阅读说明：本技术 一种高升压比的Boost电路 (Boost circuit with high Boost ratio ) 是由 张波 汪义旺 齐美星 宋佳 于 2020-12-16 设计创作，主要内容包括：本发明是一种高升压比的Boost电路,该电路包括变压器T、功率开关MOS管Q、二极管D和电容C,所述变压器T的公共端与输入直流电压端Ui的正极相连,变压器T的低压端与功率开关MOS管Q的漏极相连,变压器T的高压端与二极管D的阳极相连,所述二极管D的阴极、电容C的正极和输出直流电压端Uo的正极相连接在一起,所述输入直流电压端Ui的负极、功率开关MOS管Q的源极、电容C的负极和输出输出直流电Uo的负极相连接在一起。本发明电路实现了更高的升压比,更高的效率以及更小的体积和重量。(The invention relates to a Boost circuit with a high step-up ratio, which comprises a transformer T, a power switch MOS tube Q, a diode D and a capacitor C, wherein the common end of the transformer T is connected with the anode of an input direct current voltage end Ui, the low voltage end of the transformer T is connected with the drain electrode of the power switch MOS tube Q, the high voltage end of the transformer T is connected with the anode of the diode D, the cathode of the diode D, the anode of the capacitor C and the anode of an output direct current voltage end UO are connected together, and the cathode of the input direct current voltage end Ui, the source of the power switch MOS tube Q, the cathode of the capacitor C and the cathode of the output direct current UO are connected together. The circuit of the invention realizes higher voltage boosting ratio, higher efficiency and smaller volume and weight.)

1. A Boost circuit with a high step-up ratio comprises an input direct-current voltage end Ui and an output direct-current voltage end Uo and is characterized by comprising a transformer T, a power switch MOS tube Q, a diode D and a capacitor C, wherein the common end of the transformer T is connected with the anode of the input direct-current voltage end Ui, the low-voltage end of the transformer T is connected with the drain electrode of the power switch MOS tube Q, the high-voltage end of the transformer T is connected with the anode of the diode D, the cathode of the diode D, the anode of the capacitor C and the anode of the output direct-current voltage end Uo are connected together, and the cathode of the input direct-current voltage end Ui, the source of the power switch MOS tube Q, the cathode of the capacitor C and the cathode of the output direct-current voltage end Uo are connected together.

2. The Boost circuit with high Boost ratio of claim 1, wherein the transformer T is a high frequency autotransformer.

3. The Boost circuit with high Boost ratio of claim 2, wherein the highest working frequency of the high frequency autotransformer is not lower than 200 kHz.

4. The Boost circuit with high Boost ratio as recited in claim 2, wherein said power switch MOS transistor Q is a MOS transistor of SiC material.

5. The high Boost ratio Boost circuit of claim 2, wherein said diode D is a high frequency schottky diode of SiC material.

Technical Field

The invention relates to the technical field of DC/DC conversion circuits, in particular to a Boost circuit with a high step-up ratio.

Background

The Boost circuit is a Boost type DC/DC conversion circuit, and when a direct current is input, another direct current higher than the input voltage can be obtained. Boost circuits are widely used in applications where the supply voltage is lower than the voltage required by the load. Theoretically, the traditional Boost circuit can have a large Boost ratio, but the traditional Boost circuit has a limited actual circuit Boost ratio, the ratio of the output voltage to the input voltage is difficult to exceed 10, and moreover, the traditional Boost circuit adopts a Si material semiconductor device, so that the problems of low working frequency and large device loss exist.

In view of the above problems, the present invention provides a Boost circuit with a high Boost ratio to achieve a higher Boost ratio, higher efficiency and smaller size and weight.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provides a Boost circuit with a high step-up ratio.

In order to achieve the technical purpose and achieve the technical effect, the invention is realized by the following technical scheme:

a Boost circuit with a high step-up ratio comprises an input direct-current voltage end Ui and an output direct-current voltage end Uo, and the Boost circuit comprises a transformer T, a power switch MOS tube Q, a diode D and a capacitor C, wherein the common end of the transformer T is connected with the anode of the input direct-current voltage end Ui, the low-voltage end of the transformer T is connected with the drain electrode of the power switch MOS tube Q, the high-voltage end of the transformer T is connected with the anode of the diode D, the cathode of the diode D, the anode of the capacitor C and the anode of the output direct-current voltage end Uo are connected together, and the cathode of the input direct-current voltage end Ui, the source of the power switch MOS tube Q, the cathode of the capacitor C and the cathode of the output direct-current end Uo are connected together.

