Coil turn-to-turn corona tester

Abstract

The present invention provides a coil inter-turn corona tester, comprising a central processing unit, a high-voltage pulse discharge driving circuit, a coil detection switching circuit, a high-frequency signal detection circuit, an analog-to-digital conversion circuit, a bus voltage detection circuit, and a linear power supply circuit. The high-voltage pulse discharge driving circuit is used to perform high-frequency and high-voltage discharge on the coil to be detected to apply a corona voltage; the high-frequency signal detection circuit is used to detect the coil corona triggering voltage and monitor the critical point of the coil insulation breakdown voltage; the coil detection switching circuit is used to switch whether the coil is connected to the test loop; and the bus voltage detection circuit is used to monitor the test voltage applied to the coil. The coil inter-turn corona tester of the present invention applies a corona voltage to the coil by performing high-frequency and high-voltage discharge on the high-voltage pulse discharge driving circuit, and realizes the test of the coil inter-turn corona by coordinating with the signal detection circuit, the analog-to-digital conversion circuit, and the central processing unit. The cost is low, the measurement accuracy is high, and the detection approval of international testing institutions is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of corona resistance testing, and in particular relates to a coil inter-turn corona tester. Background Art

[0002] Corona is generated because uneven conductors produce uneven electric fields. When the voltage rises to a certain value near the electrode with a small radius of curvature around the uneven electric field, discharge will occur due to air ionization, forming corona. The coil turn-to-turn corona tester is used to detect coil turn-to-turn corona. It uses high-voltage pulse discharge to perform withstand voltage insulation tests on the coil products under test, detect coil-to-turn corona, spark discharge linearity, and solve quality problems in the product production process.

[0003] At present, corona testers are still in their infancy in China. Few people have mastered the technology, the cost is high, the product precision is low, and the reliability is poor. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a coil inter-turn corona tester, which has low cost and high measurement accuracy and has been recognized by international testing organizations for product testing.

[0005] To achieve the above object, the technical solution of the present invention is as follows: a coil inter-turn corona tester, characterized in that it includes a central processing unit, a high-voltage pulse discharge drive circuit, a coil detection switching circuit, a high-frequency signal detection circuit, an analog-to-digital conversion circuit, a bus voltage detection circuit, and a linear power supply circuit.

[0006] - the high-voltage pulse discharge driving circuit is connected to the central processing unit and is used to perform high-frequency and high-voltage discharge on the coil to be detected to apply a corona voltage;

[0007] - The high-frequency signal detection circuit is connected to the central processing unit and is used to detect the coil corona triggering voltage and monitor the critical point of the coil insulation breakdown voltage;

[0008] - the coil detection switching circuit is connected to the central processing unit and is used to switch whether the coil is connected to the test loop;

[0009] - the bus voltage detection circuit, which is connected to the central processing unit and is used to monitor the test voltage applied to the coil;

[0010] - the analog-to-digital conversion circuit is connected to the central processing unit and is used to convert the collected analog signal into a digital signal;

[0011] -The linear power supply circuit is connected to the central processing unit, the high-voltage pulse discharge drive circuit, the coil detection switching circuit, the high-frequency signal detection circuit, the analog-to-digital conversion circuit, and the bus voltage detection circuit, and is used to output a linear DC power supply to power each module circuit.

[0012] In a preferred embodiment of the present invention, the high-voltage pulse discharge drive circuit further includes a series high-voltage transistor, a transistor driver chip, and an isolation controller, the isolation controller controls the connected transistor driver chip, the transistor driver chip drives the series-connected high-voltage transistor, the isolation controller controls the transistor driver chip to drive the series-connected high-voltage transistor to output a corona voltage of -5000V to +5000V, and the central processing unit controls the connected isolation controller.

[0013] In a preferred embodiment of the present invention, the high-frequency signal detection circuit further includes a rectifier diode D, a first switch S1, a resistor-capacitor filter, and a high-frequency frequency selector. The rectifier diode D half-wave rectifies the corona voltage, and its cathode is connected to the first switch S1. The first switch S1 is connected to the resistor-capacitor filter. The first switch S1 is also connected in series with the detection coil L and then connected to the high-frequency frequency selector. The output end of the resistor-capacitor filter is connected to a central processing unit for detecting the coil corona triggering voltage, and the output end of the high-frequency frequency selector is connected to a central processing unit for monitoring the critical point of the coil insulation breakdown voltage.

[0014] In a preferred embodiment of the present invention, the coil detection switching circuit further includes a relay J1, a relay J2, a transistor Q1, a transistor Q2, and a photoelectric coupler V. The relay J1, the relay J2 and the detection coil L are connected in series and then connected to a test circuit. The base of the transistor Q1 is connected to a central processing unit, its emitter is grounded, and its collector is connected to the photoelectric coupler V. The output end of the photoelectric coupler V is connected to the base of the transistor Q2, its emitter is grounded, and its collector is connected to the relay J1 and the relay J2. The on-off switching of the relay J1 and the relay J2 detects whether the coil L is connected to the test circuit.

