Signal generating device for verifying harmonic test system in electromagnetic compatibility field

Abstract

The utility model relates to the field of electromagnetic compatibility harmonic testing, in particular to a signal generating device for verifying a harmonic testing system in the field of electromagnetic compatibility, which comprises a voltage sampling circuit, a reference voltage amplifying circuit, a comparison circuit, a pulse width control circuit and a voltage comparison and feedback control circuit. Compared with the prior art, the utility model has the advantages that the high-voltage source can be continuously adjusted from 100V to 5000V, and the input / output and control quantity full-isolation scheme is adopted to ensure that the high voltage does not have crosstalk; the efficiency of the power supply can reach more than 90% by adopting the push-pull topology, and the power supply can work and be controlled only by providing 24V / 3A direct current power supply and a path of 0-5V analog signals.

Description

Technical Field

[0001] The utility model relates to the field of electromagnetic compatibility harmonic testing, in particular to a signal generating device for calibrating a harmonic testing system in the electromagnetic compatibility field. Background Art

[0002] EMC harmonic test systems are widely used in the fields of power, communication, transportation, medical treatment, etc. to perform harmonic tests on various electronic equipment to ensure the normal operation of the equipment in the electromagnetic environment. For example, in the power system, harmonic tests are performed on generators, transformers, power capacitors and other equipment to evaluate their impact on the power grid; in the communication system, harmonic tests are performed on communication equipment to ensure its normal operation in a complex electromagnetic environment.

[0003] With the continuous development of power electronics technology, the complexity and diversity of electronic equipment are increasing, and the requirements for EMC harmonic test systems are becoming higher and higher. In the future, EMC harmonic test systems will continue to develop in the direction of high precision, wide bandwidth, high automation, and intelligence, while strengthening test support for new energy, smart grids and other fields, providing strong guarantees for the safe and stable operation of power systems.

[0004] However, there is no device in the prior art that provides a stable and adjustable harmonic signal output for conventional calibration of EMC harmonic test systems. There is an urgent need to design a signal generating device for calibrating harmonic test systems in the field of electromagnetic compatibility. Utility Model Content

[0005] The purpose of the utility model is to overcome the shortcomings of the prior art and provide a signal generating device for calibrating a harmonic test system in the field of electromagnetic compatibility, so as to solve the current situation in the EMC field where a stable and fixed harmonic signal cannot be provided to calibrate the harmonic test system.

[0006] In order to achieve the above-mentioned purpose, a signal generating device for harmonic test system calibration in the field of electromagnetic compatibility is designed, including: a voltage sampling circuit, the voltage sampling circuit includes: voltage-dividing resistors R1 and R2 connected in series, one end of which is connected to the high voltage input end, and the other end is connected to the ground point, a filter capacitor C1, one end of which is connected to the midpoint of the voltage-dividing resistors R1 and R2, and the other end is grounded, an adjustment potentiometer RP1, one end of which is connected to the midpoint of the voltage-dividing resistors R1 and R2, and the other end is connected to the input end of an operational amplifier U2, and the output end of the operational amplifier U2 is connected to a downstream control circuit to provide an amplified voltage signal; a reference voltage amplifying circuit, the reference voltage amplifying circuit includes: a resistor network R16, R17, R18, R20, R21 and a potentiometer RP2, forming a feedback loop; an operational amplifier U4, the non-inverting input end of which is connected to a reference voltage source, the inverting input end of which is connected to the feedback loop, and the output end of which is connected to one end of the feedback loop; Filter capacitors C7 and C8 are connected to the input and output of the operational amplifier U4 to the ground point respectively; a comparison circuit, the comparison circuit includes: a comparison operational amplifier U7, whose non-inverting input end is connected to the output of the voltage sampling circuit, and whose inverting input end is connected to the output of the reference voltage amplifier circuit; an adjustment potentiometer RP3 and a resistor R27, which are used to adjust the input signal of the comparison circuit; filter capacitors C15 and C17, which are connected to the input and output ends of the comparison operational amplifier U7 respectively; a pulse width control circuit, the pulse width control circuit includes a pulse width modulation chip SG1525, whose control end is connected to the output of the comparison circuit; resistors R22, R23, R24 and capacitors C11 and C12 for setting the frequency and duty cycle; the output end of the pulse width modulation chip is connected to the power converter to output a pulse width modulation signal; a voltage comparison and feedback control circuit, the voltage comparison and feedback control circuit includes: a voltage comparison operational amplifier U7, whose input end is connected to the voltage sampling circuit and the reference voltage amplifier circuit respectively, and whose output end is connected to the control input end of the pulse width modulation chip SG1525, which is used to adjust the pulse width modulation signal to achieve closed-loop control.

