CN111277128A - Flyback converter starting circuit and starting method based on high-voltage input - Google Patents
Flyback converter starting circuit and starting method based on high-voltage input Download PDFInfo
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- CN111277128A CN111277128A CN201811481414.5A CN201811481414A CN111277128A CN 111277128 A CN111277128 A CN 111277128A CN 201811481414 A CN201811481414 A CN 201811481414A CN 111277128 A CN111277128 A CN 111277128A
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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
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Abstract
The invention provides a flyback converter starting circuit and a starting method based on high-voltage input, wherein a high-voltage battery provides an input source for a flyback converter; the high-voltage battery converts high-voltage electricity into low-voltage electricity through the input starting circuit and provides input voltage for the control chip, the input starting circuit charges the capacitor, a first electrode of the capacitor is connected with the input end of the control chip and provides the input voltage for the control chip, and after the control chip normally operates, the control chip provides a control signal for a switching MOS (metal oxide semiconductor) tube of the flyback converter; the flyback converter starts to work, and the output end of the flyback converter provides output voltage to a first electrode of the capacitor; the self-shutdown circuit shuts off the input starting circuit, so that the input starting circuit stops charging the first electrode of the capacitor, and power consumption caused by the input starting circuit in normal operation is reduced.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a flyback converter starting circuit and a starting method based on high-voltage input.
Background
With the fact that the circuit structure of the vehicle-mounted inverter is more and more complex, in order to meet different functional requirements, more and more auxiliary power supplies are arranged in the inverter, a flyback converter (flyback) is usually adopted as a circuit of the auxiliary power supplies in the vehicle-mounted inverter, a simple main circuit topology can be shown in figure 1, the topology can be regarded as an isolation transformer to replace a buck-boost converter of a conventional single-winding inductor, and namely the circuit can achieve both a boost function and a buck function; the transformer has the basic function of an inductor and also comprises the basic function of the transformer, so that the transformer can store energy like a conventional inductor and can also be electrically isolated like a transformer, and the transformer can be regarded as a multi-winding inductor. Fig. 1 shows only the simplest main circuit topology, and in normal application, there are some circuits such as RCD circuit, PWM control chip, voltage and current sampling circuit, etc. For an auxiliary power supply in a conventional vehicle-mounted inverter, input voltage is obtained from a low-voltage battery, voltage reduction is converted into multi-path output power supply, and therefore the requirement on voltage stress of components in a circuit is low.
However, for the popularization of the existing new energy automobile, various working conditions of the automobile are more complicated, as shown in fig. 2, a high-voltage battery 10 is also added for the application of the new energy automobile, and when the vehicle-mounted inverter is in abnormal power supply, an auxiliary power supply (flyback converter 20) in an emergency situation is needed to drive and supply power to core devices IGBT (lower half-bridge arm drive power supply 101 and upper half-bridge arm drive power supply 102) in the inverter, so that the inverter can take some emergency measures in the emergency state; when the normal power supply is abnormal, the input electricity of the flyback converter 20 can only come from the high-voltage battery 10, and belongs to single power supply, namely, the low-voltage battery and the like can not supply power to the circuit in the vehicle-mounted inverter, and all the electricity of the vehicle-mounted inverter can only come from the high-voltage battery; thus, the conventional auxiliary power supply is not suitable for use, because the input voltage of the control chip 30 of the conventional auxiliary power supply is generally not higher than 60V, so that the flyback circuit designed to be suitable for the high-voltage input condition can only be used for processing the input voltage and then supplying power to the flyback control chip 30.
Conventional high voltage input activation (as shown in fig. 3) typically uses an RC circuit to power the control chip 30 by charging a capacitor, which has some disadvantages in the on-board system: 1) the selection of the energy storage capacitor C in the RC circuit is near the critical input voltage of the control chip, because the fluctuation reduction of the capacitor voltage is larger than the hysteresis voltage difference of the input voltage of the control chip, the control chip can be repeatedly started to generate unstable work, and in order to ensure that the control chip can not generate the problem, the capacitance value of the capacitor C is usually selected to be larger; if the ceramic capacitor or the film capacitor is selected, the occupied area of the PCB is large, and the cost is high; the electrolytic capacitor has the problems of service life and volume; 2) the capacitor charging time does not necessarily completely conform to the theoretical calculation, and the charging voltage is different due to the difference of the charging time, so that the unreliable time and voltage can cause the risk of supplying power to the control chip.
