阅读说明：本技术 一种电源自动转换系统用电流及频率采样电路 (Current and frequency sampling circuit for automatic power supply conversion system ) 是由 代智 尚劲 于 2019-04-12 设计创作，主要内容包括：本发明涉及一种电源自动转换系统用电流及频率采样电路,用以实现电源转换系统对检测负载的电流及频率的采样,包括依次连接的互感器、采样模块、电流检测模块和频率检测模块,所述的频率检测模块与MCU的输入捕获端口连接,其特征在于,所述的频率检测模块包括相互连接的电压比较器单元和门电路单元,所述的电压比较器单元的输入端分别连接电压基准和电流检测模块,输出端通过门电路单元与MCU的输入捕获端口连接。与现有技术相比,本发明具有抗干扰能力强、频率输出纹波小、采样精度高等优点。(The invention relates to a current and frequency sampling circuit for a power supply automatic conversion system, which is used for sampling the current and frequency of a detection load by the power supply conversion system. Compared with the prior art, the invention has the advantages of strong anti-interference capability, small frequency output ripple, high sampling precision and the like.)

1. The utility model provides a power is current and frequency sampling circuit for automatic transfer system for realize the sampling of power transfer system to the current and the frequency of detecting load, including mutual-inductor (PT1), sampling module, current detection module and the frequency detection module that connects gradually, the frequency detection module be connected with MCU's input capture port, a serial communication port, the frequency detection module include interconnect's voltage comparator unit and gate circuit unit, the input of voltage comparator unit connect voltage benchmark (VREF) and current detection module respectively, the output is caught the port through gate circuit unit and MCU's input and is connected.

2. The current and frequency sampling circuit for power automatic switching system according to claim 1, wherein said current detection module comprises a first operational amplifier (U1), a first capacitor (C2) and a feedback resistor (R7), an output terminal of said first operational amplifier (U1) is connected to a negative input terminal through a first capacitor (C2) and a feedback resistor (R7) which are connected in parallel to each other, an output terminal of the first operational amplifier (U1) is connected to an ADC port of the MCU and an input terminal of the voltage comparator unit through a first resistor (R8), a negative input terminal of said first operational amplifier (U1) is connected to a positive electrode of the transformer (PT1) through a first high side sampling resistor (R2), and a positive input terminal is connected to a positive electrode of the transformer (PT1) through a second high side sampling resistor (R3).

3. The current and frequency sampling circuit for the automatic power conversion system according to claim 2, wherein the sampling module comprises a sampling resistor (R1) and a sampling capacitor (C1) respectively connected in parallel to two ends of a transformer (PT1), the positive input terminal of the first operational amplifier (U1) is connected to the Voltage Reference (VREF) through a low-side sampling resistor (R6), the positive electrode of the transformer (PT1) is connected to the Voltage Reference (VREF) through a first pull-up resistor (R4), and the negative electrode of the transformer (PT1) is connected to the Voltage Reference (VREF) through a second pull-up resistor (R5).

4. The current and frequency sampling circuit according to claim 3, wherein the voltage comparator unit comprises a second operational amplifier (U2), the negative input terminal of the second operational amplifier (U2) is connected to the Voltage Reference (VREF), the positive input terminal is connected to the output terminal of the first operational amplifier (U1) through a second resistor (R9) and a first resistor (R8), and the output terminal of the second operational amplifier (U2) is connected to the gate unit.

5. The current and frequency sampling circuit for power automatic switching system as claimed in claim 4, wherein said gate circuit unit comprises a second capacitor (C7) and a gate circuit (U3), one end of said second capacitor (C7) is connected to the power supply (VCC) through a third pull-up resistor (R10), the other end is grounded, the input end of said gate circuit (U3) and the output end of the second operational amplifier (U2) are respectively connected between the third pull-up resistor (R10) and the second capacitor (C7), and the output end of the gate circuit (U3) is connected to the input capture port of the MCU.

6. The current and frequency sampling circuit for the automatic power conversion system according to claim 5, wherein after the current path to be detected passes through the current transformer (PT1), a voltage is generated across the sampling capacitor (C1) and the sampling resistor (R1), the voltage and the Voltage Reference (VREF) are connected to the ADC port of the MCU through the output of the differential amplifier module to realize current detection, the output is connected to the frequency detection module at the same time, and after passing through the voltage comparator unit and the gate circuit unit, the output and the Voltage Reference (VREF) are connected to the input capture port of the MCU to realize frequency detection.

7. The current and frequency sampling circuit of claim 4, wherein the negative input terminal of the second operational amplifier (U2) is further connected to ground through a second filter capacitor (C5).

8. The current and frequency sampling circuit of claim 5, wherein the first resistor (R8) is connected to ground through a third capacitor (C4).