[0007] Preferably, the utility model further comprises a power supply circuit, the power supply circuit comprising

[0008] A linear regulator U8, whose input terminal is connected to a +24V DC power supply, and whose output terminal provides a +15V regulated power supply; an input capacitor C19, which is connected between the input terminal of the linear regulator and the ground; an output capacitor C20, which is connected between the output terminal of the linear regulator and the ground; a diode D9, whose anode is connected to a +24V DC power supply, and whose cathode is connected to the input terminal of the linear regulator, is used to prevent reverse voltage.

[0009] Compared with the prior art, the utility model has the following advantages:

[0010] 1. It can provide the required harmonic intensity and phase, and provide customized signals for the calibration of the harmonic test system.

[0011] 2. The duration of the harmonic signal can be adjusted as needed, which is conducive to the accurate acquisition of the harmonic test system verification data.

[0012] 3. The high voltage source can be continuously adjusted from 100V to 5000V, and the input, output and control quantity are fully isolated to ensure that the high voltage does not crosstalk. The power supply adopts a push-pull topology with an efficiency of more than 90%. It only needs to provide a 24V / 3A DC power supply and a 0~5V analog signal to work and control. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the partition circuit diagram of the utility model;

[0014] Figure 2 This is the complete wiring diagram of the utility model;

[0015] Figure 3 This is the principle block diagram of the utility model system;

[0016] In the figure: 1 voltage sampling circuit; 2 reference voltage amplifier circuit; 3 comparison circuit; 4 pulse width control circuit; 5 voltage comparison and feedback control circuit. DETAILED DESCRIPTION

[0017] The utility model is further described below in conjunction with a specific embodiment. The utility model provides a signal generating device for calibrating a harmonic test system in the field of electromagnetic compatibility. Figure 1 , 2 include:

[0018] Voltage sampling circuit 1: The main function of this circuit is to sample the voltage of the input high-voltage power supply and amplify the sampled voltage. Specifically, it includes: voltage divider resistors: R1 and R2 are 1kΩ resistors respectively, one end of R1 is connected to the high-voltage input terminal, one end of R2 is connected to the ground point, and the other end of R1 is connected to the other end of R2 to form a voltage divider circuit. Filter capacitor: C1 is a 0.1µF capacitor, one end of which is connected to the connection point of the voltage divider resistors R1 and R2, and the other end is grounded, which is used to filter out high-frequency noise. Adjustment potentiometer: RP1 is an adjustable potentiometer (R_3388P_US), one end of which is connected to the connection point of the voltage divider resistors R1 and R2, and the other end is connected to the input end of the operational amplifier U2, which is used to fine-tune the voltage signal. Operational amplifier: U2 uses LM358, its pin 6 is connected to the midpoint of RP1, pin 5 is connected to the ground, and pin 7 is the output end, which is connected to the downstream control circuit to provide an amplified voltage signal.

