CN112736853B - Primary side control circuit, control method and power conversion circuit - Google Patents
Primary side control circuit, control method and power conversion circuit Download PDFInfo
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- CN112736853B CN112736853B CN202110017065.7A CN202110017065A CN112736853B CN 112736853 B CN112736853 B CN 112736853B CN 202110017065 A CN202110017065 A CN 202110017065A CN 112736853 B CN112736853 B CN 112736853B
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- 238000004804 winding Methods 0.000 claims abstract description 80
- 238000001514 detection method Methods 0.000 claims abstract description 66
- 230000005284 excitation Effects 0.000 claims abstract description 30
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- 230000002093 peripheral effect Effects 0.000 description 2
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/006—Calibration or setting of parameters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
- H02H3/207—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage also responsive to under-voltage
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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
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention provides a primary side control circuit, a control method and a power supply conversion circuit. The resistor module presents a first preset resistance value in a current loop of the primary winding excitation stage, and presents a second preset resistance value in a current loop of the secondary winding degaussing stage. In the primary winding excitation stage, the control chip acquires a first detection signal representing a current signal flowing through the multiplexing pin, and outputs a first control signal according to the first detection signal. In the secondary winding degaussing stage, the control chip acquires a second detection signal representing the current signal flowing through the multiplexing pin, and outputs a second control signal according to the second detection signal. The invention can realize the pin multiplexing of at least two protection functions and can respectively adjust the trigger threshold parameters of each protection function according to application requirements.
Description
Technical Field
The invention belongs to the field of power electronics, relates to a circuit protection technology of a power supply circuit, and particularly relates to a primary side control circuit, a control method and a power supply conversion circuit.
Background
In a typical flyback architecture system for secondary feedback control, the auxiliary winding is typically used in a circuit for circuit protection and signal detection. For specific circuit protection and signal detection, there are external accurate over-temperature protection (OTP for short), output over-voltage protection (OVP for short), output under-voltage protection (UVP for short), input under-voltage protection (BOP for short), input over-voltage protection (VIN OVP for short), and detection of demagnetizing zero crossing. In particular, there are different detection implementations when implementing circuit protection. For example, during degaussing of the secondary circuit, the voltage dividing resistor detection realizes output OVP and UVP protection, such as detecting the magnitude of current flowing into the chip IC during degaussing of the secondary circuit to characterize the output voltage signal, thereby realizing output OVP and UVP protection. Different protections are implemented with the configuration of the periphery changing, so that the types of protection compatible with the same application periphery are limited.
From the application point of view, the more the control chip has the protection function, the stability and the reliability of the power supply system can be effectively ensured. As shown in fig. 1, in the prior art, over-temperature protection and output over-voltage protection are realized through a pin multiplexing mode, and in a power supply system, the voltage of a resistor RT is detected in a time-sharing multiplexing mode in the technical scheme of fig. 1, so that the temperature of an external NTC resistor is further represented, and thus, accurate over-temperature protection control is performed. The over-temperature detection signal and the over-voltage detection signal are obtained in a time sharing way and are judged through the temperature protection circuit and the over-voltage protection circuit respectively, so that the function multiplexing is realized in a pin multiplexing mode. But its peripheral configuration can only be resistor Rovp, diode D1 and resistor RT, and resistor Rovp acts as a sampling resistor only near a short circuit to ground (i.e., OTP detection mask) at the PRT pin, with OVP detection being achieved by the magnitude of the current flowing into the PRT pin. Aiming at the peripheral configuration based on accurate OTP protection and degaussing current detection (OVP) of an inflow pin, the method has the defect that the adjustable configuration of input voltage cannot be realized, and a reasonable implementation mode cannot be provided. Furthermore, a single resistor Rovp cannot achieve a reasonably adjustable configuration when it comes to situations where an input requires adjustable BOP protection and an output requires adjustable OVP protection.
In view of this, it is necessary to provide a new structure or control method for solving the above-mentioned problems of multiplexing the functions of input undervoltage protection and output overvoltage protection, etc., and adjusting the functional parameters according to the application requirements.
Disclosure of Invention
In order to solve at least part of the above problems, the present invention provides a primary side control circuit, a control method and a power conversion circuit, so as to solve the problem of adjusting the functional parameters of the multiplexing pins.
