CN102214986A - System for providing working frequency for switching power supply converter - Google Patents

System for providing working frequency for switching power supply converter Download PDF

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Publication number
CN102214986A
CN102214986A CN2010101410895A CN201010141089A CN102214986A CN 102214986 A CN102214986 A CN 102214986A CN 2010101410895 A CN2010101410895 A CN 2010101410895A CN 201010141089 A CN201010141089 A CN 201010141089A CN 102214986 A CN102214986 A CN 102214986A
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China
Prior art keywords
output signal
signal
circuit
control circuit
oscillator
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Pending
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CN2010101410895A
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Chinese (zh)
Inventor
邓丽
赵宏伟
李拓
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DALIAN JINGTUO PHOTOELECTRIC CO LTD
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DALIAN JINGTUO PHOTOELECTRIC CO LTD
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Priority to CN2010101410895A priority Critical patent/CN102214986A/en
Publication of CN102214986A publication Critical patent/CN102214986A/en
Pending legal-status Critical Current

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Abstract

The invention provides a system for providing working frequency for a switching power supply converter. The system comprises a feedback input circuit, a variable frequency and intermittent mode control circuit, a logical control circuit, an oscillator and a PWM (Pulse Width Modulation) generator, wherein the feedback input circuit is used for feeding a load state back into an integrated circuit through an optical coupling device and generating a first control signal; the variable frequency and intermittent mode control circuit is configured to receive the first control signal and generate a first output signal related to the frequency; the logical control circuit is configured to receive the first output signal and a sawtooth wave signal of the oscillator to form a second output signal; the oscillator is configured to receive the second output signal to control the charging and the discharging of a capacitor through current to form a third output signal (a sawtooth wave signal); and the PWM generator is configured to receive the second output signal and the third output signal to form a fourth output signal for switching on or off a power switch of the switching mode power supply converter. Through the system, the working frequency of a switching power supply is controlled to change along with the change of a load, so that the aim of reducing power consumption is achieved, and the efficiency of the system is increased.

