CN217238178U

CN217238178U - Detection AC/DC source simply applied to sampling circuit

Info

Publication number: CN217238178U
Application number: CN202220083239.XU
Authority: CN
Inventors: 刘苏成; 王国俊; 李杨
Original assignee: Nanjing Apaitek Technology Co ltd
Current assignee: Nanjing Apaitek Technology Co ltd
Priority date: 2022-01-13
Filing date: 2022-01-13
Publication date: 2022-08-19
Anticipated expiration: 2032-01-13

Abstract

The invention discloses a simple AC/DC detection source applied to a sampling circuit, which comprises a variable reference source circuit, a sampling circuit and a sampling circuit, wherein the variable reference source circuit outputs a DC or AC reference power supply to an AC/DC power supply circuit; the AC-DC circuit outputs a DC or AC power supply applied to the sampling circuit to be tested; the alternating current and direct current source circuit comprises an operational amplifier U1, an operational amplifier U2 and a drive push-pull circuit; the driving push-pull circuit comprises tubes Q1, Q2, Q3 and Q4; the input of the reference source is connected to R2, a negative feedback circuit is formed by pin 2 of U1 and R1, and pin 1 of U1 outputs. The output port serial R3 is connected to the 6 pins of the U1, the 3 pins and the 5 pins of the U1 are grounded, and the 7 pins are connected with the R5 in series and used as a driving source of a push-pull circuit. The U2 functions to form a closed loop by collecting the output driving current value and the input reference value of the operational amplifier U1, so that the output current does not change along with the change of the load resistance value. The actual test value of the circuit can reach a voltage value of 7V, so that the full-load detection requirement of the board-level sampling circuit is met.

Description

Detection AC/DC source simply applied to sampling circuit

Technical Field

The invention relates to the technical field of power electronics, in particular to a detection alternating current and direct current source which is simply applied to a sampling circuit.

Background

With the continuous development of power electronic technology, the fast response and protection of the control and protection of power electronic equipment are gradually improved and perfected, and the monitoring of important voltages, currents and temperatures of all levels in an equipment system in a control unit becomes the important factor of design requirements. The control unit is provided with a plurality of sampling circuits related to voltage, current and temperature, and the circuits are all analog circuits, and the circuit devices are many and complicated. The frequency of related circuit faults is high in the control single-board faults after welding, if the circuits cannot be guaranteed to be intact, the circuits are directly electrified and tested in equipment, false operation is easy to occur under the abnormal condition (most of sampling circuits are abnormal only when voltage and current occur after the equipment is started), or key devices of the equipment and other related important equipment in a system are directly damaged, and the consequence is immeasurable. Therefore, when the control board is assembled in the equipment, the sampling circuits of all stages of the control board are ensured to be error-free, and the first important task of the control board after welding is the detection of all functional circuits of the single board. The current common simpler equipment adopts an adjustable voltage-stabilizing source, sampling circuits of related voltage, current and temperature can carry out rough test, and high-end equipment which has higher requirements and can generate alternating current and direct current voltage and current is debugged, for example, a relay protection instrument carries out pertinence test of different adopted circuits.

These two detection schemes are also necessary in practical applications, but have several disadvantages: 1) the adjustable voltage-stabilizing source is used, because the output voltage can only be voltage, the current signal is sampled aiming at the alternating current and direct current circuit, and the input sampling resistor is arranged in the sampling circuit to convert the current signal into the voltage type. If the sampling resistor parameters are abnormal, the sampling resistor can be omitted by using the adjustable voltage-stabilizing source to input voltage parameters, so that the sampling circuit is abnormal and the fault cannot be detected; 2) the high-end equipment is used for testing, voltage and current signals can be output, the equipment is complex in configuration, parameters are required to be adjusted and switched continuously according to different sampling circuits, the workload and the working procedure are complex and prone to error, and the equipment is large and heavy and is not beneficial to transportation and relocation.

Disclosure of Invention

1. The technical problem to be solved is as follows:

in view of the above technical problems, the present invention provides a detection ac/dc source that is simply applied to a sampling circuit, which is a detection ac/dc source for sampling circuits of different ac/dc voltages, currents and temperatures of power electronic devices, and which has a small volume and high precision, and can meet the requirements of setting and debugging analog parameter values of input sources by different sampling circuits. Accurate detection parameters are provided for the control panel, and the working efficiency of the control panel in the single-board detection process is further improved.

