CN117155101B - Discharge control circuit and method for X capacitor and switching power supply - Google Patents
Discharge control circuit and method for X capacitor and switching power supply Download PDFInfo
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- CN117155101B CN117155101B CN202311421150.5A CN202311421150A CN117155101B CN 117155101 B CN117155101 B CN 117155101B CN 202311421150 A CN202311421150 A CN 202311421150A CN 117155101 B CN117155101 B CN 117155101B
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- 239000003990 capacitor Substances 0.000 title claims abstract description 149
- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000007599 discharging Methods 0.000 claims abstract description 41
- 238000001514 detection method Methods 0.000 claims abstract description 19
- 238000005070 sampling Methods 0.000 claims description 9
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
- H02M1/322—Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/10—Measuring sum, difference or ratio
Abstract
The application discloses a discharge control circuit, a method and a switching power supply for an X capacitor, wherein the discharge control circuit comprises an alternating current detection unit and a discharge control unit. The alternating current detection unit is used for judging the input state of the alternating current power supply according to the variation of the voltage difference value between the two ends of the X capacitor in a preset time period. The discharging control unit is used for outputting the electric energy stored by the X capacitor to a controller power supply circuit when the working circuit is disconnected from the alternating current power supply so as to discharge the X capacitor. The controller power supply circuit is also used for providing a working power supply V for the discharge control unit after acquiring the electric energy stored in the X capacitor CC . The alternating current power supply input state is judged according to the variation of the voltage difference value between the two ends of the X capacitor in a preset time period, so that the alternating current power supply input state is judged more accurately and more quickly by judging the alternating current power supply input front end of the working circuit. In addition, the controller power supply circuit is adopted to discharge the electric energy stored in the X capacitor, so that the X capacitor discharge process is safer and more reliable.
Description
Technical Field
The invention relates to the technical field of power electronic converters, in particular to a discharge control circuit and method for an X capacitor and a switching power supply.
Background
The full name of X capacitance is generally called: x2 (X1/X3/MKP) suppresses electromagnetic interference of power supply. The common function in the circuit is mainly used in power supply filtering, plays a role in power supply filtering and plays a role in filtering differential mode interference. The X capacitor is mainly aimed at an action power supply line crossing circuit, an EMI filter, a spark eliminating circuit and the like to ensure that finished products of electronic products meet EMC requirements.
In practical circuits, the X capacitance is generally no lower than the uF level, and a large amount of charge is stored in the X capacitance. After the equipment adopting the X capacitor is separated from the power supply connection of the power grid, the X capacitor is connected across the phase line to enable high voltage to be carried between the power plugs of the equipment, and if a human body accidentally touches the power plugs, a discharging loop is formed, so that the electric shock danger exists. For the danger of charging the plug, it is specified in the national standard GB 4943.1-2011, 2.1.1.7, that the discharge time constant of the type A pluggable device (such as a power adapter and the like) must not exceed 1s, and the residual voltage of the capacitor must not exceed 37% of the initial value after discharging for 1 s. In order to meet the national standard, a discharge circuit is usually connected in parallel to the X capacitor, and the discharge is usually performed by a resistor in the discharge circuit. However, the discharge resistor also generates power consumption when the circuit works normally, so that the efficiency of the whole circuit is reduced, and more electric energy is wasted. Therefore, how to discharge the X capacitor according with the safety certification requirement and simultaneously make the discharge circuit generate as little power consumption as possible when the circuit works normally is still a technical problem to be solved.
Disclosure of Invention
The application mainly solves the technical problem of how to reduce the power consumption of the X capacitor discharging circuit when the circuit works normally.
According to a first aspect, in one embodiment, a discharge control circuit for an X capacitor is provided, where the discharge control circuit obtains, through a capacitor power-taking circuit, electric energy of the X capacitor Xcap from a working circuit of the X capacitor Xcap, so as to discharge the X capacitor Xcap when the working circuit disconnects an ac power supply;
the capacitor power taking circuit comprises a first connecting end, a second connecting end and a third connecting end, the first connecting end and the second connecting end of the capacitor power taking circuit are respectively connected with two ends of the X capacitor Xcap, and the third connecting end of the capacitor power taking circuit is connected with the discharge control circuit;
the discharge control circuit comprises an alternating current detection unit and a discharge control unit;
the alternating current detection unit is connected with the third connecting end of the capacitor power taking circuit and is used for judging the alternating current power supply input state of the working circuit according to the variation of the voltage difference value of the two ends of the X capacitor Xcap output by the capacitor power taking circuit in a preset time period;
the discharging control unit is connected with the third connecting end of the capacitor power taking circuit and is used for outputting the electric energy stored by the X capacitor Xcap to a controller power supply circuit when the working circuit is disconnected from an alternating current power supply so as to discharge the X capacitor Xcap; the controller power supply circuit is also used for providing a working power supply V for the discharge control unit after acquiring the electric energy stored by the X capacitor Xcap CC 。
In one embodiment, the capacitive power-taking circuit further includes two rectifying diodes and a sampling resistor R HV The method comprises the steps of carrying out a first treatment on the surface of the The anodes of the two rectifying diodes are respectively connected with a first connecting end and a second connecting end of the capacitance power taking circuit, and the sampling resistor R HV One end of the rectifier diode is connected with the third connecting end of the capacitor power taking circuit, and the other end of the rectifier diode is connected with the cathodes of the two rectifier diodes.