9. The current and frequency sampling circuit for an automatic power conversion system as claimed in claim 1, wherein the Voltage Reference (VREF) has a value of 1.5V.

Technical Field

The invention relates to a sampling circuit, in particular to a current and frequency sampling circuit for an automatic power supply conversion system.

Background

Along with the development of electric power utilities, the requirements of electric equipment on the continuity and the reliability of a power supply are higher and higher, the misjudgment rate of the output of a control system can be reduced to the minimum by a good signal acquisition technology, the reliability of the system is improved, the controller can detect the condition of the electric equipment in real time, and when the electric equipment deviates from a set normal state, the electric equipment can be timely reflected and adjusted.

As shown in fig. 1, the current of the existing sampling circuit is directly connected to the differential amplifier through the transformer, and the frequency detection is directly output to the MCU through only one voltage comparator. Resulting in several problems as follows:

1) the current sampling waveform has poor anti-interference capability;

2) oscillation is easy to generate;

3) the frequency output ripple is large, and the omission or multiple detection is easy;

4) the filtering capability is not strong, and the sampling precision is easily influenced by power fluctuation;

disclosure of Invention

The present invention is directed to a current and frequency sampling circuit for an automatic power conversion system to overcome the above-mentioned drawbacks of the prior art.

The purpose of the invention can be realized by the following technical scheme:

the utility model provides a power is current and frequency sampling circuit for automatic transfer system for realize the sampling of power transfer system to the current and the frequency of detecting load, including mutual-inductor, sampling module, current detection module and the frequency detection module that connects gradually, frequency detection module and MCU's input capture port be connected, its characterized in that, frequency detection module include interconnect's voltage comparator unit and gate circuit unit, the input of voltage comparator unit connect voltage reference and current detection module respectively, the output passes through gate circuit unit and MCU's input capture port and is connected.

The current detection module include first operational amplifier, first electric capacity and feedback resistance, first operational amplifier's output be connected with the negative input end through mutual parallel connection's first electric capacity and feedback resistance to first operational amplifier's output is connected with MCU's ADC port and voltage comparator unit's input respectively through first resistance, first operational amplifier's negative input end be connected with the positive pole of mutual-inductor through first high side sampling resistance, the positive input end is connected with the positive pole of mutual-inductor through second high side sampling resistance.

The sampling module comprises a sampling resistor and a sampling capacitor which are respectively connected in parallel at two ends of the mutual inductor, the positive input end of the first operational amplifier is connected with a voltage reference through a low-side sampling resistor, the positive electrode of the mutual inductor is connected with the voltage reference through a first pull-up resistor, and the negative electrode of the mutual inductor is connected with the voltage reference through a second pull-up resistor.

The voltage comparator unit comprises a second operational amplifier, the negative input end of the second operational amplifier is connected with a voltage reference, the positive input end of the second operational amplifier is connected with the output end of the first operational amplifier sequentially through a second resistor and a first resistor, and the output end of the second operational amplifier is connected with the gate circuit unit.

The gate circuit unit comprises a second capacitor and a gate circuit, one end of the second capacitor is connected with the power supply through a third pull-up resistor, the other end of the second capacitor is grounded, the input end of the gate circuit and the output end of the second operational amplifier are respectively connected between the third pull-up resistor and the second capacitor, and the output end of the gate circuit is connected with the input capture port of the MCU.

After a current path to be detected passes through a current transformer, voltages are generated at two ends of a sampling capacitor and a sampling resistor, the voltage and the voltage reference are connected to an ADC port of the MCU through the output of a differential amplifier module to realize current detection, the output is simultaneously connected to a frequency detection module, and the voltage reference and the frequency reference are connected to an input capture port of the MCU through a voltage comparator unit and a gate circuit unit to realize frequency detection.

The negative input end of the second operational amplifier is grounded through a second filter capacitor.

The first resistor is grounded through a third capacitor.

The voltage reference has a value of 1.5V.

Compared with the prior art, the invention has the following advantages:

1) the anti-interference capability is strong: the stability of the circuit is improved by the arrangement of the sampling capacitor and the two pull-up resistors, so that the anti-interference capability of current waveform output is stronger;

2) restraining self-oscillation: a first capacitor connected with the feedback resistor in parallel is arranged between the negative input end and the output end of the first operational amplifier, so that the generation of self-oscillation of the amplifier is effectively inhibited;

3) the ripple of the frequency output waveform is small: the output waveform of the voltage comparator is filtered by a second capacitor and is processed by a gate circuit unit, so that the ripple of the frequency waveform is extremely small;

4) the filtering capability is strong: the low-pass filtering construction enhances the power supply fluctuation resistance of the circuit and improves the sampling precision.

Drawings

FIG. 1 is a circuit diagram of a prior art sampling circuit;

fig. 2 is a circuit diagram of a sampling circuit of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.