CN109980954B - Switching power supply circuit - Google Patents
Switching power supply circuit Download PDFInfo
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- CN109980954B CN109980954B CN201910297762.5A CN201910297762A CN109980954B CN 109980954 B CN109980954 B CN 109980954B CN 201910297762 A CN201910297762 A CN 201910297762A CN 109980954 B CN109980954 B CN 109980954B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/003—Constructional details, e.g. physical layout, assembly, wiring or busbar connections
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2089—Modifications to facilitate cooling, ventilating, or heating for power electronics, e.g. for inverters for controlling motor
- H05K7/20909—Forced ventilation, e.g. on heat dissipaters coupled to components
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2089—Modifications to facilitate cooling, ventilating, or heating for power electronics, e.g. for inverters for controlling motor
- H05K7/20945—Thermal management, e.g. inverter temperature control
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- Dc-Dc Converters (AREA)
Abstract
A switching power supply circuit comprising: rectifier filter circuit, switch circuit, control circuit, supply circuit, main winding, transformer T1, output circuit, excess temperature protection circuit, output overvoltage crowbar, excess temperature protection circuit includes: cooling drive control circuit, it includes: the temperature-reducing power supply circuit comprises a thermistor RTH3, a driving resistor R220, a capacitor C220, a voltage stabilizing device SHR1, a switching tube Q122, a temperature-reducing power supply capacitor C221 and a capacitor C201; when the power supply temperature rises, the resistance value of the thermistor RTH3 is reduced, the voltage of the driving resistor R220 is increased, when the voltage is larger than the conducting voltage of the voltage stabilizing device SHR1, the C/A pin of the driving resistor is conducted, the B/E pin of the switching tube Q122 is caused to be conducted, the C/E pin of the driving resistor R is conducted, the capacitor C201 charges the capacitor C221 through the switching tube Q122, the smaller the resistance value of the thermistor RTH3 is, the higher the voltage of the capacitor C221 is, the larger the output power of the cooling device is, and the temperature is effectively reduced.
Description
Technical Field
The present invention relates to power supply circuits, and particularly to a switching power supply circuit.
Background
The power supply provides electrical energy to the electronic device while converting the electrical energy to heat. When the temperature of the power supply exceeds the allowable temperature, the output of the power supply will generate great drift, the efficiency is reduced, and even the power supply is burnt. How to ensure that the power supply works under a proper temperature condition or temperature environment is the key for ensuring the normal power supply of the power supply. Therefore, the heat dissipation design of the power supply is very important, and in the heat dissipation design process, the purpose of cooling is achieved by adopting a proper way to transfer heat out according to specific conditions, so that the working reliability of the power supply is improved, and the service life of the power supply is prolonged. Meanwhile, if the temperature of the power supply is too low, the working efficiency is influenced, the service life is influenced, and the charging and discharging are influenced.
Disclosure of Invention
Therefore, there is a need for a switching power supply circuit capable of regulating and cooling a power supply.
A switching power supply circuit comprising: the rectifier filter circuit, with the switch circuit of rectifier filter circuit connection, with the control circuit of switch circuit connection, with the supply circuit of control circuit connection, the primary side main winding of switch circuit connection, with the transformer T1 that the main winding corresponds sets up, set up in the output circuit of transformer T1 secondary side, set up in the excess temperature protection circuit of transformer T1 secondary side, with output circuit connection detect output voltage and feed back to the control circuit and carry out overvoltage protection's output overvoltage crowbar, the switch circuit sets up in the primary side of transformer T1, the control circuit includes: a master control unit, the output circuit comprising: the over-temperature protection circuit comprises a first secondary winding arranged on the secondary side of the transformer T1, an output rectifying and filtering circuit connected with the first secondary winding, and a load circuit arranged at the output end, wherein the over-temperature protection circuit comprises: insert the cooling supply circuit of heat sink, with cooling supply circuit connects and adjusts output voltage according to power temperature in order to adjust heat sink output's cooling drive control circuit, cooling supply circuit includes: a second secondary winding disposed on the secondary side of the transformer T1, a ramp-down rectifier-filter circuit connected to the second secondary winding, and a voltage regulator unit RG1 connected to the ramp-down rectifier-filter circuit, wherein the ramp-down rectifier-filter circuit includes: be connected with the heat sink and supply power for cooling drive control circuit or heat sink's filter capacitor C200, cooling drive control circuit includes: a thermistor RTH3 which is arranged corresponding to the power supply and detects the temperature or the temperature change of the power supply and causes the resistance value change according to the temperature change, a driving resistor R220 connected with the thermistor RTH3, a capacitor C220 which is connected in parallel with two ends of the driving resistor R220, a voltage stabilizing device SHR1 which is connected with the driving resistor R220 and conducts or not according to the voltage of two ends of the driving resistor R220, a switch tube Q122 which is connected with the voltage stabilizing device SHR1 and conducts according to the conduction of the voltage stabilizing device SHR1, a cooling power supply capacitor C221 which is connected with the switch tube Q122 and supplies power to a cooling device and causes the voltage change according to the resistance value change of the thermistor RTH3, and a capacitor C201 which is connected with the cooling power supply capacitor C221 and the switch tube Q122 and supplies power to the cooling power supply capacitor C221 through the switch tube Q, the capacitor C201 is connected to the output terminal of the voltage regulator RG1, and the thermistor RTH3 is connected in series with the driving resistor R220 and connected to two terminals of the capacitor C201.
In a preferred embodiment, a resistor R219 is further connected between the thermistor RTH3 and the driving resistor R220, the voltage regulator device SHR1 is a voltage regulator diode or a controllable voltage regulator source, the switching tube Q122 is a PNP-type triode Q122, a reference end of the voltage regulator device SHR1 is connected between the driving resistor R220 and the resistor R219, the capacitor C201 and the temperature-reducing power supply capacitor C221 are polar capacitors, an anode of the voltage regulator device SHR1 is connected to a cathode of the capacitor C201, a cathode of the voltage regulator device SHR1 is connected to a base of the triode Q122 through a resistor R223, a collector of the triode Q122 is connected to an anode of the temperature-reducing power supply capacitor C221, an emitter of the triode Q122 is connected to an anode of the capacitor C201, a cathode of the temperature-reducing power supply capacitor C221 is connected to a cathode of the capacitor C201, a resistor R222 is arranged between a base and an emitter of the triode Q122, a branch of the collector of the triode Q122 is connected to a position between the driving resistor R220 and the resistor R219, a branch is led out between the resistor R219 and the thermistor RTH3 and is connected into the output overvoltage protection circuit through a voltage regulator tube ZD 153.
In a preferred embodiment, the output overvoltage protection circuit includes: a voltage regulator tube or a voltage regulator tube group connected with the output circuit, a diode D150 connected with the voltage regulator tube or the voltage regulator tube group, and a photoelectric coupler U3 connected with the diode D150 and receiving an overvoltage signal for conduction, wherein the photoelectric coupler U3 comprises: the light emitting diode U3B is arranged at the emitting end and is connected with a voltage stabilizing tube or a voltage stabilizing tube group of the output overvoltage protection circuit, and the phototriode U3A is arranged corresponding to the light emitting diode U3B, receives the detection signal of the light emitting diode U3B, and transmits the detection signal to the main control unit so as to carry out overvoltage protection on the main control unit.
In a preferred embodiment, the output overvoltage protection circuit further comprises: a unidirectional silicon controlled triode SCR1 connected with the phototriode U3A, a resistor R64 connected with the unidirectional silicon controlled triode SCR1, and a resistor R65 connected in parallel with the resistor R64, wherein the control electrode of the unidirectional silicon controlled triode SCR1 is connected to the emitter of the phototriode U3A and is conducted according to the conduction of the phototriode U3A, the other ends of the resistor R64 and the resistor R65 connected in parallel are connected to the power supply end of the main control unit, the cathode of the unidirectional silicon controlled triode SCR1 is grounded, the anode of the unidirectional silicon controlled triode SCR1 is connected to the resistor R64, the emitter of the phototriode U3A is grounded through the resistor R66, the collector of the unidirectional silicon controlled triode SCR1 is connected to the power supply end of the main control unit through the resistor R58; the voltage regulator tube or the voltage regulator tube group of the output overvoltage protection circuit comprises: the LED driving circuit comprises series-connected Zener diodes ZD150 and ZD151, wherein the cathode of the Zener diode ZD150 is connected to the anode of the output circuit, the cathode of the ZD151 is connected to the anode of the Zener diode ZD150, the anode of the diode D150 is connected to the anode of the ZD151, the cathode of the diode D150 is connected to the anode of the LED U3B through a resistor R150, the cathode of the LED U3B is connected to the cathode of a capacitor C201, and a resistor R151 and a capacitor C150 are arranged at two ends of the LED U3B in parallel; the cooling rectification filter circuit includes: the output circuit comprises a diode D200 connected with the second secondary winding, a capacitor C202 and a resistor R207 which are arranged at two ends of the diode D200 and connected in series, a resistor R208 connected with a negative electrode of the diode D200, and a resistor R209 connected in parallel with two ends of the resistor R208, wherein a common end of the resistor R208 and the resistor R209 is connected to an anode of the filter capacitor C200, a negative electrode of the filter capacitor C200 is connected to the other end of the second secondary winding and grounded, one end of the resistor R208 connected with an anode of the filter capacitor C200 is connected to an input end of a voltage stabilizing unit RG1, a ground end of the voltage stabilizing unit RG1 is grounded, and an anode of an output end of the output circuit is connected to an input end of a voltage stabilizing unit RG.
