CN108880296B - Power supply conversion system - Google Patents
Power supply conversion system Download PDFInfo
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- CN108880296B CN108880296B CN201810601234.XA CN201810601234A CN108880296B CN 108880296 B CN108880296 B CN 108880296B CN 201810601234 A CN201810601234 A CN 201810601234A CN 108880296 B CN108880296 B CN 108880296B
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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
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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
- H02M3/33507—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 with automatic control of the output voltage or current, e.g. flyback converters
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- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The power conversion system comprises a transformer, a bipolar transistor BJT and a pulse width modulation control chip PWM IC, wherein after the power conversion system enters a closed loop state, the power conversion system comprises: generating first and second control signals based on a current sense voltage indicative of a current flowing through a primary winding of the transformer and an output representative voltage indicative of a dc output voltage; controlling the first and second power switches to be turned on and off based on the first control signal, and controlling the third power switch to be turned on and off based on the second control signal, wherein: when the first and second power switches are changed from the on state to the off state but the third power switch is in the off state, the PWM IC controls the BJT to be in the on state, so that the dc input voltage obtained by rectifying and filtering the ac input voltage charges the capacitor connected to the second terminal of the PWM IC via the primary winding of the transformer, the BJT, the first terminal of the PWM IC, and the diode connected between the first and second terminals of the PWM IC inside the PWM IC.
Description
Technical Field
The invention relates to the field of circuits, in particular to a power supply conversion system.
Background
Fig. 1 is a circuit diagram of a conventional flyback Alternating Current (AC) -Direct Current (DC) power conversion system. As shown in fig. 1, the conventional AC-DC power conversion system converts an AC input voltage into a DC output voltage as follows:
the AC input voltage is filtered and rectified by an electromagnetic interference (EMI) filter and a rectifier (including a rectifier bridge consisting of four diodes and a bulk capacitor (bulk capacitor)) to become a DC input voltage VIN; the DC input voltage VIN charges a capacitor C1 connected between a VDD terminal of a pulse width modulation control chip (PWM IC) and a reference ground through a starting resistor Rst; when the voltage on capacitor C1 (i.e., the voltage at the VDD terminal) is higher than the under-voltage-lockout (UVLO) voltage of the PWM IC, the PWM IC begins to operate; the PWM IC controls a Bipolar Junction Transistor (BJT) to change from an off state to an on state, such that a primary winding Np of the transformer T1 stores energy provided by the DC input voltage VIN, and a current flowing through the primary winding Np of the transformer T1 increases linearly; the PWM IC detects the current flowing through the primary winding Np of the transformer T1 based on the current detection voltage across the current detection resistor Rs connected between the primary winding Np of the transformer T1 and the reference ground via the CS terminal (since the current detection voltage across the current detection resistor Rs can represent the current flowing through the primary winding Np of the transformer T1); when the current flowing through the primary winding Np of the transformer T1 reaches a predetermined current threshold (i.e., the voltage at the current detection voltage/CS terminal reaches the voltage at the FB terminal/the output characterization voltage/the internal highest clamping voltage Vocp), the PWM IC controls the Bipolar Junction Transistor (BJT) to change from the on-state to the off-state; when a Bipolar Junction Transistor (BJT) is in an off state, energy stored in a primary winding Np of the transformer T1 is discharged to a secondary winding Ns of the transformer T1; the voltage on the secondary winding Ns of the transformer T1 is filtered and rectified by a filter rectification component consisting of a diode D1 and an output capacitor C0 to become a DC output voltage VO; the DC output voltage VO gradually rises; the TL431 detects the DC output voltage VO based on an output characterization voltage obtained by dividing the DC output voltage VO by resistors R1 and R0, and feeds the output characterization voltage back to an FB terminal of the PWM IC through an optocoupler when the DC output voltage VO reaches a preset voltage threshold; the PWM IC controls a Bipolar Junction Transistor (BJT) to change from an off state to an on state based on the output characterization voltage, thereby stabilizing the DC output voltage VO at a predetermined voltage threshold.
