DC-DC converter with high step-up ratio

Abstract

The invention discloses a DC-DC converter with a high step-up ratio, and relates to the field of step-up power transformation, and the DC-DC converter comprises a three-port self-coupling inductor at least comprising a first winding and a second winding which are connected in series; the three-port self-coupling inductor is provided with a center tap; one end of the center tap is connected with the common end of the first winding and the second winding; the other end of the center tap is connected with the positive electrode of the energy feedback diode and the first end of the switching tube. The first end of the three-port self-coupling inductor is connected with one end of the input end base; the second end of the three-port self-coupling inductor is connected with the positive electrode of the fly-wheel diode; the cathode of the freewheeling diode is respectively connected with the cathode of the energy feedback diode and one end of the output end base; the other end of the input end base, the second end of the switching tube and the other end of the output end base are all grounded; the third end of the switching tube is connected with the digital control module. While the step-up ratio of the DC-DC converter is improved, a circuit protection function is added.

Description

Technical Field

[0001] The present application relates to the technical field of voltage step-up and power conversion, and in particular to a DC-DC converter with a high voltage step-up ratio. Background Art

[0002] A DC-DC converter is a device that converts electrical energy of one voltage value into electrical energy of another voltage value in a DC circuit.

[0003] DC-DC converters are widely used in electronic display devices. The DC-DC converters in electronic display devices convert the input voltage supplied from the outside to generate high potential voltage and low potential voltage for driving pixels. In such electronic display devices, the DC-DC converter can generate positive voltage and negative voltage, and supply the positive voltage and negative voltage to the pixels through the voltage line.

[0004] At present, most electronic display devices use non-isolated DC-DC converters with single-winding inductors, which mainly achieve the boost effect by increasing the duty cycle of the PWM signal. Since the duty cycle adjustment range of the PWM signal is limited, once the maximum adjustment value of the duty cycle is reached, the boost ratio of the DC-DC converter will no longer increase. Therefore, the traditional DC-DC converter is affected by a single adjustment mode, and its maximum boost ratio is generally between 4:1 and 5:1, and it is difficult to achieve a higher boost ratio. In addition, existing DC-DC converters generally only focus on the final boost effect, and do not have more designs to protect circuit safety and improve converter efficiency. Summary of the invention

[0005] The purpose of the present application is to provide a DC-DC converter with a high step-up ratio, which can improve the step-up ratio of the DC-DC converter while having a circuit protection function and optimizing the converter efficiency.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] The present application provides a DC-DC converter with a high voltage step-up ratio, and the DC-DC converter with a high voltage step-up ratio comprises: a three-port auto-coupling inductor, a freewheeling diode, a feeding diode, a switch tube, an input-end base, an output-end base, and a digital control module; the three-port auto-coupling inductor comprises at least a first winding and a second winding connected in series;

[0008] The three-port autoinductor has an intermediate tap; one end of the intermediate tap is connected to the common end of the first winding and the second winding; the other end of the intermediate tap is respectively connected to the positive electrode of the energy feeding diode and the first end of the switch tube;

[0009] The first end of the three-port autoinductor is connected to one end of the input end base; the second end of the three-port autoinductor is connected to the positive electrode of the freewheeling diode; the negative electrode of the freewheeling diode is respectively connected to the negative electrode of the energy feeding diode and one end of the output end base; the other end of the input end base, the second end of the switch tube and the other end of the output end base are all grounded; the third end of the switch tube is connected to the digital control module;

[0010] The digital control module is used to control the on-time and off-time of the switch tube by changing the duty cycle of the PWM signal, and complete the protection control of the DC-DC converter with a high step-up ratio when it is overvoltage, undervoltage or overcurrent.

[0011] Optionally, the three-port autoinductor is used to store energy using the first winding when the switch tube is turned on, and to superimpose the energy stored in the first winding and transmit it to the output end using the second winding when the switch tube is turned off.

[0012] Optionally, the energy feeding diode is used for:

[0013] When the switch tube is turned off, the leakage inductance energy generated by the first winding is fed back to the output end;

[0014] Shunting the freewheeling diode to reduce the peak current stress of the freewheeling diode;

[0015] The switch tube is clamped to protect the switch tube from being broken down by overvoltage caused by oscillation.

