Power converters, PFC controllers, circuit boards, adapters and electronic devices

Abstract

The present invention provides a power converter, a PFC controller, a circuit board, an adapter, and an electronic device. The PFC controller detects the voltage of an intermediate DC power supply. When the voltage of the intermediate DC power supply is less than a threshold voltage, the PFC controller controls a PFC boost circuit to utilize the intermediate DC power supply to maintain the voltage on the DC bus at a first target PFC voltage. Driven by the resonant current generated by an LLC resonant conversion circuit, a charge pump PFC circuit can charge the DC bus. When the voltage of the intermediate DC power supply is greater than the threshold voltage, the PFC controller controls the PFC boost circuit to stop operating. Driven by the resonant current generated by the LLC resonant conversion circuit, the charge pump PFC circuit maintains the voltage on the DC bus at a second target PFC voltage. This power converter can be used in various regions of the world and can perform power factor correction relatively efficiently and at a low cost.

Description

Technical Field

[0001] The present invention relates to the field of power supplies, and in particular to a power converter, a PFC controller, a circuit board, an adapter and electronic equipment. Background Art

[0002] A common type of power converter includes an input rectifier and filter circuit, a PFC (power factor correction) circuit, a conversion circuit, and an output rectifier circuit. The input rectifier and filter circuit rectifies and filters the input AC power supply into an intermediate DC power supply. The conversion circuit converts the intermediate DC power supply into an intermediate AC power supply. The output rectifier circuit then rectifies the intermediate AC power supply into an output DC power supply for a DC load (such as an LED). The PFC circuit provides power factor correction for the power converter.

[0003] Common PFC circuits currently include charge pump PFC circuits (such as those described in CN216414184U) and active PFC circuits (also known as APFC circuits). When using a charge pump PFC circuit, the conversion circuit typically requires an LLC resonant converter circuit to drive the charge pump PFC circuit, while active PFC circuits generally use a boost converter circuit.

[0004] like Figure 1 FIG. 1 is a circuit diagram of a power converter using a charge pump PFC circuit 120 , including an input rectifier and filter circuit 110 , a charge pump PFC circuit 120 , an LLC resonant converter circuit 130 , and an output rectifier circuit 140 . The primary side of the transformer T is a component of the LLC resonant converter circuit 130 , and the secondary side is coupled to the output rectifier circuit 140 . The output of the charge pump PFC circuit 120 is coupled to the DC bus of the power converter. The resonant current generated by the LLC resonant converter circuit 130 drives the charge pump PFC circuit 120 , thereby maintaining the DC bus voltage at a designed target PFC voltage (which can be either a single value or a range of values). The output DC power Vo of the output rectifier circuit 140 is supplied to a DC load (e.g., an LED).

[0005] like Figure 2, which is a circuit diagram of a power converter using an active PFC circuit 150 and an LLC resonant conversion circuit 130, includes an input rectifier and filter circuit 110, an active PFC circuit 150, an LLC resonant conversion circuit 130, and an output rectifier circuit 140. The active PFC circuit 150 includes a PFC controller and a PFC boost circuit 151. The output of the PFC boost circuit 151 is coupled to the DC bus of the power converter. The primary side of the transformer T is a component of the LLC resonant conversion circuit 130, and the secondary side is coupled to the output rectifier circuit 140. A target PFC voltage can be set in the PFC controller. The PFC controller detects the voltage of the DC bus and maintains the DC bus voltage at the target PFC voltage by controlling the operation of the PFC boost circuit 151.

[0006] In actual product applications, power converters using charge pump PFC circuits must be used in countries or regions with an AC input voltage RMS of 200V or above. This is because the charge pump PFC circuit needs to work in conjunction with the LLC resonant converter circuit. Under the current common AC voltage RMS values ​​worldwide (for example, 120V in the United States, 220V in China, and 200-264V in Europe), the LLC resonant converter circuit generally requires an AC input voltage RMS of 200V or above. Otherwise, if the RMS value is lower than 200V, the switching frequency driving the LLC resonant converter circuit needs to be reduced to maintain a constant output DC voltage. This frequency can easily drop below the critical point frequency, causing the LLC resonant converter circuit to enter the ZCS (zero current switching) operating region, resulting in the switches in the LLC resonant converter circuit being unable to achieve ZVS (zero voltage switching). This leads to increased losses and reduced efficiency in the LLC resonant converter circuit. More seriously, it can also cause loop instability in the LLC resonant converter circuit. In short, the charge pump PFC circuit is limited by the input voltage. In actual products, the power converter using this charge pump PFC circuit has a narrow application voltage range and can only be used in countries or regions above 200V (such as Europe).

