CN102624211B - Pre-bias starting circuit of direct current-direct current (DC-DC) converter and control method - Google Patents
Pre-bias starting circuit of direct current-direct current (DC-DC) converter and control method Download PDFInfo
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- CN102624211B CN102624211B CN201210111331.3A CN201210111331A CN102624211B CN 102624211 B CN102624211 B CN 102624211B CN 201210111331 A CN201210111331 A CN 201210111331A CN 102624211 B CN102624211 B CN 102624211B
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Abstract
The invention discloses a pre-bias starting circuit of a DC-DC converter and a control method. The circuit is additionally provided with a pulse stopping circuit, when reverse current in a switching tube exists through the detection of the pulse stopping circuit, and communicating drive pulse signals of a function switching tube in the DC-DC converter are stopped to transmitted to the function switching tube, so that the communication of the function switching tube is stopped. The function switching tube is a follow current switching tube or a clamping switching tube in the DC-DC converter, therefore the constant increasing of the reverse current in the switching tube is stopped, the reverse current is effectively controlled within a low degree, the failure of devices in the DC-DC converter caused by excessive stress is avoided, the service life of the DC-DC converter is prolonged.
Description
Technical field
The application relates to DC-DC converter technical field, particularly relates to a kind of Prebias boot-strap circuit and control method of DC-DC converter.
Background technology
In DC-DC converter field, generally adopt synchronous rectification, but adopt the energy in the DC-DC converter of synchronous rectification can two-way flow, such as, Buck converter, in the time that output voltage is greater than the product of input voltage and duty ratio, electric current will flow to input by output, if the input of Buck converter is regarded as to output, and output is regarded as to input, now, Buck converter is actually a Boost converter.
The phenomenon of reverse direction current flow is prevalent in all kinds of converter topologies that adopt synchronous rectification, in the time of practical application, may throw into question, especially converter is in the time of the situation start of prebias, while start in the situation that converter output terminal exists certain voltage, reverse current may be very large, because in most of converter, in order to obtain the effect of level and smooth startup, soft starting circuit can be set, the duty ratio of driving voltage in the rear converter of converter start is increased gradually, so the duty ratio of driving voltage is very little in the time that converter is just started shooting, now will produce reverse current, increase to and be enough to make before input voltage and output voltage reach balance in the duty ratio of driving voltage, reverse current can constantly increase, reverse current is too large may cause the stresses of parts of converter excessive and cause losing efficacy, in addition, also can cause output voltage fall excessive and cause load circuit can not keep normal operation.
Summary of the invention
For solving the problems of the technologies described above, the embodiment of the present application provides a kind of DC-DC converter Prebias boot-strap circuit and control method, to prevent that reverse current from constantly increasing, reverse current is limited in to less degree effectively, avoided the phenomenon excessive and that lost efficacy of the device stress in DC-DC converter to occur, technical scheme is as follows:
The application provides a kind of Prebias boot-strap circuit of DC-DC converter, comprising:
The pulse being electrically connected with described DC-DC converter stops circuit, described pulse stop circuit for detection of the switching tube in described DC-DC converter in turn-offing, and while there is reverse current in described switching tube, stop the conducting driving pulse of the functional switch pipe in described DC-DC converter to be passed to described functional switch pipe, to stop the conducting of described functional switch pipe, until described reverse current is reduced to zero, described functional switch pipe is continued flow switch pipe or the clamp switch pipe in described DC-DC converter.
Preferably, described DC-DC converter is Buck converter, and described Buck converter mainly comprises: control circuit, switching tube, continued flow switch pipe and the first inductance, and described pulse stops circuit to comprise: the second inductance, blocking swtich pipe, wherein:
Described the second inductance and described the first inductance are coupled, and the Same Name of Ends of described the second inductance connects the first end of described blocking swtich pipe, and described first end connects the control end of described continued flow switch pipe, the other end of described the second inductance connects the control end of described blocking swtich pipe, and described the second inductance is used for judging whether described switching tube exists reverse current;
The second end of described blocking swtich pipe connects the first output of described control circuit, when described blocking swtich pipe exists reverse current for described the second inductance detection to described switching tube, stop the driving pulse of the described continued flow switch pipe of the control conducting of described control circuit the first output output to be passed to described continued flow switch pipe.
Preferably, described DC-DC converter is active-clamp converter, described active-clamp converter mainly comprises: control circuit, switching tube, clamp switch pipe and transformer, described transformer comprises former limit winding, with the secondary winding of described former limit winding coupled, the auxiliary winding with described former limit winding is coupled, is characterized in that, described pulse stops circuit to comprise: transformer coupled winding, blocking swtich pipe, wherein:
Described transformer coupled winding and described former limit winding coupled, and the Same Name of Ends of described transformer coupled winding is connected with the first end of described blocking swtich pipe, and described first end connects the second output of described control circuit, the other end of described transformer coupled winding connects the control end of described blocking swtich pipe, and described transformer coupled winding is for detection of whether there being reverse current in described switching tube;
The second end of described blocking swtich pipe connects the control end of described clamp switch pipe, described blocking swtich pipe detects when described switching tube exists reverse current for transformer coupled winding, stops the driving pulse of the described clamp switch pipe of the control conducting of described control circuit the second output output to be passed to described clamp switch pipe.
Preferably, described DC-DC converter comprises soft start capacitor, also comprise: be connected to described pulse and stop the soft start accelerating circuit between circuit and described soft start capacitor, described soft start accelerating circuit is when stoping circuit to stop described functional switch pipe conducting to described pulse, and output current is described soft start capacitor charging.
Preferably, described DC-DC converter is Buck converter, described soft start accelerating circuit comprises soft start switch pipe, the first end of described soft start switch pipe connects the second end of described blocking swtich pipe, the control end of described soft start switch pipe connects the first end of described blocking swtich pipe, the second end of described soft start switch pipe connects described soft start capacitor, in the time that described blocking swtich pipe stops described continued flow switch pipe conducting, the conducting of described soft start switch pipe, for described soft start capacitor provides charging current.
Preferably, described soft start accelerating circuit also comprises: be serially connected in successively charging resistor and diode between the second end and the described soft start switch pipe of described soft start switch pipe, described charging current flows into described soft start capacitor through described charging resistor and described diode.
