Background technology
The control technology of Switching Power Supply mainly contains three kinds: pulse width modulation (PWM), pulse frequency modulated (PFM) and pulse duration frequency modulation(FM) (PWM-PFM).
Modulation signal changes with input signal amplitude in the PFM modulation technique, and promptly modulation signal is the pulse signal of frequency change, and it has or not the control stabilization output voltage through pulse signal.During the PFM modulation, mains switch frequency system for tracking load variations, so the PFM modulation system makes switch power supply system have higher efficient under the underload, this is the main cause that the PFM modulation system is used widely.In addition, under the PFM modulation system Switching Power Supply be generally operational in the inductive current discontinuous mode promptly the next work period begin before inductive current stabilized to 0, otherwise inductive current is easy to occur vibration.The PFM modulation system load capacity that is operated under the inductive current discontinuous mode is limited; Therefore along with the increase of system load electric current; Switching Power Supply must operate at the inductive current continuous mode; And the control of the PFM modulation system system of inductive current continuous mode is very complicated, is easy to occur the vibration of output voltage and inductive current.Therefore extensively adopt the PWM modulation system under system's heavy duty.
The PWM modulation technique is under the constant situation of switching frequency, regulates its duty ratio through Voltage Feedback, thereby reaches the purpose of regulated output voltage.Switching Power Supply is generally operational in the inductive current continuous mode under the PWM modulation system, and this moment, power-supply system had enough load capacity.Though PWM modulation system switching frequency is generally high than PFM modulation system, cause under the PWM modulating mode switching loss bigger, under the heavy duty, switching loss is much smaller than conduction loss, so still has very high efficient under the PWM modulating mode heavy duty.In addition, output voltage ripple is less under the PWM modulation system, and fixing simultaneously switching frequency has been simplified the EMI design.
Present most switch power supply system adopts the PFM-PWM compound modulation, promptly adopts the PFM modulating mode under the underload, adopts the PWM modulation system under the heavy duty.Power-supply system not only has very high transformation efficiency in whole loading range like this, and has expanded the carrying load ability of switch power supply system greatly.
Fig. 1 is existing Switching Power Supply structure, and it converts input voltage to the output voltage of setting.Switching Power Supply shown in Figure 1 is divided into three modules, is respectively switching frequency generator 200, inductance peak current controller 300 and power transfer module 100.Switching frequency generator 200 provides Switching Power Supply needed switching frequency signal, and inductance peak current controller 300 provides Switching Power Supply needed peak current control signal, the peak value size of control switching inductive current.
It is existing that to be example with DC/DC BUCK transducer describe the control principle of Fig. 1; Among Fig. 2 (b) and (c) be the inductive current oscillogram of Switching Power Supply under PFM fixed inductance peak-current mode, its generation under the modulation of the clock signal C lock of figure (a) fixed frequency and figure (b) inductance peak-current signal Ipeak.The different inductive current waveforms of importing under power supply Vin1 and the Vin2 of figure (b) with figure (c) representative.Inductive current rate of rise k1=(Vin1-Vout)/L, k3=(Vin2-Vout)/L, inductive current descending slope k2=Vout/L.Wherein Vout is the output voltage of power supply changeover device, and L is an inductance value.Inductive current rise time Ton1 is by input power supply and out-put supply poor (Vin1-Vout), inductance value L and inductance peak current Ipeak decision; Inductive current rise time Ton2 is by input power supply and out-put supply poor (Vin2-Vout), inductance value L and inductance peak current Ipeak decision, and inductive current Toff fall time is by out-put supply Vout, inductance value L and inductance peak current Ipeak decision.So for same DC/DC BUCK transducer, inductive current rise time and identical inductive current fall time that different output supply voltages is corresponding different.Dead Time Tdt1 is by clock signal C lock cycle, the inductive current rise time Ton1 and the inductive current Toff fall time decision of fixed frequency; Dead Time Tdt2 is by clock signal C lock cycle, the inductive current rise time Ton2 and the inductive current Toff fall time decision of fixed frequency; Because the switching frequency cycle is fixed, the therefore different corresponding different Dead Times of input supply voltage.Be in the DC/DC BUCK transducer of stable state, the mean value of one-period internal inductance electric current equals load current, thus among Fig. 2 for identical inductance peak current Ipeak, figure (b) is with to scheme (c) load capacity different, Dead Time is more little, load capacity is big more.That is to say, for the DC/DCBUCK transducer, during PFM discontinuous mode fixed inductance peak current, the load capacity that different input voltages is corresponding different, and maximum load capability is less than 1/2nd inductance peak currents.
