Power conversion device and pre-charge method thereof

Abstract

The present application provides a power conversion device and a pre-charge method thereof. The power conversion device includes a power converter, a sensing circuit, and a pre-charge circuit. The power converter includes a flying capacitor. The sensing circuit senses a terminal voltage difference of the flying capacitor to generate a sensing result. The pre-charge circuit pre-charges the flying capacitor during a power-on transient of the power conversion device. The pre-charge circuit stops the pre-charge of the flying capacitor based on the sensing result. The power converter converts a first direct current voltage to a second direct current voltage for a load circuit during a normal operation after the power-on transient.

Description

Technical Field

[0001] This invention relates to a power supply device, and more particularly to a power conversion device and its pre-charging method. Background Technology

[0002] Almost all electrical infrastructure (such as consumer electronics, charging stations, AI servers, and automotive electronics) relies on power conversion devices. At the moment of startup, critical components of these power conversion devices (such as power switches) are typically subjected to significant voltage (or current) stress. Excessive voltage (or current) stress can damage these critical components. Summary of the Invention

[0003] The present invention provides a power conversion device and a pre-charging method thereof to avoid electrical stress damage to the power converter during the power-on instant.

[0004] In an embodiment of the present invention, the power conversion device includes a power converter, a sensing circuit, and a pre-charging circuit. The power converter converts a first DC voltage to a second DC voltage, and includes a first flying capacitor. The sensing circuit is coupled to the first flying capacitor of the power converter. The sensing circuit senses the voltage difference across the first flying capacitor to generate a sensing result. The pre-charging circuit is coupled to the first flying capacitor of the power converter to pre-charge the first flying capacitor during the power-on instant of the power conversion device. The pre-charging circuit is coupled to the sensing circuit to receive the sensing result. The pre-charging circuit stops pre-charging the first flying capacitor based on the sensing result. During normal operation after the power-on instant, the power converter converts the first DC voltage to the second DC voltage for the load circuit.

[0005] In an embodiment of the present invention, the pre-charging method described above includes: pre-charging the first flying capacitor of the power converter of the power converter by the pre-charging circuit of the power converter during the power-on instant of the power converter; generating a sensing result by sensing the terminal voltage difference of the first flying capacitor by the sensing circuit of the power converter and sending it to the pre-charging circuit; stopping the pre-charging of the first flying capacitor of the power converter by the pre-charging circuit based on the sensing result; and converting the first DC voltage to the second DC voltage for the load circuit by the power converter during normal operation after the power-on instant.

[0006] In an embodiment of the present invention, the power conversion device described above includes a power converter, a sensing circuit, and a pre-charge circuit. The power converter converts an input voltage into an output voltage, and includes a flying capacitor. The sensing circuit is coupled to the flying capacitor and senses the voltage across the flying capacitor. The pre-charge circuit is coupled to the power converter. When the voltage across the flying capacitor is less than a reference voltage, the pre-charge circuit charges the flying capacitor.

[0007] Based on the above, the power conversion device described in the embodiments of the present invention pre-charges the flying capacitor of the power converter during the power-on instant to reduce the voltage stress caused at the moment of power startup. Therefore, the power conversion device can avoid electrical stress damage to the power converter.

[0008] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of a circuit block of an electrical facility according to an embodiment of the present invention;

[0010] Figure 2 This is a schematic flowchart of a pre-charging method for a power conversion device according to an embodiment of the present invention;

[0011] Figure 3 This is a schematic diagram of the voltage waveform of a power conversion device according to an embodiment of the present invention;

[0012] Figure 4 The circuit diagram of the power converter is shown according to an embodiment of the present invention.

[0013] Figure 5 The circuit diagram of the sensing circuit is shown according to an embodiment of the present invention.

[0014] Figure 6 This is a circuit diagram of a pre-charging circuit according to an embodiment of the present invention;

[0015] Figure 7 The circuit diagram of the sensing circuit and the pre-charging circuit is shown according to another embodiment of the present invention.

[0016] Figure 8 The circuit diagram of the power converter is shown according to another embodiment of the present invention;

[0017] Figure 9 This is a timing diagram of the upper switch signal and the lower switch signal according to an embodiment of the present invention;

[0018] Figure 10The circuit diagram of the power converter is shown according to another embodiment of the present invention.

