CN103312198B - ON time for switching power converter compensates - Google Patents

Abstract

A kind of intermittent conductive pattern (DCM) switching power converter compensating the improvement of the impact of Dead Time.During switch periods, measure the Dead Time of switching power converter, and determine the benchmark ON time of the switch of switching power converter.Dead Time and benchmark ON time are for calculating the ON time of the switch of the expectation during the follow-up switch periods of compute switch at power inverter.Output voltage is adjusted to the voltage level of expectation by the switch conduction times expected.The switch conduction times duration expected also be maintained until the average current input of power inverter and input voltage substantially proportional, improve the power factor of switching power converter thus.

Description

ON time for switching power converter compensates

the cross reference of related application

This application claims on March 15th, 2012 submit the 61/611st, the priority of No. 473 U.S. Provisional Applications, its disclosure is all incorporated into this by way of reference.

Technical field

Present disclosure relates to switching power converter, and the ON time for switching power converter relating more specifically to improve compensates.

Background technology

Switching power converter in many distinct electronic apparatuses for generating the output voltage that regulates with the level of the output voltage regulated by cyclically conducting and cut-off switch according to input voltage.Some power inverters operate with intermittent conductive pattern (DCM).In DCM, actuating switch allows electric current to flow in the inductor of switching power converter.Then cut-off switch allows outflow of bus current inductor and flows out towards load, resets inductor thus.Dead Time is inserted, the switching frequency of this dead band time restriction switch after the replacement time.If have voltage ring in the top side of switch, then can revise the length of Dead Time to allow to occur this switch motion at the trough of ring.

But insert Dead Time has the power factor reducing switching power converter counter productive for the power quantity reducing loss in switch itself.The power delivery system of AC power, such as power utility transmission line are supplied in the power factor impact of power inverter to power inverter.If the power factor of converter is low, then utility companies must waste more power with to load conveying needed for power.In order to maximum power factor, the average current input to switching power converter should be proportional with input voltage.Having fixing ON time, without in the power inverter of Dead Time, average current input is naturally proportional with input voltage, and can realize good power factor.But in the power inverter with Dead Time, the level of the effect length average current input of Dead Time and average current input is departed from from input voltage is proportional.Thus Dead Time reduces the power factor of power inverter.

Summary of the invention

A kind of embodiment of DCM switching power converter of improvement compensates the impact of Dead Time duration when calculating the ON time duration.During switch periods, measure the Dead Time duration of switching power converter, and determine the benchmark ON time duration of the switch of switching power converter.Dead Time duration and benchmark ON time duration are for calculating the ON time duration of the switch of the expectation for follow-up switch periods.Output voltage is adjusted to the voltage level of expectation by the switch conduction times duration expected.The switch conduction times duration expected also be maintained until the average current input of power inverter and input voltage substantially proportional, make power inverter show as resistive load thus and improve the power factor of switching power converter.

In one embodiment, a kind of switching power converter comprises: magnet assembly, is coupling between the input voltage of switching power converter and output voltage.Switch is coupled to magnet assembly to control to flow through the electric current of magnet assembly.The electric current flowed in magnet assembly increases when switch conduction and is reduced to constant current level when switch disconnects.Controller is configured to generate for conducting or the control signal disconnecting this switch, and this switching response is in the first state and conducting in this control signal, and this switching response is in the second state in this control signal and disconnects.Controller is also configured to the Dead Time duration of the first switch periods determining power inverter, the Dead Time duration is the following time remaining time, at the duration of this time, the electric current flowed in magnet assembly is in constant current level.Controller is also configured to the ON time duration of the switch determining the expectation in the second switch cycle for power inverter based on the Dead Time duration in the first switch periods, and the second switch cycle is after the first switch periods.Additionally, controller is also configured to the described control signal being in the described first time remaining time of state continuance for switch according to the ON time duration generation conducting of described expectation of described second switch cycle.

In one embodiment, controller is also configured to the benchmark ON time duration determining switch.If it is zero that the benchmark ON time duration can represent Dead Time, output voltage is adjusted to expect voltage level, ON time duration of switch.Then controller determines the ON time duration expected based on benchmark ON time duration and the Dead Time duration in the first switch periods.The ON time duration of the simplified function calculation expectation that can calculate with the mathematical function or quardratic free root with square root calculating, this square root calculates and relates to the benchmark ON time duration.The ON time that the linear segmented approximation computation that also can calculate with square root is expected is to reduce the circuit of the ON time duration needed for calculation expectation.

In one embodiment, a kind of method of operation in switching power converter, comprise the Dead Time duration of the first switch periods determining switch, Dead Time is the duration of following time, at the duration of this time, the electric current flowed in magnet assembly is in constant current level.The method also comprises determines ON time duration of the switch of the expectation for the second switch cycle based on the Dead Time duration in the first switch periods, and the second switch cycle is after the first switch periods.The method also comprises for the second switch cycle according to the control signal that be in the time cycle of a first state continuance time of the ON time duration generation expected for this switch of conducting.