But; For the PFM-PWM compound modulation; The compound modulation that automaticallyes switch of PFM-PWM particularly; The load capacity of Switching Power Supply under the PFM pattern is very crucial, otherwise Switching Power Supply just must automatically switch to the PWM pattern under underload, thereby causes the conversion efficiency of Switching Power Supply to descend.Strengthening Switching Power Supply conventional way of load capacity under the PFM modulating mode is to realize through increasing the inductance peak current, but the increase of inductance peak current can cause the break-over of device loss to increase under the underload, thereby sacrifices the conversion efficiency of Switching Power Supply.
In addition; The inductive current of existing Switching Power Supply under PFM inductive current discontinuous mode is not the process that in each clock cycle, all has inductive energy storage and exoergic; It is hop cycle that industry is commonly called as in certain cycle inductive current cycle of 0 of remaining always; Fig. 3 is there is hop cycle in Switching Power Supply under PFM inductive current discontinuous mode an inductive current oscillogram, and Tdt1 is a hop cycle.Within a certain period of time, total hop cycle number is determined that by load current load current is more little, and the hop cycle number is many more.The existence of hop cycle make Switching Power Supply under underload power supply conversion efficiency greater than the PWM pattern.One of shortcoming of skip cycle mode is if occur big load current in the hop cycle; Switching Power Supply need wait for that this hop cycle is by the detection that just begins following one-period after finishing in the original plan; And in hop cycle; Load current is fully by the output capacitance power supply, so hop cycle can have a strong impact on the load transient response of Switching Power Supply under the PFM pattern.
Summary of the invention
The purpose of the embodiment of the invention is to provide a kind of Switching Power Supply, is intended to solve existing Switching Power Supply and under the PFM pattern, has the raising load capacity and improve the problem that conversion efficiency can not be taken into account.
The embodiment of the invention is achieved in that a kind of Switching Power Supply, and said Switching Power Supply comprises:
Power transfer module and switching frequency generator;
Power transfer module comprises inductance, and the electric current that flows through in the said inductance is an inductive current;
The switching frequency generator is used to provide power transfer module needed switching frequency signal, and said switching frequency signal is periodic pulse signal;
The switching frequency generator; Also be used to receive the inductive current entering dead band signal of said power transfer module output; The switching frequency signal that sends after modulating is given said power transfer module; After making that inductive current gets into Dead Time, the switching frequency signal after the modulation finishes this cycle fast, begins following one-period.
In the said structure, said Switching Power Supply also comprises:
The load current detection module is used to detect the load current of said Switching Power Supply, and testing result is fed back to said switching frequency generator;
The switching frequency generator; Also be used to receive the testing result of said load current detection module feedback; If in hop cycle, the load current of the value of being above standard appears, and the switching frequency signal that sends after modulating is given said power transfer module; Make the switching frequency signal after the modulation finish this hop cycle fast, begin following one-period.
In the said structure, said Switching Power Supply also comprises:
The inductance peak current controller is used for sending the peak current control signal to said power transfer module, the peak value size of control inductive current.
In the said structure, said Switching Power Supply also comprises:
The load current detection module is used to detect load current, and testing result is fed back to said inductance peak current controller;
The inductance peak current controller also is used to receive the testing result of said load current detection module feedback, sends the peak current control signal to said power transfer module, makes the inductance peak current follow the variation of load current and change.
