CN110011552B - Switching power supply control method and circuit - Google Patents
Switching power supply control method and circuit Download PDFInfo
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- CN110011552B CN110011552B CN201810013152.3A CN201810013152A CN110011552B CN 110011552 B CN110011552 B CN 110011552B CN 201810013152 A CN201810013152 A CN 201810013152A CN 110011552 B CN110011552 B CN 110011552B
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- 239000003990 capacitor Substances 0.000 claims abstract description 56
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- 238000004804 winding Methods 0.000 claims description 49
- 238000001514 detection method Methods 0.000 claims description 6
- 230000003071 parasitic effect Effects 0.000 claims description 3
- 238000004806 packaging method and process Methods 0.000 abstract description 2
- 230000008569 process Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 7
- 230000001105 regulatory effect Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
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- 102100026134 Tissue factor pathway inhibitor 2 Human genes 0.000 description 3
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Classifications
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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
- H02M3/00—Conversion of DC power input into DC power output
- H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
- H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
- H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
- H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33561—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having more than one ouput with independent control
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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
- H02M3/00—Conversion of DC power input into DC power output
- H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
- H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
- H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
- H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
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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
- H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
- H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
- H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
- H02M7/12—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M7/219—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
-
- 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
- H02M1/0048—Circuits or arrangements for reducing losses
- H02M1/0054—Transistor switching losses
- H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
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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
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a switching power supply control method and a circuit. The switching power supply comprises an input capacitor, a transformer, a first power switch and a first controller; an output capacitor, a second power switch, a second controller; the second controller controls the second power switch to carry out synchronous rectification in the process of transferring the energy of the input capacitor to the output capacitor; the second controller detects load voltage and current and generates a first control signal to control the working state of the first power switch so that the load voltage and the load current accord with expected values; the second controller controls the second power switch to generate an on/off action to transfer part of energy of the output capacitor to the input capacitor; when the first controller detects that energy is transferred from the output capacitor to the input capacitor, the first controller controls the first power switch to change the working state; the switching power supply based on the invention does not need an optocoupler or a special packaging frame to transmit the first control signal, and has low cost and high efficiency.
Description
Technical Field
The present invention relates to a switching power supply technology, and in particular, to a switching power supply control method and a corresponding control circuit.
Background
The switching power supply has the advantages of small size, high conversion efficiency and the like, and the application field of the switching power supply is continuously expanded, and the switching power supply comprises a charger, an adapter and the like. In recent years, the main countries in the world have raised requirements on the conversion efficiency of the switching power supply, and in order to meet the latest grade requirements (second stage) of energy efficiency of the European Union and the grade VI energy efficiency requirements of the U.S. department, the switching power supply generally adopts a synchronous rectification technology to raise the efficiency. In order to meet the requirement of quick charging of the mobile phone, the precision requirement on the output voltage of the charger is higher and higher, and meanwhile, the output voltage of the charger is required to be adjusted according to the load requirement. The charger meeting the USB PD 3.0 specification has an output voltage variation range of 3V-21V and a minimum voltage interval of 20mV.
Fig. 1A is a schematic diagram of a conventional primary side (or primary side) regulated switching power supply charger system 100A. The switching power supply charger includes an ac input port (the ac voltage range is typically 85V AC To 265V AC ) Rectifier bridge 101 (AC voltage V) AC Converted into DC voltage V IN ) An input capacitor 102, a transformer 120, a first controller 104, a first power switch 105, a secondary side (or secondary side) synchronous rectification power switch 122, an output capacitor 121, and the likeStep-rectification controller 124, output capacitor 121, output port (V 0 ) Etc. The output voltage of the switching power supply shown in fig. 1A is controlled by the controller 104 located on the primary side, and the secondary side controller 124 is only used for synchronous rectification control, so that an optocoupler is not needed, and the cost is low. However, the output voltage accuracy is limited by the error in the primary side sampled output voltage, and generally can only meet a mass production accuracy of +/-5%.