Description

Be used to switching power converters that the system of operating frequency is provided
Technical field
The invention provides a kind of system that is used to switching power converters that operating frequency is provided.The present invention is applied to field of switch power.
Background technology
High frequency switch power is by the high-frequency work of MOSFET or IGBT, and its switching frequency generally is controlled at 50 KHz in 100 kilohertz range, can realize high efficiency and miniaturization like this.The rising of switching frequency, filter inductance sensibility reciprocal and output capacitance capacity are descended, be beneficial to the miniaturization of Switching Power Supply, but while switching tube and transformer loss meeting increase thereupon, need to select suitable switching tube and magnetic material to reduce loss, thereby cause the rising on the cost.
With the inverse-excitation type switch power-supply transducer is example, and power consumption mainly comprises the consumption of conduction loss, switch cost and control circuit self, and these losses all have much relations with the frequency of switch.Higher switching frequency can reduce the requirement of transducer to energy-storage travelling wave tube (inductance and electric capacity) size, but when load reduction, adopts identical switching frequency only can reduce the ratio of actual power and apparent power, causes bigger power loss.
Summary of the invention
The present invention is a kind of system that is used to switching power converters that operating frequency is provided, and the operating frequency of control switching of the present invention changes with the variation of load, has reached the purpose that reduces power consumption, has improved the efficient of system.
Described system comprises: the feedback input circuit feeds back to load condition IC interior and produces first control signal by Light Coupled Device; Frequency conversion and intermittent mode control circuit are configured to receive first control signal and produce first output signal relevant with frequency; Logic control circuit, the sawtooth signal that is configured to receive first output signal and oscillator forms second output signal; Oscillator is configured to receive the second output signal Control current capacitor charge and discharge is formed the 3rd output signal (sawtooth signal); PWM generator is configured to receive the 4th output signal that second output signal and the 3rd output signal form the mains switch that is used for turning on and off switched mode power converter.
The present invention is used to provide the system of sawtooth waveforms oscillator signal to comprise current mirror, two comparators, a rest-set flip-flop and other digital circuits.Current mirror is by charging and the discharge generation sawtooth signal to electric capacity, and electric current is that reference current source is come by a series of current mirror mirror images.Two comparators are configured to receive sawtooth signal and are converted into square-wave signal, and its reference level is respectively the minimum value and the maximum of sawtooth signal.Rest-set flip-flop is configured to receive the output signal of comparator and plays the effect of keeping with switching signal.
The present invention is used to supply convertor to provide the method for FREQUENCY CONTROL to comprise variable mode and intermittent mode.Described method comprises: the feedback input circuit receives feedback input signal, handles the information that is associated with feedback input signal, produces first control signal.First control signal is an analog signal.Frequency conversion and intermittent mode control circuit receive first control signal, handle the information that is associated with first control signal, produce first output signal relevant with frequency.
The present invention is used to provide the method for saw-toothed oscillator operating frequency to comprise: receive first output signal from variable mode and intermittent mode discharging current control unit, handle the information with this signal correction connection.Receive the sawtooth signal that first output signal and pierce circuit produce by logic control circuit, handle the information that is associated with the sawtooth signal of described first output signal and oscillator generation, produce second output signal by Digital Logical Circuits.Receive second output signal by pierce circuit, handle the information that is associated with second output signal, produce the 3rd output signal, i.e. sawtooth signal.
Working voltage signal of the present invention and current signal control generator, the operating frequency of oscillator is by feedback input signal V FBDecision.For instance, work as V FB＞V MaxThe time, load end is a full load condition, oscillator is operated in peak frequency; Work as V Min＜V FB＜V MaxThe time, load end is a light condition, oscillator is operated in variable mode; Work as V FB＜V MinThe time, load is a Light Condition, oscillator is operated in intermittent mode.Through variable mode and intermittent mode discharging current control unit output signal control generator signal, thus the switching frequency in definite switched mode power converter.
The present invention can obtain to surpass many advantages of identical operating frequency supply convertor.For example, the present invention can correspondingly increase the turn-off time of transducer when load reduction, reduce switching frequency with this, has reduced power consumption, has increased the efficient of Switching Power Supply; The present invention can turn-off transducer output under no-load condition, only rely on the transformer energy stored to keep load end work, and when energy decreases arrived certain value, restarting transducer was the transformer makeup energy, turn-offed transducer output afterwards once more.So both reduced stand-by power consumption, made system's variation of responsive load end in time again.The present invention has avoided the power loss that fixed frequency is brought in the switched mode power converter for switched-mode power supply provides the switching frequency variation.Owing to be the adjustment pulsewidth of Cycle by Cycle, the dynamic response capability of circuit can be further improved.
The present invention is used for frequency change control with digital circuit, and digital circuit is of portable form, and can be used for different ic manufacturing process by transplanting easily.The present invention utilizes comparator by relatively the coming for clock signal provides frequency change of feedback signal, uses logic digital circuits to adjust the operating frequency of switched mode power converter.Variable mode and intermittent mode discharging current control unit output square-wave signal, the square-wave signal of this signal and pierce circuit output carries out logical operation, and the result of computing is as the operating frequency of switched mode power converter.
With reference to following detailed description and accompanying drawing, can more fully understand various other purposes of the present invention, feature and advantage.
Description of drawings
Fig. 1 is the system that the present invention is used to provide operating frequency;
Fig. 2 shows the simplification diagrammatic sketch that operating frequency of the present invention changes;
Fig. 3 is the feedback control circuit of logic control of the present invention and oscillator.
Embodiment