[0019] Explanation of icon numbers

[0020] 100: Electrical facilities

[0021] 110: Power conversion device

[0022] 111, 115: Sensing circuit

[0023] 112, 116: Pre-charging circuit

[0024] 113: Power Converter

[0025] 114: Control Circuit

[0026] 120: Load circuit

[0027] 510, 710: Subtractors

[0028] 511: Error Amplifier

[0029] 520, 720: Comparators

[0030] 610: Switching circuit

[0031] 730: Logic Gates

[0032] C1, C2: Voltage

[0033] Cfly1, Cfly4, Cfly10: Flying Capacitors

[0034] Co4: Output capacitor

[0035] L4, L8: Inductors

[0036] P31: During the instantaneous power-on period

[0037] P32: During normal operation

[0038] R51, R52, R53, R54: Resistors

[0039] R61, R71: Current-limiting resistors

[0040] S210, S220, S230, S240: Steps

[0041] SW41, SW81, SW101: Upper power switches

[0042] SW42, SW82, SW102: Lower power switches

[0043] SW61, SW62, SW71: Pre-charge switches

[0044] T1, T10: Sensing Results

[0045] Vcfly, Vcfly10: Terminal voltage difference

[0046] Vin: Input voltage

[0047] Vout: Output voltage

[0048] Vref: Reference voltage

[0049] Vs4, Vs8: Upper switch signals

[0050] Vsr4, Vsr7, Vsr8: Lower switch signals Detailed Implementation

[0051] Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same element references are used in the drawings and description to denote the same or similar parts.

[0052] The term "coupled (or connected)" as used throughout this specification (including the claims) may refer to any direct or indirect connection means. For example, if the text describes a first device coupled (or connected) to a second device, it should be interpreted as the first device being directly connected to the second device, or the first device being indirectly connected to the second device through other devices or some connection means. The terms "first," "second," etc., used throughout this specification (including the claims) are used to name components or distinguish different embodiments or scopes, and are not intended to limit the upper or lower limit of the number of components, nor to limit the order of components. Furthermore, wherever possible, components / components / steps using the same reference numerals in the drawings and embodiments represent the same or similar parts. Components / components / steps using the same reference numerals or the same terms in different embodiments can be referred to mutually in the relevant descriptions. It should be understood that the features of the following embodiments can be combined with each other. For example, the features of the second embodiment can be combined with the features of the first embodiment. Those skilled in the art can select appropriate combinations of features according to actual design requirements.

[0053] System startup is typically accompanied by significant electrical stress (e.g., voltage stress, current stress), and excessive electrical stress can have a substantial impact on the power converter. The following embodiments address this issue through pre-charging. These different embodiments can effectively reduce the electrical stress caused during system startup.

[0054] Figure 1This is a circuit block diagram of an electrical facility 100 according to an embodiment of the present invention. Depending on the application, the electrical facility 100 may be a consumer electronics product, a charging station, an artificial intelligence (AI) server, automotive electronic equipment, or other facilities. In the electrical facility 100, a power conversion device 110 can convert an input voltage Vin (DC voltage) into an output voltage Vout (DC voltage) for the load circuit 120. Figure 1 In the illustrated embodiment, the power conversion device 110 includes a sensing circuit 111, a pre-charging circuit 112, a power converter 113, and a control circuit 114. The control circuit 114 controls the conversion operation of the power converter 113 during normal operation. Depending on the design, in some embodiments, the control circuit 114 may be implemented as hardware circuitry. In other embodiments, the control circuit 114 may be implemented as a combination of hardware, firmware, and software (i.e., programs).

[0055] In hardware terms, the control circuit 114 described above can be implemented as logic circuitry on an integrated circuit. For example, the functions of the control circuit 114 can be implemented in various logic blocks, modules, and circuits within one or more hardware controllers, microcontrollers, hardware processors, microprocessors, application-specific integrated circuits (ASICs), digital signal processors (DSPs), field-programmable gate arrays (FPGAs), central processing units (CPUs), and / or other processing units. The functions of the control circuit 114 can be implemented as hardware circuitry, such as various logic blocks, modules, and circuits within an integrated circuit, using hardware description languages ​​(e.g., Verilog HDL or VHDL) or other suitable programming languages.

[0056] In software and / or firmware form, the functions of the control circuit 114 described above can be implemented as programming codes. For example, the control circuit 114 can be implemented using general programming languages ​​(such as C, C++, or assembly language) or other suitable programming languages. The programming codes can be recorded / stored in a non-transitory machine-readable storage medium. In some embodiments, the non-transitory machine-readable storage medium includes, for example, semiconductor memory and / or a storage device. An electronic device (e.g., a computer, CPU, hardware controller, microcontroller, hardware processor, or microprocessor) can read and execute the programming codes from the non-transitory machine-readable storage medium to implement the functions of the control circuit 114.

[0057] Based on practical design and application, power converter 113 may include a DC-DC converter, such as a series capacitor buck converter, a symmetry series capacitor buck converter, or other DC-DC converters. The power converter includes a flying capacitor (Cfly1). Under the control of control circuit 114, power converter 113 converts the input voltage Vin into an output voltage Vout for the load circuit 120.