Aiming at the defects of the scheme, the invention provides a starting scheme based on a high-voltage input flyback circuit, which aims to supply power to a control chip after the high-voltage input is converted by a starting circuit, so that the control chip can normally supply power and can normally work in the whole wide input voltage range from low voltage to high voltage, the flyback can normally output, meanwhile, the starting speed is accelerated, and the static power consumption of the circuit after starting is greatly reduced.
Disclosure of Invention
The invention aims to provide a flyback converter starting circuit and a starting method based on high-voltage input, and aims to solve the problems that a control chip of a flyback converter powered by a high-voltage battery is large in power supply capacitance or unstable in input voltage.
In order to solve the technical problem, the invention provides a flyback converter starting circuit based on high-voltage input, wherein a high-voltage battery provides input voltage for the flyback converter starting circuit based on high-voltage input, the high-voltage battery provides an input source for a flyback converter, and the flyback converter starting circuit based on high-voltage input provides a control signal for a control chip of the flyback converter, and the flyback converter starting circuit based on high-voltage input is characterized by comprising an input starting circuit and a self-shutdown circuit, wherein:
the high-voltage battery provides input voltage for the control chip through the input starting circuit, the input voltage is lower than the output voltage of the high-voltage battery, the input starting circuit charges a capacitor, the voltage on a first electrode of the capacitor reaches and is kept on the input voltage of the control chip, the first electrode of the capacitor is connected with the input end of the control chip and provides the input voltage for the control chip, and a second electrode of the capacitor is grounded;
after the control chip normally operates, a switching signal is provided for a switching MOS (metal oxide semiconductor) tube of the flyback converter;
the flyback converter starts to work, the output end of the flyback converter provides output voltage to the first electrode of the capacitor, and the output voltage enables the voltage on the first electrode of the capacitor to reach and be kept on the input voltage of the control chip;
the self-shutdown circuit shuts off the input startup circuit to cause the input startup circuit to stop charging the first electrode of the capacitor.
Optionally, in the flyback converter starting circuit based on high-voltage input, the input starting circuit includes a plurality of resistors, a second voltage regulator and a field effect transistor, where:
the resistors are connected in series to form a series circuit, one end of the series circuit is connected with the high-voltage battery, and the other end of the series circuit is connected with the grid electrode of the field effect transistor and the cathode of the second voltage regulator tube;
the anode of the second voltage regulator tube is grounded, the drain of the field effect transistor is connected with the high-voltage battery, and the source of the field effect transistor is coupled to the first electrode of the capacitor.
Optionally, in the flyback converter starting circuit based on the high-voltage input, the number of the plurality of resistors is greater than 1.
Optionally, in the flyback converter starting circuit based on high-voltage input, the field effect transistor is a P-channel field effect transistor.
Optionally, in the flyback converter starting circuit based on high-voltage input, the input starting circuit further includes a first diode, where:
the cathode of the first diode is connected with the capacitor, and the anode of the first diode is connected with the source electrode of the field effect transistor.
Optionally, in the flyback converter starting circuit based on high-voltage input, the self-shutdown circuit includes a first voltage regulator tube, a first voltage-dividing resistor, a second voltage-dividing resistor, and a triode, where:
the cathode of the first voltage-stabilizing tube is connected with the output end of the flyback converter, the anode of the first voltage-stabilizing tube is connected with one end of the first voltage-dividing resistor, the other end of the first voltage-dividing resistor is connected with one end of the second voltage-dividing resistor and the base electrode of the triode, and the other end of the second voltage-dividing resistor is grounded;
and the collector electrode of the triode is connected with the grid electrode of the field effect transistor, and the emitter electrode of the triode is grounded.
Optionally, in the flyback converter starting circuit based on the high-voltage input, the triode is an NPN-type triode.
Optionally, in the flyback converter starting circuit based on high-voltage input, the flyback converter starting circuit based on high-voltage input further includes a second diode, a cathode of the second diode is connected to the first electrode of the capacitor, and an anode of the second diode is connected to the output end of the flyback converter.