[0015] In a preferred embodiment of the present invention, the bus voltage detection circuit further includes sampling resistors R1, R2, R3, R4, an operational amplifier, and a voltage reference source of model AD680. The central processing unit is connected to the sampling resistor, the sampling resistor samples the high voltage test voltage, and is connected to the operational amplifier, the operational amplifier amplifies the sampled voltage, and the voltage reference source provides a reference voltage for the operational amplifier.

[0016] In a preferred embodiment of the present invention, the linear power supply circuit further comprises a DC linear power supply with an output accuracy of one thousandth.

[0017] In a preferred embodiment of the present invention, the central processing unit is further comprised of a 16-bit single-chip microcomputer.

[0018] In a preferred embodiment of the present invention, it further includes a host computer, and the host computer and the central processing unit communicate based on RS232 half-duplex.

[0019] In a preferred embodiment of the present invention, it further includes a keyboard display I / O circuit.

[0020] The beneficial effects of the present invention are:

[0021] First, the coil inter-turn corona tester of the present invention applies corona voltage to the coil by high-frequency and high-voltage discharge through a high-voltage pulse discharge driving circuit, and realizes the coil inter-turn corona test by coordinating with a signal detection circuit, an analog-to-digital conversion circuit and a central processing unit. It has low cost and high measurement accuracy, and has been recognized by international testing institutions for product testing;

[0022] Second, the high-voltage pulse discharge drive circuit with optimized circuit design and device selection discharges the coil by isolating and controlling the series high-voltage transistor, accurately controls the consistency of transistor conduction, and uses high-frequency absorption to reduce interference signals to ensure the measurement accuracy of the corona tester;

[0023] Third, optimize the high-frequency signal detection circuit of circuit design and device selection, design a resistor-capacitor filter to collect waveform data according to the characteristics of the inter-turn surge waveform generated by the system, and monitor the critical point of the coil insulation breakdown voltage in real time online; design a high-frequency selector to detect the coil corona triggering voltage, which can best ensure the test reliability of coil products;

[0024] Fourth, the coil detection switching circuit with optimized circuit design and device selection, and the automatic switching test realizes the coil testing without blind spots;

[0025] Fifth, the analog-to-digital conversion circuit with optimized circuit design and device selection can achieve a digital signal frequency of 20MHz, which can ensure the sampling data is not distorted to the greatest extent, thereby further improving the precision and accuracy of the detection data. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the technical description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 is a structural block diagram of a preferred embodiment of the present invention;

[0028] Figure 2 is a circuit schematic diagram of a high-frequency signal detection circuit according to a preferred embodiment of the present invention;

[0029] Figure 3 1 is a circuit schematic diagram of a high voltage pulse discharge driving circuit according to a preferred embodiment of the present invention;

[0030] Figure 4 is a circuit schematic diagram of a coil detection switching circuit according to a preferred embodiment of the present invention;

[0031] Figure 5 is a circuit schematic diagram of an analog-to-digital conversion circuit according to a preferred embodiment of the present invention;

[0032] Figure 6 It is a circuit schematic diagram of a bus detection circuit according to a preferred embodiment of the present invention.

[0033] Among them: 10-central processing unit, 20-high-voltage pulse discharge drive circuit, 30-coil detection switching circuit, 40-high-frequency signal detection circuit, 50-analog-to-digital conversion circuit, 60-bus voltage detection circuit, 70-linear power supply circuit, 80-keyboard display I / O circuit. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example

[0036] like Figure 1 As shown, the present embodiment discloses a coil inter-turn corona tester, including a central processing unit 10, a high-voltage pulse discharge drive circuit 20, a coil detection switching circuit 30, a high-frequency signal detection circuit 40, an analog-to-digital conversion circuit 50, a bus voltage detection circuit 60, a linear power supply circuit 70 and a keyboard display I / O circuit 80, and a host computer. The host computer and the central processing unit 10 communicate based on RS232 half-duplex.

[0037] The high-voltage pulse discharge driving circuit 20 is connected to the central processor 10 and is used to perform high-frequency and high-voltage discharge on the coil to be detected to apply a corona voltage;

[0038] The high-frequency signal detection circuit 40 is connected to the central processor 10 and is used to detect the coil corona triggering voltage and monitor the critical point of the coil insulation breakdown voltage;

[0039] The coil detection switching circuit 30 is connected to the central processor 10 and is used to switch whether the coil is connected to the test circuit;

[0040] The bus voltage detection circuit 60 is connected to the central processor 10 and is used to monitor the test voltage applied to the coil;

[0041] The analog-to-digital conversion circuit 50 is connected to the central processing unit 10 and is used to convert the collected analog signal into a digital signal;

[0042] The linear power supply circuit 70 is connected to the central processing unit 10, the high-voltage pulse discharge drive circuit 20, the coil detection switching circuit 30, the high-frequency signal detection circuit 20, the analog-to-digital conversion circuit 50, and the bus voltage detection circuit 60, and is used to output a linear DC power supply to power each module circuit.