[0058] Figure 2 This is a schematic flowchart of a pre-charging method for a power conversion device according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the voltage waveform of the power conversion device 110 according to an embodiment of the present invention. Figure 3 The horizontal axis represents time. Please refer to... Figure 1 , Figure 2 and Figure 3The pre-charge circuit 112 is coupled to the flying capacitor Cfly1 of the power converter 113 to pre-charge the flying capacitor Cfly1 during the power-on instant P31 of the power conversion device 110 (step S210). For example, the power-on instant P31 is the period when the voltage across the flying capacitor Cfly1 is less than the reference voltage Vref. The level of the reference voltage Vref can be determined according to the actual design and application. For example (but not limited to), the level of the reference voltage Vref can be half the level of the input voltage Vin. Generally, during the power-off period before the power-on instant P31, the voltage across the flying capacitor Cfly1 is less than the reference voltage Vref. The sensing circuit 111 senses the voltage across the flying capacitor Cfly1, and when the voltage across the flying capacitor Cfly1 is less than the reference voltage Vref, the pre-charge circuit 112 charges the flying capacitor Cfly1. For example (but not limited to), based on the sensing result (the voltage across the flying capacitor Cfly1) of the sensing circuit 111, the control circuit 114 controls the pre-charge circuit 112 to charge the flying capacitor Cfly1. Based on the pre-charge operation of the pre-charge circuit 112, the voltage difference Vcfly across the flying capacitor Cfly1 is increased during the power-on instant.

[0059] Sensing circuit 111 is coupled to the flying capacitor Cfly1 of power converter 113. Sensing circuit 111 senses the voltage difference Vcfly across flying capacitor Cfly1 and generates a sensing result T1 (step S220). For example, sensing circuit 111 changes the level of sensing result T1 based on the relationship between the voltage difference Vcfly and the reference voltage Vref. Pre-charge circuit 112 is coupled to sensing circuit 111 to receive sensing result T1. Pre-charge circuit 112 stops pre-charging flying capacitor Cfly1 based on sensing result T1 (step S230). For example, when the voltage across flying capacitor Cfly1 is greater than the reference voltage Vref, sensing circuit 111 controls pre-charge circuit 112 to stop charging flying capacitor Cfly1.

[0060] Control circuit 114 is coupled to power converter 113 and sensing circuit 111. The sensing circuit provides a sensing result T1 to control circuit 114. Control circuit 114 determines the end of the power-on instantaneous period P31 based on the sensing result T1 from sensing circuit 111. After the power-on instantaneous period P31 ends, control circuit 114 enters the normal operation period P32 to control the conversion operation of power converter 113. Based on the control of control circuit 114, power converter 113 begins to convert the input voltage Vin to the output voltage Vout for load circuit 120 during normal operation period P32 (step S240). For example, when the voltage across the flying capacitor Cfly1 is equal to half of the input voltage Vin, control circuit 114 controls power converter 113 to convert the input voltage Vin to the output voltage Vout.

[0061] In summary, during the power-on instant, P31 of the power converter 110 pre-charges the flying capacitor Cfly1 of the power converter 113 to reduce the voltage stress caused by the instant of power startup. Specifically, before the control circuit 114 controls the power converter 113 to perform the conversion operation, the pre-charging circuit 112 pre-charges the flying capacitor Cfly1 of the power converter 113. The sensing circuit 111 detects the voltage difference (Vcfly) across the flying capacitor Cfly1. In response to a voltage difference Vcfly lower than the reference voltage Vref, the sensing circuit 111 outputs a sensing result T1 at a first level (e.g., a high potential, but not limited to this), causing the pre-charging circuit 112 to continuously pre-charge the flying capacitor Cfly1. In response to a voltage difference Vcfly higher than the reference voltage Vref, the sensing circuit 111 outputs a sensing result T1 at a second level (e.g., a low potential, but not limited to this). The sensing result T1 at the second level indicates that the pre-charging of the flying capacitor Cfly1 is complete, for example, the voltage difference Vcfly across the flying capacitor Cfly1 has reached the reference voltage Vref. After the voltage difference Vcfly reaches the reference voltage Vref, the control circuit 114 starts controlling the power converter 113 to perform the conversion operation of P32 during normal operation, causing the output voltage Vout to rise to the target voltage. The level of the target voltage Vout can be determined according to the actual design and application. Therefore, the power conversion device 110 can avoid electrical stress damage to the power converter 113.

[0062] Figure 4 The circuit diagram of power converter 113 is shown according to an embodiment of the present invention. Figure 4 The sensing circuit 111, pre-charging circuit 112, power converter 113, and load circuit 120 shown can be referenced. Figure 1 Related explanations. Figure 4 The power converter 113 shown can be used as Figure 1 This is one of many implementation examples of the power converter 113 shown. Figure 4 In the embodiment shown, the power converter 113 includes an upper power switch SW41, a flying capacitor Cfly4, a lower power switch SW42, an inductor L4, and an output capacitor Co4. Figure 4 The flying capacitor Cfly4 shown can be used as Figure 1 This is one of many implementation examples of the flying capacitor Cfly1. Figure 4 The flying capacitor Cfly4 shown can be referenced. Figure 1 The relevant explanations of the flying capacitor Cfly1 are shown, and analogies are drawn from them.

