CN100499340C - Winding Voltage Sampling Control Power Converter - Google Patents

Abstract

The invention relates to a winding voltage sampling control power converter, which comprises an input circuit, at least one switching component, a controller for controlling the switching component to act, and a winding voltage sampling device, wherein the input circuit is provided with an input end; a transformer having a primary winding connected to the switching element and the winding voltage sampling device and a secondary winding; an output circuit connected with the secondary side winding of the transformer and having an output end; the winding voltage sampling device detects the set reference point voltage of the primary side winding voltage of the transformer, and the controller can perform corresponding control, so that the invention has better control accuracy and efficiency, and has good economic benefit.

Description

Winding Voltage Sampling Control Power Converter

technical field

The invention relates to a power converter, in particular to a winding voltage sampling control power converter.

Background technique

The switching power converter has the characteristics of high efficiency and small size, and is currently widely used in various electronic devices. As shown in Figure 9, it is one of the circuit structures of a conventional flyback converter, and its circuit structure It mainly has an input circuit 1', a transformer T1', an output circuit 2', and an optocoupler 3', and the input circuit 1' is connected to the input power supply Vin, and mainly has a switching transistor Q1', a controller 11', and the transistor Q1' is connected to the primary side winding of the transformer T1', and the controller 11' can be used for PWM control, and the output terminal is connected to the transistor Q1', and the input terminal FB is connected to one end of the optocoupler 3'; and the output circuit 2' is connected to the transformer T1' The secondary side winding, and its output terminal voltage Vout is connected in parallel with the other end of the optocoupler 3', so that the optocoupler 3' isolates the input circuit 1' from the output circuit 2', and feeds back the output power supply Vout to the input circuit 1' of the controller 11', so that the controller 11' can control the operation of the switching transistor Q1' to stabilize the output voltage corresponding to the output.

The output voltage stability of the aforementioned circuit must be controlled by the feedback of the optocoupler 3', but the characteristics of the optocoupler 3' will directly affect the stability and reliability of the system, for example, the coupling efficiency of the optocoupler 3' will directly It affects the accuracy of the output voltage Vout, and if the optocoupler 3' is used as a charger (not shown in the figure), the constant current function must add additional components to compensate for the instability of the optocoupler, which will increase the circuit cost and be relatively expensive. Multiple components cause a large loss in standby loss.

Figure 10 shows the circuit structure of a conventional two-flyback converter, which mainly has an input circuit 5', a transformer T2', and an output circuit 6', and its input circuit 5' is connected to the input power supply Vin, and has a switching transistor Q2' , controller 51', and the transistor Q2' is connected to the first winding N1' on the primary side of the transformer T2', and the output end of the controller 51' is connected to the transistor Q2', and the input end is connected to the second winding N2 on the primary side of the transformer T2' ', and the controller 51' is a PWM controller; and the output circuit 6' is connected to the secondary side third winding N3' of the transformer T2', and has an output terminal voltage Vout, so that the controller 51' senses the voltage generated by the transformer T2' The secondary side feeds back the voltage change of the primary side winding of the transformer T2 ′, and controls the transistor Q2 ′ to switch on and off correspondingly to control the output terminal voltage Vout.

Although the aforementioned circuit has the simplest components, as shown in Figure 11, the voltage VN2' fed back from the transformer to the primary side winding changes by ΔV due to the leakage inductance of the transformer, and the input terminal FB of the controller 51' directly depends on the transformer The feedback variable voltage of T2', its voltage reference point may be one of a', b', c', d', e' shown in the figure, resulting in poor stability and reliability of the circuit system, no-load output Poor voltage stability and poor dynamic voltage regulation performance.

Contents of the invention

The purpose of the present invention is to provide a winding voltage sampling control power converter, so that the output circuit has a stable output voltage, that is, the circuit system is more stable and reliable.