In one embodiment, a kind of controller for switching power converter comprises: ON-OFF control circuit, be arranged to the control signal generated for conducting or cut-off switch, this switching response is in the first state and conducting in control signal, and this switching response is in the second state in control signal and disconnects.This controller is arranged to the Dead Time duration of the first switch periods determining this switch, the Dead Time duration is duration of following time, at this time remaining time durations, the electric current flowed in magnet assembly is being in constant current level substantially.This controller is arranged to determines ON time duration of the switch of the expectation for the second switch cycle based on the Dead Time duration in the first switch periods, and the second switch cycle is after the first switch periods.ON-OFF control circuit is configured to for the second switch cycle according to the control signal that be in the time cycle of a first state continuance time of the ON time duration generation expected for this switch of conducting.

Feature and advantage described are not in the description all-embracing, and specifically, consider drawing and description, many supplementary features and advantage will be apparent for those skilled in the art.In addition, it should be noted that the wording used in specification is selected in order to object that is readable and that introduce in principle, instead of select to define or to limit theme of the present invention.

Accompanying drawing explanation

Consider following detailed description in conjunction with the drawings, will the instruction understanding embodiment disclosed herein be easier to.

Fig. 1 diagram is according to the switching power converter of an embodiment.

Fig. 2 A illustrate according to an embodiment for the input voltage of switching power converter and the waveform of output voltage.

Fig. 2 B illustrates the switch Q1 ON time in time according to the switching power converter of an embodiment.

Fig. 2 C illustrates the operation waveform for switching power converter according to an embodiment.

Fig. 3 illustrates the power controller of the switching power converter according to an embodiment in more detail.

Fig. 4 diagram according to an embodiment for evaluation piecewise linear approximation.

Fig. 5 illustrates the boosting rectifier control block of the power controller according to an embodiment in more detail;

Fig. 6 diagram is according to the method for operation in the power controller of an embodiment.

Fig. 7 A is shown in the waveform to the average current input of power inverter when not compensating ON time.

Fig. 7 B illustrate according to an embodiment when compensating ON time to the waveform of the average current input of power inverter.

Embodiment

Accompanying drawing and following explanation relate to various embodiment only by illustrated mode.It should be noted that from following discussion, the alternative embodiment of structure disclosed herein and method will easily be considered to be at do not depart from herein principle situation is discussed under adoptable feasible replacement.

Referring now to some embodiments of the present invention, illustrate its example in the accompanying drawings.Notice, as long as feasible, similar or identical Reference numeral can be used in accompanying drawing and it indicates similar or identical function.Accompanying drawing only describes the embodiment of present disclosure for purposes of illustration.Those skilled in the art easily recognize from hereafter describe, and can utilize the alternate embodiments of illustrated structure and method herein when not departing from principle described herein.

Embodiment disclosed herein relates to a kind of DCM switching power converter of improvement, and it compensates the impact of Dead Time.During switch periods, measure the Dead Time duration of switching power converter, and determine the benchmark ON time duration of the switch of switching power converter.Dead Time and benchmark ON time duration are used to calculate the ON time duration for the expectation of follow-up switch periods.Output voltage is adjusted to the voltage level of expectation by the switch conduction times duration expected.The switch conduction times duration expected also be maintained until the average current input of power inverter and input voltage substantially proportional, improve the power factor of switching power converter thus.

Fig. 1 diagram is according to the example switch power inverter 100 of an embodiment.As shown in the figure, power inverter 100 is AC to DC booster converters, but can design other topologys with the switch mode power converters that ON time compensates according to instruction described herein.Such as in one embodiment, switch mode power converters 100 can be inverse excitation type converter, instead of booster converter.

In front end, switching power converter 100 comprises the bridge rectifier BR1 receiving and exchange (AC) input voltage VAC.But bridge rectifier BR1 carries out rectification to ac input voltage VAC and generates the unadjusted input voltage 112 of rectification.The input voltage 112 of rectification is applied to the input side of inductor L1.In other embodiments, inductor L1 can be the magnetic energy memory module of another type, such as transformer.

Controller 102 maintains Drazin inverse via the conducting of the control signal 110 control switch Q1 exported from controller 30 and off-state.In one embodiment, controller 30 is application-specific integrated circuit (ASIC) (ASIC) and generates control signal 30 according to ON time compensation technique described herein.

The control terminal of control signal 110 driving switch Q1.In the embodiment shown in fig. 1, switch Q1 is bipolar junction transistor (BJT), and therefore control terminal is base stage (B) terminal of switch Q1.Collector electrode (C) and the inductor L1 of switch Q1 are connected in series.Emitter (E) ground connection of switch Q1.In other embodiments, switch Q1 can be the transistor of another type, such as MOSFET or can disconnect in a controlled manner or other device any of closed circuit.In one embodiment, controller 102 can use pulse-width modulation (PWM) with the conducting of control BJT power switch Q1 and off-state and duty ratio, and the amplitude of the base current of BJT switch Q1.

Along with switch Q1 conducting and disconnection, it generates the output voltage 114 providing the adjustment of power to load (not shown).Specifically, when switch Q1 conducting, through transistor Q1 generation current path, it makes the electric current 132 in inductor L1 increase, thus stored energy in inductor L1.When switch Q1 disconnects, along with electric current 132 flows through diode D1 to charge to capacitor C1 from inductor 132, the energy in inductor L1 reduces.The switch motion of switch Q1 thus control is flow through the electric current 132 of inductor L1 and is generated the output voltage 114 regulated.Because power inverter 100 is booster converters, so the output voltage 114 regulated has the voltage level higher than the input voltage 112 of rectification.