[0007] In contrast, active PFC circuits operate more stably within the commonly used AC voltage range worldwide, offering a wider voltage range. To maximize operation within this common AC voltage range (for example, catering to both the US market (100-277VAC) and the European market (200-264VAC), some current power converters employing active PFC circuits set their target output voltage to 400V or above. This allows the active PFC circuit to perform power factor correction regardless of whether the power converter is used in countries or regions with low AC input voltages (less than 200V RMS) or high AC input voltages (above 200V RMS), ensuring that the power factor (PF) and THD (harmonic distortion) of the power converter meet the relevant requirements of the respective country or region. Otherwise, if the target output voltage of the active PFC circuit is set to less than 400V, when the power converter is used in areas with high AC input voltage (RMS value above 200V), the duty cycle D of the boost circuit in the active PFC circuit will decrease, causing the active PFC circuit to malfunction, significantly reducing the power factor (PF) and worsening harmonic distortion (THD). However, if the target output voltage of the active PFC circuit is set to 400V or above, when the power converter is used in areas with low AC input voltage (RMS value below 200V), the duty cycle D of the boost circuit in the active PFC circuit will increase, causing the RMS current in the boost circuit to increase, thereby increasing the losses in the inductor and MOSFET (or other switching transistors) in the boost circuit, reducing power conversion efficiency. In addition, to accommodate the higher current in the boost circuit, MOSFETs and inductors with higher current ratings (larger in size) are required, further increasing costs. Summary of the Invention

[0008] Based on the above situation, the main purpose of the present invention is to provide a power converter, a PFC controller, a circuit board, an adapter and an electronic device, so that they can operate within the current range of common AC voltage effective values ​​in the world with high efficiency and low cost.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A power converter includes an input rectifier and filter circuit, an active PFC circuit, an LLC resonant converter circuit, and an output rectifier and filter circuit. The active PFC circuit includes a PFC controller and a PFC boost circuit. The input rectifier and filter circuit rectifies and filters an AC power supply to form an intermediate DC power supply. The power converter also includes a charge pump PFC circuit. The charge pump PFC circuit and the active PFC circuit are both coupled to an output terminal of the input rectifier and filter circuit, a DC bus, and the LLC resonant converter circuit.

[0011] The PFC controller detects the voltage of the intermediate DC power supply.

[0012] When the voltage of the intermediate DC power supply is less than a threshold voltage, the PFC controller controls the PFC boost circuit to maintain the voltage on the DC bus at a first target PFC voltage using the intermediate DC power supply, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectifier and filter circuit rectifies and filters the intermediate AC power supply into an output DC power supply for a DC load, and the charge pump PFC circuit, driven by the resonant current generated by the LLC resonant conversion circuit, can charge the DC bus.

[0013] When the voltage of the intermediate DC power supply is greater than the threshold voltage, the PFC controller controls the PFC boost circuit to stop operating, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectifier and filter circuit rectifies and filters the intermediate AC power supply into an output DC power supply for the DC load, and the charge pump PFC circuit, driven by the resonant current generated by the LLC resonant conversion circuit, maintains the voltage on the DC bus at a second target PFC voltage, wherein the second target PFC voltage is greater than the first target PFC voltage, and the first target PFC voltage is greater than the threshold voltage.

[0014] Preferably, the power converter further includes a first diode, wherein an anode of the first diode is coupled to the output end of the input rectifier filter circuit, and a cathode of the first diode is coupled to the DC bus.

[0015] Preferably, the charge pump PFC circuit includes a second diode, a third diode and a pump capacitor; the LLC resonant conversion circuit includes a half-bridge switch arm and a resonant element; the positive and negative ends of the half-bridge switch arm are respectively coupled to the DC bus and the ground; the anode of the second diode is coupled to the output end of the input rectifier filter circuit, and the cathode is coupled to the anode of the third diode; the cathode of the third diode is coupled to the DC bus; the common end of the second diode and the third diode is grounded through the pump capacitor, and is connected to the midpoint of the half-bridge switch arm through the resonant element.

[0016] Preferably, the charge pump PFC circuit includes a second diode, a third diode, a fourth diode, a fifth diode and a pump capacitor; the LLC resonant conversion circuit includes a half-bridge switch arm, a resonant inductor, a first resonant capacitor and a second resonant capacitor; the positive and negative ends of the half-bridge switch arm are respectively coupled to the DC bus and the ground; the anode of the second diode is coupled to the output end of the input rectifier and filter circuit, and the cathode is coupled to the anode of the third diode; the cathode of the third diode is coupled to the DC bus; the common end of the second diode and the third diode is grounded through the pump capacitor, and is connected to the midpoint of the half-bridge switch arm through the first resonant capacitor and the resonant inductor; the anode of the fourth diode is coupled to the output end of the input rectifier and filter circuit, and the cathode is coupled to the anode of the fifth diode; the cathode of the fifth diode is coupled to the DC bus; the common end of the fourth diode and the fifth diode is connected to the midpoint of the half-bridge switch arm through the second resonant capacitor and the resonant inductor.

[0017] Preferably, the first target PFC voltage is greater than or equal to 250V and less than or equal to 270V.

[0018] The present invention also provides a PFC controller for a power converter. The power converter includes an input rectifier and filter circuit, an active PFC circuit, an LLC resonant conversion circuit, and an output rectifier and filter circuit. The active PFC circuit includes a PFC boost circuit and the PFC controller. The input rectifier and filter circuit rectifies and filters an AC power supply to form an intermediate DC power supply. The power converter also includes a charge pump PFC circuit. The charge pump PFC circuit and the active PFC circuit are both coupled to the output end of the input rectifier and filter circuit, a DC bus, and the LLC resonant conversion circuit.

[0019] The PFC controller detects the voltage of the intermediate DC power supply.