In order to achieve the above object, the present invention adopts the following scheme: a winding voltage sampling control power converter, including: an input circuit, an input terminal, at least a switch assembly, a controller for controlling the action of the switch assembly, a winding voltage Sampling device; a transformer, with a primary winding connected to the aforementioned switch assembly and winding voltage sampling device, and having a secondary winding; an output circuit, connected to the secondary winding of the transformer, and having an output terminal; the aforementioned winding voltage sampling device detects The reference point voltage of the primary side winding voltage of the transformer, and this reference point voltage is the high point edge voltage when the transformer primary side winding voltage continues to fall from a high point to a low point, and this voltage is a negative edge voltage, and generates feedback The potential is used as a basis for the controller to feed back the input voltage, and enables the aforementioned controller to control the working cycle of the switch element accordingly.

The above-mentioned winding voltage sampling device has a negative edge detection circuit, a voltage follower circuit, a current source control circuit, and a holding capacitor, and has a winding input terminal, a sampling output terminal, and a ground terminal, and the negative edge detection circuit is a device with RC time The voltage slope change detector with constant setting, the voltage follower circuit is a voltage follower circuit with unidirectional output, and the current source control circuit is a controllable current source with switching capability to the ground terminal.

The input side of the above-mentioned negative edge detection circuit is electrically connected to the winding input end, and the winding input end is connected to the primary side winding of the transformer, and the output side of the negative edge detection circuit is connected to the current source control circuit, and the voltage is electrically connected to the input side of the coupling circuit. Connect the primary side winding of the transformer, and connect the output side of the voltage follower circuit to the current source control circuit, the holding capacitor, and the sampling output terminal, and can follow the voltage of the transformer primary side winding; and the current source control circuit is connected to the output side of the voltage follower circuit and the negative The output side of the edge detection circuit; and the holding capacitor is connected to the sampling output end.

The input side of the negative edge detection circuit is connected to a rectifier diode, and the positive end of the rectifier diode is connected to the winding input end; the voltage follower circuit is connected to a voltage dividing resistor, and one end of the voltage dividing resistor is connected to the negative end of the rectifying diode, and the other end is grounded; The voltage follower circuit has a transistor, the transistor C pole of the voltage follower circuit is connected to the negative terminal of the rectifier diode, the transistor B pole of the voltage follower circuit is connected to the voltage dividing contact of the voltage dividing resistor, and the transistor E pole of the voltage follower circuit is connected to the current source control Circuit and sampling output terminal; and the current source control circuit has a transistor, the transistor C pole of the current source control circuit is connected to the transistor E pole of the voltage follower circuit, and the sampling output terminal, and the transistor B pole of the current source control circuit is connected to the negative edge detection On the output side of the circuit, the transistor E pole of the current source control circuit is grounded; and the positive pole of the capacitor is connected to the sampling output terminal.

The above-mentioned winding voltage sampling device can be formed into an integrated circuit with three pins, and has a winding input end, a sampling output end, and a grounding end pin.

The above-mentioned negative edge detection circuit has an integrated diode, a capacitor, and a resistor, and one end of the integrated diode is connected to the rectifier diode, and the other end is connected to the aforementioned resistor, and the aforementioned resistor is connected to the B pole of the transistor of the current source control circuit, and The two terminals of the capacitor are respectively connected to the input terminal of the winding and the connection point between the aforementioned resistor and the integration diode.

The above-mentioned negative edge detection circuit has a current mirror circuit, and the input side of the current mirror circuit is connected to the negative terminal of the rectifier diode, and the output side is connected to the RC circuit and the input side of the current source control circuit.

The above-mentioned negative edge detection circuit has the third and fourth transistors, the sixth and seventh resistors, and the second capacitor, and the E poles of the third and fourth transistors are connected to the negative terminal of the rectifier diode, and the B poles of the third and fourth transistors are connected in series , and connected to the C pole of the third transistor, and the C pole of the third transistor is respectively connected in series with the sixth resistor, and the C pole of the fourth transistor is connected in series with the seventh resistor to form a current mirror circuit, and the sixth resistor is connected in parallel with the second capacitor, and The seventh resistor is connected to the transistor B pole of the current source control circuit.

The discharge time of the second capacitor is longer than the time for the winding voltage to drop from a negative edge to a low potential, and the low potential is a potential at which the winding voltage is less than the voltage of the second capacitor.

The above-mentioned negative edge detection circuit has a comparator, and the input side of the comparator inputs the winding voltage, and the output side of the comparator is connected to the input side of the current source control circuit.

