CN114710030A - Linear voltage stabilizing circuit and switching power supply - Google Patents

Linear voltage stabilizing circuit and switching power supply Download PDF

Info

Publication number
CN114710030A
CN114710030A CN202111308047.0A CN202111308047A CN114710030A CN 114710030 A CN114710030 A CN 114710030A CN 202111308047 A CN202111308047 A CN 202111308047A CN 114710030 A CN114710030 A CN 114710030A
Authority
CN
China
Prior art keywords
voltage
circuit
resistor
linear voltage
power switch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202111308047.0A
Other languages
Chinese (zh)
Inventor
刘建利
万春茂
胡月霞
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hangzhou Deming Electronic Co ltd
Joulwatt Technology Co Ltd
Original Assignee
Hangzhou Deming Electronic Co ltd
Joulwatt Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hangzhou Deming Electronic Co ltd, Joulwatt Technology Co Ltd filed Critical Hangzhou Deming Electronic Co ltd
Priority to CN202111308047.0A priority Critical patent/CN114710030A/en
Publication of CN114710030A publication Critical patent/CN114710030A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/06—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • H02M7/062—Avoiding or suppressing excessive transient voltages or currents

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses a linear voltage stabilizing circuit and a switch power supply, wherein the linear voltage stabilizing circuit comprises: the power switch tube and a drive control circuit thereof; the inductor is connected in the voltage output loop in series; the sampling resistor is used for sampling the loop current in the voltage output loop; and the voltage regulating circuit is used for regulating the grid voltage of the power switching tube according to the loop current obtained by sampling the sampling resistor so as to control the switching state of the power switching tube when surge current occurs in the circuit, wherein when the surge current occurs in the circuit, the inductor is used for reducing the change rate of the loop current in the voltage output loop. The invention can prolong the energy release time of surge current in the loop, greatly reduce the surge energy in the loop in unit time, effectively meet the high surge protection requirement of the switching power supply while reducing the loop impedance of the circuit, and improve the output load capacity of the power supply when low voltage is input.

