CN103280973B - A kind of Switching Power Supply of Controlled in Current Mode and Based - Google Patents

Abstract

The present invention relates to switch power technology.The invention discloses a kind of Switching Power Supply of Controlled in Current Mode and Based.Technical scheme of the present invention mainly comprises RS latch, comparator, error amplifying unit, slope-compensation unit, power device, driver element and inductance, described RS latch S holds and connects pwm signal, Q end connects driver element, described comparator output terminal connects the R end of RS latch, and comparator input terminal connects the bucking voltage V of sampled voltage and the output of slope-compensation unit respectively _cp, described error amplifying unit input connects the dividing potential drop of reference voltage and output voltage respectively, and described power device is connected with supply voltage by inductance, also comprises the first compensating signal computing unit and the second compensating signal computing unit.The present invention adopts minimum slope compensating circuit to carry out slope-compensation, not only makes compensation minimum, and minimally compensates with the change of circuit parameter, and the present invention is suitable for the Switching Power Supply of Controlled in Current Mode and Based very much.

Description

A kind of Switching Power Supply of Controlled in Current Mode and Based

Technical field

The present invention relates to switch power technology, particularly the Switching Power Supply slope-compensation technology of Controlled in Current Mode and Based.

Background technology

Prevent push-pull transformer magnetic bias because current mode control circuit has, fast to input voltage change response, feedback loop design is simple, and can improve the advantages such as load current regulation, nowadays Current Control Technology is admitted by everybody and is used widely.But there is the response problem to outputting inductance current disturbing in current mode control circuit.When on power device, the duty ratio of drive singal is less than 50%, disturbing signal is attenuated; But when on power device, the duty ratio of drive singal is greater than 50%, disturbing signal is exaggerated, thus causes vibration.

Solution to the problems described above is, superposes in the output of error amplifier the bucking voltage that a slope is-k (k>0, unit V/ μ s).The value of tradition slope-compensation voltage derives from two places: the first, and the oscillator output voltage of sense circuit, obtains the offset of a fixed slope; The second, get the voltage on the sampling resistor of power device source electrode, obtain a slope-compensation value relevant to supply voltage and inductance value.But minimum slope offset should meet obtain through conversion wherein m ₁(m ₁>0, unit is A/ μ s) be the inductive current rate of rise, m ₂(m ₂>0, unit is A/ μ s) be inductive current descending slope absolute value, R _sfor the sampling resistor resistance of inductive current, D is the duty ratio of drive singal on power device.Visible, slope-compensation value-k is one and m ₁and m ₂the value of being all correlated with, and m ₁and m ₂change all with circuit changes.Traditional slope-compensation value is and m ₁and m ₂all irrelevant fixed value, or only and m ₁relevant value, and compensation can be introduced when duty ratio is less than 50%.So traditional slope-compensation mode has overcompensate, or the situation of undercompensation occurs.

Summary of the invention

In order to overcome traditional slope-compensation meeting overcompensate, or the shortcoming of undercompensation, the present invention proposes a kind of Switching Power Supply of Controlled in Current Mode and Based, adopt minimum slope compensating circuit to carry out slope-compensation, not only make compensation minimum, and minimally compensate with the change of circuit parameter.

The technical scheme that the present invention solve the technical problem employing is, a kind of Switching Power Supply of Controlled in Current Mode and Based, comprise RS latch, comparator, error amplifying unit, slope-compensation unit, power device, driver element and inductance, described RS latch S holds and connects pwm signal, Q end connects driver element, and described comparator output terminal connects the R end of RS latch, and comparator input terminal connects the bucking voltage V of sampled voltage VS and the output of slope-compensation unit respectively _cpdescribed error amplifying unit input connects the dividing potential drop of reference voltage and output voltage respectively, described power device is connected with supply voltage by inductance, it is characterized in that, also comprise the first compensating signal computing unit and the second compensating signal computing unit, described first compensating signal computing unit and the second compensating signal computing unit are connected with two inputs of slope-compensation unit respectively, described first compensating signal computing unit output voltage V ₁=m ₁r _st, described second compensating signal computing unit output voltage described bucking voltage wherein, m ₁for the inductive current rate of rise, m ₂for inductive current descending slope absolute value, R _sfor the sampling resistor resistance of inductive current; V _eAOfor error amplifying unit output voltage; T is the time; V _ofor switch power source output voltage, V _iNfor supply voltage.

