Self-adaptive driving circuit and method with wide-range duty ratio change

Abstract

The invention discloses a wide-range duty ratio change self-adaptive driving circuit and method, the circuit comprises a switching power supply driving circuit and a detection turnover circuit arranged in the switching power supply driving circuit, the detection circuit is connected with the turnover circuit, and the real-time voltage stress of a power switch device in the detection circuit during the operation of a power supply product is detected, so that the duty ratio of the power supply product is changed. When the voltage stress reaches a set value, the state of the detection circuit is overturned, and the operational amplifier N1 outputs a high level, so that the driving resistance on the circuit is increased, the voltage stress of the device is reduced or the loss of the switching device is reduced, and therefore, the model selection of the power switching device is easier under the condition that the duty ratio of a product is changed in a wide range.

Description

Technical Field

[0001] The invention belongs to the technical field of switch power supply drive circuits, and in particular relates to an adaptive drive circuit and method with wide range duty cycle variation. Background Art

[0002] The switching power supply drive circuit is an important part of the switching power supply. The circuit structure is as follows: Figure 2 As shown, it is responsible for controlling the switching action of the switch tube, thereby converting the input voltage into a high-frequency pulse signal, which is then transformed by a transformer or inductor and processed by a filter circuit to ultimately obtain a stable DC output voltage.

[0003] However, the existing switching power supply drive circuit parameters are fixed and cannot be adjusted online according to the working state of the current power conversion topology. As a result, when the duty cycle changes over a wide range, it is impossible to take into account both the heating index of the power supply product and the voltage stress at both ends of the switching device. Summary of the invention

[0004] The purpose of the present invention is to provide an adaptive driving circuit and method with a wide range of duty cycle changes, so as to solve the technical problem that the switching power supply driving circuit in the prior art cannot take into account both the heating index of the power supply product and the voltage stress at both ends of the switching device.

[0005] In order to solve the above problems, the present invention adopts the following technical solutions: An adaptive driving circuit with wide range duty cycle variation includes a switching power supply driving circuit and a detection flipping circuit connected to the switching power supply driving circuit, wherein the detection flipping circuit includes a detection module and a flipping module, wherein one end of the detection module is connected to one end of the flipping module, and the other end of the detection module and the other end of the flipping module are both connected to the switching power supply driving circuit; The detection module, one end of the resistor R2 is respectively connected to the negative electrode of the power diode in the switching power drive circuit, the other end of the resistor R2 is divided into two paths, one path is connected to one end of the resistor R5, and the other path is connected to the in-phase input end of the operational amplifier, and the other end of the resistor R5 is divided into two paths, one path is grounded, and the other path is connected to the secondary side of the transformer T1 in the switching power drive circuit; The flip module includes a driving resistor R6, a capacitor C1, a relay S1, and an operational amplifier N1. The middle connection end of the resistors R2 and R5 connected in series is connected to the in-phase input end of the operational amplifier N1. The output end of the operational amplifier N1 is connected to one end of the driving resistor R6 via the relay S1. The other end of the driving resistor R6 is connected to the driving transformer L1 in the switching power supply driving circuit. The capacitor C1 is arranged between the output end of the operational amplifier N1 and the relay S1, and the capacitor C1 is grounded. The driving resistor R6 is connected in parallel with the driving resistor R7 in the switching power supply driving circuit.

[0006] Furthermore, there are two power diodes in the switching power supply driving circuit, and both power diodes are connected to the secondary side of the transformer T1.

[0007] Furthermore, a resistor R3 is connected between the middle connection end of the resistors R2 and R5 connected in series and the non-inverting input end of the operational amplifier N1. Furthermore, a diode V2, a resistor R1 and a resistor R4 are arranged between the output end of the operational amplifier N1 and the relay S1. The diode V2 is connected in series with the resistor R4 and then connected in parallel with the resistor R1. The diode V2 is connected in series with the resistor R4 and then connected in parallel with the resistor R1 and then connected to the reverse input end of the operational amplifier N1. Furthermore, the relay S1 is also connected to a power supply unit. Furthermore, the switching power supply driving circuit includes a switching module and an output module, the output module includes a transformer T1, a diode D1 and a diode D2, the anode end of the diode D1 and the anode end of the diode D2 are both connected to the secondary side of the transformer T1, the cathode end of the diode D1 and the cathode end of the diode D2 are both connected to the resistor R2 of the detection module, the switching module includes a driving resistor R7, and the driving resistor R7 is connected to the relay S1. Furthermore, the switch module also includes a MOS tube, and the MOS tube is connected to the primary side of the transformer T1.