Preferably, the transformer T is a high-frequency autotransformer.

Preferably, the highest working frequency of the high-frequency autotransformer is not lower than 200 kHz.

Preferably, the power switch MOS transistor Q is a MOS transistor made of SiC material.

Preferably, the diode D is a high frequency schottky diode of SiC material.

The invention has the beneficial effects that:

the high-frequency autotransformer is adopted to replace an inductor in a traditional Boost circuit, so that a higher Boost ratio is realized; the SiC semiconductor device with high working frequency and low loss is adopted to replace the traditional Si material semiconductor device, so that higher efficiency and smaller volume and weight are realized.

Drawings

FIG. 1 is a schematic diagram of a Boost circuit with a high step-up ratio of the present invention;

FIG. 2 is a schematic diagram of a high frequency autotransformer of the present invention;

fig. 3 is a conventional Boost circuit diagram.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

As shown in fig. 1, a Boost circuit with a high step-up ratio includes an input dc voltage terminal Ui and an output dc voltage terminal Uo, and the circuit includes a transformer T, a power switch MOS transistor Q, a diode D and a capacitor C, where a common terminal 1 of the transformer T is connected to an anode of the input dc voltage terminal Ui, a low-voltage terminal 2 of the transformer T is connected to a drain of the power switch MOS transistor Q, a high-voltage terminal 3 of the transformer T is connected to an anode of the diode D, a cathode of the diode D, an anode of the capacitor C and an anode of the output dc voltage terminal Uo are connected together, and a cathode of the input dc voltage terminal Ui, a source of the power switch MOS transistor Q, a cathode of the capacitor C and a cathode of the output dc voltage terminal Uo are connected together.

As shown in fig. 2, the transformer T is a high frequency autotransformer.

The highest working frequency of the high-frequency autotransformer is not lower than 200kHz, the number of turns of a coil between a high-voltage end 3 and a common end 1 of the high-frequency autotransformer is n1, the number of turns of a coil between a low-voltage end 2 and the common end 1 is n2, the transformation ratio of the high-frequency autotransformer is n = n1/n2, and the specific structure of the high-frequency autotransformer adopts known contents.

The power switch MOS tube Q is an MOS tube made of SiC materials.

The diode D is a high-frequency Schottky diode made of SiC materials.

The SiC device has small self loss and is beneficial to improving the efficiency, the working frequency of the SiC device can reach more than 200kHz and even megahertz, and the higher working frequency can adopt a filter inductor and a capacitor which are lighter in weight and smaller in volume; SiC devices dissipate heat better than conventional Si material devices and can operate at higher temperatures, so the heat dissipating devices can be lighter and smaller.

Principle of the invention

In the present invention, asAs shown in fig. 1, let the time of the switch Q being turned on in a control cycle be t_onAnd the time of cut-off is recorded as t_offWhen the PWM duty ratio of the controlled pulse width modulation signal is D, then. The iron core magnetic flux of the high-frequency autotransformer increases by an amount during a working period when the circuit is in a steady stateAnd amount of reduction of magnetic flux thereofThe magnitudes are equal, regardless of the sign, and the flux change amounts in both cases are recorded as(ii) a If the number of turns of the coil between the high-voltage end 3 of the transformer T and the common end 1 is n1, the voltage between the high-voltage end 3 of the transformer T and the common end 1 is U1, the number of turns of the coil between the low-voltage end 2 of the transformer T and the common end 1 is n2, and the voltage between the low-voltage end 2 of the transformer T and the common end 1 is U2, the transformer transformation ratio is:。

when the power switch MOS transistor Q is turned on, a voltage U2 between the low-voltage side of the transformer T, i.e., the low-voltage terminal 2 and the common terminal 1:

（1）；

when the power switch MOS transistor Q is turned off, it is easy to know that the voltage between the high-voltage side of the autotransformer T, i.e. the high-voltage end 3 and the common end 1, is equal to the difference between the output voltage Uo and the input voltage Ui, and is also constant, so that:

（2）；

combining formula (1) and formula (2), one can obtain:

（3）；

from formula (3): the invention relates to a relation between the output voltage and the input voltage of a Boost circuit with a high step-up ratio, which is as follows:

（4）；

in the Boost circuit, the direct-current voltage Ui is added to the input end, and the output voltage Uo can be obtained at the output end according to the formula (4); for comparison, a conventional Boost circuit is shown in fig. 3, and it can be seen from the equation that the output voltage is increased in magnitude compared to the conventional Boost circuitThe boosting efficiency is obviously improved by the multiplied input voltage Ui.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.