Preferably, described DC-DC converter is active-clamp converter, and described soft start accelerating circuit comprises: soft start switch pipe, the first switching tube, charging resistor, the first diode, the second diode and the first electric capacity, wherein:
The first end of described soft start switch pipe is connected described soft start capacitor by the charging resistor of connecting successively with the first diode, the second end of described soft start switch pipe connects the first end of described blocking swtich pipe, and the control end of described soft start switch pipe connects the second end of described blocking swtich pipe;
The first end of described the first switching tube connects earth terminal, and the second end connects the common port of described charging resistor and described the first diode, and control end connects the first end of described blocking swtich pipe;
The anodic bonding of described the second diode is at the first end of described blocking swtich pipe, and negative electrode connects the second end of described soft start switch pipe;
Described first electric capacity one end connects the negative electrode of described the second diode, and the other end connects described earth terminal
In the time that described blocking swtich pipe stops described clamp switch pipe conducting, the conducting of described soft start switch pipe, described the first switching tube cut-off, for described soft start capacitor provides charging current.
Preferably, described blocking swtich pipe is N-type metal-oxide-semiconductor, and described first end is that source electrode, the second end are drain electrode, and control end is grid.
Preferably, described soft start switch pipe is PMOS pipe, and described first end is that source electrode, the second end are drain electrode, and described control end is grid.
Preferably, described soft start switch pipe and described the first switching tube are NMOS pipe, and described first end is that source electrode, the second end are drain electrode, and control end is grid.
The application also provides a kind of Prebias boot-strap control method of DC-DC converter, comprising:
Detect switching tube in described DC-DC converter in the time turn-offing, in described switching tube, whether have reverse current, obtain the first testing result;
In the time the first testing result that has reverse current in described switching tube being detected, stop the conducting of described functional switch pipe, until described reverse current is decreased to zero, described functional switch pipe is continued flow switch pipe or the clamp switch pipe in described DC-DC converter.
Preferably, the method also comprises: in the time the first testing result that has reverse current in described switching tube being detected, be described soft start capacitor charging.
The technical scheme being provided from above the embodiment of the present application, described DC-DC converter Prebias boot-strap circuit, stop while there is reverse current in switching tube described in electric circuit inspection by pulse, stop the conducting drive pulse signal of the functional switch pipe in described DC-DC converter to be passed to described functional switch pipe, thereby stop the conducting of described functional switch pipe, described functional switch pipe is continued flow switch pipe or the clamp switch pipe in described DC-DC converter, thereby stop the reverse current in switching tube constantly to increase, reverse current is limited in to less degree effectively, avoid the phenomenon excessive and that lost efficacy of the device stress in DC-DC converter to occur, extend the useful life of DC-DC converter.
Brief description of the drawings
In order to be illustrated more clearly in the embodiment of the present application or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, the accompanying drawing the following describes is only some embodiment that record in the application, for those of ordinary skill in the art, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.
Fig. 1 is the theory diagram of a kind of DC-DC converter Prebias boot-strap circuit of the embodiment of the present application;
Fig. 2 is the circuit signal of a kind of typical Buck converter in prior art;
Fig. 3 is the groundwork waveform schematic diagram of the circuit shown in Fig. 2;
The pulse that Fig. 4 provides for the embodiment of the present application stops the physical circuit principle schematic of circuit application in the Buck converter shown in Fig. 2;
Fig. 5 is the groundwork oscillogram of the circuit shown in Fig. 4;
A kind of circuit diagram of typical active-clamp converter in Fig. 6 prior art;
Fig. 7 is the main waveform schematic diagram starting under prebias condition of the active-clamp converter shown in Fig. 6;
The pulse that Fig. 8 the embodiment of the present application provides stops circuit application in the circuit theory schematic diagram of the active-clamp converter shown in Fig. 6;
Fig. 9 is the groundwork waveform schematic diagram of the circuit shown in Fig. 8;
Figure 10 is the schematic block circuit diagram of the another kind of DC-DC converter Prebias boot-strap circuit of the embodiment of the present application;
Figure 11 is that the circuit application shown in Figure 10 is in the circuit diagram of Buck converter;
Figure 12 is that the circuit application shown in Figure 10 is in the circuit diagram of active-clamp converter;
Figure 13 is the schematic flow sheet of the Prebias boot-strap method of a kind of DC-DC converter of the embodiment of the present application.
Embodiment
In order to make those skilled in the art person understand better the technical scheme in the application, below in conjunction with the accompanying drawing in the embodiment of the present application, technical scheme in the embodiment of the present application is clearly and completely described, obviously, described embodiment is only some embodiments of the present application, instead of whole embodiment.Based on the embodiment in the application, those of ordinary skill in the art are not making the every other embodiment obtaining under creative work prerequisite, all should belong to the scope of the application's protection.
Refer to Fig. 1, show the theory diagram of a kind of DC-DC converter Prebias boot-strap circuit that the embodiment of the present application provides, application circuit as shown in the figure comprises: DC-DC converter 100, pulse stop circuit 200.
When described pulse stops circuit 200 to turn-off for detection of the switching tube in described DC-DC converter 100, in switching tube, whether there is reverse current, if the existence of reverse current detected, stop the functional switch pipe conducting in DC-DC converter circuit, until the reverse current in described switching tube is reduced to zero, the driving pulse that the conducting of described functional switch pipe is controlled in concrete prevention is passed to described functional switch pipe;
When concrete application, when described DC-DC converter is Buck converter, described functional switch pipe is continued flow switch pipe; When described DC-DC converter is active-clamp converter, described functional switch pipe is clamp switch pipe.
The DC-DC converter Prebias boot-strap circuit that the present embodiment provides, can stop the reverse current of DC-DC converter in the time of Prebias boot-strap constantly to increase, reverse current is limited in to less degree effectively, avoid the phenomenon excessive and that lost efficacy of the device stress in DC-DC converter to occur, extended the useful life of DC-DC converter.
Stop circuit application in the situation of the DC-DC converter of different circuit structures by introducing in detail the pulse that the application provides below.
(1) described pulse stops circuit application in Buck converter
Refer to Fig. 2, show a kind of circuit diagram of typical Buck converter, this converter mainly comprises: switching tube Q1, continued flow switch pipe Q2, the first inductance L, soft start capacitor Css and control circuit 101.
The first output output driving pulse of described control circuit 101 is to drive continued flow switch pipe Q2, the second output output driving pulse of described control circuit 101 is with driving switch pipe Q1, described control circuit 101 is controlled described switching tube Q1 and continued flow switch pipe Q2 with complementary type alternate conduction, while being switching tube Q1 conducting, continued flow switch pipe Q2 turn-offs, when switching tube Q1 turn-offs, continued flow switch pipe Q2 conducting.
