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 step-up power conversion, and particularly to a DC-DC converter with a high 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 converter in an electronic display device converts the input voltage supplied from the outside to generate a high-potential voltage and a low-potential voltage for driving pixels. In such an electronic display device, the DC-DC converter can generate a positive voltage and a negative voltage, and supply the positive voltage and the negative voltage to the pixels through voltage lines.

[0004] Currently, most electronic display devices use a non-isolated DC-DC converter with a single-winding inductor, which mainly achieves the step-up effect by increasing the duty cycle of the PWM signal. Since the adjustment range of the duty cycle of the PWM signal is limited, once the maximum adjustment value of the duty cycle is reached, the step-up ratio of the DC-DC converter will no longer increase. Therefore, affected by the single adjustment mode, the maximum step-up ratio of the traditional DC-DC converter is generally between 4:1 and 5:1, and it is very difficult to achieve a higher step-up ratio. In addition, existing DC-DC converters generally only focus on the final step-up effect, and do not have more designs for protecting the circuit safety and improving the 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 have a circuit protection function and optimize the converter efficiency while increasing the step-up ratio of the DC-DC converter.

[0006] To achieve the above purpose, the present application provides the following solutions:

[0007] The present application provides a DC-DC converter with a high step-up ratio, which includes: a three-port autotransformer inductor, a freewheeling diode, a feeding diode, a switching tube, an input terminal base, an output terminal base, and a digital control module; the three-port autotransformer inductor at least includes a first winding and a second winding connected in series;

[0008] The three-port autotransformer inductor has a center tap; one end of the center tap is connected to the common end of the first winding and the second winding; the other end of the center tap is respectively connected to the positive pole of the feeding diode and the first end of the switching tube;

[0009] One end of the first terminal of the three-port autotransformer inductor is connected to one end of the input terminal base; one end of the second terminal of the three-port autotransformer inductor 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 terminal base; the other end of the input terminal base, the second terminal of the switching tube, and the other end of the output terminal base are all grounded; the third terminal of the switching tube is connected to the digital control module;

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

[0011] Optionally, the three-port autotransformer inductor is configured to store energy in the first winding when the switching tube is on, and to superimpose and transfer the energy stored in the first winding to the output terminal by using the second winding when the switching tube is off.

[0012] Optionally, the energy feeding diode is configured to:

[0013] When the switching tube is off, feedback the leakage inductance energy generated by the first winding to the output terminal;

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

[0015] Clamp the switching tube to protect the switching tube from being broken down by the overvoltage generated by the oscillation.

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

[0017] The drain of the switching tube is respectively connected to the other end of the center tap and the positive electrode of the energy feeding diode; the source of the switching tube is grounded; the gate of the switching tube is connected to the digital control module.

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

[0019] One end of the PWM driving module is connected to the gate of the switching 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 configured to:

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

[0022] When the input terminal voltage is turned on, control the ADC module to sample the input terminal voltage or input terminal current. When the input terminal voltage or input terminal current is not within the set range, control the PWM driving module to turn off the PWM signal.

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

[0024]

[0025] In the formula, n is the turn ratio of the second winding to the first winding, V0 is the output terminal voltage, VBAT is the input terminal voltage, and Vlx is the voltage between the D and S poles of the switching transistor when it is turned off.

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

[0027]

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

[0029] Optionally, when the switching transistor is turned off, the voltage across the second winding is:

[0030]

[0031] In the formula, 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 terminal voltage, and VBAT is the input terminal voltage.

[0032] Optionally, both the input terminal base and the output terminal base are of a slot structure.

[0033] Optionally, the input terminal base is connected to the power supply through a slot; the output terminal base is connected to the load module through a slot.

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

[0035] This application uses a three-port autotransformer with a center tap, ensuring that one end of the center tap is connected to the common end of the first winding and the second winding connected in series. At the same time, a feed energy diode is connected in parallel on the basis of the freewheeling diode, and the other end of the center tap is connected to the anode of the feed energy diode. When the switch is turned on, the first winding starts to be charged. When the switch is turned off, the first winding starts to release energy. However, different from a single winding, the second winding of this application can further boost the voltage released by the first winding by using the turns ratio of the first winding and the second winding, which cannot be achieved by a single winding. Therefore, the boost ratio can be effectively increased. The connection method of the feed energy diode can share the current for the freewheeling diode and protect the switch from being broken down by overvoltage at the same time. The presence of the digital control module can also protect and control the converter when overvoltage, undervoltage or overcurrent occurs in the converter. Therefore, it has a circuit protection function. In addition, at the moment when the switch is turned off, the leakage inductance energy generated by the first winding can be fed back to the output end through the feed energy diode, thereby optimizing the converter efficiency. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 It is a schematic diagram of the internal structure of a DC-DC converter with a high boost ratio provided by an embodiment of the present application.