Description

Linear voltage stabilizing circuit and switching power supply
Technical Field
The invention relates to the technical field of power electronics, in particular to a linear voltage stabilizing circuit and a switching power supply.
Background
In the power electric meter industry, power frequency transformers are generally adopted for supplying power for early electric meter power supply systems, along with the development of technologies, the functions of electric meters are gradually increased, and accordingly, higher requirements are placed on power supply of the electric meter systems, the power frequency transformers cannot meet the requirements regardless of size or efficiency, and then a design scheme that a switching power supply is gradually adopted to replace the power frequency transformers is started. However, the application of the switching power supply brings new problems, and according to the national grid requirements, the ground fault of the electric meter needs to meet 1.9 times of Un (rated voltage of the electric meter), namely, the maximum voltage can reach 3 × 420Vac, and then a margin is reserved, and under the severe input condition of 3 × 440Vac, the electric meter should not be damaged and converted into direct current voltage, and the peak voltage is close to 1100V. At present, a common switching power supply is difficult to meet the high voltage input, and simultaneously, the surge protection requirement of differential mode 6.6KV needs to be met.
However, although the conventional clamping circuit can solve the problem of high-voltage input, the conventional clamping circuit can solve the high surge protection requirement, and a high-impedance current-limiting resistor needs to be added in the whole circuit to absorb surge energy to achieve the purpose of high surge protection, but the large resistor is connected in series in the circuit to consume large energy, so that the working efficiency of the circuit is influenced, and particularly, when an electric meter has a requirement on standby power consumption, the influence is particularly obvious. In addition, the large resistor can generate obvious voltage drop on the resistor in wide application, especially in low-voltage 36Vac input, and the output load capacity of the power supply is seriously influenced.
Therefore, there is a need to provide an improved technical solution to overcome the above technical problems in the prior art.
Disclosure of Invention
In order to solve the technical problems, the invention provides a linear voltage stabilizing circuit and a switching power supply, which can prolong the energy release time of surge current in a loop, greatly reduce the surge energy in the loop in unit time, effectively meet the high surge protection requirement of the switching power supply while reducing the loop impedance of the circuit, improve the working efficiency of the circuit and the output load capacity of the power supply during low-voltage input, and simultaneously realize the clamping protection of a rear-stage circuit under the condition of ultrahigh-voltage input, reduce the stress of a rear-stage device and further reduce the cost.
According to a first aspect of the present disclosure, there is provided a linear voltage stabilizing circuit, comprising: the power switch tube and the drive control circuit thereof, the power switch tube is connected in series in the voltage output loop of the linear voltage stabilizing circuit, the drive control circuit adjusts the power switch tube to output the preset output voltage, wherein, the linear voltage stabilizing circuit also comprises:
the inductor is connected in the voltage output loop in series and is connected with the drain electrode of the power switch tube;
the sampling resistor is connected in the voltage output loop in series and is connected with the source electrode of the power switch tube so as to sample loop current in the voltage output loop;
the voltage regulating circuit is used for regulating the grid voltage of the power switching tube according to the loop current obtained by sampling the sampling resistor so as to control the switching state of the power switching tube when surge current occurs in the circuit,
when surge current occurs in the circuit, the inductor is used for reducing the change rate of loop current in the voltage output loop.
Further, the voltage regulating circuit controls the gate voltage of the power switch tube according to the loop current to control the switching state of the power switch tube at least comprises pulling down the gate voltage of the power switch tube to enable the power switch tube to work in a switching mode.
Optionally, the voltage regulating circuit comprises:
and the base of the bipolar transistor is connected with the sampling resistor through a seventh resistor, and the collector of the bipolar transistor is connected with the grid of the power switch tube and used for adjusting the grid voltage of the power switch tube according to the loop current.
Optionally, the voltage regulating circuit further comprises:
and the feedback unit is connected between the inductor and the base electrode of the bipolar transistor and used for carrying out current positive feedback on the base electrode of the bipolar transistor based on the inductor.
Optionally, the feedback unit includes: an eighth resistor and a fourth capacitor,
the first end of the eighth resistor is connected with the drain electrode of the power switch tube, the second end of the eighth resistor is connected with the first end of the fourth capacitor, and the second end of the fourth capacitor is connected with the base electrode of the bipolar transistor.
Optionally, the linear voltage stabilizing circuit further comprises:
and the anode of the fourth diode is connected with the emitter of the bipolar transistor, and the cathode of the fourth diode is connected with the base of the bipolar transistor.
Optionally, the linear voltage stabilizing circuit further comprises:
and the voltage dependent resistor is connected between the drain electrode and the source electrode of the power switch tube and used for discharging at least part of surge energy when the drain electrode voltage of the power switch tube is higher than the voltage dependent voltage of the voltage dependent resistor.
Optionally, a first clamping unit is connected in parallel to two ends of the sampling resistor, and is configured to clamp a voltage across the sampling resistor.
Optionally, the linear voltage stabilizing circuit further comprises:
and the second clamping unit is connected between the grid electrode of the power switch tube and the emitter electrode of the bipolar transistor and is used for clamping the grid electrode voltage of the power switch tube.
Optionally, the linear voltage stabilizing circuit further comprises:
and the power supply unit is used for receiving the input voltage of the linear voltage stabilizing circuit and providing power supply voltage for the drive control circuit and the power switch tube according to the input voltage.
Optionally, the first clamping unit includes: a first diode and a second diode, wherein,
the anode of the first diode is connected with the source electrode of the power switch tube, the cathode of the first diode is connected with the anode of the second diode, and the cathode of the second diode is connected with the emitter of the bipolar transistor.
Optionally, the second clamping unit includes: a first resistor and a first zener diode,
the first end of the first resistor is connected with the grid electrode of the power switch tube, the second end of the first resistor is connected with the cathode of the first voltage stabilizing diode, and the anode of the first voltage stabilizing diode is connected with the emitting electrode of the bipolar transistor.
Optionally, the power supply unit includes:
the anode of the second voltage stabilizing diode receives the input voltage, and the cathode of the second voltage stabilizing diode is connected with the first node through a second resistor;
a first capacitor connected between the first node and a reference ground; and
a third resistor and a second capacitor, which are connected in series between the cathode of the second Zener diode and the reference ground,
wherein the power supply unit outputs the supply voltage at the first node.
Optionally, the power supply unit comprises:
a fourth resistor, a first end of which receives the input voltage;
a first end of the fifth resistor is connected with a second end of the fourth resistor;
the anode of the third diode is connected with the second end of the fifth resistor, and the cathode of the third diode is connected with the second node;
a third capacitor connected in parallel with the fourth resistor,