Control circuit 101 disposes soft start capacitor Css, after the start of described Buck converter control circuit 101 to soft start capacitor Css gradually the driving pulse duty ratio of charging control switch pipe Q1 increase gradually, when Buck converter is started under prebias condition, may in switching tube Q1, produce very large reverse current.
Concrete, refer to Fig. 3, corresponding groundwork waveform schematic diagram while showing the Buck converter Prebias boot-strap shown in Fig. 2.
The voltage waveform that in Fig. 3, Vgs1 is corresponding is the grid source driving voltage of switching tube Q1, and the voltage waveform that Vgs2 is corresponding is the grid source driving voltage of continued flow switch pipe Q2, and the waveform that IL is corresponding is the inductive current in inductance L;
Concrete, suppose that the electric current I L that Buck converter starts in front the first inductance L is zero, owing to disposing soft start capacitor Css in control circuit 101, Buck converter starts starting with very little duty ratio, and the duty ratio of the driving pulse of switching tube Q1 is very little.
As shown in Figure 3, Vgs1 is between high period, switching tube Q1 conducting, and in switching tube Q1 conduction period, inductive current IL rises gradually, and because the duty ratio of Vgs1 is very little, switching tube Q1 ON time is very short, and inductive current IL can only rise to a less value;
In the time that switching tube Q1 turn-offs, Vgs2 becomes high level from low level, and continued flow switch pipe Q2 starts conducting, now, be subject to the effect of output pre-bias voltage Vo, the energy storing in the first inductance L discharges through continued flow switch pipe Q2, inductive current IL is declined, because the value of inductive current IL is less, be down to very soon zero, after inductive current reduces to zero, from the waveform of Vgs2, continued flow switch pipe Q2 continues to keep conducting, therefore, inductive current IL becomes negative value, and electric current is reverse, and oppositely increases.While end to the one-period of Vgs1, value when inductive current IL can not start in the cycle of getting back to, but oppositely increase to some extent, this is because the duty ratio of Vgs1 is very little, the forward voltagesecond product that the first inductance L is born in a switch periods is less than reverse voltagesecond product.
If can not increasing rapidly, the duty ratio of Vgs1 make forward voltagesecond product and reverse voltagesecond product reach balance, inductive current IL will be oppositely increasing so, as shown in Figure 3 shown in the waveform of inductive current IL, and the excessive stresses of parts that just may cause of reverse inductive current IL is excessive and damage.
Refer to Fig. 4, the described pulse that showing the embodiment of the present application provides stops the physical circuit principle schematic of circuit application in the Buck converter shown in Fig. 2.
Described pulse stops circuit 200 to comprise blocking swtich pipe Q3, the second inductance NL, wherein,
Described the second inductance NL and described the first inductance L are coupled, and the Same Name of Ends of described the second inductance NL connects the first end of described blocking swtich pipe Q3, simultaneously, described first end connects the control end of described continued flow switch pipe Q2, the other end of described the second inductance NL connects the control end of described blocking swtich pipe Q3, and described the second inductance NL is used for judging whether switching tube Q1 exists reverse current;
The second end of described blocking swtich pipe Q3 connects the first output of described control circuit 101, when described blocking swtich pipe Q3 exists reverse current for detecting as described the second inductance NL, stop the driving pulse of the described continued flow switch pipe of the control Q2 conducting of the first output output of described control circuit 101 to be passed to described continued flow switch pipe Q2.
It should be noted that, switching tube Q1, the continued flow switch pipe Q2 in the present embodiment and blocking swtich pipe Q3 all adopt NMOS pipe to realize, and first end is that source electrode, the second end are that drain electrode, control end are grid.But the application does not limit the type of described switching tube Q1, continued flow switch pipe Q2 and blocking swtich pipe Q3, the every switching tube that can realize above-mentioned functions is all scopes that the application is open and protect.
Concrete, in conjunction with the groundwork oscillogram of the circuit shown in the Fig. 4 shown in Fig. 5, introduce in detail pulse and stop circuit application in the course of work of Buck converter.
In Fig. 5, the waveform that Vgs1 is corresponding is the driving voltage of switching tube Q1; The waveform that DRV is corresponding is the voltage waveform of the first output output drive signal of control circuit 101; The waveform that Vgs2 is corresponding is the driving voltage of continued flow switch pipe Q2, and the waveform that Vgs3 is corresponding is the driving voltage of blocking swtich pipe Q3; The waveform that IQ1 is corresponding is the current waveform in switching tube Q1; The waveform that IL is corresponding is the current waveform in the first inductance L; Vgs9 is the driving voltage waveform of soft start switch pipe Q9; The charging current Iss current waveform that Iss provides for soft start capacitor for soft start accelerating circuit, wherein, Vgs9 and Iss apply in embodiment corresponding to Figure 11.
Suppose that initial time is t0, now inductive current IL is that zero, Buck converter starts with less duty ratio.
T0 is to during t1, and Vgs1 is high level, switching tube Q1 conducting; Vgs2 is low level, and continued flow switch pipe Q2 turn-offs; Inductive current IL in the first inductance L rising of starting from scratch, the voltage of the Same Name of Ends of the first inductance L is being for just, and the voltage of the second inductance NL induction is also Same Name of Ends for just, now, the gate source voltage of blocking swtich pipe Q3 is less than zero, and therefore, blocking swtich pipe Q3 keeps turn-offing.
But, the shutoff of blocking swtich pipe Q3 can't hinder the shutoff of continued flow switch pipe Q2, because, blocking swtich pipe Q3 self has parasitic body diode, no matter whether conducting of blocking swtich pipe Q3, the shutoff drive current of continued flow switch pipe Q2 grid can flow to the first output of control circuit 101 smoothly.