[0063] Please refer to Figure 1 and Figure 4The first terminal of the upper power switch SW41 receives the input voltage Vin. The second terminal of the upper power switch SW41 is coupled to the first terminal of the flying capacitor Cfly4. The first terminal of the lower power switch SW42 is coupled to the second terminal of the flying capacitor Cfly4. The second terminal of the lower power switch SW42 receives a reference voltage (e.g., ground voltage or other fixed voltage). The first terminal of the inductor L4 is coupled to the second terminal of the flying capacitor Cfly4. The second terminal of the inductor L4 is coupled to the output terminal of the power converter 113 (the output terminal of the power converter 113 provides the output voltage Vout to the load circuit 120). The first terminal of the output capacitor Co4 is coupled to the second terminal of the inductor L4. The second terminal of the output capacitor Co4 receives a reference voltage (e.g., ground voltage or other fixed voltage). The control terminal of the upper power switch SW41 is coupled to the control circuit 114 to receive the upper switch signal Vs4.

[0064] Sensing circuit 111 is coupled to the first terminal of flying capacitor Cfly4 to detect voltage C1. Sensing circuit 111 is coupled to the second terminal of flying capacitor Cfly4 to detect voltage C2. The voltage difference between voltage C1 and voltage C2 is the terminal voltage difference Vcfly of flying capacitor Cfly4. The control terminal of lower power switch SW42 is coupled to control circuit 114 to receive lower switching signal Vsr4. During normal operation P32, control circuit 114 can perform pulse-width modulation (PWM) control on upper power switch SW41 and lower power switch SW42 through upper switching signal Vs4 and lower switching signal Vsr4.

[0065] In summary, the pre-charge circuit 112 pre-charges the flying capacitor Cfly4 via P31 during the power-on instant to reduce the voltage stress on the upper power switch SW41 caused by the instantaneous input voltage Vin during power-on. Therefore, electrical stress damage to the upper power switch SW41 can be effectively avoided. The sensing circuit 111 detects the voltages C1 and C2 across the flying capacitor Cfly4 (i.e., the voltage difference Vcfly). In response to the voltage difference Vcfly being lower than the reference voltage Vref, the sensing circuit 111 notifies the pre-charge circuit 112 via the sensing result T1 to continue pre-charging the flying capacitor Cfly4. In response to the voltage difference Vcfly reaching the reference voltage Vref (representing that the pre-charging of the flying capacitor Cfly4 is complete), the sensing circuit 111 notifies the pre-charge circuit 112 via the sensing result T1 to stop the pre-charging of the flying capacitor Cfly1, and notifies the control circuit 114 to control the power converter 113 to begin the conversion operation of P32 during normal operation (converting the input voltage Vin to the output voltage Vout).

[0066] Figure 5 The circuit diagram of sensing circuit 111 is shown according to an embodiment of the present invention. Figure 5 The sensing circuit 111 shown can be referred to Figure 1 and Figure 4 Related explanations. Figure 5 The sensing circuit 111 shown can be used as Figure 1 and Figure 4 This is one of many implementation examples of the sensing circuit 111 shown. Figure 5 In the illustrated embodiment, the sensing circuit 111 includes a subtractor 510 and a comparator 520. The first and second input terminals of the subtractor 510 are respectively coupled to the first and second terminals of the flying capacitor Cfly4 of the power converter 113 to receive the voltage difference Vcfly (i.e., the voltage difference between voltages C1 and C2) at the terminals of the flying capacitor Cfly4. The first input terminal (e.g., the inverting input terminal) of the comparator 520 is coupled to the output terminal of the subtractor 510. The second input terminal (e.g., the non-inverting input terminal) of the comparator 520 receives a reference voltage Vref. The output terminal of the comparator 520 outputs the sensing result T1 to the pre-charge circuit 112.

[0067] exist Figure 5 In the illustrated embodiment, subtractor 510 includes resistors R51, R52, R53, and R54, and an error amplifier 511. A first terminal of resistor R51 is coupled to a first input terminal of subtractor 510 to receive voltage C1. A first terminal of resistor R53 is coupled to a second terminal of resistor R51. A first terminal of resistor R52 is coupled to a second input terminal of subtractor 510 to receive voltage C2. A first terminal of resistor R54 is coupled to a second terminal of resistor R52. The second terminal of resistor R54 receives a reference voltage (e.g., ground voltage or other fixed voltage). A first input terminal (e.g., inverting input) of error amplifier 511 is coupled to a second terminal of resistor R51. A second input terminal (e.g., non-inverting input) of error amplifier 511 is coupled to a second terminal of resistor R52. The output terminal of error amplifier 511 is coupled to a second terminal of resistor R53 and the output terminal of subtractor 510, i.e., coupled to a first input terminal (e.g., inverting input) of comparator 520.