In a preferred embodiment, further comprising: an output detection feedback circuit connected to the output circuit and detecting an output voltage or current to feed back to the main control unit for constant current protection or constant voltage output, the output detection feedback circuit including: detect output circuit's output voltage or current's detecting element U100, with output circuit connects and inserts among detecting element U100 with detecting element U100 cooperation detection output circuit output current's current sampling resistance, with output circuit's output is connected and inserts among detecting element U100 with detecting element U100 cooperation carry out the divider resistance circuit that output voltage detected, with the optoelectronic coupler U2 that amplifier U100 output is connected, detecting element U100 includes: an amplifier U100A connected to a voltage dividing resistor circuit of the output detection feedback circuit, comparing and judging the divided voltage of the voltage dividing resistor circuit with a reference voltage, and feeding back the result to the control circuit through a photocoupler U2, and an amplifier U100B connected to a current sampling resistor of the output detection feedback circuit, detecting the output current or current change of the output circuit, wherein an inverting input terminal of the amplifier U100A is connected to the reference voltage, a non-inverting input terminal thereof is connected to the divided voltage of the voltage dividing resistor circuit connected thereto, an output current of the output circuit is connected to the inverting input terminal of the amplifier U100B through the current sampling resistor, and is connected to the non-inverting input terminal thereof through a capacitor C510 and is grounded, and the photocoupler U2 includes: the light emitting diode U2B is arranged at a transmitting end, is connected with the output end of the amplifier U100A or the output end of the amplifier U100B and causes current change according to the change of output voltage, and the phototriode U2A is arranged at a receiving end, receives the detection signal of the light emitting diode U2B and transmits the detection signal to the main control unit so that the main control unit adjusts the output voltage according to the detection signal to output constant current or constant voltage.
In a preferred embodiment, the voltage dividing resistance circuit includes: a resistor R161 connected with the positive output end of the output circuit, a resistor R162 connected with the resistor R161, a variable resistor SVR1 connected with the other end of the resistor 162 and used for changing the voltage division ratio to adjust the output voltage set point, a resistor R160 and a capacitor C160 connected in series and connected in parallel with the two ends of the resistor R161, a resistor R163 connected in parallel with the two ends of the resistor R162, the other end of the variable resistor SVR1 is grounded, an overvoltage protection output voltage output between the resistor R161 and the resistor R162 is connected to the positive input end of the amplifier U100A, the inverting input end of the amplifier U100A is connected to a reference voltage chip SHR500 providing a reference voltage through a resistor R503, the output end of the amplifier U100A is connected to the positive electrode of the light emitting diode U2B through a diode D500 and a resistor R520, the output end of the amplifier U100A is connected to the inverting input end through capacitors C504 and R504, the anode of the reference voltage chip SHR500 is grounded, the cathode is connected to the inverting, The reference end of the reference voltage chip SHR500 is connected to the cathode of the amplifier, the other branch of the cathode of the reference voltage chip SHR500 is grounded through a capacitor C501, and a branch between the cathode of the reference voltage chip SHR500 and the capacitor C501 is connected to the inverting input end of the amplifier U100B through a resistor R505; the output current of the output circuit is connected to the inverting input end of an amplifier U100B through a current sampling resistor consisting of resistors R510 and R511 which are connected in parallel, and is connected to the non-inverting input end of the amplifier through a capacitor C510 and is grounded, the output end of an amplifier U100B is connected to the anode of the light-emitting diode U2B through a diode D510 through a resistor R520, and the output end of the amplifier U100 is fed back to the inverting input end of an amplifier U100B through a capacitor C512 and a resistor R512; the input end of the voltage stabilizing unit RG1 is connected to the power supply end of the amplifier U100A through a resistor R500, the output end of the voltage stabilizing unit RG1 is connected to the power supply end of the amplifier U100A through a resistor R501, one branch of the power supply end of the amplifier U100A is grounded through a capacitor C500, and the other branch of the power supply end of the amplifier U100A is connected to the cathode of a reference voltage chip SHR500 through a resistor R502; the cathode of the light emitting diode U2B is grounded.
In a preferred embodiment, further comprising: the switch isolation driving circuit is connected with the switching circuit and drives the switching circuit to work, and the main winding current detection circuit is connected with the main winding and detects the overcurrent of the main winding, and the power supply circuit comprises: with the main control unit is connected the starting circuit who drives the main control unit, switch isolation drive circuit includes: a transformer T2, a T2 primary winding disposed on the primary side of the transformer T2, a T2 primary winding disposed on the secondary side of the transformer T2, an amplifying circuit connected to the T2 primary winding and connected to the driving terminal of the main control unit for amplifying the driving signal, and a T2 secondary winding disposed on the secondary side of the transformer T2, wherein the switching circuit comprises: a switch tube Q1 connected with the first secondary winding of the T2, a switch tube Q2 connected with the second secondary winding of the T2, a main winding is arranged between the switch tube Q1 and the switch tube Q2, and the starting circuit comprises: a first starting resistor or resistor group connected to the rectifying and filtering circuit, a switch tube Q50 connected to the resistor or resistor group, a second starting resistor or resistor group connected to the other end of the switch tube Q50, and a capacitor C37 connected to the switch tube Q50 and charged according to the conduction of the switch tube Q50, wherein one end of the switch tube Q50 is connected to the power supply end of the main control unit; the main winding current detection circuit includes: the current detection circuit comprises a current sensing resistor for converting the current of the main winding into voltage detection, a resistor R60 connected with one end of the current sensing resistor and connected to the detection end of the main control unit, and a capacitor C53 connected with a resistor R60.
In a preferred embodiment, the switching transistor Q50 is an N-channel MOS transistor that turns on or off the connection between the drain and the source according to the voltage between the gate and the source, and the first starting resistor or resistor group includes: resistors R20, R21, R22 and R20 which are connected in series are connected into the rectifying and filtering circuit, a second starting resistor or resistor group comprises a zener diode ZD20, a resistor R24 and a resistor R25 which are connected in series, the negative electrode of the zener diode ZD20 is connected into the rectifying and filtering circuit after being converged with a resistor R20, a resistor R25 is connected into the grid electrode of the MOS tube Q50, a resistor R22 is connected into the drain electrode of the MOS tube Q50, a capacitor C37 is a polar capacitor, the source electrode of the MOS tube Q50 is connected into the positive electrode of the capacitor C37 and the negative electrode of the capacitor C37 and is grounded, the grid electrode of the MOS tube Q50 is grounded through a zener tube ZD50, a capacitor C33 is arranged between the grid electrode and the source electrode of the capacitor C33, two ends of the capacitor C26 are connected in parallel, and the source electrode of the MOS tube Q50 is connected into the power; the amplifying circuit in the switch isolation driving circuit comprises: an NPN triode Q51 and a PNP triode Q52, bases of the triode Q51 and the triode Q52 are connected to a driving end of the main control unit, a collector of the triode Q51 is connected to a power supply end of the main control unit, an emitter of the triode Q51 is connected to an emitter of the triode Q52, an emitter of the triode Q51 or an emitter of the triode Q52 is connected to one end of a primary winding of the T2 through a capacitor C19, a collector of the triode Q52 is connected to the other end of the primary winding of the T2, a collector of the triode Q51 is also connected to the other end of the primary winding of the T2 through a capacitor C20, the switching tubes Q1 and Q2 are N-channel enhancement type MOS tubes, one end of the first secondary winding of the T2 is connected to a gate of the MOS tube Q1 through a resistor R11, the other end of the first secondary winding of the transistor Q1 is connected to a source of the MOS tube Q1, a drain of the MOS tube Q1, the negative electrode of the diode D12 is connected to one end of a first secondary winding of the T2, a resistor R12 is arranged between the grid electrode and the source electrode of the MOS tube Q1, capacitors C13 and C14 which are connected in series are arranged between the drain electrode and the source electrode of the MOS tube Q1, the source electrode of the MOS tube Q1 is also connected to one end of a main winding, the other end of the main winding is connected to the drain electrode of the MOS tube Q1 through a diode D10, a capacitor C26 is further arranged between the two ends of the main winding, the grid electrode of the MOS tube Q2 is connected to one end of a second secondary winding of the T2 through a resistor R15 and a diode D15, the other end of the second secondary winding of the T2 is connected to one end of the main winding through a diode D11, a resistor R15 and a resistor R14 are connected in parallel to the two ends of the diode D15, capacitors C16 and C15 connected in: the resistor R18 and the resistor R19 are connected in parallel, one end of the resistor R18 is connected to the main winding through the MOS tube Q2, the resistor R2 is connected to the source electrode of the MOS tube Q2, and the other end of the resistor R18 is grounded.
In a preferred embodiment, further comprising: the setting is in the EMC circuit of rectification filter circuit front end, with rectification filter circuit connects the input voltage detection circuitry who detects input voltage after the rectification, with the remote switch circuit of master control unit communication, power supply circuit still includes: the soft start circuit is connected with the starting circuit, and the transformer type power supply circuit is connected with the starting circuit and connected to the main control unit, and the soft start circuit comprises: the charging circuit comprises a voltage division resistor connected with the starting circuit, a charging capacitor connected with the voltage division resistor, a switch tube Q70 connected with the voltage division resistor and conducted according to the charging condition of the charging capacitor, a resistor R73 connected with the switch tube Q70 and connected to a delay end of the main control unit according to the conduction of a switch tube Q70, wherein one end of the charging capacitor is connected with the voltage division resistor, the other end of the charging capacitor is connected with the feedback end of the main control unit, the other end of the switch tube Q70 is grounded, and the delay end of the main control unit is grounded through a resistor R52; the transformer-type power supply circuit includes: the transformer T1 comprises a primary secondary winding arranged on the primary side of the transformer T1, a chip power supply rectification filter circuit arranged on the primary secondary winding, and a voltage reduction circuit connected with the chip power supply rectification filter circuit and supplying power to the main control unit, wherein the chip power supply rectification filter circuit comprises: a diode D30 provided at one end of the primary secondary winding, a resistor R31 connected to the diode D30, and a capacitor C36 connected to the other end of the resistor R31 and the other end of the primary secondary winding, the step-down circuit including: a switch tube Q30 connected with the resistor R31, and a voltage regulator tube ZD30 connected with the other end of the switch tube Q30 and the other end of the primary secondary winding, wherein the EMC circuit comprises: filter capacitance and common mode inductance, filter capacitance in the EMC circuit includes: an X capacitor disposed across an input line, a Y capacitor disposed between the input line and a ground line, the input voltage detection circuit comprising: the voltage dividing resistor is connected to the input voltage rectified by the rectifying and filtering circuit, and the input voltage detection circuit is connected to the low-voltage detection input end of the main control unit through the voltage division of the voltage dividing resistor; the remote switch circuit includes: remote control trigger device, with remote control trigger device's optoelectronic coupler U4 who connects, optoelectronic coupler U4 includes: the light emitting diode U4B is arranged at the transmitting end, is connected with the remote control trigger device and is triggered and conducted by remote control, and the phototriode U4A is arranged at the receiving end, receives the signal of the light emitting diode U4B and transmits the signal to the main control unit for control.
