CN206452314U - A kind of Switching Power Supply - Google Patents
A kind of Switching Power Supply Download PDFInfo
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- CN206452314U CN206452314U CN201720107409.2U CN201720107409U CN206452314U CN 206452314 U CN206452314 U CN 206452314U CN 201720107409 U CN201720107409 U CN 201720107409U CN 206452314 U CN206452314 U CN 206452314U
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- 238000001914 filtration Methods 0.000 claims abstract description 19
- 238000004804 winding Methods 0.000 claims description 75
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- 239000003990 capacitor Substances 0.000 claims description 31
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- 229910002601 GaN Inorganic materials 0.000 description 4
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- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The utility model embodiment discloses a kind of Switching Power Supply, and the Switching Power Supply includes filter circuit, rectification circuit and transformer, in addition to：PFC chip.The filter circuit is used to be filtered the ac signal of input, the electromagnetic interference in suppression circuit；The input of the rectification circuit is connected with the output end of the filter circuit, for being d. c. voltage signal by the ac signal rectification after filtering process；The PFC chip is connected with the input of the transformer, and the d. c. voltage signal for the input to the transformer carries out PFC and adjustment, to improve the power factor of power supply, while so that the transformer exports constant voltage.It by using above-mentioned Switching Power Supply, may be such that the power of power network is fully utilized, can also reach reduction power volume, cost-effective effect.
Description
Technical Field
The embodiment of the utility model provides a relate to power technical field, especially relate to a switching power supply.
Background
With the increasing global energy shortage, energy conservation and emission reduction become the common pursuit targets of people. It is very important to improve the utilization efficiency of the switching power supply.
For a switching Power supply with an output Power of 75W or more, the state requires that the Power Factor value is greater than 0.9, and therefore, in order to make full use of the Power of the national grid, a Power Factor Correction (PFC) circuit needs to be added, that is, a rectified and output voltage signal is chopped, so that the voltage and the current are in the same phase. And then the chopped voltage signal is output to the transformer after being filtered by the high-voltage electrolytic capacitor, and then the voltage signal in the winding of the transformer is controlled, so that the transformer has stable output (the process can be summarized into a traditional switching power supply topological structure). However, since the power supply adopts such a topology, the cost of the power supply will increase (e.g., a relatively expensive high-voltage large electrolytic capacitor is needed), and the area of a PCB (Printed Circuit Board) will also increase. Meanwhile, because the existing power factor correction circuit generally adopts an external MOS tube, and the existing MOS has the characteristics of low switching speed, large loss, high temperature rise and the like, the output power of the switching power supply is also reduced.
For electronic products with output power of less than 75W, the state has no requirement on the power factor, an electrolytic capacitor is also needed on the primary side of the transformer to filter the rectified voltage signal, and the transformer generates output voltage after the filtered voltage signal is output to the transformer. However, the use of electrolytic capacitors in the prior art also reduces the output power of the power supply.
Therefore, due to the reasons, the power factor of the existing switching power supply is low, so that the power of a power grid is not fully utilized, and meanwhile, the existing switching power supply is large in size and high in cost.
SUMMERY OF THE UTILITY MODEL
An embodiment of the utility model provides a switching power supply to it is low to solve current switching power supply's power factor, and current switching power supply's is bulky simultaneously and problem with high costs.
The embodiment of the utility model provides a switching power supply, including filter circuit, rectifier circuit and transformer, switching power supply still includes: a power factor correction chip; wherein,
the filter circuit is used for filtering an input alternating current signal and suppressing electromagnetic interference in the circuit;
the input end of the rectifying circuit is connected with the output end of the filter circuit and is used for rectifying the alternating current signals after filtering into direct current voltage signals;
the power factor correction chip is connected with the input end of the transformer and used for performing power factor correction and adjustment on a direct current voltage signal at the input end of the transformer so as to improve the power factor of a power supply and enable the transformer to output constant voltage.
Further, the transformer includes a primary winding, an auxiliary winding, and a secondary winding; wherein,
the primary winding is connected with the output end of the rectifying circuit and used for providing an input voltage signal;
the secondary winding is connected with a load and used for outputting power supply voltage according to the input voltage signal and supplying power to the load;
the auxiliary winding is arranged on the same side as the primary winding and used for converting the power supply voltage into an auxiliary voltage signal according to the turn ratio of the transformer.