[0038] Symbol Description:

[0039] Three-port autotransformer - 1, Freewheeling diode - 2, Feed energy diode - 3, Switch - 4, Input terminal base - 5, Output terminal base - 6, Digital control module - 7. Detailed Embodiments

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0041] The purpose of this application is to provide a DC-DC converter with a high boost ratio, which can improve the boost ratio of the DC-DC converter and have a circuit protection function at the same time.

[0042] To make the above objects, features, and advantages of the present application more apparent and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] This embodiment provides a DC-DC converter with a high boost ratio. As Figure 1 shown, the DC-DC converter with a high boost ratio includes: a three-port autotransformer inductor 1, a freewheeling diode 2, an energy feeding diode 3, a switching transistor 4, an input terminal base 5, an output terminal base 6, and a digital control module 7; the three-port autotransformer inductor 1 includes at least a first winding N1 and a second winding N2 connected in series.

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

[0045] One end of the first end of the three-port autotransformer inductor 1 is connected to one end of the input terminal base 5; the second end of the three-port autotransformer inductor 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 energy feeding diode 3 and one end of the output terminal base 6; the other end of the input terminal base 5, the second end of the switching transistor 4, and the other end of the output terminal base 7 are all grounded; the third end of the switching transistor 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 switching transistor 4 by changing the duty cycle of the PWM signal, and complete the protection control when the DC-DC converter with a high boost ratio has overvoltage, undervoltage, or overcurrent.

[0047] As a preferred embodiment, the switching transistor 4 is an insulated gate field effect transistor; the drain of the switching transistor 4 is respectively connected to the other end of the center tap and the positive electrode of the energy feeding diode 3; the source of the switching transistor 4 is grounded; the gate of the switching transistor 4 is connected to the digital control module 7. In addition, the switching transistor 4 can also be selected as a junction field effect transistor or in the form of GAN, SIC, etc.

[0048] As a preferred embodiment, both the input terminal base 5 and the output terminal base 6 are slot structures; the input terminal base 5 is connected to the power supply through the slot; the output terminal base 6 is connected to the load module through the slot. In addition, the input terminal base 5 and the output terminal base 6 can also be set 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 remain unchanged. In this case, the converter can also achieve the effect of a high boost ratio, but no longer has the functions of circuit protection and optimizing the converter efficiency, but saves economic costs to a certain extent.

[0050] In one example, the digital control module 7 can also complete the protection control when the DC-DC converter with a high boost ratio is overvoltage, undervoltage or overcurrent by changing the operating frequency of the switching transistor 4.

[0051] Furthermore, the key for the above DC-DC converter with a high boost ratio to achieve a high boost ratio lies in the setting of the three-port autotransformer inductor 1. The different windings in the three-port autotransformer inductor 1 must be in series relationship and cannot be in parallel relationship. At the same time, there can be a pair of windings or multiple pairs of windings inside the three-port autotransformer inductor 1. The working principle of the three-port autotransformer inductor 1 is as follows: when the switching transistor 4 is turned on, the three-port autotransformer inductor 1 stores energy using the first winding N1; when the switching transistor 4 is turned off, the three-port autotransformer inductor 1 uses the second winding N2 to superpose and transfer the energy stored in the first winding N1 to the output terminal. At the same time when the switching transistor 4 is turned off, the energy feedback diode 3 will also feedback the leakage inductance energy generated by the first winding N1 to the output terminal. 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 autotransformer inductor 1 and the number of turns of different windings is different, the turns ratio therebetween must be different. Therefore, when setting the turns 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 terminal voltage, VBAT is the input terminal voltage, and Vlx is the DS pole voltage when the switching transistor 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 terminal voltage, the output terminal voltage and the DS pole voltage when the switching transistor 4 is turned off. Therefore, before setting the turns ratio, it is necessary to determine the input terminal voltage according to the power supply connected to the input terminal base 5, and determine the output terminal voltage according to the load module connected to the output terminal 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 thereof is as follows:

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

[0055] When the switching transistor 4 is turned off:

[0056] Establish an equation according to volt-second balance:

[0057] The voltage gain can be deduced:

[0058] Wherein, 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 main factors affecting the maximum boost ratio are 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 fixed, once the maximum duty cycle is reached, the boost ratio of the converter reaches the maximum limit. However, the design of multiple series windings in the three-port autotransformer 1 can further adjust the boost ratio 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 excellent performance in the boost ratio, the above 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 feedback diode 3 and the digital control module 7. Among them, the energy feedback diode 3 is used for: when the switch 4 is turned off, feeding back the leakage inductance energy generated by the first winding N1 to the output terminal; shunting the freewheeling diode 2 to reduce the peak current stress of the freewheeling diode 2; clamping the switch 4 to protect the switch 4 from being broken down by the overvoltage generated by the oscillation. At the moment when the switch 4 is turned off, the leakage inductance stored in the first winding N1 will generate oscillation, and this part of the oscillation energy will be transmitted to the output terminal through the energy feedback diode 3, thus realizing the effective utilization of energy. Since the output voltage is fixed, the energy feedback diode 3 also realizes the clamping function of the switch voltage to protect the switch 4 from being broken down by the overvoltage generated by the oscillation. This clamping voltage is equal to the voltage drop of the switch 4 plus the output terminal voltage.

