; the other two relay input ends are connected to the 6th pin of the transformer TI1, and their corresponding two common output ends, one is connected to the current output interface, and the other outputs the US signal and is connected to the input end of the current sampling unit; the output end of the current sampling unit outputs the FBI signal and the FB signal respectively, and the output end that outputs the FBI signal constitutes a multi-speed The current signal sampling end of the current output unit, the FB signal is connected to the DA signal amplitude control unit; the DA signal amplitude control unit is used to control the output amplitude of the power amplifier unit; the DA signal amplitude control unit is respectively connected to the power amplifier enable unit, pins 1 and 2 of the transformer TI1 and the power amplifier unit; the test signal input end of the DA signal amplitude control unit constitutes the test end of the multi-speed current output unit; the input end of the DA signal amplitude control unit constitutes the input end of the multi-speed current output unit; the control end of the DA signal amplitude control unit constitutes the control end B of the multi-speed current output unit, and the output end of the filter unit is also connected to the control end of the DA signal amplitude control unit; the output end of the power amplifier unit is connected to pin 2 of the transformer TI1.

[0013] Preferably, the DA signal generating unit includes a resistor R49, an isolator U18, a resistor R61, a DA chip U26 and a DA signal isolation and amplification unit; the input end of the isolator U18 is connected to a group of IO ports of the main controller through the resistor R49, and the output end is connected to the input end of the DA chip U26 through the resistor R61, the output end of the DA chip U26 is connected to the DA signal amplification and isolation unit, the DA signal amplification and isolation unit constitutes the output end of the DA signal generating unit and outputs the SIN signal, and the connection end of the resistor R49 and the main controller constitutes the input end of the DA signal generating unit; the DA signal amplitude control unit includes It includes a first isolation unit, a DA chip U22, a second isolation unit, a differential amplifier U28A, a transformer signal amplification unit and a power amplifier driving unit, the input end of the first isolation unit constitutes the input end of the DA signal amplitude control unit, the input end of the first isolation unit is connected to the output end of the DA signal amplification isolation unit, and the output end is connected to the input end of the DA chip U22, the control end of the DA chip U22 constitutes the control end of the DA signal amplitude control unit, the output end of the DA chip U22 is connected to the positive input end of the differential amplifier U28A through the second isolation unit, and the FB signal is connected to the positive input end of the differential amplifier U28A;

[0014] The negative input end of the differential amplifier U28A is connected to the output end of the transformer signal amplification unit, and the input end of the transformer signal amplification unit is connected to pin 1 of the transformer TI1; the differential amplifier U28A is also respectively connected to pin 2 of the transformer TI1 and the test signal input end of the DA signal amplitude control unit, and the output end of the differential amplifier U28A is connected to the input end of the power amplifier drive signal unit, and the control end of the power amplifier drive signal unit is connected to the power amplifier enable unit, and the output end is connected to the power amplifier unit.

[0015] Preferably, the current AD conversion unit includes an amplifier unit, an AD chip U31, a resistor R80, an isolator U29 and a resistor R100, the input end of the amplifier unit constitutes the input end of the current AD conversion unit, the input end of the amplifier unit is connected to the FBI signal, the output end is connected to the AD chip U31, the output end of the AD chip U31 is connected to the input end of the isolator U29 through the resistor R80, the output end of the isolator U29 is connected to the main controller through the resistor R100, and the connection end of the resistor R100 and the main controller constitutes the output end of the current AD conversion unit;

[0016] The second reference voltage module includes a power chip U20, a first reference voltage generating unit and a second reference voltage generating unit. The output end of the power chip U20 is respectively connected to the first reference voltage generating unit and the second reference voltage generating unit, and outputs a reference voltage Vre5V. The first reference voltage generating unit and the second reference voltage generating unit respectively output a reference voltage Vre2V and a reference voltage Vre10V. The reference voltage Vre5V and the reference voltage Vre2V provide reference voltages for the AD chip U31 and the amplification unit respectively, and the reference voltage Vre10V provides a reference voltage for the DA chip U26.

[0017] Preferably, the fault detection unit includes an operational amplifier U17A, an operational amplifier U17B, a resistor R38, a resistor R45, a resistor R37, a resistor R44, a resistor R46, a resistor R53, a capacitor C68, an operational amplifier U24A, a capacitor C82, a diode D3, a resistor R58, a diode D4, a resistor R60, a resistor R70, a diode D8, a resistor R71, a resistor R75, a resistor R87, a resistor R83, an LED lamp D17 and a transistor Q2, wherein the resistor R37 and the resistor R38 are connected in series, one end of which is connected to the TEST signal emitted by the multi-speed current output unit, and the other end is connected to the ground wire, the pin 2 of the operational amplifier U17A is connected to the connection node of the resistor R37 and the resistor R38, the pin 3 is connected to the +15V power supply through the resistor R45, the pin 1 is connected to the positive electrode of the diode D3, the pin 6 of the operational amplifier U17B is connected to the -15V power supply through the resistor R46, and the pin 5 is connected to the operational Pin 2 and Pin 7 of amplifier U17A are connected to Pin 1 of operational amplifier U17A, resistor R44 is connected between Pin 3 of operational amplifier U17A and Pin 6 of operational amplifier U17B, resistor R53 is a pull-up resistor of Pin 1 of operational amplifier U17A, capacitor C68 is connected in parallel with resistor R53, the cathode of diode D3 is connected to Pin 2 of operational amplifier U24A, resistor R58 is connected in parallel with diode D3, diode D3 is also connected to the anode of diode D4, Pin 3 of operational amplifier U24A is connected to Pin 6 of operational amplifier U17B, Pin 1 is connected to the anode of diode D8, the cathode of diode D8 is connected to Pin 5 of operational amplifier U24B, Pin 6 of operational amplifier U24B is connected to +15V power supply through resistor R70, and Pin 7 outputs VOLD signal, the cathode of diode D4 is connected to Pin 6 of operational amplifier U24B through resistor R60, and Pin 6 of operational amplifier U24B is also connected to / EN signal;

[0018] Pin 5 of the operational amplifier U24B is connected to a -15V power supply through a resistor R71, and a resistor R75 is connected between pins 5 and 7 of the operational amplifier U24B; pin 7 of the operational amplifier U24B is connected to the base of the transistor Q2 through a resistor R87, and the emitter of the transistor Q2 is connected to the ground wire, and the collector is connected to a control signal FAIL signal output by the isolator U18 through the resistor R61;

[0019] The positive electrode of LED lamp D17 is connected to the 7th foot of operational amplifier U24B through resistor R83, and the negative electrode is connected to the ground wire.

