TWI784810B - Boost power conversion device - Google Patents

Abstract

A boost power conversion device provided. The boost power conversion device includes a first boost inductor, a second boost inductor, a first synchronous rectification switch, a second synchronous rectification switch, a first power switch, a second power switch, and an output capacitor. The first boost inductor, the first synchronous rectification switch, the first power switch and the output capacitor are formed a first boost circuit. The second boost inductor, the second s synchronous rectification switch, the second power switch and the output capacitor are formed a second boost circuit. The first boost circuit and the second boost circuit are controlled to adopt an alternately switching operation to provide output power, thereby reducing an output ripple current fluctuation and preventing the occurrence of large inrush currents of the boost power conversion device.

Description

Boost Power Converter

The present invention relates to a step-up power conversion device, and more particularly to a step-up power conversion device with low ripple current fluctuation.

Generally speaking, under the condition of high power of the boost converter, the output current of the boost converter is also large, and the output ripple (ripple) current of the boost converter is also large. Therefore, in design, the boost converter utilizes a plurality of output capacitors coupled in parallel with each other to suppress the fluctuation of the output ripple current. However, multiple output capacitors will increase the difficulty in the design of the output circuit and feedback compensation, and will also cause a large inrush current due to excessive capacitance at the moment of power-on, and even cause risks such as blown fuses. Therefore, the boost converter must be designed with a limited output capacitor to suppress the fluctuation of the output ripple current, so as to prevent the occurrence of large inrush current.

The present invention provides a novel step-up power conversion device with low ripple current fluctuation.

The boost power conversion device of the present invention includes a first boost inductor, a second boost inductor, a first synchronous rectification switch, a second synchronous rectification switch, a first power switch, a second power switch, an output capacitor and a control circuit. A first end of the first boost inductor and a first end of the second boost inductor receive rectified power. The first synchronous rectification switch is coupled between the second end of the first boost inductor and the device output end of the boost power conversion device. The second synchronous rectification switch is coupled between the second end of the second boost inductor and the output end of the device. The first power switch is coupled between the second end of the first boost inductor and the ground end. The second power switch is coupled between the second end of the second boost inductor and the ground end. The output capacitor is coupled between the device output terminal and the ground terminal. The control circuit is coupled to the control terminal of the first synchronous rectification switch, the control terminal of the second synchronous rectification switch, the control terminal of the first power switch, and the control terminal of the second power switch. The control circuit performs alternate switching operations on the first power switch and the second power switch. When the first power switch is turned on, the control circuit turns off the first synchronous rectification switch according to a first sensed value associated with power flowing through the first power switch. When the second power switch is turned on, the control circuit turns off the second synchronous rectification switch according to the second sensed value associated with the power flowing through the second power switch.

Based on the above, the control circuit performs alternate switching operations on the first power switch and the second power switch. The control circuit controls the first synchronous rectification switch and the second synchronous rectification switch according to the first sensing value and the second sensing value. Therefore, the present invention realizes a boost type power conversion device having two boost circuits with alternate switching operations. Based on the above two boost circuits, the control circuit turns off the first synchronous rectification switch according to the power associated with the first power switch. When the second power switch is turned on, the control circuit turns off the second synchronous rectification switch according to the power associated with the second power switch. Therefore, the present invention realizes a step-up power conversion device with automatic synchronous rectification function. In addition, each booster circuit is controlled to take turns switching to provide output power and jointly generate output current at the output terminal. Under the same output current requirement, the fluctuation of the output ripple current of the step-up power conversion device can be greatly reduced. In this way, the capacitance of the output capacitor does not need to be increased to suppress the fluctuation of the output ripple current. In addition, the step-up power conversion device also prevents a large inrush current from occurring without the capacitance of the output capacitor needing to be increased.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail together with the accompanying drawings.