The above-mentioned negative edge detection circuit has a comparator, a rectifier diode, tenth, eleventh, twelve resistors, a third capacitor, and another rectifier diode, and the positive end of the other rectifier diode is connected to the winding input end, and the negative end of the other rectifying diode is connected to one end of the tenth resistor and one end of the third capacitor, and the other end of the third capacitor is grounded, the positive input end of the comparator is connected in series with the negative end of the rectifying diode, and the negative end of the comparator is connected to the first The other end of the tenth resistor, one end of the eleventh resistor, and the eleventh resistor is grounded, so that the tenth and eleventh resistors form a third capacitor discharge path, and the output end of the comparator is connected to the twelfth resistor and the current source control circuit Input side connection.

The discharge time of the third capacitor is longer than the time for the winding voltage to drop from the negative edge to a low potential, and the low potential is a potential at which the winding voltage is less than the voltage of the third capacitor.

The controller of the above-mentioned input circuit may be a PWM controller or a PFC controller.

Adopting the above scheme, the present invention mainly provides a winding voltage sampling device on the primary side of the transformer in the input circuit, and the winding voltage sampling device can detect the set reference point voltage of the primary side winding of the transformer, and output the input voltage that can affect the controller. Voltage value, so that the controller can control the on and off actions of the switch components on the primary side of the transformer so that the output circuit has a stable output voltage, and the present invention does not require optical coupling components, which has high reliability and low corresponding functional requirements. Application cost The lowest, and can make the circuit system more stable and reliable.

Description of drawings

FIG. 1 is a schematic diagram of the circuit structure of a power converter according to the first embodiment of the present invention;

2 is a schematic diagram of the circuit structure of the winding voltage sampling device according to the first embodiment of the present invention;

Fig. 3 is a schematic circuit diagram of the first winding voltage sampling device according to the first embodiment of the present invention

picture;

Fig. 4 is a schematic diagram of the action waveform of the winding voltage sampling device according to the first embodiment of the present invention;

Fig. 5 is a schematic circuit diagram of the second winding voltage sampling device according to the first embodiment of the present invention

picture;

Fig. 6 is the winding of the second winding voltage sampling device of the first embodiment of the present invention

Schematic diagram of the comparison between voltage V1 and RC discharge time;

7 is a schematic circuit diagram of a third winding voltage sampling device according to the first embodiment of the present invention;

FIG. 8 is a schematic diagram of the circuit structure of the power converter according to the second embodiment of the present invention;

FIG. 9 is a schematic diagram of a conventional flyback converter circuit structure;

FIG. 10 is a schematic diagram of a circuit structure of a conventional two-flyback converter;

Fig. 11 is the conventional two flyback converter circuit feedback primary side winding voltage waveform and its output

Schematic diagram of the sample voltage reference point.

Explanation of main component symbols

1 input circuit Vin input terminal 11 switch components

12 Controller 13 Winding voltage sampling device T transformer

N1, N2 primary side winding N3 secondary side winding 2 output circuits

Vout output terminal 131 Negative edge detection circuit 132 Voltage follower

133 Current source control circuit C holding capacitor 134 Winding input terminal

135 sampling output terminal 136 grounding terminal

13a winding voltage sampling device

R1, R2, R3 resistors D1 rectifier diode D2 integrated diode

Q1, Q2 transistor C1 capacitor D3 rectifier diode

I1, I2 current F1, F2 negative edge FB input terminal

V1, V2, V3, V4, VS voltage 13b Winding voltage sampling setting

R4, R5, R6, R7 resistors Q3, Q4, Q5 transistors

C2 Capacitor C3 Capacitor

R8, R9, R10, R11, R12 resistors D4, D5 rectifier diodes

131a comparator Q7, Q8 transistor 121 controller

1'input circuit 11'controller T1'transformer

Q1'transistor 2'output circuit 3'optocoupler

5'input circuit 51'controller Q2'transistor

T2' transformer 6' output circuit

N1'first winding N2'second winding N3'third winding

Detailed ways

The present invention mainly includes an input circuit, a transformer, and an output circuit, and the input circuit has at least one switch assembly, a controller for controlling the action of the switch assembly, a winding voltage sampling device, and the winding voltage sampling device detects the transformer once The negative edge voltage of the side winding drops rapidly, and outputs the input voltage value that can affect the controller; the transformer has a primary side winding connected to the aforementioned switch component and winding voltage sampling device, and has a secondary side winding; and the output circuit is connected to the secondary side of the transformer The side winding has an output terminal; the above-mentioned winding voltage sampling device can detect the set reference point voltage of the primary side winding voltage of the transformer, and enable the controller to perform corresponding control.

