Large-current wide-voltage DC-DC conversion circuit

Abstract

The utility model discloses a large-current wide-voltage DC-DC conversion circuit, which comprises a first inductor, a second inductor, a first diode, a first MOS (Metal Oxide Semiconductor) tube and a second MOS tube, a buck-boost main power circuit is formed by a first inductor, a second inductor, a first MOS tube, a second MOS tube and a first diode together, the first inductor and the second inductor play a role in energy storage, and a larger range of input voltage can be adapted by controlling the duty ratio of the first MOS tube and the second MOS tube; the first inductor, the second inductor, the second MOS tube and the second MOS tube are connected in parallel and staggered to form two groups of BUCK-BOOST circuits, and adaptive input current is also two times of single-path input current, so that the high-current input characteristic is achieved.

Description

Technical Field

[0001] The utility model relates to the field of conversion circuits, in particular to a large-current and wide-voltage DC-DC conversion circuit. Background Art

[0002] In the production process of power supply products, in order to ensure the quality of the products, power supply products must undergo long-term load aging tests in the later stage of production, so that the products are in a high-temperature full-load state for a long time to simulate the customer's use environment, so that the problematic products fail prematurely, exposing the problems of product design, production and materials. Most factories use resistors as the load of the power supply. During the aging test, the resistors will convert electrical energy into heat energy for consumption. The aging test converts electrical energy into heat energy consumption in vain, which increases the power consumption cost and the ambient temperature, and also poses a certain fire hazard. With the increase of domestic production capacity, various power supplies consume more and more electricity in aging tests, which has become an unnecessary cost burden for many factories. Therefore, it is necessary to realize the conversion and reuse of electrical energy from a technical perspective.

[0003] The easiest way to convert and utilize the output power of power products is energy feedback, that is, to use an additional DC-DC (direct current to direct current) power module as a feedback load to convert the output power of power products into a fixed voltage, and then connect it to the grid through a DC-AC (direct current to alternating current) power module to realize the feedback of power. Since the DC-AC power supply is a non-isolated module, the DC-DC power module must achieve input and output isolation; due to the wide variety of power products, the voltage distribution range is extremely wide, and the current range is also relatively large. At present, the circuits commonly used for feedback loads are mainly BOOST, BUCK-BOOST and SEPIC circuits. Since the maximum boost ratio of the BOOST circuit can only be about 10 times, it is mainly used for low voltage and high current. The BUCK-BOOST and SEPIC circuits also have the function of voltage boost and buck, and the circuit itself has a wide voltage range application, but the switching element voltage stress of the circuit is high and cannot withstand large input current. At present, BUCK-BOOST and SEPIC circuits use a common ground design for BUCK-BOOST and SEPIC driving and post-stage isolation PUSH_PULL circuit driving to simplify the driving circuit, so parallel connection is impossible, and it is difficult to take into account wide voltage and large current at the same time. Therefore, there should be a circuit with a more reasonable layout to solve the above-mentioned technical problems. Utility Model Content

[0004] Aiming at the technical problem that the existing conversion circuit cannot take into account the characteristics of wide voltage and large current at the same time, the utility model provides a solution.

[0005] To achieve the above object, the present utility model provides a high-current wide-voltage DC-DC conversion circuit, which includes a first inductor, a second inductor, a first diode, a first MOS transistor, and a second MOS transistor. Among them, a first end formed after the first inductor and the second inductor are interleaved and paralleled is coupled to an input voltage, and a second end is correspondingly connected to a first input end and a second input end of the first diode. An output end of the first diode outputs a rectified voltage and is coupled to an isolation boost circuit; a drain of the first MOS transistor is coupled to a first connection point between the first inductor and the first input end, a gate is coupled to DRIVA, and a source is coupled to GND; a drain of the second MOS transistor is coupled to a second connection point between the second inductor and the second input end, a gate is coupled to DRIVB, and a source is coupled to the GND.

