Switching power supply circuit with high voltage input

Abstract

The invention is suitable for the technical field of switching power supplies, and provides a high-voltage input switching power supply circuit, which comprises a PWM control circuit, a driver transformer, at least two MOS tube circuits and a main transformer, the PWM control circuit is connected with a primary winding of the driving transformer; the driving transformer comprises at least two secondary windings with the same parameters, and each secondary winding is connected with one MOS tube circuit; mOS tubes in the at least two MOS tube circuits are connected in series to a primary winding of the main transformer, and a secondary winding of the main transformer is used for being connected with a post-stage circuit. The problem that the input voltage level of a switching power supply in the prior art is low can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of switching power supplies, and in particular relates to a switching power supply circuit with a high voltage input. Background Art

[0002] A switching power supply is a power supply that uses modern power electronics technology to control the time ratio of the switch tube being turned on and off to maintain a stable output voltage.

[0003] In the related art, a switching power supply often uses a single MOS tube for pulse width modulation control (PWM) of the input power supply. Since the highest withstand voltage of the current mainstream MOS tube is 1.5kV, when the input voltage is close to this voltage, using a single MOS tube for PWM control of the switching power supply may cause safety hazards such as MOS tube breakdown and input power short circuit. Therefore, the current switching power supply has a low input voltage level and cannot be used in situations with a higher input voltage level. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a switching power supply circuit with a high voltage input to solve the problem of low input voltage level of the switching power supply in the prior art.

[0005] The embodiment of the present invention provides a switching power supply circuit with high voltage input, comprising: a PWM control circuit, a drive transformer, at least two MOS tube circuits and a main transformer;

[0006] The PWM control circuit is connected to the primary winding of the drive transformer;

[0007] The driving transformer comprises at least two secondary windings with the same parameters, and each of the secondary windings is connected to one of the MOS tube circuits;

[0008] The MOS transistors in the at least two MOS transistor circuits are connected in series to the primary winding of the main transformer, and the secondary winding of the main transformer is used to connect to the subsequent circuit.

[0009] As a possible implementation, the MOS tube circuit includes: a discharge circuit and a MOS tube;

[0010] The secondary winding of the driving transformer is connected to the discharge circuit;

[0011] The discharge circuit is connected to the MOS tube.

[0012] As a possible implementation, the discharge circuit includes: a first resistor, a second resistor, a first unidirectional diode, a first transient suppression diode and a transistor;

[0013] The first end of the secondary winding of the driving transformer is connected to the input end of the first unidirectional diode, and is connected to the base of the transistor through the first resistor; the output end of the first unidirectional diode is connected to the emitter of the transistor, the output end of the first transient suppression diode, the first end of the second resistor and the gate of the MOS tube;

[0014] The second end of the secondary winding of the driving transformer is connected to the collector of the transistor, the input end of the first transient voltage suppression diode, the second end of the second resistor and the source of the MOS tube.

[0015] As a possible implementation, the main transformer includes: a first primary winding having the same number as the MOS tubes;

[0016] Each of the MOS tubes is connected in series with each of the first primary windings of the main transformer via a drain and a source to form a series circuit;

[0017] The first end of the first primary winding is connected to the positive electrode of the power supply as the input end of the series circuit; the source of the last MOS tube is connected to the negative electrode of the power supply as the output end of the series circuit.

[0018] As a possible implementation, the switching power supply circuit further includes: at least two peak voltage absorption circuits;

[0019] The peak voltage absorption circuit corresponds to the first primary winding of the main transformer on a one-to-one basis and is connected between the first end and the second end of the corresponding first primary winding of the main transformer.

[0020] As a possible implementation, the peak voltage absorption circuit includes: a third resistor, a first capacitor, a second transient suppression diode, and a second unidirectional diode;

[0021] The first end of the first primary winding of the main transformer is connected to the input end of the second transient suppression diode, the first end of the first capacitor and the first end of the third resistor;

[0022] The second end of the third resistor, the second end of the first capacitor and the output end of the second transient suppression diode are connected to the output end of the second unidirectional diode;

[0023] The second end of the first primary winding of the main transformer is connected to the input end of the second unidirectional diode.