2. The technical scheme is as follows:

the utility model provides a detection AC/DC source of simple and easy application in sampling circuit which characterized in that: the device comprises a variable reference source circuit and an alternating current and direct current source circuit; the variable reference source circuit outputs a direct current reference power supply or an alternating current reference power supply to the alternating current and direct current source circuit; the AC-DC circuit outputs a DC or AC power supply applied to the sampling circuit to be tested.

The alternating current and direct current source circuit comprises an operational amplifier U1, an operational amplifier U2 and a drive push-pull circuit; the operational amplifier U1 and the operational amplifier U2 are operational amplifier chips with the model number of OPA 2188; the driving push-pull circuit comprises tubes Q1, Q2, Q3 and Q4; wherein, the Q1 and Q2 are NPN tubes; the tubes Q3 and Q4 are PNP tubes; the specific connection mode of the alternating current and direct current source circuit is as follows: a reference source REF-IN output by the variable reference source circuit is connected to one end of a resistor R2, the other end of the resistor R2 is connected to a pin 2 of the operational amplifier U1, and a resistor R1 is connected IN parallel between the pin 2 and the pin 1 of the operational amplifier U1; a pin 1 of the operational amplifier U1 is connected in series with a resistor R3 and then is connected to a pin 6 of the operational amplifier U1; the 7-pin series resistor R5 of the operational amplifier U1 is connected to the base electrodes of the transistors Q1, Q2, Q3 and Q4; the

pins

3 and 5 of the operational amplifier U1 are grounded; the junction of the resistor R3 and the operational amplifier U1 is also connected to the base electrodes of the transistors Q1, Q2, Q3 and Q4 after passing through the capacitor C1; the input end RL1 of the sampling circuit to be tested is connected with the current sampling resistor R8; one end of the current sampling resistor R8 is connected with the resistor R11 and then is connected with the pin 5 of the operational amplifier U2; the 6 feet and the 7 feet of the operational amplifier U2 are in short circuit; the 6-pin series resistor R10 of the operational amplifier U2 is connected to the 2-pin of the operational amplifier U2; two ends of a pin 2 of the operational amplifier U2 and two ends of a pin 1 of the operational amplifier U2 are connected with a resistor R9 in parallel; the 2-pin series resistor R4 of the operational amplifier U2 is connected to the 6-pin of the operational amplifier U2; the 3-pin series resistor R6 of the operational amplifier U2 is connected to the 5-pin of the operational amplifier U1; the other end of the current sampling resistor R8 is connected to the rear connecting resistor R7 of the emitters of the tubes Q1, Q2, Q3 and Q4 and then is connected to the connection position of the resistor R6 and the operational amplifier U2; two branches of the driving push-pull circuit after the tubes Q1 and Q3 are connected in series and Q2 and Q4 are connected in series are connected in parallel; the collectors of the transistors Q1 and Q2 are connected to the positive pole of the power supply; the collectors of the tubes Q3 and Q4 are connected to the negative pole of the power supply.

Furthermore, 8 pins of the operational amplifier U1 and the operational amplifier U2 are both connected to the positive pole of a power supply, and 4 pins are both connected to the negative pole of the power supply.

Further, the power supplies of the operational amplifier U1, the operational amplifier U2 and the driving push-pull circuit are all 15V.

Further, the tubes Q1, Q2 are both model MJD 122; the tubes Q3, Q4 are both model MJD 127.

