Power conversion device and method for power conversion

Abstract

A power conversion device and a power conversion method are disclosed. The voltage conversion device includes a voltage input terminal, a voltage output terminal, a voltage detection selector, a buck converter circuit, and a bypass switch circuit. The voltage detection selector detects whether the input voltage is greater than a predetermined voltage to generate a first enable signal and a second enable signal. The buck converter circuit receives the second enable signal. When the second enable signal is enabled, the buck converter circuit converts the input voltage value into a converted voltage that is lower than or equal to the predetermined voltage and provides the converted voltage to the voltage output terminal. The bypass switch circuit receives the first enable signal. When the first enable signal is enabled, the bypass switch circuit provides the input voltage at the voltage input terminal to the voltage output terminal.

Description

Technical Field

[0001] This invention relates to a power supply and power conversion technology, and more particularly to a power conversion device. Prior Technology

[0002] Electronic devices can obtain the power they need from a power supply device or store this power in an energy storage device (such as a battery). Current consumer electronic devices commonly use the Universal Serial Bus (USB) interface as their power source; therefore, the USB interface of these consumer electronic devices complies with the USB Power Delivery (PD) charging protocol.

[0003] With the gradual updates to the USB PD charging protocol, the current USB PD 3.1 charging protocol supports input power up to 48 volts (V) and power supply up to 240 watts (W). However, since the input power of previous USB PD charging protocols (such as PD 2.0 and PD 3.0) was approximately 20V, to make consumer electronic devices compliant with the current USB PD 3.1 charging protocol, a power conversion device (such as a buck-boost converter) was needed to convert the input power to a voltage of less than or equal to 20V to successfully power the consumer electronic devices. However, buck-boost converters have higher costs and circuit complexity. Furthermore, if the input power is between 5V and 20V, two stages of power conversion are required (first stage: buck-boost converter; second stage: NVDC voltage conversion circuitry used in previous USB PD charging protocols) to provide power, resulting in decreased power conversion efficiency. Summary of the Invention

[0004] The present invention provides a power conversion device and a power conversion method, which can selectively activate one of two power paths by detecting the input voltage to improve the power conversion efficiency under light load, thereby achieving energy saving.

[0005] The voltage conversion device of this invention includes a voltage input terminal, a voltage output terminal, a voltage detection selector, a buck converter circuit, and a bypass switch circuit. The voltage input terminal is used to obtain an input voltage. The voltage output terminal is used to provide an output voltage. The voltage detection selector, coupled to the voltage input terminal, is used to detect whether the input voltage is greater than a predetermined voltage, thereby generating a first enable signal and a second enable signal. When the input voltage is greater than the predetermined voltage, the first enable signal changes from enabled to disabled, and the second enable signal changes from disabled to enabled. The buck converter circuit, coupled to the voltage input terminal and the voltage output terminal, is used to receive the second enable signal, and when the second enable signal is enabled, converts the input voltage value into a converted voltage lower than or equal to the predetermined voltage, and provides the converted voltage to the voltage output terminal. A bypass switch circuit is coupled to the voltage input terminal and the voltage output terminal. The bypass switch circuit is used to receive the first enable signal and, when the first enable signal is enabled, to provide the input voltage on the voltage input terminal to the voltage output terminal.

[0006] The power conversion method of this invention is applicable to a voltage conversion device including a buck converter circuit and a bypass switch circuit. The power conversion method includes the following steps: detecting whether the input voltage of the voltage conversion device is greater than a predetermined voltage to generate a first enable signal and a second enable signal, wherein when the input voltage is greater than the predetermined voltage, the first enable signal changes from enabled to disabled, and the second enable signal changes from disabled to enabled; when the first enable signal is enabled, the input voltage is provided to the voltage output terminal of the voltage conversion device through the bypass switch circuit; and when the second enable signal is enabled, the input voltage value is converted to a converted voltage lower than or equal to the predetermined voltage through the buck converter circuit, and the converted voltage is provided to the voltage output terminal.