[0020] When the voltage of the intermediate DC power supply is less than a threshold voltage, the PFC controller controls the PFC boost circuit to maintain the voltage on the DC bus at a first target PFC voltage using the intermediate DC power supply, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectifier and filter circuit rectifies and filters the intermediate AC power supply into an output DC power supply for a DC load, and the charge pump PFC circuit, driven by the resonant current generated by the LLC resonant conversion circuit, can charge the DC bus.

[0021] When the voltage of the intermediate DC power supply is greater than the threshold voltage, the PFC controller controls the PFC boost circuit to stop operating, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectifier and filter circuit rectifies and filters the intermediate AC power supply into an output DC power supply for the DC load, and the charge pump PFC circuit, driven by the resonant current generated by the LLC resonant conversion circuit, maintains the voltage on the DC bus at a second target PFC voltage, wherein the second target PFC voltage is greater than the first target PFC voltage, and the first target PFC voltage is greater than the threshold voltage.

[0022] Preferably, the power converter further includes a first diode, wherein an anode of the first diode is coupled to the output end of the input rectifier filter circuit, and a cathode of the first diode is coupled to the DC bus.

[0023] Preferably, the charge pump PFC circuit includes a second diode, a third diode and a pump capacitor; the LLC resonant conversion circuit includes a half-bridge switch arm and a resonant element; the positive and negative ends of the half-bridge switch arm are respectively coupled to the DC bus and the ground; the anode of the second diode is coupled to the output end of the input rectifier filter circuit, and the cathode is coupled to the anode of the third diode; the cathode of the third diode is coupled to the DC bus; the common end of the second diode and the third diode is grounded through the pump capacitor, and is connected to the midpoint of the half-bridge switch arm through the resonant element.

[0024] Preferably, the charge pump PFC circuit includes a second diode, a third diode, a fourth diode, a fifth diode and a pump capacitor; the LLC resonant conversion circuit includes a half-bridge switch arm, a resonant inductor, a first resonant capacitor and a second resonant capacitor; the positive and negative ends of the half-bridge switch arm are respectively coupled to the DC bus and the ground; the anode of the second diode is coupled to the output end of the input rectifier and filter circuit, and the cathode is coupled to the anode of the third diode; the cathode of the third diode is coupled to the DC bus; the common end of the second diode and the third diode is grounded through the pump capacitor, and is connected to the midpoint of the half-bridge switch arm through the first resonant capacitor and the resonant inductor; the anode of the fourth diode is coupled to the output end of the input rectifier and filter circuit, and the cathode is coupled to the anode of the fifth diode; the cathode of the fifth diode is coupled to the DC bus; the common end of the fourth diode and the fifth diode is connected to the midpoint of the half-bridge switch arm through the second resonant capacitor and the resonant inductor.

[0025] Preferably, the first target PFC voltage is greater than or equal to 250V and less than or equal to 270V.

[0026] The present invention also provides a circuit board comprising any one of the power converters.

[0027] The present invention also provides an LED adapter, comprising any one of the above-mentioned power converters.

[0028] The present invention also provides an electronic device comprising any one of the above-mentioned power converters.

[0029] In the above solution, two different PFC circuits, an active PFC circuit and a charge pump PFC circuit, are provided in the power converter. The conversion circuit is selected as an LLC resonant conversion circuit suitable for both the active PFC circuit and the charge pump PFC circuit. The PFC controller in the active PFC circuit coordinates the operation of the PFC boost circuit and the charge pump PFC circuit in the active PFC circuit. When the intermediate DC power supply voltage detected by the PFC controller is lower than the threshold voltage (indicating that the power converter is used in an area with a low effective value of the AC voltage), the PFC boost circuit is controlled to maintain the voltage VB on the DC bus at the first target PFC voltage. The charge pump PFC circuit is "attached" When used in regions with low AC voltage RMS values, the power converter can perform power factor correction using the active PFC circuit's PFC boost circuit, which operates stably and relatively efficiently when the AC voltage RMS is low. When the intermediate DC power supply voltage detected by the PFC controller is greater than the threshold voltage (indicating that the power converter is being used in regions with high AC voltage RMS values), the PFC boost circuit is controlled to stop operating and the charge pump PFC circuit is controlled to operate. This shows that when used in regions with high AC voltage RMS values, the power converter can perform power factor correction using the charge pump PFC circuit, which operates relatively efficiently when the AC voltage RMS is high. Thus, the power converter can not only be used under different common AC voltage RMS values ​​in various regions of the world, but can also perform power factor correction relatively efficiently.

[0030] Other beneficial effects of the present invention will be explained through the introduction of specific technical features and technical solutions in the specific implementation methods. Those skilled in the art should be able to understand the beneficial technical effects brought about by the introduction of these technical features and technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0032] Figure 1 This is a circuit diagram of a power converter using a charge pump PFC circuit in the prior art;

[0033] Figure 2 This is a circuit diagram of a power converter using an active PFC circuit and an LLC resonant conversion circuit in the prior art;

[0034] Figure 3 A power converter according to a preferred embodiment of the present invention;

[0035] Figure 4 A power converter according to another preferred embodiment of the present invention;

[0036] Figure 5 This is a power converter according to another preferred embodiment of the present invention. DETAILED DESCRIPTION

[0037] The present invention is described below based on the following embodiments, but the present invention is not limited to these embodiments. In the following detailed description of the present invention, some specific details are described in detail. In order to avoid obscuring the essence of the present invention, well-known methods, processes, procedures, and components are not described in detail.

