CN208174543U - A kind of high-gain Zero Voltage Converter circuit - Google Patents

Abstract

The utility model discloses a kind of high-gain Zero Voltage Converter circuits, including non-isolation type high-gain DC-direct current DC-DC conversion circuit；The Zero voltage transition circuit being connect with non-isolation type high-gain DC-DC conversion circuit；Zero voltage transition circuit, when for the controllable switch conducting in non-isolation type high-gain DC-DC conversion circuit and turning off, it is zero by the operating voltage control between the first end and second end of controllable switch, it is also used to before the second diode shutdown in non-isolation type high-gain DC-DC conversion circuit, the operating current between the anode and cathode of the second diode is reduced to zero.The voltage between its both ends can be reduced to zero when controllable switch is connected, make the voltage zero at its both ends in controllable switch shutdown, it can also realize the zero-current switching of the second diode, reduce the switching loss of controllable switch and the second diode, reduce switching loss, extends service life.

Description

A High Gain Zero Voltage Converter Circuit

technical field

The utility model relates to the field of DC step-up circuits, in particular to a high-gain zero-voltage converter circuit.

Background technique

In recent years, with the rapid development of renewable energy and new energy technologies, new energy technologies such as wind power generation and photovoltaic power generation have gradually become research hotspots. However, since the output voltage of the new energy technology is low and fluctuates greatly, it is necessary to add a high-gain DC-DC (Direct Current, DC-DC) converter to the new energy system to meet the needs of power supply equipment.

In the prior art, the non-isolated high-gain DC-DC conversion circuit can realize boosting by charging and discharging the energy storage capacitor and the energy storage inductor. Please refer to Figure 2, which is a non-isolated DC-DC conversion circuit in the prior art. Type high-gain DC-DC conversion circuit diagram, including DC input power V ₁ , first diode D ₁ , second diode D ₂ , energy storage inductor L ₁ , resonant inductor L _r , energy storage capacitor C ₁ , pole Capacitance C ₀ , controllable switch Q, and pure resistive load R, where the anode of V ₁ is connected to the anode of D ₁ and the first end of L ₁ , the cathode of D ₁ is connected to the first end of L _r , and L _r The _second end of D2 is connected to the anode of D2 and the first end of _C1 , the second end of _C1 is connected to the _second end of L1 and the _first end of Q, the cathode of D2 is connected to the anode of _C0 and R The first end of C is connected, the cathode of _C0 is connected with the second end of R, the second end of Q and the negative electrode _of V1. Using PWM (Pulse Width Modulation, pulse width modulation) to control the on and off of the switch Q can make Q turn on, V ₁ charges C ₁ and L ₁ in parallel; when Q turns off, V ₁ , L _1. C ₁ is connected in series to discharge R to realize output boost.

In the application process of the existing non-isolated high-gain DC-DC conversion circuit, due to the circuit structure and high switching frequency, the loss of the controllable switch Q and the _second diode D2 is relatively serious, and the service life is relatively long. short.

Therefore, how to provide a solution to the above technical problems is a problem that those skilled in the art need to solve at present.

Utility model content

The purpose of the utility model is to provide a high-gain zero-voltage converter circuit, which reduces the loss of the controllable switch and the second diode, and prolongs the service life.

In order to solve the above technical problems, the utility model provides a high-gain zero-voltage converter circuit, including:

Non-isolated high-gain DC-DC DC-DC conversion circuit;

A zero-voltage conversion circuit connected to the non-isolated high-gain DC-DC conversion circuit;

The zero-voltage conversion circuit is used to switch between the first terminal and the second terminal of the controllable switch when the controllable switch in the non-isolated high-gain DC-DC conversion circuit is turned on and off. The operating voltage is controlled to be zero, and it is also used to switch the working voltage between the anode and the cathode of the second diode before the second diode in the non-isolated high-gain DC-DC conversion circuit is turned off. current drops to zero.