[0007] Based on the above, the power conversion device and method described in this embodiment of the invention provide two power paths in the power conversion device. One power path uses a buck converter circuit to convert the input voltage to a converted voltage lower than or equal to a predetermined voltage (e.g., 20V). The other power path uses a bypass switch circuit to directly supply the input voltage to the voltage output terminal. A voltage detection selector detects whether the input voltage is greater than the predetermined voltage (e.g., 20V) to selectively enable one of the two power paths, thereby achieving optimal power path selection under different input voltage ranges, improving power conversion efficiency under light loads, and satisfying the USB PD 3.1 charging protocol. Simple Explanation of the Diagram

[0008] Figure 1 is a schematic diagram of a voltage conversion device according to an embodiment of the present invention. Figure 2 is an exemplary circuit diagram of the voltage detection selector in Figure 1. Figure 3 is an exemplary circuit diagram of the buck converter circuit in Figure 1. Figure 4 is an exemplary circuit diagram of the bypass switch circuit in Figure 1. Figure 5 is a schematic diagram of each signal in Figure 2. Figure 6 is a flowchart of a power conversion method according to an embodiment of the present invention. Implementation

[0009] Figure 1 is a schematic diagram of a voltage conversion device 100 according to an embodiment of the present invention. The voltage conversion device 100 can be implemented in an electronic device (e.g., a notebook computer, tablet computer, desktop computer, smartphone) or a power supply device corresponding to the electronic device (e.g., a power adapter).

[0010] The voltage conversion device 100 includes a voltage input terminal INN, a voltage output terminal OUTN, a voltage detection selector 120, a buck converter circuit 140, and a bypass switch circuit 150. The voltage input terminal INN is used to obtain the input voltage Vin. The voltage output terminal OUTN is used to provide the output voltage Vout. In this embodiment, the input voltage Vin can be in the range of 5V to 48V to meet the USB PD 3.1 charging protocol.

[0011] A voltage detection selector 120 is coupled to the voltage input terminal INN. The voltage detection selector 120 detects whether the input voltage Vin is greater than a predetermined voltage (e.g., 20V) to generate a first enable signal EN_P1 and a second enable signal EN_P2. Specifically, when the voltage conversion device 100 is first started, the first enable signal EN_P1 is enabled and the second enable signal EN_P2 is disabled. Furthermore, when the input voltage Vin is greater than the predetermined voltage (20V), the first enable signal EN_P1 changes from enabled to disabled, and the second enable signal EN_P2 changes from disabled to enabled.

[0012] The buck converter circuit 140 is coupled to the voltage input terminal INN and the voltage output terminal OUTN. In this embodiment, the buck converter circuit 140 is considered as the second power supply path P2. The buck converter circuit 140 receives a second enable signal EN_P2. When the second enable signal EN_P2 is enabled, that is, when the input voltage Vin is greater than 20V, the buck converter circuit 140 will be activated to convert the input voltage Vin to a converted voltage lower than or equal to a predetermined voltage (20V), and provide this converted voltage to the voltage output terminal OUTN. On the other hand, when the second enable signal EN_P2 is disabled, the buck converter circuit 140 will not be activated and will not provide voltage to the voltage output terminal OUTN. That is, when the second enable signal EN_P2 is disabled, the second power supply path P2 is disconnected.

[0013] The bypass switch circuit 150 is coupled to the voltage input terminal INN and the voltage output terminal OUTN. In this embodiment, the bypass switch circuit 150 is considered as the first power path P1. The bypass switch circuit 150 is used to receive the first enable signal EN_P1. When the first enable signal EN_P1 is enabled, that is, when the input voltage Vin is less than or equal to 20V, the bypass switch circuit 150 will be activated to directly provide the input voltage Vin on the voltage input terminal INN to the voltage output terminal OUTN, and the bypass switch circuit 150 will not perform voltage conversion or corresponding processing on the input voltage Vin. On the other hand, when the first enable signal EN_P1 is disabled, the bypass switch circuit 150 will not be activated and will not provide the input voltage Vin to the voltage output terminal OUTN. In this embodiment, the buck converter circuit 140 and the bypass switch circuit 150 are controlled by the second enable signal EN_P2 and the first enable signal EN_P1, respectively, and the buck converter circuit 140 and the bypass switch circuit 150 provide voltage to the voltage output terminal OUTN at different time points. In other words, the buck converter circuit 140 and the bypass switch circuit 150 will not be enabled simultaneously.

[0014] The voltage conversion device 100 also includes an input circuit 110 coupled to the voltage input terminal INN, a charging control device 160, and a system device 170. The input circuit 110 includes at least one universal sequence bus port (e.g., universal sequence bus ports 112-1 and 112-2 in Figure 1), at least one input protection switch circuit (e.g., input protection switch circuits 114-1 and 114-2 in Figure 1), and a power delivery controller 116. Users can direct external power to the voltage conversion device 100 via universal sequence bus ports 112-1 and 112-2 and universal sequence bus compliant cables. Input protection switch circuits 114-1 and 114-2 provide electrostatic discharge (ESD) protection for universal sequence bus ports 112-1 and 112-2 and overvoltage protection for the input voltage Vin. The first terminals of input protection switch circuits 114-1 and 114-2 are coupled to the output terminals of general sequence bus ports 112-1 and 112-2, respectively. The second terminals of input protection switch circuits 114-1 and 114-2 are both coupled to the voltage input terminal INN. The power transfer controller 116 can be coupled to the input protection switch circuits 114-1 and 114-2 to control the power transfer of general sequence bus ports 112-1 and 112-2 in Figure 1. The charging control device 160 is coupled to the voltage output terminal OUTN. The charging control device 160 supplies power to the system device 170 (e.g., motherboard, processor, battery-powered device, etc.) based on the voltage on the voltage output terminal OUTN.

