Two-stage voltage sampling circuit

Abstract

The utility model discloses a two-stage voltage sampling circuit, which comprises a full-bridge converter, a four-switch buck-boost converter and a digital signal processor DSP, the output end of the full-bridge converter is connected with a capacitor C1, the capacitor C1 is connected with a post-stage four-switch buck-boost converter, and the post-stage four-switch buck-boost converter is connected with the digital signal processor DSP. The output voltage of the full-bridge converter is filtered by a capacitor C1 and then enters a back-stage four-switch buck-boost converter, the four-switch buck-boost converter comprises four power switch tubes and an inductor L1, and the four power switch tubes are respectively a power switch tube Q1, a power switch tube Q2, a power switch tube Q3 and a power switch tube Q4. The four-switch buck-boost converter is input to a digital signal processor DSP through a voltage sampling circuit, and the output of the four-switch buck-boost converter is output through a filter capacitor C2 and a load R1. The system is provided with the full-bridge converter, the four-switch buck-boost converter and the digital signal processor, and the two-stage full-bridge converter and four-switch buck-boost converter topology is adopted, so that the precision of the collected voltage is higher, the calculation of the digital signal processor is more accurate, and the loop is more stable; the reliability of the loop is improved, the stability of the output voltage and the efficiency of the power supply are improved, and the output ripples are effectively reduced.

Description

Technical Field

[0001] This utility model relates to a sampling circuit, specifically a two-stage voltage sampling circuit. Background Technology

[0002] With the development of technology, there is a huge demand for high power density and high reliability DC / DC module power supplies in military and industrial production. At the same time, the power requirements of single module half-bricks are getting bigger and bigger, and the module power supplies are required to have isolation, high efficiency, low ripple, etc. Single-stage circuits cannot meet the growing demand, which has led to the development of combined designs that utilize the characteristics of various topologies.

[0003] The current approach is:

[0004] In modular power supply design, due to size limitations, most modular power supplies adopt a single-stage topology to reduce the number of components, increase the area for carrying large currents, and reduce internal circuit losses while improving efficiency. However, using a single-stage circuit may not be able to simultaneously achieve the stringent requirements of high efficiency and low ripple. Currently, to achieve the requirements of isolation, high efficiency, and low ripple in power modules, multiple topologies are often combined in development.

[0005] The traditional two-stage topology output voltage sampling circuit method is to sample the voltage at the topology input terminal for input undervoltage and overvoltage protection functions; and to participate in the module loop and other parameter calculations. The output voltage sampling of the subsequent stage is used for loop and other calculations. However, when the sampled parameters are entered into the DSP for calculation, the calculated parameters are inaccurate, which will lead to inaccurate digital calculations and loop instability. Utility Model Content

[0006] To address the problem of loop instability, this invention provides a two-stage voltage sampling circuit.

[0007] This utility model provides the following technical solution:

[0008] A two-stage voltage sampling circuit includes a full-bridge converter, a four-switch buck-boost converter, and a digital signal processor (DSP). The output of the full-bridge converter is connected to a capacitor C1, which is connected to the subsequent four-switch buck-boost converter. The output voltage of the full-bridge converter is filtered by capacitor C1 and then enters the subsequent four-switch buck-boost converter. The four-switch buck-boost converter includes four power switches and an inductor L1. The four power switches are Q1, Q2, Q3, and Q4. The voltage of the four-switch buck-boost converter is input to the DSP through a voltage sampling circuit. The output of the four-switch buck-boost converter is output through a filter capacitor C2 and a load R1.

[0009] Furthermore, the voltage sampling circuit includes operational amplifier U1 and operational amplifier U2. The front stage of inductor L1 is connected to operational amplifier U1 through a resistor, and the rear stage of inductor L1 is connected to operational amplifier U2 through a resistor.

[0010] Furthermore, power switch Q1 is connected to power switch Q2, and power switch Q3 and power switch Q4 are connected. The output terminal of the full-bridge converter is first connected to power switch Q1 and Q2, and then connected to power switch Q3 and Q4.