In an embodiment, the determining, by the ac detection unit, the ac power input state of the working circuit according to the variation of the voltage difference between two ends of the X capacitor Xcap in the preset time period includes:
and judging the input state of the alternating current power supply of the working circuit according to whether the duration time of keeping the high potential and/or the low potential of the voltage difference value at the two ends of the X capacitor Xcap within the preset unit time delta t is a preset interval threshold value.
In an embodiment, the ac detection unit includes a first switch circuit S1, a second switch circuit S2, a first operational amplifier, a first comparator, a first timing module, a timer start control module, a second timing module, and a time variation setting module;
one end of the first switch circuit S1 is connected with the third connecting end of the capacitor circuit, and the other end of the first switch circuit S1 is connected with the negative input end of the first operational amplifier;
one end of the second switching circuit S2 is connected with the negative input end of the first operational amplifier, and the other end of the second switching circuit S2 is connected with the positive input end of the first operational amplifier;
the output end of the first operational amplifier is connected with the positive input end of the first comparator;
the negative input end of the first comparator is used for inputting a preset first reference voltage signal Vref1, the positive output end of the first comparator is connected with the time variation setting module, and the reverse output end of the first comparator is connected with the first timing module;
the first timing module is connected with the timer starting control module and is used for timing the duration time of the high-level signal when the first comparator outputs the high-level signal, and outputting a timing completion first signal to the timer starting control module when the duration time of the high-level signal is in a first preset time range;
the timer starting control module is connected with the second timing module and is used for sending a timing starting signal to the second timing module when the timing completion first signal is received, and stopping sending the timing starting signal to the second timing module when the timing completion first signal is not received;
the second timing module is connected with the time variation setting module and is used for timing the duration of the received timing starting signal, outputting a timing completion second signal to the time variation setting module when the duration of the timing starting signal is within a second preset time range, and sending a discharge starting signal to the discharge control unit when the duration of the timing starting signal is not within the second preset time range so as to be used for the discharge control unit to respond to the discharge starting signal to discharge the X capacitor Xcap;
the time variation setting module is connected with the first switch circuit S1 and the second switch circuit S2, and is configured to control the switch states of the first switch circuit S1 and the second switch circuit S2 according to a preset unit time timer control logic when receiving the high level output by the forward output end of the first comparator and/or the timing completion second signal output by the second timing module.
In one embodiment, the unit time timer control logic includes:
turning on the first switching circuit S1 and turning off the second switching circuit S2 in a first preset unit time period;
when the first timing module outputs the timing completion first signal, the first switching circuit S1 is disconnected and the second switching circuit S2 is conducted in a second preset unit time period;
when the second timing module outputs the second timing completion second signal, the first switching circuit S1 is turned off and the second switching circuit S2 is turned off in a third preset unit time period.
In one embodiment, the discharge control unit includes a second comparator, a third switch circuit S3 and a fourth switch circuit S4;
one end of the third switch circuit S3 is connected with a third connecting end of the capacitor power taking circuit, and the other end of the third switch circuit S is connected with the controller power supply circuit;
one end of the fourth switch circuit S4 is connected with the controller power supply circuit, and the other end of the fourth switch circuit S is grounded;
the enabling control end of the second comparator is connected with the second timing module;
the negative input end of the second comparator is connected with the controller power supply circuit and is used for working power supply V output by the controller power supply circuit CC Is input to the computer;
the positive input end of the second comparator is input with a preset second reference voltage signal Vref 2;
the positive output end of the second comparator is connected with the third switch circuit S3, and the negative output end of the second comparator is connected with the fourth switch circuit S4; the second comparator is configured to, when receiving the discharge start signal output by the second timing module, output a voltage according to the operating power V CC And the comparison result of the second reference voltage signal Vref2 controls the third switching circuit S3 and the fourth switching circuit S4 to be turned on or off.
In one embodiment, the second comparator is based on the operating power V CC And the comparison result of the second reference voltage signal Vref2 controls theThe turning on or off of the third switching circuit S3 and the fourth switching circuit S4 includes:
when the working power supply V CC Turning on the third switch circuit S3 and turning off the fourth switch circuit S4 when the second reference voltage signal Vref2 is greater than the first reference voltage signal Vref 2;
and/or when the working power supply V CC The third switch circuit S3 is turned off and the fourth switch circuit S4 is turned on when the second reference voltage signal Vref2 is not greater.