[0015] The charging control device 160 in this embodiment of the invention is primarily capable of handling power supplies with a predetermined voltage (20V) or lower. Therefore, when the input voltage Vin (e.g., 5V~20V) is less than or equal to the predetermined voltage (20V), the first power path P1 controlled by the bypass switch circuit 150 will be turned on and the second power path P2 will be turned off, thereby improving the power conversion efficiency under light load. On the other hand, when the input voltage Vin (e.g., 48V~20V) is greater than the predetermined voltage (20V), the second power path P2 controlled by the buck converter circuit 140 will be turned on and the first power path P1 will be turned off, converting the input voltage Vin to a converted voltage lower than or equal to the predetermined voltage (20V). This reduces costs by replacing the buck-boost converter with a buck converter, while simultaneously satisfying the USB PD 3.1 charging protocol.

[0016] Figure 2 is an exemplary circuit diagram of the voltage detection selector 120 in Figure 1. Referring to Figure 2, the voltage detection selector 120 includes a voltage divider circuit 210, a reference voltage generator 220, a comparator 230, and a startup logic circuit 240. The voltage divider circuit 210 is coupled to the voltage input terminal INN. The voltage divider circuit 210 is used to generate a divided voltage Vsep based on the input voltage Vin.

[0017] Reference voltage generator 220 generates a reference voltage Vref. The first input (non-inverting input) of comparator 230 receives the divided voltage Vsep, and the second input (inverting input) receives the reference voltage Vref. Comparator 230 determines whether the divided voltage Vsep is greater than the reference voltage Vref, and provides a second enable signal EN_P2 at its output. When the divided voltage Vsep is greater than the reference voltage Vref, the second enable signal EN_P2 changes from disabled to enabled.

[0018] The startup logic circuit 240 receives the second enable signal EN_P2. The startup logic circuit 240 is used as the signal source to convert the first enable signal EN_P1 into a disable signal based on the second enable signal EN_P2 and the normal power signal PG1 of the voltage converter 100. The normal power signal PG1 of the voltage converter 100 is the signal provided when the voltage converter 100 is operating normally. When the normal power signal PG1 is enabled and the second enable signal EN_P2 is enabled, the first enable signal EN_P1 is disabled.

[0019] In detail, the startup logic circuit 240 includes transistors MN1 and MN2, which function as an inverter between the first enable signal EN_P1 and the second enable signal EN_P2. The control terminal (e.g., the gate terminal) of transistor MN2 receives the second enable signal EN_P2. Since the second enable signal EN_P2 is the output of the input voltage comparator 230, when the second enable signal EN_P2 changes from a negative potential to the positive potential of the normal power supply signal PG1, and the voltage level of the second enable signal EN_P2 rises above the threshold voltage of the gate terminal of transistor MN2, transistor MN2 will conduct, grounding its source terminal and simultaneously turning off the first enable signal EN_P1 due to grounding. The first terminal of transistor MN1 (e.g., the source terminal) is also connected to the first enable signal EN_P1, and the control terminal of transistor MN1 (e.g., the gate terminal) is connected to the power supply normal signal PG1. Transistor MN1 acts as a second fuse for the inverter. When the voltage level of the power supply normal signal PG1 rises above the threshold voltage of the gate terminal of transistor MN1, it will cause transistor MN1 to conduct, grounding the source terminal of transistor MN1, and simultaneously turning off the first enable signal EN_P1 due to grounding.

[0020] Figure 3 is an exemplary circuit diagram of the buck converter circuit 140 in Figure 1. The buck converter circuit 140 includes a buck converter 310, a first transistor M1, a second transistor M2, and a first inductor L1. The buck converter 310 receives a second enable signal EN_P2. The first terminal of the first transistor M1 is coupled to the voltage input terminal INN to receive the input voltage Vin. The control terminal of the first transistor M1 is coupled to the buck converter 310. The first terminal of the second transistor M2 is coupled to the second terminal of the first transistor M1. The control terminal of the second transistor M2 is coupled to the buck converter 310. The first terminal of the first inductor L1 is coupled to the second terminal of the first transistor M1 and the first terminal of the second transistor M2. The second terminal of the first inductor L1 is coupled to the voltage output terminal OUTN. In this embodiment, the second terminal of the second transistor M2 is coupled to ground.