[0060] Furthermore, the digital control module 7 includes: a PWM driving module, an ADC module, and an MCU; one end of the PWM driving module is connected to the gate of the switch 4; 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 for:

[0061] When the input terminal voltage is turned on instantaneously, controlling the ADC module to sample the output terminal voltage or the output terminal current. When the output terminal voltage or the output terminal current is less than the reference value, controlling the PWM driving module to gradually increase the duty cycle of the PWM signal until the output terminal voltage or the output terminal current reaches the reference value;

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

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

[0064] All actions of obtaining signals, information or data in this application are carried out on the premise of complying with the corresponding data protection regulations and policies of the country where it is located and obtaining the authorization given by the owner of the corresponding device.

[0065] The various embodiments in this specification are described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0066] Specific examples are used in this article to elaborate on the principles and implementation methods of this application. The descriptions of the above embodiments are only used to help understand the method and its core idea of this application. At the same time, for those of ordinary skill in the art, based on the idea of this application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A DC-DC converter with a high voltage boost ratio, characterized in that, The DC-DC converter with a high boost ratio includes: a three-port autotransformer inductor, a freewheeling diode, a power-feed diode, a switching transistor, an input terminal base, an output terminal base, and a digital control module; the three-port autotransformer inductor at least includes a first winding and a second winding connected in series; The three-port autotransformer inductor has a center tap by itself; one end of the center tap is connected to the common end of the first winding and the second winding; the other end of the center tap is respectively connected to the anode of the power-feed diode and the first end of the switching transistor; One end of the first winding of the three-port autotransformer inductor is connected to one end of the input terminal base; one end of the second winding of the three-port autotransformer inductor is connected to the anode of the freewheeling diode; the cathode of the freewheeling diode is respectively connected to the cathode of the power-feed diode and one end of the output terminal base; the other end of the input terminal base, the second end of the switching transistor, and the other end of the output terminal base are all grounded; the third end of the switching transistor is connected to the digital control module; The digital control module is used to control the on-time and off-time of the switching transistor by changing the duty cycle of the PWM signal, and complete the protection control when the DC-DC converter with a high boost ratio has overvoltage, undervoltage, or overcurrent.

2. The DC-DC converter with a high step-up ratio according to claim 1, wherein The three-port autotransformer inductor is used to store energy in the first winding when the switching transistor is on, and, when the switching transistor is off, use the second winding to superimpose and transfer the energy stored in the first winding to the output terminal.

3. The DC-DC converter with a high step-up ratio according to claim 1, characterized in that, The power-feed diode is used for: When the switching transistor is off, feedback the leakage inductance energy generated by the first winding to the output terminal; Shunt the freewheeling diode to reduce the peak current stress of the freewheeling diode; Clamp the switching transistor to protect the switching transistor from being broken down by the overvoltage generated by oscillation.

4. The DC-DC converter with a high boost ratio according to claim 1, characterized in that, The switching transistor is an insulated-gate field-effect transistor; The drain of the switching transistor is respectively connected to the other end of the center tap and the anode of the power-feed diode; the source of the switching transistor is grounded; the gate of the switching transistor is connected to the digital control module.

5. The DC-DC converter with a high boost ratio according to claim 4, characterized in that, The digital control module includes: a PWM driving module, an ADC module, and an MCU; One end of the PWM driving module is connected to the gate of the switching transistor; 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 for: When the input voltage is connected instantaneously, control the ADC module to sample the output voltage or output current. When the output voltage or output current is less than the reference value, control the PWM driving module to gradually increase the duty cycle of the PWM signal until the output voltage or output current reaches the reference value; When the input voltage is connected, control the ADC module to sample the input voltage or input current. When the input voltage or input current is not within the set range, control the PWM driving module 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 to: Wherein, n is the turn ratio of the second winding to the first winding, V0 is the output terminal voltage, VBAT is the input terminal voltage, and Vlx is the DS pole voltage when the switching tube is turned off.

7. The DC-DC converter with a high boost ratio according to claim 5, characterized in that, The maximum boost ratio of the DC-DC converter with a high boost ratio is: Wherein, M is the maximum boost ratio, V0 is the output terminal voltage, VBAT is the input terminal voltage, n is the turn 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 boost ratio according to claim 5, characterized in that, When the switching tube 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 terminal voltage, and VBAT is the input terminal voltage.

9. The DC-DC converter with a high step-up ratio according to claim 1, wherein Both the input terminal base and the output terminal base are slot structures.

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

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