[0068] When the output of error amplifier 511 is lower than the reference voltage Vref, the sensing result T1 output by comparator 520 is high, causing pre-charge circuit 112 to continuously pre-charge flying capacitor Cfly4. When the output of error amplifier 511 is higher than the reference voltage Vref, the sensing result T1 output by comparator 520 becomes low, indicating that pre-charging of flying capacitor Cfly4 is complete. Based on the sensing result T1 becoming low, pre-charge circuit 112 stops pre-charging flying capacitor Cfly4, and control circuit 114 controls power converter 113 to begin the conversion operation of P32 during normal operation (converting input voltage Vin to output voltage Vout).

[0069] Figure 6 The circuit diagram of the pre-charging circuit 112 is shown according to an embodiment of the present invention. Figure 6 The pre-charge circuit 112 shown can be used as Figure 1 and Figure 4 This is one of many implementation examples of the pre-charge circuit 112 shown. Figure 6 The pre-charge circuit 112, upper power switch SW41, flying capacitor Cfly4, lower power switch SW42, and inductor L4 shown can be referenced. Figure 4 The relevant explanations. In Figure 6 In the illustrated embodiment, the pre-charge circuit 112 includes a switching circuit 610 and a pre-charge switch SW62. The input terminal of the switching circuit 610 receives a pre-charge voltage. This pre-charge voltage can be determined according to the actual design and application. For example, the input terminal of the switching circuit 610 can receive an input voltage Vin (or other voltage) as the pre-charge voltage. The output terminal of the switching circuit 610 is coupled to the first terminal of the flying capacitor Cfly4 of the power converter 113.

[0070] exist Figure 6 In the illustrated embodiment, the switching circuit 610 includes a current-limiting resistor R61 and a pre-charge switch SW61. The current-limiting resistor R61 and the pre-charge switch SW61 are connected in series between the input and output terminals of the switching circuit 610. For example, the first terminal of the current-limiting resistor R61 receives the input voltage Vin, the second terminal of the current-limiting resistor R61 is coupled to the first terminal of the pre-charge switch SW61, and the second terminal of the pre-charge switch SW61 is coupled to the first terminal of the flying capacitor Cfly4. The first terminal of the pre-charge switch SW62 is coupled to the second terminal of the flying capacitor Cfly4. The second terminal of the pre-charge switch SW62 receives a reference voltage (e.g., ground voltage or other fixed voltage). The control terminals of the pre-charge switches SW61 and SW62 are coupled to the sensing circuit 111 to receive the sensing result T1. During the power-on instant, P31 of the pre-charge switches SW61 and SW62 is turned on to pre-charge the flying capacitor Cfly4. During the normal operation period after P32 following the power-on instantaneous period P31, the precharge switches SW61 and SW62 are turned off to stop the precharge of the fly capacitor Cfly4.

[0071] Figure 7 The circuit diagram of sensing circuit 111 and pre-charging circuit 112 is shown according to another embodiment of the present invention. Figure 7 The sensing circuit 111 and pre-charging circuit 112 shown can be used as Figure 1 and Figure 4 This is one of many implementation examples of the sensing circuit 111 and the pre-charging circuit 112 shown. Figure 7The sensing circuit 111, pre-charging circuit 112, upper power switch SW41, flying capacitor Cfly4, lower power switch SW42, and inductor L4 shown can be referenced. Figure 4 The relevant explanations. In Figure 7 In the illustrated embodiment, the pre-charge circuit 112 includes a switching circuit, which includes a current-limiting resistor R71 and a pre-charge switch SW7. Figure 7 The current-limiting resistor R71 and the pre-charge switch SW7 shown can be referenced. Figure 6 The relevant descriptions of the current-limiting resistor R61 and the pre-charge switch SW61 shown are provided and can be extrapolated from here, so they will not be repeated here.

[0072] exist Figure 7 In the embodiment shown, the sensing circuit 111 includes a subtractor 710, a comparator 720, and a logic gate 730. Figure 7 The subtractor 710 and comparator 720 shown can be referred to Figure 5 The descriptions of the subtractor 510 and comparator 520 shown are analogous and will not be repeated here. Depending on the actual design and application, logic gate 730 can be an exclusive-OR gate (XOR gate) or other logic gates. The first input of logic gate 730 is coupled to the output of comparator 720 to receive the sensing result T1. The second input of logic gate 730 is coupled to control circuit 114 to receive the lower switching signal Vsr4. The output of logic gate 730 is coupled to the control terminal of the lower power switch SW42 of power converter 113 to provide the lower switching signal Vsr7.