The winding voltage sampling device of the present invention has a negative edge detection circuit, a voltage follower circuit, a current source control circuit, and a holding capacitor, and has a winding input terminal, a sampling output terminal, and a ground terminal, and the sampling output terminal is connected to the controller input terminal. , and the input side of the negative edge detection circuit is electrically connected to the winding input end, and the input end is connected to the primary side winding of the transformer, and the output side is connected to the current source control circuit, and the input side of the voltage follower circuit is electrically connected to the primary side of the transformer side winding, and the output side is connected to the current source control circuit, the holding capacitor, and the sampling output end; and the current source control circuit is connected to the output side of the voltage follower circuit and the negative edge detection circuit and the sampling output end; and the holding capacitor is connected to the sampling output end ; By this, the winding voltage sampling device can detect the negative edge position voltage and then input it to the controller, so that the controller can respond to the control switch assembly to open and close the action so that the output circuit has a stable output voltage, and the present invention does not require an optical coupling assembly, High reliability, few corresponding functional requirements, lowest application cost and high efficiency.

The present invention will be described in detail below by specific embodiments and with reference to the accompanying drawings:

Please refer to Fig. 1, the first embodiment of the present invention includes an input circuit 1, a transformer T, an output circuit 2, and the input circuit 1 has an input terminal Vin, a switch assembly 11, and the switch assembly 11 is a transistor , and can also be a MOSFET or other individual components or combined components that switch, and have a controller 12 that controls the action of the switch component 11, and the controller 12 can be a PWM controller, and its output is connected to the switch component 11, and has A winding voltage sampling device 13 , and the winding voltage sampling device 13 is connected to the primary side winding N2 of the transformer T and output to the input terminal FB of the controller 12 .

The transformer T has primary side windings N1 and N2 respectively connected to the switch assembly 11 and the winding voltage sampling device 13 , and has a secondary side winding N3.

The output circuit 3 is connected to the secondary side winding N3 of the transformer T and has an output terminal Vout.

2, the winding voltage sampling device 13 of the present invention has a negative edge detection circuit 131, a voltage follower circuit 132, a current source control circuit 133, a holding capacitor C, and a winding input terminal 134 and a sampling output terminal 135. , ground terminal 136, and the negative edge detection circuit 131 is a voltage slope change detector with RC time constant; the voltage follower circuit is a unidirectional output voltage follower circuit; and the current source control circuit is A controllable current source opposite to the ground terminal with switching capability, and the input side of the negative edge detection circuit 131 is electrically connected to the winding input terminal 134, and a rectifier diode is provided, and the winding input terminal 134 is connected to the primary side winding N2 of the transformer T, And the output side is connected to the current source control circuit 133, and the gain AV of the voltage follower circuit 132=1, the input side is electrically connected to the primary side winding N2 of the transformer T, and the output side is connected to the current source control circuit 133, holding capacitor C, output terminal 135, and the voltage follower circuit 132 is connected to the voltage divider resistor to import the divided voltage; the current source control circuit 133 is connected to the output side of the voltage follower circuit 132 and the negative edge detection circuit 131 and the sampling output terminal 135; and the capacitor is held C is connected to the sampling output terminal 135 .