[0016] Optionally, the switch tube is an insulated gate field effect tube;

[0017] The drain of the switch tube is respectively connected to the other end of the middle tap and the anode of the energy-feeding diode; the source of the switch tube is grounded; and the gate of the switch tube is connected to the digital control module.

[0018] Optionally, the digital control module includes: a PWM drive module, an ADC module and an MCU;

[0019] One end of the PWM driving module is connected to the gate of the switch tube; the other end of the PWM driving module is connected to the MCU; the ADC module is respectively connected to the MCU, the input terminal base and the output terminal base;

[0020] The MCU is used to:

[0021] When the input voltage is turned on, the ADC module is controlled to sample the output voltage or the output current. When the output voltage or the output current is less than a reference value, the PWM drive module is controlled to gradually increase the duty cycle of the PWM signal until the output voltage or the output current reaches the reference value.

[0022] When the input voltage is connected, the ADC module is controlled to sample the input voltage or the input current. When the input voltage or the input current is not within a set range, the PWM drive module is controlled to turn off the PWM signal.

[0023] Optionally, the turns ratio of the second winding to the first winding is set to:

[0024]

[0025] Where n is the turns ratio of the second winding to the first winding, V0 is the output voltage, VBAT is the input voltage, and Vlx is the DS pole voltage when the switch is turned off.

[0026] Optionally, the maximum boost ratio of the DC-DC converter with a high boost ratio is:

[0027]

[0028] Where M is the maximum boost ratio, V0 is the output voltage, VBAT is the input voltage, n is the turns ratio of the second winding to the first winding, and d is the duty cycle of the PWM signal.

[0029] Optionally, when the switch tube is turned off, the voltage across the second winding is:

[0030]

[0031] Wherein, V2 is the voltage across the second winding, n1 is the number of turns of the first winding, n2 is the number of turns of the second winding, V0 is the output voltage, and VBAT is the input voltage.

[0032] Optionally, both the input end base and the output end base are slot structures.

[0033] Optionally, the input-end base is connected to a power supply via a slot; and the output-end base is connected to a load module via a slot.

[0034] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0035] The present application adopts a three-port autoinductor with an intermediate tap to ensure that one end of the intermediate tap is connected to the common end of the first winding and the second winding connected in series, and a feed diode is connected in parallel on the basis of the freewheeling diode, and the other end of the intermediate tap is connected to the anode of the feed diode. When the switch tube is turned on, the first winding begins to be charged, and when the switch tube is turned off, the first winding begins to release energy. However, unlike a single winding, the second winding of the present application will further increase the voltage released by the first winding by using the turns ratio of the first winding and the second winding, and a single winding cannot achieve this effect, so it can effectively improve the boost ratio. The connection method of the feed diode can share the current for the freewheeling diode, while protecting the switch tube from being broken down by overvoltage. The presence of the digital control module can also protect and control the converter when it is overvoltage, undervoltage or overcurrent, so it has a circuit protection function. In addition, at the moment when the switch tube is turned off, the leakage inductance energy generated by the first winding can be fed back to the output end through the feed diode, thereby optimizing the efficiency of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0037] Figure 1 A schematic diagram of the internal structure of a DC-DC converter with a high voltage step-up ratio provided in an embodiment of the present application.

[0038] Explanation of symbols:

[0039] Three-port auto-coupling inductor-1, freewheeling diode-2, energy feeding diode-3, switch tube-4, input end base-5, output end base-6, digital control module-7. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] The purpose of the present application is to provide a DC-DC converter with a high step-up ratio, which can improve the step-up ratio of the DC-DC converter and have a circuit protection function.

[0042] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0043] This embodiment provides a DC-DC converter with a high voltage step-up ratio. Figure 1 As shown, the DC-DC converter with a high step-up ratio includes: a three-port autoinductor 1, a freewheeling diode 2, a feeding diode 3, a switch tube 4, an input end base 5, an output end base 6 and a digital control module 7; the three-port autoinductor 1 includes at least a first winding N1 and a second winding N2 connected in series.