The invention discloses a primary side control circuit which is used for primary side control of a power supply conversion circuit, wherein the primary side control circuit comprises a control chip, the control chip comprises a multiplexing pin, a first protection function module and a second protection function module, and the multiplexing pin is coupled to an auxiliary winding through a resistance module in the primary side control circuit; the resistor module presents a first preset resistance value in a current loop of a primary winding excitation stage, and presents a second preset resistance value in a current loop of a secondary winding demagnetizing stage; wherein,
In the primary winding excitation stage, a control chip acquires a first detection signal representing a current signal flowing through a multiplexing pin, and a first protection function module outputs a first control signal according to the first detection signal; the first control signal is used for controlling a main switch tube in the primary circuit; and
In the secondary winding degaussing stage, the control chip acquires a second detection signal representing a current signal flowing through the multiplexing pin, and the second protection function module outputs a second control signal according to the second detection signal; the second control signal is used for controlling the main switch tube.
In one embodiment of the present invention, the resistor module includes a first resistor, a second resistor, and a first diode; the first end of the first resistor is coupled with the multiplexing pin, the second end of the first resistor is coupled with the auxiliary winding, the second resistor is connected with the first diode in series, and the second resistor and the first diode are connected between the first end and the second end of the first resistor in parallel.
In an embodiment of the present invention, the first protection function module includes a first switch and a first comparison circuit; the first end of the first switch is coupled with the multiplexing pin; the first input end of the first comparison circuit is coupled with the first reference signal end, the second input end of the first comparison circuit is coupled with the second end of the first switch, and the output end of the first comparison circuit is coupled with the main switch tube; and
The second protection function module comprises a second switch and a second comparison circuit; the first end of the second switch is coupled with the multiplexing pin; the first input end of the second comparison circuit is coupled with the second end of the second switch, the second input end of the second comparison circuit is coupled with the second reference signal end, and the output end of the second comparison circuit is coupled with the main switch tube.
In an embodiment of the present invention, the first protection function module is an input under-voltage protection circuit and/or an input over-voltage protection circuit; and the second protection function module is an output overvoltage protection circuit and/or an output undervoltage protection circuit.
In an embodiment of the present invention, the first protection function module is an input under-voltage protection circuit, a current control voltage source is further coupled between the first switch and the first comparison circuit, a first input end of the current control voltage source is coupled to a second end of the first switch, a second input end and a first output end of the current control voltage source are respectively coupled to ground, and a second output end of the current control voltage source is coupled to a second input end of the first comparison circuit.
In an embodiment of the present invention, the second protection function module is an output overvoltage protection circuit, and the second protection function module further includes a current mirror, an input end of the current mirror is coupled to the second switch, and an output end of the current mirror is respectively coupled to the first current source and the first input end of the second comparison circuit.
In one embodiment of the invention, the control chip controls the first switch to be turned on in the primary winding excitation stage; and in the secondary winding degaussing stage, the control chip controls the second switch to be conducted.
In an embodiment of the invention, the primary side control circuit further includes a third resistor, a first end of the third resistor is coupled to the first end of the first resistor, and a second end of the third resistor is coupled to ground.
The invention discloses a power conversion circuit, which comprises a primary side circuit and a secondary side circuit, wherein the primary side circuit comprises a primary side control circuit.
The invention discloses a control method for a primary side control circuit, wherein the primary side control circuit comprises a control chip, the control chip comprises a multiplexing pin, and the multiplexing pin is coupled to an auxiliary winding through a resistor module in the primary side control circuit; the resistance module presents a first preset resistance value in a current loop of a primary winding excitation stage and presents a second preset resistance value in a current loop of a secondary winding demagnetizing stage, and the control method comprises the following steps:
In the primary winding excitation stage, a first detection signal representing a current signal flowing through a multiplexing pin is obtained, and a first control signal is output according to the first detection signal and a first reference signal to realize control of a first protection function, wherein the first control signal is used for controlling a main switching tube in a primary circuit; and
And in the secondary winding degaussing stage, acquiring a second detection signal representing a current signal flowing through the multiplexing pin, and outputting a second control signal according to the second detection signal and a second reference signal to realize control of a second protection function, wherein the second control signal is used for controlling the main switching tube.
In an embodiment of the present invention, the control method further includes:
The method comprises the steps of adjusting a first preset resistance value of a resistance module in a primary winding excitation stage to adjust a first detection signal, so as to adjust a triggering reference of a first protection function; and/or
And adjusting a second preset resistance value of the resistance module in the secondary winding degaussing stage to adjust a second detection signal, thereby adjusting a triggering reference of a second protection function.