T1 is to during t2, and to the t1 moment, Vgs1 becomes low level from high level, and switching tube Q1 turn-offs, and now, the driving signal DRV of the first output output of control circuit 101 becomes high level from low level.At t1 moment inductive current, IL is forward, switching tube Q1 closes and has no progeny, inductive current IL continues to keep forward, but can turn in the parasitic body diode of continued flow switch pipe Q2, the polarity of voltage that the first inductance L is born becomes Same Name of Ends for negative, the induced voltage of the second inductance NL is also that Same Name of Ends is negative, be that Vgs3 is high level, therefore, blocking swtich pipe Q3 conducting, the high level of the first output output of control circuit 101 drives signal can be passed to smoothly by blocking swtich pipe Q3 the control end of continued flow switch pipe Q2, make continued flow switch pipe Q2 conducting, inductive current IL is transferred in the raceway groove of continued flow switch pipe Q2 by the parasitic body diode of continued flow switch pipe Q2, under the effect of output end voltage Vo, inductive current IL reduces gradually, after being reduced to zero, become oppositely, and oppositely increase, because the polarity of voltage that the first inductance L is born in the reverse process of inductive current IL is constant, always for Same Name of Ends is for negative, the polarity of the induced voltage that the second inductance NL senses is also that Same Name of Ends is negative, therefore, pulse stops the state of circuit 200 to remain to the t2 moment from the t1 moment always.
T2 is to during t3, to the t2 moment, inductive current IL has oppositely increased to certain value, now, the pulse signal DRV of the first output output of control circuit 101 becomes low level, because stoping circuit 200, pulse do not stop the shutoff of continued flow switch pipe Q2, therefore, continued flow switch pipe Q2 becomes low level shutoff simultaneously at the driving signal DRV of output, continued flow switch pipe Q2 closes and has no progeny, inductive current IL continues to keep oppositely, but can be transferred in the parasitic body diode of switching tube Q1, the polarity of voltage that the first inductance L is born becomes Same Name of Ends for just, the voltage of the second inductance NL induction also becomes Same Name of Ends for just, therefore, blocking swtich pipe Q3 turn-offs.
Meanwhile, the driving voltage Vgs1 that control circuit 101 is exported becomes high level, switching tube Q1 conducting, inductive current IL is transferred to by the parasitic body diode of switching tube Q1 in the raceway groove of switching tube Q1, and under the effect of input voltage Vi, reverse inductive current IL reduces gradually, but because the duty of Vgs1 is smaller, to the t3 moment, inductive current IL is not yet reduced to zero, is still reverse current.
T3 is to during t4, and during to the t3 moment, Vgs1 becomes low level, and switching tube Q1 turn-offs, and meanwhile, the driving signal DRV of control circuit 101 first outputs outputs becomes high level from low level, switching tube Q1 closes and has no progeny, reverse inductive current IL transfers to the parasitic body diode of switching tube Q1 from the raceway groove of switching tube Q1, the polarity of voltage that the first inductance L is born is constant, still keep Same Name of Ends for just, the voltage of the second inductance NL induction also keeps Same Name of Ends for just, be that Vgs3 is low level, blocking swtich pipe Q3 continues to keep turn-offing, therefore, the driving signal DRV that control circuit 101 is exported can not be passed to continued flow switch pipe Q2 while becoming high level, because blocking swtich pipe Q3 has stoped the transmission that drives signal DRV, so continued flow switch pipe Q2 continues to keep turn-offing.Under the effect of input voltage Vi, inductive current IL continues to reduce, until the t4 moment is reduced to zero.
T4 is to during t5, to the t4 moment, inductive current IL is also that the reverse current IQ1 in switching tube Q1 is decreased to zero, the parasitic body diode of switching tube Q1 enters reversely restoring process under the effect of input voltage Vi, and produce certain restoring current, then reverse-biased shutoff, the reverse recovery current of the parasitic body diode of switching tube Q1 is for inductive current IL, it is a forward current, but its value is less, therefore in Fig. 5, do not embody, therefore, in the time that the parasitic body diode of switching tube Q1 is oppositely turn-offed, inductive current IL is in a less forward current state, this little forward current will turn to the parasitic body diode of continued flow switch pipe Q2, the polarity of voltage that the first inductance L is born becomes Same Name of Ends for negative, the polarity of the inductive sensor of the second inductance NL is also for Same Name of Ends is for negative, be that Vgs3 becomes high level, make blocking swtich pipe Q3 conducting, and then the driving signal DRV that makes the high level that control circuit 101 exports is passed to the control end of continued flow switch pipe Q2, make continued flow switch pipe Q2 conducting, now, it is negative that the polarity of voltage that the first inductance L is born is that Same Name of Ends remains, under the effect of output voltage V o, inductive current IL is reduced to rapidly zero by less forward current, then reverse, and continue oppositely to increase, until the t5 moment, inductive current IL oppositely increases to certain value.
T5 to during t6 with t2 to similar during t3, t6 to during t7 with t3 to similar during t4, the like, the circuit shown in Fig. 4 will so move several switch periods.
Comparison diagram 3 and Fig. 5 are known, there is very large difference in the conducting interval of continued flow switch pipe Q2 in two circuit shown in Fig. 2 and Fig. 4, DC-DC converter shown in Fig. 4 is applied described pulse and is stoped circuit 200, make continued flow switch pipe Q2 in each cycle, drive signal DRV to keep conducting in the interval of high level, but close and have no progeny at switching tube Q1, until the electric current I Q1 in the parasitic body diode of switching tube Q1 reduces to zero, be after inductive current IL reduces to zero by reverse current, just conducting of continued flow switch pipe Q2.Like this, just can there is not each cycle by the reverse increase of accumulation and become gradually increasing situation in inductive current IL;
Can find out from the oscillogram shown in Fig. 5, in each cycle, to be down to moment of zero from reverse current not necessarily identical for inductive current IL, be that in Fig. 5, t3 is not necessarily equal to the time of t7 with t6 to the time of t4, but this does not affect described pulse and stops circuit to play a role, in the time that input voltage Vi is lower, may occur that reverse inductive current IL fails to be down to zero within even several cycles of one-period, now, pulse stops circuit 200 will make continued flow switch pipe Q2 keep turn-offing always, until reverse inductive current IL reduces to zero interception that just discharges the driving signal DRV to controlling continued flow switch pipe Q2 conducting.
Because pulse stops circuit 200 not stop the shutoff of continued flow switch pipe Q2, so continued flow switch pipe Q2 can be turned off in each cycle, the threshold limit value of each ON time of continued flow switch pipe Q2 is no more than a switch periods so.And inductive current IL's is oppositely to cause due to the conducting of continued flow switch pipe Q2, therefore once can to make at most the amplitude that inductive current IL oppositely increases be (VoT)/L in continued flow switch pipe Q2 conducting, in formula, Vo is output end voltage, T is the switch periods of Buck converter, and L is the inductance value of the first inductance L.Prevented the accumulation gradually of reverse inductive current IL because pulse stops circuit 200, therefore under Buck converter prebias condition, the maximum reverse current after start is also just restricted to peak value and is no more than (VoT)/L.