The negative edge detection circuit of the winding voltage sampling device of the present invention can have a variety of circuit structures with similar functions, and Fig. 3 shows the circuit structure of the first winding voltage sampling device 13a of the present invention, the rectifier diode D1 is connected to the winding input end 134, the second 1. The second piezoelectric group R1, R2 is connected to the voltage follower circuit 132, and the first resistor R1 is connected to the rectifier diode D1; and the negative edge detection circuit 131 has an integrated diode D2, a first capacitor C1, a The third resistor R3, one end of the integrated diode D2 is connected to the rectifier diode D1, the other end is connected to the third resistor R3, and the third resistor R3 is connected to the current source control circuit 133, and the two ends of the first capacitor C1 are respectively connected to the winding input end 134 and the third resistor R3; and the voltage follower circuit 132 has a first transistor Q1, and its C pole is connected to the rectifier diode D1, its B pole is connected to the voltage dividing contacts of the piezoelectric groups R1 and R2, and its E pole is connected to the current source control circuit 133 and the sampling output terminal 135; and the current source control circuit 133 has a second transistor Q2, and its C pole is connected to the first transistor Q1E pole and the sampling output terminal 135, and the B pole is connected to the third resistor R3 of the negative edge detection circuit 131, The pole E is grounded; and the positive pole of the holding capacitor C is connected to the sampling output terminal 135 .

Please refer to FIG. 1 to FIG. 4 together. The input terminal 134 of the first winding voltage sampling device 13a of the present invention inputs the winding voltage V1 fed back to the primary side of the transformer, and at time TA (switching component 11OFF) the winding voltage V1 Divided by resistors R1 and R2, the divided voltage is V3, which turns on transistor Q1 and charges the holding capacitor C, and the voltage V3 follows the voltage of V1, and the voltage V1 is supplied by the rectifier diode D1 and the integration diode D2 and resistor R3 turn on the transistor Q2, and its current is I1, and the winding voltage V1 can charge the capacitor C1, and the current I2 flowing through the transistor Q1 is much larger than the current I1, and integrates the voltage of the diode D2 and the resistor R3 The impedance value is set corresponding to the output voltage Vout of the output circuit 2 .

As shown in Figure 4, when the winding voltage V1 of the TB time feedback drops rapidly, its negative edge is F1, and when the negative edge F1 is generated, the voltage drops so that the current of the winding cannot flow through the integration diode D2 and capacitor C1, so that the transistor Q2 does not When the current I1 is turned on and the current I1 is zero, and the current of the holding capacitor C cannot be discharged by the transistor Q2, and the winding voltage V1 continues to drop, although the transistors Q1 and Q2 are cut off, the output terminal 135 still has the straight line DC state voltage of the holding capacitor C , its voltage VS as shown in Figure 4, so that the reference voltage input to the controller 12 can be the voltage corresponding to the negative edge F1, and the controller 12 can control the switch assembly 11 according to the reference voltage to control and adjust the appropriate output circuit 2 The output voltage Vout.

The above-mentioned negative edge F1 is used as the reference point voltage to be the minimum current state of the converter circuit system when the converter is in transition, and when the parasitic resistance on the circuit produces the minimum voltage drop, so it can have an accurate reference value, and the present invention can eliminate the diagram The leakage inductance of the transformer T shown in 4 affects the fluctuation voltage ΔV of the feedback winding voltage V1, so that the controller 12 can perform responsive control based on the precise reference value.

In the next sequence TC time of the present invention, it is assumed that the feedback winding voltage V1 decreases, and the voltage V3 decreases, and because the voltage VS stored in the capacitor C in the previous sequence is greater than the voltage V3, the transistor Q1 is not turned on, and the winding voltage V1 is still The transistor Q2 can be turned on by the capacitor C1 and the resistor R3, so that the voltage V4 of the holding capacitor C can be discharged by the transistor Q2, until the voltage V4 is less than the voltage V3 minus the VBE voltage of the transistor Q1, the transistor Q1 can be turned on, and the current I2 can be used again. Keep the capacitor C charged, so that the output voltage V4 can be determined by the transistor Q1, and can follow the voltage V3 and the winding voltage V1, and when the negative edge F2 is generated, the transistor Q2 can be turned off again, and the voltage V4 can be corresponding to the negative edge voltage at this time. The controller 12 is input so that the controller 12 can accurately control the on and off time of the switch element 11 according to the negative edge voltage of each time sequence as a reference voltage to precisely control the output voltage of the output circuit 2 .

