CN214506884U - Power converter and power control chip - Google Patents
Power converter and power control chip Download PDFInfo
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- CN214506884U CN214506884U CN202120527911.5U CN202120527911U CN214506884U CN 214506884 U CN214506884 U CN 214506884U CN 202120527911 U CN202120527911 U CN 202120527911U CN 214506884 U CN214506884 U CN 214506884U
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Abstract
The embodiment of the application provides a power converter and a power control chip, wherein the power converter mainly comprises a transformer, a main switching tube, a power control chip, a voltage detection module, a sampling control module and the like, the transformer comprises a main winding and an auxiliary winding with the same polarity, the power control chip comprises a charging control module, and the sampling control module and the voltage detection module are positioned inside or outside the power control chip; the first end of the sampling control module is connected with the demagnetization detection pin of the chip, the second end of the sampling control module is connected with the first end of the charging control module, and the third end of the sampling control module is connected with the power supply negative electrode pin of the chip; the second end of the charging control module is connected with the voltage detection module, and the third end of the charging control module is connected with the power supply anode pin of the chip. The scheme of this application can overcome among the prior art because the voltage of traditional auxiliary winding follows and leads to the mains voltage of power control chip to need to bear the defect of higher voltage for the voltage of chip can be stabilized at required setting value etc..
Description
Technical Field
The present application relates to the field of power conversion technologies, and in particular, to a power converter and a power control chip.
Background
The PD power adapter is a power adapter supporting the PD (power delivery) protocol. The PD power supply is generally high in power, and in order to meet the energy efficiency standard of European energy satellites, a power supply control chip for a quasi-resonance system to work is generally adopted. The PD power supply has a wide output voltage range, and the output is usually 3.3V to 20V, that is, the maximum voltage is 6 times the minimum voltage.
In the conventional flyback converter for supplying power to the power control chip based on the auxiliary winding, the polarity of the auxiliary winding is the same as that of the secondary winding, and under the condition that the turn ratio of the polarity of the auxiliary winding to that of the secondary winding is fixed, the voltage of the conventional auxiliary winding during chip power supply is approximately in direct proportion to the output voltage of the flyback converter, namely the variation range of the power supply voltage is up to 6 times.
In order to avoid affecting the efficiency of the power control chip driving the main switching tube, two common methods are currently available in the market, one is to add an external linear voltage regulator (LDO) circuit in front of a power pin of the power control chip to perform a voltage reduction function; the other is to arrange an LDO module inside the power control chip to provide a stable power supply for the chip. However, the first scheme needs to add LDO at the periphery, which increases the cost and reduces the system efficiency; the second scheme needs a higher voltage-resistant process, increases the area of a chip, increases the heat productivity of the chip, reduces the system efficiency and the system stability, improves the cost and the like. Therefore, the two methods cannot well solve the power supply problem of the main control chip under the application of the PD power supply.
SUMMERY OF THE UTILITY MODEL
In view of the above, the present application provides a power converter and a power control chip to overcome the deficiencies in the prior art.
An embodiment of the present application provides a power converter, comprising: the transformer comprises a main winding and an auxiliary winding with the same polarity, the power supply control chip comprises a demagnetization detection pin, a power supply positive electrode pin, a power supply negative electrode pin and a charging control module, and the sampling control module and the voltage detection module are positioned inside or outside the power supply control chip;
the first end of the main winding is used for connecting input voltage, and the second end of the main winding is connected with the main switching tube;
the first end of the auxiliary winding is connected with the demagnetization detection pin, and the second end of the auxiliary winding is grounded;
the positive pin of the power supply is grounded through a power supply capacitor and is also connected to the first end of the main winding through a current limiting resistor; the pin of the negative electrode of the power supply is grounded;
the first end of the sampling control module is connected with the demagnetization detection pin, the second end of the sampling control module is connected with the first end of the charging control module, and the third end of the sampling control module is connected with the negative electrode pin of the power supply;
the second end of the charging control module is connected with the output end of the voltage detection module, and the third end of the charging control module is connected with the positive pin of the power supply;
the input end of the voltage detection module is connected with the positive pin of the power supply.
In one embodiment, the voltage detection module is used for detecting the voltage of the positive pin of the power supply and outputting a path opening signal when the voltage of the positive pin of the power supply is lower than a preset value;
the charging control module is used for controlling the second end of the sampling control module and the power supply positive electrode pin to be in a conductive state when receiving the access opening signal;
the charging control module comprises a switch unit and a clamping diode, the first end of the switch unit is connected with the second end of the sampling control module, the second end of the switch unit is connected with the clamping diode arranged in the forward direction, and the third end of the switch unit is connected with the output end of the voltage detection module.
In one embodiment, the switch unit comprises a current source, a voltage drop resistor, a first switch tube and a first switch, wherein the voltage drop resistor is connected between a control end and a first end of the first switch tube in parallel, the first end of the first switch tube is connected with a second end of the sampling control module, the second end of the first switch tube is connected with a clamping diode, and the control end of the first switch tube is connected with the first end of the first switch;
the second end of the first switch is connected with the current source, and the control end is connected with the voltage detection module.
In the above embodiments, the first switch tube is a MOS tube or a triode.
In one embodiment, the sampling control module is configured to control a short circuit between the first end and the second end of the sampling control module and an open circuit between the second end and the third end when the main switching tube is turned on after the second end of the sampling control module and the positive pin of the power supply are in a conductive state, so that a current generated by the auxiliary winding flows from the demagnetization detection pin to the power supply capacitor;
the sampling control module comprises a second switch, a third switch and a voltage division unit formed by connecting a first resistor and a second resistor in series;
one end of the first resistor is connected with the demagnetization detection pin, and the other end of the first resistor is respectively connected with one end of the second resistor and the first end of the charging control module;
the second switch is connected in parallel with two ends of the first resistor;
the other end of the second resistor is connected with one end of a third switch, and the other end of the third switch is connected with a negative pin of the power supply.
In one embodiment, the transformer includes a secondary winding having an opposite polarity to the primary winding, and the power converter further includes: the homonymous end of the secondary winding is connected to the anode of the output capacitor through the rectifier diode arranged in the forward direction, and the synonym end is connected with the cathode of the output capacitor.
In one embodiment, the different-name end of the main winding is used for connecting an input voltage, and the same-name end of the main winding is connected with the main switching tube;
the synonym end of the auxiliary winding is connected with the demagnetization detection pin, and the synonym end is grounded.
In one embodiment, the power converter further comprises: the input end of the full-bridge rectification circuit is used for connecting an alternating current power supply, and the output end of the full-bridge rectification circuit is used for connecting the filter capacitor; the positive pole of the filter capacitor is connected with the synonym end of the main winding, and the negative pole is grounded.
In one embodiment, the power converter further comprises: and the absorption circuits are connected in parallel with two ends of the main winding.
An embodiment of the present application further provides a power control chip, including: the device comprises a demagnetization detection pin, a power supply positive electrode pin, a power supply negative electrode pin, a sampling control module, a charging control module and a voltage detection module;
the demagnetization detection pin is used for connecting an auxiliary winding of a transformer in the power converter;
the power supply positive electrode pin is used for being grounded through a power supply capacitor and is also connected to a main winding of the transformer through a current limiting resistor; the power supply negative electrode pin is used for grounding; the polarity of the auxiliary winding is the same as that of the main winding, and the main winding is connected with a main switching tube in the power converter;
the first end of the sampling control module is connected with the demagnetization detection pin, the second end of the sampling control module is connected with the first end of the charging control module, and the third end of the sampling control module is connected with the negative electrode pin of the power supply;
the second end of the charging control module is connected with the output end of the voltage detection module, and the third end of the charging control module is connected with the positive pin of the power supply;
the input end of the voltage detection module is connected with the positive pin of the power supply.
The embodiment of the application has the following beneficial effects:
the power converter of the embodiment sets the auxiliary winding and the main winding to have the same polarity, and simultaneously, the voltage range of the auxiliary winding does not follow the output voltage of the secondary winding any more, so that the defect that the power voltage of the power control chip needs to bear higher voltage due to the voltage following of the traditional auxiliary winding in the prior art can be well overcome. In addition, in the embodiment, the internal design of the power control chip is used for realizing the internal charging circuit structure, so that the voltage of the power control chip can be stabilized at a required set value and the like even if the traditional LDO and the structural design with large loss based on resistance current limiting and the like are abandoned.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
Fig. 1 is a schematic diagram illustrating a conventional flyback converter with an auxiliary winding for supplying power to a power control chip;
fig. 2 is a schematic structural diagram illustrating a conventional flyback converter that employs an external LDO module for voltage stabilization;
FIG. 3 illustrates a first schematic diagram of a power converter according to an embodiment of the present application;
FIG. 4 is a second schematic diagram of a power converter according to an embodiment of the present application;
fig. 5 is a first flowchart illustrating a power supply control method of a power converter according to an embodiment of the present application;
fig. 6 shows a schematic structural diagram of a power control chip according to an embodiment of the present application.
Description of the main element symbols:
100-a power converter; 110-a voltage detection module; 130-a sampling control module; 120-a charging control module; 121-a switching unit; c0-filter capacitance; c1-supply capacitance; c2 — output capacitance; c3 — absorption capacitance; r1-current limiting resistor; r2 — first resistance; r3 — second resistance; rs-current sampling resistor; r4-absorption resistance; r5-voltage drop resistance; u1-power control chip; DEM-demagnetization detection pin; VDD-Power Positive Pin; GND-power supply negative pin; a PWM-drive signal output pin; FB-primary feedback pin; a T-transformer; q1-main switching tube; q0-first switch tube; s1 — a first switch; s2 — a second switch; s3 — a third switch; d0 — first diode; d1-clamp diode; d2-rectifier diode; d3-anti-reverse diode.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments.
The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.
As shown in fig. 1, in a conventional flyback power converter, the operating principle mainly includes: after the alternating current is connected, the alternating current is rectified through the rectifier bridge, and then the filtering capacitor C0 filters and stores energy. When the main switching tube Q1 is conducted, energy is stored at two ends of a primary winding of the transformer T, the current passing through the primary winding is linearly increased, and the magnetic flux in a magnetic core of the transformer T is gradually increased; at this time, the secondary winding and the auxiliary winding induce a voltage with a polarity opposite to that of the primary winding, so that the first diode D0 and the rectifier diode D2 are turned off, and the output capacitor C2 is discharged to supply a load current.
When the main switch tube Q1 is turned off, the primary winding is opened, the polarities of the induced electromotive forces of the secondary winding and the auxiliary winding are reversed, the switches D1 and D2 are turned on, the magnetic flux in the magnetic core of the transformer T starts to release, a part of energy is used for charging the capacitor C2 and supplying power to the load on the secondary side, and the other part of energy is used for charging the capacitor C1 and supplying power to the power control chip U1 through the auxiliary winding. At this time, the circuit on the primary winding side is open, the secondary winding and the auxiliary winding circuit work, and the auxiliary winding and the secondary winding have the same polarity, so that the following requirements are met:
wherein, VAAnd VSVoltages of the auxiliary winding and the secondary winding, NAAnd NSThe number of turns in the auxiliary winding and the secondary winding, respectively. Further, it is converted into:
wherein, VDIs the voltage drop of a diode, VDDIs the chip supply voltage, VoutIs the output voltage.
Further, there are obtained:
if the voltage drop of the diode is neglected, the above equation can be simplified as:
it will be appreciated that in PD power applications, the chip supply voltage V supplied by the conventional auxiliary windingDDAnd an output voltage VoutApproximately proportional, the variation range will reach 6 times, and in order not to affect the efficiency of driving the main switch tube Q1, V is set to be the lowest when the output voltage is the lowestDDThe minimum value is 10V, and when the output voltage is switched to 6 times, V isDDWill reach 60V.
Obviously, the voltage of 60V is too high for the power control chip U1. Therefore, to cope with VDDHigh voltages may be present, and an LDO circuit may be provided before the power pin of the power control chip U1 as shown in FIG. 2, but may also be provided inside the power control chip U1. If inside, the power control chip U1 needs to be manufactured by a high voltage process of 60V.
On the other hand, VDDSuch a large voltage variation range will also lead to more complicated driving design, in order to protect the gate oxide of the power transistor at VDDUnder high voltage, the chip is not broken down, the output voltage needs to be clamped, and a voltage regulator tube is generally used for achieving the function, so that the power consumption of the chip is greatly improved. On the other hand VDDThe high-speed starting speed of the power device is greatly increased, the EMI is rapidly deteriorated, additional devices are required to be added to solve the problems of conduction and radiation in the scheme of the whole machine, the cost is further increased, and the process tolerance is simply improvedThe voltage does not well address the pain of the traditional power supply scheme under PD power supply application.
Therefore, the embodiment of the application provides a power converter, which modifies an auxiliary winding of a transformer into forward power supply so that the voltage range of the auxiliary winding follows the input voltage range of a primary winding, so as to overcome the defect that the power supply voltage of a power supply control chip needs to bear higher voltage due to the fact that the voltage of the auxiliary winding changes along with the output voltage in the prior art. Meanwhile, in order to stabilize the working voltage, the internal structure of the power supply control chip is correspondingly adjusted and designed, so that the voltage V is stableDDThe voltage is stabilized at a certain set point without adopting a circuit structure with large loss such as LDO (low dropout regulator), resistance current limiting and the like.
The power converter is described below with reference to specific embodiments.
Example 1
Referring to fig. 3, the present embodiment provides a power converter 100, which can be applied to various power supply situations, such as a PD adapter outputting a variable voltage, and other electronic devices related to power conversion.
Exemplarily, the power converter 100 includes a transformer T, a main switching tube Q1, a power control chip U1, a supply capacitor C1, a current limiting resistor R1, a voltage detection module 110, and a sampling control module 130, wherein the transformer T includes a main winding and an auxiliary winding having the same polarity. Typically, the primary winding has a first terminal for connection to an input voltage and a second terminal connected to a main switch Q1, the main switch Q1 being connected to a power ground (i.e., ground) typically via a current sampling resistor Rs. The voltage detection module 110 and the sampling control module 130 may be located inside or outside the power control chip U1.
Optionally, a snubber circuit may be further disposed at both ends of the main winding, for example, as shown in fig. 3, the snubber circuit may be formed by connecting a snubber capacitor C3 and a snubber resistor R4 in parallel and then connecting an anti-reverse diode D3 in series. In some other embodiments, the power converter 100 further comprises: the input end of the full-bridge rectifying circuit is used for accessing an Alternating Current (AC) power supply, and the output end of the full-bridge rectifying circuit is used for connecting a filter capacitor C0; the positive pole of the filter capacitor C0 is connected with the synonym end of the main winding, and the negative pole is grounded. At this time, the voltage output from the filter capacitor C0 is the input voltage.
In this embodiment, the power control chip U1 is used as a main control chip of the main switching tube Q1, and is mainly used for outputting a corresponding PWM driving signal according to a requirement to correspondingly control the main switching tube Q1, so as to achieve the purpose of power conversion. The power converter 100 also enables self-starting of the circuit and self-powering of the power control chip U1.
Exemplarily, the power control chip U1 includes a demagnetization detection pin DEM, a power positive pin VDD, a power negative pin GND, a basic driving signal output pin PWM, a primary feedback pin FB, and the like, where the driving signal output pin PWM is used for outputting a PWM signal to control the on/off of the main switching transistor Q1. It can be understood that the power control chip U1 of the present embodiment is mainly to add a new chip self-power function without changing the existing functions of the chip.
Exemplarily, as shown in fig. 3, the demagnetization detecting pin DEM of the power control chip U1 is connected to the first end of the auxiliary winding, and the second end of the auxiliary winding is grounded; the positive power pin VDD of the power control chip U1 is grounded through a power supply capacitor C1, and is also connected to the first end of the main winding through a current limiting resistor R1. It is understood that the supply capacitor C1 is used to store energy to provide the required operating voltage for the power control chip U1 and to clamp the required voltage for the chip. The power supply negative pin GND of the power supply control chip U1 is grounded. In addition, a signal output pin PWM of the power control chip U1 is connected to a control terminal of the main switching tube Q1, and a feedback pin is connected to a corresponding primary feedback circuit and the like.
In one embodiment, as shown in fig. 3, the power control chip U1 further includes a charging control module 120, and a built-in sampling control module 130 and a voltage detection module 110. Exemplarily, the first end of the sampling control module 130 is connected to the demagnetization detection pin DEM, the second end is connected to the first end of the charging control module 120, and the third end is connected to the power supply negative electrode pin GND; the second end of the charging control module 120 is connected to the voltage detection module 110, and the third end is connected to the positive power pin VDD; and the voltage detection module 110 is connected to the positive power pin VDD. It should be noted that the sampling control module 130 and the voltage detection module 110 may be located inside the power control chip U1, or may be located outside the power control chip, and is not limited herein. The present embodiment is mainly explained by a built-in scheme.
The voltage detection module 110 is configured to detect a voltage of the positive pin VDD of the power supply, and output a path opening signal to the charging control module 120 when the voltage of the positive pin VDD of the power supply is lower than a preset value. In addition, the voltage detection module 110 is further configured to output a path shutdown signal when the voltage of the positive power pin VDD is higher than the preset value.
For example, the voltage detection module 110 may be composed of a plurality of voltage dividing resistors and a voltage comparator, wherein the voltage dividing resistors are mainly used for detecting a voltage value, and the voltage comparator is used for comparing the detected voltage value with a preset set value and outputting a comparison result. For example, a high level of the output indicates a channel on signal, and a low level indicates a channel off signal, etc.
The charging control module 120 is mainly configured to control the second end of the sampling control module 130 and the power supply positive pin VDD to be in a conductive state when receiving the start signal, that is, when a current flows, the current can generate a voltage drop to turn on the internal switching tube, so that the current can flow from the second end to the power supply positive pin VDD after passing through the charging control module 120.
On the contrary, when the voltage of the positive power pin VDD is higher than the preset value, the second terminal of the sampling control module 130 and the positive power pin VDD are turned off, and at this time, even if a current is input to the second terminal, the current cannot flow to the positive power pin VDD.
Exemplarily, as shown in fig. 4, the charging control module 120 includes a switch unit 121 and a clamping diode D1, wherein a first terminal of the switch unit 121 is connected to a second terminal of the sampling control module 130, a second terminal is connected to the clamping diode D1 arranged in the forward direction, and a third terminal is connected to the output terminal of the voltage detection module 110.
In one embodiment, the switch unit 121 may include a current source I1, a voltage drop resistor R5, a first switch Q0, and a first switch S1, wherein the voltage drop resistor R5 is connected in parallel between a control terminal and a first terminal of the first switch Q0, a first terminal of the first switch Q0 is connected to a second terminal of the sampling control module 130, the second terminal is connected to a clamping diode D1, and the control terminal is connected to a first terminal of the first switch S1; the second terminal of the first switch S1 is connected to the current source, and the control terminal is connected to the voltage detection module 110.
It can be appreciated that the current source is mainly used to provide a bias power to the first switch Q0, so that when a current is applied to the first terminal of the first switch Q0, a voltage drop is formed, and the first switch Q0 is turned on. For example, the first switching transistor Q0 may be a MOS transistor, a triode, or the like. Taking a PMOS transistor as an example, the gate of the PMOS transistor is a control terminal, and the source and the drain are respectively the first terminal and the second terminal.
The sampling control module 130 is configured to control a short circuit between the first end and the second end of the sampling control module 130 and an open circuit between the second end and the third end when the main switching tube Q1 is turned on after the second end of the sampling control module 130 and the power supply positive pin VDD are in a conductive state, and at this time, the first switching tube Q0 in the switching unit 121 is turned on, so that a current generated by the auxiliary winding flows to the power supply positive pin VDD through the demagnetization detection pin DEM, thereby charging the power supply capacitor C1.
