Power converter, PFC controller, circuit board, adapter and electronic equipment

Abstract

The 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 maintain the voltage on a DC bus at a first target PFC voltage by using the intermediate DC power supply, and when the voltage of the intermediate DC power supply is less than the threshold voltage, the PFC boost circuit boosts the voltage on the DC bus at a second target PFC voltage. The charge pump PFC circuit can charge a direct current bus under the driving of resonant current generated by the LLC resonant conversion circuit; and when the voltage of the intermediate DC power supply is greater than the threshold voltage, the PFC controller controls the PFC booster circuit to stop working, and the charge pump PFC circuit maintains the voltage on the DC bus at a second target PFC voltage under the driving of the resonant current generated by the LLC resonant conversion circuit. The power converter can be applied to various different regions in the world at present, and power factor correction can be carried out in a relatively efficient and low-cost manner.

Description

Technical Field

[0001] The present invention relates to the field of power supply, and in particular to a power converter, a PFC controller, a circuit board, an adapter and an electronic device. 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] Currently common PFC circuits include charge pump PFC circuits (such as those described in CN216414184U) and active PFC circuits (or APFC circuits). When a charge pump PFC circuit is used, the conversion circuit usually needs to use an LLC resonant conversion circuit to drive the charge pump PFC circuit, while the active PFC circuit generally uses a boost conversion circuit.

[0004] like Figure 1 As shown, it is a circuit diagram of a power converter using a charge pump PFC circuit 120, including an input rectifier filter circuit 110, a charge pump PFC circuit 120, an LLC resonant conversion circuit 130 and an output rectifier circuit 140, wherein the primary side of the transformer T is a component of the LLC resonant conversion circuit 130, 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 conversion circuit 130 drives the charge pump PFC circuit 120 to operate, so that the DC bus voltage is maintained at a certain designed target PFC voltage (which can be either a numerical value or a numerical range), and the output DC power Vo of the output rectifier circuit 140 is used for a DC load (such as an LED).

[0005] like Figure 2As shown, it is a circuit diagram of a power converter using an active PFC circuit 150 and an LLC resonant conversion circuit 130, including an input rectifier filter circuit 110, an active PFC circuit 150, an LLC resonant conversion circuit 130 and an output rectifier circuit 140, wherein 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, the target PFC voltage can be set in the PFC controller, the PFC controller detects the voltage of the DC bus, and the PFC controller 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 need to be used in countries or regions where the effective value of the AC input voltage is above 200V. The reason is that the charge pump PFC circuit needs to work with the LLC resonant conversion circuit. Under the current common AC voltage effective values ​​in the world (for example, 120V in the United States, 220V in China, and 200-264V in Europe), the LLC resonant conversion circuit usually requires that the effective value of the AC input voltage should be above 200V. Otherwise, if the effective value is lower than 200V, in order to maintain the output DC voltage constant, the switching frequency in the LLC resonant conversion circuit needs to be reduced. This frequency is easy to be reduced to below the critical point frequency, and the LLC resonant conversion circuit will enter the ZCS (zero current switching) working area, resulting in the switch in the LLC resonant conversion circuit cannot achieve ZVS (zero voltage switching), which leads to the problem of increased loss and reduced efficiency of the LLC resonant conversion circuit. What is more serious is that it will also cause problems such as instability of the LLC resonant conversion circuit loop. In short, the charge pump PFC circuit is limited by the input voltage. As far as actual products are concerned, 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 can work more stably within the current range of common AC voltage effective values ​​in the world, and have a wider application voltage range. In order to work as much as possible within the current range of common AC voltage effective values ​​in the world (for example, taking into account the US market of 100-277VAC and the European market of 200-264VAC input), some power converters using active PFC circuits set the target output voltage of the active PFC circuit to 400V or above. In this way, whether the power converter is applied to countries or regions with low AC input voltage (effective value less than 200V) or high AC input voltage (effective value above 200V), the active PFC circuit can perform power factor correction, so that the power factor (PF) and harmonic distortion THD of the power converter can meet the relevant requirements of the corresponding countries or regions. 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 a large AC input voltage (effective value above 200V), the duty cycle D of the BOOST circuit in the active PFC circuit will decrease, which will cause the active PFC circuit to fail to work properly, and then significantly reduce the power factor (PF) and deteriorate the 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 a small AC input voltage (effective value less than 200V), the duty cycle D of the BOOST circuit in the active PFC circuit will be larger, resulting in an increase in the effective value of the current in the BOOST circuit, thereby increasing the loss of the inductor and MOS (or other switch tubes) in the BOOST circuit, and the power conversion efficiency is low. In addition, in order to adapt to the larger current in the BOOST circuit, it is necessary to use MOS with a larger rated current and an inductor (larger in size) to achieve this, which further leads to the problem of rising 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 work within the effective value range of the common AC voltage in the world with high efficiency and low cost.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A power converter, comprising an input rectifying and filtering circuit, an active PFC circuit, an LLC resonant conversion circuit and an output rectifying and filtering circuit, wherein the active PFC circuit comprises a PFC controller and a PFC boost circuit, the input rectifying and filtering circuit rectifying and filtering an AC power supply to form an intermediate DC power supply, and the power converter further comprises a charge pump PFC circuit; the charge pump PFC circuit and the active PFC circuit are both coupled to an output end of the input rectifying and filtering circuit, a 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 the threshold voltage, the PFC controller controls the PFC boost circuit to maintain the voltage on the DC bus at the first target PFC voltage by 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 can charge the DC bus under the drive of the resonant current generated by the LLC resonant conversion circuit; 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 working, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectification and filtering 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, 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.