Please refer to Fig. 5, the circuit of the second winding voltage sampling device 13b of the present invention, and the difference between this circuit and the aforementioned first winding voltage sampling device circuit is the negative edge detection circuit, and the winding voltage sampling device 13b is connected with a rectifier diode D3 The winding input terminal 134 has the fourth and fifth divider resistors R4 and R5 connected to the voltage follower circuit 132, and the negative edge detection circuit 132 has the third and fourth transistors Q3 and Q4, the sixth and seventh resistors R6 and R7, The second capacitor C2, and the E poles of the third and fourth transistors Q3 and Q4 are connected to the rectifier diode D3, and the B poles are connected to each other, and the C poles are respectively connected in series with the sixth and seventh resistors R6 and R7 to form a current mirror circuit , and the sixth resistor R6 is connected in parallel with the second capacitor C2, and the seventh resistor R7 is connected to the current source control circuit 133; and the voltage follower circuit 132 has a fifth transistor Q5, and its C pole is connected to the rectifier diode D3, and its B pole is connected to Divider resistors R4, R5, E poles are connected to the current source control circuit 133 and the sampling output terminal 135; and the current source control circuit 133 has a sixth transistor Q6, and its C pole is connected to the fifth transistor Q5E pole, output terminal 135, and B pole The seventh resistor R7 is connected, and the E pole is grounded; and the positive pole of the holding capacitor C is connected to the sampling output terminal 135 .

Please refer to FIG. 4 and FIG. 5 together. When the winding voltage sampling device 13b of the present invention operates, the winding voltage V1 at time TA turns on the transistor Q5 of the voltage follower circuit 132, and the voltage of V3 follows the voltage V1, and holds capacitor C Charged to the voltage V4, and the winding voltage V1 turns on the transistors Q3, Q4 to generate the same currents I2, I1, and turns on the transistor Q6 of the current source control circuit 133, and the I2 current can charge the capacitor C2.

When the negative edge F1 is generated and the TB time is due to the rapid drop of the winding voltage V1 to less than the voltage on the capacitor C2, the transistor Q3 is turned off, and the transistors Q4 and Q6 are turned off, so that the voltage V4 can have the voltage V4 of the capacitor C, and thus When the capacitor C2 can be discharged by the resistor R6, and as shown in Figure 6, the discharge RC time of the capacitor C2 is longer than the time when the winding voltage V1 drops from the negative edge F1 to the low potential time, so the transistor Q6 remains non-conductive during the TB time, and the sampling The output terminal 135 can keep outputting the DC state VS voltage to the controller 12, so that the controller 12 can control in response to the precise negative edge reference voltage.

And at the time TC, the winding voltage V1 can turn on the transistor Q6 again, and make the holding capacitor C store the reference voltage of the negative edge F2 of another time sequence.

Please refer to Fig. 7, the third winding voltage sampling device 13C of the present invention has another negative edge detection circuit, and its circuit has a rectifier diode D4 connected to the winding input terminal 134, and the eighth and ninth voltage divider resistors R8 and R9 are connected The voltage follower circuit 132, and the negative edge detection circuit 131 have a comparator 131a, a rectifier diode D5, tenth, eleventh, and twelve resistors R10, R11, R12, a third capacitor C3, and the positive side of the comparator 131a , the negative output terminals are respectively connected in series with rectifier diodes D4 and D5, and the rectifier diode D5 is connected to the winding input terminal 134, and the third capacitor C3 is connected in series with the rectifier diode D5 to ground, and the rectifier diode D5 is connected in series with the negative terminal of the comparator 131a connected to the tenth resistor R10, and one end of the tenth resistor R10 is connected to the third capacitor C3, and is connected to the eleventh resistor R11 to ground, so that the tenth and eleventh resistors form a discharge path for the third capacitor C3, and the comparator 131a The output end is connected to the twelfth resistor R12 and the current source control circuit 133; and the voltage follower circuit 132 has a seventh transistor Q7, and its C pole is connected to the rectifier diode D4, and its B pole is connected to the eighth and ninth piezoelectric groups R8, R9, the E pole is connected to the current source control circuit 133 and the sampling output terminal 135; and the current source control circuit 133 has an eighth transistor Q8, and its C pole is connected to the seventh transistor Q7E pole and the output terminal 135, and the B pole is connected to the twelfth resistor R12, the E pole is grounded; and the positive pole of the holding capacitor C is connected to the sampling output terminal 135 .