[0006] As an improved solution of the present application, it further includes a first capacitor. A positive electrode of the first capacitor is coupled to a first end formed after the first inductor and the second inductor are paralleled, and a negative electrode is coupled to the GND.

[0007] As an improved solution of the present application, it further includes a second capacitor. A negative electrode of the second capacitor is coupled to a first end formed after the first inductor and the second inductor are paralleled, and the other end is coupled to an output end of the first inductor.

[0008] As an improved solution of the present application, the isolation boost circuit includes a third MOS transistor, a fourth MOS transistor, and a transformer. Among them, a second output voltage is coupled between a first primary winding and a second primary winding of the transformer. Opposite ends of the first primary winding and the second primary winding are respectively connected to drains of the third MOS transistor and the fourth MOS transistor. Gates of the third MOS transistor and the fourth MOS transistor are correspondingly connected to Push and Pull to form a push-pull unit. Sources of the third MOS transistor and the fourth MOS transistor are commonly connected to VIN.

[0009] As an improved solution of the present application, an output end of the transformer includes a first output winding and a second output winding. A first lead of the first output winding outputs a first expected voltage after passing through a first rectification and filtering unit, and a second lead is coupled to PGND1; a first lead of the second output winding outputs a second expected voltage after passing through a second rectification unit, and a first lead is coupled to PGND2.

[0010] As an improved solution of the present application, a third capacitor is further connected between a first lead and a second lead of the first output winding; a fourth capacitor is further connected between a first lead and a second lead of the second output winding.

[0011] As an improved solution of the present application, the powers of the first output voltage and the second output voltage are both 400V.

[0012] The beneficial effects of the present utility model are as follows: Compared with the prior art, a high-current wide-voltage DC-DC conversion circuit provided by the present utility model includes a first inductor, a second inductor, a first diode, a first MOS transistor, and a second MOS transistor. Among them, a first end formed by the interleaved parallel connection of the first inductor and the second inductor is coupled to an input voltage, and a second end is correspondingly connected to a first input end and a second input end of the first diode. The output end of the first diode outputs a rectified voltage and is coupled to an isolation boost circuit; the drain of the first MOS transistor is coupled to a first connection point between the first inductor and the first input end, the gate is coupled to DRIVA, and the source is coupled to GND; the drain of the second MOS transistor is coupled to a second connection point between the second inductor and the second input end, the gate is coupled to DRIVB, and the source is coupled to GND; a buck-boost main power circuit is jointly formed by the first inductor, the second inductor, the first MOS transistor, the second MOS transistor, and the first diode. The first inductor and the second inductor play a role in energy storage, and a larger range of input voltages can be adapted by controlling the duty cycles of the first MOS transistor and the second MOS transistor; due to the parallel interleaved design of the first inductor, the second inductor, the second MOS transistor, and the second MOS transistor, which constitutes two sets of BUCK-BOOST circuits, the input current that can be adapted is also twice that of a single-path input current. Therefore, it has the characteristics of high-current input. Description of the Drawings

[0013] Figure 1 is the circuit diagram of the present utility model;

[0014] Figure 2 is the timing diagram of the first MOS transistor and the second MOS transistor of the present utility model;

[0015] Figure 3 is the circuit state diagram of the present utility model at time t1;

[0016] Figure 4 is the circuit state diagram of the present utility model at time t2;

[0017] Figure 5 is the circuit state diagram of the present utility model at time t3;

[0018] Figure 6 is the circuit state diagram of the present utility model at time t4.

[0019] The main component symbol descriptions are as follows:

[0020] L1, first inductor; L2, second inductor; Q1, first MOS tube; Q2, second MOS tube: Q3, third MOS tube; Q4, fourth MOS tube; A, first primary winding; B, second primary winding; C, first output winding; D, second output winding; D1, first diode; D2, second diode; D3, third diode; D4, fourth diode; D5, fifth diode; D6, sixth diode; D7, seventh diode; D8, eighth diode; D9, ninth diode; VIN, input voltage; VOUT, output voltage. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with the accompanying drawings.