[0021] Figure 4 is an exemplary circuit diagram of the bypass switch circuit 150 in Figure 1. The bypass switch circuit 150 includes a bypass switch transistor Mbp1. The control terminal of the bypass switch transistor Mbp1 receives a first enable signal EN_P1. The first terminal of the bypass switch transistor Mbp1 is coupled to the voltage input terminal INN. The second terminal of the bypass switch transistor Mbp1 is coupled to the voltage output terminal OUTN.

[0022] Figure 5 is a schematic diagram of the signals in Figure 2. Figure 5 shows exemplary waveforms of the input voltage Vin, the voltage divider Vsep, the first enable signal EN_P1, the second enable signal EN_P2, and the output voltage Vout. As can be seen from Figure 5, the first enable signal EN_P1 is preset to enable, and the second enable signal EN_P2 is preset to disable. Therefore, the first power path P1 is on and the second power path P2 is off. When the voltage conversion device 100 is started or an external power supply is connected to the input circuit 110 in Figure 1, the input voltage Vin will gradually increase, and the voltage divider Vsep will also increase accordingly.

[0023] When the voltage value of the voltage divider Vsep is higher than the reference voltage Vref (e.g., at the time point when the predetermined voltage is reached, as shown by line LN1), the first enable signal EN_P1 changes from enabled to disabled, and the second enable signal EN_P1 changes from disabled to enabled. Therefore, the second power supply path P2 is turned on and the first power supply path P1 is turned off. In this way, the output voltage Vout will be adjusted to a converted voltage lower than or equal to the predetermined voltage (20V).

[0024] Figure 6 is a flowchart of a power conversion method according to an embodiment of the present invention. The method described in Figure 6 is applicable to a voltage conversion device 100 including the buck converter circuit 140 and the bypass switch circuit 150 of Figure 1. Referring to Figures 1 and 6 simultaneously, in step S610, it is detected whether the input voltage Vin of the voltage conversion device 100 is greater than a predetermined voltage to generate a first enable signal EN_P1 and a second enable signal EN_P2. When the input voltage Vin rises to a level greater than the predetermined voltage (e.g., 20V), the first enable signal EN_P1 changes from enabled to disabled, and the second enable signal EN_P2 changes from disabled to enabled. In step S620, when the first enable signal EN_P1 is enabled, the input voltage Vin is provided to the voltage output terminal OUTN of the voltage conversion device 100 through the bypass switch circuit 150. In step S630, when the second enable signal EN_P2 is enabled, the input voltage Vin is converted to a voltage lower than or equal to a predetermined voltage (e.g., 20V) by the buck converter circuit 140, and this converted voltage is provided to the voltage output terminal OUTN. For details of each step in the method described in Figure 6, please refer to the foregoing embodiments.

[0025] In summary, the power conversion device and method described in this embodiment of the invention provide two power paths in the power conversion device. One power path uses a buck converter circuit to convert the input voltage to a converted voltage lower than or equal to a predetermined voltage (e.g., 20V). The other power path uses a bypass switch circuit to directly supply the input voltage to the voltage output terminal. A voltage detection selector detects whether the input voltage is greater than the predetermined voltage (e.g., 20V) to selectively enable one of the two power paths, thereby achieving optimal power path selection under different input voltage ranges, improving power conversion efficiency under light loads, and satisfying the USB PD 3.1 charging protocol.

[0026] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0027] 100: Voltage conversion device 110: Input Circuit 112-1, 112-2: General Sequence Bus Ports 114-1, 114-2: Input protection switch circuit 116: Power Transfer Controller 120: Voltage Detection Selector 140: Buck converter circuit 150: Bypass switch circuit 160: Charging control device 170: System device 210: Voltage divider circuit 220: Reference Voltage Generator 230: Comparator 240: Startup logic circuit 310: Buck Converter Vin: Input voltage Vout: Output voltage P1: First power path P2: Second power path EN_P1: First enable signal EN_P2: Second enable signal MN1, MN2: Transistors VSS: System voltage terminal Vsep: Voltage divider Vref: Reference voltage M1: First transistor M2: Second transistor L1: First Inductor Mbp1: Bypass switch transistor LN1: Lines