Parts of the embodiments of the present invention will be described in detail with reference to the accompanying drawings. For the referenced reference symbols in the following description, when the same reference symbols appear in different drawings, they will be regarded as the same or similar components. These embodiments are only a part of the present invention, and do not reveal all possible implementation modes of the present invention. Rather, these embodiments are only examples within the scope of the patent application of the present invention.

Please refer to FIG. 1 . FIG. 1 is a schematic diagram of a step-up power conversion device according to an embodiment of the present invention. In this embodiment, the boost power conversion device 100 includes boost inductors LM1 , LM2 , synchronous rectification switches SR1 , SR2 , power switches Q1 , Q2 , a control circuit 110 and an output capacitor CO. The first end of the boost inductor LM1 receives the rectified power VR. The first terminal of the boost inductor LM2 receives the rectified power supply VR. The synchronous rectification switch SR1 is coupled between the second terminal of the boost inductor LM1 and the device output terminal of the boost power conversion device 100 . The output terminal of the device is used to output the output power VO. The synchronous rectification switch SR2 is coupled between the second terminal of the boost inductor LM2 and the output terminal of the device. The power switch Q1 is coupled between the second terminal of the boost inductor LM1 and the ground terminal GND. The power switch Q2 is coupled between the second terminal of the boost inductor LM2 and the ground terminal GND. The output capacitor CO is coupled between the device output terminal and the ground terminal GND.

In this embodiment, the combination of the boost inductor LM1, the synchronous rectification switch SR1, the power switch Q1 and the output capacitor CO can be represented as a first boost circuit BC1. The combination of boost inductor LM2, synchronous rectification switch SR2, power switch Q2 and output capacitor CO can be represented as a second boost circuit BC2.

In this embodiment, the control circuit 110 is coupled to the control terminal of the synchronous rectification switch SR1 , the control terminal of the synchronous rectification switch SR2 , the control terminal of the power switch Q1 , and the control terminal of the power switch Q2 . The control circuit 110 performs alternate switching operations on the power switches Q1 and Q2. When the power switch Q1 is turned on, the control circuit 110 turns off the synchronous rectification switch SR1 according to the first sensed value V1 associated with the power flowing through the power switch Q1 . When the power switch Q2 is turned on, the control circuit 110 turns off the synchronous rectification switch SR2 according to the second sensed value V2 associated with the power flowing through the power switch Q2. In this way, this embodiment implements two boost circuits with alternate switching operation and automatic synchronous rectification function.

Please refer to FIG. 1 and FIG. 2 at the same time. FIG. 2 is a state timing diagram of a synchronous rectification switch and a power switch according to an embodiment of the present invention. In this embodiment, the control circuit 110 provides the control signal GD1 to the control terminal of the power switch Q1, and provides the control signal GD2 to the control terminal of the power switch Q2. The power flowing through the power switch Q1 is positively correlated with the first sensing value V1. The power flowing through the power switch Q2 is positively correlated with the second sensed value V2. The control circuit 110 judges the first sensing value V1 and the second sensing value V2.

In this embodiment, the control circuit 110 provides the control signal GD1 with a high voltage level during the time intervals T1 and T3. The power switch Q1 is turned on in response to the control signal GD1 having a high voltage level during the time intervals T1 and T3 . Therefore, power will flow through the power switch Q1. The first sensing value V1 is increased. When the first sensing value V1 is determined to be greater than the reference value, the control circuit 110 provides a low voltage level control signal VSR1 to turn off the first synchronous rectification switch SR1 during the time intervals T1 and T3. Therefore, the first boost circuit BC1 does not supply power during the time intervals T1 and T3.

The control circuit 110 provides the control signal GD2 with a low voltage level during the time intervals T1 and T3. The power switch Q2 is turned off during the time interval T1, T3. No power flows through power switch Q2. Therefore, the second sensing value V2 is decreased to be less than or equal to the reference value. The control circuit 110 provides a high voltage level control signal VSR2 to turn on the synchronous rectification switch SR2 during the time intervals T1 and T3. The second boost circuit BC2 supplies power during the time intervals T1, T3.

