CN205566101U - Improved generation pulse train control buck converter - Google Patents

Abstract

The utility model relates to an improved generation pulse train control buck converter, including improved generation buck converter and PT control circuit. Improved generation buck converter develop by buck topology to form, replace the energy storage inductance in the buck converter with a pair of coupling inductance. The former avris of coupling inductance termination MOS of the same name manages source electrode, synonym termination output filter capacitance C's positive pole, the vice former avris synonym of avris termination of the same name of coupling inductance end, synonym terminating diode D2's negative pole, diode D2's positive pole connects output filter capacitance C's negative pole. Converter operation to eliminate output voltage's low frequency when inductive current continuous conduction mode undulant and reduce MOS pipe peak current.

Description

A kind of IMPROVED PULSE DYNAMIC SPRAYING MACHINE sequence controls Buck changer

Technical field

This utility model relates to a kind of improved B uck changer, and specifically a kind of pulse train controls containing coupling Close the Buck changer of inductance.

Background technology:

It is to open for the pulse width modulation (PWM) based on linear control theory that pulse train (PT) controls A kind of switch converters control method that pass changer exists the slow inherent shortcoming of transient response and proposes.PT is controlled System is a kind of novel nonlinear discrete control method, adjusts by adjusting two groups of pulse combined set in advance Output voltage, has circuit realiration simple, controls loop and needs not compensate for network, to input and the change of load There is quick dynamic responding speed, be highly suitable for the switching power control system higher to reliability requirement.

PT controls a kind of control being to put forward for discontinuous current mode conduction mode (DCM) switch converters Method, it is substantially the input energy hole of switch converters.In a switch periods, switch converters Inductive energy storage be zero, input energy be all delivered to outfan.PT control select high power control pulse with Input more energy to switch converters, make output voltage increase；Select low-power control pulse with reduce to The energy of switch converters input, makes output voltage decline.During switch converters steady operation, high power controls Pulse and low-power control the combination of pulse and form a pulse train cycle period, in this pulse cycle Input energy and output energy reach dynamic equilibrium, thus maintain the constant of output voltage.Buck is controlled at PT When changer works in continuous current mode conduction mode (CCM), in a switch periods, Buck converts The inductive energy storage of device is no longer zero, and output voltage variable quantity is no longer directly relevant to controlling pulse.PT is controlled CCM Buck changer processed, when high power controls impulse action, inductive current rises, but it cannot be guaranteed that output Voltage rises immediately；Similarly, when low-power controls impulse action, inductive current declines, but it cannot be guaranteed that defeated Go out voltage to decline immediately.Therefore, there is the hysteresis quality of output voltage regulation in PT control CCM Buck changer The low-frequency fluctuation phenomenon of the output voltage thus caused.

Control CCM Buck changer for above PT and there is low-frequency fluctuation phenomenon, the utility model proposes one Plant modified model PT and control Buck changer, eliminate low-frequency fluctuation phenomenon.

Utility model content:

This utility model is for above-mentioned low-frequency fluctuation problem, proposes a kind of modified model eliminating low-frequency fluctuation Buck changer.To achieve these goals, this utility model adopts the following technical scheme that this utility model Being made up of improved B uck changer and PT control circuit, PT control circuit is to be triggered by comparator, D Device and door 1# and door 2# or door, driving are sequentially connected composition；Improved B uck changer includes: Metal-oxide-semiconductor Q, diode D₁, diode D₂, coupling inductance, output filter capacitor；Described modified model Buck changer is to be developed by Buck topology, by a pair coupling of the energy storage inductor in Buck changer Inductance replaces；Metal-oxide-semiconductor Q drain electrode connects input power positive pole；Metal-oxide-semiconductor Q grid connects driving of PT control circuit Dynamic signal；Metal-oxide-semiconductor Q source electrode, diode D₁Negative electrode, coupling inductance former avris Same Name of Ends is connected with each other； Coupling inductance former avris different name end, secondary side Same Name of Ends, the positive pole of output filter capacitor, load positive pole mutual Connect；Input power negative pole, diode D₁Anode, diode D₂Anode, output filter capacitor C Negative electrode, the negative pole of load is connected with each other；Coupling inductance secondary side different name terminating diode D₂Negative electrode.Institute The coupling inductance former limit L stated₁With secondary L₂Inductance value is identical and coefficient of coup α span is 0.8 to 0.9.

