Background technology
This year is along with the growing tension of the energy and becoming increasingly conspicuous of environmental problem, various power-saving technologies, green environmental protection technique become the focus of research day by day, improve energy utilization rate, the efficient that particularly improves energy consumption system then be pendulum with the status of equal importance that taps a new source of energy.Switching Power Supply is widely used in various electric equipments and the electronic product with its higher efficient, abundant make, reliable service behaviour.But along with reduction, the energy consumption day by day of portable electronic product operating voltage progressively reduces, the significantly rising of stand-by time, traditional more and more seeming as the switching power converters continued flow tube with diode more and more can not be satisfied the problems in present society needs at inefficiency.Especially when the operating voltage of microprocessor in the portable type electronic product drops to the 1V left and right sides, even if use various have quick restore funcitons, diodes that forward conduction voltage is very low, as Schottky silicon diode SBD etc. as continued flow tube, their forward conduction voltage still reach about 0.4V-0.6V some in addition higher, come the big electric current of afterflow output with such conducting voltage, just make the power of switch converters wasted greatly by fly-wheel diode, the efficient of switch converters also just has been lowered.Synchronous rectification produces under a kind of like this background, it utilizes the power device such as the power MOSFET of the extremely low special use of on state resistance, IGBT or the like replaces the position of diode, the voltage that is added in the power device two ends like this when the afterflow state is very low, thereby the power of loss when being reduced in the afterflow state greatly, the efficient of raising switch converters.
When adopting synchronous rectification, require to be consistent by the phase place of the control end of the phase place of commutating voltage and power rectifier device MOSFET, IGBT, this also is the title source of synchronous rectification.Because when synchronous rectification, the power rectification pipe of conducting is not unidirectional conducting, but can two-way admittance, so just may occur since the control signal of the design defect of control logic or power switch pipe and power rectification pipe because the influence of time-delay appears at power switch pipe and power rectification pipe while conducting shoot through in certain time period.Two tangible power loss points may appear for the synchronous rectification switch converter of voltage-dropping type like this.A time point is when the charging of inductance soon finishes, power switch pipe does not also have enough time to close and the power rectification pipe has been opened conducting, thereby formed at the low-resistance heavy DC path of the forward end of importing power supply loss part power through two power switch pipe ground connection; When another time point soon finishes to discharge at inductance, the power rectification pipe does not also have enough time to close and power switch pipe has been opened conducting, from and formed forward end from the input power supply through the low-resistance heavy DC path of two power switch pipe ground connection, loss part power.
Summary of the invention
The present invention solves in the existing in prior technology Dead Time controlling schemes, the general fixedly Dead Time controlling schemes that adopts the logic complexity, and be mostly to be aided with current detection circuit, logic complexity so not only, design difficulty is big, and current detection circuit will use current over-zero testing circuit or the like especially, makes the technical problem of the also big grade of design cost; Provide a kind of and realized, also do not adopted complicated control logic just to realize the effect of high efficiency synchronous rectification, had high-efficiency synchronization current adjusting and voltage-reduction switch convertor simple in structure, that efficient is high, volume is little at unfavorable Current Transformer and sensing resistor.
Above-mentioned technical problem of the present invention is mainly solved by following technical proposals:
A kind of high-efficiency synchronization current adjusting and voltage-reduction switch convertor, it is characterized in that, comprise adjusting and voltage-reduction switch converter primary module, the voltage mode negative feedback pulse width modulation controlled module that links to each other with adjusting and voltage-reduction switch converter primary module and the synchronous rectification control module that links to each other with voltage mode negative feedback pulse width modulation controlled module with adjusting and voltage-reduction switch converter primary module respectively.
A kind of high-efficiency synchronization current adjusting and voltage-reduction switch convertor of the present invention, the main circuit of employing adjusting and voltage-reduction switch converter, the high voltage that the input power supply is provided converts circuits needed low-voltage in the portable type electronic product to.Voltage mode negative feedback pulse width modulation controlled module, when utilizing load to change, the duty ratio of pulse-width signal has produced the initial pulse-width signal that can be used for driving circuit of synchronous rectification also with the principle that changes.The synchronous rectification control module is then with initial pulse-width signal filtering wave by prolonging time in addition, thereby and the pulse width signal behind the filtering wave by prolonging time compared with two reference voltages respectively obtain the two-way synchronous rectification signal, what wherein pulsewidth was slightly narrow a road is used for the driving power switching tube, and what pulsewidth was slightly wide a road is used for the driving power rectifying tube after oppositely.
