Primary side double-tube voltage conversion circuit

Abstract

The invention discloses a primary side double-tube voltage conversion circuit which comprises a first primary side primary coil T1B, a second primary side primary coil and a second primary side primary coil, the first primary side primary coil and the second primary side primary coil are both electrically connected to a first control chip, a third primary side primary coil is electrically connected to a second control chip, and the third primary side primary coil is electrically connected to a third control chip. The VDD pin of the second control chip is electrically connected with the VDD pin of the first control chip, and the GATE pin of the first control chip is electrically connected with the LIN pin and the HIN pin of the first control chip. The invention has the following advantages: the primary side current sampling double closed loop based on the double-transistor flyback converter forms a current loop through the control method of the first control chip and the second control chip; the defects of digital control in the aspect of current sampling precision are overcome, the control precision is improved, and high sensitivity and flexibility are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and in particular to a primary-side dual-tube voltage conversion circuit. Background Art

[0002] The dual-tube flyback converter is a common direct current to direct current (DC / DC) converter with the advantages of high conversion efficiency, simple structure, and low voltage withstand requirements for the power switch tube. Therefore, it has been widely used in high-voltage input scenarios. At present, high-current and high-voltage output DC converters are applied to various fields such as communication power supply, alkali metallurgical industry, and aerospace power supply systems. In order to improve the efficiency and reliability of the converter, there are many studies on the topology and control methods of high-current output DC converters.

[0003] The current single-tube flyback converter replaces the inductor in the traditional buck-boost converter by cleverly applying the transformer, so its basic working principle is consistent with the buck-boost converter. When the switch tube is turned on, the flyback converter isolates the transformer's excitation inductance to store energy, and when the switch is turned off, the excitation inductance releases energy. Therefore, the single-tube flyback converter has both the functions of energy transfer and electrical isolation. However, the resonance of the transformer leakage inductance and the switch tube junction capacitance will lead to increased voltage and current stress of the switch tube of the single-tube flyback converter, increased switch tube turn-off loss, and severe electromagnetic interference. In order to improve the performance of the single-tube flyback converter, the clamping technology and soft switching technology of the flyback converter have been proposed successively. The double-tube flyback converter improves the problem of high voltage stress of the switch tube. By modifying the primary side structure of the traditional flyback converter, two diodes are used to clamp the transformer reset voltage at the input voltage during reset, thereby reducing the voltage stress of the switch tube. At the same time, the leakage inductance energy can be directly fed back to the input power supply without the need for additional circuit absorption.

[0004] In order to make the converter have good dynamic performance and stable output performance, it is necessary to establish a dual-tube flyback converter model through analysis and select a reasonable control method. In voltage mode control, when there are disturbances such as load current or input voltage, it is necessary to wait for the load voltage to change and cause the error amplification signal to change before implementing the corresponding control process, which may cause one or more switching cycles to be delayed, which is not conducive to the dynamic response of the system. Therefore, a primary dual-tube voltage conversion circuit is provided to solve the above problems. Summary of the invention

[0005] In order to solve the problems in the above background technology, the technical solution adopted by the present invention to solve the technical problems is: a primary dual-tube voltage conversion circuit, which includes: a first primary primary coil T1B, a second primary primary coil and a second primary primary coil, the first primary coil and the second primary coil are both electrically connected to the first control chip, the third primary coil is electrically connected to the second control chip, the second control chip VDD pin is electrically connected to the first control chip VDD pin, and the first control chip GATE pin is electrically connected to the first control chip LIN pin and HIN pin.

[0006] As a preferred technical solution of the present invention, one end of the third primary coil is electrically connected to a first diode, the first diode is electrically connected to a first resistor, the first resistor is electrically connected to a first switch tube, and the connection between the first resistor and the first switch tube Q3 is electrically connected to a first capacitor and a second resistor, respectively.

[0007] As a preferred technical solution of the present invention, the second resistor is electrically connected to the first voltage regulator diode, one end of the first switch tube is electrically connected to the second capacitor and the VDD pin of the second control chip, and the second diode is connected in series between the first switch tube and the VDD pin of the second control chip.

[0008] As a preferred technical solution of the present invention, the VDD pin of the second control chip is connected to the second diode circuit in parallel with a third capacitor, and the VDD pin of the second control chip is connected to the third capacitor connection circuit in parallel with a fourth capacitor.

[0009] As a preferred technical solution of the present invention, the other end of the third primary coil is electrically connected to the VDD pin of the second control chip through a fourth capacitor, and the connection line between the third primary coil and the fourth capacitor is connected in parallel with the first capacitor, the first voltage regulator diode, the second capacitor, and the third capacitor.

[0010] As a preferred technical solution of the present invention, the GND pin of the second control chip is grounded, the FB pin of the second control chip is electrically connected to the third resistor, and the circuit connecting the third resistor and the FB pin of the second control chip is connected in parallel with a fourth resistor, a fifth resistor, and a fifth capacitor.