Preferably, the zero voltage transfer circuit includes:

Auxiliary capacitor, auxiliary inductance, third diode and auxiliary controllable switch;

The first end of the auxiliary capacitor is connected to the first end of the auxiliary inductor, the common end of the auxiliary inductor and the auxiliary capacitor is connected to the first end of the controllable switch, and the second end of the auxiliary inductor terminal is connected to the anode of the third diode and the first terminal of the auxiliary controllable switch, the cathode of the third diode is connected to the anode of the second diode, and the auxiliary capacitor The second end is connected to the second end of the auxiliary controllable switch, and the common end of the auxiliary capacitor and the auxiliary controllable switch is connected to the second end of the controllable switch.

Preferably, the controllable switch is an NMOS transistor, the first end of the controllable switch is the drain of the NMOS transistor, and the second end of the controllable switch is the source of the NMOS transistor.

Preferably, the third diode is a fast recovery diode FRD.

Preferably, the polar capacitors in the non-isolated high-gain DC-DC conversion circuit are electrolytic capacitors.

Preferably, the auxiliary controllable switch is an NMOS transistor, the first end of the auxiliary controllable switch is the drain of the NMOS transistor, and the second end of the auxiliary controllable switch is the source of the NMOS transistor.

The utility model provides a high-gain zero-voltage converter circuit, comprising: a non-isolated high-gain DC-DC DC-DC conversion circuit; a zero-voltage conversion circuit connected with a non-isolated high-gain DC-DC conversion circuit; The voltage conversion circuit is used to control the working voltage between the first terminal and the second terminal of the controllable switch to be zero when the controllable switch in the non-isolated high-gain DC-DC conversion circuit is turned on and off, It is also used to reduce the working current between the anode and the cathode of the second diode to zero before the second diode in the non-isolated high-gain DC-DC conversion circuit is turned off.

It can be seen that in the non-isolated high-gain DC-DC conversion circuit of the present invention and the zero-voltage conversion circuit connected with the non-isolated high-gain DC-DC conversion circuit, the zero-voltage conversion circuit can operate in the non-isolated high-gain DC-DC When the controllable switch in the DC conversion circuit is turned on, the operating voltage between the first terminal and the second terminal of the controllable switch is reduced to zero, and the turn-on loss is approximately zero. Compared with the current scheme, the controllable switch is reduced. The turn-on loss of the controllable switch can make the voltage across the controllable switch zero when the controllable switch is turned off, and the turn-off loss is approximately zero, which reduces the turn-off loss of the controllable switch. It can also be used in non-isolated high-gain DC-DC Before the second diode in the conversion circuit is turned off, the operating current between the anode and the cathode of the second diode is slowly reduced to zero, the turn-off loss is approximately zero, and the controllable switch and the second The switching loss of the diode prolongs the service life.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings that need to be used in the prior art and the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only the present invention. For some embodiments of the present invention, those of ordinary skill in the art can also obtain other drawings based on these drawings on the premise of not paying creative efforts.

Fig. 1 is the structural representation of a kind of high-gain zero-voltage converter circuit provided by the utility model;

FIG. 2 is a non-isolated high-gain DC-DC conversion circuit diagram in the prior art;

Fig. 3 is a circuit diagram of a high-gain zero-voltage converter circuit provided by the utility model;

FIG. 4 is a timing waveform diagram corresponding to a high-gain zero-voltage converter circuit provided by the present invention.

Detailed ways

The core of the utility model is to provide a high-gain zero-voltage converter circuit, which reduces the loss of the controllable switch and the second diode, and prolongs the service life.

In order to make the purpose, technical solutions and advantages of the embodiments of the utility model more clear, the technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the utility model. Obviously, the described The embodiments are some embodiments of the present utility model, but not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Please refer to Fig. 1. Fig. 1 is a schematic structural diagram of a high-gain zero-voltage converter circuit provided by the present invention, including:

Non-isolated high-gain DC-DC DC-DC conversion circuit;

A zero-voltage conversion circuit 2 connected to a non-isolated high-gain DC-DC conversion circuit 1;

The zero-voltage conversion circuit 2 is used to control the working voltage between the first terminal and the second terminal of the controllable switch when the controllable switch in the non-isolated high-gain DC-DC conversion circuit 1 is turned on and off It is also used to reduce the working current between the anode and the cathode of the second diode to zero before the second diode in the non-isolated high-gain DC-DC conversion circuit 1 is turned off.