In one embodiment of the present invention, the resistor module includes a first resistor, a second resistor, and a first diode; the first end of the first resistor is coupled with the multiplexing pin, the second end of the first resistor is coupled with the auxiliary winding, the second resistor is connected with the first diode in series, and the second resistor and the first diode are connected between the first end and the second end of the first resistor in parallel; the control method further comprises the following steps:
Adjusting the resistance value of the first resistor and/or the second resistor to adjust a first preset resistance value, thereby adjusting a triggering reference of the first protection function; and/or
And adjusting the resistance value of the first resistor to adjust a second preset resistance value, thereby adjusting a trigger reference of the second protection function.
In one embodiment of the present invention, the first protection function is input under-voltage protection and/or input over-voltage protection; and the second protection function is output overvoltage protection and/or output undervoltage protection, wherein,
In the primary winding excitation stage, the first switch is controlled to be conducted so as to judge whether the first protection function is triggered or not; and
And in the secondary winding degaussing stage, controlling the second switch to be conducted so as to judge whether the second protection function is triggered or not.
The invention provides a primary side control circuit, a control method and a power conversion circuit. The resistor module presents a first preset resistance value in a current loop of the primary winding excitation stage, and presents a second preset resistance value in a current loop of the secondary winding degaussing stage. The control chip acquires a first detection signal representing a current signal flowing through the multiplexing pin in the primary winding excitation stage, and the first protection function module outputs a first control signal according to the first detection signal. In addition, in the secondary winding degaussing stage, the control chip acquires a second detection signal representing a current signal flowing through the multiplexing pin, and the second protection function module outputs a second control signal according to the second detection signal. The primary side control circuit, the control method and the power supply conversion circuit provided by the invention can realize the pin multiplexing of at least two protection functions, and can respectively adjust the trigger threshold parameters of each protection function according to application requirements.
Drawings
Fig. 1 shows a schematic diagram of a part of a circuit of a prior art power conversion circuit.
Fig. 2 shows a schematic circuit diagram of a primary side control circuit according to an embodiment of the invention.
Fig. 3 shows a schematic circuit diagram of a primary side control circuit according to another embodiment of the invention.
Fig. 4 shows a schematic diagram of a part of a circuit of a primary side control circuit according to another embodiment of the invention.
Fig. 5 shows a schematic diagram of a part of a circuit of a primary side control circuit according to another embodiment of the invention.
Fig. 6 shows a schematic diagram of a part of the circuit of a primary side control circuit according to a further embodiment of the invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.
The description of this section is intended to be illustrative of only a few exemplary embodiments and the invention is not to be limited in scope by the description of the embodiments. It is also within the scope of the description and claims of the invention to interchange some of the technical features of the embodiments with other technical features of the same or similar prior art.
"Coupled" or "connected" in the specification includes both direct and indirect connections. An indirect connection is a connection made through an intermediary, such as through an electrically conductive medium, which may have parasitic inductance or parasitic capacitance; indirect connections may also include connections through other active or passive devices, such as through circuits or components such as switches, follower circuits, and the like, that accomplish the same or similar functional objectives. The terms "first," "second," "third," and the like in the description are used for distinguishing between various technical features and not for defining the sequential or sub-sequential relationship of the technical features.
An embodiment of the invention discloses a primary side control circuit, which is used for primary side control of a power supply conversion circuit. The power conversion circuit comprises a primary side circuit, a secondary side circuit and a transformer, wherein the primary side circuit comprises a primary side control circuit and a main switching tube, and the primary side control circuit controls the working state of the main switching tube so as to control the output voltage and/or the output current. The transformer includes a primary winding and a secondary winding. In order to ensure that the power conversion circuit can normally and stably work, a circuit module with a protection function is further arranged in the primary side control circuit, when the circuit is abnormal, a protection mechanism (such as outputting a protection signal) is triggered, and at the moment, the primary side control circuit outputs a control signal to a control end of the main switching tube to enable the main switching tube to be in an off state so as to avoid damage of the power conversion circuit.
