CN205336117U - Three level boost converters - Google Patents

Abstract

The utility model discloses a three level boost converters, its first diode D1's negative pole and power vs's positive pole are connected to sampling circuit's first input end and second input respectively, and sampling circuit's output is connected to the input of controller, and the output of controller is connected to drive unit's input, drive unit's first output and the grid that the second output was connected to first switch tube Q1 respectively and second switch pipe Q2's grid, the utility model discloses a three level boost converters adopts equitable structural design, under the circumstances that does not increase extra device, and the loss of the hard switch PWM control boost circuit of greatly reduced.

Description

A kind of three-level Boost converter

Technical field

This utility model belongs to electric and electronic technical field, relates to a kind of three-level Boost converter。

Background technology

Boost is a kind of switch DC booster circuit, three-level Boost converter compares two level Boost converters, the voltage stress of device reduces half, therefore it is of wide application, three level Boost circuit are initially typical PWM hard switching circuit, later in order to promote dynamic characteristic, reduce magnetics volume, improve circuit efficiency, develop multiple Sofe Switch flexible circuit gradually；But could realize owing to soft switch circuit must increase extra device, cause cost to increase, control the problems such as difficulty increase, therefore in actual applications, the hard switching three-level Boost converter that PWM controls still has very big using value, but traditional three-level Boost converter controls two staggered drivings, under normal circumstances, the driving frequency of switching tube often reaches tens of kHz, most at 20kHz～40kHz, and owing to switching tube frequency immobilizes, cause that the switching loss of three-level Boost converter is greatly increased。

Utility model content

In order to solve the problems referred to above, the utility model proposes a kind of three-level Boost converter, adopt rational structural design, when not increasing extra device, be substantially reduced hard switching PWM and control the loss of Boost circuit。

In order to achieve the above object, the technical solution adopted in the utility model is, a kind of three-level Boost converter, including power supply Vs, the positive pole of power supply Vs connects one end of the first inductance L1, the other end of the first inductance L1 connects the drain electrode of the first switching tube Q1 and the positive pole of the first diode D1 respectively, the negative pole of the first diode D1 connects the input of the first electric capacity C1, the outfan of the first electric capacity C1 connects source electrode and the substrate of the first switching tube Q1 respectively, the drain electrode of second switch pipe Q2 and the input of the second electric capacity C2, the outfan of the second electric capacity C2 connects the positive pole of the second diode D2, the negative pole of the second diode D2 is connected to the source electrode of second switch pipe Q2 and the negative pole of power supply Vs；The described negative pole of the first diode D1 and the positive pole of power supply Vs are respectively connecting to first input end and second input of sample circuit, the outfan of sample circuit is connected to the input of controller, the outfan of controller is connected to the input of driver element, and the first outfan of driver element and the second outfan are respectively connecting to the grid of the first switching tube Q1 and the grid of second switch pipe Q2。

Further, the negative pole of described second diode D2 accesses the negative pole of power supply Vs by the second inductance L2。

Further, described power supply Vs is lead-acid battery or lithium battery。

Further, described inductance all adopts the magnet ring of ferrum sial material。

In scheme of the present utility model, sample circuit obtains output voltage Vo, output electric current Io and input power Vs, send into controller, relation according to the Vs being calculated gained by concrete magnetic material stored in the controller and switching tube operating frequency, when controller exports this Vs, the dutycycle that switching tube is corresponding, controls the driving frequency f of driver element output；Under this driving frequency f, controller judges that whether the value of output voltage Vo or output electric current Io is consistent with the value of controller demand, if greater than requirements, reduces the dutycycle D of driver element output, if less than requirements, increases the dutycycle D of driver element output。

The loss of hard switching Boost circuit is made up of switching loss and conduction loss two parts, this utility model is mainly for the Boost circuit using the battery such as lead-acid battery, lithium battery as power supply, cell voltage can be gradually lowered in circuit work process, three-level Boost converter of the present utility model is by rational structural design, the switching frequency of circuit is made with the reduction of input voltage and to gradually reduce, it is greatly reduced switching loss, thus realizing reducing the purpose of whole circuit loss by reducing switching frequency。

Further, this utility model increases by a second inductance L2 in circuit, after increasing by the second inductance L2, the number of turn of single inductance can reduce, total sensibility reciprocal of the first inductance L1 and the second inductance L2 reduces to some extent relative to the inductance in traditional circuit, but the ratio falling reduction is less, less switching frequency f therefore can be obtained。

Accompanying drawing explanation

Fig. 1 is this utility model three-level Boost converter schematic diagram。

Fig. 2 is that this utility model implements key point oscillogram in schematic diagram。

Fig. 3 is the frequency in the citing of this utility model actual parameter and input voltage relation curve。

Fig. 4 is the relation curve of this utility model sendust core magnetic field intensity and Drop coefficient。

Detailed description of the invention

Below in conjunction with the drawings and specific embodiments, this utility model is described in detail。

As shown in Figure 1, this utility model includes the lead-acid battery as power supply Vs or lithium battery, the positive pole of power supply Vs connects one end of the first inductance L1, the other end of the first inductance L1 connects the drain electrode of the first switching tube Q1 and the positive pole of the first diode D1 respectively, the negative pole of the first diode D1 connects the input of the first electric capacity C1, the outfan of the first electric capacity C1 connects the source electrode of the first switching tube Q1 respectively, the drain electrode of second switch pipe Q2 and the input of the second electric capacity C2, the outfan of the second electric capacity C2 connects the positive pole of the second diode D2, the negative pole of the second diode D2 is connected to the source electrode of second switch pipe Q2 and one end of the second inductance L2, the other end of the second inductance L2 accesses the negative pole of power supply Vs；The described negative pole of the first diode D1 and the positive pole of power supply Vs are respectively connecting to first input end and second input of sample circuit, the outfan of sample circuit is connected to the input of controller, the outfan of controller is connected to the input of driver element, first outfan of driver element and the second outfan are respectively connecting to the grid of the first switching tube Q1 and the grid of second switch pipe Q2, in Fig. 1, control signal Qg1 is connected to the grid of the first switching tube Q1 from the first outfan of driver element, control signal Qg2 is connected to the grid of second switch pipe Q2 from the second outfan of driver element。。