[0038] Furthermore, persons of ordinary skill in the art will appreciate that the figures provided herein are for illustration purposes only and are not necessarily drawn to scale.

[0039] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include," "comprising," and similar words should be construed in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to."

[0040] In the description of the present invention, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0041] like Figure 3 FIG. 1 shows a power converter according to an embodiment of the present invention, including an input rectifier and filter circuit 110 , an active PFC circuit 150 , a charge pump PFC circuit 120 , a DC bus, an LLC resonant conversion circuit 130 , and an output rectifier and filter circuit 140 . A bus capacitor with a relatively large capacity (such as a common electrolytic capacitor) is provided on the DC bus. The active PFC circuit 150 includes a PFC controller 152 and a PFC boost circuit 151 .

[0042] The input rectifier and filter circuit 110 rectifies and filters the AC power supply (AC) to form an intermediate DC power supply. This intermediate DC power supply is output from the output terminal of the input rectifier and filter circuit 110. The voltage of the intermediate DC power supply reflects the effective value of the AC power supply (AC). The greater the effective value of the AC power supply (AC), the greater the voltage of the intermediate DC power supply. Conversely, the smaller the effective value of the AC power supply (AC), the smaller the voltage of the intermediate DC power supply. As an example, the voltage of the intermediate DC power supply is approximately equal to 1.4 times the effective value of the AC power supply (AC). The input rectifier and filter circuit 110 includes a rectifier bridge B and a capacitor C1. Capacitor C1 is connected across the two output terminals of the rectifier bridge B. The two input terminals of the rectifier bridge are respectively coupled to the AC power supply (AC), for example, through a filter and an overcurrent protection device (such as a fuse).

[0043] The charge pump PFC circuit 120 and the active PFC circuit 150 are both coupled to the output terminal of the input rectifier and filter circuit 110 , the DC bus, and the LLC resonant conversion circuit 130 .

[0044] The PFC controller 152 detects the voltage of the intermediate DC power supply output by the input rectifier and filter circuit 110 and compares it with a threshold voltage (e.g., 200V, 210V, 220V, 230V, or 240V). Based on the comparison result, the PFC controller 152 controls the PFC boost circuit 151 differently. Under corresponding conditions, the PFC boost circuit 151 and the charge pump PFC circuit 120 of the active PFC circuit 150 are coordinated and controlled to achieve power factor correction.

[0045] When the detected voltage of the intermediate DC power supply is lower than the threshold voltage, the PFC controller 152 further detects the voltage VB on the DC bus and controls the PFC boost circuit 151 to use the intermediate DC power supply to maintain the voltage VB on the DC bus at a first target PFC voltage (which can be a single value or a range of values, such as 250V, 260V, 270V, 280V, 300V, 320V, or 250V-260V, or 260V-270V, or 270V-280V, etc.). The LLC resonant converter circuit 130 converts the voltage VB on the DC bus into an intermediate AC power supply, and the output rectifier and filter circuit 140 rectifies and filters the intermediate AC power supply into an output DC power supply for use by the DC load. In the above process, the LLC resonant converter circuit 130 will Driven by the resonant current generated by the LLC resonant conversion circuit 130, the charge pump PFC circuit 120 can charge the bus capacitor on the DC bus. However, during this process, the DC bus voltage VB is maintained at the first target PFC voltage independently of the operation of the charge pump PFC circuit 120. Rather, it is precisely because the PFC boost circuit 151 maintains the DC bus voltage VB at the first target PFC voltage, enabling stable circuit operation, that the charge pump PFC circuit 120 can operate stably "incidentally." This "incidentally" stable operation of the charge pump PFC circuit 120 does not affect the normal operation of the PFC boost circuit 151. Therefore, during this process, no additional control circuit is required to shut down the charge pump PFC circuit 120, thereby simplifying the circuit design. Thus, in this case, the PFC boost circuit 151 in the active PFC circuit 150 maintains the DC bus voltage VB at the first target PFC voltage, while the charge pump PFC circuit 120 operates only "incidentally."

[0046] When the detected voltage of the intermediate DC power supply is greater than the threshold voltage, the PFC controller 152 controls the PFC boost circuit 151 to stop operating. The PFC controller 152 no longer detects the voltage VB on the DC bus. The LLC resonant conversion circuit 130 converts the voltage VB on the DC bus into an intermediate AC power supply. The output rectifier and filter circuit 140 rectifies and filters the intermediate AC power supply into an output DC power supply for the DC load. During the above process, the LLC resonant conversion circuit 130 generates a resonant current. Driven by the resonant current generated by the LLC resonant conversion circuit 130, the charge pump PFC circuit 120 maintains the voltage VB on the DC bus at a second target PFC voltage (which can be either a numerical value or a numerical range). The second target PFC voltage is greater than the first target PFC voltage, and the first target PFC voltage is greater than the threshold voltage. The second target PFC voltage can be 380 V, 390 V, or 400 V, or 380 V-390 V, or 390 V-400 V, etc. It can be seen that in this case, only the charge pump PFC circuit 120 works to perform power factor correction, while the PFC boost circuit 151 in the active PFC circuit 150 stops working.

