CN100454205C - Improved method of detecting switching power supply output current - Google Patents

Improved method of detecting switching power supply output current Download PDF

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Publication number
CN100454205C
CN100454205C CNB2004800057930A CN200480005793A CN100454205C CN 100454205 C CN100454205 C CN 100454205C CN B2004800057930 A CNB2004800057930 A CN B2004800057930A CN 200480005793 A CN200480005793 A CN 200480005793A CN 100454205 C CN100454205 C CN 100454205C
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inductor
dutycycle
current
discharge
signal
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CN1757005A (en
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拉里·科恩
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Jm Electronics Ltd
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JAM Technologies Inc
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Abstract

A method according to the invention includes the steps of inferring the peak current through the inductor (303) as a function of input voltage and inductor charge time, and deriving the current available to the load based upon the flyback voltage during discharge of the inductor (303). In terms of apparatus, in a switching power supply of the type wherein a switching device (302) is used to charge an inductor (303) that discharges to a load, the invention provides devices arranged for detecting output current without the need for a resistor or other component in series with the load. In the preferred embodiment, these devices include electrical components operative to generate a signal indicative of peak inductor current, and a switch (302) for switching the signal to provide a waveform, the integral of which is proportional to peak inductor current multiplied by the duty cycle of the discharge of the inductor (303).

Description

Improving one's methods of detector switch electric power outputting current
Quoting of related application
The application requires to submit on February 3rd, 2003 right of priority of U.S. Provisional Patent Application sequence number 60/444,568, and its content is incorporated herein by reference.
Technical field
The present invention is general relates to Switching Power Supply, is specifically related to detect the method for the output current in the power supply that uses less element.
Background technology
Use the Switching Power Supply of sensing element to be used a period of time.Although the output voltage (realizing by Voltage Feedback usually) that most application needs are constant, some application need constant output electric currents.
The method of the steady current output of standard comprises adds a resistor of connecting with load so that output current is converted to voltage, and this voltage then can be used as feedback.Yet this method is carried out resistors in series loss and feedback voltage magnitude, or dynamic range is compromise.So there is the demand of the output current method of not using series element detector switch power supply.
Summary of the invention
The present invention relates in Switching Power Supply to detect a kind of method and apparatus of output current, its without any need for resistor or other element connected in series in load.On wide significance, this technology obtains the inductor peak current of a switch converters by input voltage and inductor duration of charging, and calculates the current integration of the peak point current that can use load by the flyback voltage that uses the inductor interdischarge interval.
More concrete, the method according to this invention may further comprise the steps, derive by peak inductor current as the input voltage and the function in inductor duration of charging, and the electric current that obtains can be used for load based on the flyback voltage of inductor interdischarge interval.Although a disclosed example is based on a lifting voltage topology (buck/boost topology), also it is contemplated that other converter topologies.
In aspect equipment, the invention provides a kind of equipment that is used for determining the average output current in the load in the Switching Power Supply of following type, in the Switching Power Supply of described type, the reception of first switching device has first control signal of a charging dutycycle to charge to inductor, described inductor the discharge dutycycle during to load discharge, described inductor is couple to supply voltage and has and is proportional to the peak point current that supply voltage multiply by the charging dutycycle, and described equipment comprises:
The second switch device, have control end and output terminal, described output terminal is couple to supply voltage by at least one resistance element, described second switch device is configured to receive second control signal of the dutycycle with first control signal, to generate switch output signal at described output terminal, described switch output signal has described dutycycle and proportional with supply voltage at least in part;
First wave filter and first impact damper are configured to receive described switch output signal and it are carried out integration, to generate the signal of indication inductor peak current;
The 3rd switching device, be configured to receive the 3rd control signal with described discharge dutycycle, and the signal of the described indication inductor peak current of switch, with the switching waveform that provides to have based on the dutycycle of described discharge dutycycle, the integration of described switching waveform is proportional to described inductor peak current and multiply by described discharge dutycycle; With
Second wave filter and second impact damper are configured to receive described switching waveform and generation is proportional to the feedback signal that described inductor peak current multiply by described discharge dutycycle.
The present invention also provides a kind of output current that is used for the detector switch power supply, need not the equipment that resistor or other elements are connected with load, and described equipment comprises:
First switching device, be configured to receive first control signal and charge to inductor with a charging dutycycle, to load discharge, described inductor is couple to supply voltage and has and is proportional to the peak point current that supply voltage multiply by the charging dutycycle described inductor during the discharge dutycycle
The second switch device, have control end and output terminal, described output terminal is couple to supply voltage by at least one resistance element, described second switch device is configured to receive second control signal of the dutycycle with first control signal, to generate switch output signal at described output terminal, described switch output signal has described dutycycle and proportional with supply voltage at least in part;
First wave filter and first impact damper are configured to receive described switch output signal and it are carried out integration, to generate the signal of indication inductor peak current;
The 3rd switching device, be configured to receive the 3rd control signal with described discharge dutycycle, and the signal of the described indication inductor peak current of switch, with the switching waveform that provides to have based on the dutycycle of described discharge dutycycle, the integration of described switching waveform is proportional to described inductor peak current and multiply by described discharge dutycycle; With
Second wave filter and second impact damper are configured to receive described switching waveform and generation is proportional to the feedback signal that described inductor peak current multiply by described discharge dutycycle.
Description of drawings
Fig. 1 is a typical fixed frequency lifting voltage changer well known in the art;
The operating voltage of Fig. 2 displayed map 1 circuit and the waveform of electric current;
Fig. 3 is the synoptic diagram of the preferred embodiments of the present invention.
Embodiment
Forward accompanying drawing now to, Fig. 1 is a typical fixed frequency lifting voltage changer synoptic diagram well known in the art.Pulse-width modulator 101 controls the dutycycle that voltage is entered as direct ratio with switching device for one of switching device 103 output.What switching device 103 replaced gives inductor 103 chargings, and allows it to pass through diode 104 to load 106 discharges.Capacitor 105 is used for filtering the resultant voltage that offers load 106.Resistor 107 is converted to feedback voltage with the resultant current in the load 106.Feedback voltage is provided for one by resistor 110, the integrator that capacitor 112 and operational amplifier 111 are formed, and it is compared with the fixed voltage reference that comprises resistor 108 and voltage stabilizing diode 109 therein.This integrator then provides control voltage to pulse-width modulator 101, closed hoop.
With reference now to Fig. 2,, track 201 has shown the conversion output of the pulse-width modulator 101 of driving switch device 102, and track 202 has shown that track 203 has shown the resultant current in inductor 103 at the combination inductance device voltage at diode 104 anode places.At time tag 204 places, switching device 102 is activated, and causes the synthesizing linear of the electric current of inductor 103 to increase, shown in track 203.At time tag 205 places, switching device 102 is not worked, cause in track 202, occurring the flyback voltage of inductor 103, and track 203 demonstrates the linearity minimizing of inductor 103 electric currents.At time tag 206 places, the energy of inductor 103 is depleted, causes zero current and no-voltage in the inductor 103 differential, respectively shown in track 202 and 203.At time tag 207 places, this whole circulation repeats.
Note that (assertion) time of asserting of the peak point current of inductor 103 and supply voltage and switching device 102 is all linear.Note also that this peak point current linearity is decreased to and exhausts when inductor 103 discharges.Therefore, discharge to give load 106 average current be that half of peak point current of inductor 103 multiply by the ratio of discharge time to the global cycle cycle.Explain that with mathematic(al) representation average output current can be by following expression: ((V* (T205-T204))/2) * ((T206-T205)/T207-T205)), wherein V represents supply voltage, and Tnnn is illustrated in the absolute time of representing in Fig. 2 sign.Note, exhaust by the voltage of the inductor 103 of track 202 at the electric current of time tag 206 place's inductors 103 and clearly show.Therefore, the discharge time of inductor 103 can be monitored.
With reference now to Fig. 3,, notes that this circuit compared to Figure 1 difference is that the omission of resistor 107 and increase are used for driving by Fig. 1 resistor 110, the circuit of the integrator that capacitor 112 and operational amplifier 111 are formed.The element 301-306 of Fig. 3, thus with 308-312 and Fig. 1 in their homologue play a part similarly, but lack current sensing resistor 107 and feedback voltage source (derivation) herein.
As long as switch 302 is to inductor 303 charging, switching device 314 is asserted in phase inverter 307 cancellations, otherwise just asserts switching device 314.With resistor 313 associatings, switching device 314 output switching waveforms, its integration is that supply voltage multiply by the inductor dutycycle in 303 duration of charging.This switching waveform that is directly proportional with peak inductor charge current is filtered by resistor 315 and capacitor 316, and is cushioned by voltage follower 317.
Like this, the filtered voltage of the current peak of voltage follower 317 output indication inductors 303.This filtered voltage is changed by switching device 319 under comparer 323 controls by resistor 318.Connect as shown, whenever the output (at the node of diode 304) of inductor 303 surpasses input supply voltage, comparer 323 generates a low conversion output (low-switchedoutput), otherwise generates high conversion (high-switched output) output.Under the control of this mode, switching device 319 and converted-wave of resistor 318 outputs, the peak point current that its integration is proportional to inductor 303 multiply by the dutycycle of inductor 303 discharges.
Filtration and buffering through resistor 320, capacitor 321 and voltage follower 322, directly indicate the voltage of output load current, be provided for by resistor 310, the integrator that capacitor 312 and operational amplifier 311 are formed is used for the fixed reference potential that is provided by resistor 308 and voltage stabilizing diode 309 relatively.By above method, do not use any resistance of connecting with load, the power supply closed loop on output current is affected.
Be revealed although use, those skilled in the art know that to it is contemplated that other converter topologies a lifting voltage topology.

Claims (5)

1. method that is used for detecting output current in the Switching Power Supply of following type, in the Switching Power Supply of described type, switching device is used to the inductor charging to load discharge, described method does not need the resistor of connecting with described load or other element, and described method comprises following steps:
Derivation is as the described peak inductor current of passing through of the input voltage and the function in inductor duration of charging; And
Obtain can be used for the electric current of load based on the flyback voltage of described inductor interdischarge interval.
2. the method for claim 1, wherein said inductor constitutes the part of lifting voltage topology.
3. equipment that is used for determining the average output current in the load in the Switching Power Supply of following type, in the Switching Power Supply of described type, the reception of first switching device has first control signal of a charging dutycycle to charge to inductor, described inductor the discharge dutycycle during to load discharge, described inductor is couple to supply voltage and has and is proportional to the peak point current that supply voltage multiply by the charging dutycycle, and described equipment comprises:
The second switch device, have control end and output terminal, described output terminal is couple to supply voltage by at least one resistance element, described second switch device is configured to receive second control signal of the dutycycle with first control signal, to generate switch output signal at described output terminal, described switch output signal has described dutycycle and proportional with supply voltage at least in part;
First wave filter and first impact damper are configured to receive described switch output signal and it are carried out integration, to generate the signal of indication inductor peak current;
The 3rd switching device, be configured to receive the 3rd control signal with described discharge dutycycle, and the signal of the described indication inductor peak current of switch, with the switching waveform that provides to have based on the dutycycle of described discharge dutycycle, the integration of described switching waveform is proportional to described inductor peak current and multiply by described discharge dutycycle; With
Second wave filter and second impact damper are configured to receive described switching waveform and generation is proportional to the feedback signal that described inductor peak current multiply by described discharge dutycycle.
An output current that is used for the detector switch power supply, need not the resistor of connecting or the equipment of other elements with load, described equipment comprises:
First switching device, be configured to receive first control signal and charge to inductor with a charging dutycycle, to load discharge, described inductor is couple to supply voltage and has and is proportional to the peak point current that supply voltage multiply by the charging dutycycle described inductor during the discharge dutycycle
The second switch device, have control end and output terminal, described output terminal is couple to supply voltage by at least one resistance element, described second switch device is configured to receive second control signal of the dutycycle with first control signal, to generate switch output signal at described output terminal, described switch output signal has described dutycycle and proportional with supply voltage at least in part;
First wave filter and first impact damper are configured to receive described switch output signal and it are carried out integration, to generate the signal of indication inductor peak current;
The 3rd switching device, be configured to receive the 3rd control signal with described discharge dutycycle, and the signal of the described indication inductor peak current of switch, with the switching waveform that provides to have based on the dutycycle of described discharge dutycycle, the integration of described switching waveform is proportional to described inductor peak current and multiply by described discharge dutycycle; With
Second wave filter and second impact damper are configured to receive described switching waveform and generation is proportional to the feedback signal that described inductor peak current multiply by described discharge dutycycle.
5. equipment as claimed in claim 4, wherein said first switching device and described inductor constitute the part of a lifting voltage topology.
CNB2004800057930A 2003-02-03 2004-02-03 Improved method of detecting switching power supply output current Expired - Fee Related CN100454205C (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US44456803P 2003-02-03 2003-02-03
US60/444,568 2003-02-03
US10/769,952 2004-02-02

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CN1757005A CN1757005A (en) 2006-04-05
CN100454205C true CN100454205C (en) 2009-01-21

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8305063B2 (en) * 2009-08-28 2012-11-06 Power Integrations, Inc. Power supply controller with an input voltage compensation circuit
US8294388B2 (en) * 2010-05-25 2012-10-23 Texas Instruments Incorporated Driving system with inductor pre-charging for LED systems with PWM dimming control or other loads
CN104734477A (en) * 2013-12-19 2015-06-24 李永红 Output current limiting circuit and method
CN107450649B (en) * 2016-05-31 2018-11-16 展讯通信(上海)有限公司 The peak point current suppressing method and circuit of power gating circuit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5696439A (en) * 1994-07-01 1997-12-09 Consorzio Per La Ricerca Sulla Microelettronica Nel Mezzogiorno Fuzzy control process for switching power supplies, and device for performing it
US6194882B1 (en) * 1997-07-30 2001-02-27 Georg Dieter Mirow Voltage supply for a sensor
CN1365181A (en) * 2000-12-04 2002-08-21 三垦电气株式会社 DC-DC converter

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5696439A (en) * 1994-07-01 1997-12-09 Consorzio Per La Ricerca Sulla Microelettronica Nel Mezzogiorno Fuzzy control process for switching power supplies, and device for performing it
US6194882B1 (en) * 1997-07-30 2001-02-27 Georg Dieter Mirow Voltage supply for a sensor
CN1365181A (en) * 2000-12-04 2002-08-21 三垦电气株式会社 DC-DC converter

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