(2) described pulse stops circuit application in active-clamp converter
Refer to Fig. 6, show a kind of circuit diagram of typical active-clamp converter, this converter mainly comprises: switching tube Q4, clamp switch pipe Q5, transformer T, rectifying tube Q10, continued flow tube Q11, inductance L, control circuit 101 and soft start capacitor Css, wherein, transformer T comprise former limit winding 1, with the secondary winding 2 of described former limit winding coupled, with the auxiliary winding 3 of former limit winding coupled, the annexation of each element as shown in the figure, repeats no more herein.
The driving signal of the first output output of described control circuit 101 is for driving switch pipe Q4, the driving signal of the second output output is used for driving clamp switch pipe Q5, control circuit 101 control switch pipe Q4 and clamp switch pipe Q5 alternate conduction, while being switching tube Q4 conducting, clamp switch pipe Q5 turn-offs; When switching tube Q4 turn-offs, clamp switch pipe Q5 conducting.
It should be noted that, clamp switch pipe Q5 in the present embodiment adopts P channel MOS tube to realize, therefore, the grid of clamp switch pipe Q5 is provided with level shift circuit 102, can be the negative level that clamp switch pipe Q5 needs by the low transition of the second output output of control circuit 101;
Control circuit 101 disposes soft start capacitor Css, after the start of this active-clamp converter, control circuit 101 by soft start capacitor Css gradually the duty ratio of the driving signal of charging control switch pipe Q4 increase gradually.The driving signal of secondary rectifying tube Q10 and continued flow tube Q11 is from the coupling winding of transformer T, and while normally work, rectifying tube Q10 keeps synchronizeing turn-on and turn-off with switching tube Q4, and continued flow tube Q11 and clamp switch pipe Q5 keep synchronous turn-on and turn-off.
Refer to Fig. 7, show the main waveform schematic diagram starting of the active-clamp converter shown in Fig. 6 under prebias condition, comparison diagram 7 and Fig. 3 are known, the conducting state of switching tube Q1 in the corresponding Buck converter of conducting state of switching tube Q4 in active-clamp converter, the conducting state of clamp switch pipe Q5 in active-clamp converter is the conducting state of the continued flow switch pipe Q2 in corresponding Buck converter, the Changing Pattern of inductive current IL in two kinds of converters is in full accord, has equally reverse current problem.
The Prebias boot-strap problem of active-clamp converter is said consistent with Buck converter from mechanism, therefore pulse provided by the invention stops circuit can in active-clamp converter, implement equally, but because active-clamp converter is different from Buck converter on physical circuit composition, therefore also difference to some extent of specific embodiment of the invention method, is elaborated mainly for the difference part of two kinds of converters below.
Concrete, active-clamp converter shown in Fig. 6, compared with the Buck converter shown in Fig. 2, stops the influential main difference point of enforcement of circuit to have two to described pulse: the one, and active-clamp converter has increased the isolation between transformer T inputs and exports; The 2nd, the clamp switch pipe Q5 in active-clamp converter adopts P channel MOS tube to realize, driving the driving voltage Vgs5 of clamp switch pipe Q5 conducting is negative level, and the driving signal of the second output output of corresponding control circuit 101 drives clamp switch pipe Q5 conducting while being low level.
Refer to Fig. 8, show pulse and stop circuit application in the circuit theory schematic diagram of the active-clamp converter shown in Fig. 6.
As shown in Figure 8, pulse stops circuit 200 to comprise blocking swtich pipe Q6 and transformer coupled winding NT, wherein,
The former limit winding 1 of described transformer coupled winding NT and described transformer T is coupled, the clamp switch pipe Q5 that the first end of described blocking swtich pipe Q6 and the second end are serially connected in described control circuit 101 drives in the loop of signal DRV, and the conducting direction of its parasitic body diode is consistent with the cut-off current direction of driving signal DRV, therefore, blocking swtich pipe Q6 can only stop clamp switch pipe Q5 conducting, and can not stop clamp switch pipe Q5 to turn-off.
Concrete, the Same Name of Ends of described transformer coupled winding NT connects the first end of described blocking swtich pipe Q6, meanwhile, the first end of blocking swtich pipe Q6 also connects the second output of control circuit 101, and the other end of described transformer coupled winding NT connects the control end of described blocking swtich pipe Q6.
The second end of blocking swtich pipe Q6 connects the control end of described clamp switch pipe Q5 by level shifting circuit.
It should be noted that; in the present embodiment, blocking swtich pipe Q6 adopts N-channel MOS pipe to realize; the first end of Q6 is that source electrode, the second end are that drain electrode, control end are grid; the application does not limit the type of Q6, and the switching tube of every function that can realize described blocking swtich pipe Q6 is all scopes that the application is open and protect.
Refer to Fig. 9, show the groundwork waveform schematic diagram of the circuit shown in Fig. 8, in figure, Vgs4 is the voltage waveform of the driving signal of switching tube Q4; DRV is the voltage oscillogram of the driving signal of control circuit output; DRV2 is the voltage waveform of described driving signal DRV after extra pulse stops circuit 200; Vgs5 is the voltage waveform of the driving signal of clamp switch pipe Q5; Vgs6 is the voltage waveform of the driving signal of blocking swtich pipe Q6; IQ4 is the current waveform of switching tube Q4; IL is the current waveform of inductance L; Vgs7 is the voltage waveform of the driving signal of soft start switch pipe Q7; The charging current waveform that Iss provides for soft start capacitor Css for soft start accelerating circuit, wherein applies in Vgs7 and the Iss embodiment that Figure 12 is corresponding in the back.
Transformer coupled winding NT closes and has no progeny for detection of switching tube Q4, in its parasitic body diode, whether there is reverse current, if there is reverse current, the polarity of the former limit winding 1 of transformer T is Same Name of Ends for just, the polarity of the induced voltage of transformer coupled winding NT is also Same Name of Ends for just, the driving voltage Vgs6 that makes blocking swtich pipe Q6 is negative level (the t2 moment in Fig. 9), blocking swtich pipe Q6 turn-offs, make the low level of the second output output of control circuit 101 drive signal DRV can not pass to clamp switch pipe Q5, thereby stop clamp switch pipe Q5 conducting, until the reverse current in switching tube Q4 was reduced to after zero (the t4 moment in Fig. 9), the polarity of voltage of the former limit winding of transformer T is reverse, become Same Name of Ends for negative, the induced voltage polarity of transformer coupled winding NT also becomes Same Name of Ends for negative, now, the driving voltage Vgs6 of blocking swtich pipe Q6 is high level, blocking swtich pipe Q6 conducting, make the low level of the second output output of control circuit 101 drive signal DRV can pass to clamp switch pipe Q5, thereby make clamp switch pipe Q5 conducting.
