Constant current power supply device adaptive to optimal efficiency

Abstract

The utility model relates to a self-adaptive constant-current power supply device with optimal efficiency, and belongs to the technical field of power supply control in the power electronic technology. According to the technical scheme, an output current sampling unit (8) is respectively connected with a control unit (2) and a follow current unit (3); the output end of the output current sampling unit (8) is connected with a constant current output control circuit; the constant current output control circuit comprises a follow current inductance unit (5), a filter capacitor unit (6) and a current control unit (7) which are connected in sequence, the control unit (2) is connected with the Mos tube driving unit (4), and the Mos tube driving unit (4) is connected with the current control unit (7). The beneficial effects of the utility model are that through the closed-loop control of the switching frequency, the input current can be the lowest under the condition that the output is not changed, thereby realizing the maximum output efficiency. And digital control is adopted, so that the rapidity and stability of efficiency optimization are ensured.

Description

Technical Field

[0001] The utility model relates to a constant current power supply device with adaptive optimal efficiency, belonging to the technical field of power supply control in power electronics technology. Background Art

[0002] With global energy shortages, energy conservation, loss reduction, and optimized energy mix are crucial. Power electronic converters, as the critical bridge between energy production and use, play a particularly prominent role. With the miniaturization and integration of power electronic components, the performance and functional requirements for power electronic converters are constantly increasing. Power electronic converters, in particular, deserve the attention of technical personnel in improving energy efficiency.

[0003] The development of high-efficiency power conversion technology typically involves a comprehensive consideration of power device matching, circuit structure optimization, and control method improvements. Appropriate power devices are selected based on switching speed, on-resistance, withstand voltage rating, loss characteristics, and operating temperature. Soft switching technology is utilized to reduce switching device losses during the conversion process. Improved control methods enable precise power control and achieve optimal efficiency. Achieving maximum output efficiency and ensuring rapid and stable efficiency optimization remain key technical challenges in this field. Utility Model Content

[0004] The purpose of the utility model is to provide a constant current power supply device with adaptive optimal efficiency, which can achieve the optimal operating efficiency by adjusting the switching frequency according to the inverse relationship between the operating efficiency and the switching frequency, and thus achieve the optimal operating efficiency under the same working conditions.

[0005] The technical solution of the utility model is: an adaptive optimal efficiency constant current power supply device, comprising an input current sampling unit, a control unit, a freewheeling unit, a MOS tube driving unit, a constant current output control circuit, an output current sampling unit, an input end and an output end, wherein the input end and the output end are respectively connected to the input current sampling unit and the output current sampling unit, the input current sampling unit is respectively connected to the control unit and the freewheeling unit, and the output current sampling unit is respectively connected to the control unit and the freewheeling unit; the constant current output control circuit is connected to the output end of the output current sampling unit; the constant current output control circuit comprises a freewheeling inductor unit, a filter capacitor unit and a current control unit connected in sequence, the control unit is connected to the MOS tube driving unit, and the MOS tube driving unit is connected to the current control unit.

[0006] The input current sampling unit and the output current sampling unit have the same structure, both consisting of a differential amplifier (subtractor) connected to a voltage stabilization protection circuit.

[0007] The freewheeling inductor unit, the filter capacitor unit and the current control unit are composed of an emitter-follower circuit, a current comparison circuit, a class B complementary power amplifier circuit and a post-stage MOS tube current control circuit which are connected in series in sequence.

[0008] According to the inverse parabolic relationship between the operating efficiency and switching frequency of a synchronous Buck converter, the utility model seeks the optimum efficiency point through self-tuning of the switching frequency; using the switching frequency of the MOSFET as a reference, the input current value is measured, and the driving frequency is adjusted through the disturbance observation method to find the minimum input current point and achieve the optimal operating frequency.

[0009] This utility model addresses the problem of reduced output efficiency caused by a fixed switching frequency. Based on the mathematical relationship between switching frequency and output efficiency, it designs an online adaptive adjustment of the MOS tube drive frequency to minimize input current and maximize output efficiency. This optimal efficiency self-tracking method, based on the Buck circuit, seeks the efficiency optimum through self-tuning of the switching frequency, achieving optimal operating efficiency under the same operating conditions.

[0010] The beneficial effect of the present invention is that, through closed-loop control of the switching frequency, the input current can be minimized while the output remains unchanged, thereby achieving maximum output efficiency. The use of digital control ensures the rapidity and stability of efficiency optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a block diagram of the optimal efficiency tracking control of an embodiment of the present utility model;

[0012] Figure 2 This is a frequency-efficiency-current relationship curve of the Buck converter of the embodiment of the present utility model;

[0013] Figure 3 This is the optimal efficiency tracking logic diagram of the embodiment of the utility model;

[0014] Figure 4 This is a circuit diagram of a Buck converter according to an embodiment of the present utility model;

[0015] Figure 5 This is a constant current output control circuit diagram of an embodiment of the utility model;

[0016] Figure 6 This is a circuit diagram of an input current sampling unit according to an embodiment of the present utility model;

[0017] Figure 7 This is a circuit diagram of a power module based on Buck circuit optimal efficiency tracking control according to an embodiment of the present utility model;

[0018] In the figure: input current sampling unit 1, control unit 2, freewheeling unit 3, MOS tube driving unit 4, freewheeling inductor unit 5, filter capacitor unit 6, current control unit 7, output current sampling unit 8, input terminal 9, output terminal 10, GND terminal 11, emitter follower circuit 21, current comparison circuit 22, class B complementary power amplifier circuit 23, post-stage MOS tube current control circuit 24, differential amplifier 25, voltage stabilization protection circuit 26. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to examples with reference to the accompanying drawings.