Considering that in the non-isolated high-gain DC-DC conversion circuit 1 in the prior art, the controllable switch Q and the _second diode D2 are in the hard switching condition during the turn-on and turn-off process, the hard switching condition Specifically, when it is turned on, the current rise and voltage drop of the switching device are performed simultaneously; when it is turned off, the voltage rise and current drop are performed simultaneously. The overlapping of voltage and current waveforms produces switching losses, which increase rapidly with the increase of switching frequency. At the same time, because the switching frequency of the controllable switch Q can reach at least 100kHZ, it will cause high switching loss, which reduces the service life of the controllable switch and the second diode. At the same time, under the working condition of hard switching, the switching noise is relatively high Large, affecting the working environment, and the electromagnetic interference will be more serious, affecting the work of the surrounding electronic equipment. The zero-voltage conversion circuit 2 in the embodiment of the utility model can reduce the voltage at both ends to zero when the controllable switch is turned on, so that it can be turned on under zero-voltage conditions, and the turn-on loss is approximately zero. When the switch is turned off, the voltage at both ends is controlled to be zero, realizing zero-voltage turn-off, and its turn-off loss is approximately zero, and it can also control the current at both ends of the second diode to slowly drop to zero when it is turned off. , the turn-off loss is approximately zero, prolonging the service life of the controllable switch and the second diode.

Specifically, there may be various types of the zero voltage conversion circuit 2 in the embodiment of the present invention, which is not limited in this embodiment of the present invention.

Wherein, while solving the above-mentioned technical problems, the switching loss of devices in the zero-voltage switching circuit 2 in the embodiment of the present invention is short, and the switching loss is small, and the loss will not be increased so as to increase the cost.

The utility model provides a high-gain zero-voltage converter circuit, comprising: a non-isolated high-gain DC-DC DC-DC conversion circuit; a zero-voltage conversion circuit connected with a non-isolated high-gain DC-DC conversion circuit; The voltage conversion circuit is used to control the working voltage between the first terminal and the second terminal of the controllable switch to be zero when the controllable switch in the non-isolated high-gain DC-DC conversion circuit is turned on and off, It is also used to reduce the working current between the anode and the cathode of the second diode to zero before the second diode in the non-isolated high-gain DC-DC conversion circuit is turned off.

It can be seen that in the non-isolated high-gain DC-DC conversion circuit of the present invention and the zero-voltage conversion circuit connected with the non-isolated high-gain DC-DC conversion circuit, the zero-voltage conversion circuit can operate in the non-isolated high-gain DC-DC When the controllable switch in the DC conversion circuit is turned on, the operating voltage between the first terminal and the second terminal of the controllable switch is controlled to zero, and the turn-on loss is approximately zero. Compared with the current scheme, the controllable switch is reduced. The turn-on loss of the controllable switch can make the voltage across the controllable switch zero when the controllable switch is turned off, and the turn-off loss is approximately zero, which reduces the turn-off loss of the controllable switch. It can also be used in non-isolated high-gain DC-DC Before the second diode in the conversion circuit is turned off, the operating current between the anode and the cathode of the second diode is slowly reduced to zero, the turn-off loss is approximately zero, and the controllable switch and the second The switching loss of the diode prolongs the service life.