The invention provides a kind of system that operating frequency is provided for switching power converters.The present invention is applied to field of switch power.
Fig. 1 is the system that the present invention is used to provide operating frequency.System 100 comprises feedback input circuit 110, frequency conversion and intermittent mode control circuit 120, logic control circuit 130 and oscillator 140.Though used one group of selected parts that system 100 is shown, many substitutes, modification and version can have been arranged.For example, some parts can be expanded and/or be merged.Insert miscellaneous part in the parts that can mention in the above.Depend on embodiment, the arrangement of parts can exchange, and other parts can be replaced.
Feedback input circuit 110 is to frequency conversion and intermittent mode control circuit 120 output analog signals 111.The feedback input circuit comprises optically coupled circuit, current source and resistance change-over circuit.The feedback current of optical coupler and circuit internal current source are done the coupling of proper proportion, via the resistance change-over circuit current conversion are become analog voltage signal 111.Frequency conversion and intermittent mode control circuit 120 produce control signal 121 based on analog signal 111.
Control signal 121 is received by logic control circuit 130.Logic control circuit 130 produces signal 131 based on control signal 121.Control signal 131 is used for adjusting the charging and the discharge of oscillator 140.The output signal 142 of oscillator 140 is a sawtooth signal, is modulated to square-wave signal 141 by logic control circuit 130.The frequency of the output signal 141 of oscillator 140 and pulsewidth are subjected to frequency conversion and 121 modulation of intermittent mode control circuit output signal.
Clock signal 141 and serrated signal 142 are received by PWM generator 150.Pwm signal 151 is used to turn on and off the mains switch in the switched mode power converter.Sawtooth signal 142 is used to the slope compensation in the switched mode power converter.Clock signal 141 is used to determine the switching frequency of switched mode power converter.
Fig. 2 shows oscillator output signal 141 variation of t in time.The frequency of square wave in time change and the part that changes is the frequency conversion mode of operation; The part that frequency remains unchanged is the steady-working state of switched mode power converter.The frequency of oscillation of signal is the switching frequency of the switched mode power converter of PWM generator 160 controls.
Fig. 3 shows the feedback loop of logic control circuit and oscillator.System 300 comprises logical circuit, oscillator charging control switch 360 (SW1), oscillator discharge control switch 370 (SW2), oscillator charging current source 380, oscillator discharge current source 390 and charge and discharge capacitances 391 (CT) such as resitstance voltage divider 350, comparator 320 and 330, rest-set flip-flop 340, not gate and NAND gate.
In the system 300,392 is the sawtooth waveforms output of oscillator, compares with the dividing potential drop of resitstance voltage divider, and the threshold voltage 301,302 of comparator divides reference voltage 310 (V by resistance 311 (R1), 312 (R2), 313 (R3) REF1) and get, by the basic functional principle of oscillating circuit 301,302 peak V that are sawtooth waveforms as can be known HWith minimum point V L, V PPBe exactly the peak-to-peak value of sawtooth waveforms, its big I is determined by following formula:
V H = R 2 + R 3 R 1 + R 2 + R 3 V REF 1 (equation 1)
V L = R 3 R 1 + R 2 + R 3 V REF 1 (equation 2)
V PP = V H - V L = R 2 R 1 + R 2 + R 3 V REF 1 (equation 3)
Change resistance R 1, R 2, R 3Between ratio can regulate sawtooth waveforms maximum, minimum value and peak-to-peak value.R in this example 1, R 2, R 3Be set at fixed value, reference voltage is certain, and then the sawtooth waveforms amplitude is certain.Its amplitude is not subjected to the influence of other factors.
Comparator 320 and 330 output is through logic circuit output signals 304 and 306 such as rest-set flip-flops 340, and signal 304 and 306 feeds back to oscillator and comes discharging and recharging of control generator as the charge and discharge switch 360 and 370 of oscillator.Oscillator charging current source 380 is the constant-current source of current mirror mirror image, and 390 are the discharge constant-current source.When charge switch 360 closures, when discharge switch 370 was opened, charging current source 380 was to electric capacity 391 chargings; When charge switch 360 is opened, when discharge switch 370 was closed, electric capacity 391 discharged to ground by discharging current source 390.The sawtooth signal that signal 392 produces for capacitor charge and discharge.Its signal 305 in this example, changes the output frequency and the pulsewidth of oscillator for the control signal of frequency conversion and intermittent mode by logical operation.
The present invention has many advantages.For example, the present invention can correspondingly increase the turn-off time of transducer when load reduction, reduce switching frequency with this, has reduced power consumption, has increased the efficient of Switching Power Supply; Can turn-off transducer output under no-load condition, only rely on the transformer energy stored to keep load end work, when energy decreases arrived certain value, restarting transducer was the transformer makeup energy, turn-offed transducer output afterwards once more.So both reduced stand-by power consumption, made system's variation of responsive load end in time again.For instance, the present invention has avoided the power loss that fixed frequency is brought in the switched mode power converter for switched-mode power supply provides the switching frequency variation.Owing to be the adjustment pulsewidth of Cycle by Cycle, the dynamic response capability of circuit can be further improved.
The present invention is used for frequency change control with digital circuit, and digital circuit is of portable form, and can be used for different ic manufacturing process by transplanting easily.The present invention utilizes comparator by relatively the coming for clock signal provides frequency change of feedback signal, uses logic digital circuits to adjust the operating frequency of switched mode power converter.Variable mode and intermittent mode discharging current control unit output square-wave signal, the square-wave signal of this signal and pierce circuit output carries out logical operation, and the result of computing is as the operating frequency of switched mode power converter.
The present invention uses the oscillator that voltage signal and current signal control are arranged, and the operating frequency of oscillator is feedback input signal V again FBDecision.For instance, work as V FB＞V MaxThe time, load end is a full load condition, oscillator is operated in peak frequency; Work as V Min＜V FB＜V MaxThe time, load end is a light condition, oscillator is operated in variable mode; Work as V FB＜V MinThe time, load is a Light Condition, oscillator is operated in intermittent mode.Through variable mode and intermittent mode discharging current control unit output signal control generator signal, thus the switching frequency in definite switched mode power converter.
There are other embodiment that are equal to described embodiment in this area.The present invention should not be understood that the embodiment that only limits to specifically illustrate.