[0022] In the following description, the example details are given to provide a deeper understanding of the utility model. Obviously, the described embodiments are only a part of the embodiments of the utility model, rather than all the embodiments. It should be understood that the specific embodiments are only used to explain the utility model, and are not used to limit the utility model.

[0023] It should be understood that when the terms "include" and / or "comprises" are used in this specification, they indicate the existence of the stated features, integers, steps, operations, elements or components, but do not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components or combinations thereof.

[0024] In view of the technical problem that the existing conversion circuit cannot take into account the characteristics of wide voltage and large current, the present application provides a high current and wide voltage DC-DC conversion circuit. Figures 1 to 6 , comprising a first inductor L1, a second inductor L2, a first diode D1, a first MOS transistor Q1 and a second MOS transistor Q2, wherein a first end formed by the first inductor L1 and the second inductor L2 being alternately connected in parallel is coupled to an output voltage VOUT, and a second end is correspondingly connected to a first input end and a second input end of the first diode D1, and an input end of the first diode D1 outputs a rectified voltage and is coupled to an isolation boost circuit; a drain of the first MOS transistor Q1 is coupled to a first connection point between the first inductor L1 and the first input end, a gate is coupled to DRIVA, and a source is coupled to GND; a drain of the second MOS transistor Q2 is coupled to a second connection point between the second inductor L2 and the second input end, a gate is coupled to DRIVB, and a source is coupled to GND;

[0025] In the above solution, the first inductor L1 and the second inductor L2 are buck-boost power inductors, which play a role in energy storage; the first MOS transistor Q1 and the second MOS transistor Q2 play a switching role and operate alternately, so that the first inductor L1 and the second inductor L2 store and release energy to achieve voltage conversion; the first diode D1 mainly plays a rectifying role, rectifying the back electromotive force formed by turning off the first inductor L1 and the second inductor L2 by the first MOS transistor Q1 and the second MOS transistor Q2.

[0026] To make the circuit work more stably, it further includes a first capacitor and a second capacitor. The positive electrode of the first capacitor is coupled to the first end formed by the parallel connection of the first inductor L1 and the second inductor L2, and the negative electrode is coupled to GND; the negative electrode of the second capacitor is coupled to the first end where the positive electrode of the first capacitor is coupled to the parallel connection of the first inductor L1 and the second inductor L2, and the other end is coupled to the output end of the first inductor L1; the first capacitor mainly filters the input voltage VIN, and the second capacitor is a rectifying and filtering capacitor. The voltage rectified by the first diode D1 can form a stable DC voltage after being filtered by the second capacitor.

[0027] It is not difficult to understand that the calculation formula for the output voltage VOUT of this circuit is: VOUT = VIN / (1 - D) - VIN, (D is the conduction duty cycle of the first MOS transistor Q1 and the second MOS transistor Q2); when the output voltage VOUT is fixed and the input voltage VIN is lower than the output voltage VOUT, the conduction duty cycle of the first MOS transistor Q1 and the second MOS transistor Q2 is greater than 50%; when the input voltage VIN is higher than the output voltage VOUT, the conduction duty cycle of the first MOS transistor Q1 and the second MOS transistor Q2 is less than 50%; by the above mechanism, therefore, to keep the output voltage VOUT fixed, the input VIN can vary within a large range, realizing wide-voltage input. This circuit constructs a parallel interleaved input BUCK-BOOST circuit with the above components, so the input current is twice that of a single-channel input current, and large-current input can be achieved. In the two groups of circuits, the first MOS transistors Q1 and Q2 switch alternately, and the switching ripple of the input voltage VIN is twice the switching frequency of the first MOS transistor Q1 or the second MOS transistor Q2, which can effectively reduce the input ripple current.