In a preferred embodiment, a voltage dividing resistor in the soft start circuit comprises resistors R and R which are connected in sequence, one end of the resistor R is connected to the negative electrode of a capacitor C, the end of the resistor R is grounded, the other end of the resistor R is connected with a charging capacitor in the soft start circuit, the charging capacitor in the soft start circuit comprises capacitors C and C which are connected in parallel, the other end of the capacitor C and C are connected to a feedback end of a main control unit, a resistor R and a diode D which are connected in series are arranged at the two ends of the resistor R and R which are connected in series, one end of the resistor R and the resistor R connected to the negative electrode of the capacitor C is connected to the negative electrode of the capacitor C, the other end of the resistor R and the resistor R connected to the negative electrode of the resistor C is connected to the negative electrode of the resistor C and the ground of the resistor C, the resistor R connected to the negative electrode of the resistor C and the common mode detection unit, a voltage stabilizing resistor R and a ground resistor C of a voltage stabilizing diode C, a resistor R connected to a ground wire, a resistor C, a resistor R and a ground wire resistor C, a resistor R and a resistor C, a resistor R, a resistor C.
In the switching power supply circuit, after the power supply of the main control unit is started, the switching circuit is driven to perform power conversion, the cooling rectification filter circuit of the cooling power supply circuit rectifies and filters the alternating current voltage coupled to the second secondary winding of the transformer T1 and then outputs direct current, and the voltage of the filter capacitor C200 is reduced to a set voltage or the cooling drive control circuit and the fan are driven to perform cooling through the voltage stabilizing unit RG 1; when the temperature of the power supply rises, the resistance value of the thermistor RTH3 is reduced, the voltage of two ends of the driving resistor R220 rises, when the voltage of the driving resistor R is greater than the conduction voltage of the voltage stabilizing device SHR1, the C/A pin of the voltage stabilizing device SHR1 is conducted, the switching tube Q122 is driven to be conducted, namely the C/A pin of the voltage stabilizing device SHR1 is conducted to cause the B/E pin of the switching tube Q122 to be conducted, so that the C/E pin of the triode Q122 is conducted, the capacitor C201 charges the capacitor C221 through the switching tube Q122, the final voltage of the capacitor C is related to the resistance value of the thermistor RTH3, the smaller the resistance value of the thermistor RTH3 is, the higher the voltage of the capacitor C221 is, the power is supplied to the fan by the capacitor C221, the larger the output power is, the larger the; when the power supply temperature drops, the working process is vice versa, so that the cooling device is adjusted and controlled according to the detected power supply temperature, the output power of the cooling device is adjusted, the cooling device is flexibly adjusted according to the heating condition of the power supply, the power supply is effectively cooled, meanwhile, the electric energy is effectively utilized, and the energy is saved.
Drawings
Fig. 1 is a partial schematic diagram of the primary side of a transformer T1 of a switching power supply circuit according to an embodiment of the present invention;
fig. 2 is a partial schematic diagram of the secondary side of the transformer T1 of the switching power supply circuit according to an embodiment of the invention.
Detailed Description
As shown in fig. 1 to 2, a switching power supply circuit according to an embodiment of the present invention includes: the overvoltage protection circuit comprises a rectification filter circuit B, a switch circuit J connected with the rectification filter circuit B, a control circuit connected with the switch circuit J, a power supply circuit connected with the control circuit, primary side main windings 4-6 connected with the switch circuit J, a transformer T1 arranged corresponding to the main windings 4-6, an output circuit K arranged on the secondary side of the transformer T1, an over-temperature protection circuit arranged on the secondary side of the transformer T1, and an output overvoltage protection circuit N connected with the output circuit K, detecting output voltage and feeding the output voltage back to the control circuit for overvoltage protection.
The switching circuit J is provided on the primary side of the transformer T1. The control circuit includes: master unit U1. The main control unit U1 controls and collects information of related circuits or partial functional circuits, and controls according to the collected information. The output circuit K includes: the transformer T1 comprises a first secondary winding 9.10-7.8 arranged on the secondary side of the transformer T1, an output rectifying and filtering circuit connected with the first secondary winding 9.10-7.8, and a load circuit arranged at the output end.
The over-temperature protection circuit comprises a cooling power supply circuit L connected to the cooling device and a cooling drive control circuit M connected with the cooling power supply circuit L and used for adjusting the output voltage according to the power supply temperature so as to adjust the output power of the cooling device.
The cooling power supply circuit L includes a second secondary winding 11-12 disposed on the secondary side of the transformer T1, a cooling rectifying and smoothing circuit connected to the second secondary winding 11-12, and a voltage stabilizing unit RG1 connected to the cooling rectifying and smoothing circuit.
The cooling rectification filter circuit of this embodiment includes: and the filter capacitor C200 is connected with the cooling device and supplies power to the cooling drive control circuit or the cooling device.
Further, the temperature-reducing rectification filter circuit of the embodiment further comprises: a diode D200 connected to the second secondary winding 11-12, a capacitor C202 and a resistor R207 provided across the diode D200 and connected in series, a resistor R208 connected to the negative electrode of the diode D200, and a resistor R209 connected in parallel across the resistor R208. The common end of the resistor R208 and the resistor R209 is connected to the anode of the filter capacitor C200, and the cathode of the filter capacitor C200 is connected to the other end, namely 12 end, of the second secondary winding and grounded. One end of the resistor R208 connected with the positive electrode of the filter capacitor C200 is connected to the input end of the voltage stabilizing unit RG 1. The ground terminal of the voltage stabilization unit RG1 is grounded. The positive pole of the output circuit K is connected via a diode D201 to the input of the voltage regulator unit RG 1.
Preferably, the voltage regulation unit RG1 of the present embodiment is a three-terminal regulator integrated circuit 7812.
The cooling drive control circuit M of the present embodiment includes: the temperature-reducing power supply comprises a thermistor RTH3 which is arranged corresponding to a power supply to detect the temperature or the temperature change of the power supply and causes the resistance value change according to the temperature change, a driving resistor R220 connected with a thermistor RTH3, a capacitor C220 connected in parallel with two ends of the driving resistor R220, a voltage-stabilizing device SHR1 which is connected with the driving resistor R220 and conducts or not according to the voltage of two ends of the driving resistor R220, a switching tube Q122 which is connected with the voltage-stabilizing device SHR1 and conducts according to the conduction of the voltage-stabilizing device SHR1, a temperature-reducing power supply capacitor C221 which is connected with the switching tube Q122 and supplies power to a temperature-reducing device and causes the voltage change according to the resistance value change of the thermistor RTH3, and a capacitor C201 which is connected with the temperature-reducing power supply capacitor C221 and the switching. The capacitor C201 is connected to the output of the voltage regulator unit RG 1. The thermistor RTH3 is connected in series with the driving resistor R220 and across the capacitor C201.
Further, a resistor R219 is connected between the thermistor RTH3 and the driving resistor R220 in the present embodiment. The voltage regulator SHR1 is a voltage regulator diode or a controllable voltage regulator.
Further, the switching tube Q122 of the present embodiment is a PNP type triode Q122, a reference end of a voltage regulator device SHR1 is connected between the driving resistor R220 and the resistor R219, the voltage regulator device SHR1 of the present embodiment may select a voltage regulator device of type L a431, or a voltage regulator tube, the capacitor C201 and the cooling power supply capacitor C221 are polar capacitors, an anode of the voltage regulator device SHR1 is connected to a cathode of the capacitor C201, a cathode of the voltage regulator device SHR1 is connected to a base of the triode Q122 through the resistor R223, a collector of the triode Q122 is connected to an anode of the cooling power supply capacitor C221, an emitter of the triode Q122 is connected to an anode of the capacitor C201, a cathode of the cooling power supply capacitor C221 is connected to a cathode of the capacitor C201, a resistor R222 is disposed between the base and the emitter of the triode Q122, a branch of the collector of the triode Q122 is connected to a branch between the driving resistor R220 and the resistor R219 through the diode D221, a branch of the collector R219, and a branch of the thermistor.
The output overvoltage protection circuit N includes: a voltage regulator tube or a voltage regulator tube group connected with the output circuit K, a diode D150 connected with the voltage regulator tube or the voltage regulator tube group, and a photoelectric coupler U3 connected with the diode D150 and receiving overvoltage signals for conduction. The photocoupler U3 includes: the light emitting diode U3B is arranged at the emitting end and connected with a voltage stabilizing tube or a voltage stabilizing tube group of the output overvoltage protection circuit, and the phototriode U3A is arranged corresponding to the light emitting diode U3B, receives the detection signal of the light emitting diode U3B, and transmits the detection signal to the main control unit U1 so as to perform overvoltage protection on the main control unit U1.
The output overvoltage protection circuit further includes: a unidirectional silicon controlled triode SCR1 connected with a phototriode U3A, a resistor R64 connected with a unidirectional silicon controlled triode SCR1, and a resistor R65 connected with a resistor R64 in parallel, wherein the control electrode of the unidirectional silicon controlled triode SCR1 is connected to the emitter of the phototriode U3A and is conducted according to the conduction of the phototriode U3A. The other end of the resistor R64 and the resistor R65 connected in parallel is connected to a power supply terminal VCC of the main control unit U1. The cathode of the one-way thyristor SCR1 is grounded, and the anode of the one-way thyristor SCR1 is connected with the resistor R64. The emitter of the photo-transistor U3A is grounded via a resistor R66, and the collector thereof is connected to the power supply terminal VCC of the main control unit U1 via a resistor R63. And a capacitor C60 is connected in parallel with two ends of the resistor R66.