Fig. 2 is an internal circuit diagram of the PWM IC shown in fig. 1. As shown in fig. 2, inside the PWM IC, the FB terminal is connected to the voltage AVDD via a pull-up resistor Rfb; when the DC output voltage VO does not reach the predetermined voltage threshold, the voltage at the FB terminal is pulled up to the voltage AVDD by the pull-up resistor Rfb, and the PWM IC controls the Bipolar Junction Transistor (BJT) to change from the on state to the off state when the voltage at the CS terminal (i.e., the current detection voltage) reaches the internal highest clamping voltage Vocp; when the DC output voltage VO reaches a predetermined voltage threshold, the power conversion system shown in fig. 1 enters a closed loop state, the voltage at the FB terminal (i.e., the output characterization voltage) is lower than the internal highest clamping voltage Vocp, and the PWM IC controls the bipolar transistor (BJT) to change from the on state to the off state when the voltage at the CS terminal (i.e., the current detection voltage) reaches the voltage at the FB terminal (i.e., the output characterization voltage).
After the power conversion system shown in fig. 1 enters the closed loop state, the auxiliary winding Naux of the transformer T1 supplies power to the PWM IC through the diode D2 and the capacitor C1, which has the disadvantage that the auxiliary winding Naux of the transformer T1 and the diode D2 connected thereto need to be additionally added, which increases the complexity of the transformer and thus increases the system cost.
Disclosure of Invention
In view of one or more of the above-mentioned problems, the present invention provides a novel power conversion system, which can eliminate the auxiliary winding of the transformer and the diode connected thereto, reduce the complexity of the transformer and thus save the system cost.
The power conversion system according to the embodiment of the invention is used for converting an alternating current input voltage into a direct current output voltage, and comprises a transformer, a bipolar transistor and a pulse width modulation control chip, wherein after the power conversion system enters a closed loop state, the power conversion system is arranged in the pulse width modulation control chip:
generating a first control signal and a second control signal based on a current detection voltage representing a current flowing through a primary winding of the transformer and an output characterization voltage representing a direct current output voltage;
controlling the first power switch and the second power switch to be switched on and off based on the first control signal, and controlling the third power switch to be switched on and off based on the second control signal, wherein:
when the first power switch and the second power switch are both in a conducting state and the third power switch is in a switching-off state, the pulse width modulation control chip controls the bipolar transistor to be changed from the switching-off state to the conducting state, so that the transformer starts to store energy;
when the first power switch and the second power switch are changed from the on state to the off state but the third power switch is still in the off state, the pulse width modulation control chip controls the bipolar transistor to be still in the on state, so that the direct current input voltage obtained by rectifying and filtering the alternating current input voltage charges a capacitor which is arranged outside the pulse width modulation control chip and connected to the second terminal of the pulse width modulation control chip through a primary winding of the transformer, the bipolar transistor, the first terminal of the pulse width modulation control chip and a diode which is arranged inside the pulse width modulation control chip and connected between the first terminal and the second terminal of the pulse width modulation control chip;
when the third power switch is changed from the turn-off state to the turn-on state, the pulse width modulation control chip controls the bipolar transistor to be changed from the turn-on state to the turn-off state, so that the charging of the direct current input voltage to a capacitor connected to the second terminal of the pulse width modulation control chip outside the pulse width modulation control chip is finished.
The power supply conversion system provided by the embodiment of the invention adopts a novel power supply mode to supply power for the pulse width modulation control chip, and can save an auxiliary winding of the transformer and a diode connected with the auxiliary winding, thereby simplifying the manufacture of the transformer and saving the system cost.
Drawings
The invention may be better understood from the following description of specific embodiments thereof taken in conjunction with the accompanying drawings, in which:
fig. 1 is a circuit diagram of a conventional flyback AC-DC power conversion system;
FIG. 2 is an internal circuit diagram of the PWM IC shown in FIG. 1;
FIG. 3 is a circuit diagram of a secondary feedback controlled flyback AC-DC power conversion system according to an embodiment of the present invention;
FIG. 4 is an internal circuit diagram of the PWM IC shown in FIG. 3;
fig. 5 is an internal circuit diagram of the PWM control unit shown in fig. 4;
FIG. 6 is a timing diagram of signals at some terminals and some internal signals of the PWM IC shown in FIG. 3;
fig. 7 is a circuit diagram of the diode D3 shown in fig. 4 implemented with PMOS;
fig. 8 is a circuit diagram of a flyback AC-DC power conversion system employing primary side feedback control of a PWM IC operating on a similar principle to that of fig. 4;
fig. 9 is an internal circuit diagram of a PWM control unit in the PWM IC shown in fig. 8;
fig. 10 is a circuit diagram of an AC-DC power conversion system of the forward architecture of the PWM IC shown in fig. 4.
Detailed Description
Features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, numerous specific details 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 some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific configuration set forth below, but rather covers any modification, substitution, and improvement of elements, components, and algorithms without departing from the spirit of the invention. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present invention.