[0047] In this embodiment, the power converter is provided with two different PFC circuits, an active PFC circuit 150 and a charge pump PFC circuit 120. The conversion circuit is selected as an LLC resonant conversion circuit suitable for both the active PFC circuit and the charge pump PFC circuit. The PFC controller 152 in the active PFC circuit 150 coordinates and controls the operation of the PFC boost circuit 151 and the charge pump PFC circuit 120 in the active PFC circuit 150. When the intermediate DC power supply voltage detected by the PFC controller 152 is lower than a threshold voltage (indicating that the power converter is currently used in an area with a low effective AC voltage), the PFC boost circuit 151 is controlled to maintain the voltage VB on the DC bus at a first target PFC voltage, and the charge pump PFC circuit 120 is controlled to maintain the voltage VB on the DC bus at a first target PFC voltage. Circuit 120 operates "in addition," indicating that when used in regions with low AC voltage RMS values, the power converter can perform power factor correction using the PFC boost circuit 151 of the active PFC circuit 150, which operates stably and relatively efficiently under low AC voltage RMS values. When the intermediate DC power supply voltage detected by the PFC controller 152 is greater than the threshold voltage (indicating that the power converter is being used in a region with a high AC voltage RMS value), the PFC boost circuit 151 is controlled to stop operating and the charge pump PFC circuit 120 is controlled to operate. This indicates that when used in regions with high AC voltage RMS values, the power converter can perform power factor correction using the charge pump PFC circuit, which operates relatively efficiently under high AC voltage RMS values. Thus, the power converter can not only be used under the various common AC voltage RMS values ​​found in various regions of the world, but can also perform power factor correction with relative efficiency.

[0048] Since the PFC boost circuit 151 of the active PFC circuit 150 operates only in regions with a low effective value of the AC voltage, the switches and inductors in the PFC boost circuit 151 do not need to have a higher rated power and a larger volume, thereby reducing the cost. Furthermore, the diodes and capacitors typically used in the charge pump PFC circuit 120 provided in the power converter are relatively small in volume and cost, thus not adding to the overall cost of the power converter.

[0049] In addition, the PFC controller 152 uses the DC power supply voltage detected from the output end of the input rectifier and filter circuit 110 as the effective value of the AC power supply AC, rather than directly detecting the effective value of the AC power supply AC at the input end of the input rectifier and filter circuit 110. This fully utilizes the rectification and filtering function of the input rectifier and filter circuit 110, simplifies the detection circuit while achieving the detection purpose.

[0050] like Figure 4 , is a power converter according to another embodiment of the present invention, further comprising a first diode D1 , wherein the anode of the first diode D1 is coupled to the output end of the input rectifier filter circuit 110 , and the cathode of the first diode D1 is coupled to the DC bus. When the power converter is used in an area with a low effective value of the AC voltage, at the moment the power converter is powered on, the output end of the input rectifier and filter circuit 110 can be quickly charged to the bus capacitor C2 via the first diode D1 to a voltage equal to the output end voltage of the input rectifier and filter circuit 110. This allows the PFC boost circuit 151 of the active PFC circuit 150 to boost the voltage based on the output end voltage of the input rectifier and filter circuit 110 to a first target PFC voltage, thereby improving the response speed of the PFC boost circuit 151 of the active PFC circuit 150. When the power converter is used in an area with a high effective value of the AC voltage, at the moment the power converter is powered on, the output end of the input rectifier and filter circuit 110 can also be quickly charged to the bus capacitor C2 via the first diode D1 to a voltage equal to the output end voltage of the input rectifier and filter circuit 110. This allows the charge pump PFC circuit 120 to boost the voltage based on the output end voltage of the input rectifier and filter circuit 110 to a second target PFC voltage, thereby also improving the response speed of the charge pump PFC circuit 120. It can be seen that the provision of the first diode D1 promotes the PFC boost circuit 151 of the active PFC circuit 150 and the charge pump PFC circuit 120 .

[0051] like Figure 4As shown, the charge pump PFC circuit 120 includes a second diode D2, a third diode D3 and a pump capacitor C3; the LLC resonant conversion circuit 130 includes a half-bridge switch arm (composed of switch tubes Q2 and Q3), a controller 131, and a resonant element; the positive and negative ends of the half-bridge switch arm are coupled to the DC bus and ground respectively; the anode of the second diode D2 is coupled to the output end of the input rectifier filter circuit 110, and the cathode is coupled to the anode of the third diode D3; the cathode of the third diode D3 is coupled to the DC bus; the common end of the second diode D2 and the third diode D3 is grounded through the pump capacitor C3, and is connected to the midpoint of the half-bridge switch arm, i.e., the common end of the switch tubes Q2 and Q3, through the resonant element. The controller 131 controls the conduction and shutdown of the switch tubes Q2 and Q3. Among them, the resonant element includes a resonant inductor L2 and a resonant capacitor C4. Figure 4 The series LLC resonant converter circuit 130 shown in FIG. includes a resonant inductor L2 and a resonant capacitor C4 connected in series. Once the series LLC is formed, the positions of the resonant inductor L2, resonant capacitor C4, and the primary side of the transformer T can be adjusted. The resonant inductor L2 can be an independent inductor from the transformer T, or an equivalent resonant inductor L2 can be formed by designing a leakage inductance within the transformer T. In this case, the power converter does not physically have the resonant inductor L2. A controller 131 controls the on / off switching of switches Q2 and Q3, which, in conjunction with the resonant elements, enables the LLC resonant converter circuit 130 to generate a resonant current, thereby driving the charge pump PFC circuit 120. In this embodiment, only one resonant circuit is present.