Further, the switching power supply further includes:
the starting circuit is connected with the rectifying circuit and used for generating a starting voltage signal according to the rectified electric signal;
and the sampling circuit is connected with the auxiliary winding of the transformer and used for detecting the auxiliary voltage signal and generating a sampling voltage signal to be output to the power factor correction chip.
Further, the switching power supply further includes:
and the secondary rectification filter circuit is connected with the secondary winding of the transformer and used for rectifying the power supply voltage to obtain a direct current signal to supply power to a load.
Further, the switching power supply further comprises a first diode and a first capacitor; wherein,
the positive end of the first diode is connected with the auxiliary winding of the transformer, and the negative end of the first diode is connected with the power factor correction chip and used for rectifying a voltage signal of the auxiliary winding of the transformer and outputting a direct-current voltage signal to charge the first capacitor;
the first capacitor is connected between the cathode end of the first diode and the ground wire and used for supplying power to the power factor correction chip.
Furthermore, the power factor correction chip comprises a voltage stabilizing module, a PWM generator, a Schmitt trigger, a buffer and an MOS tube which are connected in sequence; wherein,
the input end of the voltage stabilizing module is connected with the auxiliary winding of the transformer, and the output end of the voltage stabilizing module is respectively connected with the PWM generator, the Schmitt trigger and the buffer and used for supplying power to the PWM generator, the Schmitt trigger and the buffer;
the PWM generator is connected with an auxiliary winding of the transformer, and outputs a pulse signal to the Schmitt trigger through a sampling voltage signal according to the sampling circuit while performing power factor correction on the direct current voltage of a primary winding of the transformer;
the Schmitt trigger is used for adjusting the pulse signal output by the PWM generator and outputting a rectangular wave signal to the buffer;
the buffer is used for controlling the on and off of the MOS tube according to the rectangular wave signal;
the MOS tube is connected with the primary winding of the transformer and used for controlling the transformer to oscillate and outputting constant voltage.
Further, the MOS tube is made of GaN materials.
Further, the pfc chip further includes: the circuit comprises a first resistor, a comparator and a current limiting setting module; wherein,
the first resistor is connected between the source electrode of the MOS tube and the ground wire, and the connection point of the first resistor and the MOS tube is used as a comparison point and is connected to the in-phase end of the comparator for inputting comparison voltage;
the current limiting setting module is connected with the inverting end of the comparator and used for inputting reference voltage;
and the output end of the comparator is connected with the PWM generator and used for outputting control voltage according to the comparison voltage and the reference voltage so as to control the PWM generator to work.
Further, the rectifying circuit is a full-wave rectifying circuit.
Further, the starting circuit comprises a second resistor and a third resistor which are sequentially connected in series; wherein,
the circuit formed by connecting the second resistor and the third resistor in series is connected between the output end of the rectifying circuit and the ground wire;
and a connection point between the second resistor and the third resistor is used as a starting point to obtain a starting voltage, and the starting point is connected to the power factor correction chip and used for driving the power factor correction chip to work according to the starting voltage.
Furthermore, the sampling circuit comprises a fourth resistor and a fifth resistor which are sequentially connected in series; wherein,
a circuit formed by connecting the fourth resistor and the fifth resistor in series is connected in parallel to two ends of an auxiliary winding of the transformer;
and a connection point between the fourth resistor and the fifth resistor is used as a sampling point and is connected to the power factor correction chip, and the connection point is used for acquiring a sampling voltage signal from the sampling point.
Further, the secondary rectifying and filtering circuit comprises a second diode, a second capacitor and a third capacitor; wherein,
the positive end of the second diode is connected with the secondary winding of the transformer, and the negative end of the second diode is connected with the positive end of the second capacitor;
the negative electrode of the second capacitor is connected with the secondary ground;
the third capacitor is connected in parallel to two ends of the second capacitor.
The embodiment of the utility model provides a switching power supply, this switching power supply include filter circuit, rectifier circuit and transformer, still include power factor correction chip. The filter circuit can filter the input alternating current signal and inhibit the electromagnetic interference in the circuit; the input end of the rectifying circuit is connected with the output end of the filter circuit, and the alternating current signal after filtering processing can be rectified into a direct current voltage signal; the power factor correction chip is connected with the input end of the transformer, so that the power factor correction and adjustment can be performed on the direct current voltage signal at the input end of the transformer, the power factor of the power supply is improved, and the transformer outputs constant voltage. The application of the power factor chip can make full use of the power grid, and can also achieve the effects of reducing the size of the power supply and saving the cost.