The input voltage 112 of resistor R1 and R2 to rectification carries out dividing potential drop to generate the voltage input sensing signal 120 of the input voltage 112 following the tracks of rectification.Resistor R3 and R4 to output voltage 114 dividing potential drop regulated to generate the output voltage sensing signal 122 of output voltage 114 following the tracks of adjustment.At the voltage of collector electrode place of switch Q1 referred to herein as collector voltage 116.Via the collector voltage sensing signal 124 following the tracks of collector voltage 116 level, collector voltage 116 is provided to power controller 102.In certain embodiments, replace the output being connected to inductor L1, collector voltage sensing signal 124 can be connected to the secondary winding of inductor L1 with the differential voltage of sensing across inductor L1.As will be described in more detail, input voltage sensing signal 120, output voltage sensing signal 122 and collector voltage sensing signal 124 are used for controlling the ON time of transistor Q1 by power controller 102.

Fig. 2 A illustrate according to an embodiment for the input voltage 112 of switching power converter 100 and the waveform of output voltage 114.Horizontal axis plots time, and longitudinal axis representative voltage level.As shown in the figure, the input voltage 112 of adjustment is periodic signal.The input voltage 112 regulated operates under frequency such as between 100-120Hz of the twice of the frequency of ac input voltage VAC, thus to be approximately 8-10ms long each cycle of input voltage 112.The average voltage level of the input voltage 112 regulated is lower than the average voltage level of output voltage 114 regulated.Such as, the average level of the output voltage 114 of adjustment can more than the peak value of input voltage 112 30 volts.

Fig. 2 B illustrates the switch Q1 ON time duration in time according to the power inverter 100 of an embodiment.Horizontal axis plots time, and the ON time duration of longitudinal axis representation switch Q1 (i.e. the duration of the time of switch Q1 conducting).The ON time duration of switch Q1 increases in time and reduces to maintain the adjustment of output voltage 114 and also to increase the power factor of power inverter 100.In one embodiment, power controller 102 arranges the ON time duration of switch Q1 based on the factor that the Dead Time duration of the level of such as input voltage 112, the level of output voltage 114, the benchmark ON time duration of switch Q1 and power inverter 100 is such.

With reference to Fig. 2 C, illustrated is the operation waveform for switching power converter 100 according to an embodiment.At the top of figure, collector voltage 116 is shown, the switch controlling signal 110 for switch Q1 is shown at the middle part of figure, and illustrate from the electric current 132 bridge rectifier BR1 inflow inductor L1 in the bottom of figure.

The duration extending to the time of time D from time A represents a switch periods of power inverter 100.The time remaining time extended from D time, F elapsed time represents another switch periods.From time A to the part of the total length of time of time F only time shown in representative graph 2A shown in Fig. 2 C.Such as, x-axis representative in Fig. 2 A and Fig. 2 B amounts to the time of 16ms, and Fig. 2 C only may illustrate the temporal operation of power inverter 100 at 0.1ms.Therefore, in each line cycle of input voltage 114, many switch periods are had.

At time A, switch controlling signal 110 uprises (HIGH) and actuating switch Q.Switch Q1 becomes short circuit in fact, and therefore collector voltage 116 is zero volts.Between time A and B, the electric current 132 flowed in inductor L1 increases due to the current path through switch Q1.

At time B, switch controlling signal 110 step-down (LOW) and cut-off switch Q.Energy in inductor L1 is released through diode D1, and the electric current 132 flowed in inductor L1 starts to reduce until it reaches constant zero current level at time C.When flowing into the electric current 132 in inductor and reaching zero current level, inductor is regarded as " replacement ", because it has lost its most energy.Therefore period between time B and time C is called as " inductor reset stage ".During inductor reset stage, the voltage level that collector voltage 116 has can be higher than the voltage level of the input voltage 112 of rectification.

At time C, diode D1 stops conducting and no longer draws electric current 132 from inductor L.Electric current 132 in inductor L1 is essentially zero and constant between time C and D, to flow into because do not exist or to flow out the current path of inductor L1 for electric current 132.Time period between C and D is being called " Dead Time " due to the electric current 132 lacked in inflow inductor L1 herein.In addition, once diode D1 stops conducting at time C, it causes inductor L1 resonance and produce ring in collector voltage 116.Due to the various damping in power inverter 100 and loss factor, collector voltage 116 is attenuated sinusoidal signal between time C and time D.

At time D, switch Q1 again conducting to start another switch periods.Power inverter 100 the time D, E with the operation of F to substantially similar with the operation that C describes about time A, B.In one embodiment, power controller 102 can measure the Dead Time duration between period C and D, then uses the Dead Time duration of measurement to adjust the ON time duration of switch Q1 during time D and E.By adjusting the length of the switch conduction times duration in follow-up switch periods based on the Dead Time in previous switching period, can be maintained until the average current input 132 of inductor L1 pro rata with the input voltage 116 of rectification, this increases the power factor of power inverter 100.

