TWI826135B - Boost converter with high conversion efficiency - Google Patents

Abstract

A boost converter with high conversion efficiency includes a bridge rectifier, a boost inductor, a power switch element, an output stage circuit, a detection circuit, and an MCU (Microcontroller Unit). The bridge rectifier generates a rectified voltage according to a first input voltage and a second input voltage. The boost inductor receives the rectified voltage. The power switch element selectively couples the boost inductor to a ground voltage according to a PWM (Pulse Width Modulation) voltage. The output stage circuit is coupled to the boost inductor, and is configured to generate an output voltage. The detection circuit monitors the rectified voltage and generates a detection voltage. The MCU generates the PWM voltage. The MCU includes a duty cycle control unit. The duty cycle control unit determines a duty cycle of the PWM voltage according to the detection voltage.

Description

High conversion efficiency boost converter

The present invention relates to a boost converter, and in particular to a boost converter with high conversion efficiency.

Boost converter is an indispensable component in the notebook computer field. However, if the conversion efficiency of the boost converter is insufficient, it will easily cause the overall operating performance of the related notebook computer to decline. In view of this, it is necessary to propose a new solution to overcome the difficulties faced by previous technologies.

In a preferred embodiment, the present invention proposes a boost converter with high conversion efficiency, including: a bridge rectifier that generates a rectified potential based on a first input potential and a second input potential; a boost inductor, receiving the rectified potential; a power switch to selectively couple the boost inductor to a ground potential according to a pulse width modulation potential; an output stage circuit coupled to the boost inductor, and generates an output potential; a detection circuit monitors the rectified potential and generates a detection potential; and a microcontroller generates the pulse width modulation potential and includes a duty cycle control unit; wherein the duty The period control unit determines the duty cycle of the pulse width modulation potential based on the detection potential.

In some embodiments, the microcontroller further includes a switching frequency control unit, and the switching frequency control unit determines the switching frequency of the pulse width modulation potential according to the detection potential.

In some embodiments, if the rectified potential decreases by a smaller proportion, the microcontroller will gradually increase the duty cycle of the PWM potential.

In some embodiments, if the rectified potential decreases by a moderate ratio, the microcontroller will maintain the duty cycle of the PWM potential at a maximum feasible value and gradually reduce the PWM potential. The switching frequency of the potential.

In some embodiments, if the rectified potential decreases by a large proportion, the microcontroller will maintain the duty cycle of the pulse width modulation potential at a maximum feasible value while maintaining the pulse width modulation The switching frequency of the potential is at a minimum feasible value.

In some embodiments, the maximum feasible value is approximately 75% and the minimum feasible value is approximately 40 kHz.

In some embodiments, the bridge rectifier includes: a first diode having an anode and a cathode, wherein the anode of the first diode is coupled to a first input node to receive the first input potential, and the cathode of the first diode is coupled to a first node to output the rectified potential; a second diode has an anode and a cathode, wherein the second diode The anode is coupled to a second input node to receive the second input potential, and the cathode of the second diode is coupled to the first node; a third diode has an anode and a cathode , wherein the anode of the third diode is coupled to a ground potential, and the cathode of the third diode is coupled to the first input node; and a fourth diode having an anode and a cathode, wherein the anode of the fourth diode is coupled to the ground potential, and the cathode of the fourth diode is coupled to the second input node.

In some embodiments, the boost inductor has a first terminal and a second terminal, the first terminal of the boost inductor is coupled to the first node to receive the rectified potential, and the boost inductor The second end of the device is coupled to a second node.

In some embodiments, the power switch includes: a switching transistor having a control terminal, a first terminal, and a second terminal, wherein the control terminal of the switching transistor is used to receive the pulse width. To modulate the potential, the first terminal of the switching transistor is coupled to the ground potential, and the second terminal of the switching transistor is coupled to the second node.

In some embodiments, the output stage circuit includes: a fifth diode having an anode and a cathode, wherein the anode of the fifth diode is coupled to the second node, and the fifth diode The cathode of the pole body is coupled to an output node to output the output potential; and an output capacitor has a first terminal and a second terminal, wherein the first terminal of the output capacitor is coupled to the output node , and the second terminal of the output capacitor is coupled to the ground potential.