At above-mentioned a kind of high-efficiency synchronization current adjusting and voltage-reduction switch convertor, the described adjusting and voltage-reduction switch converter primary module of stating comprises an input DC power Vin, a power switch tube S 1, one power rectification pipe S2, one energy storage inductor L, an output capacitance C and a load resistance R0; The positive input of described input DC power Vin connects the drain electrode of power switch tube S 1, the source electrode of power switch tube S 1 connects the drain electrode of power rectification pipe S2 and the end of energy storage inductor L, the end of another termination output capacitance C of energy storage inductor L and the end of load resistance R0, the source ground of power rectification pipe S2, the other end ground connection of load resistance R0, the other end ground connection of input DC power Vin.
At above-mentioned a kind of high-efficiency synchronization current adjusting and voltage-reduction switch convertor, described voltage mode negative feedback pulse width modulation controlled module comprises by voltage sample resistance R _ f 1, the output voltage sampling network that voltage sample resistance R _ f 2 is formed, an error amplifier A, a pulse-width modulation comparator PWM, a saw-toothed wave generator Vramp and a reference voltage source Vref3; The end of described sampling resistor Rf1 links to each other the reverse input end of another termination sampling resistor Rf2 and described error amplifier A, the other end ground connection of described sampling resistor Rf2 with described adjusting and voltage-reduction switch converter primary module forward output; The positive input of described error amplifier A meets reference voltage source Vref3, the positive input of output termination pulse-width modulation comparator PWM; The reverse input end of described pulse-width modulation comparator PWM connects the output of saw-toothed wave generator Vramp, and inverse output terminal links to each other with described synchronous rectification control module; The other end ground connection of described saw-toothed wave generator Vramp.
At above-mentioned a kind of high-efficiency synchronization current adjusting and voltage-reduction switch convertor, described described synchronous rectification control module comprises a filtering wave by prolonging time network of being made up of time delay resistance Rf and filter capacitor Cf, and synchronous rectification control comparator C1, synchronous rectification control comparator C2 and an inverter INV; The inverse output terminal of the described pulse-width modulation comparator of the termination PWM of described time delay resistance Rf, the other end links to each other the other end ground connection of described filter capacitor Cf with the end of filter capacitor Cf, the positive input that comparator C1 and C2 are controlled in synchronous rectification respectively simultaneously; The reverse input end of described synchronous rectification control comparator C1 meets reference voltage source Vref1, the control end grid of output termination power switch tube S 1; The reverse input end of synchronous rectification control comparator C2 meets reference voltage source Vref2, the input of output termination reverser INV, the control end grid of the output termination power rectification pipe S2 of inverter INV.
Therefore, the present invention has following advantage: 1. and reasonable in design, simple in structure and complete practicality; 2. realized at unfavorable Current Transformer and sensing resistor, also do not adopted complicated control logic just to realize the effect of high efficiency synchronous rectification, have simple in structure, efficient is high, volume is little.
Embodiment
Below by embodiment, and in conjunction with the accompanying drawings, technical scheme of the present invention is described in further detail.Among the figure, adjusting and voltage-reduction switch converter primary module 1, voltage mode negative feedback pulse width modulation controlled module 2, synchronous rectification control module 3.
Embodiment:
A kind of high-efficiency synchronization current adjusting and voltage-reduction switch convertor, it is characterized in that voltage mode negative feedback pulse width modulation controlled module 2 that comprise adjusting and voltage-reduction switch converter primary module 1, links to each other and the synchronous rectification control module 3 that links to each other with voltage mode negative feedback pulse width modulation controlled module 2 with adjusting and voltage-reduction switch converter primary module 1 respectively with adjusting and voltage-reduction switch converter primary module 1.