Fig. 3 illustrates the power controller 102 of the switching power converter 100 according to an embodiment in more detail.Power controller 102 comprises some main circuit blocks, and these circuit blocks comprise boosting rectifier control block 302, ON time computing block 304, switch control block 306 and Dead Time survey mass 308.Controller 102 also comprises some analog to digital converters (ADC) 310 and 312.ADC310 converts input voltage sensing signal (VinSense) 120 to one or more digital input voltage signal (Vin_DIG) 220.The value of numeral input voltage signal 220 corresponds to the level of input voltage sensing signal 120 and the level of indirect indicative input voltage 112.ADC312 converts modulating output sensing signal (VoutSense) 122 to one or more digital output voltage signal (Vout_DIG) 322.The value of digital output voltage signal 322 corresponds to the level of voltage sense signal 122 and the level of indirect instruction output voltage 114.Then remaining circuit block uses digital circuit to process these digital signals 320,322 with generation for the output voltage 114 of by-pass cock power inverter 100 and the switch controlling signal 110 maintaining good power factor.In other embodiments, can replace by analog circuit or the part implementing power controller 102 with the form of the software run on a microcontroller instead of digital circuit.

Boosting rectifier control block 302 receives digital input voltage signal 320 and digital output voltage signal 322 and generates one or more benchmark ON time signal 324.Benchmark ON time signal 324 comprises following digital value, and the representative of this digital value is used for the setting of the benchmark ON time duration of switch Q1.In one embodiment, under following hypothesis: (1) inductor is completely reset in each switch periods and (2) have zero Dead Time, then the benchmark ON time duration is the ON time duration of the voltage level of the expectation by causing the output voltage 114 regulated of switch Q1.The benchmark ON time duration can be adjusted to obtain the boost in voltage level of the expectation of the output voltage 114 regulated.The benchmark ON time duration also dynamically can change any change tackled in the load of switching power converter 100.

Boosting rectifier control block 302 periodically determines the benchmark ON time duration according to digital input voltage signal 320 and digital output voltage signal 322.In one embodiment, boosting rectifier control block 202 in each line cycle (such as every 8.3ms) of the input voltage 114 of rectification only the Calculation Basis ON time duration once, instead of each switch periods of switch Q1 (such as every 0.1ms).In other embodiments, boosting rectifier control block 202 can at different cycles interval, such as, in each switch periods or in every multiple switch periods Calculation Basis ON time duration.Hereafter illustrate in greater detail boosting rectifier control block 302 with reference to Fig. 5.

Dead Time survey mass 308 receives collector voltage sensing signal 124 and generates one or more Dead Time duration signal 225.Dead Time duration signal 226 comprises following digital value, the duration of the Dead Time of this digital value representative during switch periods.In one embodiment, during each switch periods of switch Q1, recalculate the duration of Dead Time, thus Dead Time can be compensated during follow-up switch periods.

Dead Time survey mass 308 can with the duration of any mode determination Dead Time in multiple different modes.In one embodiment, the beginning of Dead Time passes through threshold voltage instruction by the trailing edge of collector voltage sensing signal 124.Collector voltage sensing signal 124 represents in another embodiment across the differential voltage of inductor L1 wherein, from proper decline towards zero volt collector voltage sensing signal 124 before the beginning of point in time measurement Dead Time.In one embodiment, the end of Dead Time is by making effectively to indicate with the control signal of actuating switch Q1.

ON time computing block 304 receives benchmark ON time signal 324, Dead Time duration signal 226, digital input voltage signal 320 and digital output voltage signal 322 and generates one or more the ON time signal 328 expected for the ON time duration of control switch Q1.ON time signal 328 comprises following digital value, the ON time duration of the switch Q1 of the expectation of these digital values representative during switch periods.ON time computing block 304 to carry out the ON time duration of calculation expectation by the adjustment benchmark ON time duration with the impact compensating the Dead Time duration.In one embodiment, ON time computing block 304 calculates the ON time duration in order to minor function:

$t_{on}=\frac{t_{on\_orig}}{2}+\sqrt{\frac{t_{on\_orig}^2}{4}+t_{on\_orig}{t}_3\frac{V_o-V_{in}}{V_o}}$ (equation 1)

Wherein t _onrepresentative as determined by ON time computing block 304, ON time duration of transistor Q1 of expecting.T _{on_orig}representative is as the benchmark ON time duration determined by boosting rectifier control block 302.T ₃representative is as the Dead Time duration determined by Dead Time survey mass 308.V _orepresentative is as the instantaneous output voltage level indicated by the value of output voltage signal 322.V _inrepresentative is as the instantaneous input voltage level indicated by the value of input voltage signal 320.

Equation 1 is therefore according to the ON time of the switch Q1 of benchmark ON time duration, Dead Time duration, input voltage and output voltage calculation expectation.The ON time duration expected increases along with the benchmark ON time duration and increases, and increases and increase along with the Dead Time duration, increases and increase and increase along with input voltage and reduce along with output voltage.The ON time duration expected is usually longer than the benchmark ON time duration due to Dead Time.In addition, the ON time duration expected makes to the input current 132 of inductor L1 relatively proportional with the input voltage 112 of rectification.Thus the power factor of power inverter 102 is added.