Fig. 3 shows a circuit diagram of a flyback AC-DC power conversion system with secondary-side feedback control according to an embodiment of the present invention. As shown in fig. 3, the AC-DC power conversion system according to the embodiment of the present invention converts an AC input voltage into a DC output voltage as follows:
the AC input voltage is filtered and rectified by an electromagnetic interference (EMI) filter and a rectifier (including a rectifier bridge consisting of four diodes and a bulk capacitor (bulk capacitor)) to become a DC input voltage VIN; the DC input voltage VIN supplies power to the base electrode of a Bipolar Junction Transistor (BJT) through a starting resistor Rst, so that the Bipolar Junction Transistor (BJT) is changed from an off state to an on state; the DC input voltage VIN charges a capacitor C1 connected to a VDD terminal outside the PWM IC through a primary winding Np of a transformer T1, a Bipolar Junction Transistor (BJT) and a diode D3 connected between a SW terminal and the VDD terminal inside the PWM IC; when the voltage on capacitor C1 (i.e., the voltage at the VDD terminal) exceeds the under-voltage-lockout (UVLO) voltage of the PWM IC, the PWM IC begins to operate; the primary winding Np of the transformer T1 stores the energy provided by the DC input voltage VIN, and the current flowing through the primary winding Np of the transformer T1 increases linearly; the PWM IC detects the current flowing through the primary winding Np of the transformer T1 based on the current detection voltage across the current detection resistor Rs connected between the bulk capacitor in the rectifier and the reference ground via the CS terminal (since the current detection voltage across the current detection resistor Rs can characterize the current flowing through the primary winding Np of the transformer T1); when the current flowing through the primary winding Np of the transformer T1 reaches a predetermined current threshold (i.e., the inverse voltage of the current detection voltage/the voltage at the CS terminal reaches the voltage at the FB terminal/the output characterization voltage/the internal highest clamping voltage Vocp), the PWM IC controls the Bipolar Junction Transistor (BJT) to change from the on-state to the off-state; when a Bipolar Junction Transistor (BJT) is in an off state, energy stored in a primary winding Np of the transformer T1 is discharged to a secondary winding Ns of the transformer T1; the voltage on the secondary winding Ns of the transformer T1 is filtered and rectified by a filter rectification component consisting of a diode D1 and an output capacitor C0 to become a DC output voltage VO; the DC output voltage VO gradually rises; the TL431 detects the DC output voltage VO based on an output characterization voltage obtained by dividing the DC output voltage VO by the resistors R1 and R0, and feeds back the output characterization voltage to the FB terminal of the PWM IC through an optocoupler when the DC output voltage VO reaches a predetermined voltage threshold, so that the PWM IC controls a bipolar transistor (BJT) to be changed from an off state to an on state based on the output characterization voltage, thereby stabilizing the DC output voltage VO at the predetermined voltage threshold.
Fig. 4 is an internal circuit diagram of the PWM IC shown in fig. 3. As shown in fig. 4, inside the PWM IC, the FB terminal is connected to the voltage AVDD via a pull-up resistor Rfb; when the DC output voltage VO does not reach the predetermined voltage threshold, the voltage at the FB terminal is pulled up to the voltage AVDD by the pull-up resistor Rfb, and the PWM IC controls the Bipolar Junction Transistor (BJT) to change from the on state to the off state when the inverse voltage of the voltage at the CS terminal (i.e., the current detection voltage) reaches the internal highest clamping voltage Vocp; when the DC output voltage VO reaches a predetermined voltage threshold, the power conversion system shown in fig. 3 enters a closed loop state, the voltage at the FB terminal is lower than the internal highest clamping voltage Vocp, and the PWM IC controls the Bipolar Junction Transistor (BJT) to change from the on state to the off state when the inverse voltage of the voltage at the CS terminal (i.e., the current detection voltage) reaches the voltage at the FB terminal (i.e., the output characterization voltage).
