CN103812354A - Broadband strong current generator power supply - Google Patents

Abstract

The invention relates to a power supply for a broadband current booster, which includes a rectification filter module, an inverter filter module, a single-chip microcomputer for core control, a D/A conversion module, and a pulse width modulation voltage stabilization circuit module for modulating broadband large current output , Feedback connection between the single-chip microcomputer and the input terminal of the current booster for collecting the voltage sampling circuit of the input voltage of the current booster, feedback connection between the single-chip microcomputer and the output terminal of the current booster for collecting the current sampling circuit of the output current of the current booster , the output terminal of the pulse width modulation voltage stabilizing circuit module is electrically connected to the input terminal of the inverter filter module. The invention adopts a single-chip microcomputer, based on pulse width modulation voltage stabilization control, on the one hand, adjusts the output current of the current booster to achieve the effect of boosting the current, and on the other hand, feedbacks the input voltage of the current booster and the output current of the current booster to realize The purpose of steady current is that it has higher working efficiency than traditional current booster, stable output current, high measurement accuracy, wide frequency range and good repeatability.

Description

A kind of wide frequency booster power supply

technical field

The invention relates to the field of automatic control and high-voltage testing equipment, in particular to a wide-band current booster power supply.

Background technique

Electromagnetic current transformer is the key equipment in the power system. It has been running in the power grid for many years. The harmonics of the power supply are very harmful to the electromagnetic current transformer. The harmonic current will increase the copper consumption of the current transformer and accelerate its aging or damage. , will seriously affect the normal operation of the equipment, and even cause a very dangerous explosion. If currents of different frequencies can be applied to electromagnetic current transformers, the error characteristics of current transformers at different frequencies can be analyzed, and the harm of harmonics to current transformers can be analyzed and prevented, then more serious consequences can be avoided.

The current booster is also called a large current generator. In the power system, technicians often use the current booster to test the current transformer, that is, connect the current booster to the working power supply, and adjust the output voltage of the voltage regulator to obtain the required voltage for the test. High Current. Due to technical limitations, the output current of the current booster is often not stable enough, and the output frequency range is narrow, which often fails to achieve good inspection results.

Contents of the invention

The object of the present invention is to provide a current booster power supply that can provide a wide-band input signal and can regulate and stabilize the output current of the current booster in order to overcome the shortcomings of the prior art.

In order to achieve the above object, the technical solution adopted by the present invention is: a wide-band current booster power supply, which includes a rectification and filtering module for converting an AC voltage input signal into a DC voltage output, and the output terminal of the rectification and filtering module Phase electrical connection is used to convert the DC voltage signal into the inverter filter module of the set frequency AC signal, the output terminal of the inverter filter module is electrically connected to the current booster, and the current booster is connected to the current to be measured The mutual inductor is electrically connected, and it also includes a single-chip microcomputer for core control, a D/A conversion module electrically connected with the output end of the single-chip microcomputer, and an electrical connection with the output end of the D/A conversion module for modulation A pulse width modulation voltage stabilizing circuit module with wide frequency and large current output, a voltage sampling circuit for collecting the input voltage of the current booster, and a feedback connection between the single chip microcomputer and the input terminal of the current booster, and a feedback connection between the single chip microcomputer and the booster A current sampling circuit for collecting the output current of the current booster between the output terminals of the current converter, and the output terminal of the pulse width modulation voltage stabilizing circuit module is electrically connected with the input terminal of the inverter filter module.

Optimally, the pulse width modulation voltage stabilizing circuit module is SPWM modulation, which is mainly composed of a triangular wave generating circuit, a sine modulating wave generating circuit and a comparator.

Optimally, the D/A conversion module includes a DDS circuit and a D/A circuit for jointly adjusting and controlling the output waveform pulse width and frequency of the pulse width modulation voltage stabilizing circuit module.

Optimally, the inverter filter module is an IGBT driven inverter filter module.

Optimally, it also includes a liquid crystal display for voltage and current display.

Optimally, the single-chip microcomputer realizes the control of the upflow and steady flow of the upflow device based on the PID algorithm.

Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: the present invention adopts a single-chip microcomputer, and based on pulse width modulation voltage stabilization control, on the one hand, adjusts the output current of the current booster to achieve the effect of current boosting; on the other hand, the current booster The input voltage feedback and the current booster output current feedback achieve the purpose of steady flow. Compared with the traditional current booster, it has higher working efficiency, stable output current, high measurement accuracy, wide frequency range and good repeatability. The current boosting power supply of the present invention can directly output sine wave voltage of 30Hz-2500Hz, 0-150V, and can be used in other test occasions requiring variable-frequency voltage-regulating power supply in addition to being used for harmonic test tests of current transformers.