In an embodiment of the present invention, as shown in fig. 2, the primary side control circuit further includes a control chip 100, where the control chip 100 includes a multiplexing pin DEM, a first protection function module, and a second protection function module. The multiplexing pin DEM is coupled to a first terminal of the auxiliary winding AUX through a resistor module 200 in the primary control circuit, and a second terminal of the auxiliary winding AUX is coupled to ground. The resistor module 200 has a first preset resistance value in the current loop of the primary winding excitation stage and a second preset resistance value in the current loop of the secondary winding degaussing stage. As shown in fig. 2, in a specific embodiment, the resistor module 200 includes a first resistor R1, a second resistor R2, and a first diode D1. The first end of the first resistor R1 is coupled to the multiplexing pin DEM, the second end of the first resistor R1 is coupled to the auxiliary winding AUX, the second resistor R2 is connected in series with the first diode D1, and the second resistor R2 and the first diode D1 are connected in parallel between the first end and the second end of the first resistor R1. In the primary winding excitation phase, the current flows from the multiplexing pin DEM to the auxiliary winding AUX in the current loop in which the resistor module 200 is located. At this time, the control chip 100 obtains a first detection signal representing the current signal flowing through the multiplexing pin DEM, and the first protection function module outputs a first control signal according to the first detection signal, where the first control signal is used to control the main switching tube in the primary side circuit. In the secondary winding degaussing phase, the current in the current loop in which the resistor module 200 is located flows from the auxiliary winding AUX to the multiplexing pin DEM. At this time, the control chip 100 obtains a second detection signal representing the current signal flowing through the multiplexing pin DEM, and the second protection function module outputs a second control signal according to the second detection signal, where the second control signal is used to control the main switching tube. In an embodiment of the present invention, the first protection function module is a protection circuit capable of obtaining a protection function detection signal in a primary winding excitation stage, and the second protection function module is a protection circuit capable of obtaining another protection function detection signal in a secondary winding demagnetization stage. In another embodiment of the present invention, the first protection function module is an input under-voltage protection circuit or an input over-voltage protection circuit, and the second protection function module is an output over-voltage protection circuit or an output under-voltage protection circuit. The primary side control circuit can realize the pin multiplexing of at least two protection functions and can respectively adjust the trigger threshold parameters of each protection function according to application requirements.
In an embodiment of the invention, the control chip includes a first protection function module and a second protection function module. The first protection function module is an input under-voltage protection circuit, and the second protection function module is an output over-voltage protection circuit. Based on the embodiment as shown in fig. 2, in the primary winding excitation stage, the first switch K1 is turned on, and at this time, the input undervoltage protection circuit works, and the current Ibop = Vbop/r1+ (Vbop-vf_d)/R2 flowing through the multiplexing pin, where Ibop may be a fixed detection threshold value built in the control chip, vbop is a terminal voltage of the multiplexing pin, R1 is a resistance value of the first resistor R1, vf_d is a voltage drop on the first diode D1, and R2 is a resistance value of the second resistor R2. In the secondary winding degaussing stage, the second switch K2 is turned on, and when the output overvoltage protection circuit works, there is vo_ ovp1 =r1× Iovp, where vo_ ovp1 is the terminal voltage of the multiplexing pin, and Iovp1 is another fixed detection threshold value built in the control chip. For the input undervoltage protection circuit, the equation Ibop = Vbop/r1+ (Vbop-vf_d)/R2 can be converted to the equation Vbop = (Ibop +vf_d/R2) (1/r1+1/R2), where Ibop can be a fixed detection threshold, vf_d is determined by the first diode, and the voltage drop of the first diode is relatively small in selection range. The triggering threshold value of the protection function of the input undervoltage protection circuit can be adjusted by adjusting the resistance values of the first resistor R1 and the second resistor R2. As for the output overvoltage protection circuit, as known from the formula vo_ ovp 1=r1× Iovp1, the triggering threshold of the protection function of the output overvoltage protection circuit is adjusted by adjusting the resistance value of the first resistor R1. From the above, by adjusting the resistance values of the first resistor R1 and the second resistor R2, for example, by replacing the first resistor R1 and the second resistor R2, the trigger threshold values of the two protection functions of the output overvoltage protection and the input undervoltage protection can be effectively controlled.
In an embodiment of the present invention, the first protection function module includes a first switch K1 and a first comparison circuit 110. The first end of the first switch K1 is coupled to the multiplexing pin DEM, the first input end of the first comparison circuit 110 receives the first reference signal bop_ref, the second input end of the first comparison circuit 110 is coupled to the second end of the first switch K1, and the output end of the first comparison circuit 110 is coupled to the main switch tube. The second protection function includes a second switch K2 and a second comparison circuit 130. The first end of the second switch K2 is coupled to the multiplexing pin DEM, the first input end of the second comparison circuit 130 is coupled to the second end of the second switch K2, the second input end of the second comparison circuit 130 receives the second reference signal ovp_ref, and the output end of the second comparison circuit 130 is coupled to the main switching tube. In a specific embodiment, the first comparator 110 is a first comparator, the non-inverting input terminal of the first comparator is coupled to the first reference signal terminal to receive the first reference signal bop_ref, the inverting input terminal of the first comparator is coupled to the first switch K1, and the output terminal of the first comparator is coupled to the main switch tube. The first comparator is used for comparing the first reference signal and the first detection signal and outputting a first control signal. When the first protection function module is an input under-voltage protection circuit, the first comparator outputs a first control signal BOP, and when the input under-voltage protection is triggered, the first control signal BOP is in a first state (such as high level), and the primary side control circuit controls the main switching tube to be turned off. After the control chip is turned off for a proper time, the control chip is restarted to work and the detection of the input undervoltage protection is performed again.