In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are listed below and described in detail with reference to the accompanying drawings.

Certain words are used in the specification and patent claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and the patent application do not use differences in names as a way to distinguish components, but differences in functions of components as a criterion for distinction. The words "include" and "include" mentioned throughout the specification and the scope of the patent application are open-ended terms, and therefore should be interpreted as "include but not limited to." The term "approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem and achieve the basic technical effect within a certain error range. In addition, the word "coupling" in this specification includes any direct and indirect electrical connection means. Therefore, if a first device is coupled to a second device, it means that the first device can be directly electrically connected to the second device, or indirectly electrically connected to the second device via other devices or connections. Two devices.

FIG. 1 is a schematic diagram of a boost converter 100 according to an embodiment of the present invention. For example, the boost converter 100 can be applied to desktop computers, notebook computers, or all-in-one computers. As shown in Figure 1, the boost converter 100 includes: a bridge rectifier 110, a boost inductor LU, a power switch 120, an output stage circuit 130, a detection circuit 140, and a microcontroller ( Microcontroller Unit (MCU)150. It should be noted that, although not shown in FIG. 1 , the boost converter 100 may further include other components, such as a voltage regulator or/and a negative feedback circuit.

The bridge rectifier 110 can generate a rectified potential VR according to a first input potential VIN1 and a second input potential VIN2, wherein one of the first input potential VIN1 and the second input potential VIN2 can have any frequency and any amplitude. AC voltage. For example, the frequency of the AC voltage can be about 50Hz or 60Hz, and the root mean square value of the AC voltage can be about 90V to 264V, but it is not limited thereto. The boost inductor LU receives the rectified potential VR. The power switch 120 can selectively couple the boost inductor LU to a ground potential VSS (eg, 0V) according to a pulse width modulation potential VM. For example, if the pulse width modulation potential VM is a high logic level (ie, logic “1”), the power switch 120 may couple the boost inductor LU to the ground potential VSS (ie, the power The switch 120 can approximate a short-circuit path); conversely, if the pulse width modulation potential VM is a low logic level (ie, logic "0"), the power switch 120 will not convert the boost inductor LU is coupled to ground potential VSS (ie, power switch 120 may approximate an open path). The output stage circuit 130 is coupled to the boost inductor LU and can generate an output potential VOUT. For example, the output potential VOUT can be a DC potential, and its potential level can be about 400V, but it is not limited thereto. The detection circuit 140 can monitor the rectification potential VR and generate a detection potential VD accordingly. The microcontroller 150 can generate the pulse width modulation potential VM. Specifically, the microcontroller 150 includes a duty cycle control unit 152, which can be implemented in the form of a hardware circuit or a software program. The duty cycle control unit 152 can determine a duty cycle (Duty Cycle) D of the pulse width modulation potential VM according to the detection potential VD. Under this design, if the rectifier potential VR suddenly drops due to non-ideal environmental factors, the microcontroller 150 can also appropriately adjust the duty cycle D of the pulse width modulation potential VM so that the operation of the boost inductor LU can still be maintained. It works normally and complies with the law of conservation of energy. According to actual measurement results, the design proposed by the present invention can effectively improve the conversion efficiency of the boost converter 100 .

The following embodiments will introduce the detailed structure and operation of the boost converter 100 . It must be understood that these drawings and descriptions are only examples and are not intended to limit the scope of the invention.

Figure 2 is a circuit diagram of a boost converter 200 according to an embodiment of the present invention. In the embodiment of FIG. 2, the boost converter 200 has a first input node NIN1, a second input node NIN2, and an output node NOUT, and includes a bridge rectifier 210, a boost inductor LU, a A power switch 220, an output stage circuit 230, a detection circuit 240, and a microcontroller 250. The first input node NIN1 and the second input node NIN2 of the boost converter 200 may be used to receive a first input potential VIN1 and a second input potential VIN2 respectively. The output node NOUT of the boost converter 200 can be used to output an output potential VOUT.