[0011] As a preferred technical solution of the present invention, the DEM pin connection circuit of the second control chip is connected in parallel with a sixth resistor and a seventh resistor, and one end of the sixth resistor is grounded.

[0012] As a preferred technical solution of the present invention, one end of the first primary coil is electrically connected to one end of the VS pin of the first control chip through a line, the other end of the first primary coil is connected to the second switch tube through a line, and the second switch tube is connected in parallel with the third diode and the seventh resistor through a circuit.

[0013] As a preferred technical solution of the present invention, the third diode is connected to the eighth resistor through a line, and the seventh resistor and the eighth resistor are connected in parallel to the LO pin of the first control chip through a line.

[0014] As a preferred technical solution of the present invention, one end of the second primary coil is electrically connected to the HB pin of the first control chip through a line, a fourth diode and a ninth resistor are connected in series between one end of the second primary coil and the HB pin of the first control chip, and the other end of the second primary coil is connected to the VS pin of the first control chip through a line.

[0015] The present invention has the following advantages: the present invention is based on the primary current sampling double closed loop of the dual-tube flyback converter through the first control chip and the second control chip control method to form a current loop, which makes up for the defects of digital control in current sampling accuracy, improves the control accuracy, has high sensitivity, flexibility, and programmability, is conducive to the parameter design of the control loop, realizes the reduction of the switch-off loss of the circuit in a wide voltage range, improves the reliability of the converter, and has a fast dynamic response. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the primary circuit and the secondary circuit of the dual-tube voltage conversion circuit of the preferred embodiment 1 of the present invention;

[0017] Figure 2 1 is a schematic diagram of the primary circuit of the dual-tube voltage conversion circuit according to the first preferred embodiment of the present invention;

[0018] Figure 3 It is a schematic diagram of the primary circuit and the secondary circuit of the dual-tube voltage conversion circuit of the preferred embodiment 2 of the present invention;

[0019] Figure 4 It is a schematic diagram of the primary circuit of a dual-tube voltage conversion circuit according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Many specific details are explained in the following description to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0021] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Embodiment 1

[0023] Please refer to Figure 1 and Figure 2 The present invention provides a primary dual-tube voltage conversion circuit, comprising: a first primary primary coil T1B, a second primary primary coil T1D and a third primary primary coil T1C, the first primary primary coil T1B and the second primary primary coil T1D are both electrically connected to a first control chip, the third primary primary coil T1C is electrically connected to the second control chip, the VDD pin of the second control chip is electrically connected to the VDD pin of the first control chip, and the GATE pin of the first control chip is electrically connected to the LIN pin and the HIN pin of the first control chip.

[0024] One end of the third primary coil T1C is electrically connected to the first diode D13D13, the first diode D13 is electrically connected to the first resistor R16, the first resistor R16 is electrically connected to the first switch tube Q3, the connection between the first resistor R16 and the first switch tube Q3 is electrically connected to the first capacitor C15 and the second resistor R26 respectively, the second resistor R26 is electrically connected to the first voltage-stabilizing diode ZD1, one end of the first switch tube Q3 is electrically connected to the second capacitor C8 and the VDD pin of the second control chip, the first switch tube Q3 and the second control chip V The line between the DD pins is connected in series with the second diode D14, the line between the VDD pin of the second control chip and the second diode D14 is connected in parallel with the third capacitor C14, the line connecting the VDD pin of the second control chip and the third capacitor C14 is connected in parallel with the fourth capacitor C13, the other end of the third primary coil T1C is electrically connected to the VDD pin of the second control chip through the fourth capacitor C13, and the line connecting the third primary coil and the fourth capacitor C13 is connected in parallel with the first capacitor C15, the first voltage stabilizing diode ZD1, the second capacitor C8, and the third capacitor C14.

[0025] The GND pin of the second control chip is grounded, the FB pin of the second control chip is electrically connected to the third resistor R28, the third resistor R28 and the FB pin of the second control chip are connected in parallel with the fourth resistor R24, the fifth resistor R27, and the fifth capacitor C20, one end of the first primary coil T1B is electrically connected to one end of the VS pin of the first control chip through the circuit, the other end of the first primary coil T1B is connected to the second switch tube Q2 through the circuit, the second switch tube Q2 is connected in parallel with the third diode D1 and the seventh resistor R10 through the circuit, the third diode D1 is connected to the eighth resistor R11 through the circuit, the seventh resistor R10 and the eighth resistor R11 are connected in parallel to the LO pin of the first control chip through the circuit, one end of the second primary coil T1D is electrically connected to the HB pin of the first control chip through the circuit, the fourth diode D12 and the ninth resistor are connected in series between one end of the second primary coil T1D and the HB pin of the first control chip, and the other end of the second primary coil T1D is connected to the VS pin of the first control chip through the circuit.