In an embodiment, as shown in fig. 4, the sampling control module 130 includes a second switch S2, a third switch S3, and a sampling unit formed by serially connecting a first resistor R2 and a second resistor R3, wherein one end of the first resistor R2 is connected to the demagnetization detection pin DEM, and the other end of the first resistor R2 is connected to one end of the second resistor R3 and the first end of the charging control module 120; the second switch S2 is connected in parallel to two ends of the first resistor R2; the other end of the second resistor R3 is connected to one end of the third switch S3, and the other end of the third switch S3 is connected to the power supply negative terminal GND.
It can be understood that the sampling unit is an originally external sampling unit for forming demagnetization detection, which is now built inside the chip, and forms the sampling control module 130 in combination with the second switch S2 and the third switch S3. For example, the first switch S1, the second switch S2, and the third switch S3 may be implemented by using a transistor, a MOS transistor, or the like having a switching device.
In addition, the sampling control module 130 is further configured to control the short-circuit state between the first end and the second end of the sampling control module 130 to be switched off and the second end and the third end to be switched on when the main switching tube Q1 is switched off after the second end of the sampling control module 130 is switched off from the positive power pin VDD. And after the main switching tube Q1 is turned off, the sampling control module 130 is further configured to collect an electrical signal on the demagnetization detection pin DEM through the sampling unit, that is, to sample a voltage or current signal on the auxiliary winding, so as to determine the state of the transformer T according to the electrical signal, for example, whether to enter a demagnetization stage, whether to complete demagnetization, whether to enter a quasi-resonance period, and the like.
Further, after it is detected that the demagnetization of the transformer T is completed, the sampling unit is further configured to obtain a resonant current of the transformer T at a resonant (QR) stage, and further, the power control chip U1 controls the main switching tube Q1 to be turned on at a time when the resonant current is zero according to the magnitude of the resonant current, so as to reduce the switching loss of the main switching tube Q1.
Unlike the conventional flyback converter, the main winding and the auxiliary winding of the present embodiment have the same polarity. As shown in fig. 3, the different-name terminal of the main winding is used for connecting an input voltage, and the same-name terminal is connected with a main switching tube Q1; and the different name end of the auxiliary winding is connected with a demagnetization detection pin DEM of the power control chip U1, and the same name end is grounded. This design allows the auxiliary winding to be supplied when the main switching transistor Q1 is conducting, without the conventional scheme of supplying power during degaussing, so that the supply voltage of the chip can no longer vary over 6 times the output voltage, but only follow the input voltage. Generally, the input voltage range is about 3 times from 90V to 264V, and if a reasonable turn ratio is set, and the reflected voltage of the auxiliary winding is about 40V when the input voltage is 264V, the charging voltage is 13V when 90V is input, and the lowest voltage required for the energy efficiency of the main switching tube Q1 can be satisfied.
Further, taking the flyback power converter as shown in fig. 3 as an example, the transformer T in the power converter 100 includes a secondary winding having an opposite polarity to the primary winding, and the power converter 100 further includes: the high-voltage power supply comprises a rectifier diode D2 and an output capacitor C2, wherein the dotted terminal of the secondary winding is connected to the anode of the output capacitor C2 through a rectifier diode D2 arranged in the forward direction, the unlike terminal is connected to the cathode of the output capacitor C2, and then the two ends of the output capacitor C2 are used for being connected with a load and supplying power to the load.
The power converter 100 of the embodiment can well overcome the defect that the power voltage of the power control chip U1 needs to bear higher voltage due to the voltage following of the conventional auxiliary winding in the prior art by setting the auxiliary winding and the main winding to have the same polarity and enabling the voltage range of the auxiliary winding to no longer follow the output voltage of the secondary winding. In addition, this embodiment is used for realizing the circuit structure of inside charging through the internal design to power control chip U1, no matter during main switch Q1 switches on or off, the voltage of chip all can be stabilized at the required value, through giving up traditional LDO and based on the big circuit structure of loss such as resistance current-limiting, can make the chip work under reasonable and stable operating voltage, thereby the loss has been reduced, the efficiency is improved, switch tube stress is reduced, electromagnetic interference (EMI) has been improved, in addition, the periphery need not devices such as extra LDO, can reach purposes such as green energy-conservation, environmental protection.
Example 2
Referring to fig. 3 and 5, based on the power converter 100 of embodiment 1, the present embodiment provides a power supply control method of the power converter 100, which can be used to implement self-starting and self-powered control of the power converter 100.
Exemplarily, when the power converter 100 starts to be powered on, that is, when the power converter 100 is connected to a high voltage, since the main switch Q1 has no signal and no current flows through the windings of the transformers T, there is no voltage drop between the windings of the transformers T, and the voltage V at the demagnetization detection pin DEM is detectedDEM0; voltage V on power supply anode pin VDDDDA current limiting resistor R1 supplied by high voltage has a small current flowing through it to charge a supply capacitor C1The chip consumes no power. With VDDSlowly rises, the voltage detection module 110 does not work at this time, so VDDMay be stored without being dropped by the DEM pin. Then, the voltage VDDIt may slowly increase to the voltage point Vstart at which the circuit needs to start. Then, the power control chip U1 starts to enter an operating state, and the self-start of the circuit is completed.