In one embodiment, the controller power supply circuit includes a power supply inductance L VCC Power supply capacitor V CC And rectifier diode D VCC ；
The power supply inductance L VCC One end of the rectifier diode D is grounded, and the other end of the rectifier diode D VCC Is connected with the positive electrode of the battery;
the rectifier diode D VCC The negative electrode of the battery is connected with the discharge control unit;
the power supply capacitor V CC Is connected to the discharge control unit, and the other end is grounded.
According to a second aspect, in an embodiment, a switching power supply is provided, which includes the discharge control circuit according to the first aspect, wherein the discharge control circuit is disposed in a circuit controller in the working circuit, and is connected to the controller power supply circuit through a VCC power supply pin of the circuit controller.
According to a third aspect, in one embodiment, there is provided a discharge control method for an X capacitor, for application to the discharge control circuit of the first aspect, the discharge control method including:
acquiring the variation of the voltage difference value between two ends of the X capacitor Xcap in a preset time period;
acquiring an alternating current power supply input state of a working circuit where the X capacitor Xcap is located according to the variable quantity in a preset time period;
when the working circuit cuts off an alternating current power supply, outputting the electric energy stored by the X capacitor Xcap to a controller power supply circuit so as to discharge the X capacitor Xcap;
when the working circuit is disconnected with the alternating current power supply and the working power supply V output by the controller power supply circuit CC When the voltage is larger than a preset reference voltage source, stopping discharging the X capacitor Xcap, and discharging the electric energy obtained by the power supply circuit of the controller;
when the working circuit is disconnected with the alternating current power supply and the working power supply V output by the controller power supply circuit CC And when the voltage is not greater than the reference voltage source, continuously outputting the electric energy stored by the X capacitor Xcap to the controller power supply circuit.
According to the discharge control method of the embodiment, the alternating current power supply input state is judged according to the variation of the voltage difference value between the two ends of the X capacitor in the preset time period, so that the alternating current power supply input state is judged more accurately and more quickly. In addition, the controller power supply circuit is adopted to intermittently discharge the electric energy stored in the X capacitor, so that the X capacitor discharge process is safer and more reliable.
Drawings
FIG. 1 is a schematic diagram of circuit connection of a discharge control circuit in an embodiment;
FIG. 2 is a schematic diagram showing the circuit connection of an AC power detecting unit according to one embodiment;
FIG. 3 is a flow control schematic of the unit time timer control logic in one embodiment;
FIG. 4 is a schematic diagram of circuit connection of a discharging control unit according to an embodiment;
FIG. 5 is a schematic diagram showing the circuit connection of the power supply circuit of the controller in one embodiment;
FIG. 6 is a schematic flow chart of a discharging control method in an embodiment;
FIG. 7 is a schematic diagram of a VHV waveform of an AC power input and off process of the operating circuit in one embodiment;
FIG. 8 is a schematic diagram of a logic control flow of a discharging control method in another embodiment;
FIG. 9 is a timing diagram of discharging X capacitor when AC is not multiplexed in one embodiment;
FIG. 10 is a timing diagram of discharging X capacitor when AC is multiplexed in one embodiment.
Detailed Description
The invention will be described in further detail below with reference to the drawings by means of specific embodiments. Wherein like elements in different embodiments are numbered alike in association. In the following embodiments, numerous specific details are set forth in order to provide a better understanding of the present application. However, one skilled in the art will readily recognize that some of the features may be omitted, or replaced by other elements, materials, or methods in different situations. In some instances, some operations associated with the present application have not been shown or described in the specification to avoid obscuring the core portions of the present application, and may not be necessary for a person skilled in the art to describe in detail the relevant operations based on the description herein and the general knowledge of one skilled in the art.
Furthermore, the described features, operations, or characteristics of the description may be combined in any suitable manner in various embodiments. Also, various steps or acts in the method descriptions may be interchanged or modified in a manner apparent to those of ordinary skill in the art. Thus, the various orders in the description and drawings are for clarity of description of only certain embodiments, and are not meant to be required orders unless otherwise indicated.
The numbering of the components itself, e.g. "first", "second", etc., is used herein merely to distinguish between the described objects and does not have any sequential or technical meaning. The terms "coupled" and "connected," as used herein, are intended to encompass both direct and indirect coupling (coupling), unless otherwise indicated.