Drawings
Fig. 1 is a block diagram of a switching power supply according to a first embodiment of the present invention;
fig. 2 is a schematic structural diagram of a switching power supply according to a second embodiment of the present invention;
fig. 3 is a schematic circuit diagram of a preferred switching power supply according to a second embodiment of the present invention;
fig. 4 is a schematic circuit diagram of a preferred switching power supply according to a second embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Example one
Fig. 1 is a block diagram of a switching power supply according to an embodiment of the present invention. The switching power supply can be used in televisions, adapters, liquid crystal displays, projectors, medical instruments or military industrial equipment. As shown in fig. 1, the switching power supply 100 includes a filter circuit 110, a rectifier circuit 120, a transformer 130, and a power factor correction chip 140. Wherein,
the filter circuit 110 is used for filtering an input ac signal and suppressing electromagnetic interference in the circuit.
Illustratively, the filter circuit in the present embodiment is preferably an EMI (Electromagnetic Interference) filter circuit, which is used to filter out differential mode Interference and common mode Interference in the ac signal.
The input end of the rectifying circuit 120 is connected to the output end of the filtering circuit 110, and is configured to rectify the filtered ac signal into a dc voltage signal.
Preferably, the rectifier circuit is a full-wave rectifier circuit.
The pfc chip 140 is connected to the input terminal of the transformer 130, and is configured to perform pfc and regulation on the dc voltage signal at the input terminal of the transformer 130, so as to increase the power factor of the power supply and enable the transformer 130 to output a constant voltage.
It should be noted that the embodiment of the present invention provides a power factor correction chip, which can directly connect the rectified voltage signal to a transformer, and then perform power factor correction through the power factor chip, so as to improve the power factor value of an electronic product. Because the process of power factor correction can be integrated inside the power factor correction chip and accomplished, consequently, the filtering process after the power factor correction also can be carried out in the power factor correction chip simultaneously, promptly through adopting the utility model provides a switching power supply can save the high-pressure electrolytic capacitor on power former limit, improves mains power because of numerical value. Therefore, the execution process of the peripheral circuit is integrated into the power factor chip, so that the power factor correction can be completed, the utilization rate of the power supply to a power grid is improved, the size of the switching power supply can be reduced, and the cost is reduced. Thirdly, since the power factor correction chip can also adjust the output voltage of the transformer, the transformer can output a constant voltage through the power factor correction chip.
Specifically, the transformer 130 preferably includes a primary winding, an auxiliary winding, and a secondary winding; the primary winding is connected with the output end of the rectifying circuit and used for providing an input voltage signal; the secondary winding is connected with the load and used for outputting power supply voltage according to the input voltage signal and supplying power to the load; the auxiliary winding is arranged on the same side as the primary winding and used for converting the power supply voltage into an auxiliary voltage signal according to the turn ratio of the transformer. The auxiliary voltage signal may be used for sampling or other auxiliary processing functions.
Since the transformer is located between the primary and secondary of the switching power supply, it can serve to isolate the primary high voltage from the secondary low voltage.
The embodiment provides a switching power supply which comprises a filter circuit, a rectifying circuit, a transformer and a power factor correction chip. The filter circuit can filter the input alternating current signal and inhibit the electromagnetic interference in the circuit; the input end of the rectifying circuit is connected with the output end of the filter circuit, and the alternating current signal after filtering processing can be rectified into a direct current voltage signal; the power factor correction chip is connected with the input end of the transformer, so that the power factor correction and adjustment can be performed on the direct-current voltage signal at the input end of the transformer, the power factor of the power supply is improved, the power of a power grid is fully utilized, and meanwhile, the transformer can output constant voltage. The application of the power factor chip can also achieve the effects of reducing the size of the power supply and saving the cost.