[0043] The keyboard display I / O circuit 80 is connected to the central processor 10 and is used to monitor the functional operation of the tester in real time and display real-time test data through a liquid crystal display.

[0044] The specific circuit structure of each circuit module is as follows:

[0045] (1) The central processing unit 10 uses a 16-bit single-chip microcomputer.

[0046] (2) Figure 3 As shown, the high-voltage pulse discharge drive circuit 20 performs high-frequency and high-voltage discharge on the detection coil to apply a corona voltage, and includes a series high-voltage transistor, a transistor driver chip, and an isolation controller. The isolation controller controls the transistor driver chip, and the transistor driver chip drives the series high-voltage transistor. The isolation controller controls the transistor driver chip to drive the series high-voltage transistor to output a corona voltage of -5000V to +5000V, and the central processing unit controls the connection isolation controller. The high-voltage pulse discharge drive circuit is designed to achieve a 5000V pulse high-voltage output. The preferred model of the transistor driver chip is IXDF504. The series high-voltage transistor withstands a voltage of 1700V. Four IGBT tubes are connected in series. The isolation controller uses a photocoupler of model PC817. The front end of the photocoupler is controlled by a constant current source of model LM317. The constant current source is controlled by the central processing unit 10. Figure 3 The resistor R2 and capacitor C1 shown in the figure form the IGBT high-frequency absorption, the resistor R7 forms the discharge resistor of the IGBT tube breaking circuit, the diodes D1 and D2 form the driving voltage clamping diode, and the resistor R6 driving resistor controls the opening rising edge time.

[0047] (3) Figure 2As shown, the high-frequency signal detection circuit 40 includes a rectifier diode D, a first switch S1, a resistor-capacitor filter, and a high-frequency frequency selector. The rectifier diode D half-wave rectifies the corona voltage, and its cathode is connected to the first switch S1, which is connected to the resistor-capacitor filter. The first switch S1 is also connected in series with the detection coil L and then connected to the high-frequency frequency selector. The output end of the resistor-capacitor filter is connected to the central processor for detecting the coil corona triggering voltage, and the output end of the high-frequency frequency selector is connected to the central processor for monitoring the critical point of the coil insulation breakdown voltage. Figure 2 As shown, the resistor R5 and the capacitor C2 form a resistor-capacitor filter, the inductors L1, L2, and the capacitor C5 form a high-frequency selector, the high voltage is half-wave rectified by the rectifier diode D, and the capacitor C4 is charged. The first switch S1 is controlled by the single-chip microcomputer to apply a test voltage to the coil L, and the waveform change on the coil is detected by the resistor R5 and the capacitor C2, and the corona triggering voltage of the coil is detected. The corona signal of the coil under high voltage is detected by the inductors L1, L2, and the capacitor C5, and the critical point of the insulation breakdown voltage of the coil is monitored.

[0048] (4) Figure 4 As shown, the coil detection switching circuit 30 includes a relay J1, a relay J2, a transistor Q1, a transistor Q2, and a photocoupler V. The relay J1, the relay J2, and the detection coil L are connected in series and then connected to the test circuit. The base of the transistor Q1 is connected to the central processing unit, its emitter is grounded, and its collector is connected to the photocoupler V. The output end of the photocoupler V is connected to the base of the transistor Q2, its emitter is grounded, and its collector is connected to the relay J1 and the relay J2. The on-off switching of the relay J1 and the relay J2 detects whether the coil L is connected to the test circuit. The single-chip microcomputer gives a control signal to the front end of the resistor R64, and drives the photocoupler V through the transistor Q1 to control the input end of the relay J1 and the relay J2. The transistor Q2 controls the relay J1 and the relay J2 to turn on K10 and K9 to connect the coil L to the test circuit.

[0049] (5) Figure 6 As shown, the bus voltage detection circuit 60 includes sampling resistors R1, R2, R3, R4, an operational amplifier of model LM324, and a voltage reference source of model AD680. The central processor 10 is connected to the sampling resistor, which samples the high voltage test voltage. The sampling resistor is connected to the operational amplifier, which amplifies the sampled voltage. The voltage reference source provides a reference voltage for the operational amplifier. The DCBUS high voltage is divided by resistors R1, R2, R3, and R4 to obtain a sampled voltage, which is amplified by the operational amplifier and output to the single-chip microcomputer for detection. The reference voltage of the voltage reference source is 2.5V.