After the power control chip U1 operates normally, to maintain the chip voltage, the power control method exemplarily includes:
in step S110, when the voltage detection module 110 detects that the voltage of the positive pin VDD of the power supply is lower than a preset value, a path start signal is generated.
In step S120, the charging control module 120 controls the second terminal of the sampling control module 130 and the power supply positive pin VDD to be in a conductive state when receiving the path start signal.
Exemplarily, when the voltage V isDDIf the current is injected into the second terminal, the flowing current can automatically turn on the switch tube in the charging control module 120, so that the current can flow to the positive power pin VDD through the charging control module 120.
For example, in the power converter 100 shown in fig. 4, when it is detected that the voltage on the positive pin VDD of the power supply meets the requirement, the first switch S1 obtains a path open signal, so that the first switch S1 is closed, and the current source is connected to the gate of the switch tube. At this time, the switching tube in the sampling control module 130 is in a state of being capable of being turned on at any time.
Step S130, after the second terminal of the sampling control module 130 and the power supply positive terminal pin VDD are in a conductive state, when the main switching tube Q1 is turned on, the sampling control module 130 controls the first terminal and the second terminal of the sampling control module 130 to be short-circuited and the second terminal and the third terminal to be open-circuited, so that the current generated by the auxiliary winding flows to the power supply capacitor C1 through the demagnetization detection pin DEM.
Exemplarily, when the first switch S1 is closed and the main switch Q1 is turned on, the first switch S1 is short-circuited between the first terminal and the second terminal of the sampling control module 130 and is open-circuited between the second terminal and the third terminal, that is, the second switch S2 is turned on and the third switch S3 is turned off, and at this time, the voltage of the auxiliary winding is increased by Vaux Vin/Np Na. The current source I1 forms a voltage drop V across the voltage drop resistor R5 via the first switch S1fallWhen the first switch Q0 is turned on, the current generated in the auxiliary winding flows from the second switch S2, through the first switch Q0, through the clamping diode D1, and finally through the pin VDD, the supply capacitor C1 is charged.
Further, the voltage detecting module 110 starts to operate when the voltage V is appliedDDWhen the voltage drops to the set value, the voltage detecting module 110 will generate a path open signal, and the first switch S1 is turned off. When the on signal Ton of the main switch comes, the second switch S2 is controlled to be closed, the third switch S3 is turned off, the DEM pin is pulled high by the induction voltage on the auxiliary winding at this time, and since the first switch S1 is turned off, no voltage drop can be generated on the voltage drop resistor R5, the switch tube is turned off at this time, the DEM pin cannot charge the power supply capacitor C1, and thus the voltage of the pin VDD is clamped at the set value.
Further, the power supply control method further includes: and when detecting that the voltage of the power supply positive electrode pin VDD is higher than a preset value, generating a channel-off signal. At this time, the charging control module 120 controls the conductive state between the second terminal of the sampling control module 130 and the power supply positive pin VDD to be turned off when receiving the off-path signal.
The power supply control method further includes: after the second terminal of the sampling control module 130 is disconnected from the positive power pin VDD, and the main switching tube Q1 is turned off, the sampling control module 130 controls the short circuit between the first terminal and the second terminal of the sampling control module 130 to be disconnected and the second terminal and the third terminal to be connected.
Exemplarily, when the main switch Q1 is turned off, the transformer T starts to enter a degaussing phase, and the third switch S3 is closedWhen the second switch S2 is turned off, the first switch S1 is also turned off. At this time, the auxiliary winding voltage is-Vout/Ns NA. Voltage V on DEM pinDEM-Vout/Ns NA. Since the clamp diode D1 is in a reverse bias state, current of the supply capacitor C1 is blocked from being consumed.
Further, the sampling control module 130 includes a second switch S2, a third switch S3, and a sampling unit formed by serially connecting a first resistor R2 and a second resistor R3, so that after the main switching tube Q1 is turned off, the power supply control method further includes: the sampling unit is used for collecting an electric signal on a demagnetization detection pin DEM to judge the state of the transformer T, and after the transformer T is demagnetized, the resonance current of the transformer T in a resonance stage is obtained, wherein the resonance current is used for controlling the conduction of the main switching tube Q1 at the moment when the resonance current is zero.
Exemplarily, when the demagnetization of the transformer T is finished, the inductance of the main winding and the parasitic capacitance of the main switching tube Q1 form an LC resonance, the resonance amplitude of the auxiliary winding is 2Vout/Ns × NA, the intermediate voltage is 0V, and at this time, the third switch S3 is closed, and both the second switch S2 and the first switch S1 are in an open state. The positive voltage does not charge the positive pin VDD of the power supply, and the negative voltage does not discharge current due to the reverse bias of D2. By detecting the electrical signal of the DEM pin, the main switching tube Q1 can be controlled to be turned on again when the resonance current on the main winding is detected to be 0. As can be seen from the above, the power supply circuit scheme of this embodiment does not affect the existing QR detection, that is, the stabilization and clamping of the chip voltage are achieved without affecting the existing functions.
