A feedback voltage acquisition circuit based on a phase-shifted full-bridge converter

Abstract

This utility model relates to the field of voltage acquisition technology, specifically a feedback voltage acquisition circuit based on a phase-shifted full-bridge converter. It includes an inverter circuit, a resonant circuit, and a rectifier circuit electrically connected together. A voltage acquisition circuit is electrically connected to the resonant circuit. The voltage acquisition circuit includes operational amplifiers U1A, U1B, and U1C arranged in series. A capacitor C1 and a resistor R1 are connected in parallel on pins 1 and 2 of operational amplifier U1A. One end of operational amplifier U1A is connected to the voltage signal of a current transformer through a resistor R3. This utility model promptly disconnects the system connection when overvoltage or undervoltage occurs in the power grid, protecting the power grid and electrical appliances. The operational amplifiers implement second-order filtering. As voltage followers, the operational amplifiers achieve isolation, improve input impedance, reduce output impedance, and improve the small-signal load-driving capability.

Description

Technical Field

[0001] This utility model relates to a voltage acquisition circuit, and more particularly to a feedback voltage acquisition circuit based on a phase-shifting full-bridge converter, belonging to the field of voltage acquisition technology. Background Technology

[0002] In the process of generating, transmitting, and using electrical energy, the full-bridge converter is an extremely important component. Excessive voltage can endanger the safety of electrical equipment and reduce its service life, while excessively low voltage is detrimental to the safe and stable operation of the power grid. According to national standards, overvoltage or undervoltage refers to a voltage amplitude exceeding or falling below the nominal voltage for a duration greater than 60 seconds, with values ​​between 1.1 and 1.2 pu or 0.8 and 0.9 pu. By using intelligent circuit breakers to analyze and judge the power grid voltage signal, the system connection can be promptly disconnected when overvoltage or undervoltage occurs in the power grid, protecting the power grid and electrical appliances.

[0003] Currently, the voltage acquisition circuit of the converter is too simple and cannot cut off the circuit in time to isolate the fault. Once a circuit failure is triggered, it will cause unnecessary losses.

[0004] Therefore, it is urgent to improve the feedback voltage acquisition circuit based on the phase-shifted full-bridge converter in order to solve the above-mentioned problems. Utility Model Content

[0005] The purpose of this invention is to provide a feedback voltage acquisition circuit based on a phase-shifted full-bridge converter, which can promptly disconnect the system connection when overvoltage or undervoltage occurs in the power grid, thereby protecting the power grid and electrical appliances. The operational amplifier implements second-order filtering, and the operational amplifier acts as a voltage follower, achieving isolation, improving input impedance, reducing output impedance, and improving the small-signal load-driving capability.

[0006] To achieve the above objectives, the main technical solutions adopted by this utility model include:

[0007] A feedback voltage acquisition circuit based on a phase-shifted full-bridge converter includes an inverter circuit, a resonant circuit, and a rectifier circuit that are electrically connected. A voltage acquisition circuit is electrically connected to the resonant circuit. The voltage acquisition circuit includes operational amplifiers U1A, U1B, and U1C that are connected in series. Pin 1 of operational amplifier U1A is electrically connected to pin 6 of operational amplifier U1B, and pin 7 of operational amplifier U1B is electrically connected to pin 10 of operational amplifier U1B.

[0008] A capacitor C1 and a resistor R1 are connected in parallel on pins 1 and 2 of the operational amplifier U1A, and a resistor R2 and a capacitor C3 are connected in parallel on pins 6 and 7 of the operational amplifier U1B. One end of the operational amplifier U1A is connected to the voltage signal of the current transformer through a resistor R3.

[0009] Preferably, a resistor R6 is electrically connected between the operational amplifier U1A and the operational amplifier U1B, and the operational amplifier U1C is electrically connected to the rectifier circuit through a resistor R8.

[0010] Preferably, diodes VD3 and VD4 are electrically connected between the resistor R8 and the rectifier circuit, and a capacitor C4 is connected in parallel with diode VD3.

[0011] Preferably, a resistor R5 is electrically connected to pin 3 of the operational amplifier U1A, a resistor R7 is electrically connected to pin 5 of the operational amplifier U1B, and the diode VD3 is electrically connected to the resistors R5 and R7.

[0012] Preferably, the inverter circuit includes a main switch T1, a main switch T2, a main switch T3, and a main switch T4, wherein the main switch T1 and the main switch T2 are connected in series, and the main switch T3 and the main switch T4 are connected in series.

[0013] Preferably, a transformer Tr is electrically connected between the resonant circuit and the rectifier circuit, and an inductor Lm is provided on the resonant circuit in parallel with the transformer Tr. An inductor Lr and a capacitor Cr are electrically connected to the inductor Lm.

[0014] Preferably, the rectifier circuit includes diode VD1 and diode VD2, and a load is electrically connected to the rectifier circuit.