In an embodiment of the present invention, the first protection function is an input under-voltage protection circuit, and the current control voltage source 120 is further coupled between the first switch K1 and the first comparison circuit 110. The first input terminal of the current control voltage source 120 is coupled to the second terminal of the first switch K1, the second input terminal and the first output terminal of the current control voltage source 120 are respectively coupled to the ground, and the second output terminal of the current control voltage source 120 is coupled to the second input terminal of the first comparison circuit 110. In the primary winding excitation stage, when the current flowing through the multiplexing pin DEM increases, the voltage output by the current control voltage source 120 increases; as the current flowing through the multiplexing pin DEM decreases, the voltage output by the current control voltage source 120 decreases. In the embodiment shown in fig. 4, the first reference signal is a voltage Vbop _ref, and when the voltage output by the current control voltage source 120 is smaller than the voltage Vbop _ref, the BOP protection is triggered to control the main switch to be turned off.
In an embodiment of the invention, as shown in fig. 2, the second protection function module is an output overvoltage protection circuit, the output overvoltage protection circuit includes a second switch K2, a current mirror and a second comparison circuit 130, an input end of the current mirror is coupled to the second switch K2, and an output end of the current mirror is respectively coupled to an output end of the first current source I1 and a first input end of the second comparison circuit 130. A second input terminal of the second comparing circuit 130 is coupled to the second reference signal ovp_ref, and an output terminal of the second comparing circuit 130 outputs an OVP signal. The current mirror converts the received first current signal Iovp into a second current signal Iovp and outputs the second current signal to the second comparison circuit. The first current signal Iovp is proportional to the second current signal Iovp2, the proportional value being controlled by a current mirror. The current of the current mirror is regulated to meet the requirements of specific application scenes. In the secondary winding degaussing stage, the control chip 100 controls the second switch K2 to be turned on, and at this time, current flows from the auxiliary winding to the second comparison circuit through the multiplexing pin DEM. When the first current signal Iovp1 is smaller, the second current signal Iovp2 output by the current mirror to the second comparison circuit is also relatively smaller (lower than the second reference signal ovp_ref), so OVP protection is not triggered. When the first current signal Iovp a increases to a certain value, the second current signal Iovp a is greater than or equal to the second reference signal ovp_ref, the OVP protection will be triggered, and the primary side control circuit controls the main switching tube to be turned off. In order to avoid false triggering, a counting circuit can be arranged between the second comparison circuit and the main switching tube, and when the number of triggered OVP protection reaches a preset count value, the OVP protection is triggered.
In an embodiment of the present invention, as shown in fig. 3, the first protection function module is an input overvoltage protection circuit, and the second protection function module is an output undervoltage protection circuit. The input overvoltage protection circuit includes a first switch K1 and a first comparison circuit 111. The first end of the first switch K1 is coupled to the multiplexing pin DEM, the first input end of the first comparison circuit 111 receives the first reference signal INOVP _ref, the second input end of the first comparison circuit 111 is coupled to the second end of the first switch K1, and the output end of the first comparison circuit 111 is coupled to the main switch tube. In a specific embodiment, the first comparing circuit 111 is a first comparator, the non-inverting input terminal of the first comparator is coupled to the first switch K1, the inverting input terminal of the first comparator is coupled to the first reference signal terminal to receive the first reference signal INOVP _ref, and the output terminal of the first comparator is coupled to the main switch tube. The first comparator is used for comparing the first reference signal and the first detection signal and outputting a first control signal INOVP. When the input overvoltage protection is triggered, the first control signal INOVP is in a first state (such as a high level), and the primary side control circuit controls the main switching tube to be turned off. After the control chip is turned off for a proper time, the control chip is restarted and the input overvoltage protection is detected again. The first switch K1 and the first comparison circuit 111 are further coupled to a current control voltage source 121. The first input terminal of the current control voltage source 121 is coupled to the second terminal of the first switch K1, the second input terminal and the first output terminal of the current control voltage source 121 are respectively coupled to ground, and the second output terminal of the current control voltage source 121 is coupled to the non-inverting input terminal of the first comparator. The output undervoltage protection circuit comprises a second switch K2, a current mirror and a second comparison circuit 131, the second comparison circuit 131 comprises a second comparator, the input end of the current mirror is coupled with the second switch K2, and the output end of the current mirror is respectively coupled with the output end of the second current source I2 and the inverting input end of the second comparator. The non-inverting input end of the second comparator is coupled to the second reference signal UVP_ref, and the output end of the second comparator outputs a UVP signal. By adjusting the resistance values of the first resistor R1 and the second resistor R2, the trigger threshold values of the two protection functions of input overvoltage protection and output undervoltage protection can be effectively controlled.