Please refer to FIG. 4 and FIG. 7 together. When the third winding voltage sampling device 13C of the present invention operates, the winding voltage V1 can turn on the transistor Q7 at time TA, and charge the holding capacitor C, and the winding voltage V1 is controlled by the diode D5 The capacitor C3 is charged, and the voltage input to the negative terminal of the comparator 131a is a voltage divided by the resistors R10 and R11, so that the voltage at the negative terminal of the comparator 131a is smaller than the voltage at the positive terminal, and the comparator 131a can output a positive voltage so that the transistor Q8 conducts When the negative edge F1 of the TB time is generated, the voltage of the negative edge F1 drops rapidly and is lower than the voltage of the capacitor C3, so that the transistor Q8 is cut off, and the voltage of the negative edge F1 can be detected, and the capacitor C3 can be discharged by the resistors R10 and R11 at this time. And similar to the aforementioned second winding voltage sampling device 13b, the discharge time of the capacitor C3 is longer than the time for the winding voltage V1 to drop from the negative edge F1 to a low potential, so that the voltage at the sampling output terminal 135 can maintain a DC state reference voltage so that the controller 12 can respond control.

The winding voltage sampling device 13 of the present invention can be an integrated circuit with three pins, and has a winding input terminal, a sampling output terminal, and a ground terminal pin, so that the present invention can be easily mass-produced, and can be easily installed in a general converter On the other hand, it can have better economic benefits.

Please refer to FIG. 8. In addition to being used as the input reference voltage of the PWM controller in the first embodiment, the present invention can also be used in the single-stage isolated PFC converter in the second embodiment, and the PFC controller 121 can input the negative edge reference voltage, and Can have the claimed effect of the present invention.

The foregoing embodiments are examples of the present invention, and are not intended to limit the scope of the patent application of the present invention. The design of the negative edge detection circuit of the present invention can detect a set reference point close to the position of the negative edge, which is more accurate than conventional circuits. Sexual function, thus design similar to the aforementioned spirit of the present invention should also belong to the scope of the present invention, and the present invention can be changed and amended within the spirit of the present invention.

Claims (13)