[0044] The three-port autoinductor 1 has a middle tap; one end of the middle tap is connected to the common end of the first winding N1 and the second winding N2; the other end of the middle tap is connected to the positive electrode of the energy feeding diode 3 and the first end of the switch tube 4 respectively.

[0045] The first end of the three-port autoinductor 1 is connected to one end of the input end base 5; the second end of the three-port autoinductor 1 is connected to the positive electrode of the freewheeling diode 2; the negative electrode of the freewheeling diode 2 is respectively connected to the negative electrode of the feeding diode 3 and one end of the output end base 6; the other end of the input end base 5, the second end of the switch tube 4 and the other end of the output end base 7 are all grounded; the third end of the switch tube 4 is connected to the digital control module 7.

[0046] The digital control module 7 is used to control the on-time and off-time of the switch tube 4 by changing the duty cycle of the PWM signal, and to complete the protection control of the DC-DC converter with a high step-up ratio when it is overvoltage, undervoltage or overcurrent.

[0047] As a preferred implementation, the switch tube 4 is an insulated gate field effect tube; the drain of the switch tube 4 is respectively connected to the other end of the middle tap and the positive electrode of the energy feeding diode 3; the source of the switch tube 4 is grounded; and the gate of the switch tube 4 is connected to the digital control module 7. In addition, the switch tube 4 can also be a junction field effect tube or a GAN, SIC or the like.

[0048] As a preferred embodiment, the input end base 5 and the output end base 6 are both slot structures; the input end base 5 is connected to the power supply through the slot; the output end base 6 is connected to the load module through the slot. In addition, the input end base 5 and the output end base 6 can also be configured with input and output lines or other connection methods.

[0049] In one example, the energy-feeding diode 3 can be selectively deleted according to actual cost considerations, and only the freewheeling diode 2 is retained, and other circuit structures and connection relationships are not changed. In this case, the converter can also achieve a high boost ratio effect, but no longer has the functions of circuit protection and optimizing converter efficiency, but saves economic costs to a certain extent.

[0050] In an example, the digital control module 7 can also change the operating frequency of the switch tube 4 to complete the protection control of the DC-DC converter with a high voltage step-up ratio when it is over-voltage, under-voltage or over-current.

[0051] Furthermore, the key to the high boost ratio of the DC-DC converter with a high boost ratio is the setting of the three-port auto-inductor 1. The different windings in the three-port auto-inductor 1 must be in a series relationship, not in a parallel relationship. At the same time, the three-port auto-inductor 1 can have a pair of windings or multiple pairs of windings. The working principle of the three-port auto-inductor 1 is as follows: when the switch tube 4 is turned on, the three-port auto-inductor 1 uses the first winding N1 to store energy; when the switch tube 4 is turned off, the three-port auto-inductor 1 uses the second winding N2 to superimpose the energy stored in the first winding N1 and transmit it to the output end. When the switch tube 4 is turned off, the energy feeding diode 3 will also feed back the leakage inductance energy generated by the first winding N1 to the output end. The existence of the second winding N2 is the key to achieving a high boost ratio. Since there are multiple windings in the three-port auto-inductor 1, and the number of turns of different windings is different, the turn ratios therebetween must be different. Therefore, when setting the turn ratio of the second winding N2 to the first winding N1, the following relationship needs to be satisfied:

[0052]

[0053] In the formula, n is the turns ratio of the second winding N2 to the first winding N1, V0 is the output voltage, VBAT is the input voltage, and Vlx is the DS pole voltage when the switch tube 4 is turned off. It can be seen that the turns ratio of the second winding N2 to the first winding N1 is mainly related to the input voltage, the output voltage and the DS pole voltage when the switch tube 4 is turned off. Therefore, before setting the turns ratio, it is necessary to determine the input voltage according to the power supply connected to the input base 5, and determine the output voltage according to the load module connected to the output base 6. In order to obtain the voltage conversion ratio in CCM or CRM operation, it is necessary to achieve volt-second balance for the first winding N1 or the second winding N2. For the second winding N2, in each mode, the voltage calculation process at both ends is as follows:

[0054] When the switch tube 4 is turned on: V2 = n × VBAT;

[0055] When switch 4 is turned off:

[0056] The equation is established based on the volt-second balance:

[0057] The voltage gain can be derived as:

[0058] In the formula, V2 is the voltage across the second winding N2, n1 is the number of turns of the first winding N1, n2 is the number of turns of the second winding, d is the duty cycle of the PWM signal, Ts is the switching period, and M is the voltage gain (also known as the maximum boost ratio). It can be seen that the factors affecting the maximum boost ratio are mainly the turns ratio and the duty cycle. For most converters, a single winding inductor is mainly set inside. Since the adjustable range of the duty cycle is certain, once the maximum duty cycle is reached, the boost ratio of the converter has reached the maximum limit. The design of multiple series windings in the three-port autoinductor 1 can further adjust the boost through the turns ratio after the duty cycle cannot be adjusted, so it has a higher boost effect than ordinary converters.

[0059] Furthermore, in addition to the excellent performance in the boost ratio, the above-mentioned DC-DC converter with a high boost ratio also has a unique design in circuit protection, which is mainly reflected in the setting of the energy-feeding diode 3 and the digital control module 7. Among them, the energy-feeding diode 3 is used to: when the switch tube 4 is turned off, the leakage inductance energy generated by the first winding N1 is fed back to the output end; to shunt the freewheeling diode 2 to reduce the peak current stress of the freewheeling diode 2; to clamp the switch tube 4 to protect the switch tube 4 from being broken down by the overvoltage caused by the oscillation. At the moment when the switch tube 4 is turned off, the leakage inductance stored in the first winding N1 will produce oscillations, and this part of the oscillation energy will be transmitted to the output end through the energy-feeding diode 3, thereby realizing the effective utilization of energy. Since the output voltage is fixed, the energy-feeding diode 3 also realizes the clamping effect on the switch tube voltage, protecting the switch tube 4 from being broken down by the overvoltage caused by the oscillation. This clamping voltage is equal to the voltage drop of the switch tube 4 plus the output voltage.

[0060] Furthermore, the digital control module 7 includes: a PWM drive module, an ADC module and an MCU; one end of the PWM drive module is connected to the gate of the switch tube 4; the other end of the PWM drive module is connected to the MCU; the ADC module is respectively connected to the MCU, the input terminal base and the output terminal base; the MCU is used to:

[0061] When the input voltage is connected, the ADC module is controlled to sample the output voltage or the output current. When the output voltage or the output current is less than the reference value, the PWM drive module is controlled to gradually increase the duty cycle of the PWM signal until the output voltage or the output current reaches the reference value.

[0062] When the input voltage is connected, the ADC module is controlled to sample the input voltage or input current. When the input voltage or input current is not within the set range, the PWM drive module is controlled to turn off the PWM signal. For example: when the input voltage is greater than the highest voltage setting value, the DC-DC converter with a high step-up ratio is at risk of overvoltage and the PWM signal needs to be turned off; when the input voltage is less than the lowest voltage setting value, the DC-DC converter with a high step-up ratio is at risk of undervoltage and the PWM signal needs to be turned off; when the input current is greater than the maximum current setting value, the DC-DC converter with a high step-up ratio is at risk of overcurrent and the PWM signal needs to be turned off.

[0063] In summary, the three-port auto-coupling inductor 1 with a middle tap is the core component of the converter. The three-port auto-coupling inductor 1 is divided into a first winding N1 and a second winding N2. The turns ratio of the second winding N2 to the first winding N1 is optimized according to the voltage step-up ratio of the input terminal voltage and the output terminal voltage; the digital control module 7 outputs a PWM signal to drive the switch tube 4 to achieve a duty cycle output of 1-99%. At the same time, with the reasonable choice of the turns ratio, an ultra-high voltage step-up ratio (>10:1) and optimized inductor current and freewheeling tube peak current can be achieved, reducing output ripple and device peak current stress. In addition, the DC-DC converter with a high voltage step-up ratio can improve radiation interference and improve efficiency, and can realize output voltage / current detection, dimming current control, overvoltage / overcurrent protection functions, and automatic closed-loop control.

[0064] All actions to obtain signals, information or data in this application are carried out in compliance with the relevant data protection laws and policies of the country where they are located, and with the authorization given by the owner of the corresponding device.