[0008] Furthermore, the switch module further comprises a MOS tube, which is connected to the primary side of the transformer T1. The primary side of the transformer T1 is also connected to a power source VCC. In a second aspect, the present invention provides a method for operating an adaptive driving circuit with a wide range of duty cycle changes, comprising the following steps: When the duty cycle is low, the voltage division of the resistors R2 and R5 in the detection module is large, the operational amplifier N1 in the flip module outputs a high level, the driving relay S1 disconnects the driving resistor R6, and only the driving resistor R7 is connected to the circuit. The resistance in the circuit increases, which reduces the voltage stress of the power diode in the switching power supply driving circuit. The capacitor C1 is used to prevent system oscillation. When the duty cycle is high, the voltage division of resistors R2 and R5 in the detection module is small, the operational amplifier N1 in the flip module outputs a low level, the driving relay S1 connects the driving resistor R6 to the circuit, the driving resistor R6 and the driving resistor R7 are connected to the circuit in parallel, the resistance in the circuit is reduced, so that the switching loss in the switching power supply driving circuit is reduced, and the capacitor C1 is used to prevent system oscillation. Furthermore, the driving resistor R6 and the driving resistor R7 are connected in parallel, and one end of the driving resistor R6 and one end of the driving resistor R7 are both connected to the relay S1. Compared with the prior art, the present invention has the following beneficial technical effects: The present invention relates to an adaptive driving circuit with a wide range of duty cycle changes. A detection flip circuit is connected to a switching power supply driving circuit. A detection module of the detection flip circuit is used to detect the voltage of a medium power switch device. The flip module is used to control the size of the resistance in the circuit. It can be adjusted online according to the working state of the current power conversion topology, so that the selection of the power switch device becomes easy when the product has a wide range of duty cycle changes, and the technical problem of not being able to take into account both the heating index of the power supply product and the voltage stress at both ends of the switch device is solved. Preferably, the flip module further includes a capacitor C1 to prevent malfunction due to interference in the detection circuit, thereby causing the drive circuit to move back and forth and causing system oscillation. The present invention also provides a working method of an adaptive driving circuit with a wide range of duty cycle changes. When the duty cycle is low, the real-time voltage stress of the power switch device in the circuit is detected during the operation of the power supply product. When the voltage stress reaches a set value (the voltage stress increases), the detection circuit will flip the state, and the operational amplifier N1 will output a high level to increase the driving resistance on the circuit, thereby slowing down the switching edge of the power switch device to achieve the effect of reducing the voltage stress of the device; when the duty cycle is high, the operational amplifier N1 will output a low level to reduce the driving resistance on the circuit, the driving edge will become steeper, the switching loss will be reduced, and the heat generation of the product will be reduced, thereby facilitating the selection of the power switch device when the product has a wide range of duty cycle changes. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 Schematic diagram of a structure of an adaptive driving circuit with a wide range of duty cycle changes in an embodiment of the present invention; Figure 2 This is a structural diagram of a switching power supply driving circuit in the prior art. DETAILED DESCRIPTION

[0009] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0010] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0011] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0012] Glossary: The switching power supply drive circuit is the core part of the switching power supply, which is mainly composed of a control chip, a drive circuit and a switch tube. The control chip generates a PWM (pulse width modulation) signal, which is amplified by the drive circuit to control the on and off of the switch tube, thereby realizing the conversion of the input voltage and the stability of the output voltage.