[0020] The leakage protection tester described in the present invention solves the technical problem of being able to output a small current of high-precision multi-level AC mA level and being able to collect the voltage at both ends of the leakage action device in a graded manner. The present invention can output a high-precision mA level AC current and has three levels of 4mA, 20mA and 100mA. The three levels can be selected according to the requirements, and support hierarchical real-time voltage collection and detection and voltage display of the leakage action device, and record the current value and voltage waveform during leakage action, which greatly reduces manual recording and is more intelligent, convenient and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a general principle block diagram of the present invention;

[0022] Figure 2 It is a schematic block diagram of the voltage sampling circuit of the present invention;

[0023] Figure 3 It is a schematic block diagram of the voltage signal processing unit, the voltage signal isolation unit, the relay signal isolation unit and the first reference voltage module of the present invention;

[0024] Figure 4 It is a schematic block diagram of the multi-level current output unit and the control signal isolation unit of the present invention;

[0025] Figure 5 It is a schematic block diagram of a DA signal generating unit and a DA signal amplitude control unit of the present invention;

[0026] Figure 6 It is a schematic diagram and block diagram of the current AD conversion unit and the second reference voltage module of the present invention;

[0027] Figure 7 It is a block diagram of the principle diagram of the power module of the present invention;

[0028] Figure 8 A circuit diagram of a voltage signal processing unit, a voltage signal isolation unit, a relay signal isolation unit and a first reference voltage module of the present invention;

[0029] Fig. 9is a circuit diagram of a voltage sampling circuit of the present invention;

[0030] Fig.10 A circuit diagram of a control signal isolation unit of the present invention;

[0031] Fig.11 A circuit diagram of a relay group unit of the present invention;

[0032] Fig.12 is a circuit diagram of the current sampling unit and the transformer TI1 of the present invention;

[0033] Fig.13 A circuit diagram of a DA signal amplitude control unit of the present invention;

[0034] Fig.14 is a circuit diagram of a power amplifier unit of the present invention;

[0035] Fig.15 A circuit diagram of a power amplifier enabling unit of the present invention;

[0036] Fig.16 is a circuit diagram of a fault detection unit of the present invention;

[0037] Fig.17 is a circuit diagram of a DA signal generating unit of the present invention;

[0038] Fig.18 A circuit diagram of a current AD conversion unit of the present invention;

[0039] Fig.19 is a circuit diagram of a second reference voltage module of the present invention;

[0040] Fig. 20 is a circuit diagram of the power module of the present invention. DETAILED DESCRIPTION

[0041] like Figure 1-Figure 20 A leakage protection tester shown includes a voltage sampling circuit, a voltage signal processing unit, a voltage signal isolation unit, a first reference voltage module, a relay signal isolation unit, a current output interface, a multi-speed current output unit, a control signal isolation unit, a fault detection unit, a current AD conversion unit, a DA signal generation unit, a second reference voltage module, a main controller, a display screen, a button group and a power supply module, wherein the display screen and the button group are connected to the main controller;

[0042] The power supply module supplies power to the voltage sampling circuit, the voltage signal processing unit, the voltage signal isolation unit, the first reference voltage module, the relay signal isolation unit, the current output interface, the multi-speed current output unit, the control signal isolation unit, the fault detection unit, the current AD conversion unit, the DA signal generating unit and the second reference voltage module.

[0043] The power supply module includes a 15V power supply module, a 5V power supply module, a first 3.3V power supply module and a second 3.3V power supply module. The input end of the 15V power supply module is connected to an external +13.5V power supply and a -13.5V power supply, and the output end outputs +15V power supply and -15V power supply; the input end of the 5V power supply module is connected to a +15V power supply and a -15V power supply, and the output end outputs a 5V power supply; the input end of the first 3.3V power supply module is connected to a 5V power supply, and the output end outputs a 3.3VCC power supply; the input end of the second 3.3V power supply module is connected to a 5V power supply, and the output end outputs a M3.3V power supply.

[0044] In this embodiment, the 15V power supply module is chip U12. The input terminal +Vin and GND terminal of chip U12 are respectively connected to the externally provided +13.5V power supply and -13.5V power supply through interface VCCIN1. The positive output terminal +VO and negative output terminal -VO of chip U12 output +15V power supply and -15V power supply respectively. Capacitor C43, capacitor C57 and capacitor C56 are filter capacitors on both sides of chip U12 respectively. The model of chip U12 is URA2415YMD-10WR3.

[0045] The 5V power supply module is chip U16, the input terminal VIN of chip U16 is connected to +15V power supply, the output terminal VOUT outputs 5V power supply, capacitors C66, C73 and C76 are filter capacitors on both sides of chip U16, and the model of chip U16 is ASM1117-5.0. The first 3.3V power supply module is chip U15, the input terminal VIN of chip U15 is connected to 5V power supply, the output terminal VOUT outputs 3.3VCC power supply, capacitors C67 and C75 are filter capacitors on the output end of chip U15, and the model of chip U15 is ASM1117-5.0. The second 3.3V power supply module is chip U2, the input terminal Vin of chip U2 is connected to 5V power supply, the output terminal Vout outputs M3.3V power supply, capacitors C3, C4, C19 and C15 are filter capacitors on both sides of chip U2, and the model of chip U2 is SP6205EM5-3.3.

[0046] The input end of the voltage sampling circuit is connected to the voltage signal input interface, the output end is connected to the voltage signal processing unit, and the control end is connected to the output end of the relay signal isolation unit. The input end of the relay signal isolation unit is connected to the main controller; the voltage sampling circuit includes a buffer U1, a signal input interface J1, a voltage division channel selection circuit, an amplification isolation circuit, a differential amplification circuit, a controllable gain amplification circuit and an electronic switch U10. The input end of the buffer U1 is connected to the X1 / 2I signal output by the output end of the relay signal isolation unit, and the output end outputs the X1 / 2 signal; the signal input interface J1 is used to connect the voltage signal of an external voltage source;

[0047] The input end of the voltage-dividing channel selection circuit is connected to the signal input interface J1, the control end is connected to the X1 / 2 signal, and the output end is connected to the input end of the amplifying isolation circuit. The output end of the amplifying isolation circuit is connected to the input end of the differential amplifying circuit. The output end of the differential amplifying circuit is connected to the input end of the controllable gain amplifying circuit. The output end of the controllable gain amplifying circuit outputs the FBSIN signal and is connected to the input end of the voltage signal processing unit; the X5 signal output from the output end of the relay signal isolation unit is connected to the gain control end of the controllable gain amplifying circuit; the gain control end of the controllable gain amplifying circuit and the input end of the buffer U1 constitute the control end of the voltage sampling circuit.

[0048] In this embodiment, the model of the buffer U1 is SN74LVC1G126-1, which is used to cache the control signal sent from the main controller. The specific generation channel of the X1 / 2 signal is: the relay signal isolation unit isolates the X1 / 2ID1 signal sent by the main controller, generates an X1 / 2I signal, and finally generates an X1 / 2 signal after passing through the cache of the buffer U1.

[0049] The voltage-dividing channel selection circuit specifically includes a TVS tube V1, a resistor R5, a resistor R4 and a relay J33. The resistors R5 and R4 are sampling voltage-dividing resistors. After the resistors R5 and R4 are connected in series, one end is connected to pin 1 of the signal input interface J1 and the other end is connected to pin 2 of the input interface J1. The TVS tube V1 is connected between pins 1 and 2 of the input interface J1 for TVS protection.

[0050] Relay J33 is divided into two parts in the circuit, namely J33A and J33B. J33A is the contact part, and J33B is the coil part. One end of J33B is connected to a 5V power supply, and the other end is controlled by the X1 / 2 signal. The node where the common contact of J33A and resistor R4 are connected to pin 2 of the input interface J1 constitutes the output end of the voltage divider channel selection circuit, which is used to output the collected voltage signal. The normally open end of J33A is connected to the connection node of resistor R5 and resistor R4, and the normally closed end is connected to the other end of resistor R5. By controlling relay J33, the graded selection of the voltage divider resistor can be realized, thereby obtaining voltage collection values ​​of different grades.