The switching power supply shown in fig. 1B is a charger without an optocoupler. The primary side controller and the secondary side synchronous rectification controller of the switching power supply 100B are placed in the same package, and the secondary side controller transmits a control signal to the primary side controller through parasitic inductance of the package frame to control the operation state of the primary side power switch. The output voltage of the switching power supply 100B is received for the secondary side controller via the voltage dividing resistors 125 and 126, and the output voltage is regulated by the secondary side controller, so that higher voltage accuracy can be ensured to reach a mass production level of +/-2.5%. Although an optocoupler is not required in the switching power supply 100B, the system cost is high because a special package is required for the switching power supply 104.
In view of the foregoing, in order to meet the requirements of higher output voltage precision and lower system cost of the switching power supply, there is an urgent need to develop a switching power supply control method and circuit that does not have an optocoupler and controls output voltage and current from the secondary side. This is the object of the present invention.
The invention aims to overcome the defects of the prior art, and provides a novel secondary side regulating switch power supply voltage/current control method and circuit, which reduce the loss of a primary side power switch in the prior art and adapt to the requirement of quick charging.
According to an embodiment of the present invention, there is provided a switching power supply including: an input port coupled to an ac voltage or a dc voltage; an input capacitor coupled to the input port (when the input voltage is an alternating current, the input capacitor is coupled to the alternating current voltage through a rectifier bridge); a transformer having a primary (first) winding and a secondary (second) winding, the primary winding coupled to an input capacitance; a primary (first) power switch coupled to the primary winding of the transformer, having two operating states, on and off; a first (primary side) controller coupled to the primary power switch and the transformer, controlling an operating state of the primary power switch; an output port coupled to a switching power supply load, providing voltage and current to the load; an output capacitor coupled to the output port and the transformer secondary winding; a second (secondary side) power switch coupled to the transformer secondary winding, having two operating states, on and off; a second (secondary side) controller coupled to the second power switch, the output port and the transformer secondary winding. The second controller controls the second power switch to carry out synchronous rectification when energy is transferred from the input capacitor to the output capacitor; the second controller also detects load voltage and current, and generates a first control signal according to the error of the load voltage or current signal; the second controller transmits the first control signal to the first controller by transmitting the output capacitance energy to the input capacitance; the first controller changes the working state of the first power switch according to the obtained first control signal to enable the load voltage or current to accord with a preset value;
drawings
FIGS. 1A and 1B are schematic diagrams of a conventional switching power supply;
FIG. 2 is a schematic diagram of a switching power supply according to the present invention;
FIG. 3 is a schematic diagram of an AC-DC converter according to the present invention;
FIG. 4 is a schematic diagram of key node waveforms of the switching power supply controller shown in FIGS. 2-3 according to the present invention;
Detailed Description
The following describes in detail the implementation of the present invention. Examples of embodiments are given in the accompanying drawings. It should be noted that the examples described herein are for illustration only and are not intended to limit the invention. Details of implementation are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. In the description of the embodiments, in order to avoid obscuring the present invention, circuits well known in the art, such as a synchronous rectification module, a constant voltage, a constant current module, and a driving module, which are typical in secondary side controllers, are not specifically described.
Reference throughout this specification to "one embodiment," "an embodiment," or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments. Accordingly, it will be appreciated by those of ordinary skill in the art that the drawings provided herein are for illustrative purposes and that the drawings are not necessarily drawn to scale. It will be understood that when an element is referred to as being "coupled to" another element, it can be directly coupled to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly coupled to" another element, there are no intervening elements present. The same or similar reference numerals denote the same or similar elements or elements having the same or similar operations.
Fig. 2 is a schematic diagram of a secondary side regulated switching power supply 200 in accordance with the present invention. The difference from the conventional switching power supplies 100A, 100B shown in fig. 1A, 1B is that the output voltage/current and synchronous rectification of the switching power supply 200 are realized by the secondary side controller 224, and no optocoupler or special packaging form is required.