Example two
Fig. 2 is the structural schematic diagram of a switching power supply provided by the second embodiment of the present invention, the present embodiment further refines the power factor correction chip on the basis of the above embodiment, and the starting circuit, the sampling circuit and the secondary rectification filter circuit are also added at the same time. As shown in fig. 2, the switching power supply 200 includes a filter circuit 210, a rectifying circuit 220, a start circuit 230, a transformer 240, a sampling circuit 250, a power factor correction chip 260, and a secondary rectifying filter circuit 270. Fig. 3 is a schematic circuit diagram of a preferred switching power supply according to a second embodiment of the present invention. Referring to fig. 3, the following first describes each component in the pfc chip 260, its connection relationship and operation principle, and then describes each circuit:
1. specific description of the power factor correction chip:
the power factor correction chip 260 may include a voltage regulation module 261, a PWM generator 262, a schmitt trigger 263, a buffer 264 and a MOS transistor 265 connected in sequence; wherein,
the input terminal of the voltage stabilizing module 261 is connected to the auxiliary winding of the transformer 240, and the output terminal is connected to the PWM generator 262, the schmitt trigger 263 and the buffer 264, respectively, for supplying power to the PWM generator 262, the schmitt trigger 263 and the buffer 264.
Specifically, in the embodiment of the present invention, the output terminals 1 and 2 of the voltage stabilizing module 261 will output positive voltage to power the PWM generator 262 and the schmitt trigger 263, respectively. The output terminal 3 outputs a negative voltage to supply the buffer 264.
The PWM generator 262 is connected to the auxiliary winding of the transformer 240, and outputs a pulse signal to the schmitt trigger 263 by sampling a voltage signal according to the sampling circuit 250 while performing power factor correction on the dc voltage of the primary winding of the transformer 240.
Therefore, the voltage of the primary winding of the transformer is power factor corrected by the PWM generator 262, so that the voltage and the current of the utility power are supplied in the same phase, the power factor is improved, and the actual electric energy of the utility power is saved.
The schmitt trigger 263 adjusts the pulse signal output from the PWM generator 262, and outputs a rectangular wave signal to the buffer 264.
It should be noted that waveform distortion generally occurs after the rectangular pulse obtained from the PWM generator 262 is transmitted. For example, when the capacitance on the transmission line is large, the rising edge of the waveform will be significantly slowed; when the transmission line is long and the impedance of the receiving end is not matched with the impedance of the transmission line, oscillation phenomena are generated on the rising edge and the falling edge of the waveform; or when other pulse signals are superimposed on the rectangular pulse signal through distributed capacitance between wires or a common power supply line, additional noise appears on the signal. Due to the reasons, the switching efficiency of the MOS tube is easily interfered, so that the working state of the MOS tube is unstable. By using the Schmitt trigger to convert the periodic signal with slow edge change into the rectangular pulse signal with steep edge, an ideal rectangular pulse waveform can be obtained, and the effective control of the MOS tube is realized.
The buffer 264 is used for controlling the on and off of the MOS tube 265 according to the rectangular wave signal.
Specifically, since the output terminal 3 of the voltage regulation module 261 provides the buffer 264 with a negative voltage, the buffer 264 outputs a negative voltage.
And the MOS tube 265 is connected with the primary winding of the transformer and used for controlling the transformer to oscillate and outputting constant voltage.
Preferably, the MOS transistor in the embodiment of the present invention is a gallium nitride (GaN) MOS transistor. Because the gallium nitride MOS tube has the characteristics of small volume, low power consumption, low temperature rise, low conduction loss, low switching loss and the like, the gallium nitride MOS tube is integrated into the power factor correction chip, so that the working frequency of the switching power supply can be improved, the anti-interference capability of the MOS tube is improved, the volume of the switching power supply is further reduced, and the cost is reduced.
Specifically, since the driving voltage of the gallium nitride MOS transistor is a negative voltage, the MOS transistor can be effectively driven by the negative voltage output from the buffer.
Further, the pfc chip 260 further includes: a first resistor R1, a comparator 266, and a current limit setting module 267; the first resistor R1 is connected between the source of the MOS transistor 265 and the ground, and a connection point of the first resistor R1 and the MOS transistor 265 is used as a comparison point, connected to the non-inverting terminal of the comparator 266, and used for inputting a comparison voltage; the current limit setting 267 module is connected with the inverting terminal of the comparator 266 and is used for inputting a reference voltage; an output terminal of the comparator 266 is connected to the PWM generator 262 for outputting a control voltage according to the comparison voltage and the reference voltage to control the PWM generator 262 to operate.
