Parallel output DC power supply

Abstract

The utility model provides a parallel output DC power supply. The parallel output DC power supply comprises an interface circuit, a Buck-Boost adjusting circuit, a sampling circuit and a control system circuit. The Buck-Boost adjusting circuit is connected with the sampling circuit and the control system circuit; the interface circuit comprises a power interface and a control card interface; the Buck-Boost adjusting circuit comprises a first onboard half-bridge driving circuit, a second onboard half-bridge driving circuit and a Buck-Boost power topology; the sampling circuit comprises an input and output current sampling circuit, an inductive current sampling circuit, an OLED screen circuit and an input and output voltage sampling circuit. The control system circuit comprises an MCU power supply management circuit, an MCU power supply filter capacitor circuit, a control chip circuit, an auxiliary power supply, a reference voltage source circuit, an LED circuit and a crystal oscillator circuit. By applying the technical scheme, the flexible combined use of the direct current power supply can be realized, the output current can be modularly increased according to the demand of the load current, and the flexibility and applicability of the equipment are enhanced.

Description

TECHNICAL FIELD

[0001] The utility model relates to electrical engineering, automation control, embedded system technical field, especially a parallel output direct current source. BACKGROUND

[0002] For some high-precision sensitive low-voltage equipment, such as precision instruments, optoelectronic devices, communication equipment and medical equipment, low-voltage, low-ripple, adjustable voltage power supply is usually required.

[0003] MOSFET (field effect transistor) circuits have a wide range of applications in modern electronic technology, particularly in low-power, high-frequency and digital control. Such circuits are widely used in communication systems, power electronics, and power management.

[0004] Existing digital control direct current sources usually use DSP (digital signal processor) to output low-frequency PWM wave to control the shutdown of transistors. This method has the disadvantages of large output ripple, large size, and great limitations in use.

[0005] After searching the patent website, a similar patent was found, a practical patent "Programmable Low-Ripple High-Voltage Stable Power Supply". In this patent, based on the Boost circuit, the digital programmable device DPD, digital-to-analog converter DAC, AD sampling and conversion circuit (including ADC), DC-DC conversion circuit, Royer oscillation and direct current high-voltage generation circuit are integrated to solve the problem of programmable adjustment of high voltage. However, this patent has two defects: first, the output high voltage limits its application in precision instruments (such as RF circuits); second, the Royer circuit has potential defects that may cause damage to the transistor. Specifically, the scope of influence and possible causes of these problems need more detailed explanation to provide a more comprehensive understanding.

[0006] The prior art of classic DC switching power supply (such as buck type, boost type, or buck-boost type) has mature application range, but also has the disadvantages of serious electromagnetic interference, low light load efficiency, and large volume of inductive magnetic elements and capacitive elements. The core of the switching power supply is a high-frequency switching device (such as MOSFET, IGBT), and its fast on-off will generate high-frequency current spikes. These high-frequency interferences are transmitted through two main channels: conducted interference and radiated interference. The high-frequency ripple caused by switching action is conducted to the system through the power line, and the high-frequency switching process will generate electromagnetic waves through wiring, PCB traces, and heat sinks, etc. These two problems will interfere with other devices. The efficiency of the switching power supply is determined by switching loss and conduction loss, and at light load, these losses cannot be significantly reduced, resulting in a significant decrease in efficiency. The current and voltage superimposed during each conduction and turn-off of the switching tube will generate instantaneous power consumption. At light load, although the load power consumption is low, the frequency and number of switching actions have not decreased. The control circuit (such as PWM controller, reference voltage source, etc.) and MOSFET drain current loss still exist at light load and are difficult to reduce. Drive loss: the gate charge of the switching device will consume energy, and at light load, this part accounts for a higher proportion. Magnetic elements (such as inductors, transformers) are usually one of the largest components in switching power supplies. Its volume is limited by the magnetic flux density and operating frequency. The classic design uses a switching frequency of tens of kHz, and the lower the frequency, the greater the energy storage capacity required for the magnetic element, resulting in an increase in the volume of the magnetic core. Practical new type content

[0007] Therefore, the parallel output DC power supply is provided, which realizes flexible combination and use of the DC power supply, can modularly increase the output current according to the demand of the load current, and enhances the flexibility and applicability of the equipment.