In this embodiment, the control circuit 110 provides the control signal GD1 with a low voltage level during the time intervals T2 and T4. The power switch Q1 is turned off during the time interval T2, T4. No power flows through power switch Q1. The first sensing value V1 drops to be less than or equal to the reference value. Therefore, the control circuit 110 turns on the synchronous rectification switch SR1 during the time intervals T2 and T4. The first boost circuit BC1 supplies power during time intervals T2 and T4.

The control circuit 110 provides the control signal GD2 with a high voltage level during the time intervals T2 and T4. The power switch Q2 is turned on during the time intervals T2 and T4. Power flows through power switch Q2. Therefore, the second sensing value V2 will be increased. When the second sensing value V2 is determined to be greater than the reference value, the control circuit 110 turns off the synchronous rectification switch SR2 during the time intervals T2 and T4. Therefore, the second boost circuit BC2 does not supply power during the time intervals T2 and T4.

In this embodiment, in order to avoid simultaneous conduction of the synchronous rectification switches SR1 and SR2, a dead time length is designed between two adjacent time intervals in the time interval T1-T4. For example, the high voltage level control signals GD1 , GD2 , VSR1 , VSR2 are delayed based on the length of the dead time.

In this embodiment, the first booster circuit BC1 and the second booster circuit BC2 are alternately switched to jointly generate a desired output current at the output terminal. The first boost circuit BC1 provides a first output power. The second boost circuit BC2 will provide the second output power. The first output power and the second output power jointly generate a desired output current. The expected output current is substantially the sum of the current of the first output power supply and the current of the second output power supply.

It should be noted that, based on the alternate switching operation, the fluctuation of the output ripple current generated by the first boost circuit BC1 is different from the fluctuation of the output ripple current generated by the second boost circuit BC2 . Further, the fluctuation of the first output ripple current generated by the first boost circuit BC1 is substantially opposite to the fluctuation of the second output ripple current generated by the second boost circuit BC2 . The sum of the fluctuation of the first output ripple current and the fluctuation of the second output ripple current will reduce the fluctuation of the output ripple current at the output terminal. The fluctuation of the output ripple current at the output is greatly reduced to about 50%. Therefore, under the same expected output current demand, the aforementioned alternate switching operation will reduce the fluctuation of the output ripple current. In this way, the capacitance of the output capacitor CO does not need to be increased to suppress the fluctuation of the output ripple current. In addition, the step-up power conversion device 100 also prevents a large inrush current from occurring when the output capacitor CO does not need to be increased.

Please return to the embodiment shown in FIG. 1 , in this embodiment, the step-up power conversion device 100 further includes a rectifier circuit BR. The rectifier circuit BR is coupled to the first end of the boost inductor LM1 and the first end of the boost inductor LM2. The rectification circuit BR receives an input power VIN, and performs a rectification operation on the input power VIN to generate a rectified power VR. The rectification circuit BR provides the rectified power VR to the first end of the boost inductor LM1 and the first end of the boost inductor LM2.

In this embodiment, the step-up power conversion device 100 is suitable for high-frequency alternate switching operation. The frequency of the toggle operation is between 150 kilohertz (kHz) and 250 kHz. That is to say, the frequencies of the control signals GD1 and GD2 are between 150 kHz and 250 kHz.

Please refer to FIG. 3 . FIG. 3 is a schematic circuit diagram of a step-up power conversion device according to a first embodiment of the present invention. In this embodiment, the boost power conversion device 200 includes a rectifier circuit BR, boost inductors LM1, LM2, synchronous rectification switches SR1, SR2, power switches Q1, Q2, a control circuit 210 and an output capacitor CO. The coupling mode among rectifier circuit BR, boost inductors LM1, LM2, synchronous rectification switches SR1, SR2, power switches Q1, Q2 and output capacitor CO has been fully described in the embodiment of FIG. 1, so it will not be repeated stated. In this embodiment, the control circuit 210 includes a controller 211 , sensing circuits 212_1 , 212_2 and comparators CP1 , CP2 .