This utility model beneficial effect: eliminate PT and control to exist when Buck changer operates in CCM pattern Low-frequency fluctuation phenomenon, simultaneously reduce metal-oxide-semiconductor peak point current.

Accompanying drawing illustrates:

Fig. 1 is that PT controls improved B uck converter principle figure.

Fig. 2 a is improved B uck changer operation mode 1 equivalent circuit theory figure.

Fig. 2 b is improved B uck changer operation mode 2 equivalent circuit theory figure.

Fig. 2 c is improved B uck changer operation mode 3 equivalent circuit theory figure.

Fig. 3 is improved B uck changer exemplary operation waveform in a switch periods.

Fig. 4 a is the bifurcation graphs that improved B uck changer output voltage changes along with the coefficient of coup.

Fig. 4 b is the bifurcation graphs that improved B uck changer metal-oxide-semiconductor peak point current changes along with the coefficient of coup.

Fig. 5 a be PT control Buck changer output voltage, inductive current, load current, metal-oxide-semiconductor electric current and Control pulse temporal simulation waveform.

Fig. 5 b is that PT controls improved B uck changer output voltage, coupling inductance electric current, load current, MOS Tube current and control pulse temporal simulation waveform.

Detailed description of the invention:

Below in conjunction with embodiment, technical solutions of the utility model are described in detail.Fig. 1 is of the present utility model Improved B uck changer and PT control circuit block diagram.Improved B uck changer is to be drilled by Buck topology Become, the energy storage inductor in Buck changer is replaced by a pair coupling inductance；Metal-oxide-semiconductor Q drain electrode connects Input power positive pole；Metal-oxide-semiconductor Q grid connects the driving signal of PT control circuit；Metal-oxide-semiconductor Q source electrode, two Pole pipe D₁Negative electrode, coupling inductance former avris Same Name of Ends is connected with each other；Coupling inductance former avris different name end, pair Avris Same Name of Ends, the positive pole of output filter capacitor, the positive pole of load are connected with each other；Input power negative pole, two poles Pipe D₁Anode, diode D₂Anode, the negative electrode of output filter capacitor C, the negative pole of load interconnect mutually Connect；Coupling inductance secondary side different name terminating diode D₂Negative electrode.PT control circuit is to be touched by comparator, D Send out device and door 1# and door 2# or door, driving is sequentially connected composition.PT control circuit operation principle is: When sampling instant arrives, it is judged that changer output voltage v_oWhether more than reference voltage V_ref, work as v_o<V_ref Time, controller selects high power to control pulse P_H, make changer transmission energy increase, output voltage rises therewith High；Work as v_o>V_refTime, controller selects low-power to control pulse P_L, changer transmission energy reduces, output Voltage declines therewith.

This utility model has 3 kinds of operation modes in a switch periods, and the equivalent circuit diagram of each mode is such as Shown in Fig. 2.

1. mode 1 [t₀-t₁]: as shown in Fig. 2 (a), Q, D₂Conducting, D₁Turn off.At this conducting phase, power supply E Through metal-oxide-semiconductor Q to coupling inductance former limit L₁Charging, electric current i_L1With slope k₁Rise；Coupling inductance secondary Through diode D₂Charging energy-storing, electric current i_L2With slope k₂Rise.

$k_1=\frac{{\mathrm{EL}}_2-v_o(L_2+\mathrm{\&alpha;}\sqrt{L_1{L}_2})}{(1-{\mathrm{\&alpha;}}^2)L_1{L}_2}---\left(1\right)$

$k_2=\frac{\mathrm{\&alpha;}E\sqrt{L_1{L}_2}-v_o(L_1+\mathrm{\&alpha;}\sqrt{L_1{L}_2})}{(1-{\mathrm{\&alpha;}}^2)L_1{L}_2}---\left(2\right)$

Wherein, E is input voltage, v_oFor output voltage, α is the coefficient of coup, and the work of coupling inductance branch road must be expired Foot k₂> 0, i.e.