[0051] Relay J33 and buffer U1 are both powered by a 5V power supply. The power supply D5V in the figure is the power supply voltage output by the 5V power supply after being isolated by a 10R resistor, and its voltage value is still 5V. The amplification isolation circuit specifically includes resistor R8, resistor R11, resistor R15, capacitor C21, diode U5, capacitor C33, capacitor C34, amplifier U7, resistor R21, resistor R24, resistor R7, resistor R10, resistor R14, capacitor C20, diode U4, capacitor C32, capacitor C31, amplifier U6, resistor R20, resistor R23; the differential amplification circuit is composed of differential amplifier UC1 and its peripheral circuits; resistor R8, resistor R11, resistor R15, capacitor C21, diode U5, capacitor C33, capacitor C34, amplifier U7, resistor R21, resistor R24 ​​constitute the first voltage acquisition channel of the amplification isolation circuit; one end of resistor R8 is connected to the common end of J33. Resistor R7, resistor R10, resistor R14, capacitor C20, diode U4, capacitor C32, capacitor C31, amplifier U6, resistor R20, and resistor R23 constitute a second voltage acquisition channel of the amplification isolation circuit; one end of resistor R7 is connected to the node where resistor R4 is connected to pin 2 of input interface J1.

[0052] The first voltage acquisition channel and the second voltage acquisition channel are connected to the positive input terminal IN+ and the negative input terminal IN- of the differential amplifier UC1 respectively. Resistor R11, resistor R15, and capacitor C21 form a filter network for filtering the signal output by the common contact of J33A. Amplifier U7 forms a voltage follower to play an isolation role. Resistor R21 and resistor R24 ​​form a voltage divider circuit for providing a voltage divider signal to the positive input terminal IN+ of the differential amplifier UC1; diode U5, capacitor C33, and capacitor C34 provide a pull-up voltage for the positive input terminal of amplifier U7. In this embodiment, the model of diode U5 is BAV199 (NP), and its pin 1 and pin 2 are connected to the +15V power supply and -15V power supply respectively. Resistor R10, resistor R14, and capacitor C20 form a filter network for filtering the signal output from one end of resistor R4. Amplifier U6 forms a voltage follower to play an isolation role. Resistor R20 and resistor R23 form a voltage divider circuit to provide a voltage divider signal to the negative input terminal IN- of differential amplifier UC1. Diode U4, capacitor C32, and capacitor C31 provide a pull-up voltage for the positive input terminal of amplifier U6. In this embodiment, the model of diode U4 is BAV199 (NP), and its 1st and 2nd pins are connected to +15V power supply and -15V power supply respectively. The models of amplifier U7 and amplifier U6 are both LTC2057HS8. Differential amplifier UC1, amplifier U7, and amplifier U6 are all powered by +15V power supply and -15V power supply.

[0053] The model of the electronic switch U10 is TMUX6119. The input end of the electronic switch U10, that is, the 8-pin is connected to the X5 signal. In the figure, the electronic switch U10 is divided into two parts. The first part is the control part, that is, U10A, and the second part is the throwing switch part, that is, U10B. The electronic switch U10 is powered by a 5V power supply.

[0054] The controllable gain amplifier circuit is composed of an amplifier U14 and its peripheral circuits, as shown in the figure. After the resistor R33 and the resistor R32 are connected in series, one end is connected to the ground wire and the other end is connected to the output end of the amplifier U14. The capacitor C56 and the resistor R29 are both peripheral circuits of the amplifier U14.

[0055] Pin 7 of U10B is connected to the output of amplifier U14, pin 5 is connected to the connection node of resistor R33 and resistor R32, and pin 6 is connected to the negative input of amplifier U14. By controlling U10A, the action of U10B can be controlled, so as to select the resistance value of the feedback resistor from the output to the negative input of amplifier U14. Amplifier U14 is powered by +15V power supply and -15V power supply. The model of amplifier U14 is OP1177, and the model of differential amplifier UC1 is INA154.

[0056] The specific generation channel of the X5 signal is as follows: the relay signal isolation unit isolates the X5D1 signal sent by the main controller and generates the X5 signal; in this embodiment, the main controller realizes the collection and processing of voltage signals of different levels by controlling the different values ​​of the X1 / 2ID1 signal and the X5D1 signal, and its truth table 1 is as follows:

[0057] X1 / 2ID1 X5D1 10V 0 0 5V 1 0 1V 1 1

[0058] Table 1

[0059] Finally, the output of the voltage sampling circuit is composed of the output of the amplifier U14, and its output signal is the FBSIN signal, which will be sent to the voltage signal processing unit for further processing later.

[0060] The output end of the voltage signal processing unit is connected to the input end of the voltage signal isolation unit, and the output end of the voltage signal isolation unit is connected to the main controller. The first reference voltage module provides a reference voltage for the voltage signal processing unit; the voltage sampling circuit is used to collect the voltage signal of the external voltage source, and the voltage signal is isolated and AD-converted by the voltage signal processing unit, and then sent to the main controller; the relay signal isolation unit is used to receive the relay control signal sent by the main controller, and transmit the relay control signal to the voltage sampling circuit, and the voltage sampling circuit is used to control the voltage-dividing relay and the electronic switch inside it according to the relay control signal; the voltage-dividing relay is used to select different voltage-dividing resistor networks in the voltage sampling circuit, and the electronic switch is used to adjust the gain of the amplifier in the voltage sampling circuit.

[0061] The voltage signal processing unit includes an isolated voltage amplifier circuit and an AD module U13, wherein the input end of the isolated voltage amplifier circuit constitutes the input end of the voltage signal processing unit, the output end is connected to the input end of the AD module U13, and the output end of the AD module U13 constitutes the output end of the voltage signal processing unit; the first reference voltage module provides reference voltages for the isolated voltage amplifier circuit and the AD module U13 respectively; the voltage signal isolation unit includes an isolator U9 and a resistor R17, wherein the input end of the isolator U9 constitutes the input end of the voltage signal isolation unit, the input end of the isolator U9 is connected to the output end of the AD module U13, and the output end is connected to a group of IO ports of the main controller through the resistor R17; the connection end of the resistor R17 and the main controller constitutes the output end of the voltage signal isolation unit;

[0062] The relay signal isolation unit includes an isolator U8 and a resistor R16. The input end of the isolator U8 is connected to the main controller through the resistor R16. The output end of the isolator U8 constitutes the output end of the relay signal isolation unit. The connection end of the resistor R16 and the main controller constitutes the input end of the relay signal isolation unit.

[0063] In the present embodiment, the isolation voltage amplifier circuit is composed of a voltage follower composed of an amplifier U3A and an amplifier circuit composed of an amplifier U3B. The FBSIN signal is first sent to the voltage follower, and then sent to the negative input end of the amplifier circuit, and then output to the positive input end IN+ of the AD module U13, and then sent to the main controller for further identification after AD conversion by the AD module U13. Resistor R9, resistor R6, capacitor C14, and capacitor C18 are all peripheral circuits of amplifier U3A, and resistor R18, resistor R19, capacitor C30, resistor R22, resistor R25, and diode D2 are all peripheral circuits of amplifier U3B. The models of amplifier U3A and amplifier U3B are OP2177, and the model of AD module U13 is AD7685CRM. The main controller counts the voltage signal after identification, generates a waveform diagram, and displays it on a display screen.

[0064] In order to protect the subsequent circuits, the present invention provides an isolation circuit when processing the signal, namely, the isolator U9 and its matching resistor R17. The function of the isolator U9 is to isolate the port of the AD module U13 from the port of the main controller, thereby protecting the main controller.