Optionally, in the flyback converter starting circuit based on the high-voltage input, the supply voltage of the high-voltage battery is 60V.
The invention also provides a flyback converter starting method based on high-voltage input, which comprises the following steps:
the flyback converter starting circuit based on high-voltage input provides a control signal for a control chip of the flyback converter, the high-voltage battery provides input voltage for the flyback converter starting circuit based on high-voltage input, and the high-voltage battery provides an input source for the flyback converter;
the high-voltage battery provides input voltage for a control chip through an input starting circuit, the input voltage is lower than the output voltage of the high-voltage battery, the input starting circuit charges a capacitor, the voltage on a first electrode of the capacitor reaches and is kept on the input voltage of the control chip, the first electrode of the capacitor is connected with the input end of the control chip and provides the input voltage for the control chip, and a second electrode of the capacitor is grounded;
after the control chip normally operates, a switching signal is provided for a switching MOS (metal oxide semiconductor) tube of the flyback converter;
the flyback converter starts to work, and the output end of the flyback converter provides output voltage to the first electrode of the capacitor;
the self-shutdown circuit shuts off the input starting circuit to enable the input starting circuit to stop charging the first electrode of the capacitor;
the output voltage enables the voltage on the first electrode of the capacitor to reach and be kept on the input voltage of the control chip.
In the flyback converter starting circuit and the starting method based on the high-voltage input, the relatively simple input starting circuit is added on the basis of the conventional flyback converter, so that a control chip of the low-voltage input can be applied to the environment of the high-voltage input power supply without risk without replacement; compared with other RC starting circuits, the capacitor selection and service life problem of the RC starting circuit is improved, the problem of unreliability of capacitor charging time is solved, and the starting speed is higher. Meanwhile, a self-turn-off circuit is added to the input starting circuit, so that the input starting circuit is turned off automatically after the circuit output is established, and the phenomenon that the circuit runs for a long time when working normally, so that the loss is increased, and the thermal risk of a high-temperature working condition is increased is prevented.
Drawings
Fig. 1 is a schematic diagram of a prior art flyback converter;
fig. 2 is a schematic diagram of a vehicle-mounted inverter of a new energy automobile to which a conventional flyback converter is applied;
fig. 3 is a schematic diagram of a conventional RC start circuit of a flyback converter;
fig. 4 is a schematic diagram of a flyback converter start-up circuit based on high voltage input according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a first stage of a starting process in a flyback converter starting method according to another embodiment of the present invention;
fig. 6 is a schematic diagram illustrating the operation of a field effect transistor in a flyback converter start-up circuit based on a high voltage input according to another embodiment of the present invention;
fig. 7 is a schematic diagram of a second stage of the starting process in the flyback converter starting method according to another embodiment of the present invention;
fig. 8 is a schematic diagram of a flyback converter start-up circuit based on high voltage input according to another embodiment of the present invention;
fig. 9 is a schematic diagram of a flyback converter start-up circuit based on high voltage input according to another embodiment of the present invention;
shown in the figure: 10-a high voltage battery; 20-a flyback converter; 30-a control chip; 40-input start-up circuit; 50-self-shut off circuit.
Detailed Description
The flyback converter starting circuit and the starting method based on high-voltage input provided by the invention are further described in detail in the following with reference to the attached drawings and specific embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
The invention provides a flyback converter starting circuit and a starting method based on high-voltage input, and aims to solve the problem that the existing control chip of a flyback converter for supplying power to a high-voltage battery has large power supply capacitance or unstable input voltage.