[0008] In order to achieve the above object, the utility model discloses the following technical scheme: a parallel output direct current power supply, including interface circuit, buck -boost regulation circuit, sampling circuit and control system circuit, buck -boost regulation circuit connects the sampling circuit and the control system circuit, the interface circuit includes power interface (101) and control card interface (102), buck -boost regulation circuit includes first on -board half bridge drive circuit (2011), second on -board half bridge drive circuit (2012) and buck -boost power topology (202), the sampling circuit includes input and output current sampling circuit (301), inductance current sampling circuit (302), OLED screen circuit (303) and input and output voltage sampling circuit (304), the control system circuit includes MCU power management circuit (401), MCU power filter capacitor circuit (402), control chip circuit (403), auxiliary power supply and reference voltage source circuit (404), LED circuit (405) and crystal oscillator circuit (406),

[0009] In a preferred embodiment, the buck-boost power topology (202) includes a first MOS transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor; the drain of the first MOS transistor is connected to the first on-board half bridge drive circuit (2011), and the drain of the second MOS transistor is connected to the second on-board half bridge drive circuit (2012); the drain of the third MOS transistor is connected to the second on-board half bridge drive circuit (2012), and the drain of the fourth MOS transistor is connected to the first on-board half bridge drive circuit (2011).

[0010] In a preferred embodiment, a CC6920BSO current sensor is used as the input and output current sampling circuit (301) and the inductance current sampling circuit (302), and a first-order RC low-pass filter is set at the output end of the CC6920BSO current sensor to reduce output noise.

[0011] In a preferred embodiment, an OPA2188 is used as the operational amplifier chip of the input and output voltage sampling circuit (304), and a differential proportional operation circuit composed of an operational amplifier resistor network realizes 25 times reduction processing on voltage.

[0012] In a preferred embodiment, the control system circuit uses an STM32G474RBT6 single-chip microcomputer. First, the controller receives 5-way voltage and current signals from the sampling circuit, and quantizes the analog signals through the ADC circuit inside the STM32G474RBT6 single-chip microcomputer.

[0013] In a preferred embodiment, the STM32G474RBT6 single-chip microcomputer is further provided with a peripheral power supply VDD and VDDA, wherein VDD is a low-precision 3.3V, and VDDA adopts a REF3033 reference chip circuit to output a high-precision 3.3V voltage.

[0014] In a preferred embodiment, the LED circuit includes a red LED and a green LED.

[0015] Compared with the prior art, the application has the following beneficial effects: the application has multiple advantages compared with the prior art. First, the application introduces a frequency jitter function, which can effectively prevent EMI from interfering with other circuits and improve the service life and stability of the equipment. Second, by adding the parallel function of the power supply circuit, the application realizes flexible combination of the DC power supply, which can modularly increase the output current according to the demand of the load current, thereby enhancing the flexibility and applicability of the equipment. Finally, the application adopts a current inner loop and a voltage outer loop, thereby enhancing the applicability of the DC regulated power supply, and a single power supply can be self-adapted to different working environments without using multiple programs. In summary, the technical advantages of the application lie in perfect function, accurate control and stable reliability, and the application is expected to bring more efficient and reliable solutions to the related industry. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The circuit principle diagram of the preferred embodiment of the application is shown in the figure;

[0017] Figure 2 The inductor current waveform diagram under the Buck mode of the preferred embodiment of the application is shown in the figure;

[0018] Figure 3 The Bode diagram under the Buck mode of the preferred embodiment of the application is shown in the figure;

[0019] Figure 4 The DC power supply simulation diagram under parallel operation of the preferred embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0020] The application will be further described below in combination with the drawings and embodiments.

[0021] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the application belongs.

[0022] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application; as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0023] A parallel output DC power supply, referring to Figure 1 , comprising an interface circuit, a Buck-Boost regulating circuit, a sampling circuit and a control system circuit; the Buck-Boost regulating circuit is connected with the sampling circuit and the control system circuit; the interface circuit comprises a power interface 101 and a control card interface 102; the Buck-Boost regulating circuit comprises a first on-board half-bridge drive circuit 2011, a second on-board half-bridge drive circuit 2012 and a Buck-Boost power topology 202; the sampling circuit comprises an input and output current sampling circuit 301, an inductor current sampling circuit 302, an OLED screen circuit 303 and an input and output voltage sampling circuit 304; the control system circuit comprises an MCU power management circuit 401, an MCU power filter capacitor circuit 402, a control chip circuit 403, an auxiliary power supply and a reference voltage source circuit 404, an LED circuit 405 and a crystal oscillator circuit 406;

[0024] The power interface 103 can realize the splicing parallel output of two power supplies, and its connection content includes input and output ports and 12v, 5v and 3.3v signals. The control card interface 102 can realize the electrical connection with the control system circuit through a connector.