[0065] The first reference voltage module is composed of chip U11 and its peripheral circuits. The model of chip U11 is ADR435BRZ. The reference voltages it outputs include Vre5V1 and Vre2V1. Vre2V1 is connected to the positive input terminal of amplifier U3B, and Vre5V1 is connected to the REF terminal of AD module U13. Amplifier U3A and amplifier U3B are both powered by +15V power supply and 15V power supply, AD module U13 is powered by 5V power supply, and isolator U9 and isolator U8 are both powered by M3.3V power supply. The models of isolator U9 and isolator U8 are ADuM1401CRWZ. Isolator U8 is mainly used to isolate the X1 / 2ID1 signal and X5D1 signal sent by the main controller, which eventually becomes X1 / 2I signal and X5 signal. X1 / 2I signal is eventually used to control the action of relay J33, and X5 signal is eventually used to control the action of electronic switch U10.

[0066] The output end of the multi-speed current output unit is connected to the current output interface, the control end is connected to the output end of the control signal isolation unit, the input end is connected to the output end of the DA signal generating unit, the test end is connected to the input end of the fault detection unit, and the current signal sampling end is connected to the input end of the current AD conversion unit; the multi-speed current output unit is used to output current signals of several different gears; the input end of the control signal isolation unit is connected to the main controller, the output end of the current AD conversion unit is connected to the main controller, and the second reference voltage module provides a reference voltage for the current AD conversion unit.

[0067] The control signal isolation unit includes a driving register U23, a filtering unit, a resistor R67, an isolator U21 and a resistor R51. The output end of the driving register U23 constitutes the output end of the control signal isolation unit. The input end of the driving register U23 is connected to the output end of the filtering unit. The input end of the filtering unit is connected to the output end of the isolator U21 through the resistor R67. The input end of the isolator U21 is connected to a group of IO ports of the main controller through the resistor R51. The output end of the filtering unit also outputs a / 1595 signal. The output end of the driving register U23 outputs CTL1 signal, CTL2 signal, CTL3 signal and / EN signal respectively. The isolator U21 receives the control signal sent by the main controller, and its control signal includes DINAIN data signal, SCLKIN clock signal, / CS1595IN chip select signal, / CS595IN chip select signal, wherein the DINAIN data signal and the SCLKIN clock signal are common signals of the driving register U23 and the DA chip U22 in the later circuit.

[0068] The / CS1595IN chip select signal is used to enable the DA chip U22, and the / CS595IN chip select signal is used to enable the driver register U23. The driver register U23 is TPIC6B595, powered by a 5V power supply. Resistor R43 and capacitor C61, resistor R56 and capacitor C72, resistor R42 and capacitor C60, resistor R55 and capacitor C71 form four filter capacitors, which are used to filter the DINA signal, SCLK signal,

[0069] After filtering, the / CS1595 signal and / CS595 signal are sent to the input end of the drive register U23 and the input end of the DA chip U22. The isolator U21 is powered by a 3.3VCC power supply, and the model of the isolator U21 is ADuM1400BRWZ. The signals output by the drive register U23 are CTL1, CTL2, and CTL3. These three signals are used to control the relay group unit in the later circuit. The multi-speed current output unit includes a relay group unit, a current sampling unit, a transformer TI1, a power amplifier unit, a power amplifier enable unit, and a DA signal amplitude control unit;

[0070] The control end of the multi-speed current output unit includes a control end A and a control end B; the control end of the relay group unit constitutes the control end A of the multi-speed current output unit, and the output end constitutes the output end of the multi-speed current output unit; the relay group unit includes 3 relay groups, the coil control ends of the 3 relay groups constitute the control end of the relay group unit, and the coil control ends of the 3 relay groups are all controlled in parallel through parallel signals, and the parallel signals are composed of CTL1 signals, CTL2 signals and CTL3 signals; in the 3 relay groups, the common contacts of each relay group are respectively connected together to form a total of 3 common output ends, and these three common output ends constitute the output end of the relay group unit, and the normally open contacts of each relay group constitute the relay input end of the group, and a total of 3 relay input ends constitute the input end of the relay group unit; a relay input end is connected to pins 3, 4 and 5 of transformer TI1, and its corresponding common output end is connected to the current output interface;

[0071] The other two relay input terminals are connected to the 6th pin of the transformer TI1, and the corresponding two common output terminals, one is connected to the current output interface, and the other outputs the US signal and is connected to the input terminal of the current sampling unit;

[0072] In this embodiment, the relay group unit specifically includes relay J1, relay J2, relay J3, relay J4, relay J5, relay J6, and relay J7. In the figure, these relays are divided into two parts, for example, relay J1 includes J1B and J1A, relay J2 includes J2B and J2A, relay J3 includes J3B and J3A, relay J4 includes J4B and J4A, relay J5 includes J5B and J5A, relay J6 includes J6B and J6A, and relay J7 includes J7B and J7A. Taking relay J1 including J1B and J1A as an example, J1B is the coil part of relay J1, and J1A is the contact part of the relay. Similarly, the representation methods of other relays are the same.

[0073] In this embodiment, the relay J1 , the relay J2 , the relay J3 , the relay J4 , the relay J5 , the relay J6 , and the relay J7 are all powered by an external 12V power supply.

[0074] The coil control ends of the three groups of relay groups are all controlled in parallel through parallel signals as follows: relay J1, relay J2, and relay J3 are a group, and their coil parts J1B, J2B, and J3B are driven by CTL1 signal, CTL2 signal, and CTL3 signal respectively; relay J4, relay J5, and relay J6 are a group, and their coil parts J4B, J5B, and J6B are driven by CTL1 signal, CTL2 signal, and CTL3 signal respectively; relay J7, relay J8, and relay J9 are a group, and their coil parts J7B, J8B, and J9B are driven by CTL1 signal, CTL2 signal, and CTL3 signal respectively. The normally open contact of J1A is connected to the 3rd pin of the transformer IT1, the normally open contact of J2A is connected to the 4th pin of the transformer IT1, and the normally open contact of J3A is connected to the 5th pin of the transformer IT1; the common contact of J1A, the common contact of J2A and the common contact of J3A are all connected together and connected to the pin of the current output interface. In this embodiment, the current output interface is the interface machine IOUT1, and the common contact of J1A, the common contact of J2A and the common contact of J3A are all connected to the 1st pin of the interface machine IOUT1. The common contact of J4A, the common contact of J5A and the common contact of J6A are all connected together and connected to the 2nd pin of IOUT1, and the normally open contact of J4A, the normally open contact of J5A and the normally open contact of J6A are all connected together and connected to the 6th pin of the transformer TI1. In this embodiment, the 6th pin of the transformer TI1 is connected to the ground wire. The common contacts of J7A, J8A and J9A are all connected together and output US signals, which are sent to the current sampling unit for further processing. The normally open contact of J7A is connected to the normally open contact of J4A, the normally open contact of J8A is connected to the normally open contact of J5A, and the normally open contact of J9A is connected to the normally open contact of J6A. In this embodiment, the current signal is output selected by each group of three relays, and the selection output conversion between 100mA, 20mA and 4mA can be realized. The main controller controls each relay separately by controlling the drive register U23, thereby realizing this conversion. The control truth table is shown in Table 2 below:

[0075] CTL1 CTL2 CTL3 100mA 0 1 1 20mA 1 0 1 4mA 1 1 0

[0076] Table 2

[0077] The output end of the current sampling unit outputs the FBI signal and the FB signal respectively, the output end outputting the FBI signal constitutes the current signal sampling end of the multi-speed current output unit, and the FB signal is connected to the DA signal amplitude control unit;

[0078] In this embodiment, the current sampling unit includes a first-stage amplifier composed of an amplifier U32B and its peripheral circuits and a second-stage amplifier composed of U32A. The negative input terminal of U32B is connected to the ground wire through a resistor R116, the positive input terminal is connected to the US signal through a resistor R113, and the output terminal outputs the FBI signal. One end of the resistor R121 is connected to the negative input terminal of the amplifier U32B, and the other end is connected to the negative output terminal of the amplifier U32B.