In this embodiment, the controller 211 is coupled to the control terminal of the power switch Q1 and the control terminal of the power switch Q2 . The controller 211 provides the control signal GD1 to the control terminal of the power switch Q1, and provides the control signal GD2 to the control terminal of the power switch Q1. Based on the control signals GD1 , GD2 , the power switches Q1 , Q2 are turned on in different time intervals.

In this embodiment, the sensing circuit 212_1 is coupled between the second end of the boost inductor LM1 and the first end of the power switch Q1. The sensing circuit 212_1 converts the power flowing through the power switch Q1 into a first sensing value V1. The sensing circuit 212_2 is coupled between the second end of the boost inductor LM2 and the first end of the power switch Q2. The sensing circuit 212_2 converts the power flowing through the power switch Q2 into a second sensing value V2.

In this embodiment, the sensing circuit 212_1 includes a transformer TR1 , a diode DX1 , a resistor RX1 and a capacitor CX1 . Transformer TR1 includes windings N1, N2. The winding N1 is coupled between the second end of the boost inductor LM1 and the first end of the power switch Q1. The first terminal of the winding N2 is coupled to the ground terminal GND. The anode of the diode DX1 is coupled to the second end of the winding N2. The cathode of the diode DX1 serves as a sensing output terminal for outputting the first sensing value V1. The resistor RX1 is coupled between the cathode of the diode DX1 and the ground terminal GND. The capacitor CX1 is coupled between the cathode of the diode DX1 and the ground terminal GND. In other words, the capacitor CX1 and the resistor RX1 are coupled in parallel with each other. The sensing circuit 212_1 couples the power flowing through the power switch Q1 to the resistor RX1 through the transformer TR1, and defines a voltage value associated with the power flowing through the power switch Q1 through the resistor RX1, that is, the first sensing value V1 . In addition, capacitor CX1 is used as a voltage stabilizing element. The sensing circuit 212_1 also stabilizes the first sensing value V1 through the capacitor CX1.

In this embodiment, the sensing circuit 212_2 includes a transformer TR2, a diode DX2, a resistor RX2 and a capacitor CX2. Transformer TR2 includes windings N3, N4. The winding N3 is coupled between the second terminal of the boost inductor LM2 and the first terminal of the power switch Q2. The first terminal of the winding N4 is coupled to the ground terminal GND. The anode of the diode DX2 is coupled to the second end of the winding N4. The cathode of the diode DX2 serves as a sensing output terminal for outputting the second sensing value V2. The resistor RX2 is coupled between the cathode of the diode DX2 and the ground terminal GND. The capacitor CX2 is coupled between the cathode of the diode DX2 and the ground terminal GND. In other words, the capacitor CX2 and the resistor RX2 are coupled in parallel with each other. The sensing circuit 212_2 couples the power flowing through the power switch Q2 to the resistor RX2 through the transformer TR2, and defines a voltage value associated with the power flowing through the power switch Q2 through the resistor RX2, that is, the second sensing value V2 . In addition, capacitor CX2 is used as a voltage stabilizing element. The sensing circuit 212_2 also stabilizes the second sensing value V2 through the capacitor CX2.

In this embodiment, the comparator CP1 is coupled to the sensing circuit 212_1 , the controller 211 and the control terminal of the synchronous rectification switch SR1 . The comparator CP1 receives the first sensing value V1 provided by the sensing circuit 212_1 and the reference value VREF provided by the controller 211 . The comparator CP1 compares the first sensing value V1 with the reference value VREF. When the first sensing value V1 is greater than the reference value VREF, the comparator CP1 turns off the synchronous rectification switch SR1. On the other hand, when the first sensing value V1 is less than or equal to the reference value VREF, the comparator CP1 turns on the synchronous rectification switch SR1.