[0011] Furthermore, the gates of the power switches Q1, Q2, Q3, and Q4 are connected to the digital signal processor (DSP).

[0012] Furthermore, the full-bridge converter includes four power switching transistors on each of the left and right sides, forming a bridge arm structure, and is isolated by a transformer in the middle.

[0013] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention comprises a full-bridge converter, a four-switch buck-boost converter, and a digital signal processor. It employs a two-stage full-bridge converter and a four-switch buck-boost converter topology. The full-bridge converter input voltage is sampled for undervoltage and overvoltage protection of the module power supply. The full-bridge output voltage (and bus voltage or the four-switch buck-boost converter input voltage) is used to determine bus voltage stability. The voltages across the four-switch inductors are used for loop calculation and status determination. Compared with traditional two-stage voltage sampling, the sampled voltage has higher accuracy, making the digital signal processor (DSP) calculations more accurate and the loop more stable. This improves loop reliability, enhances output voltage stability and power efficiency, and effectively reduces output ripple. Attached Figure Description

[0014] Figure 1 This is the circuit diagram of this utility model;

[0015] Figure 2 This is the circuit diagram of the full-bridge converter of this utility model;

[0016] Figure 3 This is the DSP circuit diagram of this utility model. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] Please see Figure 1-3 This utility model discloses a two-stage voltage sampling circuit, including a full-bridge converter, a four-switch buck-boost converter, and a digital signal processor (DSP). The output of the full-bridge converter is connected to capacitor C1, and capacitor C1 is connected to the subsequent four-switch buck-boost converter. The output voltage of the full-bridge converter is filtered by capacitor C1 and then enters the subsequent four-switch buck-boost converter. The four-switch buck-boost converter includes four power switches and an inductor L1. The four power switches are power switches Q1, Q2, Q3, and Q4. The voltage of the four-switch buck-boost converter is input to the DSP through a voltage sampling circuit. The output of the four-switch buck-boost converter is output through a filter capacitor C2 and a load R1.

[0019] The voltage sampling circuit includes operational amplifier U1 and operational amplifier U2. The front stage of inductor L1 is connected to operational amplifier U1 through a resistor, and the rear stage of inductor L1 is connected to operational amplifier U2 through a resistor.

[0020] Power switches Q1 and Q2 are connected, and power switches Q3 and Q4 are connected. The output of the full-bridge converter is first connected to power switches Q1 and Q2, and then to power switches Q3 and Q4.

[0021] The gates of power switches Q1, Q2, Q3, and Q4 are connected to the digital signal processor (DSP).

[0022] A full-bridge converter consists of four power MOSFETs on each side. One side has MOSFETs Q5, Q6, Q7, and Q8, while the other side has MOSFETs Q9, Q10, Q11, and Q12. The overall structure is a bridge arm, isolated by a transformer. Its working principle is as follows: by controlling four sets of PWM signals (PWM1-PWM4), the MOSFETs on the bridge arms are turned on and off in a specific timing sequence, converting the input DC voltage into a high-frequency square wave voltage. After being isolated and transformed by the transformer, the output DC voltage is obtained by rectification and filtering by the secondary circuit. Full-bridge converters can achieve high power transfer and have high efficiency.

[0023] The digital signal processor used is ADP32F035, which is the core controller of this application.

[0024] The input voltage sampling of the full-bridge converter is used for the undervoltage and overvoltage protection function of the module power supply. The output voltage of the full-bridge converter is filtered by the bus capacitor C1 and then enters the subsequent four-switch buck-boost converter. The four-switch buck-boost converter includes four power switches and an inductor L1. The four power switches Q1, Q2, Q3, and Q4 are input to the DSP through the voltage sampling circuit for calculation and status judgment to turn the switches on and off. The voltage sampling circuit before the inductor L1 of the four-switch buck-boost converter includes resistors R4, R5, R7, R8, R9, and R11, capacitors C3, C5, and C6, and operational amplifier U1. The voltage sampling circuit after the inductor L1 includes resistors R2, R3, R12, R13, R14, and R15, capacitors C4, C7, and C8, and operational amplifier U2. The output of the four-switch buck-boost converter is filtered by capacitor C2 and output through the load R1.