In one embodiment, the blind area time remaining time during each switch periods.Once determine the Dead Time duration, then the ON time duration of calculation expectation, thus in follow-up switch periods (by next immediately switch periods or switch periods after a while) period, can be set according to the ON time duration expected the ON time duration of switch Q1.Such as, look back Fig. 2 C, a switch periods extends to time D from time A.Another switch periods starts from time D and extends past time F.During the first switch periods, the Dead Time duration between time C and time D can be measured.Once this Dead Time duration is known, it is used to the ON time duration of calculation expectation to be arranged on the ON time duration of the switch Q1 between time D and time E during next switch periods.

Can according to following relation derivation equation 1.Consider as shown in Figure 2 C with the power inverter 100 of DCM pattern operation, wherein d1 is ON time duty ratio, d2 is that inductor resets duty ratio, d3 is Dead Time duty ratio, m1 is the slope of inductor L1 electric current 132 during ON time, m2 is at the slope resetting time durations inductor L1 electric current 132, and Ts is switch periods.In DCM boost operations, following relation is set up:

$m_1=\frac{V_{in}}{L_m}$

$m_2=\frac{V_o-V_{in}}{L_m}$

d ₂T _sm ₂＝d ₁T _sm ₁

L _mit is the inductance of inductor L1.By these relations, can determine:

$d_2=\frac{d_1{T}_s{m}_1}{T_s{m}_2}=\frac{d_1{m}_1}{m_2}=\frac{d_1\frac{V_{in}}{L_m}}{\frac{V_o-V_{in}}{L_m}}=\frac{d_1{V}_{in}}{V_o-V_{in}}$

$<I_L>=\frac{I_{max}}{2}(d_1+d_2)=\frac{d_1{T}_s{m}_1}{2}(d_1+\frac{d_1{V}_{in}}{V_o-V_{in}})$

$<I_L>=\frac{d_1^2{T}_s{m}_1}{2}\frac{V_o}{V_o-V_{in}}=\frac{d_1^2{T}_s{m}_1{V}_o}{2(V_o-V_{in})}=\frac{d_1^2{T}_s{V}_{in}{V}_o}{2L_m(V_o-V_{in})}$

<I _l> is the average inductor current in switch periods.I _maxit is the peak inductor current during switch periods.Solve the d of above formula ₁produce:

$d_1=\sqrt{\frac{2L_m<I_L>(V_o-V_{in})}{T_s{V}_{in}{V}_o}}$

If or solve its V _o:

$V_o=\frac{2<I_L>L_m{V}_{in}}{2<I_L>L_m-T_s{V}_{in}{d}_1^2}$

In addition, following relation exists due to power conservation:

$I_{in}=<I_L>=\frac{I_o{V}_o}{V_{in}}$

I _init is the input current to inductor L1.Therefore for V _oabove-mentioned formula can be rewritten as:

$V_o=\frac{T_s{V}_{in}^2{d}_1^2+2I_o{L}_m{V}_{in}}{2I_o{L}_m}$

Therefore, and wherein R _lrepresent load resistance and I _orepresent the electric current to load supply.Therefore:

$\frac{V_o}{V_{in}}=\frac{R_L{T}_s{V}_{in}{d}_1^2+2L_m{V}_o}{2L_m{V}_o}$

Now $I_{max}=t_1{m}_1=t_2{m}_2=t_1\frac{V_{in}}{L_m}=t_2\frac{V_o-V_{in}}{L_m}$ And $t_2=\frac{V_{in}{t}_1}{V_o-V_{in}},$ Wherein t ₁be duration of the ON time during switch periods and t ₂it is the duration of the inductor replacement time during switch periods.Therefore average current input is:

$I_{in}=\frac{I_{max}}{2}\frac{t_1+t_2}{t_1+t_2+t_3}$

Input inductance is ${\mathrm{gm}}_{in}=\frac{I_{in}}{V_{in}}.$ Substitute into $I_{max}=t_1\frac{V_{in}}{L_m}$ With $t_2=\frac{V_{in}{t}_1}{V_o-V_{in}}$ Produce:

$I_{in}=V_{in}{\mathrm{gm}}_{in}=\frac{V_o{V}_{in}{t}_1^2}{2L_m{V}_o{t}_1+2L_m{V}_o{t}_3-2L_m{V}_{in}{t}_3}$

The ON time solving the expectation of this equation produces:

$t_1=\sqrt{\frac{L_m{\mathrm{gm}}_{in}(2V_o{t}_3-2V_{in}{t}_3+L_m{V}_o{\mathrm{gm}}_{in})}{V_o}}+L_m{\mathrm{gm}}_{in}$

In power controller 102, Vo, Vin and Dead Time (t3) can be measured.Also following replacement can be carried out:

K _p＝2L _mgm _in＝t _{on_orig}

This relation is set up, because if make t ₃be arranged to 0 to solve the t of above-mentioned equation ₁, then result is: 2L _mgm _in, this is output voltage 114 in order to obtain expectation and the benchmark ON time (ton_orig) expected without any compensation.By using K _pcarry out those to replace, formula becomes:

$t_{on}=\frac{K_p{V}_o+\sqrt{K_p{V}_o(K_p{V}_o+4V_o{t}_3-4V_{in}{t}_3)}}{2V_o}$

After some simplify, result is equation 1:

$t_{on}=\frac{t_{on\_orig}}{2}+\sqrt{\frac{t_{on\_orig}^2}{4}+t_{on\_orig}{t}_3\frac{V_o-V_{in}}{V_o}}$ (equation 1)