Description of drawings

Accompanying drawing 1 is the functional block diagram of the power supply of the current booster of the present invention;

Accompanying drawing 2 is the principle block diagram of pulse width modulation voltage stabilizing circuit module;

Accompanying drawing 3 is based on PID algorithm ascending flow, steady flow flow chart;

Among them: 1. Rectifier filter module; 2. Inverter filter module; 3. Current booster; 4. Tested sample; 5. Single chip microcomputer; 6. D/A conversion module; 7. Pulse width modulation regulator circuit module; 8 , Voltage sampling circuit; 9, Current sampling circuit; 10, Display.

Detailed ways

The technical scheme of the present invention will be described in detail below in conjunction with specific embodiments:

The current booster power supply shown in Figure 1 includes a rectification filter module 1, an inverter filter module 2, a single chip microcomputer 5, a D/A conversion module 6, a pulse width modulation voltage stabilization circuit module 7, a voltage sampling circuit 8, a current sampling Circuit 9, wherein the input end of the rectification filter module 1 is connected to the AC alternating current, its output end is electrically connected to the inverter filter module 2, and the output end of the inverter filter module 2 is connected to the current booster 3, when it is necessary to The test sample 4 is the current transformer, and the inspector connects the output terminal of the current booster 3 with the test sample 4 . The single-chip microcomputer 5, the D/A conversion module 6, and the output terminals of the pulse width modulation voltage stabilizing circuit module 7 are electrically connected in sequence, and the output terminals of the pulse width modulation voltage stabilizing circuit module 7 are connected with the input terminals of the inverter filter module 2, so that the single chip microcomputer 5. The D/A conversion module 6, the pulse width modulation voltage stabilizing circuit module 7, the inverter filtering module 2, the current booster 3 and the tested sample 4 form a main control circuit. The voltage sampling circuit 8 is feedback-connected between the single-chip microcomputer 5 and the input terminal of the current booster 3 , and the current sampling circuit 9 is feedback-connected between the single-chip microcomputer 5 and the output terminal of the current booster 3 .

In this embodiment, the inverter filter module 2 is driven by an IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor), and the pulse width modulation voltage stabilizing circuit module 7 uses SPWM modulation technology. The specific working principle is:

The AC voltage signal is converted into a DC signal after the rectification and filtering module 1, and output to the IGBT pulse width adjustment inverter filtering module 2, and the single-chip microcomputer 5 outputs the digital control signal to the D/A conversion module 6 according to the setting requirements, and the D/A The analog control signal converted by the conversion module 6 enters the SPWM pulse width modulation voltage stabilizing circuit module 7, and the pulse width modulation circuit generates a SPWM wave whose frequency can be changed, and the frequency range is 30 Hz to 2500 Hz, and outputs it to the IGBT pulse width adjustment inverter filter module 2. The signal is driven by IGBT, and then output to the current booster 3 through bridge inverter, isolation transformer and filter. The current booster 3 can output a wide current to detect the current transformer under test. During the operation of the current booster power supply, the single-chip microcomputer 5 will also perform the steady current control of the current booster according to the current booster input voltage feedback signal output by the voltage sampling circuit 8 and the current booster output current feedback signal output by the current sampling circuit 9 . The specific control principle is as follows:

First, the control of broadband output is realized based on SPWM pulse width modulation. As shown in Figure 2, it uses an analog circuit to form a triangular wave carrier circuit and a sine modulating wave generating circuit, uses a comparator to determine their intersection point, and converts the output high and low levels at the intersection point to generate a SPWM wave. DDS (direct digital frequency synthesizer) circuit and D/A control circuit adjust the frequency and amplitude of the sine wave, and adjust the pulse width and frequency of the SPWM wave. The SPWM synthesis part is to compare the sine wave with the triangular wave. The part of the sine wave larger than the triangular wave will output a positive pulse, and the smaller part will output a negative pulse. The synthesized SPWM wave enters the IGBT drive.

For the control of upflow and steady flow, this embodiment adopts PID algorithm. Fig. 3 is the flow chart of realizing ascending flow and steady flow with PID algorithm. The final stable current I _o output by the current booster depends on the DC voltage output by the D/A, and the voltage is determined by the input of a 16-bit binary number X to the D/A circuit by the microcontroller. Theoretically speaking, after the hardware parameters of the system are established, the corresponding D/A input X should also be determined for each set high voltage I _o .

In the stage of rising flow and steady flow of PID algorithm, the value of ΔX is calculated by PID algorithm every increment.