Concrete, described power device is insulated gate bipolar transistor or field-effect transistor.

Further, described first compensating signal computing unit and the second compensating signal computing unit are made up of integrated circuit.

Concrete, described integrated circuit adopts BiCMOS technique to make.

Concrete, described integrated circuit adopts BCD technique to make.

The invention has the beneficial effects as follows: required slope-compensation is minimum, can not overcompensate, or undercompensation; Can moment automatic the tuned slope offset, and slope-compensation value can adjust automatically with the change of external circuit parameter, not by external circuit parameter influence, need not carry out design iterations, have general applicability for the circuit of different parameters; When duty ratio is less than 50%, slope-compensation can not be introduced; Offset is little, and load capacity is strong, and load regulation is high, can be operated in continuously and discontinuous mode; During load wide variation, offset changes thereupon, and holding circuit is stablized; Be applicable to integrated, compatible BCD technique and BiCMOS technique.

Accompanying drawing explanation

For making object of the present invention, technical scheme clearly, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in further details.

Fig. 1 is a kind of implementing circuit figure of the present invention;

Fig. 2 is the circuit diagram of Fig. 1 medial error amplifying unit;

Fig. 3 is the circuit diagram of the first compensating signal computing unit in Fig. 1;

Fig. 4 is the circuit diagram of the second compensating signal computing unit in Fig. 1;

Fig. 5 is a kind of implementation of slope-compensation unit in Fig. 1.

Embodiment

The Switching Power Supply of Controlled in Current Mode and Based of the present invention, circuit structure as shown in Figure 1, comprising: error amplifying unit, the first compensating signal computing unit, second compensating signal computing unit, slope-compensation unit, comparator, RS latch, driver element, inductance L, resistance R ₃, the sampling resistor R of inductive current _s, output voltage V _oUTdivider resistance R ₁, R ₂, supply voltage V _iNdivider resistance R ₅, R ₆with a power device.

Fig. 1 is using IGBT as power device, and the power device adopted in the present invention is operated on off state, also can sampled field effect transistor as power device.

In Fig. 1, RS latch S holds and connects pwm signal, and Q end connects driver element.Comparator output terminal connects the R end of RS latch, and comparator input terminal connects the sampled voltage VS of inductive current and the bucking voltage V of slope-compensation unit output respectively _cp.Error amplifying unit input connects reference voltage V respectively _refwith output voltage V _oUTdividing potential drop VB.The output EAO of error amplifying unit connects slope-compensation unit, by the error amplifier in error amplifying unit, dividing potential drop VB is limited in reference voltage V _refplace, regulated output voltage V _oUT.The collector electrode of power device IGBT is by inductance L and supply voltage V _iNconnect.First compensating signal computing unit and the second compensating signal computing unit are connected with two inputs of slope-compensation unit respectively.

In Fig. 1, resistance R ₁, R ₂form output voltage V _oUTbleeder circuit, wherein resistance R ₂one end ground connection, the other end exports dividing potential drop VB, resistance R ₁a termination export output voltage V _oUT, other end connecting resistance R ₂.Resistance R ₅, R ₆form the bleeder circuit of input voltage, wherein resistance R ₆one end ground connection, other end output voltage VC, resistance R ₅a termination input voltage V _iN, other end connecting resistance R ₆.Resistance meets relational expression: be connected on the sampling resistor R of IGBT emitter _sone end ground connection, other end outputting inductance current sample voltage VS, resistance R _sit is exactly the sampling resistor of inductive current.Inductance L, diode D ₁with electric capacity C _oform current rectifying and wave filtering circuit, R _ofor load resistance.