[0052] The following Figure 4The working process of the charge pump PFC circuit 120 shown in FIG. 1 is briefly described. (1) Phase 1: When both the switch tubes Q2 and Q3 are turned off (the stage before the switch tube Q2 is about to turn on), the current flows through the circuit: resonant inductor L2-body diode of the switch tube Q2-bus capacitor C2-capacitor C1-second diode D2-resonant capacitor C4-primary side of the transformer T-resonant inductor L2. In this process, the resonant current charges the bus capacitor C2. (2) Phase 2: When the switch tube Q2 is turned on and the switch tube Q3 is turned off, the current flows through the circuit: bus capacitor C2-switch tube Q2-resonant inductor L2-primary side of the transformer T-resonant capacitor C4-pump capacitor C3-bus capacitor C2. In this process, the bus capacitor C2 is discharged to the outside. (3) Phase 3: The switch tube Q2 continues to be turned on and the switch tube Q3 continues to be turned off. The current flows through the circuit: resonant capacitor C4-third diode D3-switch tube Q2-resonant inductor L2-transformer T The primary side of the transformer T - the resonant capacitor C4; (4) Stage 4: When both the switch tubes Q2 and Q3 are turned off (the stage before the switch tube Q3 is about to be turned on), the current flows through the circuit: resonant inductor L2 - the primary side of the transformer T - the resonant capacitor C4 - the third diode D3 - the bus capacitor C2 - the body diode of the switch tube Q3 - the resonant inductor L2. In this process, the resonant current charges the bus capacitor C2; (5) Stage 5: When the switch tube Q3 is turned on and the switch tube Q2 is turned off, the current flows through the circuit: pump capacitor C3 - resonant capacitor C4 - the primary side of the transformer T - the resonant inductor L2 - the switch tube Q3 - pump capacitor C3: (6) Stage 6: The switch tube Q3 continues to be turned on and the switch tube Q2 continues to be turned off. The current flows through the circuit: capacitor C1 - the second diode D2 - resonant capacitor C4 - the primary side of the transformer T - the resonant inductor L2 - the switch tube Q3 - capacitor C1.

[0053] The active PFC circuit 150 includes a PFC controller 152 and a PFC boost circuit 151. The PFC boost circuit 151 includes a boost inductor L1, a boost diode D0, and a boost switch Q1. The anode of the boost diode D0 is coupled to the output terminal of the input rectifier and filter circuit 110 via the boost inductor L1, and the cathode of the boost diode D0 is coupled to the DC bus. The common terminal of the boost inductor L1 and the boost diode D0 is grounded via the boost switch Q1. One voltage detection terminal of the PFC controller 152 is connected to the output terminal of the input rectifier and filter circuit 110 to detect the voltage of the intermediate DC power supply, and the other voltage detection terminal is connected to the DC bus to detect the voltage of the DC bus. The control terminal of the PFC controller 152 is connected to the control terminal of the boost switch Q1.

[0054] like Figure 5 FIG. 1 is a power converter according to another embodiment of the present invention, which adopts the Figure 4Different charge pump PFC circuits (compared to Figure 4 The charge pump PFC circuit has a fourth diode D4, a fifth diode D5) and an LLC resonant conversion circuit (compared to Figure 4 The LLC resonant conversion circuit has an additional second resonant capacitor C5 for the convenience of description).

[0055] The charge pump PFC circuit includes a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5 and a pump capacitor C3; the LLC resonant conversion circuit includes a half-bridge switch arm (including switch tubes Q2 and Q3), a resonant inductor L2, a first resonant capacitor C4, and a second resonant capacitor C5; the positive end and the negative end of the half-bridge switch arm are coupled to the DC bus and the ground respectively; the anode of the second diode D2 is coupled to the output end of the input rectifier filter circuit, and the cathode is coupled to the anode of the third diode D3; the cathode of the third diode D3 is coupled to the DC bus. bus; the common end of the second diode D2 and the third diode D3 is grounded through the pump capacitor C3, and is connected to the midpoint of the half-bridge switch arm (the common end of the switch tubes Q2 and Q3) through the first resonant capacitor C4 and the resonant inductor L2; the anode of the fourth diode D4 is coupled to the output end of the input rectifier and filter circuit, and the cathode is coupled to the anode of the fifth diode D5; the cathode of the fifth diode D5 is coupled to the DC bus; the common end of the fourth diode D4 and the fifth diode D5 is connected to the midpoint of the half-bridge switch arm through the second resonant capacitor C5 and the resonant inductor L2.