$\frac{v_o}{E-v_o}\frac{L_1}{\sqrt{L_1{L}_2}}<\mathrm{\&alpha;}<1---\left(3\right)$

2. mode 2 [t₁-t₂]: as shown in Fig. 2 (b), D₁、D₂Conducting, Q turns off.The former limit of coupling inductance is by continuous Stream diode D₁Release energy, electric current i_L1With slope k₃Decline；Coupling inductance secondary passes through fly-wheel diode D₂Release energy, electric current i_L2With slope k₄Decline.

$k_3=-\frac{v_o(L_2+\mathrm{\&alpha;}\sqrt{L_1{L}_2})}{(1-{\mathrm{\&alpha;}}^2)L_1{L}_2}---\left(4\right)$

$k_4=-\frac{v_o(L_1+\mathrm{\&alpha;}\sqrt{L_1{L}_2})}{(1-{\mathrm{\&alpha;}}^2)L_1{L}_2}---\left(5\right)$

3. mode 3 [t₂-t₃]: as shown in Fig. 2 (c), D₁Conducting, Q, D₂Turn off.The former limit of coupling inductance is by continuous Stream diode D₁Continue to release energy, electric current i_L1With slope k₅Decline；The release of coupling inductance secondary energy is complete, It is in cut-off state.

$k_5=-\frac{v_o}{L_1}---\left(6\right)$

It is illustrated in figure 3 improved B uck changer when working in CCM pattern, in a switch periods Its main waveform diagram.i_L1、i_L2It is respectively the former limit of coupling inductance, the electric current of secondary, i_LFor coupling electricity Inducing current.When coupling inductance electric current more than load current time, coupling inductance electric current while powering load, Unnecessary electric current charges to output filter capacitor, and output voltage rises；Otherwise, when coupling inductance electric current is less than negative When carrying electric current, coupling inductance electric current is all supplied to load, and the insufficient section of the required electric current of load is discharged by electric capacity Electric current supplements, and output voltage declines.

In mode 1, coupling inductance electric current i_LAscending amount is coupling inductance primary current i_L1With secondary current i_L2Sum, I.e. electric current i_LRate of rise k₁₂For electric current i_L1With electric current i_L2Slope sum.

$k_{12}=\frac{E(L_2+\mathrm{\&alpha;}\sqrt{L_1{L}_2})-v_o(L_1+L_2+2\mathrm{\&alpha;}\sqrt{L_1{L}_2})}{(1-{\mathrm{\&alpha;}}^2)L_1{L}_2}---\left(7\right)$

From Fig. 3 (d), coupling inductance secondary current i_L2In mode 1, ascending amount declines equal in mode 2 Amount, i.e.

k₂DT=-k₄dT (8)

D is that switching tube Q turns on dutycycle, and d is electric current i_L2The time used by zero and switch week is dropped to from maximum The ratio of phase T.

Simultaneous formula (2), (3) and (6):

$d=(\frac{\mathrm{\&alpha;}\sqrt{L_1{L}_2}}{L_1+\mathrm{\&alpha;}\sqrt{L_1{L}_2}}\frac{E}{v_o}-1)D---\left(9\right)$

In mode 2, coupling inductance electric current i_LDescending slope k₃₄For electric current i_L1With electric current i_L2Slope sum, i.e.

$k_{34}=-\frac{v_o(L_1+L_2+2\mathrm{\&alpha;}\sqrt{L_1{L}_2})}{(1-{\mathrm{\&alpha;}}^2)L_1{L}_2}---\left(10\right)$

Due to t₂The energy release of moment coupling inductance branch road is complete, electric current i_LDescending slope is equal to electric current i_L1Slope.

In this utility model, the former avris of coupling inductance is identical with secondary side inductance value, and all for L.Open at one In the cycle of pass, coupling inductance current change quantity is

$\begin{array}{c}{\mathrm{\&Delta;i}}_L=k_{12}DT+k_{34}dT+k_5(1-D-d)T\\ =\left\{\begin{array}{cc}\frac{{\mathrm{ED}}_H-v_o}{L}T>0,& P=P_H\\ \frac{{\mathrm{ED}}_L-v_o}{L}T<0,& P=P_L\end{array}\right.\end{array}---\left(11\right)$

Wherein D_HAnd D_LIt is that high power controls pulse P respectively_HPulse P is controlled with low-power_LCorresponding dutycycle. From formula (11), coupling inductance current increment and PT control Buck changer identical expression formula, Unrelated with inductive value.And distinguish the track being a switch periods internal inductance electric current, Buck changer Inductive current track is broken line AB'D, and improved B uck converter current track is broken line ABCD.