[0019] Reference voltage amplifier circuit 2: The main function of this circuit is to amplify the reference voltage so as to compare it with the sampled voltage. Specifically, it includes: Resistor network: R16, R17, R18, R20, and R21 are 1kΩ resistors respectively, and RP2 is an adjustable potentiometer (R_3388P_US), forming a feedback network to set the gain of the operational amplifier. R16 is connected to the reference voltage source, and the other end of R16 is connected to the non-inverting input terminal (pin 5) of the operational amplifier U4. One end of R17 is connected to the inverting input terminal (pin 4) of U4, and the other end is connected to the midpoint of R18 and RP2. R20 is connected between the output terminal (pin 7) and the inverting input terminal (pin 4) of U4, and R21 is connected between the midpoint of RP2 and ground. Operational amplifier: U4 uses LM358, whose pin 5 is connected to R16 as the non-inverting input, pin 4 is connected to R17 and the feedback loop, and the output terminal (pin 7) is connected to R20 and the feedback network. Filter capacitors: C7 and C8 are 0.1µF capacitors connected from the input and output of operational amplifier U4 to ground, respectively, to filter out high-frequency noise in the circuit.

[0020] Comparison circuit 3: The main function of this circuit is to compare the sampled voltage with the reference voltage and generate a control signal, including: Comparison operational amplifier: U7 uses LM358, whose non-inverting input (pin 3) is connected to the output of the voltage sampling circuit, and its inverting input (pin 2) is connected to the output of the reference voltage amplifier circuit. Adjustment potentiometer and resistor: RP3 is an adjustable potentiometer (R_3388P_US), and R27 is a 1kΩ resistor, which are used to adjust the input signal of the comparison circuit. R27 is connected between the non-inverting input of U7 and RP3, one end of RP3 is connected to the sampled voltage signal, and the other end is connected to the reference voltage signal. Filter capacitor: C15 and C17 are 0.1µF capacitors, which are connected to the input and output of the comparison operational amplifier U7, respectively, to filter out high-frequency noise in the signal.

[0021] Pulse width control circuit 4: The main function of this circuit is to generate a pulse width modulation signal for driving a high voltage conversion circuit, specifically including: Pulse width modulation chip: U8 uses SG1525, whose control terminal is connected to the output of the comparison circuit to generate a pulse width modulation signal. Pin 16 (VCC) is connected to the power supply to provide the operating voltage; Pin 7 (GND) is connected to the ground; Pin 1 (OSC) and Pin 2 (CT) are connected to the resistor and capacitor for setting the frequency and duty cycle. Resistors and capacitors for setting the frequency and duty cycle: R22, R23, and R24 are 1kΩ resistors, respectively, and C11 and C12 are 1µF capacitors, respectively, for adjusting the frequency and duty cycle of the pulse width modulation signal. R22 is connected between pin 1 and pin 2 of SG1525, C11 is connected between pin 2 and the ground point, and R23 and C12 are connected in parallel between pin 3 and the ground point. Pulse width modulation output: The output end (pin 11 and pin 14) of U8 is connected to the power converter to output a pulse width modulation signal.

[0022] Voltage comparison and feedback control circuit 5: The main function of this circuit is to compare the sampled voltage and the reference voltage, generate a feedback control signal, adjust the pulse width modulation signal, and realize closed-loop control, including: Voltage comparison operational amplifier: U7 uses LM358, its non-inverting input (pin 3) is connected to the output of the voltage sampling circuit, and its inverting input (pin 2) is connected to the output of the reference voltage amplifier circuit. Output feedback control signal: The output end (pin 1) of U7 is connected to the control input end of the pulse width modulation chip SG1525 to provide a feedback control signal. By adjusting the duty cycle and frequency of the pulse width modulation signal, the stability and accuracy of the output voltage are ensured.