It is to be understood that the alternatives described above in embodiment 1 are equally applicable to the power converter 100 in this embodiment, and therefore, the description thereof will not be repeated here.
Example 3
Referring to fig. 6, the present embodiment further provides a power control chip U1, which can be used in the power converter 100 operating in the quasi-resonant mode. Exemplarily, the power control chip U1 includes: the device comprises a demagnetization detection pin DEM, a power supply positive electrode pin VDD, a power supply negative electrode pin GND, a built-in charging control module 120, a built-in sampling control module 130 and a voltage detection module 110. In some embodiments, the sampling control module 130 and the voltage detection module 110 may be peripheral circuits of the power control chip U1, and their location forms are not limited.
The demagnetization detection pin DEM is used for connecting an auxiliary winding of a transformer T in the converter; the power supply positive electrode pin VDD is used for being grounded through a power supply capacitor C1 and is also connected to a main winding of the transformer T through a current limiting resistor R1; the power supply cathode pin GND is used for grounding; the auxiliary winding and the main winding have the same polarity, and the main winding is used for being connected with a main switching tube Q1.
A first end of the sampling control module 130 is connected with the demagnetization detection pin DEM, a second end is connected with a first end of the charging control module 120, and a third end is connected with a power supply negative electrode pin GND; the second terminal of the charging control module 120 is connected to the output terminal of the voltage detection module 110, and the third terminal is connected to the positive power pin VDD. The input terminal of the voltage detection module 110 is connected to the positive power pin VDD.
The voltage detection module 110 is configured to detect a voltage of a positive pin VDD of the power supply, and output a path start signal when the voltage of the positive pin VDD of the power supply is lower than a preset value; the charging control module 120 is configured to control the second end of the sampling control module 130 to be in a conductive state with the power supply positive pin VDD when receiving the path start signal; the sampling control module 130 is configured to control a short circuit between the first end and the second end of the sampling control module 130 and an open circuit between the second end and the third end when the main switching tube Q1 is turned on after the second end of the sampling control module 130 and the power supply positive pin VDD are in a conductive state, so that a current generated by the auxiliary winding flows to the power supply capacitor C1 through the demagnetization detection pin DEM.
It is to be understood that the options regarding the power control chip in embodiment 1 described above are also applicable to this embodiment, and therefore, the description will not be repeated here.
The present application further provides an electronic device, exemplarily including the power converter in embodiment 1, wherein the power converter can perform circuit self-starting and stabilize the power supply voltage of the power control chip according to the power supply control method in embodiment 2.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application.
Claims (10)
1. A power converter, comprising: the transformer comprises a main winding and an auxiliary winding with the same polarity, the power supply control chip comprises a demagnetization detection pin, a power supply positive electrode pin, a power supply negative electrode pin and a charging control module, and the sampling control module and the voltage detection module are positioned inside or outside the power supply control chip;
the first end of the main winding is used for connecting input voltage, and the second end of the main winding is connected with the main switching tube;
the first end of the auxiliary winding is connected with the demagnetization detection pin, and the second end of the auxiliary winding is grounded;
the power supply positive electrode pin is grounded through the power supply capacitor and is also connected to the first end of the main winding through the current limiting resistor; the negative pin of the power supply is grounded;
the first end of the sampling control module is connected with the demagnetization detection pin, the second end of the sampling control module is connected with the first end of the charging control module, and the third end of the sampling control module is connected with the power supply negative electrode pin;
the second end of the charging control module is connected with the output end of the voltage detection module, and the third end of the charging control module is connected with the power supply positive electrode pin;
the input end of the voltage detection module is connected with the positive pin of the power supply.
2. The power converter according to claim 1, wherein the voltage detection module is configured to detect a voltage at the positive power pin and output a path on signal when the voltage at the positive power pin is lower than a preset value;
the charging control module is used for controlling the second end of the sampling control module and the power supply positive electrode pin to be in a conductive state when the access opening signal is received;
the charging control module comprises a switch unit and a clamping diode, wherein the first end of the switch unit is connected with the second end of the sampling control module, the second end of the switch unit is connected with the clamping diode arranged in the forward direction, and the third end of the switch unit is connected with the output end of the voltage detection module.
3. The power converter according to claim 2, wherein the switch unit comprises a current source, a voltage drop resistor, a first switch tube and a first switch, the voltage drop resistor is connected between a control end and a first end of the first switch tube in parallel, the first end of the first switch tube is connected with a second end of the sampling control module, the second end of the first switch tube is connected with the clamping diode, and the control end of the first switch tube is connected with the first end of the first switch;
the second end of the first switch is connected with the current source, and the control end of the first switch is connected with the voltage detection module.