In one embodiment, ON time computing block can not use equation 1 with the ON time duration of calculation expectation.Replace, the simple version of equation 1 is used for ON time duration of calculation expectation by ON time computing block 304.Function is as follows:

$t_{on}=t_{on\_orig}(1+\frac{t_3}{t_{on\_orig}}\frac{V_o-V_{in}}{V_o})$ (equation 2)

By reset equation 1 and hypothesis ON time duration and the benchmark ON time duration expected mutually substantially similar to remove some from equation, to derive equation 2 according to equation 1.The Dead Time duration is significantly less than in the situation of ON time duration the most applicable wherein to use equation 2.Equation 2 is accurate not as equation 1, but equation 2 is easier to implement in circuit than equation 1 because it without the need to relate to the benchmark ON time duration, the Dead Time duration, input voltage and output voltage square root calculate.Replace, equation 2 only needs addition, subtraction and two division arithmetics with the ON time of calculation expectation.

In another embodiment, equation 1 can be rearranged into and be used for the following equation of ON time of calculation expectation by ON time computing block 304:

$t_{on}=\frac{t_{on\_orig}}{2}+t_{on\_orig}\sqrt{.25+k}$ (equation 3)

Wherein:

$k=\frac{t_3}{t_{on\_orig}}\frac{V_o-V_{in}}{V_o}$

Piecewise linear approximation is as seen in Figure 4 used to carry out value finding function fig. 4 diagram according to an embodiment for evaluation piecewise linear approximation.X-axis represents the value of k.Y-axis represents this piecewise linear approximation utilizes six different linear function 405-1,405-2,405-3,405-4 and 405-6 for calculating value based on k selects each linear function 405.Such as, if the value of k is between 8 and 11, then can be used for calculating by choice function 405-1 as another example, if the value of k is between 0 and 0.5, then can be used for calculating by choice function 405-6

Equation 3 implements simpler than equation 1 with circuit, calculates instead of the calculating of explicitly execution square root because it approaches square root by the piecewise linear approximation that square root calculates.Equation 3 is also more accurate than equation 2, especially wherein in the significant situation of Dead Time, because equation 3 does not depend on hypothesis to remove item from equation.

Look back Fig. 3, switch control block 306 receives ON time signal 328 and generates the switch controlling signal 110 for conducting and cut-off switch Q1.Switch control block 306 arranges according to the value of the ON time duration expected the duration that control signal 110 is in the time in conducting state wherein.When control signal 110 is in conducting state (such as having high-voltage level), its actuating switch Q1.When control signal 110 is in off-state (such as having low voltage level), its cut-off switch Q1.In one embodiment, switch control block 306 comprises timer, and this timer converts the ON time duration value of expectation the potential pulse of actuating switch Q1 to.More high expected ON time duration value produces more long pulse, and the ON time value that more short-term is hoped produces more short pulse.

Fig. 5 illustrates the boosting rectifier control block 302 of the power controller 102 according to an embodiment in more detail.Boosting rectifier control block 302 comprises the digital input voltage signal 320 of reception and exports the peak detector 505 of one or more peak detection signal 552, and this one or more peak detection signal represents the peak value of digital input voltage signal 320.The value of skew 556 with peak detection signal 552 is added by adder circuit 510.The size determination output voltage 114 of skew 556 is relative to the quantity of the boost in voltage of input voltage 112.In other words, skew 556 is higher, and the voltage level of output voltage 114 just becomes higher.The output of summing circuit 510 is one or more reference voltage signals 558 of the input voltage 112 of representative skew adjustment.

Low pass filter (LPF) 510 is removed dither from digital output voltage signal 320 and is generated one or more average-voltage signal 554 representing the mean value of digital input voltage signal 320.Subtraction circuit 515 deducts the value of average-voltage signal 554 to generate one or more step-up error signal 560 with reference to the value of voltage signal 558.Average-voltage signal 554 is used to provide the feedback about whether increasing output voltage 114 in fact in the closed.Therefore, the value of step-up error signal 560 indicates whether that output voltage 114 needs to increase or minimizing, and if be so then increase or reduce how many.

Step-up error signal 560 is provided to the error amplifier 502 generating benchmark ON time signal 324.The benchmark ON time duration of the value representation switch Q1 of benchmark ON time signal 324.The P-I function (proportional, integral function) comprising proportional parts 520 sum-product intergrator part 525 implemented by error amplifier 502.Proportional parts 520 is according to steady state value convergent-divergent step-up error value.Integrator part 525 in time to step-up error value integration and according to steady state value convergent-divergent it.The output of proportional parts 520 sum-product intergrator part 525 is added to generate benchmark ON time signal 324 by adder circuit 530.

Fig. 6 diagram is according to the method for operation in power controller 102 of an embodiment.In step 602, power controller 102 determines the benchmark ON time duration of switch Q1.In step 604, power controller 102 determines the Dead Time duration of switch periods.During Dead Time, the electric current 132 flowing through inductor is flat substantially and can equals zero.In step 606, power controller 102 determines the ON time duration of the switch Q1 of the expectation of follow-up switch periods based on benchmark ON time duration and Dead Time duration.Follow-up switch periods can be follow next the immediately switch periods at initial switch week after date, during this initial switch cycle, determine the Dead Time duration.Alternatively, follow-up switch periods can be more late in time and not follow the switch periods in the initial switch cycle immediately.In step 608, power controller 102 is in the control signal 110 of conducting (ON) state with actuating switch Q1 according to the ON time duration generation expected.Power controller 102 maintains duration of the conducting state of control signal 110 based on the ON time duration expected during follow-up switch periods, and this makes switch Q1 be switched on to continue the controllable period of time length that power factor is improved.