Example 1
Referring to fig. 1, a schematic circuit connection diagram of a discharging control circuit in an embodiment is shown, wherein the discharging control circuit 30 obtains the electric energy of the X capacitor Xcap from the working circuit 1 of the X capacitor Xcap through the capacitor power-taking circuit 2, so as to be used for supplying the electric energy to the working circuit 1 when the ac power is disconnectedThe X capacitor Xcap discharges. The capacitor power taking circuit 2 comprises a first connecting end, a second connecting end and a third connecting end, the first connecting end and the second connecting end of the capacitor power taking circuit 2 are respectively connected with two ends of the X capacitor Xcap, and the third connecting end of the capacitor power taking circuit 2 is connected with the discharge control circuit 30. The discharge control circuit 30 includes an alternating current detection unit 31 and a discharge control unit 32. The ac detection unit 31 is connected to the third connection end of the capacitor power-taking circuit 2, and is configured to determine the ac power input state of the working circuit 1 according to the variation of the voltage difference between the two ends of the X capacitor Xcap output by the capacitor power-taking circuit 2 in the preset time period. The discharging control unit 32 is connected to the third connection terminal of the capacitor power taking circuit 2, and is configured to output the electric energy stored in the X capacitor Xcap to a controller power supply circuit 33 when the working circuit 1 disconnects the ac power supply, so as to discharge the X capacitor Xcap. The controller power supply circuit 33 is also used for providing the working power supply V for the discharge control unit 32 after obtaining the electric energy stored in the X capacitor Xcap CC . In one embodiment, the capacitive pick-up circuit 2 further includes two rectifying diodes and a sampling resistor R HV . The anodes of the two rectifier diodes are respectively connected with a first connecting end and a second connecting end of the capacitance sampling circuit 2, and the sampling resistor R HV One end of the capacitor power taking circuit 2 is connected with the third connecting end of the capacitor power taking circuit, and the other end of the capacitor power taking circuit is connected with the cathodes of the two rectifier diodes. In an embodiment, the ac detection unit 31 determines the ac power input state of the working circuit 1 according to the variation of the voltage difference across the X capacitor Xcap in the preset time period, and determines the ac power input state of the working circuit 1 according to whether the duration of the voltage difference across the X capacitor Xcap to maintain the high potential and/or the low potential within the preset unit time Δt is a preset interval threshold.
Referring to fig. 2, a schematic circuit diagram of an ac detection unit according to an embodiment is shown, in which the ac detection unit 31 includes a first switch circuit S1, a second switch circuit S2, a first operational amplifier, a first comparator, a first timing module 312, a timer start control module 313, a second timing module 314, and a time variation setting module 311. One end of the first switch circuit S1 is connected with the third connecting end of the capacitor electricity taking circuit 2, and the other end of the first switch circuit S1 is connected with the negative input end of the first operational amplifier. One end of the second switching circuit S2 is connected with the negative input end of the first operational amplifier, and the other end of the second switching circuit S2 is connected with the positive input end of the first operational amplifier. The output end of the first operational amplifier is connected with the positive input end of the first comparator. The negative input end of the first comparator is used for inputting a preset first reference voltage signal Vref1, the positive output end of the first comparator is connected with the time variation setting module 311, and the reverse output end of the first comparator is connected with the first timing module 312. The first timing module 312 is connected to the timer start control module, and is configured to, when the first comparator outputs the high level signal, time the duration of the high level signal, and when the duration of the high level signal is within a first predetermined time range, output a first signal to the timer start control module 313 after the time is completed. The timer start control module 313 is connected to the second timing module 314, and is configured to send a timing start signal to the second timing module 314 when the timing completion first signal is received, and stop sending the timing start signal to the second timing module 314 when the timing completion first signal is not received. The second timing module 314 is connected to the time variation setting module 311, and is configured to time the duration of the received timing start signal, output a timing completion second signal to the time variation setting module 311 when the duration of the timing start signal is within a second preset time range, and send a discharge start signal to the discharge control unit 32 when the duration of the timing start signal is not within the second preset time range, so that the discharge control unit 32 discharges the X capacitor Xcap in response to the discharge start signal. The time variation setting module 311 is connected to the first switch circuit S1 and the second switch circuit S2, and is configured to control the switch states of the first switch circuit S1 and the second switch circuit S2 according to a preset unit time timer control logic when receiving the high level output from the forward output end of the first comparator and/or the timing completion second signal output from the second timing module 314.
Referring to fig. 3, a flow control diagram of a unit time timer control logic in an embodiment is shown, and in an embodiment, the unit time timer control logic includes:
turning on the first switching circuit S1 and turning off the second switching circuit S2 in a first preset unit time period; when the first timing module outputs a timing completion first signal, the first switching circuit S1 is disconnected and the second switching circuit S2 is conducted in a second preset unit time period; when the second timing module outputs a second timing completion second signal, the first switching circuit S1 is turned off and the second switching circuit S2 is turned off in a third preset unit time period.