The bridge rectifier 210 includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The first diode D1 has an anode and a cathode, wherein the anode of the first diode D1 is coupled to the first input node NIN1, and the cathode of the first diode D1 is coupled to a first node N1 To output the rectified potential VR. The second diode D2 has an anode and a cathode, wherein the anode of the second diode D2 is coupled to the second input node NIN2, and the cathode of the second diode D2 is coupled to the first node N1. The third diode D3 has an anode and a cathode, wherein the anode of the third diode D3 is coupled to a ground potential VSS, and the cathode of the third diode D3 is coupled to the first input node NIN1. The fourth diode D4 has an anode and a cathode, wherein the anode of the fourth diode D4 is coupled to the ground potential VSS, and the cathode of the fourth diode D4 is coupled to the second input node NIN2.

The boost inductor LU has a first terminal and a second terminal, wherein the first terminal of the boost inductor LU is coupled to the first node N1 to receive the rectified potential VR, and the second terminal of the boost inductor LU is coupled to a second node N2. In some embodiments, an inductor current IL flows through the boost inductor LU, which will be described in detail later.

The power switch 220 includes a switching transistor MS. For example, the switching transistor MS may be an N-type Metal-Oxide-Semiconductor Field-Effect Transistor (NMOSFET). The switching transistor MS has a control terminal (for example: a gate), a first terminal (for example: a source), and a second terminal (for example: a drain), wherein the control terminal of the switching transistor MS is For receiving a pulse width modulation potential VM, the first terminal of the switching transistor MS is coupled to the ground potential VSS, and the second terminal of the switching transistor MS is coupled to the second node N2.

The output stage circuit 230 includes a fifth diode D5 and an output capacitor CO. The fifth diode D5 has an anode and a cathode, wherein the anode of the fifth diode D5 is coupled to the second node N2, and the cathode of the fifth diode D5 is coupled to the output node NOUT. The output capacitor CO has a first terminal and a second terminal, wherein the first terminal of the output capacitor CO is coupled to the output node NOUT, and the second terminal of the output capacitor CO is coupled to the ground potential VSS.

The detection circuit 240 can monitor the rectification potential VR and generate a detection potential VD accordingly. The detection potential VD can be used to record relevant information of the rectification potential VR, such as: the root mean square value and an average value of the rectification potential VR. , or a peak, but it is not limited to this.

The microcontroller 250 can generate the aforementioned pulse width modulation potential VM. In detail, the microcontroller 250 includes a duty cycle control unit 252 and a switching frequency control unit 254, which can each be implemented by a hardware circuit or a software program. Generally speaking, by analyzing the detection potential VD, the microcontroller 250 can obtain relevant information about the rectified potential VR. In some embodiments, the duty cycle control unit 252 can determine the duty cycle D of the pulse width modulation potential VM according to the detection potential VD. In other embodiments, the switching frequency control unit 254 can determine the switching frequency (Switching Frequency) F of the pulse width modulation potential VM according to the detection potential VD.

Figure 3 shows a waveform diagram of the pulse width modulation potential VM of the boost converter 200 according to an embodiment of the present invention, in which the horizontal axis represents time and the vertical axis represents the potential level. As shown in Figure 3, the pulse width modulation potential VM includes a plurality of switching periods (Switching Periods) T, where each switching period T includes a high logic interval TN and a low logic interval TF. In some embodiments, some setting parameters regarding the pulse width modulation potential VM may be as described in the following equations (1) and (2):

……………………………………………… (1)

…………………………………………… (2) Where “F” represents the value of the switching frequency F, “D” represents the duty cycle, “T” represents the length of the switching period T, and “ TN" represents the length of the high logic interval TN.

It must be noted that based on the "boost inductor current differential formula", the boost inductor 200 can operate according to the following equation (3):

………………………………………… (3) “VR” represents the root mean square value of the rectifier potential VR, “LU” represents the inductance value of the boost inductor LU, and “ILMAX” represents the inductor current The maximum current value of IL, "D" represents the duty cycle D, and "T" represents the length of the switching period T.

In some embodiments, if the rectification potential VR suddenly decreases, the microcontroller 250 may operate in the following manner, thereby improving the conversion efficiency of the boost converter 200 .

If the rectification potential VR decreases to a small proportion (for example, less than 10%), the duty cycle control unit 252 of the microcontroller 250 will gradually increase the duty cycle D of the pulse width modulation potential VM. Therefore, the aforementioned boost inductor current differential formula (3) can be rebalanced.