In an embodiment of the invention, as shown in fig. 5, the second protection function module includes a second switch K2, a current mirror and a second comparison circuit 130, the second comparison circuit 130 is a second comparator, an input terminal of the current mirror is coupled to the second switch K2, and an output terminal of the current mirror is coupled to a non-inverting input terminal of the second comparator. The current mirror converts the received first current signal Iovp into a second current signal Iovp2, so that the non-inverting input end of the second comparator presents a voltage signal vo_ OVP2, the inverting input end of the second comparator is coupled with the reference voltage Vref1, and the second comparator outputs an OVP signal according to the voltage signal vo_ OVP2 and the reference voltage Vref1, thereby realizing overvoltage protection control. .
As shown in fig. 6, in an embodiment of the present invention, the first protection function module includes an input under-voltage protection circuit or an input over-voltage protection circuit. The input undervoltage protection circuit comprises a first comparison circuit 110, and the first comparison circuit 110 controls the switching state of the main switching tube according to the input undervoltage protection reference voltage Vbop _ref and a first detection signal, so that the input undervoltage protection of the power conversion circuit is realized. The input overvoltage protection circuit comprises a third comparison circuit 160, and the third comparison circuit 160 controls the switching state of the main switching tube according to the input overvoltage protection reference voltage Vinovp _ref and the first detection signal, so that the input overvoltage protection of the power supply conversion circuit is realized. In this embodiment, the multiplexing pin may implement multiplexing of three protection functions, and may effectively adjust trigger threshold parameters of at least two of the protection functions.
In an embodiment of the present invention, during the excitation phase of the primary winding, the control chip controls the first switch K1 to be turned on, so as to perform input undervoltage protection detection or input overvoltage protection detection. In the secondary winding degaussing stage, the control chip controls the second switch K2 to be conducted, so that output overvoltage protection detection or output undervoltage protection detection is performed.
In an embodiment of the invention, the primary side control circuit includes a resistor module and a third resistor, a first end of the third resistor is coupled to the resistor module, a second end of the third resistor is coupled to ground, and the third resistor is used as a voltage dividing resistor to reduce the voltage on the multiplexing pin. In another embodiment of the present invention, the resistor module includes a first resistor, a second resistor, and a first diode. The first end of the first resistor is coupled with the multiplexing pin, the second end of the first resistor is coupled with the auxiliary winding, the second resistor is connected with the first diode in series, and the second resistor and the first diode are connected between the first end and the second end of the first resistor in parallel. The first end of the third resistor is coupled to the first end of the first resistor, and the second end of the third resistor is coupled to ground.
The primary side control circuit is used for controlling the working state of the main switching tube, thereby controlling the output voltage and/or the output current so as to realize constant voltage output or constant current output of the power supply conversion circuit. In addition, the primary side control circuit is also used for performing circuit protection control of the voltage conversion circuit. In an embodiment of the present invention, the working state of the main switching tube is a switching state, and the output of the power conversion circuit is controlled by controlling the switching state of the main switching tube.
An embodiment of the invention discloses a control method for a primary side control circuit, wherein the primary side control circuit comprises a control chip, the control chip comprises a multiplexing pin, and the multiplexing pin is coupled to an auxiliary winding through a resistor module in the primary side control circuit. The resistor module presents a first preset resistance value in a current loop of the primary winding excitation stage, and presents a second preset resistance value in a current loop of the secondary winding degaussing stage. The control method of the primary side control circuit comprises the following steps:
In the primary winding excitation stage, a control chip acquires a first detection signal representing a current signal flowing through a multiplexing pin, and outputs a first control signal according to the first detection signal and a first reference signal to realize control of a first protection function, wherein the first control signal is used for controlling a main switching tube in a primary circuit; and
In the secondary winding degaussing stage, the control chip acquires a second detection signal representing a current signal flowing through the multiplexing pin, and outputs a second control signal according to the second detection signal and a second reference signal to realize control of a second protection function, wherein the second control signal is used for controlling a main switching tube in the primary circuit.