Claims

1. A voltage conversion device, comprising: Voltage input terminal, used to obtain the input voltage; Voltage output terminal, used to provide output voltage; A voltage detection selector, coupled to the voltage input terminal, is used to detect whether the input voltage is greater than a predetermined voltage to generate a first enable signal and a second enable signal, wherein when the input voltage is greater than the predetermined voltage, the first enable signal changes from enabled to disabled, and the second enable signal changes from disabled to enabled; a buck converter circuit, coupled to the voltage input terminal and the voltage output terminal, wherein the buck converter circuit is used to receive the second enable signal, and when the second enable signal is enabled, converts the voltage value of the input voltage to a converted voltage lower than or equal to the predetermined voltage, and provides the converted voltage to the voltage output terminal; and a bypass switch circuit, coupled to the voltage input terminal and the voltage output terminal, wherein the bypass switch circuit is used to receive the first enable signal, and when the first enable signal is enabled, provides the input voltage at the voltage input terminal to the voltage output terminal.

2. The voltage conversion device as claimed in claim 1, wherein the buck conversion circuit and the bypass switch circuit provide voltage to the voltage output terminal at different times.

3. The voltage conversion device as claimed in claim 1, wherein the first enable signal is preset to enable.

4. The voltage conversion device as claimed in claim 1, wherein the buck converter circuit comprises: The buck converter receives the second enable signal; A first transistor, the first terminal of which is coupled to the voltage input terminal, and the control terminal of the first transistor is coupled to the buck converter; The second transistor has a first terminal coupled to the second terminal of the first transistor, and the control terminal of the second transistor is coupled to the buck converter. And a first inductor, the first end of which is coupled to the second end of the first transistor and the first end of the second transistor, and the second end of the first inductor is coupled to the voltage output terminal.

5. The voltage conversion device as claimed in claim 1, wherein the bypass switch circuit comprises: A bypass switch transistor has a control terminal that receives the first enable signal, a first terminal of the bypass switch transistor that is coupled to the voltage input terminal, and a second terminal of the bypass switch transistor that is coupled to the voltage output terminal.

6. The voltage conversion device as claimed in claim 1, wherein the voltage detection selector comprises: A voltage divider circuit, coupled to the voltage input terminal, is used to generate a voltage divider based on the input voltage; A reference voltage generator is used to generate a reference voltage. A comparator, whose first input receives the divided voltage and whose second input receives the reference voltage, is used to determine whether the divided voltage is greater than the reference voltage to provide a second enable signal at the output of the comparator, wherein when the divided voltage is greater than the reference voltage, the second enable signal changes from disabled to enabled; and a startup logic circuit, which receives the second enable signal and uses the second enable signal and the normal power signal of the voltage conversion device as a signal source to provide the first enable signal to change to a disabled signal, wherein when the normal power signal is enabled and the second enable signal is enabled, the first enable signal is disabled.

7. The voltage conversion device as claimed in claim 1, further comprising an input circuit coupled to the voltage input terminal, wherein the input circuit includes: At least one general sequence bus port; At least one input protection switch circuit, wherein the first terminal of the at least one input protection switch circuit is coupled to the output terminal of the at least one general sequence bus port, and the second terminal of the at least one input protection switch circuit is coupled to the voltage input terminal; And a power transmission controller, coupled to the at least one input protection switch circuit.

8. The voltage conversion device as claimed in claim 1, further comprising: A charging control device, coupled to the voltage output terminal, is used to supply power to the system device based on the voltage at the voltage output terminal.

9. A power conversion method, applicable to a voltage conversion device including a step-down conversion circuit and a bypass switch circuit, the method comprising: The system detects whether the input voltage of the voltage conversion device is greater than a predetermined voltage to generate a first enable signal and a second enable signal. When the input voltage is greater than the predetermined voltage, the first enable signal changes from enabled to disabled, and the second enable signal changes from disabled to enabled. When the first enable signal is enabled, the input voltage is provided to the voltage output terminal of the voltage conversion device through the bypass switch circuit. When the second enable signal is enabled, the input voltage is converted to a converted voltage that is lower than or equal to the predetermined voltage through the buck converter circuit, and the converted voltage is provided to the voltage output terminal.

10. The method of claim 9, wherein the step of detecting whether the input voltage of the voltage conversion device is greater than the predetermined voltage includes: The input voltage is divided to generate a divided voltage; Determine whether the voltage divider is greater than the reference voltage to provide the second enable signal, wherein when the voltage divider is greater than the reference voltage, the second enable signal changes from disabled to enabled; and use the second enable signal and the power supply normal signal of the voltage conversion device as the signal source for providing the first enable signal to change to disabled signal, wherein when the power supply normal signal is enabled and the second enable signal is enabled, the first enable signal is disabled.

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