CN203825100U - Transformer transformation ratio tester - Google Patents

Abstract

The utility model discloses a transformer conversion ratio tester, which comprises: a three-phase digital variable frequency power supply: used to transform an AC power supply into a three-phase power supply; a relay: used to control the output of the three-phase digital variable frequency power supply; a signal conditioning circuit: used To adjust the primary and secondary voltage signals of the transformer to be tested and send them to the main control CPU; peripheral interfaces and equipment: including USB interface, RS232 interface, display, input device and printer, used to realize data input, transmission, display and Printing operation; the main control CPU integrates an A/D conversion module, which is used to convert analog signals into digital signals that the main control CPU can recognize; the utility model improves performance while reducing costs and reducing failures The probability of generation avoids the loss caused by frequent maintenance; improves the accuracy of measurement and test speed.

Description

Transformer Ratio Tester

technical field

The utility model relates to a transformer ratio tester.

Background technique

Existing transformer transformation ratio tester tests are often relatively single, group tests and transformation ratio tests are often separated and the test results often only include voltage ratio data. There are two commonly used methods for voltage ratio measurement: double voltmeter method and variable ratio bridge method. Regardless of using the double voltmeter method or the ratio bridge method, the single-phase power supply is used in the measurement experiment, because the single-phase power supply is used to apply voltage to an iron core column, and the voltage and number of turns of the winding on the iron core column are proportional. When using a three-phase power supply, since the three-phase voltage may be asymmetrical, the relationship between the phase voltage and the line voltage may not be equal to √3. Incorrect results may be obtained because the voltage ratio allows very small deviations.

With the long-term use of the current ratio test equipment, experimenters continue to discover new problems and put forward new requirements. At present, it is urgent to give the turn ratio, phase voltage ratio, and single-phase ratio while measuring the voltage ratio (line voltage). The measured voltage ratio of the power supply, the specific angle value when measuring the group by the phase table method, the intermediate results such as the primary and secondary line voltage during the measurement, and other unmeasured data, so that the experimenter can analyze the parameters of the transformer in all aspects .

Utility model content

The purpose of this utility model is to solve the above problems and propose a transformer ratio tester. The device can be measured by the user according to the principle of which measurement method to use, and the tester has a three-phase voltage symmetrical three-phase transformer. Phase inverter digital power supply, accurate measurement results and high measurement efficiency.

In order to achieve the above object, the utility model adopts the following technical solutions:

A transformer ratio tester, a three-phase digital variable frequency power supply, a relay, a main control CPU, a signal conditioning circuit, and peripheral interfaces and equipment;

Three-phase digital variable frequency power supply: used to convert AC power into three-phase power;

Relay: used to control the output of three-phase digital variable frequency power supply;

Signal conditioning circuit: used to condition the primary and secondary voltage signals of the transformer to be tested respectively, and send them to the main control CPU;

Peripheral interface and equipment: including USB interface, RS232 interface, display, input device and printer, used to realize data input, transmission, display and printing operations;

An A/D conversion module is integrated inside the main control CPU for converting analog signals into digital signals recognizable by the main control CPU;

The three-phase digital variable frequency power supply is connected to the relay, the relay is connected to the main control CPU through the signal conditioning circuit, the main control CPU is also connected to the peripheral interface and equipment, and the relay is connected to the transformer to be tested.

The main control CPU includes an ARM Cortex ^TM -M4 core CPU and a 16-bit 8-channel A/D conversion chip A/D7606, and the CPU model is STM32F407.