The regulator tube or the regulator tube group of the output overvoltage protection circuit comprises: and zener diodes ZD150, ZD151 connected in series. The cathode of the zener diode ZD150 is connected to the anode of the output circuit. The cathode of the ZD151 is connected to the anode of the zener diode ZD 150. The anode of diode D150 is connected to the anode of ZD151, and the cathode thereof is connected to the anode of led U3B through resistor R150. The cathode of the light emitting diode U3B is connected to the cathode of the capacitor C201. A resistor R151 and a capacitor C150 are connected in parallel to two ends of the light emitting diode U3B.
In this embodiment, the cooling device is described as a fan, but other cooling devices may be used. After the main control unit U1 of this embodiment is powered and started by the power supply circuit, the power switch is driven to perform power conversion, the diode D200 rectifies the ac voltage coupled to the second secondary winding 11-12 of the transformer T1, and then the rectified ac voltage is filtered by the resistors R208 and R209 and the capacitor C200 to become a dc voltage, and the dc voltage is then reduced to 12V by the voltage stabilizing unit RG1 and then supplied to the cooling drive control circuit M and the fan.
When the power supply temperature rises, the resistance value of the thermistor RTH3 is reduced, the voltage of the two ends of the resistor R220 rises, when the voltage of the thermistor is more than 2.5V, the C/A pin of the voltage stabilizing device SHR1 is conducted, the B/E pin of the triode Q122 is conducted, the C/E pin of the triode Q122 is conducted, and the capacitor C201 charges the capacitor C221 through the triode Q122. The final voltage is related to the resistance of the thermistor RTH3, the smaller the resistance of the thermistor RTH3 is, the higher the voltage of the capacitor C221 is, and the maximum voltage is set to 12V in the embodiment. Capacitor C221 powers the fan. The higher the power supply temperature, the faster the fan is driven. When the temperature of the power supply is reduced, the working process is reversed.
When the output voltage of the output circuit is greater than the regulated voltage value of the voltage regulator tube ZD150+ ZD151, the voltage regulator tubes ZD150 and ZD151 are conducted, the light emitting diode U3B at the emitting end of the photoelectric coupler is conducted, the phototriode U3A at the receiving end of the photoelectric coupler at the primary side of the output overvoltage protection circuit detects that the light emitting diode U3B at the emitting end is conducted, and then OVP protection (output voltage overvoltage protection) is triggered to control the power supply to be turned off.
The output circuit K includes: the transformer T1 comprises a first secondary winding 9.10-7.8 arranged on the secondary side of the transformer T1, an output rectifying and filtering circuit connected with the first secondary winding 9.10-7.8, and a load circuit arranged at the output end.
Q101, Q102, D61, D62, D63, L100, C105, C106, C107 and C108 in the output rectifying and filtering circuit rectify and filter the PWM voltage coupled to the primary secondary winding 9.10-7.8 on the secondary side of the T1 into a direct current output voltage, and the output voltage is in proportion to the voltage value and the duty ratio of the PWM voltage.
The rectifying and filtering circuit B of the present embodiment includes: input rectifying circuit, input filter circuit. The input rectification circuit includes: rectifier bridge BD 1. The input filter circuit includes: and filter capacitors C5 and C6.
The filter capacitors C5 and C6 are polar capacitors, the positive output end rectified by the rectifier bridge BD1 is connected to the positive electrode of the filter capacitor C5 after passing through the thermistor RTH1, the zero line input end enters the negative electrode of the filter capacitor C5 after passing through the common mode inductor L F1 and the switch SW1, two ends of the filter capacitor C5 are connected in parallel with resistors R6 and R5 which are connected in series, and two ends of the filter capacitor C5 are connected in parallel with the piezoresistor ZNR 5.
The negative output end rectified by the rectifier bridge BD1 is connected to the negative electrode of the filter capacitor C6 through the resistor RTH2 and grounded, and the positive electrode of the filter capacitor C6 is connected to the negative electrode of the filter capacitor C5. The two ends of the filter capacitor C6 are connected in parallel with resistors R7 and R8 which are connected in series, and the two ends of the filter capacitor C6 are also connected in parallel with a piezoresistor ZNR 6. And a capacitor C30 is arranged between the negative output end rectified by the rectifier bridge BD1 and the ground wire input end.
The rectifying and filtering circuit B of the present embodiment further includes: and the capacitor bank is arranged between the positive electrode and the negative electrode of the rectified output of the rectifier bridge BD 1. The capacitor bank includes: and the capacitors are connected in parallel, namely C9, C10, C11 and C12. One end of each of the C9, C10, C11 and C12 which are connected in parallel is grounded, and the other end is connected to the switch circuit.
The rectifying-smoothing circuit B of the present embodiment rectifies an ac input voltage by the rectifier bridge BD1, and then smoothes the rectified ac input voltage by the C5 and the C6 to convert the rectified ac input voltage into a dc voltage. The piezoresistors RTH1 and RTH2 can suppress inrush current when the power supply is started.
Further, the switching power supply circuit of the present embodiment further includes: and an output detection feedback circuit P, Q connected to the output circuit K and detecting an output voltage or current to feed back to the main control unit U1 for constant current protection or constant voltage output. In this embodiment, the P portion of the output detection feedback circuit mainly detects and feeds back the output current, and the Q portion mainly detects and feeds back the output voltage.
Further, the output detection feedback circuit of the present embodiment includes: the detection circuit comprises a detection unit U100 for detecting the output voltage or current of the output circuit, a current sampling resistor connected with the output circuit and connected into the detection unit U100 to be matched with the detection unit U100 to detect the output current of the output circuit, a voltage division resistor circuit connected with the output end of the output circuit and connected into the detection unit U100 to be matched with the detection unit U100 to detect the output voltage, and a photoelectric coupler U2 connected with the output end of the amplifier U100.
The detection unit U100 includes: the amplifier U100A is connected with a voltage dividing resistor circuit of the output detection feedback circuit, compares and judges the voltage divided by the voltage dividing resistor circuit with a reference voltage, and feeds back the voltage divided by the voltage dividing resistor circuit to the control circuit through a photoelectric coupler U2, and the amplifier U100B is connected with a current sampling resistor of the output detection feedback circuit and detects the output current or the current change of the output circuit. The amplifier U100A has an inverting input terminal connected to the reference voltage and a non-inverting input terminal connected to the divided voltage of the voltage dividing resistor circuit connected thereto.
The output current of the output circuit is coupled through a current sampling resistor to the inverting input of amplifier U100B and through capacitor C510 to its non-inverting input and to ground. The photocoupler U2 includes: the light emitting diode U2B is arranged at the emitting end, is connected with the output end of the amplifier U100A or the output end of the amplifier U100B and causes current change according to the change of the output voltage of the amplifier, and the phototriode U2A is arranged corresponding to the light emitting diode U2B and receives the detection signal of the light emitting diode U2B and transmits the detection signal to the main control unit U1 so that the phototriode U2A can adjust the output voltage according to the detection signal to output constant current or constant voltage.
Further, the voltage-dividing resistance circuit of the present embodiment includes: the circuit comprises a resistor R161 connected with the positive electrode output end of the output circuit, a resistor R162 connected with the resistor R161, a variable resistor SVR1 connected with the other end of the resistor 162 and used for changing the voltage division ratio to adjust the output voltage set point, a resistor R160 and a capacitor C160 which are connected in series and connected in parallel with the two ends of the resistor R161, and a resistor R163 connected in parallel with the two ends of the resistor R162.
The other end of the variable resistor SVR1 is grounded, and the voltage division value of the voltage division point is adjusted by adjusting the resistance of the variable resistor SVR1 so as to adapt to the requirements of different loads, different products and different scenes.
The output voltage of the overvoltage protection between the resistor R161 and the resistor R162 of the present embodiment is connected to the non-inverting input terminal of the amplifier U100A. The inverting input of amplifier U100A is coupled through resistor R503 to a reference voltage chip SHR500 that provides a reference voltage. The output end of the amplifier U100A is connected to the anode of the LED U2B through a diode D500 and a resistor R520. The output terminal of the amplifier U100A is further connected to the inverting input terminal thereof through capacitors C504 and R504, the anode of the reference voltage chip SHR500 is grounded, the cathode thereof is connected to the inverting input terminal of the amplifier U100A through a resistor R503, and the reference terminal thereof is connected to the cathode thereof.
The other branch of the cathode of the reference voltage chip SHR500 is grounded through a capacitor C501, and the branch between the cathode of the reference voltage chip SHR500 and the capacitor C501 is connected to the inverting input terminal of the amplifier U100B through a resistor R505. The output current of the output circuit is connected to the inverting input terminal of the amplifier U100B through a current sampling resistor consisting of resistors R510 and R511 connected in parallel, and is connected to the non-inverting input terminal thereof through a capacitor C510 and grounded. The current sampling resistor is connected to the output circuit at J109. The output terminal of the amplifier U100B is coupled to the anode of the led U2B through the diode D510 via the resistor R520, and the output terminal is fed back to the inverting input terminal of the amplifier U100B through the capacitor C512 and the resistor R512. The input of the voltage regulation unit RG1 is connected via a resistor R500 to the supply terminal of the amplifier U100A, and its output is connected via a resistor R501 to the supply terminal of the amplifier U100A. One branch of the power supply terminal of the amplifier U100A is connected to ground through a capacitor C500, and the other branch thereof is connected to the cathode of a reference voltage chip SHR500 through a resistor R502. The cathode of the led U2B is grounded.
The potential of the junction point of the resistor R510 and the resistor R511 connected in parallel at the J109 of the output circuit K is reduced along with the increase of the output current, so that the potential of the pin 6 of the detection unit U100 is reduced, that is, the potential of the non-inverting input terminal of the amplifier U100B is also reduced, when the potential is less than 0V, the pin 7 of the detection unit U100, that is, the output terminal of the amplifier U100B outputs a high level, so that the current of the light emitting diode U2B at the transmitting terminal of the photocoupler U2 is increased, and a signal is transmitted to the phototriode U2A at the receiving terminal, so that the detected output current change of the output circuit is transmitted to the main control unit U1, the main control unit U1 drives the PWM duty ratio to be reduced, the output current is reduced, and through the negative feedback circuit, the output current is stabilized at the OCP (over-current protection) set point, the protection mode is a constant current protection, which, the problem of power hiccup protection that often takes place in practical application is solved.