Adjusting and voltage-reduction switch converter primary module 1 comprises an input DC power Vin, a power switch tube S 1, one power rectification pipe S2, an energy storage inductor L, an output capacitance C and a load resistance R0; The positive input of input DC power Vin connects the drain electrode of power switch tube S 1, the source electrode of power switch tube S 1 connects the drain electrode of power rectification pipe S2 and the end of energy storage inductor L, the end of another termination output capacitance C of energy storage inductor L and the end of load resistance R0, the source ground of power rectification pipe S2, the other end ground connection of load resistance R0, the other end ground connection of input DC power Vin.
Voltage mode negative feedback pulse width modulation controlled module 2 comprises by voltage sample resistance R _ f 1, the output voltage sampling network that voltage sample resistance R _ f 2 is formed, an error amplifier A, a pulse-width modulation comparator PWM, a saw-toothed wave generator Vramp and a reference voltage source Vref3; The end of sampling resistor Rf1 links to each other with adjusting and voltage-reduction switch converter primary module 1 forward output, the reverse input end of another termination sampling resistor Rf2 and error amplifier A, the other end ground connection of sampling resistor Rf2; The positive input of error amplifier A meets reference voltage source Vref3, the positive input of output termination pulse-width modulation comparator PWM; The reverse input end of pulse-width modulation comparator PWM connects the output of saw-toothed wave generator Vramp, and inverse output terminal links to each other with synchronous rectification control module 3; The other end ground connection of saw-toothed wave generator Vramp.
Synchronous rectification control module 3 comprises a filtering wave by prolonging time network of being made up of time delay resistance Rf and filter capacitor Cf, and synchronous rectification control comparator C1, synchronous rectification control comparator C2 and an inverter INV; The inverse output terminal of the termination pulse-width modulation comparator PWM of time delay resistance Rf, the other end link to each other the other end ground connection of filter capacitor Cf with the end of filter capacitor Cf, the positive input that comparator C1 and C2 are controlled in synchronous rectification respectively simultaneously; The reverse input end of synchronous rectification control comparator C1 meets reference voltage source Vref1, the control end grid of output termination power switch tube S 1; The reverse input end of synchronous rectification control comparator C2 meets reference voltage source Vref2, the input of output termination reverser INV, the control end grid of the output termination power rectification pipe S2 of inverter INV.The pulse-width control signal that 3 pairs of voltage mode negative feedbacks of synchronous rectification control module pulse width modulation controlled module 2 is produced carries out behind the filtering wave by prolonging time and two-way reference voltage V ref1, Vref2 and Vref1<Vref2 compare, it is identical to obtain the two-way cycle, the synchronous rectification control signal that high level part pulsewidth is different
,
The synchronous rectification control signal of the two-way distinct pulse widths that synchronous rectification control module 3 produces
,
, signal
After process inverter INV is reverse, the synchronous rectification control signal
With
Between have Dead Time, the control of Dead Time is satisfied:
Wherein
It is the high level of the pulse-width modulation square-wave signal of voltage mode negative feedback pulse width modulation controlled module 2 outputs.
Should be noted that: error amplifier A, pulse-width modulation comparator PWM, synchronous rectification control comparator C1, C2, the operating frequency of inverter INV is higher than the switching frequency of synchronization current adjusting and voltage-reduction switch convertor; Filtering wave by prolonging time network Rf, Cf in the synchronous rectification control module 3, synchronous rectification control comparator C1, C2, the two-way synchronous rectification control signal that first, second reference voltage acting in conjunction produces
With
Between the Dead Time that exists should satisfy 0.1-0.2T, wherein T is the switch periods of synchronization current adjusting and voltage-reduction switch convertor.
Wherein
It is the high level of the square wave of pulse-width signal output, enough the unlatching of power switch pipe and the unlatching effective isolation of power rectification pipe are come in order to satisfy Dead Time, general Dead Time Td should satisfy 0.1T-0.2T, and wherein T is the switch periods of voltage-dropping type synchronous rectification switch converter.And the regulating measure for Dead Time is various, both can obtain effective Dead Time, also can obtain effective Dead Time by the size of regulating reference voltage V ref1 and Vref2 by the value of time delay resistance and filter capacitor in the adjusting filtering wave by prolonging time network.Like this, when being optimized, Dead Time at least just have two kinds of means to use, a kind of can be by changing Rf into variable resistor, its resistance of adjusting by machinery, the dead band control time of optimizing, another kind of then be to obtain effective Dead Time by the size that the mode of programming Control is dynamically controlled reference voltage V ref1 and Vref2.Especially a kind of mode in back is a kind of good mode of raising the efficiency for the Switching Power Supply of control able to programme.