1. A winding voltage sampling control power converter, characterized in that: comprising, An input circuit with an input terminal, at least one switch component, a controller for controlling the action of the switch component, and a winding voltage sampling device; A transformer with a primary side winding connected to the aforementioned switching components and a winding voltage sampling device, and with a secondary side winding; An output circuit, connected to the secondary side winding of the transformer, and having an output terminal; Moreover, the above-mentioned winding voltage sampling device detects the reference point voltage of the primary side winding voltage of the transformer, and this reference point voltage is the high point edge voltage of the transformer primary side winding voltage continuously falling from a high point to a low point, and the voltage is Negative edge voltage, and generate a feedback potential for the controller to feed back the input voltage basis, and enable the aforementioned controller to control the working cycle of the switching element in response. 2. The winding voltage sampling control power converter according to claim 1, wherein the winding voltage sampling device has a negative edge detection circuit, a voltage follower circuit, a current source control circuit, a holding capacitor, and a winding input terminal , sampling output terminal, ground terminal, and the negative edge detection circuit is a voltage slope change detector with RC time constant setting, and the voltage follower circuit is a unidirectional output voltage follower circuit, and the current The source control circuit is a controllable current source with switching capability to ground. 3. The winding voltage sampling control power converter according to claim 2, characterized in that: the input side of the negative edge detection circuit is electrically connected to the winding input end, and the winding input end is connected to the primary side winding of the transformer, and the negative edge detection circuit The output side of the circuit is connected to the current source control circuit, and the input side of the voltage follower circuit is electrically connected to the primary side winding of the transformer, and the output side of the voltage follower circuit is connected to the current source control circuit, holding capacitor, and sampling output terminal, and can follow The winding voltage of the primary side of the transformer; the fork current source control circuit is connected to the output side of the voltage follower circuit and the output side of the negative edge detection circuit; and the holding capacitor is connected to the sampling output end. 4. The winding voltage sampling control power converter according to claim 3, characterized in that: the input side of the negative edge detection circuit is connected to a rectifier diode, and the positive end of the rectifier diode is connected to the winding input end; Piezoresistor, and one end of the voltage dividing resistor is connected to the negative end of the rectifier diode, and the other end is grounded; the voltage follower circuit has a transistor, and the voltage follower circuit’s C pole of the transistor is connected to the rectifier diode’s negative end, and the voltage follower circuit’s transistor B pole is connected The voltage-dividing contact of the voltage-dividing resistor, the transistor E pole of the voltage follower circuit is connected to the current source control circuit and the sampling output terminal; and the current source control circuit has a transistor, and the transistor C pole of the current source control circuit is connected to the transistor of the voltage follower circuit E pole, sampling output terminal, the transistor B pole of the current source control circuit is connected to the output side of the negative edge detection circuit, the transistor E pole of the current source control circuit is grounded; and the positive pole of the holding capacitor is connected to the sampling output terminal. 5. The winding voltage sampling control power converter according to claim 2, characterized in that: the winding voltage sampling device can be formed as a three-pin integrated circuit, and has a winding input terminal, a sampling output terminal, and a ground terminal foot. 6. The winding voltage sampling control power converter according to claim 4, characterized in that: the negative edge detection circuit has an integrated diode, a capacitor, and a resistor, one end of the integrated diode is connected to the rectifier diode, and the other end is connected to The aforementioned resistor is connected to the transistor B pole of the current source control circuit, and the two terminals of the capacitor are respectively connected to the winding input end and the junction point between the aforementioned resistor and the product diode. 7. The winding voltage sampling control power converter according to claim 4, characterized in that: the negative edge detection circuit has a current mirror circuit, and the input side of the current mirror circuit is connected to the negative terminal of the rectifier diode, and the output side is connected to the RC circuit , The input side of the current source control circuit. 8. The winding voltage sampling control power converter according to claim 7, characterized in that: the negative edge detection circuit has third and fourth transistors, sixth and seventh resistors, and a second capacitor, and the third and fourth transistors The E pole of the rectifier diode is connected to the negative terminal of the rectifier diode, and the B poles of the third and fourth transistors are connected in series, and are connected to the C pole of the third transistor, and the C poles of the third transistor are respectively connected in series with the sixth resistor, and the C poles of the fourth transistor are connected in series. The seventh resistor forms a current mirror circuit, and the sixth resistor is connected to the second capacitor in parallel, and the seventh resistor is connected to the transistor B pole of the current source control circuit. 9. The winding voltage sampling control power converter according to claim 8, characterized in that: the discharge time of the second capacitor is longer than the time for the winding voltage to drop from the negative edge to a low potential, and the low potential means that the winding voltage is less than the voltage of the second capacitor The potential. 10. The winding voltage sampling control power converter according to claim 4, characterized in that: the negative edge detection circuit has a comparator, and the input side of the comparator inputs the winding voltage, and the output side of the comparator is connected to a current source to control input side of the circuit. 11. The winding voltage sampling control power converter according to claim 10, characterized in that: the negative edge detection circuit has a comparator, tenth, eleventh, twelve resistors, a third capacitor, and another A rectifying diode, and the positive end of the other rectifying diode is connected to the winding input end, and the negative end of the other rectifying diode is connected to one end of the tenth resistor and one end of the third capacitor, and the other end of the third capacitor is grounded, and the positive end of the comparator The input end is connected in series with the negative end of the rectifier diode, and the negative end of the comparator is connected to the other end of the tenth resistor and one end of the eleventh resistor, and the eleventh resistor is grounded, so that the tenth and eleventh resistors form a third capacitor discharge path, In addition, the output end of the comparator is connected to the twelfth resistor and the input side of the current source control circuit. 12. The winding voltage sampling control power converter according to claim 11, characterized in that: the discharge time of the third capacitor is longer than the time for the winding voltage to drop from the negative edge to a low potential, and the low potential is that the winding voltage is less than the voltage of the third capacitor The potential. 13. The winding voltage sampling control power converter according to claim 1, wherein the controller of the input circuit can be a PWM controller or a PFC controller.

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