[0024] As a possible implementation, the main transformer further includes: a secondary winding corresponding one-to-one to the first primary winding;

[0025] Each of the secondary windings is connected to a subsequent circuit via a rectifier and filter circuit.

[0026] As a possible implementation, the rectification and filtering circuit includes: a third unidirectional diode, a second capacitor and a third transient suppression diode;

[0027] The first end of the secondary winding of the main transformer is connected to the input end of the third unidirectional diode; the output end of the third unidirectional diode is connected to the first end of the second capacitor, the output end of the third transient suppression diode and a subsequent circuit contact; the subsequent circuit contact is used to connect a subsequent circuit;

[0028] The second end of the secondary winding of the main transformer is connected to the second end of the second capacitor, the input end of the third transient suppression diode and the ground.

[0029] As a possible implementation, the main transformer further includes: a second primary winding;

[0030] The first end of the second primary winding is connected to a PWM chip power supply circuit, and the PWM chip power supply circuit is used to supply power to the PWM chip;

[0031] A second end of the second primary winding is grounded.

[0032] As a possible implementation manner, the number of the MOS tube circuits is three.

[0033] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0034] In an embodiment of the present invention, a PWM control circuit is connected to the primary winding of a driving transformer, and the driving transformer controls a MOS tube circuit independently through at least two secondary windings with the same parameters, and the MOS tubes in each MOS tube circuit are connected in series to the primary winding of the main transformer, and the secondary winding of the main transformer is connected to the subsequent circuit. Since the three secondary windings of the driving transformer have the same parameters, the gate drive signals of each MOS tube are synchronized, and sufficient driving capacity is provided. The input power supply is PWM controlled by connecting at least two MOS tubes in series with the primary winding of the main transformer, and each MOS tube is opened and closed synchronously, so that each MOS tube bears the input voltage on average, and the withstand voltage requirement of a single MOS tube is reduced when a high voltage is input. At the same time, the driving transformer can reduce the output voltage by adjusting the number of turns, further ensuring the safety of the switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 The structure of the switching power supply circuit with high voltage input provided by the embodiment of the present invention is shown in FIG. Figure 1 ;

[0037] Figure 2 The structure of the switching power supply circuit with high voltage input provided by the embodiment of the present invention is shown in FIG. Figure 2 ;

[0038] Figure 3 The structure of the switching power supply circuit with high voltage input provided by the embodiment of the present invention is shown in FIG. Figure 3 . DETAILED DESCRIPTION

[0039] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0040] In order to illustrate the technical solution of the present invention, a specific embodiment is provided below for illustration.

[0041] The embodiment of the present invention provides a switching power supply circuit with high voltage input to solve the problem of low input voltage level of the switching power supply in the prior art. The switching power supply circuit includes:

[0042] PWM control circuit, drive transformer, at least two MOS tube circuits and main transformer;

[0043] The PWM control circuit is connected to the primary winding of the driving transformer;

[0044] The driving transformer includes at least two secondary windings with the same parameters, and each secondary winding is connected to a MOS tube circuit;

[0045] The MOS transistors in at least two MOS transistor circuits are connected in series to the primary winding of the main transformer, and the secondary winding of the main transformer is used to connect to the subsequent circuit.

[0046] Figure 1It is a structural schematic diagram of a high voltage input switching power supply circuit provided by an embodiment of the present invention, taking three MOS tube circuits as an example.

[0047] exist Figure 1 In the switching power supply circuit, the PWM signal output by the PWM chip is connected to the primary winding of the driving transformer after passing through the PWM control circuit. The three independent secondary windings of the driving transformer with the same parameters (including number of turns, resistance inductance, specifications and dimensions, etc.) each independently control a MOS tube circuit, specifically the MOS tube in the control MOS tube circuit. The three MOS tubes are connected in series to the primary winding of the main transformer to realize the series control of the three primary windings of the main transformer. The DC power supply of the main transformer can be obtained after rectification and filtering to supply power to the subsequent circuit.