In one implementation, the current limit setting module 267 generates a reference voltage to be compared with the sampled voltage of the transformer. The first resistor R1 is connected to the MOS transistor 265, and can obtain the current of the MOS transistor, and the voltage of the primary winding of the transformer can be obtained as a comparison voltage by sampling the current and compared with the reference voltage. When the comparison voltage is less than the reference voltage, the comparator 266 outputs a control signal to control the PWM generator 262 to operate. When the comparison voltage is greater than the reference voltage, the comparator 266 inverts the output control information to control the PWM generator to stop working. Therefore, the PWM generator can be effectively controlled to work through the first resistor, the comparator and the current limiting setting module.
Further, a resistor R7 may be connected between the current limiting setting module 267 and ground as an overcurrent protection resistor, so that the current limiting setting module generates a certain reference voltage.
2. The starting circuit 230, the sampling circuit 250 and the secondary rectifying and filtering circuit 270 are specifically described below:
(1) a start circuit 230 connected to the rectifying circuit 220 for generating a start voltage signal according to the rectified electrical signal;
illustratively, as shown in fig. 3, the start-up circuit 230 includes a second resistor R2 and a third resistor R3; the circuit formed by connecting the second resistor R2 and the third resistor R3 in series is connected between the output end of the rectifying circuit 220 and the ground wire; the connection point between the second resistor R2 and the third resistor R3 is used as a starting point to obtain a starting voltage, and the starting point is connected to the power factor correction chip 260 for driving the power factor correction chip 260 to operate according to the starting voltage.
(2) And the sampling circuit 250 is connected with the auxiliary winding of the transformer and is used for detecting the auxiliary voltage signal and generating a sampling voltage signal to be output to the power factor correction chip 260.
Specifically, as shown in fig. 3, the sampling circuit 250 includes a fourth resistor R4 and a fifth resistor R5 connected in series in sequence; the circuit formed by connecting the fourth resistor R4 and the fifth resistor R5 in series is connected in parallel to two ends of the auxiliary winding of the transformer 240; the connection point between the fourth resistor R4 and the fifth resistor R5 is used as a sampling point, and is connected to the power factor correction chip 260 for obtaining a sampling voltage signal from the sampling point.
Further, the switching power supply 200 further includes a first diode D1 and a first capacitor C1; the positive end of the first diode D1 is connected to the auxiliary winding of the transformer 240, and the negative end of the first diode D1 is connected to the power factor correction chip 260, and is configured to rectify a voltage signal of the auxiliary winding of the transformer 240 and output a dc voltage signal to charge the first capacitor C1; the first capacitor C1 is connected between the negative terminal of the first diode D1 and ground for supplying power to the pfc chip 260.
(3) And a secondary rectifying and filtering circuit 270 connected to the secondary winding of the transformer 240, for rectifying the power supply voltage output by the secondary winding to obtain a dc signal to supply power to the load.
Specifically, the secondary rectifying and filtering circuit 270 includes a second diode D2, a second capacitor C2, and a third capacitor C3; the positive terminal of the second diode D2 is connected with the secondary winding of the transformer, and the negative terminal of the second diode C2 is connected with the positive terminal of the second capacitor C2; the negative terminal of the second capacitor C2 is connected to the secondary ground; the third capacitor C3 is connected in parallel across the second capacitor C2.
Furthermore, because a high-voltage electrolytic capacitor is omitted in the secondary rectifying and filtering circuit, the output ripple voltage is larger. Therefore, the linear regulation module 271 can be increased to filter out the ripple voltage.
Specifically, fig. 4 is a schematic circuit diagram of a preferred switching power supply according to the second embodiment of the present invention, and with reference to fig. 4, on the basis of the second embodiment, the following specifically describes the operating principle of the switching power supply in combination with the starting circuit, the sampling circuit and the secondary rectifying and filtering circuit:
after the high-voltage signal rectified by the rectifying circuit passes through the second resistor R2 and the third resistor R3, the power-on of the switching power supply is detected by the resistors R2 and R3, and the PWM generator starts to work. Meanwhile, the rectified voltage passes through the 1 st pin of the transformer, then is output from the 3 pins and is connected with a power factor correction chip (actually connected with the drain electrode of an MOS tube integrated in the chip, in the figure, the D pin of the chip), and the 4 pins of the transformer are connected with the power supply end of the chip.
And in the normal working process of the power factor correction chip, the auxiliary winding of the transformer supplies power to the power factor correction chip. The specific process is as follows: the voltage of the auxiliary winding of the transformer charges a first capacitor C1 through a first diode D1, and when the voltage of C1 rises to the starting voltage of the power factor correction chip, the chip starts to drive the whole switching power supply system to work. Meanwhile, the power factor correction chip can also perform power factor correction on a direct-current voltage signal of the primary winding of the transformer, namely, the voltage signal is chopped into a square wave signal (specifically, a PWM generator in the chip works), so that the current and the voltage have the same phase, the power factor of a power supply is further improved, and the power of a power grid is utilized to the maximum extent.