After the output voltage of the output circuit K is divided by the resistors R160-R163 and the variable resistor SVR1, the divided voltage of the divided voltage point is input to the positive input end of the amplifier U100A, the detection unit U100 compares the detected divided voltage with the reference voltage generated by the reference voltage chip SHR500, such as 2.5V, when the divided voltage is greater than 2.5V, the output voltage of the pin U1001 of the detection unit increases, that is, the output terminal voltage of the amplifier U100A increases, so that the current of the light emitting diode U2B at the transmitting end of the photocoupler U2 increases, and a signal is transmitted to the phototransistor U2A at the receiving end, so that the detected output current change of the output circuit is transmitted to the main control unit U1, the main control unit U1 drives the PWM duty ratio to decrease, the output voltage decreases, and the output voltage will be stabilized at the output voltage set point through the negative feedback circuit. Variable resistor SVR1 may vary the voltage division ratio and thus the output voltage set point.
The detection unit U100 of this embodiment may preferably be implemented by using a chip with a model number of L M258, and certainly is not limited to this model chip, as long as the function of the detection feedback circuit is implemented.
The main control unit U1 of this embodiment is preferably a control chip of the model NCP 1252. Of course, the present invention is not limited to this chip, as long as the functions of the switching circuit of the present invention and the detection and control functions of the present invention can be controlled.
Further, the switching power supply circuit of the present embodiment further includes: a switch isolation driving circuit H which is connected with the switch circuit J and drives the switch circuit to work, and a main winding current detection circuit I which is connected with the main windings 4-6 and detects the overcurrent of the main windings.
The switch isolation driving circuit H of the present embodiment includes: the transformer T2, the T2 primary winding 10-1 arranged on the primary side of the transformer T2, the T2 first secondary winding 6-3 arranged on the secondary side of the transformer T2, an amplifying circuit connected with the T2 primary winding and connected to the driving end DRV of the main control unit U1 to amplify the driving signal, and the T2 second secondary winding arranged on the secondary side of the transformer T2.
The switch circuit J of the present embodiment includes: a switch tube Q1 connected with the first secondary winding of T2, and a switch tube Q2 connected with the second secondary winding of T2. The main windings 4-6 are disposed between the switch tube Q1 and the switch tube Q2.
Further, the amplifying circuit in the switch isolation driving circuit of the present embodiment includes: an NPN triode Q51 and a PNP triode Q52. The base electrodes of the transistor Q51 and the transistor Q52 are connected to the drive terminal DRV of the main control unit U1, that is, the pin 6 of the main control unit U1. The collector of the triode Q51 is connected to the power supply terminal VCC of the main control unit U1. The emitter of the transistor Q51 is connected with the emitter of the transistor Q52, the emitter of the transistor Q51 or the emitter of the transistor Q52, namely the common end of the emitter of the transistor Q51 and the emitter of the transistor Q52 is connected with one end 10 of a T2 primary winding 10-11 through a capacitor C19, and the collector of the transistor Q52 is connected with the other end 11 of a T2 primary winding. The collector of the transistor Q51 is also connected to the other end 11 of the T2 primary winding through a capacitor C20.
Further, the switching transistors Q1 and Q2 of the present embodiment are N-channel enhancement MOS transistors. One end of the first secondary winding of the T2 is connected to the grid of the MOS transistor Q1 through the resistor R11, and the other end is connected to the source of the MOS transistor Q1. The drain of the MOS transistor Q1 is connected to the rectifying and smoothing circuit B, and a diode D12 and a resistor R10 connected in series are connected in parallel to both ends of the resistor R11. The cathode of diode D12 is connected to one end 6 of the first secondary winding 6-3 of T2. A resistor R12 is provided between the gate and the source of the MOS transistor Q1. Capacitors C13 and C14 connected in series are provided between the drain and the source of the MOS transistor Q1. The source of the MOS transistor Q1 is also connected to one end 4 of the main winding 4-6. The other end 6 of the main winding 4-6 is connected to the drain of the MOS transistor Q1 through a diode D10. A capacitor C26 is also provided between the ends of the main windings 4-6. The gate of MOS transistor Q2 is connected to one end 8 of the second secondary winding 8-5 of T2 through resistor R15 and diode D15, and the other end 5 of the second secondary winding 8-5 of T2 is connected to one end 4 of the main winding 4-6 through diode D11. The resistor R15 and the diode D15 are connected in parallel with the resistor R14 at two ends. Capacitors C16 and C15 connected in series are provided between the drain and the source of the MOS transistor Q2. The current sensing resistor includes: a resistor R18 and a resistor R19 connected in parallel. One end of the resistor R18 is connected to the main windings 4-6 through the MOS transistor Q2, the source of the MOS transistor Q2, and the other end is grounded.
The MOS tubes Q1 and Q2 are driven or turned off by the main control unit U1 at the same time, an alternating current PWM voltage is generated on the main winding 4-6 of the transformer T1, so that the alternating current PWM voltage can transmit energy to other windings of the transformer T1, and the diodes D10 and D11 are excitation inductance reset current paths of the transformer T1.
Further, the main winding current detection circuit I of the present embodiment includes: the current detection circuit comprises a current sensing resistor for converting the current of the main winding into voltage detection, a resistor R60 connected with one end of the current sensing resistor and connected to a detection end CS of the main control unit U1, and a capacitor C53 connected with a resistor R60. One end of the capacitor C53 is connected to the detection terminal CS of the main control unit U1, and the other end is grounded.
The grounded end or one pole of the capacitor C53 is connected to the 12 end of the second secondary winding 11-12 of the temperature-reducing power supply circuit L through the capacitor C3.
The main winding current detection circuit I detects the current of the main winding 4-6, converts the current value of the main winding 4-6 of the transformer T1 into a voltage value through the resistors R18 and R19, and inputs the voltage value into the detection end CS (pin 3) of the main control unit U1 after filtering through the resistor R60 and the capacitor C53. If the main control unit U1 detects that the voltage of the detection end CS is larger than 1V, the driving is controlled to be closed, so that the current of the main winding 4-6 is prevented from being overlarge, and the purpose of performing overpower protection on the primary side is achieved.
Further, the power supply circuit of the present embodiment includes: and the starting circuit D is connected with the main control unit U1 and drives the main control unit U1.
The start-up circuit D of the present embodiment includes: the rectifier filter circuit comprises a first starting resistor or resistor group connected to the rectifier filter circuit B, a switch tube Q50 connected with the first starting resistor or resistor group, a second starting resistor or resistor group connected with the other end of the switch tube Q50, and a capacitor C37 connected with the switch tube Q50 and charged according to the conduction of the switch tube Q50. One end of the switching tube Q50 is connected to a power supply terminal VCC of the main control unit U1.
The switching transistor Q50 is an N-channel MOS transistor that turns on or off the connection between its drain and source according to the voltage between the gate and source. The source of the MOS transistor Q50 is further connected to the power supply terminal VCC of the main control unit U1 and grounded through the capacitor C50.
The first firing resistor or resistor bank includes: resistors R20, R21 and R22 connected in series. R20 is connected into the rectification filter circuit B. Preferably, R20 is connected to the output terminal of the rectifier circuit BD1 rectified by the rectifier filter circuit and then connected to the thermistor RTH 1. The second firing resistor or resistor bank includes: a voltage stabilizing diode ZD20, a resistor R24 and a resistor R25 which are connected in series. The negative electrode of the voltage stabilizing diode ZD20 is merged with the resistor R20 and then is connected into the rectifying and filtering circuit B, and is connected into the output end which is rectified and output by the rectifying circuit BD1 and then passes through the thermistor RTH 1.
The resistor R25 is connected to the gate of the MOS transistor Q50. The resistor R22 is connected to the drain of the MOS transistor Q50. The capacitor C37 is a polar capacitor. The source of the MOS transistor Q50 is connected to the anode of the capacitor C37. The negative terminal of the capacitor C37 is connected to ground. The gate of the MOS transistor Q50 is grounded through a voltage regulator ZD50, and a capacitor C33 is disposed between the gate and the source. A resistor R26 is connected in parallel with the two ends of the capacitor C33.
When the mains supply is connected, and the input L/N is just powered on, the voltage of the capacitor C37 is 0V, the voltage between the gate G and the source S of the MOS transistor Q50 is 15V, and the drain D and the source S of the MOS transistor Q50 are connected.
The current output by the rectifier circuit BD1 after being rectified and passing through the thermistor RTH1 passes through the resistors R20, R21, R22 and the MOS tube Q50 to charge the capacitor C37. When the voltage of the capacitor C37 rises to a preset starting voltage, for example, about 10V, the power terminal VCC of the main control unit U1 reaches the starting voltage. When the voltage of the capacitor C37 continues to rise, and the voltage between the gate G and the source S of the MOS transistor Q50 drops to about 3V, the drain D and the source S of the MOS transistor Q50 are turned off.
Further, the power supply circuit of the present embodiment further includes: the soft start circuit E is connected with the start circuit D, and the transformer type power supply circuit G is connected with the start circuit D and is connected to the main control unit U1.
Further, the soft start circuit of the present embodiment includes: the starting circuit comprises a voltage division resistor connected with the starting circuit D, a charging capacitor connected with the voltage division resistor, a switch tube Q70 connected with the voltage division resistor and conducted according to the charging condition of the charging capacitor, and a resistor R73 connected with the switch tube Q70 and conducted to a delay terminal RT connected to the main control unit U1 according to the switch tube Q70. One end of the charging capacitor is connected with the voltage dividing resistor, and the other end of the charging capacitor is connected with the feedback end FB of the main control unit U1. The other end of the switching tube Q70 is grounded. The delay terminal RT of the master unit U1 is further connected to ground through a resistor R52.