[0048] In this embodiment, because the parameters of the three secondary windings of the driving transformer are the same, the gate drive signals of the three MOS tubes are synchronized, and sufficient driving capability is provided. The input power is PWM controlled by connecting three MOS tubes in series with the primary winding of the main transformer. The three MOS tubes are turned on and off synchronously, so that a single MOS tube only needs to bear 1 / 3 of the input voltage, which reduces the withstand voltage requirement for a single MOS tube when the input voltage is high. At the same time, the driving transformer can reduce the output voltage by adjusting the number of turns, which can further ensure the safety of the switching power supply.

[0049] exist Figure 1 Based on the embodiment, the embodiment of the present invention provides a more detailed structural schematic diagram of a high voltage input switching power supply circuit, see Figure 2 and Figure 3 The following combination Figure 2 and Figure 3 , the switching power supply circuit with high voltage input is explained in detail.

[0050] As a possible implementation, the PWM control circuit 100 may be composed of: capacitor C3, capacitor C4, capacitor C5, unidirectional diode D2, unidirectional diode D3, resistor R1, resistor R2, resistor R26, transient suppression diode TV1, and control MOS tube Q1. The network DVCC is the power supply of the primary winding (13, 14) of the driving transformer T1, the network PWM is the control signal output by the PWM chip, the PWM control signal controls the primary winding (13, 14) of the driving transformer T1 by controlling the MOS tube Q1, and the outputs of the three secondary windings (6, 7) (9, 10) (4, 5) of the driving transformer T1 are respectively used as the gate drive signals of the MOS tubes V1, V2, and V3. The three secondary windings of the driving transformer T1 have the same parameters, which ensures that the gate drive signals of the three MOS tubes are synchronized and provides sufficient driving capability. The driving transformer T1 isolates the PWM control circuit from the high-voltage circuit and improves the stability of the system.

[0051] As a possible implementation, the MOS transistor circuit may include: a discharge circuit 200 and a MOS transistor. The secondary winding of the driving transformer T1 is connected to the discharge circuit 200; the discharge circuit 200 is connected to the MOS transistor. The discharge circuit 200 can limit the peak discharge current to the smallest loop and does not return to the driver, thereby reducing the loop inductance.

[0052] Taking the MOS transistor circuit corresponding to the secondary winding (6, 7) of the driving transformer T1 as an example, the discharge circuit 200 may include: a first resistor R29, a second resistor R38, a first unidirectional diode D4, a first transient suppression diode TV2 and a transistor Q3. The first end 7 of the secondary winding (6, 7) of the driving transformer T1 is connected to the input end of the first unidirectional diode D4, and is connected to the base of the transistor Q3 through the first resistor R29; the output end of the first unidirectional diode D4 is connected to the emitter of the transistor Q3, the output end of the first transient suppression diode TV2, the first end of the second resistor R38 and the gate of the MOS transistor V1; the second end 6 of the secondary winding (6, 7) of the driving transformer T1 is connected to the collector of the transistor Q3, the input end of the first transient suppression diode TV2, the second end of the second resistor R38 and the source of the MOS transistor V1.

[0053] Among them, the diode D4 provides the current path when the MOS tube V1 is turned on, and D4, R29, and Q3 form the fast shutdown circuit of the MOS tube V1. When V1 is turned off, the PNP transistor Q3 is turned on to quickly discharge the charge stored in the gate of V1 to accelerate the shutdown of V1 and reduce the heat generated by V1.

[0054] In this embodiment, a discharge circuit is configured for the gate of each MOS tube to achieve rapid discharge of gate charge, thereby quickly shutting off the MOS tube, reducing heat generation, and improving working reliability.

[0055] As a possible implementation, the main transformer T2 includes: (three) first primary windings (1, 2) (3, 4) (5, 6) of the same number of MOS tubes. MOS tubes V1, V2, and V3 are connected in series with the first primary windings of the main transformer T2 through drains and sources to form a series circuit. Specifically, the first end 1 of the first primary winding (1, 2) is connected to the positive electrode V+ of the power supply as the input end of the series circuit, the second end 2 of the first primary winding (1, 2) is connected to the drain of the MOS tube V1, the source of the MOS tube V1 is connected to the first end 3 of the first primary winding (3, 4), the second end 4 of the first primary winding (3, 4) is connected to the drain of the MOS tube V2, and so on. The source of the last MOS tube V3 is connected to the negative electrode V- of the power supply through resistors R41, R42, R46, and R47 as the output end of the series circuit.