After the power conversion system shown in fig. 4 enters the closed loop state, the PWM control unit generates a PWM signal and a PWM _ pre signal based on the voltages at the CS terminal and the FB terminal of the PWM IC (i.e., the current detection voltage and the output characterization voltage) to control the turn-on and turn-off of the power switches M0 to M2 to control the turn-on and turn-off of the Bipolar Transistor (BTJ); the power switch M0 is in a conducting state when the pwm _ pre signal is high and in a shutdown state when the pwm _ pre signal is low; the power switch M1 is in an off state when the pwm signal is high and in an on state when the pwm signal is low; the power switch M2 is in a conducting state when the pwm _ pre signal is high and in a shutdown state when the pwm _ pre signal is low; when both power switches M0 and M2 are in an on state and power switch M1 is in an off state, the Ibase drives a Bipolar Junction Transistor (BJT) external to the current-controlled PWM IC from an off state to an on state such that transformer T1 begins storing energy; the Ibase drive current increases with increasing current through the primary winding Np of the transformer T1; when the power switches M0 and M2 are turned from the on state to the off state but the power switch M1 is still in the off state, the Bipolar Junction Transistor (BJT) is still in the on state, the DC input voltage VIN charges the capacitor C1 connected to the VDD terminal of the PWM IC through the primary winding Np of the transformer T1, the Bipolar Junction Transistor (BJT), the SW terminal of the PWM IC, and the diode D3, and at this time, the transformer T1 is still in the energy storage state, and the current flowing through the primary winding Np of the transformer T1 continues to increase; when the power switch M1 changes from the off state to the on state, the Ibase driving current no longer flows to the Bipolar Junction Transistor (BJT) outside the PWM IC, the Bipolar Junction Transistor (BJT) changes from the on state to the off state, the charging of the capacitor C1 connected to the VDD terminal of the PWM IC is completed, and at this time, the energy stored in the primary winding Np of the transformer T1 is released to the secondary winding Ns of the transformer T1.
Fig. 5 is a timing diagram of signals at some terminals and some internal signals of the PWM IC shown in fig. 3. Fig. 6 is an internal circuit diagram of the PWM control unit shown in fig. 4. As shown in fig. 5 and 6, the PWM signal changes from the low level to the high level when the rising edge of the clock signal generated by the oscillator arrives, changes from the high level to the low level when the inverted voltage of the voltage at the CS terminal (i.e., the current detection voltage) of the PWM IC reaches the voltage at the FB terminal (i.e., the output characterization voltage) of the PWM IC or the internal highest clamping voltage Vocp, until the clock signal generated by the oscillator changes from the low level to the high level again when the rising edge of the next clock cycle arrives; the PWM _ pre signal changes from a low level to a high level when a rising edge of the clock signal generated by the oscillator arrives, and changes from a high level to a low level when the inverted voltage-superimposed offset voltage Voffset of the voltage at the CS terminal of the PWM IC (i.e., the current detection voltage) reaches the voltage at the FB terminal of the PWM IC (i.e., the output characterization voltage) or the internal highest clamping voltage Vocp until the clock signal generated by the oscillator changes from a low level to a high level again when the rising edge of the next clock cycle arrives.
Here, since the PWM _ pre signal changes from a high level to a low level PWM _ pre signal when the inverse voltage-superimposed offset voltage Voffset of the voltage at the CS terminal of the PWM IC reaches the voltage at the FB terminal of the PWM IC or the internal highest clamping voltage Vocp, the PWM signal changes from a high level to a low level in advance of the PWM signal.
In the PWM IC shown in fig. 4, the comparator 1 divides the voltage at the VDD terminal based on the resistors R2 and R3 to obtain a supply representative voltage, and outputs a high level when the supply representative voltage exceeds a supply voltage threshold, so that the power switch M1 changes from an off state to an on state to change a bipolar transistor (BJT) from an on state to an off state to prevent the voltage across the capacitor C1 connected to the VDD terminal (i.e., the voltage at the VDD terminal) from being charged too high to damage the PWM IC.
According to the power conversion system disclosed by the embodiment of the invention, the power supply function of the PWM IC and the PWM modulation process in the traditional power conversion system can be realized without an auxiliary winding of the transformer T1 and a diode connected with the auxiliary winding, so that the system design is simplified, and the system cost is saved.
It will be appreciated by those skilled in the art that diode D3 shown in fig. 4 may be replaced by a PMOS. Fig. 7 is a circuit diagram in which the diode D3 shown in fig. 4 is implemented with a PMOS. In fig. 7, the PMOS on and off are controlled by the pwm signal and the pwm _ pre signal together.
Fig. 8 is a circuit diagram of a primary side feedback controlled AC-DC power conversion system using a PWM IC operating on a similar principle to that of fig. 4. Fig. 9 is an internal circuit diagram of a PWM control unit in the PWM IC shown in fig. 8. The PWM control unit shown in fig. 9 is different from the PWM control unit shown in fig. 6 in that: the demagnetization detection module generates a demagnetization platform voltage representing the magnitude of the DC output voltage VO based on the voltage at the FB terminal of the PWM IC, the sampling module samples and holds the demagnetization platform voltage onto a capacitor C0, and an error amplifier EA generates an error amplification signal vcomp, wherein the vcomp voltage is equal to the voltage at the FB terminal of the PWM IC in FIG. 4, and the larger the vcomp represents the larger the output load current, and the smaller the vcomp represents the smaller the output load current.