On the basis of above-mentioned embodiment:

As a preferred embodiment, the zero voltage transfer circuit 2 includes:

Auxiliary capacitor, auxiliary inductance, third diode and auxiliary controllable switch;

The first end of the auxiliary capacitor is connected to the first end of the auxiliary inductor, the common end of the auxiliary inductor and the auxiliary capacitor is connected to the first end of the controllable switch, the second end of the auxiliary inductor is connected to the anode of the third diode and the auxiliary connected to the first end of the control switch, the cathode of the third diode is connected to the anode of the second diode, the second end of the auxiliary capacitor is connected to the second end of the auxiliary controllable switch, the auxiliary capacitor and the auxiliary controllable switch The common end is connected with the second end of the controllable switch.

In order to better describe the embodiment of the utility model, please refer to FIG. 3, which is a circuit diagram of a high-gain zero-voltage converter circuit provided by the utility model. It should be noted that, except for the transfer switch Q and the auxiliary switch Q The first terminal and the second terminal of the electronic device referred to in ₁ are only for the convenience of describing the connection relationship between the devices, and do not limit their connection ports, that is to say, the two connection ports can be used interchangeably.

Among them, on the basis of reducing the loss of the controllable switch and the second diode in the embodiment of the present invention, the change of the voltage and current of the controllable switch during the switching process is limited due to the resonance process of the auxiliary capacitor and the auxiliary inductance rate, the switching noise is reduced, and the working environment is optimized.

Specifically, there can be many types of controllable switch Q, for example, various controllable switch tubes containing parasitic body diodes, such as NMOS (N-Metal-Oxide-Semiconductor, N-type metal-oxide-semiconductor ) pipes, etc., the embodiments of the present utility model are not limited here.

Specifically, the first diode, the second diode and the third diode can be various types of diodes, such as Schottky diodes or other types of diodes that do not affect the purpose of the utility model, The embodiment of the present utility model is not limited here.

As a preferred embodiment, the controllable switch is an NMOS transistor, the first end of the controllable switch is the drain of the NMOS transistor, and the second end of the controllable switch is the source of the NMOS transistor.

Specifically, the NMOS tube has the advantages of small size, light weight, long life, low noise, good thermal stability, strong anti-interference ability, low power consumption, and convenient control.

Of course, in addition to the NMOS transistor, the controllable switch may also be other types of controllable switch transistors including parasitic body diodes, which are not limited in this embodiment of the present invention.

As a preferred embodiment, the third diode is FRD (Fast recovery diode, fast recovery diode).

Specifically, the FRD has the advantages of good switching characteristics and short reverse recovery time.

Of course, in addition to the FRD, the third diode may also be other types of diodes, which are not limited in this embodiment of the present invention.

As a preferred embodiment, the polar capacitors in the non-isolated high-gain DC-DC conversion circuit 1 are electrolytic capacitors.

Specifically, the electrolytic capacitor has the advantages of large capacitance and low price.

Of course, in addition to the electrolytic capacitor, the polar capacitor may also be of other types, which are not limited in this embodiment of the present invention.

As a preferred embodiment, the auxiliary controllable switch is an NMOS transistor, the first end of the auxiliary controllable switch is the drain of the NMOS transistor, and the second end of the auxiliary controllable switch is the source of the NMOS transistor.

Specifically, the NMOS tube has the advantages of small size, light weight, long life, low noise, good thermal stability, strong anti-interference ability, low power consumption, and convenient control.

Of course, in addition to the NMOS transistor, the auxiliary controllable switch may also be other types of controllable switch transistors, which are not limited in this embodiment of the present invention.

As a preferred embodiment, the frequency of the driving pulse of the controllable switch is the same as that of the auxiliary controllable switch.

Specifically, the driving pulse of the controllable switch and the driving pulse of the auxiliary controllable switch have the same frequency, which can make the design of the control circuit more convenient.

As a preferred embodiment, the duty cycle of the driving pulse of the controllable switch is N times the duty cycle of the driving pulse of the auxiliary controllable switch, where N is a positive number greater than 1.

Specifically, the duty cycle of the driving pulse of the controllable switch is N times the duty cycle of the driving pulse of the auxiliary controllable switch, wherein N is a positive number greater than 1, which can make the Conduction loss is small.