The inverting input terminal of the comparator CP1 is coupled to the sensing circuit 212_1 . The inverting input terminal of the comparator CP1 receives the first sensing value V1. The non-inverting input terminal of the comparator CP1 is coupled to the controller 211 . The non-inverting input of comparator CP1 receives reference value VREF. The output terminal of the comparator CP1 is coupled to the control terminal of the synchronous rectification switch SR1. When the first sensing value V1 is greater than the reference value VREF, the comparator CP1 provides the control signal VSR1 with a low voltage level. Therefore, the synchronous rectification switch SR1 is turned off in response to the control signal VSR1 of the low voltage level. On the other hand, when the first sensing value V1 is less than or equal to the reference value VREF, the comparator CP1 provides the control signal VSR1 with a high voltage level. Therefore, the synchronous rectification switch SR1 is turned on in response to the control signal VSR1 of the high voltage level.

In this embodiment, the comparator CP2 is coupled to the sensing circuit 212_2 , the controller 211 and the control terminal of the synchronous rectification switch SR2 . The comparator CP2 receives the second sensing value V2 provided by the sensing circuit 212_2 and the reference value VREF provided by the controller 211 . The comparator CP2 compares the second sensing value V2 with the reference value VREF. When the second sensing value V2 is greater than the reference value VREF, the comparator CP2 turns off the synchronous rectification switch SR2. On the other hand, when the second sensing value V2 is less than or equal to the reference value VREF, the comparator CP2 turns on the synchronous rectification switch SR2.

The inverting input terminal of the comparator CP2 is coupled to the sensing circuit 212_2 . The inverting input terminal of the comparator CP2 receives the second sensed value V2. The non-inverting input terminal of the comparator CP2 is coupled to the controller 211 . The non-inverting input of comparator CP2 receives reference value VREF. The output terminal of the comparator CP2 is coupled to the control terminal of the synchronous rectification switch SR2. When the second sensing value V2 is greater than the reference value VREF, the comparator CP2 provides the control signal VSR2 with a low voltage level. Therefore, the synchronous rectification switch SR2 is turned off in response to the control signal VSR2 of the low voltage level. On the other hand, when the second sensing value V2 is less than or equal to the reference value VREF, the comparator CP2 provides the control signal VSR2 with a high voltage level. Therefore, the synchronous rectification switch SR2 is turned on in response to the control signal VSR2 of the high voltage level.

It should be noted that the control signals VSR1 and VSR2 are not generated by the controller 211 . The control signal VSR1 is generated by the comparator CP1 according to the comparison result between the first sensing value V1 and the reference value VREF. The control signal VSR2 is generated by the comparator CP2 according to the comparison result between the second sensing value V2 and the reference value VREF. Therefore, the controller 211 does not need to additionally provide the control signals VSR1 and VSR2. In this embodiment, a step-up power conversion device 200 with an automatic synchronous rectification function is implemented.

Please refer to FIG. 4 . FIG. 4 is a schematic circuit diagram of a step-up power conversion device according to a second embodiment of the present invention. Different from FIG. 3 , the step-up power conversion device 300 of this embodiment further includes discharge resistors RD1 and RD2 . In this embodiment, the first end of the discharge resistor RD1 is coupled to the first end of the power switch Q1. The second terminal of the discharge resistor RD1 is coupled to the second terminal of the power switch Q1 and the ground terminal GND. The discharge resistor RD1 discharges the energy stored in the parasitic capacitor C1 located between the first terminal of the power switch Q1 and the second terminal of the power switch Q1 . Similarly, the first end of the discharge resistor RD2 is coupled to the first end of the power switch Q2. The second terminal of the discharge resistor RD2 is coupled to the second terminal of the power switch Q2 and the ground terminal GND. The discharge resistor RD2 discharges the energy stored in the parasitic capacitor C2 between the first terminal of the power switch Q2 and the second terminal of the power switch Q2.