In the said structure, the load current detection module also is used for testing result is fed back to said switching frequency generator;
The switching frequency generator; Also be used to receive the testing result of said load current detection module feedback; If in hop cycle, the load current of the value of being above standard appears, and the switching frequency signal that sends after modulating is given said power transfer module; Make the switching frequency signal after the modulation finish this hop cycle fast, begin following one-period.
In embodiments of the present invention; Because the switching frequency generator receives the entering dead band signal of power transfer module output; And send the switching frequency signal and give power transfer module, finish this cycle after making the inductive current of Switching Power Supply get into Dead Time, begin following one-period; Inductive current almost is operated in critical conduction mode like this, improves the load capacity of Switching Power Supply under the PFM discontinuous mode.
Another purpose of the embodiment of the invention is to provide a kind of Switching Power Supply, and said Switching Power Supply comprises power transfer module, load current detection module and inductance peak current controller;
Power transfer module comprises inductance, and the electric current that flows through in the said inductance is an inductive current;
The load current detection module is used to detect load current, and testing result is fed back to said inductance peak current controller;
The inductance peak current controller is used for the testing result according to said load current detection module feedback, sends the peak current control signal to said power transfer module, makes the inductance peak current follow the variation of said load current and change.
In embodiments of the present invention, because Switching Power Supply is provided with load current detection module and inductance peak current controller, the inductance peak current controller is according to the testing result of load current detection module feedback; Sending the peak current control signal to power transfer module makes the inductance peak current of Switching Power Supply follow the variation of said load current and change; Under underload, the inductive current of Switching Power Supply is smaller, thereby the break-over of device loss ratio is lower in the Switching Power Supply; Can increase substantially the conversion efficiency of Switching Power Supply; Along with the increase of load, the inductive current of Switching Power Supply is along with increase, thereby strengthens the load capacity of Switching Power Supply and reduce switching loss.
Another purpose of the embodiment of the invention is to provide a kind of Switching Power Supply, is intended to solve existing Switching Power Supply and under the PFM pattern, exists hop cycle can have a strong impact on the problem of the load transient response of Switching Power Supply.
The embodiment of the invention is achieved in that a kind of Switching Power Supply, and said Switching Power Supply comprises power transfer module, load current detection module and switching frequency generator;
Power transfer module comprises inductance, and the electric current that flows through in the said inductance is an inductive current;
The load current detection module is used to detect load current, and testing result is fed back to said switching frequency generator;
The switching frequency generator is used to provide power transfer module needed switching frequency signal, and said switching frequency signal is periodic pulse signal;
The switching frequency generator; Also be used to receive the testing result of said load current detection module feedback; If in hop cycle, the load current of the value of being above standard appears, and the switching frequency signal that sends after modulating is given said power transfer module; This hop cycle of switching frequency signal ended after the feasible modulation begins following one-period.
In the said structure, said Switching Power Supply also comprises:
The inductance peak current controller is used for sending the peak current control signal to said power transfer module, the peak value size of control inductive current.
In the said structure, the load current detection module also is used to detect the load current of said Switching Power Supply, and testing result is fed back to said inductance peak current controller;
The inductance peak current controller also is used to receive the testing result of said load current detection module feedback, sends the peak current control signal to said power transfer module, makes the inductance peak current follow the variation of load current and change.
In embodiments of the present invention, because Switching Power Supply is provided with the load current detection module, the switching frequency generator is according to the testing result of load current detection module feedback; If in hop cycle, the load current of the value of being above standard appears, and the transmit button frequency signal is given power transfer module; Make the inductive current of Switching Power Supply finish this hop cycle; Begin following one-period, shorten the time of hop cycle, improve the load transient response of Switching Power Supply.
Embodiment
In order to make the object of the invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with accompanying drawing and embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.