3. Has the advantages that:

(1) the invention provides a simple AC/DC source detection device applied to a sampling circuit, which is characterized in that the functions of a variable reference source circuit and an AC/DC source circuit are realized; since the variable reference source circuit is a conventional circuit, it is not described in detail. The AC/DC source circuit part is mainly applied to the characteristic of an operational amplifier closed loop, and a proper resistance parameter is matched through the principles of 'virtual short' and 'virtual break' of the operational amplifier to obtain a current value which does not change along with the change of load resistance. The input reference value is equal to a direct current or alternating current reference value of 0-5V through a DA chip by a main control chip. And configuring a fixed input reference source according to different current sources required by sampling circuits in different power electronic equipment control boards. The output current can reach 5A, the input of the control board level large current alternating current CT5A level can be completely reached, the current value input to the board level by the Hall sensor and the PT sensor is smaller, and the output value is basically in mA level. For safe and reliable operation, the circuit is designed with a voltage design limit, and the voltage value of a sampling resistor of the sampling circuit after current conversion does not exceed 5V. The sampling of the leading cause control panel and the maximum voltage value that main control chip can handle are exactly 5V, and this patent circuit actual test value can reach 7V's voltage value, so to the full load demand of detection to board level sampling circuit completely.

(2) The invention provides an AC/DC source detection device which is simply applied to a sampling circuit, can provide an efficient detection means for the correct welding of the sampling circuit for controlling the voltage, the current and the temperature of a board level in an equipment system, and sets different input sources, overvoltage, overcurrent and overtemperature action threshold sources according to different sampling circuits. The circuit can be effectively adopted, the circuit is simple, only one main control chip needs to be built to obtain the reference source, the size is small, the cost is low, the equipment is convenient to move, the working efficiency of the control panel in the veneer detection flow is greatly improved, and particularly, the efficiency is more obvious when the control panel is used in mass production stage testing.

Drawings

Fig. 1 is a circuit diagram of an embodiment of an ac/dc source circuit according to the present invention.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings.

As shown in fig. 1, 2, a detection ac/dc source simply applied to a sampling circuit is characterized in that: the device comprises a variable reference source circuit and an alternating current and direct current source circuit; the variable reference source circuit outputs a direct current reference power supply or an alternating current reference power supply to the alternating current and direct current source circuit; the AC-DC circuit outputs a DC or AC power supply applied to the sampling circuit to be tested.

pins

3 and 5 of the operational amplifier U1 are grounded; the junction of the resistor R3 and the operational amplifier U1 is also connected to the base electrodes of the transistors Q1, Q2, Q3 and Q4 after passing through the capacitor C1; the input end RL1 of the sampling circuit to be tested is connected with the current sampling resistor R8; one end of the current sampling resistor R8 is connected with the resistor R11 and then is connected with the pin 5 of the operational amplifier U2; the 6 feet and the 7 feet of the operational amplifier U2 are in short circuit; the 6-pin series resistor R10 of the operational amplifier U2 is connected to the 2-pin of the operational amplifier U2; two ends of a pin 2 of the operational amplifier U2 and two ends of a pin 1 of the operational amplifier U2 are connected with a resistor R9 in parallel; the 2-pin series resistor R4 of the operational amplifier U2 is connected to the 6-pin of the operational amplifier U2; the 3-pin series resistor R6 of the operational amplifier U2 is connected to the 5-pin of the operational amplifier U1; the other end of the current sampling resistor R8 is connected to the rear connecting resistor R7 of the emitters of the tubes Q1, Q2, Q3 and Q4 and then is connected to the connection position of the resistor R6 and the operational amplifier U2; the two branches of the driving push-pull circuit after the tubes Q1 and Q3 are connected in series and the tubes Q2 and Q4 are connected in series are connected in parallel; the collectors of the transistors Q1 and Q2 are connected to the positive pole of the power supply; the collectors of the tubes Q3 and Q4 are connected to the negative pole of the power supply.

The circuit principle is as follows:

as shown IN figure 1, the circuit needs two direct current power supplies, +15V and-15V and AGND to provide power supplies for the operational amplifier and the output source, the power of the power supplies is selected according to the output current value, and the reference source REF _ IN is a variable reference source. The variable reference source can provide a 0-5V direct-current voltage source according to the requirements of the sampling circuit, and can also generate bias output maximum 5V alternating-current voltage through the conditioning operational amplifier. The common variable reference source circuit is a direct current reference power supply or an alternating current reference power supply which is formed by pulse modulation of a master control such as a DSP output and conversion through a DA chip. The AC/DC circuit inputs the DC reference power supply or the AC reference power supply output by the variable reference source circuit, and obtains a larger DC or AC power supply which is required to be applied to the sampling circuit to be tested through the operational amplifier circuit and the driving push-pull circuit.