In an embodiment of the present invention, the control method further includes:
The method comprises the steps of adjusting a first preset resistance value of a resistance module in a primary winding excitation stage to adjust a first detection signal, so as to adjust a triggering reference of a first protection function; and/or
And adjusting a second preset resistance value of the resistance module in the secondary winding degaussing stage to adjust a second detection signal, thereby adjusting a triggering reference of a second protection function.
In an embodiment of the invention, the resistor module includes a first resistor, a second resistor and a first diode; the first end of the first resistor is coupled with the multiplexing pin, the second end of the first resistor is coupled with the auxiliary winding, the second resistor is connected with the first diode in series, and the second resistor and the first diode are connected between the first end and the second end of the first resistor in parallel; the control method further comprises the following steps:
Adjusting the resistance value of the first resistor and/or the second resistor to adjust a first preset resistance value, thereby adjusting a triggering reference of the first protection function; and/or
And adjusting the resistance value of the first resistor to adjust a second preset resistance value, thereby adjusting a trigger reference of the second protection function.
In an embodiment of the present invention, the first protection function is input under-voltage protection or input over-voltage protection; and the second protection function is output overvoltage protection or output undervoltage protection, wherein in the excitation stage of the primary winding, the first switch is controlled to be conducted so as to judge whether the first protection function is triggered or not. And in the secondary winding degaussing stage, controlling the second switch to be conducted so as to judge whether the second protection function is triggered or not.
The invention provides a primary side control circuit, a control method and a power conversion circuit. The resistor module presents a first preset resistance value in a current loop of the primary winding excitation stage, and presents a second preset resistance value in a current loop of the secondary winding degaussing stage. In the primary winding excitation stage, a control chip acquires a first detection signal representing a current signal flowing through a multiplexing pin, and a first protection function module outputs a first control signal according to the first detection signal, wherein the first control signal is used for controlling a main switching tube in a primary circuit. In addition, in the secondary winding degaussing stage, the control chip acquires a second detection signal representing a current signal flowing through the multiplexing pin, and the second protection function module outputs a second control signal according to the second detection signal, wherein the second control signal is used for controlling the main switching tube. The primary side control circuit, the control method and the power supply conversion circuit provided by the invention can realize the pin multiplexing of at least two protection functions, and can respectively adjust the trigger threshold parameters of each protection function according to application requirements.
The description and applications of the present invention herein above are illustrative and are not intended to limit the scope of the invention to the embodiments described above. The relevant descriptions of effects or advantages and the like related to the embodiments may not be embodied in experimental examples due to uncertainty of specific condition parameters, and are not intended to limit the embodiments. Variations and modifications of the embodiments disclosed herein are possible, and alternatives and equivalents of the various components of the embodiments are known to those of ordinary skill in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other assemblies, materials, and components, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.
Claims (10)
1. A primary side control circuit for primary side control of a power conversion circuit, the primary side control circuit comprising a control chip, characterized in that the control chip comprises a multiplexing pin, a first protection function module and a second protection function module, the multiplexing pin is coupled to an auxiliary winding through a resistor module in the primary side control circuit; the resistor module presents a first preset resistance value in a current loop of a primary winding excitation stage, and presents a second preset resistance value in a current loop of a secondary winding demagnetizing stage; wherein,
In the primary winding excitation stage, the control chip acquires a first detection signal representing a current signal flowing through the multiplexing pin, and the first protection function module outputs a first control signal according to the first detection signal; the first control signal is used for controlling a main switching tube in the primary circuit; and
In the secondary winding degaussing stage, the control chip acquires a second detection signal representing a current signal flowing through the multiplexing pin, and the second protection function module outputs a second control signal according to the second detection signal; the second control signal is used for controlling the main switching tube;
The first protection function module comprises a first switch and a first comparison circuit; a first end of the first switch is coupled with a multiplexing pin; the first input end of the first comparison circuit is coupled with a first reference signal end, the second input end of the first comparison circuit is coupled with the second end of the first switch, and the output end of the first comparison circuit is coupled with the main switch tube; and
The second protection function module comprises a second switch and a second comparison circuit; the first end of the second switch is coupled with a multiplexing pin; the first input end of the second comparison circuit is coupled with the second end of the second switch, the second input end of the second comparison circuit is coupled with the second reference signal end, and the output end of the second comparison circuit is coupled with the main switch tube;
The first protection function module is an input undervoltage protection circuit, a current control voltage source is further coupled between the first switch and the first comparison circuit, a first input end of the current control voltage source is coupled with a second end of the first switch, a second input end and a first output end of the current control voltage source are respectively coupled with the ground, and a second output end of the current control voltage source is coupled with a second input end of the first comparison circuit; the second protection function module is an output overvoltage protection circuit, and further comprises a current mirror, wherein the input end of the current mirror is coupled with the second switch, and the output end of the current mirror is respectively coupled with the first current source and the first input end of the second comparison circuit.