[0025] The Buck-Boost power topology 202 comprises a first MOSFET tube, a second MOSFET tube, a third MOSFET tube and a fourth MOSFET tube; the drain of the first MOSFET tube is connected with the first on-board half-bridge drive circuit 2011, and the drain of the second MOSFET tube is connected with the second on-board half-bridge drive circuit 2012; the drain of the third MOSFET tube is connected with the second on-board half-bridge drive circuit 2012, and the drain of the fourth MOSFET tube is connected with the first on-board half-bridge drive circuit 2011. The input DC power is driven by two high-speed half-bridge drive chips to alternately and complementarily chop four low-resistance MOSFETs, and the synchronous rectified DC power is filtered through a calculated inductor-capacitor filter network to output stable DC power. The MOSFETs alternately work in this process, and when one MOSFET is turned on, the other MOSFET is in the off state.

[0026] The CC6920BSO current sensor is used as the input and output current sampling circuit (301) and the inductance current sampling circuit (302), which can collect the current in two flow directions, and a first-order RC low-pass filter is arranged at the output end of the CC6920BSO current sensor to reduce the output noise.

[0027] The OPA2188 is used as the operational amplifier chip of the input and output voltage sampling circuit (304), and the differential proportional operation circuit composed of the operational amplifier resistor network realizes 25 times reduction processing on the voltage. The OLED display can display the signals collected by each sensor and the working state of the system.

[0028] The control system circuit uses an STM32G474RBT6 single-chip microcomputer. First, the controller receives 5-way voltage and current signals from the sampling circuit, and quantizes the analog signals through the ADC circuit inside the single-chip microcomputer. The digital discrete compensator program inside the single-chip microcomputer compensates the input multi-channel voltage and current signals, obtains the optimal output PWM duty cycle, optimizes the PWM duty cycle through the internal frequency jitter technology, and finally obtains the low EMI switching signal, which is output to the half-bridge drive circuit by the high-frequency PWM output module inside the single-chip microcomputer. The peripheral power supply of the single-chip microcomputer in this patent has two, of which VDD is a low-precision 3.3V, and VDDA uses a REF3033 reference chip circuit to output a high-precision 3.3V voltage for the analog signals of the whole system. The LED circuit contains two colors, red and green, which can automatically switch between constant voltage mode (CV) and constant current mode (CC) under normal working conditions, and the LED state is green long light. The LED is red in abnormal state.

[0029] The design of the parallel output DC power supply integrates a Buck-Boost regulator, a sampling module, and a control module, forming a high-efficiency and comprehensive power supply system. The rectifier bridge first converts the input AC power into DC power, providing a solid foundation for the subsequent circuit. The Buck-Boost regulator controls the MOS transistor through the PWM wave output by the STM32 microcontroller, achieving precise voltage reduction on the input voltage, so that the output voltage can remain stable within a adjustable range, adapting to various working conditions. The ADC sampling module adds resistors and operational amplifiers at the output end, achieving accurate sampling of the output voltage and converting it into a digital signal, providing a key feedback signal for closed-loop control of the system.

[0030] The circuit topology of the Buck-Boost regulator is shown in Figure 1 The figure shows the operation principle of two complementary conducting transistors. In each switching period, when Q1 is on, Q2 is off, and vice versa. In the Buck mode, the current change process of the inductor L1 is shown in Figure 2 .

[0031] In the design of Buck regulator, ignoring the impact of Schottky diode voltage drop and switch saturation voltage drop, the duty cycle D can be calculated:

[0032]

[0033] Suppose the input voltage size is V g , the output voltage size is V, the ripple current size is ∆i L , the Mosfet switch cycle is T s , the ripple current calculation formula of Buck circuit is:

[0034]

[0035] Suppose the switching frequency of the switching power supply is

[0036]

[0037] In order to ensure that the Buck regulator can work normally under the worst conditions, and taking into account the size of the power supply, the switching frequency is selected as 200KHz. Inductance determines the current ripple and the characteristics of the system, which is related to whether the system can work normally, has the functions of energy storage, harmonic current suppression and current waveform adjustment. Through calculation, the inductance value is 22uH, and four-strand winding design is adopted to avoid skin effect, thereby effectively reducing the heating problem of inductance. The capacity of the main capacitor determines the output ripple and the volume of the product, so that the smaller the output voltage ripple, the larger the capacity of the capacitor, but it will increase the volume of the product. Therefore, the main capacitor is selected to be 2 100uF electrolytic capacitor, and 2-4 4.7uF low ESR ceramic capacitors are connected in parallel, which aims to speed up the high frequency response speed of the power supply.

[0038] STL90N10F7 PowerFLAT-8 type N-channel MOSFET is selected as the model of MOS tube. This MOSFET has very small internal resistance, the maximum is only 7mΩ, the rated voltage is 100V, and the maximum current can reach 70A. This selection effectively reduces the power consumption of the transistor, further reduces the heating of MOSFET.