Working condition of the present invention is as follows:
When the power switch pipe conducting, energy flows into from the input power supply, makes energy storage inductor, output capacitance begin storage power, and powers to load resistance simultaneously for adjusting and voltage-reduction switch converter primary module 1.Synchronous rectification control module power controlling rectifying tube is in off state in this process, and negative just down on during the output of converter, and the body diode of power rectification pipe is in reverse-bias state, can not conducting.When energy storage finishes, when power switch pipe turn-offs, because energy storage inductor is converted to the energy output element by the store energy element, the electric current that flows through it can not be undergone mutation, stop the electric current that flows through inductance to reduce and produce an induced potential, this electromotive force is just to go up down to bear for the power rectification pipe, at this moment in the very short Dead Time before the power rectification pipe is opened conducting, take over the conducting of power rectification pipe with occurring by the body diode of power rectification pipe is instantaneous, the conducting of the power controlling of synchronous rectification control module then rectifying tube, energy in the energy storage inductor is exported to storage capacitor through the power rectification pipe, gives the power supply of storage capacitor and load resistance simultaneously.Because the resistance of power rectification pipe is extremely low, the voltage at power rectification pipe two ends will be not enough to support the conducting of the body diode of power rectification pipe, so body diode ends after finishing its instantaneous function of taking over the conducting of power rectification pipe.
For voltage mode negative feedback pulse width modulation controlled module, adopt on the sampling resistor sampled voltage and the 3rd reference voltage relatively amplify and relatively to produce pulse-width modulation control signal with sawtooth waveforms again in the back, this signal directly is not used for the break-make of power controlling switching tube, but is used for the break-make of power controlling switching tube and power rectification pipe after the processing through the synchronous rectification control module.When load changes, the sampled voltage that sampling network obtains also can change, thereby change the duty ratio of pulse-width signal, be used for after the processing through the synchronous rectification control module service time of power controlling switching tube and power rectification pipe guaranteeing the stable of output voltage.
For the synchronous rectification control module, the pulse-width signal that transmits from voltage mode negative feedback pulse width modulation controlled module, after the processing through the filtering wave by prolonging time network, its waveform will change, it is obvious that the rising edge of pulse-width signal and trailing edge will become, the width of high level part will narrow down, and then depend on the size of the time constant of filtering wave by prolonging time network as for the degree of the narrowed width of the rising edge of pulse-width signal and the obvious degree of trailing edge, high level part.To compare with two reference voltage V ref1, Vref2 configuring respectively through the pulse-width signal after the delay process, will obtain the slightly variant synchronous rectification signal of two-way high level part pulsewidth
,
, and the synchronous rectification signal high level part that big rood of fiducial value arrives is slightly narrow, promptly
The width of high level part slightly be narrower than
The width of high level part.The characteristics of such two-way synchronous rectification signal are,
Rising edge exist
Afterwards, but trailing edge exist
Before, but the identical period T that all equals the pulse-width signal that pulse-width modulation circuit obtains of their cycle.
Directly be used for the driving power switching tube,
After oppositely, be used for the driving power rectifying tube.
Specific embodiment described herein only is that the present invention's spirit is illustrated.The technical staff of the technical field of the invention can make various modifications or replenishes or adopt similar mode to substitute described specific embodiment, but can't depart from spirit of the present invention or surmount the defined scope of appended claims.
Although this paper has used terms such as adjusting and voltage-reduction switch converter primary module 1, voltage mode negative feedback pulse width modulation controlled module 2, synchronous rectification control module 3 morely, do not get rid of the possibility of using other term.Using these terms only is in order to describe and explain essence of the present invention more easily; They are construed to any additional restriction all is contrary with spirit of the present invention.