[0056] The three first primary windings (1, 2) (3, 4) (5, 6) of the main transformer T2 and the three MOS tubes V1, V2, and V3 are connected in series, and the three secondary windings (6, 7) (9, 10) (4, 5) of the driving transformer T1 synchronously drive the gates of V1, V2, and V3 to realize the switch control of the high voltage power supply (V+, V-). The MOS tubes V1, V2, and V3 are turned on and off synchronously, so that a single MOS tube only needs to bear 1 / 3 of the input voltage, which reduces the withstand voltage requirement of a single MOS tube when the input voltage is high.

[0057] As a possible implementation, the switching power supply circuit also includes: at least two peak voltage absorption circuits 300; the peak voltage absorption circuits 300 correspond one-to-one to the first primary winding of the main transformer T2, and are connected between the first end and the second end of the corresponding first primary winding of the main transformer T2.

[0058] Taking the peak voltage absorption circuit 300 corresponding to the first primary winding (1, 2) of the main transformer T2 as an example, the peak voltage absorption circuit 300 may include: a third resistor R45, a first capacitor C17, a second transient suppression diode TV7 and a second unidirectional diode D7; the first end 1 of the first primary winding (1, 2) of the main transformer T2 is connected to the input end of the second transient suppression diode TV7, the first end of the first capacitor C17 and the first end of the third resistor R45; the second end of the third resistor R45, the second end of the first capacitor C17 and the output end of the second transient suppression diode TV7 are connected to the output end of the second unidirectional diode D7; the second end 2 of the first primary winding (1, 2) of the main transformer T2 is connected to the input end of the second unidirectional diode D7. The peak voltage absorption circuit 300 can absorb the peak high voltage generated during the fast switching process of the MOS tube.

[0059] As a possible implementation, the main transformer further includes: secondary windings corresponding one to one with the first primary winding; each secondary winding is connected to a subsequent circuit via a rectifier and filter circuit.

[0060] Taking the secondary winding (15, 16) corresponding to the first primary winding (1, 2) of the main transformer T2 and the rectifier filter circuit 400 as an example, the rectifier filter circuit 400 may include: a third unidirectional diode D10, a second capacitor C18 and a third transient suppression diode TV8; the first end 16 of the secondary winding (15, 16) of the main transformer T2 is connected to the input end of the third unidirectional diode D10; the output end of the third unidirectional diode D10 is connected to the first end of the second capacitor C18, the output end of the third transient suppression diode TV8 and the subsequent circuit contact VCC1; the subsequent circuit contact VCC1 is used to connect the subsequent circuit; the second end 15 of the secondary winding (15, 16) of the main transformer T2 is connected to the second end of the second capacitor C18, the input end of the third transient suppression diode TV8 and the ground GND1. After the three secondary windings of the main transformer T2 are rectified and filtered, three mutually isolated DC power supplies can be obtained for use by the subsequent circuit.

[0061] As a possible implementation, the main transformer T2 further includes: a second primary winding 500 (7, 8); a first end 7 of the second primary winding 500 (7, 8) is connected to a PWM chip power supply circuit F+, and the PWM chip power supply circuit is used to power the PWM chip; a second end 8 of the second primary winding is connected to a negative power supply V-. The PWM chip power supply circuit may be a rectifier and filter circuit, and the second primary winding 500 (7, 8) of the main transformer T2 is used as a power supply to power the PWM chip after rectification and filtering.

[0062] It should be noted that, in order to illustrate the switching power supply circuit with high voltage input, the embodiment of the present invention provides Figure 1 , Figure 2 and Figure 3 Three MOS tube circuits are used as examples. In practical applications, fewer or more MOS tube circuits may be provided, and this application does not limit this.

[0063] The current maximum withstand voltage of mainstream MOS tubes is 1.5kV. When the input voltage is close to this voltage, using a single MOS tube for power PWM control may cause major safety hazards such as MOS tube breakdown and input power short circuit. The embodiment of the present invention uses three high-voltage MOS tubes in series for PWM control, which is not limited by the current maximum withstand voltage of 1.5kV of mainstream MOS tubes. It can significantly improve the input voltage level of the switching power supply, or reduce the withstand voltage requirement for a single MOS tube under the same input voltage level. It is very suitable for use as a power supply for devices with high input voltage, low power consumption and small size.