If the system sets the output current value as I _os ; the sampling value of the output current during the actual control process is I _oi ; the sampling values of the first two output currents are: I _oi-1 and I _oi-2 respectively. Then the difference can be calculated as:

ei=I _os -I _oi ;

Δei=ei-ei-1=I _oi-1 -I _oi ;

Δ2ei=Δei-Δei-1=2I _oi-1 -I _oi -I _oi-2 .

It can be calculated by the PID algorithm:

ΔX _i +1=ΔX _i +K(Δei+I _ei +DΔ2ei).

Among them, ΔX _i +1 is the data increment to be input to D/A, and ΔX _i is the data increment of the previous input D/A. In the above expression, K, I, and D are proportional coefficients, integral coefficients, and differential coefficients, respectively, and their values are adjusted according to actual system conditions.

Entering the step-up phase of the PID algorithm, the initial value of ΔX _i in the above formula is ΔX _o in the previous stage. As the voltage increases, the incremental value ΔX _i+1 becomes smaller and smaller, and the value is 0 after the boost is stable. In the PID control process, the time interval of each incremental input of D/A data X is also a very important parameter. The size of this time interval depends on three factors: the delay time from D/A data input to stable high-voltage output, The value of the boost time set by the system hardware parameters and software should be adjusted according to the actual system conditions.

Figure 3 is the program block diagram of boosting and steady flow. At the beginning of the program, parameters are calculated and assigned to corresponding registers. These parameters are used in the boosting process, such as ΔX _o , PID coefficients K, P, I, D, etc. Input ΔX _o to D/A when starting to upflow. In hardware design, the register in D/A chip is designed as the unit of off-chip data memory of single-chip microcomputer, so as long as the instruction of accessing off-chip data memory is executed, D/A A chip transmits data. Use PID algorithm to calculate ΔX _i+1 each time, and then input it into D/A, and output corresponding current until the output current reaches the set current. After reaching the set value of the current, the calculation of ΔX _i+1 is still repeated to stabilize the output current at the set value.

To sum up, the power supply of the current booster of the present invention adopts SPWM pulse width stabilizing control, on the one hand to adjust the output current of the current booster, on the other hand, through the input voltage feedback of the current booster and the output current feedback control of the current Compared with the traditional current booster, it has higher working efficiency, more stable output current, higher measurement accuracy and wider frequency range. The power supply instrument made by adopting the technical scheme of the invention can also add manual test and automatic test functions, and one machine has multiple functions. Moreover, it can adopt the control interface of the display 10, an external micro-printer, etc., to facilitate on-site detection and use.

The current booster power supply of the present invention can directly output 30Hz-2500Hz, 0-150V sine wave voltage, so in addition to being used for the harmonic test of the current transformer (CT), it can also be used for other frequency conversion and voltage regulation power supplies used in test cases.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (6)

1. A wide-band current booster power supply, which includes a rectification and filtering module for converting an AC voltage input signal into a DC voltage output, and is electrically connected with the output terminal of the rectification and filtering module for converting the DC voltage signal into An inverter filter module for setting the frequency of the AC signal, the output terminal of the inverter filter module is electrically connected to the current booster, and the current booster is electrically connected to the current transformer to be measured, characterized in that: it It also includes a single-chip microcomputer for core control, a D/A conversion module electrically connected to the output end of the single-chip microcomputer, and an electrical connection with the output end of the D/A conversion module for modulating the pulse width of the broadband high-current output A modulating voltage stabilizing circuit module, a voltage sampling circuit for collecting the input voltage of the current booster, and a feedback connection between the single-chip microcomputer and the input terminal of the current booster, and a feedback connection between the single-chip microcomputer and the output terminal of the current booster In the current sampling circuit for collecting the output current of the current booster, the output terminal of the pulse width modulation voltage stabilizing circuit module is electrically connected with the input terminal of the inverter filter module. 2. A kind of wide-band current booster power supply according to claim 1, characterized in that: said pulse width modulation regulator circuit module is SPWM modulation, which is mainly composed of a triangular wave generating circuit, a sine modulating wave generating circuit and a comparator composition. 3. A power supply for a wide-band current booster according to claim 1 or 2, characterized in that: the D/A conversion module includes an output waveform pulse width and Frequency DDS circuit and D/A circuit. 4. A power supply for a broadband current booster according to claim 1, wherein the inverter filter module is an IGBT driven inverter filter module. 5. A wide-band current booster power supply according to claim 1, characterized in that it also includes a liquid crystal display for displaying voltage and current. 6. A power supply for a wide-band current booster according to claim 1, characterized in that: the single-chip microcomputer realizes the control of the current booster and steady current of the current booster based on the PID algorithm.

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