wherein the power supply unit outputs the supply voltage at the second node.
Optionally, the linear voltage stabilizing circuit further comprises:
the sixth resistor is connected between the grid electrode of the power switch tube and the drain electrode of the power switch tube;
and the seventh resistor is connected between the source electrode of the power switch tube and the base electrode of the bipolar transistor.
Optionally, the power switch tube and the driving control circuit are integrated in the same chip.
Optionally, the chip comprises:
a first pin receiving the supply voltage;
the second pin is connected with a collector of the bipolar transistor;
the third pin is connected with the inductor;
the fourth pin is connected with the sampling resistor;
and the fifth pin is connected with the fourth pin.
Optionally, the chip comprises:
a sixth pin, receiving the supply voltage, and connected to a collector of the bipolar transistor;
a seventh pin connected to the inductor;
the eighth pin is connected with the sampling resistor;
and a ninth pin.
Optionally, the linear voltage regulating circuit further comprises:
and the sixth resistor is connected between the second pin and the third pin.
Optionally, the linear voltage stabilizing circuit further comprises:
and the ninth resistor is connected between the ninth pin and the reference ground.
Optionally, the resistance value of the sampling resistor is smaller than a preset value.
Optionally, the inductor is connected between the output end of the linear voltage stabilizing circuit and the drain of the power switching tube, or the inductor is connected between the input end of the linear voltage stabilizing circuit and the drain of the power switching tube.
According to a second aspect of the present disclosure, there is provided a switching power supply including: the three-phase conversion circuit receives the power grid voltage and outputs a first voltage signal;
the linear voltage stabilizing circuit is connected with the three-phase conversion circuit, receives the first voltage signal and outputs a preset second voltage signal.
The beneficial effects of the invention at least comprise:
the linear voltage stabilizing circuit disclosed by the invention has the advantages that through serially connecting the inductor in the output loop of the linear voltage stabilizing circuit, so that the change rate of the current in the loop can be reduced when the circuit generates surge current, the surge current is slowly increased, meanwhile, by arranging a sampling resistor and a voltage regulating circuit, the sampling resistor samples the current in the loop and triggers the voltage regulating circuit to control the grid voltage of the power switching tube so as to control the switching state of the power switching tube, for example, the gate voltage of the power switch tube is pulled down to control the power switch tube to operate in the switch mode, and furthermore, in the continuous on-off process of the power switch tube, the energy release time of the surge current in the loop is prolonged, the surge energy in the loop in unit time is greatly reduced, the current in the output loop is reduced, and the linear voltage stabilizing circuit also has the surge current protection function. In addition, the impedance of the inductor is relatively low, which is beneficial to improving the working efficiency of the circuit and the output load capacity of the switching power supply when low voltage is input.
The switching power supply disclosed by the invention can reduce the resistance value requirement of the surge protection resistor required to be adopted in a preceding stage circuit (such as a three-phase conversion circuit) of the linear voltage stabilizing circuit in the switching power supply based on the surge protection capability of the linear voltage stabilizing circuit, and greatly reduces the loop impedance in the switching power supply while ensuring that the switching power supply can meet the specified surge protection requirement.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
Fig. 1 shows a schematic diagram of a three-phase converter circuit according to the prior art;
FIG. 2 is a schematic diagram illustrating a conventional linear voltage regulator circuit;
fig. 3 is a schematic structural diagram of a three-phase conversion circuit provided according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating a structure of a linear voltage regulating circuit according to a first embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating a linear voltage regulating circuit according to a second embodiment of the present invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
In a switching power supply, such as an electric meter switching power supply, a three-phase conversion circuit and a linear voltage stabilizing circuit are generally included. The three-phase conversion circuit is used for receiving the power grid voltage and outputting a first voltage signal after converting the received power grid voltage; the linear voltage stabilizing circuit is connected with the output end of the three-phase conversion circuit and used for receiving the first voltage signal and outputting a preset second voltage signal according to the first voltage signal.
Fig. 1 is a schematic diagram of a conventional three-phase converter circuit. The three-phase conversion circuit includes: three-phase rectifier circuit 1, filter capacitance CX1 and common mode inductance LF 1. The three-phase rectification circuit 1 is respectively connected with the first phase input end L1, the second phase input end L2, the third phase input end L3 and the neutral line input end N to perform three-phase rectification on the grid voltage input from the first phase input end L1, the second phase input end L2, the third phase input end L3 and the neutral line input end N. The rectified voltage is converted into a first voltage signal Vdc after being filtered by the filter capacitor CX1 and the common mode inductor LF1, and the first voltage signal Vdc is output from the output end of the three-phase conversion circuit.
In fig. 1, wire-wound resistors RX1, RX2, and RX3 are further respectively connected in series between each of the first phase input end L1, the second phase input end L2, and the third phase input end L3 and the three-phase rectification circuit 1, a wire-wound resistor RX4 is further connected in series between the common mode inductor LF1 and one of the output ends of the three-phase conversion circuit, the wire-wound resistors are used for limiting current in the three-phase conversion circuit, and meanwhile, piezoresistors RV1, RV2, and RV3 are further respectively connected between each of the first phase input end L1, the second phase input end L2, and the third phase input end L3 and the neutral input end N.
Fig. 2 is a schematic diagram of a conventional linear voltage regulator circuit. The linear voltage regulator circuit includes a clamp chip controller U1 having a power switch transistor Q1, and the power switch transistor Q1 is connected at the low end of the load output. When the input voltage Vdc of the linear voltage stabilizing circuit is higher than the set voltage, the clamp chip controller U1 adjusts the driving voltage of the power switch tube Q1 through an internal circuit, so that the power switch tube Q1 is in a linear region, and when the input voltage Vdc is higher, the control end voltage of the power switch tube Q1 is lower, the voltage between the drain and the source of the power switch tube Q1 is higher, thereby ensuring the stability of the output voltage Vout.
After the above fig. 1 and fig. 2 are matched, that is, a structure of a conventional electric meter switching power supply is obtained, in which the wire-wound resistors RX1, RX2, RX3 and RX4, and the voltage dependent resistors RV1, RV2 and RV3, which are provided in the three-phase conversion circuit shown in fig. 1, can jointly implement a surge protection function of the switching power supply. However, in order to meet the ideal surge protection requirement of the conventional switching power supply, the three-phase rectifier circuit 1 is provided with wire-wound resistors for surge protection before and after rectification, which may further result in large loop impedance of the circuit and affect the working efficiency of the switching power supply, and especially under the condition of low-voltage input, the efficiency is affected more obviously. Meanwhile, the large loop impedance also influences the loading capacity of the switching power supply when low voltage is input.
Aiming at the problems in the prior art, the invention respectively optimizes and improves the three-phase conversion circuit and the linear voltage stabilizing circuit in the switching power supply, and the improved switching power supply can meet the requirement of high surge protection and simultaneously reduce the impedance in a loop, thereby improving the working efficiency and the output load capacity of the power supply at low voltage input.