[0010] Preferably, the power converter further includes a first diode, an anode of the first diode is coupled to the output end of the input rectifier and filter circuit, and a cathode of the first diode is coupled to the DC bus.

[0011] 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 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 resonant element.

[0012] 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 end and the negative end 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.

[0013] Preferably, the first target PFC voltage is greater than or equal to 250V and less than or equal to 270V.

[0014] The present invention also provides a PFC controller for a power converter, the power converter comprising an input rectifier filter circuit, an active PFC circuit, an LLC resonant conversion circuit and an output rectifier filter circuit, the active PFC circuit comprising a PFC boost circuit and the PFC controller, the input rectifier filter circuit rectifies and filters an AC power supply to form an intermediate DC power supply, the power converter further comprising 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 filter circuit, a 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 the threshold voltage, the PFC controller controls the PFC boost circuit to maintain the voltage on the DC bus at the first target PFC voltage by 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 can charge the DC bus under the drive of the resonant current generated by the LLC resonant conversion circuit; 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 working, the LLC resonant conversion circuit converts the voltage on the DC bus into an intermediate AC power supply, the output rectification and filtering 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, 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.

[0015] Preferably, the power converter further includes a first diode, an anode of the first diode is coupled to the output end of the input rectifier and filter circuit, and a cathode of the first diode is coupled to the DC bus.

[0016] 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 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 resonant element.

[0017] 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 end and the negative end 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.

[0018] Preferably, the first target PFC voltage is greater than or equal to 250V and less than or equal to 270V.

[0019] The present invention also provides a circuit board, comprising any one of the power converters described above.

[0020] The present invention also provides an LED adapter, comprising any one of the power converters described above.

[0021] The present invention also provides an electronic device, comprising any one of the power converters described above.

[0022] In the above scheme, two different PFC circuits, namely, an active PFC circuit and a charge pump PFC circuit, are arranged 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 and controls 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 less than the threshold voltage (indicating that the power converter is applied to an area with a small effective value of the AC voltage at this time), 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" It can be seen that when the power converter is applied to areas with a small effective value of AC voltage, the power converter can perform power factor correction through the PFC boost circuit of the active PFC circuit that can work stably and relatively efficiently when the effective value of AC voltage is small; when the intermediate DC power supply voltage detected by the PFC controller is greater than the threshold voltage (indicating that the power converter is applied to an area with a large effective value of AC voltage at this time), the PFC boost circuit is controlled to stop working and the charge pump PFC circuit is controlled to work. It can be seen that when the power converter is applied to an area with a large effective value of AC voltage, the power converter can perform power factor correction through the charge pump PFC that can work relatively efficiently when the effective value of AC voltage is large. In this way, the power converter can not only be applied to different common effective values ​​of AC voltage in different regions of the world at present, but also can perform power factor correction relatively efficiently.