[0015] This utility model has at least the following beneficial effects:

[0016] When overvoltage or undervoltage occurs in the power grid, the system connection is disconnected in a timely manner to protect the power grid and electrical appliances. The operational amplifier implements second-order filtering. As a voltage follower, the operational amplifier achieves isolation, improves input impedance, reduces output impedance, and improves the ability to drive small signals with loads. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 This is the electrical schematic diagram of this utility model;

[0019] Figure 2 This is the circuit diagram of this utility model;

[0020] Figure 3 This is a voltage acquisition circuit diagram of this utility model.

[0021] In the diagram, 1 is the inverter circuit; 2 is the resonant circuit; 3 is the rectifier circuit; and 4 is the voltage acquisition circuit. Detailed Implementation

[0022] The following will describe in detail the implementation of this application with reference to the accompanying drawings and embodiments, so that the implementation process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0023] like Figures 1-3 As shown, the feedback voltage acquisition circuit based on a phase-shifted full-bridge converter provided in this embodiment includes an inverter circuit, a resonant circuit, and a rectifier circuit that are electrically connected. The combination of the inverter circuit, resonant circuit, and rectifier circuit can achieve efficient power conversion and control, improving system efficiency and performance. A voltage acquisition circuit is electrically connected to the resonant circuit. The voltage acquisition circuit includes operational amplifiers U1A, U1B, and U1C arranged in series. Pin 1 of operational amplifier U1A is electrically connected to pin 6 of operational amplifier U1B, and pin 7 of operational amplifier U1B is electrically connected to... Operational amplifier U1B's pin 10 is electrically connected. A capacitor C1 and a resistor R1 are connected in parallel on pins 1 and 2 of operational amplifier U1A. A resistor R2 and a capacitor C3 are connected in parallel on pins 6 and 7 of operational amplifier U1B. One end of operational amplifier U1A is connected to the transformer voltage signal through resistor R3. Excessive voltage can endanger the safety of power equipment and reduce its lifespan, while insufficient voltage is detrimental to the safe and stable operation of the power grid. According to national standards, overvoltage or undervoltage refers to a voltage amplitude exceeding or falling below the nominal voltage for a duration greater than 60 seconds, with a value between 1.1 and 1.2 pu or 0.8 and 0.9 pu. Intelligent circuit breakers are used to analyze and judge the power grid voltage signal, promptly disconnecting the system connection when overvoltage or undervoltage occurs, protecting the power grid and electrical appliances. The AC voltage sampling circuit is as follows: Figure 3 As shown, operational amplifiers U1A and U1B implement second-order filtering, while operational amplifier U1C acts as a voltage follower, achieving isolation, increasing input impedance, reducing output impedance, and improving the small-signal load-driving capability.

[0024] Furthermore, such as Figure 3As shown, operational amplifiers U1A and U1B are electrically connected by resistor R6. Operational amplifier U1C is electrically connected to the rectifier circuit through resistor R8. Diodes VD3 and VD4 are electrically connected between resistor R8 and the rectifier circuit. A capacitor C4 is connected in parallel with diode VD3. A resistor R5 is electrically connected to pin 3 of operational amplifier U1A, and a resistor R7 is electrically connected to pin 5 of operational amplifier U1B. Diode VD3 is electrically connected to resistors R5 and R7. The capacitor C4 connected in parallel with diode VD3 can form an oscillator to generate a periodic signal. At the moment of power-on, due to the capacitance of the subsequent circuit, the starting current is large. Capacitor C4 can share the burden of diode startup, protecting the diode from damage. Through parallel capacitors, the adaptability of the circuit is enhanced, enabling it to work more stably in different environments. In addition, the parallel connection of capacitor C4 also helps to prevent voltage spikes in the circuit, improves the circuit's anti-interference ability, and thus ensures the reliable operation of the circuit.

[0025] Furthermore, such as Figure 2 As shown, the inverter circuit includes main switching transistors T1, T2, T3, and T4. Main switching transistors T1 and T2 are connected in series, and main switching transistors T3 and T4 are connected in series. Therefore, two modulation methods are adopted: finite bipolar PWM modulation and full-bridge phase-shift modulation. The finite bipolar PWM modulation strategy uses the lower transistors, namely main switching transistors T2 and T4, for PWM modulation, while the upper transistors are turned on sequentially according to half of the switching cycle. The full-bridge phase-shift modulation uses the left half-bridge main switching transistors T1 and T2 as the reference, and the control timing of the right half-bridge is phase-shifted relative to the left half-bridge to control the output voltage. The duty cycles of main switching transistors T1 and T3 are both 0.5, and they are turned on alternately. Compared with the traditional bipolar control method, finite bipolar control only adjusts the duty cycle of one switching transistor each time it is turned on, which can more easily achieve soft-switching operation.

[0026] Furthermore, such as Figure 2As shown, a transformer Tr is electrically connected between the resonant circuit and the rectifier circuit. An inductor Lm is connected in parallel with the transformer Tr on the resonant circuit. An inductor Lr and a capacitor Cr are electrically connected to the inductor Lm. The inductor Lr is electrically connected to the inverter circuit 1 through the DC blocking capacitor Cr. When the PWM-driven MOSFET is turned on, the on-state voltage drop of the MOSFET is ignored, and the voltage across the inductor remains constant. When the PWM-driven MOSFET is turned off, the inductor current forms a loop through the diode VD1, and the inductor current decreases linearly. The rectifier circuit includes diodes VD1 and VD2, and a load is electrically connected to the rectifier circuit. Since DC voltage is usually much lower than AC voltage, converting AC voltage to DC voltage can reduce the maximum AC voltage faced by electronic components, thereby improving the safety and stability of the circuit.