Wherein, N may be a positive number greater than 1, such as 1, 1.5, or 3, which is not limited in this embodiment of the present invention.

Specifically, in practical applications, the converter circuit can be designed with reference to the following parameters:

For non-isolated high-gain DC-DC conversion circuit 1, input power V ₁ =15v; resonant inductance L _r =0.3uH; energy storage capacitor C ₁ =4.7uF; energy storage inductance L ₁ =50uH; polarity capacitance C ₀ = 100uF; pure resistance load R = 45Ω; controllable switch Q is NMOS, switching frequency fs = 100kHZ, duty cycle d = 0.6. For the zero-voltage conversion circuit 2, the auxiliary capacitor C _r =10nF; the auxiliary inductor L _r1 =5uF; the auxiliary controllable switch Q ₁ is an N-channel MOSFET, the switching frequency fs=100kHZ, and the duty cycle d=0.1.

Of course, in addition to the above parameters, each device in the converter circuit can also be designed with other parameters, which are not limited in this embodiment of the present invention.

In order to facilitate the understanding of the technical solutions provided by the embodiments of the present invention, the conversion circuit provided by the embodiments of the present invention will be illustrated below with reference to FIG. 3 and FIG. 4 .

It should be noted that, for the convenience of analysis, for the circuit shown in Figure 3, it is assumed that all components are in an ideal state, that is, the conduction voltage drop of the switch tube is ignored, the drain current when the diode and the switch tube are off, and the series connection of capacitors is ignored. resistor, the current flowing through _L1 is continuous, and _C0 is sufficient to make the output voltage across the load resistor R constant.

As shown in Figure 4, where t ₀ -t ₇ is the waveform change in a complete cycle, the following seven working states are mainly analyzed. (Before t ₀ , the initial state of the topology is: both Q and Q ₁ are in the cut-off state, V ₁ -L ₁ -C ₁ -D ₂ -R supplies power to R in series to form a boost loop, and the current flowing through the loop is i _D2 .)

(1) t ₀ -t ₁ time period

At time t ₀ , the pulse signal V _gs1 drives Q ₁ to conduct with zero current. Thus forming a loop V ₁ -L ₁ -L _r1 -Q ₁ , at this time the current i _r1 flowing through the loop V ₁ -L ₁ -L _r1 -Q ₁ increases linearly, and flows through the loop V ₁ -L ₁ -C ₁ The current i _D2 of -D ₂ -R decreases linearly. At the time t ₁ , the value of the current i _r1 is equal to the value of the current i _D2 at the time t ₀ , and the current i _D2 drops to zero at the time t ₁ , and D ₂ is cut off to realize Zero current shutdown.

(2) t ₁ -t ₂ time period

Q ₁ continues to be turned on. At this time, C _r and L _r1 are connected in parallel to form a resonant circuit C _r -L _r1 -Q ₁ , C _r charges L _r1 , and the current i _r1 flowing through L _r1 increases sinusoidally while C _r The voltage of L r1 decreases, and at _t2 time, when the voltage on C _r decreases to zero, the current i _r1 of L _r1 reaches the maximum value. Because Q is in parallel with Cr, the voltage _vQ across _Q is also zero at instant _t2 .

(3) t ₂ -t ₃ time period

During this time period, Q1 continues to conduct, i _r1 remains at the maximum value, and the body diode of Q conducts so that the voltage _vQ across _Q remains also zero.

(4) t ₃ -t ₄ time period

At time _t3 , Q is turned on under the action _of the pulse signal V _gs , and Q1 is turned off. Since the voltage v _{Q at both ends of Q} has dropped to zero before it is turned on, Q realizes zero-voltage conduction. Compared with the prior art, the realization of zero-voltage conduction reduces switching loss and switching noise. At the same time, V ₁ starts to charge C ₁ and L ₁ respectively, forming two loops V ₁ -D ₁ -L _r -C ₁ -Q and V ₁ -L ₁ -Q. Since L _r and C ₁ form a series resonance, the current i _D1 flowing through D ₁ changes sinusoidally, and the current i _l1 on L ₁ rises linearly. At this point V1 still _keeps charging to _C1 and _L1 . Since Q ₁ is turned off, D _r is turned on, L _r1 charges C ₁ to form a loop L _r1 -D _r -C ₁ , the current i _r1 on L _r1 decreases linearly from the maximum value, and at time t ₄ , The current i _r1 on L _r1 drops to zero, and D _r realizes zero-current shutdown.