In order to achieve the above idea, the present invention provides a flyback converter start circuit based on high voltage input and a start method, wherein a high voltage battery provides an input voltage for the flyback converter start circuit based on high voltage input, the high voltage battery provides an input source for a flyback converter, and the flyback converter start circuit based on high voltage input provides a control signal for a control chip of the flyback converter, and the flyback converter start circuit based on high voltage input is characterized by comprising an input start circuit and a self-turn-off circuit, wherein: the high-voltage battery provides input voltage for the control chip through the input starting circuit, the input voltage is lower than the output voltage of the high-voltage battery, the input starting circuit charges a capacitor, the voltage on a first electrode of the capacitor reaches and is kept on the input voltage of the control chip, the first electrode of the capacitor is connected with the input end of the control chip and provides the input voltage for the control chip, and a second electrode of the capacitor is grounded; after the control chip normally operates, a switching signal is provided for a switching MOS (metal oxide semiconductor) tube of the flyback converter; the flyback converter starts to work, the output end of the flyback converter provides output voltage to the first electrode of the capacitor, and the output voltage enables the voltage on the first electrode of the capacitor to reach and be kept on the input voltage of the control chip; the self-shutdown circuit shuts off the input startup circuit to cause the input startup circuit to stop charging the first electrode of the capacitor.
The invention provides a flyback converter starting circuit based on high-voltage input, as shown in fig. 4-9, a high-voltage battery T + provides an input voltage for the flyback converter starting circuit based on high-voltage input, the high-voltage battery T + provides an input source for a flyback converter 20, the flyback converter starting circuit based on high-voltage input provides a control signal for a control chip of the flyback converter 20, the flyback converter starting circuit based on high-voltage input comprises an input starting circuit 40 and a self-shutdown circuit 50, wherein: the high voltage battery T + provides an input voltage for the control chip 30 through the input start circuit 40, the input voltage is lower than the output voltage of the high voltage battery, the input start circuit 40 charges a capacitor C1, so that the voltage on a first electrode of the capacitor C1 reaches and is kept at the input voltage of the control chip 30, a first electrode of the capacitor C1 is connected to the input terminal Vin of the control chip 30 and provides the input voltage for the control chip 30, and a second electrode of the capacitor C1 is grounded; after the control chip 30 normally operates, a switching signal is provided for a switching MOS transistor of the flyback converter 20; the flyback converter 20 starts to operate, and the output Vo1 of the flyback converter 20 provides an output voltage to the first electrode of the capacitor C1; the output voltage Vo1 makes the voltage on the first electrode of the capacitor C1 reach and maintain at the input voltage of the control chip 30; the self-shutdown circuit 50 shuts down the input startup circuit 40 to cause the input startup circuit 40 to stop charging the first electrode of the capacitor C1.
As shown in fig. 4, the input start circuit 40 of this embodiment is composed of three start resistors R1, R2, and R3 (the number of resistors is adjustable according to the input voltage and power consumption), a voltage regulator tube D2, a field effect transistor T2, and a diode D3, and the Vds withstand voltage value of the field effect transistor T2 of the input start circuit 40 is selected according to the maximum input voltage and the worst operating condition; the self-turn-off circuit 50 is composed of a voltage regulator tube D1, two voltage dividing resistors R4 and R5 and a common NPN triode T1.
Specifically, in the flyback converter starting circuit based on high-voltage input, the input starting circuit 40 includes a plurality of resistors, a second regulator D2 and a field effect transistor T2, wherein: the resistors are connected in series to form a series circuit, one end of the series circuit is connected with the high-voltage battery T +, and the other end of the series circuit is connected with the grid electrode of the field effect transistor T2 and the cathode of the second voltage regulator tube D2; the anode of the second regulator tube D2 is grounded, the drain of the fet T2 is connected to the high voltage battery T +, and the source of the fet T2 is coupled to the first electrode of the capacitor C1. The number of the resistors is larger than 1, for example, 2-5, and the specific number is selected according to actual power consumption. The field effect transistor T2 is a P-channel field effect transistor. The input enable circuit 40 further includes a first diode D3, wherein: the cathode of the first diode D3 is connected to the capacitor C1, and the anode of the first diode D3 is connected to the source of the field effect transistor T2.
Further, in the flyback converter starting circuit based on the high voltage input, the self-turn-off circuit 50 includes a first voltage regulator D1, a first voltage-dividing resistor R4, a second voltage-dividing resistor R5, and a transistor T1, wherein: the cathode of the first voltage-regulator tube D1 is connected to the output Vo1 of the flyback converter 20, the anode of the first voltage-regulator tube D1 is connected to one end of the first voltage-dividing resistor R4, the other end of the first voltage-dividing resistor R4 is connected to one end of the second voltage-dividing resistor R5 and the base of the triode T1, and the other end of the second voltage-dividing resistor R5 is grounded; the collector of the transistor T1 is connected to the gate of the FET T2, and the emitter of the transistor T1 is grounded. The triode T1 is an NPN type triode.