Fig. 9 is a circuit diagram of an AC-DC power conversion system employing the forward architecture of the PWM IC shown in fig. 4. Here, the operation principle of the PWM IC is exactly the same as that described in conjunction with fig. 4 and 5, and thus, the description thereof is omitted.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. For example, the algorithms described in the specific embodiments may be modified without departing from the basic spirit of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (7)
1. A power conversion system for converting an AC input voltage to a DC output voltage, comprising a transformer, a bipolar transistor, and a PWM control chip, wherein, after the power conversion system enters a closed loop state, within the PWM control chip:
generating a first control signal and a second control signal based on a current sense voltage characterizing a current flowing through a primary winding of the transformer and an output characterization voltage characterizing the DC output voltage;
controlling the first power switch and the second power switch to be switched on and off based on the first control signal, and controlling the third power switch to be switched on and off based on the second control signal, wherein:
when the first power switch and the second power switch are both in a conducting state and the third power switch is in an off state, the pulse width modulation control chip controls the bipolar transistor to be changed from the off state to the conducting state, so that the transformer starts to store energy;
when the first power switch and the second power switch are changed from an on state to an off state but the third power switch is still in the off state, the pwm control chip controls the bipolar transistor to be still in the on state, so that a dc input voltage obtained by rectifying and filtering the ac input voltage is charged to a capacitor connected to the second terminal of the pwm control chip outside the pwm control chip via the primary winding of the transformer, the bipolar transistor, the first terminal of the pwm control chip, and a PMOS inside the pwm control chip and connected between the first terminal and the second terminal of the pwm control chip, and the on and off of the PMOS is controlled by the first control signal and the second control signal;
when the third power switch is changed from an off state to an on state, the pulse width modulation control chip controls the bipolar transistor to be changed from an on state to an off state, so that the charging of the direct current input voltage to a capacitor connected to a second terminal of the pulse width modulation control chip outside the pulse width modulation control chip is finished,
and inside the PWM control chip, a power supply representation voltage is obtained by dividing the voltage at the second terminal of the PWM control chip, and the third power switch is controlled to be changed from an off state to an on state when the power supply representation voltage exceeds a power supply threshold voltage, so that the bipolar transistor is changed from the on state to the off state.
2. The power conversion system of claim 1, wherein, within the pulse width modulation control chip:
generating a clock signal by an oscillator;
the first control signal changes from low level to high level when the rising edge of the clock signal comes, changes from high level to low level when the inverted voltage of the current detection voltage reaches the output representation voltage or the highest clamping voltage inside the pulse width modulation control chip, and changes from low level to high level again until the rising edge of the clock signal in the next clock period comes;
the second control signal changes from a low level to a high level when a rising edge of the clock signal comes, changes from a high level to a low level when an inverted voltage superposition bias voltage of the current detection voltage reaches the output characterization voltage or the highest clamping voltage, and changes from the low level to the high level again until the clock signal changes from the low level to the high level when the rising edge of the next clock period comes.
3. The power conversion system of claim 1, wherein prior to operation of the pulse width modulation control chip:
the direct current input voltage supplies power to the base electrode of the bipolar transistor through a starting resistor, so that the bipolar transistor is changed from an off state to an on state, and the direct current input voltage charges a capacitor which is arranged outside the pulse width modulation control chip and connected to a second terminal of the pulse width modulation control chip through a primary winding of the transformer, the bipolar transistor, a first terminal of the pulse width modulation control chip and a diode which is arranged inside the pulse width modulation control chip and connected between the first terminal and the second terminal of the pulse width modulation control chip;
and when the voltage of a capacitor outside the pulse width modulation control chip and connected to the second terminal of the pulse width modulation control chip exceeds the undervoltage locking voltage of the pulse width modulation control chip, the pulse width modulation control chip starts to work.
4. The power conversion system of claim 1, wherein the pwm control chip controls the bipolar transistor to change from the on state to the off state when the inverse voltage of the current sense voltage reaches a highest clamping voltage inside the pwm control chip when the dc output voltage does not reach a predetermined voltage threshold; and when the direct current output voltage reaches the preset voltage threshold value, controlling the bipolar transistor to be changed from a conducting state to a closing state when the reverse voltage of the current detection voltage reaches the output representation voltage.