The three-phase digital variable frequency power supply includes:

The drain of the field effect transistor Q1 is connected to the bus bar, the source is connected to the drain of the field effect transistor Q2, the gate of the field effect transistor Q1 is connected to EPWM1A; the gate of the field effect transistor Q2 is connected to EPWM1B, and the source is grounded;

The drain of the field effect transistor Q3 is connected to the bus bar, the source is connected to the drain of the field effect transistor Q4, the gate of the field effect transistor Q3 is connected to EPWM2A; the gate of the field effect transistor Q4 is connected to EPWM2B, and the source is grounded;

The drain of the field effect transistor Q5 is connected to the bus bar, the source is connected to the drain of the field effect transistor Q6, the gate of the field effect transistor Q5 is connected to EPWM3A; the gate of the field effect transistor Q6 is connected to EPWM3B, and the source is grounded;

The signal conditioning circuit includes:

The negative input terminal of the operational amplifier U1 is connected to the negative input terminal of the transformer signal after being connected in series with the resistor R1 and the resistor R9. Connected in series between the output terminal of the operational amplifier U1 and the inverting input terminal;

The negative input terminal of the operational amplifier U2 is connected in series with the resistor R5 and the resistor R10 to receive the positive input terminal of the transformer signal to be tested. R6 is connected in series between the output terminal of the operational amplifier U2 and the inverting input terminal;

One end of the resistor R4 is connected to the positive input terminal of the operational amplifier U1, and the other end is grounded; one end of the resistor R8 is connected to the positive input terminal of the operational amplifier U2, and the other end is grounded;

The output terminals of operational amplifier U1 and operational amplifier U2 are respectively connected to No. 3 pin and No. 2 pin of operational amplifier U3, and No. 4 pin and No. 8 pin of operational amplifier U3 are respectively connected to -15V and +15V power supply. No. 5 and No. 6 pins of the amplifier U3 are grounded, the operational amplifier U3 is connected to the controller, and the output terminal of the operational amplifier U3 is connected to the A/D conversion module;

One end of the capacitor C1 and the capacitor C2 are respectively connected to the No. 8 pin of the operational amplifier U3, and the other end is grounded;

One end of the capacitor C3 and the capacitor C4 are respectively connected to the No. 4 pin of the operational amplifier U3, and the other end is grounded.

The model of the operational amplifier U3 is A/D8253.

The beneficial effects of the utility model are:

1. This utility model uses a highly integrated dual-core processor chip to replace the original 51 series single-chip microcomputer and its numerous and complicated peripheral equipment. While the performance is improved, the cost is reduced, the probability of failure is also reduced, and the loss caused by frequent maintenance is avoided.

2. The utility model adopts a three-phase digital frequency conversion power supply, so there is no large and heavy original such as a transformer, so that the volume and weight of the overall instrument have been significantly improved; and the output voltage can be adjusted according to needs (10V-160V ), which is more flexible to use.

3. The two differential amplifiers of the signal conditioning circuit of the present utility model are configured to provide a differential output connection, so it can be guaranteed that the signal exists and is processed in the form of a differential mode signal before the signal enters the A/D sampling, Therefore, it has better anti-interference ability, is used to realize precision signal conditioning in applications requiring high performance, can provide excellent common-mode rejection ratio and high bandwidth, can provide excellent gain accuracy, and has very good temperature characteristics. These characteristics can ensure the integrity of the signal when the signal is attenuated at the current stage and the signal is amplified by the programmable gain amplifier of the subsequent stage, thus providing higher measurement accuracy.

4. This utility model abandons the previous method of changing the gain by switching the resistance of the relay, and instead uses A/D8253 to amplify the signal, reducing the signal distortion and gain error caused by the resistance error, and almost no waiting time (relay switching When you need to wait for the signal to stabilize), it can also improve the speed of the test.

Description of drawings

Fig. 1 is a block diagram of the overall structure of the utility model;

Fig. 2 is a circuit diagram of a three-phase digital variable frequency power supply of the present invention;

Fig. 3 is a signal conditioning circuit diagram of the utility model.

Among them, 1. Transformer to be tested, 2. Signal conditioning circuit, 3. Three-phase digital variable frequency power supply, 4. Main control CPU, 6. Display, 7. Input device, 8. USB interface, 9. RS232 interface, 10. Printer , 11. Relay.