Further, the voltage dividing resistor in the soft start circuit E of the present embodiment includes: and resistors R72 and R71 connected in sequence. One end of the resistor R72 is connected to the negative electrode of the capacitor C37, and the end is grounded. The other end of the resistor R71 is connected with a charging capacitor in the circuit. The charging capacitor in the soft start circuit E includes: and the capacitors C70 and C71 are connected in parallel. The other end of the resistor R71 is connected with capacitors C70 and C71. The other end of the parallel capacitor C70 and C71 is connected to the feedback terminal FB of the main control unit U1. Both ends of the resistors R72 and R71 connected in this order are connected to a resistor R70 and a diode D70 connected in series. One end of the resistor R70 connected with the resistor R72 is connected to the cathode of the capacitor C37, and the other end is connected to the anode of the diode D70. The cathode of the diode D70 is connected to the capacitor C70. The switch tube Q70 is an N-channel MOS tube, the gate of which is connected between the resistors R72 and R71, and the source of which is connected to the cathode of the capacitor C37 and grounded.
After the main control unit U1 reaches the starting voltage, the feedback end FB is suddenly changed from the low level to the high level, at this time, the negative end of the capacitor C37 charges the capacitors C70 and C71 through the resistors R71 and R72, when the voltage at the two ends of the resistor R72 reaches the GS threshold voltage of the MOS transistor Q70, the DS of the MOS transistor Q70 is conducted, at this time, the resistor R73 is connected with the resistor R52 in parallel, and after the delay end RT of the main control unit U1 detects that the external resistor is reduced, the switching frequency of the main control unit U1 is increased, so that the impact current to the MOS transistors Q1 and Q2 during starting is reduced, and the purpose of soft starting is achieved.
Further, the transformer-type power supply circuit G of the present embodiment includes: the transformer T1 comprises a primary secondary winding 1-2 arranged on the primary side of the transformer T1, a chip power supply rectification filter circuit arranged on the primary secondary winding 1-2, and a voltage reduction circuit connected with the chip power supply rectification filter circuit and supplying power to the main control unit.
The chip power supply rectification filter circuit of this embodiment includes: a diode D30 disposed at one end 1 of the primary secondary winding 1-2, a resistor R31 connected to the diode D30, and a capacitor C36 connected to the other end of the resistor R31 and the other end 2 of the primary secondary winding 1-2.
The step-down circuit of the present embodiment includes: a switch tube Q30 connected with the resistor R31, and a voltage regulator tube ZD30 connected with the other end of the switch tube Q30 and the other end of the primary secondary winding.
The switching transistor Q30 of the present embodiment is an NPN transistor. The diode D30 has a series resistor R30 and a capacitor C35 disposed at two ends. Two ends of the resistor R31 are connected in parallel with a resistor R34, one end of the resistor R31 is connected with the cathode of the diode D30, and the other end of the resistor R31 is connected to the collector of the triode Q30. The capacitor C36 is a polar capacitor, and the other end of the resistor R31, that is, the end connected to the collector of the transistor Q30, is branched into the positive electrode of the capacitor C36. A resistor R32 is arranged between the collector and the base of the triode Q30. The zener diode ZD30 is a zener diode. The base of the triode Q30 is connected to the negative electrode of the zener diode ZD30, and the emitter thereof is connected to the power supply terminal VCC of the main control unit U1 through the diode D31 and the resistor R33. A branch circuit is led out between the base electrode of the triode Q30 and the anode of the diode D31 and is connected to a low-voltage detection input end BO of the main control unit U1 through a resistor R74. The cathode of the capacitor C36 and the anode of the zener diode ZD30 are grounded.
When the main control unit U1 is started by the starting circuit, the power switch is driven to perform power conversion, the diode D30 rectifies alternating-current voltage coupled to a primary secondary winding 1-2 of the transformer T1, the rectified alternating-current voltage is filtered by the R31 and the C36 to be converted into direct current, the voltage of the capacitor C36 is reduced to 20V by the triode Q30, the resistor R32 and the voltage regulator ZD30 and then is supplied to the power supply terminal VCC of the main control unit U1, and the starting circuit D can be completely turned off, so that loss is reduced, and power supply efficiency is improved.
Further, the switching power supply circuit of the present embodiment further includes: and the EMC circuit A is arranged at the front end of the rectifying and filtering circuit.
The EMC circuit of the present embodiment includes: a filter capacitor, and a common mode inductor. The filter capacitance in the EMC circuit includes: an X capacitor disposed at both ends of the input line, and a Y capacitor disposed between the input line and the ground line.
Further, the EMC circuit of the present embodiment further includes: the live wire voltage regulator comprises a piezoresistor ZNR1 arranged between live and neutral wires, and series-connected resistors R2 and R1 arranged between the live and neutral wires. One end of the resistor R1 is connected with the resistor R2, and the other end is connected with a live wire. The other end of the resistor R2 is connected with a zero line.
Further, the Y capacitor of the present embodiment includes: the capacitor C23 is connected between the live wire and the ground wire, the capacitor C3 is connected between the live wire and the ground wire, the capacitor C24 is connected between the zero line and the ground wire, and the capacitor C4 is connected between the zero line and the ground wire. One end of the capacitor C3 is connected with the capacitor C4, and the other end is connected to the live wire. The other end of the capacitor C4 is connected with a zero line. The X capacitor includes: and the capacitor C1 is connected between the live wire and the neutral wire, and the capacitor C2 is connected between the live wire and the neutral wire.
The common-mode inductor comprises a common-mode inductor L F1, two ends of one coil of the common-mode inductor L F1 are respectively connected to the other ends of a resistor R1 and a capacitor C3 and connected to a live wire, and two ends of the other coil of the common-mode inductor are respectively connected to the other ends of a resistor R2 and a capacitor C4 and connected to a zero wire.
The EMC circuit of the present embodiment further includes a varistor ZNR1 provided at the input terminal of the common mode inductor L F1 and between the live line and the neutral line.
The EMC (Electro Magnetic Compatibility) circuit inhibits the conduction and radiation interference caused by the self power switch to the outside through the common mode inductor L F1 and the filtering of the X capacitor and the Y capacitor, and the voltage dependent resistor ZNR1 protects the rear circuit from being damaged by lightning surge voltage.
Further, the switching power supply circuit of the present embodiment further includes: and an input voltage detection circuit C connected to the rectification filter circuit B and detecting the rectified input voltage.
The input voltage detection circuit C of the present embodiment includes: and the divider resistor is connected to the input voltage point rectified by the rectifying and filtering circuit. The input voltage detection circuit C is connected to a low voltage detection input BO of the main control unit U1 through the voltage division of the voltage division resistor.
Further, the voltage dividing resistor of the input voltage detection circuit of the present embodiment includes: the resistor R45, R46, R47 and R53 are connected in sequence.
One end of the resistor R45 is connected to the input voltage end rectified by the rectifying and filtering circuit B, and the other end is connected with the resistor R46. Preferably, one end of the resistor R45 is connected to an input voltage end rectified by the rectifier circuit DB1 and outputted from the thermistor RTH 1. The input voltage end of the voltage regulator is mainly used for supplying power to other functional circuits and chips after rectifying and filtering. A low-voltage detection input end BO of the main control unit U1 is connected between the resistors R53 and R47. The other end of the resistor R53 is grounded.
The input voltage rectified by the rectifying circuit or the rectifying bridge DB1 is divided by resistors R53 and R45/R46/R47, the voltage at two ends of R53 is input to a low-voltage detection input end BO of the main control unit U1, and when the main control unit U1 detects that the divided voltage input by the low-voltage detection input end BO is lower than 1V, the main control unit U1 controls to close driving, so that the power supply enters an input low-voltage protection state.
Further, the switching power supply circuit of the present embodiment further includes: a remote switch circuit O in communication with the master control unit U1. The remote control switch circuit O of the present embodiment includes: remote control trigger device, photoelectric coupler U4 connected with the remote control trigger device. The trigger switch of the remote control trigger device or trigger connector end CN 600. The photocoupler U4 includes: the light emitting diode U4B is arranged at the transmitting end and connected with the remote control trigger device and is triggered and conducted by remote control, and the phototriode U4A receives the signal of the light emitting diode U4B and transmits the signal to the main control unit U1 for control. The collector of the phototriode U4A is connected to the low voltage detection input BO of the main control unit U1, and the emitter thereof is grounded. The ground GND of the main control unit U1 is grounded.
Further, the remote switch circuit of the present embodiment further includes: the LED driving circuit comprises a resistor R600 connected with the LED U4B in series, a resistor R601 connected with two ends of the LED U4B in parallel and a capacitor C601 connected with the resistor R601 in parallel. One end of the resistor R600 is connected to the anode of the remote control trigger device CN600, and the other end is connected to the anode of the light emitting diode U4B. The cathode of the light emitting diode U4B is connected to the cathode of the remote control trigger device CN 600.
When the trigger switch of the remote control trigger device or the input of the trigger connector end CN600 is at a high level, the light emitting diode U4B of the photoelectric coupler U4 is turned on, so as to drive the photoelectric triode U4A at the receiving end to be turned on, pull the potential of the low voltage detection input end BO of the main control unit U1 to be lower than 1V, thereby turning off the drive, and turning off the output. When the trigger switch of the remote control trigger device or the input of the trigger connector end CN600 is at a low level, the light emitting diode U4B of the photoelectric coupler U4 is turned off, which results in the turn-off of the phototriode U4A at the receiving end, and the potential of the low voltage detection input end BO of the main control unit U1 is higher than 1V, so that the output drive is performed, and the power supply works normally.