Fig. 1 shows an embodiment of an ac/dc source circuit according to the present invention, which comprises an operational amplifier circuit and a driving output circuit.

As shown in the figure, in order to obtain a high-precision output source circuit, high-precision resistors with the precision of 0.1% are adopted in the resistors in the circuit. The operational amplifier is in an OPA2188 specification model, has high precision, strong anti-interference capability, zero drift of only 0.03 uV/DEG C, low noise and low quiescent current amplifier, provides high input impedance and rail-to-rail output with swing amplitude within 15mV of a power rail, and has excellent alternating current and direct current adjustment precision. The driving push-pull tube in the circuit adopts an NPN tube MJD122 and a PNP tube MJD 127. The single tube drives the current 8A, and the double tubes are connected in parallel, so that the output large current parameters are stable, the heating is not high, and the additional heat dissipation treatment is not needed.

The net point REN _ IN IN the circuit is an input of a reference source, is connected to R2, forms a negative feedback circuit through a pin 2 of the operational amplifier U1 and a resistor R1, and outputs through a pin 1 of the operational amplifier U1. The output port series resistor R3 is connected to the 6 feet of the operational amplifier U1, the 3 feet and the 5 feet of the operational amplifier are grounded, and the 7 feet of the operational amplifier are output series resistors R5 which are used as driving sources of a push-pull circuit and are connected to the base electrodes of 4 driving tubes Q1, Q2, Q3 and Q4. The capacitor C1 is used for filtering processing to enable the output AC/DC driving signal to be smoother and reduce unstable output of burrs. The 4 pins of the operational amplifier U1 are connected with a power supply of-15V, and the 8 pins are connected with a power supply of + 15V.

The operational amplifier U2 is used for collecting the output driving current value and the input reference value of the operational amplifier U1 to form a closed loop, so that the output current is not changed along with the change of the load resistance value. The resistor R8 is a sampling resistor of current, one end of the resistor R8 is connected to an input end RL1 (the load is not in the circuit) of a sampling circuit to be tested, and is simultaneously connected to the resistor R11, the other end of the resistor R11 is connected to a pin 5 of the operational amplifier U2, and a pin 6 and a pin 7 of the U2 are connected to form a follower, so that high impedance input is formed. The output of the pin 7 of the operational amplifier U2 is connected to the resistor R10, and the R10 is connected to the pin 2 of the operational amplifier U2 to form negative feedback with the resistor R9. The other end of the R8 is connected to the emitters of the driving tubes Q1, Q2, Q3 and Q4, and is simultaneously connected to a resistor R7, and a resistor R7 is connected to the pin 3 of the operational amplifier U2 and the resistor R6. The output of the operational amplifier U2 pin 1 is connected in series with a resistor R4 and then connected to the operational amplifier U1 pin 6. The 4 pins of the operational amplifier U2 are connected with a power supply of-15V, and the 8 pins are connected with a power supply of + 15V. Therefore, the closed-loop current source circuit consisting of the operational amplifier is completed through simple device construction.

The parameters of each stage of the circuit in the embodiment are presented in the circuit diagram, and are calculated as follows through the parameters of each stage in the circuit diagram: according to the 'virtual short' and 'virtual break' characteristics of the operational amplifier, the current flowing through the sampling resistor R8 is assumed to be I, and the voltage value of the input reference source REN _ IN is assumed to be Vref. Output voltage value of pin 1 of the operational amplifier U1: vu1_1 = -Vref × R1/R2 = -Vref. The voltage of the pin 6 of the operational amplifier U1 is synchronous with the voltage of the pin 5 of the U1, i.e., 0V, then the voltage value of the pin 1 output of the operational amplifier U2 is: vu2_1 = Vref × R4/R3 = Vref. Assuming that the upper end voltage of the sampling resistor R8 is Vr8_1 and the lower end voltage is Vr8_2, the voltage value of the pin 3 of the operational amplifier U2 is as follows: vu2_3 = Vr8_1 × R6/(R6 + R7) = 5 × Vr8_ 1/6; voltage value of 2 pins of the operational amplifier U2: vu2_2 = (Vr 8_2 × R9+ Vref × 10)/(R9 + R10) = (5 × Vr8_2+ Vref)/6. Since Vu2_3 = Vu2_2, then the scaling yields: 5 × Vr8_1 = 5 × Vr8_2+ Vref. The current flowing through the sampling resistor R8 is I = (Vr 8_1-Vr8_ 2)/0.2 to obtain the final conversion result: i = Vref. It can be seen that the current through resistor R8 is related only to the input reference voltage and is equal. And the resistor R11 is connected to the pin 5 of the U2, and according to the 'virtual break', the current is zero, and the current flowing through the sampling resistor R8 completely flows to the load RL1, and finally the whole AC-DC source current output circuit is completed.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The utility model provides a detection AC/DC source of simple and easy sampling circuit that is applied to which characterized in that: the device comprises a variable reference source circuit and an alternating current and direct current source circuit; the variable reference source circuit outputs a direct current reference power supply or an alternating current reference power supply to the alternating current direct current power supply circuit; the AC-DC circuit outputs a DC or AC power supply applied to the sampling circuit to be tested;