Buck changer variable quantity of output voltage in a switch periods is

${\mathrm{\&Delta;v}}_o\left(nT\right)=\frac{1}{C}{\&Integral;}_{nT}^{(n+1)T}(i_L-I_o)dt---\left(12\right)$

According to Fig. 3 (b), the formula (10) area equal to polygon AB'DE and hatched area ABCB' sum Deduct the area of rectangle AEFG, be then multiplied by 1/C.

Polygon AB'DE area is that PT controls CCM Buck changer peaces produced in a switch periods more Second area, its value is:

$S_{{\mathrm{AB}}^{\&prime;}DE}=\frac{T^2}{2L}(2ED-v_o-{\mathrm{ED}}^2)---\left(13\right)$

Hatched area ABCB' is that PT control improved B uck changer is opened at one relative to Buck changer The ampere-second areas produced in the cycle of pass more, its value is:

$S_{{\mathrm{ABCB}}^{\&prime;}}=\frac{{\mathrm{\&alpha;ED}}^2{T}^2\&lsqb;\mathrm{\&alpha;}E-(1+\mathrm{\&alpha;})v_o\&rsqb;}{2(1-{\mathrm{\&alpha;}}^2){\mathrm{Lv}}_o}---\left(14\right)$

Rectangle AEFG area is:

S_AEFG=| i_L(nT)-I_o| T=-Δ i_Lo(nT)T (15)

In formula, i_Lo(nT) it is the coupling inductance electric current i of the n-th switch periods start time_L(nT) with load current I_oIt Difference.

The voltage increment that can be obtained a switch periods by formula (12)-(15) is:

${\mathrm{\&Delta;v}}_o\left(nT\right)=\frac{T^2}{2LC}(2ED-v_o-{\mathrm{ED}}^2)+\frac{{\mathrm{\&Delta;i}}_{Lo}\left(nT\right)T}{C}+\frac{{\mathrm{\&alpha;ED}}^2{T}^2\&lsqb;\mathrm{\&alpha;}E-(1+\mathrm{\&alpha;})v_o\&rsqb;}{2(1-{\mathrm{\&alpha;}}^2){\mathrm{LCv}}_o}---\left(16\right)$

Fig. 3 (b) only gives a kind of situation of coupling inductance electric current and load current relation, all can obtain for other situations Go out formula (16), do not do at this and repeat to derive.

Use v_oAnd i (nT)_L(nT) the n-th switch periods start time output voltage and coupling inductance electricity are represented respectively Stream, i_p(nT) metal-oxide-semiconductor peak point current in the n-th switch periods is represented, convolution (1), (11), (16), can Obtain PT and control the discrete time mapping model of improved B uck changer output voltage and metal-oxide-semiconductor peak point current.

$\left\{\begin{array}{c}{v}_o(nT+T)=(1-\frac{T^2}{2LC}-\frac{T}{RC})v_o\left(nT\right)+\frac{{\mathrm{\&alpha;}}^2{E}^2{D}^2{T}^2}{2(1-{\mathrm{\&alpha;}}^2)LC}\frac{1}{v_o\left(nT\right)}\\ +\frac{T}{C}{i}_L\left(nT\right)+\frac{{\mathrm{EDT}}^2(2-2\mathrm{\&alpha;}-D)}{2(1-\mathrm{\&alpha;})LC}\\ i_L(nT+T)=-\frac{T}{L}{v}_o\left(nT\right)+i_L\left(nT\right)+\frac{EDT}{L}\\ i_p(nT+T)=i_L\left(nT\right)+\frac{E-v_o\left(nT\right)(1+\mathrm{\&alpha;})}{(1-\mathrm{\&alpha;})L}DT\end{array}\right.---\left(17\right)$