The switching power supply circuit is mainly used for realizing a switching power supply with the power of 350W, the input voltage is preferably 90-132 or 180-264 VAC, the rated output is 12VDC/29A or 24VDC/14.6A, the circuit has input low voltage protection, OVP (output overvoltage protection), OCP (output overcurrent protection) and OTP (over-temperature protection), and the used power conversion topology is double-tube forward.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (5)
1. A switching power supply circuit, comprising: the rectifier filter circuit, with the switch circuit of rectifier filter circuit connection, with the control circuit of switch circuit connection, with the supply circuit of control circuit connection, the primary side main winding of switch circuit connection, with the transformer T1 that the main winding corresponds sets up, set up in the output circuit of transformer T1 secondary side, set up in the excess temperature protection circuit of transformer T1 secondary side, with output circuit connection detect output voltage and feed back to the control circuit and carry out overvoltage protection's output overvoltage crowbar, the switch circuit sets up in the primary side of transformer T1, the control circuit includes: a master control unit, the output circuit comprising: the over-temperature protection circuit comprises a first secondary winding arranged on the secondary side of the transformer T1, an output rectifying and filtering circuit connected with the first secondary winding, and a load circuit arranged at the output end, wherein the over-temperature protection circuit comprises: insert the cooling supply circuit of heat sink, with cooling supply circuit connects and adjusts output voltage according to power temperature in order to adjust heat sink output's cooling drive control circuit, cooling supply circuit includes: a second secondary winding disposed on the secondary side of the transformer T1, a ramp-down rectifier-filter circuit connected to the second secondary winding, and a voltage regulator unit RG1 connected to the ramp-down rectifier-filter circuit, wherein the ramp-down rectifier-filter circuit includes: be connected with the heat sink and supply power for cooling drive control circuit or heat sink's filter capacitor C200, cooling drive control circuit includes: a thermistor RTH3 which is arranged corresponding to the power supply and detects the temperature or the temperature change of the power supply and causes the resistance value change according to the temperature change, a driving resistor R220 connected with the thermistor RTH3, a capacitor C220 which is connected in parallel with two ends of the driving resistor R220, a voltage stabilizing device SHR1 which is connected with the driving resistor R220 and conducts or not according to the voltage of two ends of the driving resistor R220, a switch tube Q122 which is connected with the voltage stabilizing device SHR1 and conducts according to the conduction of the voltage stabilizing device SHR1, a cooling power supply capacitor C221 which is connected with the switch tube Q122 and supplies power to a cooling device and causes the voltage change according to the resistance value change of the thermistor RTH3, and a capacitor C201 which is connected with the cooling power supply capacitor C221 and the switch tube Q122 and supplies power to the cooling power supply capacitor C221 through the switch tube Q, the capacitor C201 is connected with the output end of the voltage stabilizing unit RG1, and the thermistor RTH3 is connected with the driving resistor R220 in series and is connected to the two ends of the capacitor C201; a resistor R219 is further connected between the thermistor RTH3 and the driving resistor R220, the voltage regulator SHR1 is a voltage regulator diode or a controllable voltage regulator, the switching tube Q122 is a PNP type triode Q122, a reference end of the voltage regulator SHR1 is connected between the driving resistor R220 and the resistor R219, the capacitor C201 and the cooling power supply capacitor C221 are polar capacitors, the positive electrode of the voltage regulator SHR1 is connected to the negative electrode of the capacitor C201, the negative electrode of the voltage regulator SHR1 is connected to the base electrode of the triode Q122 through a resistor R223, the collector electrode of the triode Q122 is connected to the positive electrode of the cooling power supply capacitor C221, the emitter electrode of the cooling power supply capacitor C221 is connected to the positive electrode of the capacitor C201, a resistor R222 is arranged between the base electrode and the emitter electrode of the triode Q122, one branch of the collector electrode of the triode Q122 is connected to a position between the driving resistor R220 and the resistor R219 through a diode D221 and a resistor R221, a branch is led out between the resistor R219 and the thermistor RTH3 and is connected into the output overvoltage protection circuit through a voltage regulator tube ZD 153;
the output overvoltage protection circuit includes: a voltage regulator tube or a voltage regulator tube group connected with the output circuit, a diode D150 connected with the voltage regulator tube or the voltage regulator tube group, and a photoelectric coupler U3 connected with the diode D150 and receiving an overvoltage signal for conduction, wherein the photoelectric coupler U3 comprises: the light emitting diode U3B is arranged at the emitting end and is connected with a voltage stabilizing tube or a voltage stabilizing tube group of an output overvoltage protection circuit, and the phototriode U3A is arranged corresponding to the light emitting diode U3B, receives a detection signal of the light emitting diode U3B, and transmits the detection signal to the main control unit so as to perform overvoltage protection on the main control unit;
the output overvoltage protection circuit further comprises: a unidirectional silicon controlled triode SCR1 connected with the phototriode U3A, a resistor R64 connected with the unidirectional silicon controlled triode SCR1, and a resistor R65 connected in parallel with the resistor R64, wherein the control electrode of the unidirectional silicon controlled triode SCR1 is connected to the emitter of the phototriode U3A and is conducted according to the conduction of the phototriode U3A, the other ends of the resistor R64 and the resistor R65 connected in parallel are connected to the power supply end of the main control unit, the cathode of the unidirectional silicon controlled triode SCR1 is grounded, the anode of the unidirectional silicon controlled triode SCR1 is connected to the resistor R64, the emitter of the phototriode U3A is grounded through the resistor R66, the collector of the unidirectional silicon controlled triode SCR1 is connected to the power supply end of the main control unit through the resistor R58; the voltage regulator tube or the voltage regulator tube group of the output overvoltage protection circuit comprises: the LED driving circuit comprises series-connected Zener diodes ZD150 and ZD151, wherein the cathode of the Zener diode ZD150 is connected to the anode of the output circuit, the cathode of the ZD151 is connected to the anode of the Zener diode ZD150, the anode of the diode D150 is connected to the anode of the ZD151, the cathode of the diode D150 is connected to the anode of the LED U3B through a resistor R150, the cathode of the LED U3B is connected to the cathode of a capacitor C201, and a resistor R151 and a capacitor C150 which are connected in parallel are arranged at two ends of the LED U3B; the cooling rectification filter circuit includes: a diode D200 connected to the second secondary winding, a capacitor C202 and a resistor R207 connected in series and disposed at two ends of the diode D200, a resistor R208 connected to a cathode of the diode D200, and a resistor R209 connected in parallel to two ends of the resistor R208, wherein a common terminal of the resistor R208 and the resistor R209 is connected to an anode of the filter capacitor C200, a cathode of the filter capacitor C200 is connected to the other end of the second secondary winding and grounded, one end of the resistor R208 connected to an anode of the filter capacitor C200 is connected to an input terminal of a voltage regulator unit RG1, a ground terminal of the voltage regulator unit RG1 is grounded, and an anode of an output terminal of the output circuit is connected to an input terminal of the voltage regulator unit RG1 through a diode D201;
an output detection feedback circuit connected to the output circuit and detecting an output voltage or current to feed back to the main control unit for constant current protection or constant voltage output, the output detection feedback circuit including: detect output circuit's output voltage or current's detecting element U100, with output circuit connects and inserts among detecting element U100 with detecting element U100 cooperation detection output circuit output current's current sampling resistance, with output circuit's output is connected and inserts among detecting element U100 with detecting element U100 cooperation carry out the divider resistance circuit that output voltage detected, with the optoelectronic coupler U2 that detecting element U100 output is connected, detecting element U100 includes: an amplifier U100A connected to a voltage dividing resistor circuit of the output detection feedback circuit, comparing and judging the divided voltage of the voltage dividing resistor circuit with a reference voltage, and feeding back the result to the control circuit through a photocoupler U2, and an amplifier U100B connected to a current sampling resistor of the output detection feedback circuit, detecting the output current or current change of the output circuit, wherein an inverting input terminal of the amplifier U100A is connected to the reference voltage, a non-inverting input terminal thereof is connected to the divided voltage of the voltage dividing resistor circuit connected thereto, an output current of the output circuit is connected to the inverting input terminal of the amplifier U100B through the current sampling resistor, and is connected to the non-inverting input terminal thereof through a capacitor C510 and is grounded, and the photocoupler U2 includes: the light emitting diode U2B is arranged at a transmitting end, is connected with the output end of the amplifier U100A or the output end of the amplifier U100B and causes current change according to the change of output voltage, and the phototriode U2A is arranged at a receiving end, receives a detection signal of the light emitting diode U2B and transmits the detection signal to the main control unit so as to adjust the output voltage according to the detection signal to output constant current or constant voltage;
the voltage-dividing resistance circuit includes: a resistor R161 connected with the positive output end of the output circuit, a resistor R162 connected with the resistor R161, a variable resistor SVR1 connected with the other end of the resistor 162 and used for changing the voltage division ratio to adjust the output voltage set point, a resistor R160 and a capacitor C160 connected in series and connected in parallel with the two ends of the resistor R161, a resistor R163 connected in parallel with the two ends of the resistor R162, the other end of the variable resistor SVR1 is grounded, an overvoltage protection output voltage output between the resistor R161 and the resistor R162 is connected to the positive input end of the amplifier U100A, the inverting input end of the amplifier U100A is connected to a reference voltage chip SHR500 providing a reference voltage through a resistor R503, the output end of the amplifier U100A is connected to the positive electrode of the light emitting diode U2B through a diode D500 and a resistor R520, the output end of the amplifier U100A is connected to the inverting input end through capacitors C504 and R504, the anode of the reference voltage chip SHR500 is grounded, the cathode is connected to the inverting, The reference end of the reference voltage chip SHR500 is connected to the cathode of the amplifier, the other branch of the cathode of the reference voltage chip SHR500 is grounded through a capacitor C501, and a branch between the cathode of the reference voltage chip SHR500 and the capacitor C501 is connected to the inverting input end of the amplifier U100B through a resistor R505; the output current of the output circuit is connected to the inverting input end of an amplifier U100B through a current sampling resistor consisting of resistors R510 and R511 which are connected in parallel, and is connected to the non-inverting input end of the amplifier through a capacitor C510 and is grounded, the output end of an amplifier U100B is connected to the anode of the light-emitting diode U2B through a diode D510 through a resistor R520, and the output end of the amplifier U100 is fed back to the inverting input end of an amplifier U100B through a capacitor C512 and a resistor R512; the input end of the voltage stabilizing unit RG1 is connected to the power supply end of the amplifier U100A through a resistor R500, the output end of the voltage stabilizing unit RG1 is connected to the power supply end of the amplifier U100A through a resistor R501, one branch of the power supply end of the amplifier U100A is grounded through a capacitor C500, and the other branch of the power supply end of the amplifier U100A is connected to the cathode of a reference voltage chip SHR500 through a resistor R502; the cathode of the light emitting diode U2B is grounded.