In this embodiment, the step-up power conversion device 300 can operate at a high frequency between 150 kHz and 250 kHz. That is to say, the power switches Q1, Q2 and the synchronous rectification switches SR1, SR2 perform high-frequency switching operations. The power switches Q1, Q2 are designed as components with high voltage tolerance. The power switch Q1 has a large parasitic capacitance C1. The power switch Q2 has a large parasitic capacitance C2. Therefore, in the case of high-frequency switching operation, the discharge resistors RD1, RD2 discharge the energy stored in the parasitic capacitances C1, C2, respectively.

In summary, the control circuit of the present invention performs alternate switching operations on the first power switch and the second power switch. The control circuit controls the first synchronous rectification switch and the second synchronous rectification switch according to the first sensing value and the second sensing value. Therefore, the step-up power conversion device of the present invention has a first boost circuit and a second boost circuit that operate alternately. The first boost circuit and the second boost circuit provide output power and jointly generate a desired output current at the output terminal. Under the same expected output current demand, the aforementioned alternate switching operation will greatly reduce the fluctuation of the output ripple current. In this way, the capacitance of the output capacitor does not need to be increased to suppress the fluctuation of the output ripple current. In addition, the step-up power conversion device also prevents a large inrush current from occurring without the capacitance of the output capacitor needing to be increased. In addition, the invention also realizes a step-up power conversion device with automatic synchronous rectification function.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention should be defined by the scope of the appended patent application.

100, 200, 300: step-up power conversion device 110, 210: control circuit 211: Controller 212_1, 212_2: sensing circuit BC1: the first boost circuit BC2: The second boost circuit BR: rectifier circuit C1, C2: Parasitic capacitance CO: output capacitor CP1, CP2: Comparator CX1, CX2: Capacitors DX1, DX2: Diode GD1, GD2, VSR1, VSR2: control signal GND: ground terminal LM1, LM2: boost inductor N1~N4: winding Q1, Q2: Power switch RD1, RD2: discharge resistors RX1, RX2: resistors SR1, SR2: Synchronous rectification switch t: time T1~T4: time interval TR1, TR2: Transformer V1: first sensing value V2: Second sensing value VIN: input power VO: output power VR: rectified power supply VREF: reference value

FIG. 1 is a schematic diagram of a step-up power conversion device according to an embodiment of the present invention. FIG. 2 is a timing diagram of states of a synchronous rectification switch and a power switch according to an embodiment of the present invention. FIG. 3 is a schematic circuit diagram of a step-up power conversion device according to a first embodiment of the present invention. FIG. 4 is a schematic circuit diagram of a step-up power conversion device according to a second embodiment of the present invention.

100: Step-up power conversion device

110: control circuit

BC1: the first boost circuit

BC2: The second boost circuit

BR: rectifier circuit

CO: output capacitor

GD1, GD2, VSR1, VSR2: control signal

GND: ground terminal

LM1, LM2: boost inductor

Q1, Q2: Power switch

SR1, SR2: Synchronous rectification switch

V1: first sensing value

V2: Second sensing value

VIN: input power

VO: output power

VR: rectified power supply

Claims (10)