Fig. 3 is a schematic structural diagram of a three-phase conversion circuit in the switching power supply according to the embodiment of the present invention. Compared with the three-phase conversion circuit shown in fig. 1, the winding resistors RX1, RX2, and RX3 respectively connected in series between each of the first phase input terminal L1, the second phase input terminal L2, and the third phase input terminal L3 and the three-phase rectification circuit 1 in the three-phase conversion circuit 10 in this embodiment are replaced by the first winding resistor RX11, the second winding resistor RX21, and the third winding resistor RX31, wherein the impedances of the first winding resistor RX11, the second winding resistor RX21, and the third winding resistor RX31 are all smaller than the impedances of the winding resistors RX1, RX2, and RX 3. Meanwhile, the wire-wound resistor RX4 connected in series between the common mode inductor LF1 and one of the output ends of the three-phase conversion circuit is eliminated, so that the optimized three-phase conversion circuit greatly reduces the loop impedance, and improves the output load capacity of a power supply at low-voltage input.
For example, if the resistances of the winding resistors RX1, RX2, and RX3 in fig. 1 are all 22 ohms, and the resistance of the winding resistor RX4 in fig. 1 is 47 ohms, the resistances of the first winding resistor RX11, the second winding resistor RX21, and the third winding resistor RX31 in the optimized three-phase transformation circuit of the present invention may all be reduced to 10 ohms, that is, the loop impedance in the optimized three-phase transformation circuit of the present invention may be changed from 91 ohms to 20 ohms, which is only lower than 1/4 ohms.
Meanwhile, the invention also provides a linear voltage stabilizing circuit in the switching power supply matched with the circuit shown in the figure 3, the linear voltage stabilizing circuit is connected with an inductor in series in an output loop, so that the change rate of current in the loop can be reduced when the circuit generates surge current, the surge current is slowly increased, the sampling resistor samples the current in the loop and triggers the voltage regulating circuit to control the grid voltage of the power switch tube so as to control the working state of the power switch tube (at least including pulling down the grid voltage of the power switch tube so as to enable the power switch tube to work in a switching mode), and further, the current in the output loop is reduced, so that the linear voltage stabilizing circuit can also have the surge current protection function, and the problem that the surge protection capability of the switching power supply is reduced due to the reduction of the total resistance value of the surge protection resistor in fig. 3 is solved. In addition, because the impedance of the inductor is relatively low, the switching power supply based on the technical scheme of the invention can effectively meet the high surge protection requirement while reducing the loop impedance, and improves the working efficiency and the output load capacity of the power supply during low-voltage input.
Referring to fig. 4 and 5, the linear regulator circuit 20 of the present invention includes a power switch Q1 and a driving control circuit thereof, the power switch Q1 is connected in series in a voltage output loop of the linear regulator circuit 20, and the driving control circuit is connected to the power switch Q1 for adjusting a switching state of the power switch Q1 to output a predetermined output voltage Vout. In the invention, the linear voltage stabilizing circuit comprises a first input end, a second input end, a first output end and a second output end, wherein the first input end and the second input end are used for receiving a first voltage signal Vdc, the linear voltage stabilizing circuit receives an input voltage (such as the first voltage signal output by the three-phase conversion circuit) Vdc from the first input end and the second input end, and outputs a preset second voltage signal, namely a preset output voltage Vout, from the first output end and the second output end. Illustratively, in the present invention, the first input terminal of the linear voltage stabilizing circuit 10 is a high voltage input terminal, the second input terminal of the linear voltage stabilizing circuit 20 is a low voltage input terminal, the first output terminal of the linear voltage stabilizing circuit 10 is a high voltage output terminal, the second output terminal of the linear voltage stabilizing circuit 10 is a low voltage output terminal, and the low voltage input terminal and the low voltage output terminal of the linear voltage stabilizing circuit 20 are both connected to the reference ground. Illustratively, the power switch Q1 is, for example, an NMOS transistor.
Two embodiments of the present invention are used to describe the linear voltage regulating circuit 20 in detail. In a first embodiment of the present invention, as shown in FIG. 4, which illustrates an implementation of the present invention in which the input and output of the linear voltage regulating circuit 20 are connected in common, a power switch Q1 is connected in series between the low voltage input terminal and the low voltage output terminal of the linear voltage regulating circuit 20. In a second embodiment of the present invention, as shown in FIG. 5, an implementation of the input and output common power supply of the linear voltage regulating circuit 20 of the present invention is shown, in which a power switch Q1 is connected in series between the high voltage input terminal and the high voltage output terminal of the linear voltage regulating circuit 20. It is understood that the first and second embodiments shown in fig. 4 and 5, respectively, are based on the same inventive concept, and the specific operation principle is substantially the same, only the difference in specific circuit implementation is made.
Optionally, the power switch Q1 and the driving control circuit in the linear voltage regulator circuit 20 of the present invention may be independent components or modules separately provided, or may be integrated in the same chip U1, which is not limited in this disclosure. Therefore, it should be understood that the drawings (such as fig. 4 and 5) in the specification are only based on the consideration of simplified drawings, and the power switch Q1 and the driving control circuit are illustrated as being integrated in the same chip U1, which should not be construed as limiting the invention. Illustratively, when the power switch Q1 and the driving control circuit are integrated in the same chip, in the embodiment shown in fig. 4, the chip U1 includes at least five pins, specifically, a first pin VCC, for receiving the supply voltage; a second pin G connected to the collector of the bipolar transistor Q2 in the voltage regulator circuit 26 and to the gate of the power switch Q1 via the controller 25; a third pin D connected to inductor L1; the fourth pin S is connected to the low voltage output terminal of the circuit 20, i.e., the reference ground, via the sampling resistor Rs 1; the fifth pin GND is connected to the fourth pin S. In the first embodiment shown in fig. 4, a sixth resistor R6 is connected between the second pin G and the third pin D, and the sixth resistor R6 is used for sampling the output voltage Vout of the circuit 20 when the circuit is operating normally to realize the adjustment of the gate voltage of the power switch Q1. In the embodiment shown in fig. 5, the chip U1 includes at least four pins, specifically, a sixth pin G, which is connected to the gate of the power switch Q1 via the controller 25, receives the supply voltage, and is connected to the collector of the bipolar transistor Q2 in the voltage regulation circuit 26; a seventh pin D connected to the inductor L1; the eighth pin S is connected to the high voltage output terminal of the circuit 20 through a sampling resistor Rs 1; the ninth pin Isen is connected to the low voltage output terminal of the circuit 20, i.e. the ground reference, through a ninth resistor Rs2, and the ninth resistor Rs2 is used for sampling the output voltage Vout of the circuit 20 when the circuit is in normal operation to adjust the gate voltage of the power switch Q1.
Alternatively, the controller 25 may be a driving control circuit or a sub-circuit of the driving control circuit, or may also be a circuit module in the chip U1, which is parallel to the driving control circuit, and may be specifically set according to the actual integration process and circuit requirements, which is not limited in this disclosure.