[0064] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A switching power supply circuit with high voltage input, characterized in that: include: PWM control circuit, drive transformer, at least two MOS tube circuits and main transformer; The PWM control circuit is connected to the primary winding of the drive transformer; The driving transformer comprises at least two secondary windings with the same parameters, and each of the secondary windings is connected to one of the MOS tube circuits; The MOS transistors in the at least two MOS transistor circuits are connected in series to the primary winding of the main transformer, and the secondary winding of the main transformer is used to connect to the subsequent circuit.

2. The high voltage input switching power supply circuit according to claim 1, characterized in that: The MOS tube circuit comprises: a discharge circuit and a MOS tube; The secondary winding of the driving transformer is connected to the discharge circuit; The discharge circuit is connected to the MOS tube.

3. The high voltage input switching power supply circuit according to claim 2, characterized in that: The discharge circuit includes: a first resistor, a second resistor, a first unidirectional diode, a first transient suppression diode and a transistor; The first end of the secondary winding of the driving transformer is connected to the input end of the first unidirectional diode, and is connected to the base of the transistor through the first resistor; the output end of the first unidirectional diode is connected to the emitter of the transistor, the output end of the first transient suppression diode, the first end of the second resistor and the gate of the MOS tube; The second end of the secondary winding of the driving transformer is connected to the collector of the transistor, the input end of the first transient voltage suppression diode, the second end of the second resistor and the source of the MOS tube.

4. The high voltage input switching power supply circuit according to claim 2, characterized in that: The main transformer comprises: first primary windings having the same number as the MOS tubes; Each of the MOS tubes is connected in series with each of the first primary windings of the main transformer via a drain and a source to form a series circuit; The first end of the first primary winding is connected to the positive electrode of the power supply as the input end of the series circuit; the source of the last MOS tube is connected to the negative electrode of the power supply as the output end of the series circuit.

5. The high voltage input switching power supply circuit according to claim 4, characterized in that: The switching power supply circuit also includes: at least two peak voltage absorption circuits; The peak voltage absorption circuit corresponds to the first primary winding of the main transformer on a one-to-one basis and is connected between the first end and the second end of the corresponding first primary winding of the main transformer.

6. The high voltage input switching power supply circuit according to claim 5, characterized in that: The peak voltage absorption circuit comprises: a third resistor, a first capacitor, a second transient suppression diode and a second unidirectional diode; The first end of the first primary winding of the main transformer is connected to the input end of the second transient suppression diode, the first end of the first capacitor and the first end of the third resistor; The second end of the third resistor, the second end of the first capacitor and the output end of the second transient suppression diode are connected to the output end of the second unidirectional diode; The second end of the first primary winding of the main transformer is connected to the input end of the second unidirectional diode.

7. The switching power supply circuit with high voltage input as claimed in claim 4, characterized in that: The main transformer further comprises: a secondary winding corresponding one-to-one to the first primary winding; Each of the secondary windings is connected to a subsequent circuit via a rectifier and filter circuit.

8. The high voltage input switching power supply circuit according to claim 7, characterized in that: The rectification and filtering circuit comprises: a third unidirectional diode, a second capacitor and a third transient suppression diode; The first end of the secondary winding of the main transformer is connected to the input end of the third unidirectional diode; the output end of the third unidirectional diode is connected to the first end of the second capacitor, the output end of the third transient suppression diode and a subsequent circuit contact; the subsequent circuit contact is used to connect a subsequent circuit; The second end of the secondary winding of the main transformer is connected to the second end of the second capacitor, the input end of the third transient suppression diode and the ground.

9. The switching power supply circuit with high voltage input as claimed in claim 4, characterized in that: The main transformer further comprises: a second primary winding; The first end of the second primary winding is connected to a PWM chip power supply circuit, and the PWM chip power supply circuit is used to supply power to the PWM chip; The second end of the second primary winding is connected to the negative electrode of the power supply.

10. The high voltage input switching power supply circuit according to any one of claims 1 to 9, characterized in that: The number of the MOS tube circuits is three.

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