Refer to Figure 10, show the schematic block circuit diagram of another kind of DC-DC converter Prebias boot-strap circuit, on the basis of embodiment corresponding to Fig. 1, increased soft start accelerating circuit.
The DC-DC converter Prebias boot-strap circuit that the present embodiment provides comprises: DC-DC converter 100, pulse stop circuit 200, soft start accelerating circuit 300, wherein,
Described pulse stops the effect of circuit 200 to stop the effect of circuit identical with the pulse in Fig. 1, repeats no more herein;
Described soft start accelerating circuit 300 is when stoping circuit 200 to stop described functional switch pipe conducting to described pulse, output current is described soft start capacitor charging, shorten the charging process of soft start capacitor, thereby accelerate the soft start-up process of DC-DC converter, prevented that the output voltage of DC-DC converter from falling the phenomenon generation that load circuit excessive and that cause can not normally move.
Concrete, refer to Figure 11, show the circuit application shown in Figure 10 in the circuit diagram of Buck converter, on the basis of the circuit shown in Fig. 4, set up soft start accelerating circuit 300.
Referring to Figure 11, described soft start accelerating circuit 300 comprises soft start switch pipe Q9, charging resistor Rss, diode Dss, and wherein, in the present embodiment, soft start switch pipe Q9 is P channel MOS tube.
The first end of described soft start switch pipe Q9 connects the second end of blocking swtich pipe Q3, it is the first output of control circuit 101, the second end is connected to soft start capacitor Css by charging resistor Rss and diode Dss successively, and the control end of described soft start switch pipe connects the first end of described blocking swtich pipe Q3.
Concrete, waveform schematic diagram shown in Figure 5, when described blocking swtich pipe Q3 works while stoping the high level exported of control circuit 101 to drive signal DRV to be passed to described continued flow switch pipe Q2, be in Fig. 5 during t3 to t4, the driving signal Vgs9 of soft start switch pipe Q9 is negative level, soft start switch pipe Q9 conducting, soft start accelerating circuit 300 output current Iss flow to soft start capacitor Css through charging resistor Rss and diode Dss, and the size of electric current I ss can be adjusted by the size of the resistance of adjusting charging resistor Rss.
It should be noted that, in the present embodiment, soft start switch pipe Q9 adopts P channel MOS tube to realize, the first end of Q9 is that source electrode, the second end are that drain electrode, control end are grid, the application does not limit the type of Q9, and the switching tube of every function that can realize described soft start switch pipe Q9 is all scopes that the application is open and protect; In addition, while specifically application, described diode Dss and described charging resistor Rss can select application as required.
Refer to Figure 12, show the circuit application shown in Figure 10 in the circuit diagram of active-clamp converter, on the basis of the circuit shown in Fig. 8, set up soft start accelerating circuit 300.
Described soft start accelerating circuit 300 comprises: soft start switch pipe Q7, and charging resistor Rss, the first diode Dss, the second diode D1, the first capacitor C 1, the first switching tube Q8, wherein,
The first end of described soft start switch pipe Q7 is connected described soft start capacitor Css by the described charging resistor Rss being connected in series with described the first diode Dss, the second end connects the negative electrode of described the second diode D1, the first end of blocking swtich pipe Q6 described in the anodic bonding of the second diode D1, simultaneously, the second end of described soft start switch pipe Q7 is by the first capacitor C 1 ground connection, and the control end of described soft start switch pipe Q7 connects the second end of described blocking swtich pipe Q6;
The second end of described the first switching tube Q8 connects the first end of described soft start switch pipe Q7 by described charging resistor Rss, the first end of described the first switching tube Q8 connects earth terminal, and the control end of described the first switching tube Q8 connects the first end of described blocking swtich pipe Q6.
The driving signal DRV that the first switching tube Q8 is exported by control circuit 101 drives, and soft start switch pipe Q7 drives signal DRV2 to drive by the clamp switch pipe after described pulse stops circuit 200.
When stoping clamp switch pipe Q5 conducting as blocking swtich pipe Q6, while needing described soft starting circuit to provide charging current for soft start capacitor Css, the driving signal DRV that described control circuit 101 is exported is low level, this low level can not provide charging current for soft start capacitor Css, therefore the second diode D1 and the first capacitor C 1 have been set up, when the driving signal DRV exporting when control circuit 101 is high level, this high level signal charges to the first capacitor C 1 by the second diode D1, in the first capacitor C 1, set up certain voltage, like this, in the time that blocking swtich pipe Q6 stops clamp switch pipe Q5 conducting, the voltage of setting up in advance in described the first capacitor C 1 provides charging current for soft start capacitor Css.
Again owing to being between high period driving signal DRV, blocking swtich pipe Q6 is in conducting state, now, the gate-source voltage of soft start switch pipe Q7 is poor is therefore that high level is soft start switch pipe Q7 conducting, but this stage does not need to provide charging current for soft start capacitor Css, therefore set up described the first switching tube Q8, during described driving signal DRV is high level, the gate-source voltage of described the first switching tube Q8 is poor is also high level, the first switching tube Q8 is in conducting state, thereby stoped the charging to soft start capacitor Css.
Known in conjunction with Fig. 9, only have when the first switching tube Q8 shutoff, when soft start switch pipe Q7 conducting simultaneously, be low level when driving signal DRV, while driving signal DRV2 to be high level (during the t3 to t4 in Fig. 9) simultaneously, soft starting circuit 300 output current Iss are to soft start capacitor Css, thereby have accelerated the soft start-up process of active-clamp converter.During t3 to t4, be also during pulse stops circuit 200 to bring into play interception, stop negative level to drive signal to be passed to clamp switch pipe Q5.
During t2 to t3, the driving signal Vgs7 of soft start switch pipe Q7 is high level, but during this, driving signal DRV is also high level, and therefore, soft start switch pipe Q7 and the equal conducting of the first switching tube Q8, now, do not have current direction soft start capacitor Css.
It should be noted that, the soft start switch pipe Q7 in the present embodiment and the first switching tube Q8 all adopt N-channel MOS pipe to realize, and the first end of Q7 and Q8 is that source electrode, the second end are that drain electrode, control end are grid, and the application does not limit the type of Q7 and Q8.