[0023] Other beneficial effects of the present invention will be explained in the specific implementation manner through the introduction of specific technical features and technical solutions. Through the introduction of these technical features and technical solutions, those skilled in the art should be able to understand the beneficial technical effects brought about by the technical features and technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Figure 1 It is a circuit diagram of a power converter using a charge pump PFC circuit in the prior art; Figure 2 It is a circuit diagram of a power converter using an active PFC circuit and an LLC resonant conversion circuit in the prior art; Figure 3A power converter according to a preferred embodiment of the present invention; Figure 4 A power converter according to another preferred embodiment of the present invention; Figure 5 A power converter according to another preferred embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention is described below based on 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 confusing the essence of the present invention, known methods, processes, procedures, and components are not described in detail.

[0026] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0027] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include", "comprising" and similar words should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0028] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0029] like Figure 3 As shown, a power converter according to an embodiment of the present invention includes 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 arranged on the DC bus. The active PFC circuit 150 includes a PFC controller 152 and a PFC boost circuit 151.

[0030] The input rectifier and filter circuit 110 rectifies and filters the AC power supply AC to form an intermediate DC power supply, that is, the output end of the input rectifier and filter circuit 110 outputs the intermediate DC power supply. The voltage of the intermediate DC power supply reflects the magnitude of the effective value of the AC power supply AC. The larger the effective value of the AC power supply AC, the larger 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. The capacitor C1 is connected across the two output ends of the rectifier bridge B. The two input ends of the rectifier bridge are respectively coupled to the AC power supply AC, for example, connected to the AC power supply AC through a filter and an overcurrent protection device (such as a fuse, etc.).

[0031] The charge pump PFC circuit 120 and the active PFC circuit 150 are both coupled to the output end of the input rectifying and filtering circuit 110 , the DC bus and the LLC resonant conversion circuit 130 .

[0032] The PFC controller 152 detects the voltage of the intermediate DC power supply output by the input rectifier filter circuit 110, and compares it with the threshold voltage (for example, 200V, 210V, 220V, 230V, 240V). According to different comparison results, the PFC controller 152 makes different controls on the PFC boost circuit 151, so as to coordinate and control the PFC boost circuit 151 and the charge pump PFC circuit 120 of the active PFC circuit 150 to work under corresponding conditions to play a power factor correction role.

[0033] When the detected voltage of the intermediate DC power supply is less 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 the first target PFC voltage (which can be a value or a value range, such as 250V, 260V, 270V, 280V, 300V, 320V, or 250V-260V, or 260V-270V, or 270V-280V, etc.), the LLC resonant conversion circuit 130 converts the voltage VB on the DC bus into the 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 conversion circuit 130 will The charge pump PFC circuit 120 generates a resonant current, and driven by the resonant current generated by the LLC resonant conversion circuit 130, the bus capacitor on the DC bus can be charged. However, in this process, the voltage VB on the DC bus is maintained at the first target PFC voltage and does not depend on the operation of the charge pump PFC circuit 120. On the contrary, it is precisely because the PFC boost circuit 151 maintains the voltage VB on the DC bus at the first target PFC voltage that the circuit operates stably, and the charge pump PFC circuit 120 can "incidentally" work stably, and the "incidentally" stable operation of the charge pump PFC circuit 120 will not affect the normal operation of the PFC boost circuit 151. Therefore, in this process, there is no need to add an additional control circuit to turn off the charge pump PFC circuit 120, thereby simplifying the circuit design. It can be seen that in this case, the PFC boost circuit 151 in the active PFC circuit 150 plays a role in maintaining the voltage VB on the DC bus at the first target PFC voltage, and the charge pump PFC circuit 120 only works "incidentally".

[0034] 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 working. The PFC controller 152 may no longer detect the voltage VB on the DC bus at this time. 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. The LLC resonant conversion circuit 130 generates a resonant current in the above process. 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 value or a range of values) driven by the resonant current generated by the LLC resonant conversion circuit 130. The second target PFC voltage is greater than the first target PFC voltage, the first target PFC voltage is greater than the threshold voltage, and the second target PFC voltage can be 380V, 390V, or 400V, or 380V-390V, or 390V-400V, 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.