In the present invention, the linear voltage regulating circuit 20 further includes: inductor L1, sampling resistor Rs1, and voltage regulation circuit 26. The inductor L1 is connected in series in the voltage output loop and is connected with the drain of the power switch tube Q1. The sampling resistor Rs1 is connected in series in the voltage output loop and connected with the source of the power switch tube Q1 for sampling the loop current in the voltage output loop. The voltage regulating circuit 26 is used for regulating the grid voltage of the power switch tube Q1 according to the loop current. Based on the inductor L1, the sampling resistor Rs1 and the voltage regulating circuit 26, when an inrush current occurs in the circuit, the inductor L1 is used to reduce the change rate of the loop current in the voltage output loop, and the voltage regulating circuit 26 controls the gate voltage of the power switching tube Q1 according to the loop current obtained by sampling the sampling resistor Rs1 to control the switching state of the power switching tube Q1, wherein at least the gate voltage of the power switching tube Q1 is pulled down so that the power switching tube Q1 works in the switching mode, thereby realizing protection against the inrush current.
In one possible embodiment of the present invention, the voltage regulation circuit 26 includes a bipolar transistor Q2, the base of the bipolar transistor Q2 is connected to a resistor Rs1 through a seventh resistor R7, and the collector of the bipolar transistor Q2 is connected to the gate of the power switch Q1. The seventh resistor R7 is used to limit the current on the base of the bipolar transistor Q2, and protect the bipolar transistor Q2.
In the invention, the resistance value of the sampling resistor Rs1 is smaller than a preset value, so that the influence of the impedance of the sampling resistor Rs1 on the impedance of the whole loop is reduced as much as possible while the sampling effect is realized.
In the first embodiment shown in fig. 4, an inductor L1 is connected in series between the drain of the power switch Q1 and the low voltage output terminal of the linear regulator circuit 20, a sampling resistor Rs1 is connected between the source of the power switch Q1 and the low voltage input terminal of the linear regulator circuit 20, the base of the bipolar transistor Q2 is connected to the common connection point of the sampling resistor Rs1 and the power switch Q1, i.e., the source of the power switch Q1 through a seventh resistor R7, the collector of the bipolar transistor Q2 is connected to the gate of the power switch Q1, and the emitter of the bipolar transistor Q2 is connected to the low voltage input terminal of the linear regulator circuit 20. In the second embodiment shown in fig. 5, an inductor L1 is connected in series between the drain of the power switch Q1 and the high voltage input terminal of the linear regulator circuit 20, a sampling resistor Rs1 is connected between the source of the power switch Q1 and the high voltage output terminal of the linear regulator circuit 20, the base of the bipolar transistor Q2 is connected to the common connection point of the sampling resistor Rs1 and the power switch Q1, i.e., the source of the power switch Q1 through a seventh resistor R7, the collector of the bipolar transistor Q2 is connected to the gate of the power switch Q1, and the emitter of the bipolar transistor Q2 is connected to the high voltage output terminal of the linear regulator circuit 20.
Further, the linear voltage regulating circuit 20 further includes: and a piezoresistor RV 4. The voltage dependent resistor RV4 is connected between the drain and the source of the power switch transistor Q1, and is used for discharging at least part of surge energy when the drain voltage of the power switch transistor Q1 is higher than the voltage dependent voltage of the voltage dependent resistor RV 4.
Further, the present invention further includes a first clamping unit 21 connected in parallel to two ends of the sampling resistor Rs1, where the first clamping unit 21 is configured to clamp the voltage across the sampling resistor Rs1, so as to protect the sampling resistor Rs1 and the triode Q2 from being damaged when a surge current occurs in the circuit. Illustratively, the first clamping unit 21 includes a first diode D1 and a second diode D2. The anode of the first diode D1 is connected to the source of the power switch Q1, the cathode of the first diode D1 is connected to the anode of the second diode D2, and the cathode of the second diode D2 is connected to the emitter of the bipolar transistor Q2.
Further, the linear voltage regulating circuit 20 further includes: and a second clamping unit 22. The second clamping unit 22 is connected between the gate of the power switch Q1 and the emitter of the bipolar transistor Q2, and is used for clamping the gate voltage of the power switch Q1, so as to protect the power switch Q1 from being damaged due to the excessively high gate voltage. Illustratively, the second clamping unit 22 includes a first resistor R1 and a first zener diode ZV 1. The first end of the first resistor R1 is connected with the grid of the power switch tube Q1, the second end of the first resistor R1 is connected with the cathode of the first voltage-stabilizing diode ZV1, and the anode of the first voltage-stabilizing diode ZV1 is connected with the emitter of the bipolar transistor Q2.
Further, the linear voltage regulating circuit 20 further includes: a power supply unit 23. The power supply unit 23 receives the input voltage Vdc of the linear voltage regulator circuit 20, and is configured to provide a power supply voltage for the chip U1 (including the driving control circuit and the power switch Q1) according to the input voltage Vdc.
In the first embodiment shown in fig. 4, the power supply unit 23 and the first pin VCC of the chip U1 are connected to a first node a, and then a power supply voltage is output at the first node a. Illustratively, the power supply unit 23 includes: a second zener diode ZV2, a second resistor R2, a first capacitor C2, a third resistor R3 and a second capacitor C4. Wherein the anode of the second zener diode ZV2 receives the input voltage Vdc, and the cathode of the second zener diode ZV2 is connected to the first node a through the second resistor R2; the first capacitor C2 is connected between the first node a and the reference ground; and a third resistor R3 and a second capacitor C4 are sequentially connected in series between the cathode of the second Zener diode ZV2 and the ground. In the second embodiment shown in fig. 5, the power supply unit 23 and the sixth pin G of the chip U1 are connected to the second node b, and then output a power supply voltage at the second node b. Illustratively, the power supply unit 23 includes: a fourth resistor R4, a fifth resistor R5, a third diode D3 and a third capacitor C6. Wherein, the first end of the fourth resistor R4 receives the input voltage Vdc; a first end of the fifth resistor R5 is connected with a second end of the fourth resistor R4; an anode of the third diode D3 is connected to the second terminal of the fifth resistor R5, and a cathode of the third diode D3 is connected to the second node b; the third capacitor C6 is connected in parallel with the fourth resistor R4.
The specific working principle of the linear voltage stabilizing circuit 20 provided by the invention is as follows:
when a large surge current occurs in a loop of a circuit due to lightning strike, the surge current generates a large voltage across the sampling resistor Rs1, but due to the existence of the first clamping unit 21, the maximum voltage across the sampling resistor Rs1 can be clamped to about 1.4V, and the sampling resistor Rs1 and the bipolar transistor Q2 can be protected from being damaged. Meanwhile, because the inductor L1 is connected in series in the loop of the circuit, the surge current in the loop can be only slowly increased based on the principle that the inductor current cannot be suddenly changed. As the current in the loop increases, the voltage across the sampling resistor Rs1 also gradually begins to increase, when it increases to a certain extent, for example, when the current on the sampling resistor Rs1 satisfies IlimitWhen the value is approximately equal to 0.7V/Rs1, current starts to flow to the base of the bipolar transistor Q2 through the seventh resistor R7, and the current flowing to the base of the bipolar transistor Q2 also continuously increases along with the increase of surge current in the loop. At this time, based on the connection relationship between the bipolar transistor Q2 and the power switch Q1, the voltage of the gate of the power switch Q1 is gradually pulled down by the bipolar transistor Q2, so that the power switch Q1 is gradually turned off. When the power switch tube Q1 is turned off, the voltage at the common node where the drain of the power switch tube Q1 is connected with the inductor L1 starts to gradually increase, and when the voltage increases to be higher than the voltage-dependent voltage of the voltage-dependent resistor RV4, the voltage-dependent resistor RV4 starts to act, so that at least part of surge energy of surge current is consumed from the path of the voltage-dependent resistor RV 4. In other words, the highest voltage between the drain and the source of the power switch Q1 can be clamped by the varistor RV4, thereby protecting the power switch Q1 from being damaged by large voltage stress.