the alternating current and direct current source circuit comprises an operational amplifier U1, an operational amplifier U2 and a drive push-pull circuit; the operational amplifier U1 and the operational amplifier U2 are operational amplifier chips with the model number of OPA 2188; the driving push-pull circuit comprises tubes Q1, Q2, Q3 and Q4; wherein, the Q1 and Q2 are NPN tubes; the tubes Q3 and Q4 are PNP tubes; the specific connection mode of the alternating current and direct current source circuit is as follows: a reference source REF-IN output by the variable reference source circuit is connected to one end of a resistor R2, the other end of the resistor R2 is connected to a pin 2 of the operational amplifier U1, and a resistor R1 is connected IN parallel between the pin 2 and the pin 1 of the operational amplifier U1; a pin 1 of the operational amplifier U1 is connected in series with a resistor R3 and then is connected to a pin 6 of the operational amplifier U1; the 7-pin series resistor R5 of the operational amplifier U1 is connected to the base electrodes of the transistors Q1, Q2, Q3 and Q4; the pins 3 and 5 of the operational amplifier U1 are grounded; the junction of the resistor R3 and the operational amplifier U1 is also connected to the base electrodes of the transistors Q1, Q2, Q3 and Q4 after passing through the capacitor C1; the input end RL1 of the sampling circuit to be tested is connected with the current sampling resistor R8; one end of the current sampling resistor R8 is connected with the resistor R11 and then is connected with the pin 5 of the operational amplifier U2; the 6 feet and the 7 feet of the operational amplifier U2 are in short circuit; the 6-pin series resistor R10 of the operational amplifier U2 is connected to the 2-pin of the operational amplifier U2; two ends of a pin 2 of the operational amplifier U2 and two ends of a pin 1 of the operational amplifier U2 are connected with a resistor R9 in parallel; the 2-pin series resistor R4 of the operational amplifier U2 is connected to the 6-pin of the operational amplifier U2; the 3-pin series resistor R6 of the operational amplifier U2 is connected with the 5-pin of the operational amplifier U1; the other end of the current sampling resistor R8 is connected to the rear connecting resistor R7 of the emitters of the tubes Q1, Q2, Q3 and Q4 and then is connected to the connection position of the resistor R6 and the operational amplifier U2; the two branches of the driving push-pull circuit after the tubes Q1 and Q3 are connected in series and the tubes Q2 and Q4 are connected in series are connected in parallel; the collectors of the transistors Q1 and Q2 are connected to the positive pole of the power supply; the collectors of the tubes Q3 and Q4 are connected to the negative pole of the power supply.

2. The detection ac/dc source for simple application to a sampling circuit of claim 1, wherein: the 8 pins of the operational amplifier U1 and the operational amplifier U2 are both connected to the positive pole of a power supply, and the 4 pins are both connected to the negative pole of the power supply.

3. The detection ac/dc source for simple application to a sampling circuit as claimed in claim 1, wherein: the power supplies of the operational amplifier U1, the operational amplifier U2 and the driving push-pull circuit are all 15V.

4. The detection ac/dc source for simple application to a sampling circuit as claimed in claim 1, wherein: the types of the tubes Q1 and Q2 are both MJD 122; the tubes Q3, Q4 are both model MJD 127.