In addition, in the flyback converter starting circuit based on the high voltage input, the flyback converter starting circuit based on the high voltage input further includes a second diode D4, a cathode of the second diode D4 is connected to the first electrode of the capacitor C1, and an anode of the second diode D4 is connected to the output Vo1 of the flyback converter 20. The power supply voltage of the high-voltage battery T + is more than 60V.
The present embodiment is based on the auxiliary power supply of the flyback converter 20, and is applied to the environment of the high-voltage battery T + input. Compared with a conventional auxiliary power supply for taking electricity from a low-voltage battery, the limitation of the input voltage range is improved, the application occasions of the flyback converter 20 circuit are widened, and only a relatively simple input starting circuit 40 is added on the basis of the conventional auxiliary power supply, so that the control chip 30 with low-voltage input can be applied to the environment with high-voltage input without risk without replacement; compared with other RC starting circuits, the capacitor C1 selection and service life problem of the RC starting circuit are improved, the problem of unreliability of the charging time of the capacitor C1 is solved, and the starting speed is higher. Meanwhile, the self-turn-off circuit 50 is added to the field effect transistor T2 applied to the starting circuit, so that the field effect transistor T2 can be automatically turned off after the circuit output of the flyback converter 20 is established, and the phenomenon that the field effect transistor T2 runs for a long time when the circuit normally works, so that the loss is increased, and the thermal risk of a high-temperature working condition is increased is prevented.
According to the technical idea of the embodiment, the input voltage can be expanded to a wider range under the condition that each circuit component is properly selected. Meanwhile, the number of paths of the output of the applicable circuit is not limited to 2 paths or 3 paths, and can be extended to multiple paths, such as 4, 5 and 6 … … n. If the circuit is expanded to be applied to a multi-output circuit, as shown in FIG. 8. The main circuit flyback converter 20 can also be extended to other DCDC circuits, as shown in fig. 9.
In summary, the foregoing embodiments have described in detail different configurations of the starting circuit of the flyback converter 20, but it is understood that the present invention includes, but is not limited to, the configurations listed in the foregoing embodiments, and any configuration converted based on the configurations provided in the foregoing embodiments is within the scope of the present invention. One skilled in the art can take the contents of the above embodiments to take a counter-measure.
The embodiment also provides a flyback converter starting method based on high-voltage input, as shown in fig. 5 to 7, the flyback converter starting method based on high-voltage input includes: the high-voltage battery T + provides an input source for the flyback converter 20; the high-voltage battery T + provides an input voltage for the control chip 30 through the input starting circuit 40, the input starting circuit 40 charges the capacitor C1, the voltage on the first electrode of the capacitor C1 reaches and is kept on the input voltage of the control chip 30, the first electrode of the capacitor C1 is connected with the input end of the control chip 30 and provides the input voltage for the control chip 30, and the second electrode of the capacitor C1 is grounded; after the control chip 30 normally operates, a control signal is provided for the switching MOS transistor of the flyback converter 20; the flyback converter 20 starts to operate, and the output Vo1 of the flyback converter 20 provides an output voltage to the first electrode of the capacitor C1; the output voltage makes the voltage on the first electrode of the capacitor C1 reach and keep on the input voltage of the control chip 30; the self-shutdown circuit 50 shuts down the input startup circuit 40 to cause the input startup circuit 40 to stop charging the first electrode of the capacitor C1.
The whole circuit functions in the sequence that after the high-voltage battery T + is electrified, the high-voltage battery T + is firstly input into the starting circuit 40 to function; then the control chip 30 works (for example, LM3478 is a reference chip); then, the main circuit of the flyback converter 20 works; and finally the self-shutdown circuit 50 is active. The detailed procedure of the circuit principle can be analyzed in detail in connection with the order in which the circuits function.