Referring to fig. 4, a schematic circuit diagram of a circuit connection of a discharge control unit in an embodiment, the discharge control unit 32 includes a second comparator, a third switch circuit S3 and a fourth switch circuit S4. One end of the third switch circuit S3 is connected to the third connection end of the capacitor power supply circuit 2, and the other end is connected to the controller power supply circuit 33. One end of the fourth switch circuit S4 is connected to the controller power supply circuit 33, and the other end is grounded. The enable control terminal En of the second comparator is connected to the second timing module 314. The negative input end of the second comparator is connected with the controller power supply circuit 33 and is used for operating power supply V output by the controller power supply circuit 33 CC Is input to the computer. The positive input end of the second comparator is input with a preset second reference voltage signal Vref 2. The positive output end of the second comparator is connected with the third switch circuit S3, and the negative output end of the second comparator is connected with the fourth switch circuit S4. The second comparator is used for receiving the discharge start signal output by the second timing module 314 according to the working power V CC The comparison result with the second reference voltage signal Vref2 controls the third switching circuit S3 and the fourth switching circuit S4 to be turned on or off. In one embodiment, the fourth switch circuit S4 is turned off when the third switch circuit S3 is turned on, and I is stopped when the controller power supply circuit is charged (X capacitor Xcap is discharged) VCC The current source discharges. In one embodiment, the fourth switch circuit S4 is turned on when the third switch circuit S3 is turned off, and the X capacitor Xcap is stopped from discharging when the controller power supply circuit is discharged. In one embodiment, the second comparator is based on the operating power V CC The comparison result with the second reference voltage signal Vref2 controls the third switching circuit S3 and the fourth switching circuit S4 to be turned on or off, including:
when working power supply V CC When the voltage is larger than the second reference voltage signal Vref2, the third switch circuit S3 is turned on and the fourth switch circuit S4 is turned off; and/or when the working power supply V CC When the voltage is not greater than the second reference voltage signal Vref2, the third switch circuit S3 is turned off and the fourth switch circuit S4 is turned on.
Referring to fig. 5, a schematic circuit diagram of a circuit connection of a controller power supply circuit in an embodiment, the controller power supply circuit 33 includes a power supply inductance L VCC Power supply capacitor V CC And rectifier diode D VCC . Power supply inductance L VCC One end of (B) is grounded and the other end is connected with a rectifier diode D VCC Is connected to the positive electrode of the battery. Rectifier diode D VCC Is connected with the discharge control unit. Power supply capacitor V CC One end of the power supply is connected with the discharge control unit, and the other end is grounded. In one embodiment, the power supply inductance L VCC The power-taking auxiliary winding of the circuit controller 3 in the working circuit 1.
An embodiment of the application also discloses a switching power supply, which comprises the discharge control circuit. Wherein the discharge control circuit 30 is provided in the circuit controller 3 in the working circuit 1 and is connected to the controller power supply circuit 33 through the VCC power supply pin of the circuit controller 3.
In an embodiment, the present application further discloses a discharge control method for an X capacitor, which is applied to the discharge control circuit described above, please refer to fig. 6, which is a schematic flow chart of a discharge control method in an embodiment, the discharge control method includes:
step 101, obtaining the variation.
And acquiring the variation of the voltage difference value between the two ends of the X capacitor Xcap in a preset time period.
Step 102, determining the input state of the ac power supply.
And acquiring the alternating current power supply input state of the working circuit where the X capacitor Xcap is positioned according to the variation in the preset time period.
Step 103, discharging the X capacitor.
When the working circuit cuts off the alternating current power supply, the electric energy stored by the X capacitor Xcap is output to a controller power supply circuit so as to discharge the X capacitor Xcap.
Step 104, discharging the controller power supply circuit.
When the working circuit is disconnected with the alternating current power supply and the controller power supply circuit outputs the working power supply V CC When the voltage is larger than a preset reference voltage source, the X capacitor Xcap is stopped from being discharged, and the electric energy obtained by the power supply circuit of the controller is discharged.
And step 105, recovering discharging the X capacitor.
When the working circuit is disconnected with the alternating current power supply and the controller power supply circuit outputs the working power supply V CC And when the power supply voltage is not greater than the reference voltage source, continuously outputting the electric energy stored by the X capacitor Xcap to the controller power supply circuit.
Repeating steps 103-105 until the X capacitor Xcap charges the power supply circuit of the controller to obtain a working power supply V CC The discharging of the X capacitor Xcap is not completed when the voltage is greater than the voltage of the preset reference voltage source.
Embodiments of the discharge control method disclosed in the present application are described below by way of specific examples.
Referring to fig. 7, a schematic view of VHV waveforms of an ac power input and turn-off process of a working circuit according to an embodiment shows waveform differences of the working circuit when an ac power source is connected and disconnected, and a stage of discharging an X capacitor is required when the ac power source is disconnected, so that determining that the stage of disconnecting the ac power source is the first technical problem to be solved by the present application is that the X capacitor is discharged, and another technical problem is that the X capacitor is discharged. The X capacitor discharging system detection circuit aims to reduce the complexity and cost of the X capacitor discharging system detection circuit, has the combination of an X capacitor discharging function and a balancing function of the system VCC voltage, and also needs to judge the strategy of the on-off state of an alternating current power supply in the discharging process.