(5) t ₄ -t ₅ time period

In the V ₁ -D ₁ -L _r- C ₁ -Q resonant circuit, V ₁ continues to charge C ₁ until the current i _D1 drops to zero at t ₅ , D ₁ is turned off with zero current, C ₁ is charged, and C ₁ The upper voltage reaches the maximum value. In the V ₁ -L ₁ -Q circuit, V ₁ keeps charging to L ₁ , and the i _L1 current on L ₁ still increases linearly.

(6) t ₅ -t ₆ time period

During this period, there is only the V ₁ -L ₁ -Q circuit, and L ₁ is charged until t ₆ , when Q is cut off, and the charging of L ₁ ends. _The current on L1 reaches the maximum value.

(7) t ₆ -t ₇ time period

Both Q and Q ₁ are cut off, and V ₁ -L ₁ -C _r forms a loop to charge C _r so that the voltage across Q rises slowly to achieve zero-voltage shutdown, and the voltage across both ends reaches at time t ₇ ; at the same time, V ₁ -L ₁ -C ₁ -D ₂ -R forms a loop to discharge to R to obtain a higher output voltage.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. It should also be noted that in this specification, relative terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations There is no such actual relationship or order between the operations. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article or apparatus comprising that element.

The above description of the disclosed embodiments enables those skilled in the art to realize or use the utility model. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims (6)

1. A high-gain zero-voltage converter circuit, characterized in that, comprising: Non-isolated high-gain DC-DC DC-DC conversion circuit; A zero-voltage conversion circuit connected to the non-isolated high-gain DC-DC conversion circuit; The zero-voltage conversion circuit is used to switch between the first terminal and the second terminal of the controllable switch when the controllable switch in the non-isolated high-gain DC-DC conversion circuit is turned on and off. The operating voltage is controlled to be zero, and it is also used to switch the working voltage between the anode and the cathode of the second diode before the second diode in the non-isolated high-gain DC-DC conversion circuit is turned off. current drops to zero. 2. The converter circuit according to claim 1, wherein the zero voltage transfer circuit comprises: Auxiliary capacitor, auxiliary inductance, third diode and auxiliary controllable switch; The first end of the auxiliary capacitor is connected to the first end of the auxiliary inductor, the common end of the auxiliary inductor and the auxiliary capacitor is connected to the first end of the controllable switch, and the second end of the auxiliary inductor terminal is connected to the anode of the third diode and the first terminal of the auxiliary controllable switch, the cathode of the third diode is connected to the anode of the second diode, and the auxiliary capacitor The second end is connected to the second end of the auxiliary controllable switch, and the common end of the auxiliary capacitor and the auxiliary controllable switch is connected to the second end of the controllable switch. 3. The converter circuit according to claim 2, wherein the controllable switch is an NMOS transistor, the first end of the controllable switch is the drain of the NMOS transistor, and the second end of the controllable switch is an NMOS transistor. source of the tube. 4. The converter circuit according to claim 3, wherein the third diode is a fast recovery diode (FRD). 5. The converter circuit according to claim 4, wherein the polarized capacitor in the non-isolated high-gain DC-DC conversion circuit is an electrolytic capacitor. 6. The converter circuit according to any one of claims 2-5, wherein the auxiliary controllable switch is an NMOS transistor, and the first end of the auxiliary controllable switch is the drain of the NMOS transistor, The second terminal of the auxiliary controllable switch is the source of the NMOS transistor.