Meanwhile, after the power switch tube Q1 is turned off, the current in the loop starts to decrease, the voltage at the two ends of the sampling resistor Rs1 also decreases, and the current on the base of the bipolar transistor Q2 also starts to decrease gradually, so that the pull-down degree of the gate voltage of the power switch tube Q1 by the bipolar transistor Q2 starts to decrease, the power switch tube Q1 starts to gradually exit the off state, the current in the loop starts to increase, and the power switch tube Q1 forms a switching oscillation with a certain frequency to gradually discharge surge energy. If surge energy is generated within 8/20us of standard lightning stroke, the switch oscillation mode can prolong the energy release time of surge current in the loop to hundreds or even thousands of microseconds, greatly weakens the surge energy in the loop within unit time, reduces the stress of devices, further protects the devices in the circuit from being damaged, and achieves the purpose of reducing the surge current in the loop.
On the other hand, referring to fig. 2, when the conventional linear voltage regulator circuit is used for single-phase low-voltage input, especially when the voltage is supplied by only depending on the resistor R11 at an ac input lower than 36V, the voltage supplied to the power supply terminal VCC of the chip U1 at the bottom of the sine wave is lower, and it is difficult to ensure the fully-on state of the power switch Q1, because of the shortage of VCC power supply, the power switch Q1 is in a linear state at this time, and then a large voltage drop occurs between the drain and source terminals, which affects the load carrying capability of the subsequent output of the circuit. Based on this, referring to fig. 4, in the first embodiment of the present invention, the second zener diode ZV2, the third resistor R3 and the second capacitor C4 are added in the power supply unit 23, so that in a sine wave period, at the time of a voltage peak, the input voltage Vdc can supply power to the chip U1 through the second zener diode ZV2, and at the same time, the second capacitor C4 can be charged through the third resistor R3, and at the time of a voltage valley, the power supply terminal VCC of the chip U1 can be discharged through the third resistor R3 by the second capacitor C4. Therefore, the lowest voltage of the power supply terminal VCC of the chip U1 is raised, so that the power switch tube Q1 can have enough voltage to be completely conducted even at the valley bottom of the sine wave, the voltage drop between the drain and the source of the power switch tube Q1 is reduced, and the output load capacity of the linear voltage stabilizing circuit and the switching power supply in low voltage is improved.
Referring to fig. 5, in the second embodiment of the present invention, the power supply unit 23 is further configured to provide a driving level to the power switch Q1 in addition to supplying power to the chip U1, so that the power switch Q1 can operate normally after the circuit 20 is started. Meanwhile, based on the circuit structure of the power supply unit 23 in the second embodiment shown in fig. 5, the number of pins of the chip U1 in this embodiment can be reduced, which is helpful for reducing the manufacturing cost of the chip U1.
Further, the linear voltage regulating circuit 20 of the present invention further includes a feedback unit 24 connected between the drain of the power switch Q1 and the base of the bipolar transistor Q2. When an inrush current occurs in the circuit, the feedback unit 24 can perform current positive feedback on the base of the bipolar transistor Q2 based on the inductor L1. When a large surge current occurs in the circuit due to a lightning strike, based on the above description of the operating principle of the linear voltage stabilizing circuit 20, after the voltage of the gate of the linear power transistor Q1 is gradually pulled down by the bipolar transistor Q2, the voltage at the common node where the inductor L1 is connected to the drain of the linear power transistor Q1 will still continue to rise because the inductor current cannot suddenly change, but at this time, because the feedback unit 24 exists in the circuit, the current at the base of the bipolar transistor Q2 will still slowly increase to form a positive feedback, so that the power switch Q1 is turned off deeper, and the protection capability of the linear voltage stabilizing circuit 20 against the surge current is further enhanced.
Illustratively, the feedback unit 24 includes an eighth resistor R8 and a fourth capacitor C5. A first end of the eighth resistor R8 is connected to the drain of the power switch Q1, a second end of the eighth resistor R8 is connected to a first end of the fourth capacitor C5, and a second end of the fourth capacitor C5 is connected to the base of the bipolar transistor Q2.
Further, the linear voltage regulating circuit 20 at this time further includes: a fourth diode D4. The anode of the fourth diode D4 is connected to the emitter of the bipolar transistor Q2, and the cathode of the fourth diode D4 is connected to the base of the bipolar transistor Q2.
Further, at the moment of starting up, the surge energy in the loop is also large, the linear voltage stabilizing circuit works in the switching oscillation mode, at this time, there is a charging and discharging process in the fourth capacitor C5 in the feedback unit 24, and in the discharging phase of each oscillation cycle, the current on the fourth capacitor C5 mainly passes through the sampling resistor Rs1 and the seventh resistor R7 to form a discharging loop, so that a small voltage difference is formed between the sampling resistor Rs1 and the seventh resistor R7, that is, a small negative voltage Vbe is generated between the base and the emitter of the bipolar transistor Q2. According to the invention, the fourth diode D4 is arranged between the base electrode and the emitter electrode of the bipolar transistor Q2, so that the negative voltage can be clamped at 0.7V, the bipolar transistor Q2 is protected from being damaged by the negative voltage, and the reliability of the circuit is improved.
In summary, in the invention, an inductor is connected in series in an output loop of a linear voltage stabilizing circuit, so that when a surge current occurs in a circuit, the change rate of the current in the loop can be reduced, and the surge current is increased slowly, and meanwhile, by arranging a sampling resistor and a voltage regulating circuit, the current in the loop is sampled by the sampling resistor and the voltage regulating circuit is triggered to control the gate voltage of a power switching tube so as to control the switching state of the power switching tube, thereby prolonging the energy release time of the surge current in the loop in the continuous on-off process of the power switching tube, greatly reducing the surge energy in the loop in unit time, reducing the current in the output loop, and enabling the linear voltage stabilizing circuit to have the surge current protection function. In addition, the impedance of the inductor is relatively low, which is beneficial to improving the working efficiency of the circuit and the output load capacity of the switching power supply when low voltage is input.
On the other hand, the switching power supply disclosed by the invention can reduce the resistance value requirement of the surge protection resistor required in the preceding stage circuit (such as a three-phase conversion circuit) of the linear voltage stabilizing circuit in the switching power supply based on the surge protection capability of the linear voltage stabilizing circuit, so that the switching power supply can meet the specified surge protection requirement, meanwhile, the loop impedance in the switching power supply is greatly reduced, and the cost is reduced.
Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.