[0056] The following Figure 5The working process of the charge pump PFC circuit 120 shown is briefly described. (1) Phase 1: When both the switches Q2 and Q3 are turned off (the stage before the switch Q2 is about to turn on), the current flows through two loops. One loop is: resonant inductor L2-body diode of the switch Q2-bus capacitor C2-capacitor C1-second diode D2-first resonant capacitor C4-primary side of the transformer T-resonant inductor L2, and the other loop is: resonant inductor L2-body diode of the switch Q2-bus capacitor C2-capacitor C1-fourth diode D4-second resonant capacitor C5-primary side of the transformer T-resonant inductor L2. In this process, the resonant current charges the bus capacitor C2; (2) Phase 2 : When the switch tube Q2 is turned on and the switch tube Q3 is turned off, the current flows through two loops. One loop is: bus capacitor C2-switch tube Q2-resonant inductor L2-primary side of transformer T-first resonant capacitor C4-pump capacitor C3-bus capacitor C2. The other loop is: switch tube Q2-resonant inductor L2-primary side of transformer T-second resonant capacitor C5-fifth diode D5-switch tube Q2. In this process, the bus capacitor C2 is discharged to the outside. (3) Phase 3: The switch tube Q2 continues to be turned on and the switch tube Q3 continues to be turned off. The current flows through two loops. One loop is: first resonant capacitor C4-fifth The third circuit is: diode D3 - switch tube Q2 - resonant inductor L2 - primary side of transformer T - first resonant capacitor C4, and the other circuit is: second resonant capacitor C5 - fifth diode D5 - switch tube Q2 - resonant inductor L2 - primary side of transformer T - second resonant capacitor C5; (4) Stage 4: When both switch tubes Q2 and Q3 are turned off (the stage before switch tube Q3 is about to turn on), the current flows through two circuits, one circuit is: resonant inductor L2 - primary side of transformer T - first resonant capacitor C4 - third diode D3 - bus capacitor C2 - body diode of switch tube Q3 - resonant inductor L2, and the other circuit is: resonant inductor L2-primary side of transformer T-second resonant capacitor C5-fifth diode D5-bus capacitor C2-body diode of switch tube Q3-resonant inductor L2. In this process, the resonant current charges the bus capacitor C2. (5) Stage 5: When switch tube Q3 is on and switch tube Q2 is off, the current flows through two loops. One loop is: pump capacitor C3-first resonant capacitor C4-primary side of transformer T-resonant inductor L2-switch tube Q3-pump capacitor C3. The other loop is: capacitor C1-fourth diode D4-second resonant capacitor C5-primary side of transformer T-resonant inductor L2-switch tube Q3-capacitor C1.(6) Phase 6: The switch Q3 remains on and the switch Q2 remains off. The current flows through two loops: one loop is: capacitor C1 - second diode D2 - first resonant capacitor C4 - primary side of transformer T - resonant inductor L2 - switch Q3 - capacitor C1; the other loop is: capacitor C1 - fourth diode D4 - second resonant capacitor C5 - primary side of transformer T - resonant inductor L2 - switch Q3 - capacitor C1.

[0057] The present invention also provides a circuit board including any power converter. The circuit board can be assembled on any component or device that can provide output DC power to a DC load (such as an LED).

[0058] The present invention also provides an LED adapter, including any power converter. The LED adapter may include a housing, and the power converter is arranged in the housing to provide a DC power supply for an LED serving as a DC load.

[0059] The present invention further provides an electronic device, including any power converter. The electronic device may further include a DC load (such as an LED), and the power converter provides an output DC power supply for the DC load.

[0060] Those skilled in the art will appreciate that, provided there is no conflict, the above preferred solutions can be freely combined and superimposed.

[0061] It should be understood that the above-mentioned embodiments are merely illustrative and non-restrictive. Without departing from the basic principles of the present invention, various obvious or equivalent modifications or substitutions that can be made by those skilled in the art to the above-mentioned details will be included in the scope of the claims of the present invention.

Claims

1. A power converter comprising an input rectifier and filter circuit, an active PFC circuit, an LLC resonant converter circuit, and an output rectifier and filter circuit, wherein the active PFC circuit comprises a PFC controller and a PFC boost circuit, and the input rectifier and filter circuit rectifies and filters an AC power supply to form an intermediate DC power supply, characterized in that: The power converter further includes a charge pump PFC circuit and a first diode, wherein the anode of the first diode is coupled to the output end of the input rectifier filter circuit, and the cathode of the first diode is coupled to the DC bus; The charge pump PFC circuit and the active PFC circuit are both coupled to the output end of the input rectifier filter circuit, the DC bus and the LLC resonant conversion circuit; The PFC controller detects the voltage of the intermediate DC power supply. When the voltage of the intermediate DC power supply is less than a threshold voltage, the PFC controller controls the PFC boost circuit to maintain the voltage on the DC bus at a first target PFC voltage using the intermediate DC power supply, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectifier and filter circuit rectifies and filters the intermediate AC power supply into an output DC power supply for a DC load, and the charge pump PFC circuit, driven by the resonant current generated by the LLC resonant conversion circuit, can charge the DC bus. When the voltage of the intermediate DC power supply is greater than the threshold voltage, the PFC controller controls the PFC boost circuit to stop operating, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectifier and filter circuit rectifies and filters the intermediate AC power supply into an output DC power supply for the DC load, and the charge pump PFC circuit maintains the voltage on the DC bus at a second target PFC voltage under the drive of the resonant current generated by the LLC resonant conversion circuit. The charge pump PFC circuit boosts the voltage of the output terminal of the input rectifier and filter circuit to a second target PFC voltage, wherein the second target PFC voltage is greater than the first target PFC voltage, and the first target PFC voltage is greater than the threshold voltage.