[0026] Embodiment 2

[0027] Combination Figure 3 and Figure 4 As shown, the DEM pin connection line of the second control chip is connected in parallel with the sixth resistor R1 and the seventh resistor R10, and one end of the sixth resistor R1 is grounded.

[0028] In summary, the primary current in the dual-tube flyback circuit is the excitation inductor current that rises when the main switch tube is turned on and decreases when the main switch tube is turned off. The current corresponding to the middle moment of the switch tube turning on is approximately the average current of the primary current. Therefore, the flexibility of the DSP programming of the first control chip and the second control chip is used to sample the current at the moment corresponding to the half duty cycle. Sample once per cycle and take the average value of five cycles. The primary current value is sampled by the Hall current sensor, the current signal is converted into a voltage signal, and the sampled value is stored in the result register. The current rises when the first switch tube Q3 and the second switch tube Q2 are turned on, and the current is zero when the first switch tube Q3 and the second switch tube Q2 are turned off. The current corresponding to the middle moment of the switch tube turning on is approximately the average current of the primary current. Therefore, the flexibility of the programming of the first control chip and the second control chip is used to sample the current at the moment corresponding to the half duty cycle. Sample once per cycle and take the average value of five cycles. The current average value is used as feedback and input into the current inner loop controller, and PWM is generated by the controller. The PWM is input into the isolation driver chip to drive the first switch tube Q3 and the second switch tube Q2.

[0029] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0030] Other parts of the present invention not described in detail belong to the prior art and will not be described in detail here.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A primary-side dual-tube voltage conversion circuit, comprising: The first primary coil T1B, the second primary coil and the second primary coil are characterized in that the first primary coil and the second primary coil are electrically connected to the first control chip, the third primary coil is electrically connected to the second control chip, the VDD pin of the second control chip is electrically connected to the VDD pin of the first control chip, and the GATE pin of the first control chip is electrically connected to the LIN pin and the HIN pin of the first control chip.

2. A primary-side dual-tube voltage conversion circuit as claimed in claim 1, characterized in that: One end of the third primary coil is electrically connected to a first diode, the first diode is electrically connected to a first resistor, the first resistor is electrically connected to a first switch tube, and the connection between the first resistor and the first switch tube is electrically connected to a first capacitor and a second resistor, respectively.

3. A primary-side dual-tube voltage conversion circuit as claimed in claim 2, characterized in that: The second resistor is electrically connected to the first voltage regulator diode, one end of the first switch tube is electrically connected to the second capacitor and the VDD pin of the second control chip, and a second diode is connected in series between the first switch tube and the VDD pin of the second control chip.

4. A primary-side dual-tube voltage conversion circuit as claimed in claim 1, characterized in that: The VDD pin of the second control chip and the second diode circuit are connected in parallel with a third capacitor, and the VDD pin of the second control chip and the third capacitor connection circuit are connected in parallel with a fourth capacitor.

5. A primary-side dual-tube voltage conversion circuit as claimed in claim 2, characterized in that: The other end of the third primary coil is electrically connected to the VDD pin of the second control chip through the fourth capacitor, and the connection line between the third primary coil and the fourth capacitor is connected in parallel with the first capacitor, the first voltage regulator diode, the second capacitor, and the third capacitor.

6. A primary-side dual-tube voltage conversion circuit as claimed in claim 1, characterized in that: The GND pin of the second control chip is grounded, the FB pin of the second control chip is electrically connected to a third resistor, and a fourth resistor, a fifth resistor, and a fifth capacitor are connected in parallel in a circuit connecting the third resistor and the FB pin of the second control chip.

7. A primary-side dual-tube voltage conversion circuit as claimed in claim 1, characterized in that: Or the DEM pin connection circuit of the second control chip is connected in parallel with a sixth resistor and a seventh resistor, and one end of the sixth resistor is grounded.

8. A primary-side dual-tube voltage conversion circuit as claimed in claim 1, characterized in that: One end of the first primary coil is electrically connected to one end of the VS pin of the first control chip through a line, the other end of the first primary coil is connected to the second switch tube through a line, and the second switch tube is connected in parallel with the third diode and the seventh resistor through a circuit.

9. A primary-side dual-tube voltage conversion circuit as claimed in claim 8, characterized in that: The third diode is connected to the eighth resistor through a line, and the seventh resistor and the eighth resistor are connected in parallel to the LO pin of the first control chip through a line.

10. A primary-side dual-tube voltage conversion circuit as claimed in claim 1, characterized in that: One end of the second primary coil is electrically connected to the HB pin of the first control chip through a line, a fourth diode and a ninth resistor are connected in series between one end of the second primary coil and the HB pin of the first control chip, and the other end of the second primary coil is connected to the VS pin of the first control chip through a line.

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