[0079] The FBI signal is connected to the positive input terminal of the amplifier U32A, the negative input terminal of the amplifier U32A is connected to its output terminal, and the negative output terminal of the amplifier U32A outputs the FB signal, which is sent to the DA signal amplitude control unit as a current feedback signal. The DA signal amplitude control unit is used to control the output amplitude of the power amplifier unit; the DA signal amplitude control unit is respectively connected to the power amplifier enable unit, the 1st and 2nd pins of the transformer TI1, and the power amplifier unit; the test signal input terminal of the DA signal amplitude control unit constitutes the test terminal of the multi-speed current output unit; the input terminal of the DA signal amplitude control unit constitutes the input terminal of the multi-speed current output unit; the control terminal of the DA signal amplitude control unit constitutes the control terminal B of the multi-speed current output unit, and the output terminal of the filter unit is also connected to the control terminal of the DA signal amplitude control unit; the output terminal of the power amplifier unit is connected to the 2nd pin of the transformer TI1.

[0080] The power amplifier enabling unit is a constant current drive circuit composed of a resistor R98, a diode D18, a voltage regulator U33, a transistor Q5, a transistor Q6 and a diode D19, and resistors R105, R99, R110, R114, R115, R125, R123, R118, capacitors C119, C124, C140 and C141 are all peripheral circuits in the constant current drive circuit;

[0081] The constant current driving circuit provides a B+ signal and a B- signal for driving the power amplifier driving signal unit. The B+ signal is output from the K terminal of the voltage regulator U33, and the B- signal is output from the A terminal of U33.

[0082] The / EN signal is input to the constant current drive circuit through the resistor R98, and is used to control the opening of the constant current drive circuit. Specifically, the / EN signal is connected to the base of the transistor Q5 through the resistors R98 and R99, and the positive electrode of the diode D18 is connected to an OVLD signal output from the input end of the fault detection unit. The model of the voltage regulator U33 is TL431. The output end of the power amplifier drive signal unit outputs the UP signal and DOWN signal used to control the power amplifier unit.

[0083] The power amplifier unit is a power amplifier circuit composed of transistor Q7, transistor Q8, transistor Q9, transistor Q10, field effect transistor Q12 and field effect transistor Q11. Transistor Q8, transistor Q9 and field effect transistor Q12 are used to amplify the rising edge signal, and transistor Q7, transistor Q10 and field effect transistor Q11 are used to amplify the falling edge signal. The UP signal is input to the base of transistor Q8, and the DOWM signal is input to the base of transistor Q7. The D pole of field effect transistor Q12 and the D pole of field effect transistor Q11 together constitute the output end of the power amplifier unit, which is used to output the MOS signal used to control the transformer TI1. The MOS signal is connected to pin 2 of the transformer TI1.

[0084] The fault detection unit includes an operational amplifier U17A, an operational amplifier U17B, a resistor R38, a resistor R45, a resistor R37, a resistor R44, a resistor R46, a resistor R53, a capacitor C68, an operational amplifier U24A, a capacitor C82, a diode D3, a resistor R58, a diode D4, a resistor R60, a resistor R70, a diode D8, a resistor R71, a resistor R75, a resistor R87, a resistor R83, an LED lamp D17 and a transistor Q2. After the resistor R37 and the resistor R38 are connected in series, one end is connected to the TEST signal emitted by the multi-speed current output unit, and the other end is connected to the ground wire. Pin 2 of the operational amplifier U17A is connected to the connection node of the resistor R37 and the resistor R38, pin 3 is connected to the +15V power supply through the resistor R45, and pin 1 is connected to the positive electrode of the diode D3. Pin 6 of the operational amplifier U17B is connected to the -15V power supply through the resistor R46, and pin 5 is connected to the operational amplifier Pin 2 and Pin 7 of U17A are connected to Pin 1 of operational amplifier U17A, resistor R44 is connected between Pin 3 of operational amplifier U17A and Pin 6 of operational amplifier U17B, resistor R53 is a pull-up resistor for Pin 1 of operational amplifier U17A, capacitor C68 is connected in parallel with resistor R53, the cathode of diode D3 is connected to Pin 2 of operational amplifier U24A, resistor R58 is connected in parallel with diode D3, diode D3 is also connected to the anode of diode D4, Pin 3 of operational amplifier U24A is connected to Pin 6 of operational amplifier U17B, Pin 1 is connected to the anode of diode D8, the cathode of diode D8 is connected to Pin 5 of operational amplifier U24B, Pin 6 of operational amplifier U24B is connected to +15V power supply through resistor R70, and Pin 7 outputs VOLD signal, the cathode of diode D4 is connected to Pin 6 of operational amplifier U24B through resistor R60, and Pin 6 of operational amplifier U24B is also connected to / EN signal;

[0085] Pin 5 of the operational amplifier U24B is connected to a -15V power supply through a resistor R71, and a resistor R75 is connected between pins 5 and 7 of the operational amplifier U24B; pin 7 of the operational amplifier U24B is connected to the base of the transistor Q2 through a resistor R87, and the emitter of the transistor Q2 is connected to the ground wire, and the collector is connected to a control signal FAIL signal output by the isolator U18 through the resistor R61;

[0086] The positive electrode of LED lamp D17 is connected to pin 7 of operational amplifier U24B through resistor R83, and the negative electrode is connected to the ground wire. The FAIL signal is first isolated by isolator U18, and after generating signal FAILOUT, it is sent to an IO port of the main controller for further identification. The fault detection unit determines whether a fault occurs by detecting the signal output by differential amplifier U28A.

[0087] The operational amplifier U17A and the operational amplifier U17B are both LM393, and the operational amplifier U24A and the operational amplifier U24B are both LM358N. The DA signal generating unit includes a resistor R49, an isolator U18, a resistor R61, a DA chip U26 and a DA signal isolation amplification unit; the input end of the isolator U18 is connected to a group of IO ports of the main controller through the resistor R49, and the output end is connected to the input end of the DA chip U26 through the resistor R61, and the output end of the DA chip U26 is connected to the DA signal amplification isolation unit. The DA signal amplification isolation unit constitutes the output end of the DA signal generating unit and outputs the SIN signal. The connection end of the resistor R49 and the main controller constitutes the input end of the DA signal generating unit;

[0088] In this embodiment, the isolator U18 is used to isolate the control end of the DA chip U26 from the main controller. Specifically, the SCK2 signal, SDIN2 signal, and SLD2 signal sent by the main controller are isolated by the isolator U18 and converted into SCK signal, SDIN signal, and SLD signal and input to pins 7, 6, and 5 of U26. The model of the DA chip U26 is LTC1595, which is powered by a 5V power supply. The reference voltage of the DA chip U26 is the reference voltage Vre10V provided by the second reference voltage module. The DA signal isolation amplifier unit is a two-stage amplifier circuit composed of amplifier U27A and amplifier U27B. Amplifier U27A is the first-stage amplifier circuit, and amplifier U27B is the second-stage amplifier circuit. Capacitors C100, C99, and C97 are all peripheral circuits of amplifier U27A. Resistors R79, R82, R92, and capacitor C109 are all peripheral circuits of amplifier U27B. The positive input of amplifier U27A is connected to the ground wire, the negative input is connected to the OUT of DA chip U26, and the output is connected to the negative input of amplifier U27B through resistor R82. The positive input of amplifier U27B is connected to the ground wire, and the output outputs the SIN signal. The models of amplifier U27A and amplifier U27B are both OP2177, and the model of isolator U18 is ADuM1401CRWZ.