[0073] Figure 8 The circuit diagram of power converter 113 is shown according to another embodiment of the present invention. Figure 8 The power converter 113 and load circuit 120 shown can be referenced. Figure 1 Related explanations. Figure 8 The sensing circuit 111 shown can be referred to Figure 1 , Figure 4 , Figure 5 and Figure 7 The relevant explanations are then drawn by analogy. Figure 8 The pre-charge circuit 112 shown can be referred to Figure 1 , Figure 4 , Figure 6 and Figure 7 The relevant explanations are then drawn by analogy. Figure 8 The power converter 113 shown can be used as Figure 1 This is one of many implementation examples of the power converter 113 shown. Figure 8In the embodiment shown, the power converter 113 includes an upper power switch SW41, a flying capacitor Cfly4, a lower power switch SW42, an inductor L4, an upper power switch SW81, a lower power switch SW82, an inductor L8, and an output capacitor Co4.

[0074] Figure 9 The following is a timing diagram of the upper switch signal Vs4, the lower switch signal Vsr4, the upper switch signal Vs8, and the lower switch signal Vsr8, according to an embodiment of the present invention. Figure 9 The horizontal axis represents time. Figure 9 The upper switch signal Vs4, lower switch signal Vsr4, upper switch signal Vs8, and lower switch signal Vsr8 shown can be used as... Figure 8 This is one of many implementation examples of the upper switch signal Vs4, lower switch signal Vsr4, upper switch signal Vs8, and lower switch signal Vsr8 shown. Figure 4 The upper switch signal Vs4 and the lower switch signal Vsr4 shown can also be referenced. Figure 9 Please refer to the relevant instructions. Figure 1 , Figure 8 and Figure 9 The control terminal of the upper power switch SW41 is coupled to the control circuit 114 to receive the upper switch signal Vs4. The control terminal of the lower power switch SW42 is coupled to the control circuit 114 to receive the lower switch signal Vsr4. The control terminal of the upper power switch SW81 is coupled to the control circuit 114 to receive the upper switch signal Vs8. The control terminal of the lower power switch SW82 is coupled to the control circuit 114 to receive the lower switch signal Vsr8.

[0075] Figure 8 The power converter 113 shown includes an upper power switch SW41, a flying capacitor Cfly4, a lower power switch SW42, an inductor L4, and an output capacitor Co4, which can be referred to as [reference needed]. Figure 4 The relevant explanations are omitted here. The first terminal of the upper power switch SW81 is coupled to the second terminal of the upper power switch SW41. The first terminal of the lower power switch SW82 is coupled to the second terminal of the upper power switch SW81. The second terminal of the lower power switch SW82 receives a reference voltage (e.g., ground voltage or other fixed voltage). The first terminal of inductor L8 is coupled to the second terminal of the upper power switch SW81. The second terminal of inductor L8 is coupled to the output terminal of power converter 113, together with inductor L4, to provide the output voltage Vout to load circuit 120.

[0076] Figure 10 The circuit diagram of power converter 113 is shown according to another embodiment of the present invention. Figure 10 The power converter 113 and load circuit 120 shown can be referenced. Figure 1 Related explanations. Figure 10The sensing circuits 111 and 115 shown can be referenced. Figure 1 , Figure 4 , Figure 5 and Figure 7 The relevant explanations are then drawn by analogy. Figure 10 The pre-charge circuits 112 and 116 shown can be referenced. Figure 1 , Figure 4 , Figure 6 and Figure 7 The relevant explanations are as follows, and analogies are drawn. The sensing circuit 115 detects the voltage across the flying capacitor Cfly10 (i.e., the voltage difference Vcfly10). In response to the voltage difference Vcfly10 being lower than the reference voltage, the sensing circuit 115 notifies the pre-charging circuit 116 to continue pre-charging the flying capacitor Cfly10 via the sensing result T10. In response to the voltage difference Vcfly10 reaching the reference voltage (representing that the pre-charging of the flying capacitor Cfly10 is complete), the sensing circuit 115 notifies the pre-charging circuit 116 to stop pre-charging the flying capacitor Cfly10 via the sensing result T10, and notifies the control circuit 114 to control the power converter 113 to begin the conversion operation of P32 during normal operation (converting the input voltage Vin to the output voltage Vout). Figure 10 The sensing circuit 115, pre-charging circuit 116 and flying capacitor Cfly10 shown can be deduced by referring to the relevant descriptions of sensing circuit 111, pre-charging circuit 112 and flying capacitor Cfly4, and will not be described again.