1) The input startup circuit 40 functions: as shown in fig. 5, when the input voltage supplied by the high-voltage battery to the input start-up circuit slowly increases from 0V, the gate voltage Vg of the fet T2 in the input start-up circuit 40 increases to reach the gate threshold voltage Vgsth of the fet T2, at this time, the fet T2 is in the variable resistance region, the capacitor C1 starts to charge, Vg and Vs of the fet T2 both increase continuously, and Vgs becomes Vg-Vs; when Vgs > -Vgsth the fet T2 increases with Vgs, Id charges C1 through fet T2, which increases Vs further, causing Vgs to decrease, and Id to decrease (as can be seen from fig. 6), thus forming a negative feedback mechanism similar to voltage control, so that Vgs Vg-Vs ═ Vgsth can be maintained at all times; at this time, T1 is in the off state; wherein the voltage regulator tube D2 is used for protecting the field effect transistor T2;
2) the control chip 30 operates: when the configuration circuits of other ports of the control chip 30 are in a reasonable design range, when the input voltage Vin of the control chip 30 reaches the starting voltage requirement, the control chip 30 works normally and outputs PWM; compared with a similar input starting circuit 40 containing a switching device, the input starting circuit is applied to a vehicle-mounted inverter, the highest temperature of the working environment of the input starting circuit 40 can reach 125 ℃, the switching device always works in the input starting circuit 40, the input starting circuit has no meaning when the circuit works normally, and loss exists on the contrary, so that the temperature of the device is further increased; for the input starting circuit 40, the efficiency of the whole flyback converter 20 circuit is reduced, and meanwhile, the temperature of the switching devices in the input starting circuit 40 rises after long-time operation, so that the switching devices are in thermal risk and are burnt out under the worst high-temperature condition. In the vehicle-mounted inverter, before the main circuit starts to work, the input starting circuit 40 is operated, after the main circuit starts to work, the input starting circuit 40 can be turned off, and static loss of the circuit is reduced.
3) The flyback converter 20 operates, the self-shutdown circuit 50 functions: as shown in fig. 7, the control chip 30 normally operates, the main circuit of the flyback converter 20 starts to operate, a normal output Vo1 is established, the voltage regulator D1 breaks down, the Vb voltage of the triode T1 after being divided by the resistor is greater than 0.7V (reference value), T1 is turned on, the gate voltage Vg of the field effect transistor T2 is pulled to the ground, the field effect transistor T2 is turned off (the field effect transistor T2 only operates during the starting process, the main circuit is turned off during the normal operation, the loss of the field effect transistor T2 is reduced, and the thermal risk at high temperature is reduced); the input of the control chip 30 is subsequently powered by the output Vo1 through the diode D4.
In the flyback converter starting circuit and the starting method based on high-voltage input, the relatively simple input starting circuit 40 is added on the basis of the conventional flyback converter 20, so that the low-voltage input control chip 30 can be applied to the environment of high-voltage battery T + power supply without risk without replacement; compared with other RC starting circuits, the capacitor C1 selection and service life problem of the RC starting circuit are improved, the problem of unreliability of the charging time of the capacitor C1 is solved, and the starting speed is higher. Meanwhile, the self-turn-off circuit 50 is added to the input starting circuit 40, so that the input starting circuit 40 is turned off automatically after the circuit output is established, and the phenomenon that the circuit runs for a long time when working normally, so that the loss is increased, and the thermal risk of a high-temperature working condition is increased is prevented.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (10)
1. The utility model provides a flyback converter starting circuit based on high-voltage input, high-voltage battery for flyback converter starting circuit based on high-voltage input provides input voltage, high-voltage battery provides the input source for flyback converter, flyback converter starting circuit based on high-voltage input provides control signal for flyback converter's control chip, its characterized in that, flyback converter starting circuit based on high-voltage input includes input starting circuit and self-shutdown circuit, wherein:
the high-voltage battery provides input voltage for the control chip through the input starting circuit, the input voltage is lower than the output voltage of the high-voltage battery, the input starting circuit charges a capacitor, the voltage on a first electrode of the capacitor reaches and is kept on the input voltage of the control chip, the first electrode of the capacitor is connected with the input end of the control chip and provides the input voltage for the control chip, and a second electrode of the capacitor is grounded;
after the control chip normally operates, a switching signal is provided for a switching MOS (metal oxide semiconductor) tube of the flyback converter;
the flyback converter starts to work, the output end of the flyback converter provides output voltage to the first electrode of the capacitor, and the output voltage enables the voltage on the first electrode of the capacitor to reach and be kept on the input voltage of the control chip;
the self-shutdown circuit shuts off the input startup circuit to cause the input startup circuit to stop charging the first electrode of the capacitor.