[0089] The DA signal amplitude control unit includes a first isolation unit, a DA chip U22, a second isolation unit, a differential amplifier U28A, a transformer signal amplification unit and a power amplifier driving unit. The input end of the first isolation unit constitutes the input end of the DA signal amplitude control unit, the input end of the first isolation unit is connected to the output end of the DA signal amplification isolation unit, and the output end is connected to the input end of the DA chip U22. The control end of the DA chip U22 constitutes the control end of the DA signal amplitude control unit. The output end of the DA chip U22 is connected to the positive input end of the differential amplifier U28A through the second isolation unit, and the FB signal is connected to the positive input end of the differential amplifier U28A.

[0090] The negative input end of the differential amplifier U28A is connected to the output end of the transformer signal amplification unit, and the input end of the transformer signal amplification unit is connected to the 1st pin of the transformer TI1; the differential amplifier U28A is also connected to the 2nd pin of the transformer TI1 and the test signal input end of the DA signal amplitude control unit respectively, and the output end of the differential amplifier U28A is connected to the input end of the power amplifier drive signal unit, and the control end of the power amplifier drive signal unit is connected to the power amplifier enable unit, and the output end is connected to the power amplifier unit. In this embodiment, the first isolation unit is an amplification isolation circuit composed of an amplifier U19B, and resistors R41, R39, R50, capacitor C62, and C63 are all peripheral circuits of the amplifier U19B. The positive input end of the amplifier U19B is connected to the SIN signal through resistors R41 and R50 connected in series, and the output end is connected to the VREF end of the DA chip U22, and the OUT end of the DA chip U22 is connected to the negative input end of the amplifier U19A; the DA chip U22 is powered by a 5V power supply, and the model of the DA chip U22 is LTC1595BCS8. The second isolation unit is an amplifying isolation circuit composed of an amplifier U19A, and the output end of the amplifier U19A is connected to the positive input end of the differential amplifier U28A through a resistor R74. The models of amplifier U19A and amplifier U19B are both OP2177. The FB signal is also connected to the positive input end of the differential amplifier U28A through a resistor RF1; resistors R77, R78, R93, R86, R85, ER2, R94, capacitors C108, C112, C110, and C117 are all peripheral circuits of the differential amplifier U28A. The output end of the differential amplifier U28A also outputs a TEST signal for testing.

[0091] The transformer signal amplification unit is an amplifier circuit composed of amplifier U28B. The negative input terminal of amplifier U28B is connected to the 1-pin of transformer TI1 through resistor R72. The negative input terminal of amplifier U28B is also connected to a 3.6V voltage-stabilizing diode. Resistor ER1 and capacitor C101 are peripheral circuits of amplifier U28B. The output terminal of amplifier U28B is connected to the negative input terminal of amplifier U28A through resistor R78. The models of amplifier U28B and amplifier U28A are both OP2177.

[0092] The power amplifier drive signal unit is used to provide a drive signal for the power amplifier unit, including transistor Q4, transistor Q3, resistor R104, and resistor R103. The base of transistor Q4 and the base of transistor Q3 constitute the control end of the power amplifier drive signal unit, and are both connected to the power amplifier enable unit, used to receive the enable signal sent by the power amplifier enable unit, the base B+ signal and the B- signal, the emitter of transistor Q4 is connected to one end of resistor R94 through resistor R104, and the other end of resistor R94 is connected to the output end of amplifier U28A, the emitter of transistor Q3 is connected to one end of resistor R94, and the collector of transistor Q4 and the collector of transistor Q3 constitute the output end of the power amplifier drive signal unit, which outputs the UP signal and DOWN signal for controlling the power amplifier unit. The emitter of transistor Q3 and the emitter of transistor Q4 constitute the input end of the power amplifier drive signal unit.

[0093] The current AD conversion unit includes an amplifier unit, an AD chip U31, a resistor R80, an isolator U29 and a resistor R100. The input end of the amplifier unit constitutes the input end of the current AD conversion unit. The input end of the amplifier unit is connected to the FBI signal, and the output end is connected to the AD chip U31. The output end of the AD chip U31 is connected to the input end of the isolator U29 through the resistor R80. The output end of the isolator U29 is connected to the main controller through the resistor R100. The connection end of the resistor R100 and the main controller constitutes the output end of the current AD conversion unit.

[0094] In this embodiment, the amplification unit is a current amplification circuit composed of an amplifier U30A and an amplifier U30B. The amplifier U30A constitutes a first-stage amplification circuit, and the amplifier U30B constitutes a second-stage amplification circuit. Resistors R81, R88, C107, and C113 constitute the peripheral circuit of the amplifier U30A. Resistors R96, R101, C118, R106, and C127 constitute the peripheral circuit of the amplifier U30B. The FBI signal enters the positive input terminal of the amplifier U30A from resistors R81 and R88, and after first-stage amplification of the amplifier U30A, it is input to the negative input terminal of the amplifier U30B. After second-stage amplification of the amplifier U30B, it is output to the input terminal of the AD chip U31, i.e., IN+ of the AD chip U31.

[0095] The control end of the AD chip U31 is connected to the main controller after being isolated by the isolator U29. Specifically, the 8th, 7th and 6th pins of the AD chip U31 are respectively connected to the SCLK1 signal, SDOUT signal and CNVA signal. The SCLK1 signal, SDOUT signal and CNVA signal are obtained after the isolator U29 isolates the SCLK2 signal, CNVA2 signal and SDOUT2 signal sent by the main controller.

[0096] The reference voltage of the AD chip U31 is the reference voltage Vre5V.

[0097] The model of isolator U29 is ADuM14101CRWZ, the model of AD chip U31 is AD7685, and the model of amplifier U30A and amplifier U30B are both OP2177.

[0098] The second reference voltage module includes a power chip U20, a first reference voltage generating unit and a second reference voltage generating unit. The output end of the power chip U20 is respectively connected to the first reference voltage generating unit and the second reference voltage generating unit, and outputs a reference voltage Vre5V. The first reference voltage generating unit and the second reference voltage generating unit respectively output a reference voltage Vre2V and a reference voltage Vre10V. The reference voltage Vre5V and the reference voltage Vre2V provide reference voltages for the AD chip U31 and the amplification unit respectively, and the reference voltage Vre10V provides a reference voltage for the DA chip U26.