Detailed ways:

Below in conjunction with accompanying drawing and embodiment the utility model is described further:

As shown in Figure 1, a kind of transformer transformation ratio tester, comprises: three-phase digital variable frequency power supply 3, relay 11, main control CPU4, A/D conversion module, signal conditioning circuit 2 and peripheral interface and equipment;

Three-phase digital variable frequency power supply 3: used to convert AC power into three-phase power;

Relay 11: used to control the output of the three-phase digital variable frequency power supply;

Signal conditioning circuit 2: used to condition the primary and secondary voltage signals of the transformer to be tested respectively, and send them to the AD conversion chip AD7606 of the main control CPU;

Peripheral interface and equipment: including USB interface 8, RS232 interface 9, display 6, input device 7 and printer 10, used to realize data input, transmission, display and printing operations;

The main control CPU4 integrates an A/D conversion module, which is used to convert the analog signal into a digital signal that the main control CPU4 can recognize;

The three-phase digital variable frequency power supply 3 is connected to the relay 11, the relay is connected to the main control CPU 4 through the signal conditioning circuit 2, the main control CPU 4 is also connected to the peripheral interface and equipment, and the relay 11 is connected to the transformer 1 to be tested.

The control part of the relay 11 adds the output of the three-phase digital variable frequency power supply 3 to the transformer 1 to be tested as required, and short-circuits the corresponding terminals of the transformer if it needs to be shorted, and the signal conditioning circuit 2 separates the primary and secondary voltage signals of the transformer 1 to be tested. Conditioning is carried out and sent to the A/D conversion module.

As shown in Figure 2, the three-phase digital variable frequency power supply 3 adopts SPWM inverter technology to directly convert the 220V AC power supply into a three-phase power supply, while the three-phase power supply in the previous three-phase ratio tester is all amplified by power The method generates a low-voltage three-phase power supply of about 10V and then boosts it through a transformer to obtain a high voltage.

As shown in Figure 3, the signal conditioning circuit 2 includes:

The negative input terminal of the operational amplifier U1 is connected to the negative input terminal of the transformer signal after being connected in series with the resistor R1 and the resistor R9. Connected in series between the output terminal of the operational amplifier U1 and the inverting input terminal;

The negative input terminal of the operational amplifier U2 is connected in series with the resistor R5 and the resistor R10 to receive the positive input terminal of the transformer signal to be tested. R6 is connected in series between the output terminal of the operational amplifier U2 and the inverting input terminal;

One end of the resistor R4 is connected to the positive input terminal of the operational amplifier U1, and the other end is grounded; one end of the resistor R8 is connected to the positive input terminal of the operational amplifier U2, and the other end is grounded;

The output terminals of operational amplifier U1 and operational amplifier U2 are respectively connected to No. 3 pin and No. 2 pin of operational amplifier U3, and No. 4 pin and No. 8 pin of operational amplifier U3 are respectively connected to -15V and +15V power supply. No. 5 and No. 6 pins of the amplifier U3 are grounded, the operational amplifier U3 is connected to the controller, and the output terminal of the operational amplifier U3 is connected to the A/D conversion module;

One end of the capacitor C1 and the capacitor C2 are respectively connected to the No. 8 pin of the operational amplifier U3, and the other end is grounded;

One end of the capacitor C3 and the capacitor C4 are respectively connected to the No. 4 pin of the operational amplifier U3, and the other end is grounded.

The model of the operational amplifier U3 is A/D8253.

Although the specific implementation of the utility model has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the utility model. Those skilled in the art should understand that on the basis of the technical solution of the utility model, those skilled in the art do not need to Various modifications or deformations that can be made with creative efforts are still within the protection scope of the present utility model.

