CN204068702U - A Non-isolated High Gain DC/DC Converter - Google Patents

Abstract

A kind of non-isolation type high-gain DC/DC converter, comprises inductance L ₁, L ₂, power switch S ₁, S ₂, diode D ₁, D ₂, D ₃, D ₄, electric capacity C ₁, C ₂, C ₃, C ₄; First inductance L ₁one end, the second inductance L ₂one end meet input power u simultaneously _inpositive pole, the first inductance L ₁the other end, the second inductance L ₂the other end meet the first power switch S respectively ₁drain electrode, the second power switch S ₂drain electrode; First power switch S ₁source electrode, the second power switch S ₂source electrode meet input power u _innegative pole; First power switch S ₁, the second power switch S ₂grid connect respective controller respectively.A kind of non-isolation type high-gain DC/DC of the utility model converter, compared with existing high-gain boost converter, not containing transformer and coupling inductance, EMI characteristic is good, and circuit topology is simple, Control System Design and to realize difficulty all lower.

Description

A Non-isolated High Gain DC/DC Converter

technical field

The utility model relates to a DC-DC converter, in particular to a non-isolated high-gain DC/DC converter.

Background technique

In the prior art, the basic two-phase step-up (Boost) interleaved parallel converter, see Figure 1 in the accompanying drawings, includes two inductors L ₁ , L ₂ , two power switch tubes S ₁ , S ₂ , two output diodes D ₁ and D ₂ . Among them, the input terminal of the first inductor _L1 and the input terminal of the second inductor _L2 are connected to the anode of the input power supply V _in together, the output terminal V _in is connected to the anode of the first output diode _D1 , and the first diode D The cathode of ₁ and the cathode of the second diode D ₂ are connected to the positive pole of the converter output terminal V _OUT ; the drain of the first power switch S ₁ is connected between the first inductor L ₁ and the anode of the first diode D ₁ , The source of the first power switch _S1 is connected to the negative pole of the converter; the output terminal of the second inductor _L2 is connected to the anode of the second output diode _D2 , between the second inductor _L2 and the anode of the second diode _D2 Indirectly connected to the drain of the second power switch _S2 , the second power switch source _S2 is connected to the negative pole of the converter. The input and output voltage gain of this converter is small, and the voltage stresses of the power switch tubes S ₁ and S ₂ and the diodes D ₁ and D ₂ are all output voltages, so the voltage stress is high and the loss is large. And in some occasions where the input and output voltage difference is large, its input and output boost capability is difficult to meet the requirements, such as: grid-connected photovoltaic cells, X-ray machine power supply, etc.

At present, there are usually three ways to achieve high-gain conversion: ① With the help of a transformer: add a high-frequency transformer in the middle of the original DC-DC converter, and achieve the purpose of high-gain boost by changing the transformer ratio, but the energy of this solution The conversion process is complicated, and the energy conversion efficiency of the whole system is low. ②Using switched capacitors: This solution requires many switching devices, and the control and drive circuits are complicated to implement. ③Use of coupled inductance: The use of coupled inductance often causes excessive voltage stress of switching devices, and may cause electromagnetic interference and other effects.

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, in order to solve the problems of insufficient boosting capacity, low working efficiency and low power density in the existing boost converter, the utility model provides a non-isolated DC-DC converter with high gain capability device.

The technical scheme that the utility model takes is:

A non-isolated high-gain DC/DC converter, including inductors L ₁ , L ₂ , power switches S ₁ , S ₂ , diodes D ₁ , D ₂ , D ₃ , D ₄ , capacitors C ₁ , C ₂ , C ₃ , C ₄ ; one end of the first inductance L ₁ and one end of the second inductance L ₂ are simultaneously connected to the positive pole of the input power supply u _in , the other end of the first inductance L ₁ and the other end of the second inductance L ₂ are respectively connected to the first power switch The drain of _S1 and the drain of the second power switch _S2 ; the source of the first power switch _S1 and the source of the second power switch _S2 are connected to the negative pole of the input power supply u _in ; the first power switch _S1 , The gates of the second power switch _S2 are respectively connected to their respective controllers; diodes _D1 and _D2 are connected in series, and diodes _D3 and _D4 are connected in series, wherein the cathode of diode _D1 is connected to the anode of diode _D2 , and the diode _D3 The cathode is connected to the anode of the diode _D4 ; capacitors C ₁ and C ₂ are connected in series, and capacitors C ₃ and C ₄ are connected in series, wherein capacitors C ₁ and C ₃ are located at the top, and capacitors C ₂ and C ₄ are located at the bottom; the upper end of capacitor C ₁ is connected to The junction of diodes D ₁ and D ₂ is connected in series, the upper end of capacitor C ₂ is connected with the junction of diodes D ₃ and D ₄ in series; the upper end of capacitor C ₃ is connected with the cathode of diode D ₂ and used as the output terminal u _o The positive pole, the lower end of the capacitor _C4 is connected to the anode of the diode _D3 , and is used as the negative pole of the output terminal _uo ; at the same time, the other end of the first inductor _L1 is also connected to the anode of the diode _D1 and the junction of the capacitors _C3 and _{C4 in} series point, the other end of the second inductance L ₂ is also connected to the junction of the capacitors C ₁ and C ₂ connected in series; the cathode of the diode D ₄ is connected to the negative pole of the input power supply u _in .