[0065] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0066] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A DC-DC converter with a high step-up ratio, characterized in that: The DC-DC converter with a high step-up ratio comprises: a three-port auto-inductor, a freewheeling diode, a feeding diode, a switch tube, an input end base, an output end base and a digital control module; the three-port auto-inductor comprises at least a first winding and a second winding connected in series; The three-port autoinductor has an intermediate tap; one end of the intermediate tap is connected to the common end of the first winding and the second winding; the other end of the intermediate tap is respectively connected to the positive electrode of the energy feeding diode and the first end of the switch tube; The first end of the three-port autoinductor is connected to one end of the input end base; the second end of the three-port autoinductor is connected to the positive electrode of the freewheeling diode; the negative electrode of the freewheeling diode is respectively connected to the negative electrode of the energy feeding diode and one end of the output end base; the other end of the input end base, the second end of the switch tube and the other end of the output end base are all grounded; the third end of the switch tube is connected to the digital control module; The digital control module is used to control the on-time and off-time of the switch tube by changing the duty cycle of the PWM signal, and complete the protection control of the DC-DC converter with a high step-up ratio when it is overvoltage, undervoltage or overcurrent.

2. The DC-DC converter with a high voltage step-up ratio according to claim 1, characterized in that: The three-port autoinductor is used to store energy using the first winding when the switch tube is turned on, and to superimpose the energy stored in the first winding and transmit it to the output end using the second winding when the switch tube is turned off.

3. The DC-DC converter with a high step-up ratio according to claim 1, characterized in that: The energy feeding diode is used for: When the switch tube is turned off, the leakage inductance energy generated by the first winding is fed back to the output end; Shunting the freewheeling diode to reduce the peak current stress of the freewheeling diode; The switch tube is clamped to protect the switch tube from being broken down by overvoltage caused by oscillation.

4. The DC-DC converter with a high voltage step-up ratio according to claim 1, characterized in that: The switch tube is an insulated gate field effect tube; The drain of the switch tube is respectively connected to the other end of the middle tap and the anode of the energy-feeding diode; the source of the switch tube is grounded; and the gate of the switch tube is connected to the digital control module.

5. The DC-DC converter with a high voltage step-up ratio according to claim 4, characterized in that: The digital control module includes: a PWM drive module, an ADC module and an MCU; One end of the PWM driving module is connected to the gate of the switch tube; the other end of the PWM driving module is connected to the MCU; the ADC module is respectively connected to the MCU, the input terminal base and the output terminal base; The MCU is used to: When the input voltage is turned on, the ADC module is controlled to sample the output voltage or the output current. When the output voltage or the output current is less than a reference value, the PWM drive module is controlled to gradually increase the duty cycle of the PWM signal until the output voltage or the output current reaches the reference value. When the input voltage is connected, the ADC module is controlled to sample the input voltage or the input current. When the input voltage or the input current is not within a set range, the PWM drive module is controlled to turn off the PWM signal.

6. The DC-DC converter with a high step-up ratio according to claim 5, characterized in that: The turns ratio of the second winding to the first winding is set as: Where n is the turns ratio of the second winding to the first winding, V0 is the output voltage, VBAT is the input voltage, and Vlx is the DS pole voltage when the switch is turned off.

7. The DC-DC converter with a high voltage step-up ratio according to claim 5, characterized in that: The maximum boost ratio of the DC-DC converter with a high boost ratio is: Where M is the maximum boost ratio, V0 is the output voltage, VBAT is the input voltage, n is the turns ratio of the second winding to the first winding, and d is the duty cycle of the PWM signal.

8. The DC-DC converter with a high voltage step-up ratio according to claim 5, characterized in that: When the switch is turned off, the voltage across the second winding is: Wherein, V2 is the voltage across the second winding, n1 is the number of turns of the first winding, n2 is the number of turns of the second winding, V0 is the output voltage, and VBAT is the input voltage.

9. The DC-DC converter with a high step-up ratio according to claim 1, characterized in that: The input end base and the output end base are both slot structures.

10. The DC-DC converter with a high voltage step-up ratio according to claim 9, characterized in that: The input end base is connected to the power supply through a slot; the output end base is connected to the load module through a slot.

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