If the rectification potential VR decreases to a moderate proportion (for example: 10% to 30%), the duty cycle control unit 252 of the microcontroller 250 will be able to maintain the duty cycle D of the pulse width modulation potential VM at a maximum feasible value. DMAX, and the switching frequency control unit 254 of the microcontroller 250 will gradually reduce the switching frequency F of the pulse width modulation potential VM. For example, the aforementioned maximum feasible value DMAX may be approximately 75%, but is not limited thereto. Therefore, the aforementioned boost inductor current differential formula (3) can be rebalanced.

If the rectifier potential VR drops by a large proportion (for example, more than 30%), the duty cycle control unit 252 of the microcontroller 250 will maintain the duty cycle D of the pulse width modulation potential VM at the maximum feasible value DMAX, At the same time, the switching frequency control unit 254 of the microcontroller 250 can maintain the switching frequency F of the pulse width modulation potential VM at a minimum feasible value FMIN, thereby maximizing the length of the switching period T. For example, the aforementioned minimum feasible value FMIN may be approximately 40kHz, but is not limited thereto. Therefore, the aforementioned boost inductor current differential formula (3) can be rebalanced.

Figure 4 shows a waveform diagram of the inductor current IL of the boost converter 200 according to an embodiment of the present invention, in which the horizontal axis represents time and the vertical axis represents the current value. According to the measurement results in Figure 4, if the rectification potential VR drops too much (for example, more than 50%), the maximum value of the inductor current IL will naturally change from a first peak value MAX1 (as shown by a first curve CC1) drops to a second peak value MAX2 (as shown in a second curve CC2). Therefore, the aforementioned boost inductor current differential formula (3) can eventually be rebalanced.

It must be noted that as long as the aforementioned boost inductor current differential formula (3) can be satisfied, the conversion efficiency of the boost converter 200 can be ensured to be maintained within an acceptable range. Therefore, even if the rectifier potential VR suddenly drops due to non-ideal environmental factors, the microcontroller 250 can still appropriately adjust the duty cycle D or/and the switching frequency F of the pulse width modulation potential VM to improve the boost converter. 200 overall operating performance.

The present invention proposes a novel boost converter that can automatically optimize the duty cycle or/and switching frequency of the corresponding pulse width modulation potential. According to the actual measurement results, using the boost converter designed as mentioned above can effectively improve the overall conversion efficiency, so it is very suitable for use in various devices.

It is worth noting that the above-mentioned potential, current, resistance value, inductance value, capacitance value, and other component parameters are not limiting conditions of the present invention. Designers can adjust these settings according to different needs. The boost converter of the present invention is not limited to the state shown in Figures 1-4. The present invention may only include any one or multiple features of any one or multiple embodiments of Figures 1-4. In other words, not all features shown in the figures need to be implemented in the boost converter of the present invention at the same time. Although the embodiment of the present invention uses a metal oxide semi-field effect transistor as an example, the present invention is not limited thereto. Those skilled in the art can use other types of transistors, such as junction field effect transistors or fins. type field effect transistor, etc., without affecting the effect of the present invention.

The ordinal numbers in this specification and the scope of the patent application, such as "first", "second", "third", etc., have no sequential relationship with each other. They are only used to distinguish two items with the same Different components with names.

Although the present invention is disclosed above in terms of preferred embodiments, they are not intended to limit the scope of the present invention. Anyone skilled in the art can make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the appended patent application scope.