A step-up power conversion device, comprising: a first boost inductor and a second boost inductor, the first end of the first boost inductor and the first end of the second boost inductor receive a rectified power supply; a first synchronous rectification switch coupled between the second end of the first boost inductor and a device output end of the boost power conversion device; a second synchronous rectification switch coupled between the second terminal of the second boost inductor and the output terminal of the device; a first power switch coupled between the second terminal of the first boost inductor and a ground terminal; a second power switch coupled between the second terminal of the second boost inductor and the ground terminal; an output capacitor coupled between the device output and the ground; and A control circuit, coupled to the control terminal of the first synchronous rectification switch, the control terminal of the second synchronous rectification switch, the control terminal of the first power switch, and the control terminal of the second power switch, is configured to: performing an alternate switching operation on the first power switch and the second power switch, turning off the first synchronous rectification switch according to a first sensed value associated with power flowing through the first power switch when the first power switch is turned on, and When the second power switch is turned on, the second synchronous rectification switch is turned off according to a second sensed value associated with power flowing through the second power switch. The step-up power conversion device as described in claim 1, wherein: The power flowing through the first power switch is positively correlated with the first sensed value, and The power flowing through the second power switch is positively correlated with the second sensing value. The step-up power conversion device as described in claim 1, wherein: The control circuit judges the first sensing value and the second sensing value, When the first sensing value is greater than a reference value, the control circuit turns off the first synchronous rectification switch, and When the second sensing value is greater than the reference value, the control circuit turns off the second synchronous rectification switch. The step-up power conversion device as claimed in item 1, wherein the control circuit includes: a controller, coupled to the control terminal of the first power switch and the control terminal of the second power switch, configured to provide a first control signal to the control terminal of the first power switch, and a second control signal The signal is provided to the control terminal of the second power switch, so that the first power switch and the second power switch are turned on in different time intervals. The step-up power conversion device as described in claim 4, wherein the control circuit further includes: A first sensing circuit, coupled between the second terminal of the first boost inductor and the first terminal of the first power switch, configured to convert power flowing through the first power switch into the a first sensed value; and A second sensing circuit, coupled between the second terminal of the second boost inductor and the first terminal of the second power switch, configured to convert power flowing through the second power switch into the the second sensed value. The step-up power conversion device as claimed in claim 5, wherein the first sensing circuit includes: A first transformer, comprising: a first winding coupled between the second terminal of the first boost inductor and the first terminal of the first power switch; and a second winding, the first end of the second winding is coupled to the ground end; A first diode, the anode of the first diode is coupled to the second end of the second winding, and the cathode of the first diode serves as a first sensor for outputting the first sense value Measure the output terminal; a first resistor coupled between the cathode of the first diode and the ground; and A first capacitor is coupled between the cathode of the first diode and the ground terminal. The step-up power conversion device as claimed in claim 6, wherein the second sensing circuit includes: a second transformer comprising: a third winding coupled between the second terminal of the third boost inductor and the first terminal of the second power switch; and a fourth winding, the first end of the fourth winding is coupled to the ground end; A second diode, the anode of the second diode is coupled to the second end of the fourth winding, and the cathode of the second diode serves as a second sensor for outputting the second sense value Measure the output terminal; a second resistor coupled between the cathode of the second diode and the ground; and A second capacitor is coupled between the cathode of the second diode and the ground terminal. The step-up power conversion device as described in claim item 5, wherein: The controller also provides a reference value, and The control circuit also includes: A first comparator, coupled to the first sensing circuit, the controller and the control terminal of the first synchronous rectification switch, configured to receive the first sensing value and the reference value, when the first sensing When the measured value is greater than the reference value, turn off the first synchronous rectification switch, and when the first sensed value is less than or equal to the reference value, turn on the first synchronous rectification switch; and a second comparator, coupled to the second sensing circuit, the controller and the control terminal of the second synchronous rectification switch, configured to receive the second sensing value and the reference value, when the second sensing When the measured value is greater than the reference value, the first synchronous rectification switch is turned off, and when the second sensed value is less than or equal to the reference value, the second synchronous rectification switch is turned on. The step-up power conversion device as claimed in claim 1, wherein the frequency of the alternate switching operation is between 150 kHz and 250 kHz. The step-up power conversion device as described in claim 1, further comprising: A first discharge resistor, the first end of the first discharge resistor is coupled to the first end of the first power switch, the second end of the first discharge resistor is coupled to the first end of the first power switch two terminals and the ground terminal configured to discharge energy stored in a parasitic capacitance between the first terminal of the first power switch and the second terminal of the first power switch; and A second discharge resistor, the first terminal of the second discharge resistor is coupled to the first terminal of the second power switch, the second terminal of the second discharge resistor is coupled to the first terminal of the second power switch The two terminals and the ground terminal are configured to discharge the energy stored in the parasitic capacitance between the first terminal of the second power switch and the second terminal of the second power switch.

Images