[0077] Figure 10 The power converter 113 shown can be used as Figure 1 This is one of many implementation examples of the power converter 113 shown. Figure 10 In the embodiment shown, the power converter 113 includes an upper power switch SW41, a flying capacitor Cfly4, a lower power switch SW42, an inductor L4, an upper power switch SW81, a lower power switch SW82, an inductor L8, an upper power switch SW101, a lower power switch SW102, a flying capacitor Cfly10, and an output capacitor Co4. Figure 10 The upper power switch SW41, flying capacitor Cfly4, lower power switch SW42, inductor L4, upper power switch SW81, lower power switch SW82, inductor L8, and output capacitor Co4 shown can be referenced. Figure 8The relevant explanations are omitted here. The first terminal of the upper power switch SW101 receives the input voltage Vin. The first terminal of the lower power switch SW102 is coupled to the second terminal of the upper power switch SW101. The second terminal of the lower power switch SW102 is coupled to the second terminal of the flying capacitor Cfly4. The first terminal of the flying capacitor Cfly10 is coupled to the second terminal of the upper power switch SW101. The second terminal of the flying capacitor Cfly10 receives a reference voltage (e.g., ground voltage or other fixed voltage).

[0078] The control terminal of the upper power switch SW41 is coupled to the control circuit 114 to receive the upper switch signal Vs4. The control terminal of the lower power switch SW42 is coupled to the control circuit 114 to receive the lower switch signal Vsr4. The control terminals of the upper power switches SW81 and SW101 are coupled to the control circuit 114 to receive the upper switch signal Vs8. The control terminals of the lower power switches SW82 and SW102 are coupled to the control circuit 114 to receive the lower switch signal Vsr8. Figure 9 The upper switch signal Vs4, lower switch signal Vsr4, upper switch signal Vs8, and lower switch signal Vsr8 shown can be used as... Figure 10 This is one of many implementation examples of the upper switch signal Vs4, lower switch signal Vsr4, upper switch signal Vs8, and lower switch signal Vsr8 shown.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A power conversion device, characterized in that, The power conversion device includes: A power converter for converting a first DC voltage into a second DC voltage, wherein the power converter includes a first flying capacitor; A sensing circuit, coupled to the first flying capacitor of the power converter, wherein the sensing circuit senses the voltage difference across the first flying capacitor to generate a sensing result; and A pre-charge circuit is coupled to the first flying capacitor of the power converter to pre-charge the first flying capacitor during the power-on instant of the power conversion device, wherein the pre-charge circuit is coupled to the sensing circuit to receive the sensing result, the pre-charge circuit stops the pre-charging of the first flying capacitor based on the sensing result, and the power converter converts the first DC voltage to the second DC voltage for the load circuit during normal operation after the power-on instant.

2. The power conversion device according to claim 1, characterized in that, The power conversion device further includes: A control circuit is coupled to the power converter and the sensing circuit, wherein the sensing circuit further provides the sensing result to the control circuit, and the control circuit determines the end of the power-on instantaneous period based on the sensing result of the sensing circuit, and the control circuit enters the normal operation period after the power-on instantaneous period ends to control the conversion operation of the power converter.

3. The power conversion device according to claim 1, characterized in that, The power converter also includes: A first power switch, wherein a first terminal of the first power switch receives the first DC voltage, a second terminal of the first power switch is coupled to a first terminal of the first flying capacitor, and a control terminal of the first power switch is coupled to a control circuit to receive a first power switch signal. A first down-power switch, wherein a first terminal of the first down-power switch is coupled to a second terminal of the first flying capacitor, the second terminal of the first down-power switch receives a first reference voltage, and a control terminal of the first down-power switch is coupled to the control circuit to receive a first down-switching signal; and A first inductor, wherein a first end of the first inductor is coupled to a second end of the first flying capacitor, a second end of the first inductor is coupled to an output terminal of the power converter, and the output terminal of the power converter outputs the second DC voltage to the load circuit.

4. The power conversion device according to claim 3, characterized in that, The power converter also includes: An output capacitor, wherein a first terminal of the output capacitor is coupled to a second terminal of the first inductor, and a second terminal of the output capacitor receives a second reference voltage.

5. The power conversion device according to claim 3, characterized in that, The power converter also includes: The second power switch, wherein a first terminal of the second power switch is coupled to a second terminal of the first power switch, and a control terminal of the second power switch is coupled to the control circuit to receive a second power switch signal; A second lower power switch, wherein a first terminal of the second lower power switch is coupled to a second terminal of the second upper power switch, the second terminal of the second lower power switch receives a second reference voltage, and a control terminal of the second lower power switch is coupled to the control circuit to receive a second lower switch signal; and The second inductor, wherein a first end of the second inductor is coupled to a second end of the second upper power switch, and a second end of the second inductor is coupled to the output of the power converter.

6. The power conversion device according to claim 5, characterized in that, The power converter also includes: A third power switch, wherein a first terminal of the third power switch receives the first DC voltage, and a control terminal of the third power switch is coupled to the control circuit to receive a third power switch signal; A third power switch, wherein a first terminal of the third power switch is coupled to a second terminal of the third power switch, a second terminal of the third power switch is coupled to a second terminal of the first flying capacitor, and a control terminal of the third power switch is coupled to the control circuit to receive a third power switch signal; and A second flying capacitor, wherein a first terminal of the second flying capacitor is coupled to the second terminal of the third power switch, and a second terminal of the second flying capacitor receives a third reference voltage.