[0023] See also Figure 3 The technical solution of this utility model is as follows: 24V DC is input to the high-frequency transformer through an inverter, and the positive and negative voltage doubler rectifier circuits are selected through the polarity switching circuit to output high voltage. This power supply belongs to the pulse width modulation type high-voltage power supply. The high-voltage output is obtained by the sampling circuit to obtain the sampling voltage and the given signal voltage. After comparison by the comparison circuit, the input pulse width modulation circuit controls the oscillation duty cycle to achieve the purpose of linear adjustable high-voltage output.

[0024] The high-voltage power supply described in the utility model belongs to the pulse width modulation type high-voltage power supply. The main high-voltage output of the control part is compared by the sampling circuit and the sampling voltage and the given signal voltage. After comparison by the comparison circuit, the input is input into the pulse width modulation circuit to control the MOS tube switch oscillation duty cycle, control the high-frequency transformer output voltage, form a voltage closed loop, and achieve the purpose of linear adjustable high-voltage output. Both positive and negative high voltages can be adjusted by adjusting the potentiometer.

[0025] The above is only a specific implementation method of this utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field within the technical scope disclosed by the utility model, according to the technical solution and new concept of the utility model, shall be covered by the protection scope of the utility model.

Claims

1. A signal generating device for harmonic test system calibration in the field of electromagnetic compatibility, characterized in that include A voltage sampling circuit, the voltage sampling circuit comprising The voltage-dividing resistors R1 and R2 are connected in series, one end of which is connected to the high voltage input terminal, and the other end is connected to the ground point. The filter capacitor C1 has one end connected to the midpoint of the voltage divider resistors R1 and R2, and the other end is grounded. Adjust the potentiometer RP1, one end of which is connected to the midpoint of the voltage-dividing resistors R1 and R2, and the other end is connected to the input of the operational amplifier U2. Operational amplifier U2, whose output is connected to a downstream control circuit to provide an amplified voltage signal; A reference voltage amplifier circuit, the reference voltage amplifier circuit comprising The resistor network R16, R17, R18, R20, R21 and the potentiometer RP2 form a feedback loop; the operational amplifier U4 has its non-inverting input terminal connected to the reference voltage source, its inverting input terminal connected to the feedback loop, and its output terminal connected to one end of the feedback loop; the filter capacitors C7 and C8 are connected to the input and output terminals of the operational amplifier U4 to the ground point respectively; A comparison circuit, the comparison circuit comprising A comparison operational amplifier U7, whose non-inverting input terminal is connected to the output of the voltage sampling circuit, and whose inverting input terminal is connected to the output of the reference voltage amplifier circuit; an adjustment potentiometer RP3 and a resistor R27, used to adjust the input signal of the comparison circuit; filter capacitors C15 and C17, respectively connected to the input and output terminals of the comparison operational amplifier U7; A pulse width control circuit, the pulse width control circuit comprising The pulse width modulation chip SG1525, whose control terminal is connected to the output of the comparison circuit; the resistors R22, R23, R24 and the capacitors C11, C12 for setting the frequency and duty cycle; the output terminal of the pulse width modulation chip is connected to the power converter to output the pulse width modulation signal; A voltage comparison and feedback control circuit, the voltage comparison and feedback control circuit comprising The voltage comparison operational amplifier U7 has its input terminals connected to the voltage sampling circuit and the reference voltage amplifier circuit respectively. The output end is connected to the control input end of the pulse width modulation chip SG1525 to adjust the pulse width modulation signal and realize closed-loop control.

2. A signal generating device for harmonic test system calibration in the field of electromagnetic compatibility as claimed in claim 1, characterized in that Also included is a power supply circuit, the power supply circuit comprising A linear regulator U8, whose input terminal is connected to a +24V DC power supply, and whose output terminal provides a +15V regulated power supply; an input capacitor C19, which is connected between the input terminal of the linear regulator and the ground; an output capacitor C20, which is connected between the output terminal of the linear regulator and the ground; a diode D9, whose anode is connected to a +24V DC power supply, and whose cathode is connected to the input terminal of the linear regulator, is used to prevent reverse voltage.

Images