2. The primary side control circuit of claim 1, wherein the resistor module comprises a first resistor, a second resistor, and a first diode; the first end of the first resistor is coupled with the multiplexing pin, the second end of the first resistor is coupled with the auxiliary winding, the second resistor is connected with the first diode in series, and the second resistor and the first diode are connected between the first end and the second end of the first resistor in parallel.
3. The primary side control circuit of claim 1, wherein the first protection function module is an input under-voltage protection circuit and/or an input over-voltage protection circuit; and the second protection function module is an output overvoltage protection circuit and/or an output undervoltage protection circuit.
4. The primary side control circuit of claim 1, wherein the control chip controls the first switch to conduct during a primary side winding excitation phase; and in the secondary winding degaussing stage, the control chip controls the second switch to be conducted.
5. The primary side control circuit of claim 2, further comprising a third resistor, a first terminal of the third resistor coupled to the first terminal of the first resistor, and a second terminal of the third resistor coupled to ground.
6. A power conversion circuit comprising a primary side circuit and a secondary side circuit, wherein the primary side circuit comprises a primary side control circuit as claimed in any one of claims 1 to 5.
7. A control method for the primary side control circuit of any one of claims 1-5, the primary side control circuit comprising a control chip, characterized in that the control chip comprises a multiplexing pin coupled to an auxiliary winding through a resistive module in the primary side control circuit; the resistance module presents a first preset resistance value in a current loop of a primary winding excitation stage and presents a second preset resistance value in a current loop of a secondary winding demagnetizing stage, and the control method comprises the following steps:
In the primary winding excitation stage, a first detection signal representing a current signal flowing through the multiplexing pin is obtained, and a first control signal is output according to the first detection signal and a first reference signal to realize control of a first protection function, wherein the first control signal is used for controlling a main switching tube in a primary circuit; and
And in the secondary winding degaussing stage, acquiring a second detection signal representing the current signal flowing through the multiplexing pin, and outputting a second control signal according to the second detection signal and a second reference signal to realize control of a second protection function, wherein the second control signal is used for controlling the main switching tube.
8. The control method according to claim 7, characterized in that the control method further comprises:
Adjusting a first preset resistance value of the resistance module in a primary winding excitation stage to adjust a first detection signal, thereby adjusting a triggering reference of a first protection function; and/or
And adjusting a second preset resistance value of the resistance module in the secondary winding degaussing stage to adjust a second detection signal, so as to adjust a triggering reference of a second protection function.
9. The control method of claim 8, wherein the resistor module comprises a first resistor, a second resistor, and a first diode; the first end of the first resistor is coupled with the multiplexing pin, the second end of the first resistor is coupled with the auxiliary winding, the second resistor is connected with the first diode in series, and the second resistor and the first diode are connected between the first end and the second end of the first resistor in parallel; the control method further includes:
adjusting the resistance value of the first resistor and/or the second resistor to adjust a first preset resistance value, thereby adjusting a triggering reference of the first protection function; and/or
And adjusting the resistance value of the first resistor to adjust a second preset resistance value, so as to adjust a trigger reference of the second protection function.
10. The control method according to claim 7, wherein the first protection function is an under-input voltage protection and/or an over-input voltage protection; and the second protection function is output overvoltage protection and/or output undervoltage protection, wherein,
In the primary winding excitation stage, the first switch is controlled to be conducted so as to judge whether the first protection function is triggered or not; and
And in the secondary winding degaussing stage, controlling the second switch to be conducted so as to judge whether the second protection function is triggered or not.
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| CN114024429B (en) * | 2021-10-27 | 2024-02-20 | 成都芯源系统有限公司 | Power supply chip with multiplexing pins |
| CN115603283B (en) * | 2022-11-21 | 2023-03-21 | 珠海智融科技股份有限公司 | Flyback protection circuit |
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| CN110265971A (en) * | 2019-07-25 | 2019-09-20 | 杭州必易微电子有限公司 | Control circuit and chip |
| CN214314538U (en) * | 2021-01-07 | 2021-09-28 | 深圳市必易微电子股份有限公司 | Primary side control circuit and power conversion circuit |
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| TWI513163B (en) * | 2014-04-11 | 2015-12-11 | Power Forest Technology Corp | Flyback-based power conversion apparatus |
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| CN102820764A (en) * | 2012-09-11 | 2012-12-12 | 成都芯源系统有限公司 | control circuit, switching converter and control method thereof |
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