Fig. 4 shows the structure of the Switching Power Supply that first embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
Switching Power Supply comprises:
Power transfer module 101 and switching frequency generator 201;
Power transfer module 101 comprises inductance, and the electric current that flows through in the inductance is an inductive current;
Switching frequency generator 201 is used to provide power transfer module 101 needed switching frequency signals, and the switching frequency signal is periodic pulse signal; Switching frequency generator 201; Also be used to receive the inductive current entering dead band signal of power transfer module 101 outputs; The switching frequency signal that sends after modulating is given power transfer module 101; Make inductive current get into behind the Dead Time fast, in switching frequency this cycle of signal ended after the modulation, begin following one-period.
In embodiments of the present invention; Because the switching frequency generator receives the entering dead band signal of power transfer module output, and send the switching frequency signal and give power transfer module, make that the inductive current of Switching Power Supply gets into Dead Time after; Switching frequency this cycle of signal ended after the modulation; Begin following one-period, inductive current almost is operated in critical conduction mode like this, improves the load capacity of Switching Power Supply under the PFM discontinuous mode.
Fig. 5 shows the structure of the Switching Power Supply that second embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
On the basis of first embodiment of the invention, Switching Power Supply also comprises:
Load current detection module 401 is used for the load current of sense switch power supply, and testing result is fed back to switching frequency generator 201;
Switching frequency generator 201; Also be used to receive the testing result of load current detection module 401 feedbacks; If in hop cycle, the load current of the value of being above standard appears, and the switching frequency signal that sends after modulating is given power transfer module 101; Make the switching frequency signal after the modulation finish this hop cycle fast, begin following one-period.
Fig. 6 shows the structure of the Switching Power Supply that third embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
On the basis of first embodiment of the invention, Switching Power Supply also comprises:
Inductance peak current controller 301 is used for sending the peak current control signal to power transfer module 101, the peak value size of control inductive current.
The Switching Power Supply that Fig. 7 shows the embodiment of the invention to be provided is the inductive current waveform of Fig. 6 structure, for the ease of explanation, only shows the part relevant with the present invention.
Wherein, figure (a) and the switching frequency signal that (c) is got into respectively after the modulation of dead band signal, scheming (b) is respectively the inductive current waveform under the different input supply voltages with (d).Get into Dead Time immediately or after postponing a period of time in case its operation principle is an inductive current, finish this cycle fast, begin the detection of following one-period then.Inductive current almost is operated in critical conduction mode like this, improves the load capacity of Switching Power Supply under PFM inductive current discontinuous mode.
Fig. 8 shows the structure of the Switching Power Supply that fourth embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
On the basis of third embodiment of the invention, Switching Power Supply also comprises:
Load current detection module 401 is used to detect load current, and testing result is fed back to inductance peak current controller 301;
Inductance peak current controller 301 also is used to receive the testing result of load current detection module 401 feedbacks, sends the peak current control signals to power transfer module 101, makes the inductance peak current follow the variation of load current and change.
The Switching Power Supply that Fig. 9 shows the embodiment of the invention to be provided is the inductive current waveform of Fig. 8 structure, for the ease of explanation, only shows the part relevant with the present invention.
In case inductive current gets into Dead Time immediately or after postponing a period of time, finishes this cycle fast, begins the detection of following one-period then; Inductance peak current in first clock cycle is Ipeak1, and after the load current detection module detected the load current increase, the inductance peak current in the next clock cycle of control was Ipeak2.Thereby power supply conversion efficiency strengthens to have realized strengthening Switching Power Supply load capacity under PFM inductive current discontinuous mode simultaneously.
Figure 10 shows the structure of the Switching Power Supply that fifth embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
On the basis of fourth embodiment of the invention, load current detection module 401 also is used for testing result is fed back to switching frequency generator 201;
Switching frequency generator 201; Also be used to receive the testing result of load current detection module 401 feedbacks; If in hop cycle, the load current of the value of being above standard appears, and the switching frequency signal that sends after modulating is given power transfer module 101; Make the switching frequency signal after the modulation finish this hop cycle fast, begin following one-period.