[0013] Example 1 The present invention provides an adaptive driving circuit with a wide range of duty cycle changes, such as Figure 1 As shown, it includes a switching power supply driving circuit and a detection flip circuit arranged in the switching power supply driving circuit, the detection circuit is connected to the flip circuit, wherein the connection sequence is switching power supply driving circuit-detection module-flip module-switching power supply driving circuit, the detection module includes a resistor R2, one end of the resistor R2 is respectively connected to the negative electrodes of the power diodes D1 and D2 in the switching power supply driving circuit, the other end of the resistor R2 is divided into two paths, one is connected to one end of the resistor R5, and the other is connected to the in-phase input end of the operational amplifier through the resistor R3, and the other end of the resistor R5 is divided into two paths, one is grounded, and the other is connected On the secondary side of the transformer T1, the flip module includes an operational amplifier N1, the non-inverting input terminal of the operational amplifier N1 is connected to the middle connection terminal of the resistors R2 and R5 connected in series, the output terminal of the operational amplifier N1 is connected to the relay S1, the relay S1 is connected to the driving resistor R6, and the driving resistor R6 is connected in parallel with the driving resistor R7 in the switching power supply driving circuit; compared with the conventional switching power supply driving circuit, the added detection flip circuit can ensure that when the duty cycle changes over a large range, the comprehensive design index optimization design problem of the heating index of the power supply product and the voltage stress at both ends of the switching device V1 is solved. The capacitor C1 is arranged between the output terminal of the operational amplifier N1 and the relay S1 and is grounded, so as to prevent malfunction due to interference in the detection circuit, thereby causing the drive circuit to operate back and forth and causing system oscillation.

[0014] Example 2 In another embodiment of the present invention, it includes a switching power supply driving circuit and a detection flipping circuit arranged in the switching power supply driving circuit, the detection circuit is connected to the flipping circuit, wherein the detection circuit includes resistors R2 and R5 connected to the power switch in the switching power supply driving circuit, and one end of the resistor R5 is grounded, and the flipping module includes an operational amplifier N1, the non-inverting input end of the operational amplifier N1 is connected to the middle connection end of the resistors R2 and R5 connected in series, the output end of the operational amplifier N1 is connected to the relay S1, and the relay S1 is also connected to the power resistor R6.

[0015] The flipping circuit also includes a resistor R3, which is arranged between the middle connection end of the resistors R2 and R5 connected in series and the non-inverting input end of the operational amplifier N1; a capacitor C1 is also arranged between the output end of the operational amplifier N1 and the relay S1, and a diode V2 and a resistor R4 connected in series with the diode V2 are also included between the output end of the operational amplifier N1 and one end of the capacitor C1. The diode V2 is connected in series with the resistor R4 and then connected in parallel with the resistor R1, and is connected to the inverting input end of the operational amplifier N1, and the other end of the capacitor C1 is grounded.

[0016] Example 3 In another embodiment of the present invention, it includes a switching power supply driving circuit and a detection flipping circuit arranged in the switching power supply driving circuit, the detection circuit is connected to the flipping circuit, wherein the detection circuit includes resistors R2 and R5 connected to the power switch in the switching power supply driving circuit, and one end of the resistor R5 is grounded, and the flipping module includes an operational amplifier N1, the non-inverting input end of the operational amplifier N1 is connected to the middle connection end of the resistors R2 and R5 connected in series, the output end of the operational amplifier N1 is connected to the relay S1, and the relay S1 is also connected to the power resistor R6.

[0017] The flip circuit also includes a resistor R3, which is arranged between the middle connection end of the resistors R2 and R5 connected in series and the non-inverting input end of the operational amplifier N1; a capacitor C1 is also arranged between the output end of the operational amplifier N1 and the relay S1, and a diode V2 and a resistor R4 connected in series with the diode V2 are also included between the output end of the operational amplifier N1 and one end of the capacitor C1. The diode V2 is connected in series with the resistor R4 and then connected in parallel with the resistor R1, and is connected to the inverting input end of the operational amplifier N1, and the other end of the capacitor C1 is connected.

[0018] The switching power supply driving circuit includes a switching module and an output module, wherein the resistor R7 in the switching module is connected to the relay S1, the drain of the MOS tube of the switching module is connected to the primary side of the transformer T1 of the output module, and the secondary side of the transformer T1 is connected to the power switching device.