2. The switching power supply circuit according to claim 1, further comprising: the switch isolation driving circuit is connected with the switching circuit and drives the switching circuit to work, and the main winding current detection circuit is connected with the main winding and detects the overcurrent of the main winding, and the power supply circuit comprises: with the main control unit is connected the starting circuit who drives the main control unit, switch isolation drive circuit includes: a transformer T2, a T2 primary winding disposed on the primary side of the transformer T2, a T2 primary winding disposed on the secondary side of the transformer T2, an amplifying circuit connected to the T2 primary winding and connected to the driving terminal of the main control unit for amplifying the driving signal, and a T2 secondary winding disposed on the secondary side of the transformer T2, wherein the switching circuit comprises: a switch tube Q1 connected with the first secondary winding of the T2, a switch tube Q2 connected with the second secondary winding of the T2, a main winding is arranged between the switch tube Q1 and the switch tube Q2, and the starting circuit comprises: a first starting resistor or resistor group connected to the rectifying and filtering circuit, a switch tube Q50 connected to the resistor or resistor group, a second starting resistor or resistor group connected to the other end of the switch tube Q50, and a capacitor C37 connected to the switch tube Q50 and charged according to the conduction of the switch tube Q50, wherein one end of the switch tube Q50 is connected to the power supply end of the main control unit; the main winding current detection circuit includes: the current detection circuit comprises a current sensing resistor for converting the current of the main winding into voltage detection, a resistor R60 connected with one end of the current sensing resistor and connected to the detection end of the main control unit, and a capacitor C53 connected with a resistor R60.
3. The switching power supply circuit according to claim 2, wherein the switching transistor Q50 is an N-channel MOS transistor for turning on or off the connection between the drain and the source according to the voltage between the gate and the source, and the first starting resistor or resistor group comprises: resistors R20, R21, R22 and R20 which are connected in series are connected into the rectifying and filtering circuit, a second starting resistor or resistor group comprises a zener diode ZD20, a resistor R24 and a resistor R25 which are connected in series, the negative electrode of the zener diode ZD20 is connected into the rectifying and filtering circuit after being converged with a resistor R20, a resistor R25 is connected into the grid electrode of the MOS tube Q50, a resistor R22 is connected into the drain electrode of the MOS tube Q50, a capacitor C37 is a polar capacitor, the source electrode of the MOS tube Q50 is connected into the positive electrode of the capacitor C37 and the negative electrode of the capacitor C37 and is grounded, the grid electrode of the MOS tube Q50 is grounded through a zener tube ZD50, a capacitor C33 is arranged between the grid electrode and the source electrode of the capacitor C33, two ends of the capacitor C26 are connected in parallel, and the source electrode of the MOS tube Q50 is connected into the power; the amplifying circuit in the switch isolation driving circuit comprises: an NPN triode Q51 and a PNP triode Q52, bases of the triode Q51 and the triode Q52 are connected to a driving end of the main control unit, a collector of the triode Q51 is connected to a power supply end of the main control unit, an emitter of the triode Q51 is connected to an emitter of the triode Q52, an emitter of the triode Q51 or an emitter of the triode Q52 is connected to one end of a primary winding of the T2 through a capacitor C19, a collector of the triode Q52 is connected to the other end of the primary winding of the T2, a collector of the triode Q51 is also connected to the other end of the primary winding of the T2 through a capacitor C20, the switching tubes Q1 and Q2 are N-channel enhancement type MOS tubes, one end of the first secondary winding of the T2 is connected to a gate of the MOS tube Q1 through a resistor R11, the other end of the first secondary winding of the transistor Q1 is connected to a source of the MOS tube Q1, a drain of the MOS tube Q1, the negative electrode of the diode D12 is connected to one end of a first secondary winding of the T2, a resistor R12 is arranged between the grid electrode and the source electrode of the MOS tube Q1, capacitors C13 and C14 which are connected in series are arranged between the drain electrode and the source electrode of the MOS tube Q1, the source electrode of the MOS tube Q1 is also connected to one end of a main winding, the other end of the main winding is connected to the drain electrode of the MOS tube Q1 through a diode D10, a capacitor C26 is further arranged between the two ends of the main winding, the grid electrode of the MOS tube Q2 is connected to one end of a second secondary winding of the T2 through a resistor R15 and a diode D15, the other end of the second secondary winding of the T2 is connected to one end of the main winding through a diode D11, a resistor R15 and a resistor R14 are connected in parallel to the two ends of the diode D15, capacitors C16 and C15 connected in: the resistor R18 and the resistor R19 are connected in parallel, one end of the resistor R18 is connected to the main winding through the MOS tube Q2, the resistor R2 is connected to the source electrode of the MOS tube Q2, and the other end of the resistor R18 is grounded.
4. The switching power supply circuit according to claim 2, further comprising: the setting is in the EMC circuit of rectification filter circuit front end, with rectification filter circuit connects the input voltage detection circuitry who detects input voltage after the rectification, with the remote switch circuit of master control unit communication, power supply circuit still includes: the soft start circuit is connected with the starting circuit, and the transformer type power supply circuit is connected with the starting circuit and connected to the main control unit, and the soft start circuit comprises: the charging circuit comprises a voltage division resistor connected with the starting circuit, a charging capacitor connected with the voltage division resistor, a switch tube Q70 connected with the voltage division resistor and conducted according to the charging condition of the charging capacitor, a resistor R73 connected with the switch tube Q70 and connected to a delay end of the main control unit according to the conduction of a switch tube Q70, wherein one end of the charging capacitor is connected with the voltage division resistor, the other end of the charging capacitor is connected with the feedback end of the main control unit, the other end of the switch tube Q70 is grounded, and the delay end of the main control unit is grounded through a resistor R52; the transformer-type power supply circuit includes: the transformer T1 comprises a primary secondary winding arranged on the primary side of the transformer T1, a chip power supply rectification filter circuit arranged on the primary secondary winding, and a voltage reduction circuit connected with the chip power supply rectification filter circuit and supplying power to the main control unit, wherein the chip power supply rectification filter circuit comprises: a diode D30 provided at one end of the primary secondary winding, a resistor R31 connected to the diode D30, and a capacitor C36 connected to the other end of the resistor R31 and the other end of the primary secondary winding, the step-down circuit including: a switch tube Q30 connected with the resistor R31, and a voltage regulator tube ZD30 connected with the other end of the switch tube Q30 and the other end of the primary secondary winding, wherein the EMC circuit comprises: filter capacitance and common mode inductance, filter capacitance in the EMC circuit includes: an X capacitor disposed across an input line, a Y capacitor disposed between the input line and a ground line, the input voltage detection circuit comprising: the voltage dividing resistor is connected to the input voltage rectified by the rectifying and filtering circuit, and the input voltage detection circuit is connected to the low-voltage detection input end of the main control unit through the voltage division of the voltage dividing resistor; the remote switch circuit includes: remote control trigger device, with remote control trigger device's optoelectronic coupler U4 who connects, optoelectronic coupler U4 includes: the light emitting diode U4B is arranged at the transmitting end, is connected with the remote control trigger device and is triggered and conducted by remote control, and the phototriode U4A is arranged at the receiving end, receives the signal of the light emitting diode U4B and transmits the signal to the main control unit for control.
5. The switch power supply circuit according to claim 4, wherein a voltage dividing resistor in the soft start circuit comprises resistors R and R connected in sequence, one end of the resistor R is connected to the negative electrode of a capacitor C, the end of the resistor R is connected to the ground, the other end of the resistor R is connected to a charging capacitor in the soft start circuit, the charging capacitor in the soft start circuit comprises capacitors C and C connected in parallel, the other end of the capacitor C and C connected in parallel is connected to the feedback end of the master control unit, two ends of the resistor R and R connected in series are provided with a resistor R and a diode D connected in series, one end of the resistor R and R connected to the negative electrode of the capacitor C, the other end of the resistor R is connected to the positive electrode of a diode D, the negative electrode of the diode D is connected to the negative electrode of a resistor C connected in series, the negative electrode of a resistor R and R connected to the ground of a transistor C is connected to the ground, the collector of a voltage stabilizing triode C, the resistor R and the resistor C connected to the ground of the master control unit, the ground, the resistor R and the resistor C is connected between the ground, the resistor R and the ground of the power supply terminal of the power supply unit, the power supply terminal of the power.
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| CN113824304A (en) * | 2021-11-23 | 2021-12-21 | 西安空天紫电等离子体技术有限公司 | Input/output power supply system based on vehicle-mounted plasma driving power supply |
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| CN2938554Y (en) * | 2006-08-29 | 2007-08-22 | Bcd半导体制造有限公司 | Switch mode power supply and its overvoltage protection circuit |
| CN204258271U (en) * | 2014-12-03 | 2015-04-08 | 深圳市京泉华科技股份有限公司 | A kind of under-voltage protective switch of the short circuit supply unit |
| CN206041464U (en) * | 2016-08-26 | 2017-03-22 | 宁波赛耐比光电科技股份有限公司 | Over -temperature protection circuit |
| CN206250751U (en) * | 2016-12-20 | 2017-06-13 | 东莞市乐丰电器科技有限公司 | Switching Power Supply with overheat protector |
| CN209881672U (en) * | 2019-04-15 | 2019-12-31 | 苏州沙丘电子科技有限公司 | Switching power supply circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW200826444A (en) * | 2006-07-27 | 2008-06-16 | Koninkl Philips Electronics Nv | Switch mode power supply for in-line voltage applications |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2938554Y (en) * | 2006-08-29 | 2007-08-22 | Bcd半导体制造有限公司 | Switch mode power supply and its overvoltage protection circuit |
| CN204258271U (en) * | 2014-12-03 | 2015-04-08 | 深圳市京泉华科技股份有限公司 | A kind of under-voltage protective switch of the short circuit supply unit |
| CN206041464U (en) * | 2016-08-26 | 2017-03-22 | 宁波赛耐比光电科技股份有限公司 | Over -temperature protection circuit |
| CN206250751U (en) * | 2016-12-20 | 2017-06-13 | 东莞市乐丰电器科技有限公司 | Switching Power Supply with overheat protector |
| CN209881672U (en) * | 2019-04-15 | 2019-12-31 | 苏州沙丘电子科技有限公司 | Switching power supply circuit |
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