The control method of the first power switch S ₁ and the second power switch S ₂ is that the power switches of each phase adopt an interleaved control strategy, that is, the difference between the driving phases of each phase switch is 180 ^° .

Compared with the prior art, the utility model is a non-isolated high-gain DC/DC converter, which has the following beneficial effects:

1) The utility model utilizes four diodes and four capacitors to form a high-gain boost network, realizing four times the input and output voltage gain of the basic Boost converter.

2) The voltage stress of the switching device in the circuit is low, and the voltage stress of the switching tube is only a quarter of that of the basic Boost converter.

3) Compared with the existing high-gain boost converter, it does not contain transformers and coupled inductors, has good EMI characteristics, simple circuit topology, and low difficulty in control system design and implementation.

Description of drawings

FIG. 1 is a circuit schematic diagram of a two-phase boost (Boost) interleaved parallel converter described in the background art.

Fig. 2 is a schematic circuit diagram of the utility model.

Detailed ways

As shown in Figure 2, a non-isolated high-gain DC/DC converter is composed of a low-voltage input power supply and a DC/DC boost circuit; the converter includes two inductors L ₁ and L ₂ , and two power switches S ₁ , S ₂ , four diodes D ₁ , D ₂ , D ₃ , D ₄ and four capacitors C ₁ , C ₂ , C ₃ , C ₄ .

One end of the first inductance _L1 and one end of the second inductance _L2 are simultaneously connected to the positive pole of the input power u _in , and the other end of the first inductance _L1 and the other end of the second inductance _L2 are respectively connected to the drain of the first power switch _S1 , the drain of the second power switch _S2 ; the source of the first power switch _S1 and the source of the second power switch _S2 are connected to the negative pole of the input power supply u _in ; the gates of the two power switches _S1 and _S2 connected to their respective controllers.

Diodes D ₁ and D ₂ are connected in series, D ₃ and D ₄ are connected in series, wherein the cathode of diode D ₁ is connected to the anode of diode D ₂ , the cathode of diode D ₃ is connected to the anode of diode D ₄ ; capacitors C ₁ and C ₂ are connected in series, C ₃ and C ₄ are connected in series, where capacitors C ₁ and C ₃ are located at the top, and capacitors C ₂ and C ₄ are located at the bottom; the upper end of capacitor C ₁ is connected to the junction of diodes D ₁ and D ₂ in series, and the upper end of capacitor C ₂ is connected to The junctions of diodes D ₃ and D ₄ are connected in series; the upper end of capacitor C ₃ is connected to the cathode of diode D ₂ and serves as the anode of the output terminal u _o , and the lower end of capacitor C ₄ is connected to the anode of diode D ₃ and serves as the output Negative pole of terminal u _o ;

At the same time, the other end of the first inductance L ₁ is also connected to the anode of the diode D ₁ and the junction of the capacitors C ₃ and C ₄ in series, and the other end of the second inductor L ₂ is also connected to the junction of the capacitors C ₁ and C ₂ in series; the diode The cathode of D ₄ is connected to the negative pole of the input power supply u _in .

The gates of the power switches S ₁ and S ₂ are respectively connected to respective controllers.

The non-isolated high-gain DC/DC converter has a gain ratio of 4 times compared with the traditional Boost converter. The input end of the converter is connected to a voltage supply module (such as a photovoltaic cell, a fuel cell, etc.), and the output voltage is a controllable high-voltage direct current.

According to the different states of the power switch, the circuit can be divided into three working states:

(1) The controller controls the power switch S ₁ to turn off, and the power switch S ₂ to turn on. At this time, part of the current _of the inductor L ₁ charges the capacitor C 1 through the diode D ₁ , the switch S ₂ and the low-voltage input power supply, and the other part passes through Diode D ₃ , capacitor C ₂ , switch S ₂ and the low-voltage power supply charge capacitor C ₄ . During this process, the low-voltage input power supply, inductor L ₁ , and capacitor C ₂ are all in a discharging state, and capacitors C ₁ and C ₄ are in a charging state; At this time, the power switch S ₂ remains on, and the low-voltage power supply charges the inductor L ₂ through the power switch S ₂ ; the diodes D ₂ and D ₄ are both turned off.