[0028] To further elaborate on the solution of this application, the following is an explanation in combination with the timing waveforms of the first MOS transistor Q1 and the second MOS transistor Q2: Please refer to Figure 2 , the first MOS transistor Q1 and the second MOS transistor Q2 work to form a driving waveform timing. Four timings t1, t2, t3, and t4 are intercepted and combined with the attached Figures 3 - 6 for explanation:

[0029] Timing t1, please refer to the attached Figure 3, the first MOS transistor Q1 is turned on, and the current flows from the input terminal VIN, through the first inductor L1, and then back to the negative terminal GND of the input voltage VIN through the first MOS transistor Q1. At this time, the VIN current stores energy in the first inductor L1, and the induced electromotive force of the first inductor L1 is positive on the left and negative on the right.

[0030] For the t2 timing, please refer to the appendix Figure 4 , the first MOS transistor Q1 is turned off, and the energy storage current of the first inductor L1 is interrupted. The first inductor forms a back electromotive force with negative on the left and positive on the right, which passes through the first input pin (corresponding to Figure 4 the 3rd pin of the second diode in Figure 4 ), and the output pin (corresponding to

[0031] For the T3 timing, please refer to the appendix Figure 5 , the second MOS transistor Q2 is turned on, and the current flows from the input voltage VIN, through the second inductor L2, and then back to the negative terminal GND of the input voltage VIN through the second MOS transistor Q2. At this time, the input voltage VIN current stores energy in the second inductor L2, and the induced electromotive force of the second L2 is positive on the left and negative on the right.

[0032] For the T4 timing, please refer to the appendix Figure 6 , the second MOS transistor Q2 is turned on, and the current flows from the input voltage VIN, through the second inductor L2, and then back to the negative terminal GND of the input voltage VIN through the second MOS transistor Q2. At this time, the input voltage VIN current stores energy in the second inductor L2, and the induced electromotive force of the second L2 is positive on the left and negative on the right.

[0033] It is not difficult to understand that the isolated boost circuit is responsible for boosting the output voltage VOUT to the voltage required for the inverter to be connected to the grid or the load. That is to say, it can be understood that the corresponding expected voltage is output through the isolated boost circuit for use. In this embodiment, the isolated boost circuit includes a third MOS transistor Q3, a fourth MOS transistor Q4, and a transformer. Among them, the second output voltage VOUT is coupled between the first primary winding A and the second primary winding B of the transformer. The opposite ends of the first primary winding and the second primary winding are respectively connected to the drains of the third MOS transistor Q3 and the fourth MOS transistor Q4. The gates of the third MOS transistor Q3 and the fourth MOS transistor Q4 are correspondingly connected to Push and Pull to form a push-pull unit. The sources of the third MOS transistor Q3 and the fourth MOS transistor Q4 are commonly connected to VIN. In specific operation, when the third MOS transistor Q3 and the fourth MOS transistor Q4 are alternately turned on, alternating currents with equal magnitudes and opposite directions are generated in the first primary winding A and the second primary winding B, so that an alternating magnetic field is generated in the magnetic core of the side transformer, enabling the output terminal of the transformer to generate a voltage with an expected value for use;

[0034] In a further solution, the output end of the transformer includes a first output winding C and a second output winding D. The first terminal of the first output winding C outputs a first expected voltage after passing through the first rectification and filtering unit, and the second terminal is coupled to PGND1; the first terminal of the second output winding D outputs a second expected voltage after passing through the second rectification unit, and the first terminal is coupled to PGND2; the first rectification unit is composed of a second diode D2, a third diode D3, a fourth diode D4, and a fifth diode D5. After rectification and filtering are achieved through the above-mentioned multiple groups of diodes, the first expected voltage can be output; similarly, the second rectification unit is composed of a sixth diode D6, a seventh diode D7, an eighth diode D8, and a ninth diode D9. After rectification and filtering are achieved through the above-mentioned multiple groups of diodes, the second expected voltage can be output. Taking the first expected voltage and the second expected voltage both being 400V as an example for further illustration, in practical applications, the first expected voltage and the second expected voltage are used in series and can be connected to a three-phase 800V bus inverter or load. Through the series and parallel connection methods of the first expected voltage and the second expected voltage, a larger voltage conversion ratio can be achieved, which is suitable for a wider output voltage VOUT environment.