[0027] like Figures 1-3 As shown, the principle of the feedback voltage acquisition circuit based on the phase-shifted full-bridge converter provided in this embodiment is as follows:

[0028] The inverter circuit, resonant circuit, and rectifier circuit are electrically connected. The combination of these circuits enables efficient power conversion and control, improving system efficiency and performance. A voltage acquisition circuit is electrically connected to the resonant circuit. This circuit includes operational amplifiers U1A, U1B, and U1C, arranged in series. Pin 1 of operational amplifier U1A is electrically connected to pin 6 of operational amplifier U1B, and pin 7 of operational amplifier U1B is electrically connected to pin 10. A capacitor C1 and a resistor R1 are connected in parallel on pins 1 and 2 of operational amplifier U1A, and a resistor R2 and a capacitor C3 are connected in parallel on pins 6 and 7 of operational amplifier U1B. One end of operational amplifier U1A is connected to the transformer voltage signal through resistor R3. Excessive voltage can endanger the safety of power equipment and reduce its lifespan, while insufficient voltage is detrimental to the safe and stable operation of the power grid. According to national standards, overvoltage or undervoltage refers to a voltage amplitude exceeding or falling below the nominal voltage for a duration greater than 60 seconds. The value of s is between 1.1 and 1.2 pu or 0.8 and 0.9 pu. The application of intelligent circuit breakers analyzes and judges the grid voltage signal, and disconnects the system connection in time when overvoltage or undervoltage occurs in the grid, protecting the grid and electrical appliances. Operational amplifiers U1A and U1B implement second-order filtering, and operational amplifier U1C acts as a voltage follower, realizing isolation, improving input impedance, reducing output impedance, and improving the small-signal load-driving capability.

[0029] If certain terms are used in the specification and claims to refer to specific components, those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" as used throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.

[0030] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes that element.

[0031] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A feedback voltage acquisition circuit based on a phase-shifted full-bridge converter, comprising an inverter circuit (1), a resonant circuit (2) and a rectifier circuit (3) connected in electrical connection, characterized in that, The resonant circuit (2) is electrically connected to a voltage acquisition circuit (4). The voltage acquisition circuit (4) includes an operational amplifier U1A, an operational amplifier U1B and an operational amplifier U1C arranged in series. Pin 1 of the operational amplifier U1A is electrically connected to pin 6 of the operational amplifier U1B, and pin 7 of the operational amplifier U1B is electrically connected to pin 10 of the operational amplifier U1B. A capacitor C1 and a resistor R1 are connected in parallel on pins 1 and 2 of the operational amplifier U1A, and a resistor R2 and a capacitor C3 are connected in parallel on pins 6 and 7 of the operational amplifier U1B. One end of the operational amplifier U1A is connected to the voltage signal of the current transformer through a resistor R3. 2.The feedback voltage sampling circuit based on a phase-shifted full-bridge converter of claim 1, wherein: The operational amplifier U1A and the operational amplifier U1B are electrically connected by a resistor R6, and the operational amplifier U1C is electrically connected to the rectifier circuit (3) through a resistor R8. 3.The feedback voltage sampling circuit based on a phase-shifted full-bridge converter of claim 1, wherein: The resistor R8 is electrically connected to the rectifier circuit (3) by diodes VD3 and VD4, and a capacitor C4 is connected in parallel on the diode VD3.

4. The feedback voltage acquisition circuit based on a phase-shifted full-bridge converter according to claim 1, characterized in that: A resistor R5 is electrically connected to pin 3 of the operational amplifier U1A, a resistor R7 is electrically connected to pin 5 of the operational amplifier U1B, and the diode VD3 is electrically connected to the resistors R5 and R7.

5. The feedback voltage sampling circuit based on the phase-shifted full-bridge converter according to claim 1, characterized in that: The inverter circuit (1) includes a main switch transistor T1, a main switch transistor T2, a main switch transistor T3 and a main switch transistor T4. The main switch transistor T1 and the main switch transistor T2 are connected in series, and the main switch transistor T3 and the main switch transistor T4 are connected in series.

6. The feedback voltage sampling circuit based on a phase-shifted full-bridge converter according to claim 1, characterized in that: A transformer Tr is electrically connected between the resonant circuit (2) and the rectifier circuit (3). An inductor Lm is provided on the resonant circuit (2) in parallel with the transformer Tr. An inductor Lr and a capacitor Cr are electrically connected to the inductor Lm.

7. The feedback voltage sampling circuit based on a phase-shifted full-bridge converter according to claim 1, characterized in that: The rectifier circuit (3) includes diodes VD1 and VD2, and a load is electrically connected to the rectifier circuit (3).

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