Referring to fig. 8, a logic control flow diagram of a discharging control method in another embodiment is shown, wherein voltage differential sampling information at two ends of an X capacitor is sent to a first comparator to be compared with a set first reference voltage signal Vref1, if the first comparator outputs a high level, a reverse output end outputs a low level, a t time control logic (a unit time timer control logic is enabledEditing). If the first comparator outputs a low level, the inverted output terminal outputs a high level, and the first timer starts to count T1. The T1 timer is not complete and the Δt time control logic is still enabled. The T1 timing is completed, the X capacitance flag bit is high, the timing T2 is started, the T2 timing is not completed, and the second comparator is enabled. The second comparator compares the VCC voltage with the second reference voltage signal Vref2, if the output of the second comparator is high and the output of the reverse output end is low, the switch tube of the third switch circuit S3 is closed, I HV The controlled current source starts to work and gives C VCC The capacitor charges. When the output of the second comparator is low and the output of the reverse output terminal is high, the third switch circuit S3 is turned off, the fourth switch circuit S4 is turned on, I HV 、I VCC The controlled current source is operated to perform X capacitor discharge operation and so on until the T2 timer is completed, at which time the delta T time control logic is enabled and so on until V HV Voltage and VCC _UVLO And when the voltage is smaller than a set parameter, ending the discharge of the X capacitor.
Please refer to fig. 9 and 10, which are a timing waveform diagram of discharging the X capacitor when the ac is not multiplexed and a timing waveform diagram of discharging the X capacitor when the ac is multiplexed, respectively, in which V is the ordinate HV 、V CC 、V Ref1_hys 、V ref1 、VCC_UVLO、I HV And VG are respectively a high-voltage X capacitor sampling voltage value, a chip power supply voltage value, a first reference voltage hysteresis voltage value, a chip under-voltage protection voltage value, an X capacitor charging and discharging current value and a driving voltage value. Even if alternating current is multiplexed in the discharging process of the X capacitor, the discharging control method disclosed by the application can stop the discharging of the X capacitor in time.
The circuit structure and the judgment logic of the discharging control circuit for the X capacitor are simple, the sensitivity and the response speed of the discharging reaction of the X capacitor when the AC power supply is powered back at any time can be realized, in addition, the X capacitor is discharged through the power supply of the circuit controller, and the situation that the X capacitor is out of control due to power failure of the system is avoided in the discharging process of the X capacitor.
The discharge control circuit disclosed in the application comprises an alternating current detection unit and a discharge circuitAn electric control unit. The alternating current detection unit is used for judging the input state of the alternating current power supply according to the variation of the voltage difference value between the two ends of the X capacitor in a preset time period. The discharging control unit is used for outputting the electric energy stored by the X capacitor to a controller power supply circuit when the working circuit is disconnected from the alternating current power supply so as to discharge the X capacitor. The controller power supply circuit is also used for providing a working power supply V for the discharge control unit after acquiring the electric energy stored in the X capacitor CC . The alternating current power supply input state is judged according to the variation of the voltage difference value between the two ends of the X capacitor in a preset time period, so that the alternating current power supply input state is judged more accurately and more quickly by judging the alternating current power supply input front end of the working circuit. In addition, the controller power supply circuit is adopted to discharge the electric energy stored in the X capacitor, so that the X capacitor discharge process is safer and more reliable.
The foregoing description of the invention has been presented for purposes of illustration and description, and is not intended to be limiting. Several simple deductions, modifications or substitutions may also be made by a person skilled in the art to which the invention pertains, based on the idea of the invention.
Claims (8)
1. The discharging control circuit is characterized by acquiring the electric energy of the X capacitor Xcap from a working circuit of the X capacitor Xcap through a capacitor electricity acquisition circuit, and discharging the X capacitor Xcap when the working circuit is disconnected from an alternating current power supply;
the capacitor power taking circuit comprises a first connecting end, a second connecting end and a third connecting end, the first connecting end and the second connecting end of the capacitor power taking circuit are respectively connected with two ends of the X capacitor Xcap, and the third connecting end of the capacitor power taking circuit is connected with the discharge control circuit;
the discharge control circuit comprises an alternating current detection unit and a discharge control unit;
the alternating current detection unit is connected with the third connecting end of the capacitor power taking circuit and is used for judging the alternating current power supply input state of the working circuit according to the variation of the voltage difference value of the two ends of the X capacitor Xcap output by the capacitor power taking circuit in a preset time period;
the discharging control unit is connected with the third connecting end of the capacitor power taking circuit and is used for outputting the electric energy stored by the X capacitor Xcap to a controller power supply circuit when the working circuit is disconnected from an alternating current power supply so as to discharge the X capacitor Xcap; the controller power supply circuit is also used for providing a working power supply V for the discharge control unit after acquiring the electric energy stored by the X capacitor Xcap CC ；
The alternating current detection unit judges the alternating current power supply input state of the working circuit according to the variation of the voltage difference value between two ends of the X capacitor Xcap in a preset time period, and the alternating current power supply input state comprises the following steps:
judging the input state of the alternating current power supply of the working circuit according to whether the duration time of keeping the high potential and/or the low potential in the preset unit time delta t of the voltage difference value between the two ends of the X capacitor Xcap is a preset interval threshold value or not;