100,200:Boost converter

110,210: Bridge rectifier

120,220:Power switcher

130,230: Output stage circuit

140,240: Detection circuit

150,250:Microcontroller

152,252: Responsibility cycle control unit

254: Switching frequency control unit

CC1: first curve

CC2: Second curve

CO: output capacitor

D: Responsibility cycle

D1: first diode

D2: Second diode

D3: The third diode

D4: The fourth diode

D5: The fifth diode

DMAX: Maximum feasible value

F: switching frequency

FMIN: minimum feasible value

IL: inductor current

LU: Boost inductor

MAX1: first peak

MAX2: second peak

MS: switching transistor

N1: first node

N2: second node

NIN1: first input node

NIN2: second input node

NOUT: output node

T: switching cycle

TF: low logic range

TN: high logic interval

VD: detection potential

VIN1: first input potential

VIN2: second input potential

VM: pulse width modulation potential

VOUT: output potential

VR: rectifier potential

VSS: ground potential

Figure 1 is a schematic diagram of a boost converter according to an embodiment of the present invention. Figure 2 is a circuit diagram showing a boost converter according to an embodiment of the present invention. Figure 3 is a waveform diagram showing a pulse width modulation potential of a boost converter according to an embodiment of the present invention. FIG. 4 is a waveform diagram showing the inductor current of the boost converter according to an embodiment of the present invention.

100:Boost converter

110: Bridge rectifier

120:Power switcher

130:Output stage circuit

140:Detection circuit

150:Microcontroller

152: Responsibility cycle control unit

D: Responsibility cycle

LU: Boost inductor

VD: detection potential

VIN1: first input potential

VIN2: second input potential

VM: pulse width modulation potential

VOUT: output potential

VR: rectifier potential

VSS: ground potential

Claims (9)

A boost converter with high conversion efficiency includes: a bridge rectifier, which generates a rectified potential according to a first input potential and a second input potential; a boost inductor, which receives the rectified potential; a power switch, The boost inductor is selectively coupled to a ground potential according to a pulse width modulation potential; an output stage circuit is coupled to the boost inductor and generates an output potential; a detection circuit , monitor the rectified potential and generate a detection potential; and a microcontroller, generate the pulse width modulation potential, and include a duty cycle control unit; wherein the duty cycle control unit is based on the detection potential. Determine the duty cycle of the pulse width modulation potential; if the rectification potential drops by a small proportion, the microcontroller will gradually increase the duty cycle of the pulse width modulation potential. The boost converter of claim 1, wherein the microcontroller further includes a switching frequency control unit, and the switching frequency control unit determines the switching frequency of the pulse width modulation potential based on the detection potential. For example, in the boost converter of claim 2, if the rectified potential drops to a medium ratio, the microcontroller will maintain the duty cycle of the pulse width modulation potential at a maximum feasible value, and gradually reduce the The switching frequency of the pulse width modulation potential. For the boost converter of claim 2, if the rectified potential drops by a large proportion, the microcontroller will maintain the duty cycle of the pulse width modulation potential at a maximum feasible value while maintaining the The switching frequency of the pulse width modulation potential is at a minimum feasible value. For example, in the boost converter of claim 4, the maximum feasible value is approximately 75%, and the minimum feasible value is approximately 40kHz. The boost converter of claim 1, wherein the bridge rectifier includes: a first diode having an anode and a cathode, wherein the anode of the first diode is coupled to a first input node to receive the first input potential, and the cathode of the first diode is coupled to a first node to output the rectified potential; a second diode has an anode and a cathode, wherein the second The anode of the diode is coupled to a second input node to receive the second input potential, and the cathode of the second diode is coupled to the first node; a third diode has an anode and a cathode, wherein the anode of the third diode is coupled to a ground potential and the cathode of the third diode is coupled to the first input node; and a fourth diode A body having an anode and a cathode, wherein the anode of the fourth diode is coupled to the ground potential, and the cathode of the fourth diode is coupled to the second input node. The boost converter of claim 6, wherein the boost inductor has a first terminal and a second terminal, and the first terminal of the boost inductor is coupled to the first node. point to receive the rectified potential, and the second terminal of the boost inductor is coupled to a second node. The boost converter of claim 7, wherein the power switch includes: a switching transistor having a control terminal, a first terminal, and a second terminal, wherein the control terminal of the switching transistor is used for Receiving the pulse width modulation potential, the first terminal of the switching transistor is coupled to the ground potential, and the second terminal of the switching transistor is coupled to the second node. The boost converter of claim 7, wherein the output stage circuit includes: a fifth diode having an anode and a cathode, wherein the anode of the fifth diode is coupled to the second node, The cathode of the fifth diode is coupled to an output node to output the output potential; and an output capacitor has a first terminal and a second terminal, wherein the first terminal of the output capacitor is coupled is connected to the output node, and the second terminal of the output capacitor is coupled to the ground potential.

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