In the secondary side regulating switching power supply 200 of the present invention shown in fig. 2, the input voltage Vin is a dc voltage, and the switching power supply 200 is a dc-dc converter; the input voltage Vin may also be rectified from an ac power source, as shown in fig. 3, and the switching power supply 300 is an ac-dc converter.
Embodiments and advantages of the present invention are described in detail below with reference to fig. 2 and 3.
The invention can be applied to a DC-DC converter power supply which needs to be electrically isolated from input and output. As shown in fig. 2, the switching power supply 200 includes a transformer 220 composed of a primary winding, a secondary winding, and an auxiliary (third) winding. The auxiliary winding may be in a forward relationship (phase identical) with the primary winding, or the auxiliary winding may be in a flyback relationship (phase opposite) with the primary winding. In dc-dc conversion applications, such as the power over ethernet POE scheme 48V to 12V application, the auxiliary winding may be omitted and the control signal receiving end VS of the controller 204 may be coupled to the primary winding via a voltage dividing resistor.
The switching power supply 200 shown in fig. 2 further includes an input port (V IN ) An input (first) capacitor 202, a primary side (first) controller 204, a first power switch 205, a second power switch 222, a secondary side (second) controller 224, an output (second) capacitor 221, an output port (V 0 ) Output voltage dividing resistors 225 and 226, secondary winding waveform detection resistor 223, primary side controller storage capacitor 207, primary side current detection resistor 208, auxiliary winding dividing resistors 209 and 210, auxiliary winding rectifying diode 206, and start-up resistor 203. To limit the charging current of the storage capacitor 207, a current limiting resistor (not shown in fig. 2) may be optionally connected in series with the anode (or cathode) of the rectifying diode 206.
Unlike the prior art switching power supply shown in fig. 1A and 1B, the secondary power switch 222 of the switching power supply 200 (fig. 2) according to the present invention functions not only as a secondary synchronous rectification power device but also as a control signal generated by the secondary controller 224 to control the operation state of the primary power switch 205 to the primary controller 204. The second controller 224 detects the load voltage, generates a first control signal pd_sw for changing the operating state of the first power switch 205 according to an error of the load voltage, and transmits the first control signal pd_sw to the first controller 204; the second controller 224 transfers the energy of the second capacitor 221 to the first capacitor 202 by turning on and off the second power switch 222 in such a way that the first control signal pd_sw is transferred to the first controller 204; after the first controller 204 detects that the first capacitor 202 obtains the energy transferred by the second capacitor 221, the first power switch 205 is controlled to change the working state so as to control the load voltage to conform to the preset value;
the secondary controller 224 includes a synchronous rectification control circuit, an output voltage regulation circuit, and may also include an output current regulation circuit. The primary controller 204 includes a primary side current detection circuit, a control signal receiving circuit, and a driving circuit of the primary power switch 205. One specific implementation of the control loop of switching power supply 200 is as follows: when (when)After the charging process of the secondary winding to the output capacitor 221 is completed, the secondary power switch 222 is in an off state, and the primary power switch 205 is also in an off state. When the switching power supply 200 operates in the constant voltage mode, the secondary controller 224 generates the next turn-on timing control signal pd_sw of the primary power switch 205 according to the detected error of the output voltage. To transfer the control signal from the secondary controller 224 to the primary controller 204, the secondary controller 224 causes the second power switch 222 to open for a brief period of time to transfer a portion of the energy of the output capacitor 221 to the input capacitor 202. When the control signal receiving circuit of the primary controller 204 detects that energy is transferred from the output capacitor 221 to the input capacitor 202, it recognizes that this is the first control signal pd_sw sent by the second controller 224, which needs to turn on the primary power switch 205. The primary controller 204 then switches the primary power switch 205 to the on state when the primary side current reaches the first peak current I PP In this case, the current detection circuit 204 switches the first power switch 205 to the off state, thereby realizing constant voltage closed loop control for one cycle.