the alternating current detection unit comprises a first switch circuit S1, a second switch circuit S2, a first operational amplifier, a first comparator, a first timing module, a timer starting control module, a second timing module and a time variation setting module;
one end of the first switch circuit S1 is connected with the third connecting end of the capacitor circuit, and the other end of the first switch circuit S1 is connected with the negative input end of the first operational amplifier;
one end of the second switching circuit S2 is connected with the negative input end of the first operational amplifier, and the other end of the second switching circuit S2 is connected with the positive input end of the first operational amplifier;
the output end of the first operational amplifier is connected with the positive input end of the first comparator;
the negative input end of the first comparator is used for inputting a preset first reference voltage signal Vref1, the positive output end of the first comparator is connected with the time variation setting module, and the reverse output end of the first comparator is connected with the first timing module;
the first timing module is connected with the timer starting control module and is used for timing the duration time of the high-level signal when the first comparator outputs the high-level signal, and outputting a timing completion first signal to the timer starting control module when the duration time of the high-level signal is in a first preset time range;
the timer starting control module is connected with the second timing module and is used for sending a timing starting signal to the second timing module when the timing completion first signal is received, and stopping sending the timing starting signal to the second timing module when the timing completion first signal is not received;
the second timing module is connected with the time variation setting module and is used for timing the duration of the received timing starting signal, outputting a timing completion second signal to the time variation setting module when the duration of the timing starting signal is within a second preset time range, and sending a discharge starting signal to the discharge control unit when the duration of the timing starting signal is not within the second preset time range so as to be used for the discharge control unit to respond to the discharge starting signal to discharge the X capacitor Xcap;
the time variation setting module is connected with the first switch circuit S1 and the second switch circuit S2, and is configured to control the switch states of the first switch circuit S1 and the second switch circuit S2 according to a preset unit time timer control logic when receiving the high level output by the forward output end of the first comparator and/or the timing completion second signal output by the second timing module.
2. The discharge control circuit of claim 1 wherein said capacitive pick-up circuit further comprises two rectifier diodes and a sampling resistor R HV The method comprises the steps of carrying out a first treatment on the surface of the The anodes of the two rectifying diodes are respectively connected with a first connecting end and a second connecting end of the capacitance power taking circuit, and the sampling resistor R HV One end of the rectifier diode is connected with the third connecting end of the capacitor power taking circuit, and the other end of the rectifier diode is connected with the cathodes of the two rectifier diodes.
3. The discharge control circuit of claim 1 wherein the unit time timer control logic comprises:
turning on the first switching circuit S1 and turning off the second switching circuit S2 in a first preset unit time period;
when the first timing module outputs the timing completion first signal, the first switching circuit S1 is disconnected and the second switching circuit S2 is conducted in a second preset unit time period;
when the second timing module outputs the second timing completion second signal, the first switching circuit S1 is turned off and the second switching circuit S2 is turned off in a third preset unit time period.
4. The discharge control circuit of claim 1, wherein the discharge control unit comprises a second comparator, a third switching circuit S3, and a fourth switching circuit S4;
one end of the third switch circuit S3 is connected with a third connecting end of the capacitor power taking circuit, and the other end of the third switch circuit S is connected with the controller power supply circuit;
one end of the fourth switch circuit S4 is connected with the controller power supply circuit, and the other end of the fourth switch circuit S is grounded;
the enabling control end of the second comparator is connected with the second timing module;
the negative input end of the second comparator is connected with the controller power supply circuit and is used for working power supply V output by the controller power supply circuit CC Is input to the computer;
the positive input end of the second comparator is input with a preset second reference voltage signal Vref 2;
the positive output end of the second comparator is connected with the third switch circuit S3, and the negative output end of the second comparator is connected with the fourth switch circuit S4; the second comparator is configured to, when receiving the discharge start signal output by the second timing module, output a voltage according to the operating power V CC And the second reference voltage signal Vref2The comparison result controls the third switching circuit S3 and the fourth switching circuit S4 to be turned on or off.
5. The discharge control circuit of claim 4 wherein said second comparator is responsive to said operating power supply V CC And the comparison result of the second reference voltage signal Vref2 controls the third switching circuit S3 and the fourth switching circuit S4 to be turned on or off, including:
when the working power supply V CC Turning on the third switch circuit S3 and turning off the fourth switch circuit S4 when the second reference voltage signal Vref2 is greater than the first reference voltage signal Vref 2;
and/or when the working power supply V CC The third switch circuit S3 is turned off and the fourth switch circuit S4 is turned on when the second reference voltage signal Vref2 is not greater.
6. The discharge control circuit of claim 4 wherein the controller power supply circuit comprises a power supply inductance L VCC Power supply capacitor V CC And rectifier diode D VCC ；
The power supply inductance L VCC One end of the rectifier diode D is grounded, and the other end of the rectifier diode D VCC Is connected with the positive electrode of the battery;
the rectifier diode D VCC The negative electrode of the battery is connected with the discharge control unit;
the power supply capacitor V CC Is connected to the discharge control unit, and the other end is grounded.