The Switching Power Supply that Figure 11 shows the embodiment of the invention to be provided is the inductive current waveform of Figure 10 structure, for the ease of explanation, only shows the part relevant with the present invention.
First switching frequency is in the cycle, and the inductance peak current is Ipeak1; Second switching frequency cycle is hop cycle; The 3rd switching frequency is in the cycle, and the inductance peak current is Ipeak2.Can find out: (first switching frequency cycle and the 3rd switching frequency cycle) is in case produce entering dead band signal in the switch periods of non-hop cycle; Get into the dead band signal and just the switch frequency signal is regulated, Switching Power Supply load capacity under PFM inductive current discontinuous mode is strengthened; If the big load current of (second switching frequency cycle) appearance then finishes this switch periods immediately in the hop cycle, begin the detection of following one-period then; If before the cycle, load current detection module 401 detects load current greater than the load current of first switching frequency in the cycle, just controls inductance peak current controller 301 the inductance peak current is increased to Ipeak2 from Ipeak1 at the 3rd switching frequency.
Figure 12 shows the structure of the Switching Power Supply that sixth embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
Switching Power Supply comprises power transfer module 101, load current detection module 401 and inductance peak current controller 301;
Power transfer module 101 comprises inductance, and the electric current that flows through in the inductance is an inductive current; Load current detection module 401 is used to detect load current, and testing result is fed back to inductance peak current controller 301;
Inductance peak current controller 301 is used for the testing result according to load current detection module 401 feedback, sends the peak current control signals to power transfer module 101, makes the inductance peak current follow the variation of load current and change.
In embodiments of the present invention, because Switching Power Supply is provided with load current detection module and inductance peak current controller, the inductance peak current controller is according to the testing result of load current detection module feedback; Sending the peak current control signal to power transfer module makes the inductance peak current of Switching Power Supply follow the variation of said load current and change; Under underload, the inductive current of Switching Power Supply is smaller, thereby the break-over of device loss ratio is lower in the Switching Power Supply; Can increase substantially the conversion efficiency of Switching Power Supply; Along with the increase of load, the inductive current of Switching Power Supply is along with increase, thereby strengthens the load capacity of Switching Power Supply and reduce switching loss.
Figure 13 shows the structure of the Switching Power Supply that seventh embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
Switching Power Supply comprises power transfer module 101, load current detection module 401 and switching frequency generator 201;
Power transfer module 101 comprises inductance, and the electric current that flows through in the inductance is an inductive current;
Load current detection module 401 is used to detect load current, and testing result is fed back to switching frequency generator 201;
Switching frequency generator 201 is used to provide power transfer module 101 needed switching frequency signals, and the switching frequency signal is periodic pulse signal; Switching frequency generator 201; Also be used to receive the testing result of load current detection module 401 feedbacks; If in hop cycle, the load current of the value of being above standard appears, and the switching frequency signal that sends after modulating is given power transfer module 101; This hop cycle of switching frequency signal ended after the feasible modulation begins following one-period.
In embodiments of the present invention, because Switching Power Supply is provided with the load current detection module, the switching frequency generator is according to the testing result of load current detection module feedback; If in hop cycle, the load current of the value of being above standard appears, and the transmit button frequency signal is given power transfer module; Make the inductive current of Switching Power Supply finish this hop cycle; Begin following one-period, shorten the time of hop cycle, improve the load transient response of Switching Power Supply.
Figure 14 shows the structure of the Switching Power Supply that eighth embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
On the basis of seventh embodiment of the invention, Switching Power Supply also comprises:
Inductance peak current controller 301 is used for sending the peak current control signal to power transfer module 101, the peak value size of control inductive current.