The DC-DC converter Prebias boot-strap circuit that the embodiment of the present application provides, stop in the switching tube in electric circuit inspection DC-DC converter, whether there is reverse current by pulse, if there is reverse current, stop the driving signal of controlling functional switch pipe (the clamp switch pipe in continued flow switch pipe or active-clamp converter in the Buck converter) conducting in DC-DC converter, thereby stop the reverse current in described switching tube constantly to increase, avoided the phenomenon excessive and that lost efficacy of the device stress in DC-DC converter to occur; Utilize soft start accelerating circuit to detect when described pulse stops circuit 200 to stop described functional switch pipe conducting, output current is described soft start capacitor charging, shorten the charging process of soft start capacitor, thereby accelerate the soft start-up process of DC-DC converter, prevented that the output voltage of DC-DC converter from falling the phenomenon generation that load circuit excessive and that cause can not normally move.
Corresponding to the Prebias boot-strap circuit of above-mentioned DC-DC converter, the application also provides a kind of Prebias boot-strap method of DC-DC converter, refer to Figure 13, show the schematic flow sheet of the Prebias boot-strap method of a kind of DC-DC converter of the embodiment of the present application.
Described method is applied in DC-DC converter, mainly comprises:
S101, detects switching tube in described DC-DC converter in the time turn-offing, and whether has reverse current in described switching tube, obtains the first testing result;
S102, in the time the first testing result that has reverse current in described switching tube being detected, stop the conducting of described functional switch pipe, until described reverse current is decreased to zero, described functional switch pipe is continued flow switch pipe or the clamp switch pipe in described DC-DC converter.
Concrete, in the time that described DC-DC converter is Buck converter, described functional switch pipe is continued flow switch pipe; When described DC-DC converter is active-clamp converter, described functional switch pipe is clamp switch pipe.
S103, in the time the first testing result that has reverse current in described switching tube being detected, is described soft start capacitor charging.
The Prebias boot-strap method of the DC-DC converter that the present embodiment provides, detect switching tube in described DC-DC converter in the time turn-offing, in described switching tube, whether there is reverse current, if there is reverse current, because functional switch pipe (such as the clamp switch pipe in the continued flow switch pipe in Buck converter or the source clamp converter) conducting in described DC-DC converter causes, now, stop the conducting of described functional switch pipe, until described reverse current is decreased to zero, thereby can stop reverse current constantly to increase, reverse current is limited in to less degree effectively, avoid the phenomenon excessive and that lost efficacy of the device stress in DC-DC converter to occur, extend the useful life of DC-DC converter.And if there is reverse current in described switching tube, for soft start capacitor provides charging current, start quickly process, prevents that the output voltage of DC-DC converter from falling the phenomenon generation that load circuit excessive and that cause can not normally move.
It should be noted that, in this article, relational terms such as the first and second grades is only used for an entity or operation to separate with another entity or operating space, and not necessarily requires or imply and between these entities or operation, have the relation of any this reality or sequentially.
The above is only the application's embodiment; it should be pointed out that for those skilled in the art, do not departing under the prerequisite of the application's principle; can also make some improvements and modifications, these improvements and modifications also should be considered as the application's protection range.
Claims (10)
1. a Prebias boot-strap circuit for DC-DC converter, is characterized in that, comprising:
The pulse being electrically connected with described DC-DC converter stops circuit, described pulse stop circuit for detection of the switching tube in described DC-DC converter in turn-offing, and while there is reverse current in described switching tube, stop the conducting driving pulse of the functional switch pipe in described DC-DC converter to be passed to described functional switch pipe, to stop the conducting of described functional switch pipe, until described reverse current is reduced to zero, described functional switch pipe is continued flow switch pipe or the clamp switch pipe in described DC-DC converter;
Described DC-DC converter is Buck converter or active-clamp converter;
Described Buck converter mainly comprises: control circuit, switching tube, continued flow switch pipe and the first inductance, and described pulse stops circuit to comprise: the second inductance, blocking swtich pipe, wherein:
Described the second inductance and described the first inductance are coupled, and the Same Name of Ends of described the second inductance connects the first end of described blocking swtich pipe, and described first end connects the control end of described continued flow switch pipe, the other end of described the second inductance connects the control end of described blocking swtich pipe, and described the second inductance is used for judging whether described switching tube exists reverse current;
The second end of described blocking swtich pipe connects the first output of described control circuit, when described blocking swtich pipe exists reverse current for described the second inductance detection to described switching tube, stop the driving pulse of the described continued flow switch pipe of the control conducting of described control circuit the first output output to be passed to described continued flow switch pipe;
Described active-clamp converter mainly comprises: control circuit, switching tube, clamp switch pipe and transformer, described transformer comprises former limit winding, secondary winding with described former limit winding coupled, the auxiliary winding being coupled with described former limit winding, it is characterized in that, described pulse stops circuit to comprise: transformer coupled winding, blocking swtich pipe, wherein:
Described transformer coupled winding and described former limit winding coupled, and the Same Name of Ends of described transformer coupled winding is connected with the first end of described blocking swtich pipe, and described first end connects the second output of described control circuit, the other end of described transformer coupled winding connects the control end of described blocking swtich pipe, and described transformer coupled winding is for detection of whether there being reverse current in described switching tube;
The second end of described blocking swtich pipe connects the control end of described clamp switch pipe, described blocking swtich pipe detects when described switching tube exists reverse current for transformer coupled winding, stops the driving pulse of the described clamp switch pipe of the control conducting of described control circuit the second output output to be passed to described clamp switch pipe.
2. according to the Prebias boot-strap circuit of the DC-DC converter described in claim 1 any one, described DC-DC converter comprises soft start capacitor, it is characterized in that, also comprise: be connected to described pulse and stop the soft start accelerating circuit between circuit and described soft start capacitor, described soft start accelerating circuit is when stoping circuit to stop described functional switch pipe conducting to described pulse, and output current is described soft start capacitor charging.
3. the Prebias boot-strap circuit of DC-DC converter according to claim 2, it is characterized in that, described DC-DC converter is Buck converter, described soft start accelerating circuit comprises soft start switch pipe, the first end of described soft start switch pipe connects the second end of described blocking swtich pipe, the control end of described soft start switch pipe connects the first end of described blocking swtich pipe, the second end of described soft start switch pipe connects described soft start capacitor, in the time that described blocking swtich pipe stops described continued flow switch pipe conducting, the conducting of described soft start switch pipe, for described soft start capacitor provides charging current.