7. The power conversion device according to claim 1, characterized in that, The sensing circuit includes: A subtractor, wherein the first input terminal and the second input terminal of the subtractor are respectively coupled to the first terminal and the second terminal of the first flying capacitor of the power converter to receive the terminal voltage difference of the first flying capacitor; and A comparator, wherein a first input of the comparator is coupled to the output of the subtractor, a second input of the comparator receives a first reference voltage, and the output of the comparator outputs the sensing result.

8. The power conversion device according to claim 7, characterized in that, The subtractor includes: A first resistor, wherein a first end of the first resistor is coupled to the first input terminal of the subtractor; A second resistor, wherein a first end of the second resistor is coupled to the second input terminal of the subtractor; A third resistor, wherein a first end of the third resistor is coupled to a second end of the first resistor; A fourth resistor, wherein a first terminal of the fourth resistor is coupled to a second terminal of the second resistor, and the second terminal of the fourth resistor receives a second reference voltage; and An error amplifier, wherein a first input terminal of the error amplifier is coupled to a second terminal of the first resistor, a second input terminal of the error amplifier is coupled to a second terminal of the second resistor, and an output terminal of the error amplifier is coupled to a second terminal of the third resistor and the output terminal of the subtractor.

9. The power conversion device according to claim 7, characterized in that, The sensing circuit further includes: A logic gate, wherein a first input of the logic gate is coupled to the output of the comparator to receive the sensing result, a second input of the logic gate is coupled to a control circuit to receive a first down-switching signal, and the output of the logic gate is coupled to the power converter to provide a second down-switching signal.

10. The power conversion device according to claim 1, characterized in that, The pre-charging circuit includes: A switching circuit, wherein the input terminal of the switching circuit receives a pre-charge voltage, the output terminal of the switching circuit is coupled to a first terminal of the first flying capacitor of the power converter, the switching circuit includes a current-limiting resistor and a first pre-charge switch, the current-limiting resistor and the first pre-charge switch are connected in series between the input terminal and the output terminal of the switching circuit, the control terminal of the first pre-charge switch is coupled to the sensing circuit to receive the sensing result, and the first pre-charge switch is turned on during the power-on instant to pre-charge the first flying capacitor.

11. The power conversion device according to claim 10, characterized in that, The pre-charging circuit also includes: A second pre-charge switch, wherein a first terminal of the second pre-charge switch is coupled to a second terminal of the first flying capacitor of the power converter, a second terminal of the second pre-charge switch receives a reference voltage, and a control terminal of the second pre-charge switch is coupled to the sensing circuit to receive the sensing result.

12. A pre-charging method for a power conversion device, characterized in that, The pre-charging method includes: The pre-charging circuit of the power conversion device pre-charges the first flying capacitor of the power converter of the power conversion device during the instant of power conversion device startup; The sensing circuit of the power conversion device senses the voltage difference across the first flying capacitor and generates a sensing result for the pre-charging circuit. The pre-charging circuit stops the pre-charging of the first flying capacitor of the power converter based on the sensing result; and The power converter converts the first DC voltage to a second DC voltage for the load circuit during normal operation after the power-on instant.

13. The pre-charging method according to claim 12, characterized in that, The pre-charging method further includes: The sensing circuit provides the sensing result to the control circuit of the power conversion device, wherein the control circuit is coupled to the power converter and the sensing circuit. The control circuit determines the end of the power-on instantaneous period based on the sensing result of the sensing circuit; and The control circuit controls the conversion operation of the power converter during the normal operation period after the power-on instantaneous period ends.

14. A power conversion device, characterized in that, The power conversion device includes: A power converter that converts an input voltage into an output voltage, wherein the power converter includes a flying capacitor; A sensing circuit, coupled to the flying capacitor, senses the voltage across the flying capacitor; and A pre-charge circuit, coupled to the power converter, charges the flying capacitor when the voltage across the flying capacitor is less than a reference voltage.

15. The power conversion device according to claim 14, characterized in that, When the voltage across the flying capacitor is greater than the reference voltage, the pre-charge circuit stops charging the flying capacitor.

16. The power conversion device according to claim 14, characterized in that, The reference voltage is less than or equal to half of the input voltage.

17. The power conversion device according to claim 14, characterized in that, The power conversion device further includes: A control circuit is coupled to the power converter and the sensing circuit, wherein the control circuit controls the pre-charge circuit based on the cross voltage of the flying capacitor, and when the cross voltage of the flying capacitor is equal to half of the input voltage, the control circuit controls the power converter to convert the input voltage into the output voltage.

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