The Switching Power Supply that Figure 15 shows the embodiment of the invention to be provided is the inductive current waveform of Figure 14 structure, for the ease of explanation, only shows the part relevant with the present invention.
In inductive current remains certain switch periods of 0 always, if big load current occurs, then finish this switch periods immediately, begin the detection of following one-period then.So need not wait for that inductive current 0 the cycle of always remaining just begins the detection of following one-period after finishing in the original plan, thereby shorten the time of hop cycle greatly, improve the load transient response of Switching Power Supply.
In embodiments of the present invention, because Switching Power Supply is provided with the load current detection module, the switching frequency generator is according to the testing result of load current detection module feedback; If in hop cycle, the load current of the value of being above standard appears, and the transmit button frequency signal is given power transfer module; Make the inductive current of Switching Power Supply finish this hop cycle; Begin following one-period, shorten the time of hop cycle, improve the load transient response of Switching Power Supply.
Figure 16 shows the structure of the Switching Power Supply that nineth embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
On the basis of eighth embodiment of the invention, load current detection module 401 also is used for the load current of sense switch power supply, and testing result is fed back to inductance peak current controller 301;
Inductance peak current controller 301 also is used to receive the testing result of load current detection module 401 feedbacks, sends the peak current control signals to power transfer module 101, makes the inductance peak current follow the variation of load current and change.
Figure 17 shows the structure of the switching frequency generator that the embodiment of the invention provides, and for the ease of explanation, only shows the part relevant with the present invention.
Switching frequency generator 201 comprises:
Variable resistor R, capacitor C, inverter U1, inverter U2 and inverter U3;
The output of inverter U1 is the output termination power transfer module 101 of switching frequency generator 201; Connect the input of inverter U3 simultaneously; The input of the output termination inverter U2 of inverter U3, first end of the output termination variable resistor R of inverter U2, the control end of variable resistor R are the input termination power transfer module 101 of switching frequency generator 201; Second end of variable resistor R is leaded up to capacitor C ground connection, and another road connects the input of inverter U1.
The circular oscillator that switching frequency generator 201 postpones for band RC, the clock signal frequency of the switching frequency signal of its output is about 1/2 π RC.Get into the dead band signal and come the control clock signal frequency through the size of control variable resistor R.When Switching Power Supply was not operated in Dead Time, the size of variable resistor R was R1; When in case the dead band signal occurs, reduce variable resistor immediately, make variable resistor R from R1 become R2 (R2<R1), thus accelerate clock signal frequency; In case during the blackout of dead band, make variable resistor become R1 immediately from R2.
In embodiments of the present invention, because Switching Power Supply is provided with the load current detection module, the inductance peak current controller is according to the testing result of load current detection module feedback; Follow the variation of said load current and change to the transmit control signal inductance peak current that makes Switching Power Supply of power transfer module; Under underload, the inductive current of Switching Power Supply is smaller, thereby the break-over of device loss ratio is lower in the Switching Power Supply; Can increase substantially the conversion efficiency of Switching Power Supply; Along with the increase of load, the inductive current of Switching Power Supply is along with increase, thereby strengthens the load capacity of Switching Power Supply and reduce switching loss; Simultaneously; The switching frequency generator receives the entering dead band signal of power transfer module output; The transmit button frequency signal is given power transfer module, finishes this cycle after making the inductive current of Switching Power Supply get into Dead Time, begins following one-period; Inductive current almost is operated in critical conduction mode like this, improves the load capacity of Switching Power Supply under the PFM discontinuous mode.In addition, the switching frequency generator is according to the testing result of load current detection module feedback, if in hop cycle; The load current that the value of being above standard occurs; The transmit button frequency signal is given power transfer module, makes the inductive current of Switching Power Supply finish this hop cycle, begins following one-period; Shorten the time of hop cycle, improve the load transient response of Switching Power Supply.
The above is merely preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of within spirit of the present invention and principle, being done, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.