[0039] In order to realize the effect of parallel use of DC power supply, the power supply must be able to work in current source mode, so single current loop control is required. First, the transfer function of Buck topology is obtained by large signal analysis method:

[0040]

[0041] In the formula, L and C are output filter inductance and capacitance, R1 is the DC resistance of inductance, and R2 is the load resistance.

[0042] wherein , , , ,

[0043] In order to make the Buck converter work in constant current mode, a current inner loop compensator is needed, and the type II compensator is used in this design, and its transfer function is as follows:

[0044]

[0045] In Figure 3 , the closed-loop stability of the type II compensator is shown, and it can be seen that the crossover frequency basically meets the design requirements of this design, and the phase margin is close to 60 degrees.

[0046] In order to make the Buck converter work in constant voltage mode, a voltage outer loop compensator is also needed, and the type II compensator is also used, and the bandwidth of the voltage outer loop needs to be lower than that of the current inner loop to prevent loop oscillation, and the crossover frequency of the voltage outer loop is selected to be 1 / 4 of that of the current inner loop.

[0047] Figure 4 The circuit model of this design in parallel operation mode is shown, which is divided into master power supply and slave power supply. The master output power supply adopts voltage mode, and the slave output power supply works in current mode.

[0048] Other circuits of this patent include control chip (STM32G474RBT6), inductance current sampling, output voltage sampling, bridge driving chip (LM5109), etc. In order to overcome the electromagnetic interference (EMI) caused by semiconductor transistor MOSFET in high-frequency switching, the frequency jitter technology of G4 series chip is specially used, which starts from dispersing harmonic interference energy to solve the EMI problem, and through the new method of improving control technology to optimize performance, this method is first used in high-frequency digital circuit, and this patent refers this technology to switching power supply, which provides a new idea for suppressing electromagnetic interference of switching power supply.

Claims

1. A parallel output DC power supply, characterized in that... Interface circuit, Buck-Boost regulating circuit, sampling circuit and control system circuit; the Buck-Boost regulating circuit is connected with the sampling circuit and the control system circuit; the interface circuit comprises a power interface (101) and a control card interface (102); the Buck-Boost regulating circuit comprises a first on-board half-bridge drive circuit (2011), a second on-board half-bridge drive circuit (2012) and a Buck-Boost power topology (202); the sampling circuit comprises an input and output current sampling circuit (301), an inductance current sampling circuit (302), an OLED screen circuit (303) and an input and output voltage sampling circuit (304); the control system circuit comprises an MCU power management circuit (401), an MCU power filter capacitor circuit (402), a control chip circuit (403), an auxiliary power supply and a reference voltage source circuit (404), an LED circuit (405) and a crystal oscillator circuit (406).

2. The parallel output DC power supply according to claim 1, wherein The Buck-Boost power topology (202) comprises a first MOS tube, a second MOS tube, a third MOS tube and a fourth MOS tube; the drain of the first MOS tube is connected with the first on-board half-bridge drive circuit (2011), and the drain of the second MOS tube is connected with the second on-board half-bridge drive circuit (2012); the drain of the third MOS tube is connected with the second on-board half-bridge drive circuit (2012), and the drain of the fourth MOS tube is connected with the first on-board half-bridge drive circuit (2011).

3. The parallel output DC power supply according to claim 1, wherein The CC6920BSO current sensor is used as the input and output current sampling circuit (301) and the inductance current sampling circuit (302), and a first-order RC low-pass filter is arranged at the output end of the CC6920BSO current sensor to reduce the output noise.

4. The parallel output DC power supply according to claim 3, wherein The OPA2188 is used as the operational amplifier chip of the input and output voltage sampling circuit (304), and a differential proportional operation circuit composed of an operational amplifier resistor network realizes 25 times reduction processing on voltage.

5. The parallel output DC power supply according to claim 1, wherein The control system circuit adopts the STM32G474RBT6 single-chip microcomputer, first, the controller receives 5-way voltage and current signals from the sampling circuit, and quantizes the analog signals through the ADC circuit in the STM32G474RBT6 single-chip microcomputer.

6. The parallel output DC power supply according to claim 5, wherein It also comprises the peripheral power supply VDD and VDDA of the STM32G474RBT6 single-chip microcomputer, wherein VDD is a low-precision 3.3V, and VDDA adopts the REF3033 reference chip circuit to output a high-precision 3.3V voltage.

7. The parallel output DC power supply according to claim 5, wherein The LED circuit red LED and green LED.

Images