In Fig. 1, the first input end of the first compensating signal computing unit meets sampled voltage V _s, the source electrode of IGBT and the inverting input of comparator, the grid of IGBT meets resistance R ₃, drain electrode meets inductance L and diode D ₁anode, another termination power V of inductance _iN, diode D ₁negative electrode meet load resistance R _o.Second output QN of the second input termination RS latch of the first compensating signal computing unit, exports the first input end of termination second compensating signal computing unit and the second input of slope-compensation unit.First compensating signal computing unit produces one and inductive current rate of rise m ₁proportional output voltage V ₁=m ₁r _st.

In Fig. 1, the first input end of the second compensating signal computing unit meets the output voltage V of the first compensating signal computing unit ₁, the second input termination voltage V _c, the 3rd input termination voltage V _oUT, export the 3rd input of termination slope-compensation unit.Second compensating signal computing unit produces a voltage

The first input end of slope-compensation unit of the present invention meets the output voltage V of error amplifying unit _eAC, the output V1 of the second input termination first compensating signal computing unit, the output V2 of the 3rd input termination second compensating signal computing unit, exports the in-phase input end of termination comparator.Slope-compensation unit realizes the output voltage after compensating wherein V _eAOfor the output voltage of error amplifier.

The output of the R termination comparator of RS latch of the present invention, the square wave oscillation signal of S termination fixed frequency and pulsewidth, the first output Q connects driver element, and wherein the output of driver element is by resistance R ₃drive the grid of IGBT, the second output QN connects the second input of the first compensating signal computing unit.RS latch first output Q output switch control signal, the output voltage of the second output QN to the first compensating signal computing unit resets simultaneously.

The present invention obtains voltage V by the first signal compensation unit ₁=m ₁r _st, obtains voltage by secondary signal compensating unit $V_2=\frac{V_O}{V_{\mathrm{IN}}}{m}_1{R}_{S}t,$ Output voltage after being compensated by slope-compensation unit again $V_{\mathrm{CP}}=V_{\mathrm{EAO}}-\frac{1}{2}(m_2-m_1)R_{S}t,$ Use V _cPwith sampling resistor R _son voltage V _scompare, control the conducting of power device.

Fig. 2 is a kind of implementation circuit diagram of Fig. 1 medial error amplifying unit.Resistance R ₁₁with electric capacity C ₁₁be connected in parallel on operational amplifier A MP ₁₁output and reverse input end, R ₁₂a termination operational amplifier A MP ₁₁inverting input, the first input end V of another termination error amplifying unit _b, operational amplifier A MP ₁₁in-phase input end meet reference voltage V _ref.The in-phase input end of error amplifier meets reference voltage V _ref, anti-phase input termination V _b.The Main Function of error amplifying unit of the present invention is by voltage V _bbe limited in reference voltage V _refplace, regulated output voltage V _oUT.

Fig. 3 is a kind of implementation circuit diagram of the first compensating signal computing unit in Fig. 1.Resistance R ₂₁, R ₂₂, R ₂₃with operational amplifier A MP ₂₁form anti-phase proportion operational amplifier, by voltage V/ _s=m ₁r _st+A ₁, be converted into voltage V _s1=-m ₁r _st-A ₁, wherein A ₁for DC level.Resistance R ₂₄, R ₂₅, electric capacity C ₂₁with operational amplifier A MP ₂₂form differential circuit, by voltage V _s1be converted into voltage resistance R ₂₇, metal-oxide-semiconductor M ₂₁, M ₂₃, M ₂₄, electric capacity C ₂₃, operational amplifier A MP ₂₃form integrating circuit, by voltage V _dbe converted into electric current wherein resistance R ₂₄=R ₂₇, then use electric current I _dto electric capacity C ₂₃charging, obtains output voltage V ₁=m ₁r _st, wherein metal-oxide-semiconductor M ₂₃, M ₂₄image current equal, electric capacity C ₂₁=C ₂₃.First compensating signal computing unit draws one and inductive current rate of rise m ₁proportional voltage V ₁.