The switching power supply is provided with a sampling circuit and is connected with an auxiliary winding of the transformer. As shown in fig. 4, the fourth resistor R4 and the fifth resistor R5 are connected as sampling resistors to the secondary winding of the transformer, and the voltage of the secondary winding and the voltage of the auxiliary winding are proportional to each other due to the turn ratio of the auxiliary winding and the secondary winding. Therefore, the output voltage of the secondary winding can be reflected by obtaining the voltage of the auxiliary winding. Therefore, taking the connection point of R4 and R5 as a sampling point, a sampled voltage can be obtained from the sampling point to reflect the output voltage of the secondary winding. By connecting the sampling point with the power factor chip circuit, the output voltage of the secondary winding of the transformer can be fed back to the power factor correction chip in the form of sampling voltage, and then the output voltage is adjusted. For example, when the voltage output by the secondary winding of the transformer is low, the sampled voltages obtained through R4 and R5 are correspondingly low. At this time, by increasing the duty ratio of the pulse signal output by the PWM generator, the conduction time of the MOS transistor can be increased, so that the charging time of the primary winding of the transformer is increased, and the output voltage of the transformer is increased. Based on the same principle as the above process, when the output voltage of the transformer is high, the output voltage of the transformer can be lowered by reducing the duty ratio of the pulse signal. Therefore, the sampling circuit can ensure that the transformer has stable output voltage.
When the MOS transistor is turned on, the primary winding of the transformer stores energy, and the secondary winding discharges through the second capacitor and the third capacitor to provide voltage for the load; when the MOS tube is turned off, the primary winding of the transformer releases energy, and the secondary winding supplies the output voltage to a load. Therefore, the transformer can oscillate by controlling the on and off of the MOS tube to output a constant voltage.
It should be noted that, the secondary rectifying and filtering circuit can rectify the voltage induced by the secondary winding of the transformer through the second diode D2, and then obtain a smooth and stable dc voltage after being filtered by the capacitors (C2 and C3), so as to provide a high-precision and stable power supply for the use of the terminal product.
The embodiment provides a switching power supply, and on the basis of the above embodiment, by integrating the MOS transistor into the power factor core, the embodiment can further reduce the size of the switching power supply and reduce the cost while improving the power factor value. Meanwhile, the starting circuit, the sampling circuit, the secondary pole rectifying and filtering circuit, the power factor correcting chip and the rectifying circuit, the filtering circuit and the transformer provided by the embodiment are combined, the voltage output by the secondary winding of the transformer can be fed back to the power factor correcting chip, the on-off time of the internal MOS tube is controlled by adjusting the duty ratio through the power factor correcting chip, and then the output voltage of the transformer can be stable. Therefore, the switching power supply circuit provided by the novel embodiment of the present application has high operating frequency, large output power, small size and low cost.
It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
Claims (10)
1. The utility model provides a switching power supply, includes filter circuit, rectifier circuit and transformer, its characterized in that, switching power supply still includes: a power factor correction chip; wherein,
the filter circuit is used for filtering an input alternating current signal and suppressing electromagnetic interference in the circuit;
the input end of the rectifying circuit is connected with the output end of the filter circuit and is used for rectifying the alternating current signals after filtering into direct current voltage signals;
the power factor correction chip is connected with the input end of the transformer and used for performing power factor correction and adjustment on a direct current voltage signal at the input end of the transformer so as to improve the power factor of a power supply and enable the transformer to output constant voltage.
2. The switching power supply according to claim 1, wherein the transformer includes a primary winding, an auxiliary winding, and a secondary winding; wherein,
the primary winding is connected with the output end of the rectifying circuit and used for providing an input voltage signal;
the secondary winding is connected with a load and used for outputting power supply voltage according to the input voltage signal and supplying power to the load;
the auxiliary winding is arranged on the same side as the primary winding and used for converting the power supply voltage into an auxiliary voltage signal according to the turn ratio of the transformer.