2. The power converter according to claim 1, wherein: The charge pump PFC circuit includes a second diode, a third diode and a pump capacitor; The LLC resonant conversion circuit includes a half-bridge switch arm and a resonant element; the positive end and the negative end of the half-bridge switch arm are coupled to the DC bus and the ground respectively; The anode of the second diode is coupled to the output end of the input rectifier filter circuit, and the cathode is coupled to the anode of the third diode; the cathode of the third diode is coupled to the DC bus; A common end of the second diode and the third diode is grounded through the pump capacitor and connected to the midpoint of the half-bridge switch arm through a resonant element.

3. The power converter according to claim 1, wherein: The charge pump PFC circuit includes a second diode, a third diode, a fourth diode, a fifth diode and a pump capacitor; The LLC resonant conversion circuit includes a half-bridge switch arm, a resonant inductor, a first resonant capacitor, and a second resonant capacitor; the positive end and the negative end of the half-bridge switch arm are coupled to the DC bus and the ground respectively; The anode of the second diode is coupled to the output end of the input rectifier filter circuit, and the cathode is coupled to the anode of the third diode; the cathode of the third diode is coupled to the DC bus; A common end of the second diode and the third diode is grounded through the pump capacitor and connected to the midpoint of the half-bridge switch arm through the first resonant capacitor and the resonant inductor; The anode of the fourth diode is coupled to the output end of the input rectifier filter circuit, and the cathode is coupled to the anode of the fifth diode; the cathode of the fifth diode is coupled to the DC bus; A common terminal of the fourth diode and the fifth diode is connected to a midpoint of the half-bridge switch arm through the second resonant capacitor and the resonant inductor.

4. A PFC controller for a power converter, comprising an input rectifier and filter circuit, an active PFC circuit, an LLC resonant conversion circuit, and an output rectifier and filter circuit. The active PFC circuit comprises a PFC boost circuit and the PFC controller. The input rectifier and filter circuit rectifies and filters an AC power supply to form an intermediate DC power supply. The power converter further includes a charge pump PFC circuit and a first diode, wherein the anode of the first diode is coupled to the output end of the input rectifier filter circuit, and the cathode of the first diode is coupled to the DC bus; The charge pump PFC circuit and the active PFC circuit are both coupled to the output end of the input rectifier filter circuit, the DC bus and the LLC resonant conversion circuit; The PFC controller detects the voltage of the intermediate DC power supply. When the voltage of the intermediate DC power supply is less than a threshold voltage, the PFC controller controls the PFC boost circuit to maintain the voltage on the DC bus at a first target PFC voltage using the intermediate DC power supply, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectifier and filter circuit rectifies and filters the intermediate AC power supply into an output DC power supply for a DC load, and the charge pump PFC circuit, driven by the resonant current generated by the LLC resonant conversion circuit, can charge the DC bus. When the voltage of the intermediate DC power supply is greater than the threshold voltage, the PFC controller controls the PFC boost circuit to stop operating, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectifier and filter circuit rectifies and filters the intermediate AC power supply into an output DC power supply for the DC load, and the charge pump PFC circuit maintains the voltage on the DC bus at a second target PFC voltage under the drive of the resonant current generated by the LLC resonant conversion circuit. The charge pump PFC circuit boosts the voltage of the output terminal of the input rectifier and filter circuit to a second target PFC voltage, wherein the second target PFC voltage is greater than the first target PFC voltage, and the first target PFC voltage is greater than the threshold voltage.

5. The PFC controller according to claim 4, wherein: The charge pump PFC circuit includes a second diode, a third diode and a pump capacitor; The LLC resonant conversion circuit includes a half-bridge switch arm and a resonant element; the positive end and the negative end of the half-bridge switch arm are coupled to the DC bus and the ground respectively; The anode of the second diode is coupled to the output end of the input rectifier filter circuit, and the cathode is coupled to the anode of the third diode; the cathode of the third diode is coupled to the DC bus; A common end of the second diode and the third diode is grounded through the pump capacitor and connected to the midpoint of the half-bridge switch arm through a resonant element.

6. The PFC controller according to claim 4, wherein: The charge pump PFC circuit includes a second diode, a third diode, a fourth diode, a fifth diode and a pump capacitor; The LLC resonant conversion circuit includes a half-bridge switch arm, a resonant inductor, a first resonant capacitor, and a second resonant capacitor; the positive end and the negative end of the half-bridge switch arm are coupled to the DC bus and the ground respectively; The anode of the second diode is coupled to the output end of the input rectifier filter circuit, and the cathode is coupled to the anode of the third diode; the cathode of the third diode is coupled to the DC bus; A common end of the second diode and the third diode is grounded through the pump capacitor and connected to the midpoint of the half-bridge switch arm through the first resonant capacitor and the resonant inductor; The anode of the fourth diode is coupled to the output end of the input rectifier filter circuit, and the cathode is coupled to the anode of the fifth diode; the cathode of the fifth diode is coupled to the DC bus; A common terminal of the fourth diode and the fifth diode is connected to a midpoint of the half-bridge switch arm through the second resonant capacitor and the resonant inductor.

7. A circuit board, characterized in that: The invention comprises a power converter as described in any one of claims 1 to 3.

8. An LED adapter, characterized in that: The invention comprises a power converter as described in any one of claims 1 to 3.

9. An electronic device, characterized in that: The invention comprises a power converter as described in any one of claims 1 to 3.

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