2. The flyback converter start-up circuit based on a high voltage input of claim 1, wherein the input start-up circuit comprises a plurality of resistors, a second regulator tube, and a field effect transistor, wherein:
the resistors are connected in series to form a series circuit, one end of the series circuit is connected with the high-voltage battery, and the other end of the series circuit is connected with the grid electrode of the field effect transistor and the cathode of the second voltage regulator tube;
the anode of the second voltage regulator tube is grounded, the drain of the field effect transistor is connected with the high-voltage battery, and the source of the field effect transistor is coupled to the first electrode of the capacitor.
3. The flyback converter startup circuit based on high voltage input of claim 2 wherein the number of the plurality of resistors is greater than 1.
4. The flyback converter startup circuit based on high voltage input of claim 2 wherein the field effect transistor is a P-channel field effect transistor.
5. The high voltage input based flyback converter startup circuit of claim 2 wherein the input startup circuit further comprises a first diode, wherein:
the cathode of the first diode is connected with the capacitor, and the anode of the first diode is connected with the source electrode of the field effect transistor.
6. The flyback converter startup circuit based on high voltage input of claim 2 wherein the self-turn-off circuit comprises a first voltage regulator tube, a first voltage-dividing resistor, a second voltage-dividing resistor and a triode, wherein:
the cathode of the first voltage-stabilizing tube is connected with the output end of the flyback converter, the anode of the first voltage-stabilizing tube is connected with one end of the first voltage-dividing resistor, the other end of the first voltage-dividing resistor is connected with one end of the second voltage-dividing resistor and the base electrode of the triode, and the other end of the second voltage-dividing resistor is grounded;
and the collector electrode of the triode is connected with the grid electrode of the field effect transistor, and the emitter electrode of the triode is grounded.
7. The flyback converter start-up circuit based on a high voltage input of claim 6 wherein the transistor is an NPN transistor.
8. The high voltage input based flyback converter start circuit of claim 1 further comprising a second diode, wherein a cathode of the second diode is connected to the first electrode of the capacitor and an anode of the second diode is connected to the output of the flyback converter.
9. The flyback converter startup circuit based on high voltage input of claim 1 wherein the supply voltage of the high voltage battery is greater than 60V.
10. A flyback converter starting method based on high-voltage input is characterized by comprising the following steps:
the flyback converter starting circuit based on high-voltage input provides a control signal for a control chip of the flyback converter, the high-voltage battery provides input voltage for the flyback converter starting circuit based on high-voltage input, and the high-voltage battery provides an input source for the flyback converter;
the high-voltage battery provides input voltage for a control chip through an input starting circuit, the input voltage is lower than the output voltage of the high-voltage battery, the input starting circuit charges a capacitor, the voltage on a first electrode of the capacitor reaches and is kept on the input voltage of the control chip, the first electrode of the capacitor is connected with the input end of the control chip and provides the input voltage for the control chip, and a second electrode of the capacitor is grounded;
after the control chip normally operates, a switching signal is provided for a switching MOS (metal oxide semiconductor) tube of the flyback converter;
the flyback converter starts to work, and the output end of the flyback converter provides output voltage to the first electrode of the capacitor;
the self-shutdown circuit shuts off the input starting circuit to enable the input starting circuit to stop charging the first electrode of the capacitor;
the output voltage enables the voltage on the first electrode of the capacitor to reach and be kept on the input voltage of the control chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811481414.5A CN111277128B (en) | 2018-12-05 | 2018-12-05 | Flyback converter starting circuit and starting method based on high-voltage input |
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| CN112260529A (en) * | 2020-10-15 | 2021-01-22 | 西安爱科赛博电气股份有限公司 | High-voltage direct-current input switching power supply and starting auxiliary source locking method |
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| CN111277128B (en) | 2021-06-08 |
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