Use the artificial circuit parameter in table 1, with coefficient of coup α for fork parameter, give such as Fig. 4 (a), (b) Output voltage and metal-oxide-semiconductor peak point current bifurcation graphs when shown α excursion is 0.52-0.96.From figure permissible Finding out, PT controls improved B uck changer and there is complicated non-linear behavior.During α increases, defeated Going out voltage and reference voltage generation border collision, Low-Frequency Oscillation Period there occurs and repeatedly suddenlys change.When α excursion During for 0.52-0.64, output voltage fluctuates in the range of 4.65V-5.20V, and metal-oxide-semiconductor peak point current exists Change in the range of 0.6A-2.2A, occur in that low-frequency fluctuation phenomenon；When α is equal to 0.64, changer occurs the Border collision, along with the increase of α, Low-Frequency Oscillation Period occurs repeatedly to suddenly change, when α excursion is During 0.80-0.90, output voltage fluctuates in the range of 4.95V-5.05V, and switching tube peak point current is at 1.0A-2.0A In the range of change, low-frequency fluctuation phenomenon disappear；When α excursion is 0.90-0.96, although do not exist low Frequently oscillatory occurences, but output voltage ripple increases, and metal-oxide-semiconductor peak point current also increases.So at design PT By choosing the suitable coefficient of coup α during control improved B uck changer, in suppression low-frequency fluctuation phenomenon Reduce metal-oxide-semiconductor peak point current simultaneously.

Fig. 5 (a), (b) are respectively PT and control Buck changer and PT control improved B uck changer output Voltage v_o, inductive current i_L, load current I_o, metal-oxide-semiconductor electric current i_QWith control pulse v_GSTime-domain-simulation Waveform.From the time-domain-simulation waveform shown in Fig. 5 (a) it can be seen that PT control Buck changer is the most continuous Selecting high power pulse and low powder pulsed, there is low-frequency fluctuation phenomenon, metal-oxide-semiconductor peak point current is 2.0A； From the time-domain-simulation waveform shown in Fig. 5 (b) it can be seen that PT controls improved B uck convertor controls arteries and veins Punching is 2P_H-1P_L, there is not low-frequency fluctuation phenomenon, metal-oxide-semiconductor peak point current is 1.6A.

Table 1 PT controls improved B uck transducer parameters

Title	Parameter
		Input voltage E	15V
Defeated ginseng to examine voltage V Vref	5V
		Filter capacitor C	470uF
Coupling inductance former limit L1	500uH
		Coupling inductance secondary L2	500uH
Coefficient of coup α	0.86
		Negative height carries the resistance of power electricity arteries and veins and rushes R DH	40.40Ω
Low powder pulsed DL	0.2
		Switching frequency f	20kHz

Claims (2)

1. IMPROVED PULSE DYNAMIC SPRAYING MACHINE sequence controls a Buck changer, is made up of improved B uck changer and PT control circuit, and PT control circuit is sequentially connected is formed by comparator, d type flip flop and door 1# and door 2# or door, driving；Improved B uck changer includes: metal-oxide-semiconductor Q, diode D₁, diode D₂, coupling inductance, output filter capacitor；It is characterized in that, described improved B uck changer is to be developed by Buck topology, is replaced by a pair coupling inductance by the energy storage inductor in Buck changer；Metal-oxide-semiconductor Q drain electrode connects input power positive pole；Metal-oxide-semiconductor Q grid connects the driving signal of PT control circuit；Metal-oxide-semiconductor Q source electrode, diode D₁Negative electrode, coupling inductance former avris Same Name of Ends is connected with each other；Coupling inductance former avris different name end, secondary side Same Name of Ends, the positive pole of output filter capacitor, the positive pole of load are connected with each other；Input power negative pole, diode D₁Anode, diode D₂Anode, the negative electrode of output filter capacitor C, the negative pole of load be connected with each other；Coupling inductance secondary side different name terminating diode D₂Negative electrode.

2. control Buck changer according to the IMPROVED PULSE DYNAMIC SPRAYING MACHINE sequence described in claim 1, it is characterised in that described coupling inductance former avris L₁With secondary side L₂Inductance value is identical and coefficient of coup α span is 0.8 to 0.9.