5. The power conversion system of claim 1, wherein the power conversion system is a secondary-side feedback controlled flyback power conversion system.
6. The power conversion system of claim 1, wherein the power conversion system is a forward architecture power conversion system.
7. The power conversion system of claim 1, wherein the power conversion system is a primary-side feedback controlled flyback power conversion system.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810601234.XA CN108880296B (en) | 2018-06-12 | 2018-06-12 | Power supply conversion system |
| TW107125238A TWI657653B (en) | 2018-06-12 | 2018-07-20 | Power conversion system |
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| CN201810601234.XA CN108880296B (en) | 2018-06-12 | 2018-06-12 | Power supply conversion system |
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| US9595874B2 (en) | 2012-04-12 | 2017-03-14 | On-Bright Electronics (Shanghai) Co., Ltd. | Systems and methods for regulating power conversion systems with output detection and synchronized rectifying mechanisms |
| US10622902B2 (en) | 2012-04-12 | 2020-04-14 | On-Bright Electronics (Shanghai) Co., Ltd. | Systems and methods for regulating power conversion systems with output detection and synchronized rectifying mechanisms |
| CN111146961B (en) | 2020-01-20 | 2022-04-12 | 昂宝电子（上海）有限公司 | Control circuit and method for controlling synchronous rectification system |
| CN113541444B (en) * | 2020-04-15 | 2023-03-24 | 成都中启易联科技有限公司 | Current recovery circuit, switch converter and integrated circuit |
| CN111697838B (en) | 2020-05-29 | 2023-09-26 | 昂宝电子（上海）有限公司 | Synchronous rectification control circuit, method and switching power supply system |
| CN112838772B (en) * | 2021-01-18 | 2022-05-13 | 昂宝电子（上海）有限公司 | Flyback switching power supply and control method thereof |
| CN112821727B (en) * | 2021-03-11 | 2022-06-28 | 昂宝电子（上海）有限公司 | Switching power supply system |
| CN113394983B (en) * | 2021-07-01 | 2023-07-04 | 上海南芯半导体科技股份有限公司 | Voltage feedback circuit of flyback converter and control method thereof |
| CN114244153B (en) * | 2021-11-23 | 2023-11-03 | 昂宝电子（上海）有限公司 | Switching power supply, control chip and control method thereof |
| CN114285249B (en) * | 2021-12-06 | 2024-01-26 | 昂宝电子（上海）有限公司 | Switching power supply, control chip and control method thereof |
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| US6853174B1 (en) * | 2003-08-11 | 2005-02-08 | Micrel, Inc. | Selective high-side and low-side current sensing in switching power supplies |
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| US9246391B2 (en) * | 2010-01-22 | 2016-01-26 | Power Systems Technologies Ltd. | Controller for providing a corrected signal to a sensed peak current through a circuit element of a power converter |
| CN102957304B (en) * | 2011-08-29 | 2016-04-27 | 比亚迪股份有限公司 | A kind of drive circuit of triode and driving method thereof |
| CN103023298B (en) * | 2013-01-04 | 2014-11-05 | 无锡硅动力微电子股份有限公司 | Self-powered circuit applied to AC-DC (alternating current to digital current) switching mode power converter |
| CN103825469B (en) * | 2014-03-06 | 2016-05-18 | 矽力杰半导体技术(杭州)有限公司 | For control circuit and the isolated converter of isolated converter |
| CN103929055A (en) * | 2014-04-30 | 2014-07-16 | 矽力杰半导体技术(杭州)有限公司 | Power supply circuit and switching power supply |
| CN106130319B (en) * | 2016-08-22 | 2019-04-16 | 昂宝电子（上海）有限公司 | A kind of system and method for driving power transistor |
| CN106374733B (en) * | 2016-10-28 | 2019-04-16 | 昂宝电子（上海）有限公司 | A kind of system for Switching Power Supply quick start |
| CN106685236B (en) * | 2017-03-10 | 2019-03-15 | 绍兴光大芯业微电子有限公司 | The controllable circuit structure without auxiliary winding isolation type switching power supply of primary current |
-
2018
- 2018-06-12 CN CN201810601234.XA patent/CN108880296B/en active Active
- 2018-07-20 TW TW107125238A patent/TWI657653B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| TWI657653B (en) | 2019-04-21 |
| TW202002494A (en) | 2020-01-01 |
| CN108880296A (en) | 2018-11-23 |
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