Fig. 4 is a kind of implementation of the second compensating signal computing unit in Fig. 1.Resistance R ₃₁, metal-oxide-semiconductor M ₃₁, M ₃₂, operational amplifier A MP ₃₁make voltage V _brise a threshold voltage V _tH, obtain a V _b+ V _tHvoltage; In like manner, resistance R ₄₂, metal-oxide-semiconductor M ₃₃, M ₃₄, operational amplifier A MP ₃₆make voltage V _crise a threshold voltage V _tH, obtain a V _c+ V _tHvoltage.Resistance R ₃₂, R ₃₃, R ₃₄, R ₃₅, R ₃₆with operational amplifier A MP ₃₃composition operational amplifier, wherein obtaining an output is voltage; In like manner, resistance R ₄₃, R ₄₄, R ₄₅, R ₄₆, R ₄₇with operational amplifier A MP ₃₈composition operational amplifier, wherein obtaining an output is voltage.Resistance R ₃₇, R ₃₈, R ₃₉, R ₄₀, R ₄₁with operational amplifier A MP ₃₂, AMP ₃₄, AMP ₃₅form adder operation circuit, wherein, operational amplifier A MP ₃₂, AMP ₃₄play buffer action, resistance $R_{39}=R_{40}=R_{41}=3R_{37}=\frac{3}{2}{R}_{38},$ Obtaining output voltage is $V_B+V_{\mathrm{TH}}+\frac{1}{2}{V}_A;$ In like manner, resistance R ₄₈, R ₄₉, R ₅₀, R ₅₁, R ₅₂with operational amplifier A MP ₃₇, AMP ₃₉, AMP ₄₀form adder operation circuit, wherein, operational amplifier A MP ₃₇, AMP ₃₉play buffer action, resistance $R_{50}=R_{51}=R_{52}=3R_{48}=\frac{3}{2}{R}_{49},$ Obtaining output voltage is $V_C+V_{\mathrm{TH}}+\frac{1}{2}{V}_2.$ Be operated in the electric current I of the metal-oxide-semiconductor of linear zone _dSexpression formula:

$I_{\mathrm{DS}}=\mathrm{C\μ}\frac{W}{L}[(V_{\mathrm{GS}}-V_{\mathrm{TH}})V_{\mathrm{DS}}-\frac{1}{2}{V}_{\mathrm{DS}}^2]$

Wherein, C is the electric capacity of gate oxide unit are, and μ is the mobility in electric charge (electronics or hole), and W is the channel width of metal-oxide-semiconductor, and L is the channel length of metal-oxide-semiconductor.Metal-oxide-semiconductor M ₃₇and M ₃₈be operated in linear zone, so, metal-oxide-semiconductor M ₃₇electric current I _dS37expression formula:

$I_{\mathrm{DS}37}=\mathrm{C\μ}\frac{W}{L}[(V_B+V_{\mathrm{TH}}+\frac{1}{2}{V}_A-V_{\mathrm{TH}})V_A-\frac{1}{2}{V}_A^2]=\mathrm{C\μ}\frac{W}{L}{V}_B{V}_A$

Metal-oxide-semiconductor M ₃₇conducting resistance r _on37expression formula:

$r_{\mathrm{on}37}=\frac{1}{\mathrm{C\μ}\frac{W}{L}{V}_B}$

In like manner, metal-oxide-semiconductor M ₃₈electric current I _dS38expression formula:

$I_{\mathrm{DS}38}=\mathrm{C\μ}\frac{W}{L}[(V_C+V_{\mathrm{TH}}+\frac{1}{2}{V}_2-V_{\mathrm{TH}})V_2-\frac{1}{2}{V_2}^2]=\mathrm{C\μ}\frac{W}{L}{V}_C{V}_2$

Metal-oxide-semiconductor M ₃₈conducting resistance r _on38expression formula:

$r_{\mathrm{on}38}=\frac{1}{\mathrm{C\μ}\frac{W}{L}{V}_C}$

According to amplifier AMP ₄₁the short principle of void of two inputs, obtains V _a=V ₁, so, obtain metal-oxide-semiconductor M ₃₇electric current because the image current of metal-oxide-semiconductor M35 and M36 is equal, obtain:

$V_2=\mathrm{C\μ}\frac{W}{L}{V}_B{V}_1*\frac{1}{\mathrm{C\μ}\frac{W}{L}{V}_C}=\frac{V_B}{V_C}{V}_1=\frac{V_{\mathrm{OUT}}}{V_{\mathrm{IN}}}{V}_1=\frac{V_{\mathrm{OUT}}}{V_{\mathrm{IN}}}{m}_1{R}_{S}t$

Wherein, resistance $\frac{R_1}{R_2}=\frac{R_5}{R_6}.$

First compensating signal computing unit of the present invention and the second compensating signal computing unit are made up of integrated circuit, and can be integrated in same chip with other control circuits of Switching Power Supply, integrated circuit technology can adopt BiCMO technique or BCD technique.

Fig. 5 is a kind of implementation of slope-compensation unit in Fig. 1.Resistance R ₅₁, metal-oxide-semiconductor M ₅₁, M ₅₂, M ₆₁, operational amplifier A MP ₅₁form a Voltage-current conversion circuit, obtain an output current resistance R ₅₂, metal-oxide-semiconductor M ₅₃, M ₅₄, M ₆₀, operational amplifier A MP ₅₂form a Voltage-current conversion circuit, obtain an output current resistance R ₅₄r54, metal-oxide-semiconductor M ₅₅, M ₅₆, M ₅₉, operational amplifier A MP ₅₃form a Voltage-current conversion circuit, obtain an output current $I_{\mathrm{EAO}}=\frac{V_{\mathrm{EAO}}}{R_{54}}.$ Resistance $R_{54}=R_{53}=R_{51}=\frac{1}{2}{R}_{52},$ Inductive current descending slope m ₂with inductive current rate of rise m ₁pass be:

$m_2=(\frac{V_{\mathrm{OUT}}}{V_{\mathrm{IN}}}-1)m_1$

So, obtain output voltage:

$V_{\mathrm{CP}}=[I_{\mathrm{EAO}}-(I_{V2}-I_{V1})]R_{53}=V_{\mathrm{EAO}}-\frac{1}{2}(\frac{V_{\mathrm{OUT}}}{V_{\mathrm{IN}}}{V}_1-V_1-V_1)=V_{\mathrm{EAO}}-\frac{1}{2}(m_2-m_1)R_{S}t$

V _cPjust be through the output voltage that minimum slope compensates.

Claims (5)

1. the Switching Power Supply of a Controlled in Current Mode and Based, comprise RS latch, comparator, error amplifying unit, slope-compensation unit, power device, driver element and inductance, described RS latch S holds and connects pwm signal, Q end connects driver element, described comparator output terminal connects the R end of RS latch, and comparator input terminal connects the bucking voltage V of sampled voltage VS and the output of slope-compensation unit respectively _cpdescribed error amplifying unit input connects the dividing potential drop of reference voltage and output voltage respectively, described power device is connected with supply voltage by inductance, it is characterized in that, also comprise the first compensating signal computing unit and the second compensating signal computing unit, described first compensating signal computing unit and the second compensating signal computing unit are connected with two inputs of slope-compensation unit respectively, described first compensating signal computing unit output voltage V ₁=m ₁r _st, described second compensating signal computing unit output voltage described bucking voltage wherein, m ₁for the inductive current rate of rise, m ₂for inductive current descending slope absolute value, R _sfor the sampling resistor resistance of inductive current; V _eAOfor error amplifying unit output voltage; T is the time; V _ofor switch power source output voltage, V _iNfor supply voltage.

2. the Switching Power Supply of a kind of Controlled in Current Mode and Based according to claim 1, is characterized in that, described power device is insulated gate bipolar transistor or field-effect transistor.

3. the Switching Power Supply of a kind of Controlled in Current Mode and Based according to claim 1 and 2, is characterized in that, described first compensating signal computing unit and the second compensating signal computing unit are made up of integrated circuit.

4. the Switching Power Supply of a kind of Controlled in Current Mode and Based according to claim 3, is characterized in that, described integrated circuit adopts BiCMOS technique to make.

5. the Switching Power Supply of a kind of Controlled in Current Mode and Based according to claim 3, is characterized in that, described integrated circuit adopts BCD technique to make.