Claims (5)

1. a transformer voltage ratio tester, is characterized in that, comprising: three-phase digital variable-frequency power sources, relay, master cpu, signal conditioning circuit and peripheral interface and equipment;

Three-phase digital variable-frequency power sources: for AC power is transformed into three-phase supply;

Relay: for controlling the output of three-phase digital variable-frequency power sources;

Signal conditioning circuit: for transformer primary and secondary voltage signal to be measured is nursed one's health respectively, and deliver to master cpu;

Peripheral interface and equipment: comprise USB interface, RS232 interface, display, input equipment and printer, for realizing input, transmission, demonstration and the printing of data;

The inner integrated A/D modular converter of described master cpu, for changing into simulating signal the digital signal that master cpu can be identified;

Three-phase digital variable-frequency power sources is connected with relay, and relay is connected with master cpu through signal conditioning circuit, master cpu also with peripheral interface and equipment connection, relay is connected with transformer to be measured.

2. a kind of transformer voltage ratio tester as claimed in claim 1, is characterized in that, described master cpu comprises ARMCortex ^tM-M4 kernel CPU and 16 8 passage A/D conversion chip A/D7606, described CPU model is STM32F407.

3. a kind of transformer voltage ratio tester as claimed in claim 1, is characterized in that, described three-phase digital variable-frequency power sources comprises:

The drain electrode of field effect transistor Q1 is connected on bus, source electrode is connected with the drain electrode of field effect transistor Q2, and the grid of field effect transistor Q1 connects SPWM modulation signal EPWM1A; The grid of field effect transistor Q2 connects SPWM modulation signal EPWM1B, source ground;

The drain electrode of field effect transistor Q3 is connected on bus, source electrode is connected with the drain electrode of field effect transistor Q4, and the grid of field effect transistor Q3 connects SPWM modulation signal EPWM2A; The grid of field effect transistor Q4 connects SPWM modulation signal EPWM2B, source ground;

The drain electrode of field effect transistor Q5 is connected on bus, source electrode is connected with the drain electrode of field effect transistor Q6, and the grid of field effect transistor Q5 connects SPWM modulation signal EPWM3A; The grid of field effect transistor Q6 connects SPWM modulation signal EPWM3B, source ground.

4. a kind of transformer voltage ratio tester as claimed in claim 1, is characterized in that, described signal conditioning circuit comprises:

Transformer signal negative input is surveyed in the reception after resistance R 1, resistance R 9 series connection of the reverse input end of operational amplifier U1, transformer signal electrode input end is surveyed in the reception after resistance R 3, resistance R 10 series connection of the positive input of operational amplifier U1, and resistance R 2 is serially connected between the output terminal and reverse input end of operational amplifier U1;

Transformer signal electrode input end is surveyed in the reception after resistance R 5, resistance R 10 series connection of the reverse input end of operational amplifier U2, transformer signal negative pole utmost point input end is surveyed in the reception after resistance R 7, resistance R 9 series connection of the positive input of operational amplifier U2, and resistance R 6 is serially connected between the output terminal and reverse input end of operational amplifier U2;

Positive input, the other end ground connection of resistance R 4 one termination operational amplifier U1; Positive input, the other end ground connection of resistance R 8 one termination operational amplifier U2;

The output terminal of operational amplifier U1 and operational amplifier U2 accesses respectively No. 3 pins and No. 2 pins of operational amplifier U3, No. 4 pins of operational amplifier U3 and No. 8 connect respectively-15V of pin and+15V power supply, No. 5 of operational amplifier U3, No. 6 pin ground connection, operational amplifier U3 connects controller, the output termination A/D modular converter of operational amplifier U3;

One end of capacitor C 1 and capacitor C 2 connects respectively No. 8 pins, the other end ground connection of operational amplifier U3;

One end of capacitor C 3 and capacitor C 4 connects respectively No. 4 pins, the other end ground connection of operational amplifier U3.

5. a kind of transformer voltage ratio tester as claimed in claim 4, is characterized in that, the model of described operational amplifier U3 is A/D8253.