[0035] In this embodiment, two different PFC circuits, an active PFC circuit 150 and a charge pump PFC circuit 120, 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 152 in the active PFC circuit 150 coordinates and controls the PFC boost circuit 151 and the charge pump PFC circuit 120 in the active PFC circuit 150 to work. When the intermediate DC power supply voltage detected by the PFC controller 152 is less than the threshold voltage (indicating that the power converter is applied to an area with a small effective value of the AC voltage at this time), the PFC boost circuit 151 is controlled to maintain the voltage VB on the DC bus at the first target PFC voltage, and the charge pump PFC circuit 120 is controlled to maintain the voltage VB on the DC bus at the first target PFC voltage. Circuit 120 works "in addition", which shows that when the power converter is applied to areas with a small effective value of AC voltage, the power converter can perform power factor correction through the PFC boost circuit 151 of the active PFC circuit 150 which can work stably and relatively efficiently when the effective value of AC voltage is small; 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 applied to an area with a large effective value of AC voltage at this time), the PFC boost circuit 151 is controlled to stop working, and the charge pump PFC circuit 120 is controlled to work. It can be seen that when the power converter is applied to an area with a large effective value of AC voltage, the power converter can perform power factor correction through the charge pump PFC which can work relatively efficiently when the effective value of AC voltage is large. In this way, the power converter can not only be applied to different common effective values ​​of AC voltage in different regions of the world at present, but also can perform power factor correction relatively efficiently.

[0036] Since the PFC boost circuit 151 of the active PFC circuit 150 only works in areas where the effective value of the AC voltage is small, the rated power and volume of the switches and inductors in the PFC boost circuit 151 do not need to be larger, thereby reducing the cost. In addition, the diodes and capacitors generally used in the charge pump PFC circuit 120 provided in the power converter are relatively small in volume and cost, therefore, generally, it will not bring more cost to the power converter.

[0037] 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, instead of directly detecting the effective value of the AC power supply AC at the input end of the input rectifier and filter circuit 110. This makes full use of the rectification and filtering function of the input rectifier and filter circuit 110, and simplifies the detection circuit while achieving the detection purpose.

[0038] 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 rectifying and filtering circuit 110 , and the cathode of the first diode D1 is coupled to the DC bus. When the power converter is applied to a region with a relatively small effective value of the AC voltage, at the moment of powering on the power converter, the output end of the input rectifying and filtering circuit 110 can be quickly charged to the bus capacitor C2 via the first diode D1 to a voltage that is the same as the output end voltage of the input rectifying and filtering circuit 110, so that the PFC boost circuit 151 of the active PFC circuit 150 can be boosted on the basis of the output end voltage of the input rectifying and filtering circuit 110 until the first target PFC voltage is reached, thereby improving the response speed of the PFC boost circuit 151 of the active PFC circuit 150; when the power converter is applied to a region with a relatively large effective value of the AC voltage, at the moment of powering on the power converter, the output end of the input rectifying and filtering circuit 110 can also be quickly charged to the bus capacitor C2 via the first diode D1 to a voltage that is the same as the output end voltage of the input rectifying and filtering circuit 110, thereby improving the charge pump PFC circuit 120 on the basis of the output end voltage of the input rectifying and filtering circuit 110 until the second target PFC voltage is reached, thereby improving the response speed of the charge pump PFC circuit 120. It can be seen that the provision of the first diode D1 achieves a promotion effect on the PFC boost circuit 151 of the active PFC circuit 150 and the charge pump PFC circuit 120 .

[0039] 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 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 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, and 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, a resonant capacitor C4, Figure 4 The series LLC resonant conversion circuit 130 shown in the figure has a resonant inductor L2 and a resonant capacitor C4 connected in series. As long as the series LLC is formed, the positions of the resonant inductor L2, the resonant capacitor C4 and the primary side of the transformer T can be adjusted. The resonant inductor L2 can be an inductor device independent of the transformer T, or a leakage inductance can be designed in the transformer T to form an equivalent resonant inductor L2. In this case, the power converter does not have the above-mentioned resonant inductor L2 in entity. The controller 131 controls the on and off of the switch tubes Q2 and Q3, and cooperates with the above-mentioned resonant element to enable the LLC resonant conversion circuit 130 to generate a resonant current, and then drive the charge pump PFC circuit 120 to work. In this embodiment, there is only one resonant loop.

[0040] 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 be turned 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 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 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 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.

[0041] The active PFC circuit 150 includes a PFC controller 152 and a PFC boost circuit 151, wherein 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 end of the input rectifier and filter circuit 110 through the boost inductor L1, the cathode of the boost diode D0 is coupled to the DC bus, the common end of the boost inductor L1 and the boost diode D0 is grounded through the boost switch Q1, one voltage detection end of the PFC controller 152 is connected to the output end of the input rectifier and filter circuit 110 to detect the voltage of the intermediate DC power supply, and the other voltage detection end is connected to the DC bus to detect the voltage of the DC bus, and the control end of the PFC controller 152 is connected to the control end of the boost switch Q1.