In one embodiment, when the Dead Time duration of the measurement in switch periods is used for the ON time duration determined in next immediately switch periods, substantially can perform step 606 and 608 simultaneously.Therefore control signal 110 is placed in conducting state when the ON time of calculation expectation, then once determine that the ON time expected departs from conducting state according to the ON time expected.In other words, with reference to Fig. 2 C, can at time D actuating switch, can between time D and E the ON time of calculation expectation, then once the ON time expected is known, can at time E cut-off switch Q1.

In step 610, power controller 102 determines whether to refresh the benchmark ON time duration.As described in, can only in periodic intervals determination benchmark ON time, during many different switch periods, be then used for the ON time duration determining to expect.If without the need to refreshing the benchmark ON time duration, then repeat step 604 to 608.If should refresh the benchmark ON time duration, then process turns back to step 602 to determine the new benchmark ON time duration.

Fig. 7 A is shown in and does not compensate the ON time duration to correct the waveform of impact up to the average current input of power inverter 100 of Dead Time.The left side of Fig. 7 A is the figure of the input current to bridge rectifier R1.Horizontal axis plots time, and the longitudinal axis represents the level of input current.Due to not enabled dead-time compensation, so input current is not sinusoidal, but replace slightly distortion.The power factor of this distortion reduction power inverter 100, because input current is not proportional with ac input voltage VAC.The right side of Fig. 7 A is the Fourier transform of the input current in the left side from Fig. 7 A.Transverse axis represents the harmonic wave of input current, and the longitudinal axis represents the amplitude of harmonic wave.As shown in the figure, the distortion in input current produces the remarkable level of the odd harmonic (such as at k=3,5) that electromagnetic interference (EMI) is increased.

Fig. 7 B illustrate according to an embodiment compensation the ON time duration to correct the waveform of impact up to the average current input of power inverter 100 of Dead Time duration.The left side of Fig. 7 B is the figure of the input current to bridge rectifier BR1.Horizontal axis plots time, and the longitudinal axis represents the level of input current.Owing to enabling dead-time compensation, so input current is almost sinusoidal ideally and proportional with ac input voltage VAC, this increases the power factor of power inverter 100.The right side of Fig. 7 B is the Fourier transform of the input current in the left side from Fig. 7 B.Transverse axis represents the harmonic wave of input current, and the longitudinal axis represents the amplitude of harmonic wave.As shown in the figure, due to reduce distortion, so odd harmonic much lower in figure 7b thus produce reduce EMI.

By reading present disclosure, those skilled in the art will understand more additional alternate embodiment of the ON time compensation being used for switch mode power converters by principle disclosed herein.Therefore, although show and describe specific embodiment and application, be appreciated that the disclosed embodiments are not limited to precise arrangements disclosed herein and assembly.Under the prerequisite of spirit and scope disclosed in not departing from herein, can carry out in the configuration of method and apparatus disclosed herein, operation and details for those skilled in the art by apparent various amendment, change and change.

Claims (23)

1. a switching power converter, comprising:

Magnet assembly, between the input voltage being coupling in described switching power converter and output voltage;

Switch, be coupled to described magnet assembly to control to flow through the electric current of described magnet assembly, wherein said electric current increases when described switch conduction and is reduced to constant levels of current when described switch disconnects; And

Controller, be configured to generate for conducting or the control signal disconnecting described switch, described switching response is in the first state and conducting in described control signal, and described switching response is in the second state in described control signal and disconnects,

Wherein said controller is configured to the Dead Time duration of the first switch periods determining described switching power converter, the described Dead Time duration is the time remaining time that the described electric current flowed in described magnet assembly is in described constant levels of current

Wherein said controller is configured to determine ON time duration of the described switch of the expectation in the second switch cycle of described switching power converter based on the described Dead Time duration in described first switch periods, the described second switch cycle after described first switch periods, and

Wherein said controller be configured to for the described second switch cycle according to ON time duration of described expectation generate for switch described in conducting, the described control signal that is in described first state, a described duration of first state continuance.

2. switching power converter according to claim 1, wherein said controller is also arranged to the benchmark ON time duration determining described switch, and determines the ON time duration of described expectation based on described benchmark ON time duration and the described Dead Time duration in described first switch periods.

3. switching power converter according to claim 2, if the wherein said benchmark ON time duration is zero for the described Dead Time duration, is adjusted to the ON time duration of the described switch of the voltage level of expectation by described output voltage.

4. switching power converter according to claim 2, the ON time duration of wherein said expectation is longer than described benchmark ON time on the duration.

5. switching power converter according to claim 2, its middle controller determines the ON time duration of described expectation by the ON time duration calculating described expectation according to described benchmark ON time duration and the described Dead Time duration during described first switch periods.