The switching power supply based on the present invention may also be constant current controlled by the secondary controller 224. See fig. 3 for a specific implementation.
Fig. 3 is an ac-dc converter power scheme in accordance with the present invention. Input port V IN Coupled to ac voltage V through rectifier bridge 201 AC The switching power supply 300 operates in a Discontinuous Conduction Mode (DCM), and the primary side controller 204 includes an on signal receiving circuit 302 coupled to the auxiliary winding (third winding) through voltage dividing resistors 209 and 210, responsible for receiving a first control signal pd_sw from the secondary controller 224 to switch the power switch 205 from an off state to an on state. The controller 204 further includes a primary side peak current comparator 303 having a first comparison terminal coupled to the primary side current detection resistor 208 and a second comparison terminal coupled to the reference voltage V REF1 . After the primary-side turn-ON signal receiving module 302 in the first controller 204 detects the first control signal pd_sw generated by the secondary-side controller 224 and requiring the primary-side power switch 205 to be turned ON, the module 302 outputs a positive pulse signal pow_on to set the output OUT of the RS flip-flop 301 to 1, and the power switch 205 is turned ONState, primary winding current I P Increases linearly from 0 when I P Current is increased to I PP ＝V REF1 /R 208 When the comparator 303 outputs a positive pulse signal pow_off to clear the output OUT of the RS flip-flop 301 to 0, the power switch 205 is turned OFF.
The second controller 224 shown in fig. 3 includes a synchronous rectification control module 404, a constant current control module 401, a constant voltage control module 402, an and gate 403, or gate 405. The second controller 224 detects the charging time T of the output capacitor 221 by the transformer secondary winding through the port DET and the resistor 223 ONS For synchronous rectification control and constant current/constant voltage control. As described in the previous paragraph, the current flowing through the primary power switch 205 reaches I PP The first controller 204 switches the primary power switch 205 from an on state to an off state. Output average current
I 0 ＝(1/2)*I PP *(N P /N S )*T ONS /T SW
Wherein I is PP ＝V REF1 /R 208 Is a fixed value, T SW For the switching period, T SW ＝T ONS +T DIS +T ONP ，T DIS Intermittent operation time, i.e. from T ONS Ending the period of time until the next time the first power switch 205 is turned on, T ONP The first power switch is turned on; n (N) P For the number of turns of the primary winding of the transformer, N S Is the number of turns of the secondary winding of the transformer. The constant current function is realized as follows: the second controller 224 controls the intermittent operation time T of each switching cycle DIS Let T ONS /T SW Not exceeding a fixed upper limit (e.g., 0.5). When T is one period DIS Is of insufficient length to make T ONS /T SW When the output signal cc_en=0 of the constant current control module (constant current enable) is smaller than the fixed upper limit (e.g., 0.5), the first control signal pd_sw is still 0 even though the output signal cv_en=1 of the constant voltage control module (constant voltage enable). At this time T DIS Will lengthen until T ONS /T SW Cc_en=1 after being smaller than a set fixed upper limit (e.g., 0.5), and the output pd_sw=1 of and gate 403, the first control signal pd_sw is derived fromThe second controller is transferred to the first controller, thereby realizing constant current operation of the switching power supply 300.
The embodiment of the present invention shown in fig. 3 further includes a third controller 227, which changes the ratio of the voltage dividing resistors 225 and 226 according to the needs of the load, so that the switching power supply 300 outputs different voltages according to the needs of the load, thereby realizing fast charging.