4. the Prebias boot-strap circuit of DC-DC converter according to claim 3, it is characterized in that, described soft start accelerating circuit also comprises: be serially connected in successively charging resistor and diode between the second end and the described soft start switch pipe of described soft start switch pipe, described charging current flows into described soft start capacitor through described charging resistor and described diode.
5. the Prebias boot-strap circuit of DC-DC converter according to claim 2, it is characterized in that, described DC-DC converter is active-clamp converter, described soft start accelerating circuit comprises: soft start switch pipe, the first switching tube, charging resistor, the first diode, the second diode and the first electric capacity, wherein:
The first end of described soft start switch pipe is connected described soft start capacitor by the charging resistor of connecting successively with the first diode, the second end of described soft start switch pipe connects the first end of described blocking swtich pipe, and the control end of described soft start switch pipe connects the second end of described blocking swtich pipe;
The first end of described the first switching tube connects earth terminal, and the second end connects the common port of described charging resistor and described the first diode, and control end connects the first end of described blocking swtich pipe;
The anodic bonding of described the second diode is at the first end of described blocking swtich pipe, and negative electrode connects the second end of described soft start switch pipe;
Described first electric capacity one end connects the negative electrode of described the second diode, and the other end connects described earth terminal
In the time that described blocking swtich pipe stops described clamp switch pipe conducting, the conducting of described soft start switch pipe, described the first switching tube cut-off, for described soft start capacitor provides charging current.
6. the Prebias boot-strap circuit of DC-DC converter according to claim 1, is characterized in that, described blocking swtich pipe is N-type metal-oxide-semiconductor, and described first end is that source electrode, the second end are drain electrode, and control end is grid.
7. according to the Prebias boot-strap circuit of the DC-DC converter described in claim 3 or 4, it is characterized in that, described soft start switch pipe is PMOS pipe, and described first end is that source electrode, the second end are drain electrode, and described control end is grid.
8. the Prebias boot-strap circuit of DC-DC converter according to claim 5, is characterized in that, described soft start switch pipe and described the first switching tube are NMOS pipe, and described first end is that source electrode, the second end are drain electrode, and control end is grid.
9. a Prebias boot-strap control method for DC-DC converter, is characterized in that, comprising:
When pulse stop electric circuit inspection to the switching tube in described DC-DC converter in the time turn-offing, in described switching tube, whether there is reverse current, obtain the first testing result;
When pulse stops electric circuit inspection when there is the first testing result of reverse current in described switching tube, stop the functional switch pipe conducting in described DC-DC converter, until described reverse current is decreased to zero, described functional switch pipe is continued flow switch pipe or the clamp switch pipe in described DC-DC converter;
Wherein said DC-DC converter is Buck converter or active-clamp converter;
Described Buck converter mainly comprises: control circuit, switching tube, continued flow switch pipe and the first inductance, and described pulse stops circuit to comprise: the second inductance, blocking swtich pipe, wherein:
Described the second inductance and described the first inductance are coupled, and the Same Name of Ends of described the second inductance connects the first end of described blocking swtich pipe, and described first end connects the control end of described continued flow switch pipe, the other end of described the second inductance connects the control end of described blocking swtich pipe, and described the second inductance is used for judging whether described switching tube exists reverse current;
The second end of described blocking swtich pipe connects the first output of described control circuit, when described blocking swtich pipe exists reverse current for described the second inductance detection to described switching tube, stop the driving pulse of the described continued flow switch pipe of the control conducting of described control circuit the first output output to be passed to described continued flow switch pipe;
Described active-clamp converter mainly comprises: control circuit, switching tube, clamp switch pipe and transformer, described transformer comprises former limit winding, secondary winding with described former limit winding coupled, the auxiliary winding being coupled with described former limit winding, it is characterized in that, described pulse stops circuit to comprise: transformer coupled winding, blocking swtich pipe, wherein:
Described transformer coupled winding and described former limit winding coupled, and the Same Name of Ends of described transformer coupled winding is connected with the first end of described blocking swtich pipe, and described first end connects the second output of described control circuit, the other end of described transformer coupled winding connects the control end of described blocking swtich pipe, and described transformer coupled winding is for detection of whether there being reverse current in described switching tube;
The second end of described blocking swtich pipe connects the control end of described clamp switch pipe, described blocking swtich pipe detects when described switching tube exists reverse current for transformer coupled winding, stops the driving pulse of the described clamp switch pipe of the control conducting of described control circuit the second output output to be passed to described clamp switch pipe.
10. method according to claim 9, described DC-DC converter comprises soft start capacitor, it is characterized in that, the method also comprises: in the time the first testing result that has reverse current in described switching tube being detected, be described soft start capacitor charging.
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| CN103825458B (en) * | 2014-03-21 | 2016-11-16 | 大陆汽车投资（上海）有限公司 | DC-to-DC converter and pre-charge method |
| CN107078643B (en) * | 2014-10-11 | 2019-12-31 | 德克萨斯仪器股份有限公司 | Pre-biased start-up of a converter |
| CN105790616B (en) * | 2016-05-27 | 2018-12-18 | 广东美的制冷设备有限公司 | PFC pfc circuit and its inductance discrimination method and device |
| CN107482885B (en) | 2017-09-01 | 2019-12-06 | 华为数字技术（苏州）有限公司 | Follow current tube control method and device and switching power supply device |
| CN108696122B (en) * | 2018-02-07 | 2020-08-18 | 深圳航天科技创新研究院 | High-conversion-efficiency voltage conversion circuit applied to high-power-density occasions |
| CN112363384B (en) * | 2020-11-23 | 2022-11-25 | 上海新时达机器人有限公司 | Control circuit and control system |
| CN112803745B (en) * | 2020-12-31 | 2022-05-27 | 广东美的制冷设备有限公司 | Current control method, device and storage medium |
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| CN101860186A (en) * | 2010-04-21 | 2010-10-13 | 艾默生网络能源有限公司 | Prebias boot-strap circuit for direct current converter and direct current converter |
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| US5726869A (en) * | 1995-10-05 | 1998-03-10 | Fujitsu Limited | Synchronous rectifier type DC-to-DC converter in which a saturable inductive device is connected in series with a secondary-side switching device |
| CN101630911A (en) * | 2009-08-13 | 2010-01-20 | 艾默生网络能源有限公司 | DC/DC converter and pre-bias switching circuit thereof |
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