(2) The controller controls the power switch S ₂ to turn off and the power switch S ₁ to turn on. At this time, part of the current of the inductor L ₂ charges the capacitor _{C 2} through the diode D ₄ and the low-voltage input power supply, and the other part passes through the capacitor C ₁ , The diode D ₂ , the switch S ₁ and the low-voltage power supply charge the capacitor C ₃ . During this process, the low-voltage input power supply, the inductor L ₂ , and the capacitor C ₁ are all in the discharging state, and the capacitors C ₂ and C ₃ are in the charging state; at this time, the power switch S ₁ remains on, the low-voltage power supply charges the inductor L ₁ through the power switch S ₁ ; the diodes D ₁ and D ₃ are both turned off.

(3) The power switches are all turned on. At this time, the low-voltage power supply charges the inductor L ₁ and the inductor L ₂ through the power switch S ₁ and the power switch S ₂ respectively; the diodes D ₁ , D ₂ , D ₃ , and D ₄ are all turned off. .

During the above three working processes, the capacitors C ₃ and C ₄ supply power to the load.

In a specific embodiment of the present invention, the power switch selects switching devices with different voltage stresses according to the output voltage in the actual system, which has the characteristics of lower voltage stress than the traditional solution.

The power switch used in the utility model is a switching device, and the opening and closing of the power switch is controlled by the controller. The above-mentioned DC converter with a boosting capacity 4 times that of the traditional Boost converter is controlled by the controller. The phase difference between each phase is 180°, and the duty cycle of each phase is determined according to the relationship between input and output.

To sum up, the topology of the circuit is simple, and the boost capability is strong, which is suitable for some applications with large input and output voltage differences. The diode between the drain and source of the switch tube in Figure 2 is the body diode of the switch tube, and this is just an example of a MOS tube. Other fully controlled devices can also be selected.

The above-mentioned implementation examples of the present utility model are only examples for illustrating the present utility model, and are not intended to limit the implementation of the present utility model. For those of ordinary skill in the art, other variations and modifications in various forms can be made on the basis of the above description. All the implementation manners cannot be exhaustively listed here. All obvious changes or variations derived from the technical solutions of the utility model are still within the scope of protection of the utility model.

Claims (2)

1. a non-isolation type high-gain DC/DC converter, comprises inductance L ₁, L ₂, power switch S ₁, S ₂, diode D ₁, D ₂, D ₃, D ₄, electric capacity C ₁, C ₂, C ₃, C ₄; It is characterized in that, the first inductance L ₁one end, the second inductance L ₂one end meet input power u simultaneously _inpositive pole, the first inductance L ₁the other end, the second inductance L ₂the other end meet the first power switch S respectively ₁drain electrode, the second power switch S ₂drain electrode;

First power switch S ₁source electrode, the second power switch S ₂source electrode meet input power u _innegative pole;

First power switch S ₁, the second power switch S ₂grid connect respective controller respectively;

Diode D ₁, D ₂series connection, diode D ₃, D ₄series connection, wherein diode D ₁negative electrode and diode D ₂anode be connected, diode D ₃negative electrode and diode D ₄anode be connected;

Electric capacity C ₁, C ₂series connection, electric capacity C ₃, C ₄series connection, wherein electric capacity C ₁, C ₃be positioned at top, electric capacity C ₂, C ₄be positioned at below; Electric capacity C ₁upper end and diode D ₁, D ₂the node of series connection is connected, electric capacity C ₂upper end and diode D ₃, D ₄the node of series connection is connected; Electric capacity C ₃upper end and diode D ₂negative electrode be connected, and as output u _opositive pole, electric capacity C ₄lower end and diode D ₃anode be connected, and as output u _onegative pole;

First inductance L simultaneously ₁the other end also meet diode D ₁anode and electric capacity C ₃, C ₄the node of series connection, the second inductance L ₂the other end also meet electric capacity C ₁, C ₂the node of series connection; Diode D ₄negative electrode and input power u _innegative pole be connected.

2. a kind of non-isolation type high-gain DC/DC converter according to claim 1, is characterized in that, the first power switch S ₁, the second power switch S ₂, its control mode is that each phase power switch adopts Interleaved control strategy, that is: difference 180 between every phase switch drive phase place ^o.