Such as Fig. 2, embodiment of the present utility model is the change according to input voltage, makes the operating frequency of switching tube slowly reduce within the specific limits。Owing to three level BOOST circuit are booster circuit, therefore the upper limit of input voltage Vs is output voltage Vo；Ripple alternately sent out by first switching tube and second switch pipe simultaneously, and dutycycle need to less than 0.5, and therefore the lower limit of input voltage isSo, what frequency reduced ranges for:

Circuit work schedule is as shown in Figure 2: t₀～t₂In the moment, the cycle is T₁；T_n+1～t_n+3In the moment, the cycle is T_n+1, it can be seen that T_n+1>T₁, namely along with the reduction of input voltage Vs, the switching frequency of circuit work declines, and the relation between input voltage Vs and switching frequency is:

$f\left(Vs\right):=\frac{(Vs-\frac{1}{2}\·Vo)\·Don\left(Vs\right)}{L\left(Vs\right)\·\mathrm{\Δ}I\left(Vs\right)}---(1-1)$

Wherein Δ I (Vs) is the ripple current on inductance L1, and Don (Vs) is dutycycle, and L (Vs) is that inductance L1 sensibility reciprocal increases the actual value after falling with electric current。

$Don\left(Vs\right):=\frac{Vo-Vs}{Vo}---(1-2)$

$\mathrm{\Δ}I\left(Vs\right):=K\_L\·\frac{Po}{Vs\·\mathrm{\μ}}---(1-3)$

Illustrate with actual parameter: output voltage Vo=650V, output Po=12kW, circuit efficiency η=98%, power supply is ternary lithium battery group, and voltage range is 330V～450V；Inductive current ripple factor K_L=0.25；The initial sensibility reciprocal L0=390uH of inductance, adopts the magnet ring of ferrum sial material, magnetic circuit l=0.1074m, totally 38 circle。

The material of L (Vs) function and inductance, number of turns also has relation, and under above-mentioned actual parameter, the Drop coefficient of inductance value follows the curve of Fig. 4, and transverse axis is magnetic field intensity, its relation such as formula 1-4 with Vs；The actual value that inductance value falls can be expressed as formula 1-5。

$H\left(Vs\right):=N\·\frac{\left(Iin\right(Vs)+\frac{1}{2}\·\mathrm{\Δ}I(Vs\left)\right)}{l}---(1-4)$

L (Vs) :=LO NPS60_fall (H (Vs)) (1-5)

The frequency obtained according to instance parameter and relation curve such as Fig. 3 of input voltage, it can be seen that when the switching frequency when 330V inputs is 2kHz, 420V input voltage, switching frequency is 30kHz。It means that compared to the three level Boost circuit that traditional fixed frequency is 30kHz, this programme is when minimum input voltage, and switching loss is the highest reduces 15 times；

Switching loss P_swWith switching frequency f positive correlation:

P_sw=k_every* f；

Wherein k_everyFor the switching loss of each switch periods, the switching frequency that therefore this utility model reduces can be substantially reduced the switching loss of three-level Boost converter。

In addition, due to when magnetic field intensity becomes big, inductance value Drop coefficient becomes rapidly big, therefore this utility model increases by the second inductance L2, as shown in Figure 1 schematic diagram in circuit, after increasing by the second inductance L2, the number of turn of single inductance can reduce, total sensibility reciprocal of two inductance reduces to some extent relative to the inductance in traditional circuit, but the ratio falling reduction is less, therefore can obtain less switching frequency f。

Claims (4)

1. a three-level Boost converter, it is characterized in that, including power supply Vs, the positive pole of power supply Vs connects one end of the first inductance L1, the other end of the first inductance L1 connects the drain electrode of the first switching tube Q1 and the positive pole of the first diode D1 respectively, the negative pole of the first diode D1 connects the input of the first electric capacity C1, the outfan of the first electric capacity C1 connects source electrode and the substrate of the first switching tube Q1 respectively, the drain electrode of second switch pipe Q2 and the input of the second electric capacity C2, the outfan of the second electric capacity C2 connects the positive pole of the second diode D2, the negative pole of the second diode D2 is connected to the source electrode of second switch pipe Q2 and the negative pole of power supply Vs；The described negative pole of the first diode D1 and the positive pole of power supply Vs are respectively connecting to first input end and second input of sample circuit, the outfan of sample circuit is connected to the input of controller, the outfan of controller is connected to the input of driver element, and the first outfan of driver element and the second outfan are respectively connecting to the grid of the first switching tube Q1 and the grid of second switch pipe Q2。

2. a kind of three-level Boost converter according to claim 1, it is characterised in that the negative pole of described second diode D2 accesses the negative pole of power supply Vs by the second inductance L2。

3. a kind of three-level Boost converter according to claim 1, it is characterised in that described power supply Vs is lead-acid battery or lithium battery。

4. a kind of three-level Boost converter according to claim 1, it is characterised in that described inductance all adopts the magnet ring of ferrum sial material。