[0050] (6) Figure 5As shown, the analog-to-digital conversion circuit 50 includes a conversion chip selected as 74AC14, which converts the collected analog high-frequency signal into a digital signal through the conversion chip 74AC14 and transmits it to the central processor. The digital signal frequency can reach 20MHz, which can maximize the guarantee of non-distortion of the sampled data. In a preferred embodiment of the present invention, it further includes a DC linear power supply with an output accuracy of one thousandth of the linear power supply circuit.

[0051] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A coil turn-to-turn corona tester, Features: Including central processing unit, high voltage pulse discharge drive circuit, coil detection switching circuit, high frequency signal detection circuit, analog-to-digital conversion circuit, bus voltage detection circuit, linear power supply circuit, - the high-voltage pulse discharge driving circuit is connected to the central processing unit and is used to perform high-frequency and high-voltage discharge on the coil to be detected to apply a corona voltage; - The high-frequency signal detection circuit is connected to the central processing unit and is used to detect the coil corona triggering voltage and monitor the critical point of the coil insulation breakdown voltage; - the coil detection switching circuit is connected to the central processing unit and is used to switch whether the coil is connected to the test loop; - the bus voltage detection circuit, which is connected to the central processing unit and is used to monitor the test voltage applied to the coil; - the analog-to-digital conversion circuit is connected to the central processing unit and is used to convert the collected analog signal into a digital signal; -The linear power supply circuit is connected with a central processing unit, a high-voltage pulse discharge drive circuit, a coil detection switching circuit, a high-frequency signal detection circuit, an analog-to-digital conversion circuit, and a bus voltage detection circuit, and is used to output a linear DC power supply to power each module circuit. The high-voltage pulse discharge drive circuit includes a series high-voltage transistor, a transistor driver chip, and an isolation controller. The isolation controller controls the connection of the transistor driver chip. The transistor driver chip drives the series high-voltage transistor. The isolation controller controls the transistor driver chip to drive the series high-voltage transistor to output a corona voltage of -5000V to +5000V. The central processing unit controls the connection of the isolation controller. The high-frequency signal detection circuit includes a rectifier diode (D), a first switch (S1), a resistor-capacitor filter, and a high-frequency frequency selector. The rectifier diode (D) half-wave rectifies the corona voltage, and its cathode is connected to the first switch (S1). The first switch (S1) is connected to the resistor-capacitor filter. The first switch (S1) is also connected in series with the detection coil (L) and then connected to the high-frequency frequency selector. The output end of the resistor-capacitor filter is connected to the central processing unit for detecting the coil corona triggering voltage. The output end of the high-frequency frequency selector is connected to the central processing unit for monitoring the critical point of the coil insulation breakdown voltage.

2. The coil turn-to-turn corona tester according to claim 1, Features: The coil detection switching circuit comprises a relay 1 (J1), a relay 2 (J2), a transistor 1 (Q1), a transistor 2 (Q2), and a photoelectric coupler (V). The relay 1 (J1), the relay 2 (J2) and the detection coil (L) are connected in series and then connected to a test circuit. The base of the transistor 1 (Q1) is connected to a central processing unit, the emitter thereof is grounded, and the collector thereof is connected to the photoelectric coupler (V). The output end of the photoelectric coupler (V) is connected to the base of the transistor 2 (Q2), the emitter thereof is grounded, and the collector thereof is connected to the relay 1 (J1) and the relay 2 (J2). The on-off switching of the relay 1 (J1) and the relay 2 (J2) detects whether the detection coil (L) is connected to the test circuit.

3. The coil turn-to-turn corona tester according to claim 1, Features: The bus voltage detection circuit comprises sampling resistors (R1, R2, R3, R4), an operational amplifier, and a voltage reference source of model AD680. The central processing unit is connected to the sampling resistor, the sampling resistor samples the high voltage test voltage, and is connected to the operational amplifier, the operational amplifier amplifies the sampled voltage, and the voltage reference source provides a reference voltage for the operational amplifier.

4. The coil turn-to-turn corona tester according to claim 1, Features: The linear power supply circuit outputs a direct current linear power supply with an output accuracy of one thousandth.

5. The coil turn-to-turn corona tester according to any one of claims 1 to 4, Features: The central processing unit is a 16-bit single-chip microcomputer.

6. The coil turn-to-turn corona tester according to any one of claims 1 to 4, Features: It also includes a host computer, and the host computer communicates with the central processing unit based on RS232 half-duplex communication.

7. The coil turn-to-turn corona tester according to any one of claims 1 to 4, Features: It also includes keyboard display I / O circuitry.

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