[0042] like Figure 5 FIG. 1 is a power converter of another embodiment of the present invention, in which the power converter adopts 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).

[0043] 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 respectively coupled to the DC bus and the ground; 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.

[0044] The following Figure 5The working process of the charge pump PFC circuit 120 shown is briefly described. (1) Stage 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 two loops, one loop is: resonant inductor L2-body diode of switch tube Q2-bus capacitor C2-capacitor C1-second diode D2-first resonant capacitor C4-primary side of transformer T-resonant inductor L2, and the other loop is: resonant inductor L2-body diode of switch tube Q2-bus capacitor C2-capacitor C1-fourth diode D4-second resonant capacitor C5-primary side of transformer T-resonant inductor L2. In this process, the resonant current charges the bus capacitor C2; (2) Stage 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, and 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 discharges to the outside; (3) Stage 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 turned on and switch tube Q2 is turned 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 tube Q3 continues to be turned on, and the switch tube Q2 continues to be turned off. There are two loops through which the current flows. One loop is: capacitor C1-second diode D2-first resonant capacitor C4-primary side of transformer T-resonant inductor L2-switch tube Q3-capacitor C1, and 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. ;

[0045] The present invention also provides a circuit board, including any power converter, and 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).

[0046] 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.

[0047] The present invention further provides an electronic device, including any power converter. The electronic device may also include a DC load (such as an LED), and the power converter provides an output DC power supply for the DC load.

[0048] Those skilled in the art will appreciate that, without conflict, the above-mentioned preferred solutions can be freely combined and superimposed.

[0049] It should be understood that the above-mentioned embodiments are merely illustrative and not 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 all 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 conversion 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 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 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 the threshold voltage, the PFC controller controls the PFC boost circuit to maintain the voltage on the DC bus at the first target PFC voltage by 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 can charge the DC bus under the drive of the resonant current generated by the LLC resonant conversion circuit; 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 working, 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 the second target PFC voltage under the drive of the resonant current generated by the LLC resonant conversion circuit. 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, characterized in that: It also includes a first diode, wherein the anode of the first diode is coupled to the output end of the input rectification and filtering circuit, and the cathode of the first diode is coupled to the DC bus.

3. The power converter according to claim 1, characterized in that: The charge pump PFC circuit includes a second diode, a third diode and a pump capacitor; The LLC resonant conversion circuit comprises a half-bridge switch arm and a resonant element; the positive end and the negative end 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 rectifying and filtering 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 middle point of the half-bridge switch arm through a resonant element.

4. The power converter according to claim 1, characterized in that: 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 comprises 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 rectifying and filtering 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 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 rectifying and filtering 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 end 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.

5. A PFC controller for a power converter, the power converter comprising an input rectifier filter circuit, an active PFC circuit, an LLC resonant conversion circuit and an output rectifier filter circuit, the active PFC circuit comprising a PFC boost circuit and the PFC controller, the input rectifier filter circuit rectifies and filters an AC power supply to form an intermediate DC power supply, characterized in that: 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 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 the threshold voltage, the PFC controller controls the PFC boost circuit to maintain the voltage on the DC bus at the first target PFC voltage by 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 can charge the DC bus under the drive of the resonant current generated by the LLC resonant conversion circuit; 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 working, 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 the second target PFC voltage under the drive of the resonant current generated by the LLC resonant conversion circuit. 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.

6. The PFC controller according to claim 5, characterized in that: The power converter further includes a first diode, wherein an anode of the first diode is coupled to the output end of the input rectifying and filtering circuit, and a cathode of the first diode is coupled to the DC bus.

7. The PFC controller according to claim 5, characterized in that: The charge pump PFC circuit includes a second diode, a third diode and a pump capacitor; The LLC resonant conversion circuit comprises a half-bridge switch arm and a resonant element; the positive end and the negative end 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 rectifying and filtering 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 middle point of the half-bridge switch arm through a resonant element.

8. The PFC controller according to claim 5, characterized in that: 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 comprises 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 rectifying and filtering 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 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 rectifying and filtering 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 end 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.

9. A circuit board, characterized in that: Comprising a power converter as described in any one of claims 1-4.

10. An LED adapter, characterized in that: Comprising a power converter as described in any one of claims 1-4.

11. An electronic device, characterized in that: Comprising a power converter as described in any one of claims 1-4.

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