Low ripple boost DC-DC converter

Low Ripple Boost DC-DC Converter

This creation is about a low-ripple boost DC-DC converter, in particular, an output current is a continuous conduction current [CCM], which can reduce electromagnetic interference [EMI] without increasing the output capacitor value. Innovative designer of low-ripple boost DC-DC converters that reduce output voltage ripple and have higher voltage conversion at the same switch turn-on ratio, and more practical features in its overall implementation.

According to recent years, the power converters of many electronic products often require high current power supply and high power density. Under the requirements of high current output specifications, power converters will face the problems of power loss and thermal stress of magnetic and semiconductor components. , And the disadvantages of increased output voltage ripple.

Among them, generally common step-up DC-DC converters, please refer to the existing circuit diagram in Figure 5. The converter (2) is mainly connected to the positive pole of the power input terminal and the inductor (21), and the power input terminal The negative electrode is connected to the switch (22) and the capacitor (23) respectively, and the other ends of the inductor (21) and the switch (22) are connected to the anode of the diode (24), and the anode of the diode (24) is connected to The other end of the capacitor (23) is connected, and its voltage conversion ratio is V_O= V_i/ (1-D); Assume that the converter (2) has an input voltage of 12V, an output voltage of 36V, a maximum output power of 50W, a switching frequency of 100kHz, an input inductance of 30μH and an output capacitance of 100μH. The simulation shows that as shown in the current input current and output current waveforms in the sixth figure, the output current of the converter (2) can be seen in the figure as a pulsed current, and please refer to the seventh figure The input and output voltage ripple waveforms are shown in the figure. It can be known that the converter (2) has a peak-to-peak output voltage of 47 ~ 9mV. Please refer to Figure 8 for the current ratio of the input voltage to the output voltage. As shown in the figure, it can be known that when the switch (2) has a conduction ratio of 0 to 67, the output voltage is 36V.

Because of this, the step-up DC-DC converter's output current due to the circuit structure is a discontinuous pulse current, which causes the disadvantage of large output voltage ripple. The ripple voltage and the size of the power supply product are strict. The step-up DC-DC converter products have a great impact.

There are two general methods to resolve the voltage ripple:

The first is to increase the output capacitance value to reduce the voltage ripple. The disadvantage is that the capacitance volume increases, which reduces the power density.

The second is to increase the switching frequency. The disadvantage is that it increases the switching loss and reduces the efficiency.

The reason is that in view of this, the creators have maintained rich design and development and practical production experience in the relevant industry for many years, researched and improved the existing structure and defects, and provided a low-ripple boost DC-DC converter in order to achieve more For the purpose of good practical value.

The low-ripple boost DC-DC converter of this creation, the converter mainly connects the positive terminal of the power input terminal to the first terminal of the input inductor, and the negative terminal of the power input terminal is connected to the switch, the first capacitor and the output capacitor, respectively. The first end of the input inductor is connected, the second end of the input inductor is connected to the second end of the switch, and the first end of the first diode and the second capacitor are connected to the input inductor and the second end of the switch at the same time, the first The second end of the diode and the first capacitor are connected to the first end of the second diode at the same time, and the second end of the second capacitor and the second capacitor are connected to the first end of the output inductor at the same time. The second end of the inductor is connected to the second end of the output capacitor; thus, the output current of the converter is a continuous conduction current [CCM], which can reduce electromagnetic interference [EMI], and can be reduced without increasing the output capacitor value. The output voltage ripples, and the voltage conversion is relatively high at the same switch on ratio, and it is more practical and convenient for its overall implementation and use.

In order to provide a more complete and clear disclosure of the technical content, creative purpose and effectiveness achieved by this creation, it is described in detail below, and please also refer to the drawings and numbers disclosed:

First, please refer to the circuit diagram of this creation in the first picture. The converter (1) in this creation is mainly to connect the positive terminal of the power input terminal to the first terminal of the input inductor (11), and the negative terminal of the power input terminal to The first terminal of the switch (12), the first capacitor (13) and the output capacitor (14) is connected, the second terminal of the input inductor (11) is connected to the second terminal of the switch (12), and the input inductor (11) ) And the second end of the switch (12) are connected at the same time with the first end of the first diode (15) and the second capacitor (16), the first diode (15) and the first end of the first capacitor (13) The two terminals are simultaneously connected to the first terminal of the second diode (17), and the second capacitor (16) and the second terminal of the second diode (17) are simultaneously connected to the first terminal of the output inductor (18). Then the second end of the output inductor (18) is connected to the second end of the output capacitor (14).