Claims (19)

1. A linear voltage regulator circuit, comprising: the power switch tube and the drive control circuit thereof, the power switch tube is connected in series in the voltage output loop of the linear voltage stabilizing circuit, the drive control circuit adjusts the power switch tube to output the preset output voltage, wherein, the linear voltage stabilizing circuit also comprises:
the inductor is connected in the voltage output loop in series;
the sampling resistor is connected in the voltage output loop in series and used for sampling loop current in the voltage output loop;
the voltage regulating circuit is used for regulating the grid voltage of the power switching tube according to the loop current obtained by sampling the sampling resistor so as to control the switching state of the power switching tube when surge current occurs in the circuit,
when surge current occurs in the circuit, the inductor is used for reducing the change rate of loop current in the voltage output loop.
2. The linear voltage regulating circuit of claim 1, wherein the voltage regulating circuit comprises:
and the base of the bipolar transistor is connected with the sampling resistor through a seventh resistor, and the collector of the bipolar transistor is connected with the grid of the power switch tube through a controller and used for adjusting the grid voltage of the power switch tube according to the loop current.
3. The linear voltage regulation circuit of claim 2, wherein the voltage regulation circuit further comprises:
and the feedback unit is connected between the inductor and the base electrode of the bipolar transistor and used for carrying out current positive feedback on the base electrode of the bipolar transistor based on the inductor.
4. The linear voltage regulating circuit of claim 3, wherein the feedback unit comprises: an eighth resistor and a fourth capacitor,
the first end of the eighth resistor is connected with the drain electrode of the power switch tube, the second end of the eighth resistor is connected with the first end of the fourth capacitor, and the second end of the fourth capacitor is connected with the base electrode of the bipolar transistor.
5. The linear voltage regulator circuit of claim 4, wherein the linear voltage regulator circuit further comprises:
and the anode of the fourth diode is connected with the emitter of the bipolar transistor, and the cathode of the fourth diode is connected with the base of the bipolar transistor.
6. The linear voltage regulator circuit of claim 1, wherein the linear voltage regulator circuit further comprises:
and the voltage dependent resistor is connected between the drain electrode and the source electrode of the power switch tube and used for discharging at least part of surge energy when the voltage of the drain electrode of the power switch tube is higher than the voltage dependent voltage of the voltage dependent resistor.
7. The linear voltage regulator circuit of claim 2, wherein a first clamping unit is connected in parallel across the sampling resistor for clamping the voltage across the sampling resistor.
8. The linear voltage regulator circuit of claim 7, wherein the linear voltage regulator circuit further comprises:
and the second clamping unit is connected between the grid electrode of the power switch tube and the emitter electrode of the bipolar transistor and used for clamping the grid electrode voltage of the power switch tube.
9. The linear voltage regulator circuit of claim 2, wherein the linear voltage regulator circuit further comprises:
and the power supply unit is used for receiving the input voltage of the linear voltage stabilizing circuit and providing power supply voltage for the drive control circuit and the power switch tube according to the input voltage.
10. The linear voltage regulator circuit of claim 9, wherein the power switching transistor and the drive control circuit are integrated within a same chip.
11. The linear voltage regulating circuit of claim 10, wherein the power supply unit comprises:
the anode of the second voltage stabilizing diode receives the input voltage, and the cathode of the second voltage stabilizing diode is connected with the first node through a second resistor;
a first capacitor connected between the first node and a reference ground; and
a third resistor and a second capacitor, which are connected in series between the cathode of the second Zener diode and the reference ground,
wherein the power supply unit outputs the supply voltage at the first node.
12. The linear voltage regulating circuit of claim 10, wherein the power supply unit comprises:
a fourth resistor, a first end of which receives the input voltage;
a first end of the fifth resistor is connected with a second end of the fourth resistor;
the anode of the third diode is connected with the second end of the fifth resistor, and the cathode of the third diode is connected with the second node;
a third capacitor connected in parallel with the fourth resistor,
wherein the power supply unit outputs the supply voltage at the second node.
13. The linear voltage regulator circuit of claim 11, wherein the chip comprises:
a first pin receiving the supply voltage;
the second pin is connected with a collector of the bipolar transistor;
the third pin is connected with the inductor;
the fourth pin is connected with the sampling resistor;
and the fifth pin, a chip reference ground pin, is connected with the fourth pin.
14. The linear voltage regulator circuit of claim 12, wherein the chip comprises:
a sixth pin, receiving the supply voltage, and connected to a collector of the bipolar transistor;
the seventh pin is connected with the drain electrode of the power switch tube and is connected with the inductor;
the eighth pin is connected with the sampling resistor;
and the ninth pin is connected with the source electrode of the power switch tube and is connected with a high potential node of the voltage output loop.
15. The linear voltage regulator circuit of claim 13, wherein the linear voltage regulator circuit further comprises:
and the sixth resistor is connected between the second pin and the third pin.
16. The linear voltage regulating circuit of claim 14, wherein said linear voltage regulating circuit further comprises:
and the ninth resistor is connected between the ninth pin and the reference ground.
17. The linear voltage regulating circuit of claim 1, wherein the resistance of the sampling resistor is less than a preset value.
18. The linear voltage regulating circuit of claim 1, wherein the inductor is connected between the output terminal of the linear voltage regulating circuit and the drain of the power switching tube, or the inductor is connected between the input terminal of the linear voltage regulating circuit and the drain of the power switching tube.
19. A switching power supply, comprising:
the three-phase conversion circuit receives the power grid voltage and outputs a first voltage signal;
the linear voltage regulator circuit of any of claims 1-18, coupled to the three phase inverter circuit, to receive the first voltage signal and to output a predetermined second voltage signal.
CN202111308047.0A 2021-11-05 2021-11-05 Linear voltage stabilizing circuit and switching power supply Pending CN114710030A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111308047.0A CN114710030A (en) 2021-11-05 2021-11-05 Linear voltage stabilizing circuit and switching power supply