[0099] In this embodiment, the model of the power chip U20 is MAX6250ACSA, the first reference voltage generating unit is composed of an amplifier U25A and its peripheral circuits, the second reference voltage generating unit is composed of an amplifier U25B and its peripheral circuits, the output terminal OUT of the power chip U20 is connected to the positive input terminal of the amplifier U25B, and outputs a reference voltage Vre5V;

[0100] The output end of the amplifier U25B is connected to the base of the transistor Q1 through the resistor R73, the emitter of the transistor Q1 is connected to the negative input end of the amplifier U25B through the resistor R68, and the emitter of the transistor Q1 outputs the reference voltage Vre10V.

[0101] The OUT terminal of the power chip U20 is divided by the voltage-dividing resistors R64 and R63, and then input to the positive input terminal of the amplifier U25A. The output terminal of U25A outputs the reference voltage Vre2V.

[0102] Amplifier U25B and amplifier U25A are both OP2177.

[0103] The leakage protection tester described in the present invention solves the technical problem of being able to output a small current of high-precision multi-gear AC mA level and being able to collect the voltage at both ends of the leakage action device in a graded manner. The present invention can output high-precision mA-level AC current and has three gears of 4mA, 20mA and 100mA. The three gears can be selected according to the requirements, and support hierarchical real-time voltage collection and detection and voltage display of the leakage action device. The voltage record during leakage action greatly reduces manual recording, and is more intelligent, more convenient and more efficient.

Claims

1. A leakage protection tester, characterized in that: It includes a voltage sampling circuit, a voltage signal processing unit, a voltage signal isolation unit, a first reference voltage module, a relay signal isolation unit, a current output interface, a multi-speed current output unit, a control signal isolation unit, a fault detection unit, a current AD conversion unit, a DA signal generation unit, a second reference voltage module, a main controller, a display screen, a button group and a power supply module, and the display screen and the button group are connected to the main controller; The input end of the voltage sampling circuit is connected to the voltage signal input interface, the output end is connected to the voltage signal processing unit, the control end is connected to the output end of the relay signal isolation unit, and the input end of the relay signal isolation unit is connected to the main controller; The output end of the voltage signal processing unit is connected to the input end of the voltage signal isolation unit, the output end of the voltage signal isolation unit is connected to the main controller, and the first reference voltage module provides a reference voltage for the voltage signal processing unit; The voltage sampling circuit is used to collect the voltage signal of the external voltage source, and after isolating and AD converting the voltage signal through the voltage signal processing unit, it is sent to the main controller; The relay signal isolation unit is used to receive the relay control signal sent by the main controller and transmit the relay control signal to the voltage sampling circuit. The voltage sampling circuit is used to control the voltage-dividing relay and the electronic switch inside itself according to the relay control signal. The voltage-dividing relay is used to select different voltage-dividing resistor networks in the voltage sampling circuit, and the electronic switch is used to adjust the gain of the amplifier in the voltage sampling circuit. The output end of the multi-speed current output unit is connected to the current output interface, the control end is connected to the output end of the control signal isolation unit, the input end is connected to the output end of the DA signal generation unit, the test end is connected to the input end of the fault detection unit, and the current signal sampling end is connected to the input end of the current AD conversion unit; The multi-level current output unit is used to output current signals of several different levels; The input end of the control signal isolation unit is connected to the main controller, the output end of the current AD conversion unit is connected to the main controller, and the second reference voltage module provides a reference voltage for the current AD conversion unit; The power supply module supplies power to the voltage sampling circuit, the voltage signal processing unit, the voltage signal isolation unit, the first reference voltage module, the relay signal isolation unit, the current output interface, the multi-speed current output unit, the control signal isolation unit, the fault detection unit, the current AD conversion unit, the DA signal generating unit and the second reference voltage module.

2. A leakage protection tester as claimed in claim 1, characterized in that: The power supply module includes a 15V power supply module, a 5V power supply module, a first 3.3V power supply module and a second 3.3V power supply module, the input end of the 15V power supply module is connected to an external +13.5V power supply and a -13.5V power supply, and the output end outputs a +15V power supply and a -15V power supply; The input end of the 5V power module is connected to +15V power supply and -15V power supply, and the output end outputs 5V power supply; The input end of the first 3.3V power module is connected to a 5V power supply, and the output end outputs a 3.3VCC power supply. The input end of the second 3.3V power module is connected to a 5V power supply, and the output end outputs a M3.3V power supply.

3. A leakage protection tester as claimed in claim 1, characterized in that: The voltage sampling circuit includes a buffer U1, a signal input interface J1, a voltage division channel selection circuit, an amplification isolation circuit, a differential amplification circuit, a controllable gain amplification circuit and an electronic switch U10, the input end of the buffer U1 is connected to the X1 / 2I signal output by the output end of the relay signal isolation unit, and the output end outputs the X1 / 2 signal; The signal input interface J1 is used to connect the voltage signal of the external voltage source; The input end of the voltage-dividing channel selection circuit is connected to the signal input interface J1, the control end is connected to the X1 / 2 signal, and the output end is connected to the input end of the amplifying isolation circuit. The output end of the amplifying isolation circuit is connected to the input end of the differential amplifying circuit. The output end of the differential amplifying circuit is connected to the input end of the controllable gain amplifying circuit. The output end of the controllable gain amplifying circuit outputs the FBSIN signal and is connected to the input end of the voltage signal processing unit. The X5 signal outputted from the output end of the relay signal isolation unit is connected to the gain control end of the controllable gain amplifier circuit; The gain control terminal of the controllable gain amplifier circuit and the input terminal of the buffer U1 constitute the control terminal of the voltage sampling circuit.

4. A leakage protection tester as claimed in claim 1, characterized in that: The voltage signal processing unit includes an isolated voltage amplifier circuit and an AD module U13, the input end of the isolated voltage amplifier circuit constitutes the input end of the voltage signal processing unit, the output end is connected to the input end of the AD module U13, and the output end of the AD module U13 constitutes the output end of the voltage signal processing unit; The first reference voltage module provides reference voltage for the isolation voltage amplifier circuit and the AD module U13 respectively; The voltage signal isolation unit includes an isolator U9 and a resistor R17. The input end of the isolator U9 constitutes the input end of the voltage signal isolation unit. The input end of the isolator U9 is connected to the output end of the AD module U13, and the output end is connected to a group of IO ports of the main controller through the resistor R17; the connection end of the resistor R17 and the main controller constitutes the output end of the voltage signal isolation unit; The relay signal isolation unit includes an isolator U8 and a resistor R16. The input end of the isolator U8 is connected to the main controller through the resistor R16. The output end of the isolator U8 constitutes the output end of the relay signal isolation unit. The connection end of the resistor R16 and the main controller constitutes the input end of the relay signal isolation unit.