Claims (4)

1. system that is used to switching power converters that operating frequency is provided, described system comprises:
Feedback input circuit, frequency conversion and intermittent mode control circuit, logic control circuit, oscillator and PWM generator; Wherein:
The feedback input circuit, load condition is fed back to IC interior and produces first control signal by Light Coupled Device, the output of feedback input circuit is associated with the load condition of switched mode power converter system, and the feedback input circuit comprises optically coupled circuit, current source and resistance change-over circuit;
Frequency conversion and intermittent mode control circuit, be configured to receive first control signal and result from the first relevant output signal of frequency, the output of frequency conversion and intermittent mode control circuit is associated with the output square wave frequency of oscillator, frequency conversion and intermittent mode control circuit comprise: comparator, rest-set flip-flop and logical circuit, wherein comparator is configured to receive first control signal, two reference levels of comparator are respectively intermittent mode predetermined value and variable mode predetermined value, and wherein the intermittent mode predetermined value is less than the variable mode predetermined value.Rest-set flip-flop is configured to receive the output signal of comparator and plays the effect of keeping with switching signal, and logical circuit output frequency variation signal i.e. first output signal, is used for the operating frequency of by-pass cock supply convertor;
Logic control circuit, the sawtooth signal that is configured to receive first output signal and oscillator forms second output signal;
Oscillator, be configured to receive the second output signal Control current capacitor charge and discharge is formed the 3rd output signal, it is sawtooth signal, oscillator and logic control circuit constitute feedback loop, the charge and discharge switch of the output signal control generator of logic control circuit, pierce circuit comprises: constant-current source, charge and discharge switch and charge and discharge capacitance wherein constant-current source provide charging current and discharging current for oscillator, charge and discharge switch is used for the charging and the discharge of control generator, when the charge switch closure, when discharge switch is opened, the electric capacity charging, when charge switch is opened, when discharge switch is closed, capacitor discharge, form sawtooth signal, its frequency is by the cycle decision of second output signal;
PWM generator is configured to receive the 4th output signal that second output signal and the 3rd output signal form the mains switch that is used for turning on and off switched mode power converter.
2. the system as claimed in claim 1, the operating state of described frequency conversion and intermittent mode control circuit, if the output of feedback input circuit less than the intermittent mode predetermined value, switched mode power converter is operated in intermittent mode.
3. the system as claimed in claim 1, the operating state of described frequency conversion and intermittent mode control circuit, if the output of feedback input circuit greater than the intermittent mode predetermined value, and less than the variable mode predetermined value, switched mode power converter is operated in variable mode.
4. the system as claimed in claim 1, the operating state of described frequency conversion and intermittent mode control circuit, if the output of feedback input circuit greater than the variable mode predetermined value, switched mode power converter is in normal operating conditions.
CN2010101410895A 2010-04-06 2010-04-06 System for providing working frequency for switching power supply converter Pending CN102214986A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102570563A (en) * 2012-03-13 2012-07-11 绍兴文理学院 Remote controller bracket with two-position voltage control and controllable constant current charging functions
CN103208934A (en) * 2012-01-11 2013-07-17 成都启臣微电子有限公司 Pulse width modulation switching power supply controller and switching power supply
CN113889991A (en) * 2020-07-03 2022-01-04 圣邦微电子（北京）股份有限公司 Short-circuit protection circuit and short-circuit protection method

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08266064A (en) * 1995-03-23 1996-10-11 Okuma Mach Works Ltd Controller for inverter
US5663878A (en) * 1996-03-21 1997-09-02 Unitrode Corporation Apparatus and method for generating a low frequency AC signal
US20070075790A1 (en) * 2005-10-03 2007-04-05 Linear Technology Corp. Switching regulator duty cycle control in a fixed frequency operation
CN101087105A (en) * 2006-06-09 2007-12-12 富士通株式会社 DC-DC converter and control for DC-DC converter
CN101335488A (en) * 2007-06-29 2008-12-31 天钰信息科技（上海）有限公司 System for modulating working frequency of switch power source converter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08266064A (en) * 1995-03-23 1996-10-11 Okuma Mach Works Ltd Controller for inverter
US5663878A (en) * 1996-03-21 1997-09-02 Unitrode Corporation Apparatus and method for generating a low frequency AC signal
US20070075790A1 (en) * 2005-10-03 2007-04-05 Linear Technology Corp. Switching regulator duty cycle control in a fixed frequency operation
CN101087105A (en) * 2006-06-09 2007-12-12 富士通株式会社 DC-DC converter and control for DC-DC converter
CN101335488A (en) * 2007-06-29 2008-12-31 天钰信息科技（上海）有限公司 System for modulating working frequency of switch power source converter

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103208934A (en) * 2012-01-11 2013-07-17 成都启臣微电子有限公司 Pulse width modulation switching power supply controller and switching power supply
CN103208934B (en) * 2012-01-11 2016-12-14 成都启臣微电子股份有限公司 A kind of pulse width modulating switch power source controller and Switching Power Supply
CN102570563A (en) * 2012-03-13 2012-07-11 绍兴文理学院 Remote controller bracket with two-position voltage control and controllable constant current charging functions
CN113889991A (en) * 2020-07-03 2022-01-04 圣邦微电子（北京）股份有限公司 Short-circuit protection circuit and short-circuit protection method

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Application publication date: 20111012