[0020] A constant current power supply device with adaptive optimal efficiency comprises an input current sampling unit 1, a control unit 2, a freewheeling unit 3, a MOSFET drive unit 4, a constant current output control circuit, an output current sampling unit 8, an input end 9 and an output end 10, wherein the input end 9 and the output end 10 are respectively connected to the input current sampling unit 1 and the output current sampling unit 8, the input current sampling unit 1 is respectively connected to the control unit 2 and the freewheeling unit 3, and the output current sampling unit 8 is respectively connected to the control unit 2 and the freewheeling unit 3; the output end of the output current sampling unit 8 is connected to the constant current output control circuit; the constant current output control circuit comprises a freewheeling inductor unit 5, a filter capacitor unit 6 and a current control unit 7 connected in sequence, the control unit 2 is connected to the MOSFET drive unit 4, and the MOSFET drive unit 4 is connected to the current control unit 7.

[0021] The input current sampling unit 1 and the output current sampling unit 8 have the same structure, and both are composed of a differential amplifier (subtractor) 25 connected to a voltage stabilization protection circuit 26 .

[0022] The freewheeling inductor unit 5, the filter capacitor unit 6 and the current control unit 7 are composed of an emitter-follower circuit 21, a current comparison circuit 22, a class-B complementary power amplifier circuit 23 and a post-stage MOS tube current control circuit 24 connected in series in sequence.

[0023] According to the inverse parabolic relationship between the operating efficiency and switching frequency of a synchronous Buck converter, the utility model seeks the optimum efficiency point through self-tuning of the switching frequency; using the switching frequency of the MOSFET as a reference, the input current value is measured, and the driving frequency is adjusted through the disturbance observation method to find the minimum input current point and achieve the optimal operating frequency.

[0024] Working steps;

[0025] ① Given an initial switching frequency for the converter, the corresponding PWM wave controls the on / off switching of the MOS tube. After a certain period, the input current value is sampled. When the output current is detected to be stable, the switching frequency is adjusted, such as adding a constant A0. Then, the next period is entered for iteration, so that the current frequency is the frequency at the previous moment plus the constant A0.

[0026] ② Use the current frequency as the switching frequency to control the on and off of the MOS tube. After a certain period, sample the input current value at this time and compare the two input currents.

[0027] ③ According to the difference between the two input currents, the switching frequency is adjusted to minimize the input current and form a control closed loop.

[0028] In the embodiments, refer to the attached Figure 1 、 3 , the optimal efficiency tracking control block diagram includes: input current sampling unit, control unit, MOS tube driving unit, freewheeling unit, output current sampling unit, freewheeling inductor unit, filter capacitor unit and current control unit.

[0029] Process: First, set the initial switching frequency f = f0; if the output current is unstable, reset the initial switching frequency; if the output current is stable, ADC samples the input current I0;

[0030] If f is not less than f0, adjust the switching frequency f=f+A0, and the ADC samples the input current I1. If I1 is greater than I0, adjust the switching frequency f=f-A0; if I1 is not greater than I0, continue to adjust the switching frequency f=f+A0 until I1 is greater than I0;

[0031] If f is less than f0, directly adjust the switching frequency f=f-A0;

[0032] The ADC samples the input current I2. If I2 is less than I0, the switching frequency f=f-A0 is adjusted.

[0033] If I2 is not less than I0, the switching frequency f remains unchanged.

[0034] Refer to the attached Figure 4 Buck circuit.

[0035] Figure 6 Sampling input resistance R in The voltage across the input resistor is subtracted via differential amplifier (subtractor) 25. Voltage regulator protection circuit 26 filters and limits the peak sampling rate to protect the controller's ADC peripherals. The controller detects the input current and uses the perturbation-observation method to adjust the switching frequency of MOS transistors VT1 and VT2, achieving adaptive switching frequency output and increasing efficiency.

[0036] In this embodiment, Figure 7 Design a step-down DC-DC power supply module with high load current output. The design dimensions are 50mm*50mm*25mm. Parameter requirements include a 48V input voltage, a continuously adjustable 20A output current, and adaptive output voltage. All comparators use LM324 operational amplifiers, and MOSFETs VT1 and VT2 use CSD19531Q5A. The power supply module was designed and tested using the control method and circuit design described above. Ultimately, adaptive switching frequency setting and precise and stable output current control were achieved, resulting in lower overall power consumption and higher efficiency. This method has promising application prospects and good economic benefits, making it highly worthy of widespread adoption.

Claims

1. A constant current power supply device with adaptive optimal efficiency, characterized by: The invention comprises an input current sampling unit (1), a control unit (2), a freewheeling unit (3), a MOSFET drive unit (4), a constant current output control circuit, an output current sampling unit (8), an input end (9) and an output end (10), wherein the input end (9) and the output end (10) are respectively connected to the input current sampling unit (1) and the output current sampling unit (8), the input current sampling unit (1) is respectively connected to the control unit (2) and the freewheeling unit (3), and the output current sampling unit (8) is respectively connected to the control unit (2) and the freewheeling unit (3); the output end of the output current sampling unit (8) is connected to the constant current output control circuit; the constant current output control circuit comprises a freewheeling inductor unit (5), a filter capacitor unit (6) and a current control unit (7) connected in sequence, the control unit (2) is connected to the MOSFET drive unit (4), and the MOSFET drive unit (4) is connected to the current control unit (7).

2. The adaptive optimal efficiency constant current power supply device according to claim 1, characterized in that: The input current sampling unit (1) and the output current sampling unit (8) have the same structure, and both consist of a differential amplifier (25) connected to a voltage stabilization protection circuit (26).

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