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111308047.0A CN114710030A (en) 2021-11-05 2021-11-05 Linear voltage stabilizing circuit and switching power supply

Publications (1)

Publication Number Publication Date
CN114710030A true CN114710030A (en) 2022-07-05

Family

ID=82167768

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111308047.0A Pending CN114710030A (en) 2021-11-05 2021-11-05 Linear voltage stabilizing circuit and switching power supply

Country Status (1)

Country Link
CN (1) CN114710030A (en)

Similar Documents

Publication Publication Date Title
WO2006129152A1 (en) Active inrush current control using a relay for ac to dc converters
US10498222B2 (en) Power supply
CN215186536U (en) Motor controller and motor using same
CN111585266A (en) DC distribution electronic soft start switch
CN215528878U (en) Switching power supply device
CN100561816C (en) Burst current suppressing circuit and use its power supply device
CN108899876A (en) The short circuit protection system at current detecting end in Switching Power Supply
CN108134381A (en) Overvoltage crowbar, method and electronic equipment
CN216252552U (en) Switching power supply circuit
CN114710030A (en) Linear voltage stabilizing circuit and switching power supply
KR100724313B1 (en) Method for converting voltage and converter for performing the same
CN115694187A (en) Boost power conversion circuit and device
CN113541458B (en) Filter circuit
CN211018675U (en) Flyback AC-DC constant current power supply box
CN212969038U (en) Overvoltage protection circuit and electronic equipment
CN114710031A (en) Linear voltage stabilizing circuit and switching power supply
CN106411160A (en) Switching power supply
CN219041622U (en) Surge protection circuit is prevented to power
CN221103316U (en) Energy absorption loop, electronic switch driving circuit and electronic switch with surge protection and constant current control
CN220042989U (en) Surge protection circuit and switching power supply
CN114362499B (en) Protection circuit and full-control rectifying circuit
CN216819698U (en) Terminal power supply circuit and device
CN217692764U (en) Capacitor discharge circuit
TWI808871B (en) Trip circuit of circuit breaker using power converter and rechargeable battery
US11682965B2 (en) Power supply with lightning protection

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination