CN112886807B - Device and method for realizing soft start - Google Patents
Device and method for realizing soft start Download PDFInfo
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- CN112886807B CN112886807B CN202110177371.7A CN202110177371A CN112886807B CN 112886807 B CN112886807 B CN 112886807B CN 202110177371 A CN202110177371 A CN 202110177371A CN 112886807 B CN112886807 B CN 112886807B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention discloses a soft start realizing device and a soft start realizing method, wherein a soft start circuit, a driving signal generating circuit, a switching power supply main power circuit and an output voltage sampling feedback circuit are connected with each other by circuits; the soft start circuit includes: comprising a resistor R 1 Resistance R 2 Resistance R 0 Voltage stabilizing tube D 1 Capacitor C and NPN triode Q 1 The resistance R 1 Connected in series with a capacitor C, one end of which is connected with a DC voltage signal V + Connected at the other end to a resistor R 1 One end is connected with R 1 The other end is connected with the signal ground SGND, the resistor R 2 And a voltage stabilizing tube D 1 In series, R 2 One end of the DC voltage signal V + Connected at the other end to D 1 Cathode is connected with D 1 The anode is connected to a signal ground SGND.
Description
Technical Field
The invention relates to the technical field of switching power supplies, in particular to a soft start implementation mode and electronic equipment with the soft start implementation mode.
Background
The switching power supply circuit generally comprises a rectifying circuit and a main power conversion circuit, and the input and output of the main power converter are generally provided with a capacitance filter circuit, so the main power conversion circuit is often self-capacitive. When the capacitive load is powered up, a large surge current is easily generated in the starting stage, and circuit components can be damaged, or input voltage is reduced and output voltage overshoots are caused. In order to protect circuit components and avoid the reduction of input voltage and the overshoot of output voltage, a soft start circuit is generally added when designing a switching power supply. The principle of the soft start circuit is that the start-up phase provides pulses with gradually increasing pulse width to the switching tube, so that the output voltage of the main power conversion circuit gradually rises from zero to a stable value.
Several soft start techniques commonly used at present include a series power thermistor between a pre-stage rectifying circuit and a main power circuit input capacitor; an SCR-R circuit is adopted; a circuit formed by connecting a relay and a resistor in parallel is added between the front-stage rectifying circuit and the input capacitor of the main power circuit; a timer triggered relay and a current limiting resistor circuit are adopted. The serial thermistor and the SCR-R circuit are not suitable for the condition that the power is required to be quickly turned on after the power is cut off, and have limitations. The circuit formed by connecting the relay and the resistor in parallel and the circuit formed by connecting the relay triggered by the timer and the current-limiting resistor are complex in structure, and the working reliability of the relay is not high.
Disclosure of Invention
The invention aims to provide a soft start implementation device and a soft start implementation method, which have the advantages of simple structure, high reliability and strong applicability.
In order to achieve the above object, the present invention is realized by the following technical scheme:
an implementation apparatus for soft start, comprising: the circuit is connected with the soft start circuit, the driving signal generating circuit, the switching power supply main power circuit and the output voltage sampling feedback circuit;
the soft start circuit comprises: comprising a resistor R 1 Resistance R 2 Resistance R 0 Voltage stabilizing tube D 1 Capacitor C and NPN triode Q 1 The resistance R 1 Connected in series with a capacitor C, one end of which is connected with a DC voltage signal V + Connected at the other end to a resistor R 1 One end is connected with R 1 The other end is connected with the signal ground SGND, the resistor R 2 And a voltage stabilizing tube D 1 In series, R 2 One end of the DC voltage signal V + Connected at the other end to D 1 Cathode is connected with D 1 The anode is connected with a signal ground SGND;
the driving signal generating circuit comprises an error compensation network, the positive end of which is connected with a resistor R 2 One end and a voltage stabilizing tube D 1 The resistance R is a cathode of 2 And a voltage stabilizing tube D 1 The voltage at the junction is used as the positive input of the error compensation networkV ref ；
The NPN triode Q 1 Base pass resistance R 0 And R is R 1 And the collector is connected with the output end of the error compensation network, and the emitter is connected with the signal ground SGND.
The driving signal generating circuit further comprises a PWM comparator and a driver; the negative end of the error compensation network is connected with the output end of the output voltage sampling feedback circuit, and the output end of the error compensation network is connected with the NPN triode Q 1 The collector is connected and used as the negative end input of the PWM comparator; the positive end input of the PWM comparator is a carrier signal, the output of the PWM comparator is connected with the input end of the driver, and the output end of the driver is connected with the main power circuit of the switching power supply.
The switching power supply main power circuit comprises a switching tube Q 2 The switch tube Q 2 A gate connected to the output end of the driver, a switch tube Q 2 The gate drive signal of (2) is derived from a driver of the drive signal generation circuit.
The output voltage sampling feedback circuit comprises a resistor R 4 And resistance R 5 The output voltage of the main power circuit of the switching power supply is V o Through a voltage dividing resistor R 4 And resistance R 5 Dividing the voltage to obtain a sampling feedback voltage V FB The sampling feedback voltage V FB As the negative terminal input of the error compensation network.
The implementation method of the implementation device for soft start comprises the following steps:
in the initial state of power-on, the voltage at two ends of the capacitor C is zero, and the resistor R 0 One end of the voltage is V + Ensure Q 1 Voltage between base and emitter is greater than turn-on threshold, Q 1 On, the output end of the error compensation network is grounded, and the switch tube Q 2 Cut-off, at the same time, the DC voltage signal V + Charging the capacitor C;
during this period, the voltage across the capacitor C gradually rises from 0 to V + Resistance R 0 Is one end voltage of V + Gradually drop to 0, Q 1 Base current i b Gradually decrease with i b Gradually decrease, Q 1 The output voltage of the output end of the error compensation network is gradually increased from the saturation region to the amplifying region, and the switch tube Q 2 And realizing soft start, and after the soft start is finished, entering a cut-off region by Q1.
Compared with the prior art, the invention has the following advantages:
the soft start circuit has the advantages of realizing a soft start function by adopting a simple structure, along with strong applicability, no limitation such as incapability of immediately powering up after power failure, high reliability and difficulty in generating interference to a later-stage circuit.
Drawings
FIG. 1 is a circuit diagram of a soft start implementation device according to the present invention;
fig. 2 is a schematic waveform diagram of the present invention.
Detailed Description
The invention will be further described by the following detailed description of a preferred embodiment, taken in conjunction with the accompanying drawings.
As shown in fig. 1, a device for implementing soft start is characterized by comprising: the circuit is connected with the soft start circuit, the driving signal generating circuit, the switching power supply main power circuit and the output voltage sampling feedback circuit; the soft start circuit comprises: comprising a resistor R 1 Resistance R 2 Resistance R 0 Voltage stabilizing tube D 1 Capacitor C and NPN triode Q 1 The resistance R 1 Connected in series with a capacitor C, one end of which is connected with a DC voltage signal V + Connected at the other end to a resistor R 1 One end is connected with R 1 The other end is connected with the signal ground SGND, the resistor R 2 And a voltage stabilizing tube D 1 In series, R 2 One end of the DC voltage signal V + Connected at the other end to D 1 Cathode is connected with D 1 The anode is connected with a signal ground SGND; the driving signal generating circuit comprises an error compensation network, the positive end of which is connected with a resistor R 2 One end and a voltage stabilizing tube D 1 The resistance R is a cathode of 2 And a voltage stabilizing tube D 1 The voltage at the junction is used as the positive input V of the error compensation network ref The method comprises the steps of carrying out a first treatment on the surface of the The NPN triode Q 1 Base pass throughResistor R 0 And R is R 1 And the collector is connected with the output end of the error compensation network, and the emitter is connected with the signal ground SGND.
The driving signal generating circuit further comprises a PWM comparator and a driver; the negative end of the error compensation network is connected with the output end of the output voltage sampling feedback circuit, and the output end of the error compensation network is connected with the NPN triode Q 1 The collector is connected and used as the negative end input of the PWM comparator; the positive end input of the PWM comparator is a carrier signal, the output of the PWM comparator is connected with the input end of a driver, and the output end of the driver is connected with a switching tube Q in a switching power supply main power circuit 2 Is connected to the gate of (c).
The switching power supply main power circuit comprises a switching tube Q 2 The switch tube Q 2 A gate connected to the output end of the driver, a switch tube Q 2 The gate drive signal of (2) is derived from a driver of the drive signal generation circuit.
The output voltage sampling feedback circuit comprises a resistor R 4 And resistance R 5 The output voltage of the main power circuit of the switching power supply is V o Through a voltage dividing resistor R 4 And resistance R 5 Dividing the voltage to obtain a sampling feedback voltage V FB The sampling feedback voltage V FB As the negative terminal input of the error compensation network.
Specifically, the resistance R 1 The capacitor c=3.3μf is connected in series with 110kΩ, the upper end of the capacitor is connected to the dc voltage signal +5v, the lower end is connected to a 110kΩ resistor, and the lower end of the 110kΩ resistor is connected to the signal ground SGND. Resistor R 2 And a voltage stabilizing tube D 1 In series, R 2 The upper end is connected with the direct current voltage signal +5V, and the lower end is connected with D 1 Cathode is connected with D 1 The anode is connected to a signal ground SGND. Resistor R 2 And a voltage stabilizing tube D 1 The voltage at the junction is used as the positive end input V of the error compensation network in the driving signal generating circuit ref . NPN type triode Q 1 Base pass resistance R 0 The connection point of the =2kΩ with the 110kΩ resistor and the 3.3 μf capacitor, the collector with the output of the error compensation network and the emitter with the signal ground SGND. The above is a soft start circuitEmbodiments of (a).
The soft start implementation device according to the embodiment of the present invention is described above with reference to fig. 1. Further, the invention also provides a method for realizing the soft start device, which comprises the steps that in the initial state of power-on, the voltage at the two ends of the capacitor C is zero, and the resistor R 0 Is V at the left end voltage of + Ensure Q 1 Voltage between base and emitter is greater than turn-on threshold, Q 1 On, the output end of the error compensation network is grounded, the COMP signal is pulled to zero, and the main circuit switch tube Q 2 Cut-off, at the same time, the DC voltage signal V + Charging the capacitor C. During this period, the voltage across the capacitor C gradually rises from 0 to V + Resistance R 0 Is set by V + Gradually drop to 0, Q 1 Base current i b Gradually decreasing. With i b Gradually decrease, Q 1 From saturation region to amplification region, the output voltage of COMP foot is gradually raised, and the main circuit switch tube Q 2 Soft start is realized. After the soft start is completed, Q1 enters the cut-off region without affecting the closed loop control circuit, i.e. the change of signal COMP. The soft start implementation mode has the advantages of strong applicability, simple structure, high reliability, difficult interference to a later-stage circuit, capability of inhibiting surge current and protection of circuit elements.
Specifically, referring to fig. 2, in a power-on initial state t 0 At the moment, the voltage at two ends of the 3.3 mu F capacitor is zero, the voltage of the node A is +5V, and Q is caused by a 2k omega resistor 1 Voltage between base and emitter is greater than turn-on threshold, Q 1 On, the output end of the error compensation network is grounded, the voltage of node B, namely the signal COMP, is pulled to zero, and the main circuit switch tube Q 2 Cut off, direct current voltage signal +5V charges capacitor C at the same time. t is t 0 ～t 2 At moment, the voltage at two ends of the capacitor gradually rises, and the voltage at the node A gradually drops to enable Q 1 The base current gradually decreases; t is t 2 The voltage at both ends of the capacitor rises to +5V at the moment, the voltage of the node A drops to 0V, and Q is caused 1 The base current is eventually 0.t is t 1 Moment when Q 1 Beginning to exit from the saturation region and enter the amplification region, the signal COMP voltage gradually rises, and the main circuit switch tube Q 2 Drive signal duty cycleThe ratio is gradually increased until t 3 The time remains stable.
While the present invention has been described in detail through the foregoing description of the preferred embodiment, it should be understood that the foregoing description is not to be considered as limiting the invention. Many modifications and substitutions of the present invention will become apparent to those of ordinary skill in the art upon reading the foregoing. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims (5)
1. A soft start implementation apparatus, comprising: the circuit is connected with the soft start circuit, the driving signal generating circuit, the switching power supply main power circuit and the output voltage sampling feedback circuit;
the soft start circuit comprises: resistor R 1 Resistance R 2 Resistance R 0 Voltage stabilizing tube D 1 Capacitor C and NPN triode Q 1 The resistance R 1 Connected in series with a capacitor C, one end of which is connected with a DC voltage signal V + Connected at the other end to a resistor R 1 One end is connected with R 1 The other end is connected with the signal ground SGND, the resistor R 2 And a voltage stabilizing tube D 1 In series, R 2 One end of the DC voltage signal V + Connected at the other end to D 1 Cathode is connected with D 1 The anode is connected with a signal ground SGND;
the driving signal generating circuit comprises an error compensation network, the positive end of which is connected with a resistor R 2 And the other end of the voltage stabilizing tube D 1 The resistance R is a cathode of 2 And a voltage stabilizing tube D 1 The voltage at the junction is used as the positive input V of the error compensation network ref ；
The NPN triode Q 1 Base pass resistance R 0 And R is R 1 And the collector is connected with the output end of the error compensation network, and the emitter is connected with the signal ground SGND.
2. The soft start implementation of claim 1, wherein the drive signal generation circuit further comprises a PWM comparator and a driver;
the negative end of the error compensation network is connected with the output end of the output voltage sampling feedback circuit, and the output end of the error compensation network is connected with the NPN triode Q 1 The collector is connected and used as the negative end input of the PWM comparator;
the positive end input of the PWM comparator is a carrier signal, the output of the PWM comparator is connected with the input end of the driver, and the output end of the driver is connected with the main power circuit of the switching power supply.
3. The soft start implementation device as set forth in claim 2, wherein the switching power supply main power circuit includes a switching tube Q 2 The switch tube Q 2 A gate connected to the output end of the driver, a switch tube Q 2 The grid driving signal of the switch power supply is sourced from a driver of the driving signal generating circuit, and the output end of the switch power supply main power circuit is connected with the output voltage sampling feedback circuit.
4. A soft start implementation as defined in claim 3, wherein the output voltage sampling feedback circuit includes a resistor R 4 And resistance R 5 The output voltage of the main power circuit of the switching power supply is V o Through a voltage dividing resistor R 4 And resistance R 5 Dividing the voltage to obtain a sampling feedback voltage V FB The sampling feedback voltage V FB As the negative terminal input of the error compensation network.
5. A method of implementing a soft start implementation as claimed in claim 1, the method comprising:
in the initial state of power-on, the voltage at two ends of the capacitor C is zero, and the resistor R 0 One end of the voltage is V + Ensure Q 1 Voltage between base and emitter is greater than turn-on threshold, Q 1 On, the output end of the error compensation network is grounded, and the switch tube Q 2 Cut-off, at the same time, the DC voltage signal V + Charging the capacitor C;
during this period, the voltage across the capacitor C is gradually changed from 0Gradually rise to V + Resistance R 0 Is one end voltage of V + Gradually drop to 0, Q 1 Base current i b Gradually decrease with i b Gradually decrease, Q 1 The output voltage of the output end of the error compensation network is gradually increased from the saturation region to the amplifying region, and the switch tube Q 2 Realize soft start, after soft start is completed, Q 1 Into the cut-off zone.
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| CN202110177371.7A CN112886807B (en) | 2021-02-07 | 2021-02-07 | Device and method for realizing soft start |
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| CN202110177371.7A CN112886807B (en) | 2021-02-07 | 2021-02-07 | Device and method for realizing soft start |
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| CN112886807B true CN112886807B (en) | 2023-06-20 |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103475223A (en) * | 2012-06-08 | 2013-12-25 | 中国科学院深圳先进技术研究院 | Step-down converter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100525040C (en) * | 2007-10-26 | 2009-08-05 | 东南大学 | Sample-taking feedback circuit of switch electric power output electric voltage |
| US8427130B2 (en) * | 2010-12-16 | 2013-04-23 | Integrated Device Technology, Inc. | Methods and apparatuses for combined frequency compensation and soft start processes |
| CN102682714B (en) * | 2012-04-27 | 2015-04-15 | 深圳麦格米特电气股份有限公司 | LED backlight source driving circuit and method for realizing soft startup |
| CN204156724U (en) * | 2014-10-17 | 2015-02-11 | 南车株洲电力机车研究所有限公司 | A kind of rotating forward positive voltage feedback circuit |
| CN104852563A (en) * | 2015-05-20 | 2015-08-19 | 重庆大学 | Switching power supply external soft start circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103475223A (en) * | 2012-06-08 | 2013-12-25 | 中国科学院深圳先进技术研究院 | Step-down converter |
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