6. switching power converter according to claim 5, its middle controller also calculates the ON time duration of described expectation according to the output voltage values of the input voltage value of level and the level of the described output voltage of expression that represent described input voltage.

7. switching power converter according to claim 6, wherein said controller also calculates the ON time duration of described expectation when not using the square root relating to the described benchmark ON time duration to calculate.

8. switching power converter according to claim 6, wherein said controller also uses the piecewise linear approximation of the square root calculating relating to the described benchmark ON time duration and calculates the ON time duration of described expectation.

9. switching power converter according to claim 2, wherein said controller is also configured to determine the described benchmark ON time duration based on the output feedback signal of the input feedback signal of the level representing described input voltage and the level of the described output voltage of expression.

10. switching power converter according to claim 9, wherein said controller is also configured to generate one or more peak detection signal representing the peak voltage level of described input feedback signal, generate the average output signal that one or more represents the average voltage level of described output feedback signal, and determine the described benchmark ON time duration based on described peak detection signal and described average output signal.

11. switching power converters according to claim 10, wherein said controller is also configured to use skew to adjust described peak detection signal to generate one or more reference voltage signal, described skew represents the boost level of the expectation of described output voltage, and described controller determines the described benchmark ON time duration based on described reference voltage signal.

12. 1 kinds of methods of operation in switching power converter, described switching power converter comprises: magnet assembly, between the input voltage being coupling in described switching power converter and output voltage; Switch, be coupled to described magnet assembly to control to flow through the electric current of described magnet assembly, wherein said electric current increases when described switch conduction and is reduced to constant levels of current when described switch disconnects; And controller, be configured to generate for conducting or the control signal disconnecting described switch, described switching response is in the first state and conducting in described control signal, and described switching response is in the second state in described control signal and disconnects, and described method comprises:

Determine the Dead Time duration of the first switch periods of described switching power converter, the described Dead Time duration is the time remaining time that the described electric current flowed in described magnet assembly is in described constant levels of current;

Determine the ON time duration of the described switch of the expectation in the second switch cycle of described switching power converter based on the described Dead Time duration in described first switch periods, the described second switch cycle is after described first switch periods; And

Described control signal that be used for switch described in conducting, that be in described first state is generated according to the ON time duration of described expectation, a described duration of first state continuance for the described second switch cycle.

13. methods according to claim 12, also comprise:

Determine the benchmark ON time duration of described switch, and

The ON time duration of described expectation is wherein determined based on described benchmark ON time duration and the described Dead Time duration in described first switch periods.

14. methods according to claim 13, if the wherein said benchmark ON time duration is zero for the described Dead Time duration, are adjusted to the ON time duration of the described switch of the output level of expectation by described output voltage.

15. methods according to claim 13, the ON time duration of wherein said expectation is longer than described benchmark ON time on the duration.

16. methods according to claim 13, wherein determine that the ON time duration of described expectation comprises and calculate ON time duration of described expectation according to described benchmark ON time duration and the described Dead Time duration during described first switch periods.

17. methods according to claim 16, wherein also calculate the ON time duration of described expectation according to the output voltage values of the input voltage value of level and the level of the described output voltage of expression that represent described input voltage.

18. methods according to claim 17, wherein calculate the ON time duration of described expectation when not using the square root relating to the described benchmark ON time duration to calculate.

19. methods according to claim 17, the piecewise linear approximation wherein using the square root relating to the described benchmark ON time duration to calculate and calculate ON time duration of described expectation.

20. methods according to claim 13, the output feedback signal wherein based on the input feedback signal of level and the level of the described output voltage of expression that represent described input voltage determines the described benchmark ON time duration.

21. methods according to claim 20, also comprise:

Generate the peak detection signal that one or more represents the peak voltage level of described input feedback signal; And

Generate the average output signal that one or more represents the average voltage level of described output feedback signal,

Wherein determine the described benchmark ON time duration based on described peak detection signal and described average output signal.

22. methods according to claim 21, also comprise:

Use skew to adjust described peak detection signal to generate one or more reference voltage signal, described skew represents the boost level of the expectation of described output voltage;

Wherein also determine the described benchmark ON time duration based on described reference voltage signal.

23. 1 kinds of controllers for switching power converter, described switching power converter comprises: magnet assembly, between the input voltage being coupling in described switching power converter and output voltage; And switch, be coupled to described magnet assembly to control to flow through the electric current of described magnet assembly, wherein said electric current increases when described switch conduction and is reduced to constant levels of current when described switch disconnects, and described controller comprises:

ON-OFF control circuit, be configured to generate for conducting or the control signal disconnecting described switch, described switching response is in the first state and conducting in described control signal, and described switching response is in the second state in described control signal and disconnects,

Wherein said controller is configured to the Dead Time duration of the first switch periods determining described switching power converter, the described Dead Time duration is the time remaining time that the described electric current flowed in described magnet assembly is in described constant levels of current

Wherein said controller is configured to determine ON time duration of the described switch of the expectation in the second switch cycle of described switching power converter based on the described Dead Time duration in described first switch periods, the described second switch cycle after described first switch periods, and

Wherein said ON-OFF control circuit be configured to for the described second switch cycle according to ON time duration of described expectation generate for switch described in conducting, the described control signal that is in described first state, a described duration of first state continuance.