5. A leakage protection tester as claimed in claim 1, characterized in that: The control signal isolation unit includes a driving register U23, a filtering unit, a resistor R67, an isolator U21 and a resistor R51. The output end of the driving register U23 constitutes the output end of the control signal isolation unit. The input end of the driving register U23 is connected to the output end of the filtering unit. The input end of the filtering unit is connected to the output end of the isolator U21 through the resistor R67. The input end of the isolator U21 is connected to a group of IO ports of the main controller through the resistor R51. The output of the filter unit also outputs a / 1595 signal; The output end of the driving register U23 outputs CTL1 signal, CTL2 signal, CTL3 signal and / EN signal respectively; The multi-speed current output unit includes a relay group unit, a current sampling unit, a transformer TI1, a power amplifier unit, a power amplifier enabling unit and a DA signal amplitude control unit; The control end of the multi-speed current output unit includes a control end A and a control end B; The control end of the relay group unit constitutes the control end A of the multi-speed current output unit, and the output end constitutes the output end of the multi-speed current output unit; The relay group unit includes three relay groups, the coil control ends of the three relay groups constitute the control end of the relay group unit, and the coil control ends of the three relay groups are all controlled in parallel through parallel signals, and the parallel signals are composed of CTL1 signal, CTL2 signal and CTL3 signal; In the three relay groups, the common contacts of each relay group are connected together to form three common output terminals, which constitute the output terminals of the relay group unit. The normally open contacts of each relay group constitute the relay input terminals of the group, which constitute three relay input terminals, which constitute the input terminals of the relay group unit. A relay input terminal is connected to pins 3, 4 and 5 of transformer TI1, and its corresponding common output terminal is connected to the current output interface; The other two relay input terminals are connected to the 6th pin of the transformer TI1, and the corresponding two common output terminals, one is connected to the current output interface, and the other outputs the US signal and is connected to the input terminal of the current sampling unit; The output end of the current sampling unit outputs the FBI signal and the FB signal respectively, the output end outputting the FBI signal constitutes the current signal sampling end of the multi-speed current output unit, and the FB signal is connected to the DA signal amplitude control unit; The DA signal amplitude control unit is used to control the output amplitude of the power amplifier unit; The DA signal amplitude control unit is respectively connected to the power amplifier enabling unit, pins 1 and 2 of the transformer TI1, and the power amplifier unit; The test signal input terminal of the DA signal amplitude control unit constitutes the test terminal of the multi-level current output unit; The input end of the DA signal amplitude control unit constitutes the input end of the multi-level current output unit; The control end of the DA signal amplitude control unit constitutes the control end B of the multi-speed current output unit, and the output end of the filter unit is also connected to the control end of the DA signal amplitude control unit; The output end of the power amplifier unit is connected to pin 2 of transformer TI1.

6. A leakage protection tester as claimed in claim 5, characterized in that: The DA signal generating unit includes a resistor R49, an isolator U18, a resistor R61, a DA chip U26 and a DA signal isolation amplification unit; The input end of the isolator U18 is connected to a group of IO ports of the main controller through the resistor R49, and the output end is connected to the input end of the DA chip U26 through the resistor R61. The output end of the DA chip U26 is connected to the DA signal amplification isolation unit. The DA signal amplification isolation unit constitutes the output end of the DA signal generation unit and outputs the SIN signal. The connection end of the resistor R49 and the main controller constitutes the input end of the DA signal generation unit. The DA signal amplitude control unit includes a first isolation unit, a DA chip U22, a second isolation unit, a differential amplifier U28A, a transformer signal amplification unit and a power amplifier driving unit. The input end of the first isolation unit constitutes the input end of the DA signal amplitude control unit, the input end of the first isolation unit is connected to the output end of the DA signal amplification isolation unit, and the output end is connected to the input end of the DA chip U22. The control end of the DA chip U22 constitutes the control end of the DA signal amplitude control unit. The output end of the DA chip U22 is connected to the positive input end of the differential amplifier U28A through the second isolation unit, and the FB signal is connected to the positive input end of the differential amplifier U28A. The negative input terminal of the differential amplifier U28A is connected to the output terminal of the transformer signal amplification unit, and the input terminal of the transformer signal amplification unit is connected to the 1st pin of the transformer TI1; The differential amplifier U28A is also connected to pin 2 of the transformer TI1 and the test signal input end of the DA signal amplitude control unit respectively. The output end of the differential amplifier U28A is connected to the input end of the power amplifier drive signal unit. The control end of the power amplifier drive signal unit is connected to the power amplifier enable unit, and the output end is connected to the power amplifier unit.

7. A leakage protection tester as claimed in claim 6, characterized in that: The current AD conversion unit includes an amplifier unit, an AD chip U31, a resistor R80, an isolator U29 and a resistor R100. The input end of the amplifier unit constitutes the input end of the current AD conversion unit. The input end of the amplifier unit is connected to the FBI signal, and the output end is connected to the AD chip U31. The output end of the AD chip U31 is connected to the input end of the isolator U29 through the resistor R80. The output end of the isolator U29 is connected to the main controller through the resistor R100. The connection end of the resistor R100 and the main controller constitutes the output end of the current AD conversion unit. The second reference voltage module includes a power chip U20, a first reference voltage generating unit and a second reference voltage generating unit. The output end of the power chip U20 is respectively connected to the first reference voltage generating unit and the second reference voltage generating unit, and outputs a reference voltage Vre5V. The first reference voltage generating unit and the second reference voltage generating unit respectively output a reference voltage Vre2V and a reference voltage Vre10V. The reference voltage Vre5V and the reference voltage Vre2V provide reference voltages for the AD chip U31 and the amplification unit respectively, and the reference voltage Vre10V provides a reference voltage for the DA chip U26.

8. A leakage protection tester as claimed in claim 7, characterized in that: The fault detection unit includes an operational amplifier U17A, an operational amplifier U17B, a resistor R38, a resistor R45, a resistor R37, a resistor R44, a resistor R46, a resistor R53, a capacitor C68, an operational amplifier U24A, a capacitor C82, a diode D3, a resistor R58, a diode D4, a resistor R60, a resistor R70, a diode D8, a resistor R71, a resistor R75, a resistor R87, a resistor R83, an LED lamp D17 and a transistor Q2. After the resistor R37 and the resistor R38 are connected in series, one end is connected to the TEST signal emitted by the multi-speed current output unit, and the other end is connected to the ground wire. Pin 2 of the operational amplifier U17A is connected to the connection node of the resistor R37 and the resistor R38, pin 3 is connected to the +15V power supply through the resistor R45, and pin 1 is connected to the positive electrode of the diode D3. Pin 6 of the operational amplifier U17B is connected to the -15V power supply through the resistor R46, and pin 5 is connected to the operational amplifier. Pin 2 and pin 7 of the device U17A are connected to pin 1 of the operational amplifier U17A, resistor R44 is connected between pin 3 of the operational amplifier U17A and pin 6 of the operational amplifier U17B, resistor R53 is a pull-up resistor for pin 1 of the operational amplifier U17A, capacitor C68 is connected in parallel with resistor R53, the cathode of diode D3 is connected to pin 2 of the operational amplifier U24A, resistor R58 is connected in parallel with diode D3, diode D3 is also connected to the anode of diode D4, pin 3 of the operational amplifier U24A is connected to pin 6 of the operational amplifier U17B, pin 1 is connected to the anode of diode D8, the cathode of diode D8 is connected to pin 5 of the operational amplifier U24B, pin 6 of the operational amplifier U24B is connected to a +15V power supply through resistor R70, and pin 7 outputs a VOLD signal, the cathode of diode D4 is connected to pin 6 of the operational amplifier U24B through resistor R60, and pin 6 of the operational amplifier U24B is also connected to the / EN signal; Pin 5 of the operational amplifier U24B is connected to a -15V power supply through a resistor R71, and a resistor R75 is connected between pins 5 and 7 of the operational amplifier U24B; Pin 7 of the operational amplifier U24B is connected to the base of the transistor Q2 through the resistor R87, the emitter of the transistor Q2 is connected to the ground wire, and the collector is connected to a control signal FAIL signal output by the isolator U18 through the resistor R61; The positive electrode of LED lamp D17 is connected to pin 7 of operational amplifier U24B through resistor R83, and the negative electrode is connected to the ground wire.

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