[0019] Example 4 In another embodiment of the present invention, Figure 1As shown, the secondary side of the transformer T1 is connected to the anode ends of the rectifier diodes D1 and D2, the cathode ends of the rectifier diodes D1 and D2 are connected together and then connected to one end of the resistor R2, and the end of the secondary side of the transformer T1 that is not connected to the rectifier diodes D1 and D2 is connected to one end of the resistor R5 as the ground wire (kGND) of the output end; The middle connection end between the resistors R2 and R5 connected in series is connected to the resistor R3, the other end of the resistor R3 is connected to the 5th pin (non-inverting input terminal) of the operational amplifier N1, the 7th pin (output terminal) of N1 is connected in series with the cathode end of the diode V2 connected in series with the resistor R4 and then connected in parallel with the resistor R1 to form a network, the node where the resistors R1 and R4 are connected is connected to the 6th pin (inverting input terminal) of N1, one end of the capacitor C1 is connected to the 6th pin of N1, and the other end is connected to the ground wire (kGND); One end of capacitor C1 is connected to the R+ end of relay S1, the R- end of S1 is connected to diode V1 (power supply end), the A2 end of relay S1 is connected to resistor R6, the other end of resistor R6 is connected to resistor R7, the A1 end of relay S1 is connected to power resistor R7, the anode of diode V3 and one end of resistor R8, the base of transistor V5 is connected to resistor R8, the emitter is connected to the cathode of diode V3, and the collector is connected to the B end; the anode of voltage regulator tube V4 is connected to the B end, the cathode is connected to the A end, and the A end is connected to the emitter of transistor V5; the A end is connected to the gate (G) of switch tube Q1, the B end is connected to the source (S) of switch tube Q1, the drain (D) of Q1 is connected to one end of the primary side of transformer T1, and the other end of the primary side of T1 transformer is connected to VCC (input power supply). The detection resistors R2 and R5 are used to detect the voltage stress across the rectifier diodes D1 and D2; the circuit function implemented by the resistor R3, operational amplifier N1, resistor R1, resistor R4, diode V2, and capacitor C1 is a level holding function. The length of the level holding time is related to the parameters of the capacitor C1 and the resistor R1. The RC discharge time composed of these two parameters determines the length of time the circuit detects the set high level to prevent malfunction due to interference in the detection circuit, thereby causing the drive circuit to move back and forth and causing system oscillation.

[0020] The present invention also provides a working method of an adaptive driving circuit with a wide range of duty cycle changes, comprising the following steps: When the duty cycle is low, the voltage division of resistors R2 and R5 is large, the operational amplifier N1 outputs a high level, the driving relay S1 disconnects the driving resistor R6, the resistance in the circuit increases, and the voltage stress of the power diode in the switching power supply driving circuit is reduced; When the duty cycle is high, the voltage divider of resistors R2 and R5 is small, the operational amplifier N1 outputs a low level, and the driving relay S1 connects the driving resistor R6 to the circuit. The resistance in the circuit is reduced, so that the switching loss in the switching power supply driving circuit is reduced.

[0021] Specifically, (1) when the duty cycle is low (system output power is low), the voltage stress of D1 and D2 is large, the voltage divider of R2 and R5 is large, the operational amplifier N1 outputs a high level, and the R+ of S1 is a high level. At this time, the control switch of S1 is switched from A2 to A3, and the resistors R6 and R7 are disconnected. The driving resistor on the line is only R7, and the driving edge becomes smooth. The voltage stress of D1 and D2 decreases, but the smooth driving edge will cause the switching loss to increase and the product heat generation to increase. At this time, the product efficiency is sacrificed. However, since the overall output power of the product is low at this time, the increased heat generation is acceptable.

[0022] (2) When the duty cycle is high (system output power is high), the voltage stress of D1 and D2 is small, the operational amplifier N1 outputs a low level, and the R+ of S1 is a low level. At this time, the control switch of S1 is turned from A2 to A1, R6 and R7 are connected in parallel, and the driving resistance on the line is R6. The parallel resistance of R7 is reduced, the driving edge becomes steeper, the switching loss is reduced, and the heat generation of the product is reduced.

[0023] The present invention detects the real-time voltage stress of power diodes V1 and V2 in the circuit during the operation of the power supply product. When the voltage stress reaches the set value (voltage stress increases), the detection circuit will flip the state, and the operational amplifier N1 will output a high level, so that the driving resistance on the circuit increases, thereby slowing down the switching edge of the switching devices V1 and V2 to achieve the effect of reducing the voltage stress of the device. Therefore, the selection of power diodes V1 and V2 becomes easier when the product has a wide range of duty cycle changes (voltage and current parameter indicators are easier to achieve).