[0025] Power switching transistors (Q1 - Q4): These are MOSFETs or IGBTs, used to control the switching on and off of circuits. They achieve energy conversion and transfer by turning on and off in a specific timing sequence.

[0026] Inductor (L1): Used to store and release energy, maintaining the continuity of current during the switching process of the transistor.

[0027] Capacitors (C1-C8): They serve functions such as filtering, energy storage, and DC blocking. Capacitors C1 and C2 are used for filtering to stabilize the output voltage; capacitors C3 and C4 are used to absorb the voltage spikes when the switching transistor is turned off.

[0028] Resistors (R1-R15): Used for voltage division, current limiting, biasing, etc. They provide sampling voltage to the control chip through voltage division.

[0029] Operational amplifiers (U1, U2): used for signal amplification, comparison and other functions, and process the sampled signal and feed it back to the digital signal processor (DSP).

[0030] Digital Signal Processor (DSP): As the control core, it generates control signals according to a predetermined algorithm based on input and feedback signals, drives power switching transistors, realizes closed-loop control of the full-bridge converter, and ensures stable output voltage and current.

[0031] Working principle:

[0032] When the full-bridge converter is operating, the two sets of switching transistors Q1 and Q4, and Q2 and Q3, conduct alternately. When Q1 and Q4 are on, current flows through Q1, inductor L1, the load, and Q4 to form a loop, and inductor L1 stores energy. When Q2 and Q3 are on, inductor L1 releases energy. The output voltage and current can be adjusted by precisely controlling the on-time (duty cycle) of the switching transistors through the DSP. The operational amplifier, in conjunction with the resistor network, samples and processes the output voltage and current signals, feeding them back to the DSP to achieve closed-loop control and stabilize the output at the set value.

[0033] Compared with traditional two-stage voltage sampling, the sampled voltage has higher accuracy, making DSP calculations more accurate and the loop more stable; it improves the reliability of the loop, enhances the stability of the output voltage and power efficiency, and effectively reduces output ripple.

[0034] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A two-stage voltage sampling circuit, characterized by: The system includes a full-bridge converter, a four-switch buck-boost converter, and a digital signal processor (DSP). The output of the full-bridge converter is connected to capacitor C1, which is connected to the subsequent four-switch buck-boost converter. The output voltage of the full-bridge converter is filtered by capacitor C1 before entering the subsequent four-switch buck-boost converter. The four-switch buck-boost converter includes four power transistors (Q1, Q2, Q3, and Q4) and an inductor L1. The voltage of the four-switch buck-boost converter is input to the DSP through a voltage sampling circuit. The output of the four-switch buck-boost converter is output through a filter capacitor C2 and a load R1.

2. The two-stage voltage sampling circuit according to claim 1, characterized in that: The voltage sampling circuit includes operational amplifier U1 and operational amplifier U2. The front stage of inductor L1 is connected to operational amplifier U1 through a resistor, and the rear stage of inductor L1 is connected to operational amplifier U2 through a resistor.

3. The two-stage voltage sampling circuit of claim 1, wherein: The power switch Q1 is connected to the power switch Q2, and the power switch Q3 is connected to the power switch Q4. The output terminal of the full-bridge converter is first connected to the power switches Q1 and Q2, and then connected to the power switches Q3 and Q4.

4. The two-stage voltage sampling circuit of claim 1, wherein: The gates of power switches Q1, Q2, Q3, and Q4 are connected to the digital signal processor (DSP).

5. The two-stage voltage sampling circuit of claim 1, wherein: The full-bridge converter includes four power switching transistors on each of the left and right sides, forming a bridge arm structure, and is isolated by a transformer in the middle.

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