In the embodiment of fig. 3, where the output voltage varies with load demand, the polarity of the third winding may be selected to be in phase with the first winding (forward supply) such that the supply voltage of the first controller is in phase with the input voltage V IN Directly proportional to the output voltage. The power supply mode can overcome the defect that the polarity of the traditional third winding is connected with the first winding in an opposite phase (flyback power supply) way: when the output voltage varies greatly, the power supply voltage of the first controller also varies greatly.
Fig. 4 is a waveform diagram of key nodes of fig. 2 and 3 according to an embodiment of the present invention. I SP Is the secondary winding current; DET is the drain voltage waveform of the second power switch 222; t (T) ONS The time for charging the secondary winding to the output capacitor 221; cv_en (active high) is the enable signal output by the constant voltage control module 402 of fig. 3 that requires the primary power switch 205 to be turned on for stable output voltage; cc_en (active high) is an enable signal of the constant current control module 401 of fig. 3 limiting the output current; pd_sw is a control signal generated by the second controller to turn on the primary side first power switch 205, which is transferred to the primary side first controller 204 by way of a brief turn-on of the second power switch to transfer a small portion of the energy on the output capacitance 221 to the input capacitance 202; the DRV is a driving signal of the second controller 224 to the second power switch 222, including synchronous rectification driving (and T ONS Coincidence) and a first control signal pd_sw controlling the primary power switch 205; i PP Is the primary peak current; VS is an auxiliary (third) winding (with polarity opposite to primary winding) waveform for receiving the first control signal pd_sw sent from the second controller 224 to control the primary power switch 205 to be turned on; OUT is a signal of the first controller 204 driving the first power switch 205. When the first control signal PD_SW generated by the second controller 224 is highAfter the energy is low, a small part of energy of the output capacitor 221 is transferred to the primary input capacitor 202, the parasitic body diode of the first power switch 205 is conducted, and the first controller 204 detects that the energy is transferred from the output capacitor 221 to the input capacitor 202 and drives the first power switch 205 to be switched from an off state to an on state; by adopting the method of the invention, the control of the working state of the first power switch 205 by the second controller 224 is realized by transmitting a small part of energy of the output capacitor 221 to the input capacitor 202 through the second power switch 222 and the transformer, and the first power switch 205 can be turned on when the power port voltage is basically 0V, namely the first power switch 205 is turned on in a zero crossing way, so that the switching loss is reduced, and the conversion efficiency is improved.
While the invention has been described in terms of the above exemplary embodiments, it is to be understood that the terminology used is intended to be in the nature of words of description and of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims. Therefore, all changes and modifications that come within the scope of the claims or equivalents thereof are intended to be embraced thereby.
Claims (8)
1. A switching power supply, comprising:
a first port coupled to an input voltage;
a first capacitor coupled to the first port;
a transformer having a first winding and a second winding, the first winding coupled to a first capacitor;
the first power switch is coupled to the first winding of the transformer and has two working states of on and off;
a first controller coupled to the first power switch and the transformer;
a second port coupled to a switching power supply load, providing voltage and current to the load;
a second capacitor coupled to the second port and the transformer second winding;
the second power switch is coupled to the second winding of the transformer and has two working states of on and off;
a second controller coupled to the second power switch, the second port, and the transformer second winding;
the second controller detects the load voltage and generates a first control signal to control the working state of the first power switch so that the load voltage accords with a preset value; the method for transmitting the first control signal from the second controller to the first controller comprises the following steps: the second controller controls the on and off of the second power switch to transfer part of energy of the second capacitor to the first capacitor; after the first controller detects that the first capacitor obtains energy transferred by the second capacitor, the first controller controls the first power switch to change state;
the second controller comprises a constant current control circuit which is coupled to the second winding of the transformer and the second port of the switching power supply; the constant current control circuit limits the current flowing through the load, and when the load current is larger than a preset value, the generation of a first control signal is forbidden;
the second controller comprises a constant voltage control circuit and a constant current control circuit, the constant voltage control circuit generates a constant voltage enabling signal according to the error of the load voltage, and the constant current control circuit generates a constant current enabling signal according to the magnitude of the load current; when the load current is lower than a preset value, the constant current enabling signal is valid; generating a first control signal when both the constant voltage enabling signal and the constant current enabling signal are valid, wherein the first control signal is transmitted to a first controller through a second power switch and a transformer;
when a first control signal generated by the second controller is changed from high to low, a small part of energy of the second capacitor is transferred to the first capacitor, a parasitic body diode of the first power switch is conducted, and the first controller drives the first power switch to be switched from a cut-off state to a conducting state after detecting that the energy is transferred from the second capacitor to the first capacitor; the control of the working state of the first power switch by the second controller is realized by adopting a mode of transmitting a small part of energy of the second capacitor to the first capacitor through the second power switch and the transformer, so that the first power switch enters a conducting state when the power port voltage is 0V, namely the first power switch voltage is zero-crossing on.