[0024] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An adaptive driving circuit with wide range duty cycle variation, characterized in that: It includes a switch power drive circuit and a detection flip circuit connected to the switch power drive circuit, the detection flip circuit includes a detection module and a flip module, one end of the detection module is connected to one end of the flip module, and the other end of the detection module and the other end of the flip module are both connected to the switch power drive circuit; The detection module, one end of the resistor R2 is respectively connected to the negative electrode of the power diode in the switching power drive circuit, the other end of the resistor R2 is divided into two paths, one path is connected to one end of the resistor R5, and the other path is connected to the in-phase input end of the operational amplifier, and the other end of the resistor R5 is divided into two paths, one path is grounded, and the other path is connected to the secondary side of the transformer T1 in the switching power drive circuit; The flip module includes a driving resistor R6, a capacitor C1, a relay S1, and an operational amplifier N1. The middle connection end of the resistors R2 and R5 connected in series is connected to the in-phase input end of the operational amplifier N1. The output end of the operational amplifier N1 is connected to one end of the driving resistor R6 via the relay S1. The other end of the driving resistor R6 is connected to the driving transformer L1 in the switching power supply driving circuit. The capacitor C1 is arranged between the output end of the operational amplifier N1 and the relay S1, and the capacitor C1 is grounded. The driving resistor R6 is connected in parallel with the driving resistor R7 in the switching power supply driving circuit.

2. The adaptive driving circuit with wide duty cycle variation according to claim 1, characterized in that: There are two power diodes in the switching power supply driving circuit, and both power diodes are connected to the secondary side of the transformer T1.

3. The adaptive driving circuit with wide duty cycle variation according to claim 1, characterized in that: A resistor R3 is connected between the middle connection end of the series connection of the resistors R2 and R5 and the non-inverting input end of the operational amplifier N1.

4. The adaptive driving circuit with wide duty cycle variation according to claim 1, characterized in that: A diode V2, a resistor R1 and a resistor R4 are arranged between the output end of the operational amplifier N1 and the relay S1. The diode V2 is connected in series with the resistor R4 and then connected in parallel with the resistor R1. The diode V2 is connected in series with the resistor R4 and then connected in parallel with the resistor R1 and then connected to the reverse input end of the operational amplifier N1.

5. The adaptive driving circuit with wide duty cycle variation according to claim 1, characterized in that: The relay S1 is also connected to a power supply unit.

6. The adaptive driving circuit with wide duty cycle variation according to claim 1, characterized in that: The switching power supply driving circuit includes a switching module and an output module. The output module includes a transformer T1, a diode D1 and a diode D2. The anode end of the diode D1 and the anode end of the diode D2 are both connected to the secondary side of the transformer T1, and the cathode end of the diode D1 and the cathode end of the diode D2 are both connected to the resistor R2 of the detection module. The switching module includes a driving resistor R7, and the driving resistor R7 is connected to the relay S1.

7. The adaptive driving circuit with wide duty cycle variation according to claim 6, characterized in that: The switch module further includes a MOS tube, which is connected to the primary side of the transformer T1.

8. The adaptive driving circuit with wide duty cycle variation according to claim 7, characterized in that: The primary side of the transformer T1 is also connected to a power source VCC.

9. A method for operating an adaptive driving circuit with wide duty cycle variation according to claim 1, characterized in that: The following steps are involved: When the duty cycle is low, the voltage division of the resistors R2 and R5 in the detection module is large, the operational amplifier N1 in the flip module outputs a high level, the driving relay S1 disconnects the driving resistor R6, and only the driving resistor R7 is connected to the circuit. The resistance in the circuit increases, which reduces the voltage stress of the power diode in the switching power supply driving circuit. The capacitor C1 is used to prevent system oscillation. When the duty cycle is high, the voltage division of resistors R2 and R5 in the detection module is small, the operational amplifier N1 in the flip module outputs a low level, the driving relay S1 connects the driving resistor R6 to the circuit, the driving resistor R6 and the driving resistor R7 are connected to the circuit in parallel, the resistance in the circuit is reduced, so that the switching loss in the switching power supply driving circuit is reduced, and the capacitor C1 is used to prevent system oscillation.

10. The operating method of the adaptive driving circuit with wide range duty cycle variation according to claim 9, characterized in that: The driving resistor R6 and the driving resistor R7 are connected in parallel, and one end of the driving resistor R6 and one end of the driving resistor R7 are both connected to the relay S1.

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