[0035] In order to obtain a more stable voltage, in this embodiment, a third capacitor is also connected between the first terminal and the second terminal of the first output winding C; a fourth capacitor is also connected between the first terminal and the second terminal of the second output winding D; the third capacitor and the fourth capacitor respectively rectify and filter the first expected voltage and the second expected voltage, making the voltage parameters more stable.

[0036] The advantages of the present utility model are as follows:

[0037] A buck-boost main power circuit is jointly formed by the first inductor, the second inductor, the first MOS transistor, the second MOS transistor, and the first diode. The first inductor and the second inductor play a role in energy storage, and by controlling the duty cycles of the first MOS transistor and the second MOS transistor, a wider range of input voltages can be adapted; due to the parallel interleaved design of the first inductor, the second inductor, the second MOS transistor, and the second MOS transistor, which constitutes two groups of BUCK-BOOST circuits, the input current that can be adapted is also twice that of a single-path input current. Therefore, it has the characteristic of large current input.

[0038] The above only discloses several specific embodiments of the present utility model, but the present utility model is not limited thereto. Any changes that can be thought of by those skilled in the art should fall within the protection scope of the present utility model.

Claims

1. A high-current wide-voltage DC-DC conversion circuit, characterized in that, It includes a first inductor, a second inductor, a first diode, a first MOS transistor and a second MOS transistor. Among them, the first end formed after the first inductor and the second inductor are interleaved and paralleled is coupled to the input voltage, and the second end is correspondingly connected to the first input terminal and the second input terminal of the first diode. The output terminal of the first diode outputs a rectified voltage and is coupled to an isolation boost circuit; the drain of the first MOS transistor is coupled to the first connection point between the first inductor and the first input terminal, the gate is coupled to DRIVA, and the source is coupled to GND; the drain of the second MOS transistor is coupled to the second connection point between the second inductor and the second input terminal, the gate is coupled to DRIVB, and the source is coupled to the GND.

2. The high-current wide-voltage DC-DC conversion circuit according to claim 1, wherein It further includes a first capacitor. The positive electrode of the first capacitor is coupled to the first end formed after the first inductor and the second inductor are paralleled, and the negative electrode is coupled to the GND.

3. The high-current wide-voltage DC-DC conversion circuit according to claim 2, characterized in that It further includes a second capacitor. The negative electrode of the second capacitor is coupled to the first end formed after the first inductor and the second inductor are paralleled where the positive electrode of the first capacitor is coupled, and the other end is coupled to the output terminal of the first inductor.

4. The high-current wide-voltage DC-DC conversion circuit according to any one of claims 1-3, characterized in that, The isolation boost circuit includes a third MOS transistor, a fourth MOS transistor and a transformer. Among them, a second output voltage is coupled between the first primary winding and the second primary winding of the transformer. The opposite ends of the first primary winding and the second primary winding are respectively connected to the drains of the third MOS transistor and the fourth MOS transistor. The gates of the third MOS transistor and the fourth MOS transistor are correspondingly connected to Push and Pull to form a push-pull unit. The sources of the third MOS transistor and the fourth MOS transistor are commonly connected to VIN.

5. The high-current wide-voltage DC-DC conversion circuit according to claim 4, characterized in that, The output terminal of the transformer includes a first output winding and a second output winding. The first pin of the first output winding outputs a first expected voltage after passing through a first rectifying and filtering unit, and the second pin is coupled to PGND1; the first pin of the second output winding outputs a second expected voltage after passing through a second rectifying unit, and the first pin is coupled to PGND2.

6. The high-current wide-voltage DC-DC conversion circuit according to claim 5, wherein A third capacitor is also connected between the first pin and the second pin of the first output winding; a fourth capacitor is also connected between the first pin and the second pin of the second output winding.

7. The high-current wide-voltage DC-DC conversion circuit according to claim 6, wherein The power of both the first expected voltage and the second expected voltage is 400V.

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