4. The power converter according to claim 3, wherein the first switch tube is a MOS tube or a triode.
5. The power converter according to any one of claims 1 to 4, wherein the sampling control module is configured to control a short circuit between the first terminal and the second terminal and a short circuit between the second terminal and the third terminal of the sampling control module when the main switching tube is turned on after the second terminal of the sampling control module and the positive power pin are in a conductive state, so that a current generated by the auxiliary winding flows from the demagnetization detection pin to the supply capacitor;
the sampling control module comprises a second switch, a third switch and a voltage division unit formed by connecting a first resistor and a second resistor in series;
one end of the first resistor is connected with the demagnetization detection pin, and the other end of the first resistor is respectively connected with one end of the second resistor and the first end of the charging control module;
the second switch is connected in parallel with two ends of the first resistor;
the other end of the second resistor is connected with one end of the third switch, and the other end of the third switch is connected with the negative pin of the power supply.
6. The power converter of claim 1, wherein the transformer includes a secondary winding having an opposite polarity to the primary winding, the power converter further comprising: the homonymous end of the secondary winding is connected to the anode of the output capacitor through the rectifier diode arranged in the forward direction, and the synonym end of the secondary winding is connected to the cathode of the output capacitor.
7. The power converter according to claim 1, wherein the different-name terminal of the main winding is used for connecting the input voltage, and the same-name terminal is connected with the main switching tube;
the synonym end of the auxiliary winding is connected with the demagnetization detection pin, and the homonym end is grounded.
8. The power converter of claim 7, further comprising: the input end of the full-bridge rectification circuit is used for connecting an alternating current power supply, and the output end of the full-bridge rectification circuit is used for connecting the filter capacitor; and the anode of the filter capacitor is connected with the synonym end of the main winding, and the cathode of the filter capacitor is grounded.
9. The power converter of any of claims 6-8, further comprising: and the absorption circuits are connected in parallel to two ends of the main winding.
10. A power control chip, comprising: the device comprises a demagnetization detection pin, a power supply positive electrode pin, a power supply negative electrode pin, a sampling control module, a charging control module and a voltage detection module;
the demagnetization detection pin is used for connecting an auxiliary winding of a transformer in the power converter;
the power supply positive electrode pin is used for being grounded through a power supply capacitor and is also connected to a main winding of the transformer through a current limiting resistor; the power supply negative electrode pin is used for grounding; the polarity of the auxiliary winding is the same as that of the main winding, and the main winding is connected with a main switching tube in the power converter;
the first end of the sampling control module is connected with the demagnetization detection pin, the second end of the sampling control module is connected with the first end of the charging control module, and the third end of the sampling control module is connected with the power supply negative electrode pin;
the second end of the charging control module is connected with the output end of the voltage detection module, and the third end of the charging control module is connected with the power supply positive electrode pin;
the input end of the voltage detection module is connected with the positive pin of the power supply.
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| CN202120527911.5U CN214506884U (en) | 2021-03-11 | 2021-03-11 | Power converter and power control chip |
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| CN202120527911.5U CN214506884U (en) | 2021-03-11 | 2021-03-11 | Power converter and power control chip |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114597863A (en) * | 2022-03-07 | 2022-06-07 | 潍柴动力股份有限公司 | Power supply protection circuit |
| CN115102370A (en) * | 2022-08-03 | 2022-09-23 | 深圳原能电器有限公司 | Current detection circuit and control method |
| CN115967258A (en) * | 2023-02-21 | 2023-04-14 | 恩赛半导体(成都)有限公司 | Power supply circuit, power supply system and electronic device |
| CN116488433A (en) * | 2023-06-21 | 2023-07-25 | 成都智融微电子有限公司 | Auxiliary power supply circuit of switching power supply and control method thereof |
| WO2023198170A1 (en) * | 2022-04-14 | 2023-10-19 | 深圳英集芯科技股份有限公司 | High-voltage power supply circuit and apparatus for switching power supply |
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2021
- 2021-03-11 CN CN202120527911.5U patent/CN214506884U/en active Active
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114597863A (en) * | 2022-03-07 | 2022-06-07 | 潍柴动力股份有限公司 | Power supply protection circuit |
| CN114597863B (en) * | 2022-03-07 | 2024-02-20 | 潍柴动力股份有限公司 | Power protection circuit |
| WO2023198170A1 (en) * | 2022-04-14 | 2023-10-19 | 深圳英集芯科技股份有限公司 | High-voltage power supply circuit and apparatus for switching power supply |
| CN115102370A (en) * | 2022-08-03 | 2022-09-23 | 深圳原能电器有限公司 | Current detection circuit and control method |
| CN115967258A (en) * | 2023-02-21 | 2023-04-14 | 恩赛半导体(成都)有限公司 | Power supply circuit, power supply system and electronic device |
| CN115967258B (en) * | 2023-02-21 | 2023-05-23 | 恩赛半导体(成都)有限公司 | Power supply circuit, power supply system and electronic device |
| CN116488433A (en) * | 2023-06-21 | 2023-07-25 | 成都智融微电子有限公司 | Auxiliary power supply circuit of switching power supply and control method thereof |
| CN116488433B (en) * | 2023-06-21 | 2023-09-12 | 成都智融微电子有限公司 | Auxiliary power supply circuit of switching power supply and control method thereof |
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