3. The switching power supply according to claim 2, further comprising:
the starting circuit is connected with the rectifying circuit and used for generating a starting voltage signal according to the rectified electric signal;
and the sampling circuit is connected with the auxiliary winding of the transformer and used for detecting the auxiliary voltage signal and generating a sampling voltage signal to be output to the power factor correction chip.
4. The switching power supply according to claim 3, further comprising:
and the secondary rectification filter circuit is connected with the secondary winding of the transformer and used for rectifying the power supply voltage to obtain a direct current signal to supply power to a load.
5. The switching power supply according to claim 3, further comprising a first diode and a first capacitor; wherein,
the positive end of the first diode is connected with the auxiliary winding of the transformer, and the negative end of the first diode is connected with the power factor correction chip and used for rectifying a voltage signal of the auxiliary winding of the transformer and outputting a direct-current voltage signal to charge the first capacitor;
the first capacitor is connected between the cathode end of the first diode and the ground wire and used for supplying power to the power factor correction chip.
6. The switching power supply according to claim 3, wherein the power factor correction chip comprises a voltage stabilizing module, a PWM generator, a Schmitt trigger, a buffer and a MOS tube which are connected in sequence; wherein,
the input end of the voltage stabilizing module is connected with the auxiliary winding of the transformer, and the output end of the voltage stabilizing module is respectively connected with the PWM generator, the Schmitt trigger and the buffer and used for supplying power to the PWM generator, the Schmitt trigger and the buffer;
the PWM generator is connected with an auxiliary winding of the transformer, and outputs a pulse signal to the Schmitt trigger through a sampling voltage signal according to the sampling circuit while performing power factor correction on the direct current voltage of a primary winding of the transformer;
the Schmitt trigger is used for adjusting the pulse signal output by the PWM generator and outputting a rectangular wave signal to the buffer;
the buffer is used for controlling the on and off of the MOS tube according to the rectangular wave signal;
the MOS tube is connected with the primary winding of the transformer and used for controlling the transformer to oscillate and outputting constant voltage.
7. The switching power supply according to claim 6, wherein the MOS transistor is a GaN MOS transistor.
8. The switching power supply according to claim 6, wherein: the power factor correction chip further comprises: the circuit comprises a first resistor, a comparator and a current limiting setting module; wherein,
the first resistor is connected between the source electrode of the MOS tube and the ground wire, and the connection point of the first resistor and the MOS tube is used as a comparison point and is connected to the in-phase end of the comparator for inputting comparison voltage;
the current limiting setting module is connected with the inverting end of the comparator and used for inputting reference voltage;
and the output end of the comparator is connected with the PWM generator and used for outputting control voltage according to the comparison voltage and the reference voltage so as to control the PWM generator to work.
9. The switching power supply according to claim 3, characterized in that: the starting circuit comprises a second resistor and a third resistor which are sequentially connected in series; wherein,
the circuit formed by connecting the second resistor and the third resistor in series is connected between the output end of the rectifying circuit and the ground wire;
and a connection point between the second resistor and the third resistor is used as a starting point to obtain a starting voltage, and the starting point is connected to the power factor correction chip and used for driving the power factor correction chip to work according to the starting voltage.
10. The switching power supply according to claim 3, characterized in that: the sampling circuit comprises a fourth resistor and a fifth resistor which are sequentially connected in series; wherein,
a circuit formed by connecting the fourth resistor and the fifth resistor in series is connected in parallel to two ends of an auxiliary winding of the transformer;
and a connection point between the fourth resistor and the fifth resistor is used as a sampling point and is connected to the power factor correction chip, and the connection point is used for acquiring a sampling voltage signal from the sampling point.
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| CN201720107409.2U CN206452314U (en) | 2017-01-25 | 2017-01-25 | A kind of Switching Power Supply |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107994784A (en) * | 2017-12-29 | 2018-05-04 | 重庆希诺达通信有限公司 | A kind of ultrathin high-power ACDC Switching Power Supplies |
| CN111987911A (en) * | 2020-06-08 | 2020-11-24 | 江苏理工学院 | DCDC converter based on gallium nitride |
-
2017
- 2017-01-25 CN CN201720107409.2U patent/CN206452314U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107994784A (en) * | 2017-12-29 | 2018-05-04 | 重庆希诺达通信有限公司 | A kind of ultrathin high-power ACDC Switching Power Supplies |
| CN111987911A (en) * | 2020-06-08 | 2020-11-24 | 江苏理工学院 | DCDC converter based on gallium nitride |
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