7. A switching voltage source comprising a discharge control circuit according to any one of claims 1 to 6, wherein the discharge control circuit is provided in a circuit controller in the operating circuit and is connected to the controller power supply circuit via a VCC power supply pin of the circuit controller.
8. A discharge control method for an X capacitance, characterized by being applied to the discharge control circuit according to any one of claims 1 to 6, comprising:
acquiring the variation of the voltage difference value between two ends of the X capacitor Xcap in a preset time period;
acquiring an alternating current power supply input state of a working circuit where the X capacitor Xcap is located according to the variable quantity in a preset time period;
when the working circuit cuts off an alternating current power supply, outputting the electric energy stored by the X capacitor Xcap to a controller power supply circuit so as to discharge the X capacitor Xcap;
when the working circuit is disconnected with the alternating current power supply and the working power supply V output by the controller power supply circuit CC When the voltage is larger than a preset reference voltage source, stopping discharging the X capacitor Xcap, and discharging the electric energy obtained by the power supply circuit of the controller;
when the working circuit is disconnected with the alternating current power supply and the working power supply V output by the controller power supply circuit CC And when the voltage is not greater than the reference voltage source, continuously outputting the electric energy stored by the X capacitor Xcap to the controller power supply circuit.
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102545195A (en) * | 2012-03-16 | 2012-07-04 | 成都芯源系统有限公司 | EMI filter capacitor discharge circuit and discharge method |
| CN202661533U (en) * | 2012-07-16 | 2013-01-09 | 成都芯源系统有限公司 | Alternating voltage detection circuit and safety capacitor discharge circuit |
| EP2624422A2 (en) * | 2012-01-31 | 2013-08-07 | Canon Kabushiki Kaisha | Power source, power failure detection apparatus, and image forming apparatus |
| CN105119476A (en) * | 2015-09-17 | 2015-12-02 | 矽力杰半导体技术(杭州)有限公司 | X capacitor discharge control circuit used in switching power supply |
| JP2016171686A (en) * | 2015-03-13 | 2016-09-23 | 新電元工業株式会社 | Control circuit and switching power supply |
| CN111277130A (en) * | 2020-03-20 | 2020-06-12 | 苏州力生美半导体有限公司 | High-voltage starting circuit and method integrating zero-crossing detection and X capacitor discharge |
| CN113794185A (en) * | 2021-08-30 | 2021-12-14 | 西安鼎芯微电子有限公司 | High-voltage detection circuit for AC-DC converter |
| CN114008906A (en) * | 2019-09-13 | 2022-02-01 | 新电元工业株式会社 | Control circuit and power supply device |
| CN114614659A (en) * | 2022-02-17 | 2022-06-10 | 西安稳先半导体科技有限责任公司 | Discharge control circuit, chip, power supply and electronic device of X capacitor |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8471626B2 (en) * | 2009-08-12 | 2013-06-25 | System General Corp. | Start-up circuit to discharge EMI filter of power supplies |
| TWI464991B (en) * | 2011-08-31 | 2014-12-11 | Leadtrend Tech Corp | Circuit for discharging an x capacitor |
-
2023
- 2023-10-31 CN CN202311421150.5A patent/CN117155101B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2624422A2 (en) * | 2012-01-31 | 2013-08-07 | Canon Kabushiki Kaisha | Power source, power failure detection apparatus, and image forming apparatus |
| CN102545195A (en) * | 2012-03-16 | 2012-07-04 | 成都芯源系统有限公司 | EMI filter capacitor discharge circuit and discharge method |
| CN202661533U (en) * | 2012-07-16 | 2013-01-09 | 成都芯源系统有限公司 | Alternating voltage detection circuit and safety capacitor discharge circuit |
| JP2016171686A (en) * | 2015-03-13 | 2016-09-23 | 新電元工業株式会社 | Control circuit and switching power supply |
| CN105119476A (en) * | 2015-09-17 | 2015-12-02 | 矽力杰半导体技术(杭州)有限公司 | X capacitor discharge control circuit used in switching power supply |
| CN114008906A (en) * | 2019-09-13 | 2022-02-01 | 新电元工业株式会社 | Control circuit and power supply device |
| CN111277130A (en) * | 2020-03-20 | 2020-06-12 | 苏州力生美半导体有限公司 | High-voltage starting circuit and method integrating zero-crossing detection and X capacitor discharge |
| CN113794185A (en) * | 2021-08-30 | 2021-12-14 | 西安鼎芯微电子有限公司 | High-voltage detection circuit for AC-DC converter |
| CN114614659A (en) * | 2022-02-17 | 2022-06-10 | 西安稳先半导体科技有限责任公司 | Discharge control circuit, chip, power supply and electronic device of X capacitor |
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