In this way, the converter (1) of this creation is used for circuit operation. When the switch (12) is ON and the first diode (15) is OFF, the first capacitor (13) is released. The second capacitor (16) can be charged, so that the forward bias of the second diode (17) is ON, and the voltage across the input inductor (11) is equal to the input voltage, and the current of the input inductor (11) is linear. If the voltage rises, the voltage across the output inductor (18) is the voltage of the first capacitor (13) minus the output voltage, and the current of the output inductor (18) decreases linearly. When the switch (12) is OFF, the first capacitor (13) The input voltage is charged, so that the forward bias of the first diode (15) is ON, and the reverse bias of the second diode (17) is OFF. The input voltage (11) is at this time. The voltage of the first capacitor (13) is subtracted from the input voltage, the current of the input inductor (11) decreases linearly, and the voltage across the output inductor (18) at this time is the voltage of the second capacitor (16) plus the first capacitor 13) voltage minus the output voltage, the output inductor (18) of the current decreases linearly.

Assuming that the converter (1) of this creation has the same electrical specifications as the traditional converter (2), the input voltage is 12V, the output voltage is 36V, the maximum output power is 50W, the switching frequency is 100kHz, the input inductance is 30μH, and the output capacitance is 100μH , It is simulated by IsSpice circuit simulation software. Please refer to the second figure again for the input current and output current waveforms of this creation. It can be known that the output current of this converter (1) is a continuous conduction current [CCM], which can reduce electromagnetic interference [EMI], and Please refer to the third figure again for the input voltage and output voltage ripple waveforms of this creation. It can be seen that the output voltage peak-to-peak value of this creative converter (1) is 13.3mV, and this creative converter (1) The output voltage ripple can be reduced without increasing the output capacitor value. Please refer to Figure 4 again for the input voltage and output voltage ratio waveforms shown in this work. It can be seen that the converter (1) of this work is a switch. When the conduction ratio is 0 ~ 5, the output voltage is 36V, so that at the same switch conduction ratio, the voltage conversion of the creative converter (1) is relatively high.

Based on the above, the composition and implementation of this creative structure can be seen. Compared with the existing structure, this creative is mainly to make the output current be a continuous conduction current, which can reduce electromagnetic interference, and does not need to be increased. The output capacitor value can reduce the output voltage ripple, and the voltage conversion is higher at the same switch on-ratio, and it is more practical and convenient for its overall implementation and use.

The foregoing embodiments or drawings do not limit the structure of this creation, and any appropriate changes or modifications by those with ordinary knowledge in the technical field should be deemed not to depart from the patent scope of this creation.

In summary, this creative embodiment can indeed achieve the expected use effect, and the specific structure disclosed is not only not seen in similar products, nor has it been disclosed before the application. It has fully met the requirements and requirements of the Patent Law. If you apply for a new type of patent in accordance with the law, you are kindly requested to review it and grant the patent.

<p>(1) converter</p><p>(11) Input inductance</p><p>(12) Switch</p><p>(13) the first capacitor</p><p>(14) Output Capacitance</p><p>(15) First Diode</p><p>(16) Second capacitor</p><p>(17) Second Diode</p><p>(18) Output inductance</p><p>(2) converter</p><p>(21) Inductance</p><p>(22) Switch</p><p>(23) Capacitance</p><p>(24) Diode</p>

The first picture: the circuit diagram of this creation

Figure 2: Input current and output current waveforms of this creation

The third picture: the input and output voltage ripple waveforms of this creation

Figure 4: Waveform of input voltage and output voltage ratio of this creation

Figure 5: Schematic of the existing circuit

Figure 6: Current input and output current waveforms

Figure 7: Current input voltage and output voltage ripple waveform

Figure 8: Current input voltage to output voltage ratio waveform