2. The switching power supply of claim 1 wherein the first port is coupled to an ac power source through a rectifying circuit to form an ac-to-dc converter.
3. The switching power supply of claim 1 wherein the second controller includes a synchronous rectification circuit that controls the second power switch to achieve synchronous rectification when energy is transferred from the first capacitor to the second capacitor.
4. The switching power supply of claim 1 wherein said transformer includes a third winding coupled to a first controller; the polarity of the third winding is the same as or opposite to that of the first winding; the first controller receives the first control signal generated by the second controller through the third winding.
5. The switching power supply of claim 4 wherein said switching power supply includes a third capacitor coupled to the first controller and to the third winding of the transformer; the third winding is of the same polarity as the first winding and supplies power to the third capacitor, the power supply voltage being proportional to the first port voltage and independent of the second port voltage.
6. The switching power supply of claim 1 wherein the first controller includes a control signal receiving circuit coupled to the transformer; when the control signal receiving circuit detects that energy is transferred from the second capacitor to the first capacitor, the first controller switches the first power switch from an off state to an on state.
7. The switching power supply of claim 1 wherein the first controller includes a current detection circuit coupled to the first power switch; when the current flowing through the first power switch reaches a first peak current, the first controller switches the first power switch from an on state to an off state.
8. The switching power supply of claim 1 wherein the switching power supply comprises a third controller coupled to the second controller and the second port; and the third controller changes the voltage of the second port according to the load requirement to realize quick charging.
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| CN113765387B (en) * | 2020-06-02 | 2024-04-26 | 上海芯熠微电子有限公司 | Method and device for widening the voltage range of AC-DC converter |
| CN112019060A (en) * | 2020-08-28 | 2020-12-01 | 东莞市大忠电子有限公司 | Vehicle-mounted AC/DC quick-charging power adapter circuit |
| CN113179026A (en) * | 2021-05-17 | 2021-07-27 | 上海南芯半导体科技有限公司 | Flyback power supply circuit and control method thereof |
| CN115514195B (en) * | 2021-06-07 | 2025-08-05 | 广州视源电子科技股份有限公司 | Power supply control circuit, power supply circuit control method, and electronic equipment |
| CN114142560A (en) * | 2021-11-29 | 2022-03-04 | 东莞新能安科技有限公司 | Protection circuit, battery management system, battery pack and electric equipment |
| CN116961432B (en) * | 2023-06-29 | 2025-06-13 | 上海芯熠微电子有限公司 | A switching power supply fast charging system and a secondary side control method without optocoupler |
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| CN105529799A (en) * | 2014-09-28 | 2016-04-27 | 比亚迪股份有限公司 | Charging system based on secondary control and its secondary control device |
| CN106533179A (en) * | 2015-09-11 | 2017-03-22 | 万国半导体(开曼)股份有限公司 | Voltage converter |
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| US9318963B2 (en) * | 2013-03-13 | 2016-04-19 | Dialog Semiconductor Inc. | Switching power converter with secondary to primary messaging |
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