Rectification circuit and ac / DC converter

Abstract

To downsize an AC / DC converter.SOLUTION: A first input terminal IN1 and a second input terminal IN2 receive an AC voltage VAC from an AC power source 2. A full-bridge circuit 210 includes two bidirectional switches Q3, Q4 which are high-side elements, and two rectifier diodes D1, D2 which are low-side elements. A smoothing capacitor C1 is connected with the full-bridge circuit 210. A controller 220 controls an on / off state of the bidirectional switches Q3, Q4 on the basis of the AC voltage VAC and a voltage VC1 between both ends of the smoothing capacitor C1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a rectifier circuit and an AC / DC converter. [Background technology]

[0002] AC / DC converters are used to supply power from commercial AC power sources to electronic devices. An AC / DC converter includes a rectifier circuit that rectifies the AC voltage, and a DC / DC converter that converts the output voltage of the rectifier circuit to a voltage level suitable for the load.

[0003] AC / DC converters of 75W or less that do not require power factor correction (PFC) typically use an AC rectifier circuit that combines a diode bridge and an electrolytic capacitor. In this configuration, the electrolytic capacitor generates a voltage that is approximately √2 times the AC input voltage. This means that it is necessary to select an electrolytic capacitor with a high voltage resistance of, for example, 400V. This electrolytic capacitor has been an obstacle to miniaturizing and reducing the cost of AC / DC converters. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2024-001433

[0005] [overview] The present disclosure has been made in light of these circumstances, and one of its exemplary purposes is to reduce the size of an AC / DC converter.

[0006] One aspect of the present disclosure relates to a rectifier circuit including: first and second input terminals for receiving an AC voltage generated by an AC power supply; a full-bridge circuit connected to the first and second input terminals and including a pair of high-side and low-side elements, one of which is configured as a bidirectional switch and the other of which is configured as a rectifier diode; a smoothing capacitor connected to the full-bridge circuit; and a controller for controlling the on / off of the bidirectional switch in response to the AC voltage and the voltage across the smoothing capacitor.

[0007] Any combination of the above elements, or mutual substitution of elements or expressions between methods, devices, systems, etc., are also valid aspects of the present invention or the present disclosure. Furthermore, the description in this section (Means for Solving the Problems) does not explain all essential features of the present invention, and therefore, subcombinations of the described features may also constitute the present invention. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram of an AC / DC converter according to an embodiment. [Figure 2] FIG. 2 is a waveform diagram illustrating the operation of the AC / DC converter of FIG. [Figure 3] FIG. 3 is a circuit diagram of an AC / DC converter according to the first modification.

[0009] [Detailed explanation] (Outline of the embodiment) A summary of some exemplary embodiments of the present disclosure is provided. This summary is intended to provide a simplified overview of some concepts of one or more embodiments in order to provide a basic understanding of the embodiments as a prelude to the more detailed description that follows. It is not intended to limit the scope of the invention or disclosure. This summary is not an exhaustive overview of all possible embodiments, and is not intended to identify key elements of all embodiments or to delineate the scope of some or all aspects. For convenience, the term "one embodiment" may refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed herein.

[0010] A rectifier circuit according to one embodiment includes: a first input terminal and a second input terminal that are to receive an AC voltage generated by an AC power supply; a full-bridge circuit that is connected to the first input terminal and the second input terminal and includes a pair of high-side elements and a pair of low-side elements, one of the pair of high-side elements and the pair of low-side elements being configured as a bidirectional switch and the other being configured as a rectifier diode; a smoothing capacitor connected to the full-bridge circuit; and a controller that controls the on / off of the bidirectional switch in accordance with the AC voltage and the voltage across the smoothing capacitor.

[0011] With this configuration, the voltage across the smoothing capacitor is clamped, thereby lowering the withstand voltage required of the smoothing capacitor. This allows a small electrolytic capacitor to be used as the smoothing capacitor, making it possible to reduce the size and cost of the device.

[0012] Furthermore, by replacing two of the four elements that make up the rectifier bridge circuit with bidirectional switches, it is possible to achieve both the rectification function and the function of clamping the voltage of the smoothing capacitor in a single circuit. This allows for a smaller circuit area than when the diode bridge circuit and voltage clamp circuit are configured separately. Furthermore, compared to when a diode bridge circuit is used as the rectifier bridge circuit, the on-resistance (voltage drop) is smaller, allowing for reduced losses.

[0013] In one embodiment, the pair of high-side devices may be bidirectional switches.

[0014] In one embodiment, the pair of low-side devices may be bidirectional switches.

[0015] An AC / DC converter according to one embodiment may include any of the rectifier circuits described above and a DC / DC converter connected to the rectifier circuit.

[0016] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and redundant explanations will be omitted as appropriate. Furthermore, the embodiments are examples and do not limit the disclosure and invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the disclosure and invention.

[0017] In this specification, "a state in which component A is connected to component B" includes not only a case in which component A and component B are directly physically connected to each other, but also a case in which component A and component B are indirectly connected to each other via other components that do not substantially affect the electrical connection between them or that do not impair the function or effect achieved by their connection.

[0018] Similarly, "a state in which component C is provided between component A and component B" includes not only cases in which components A and C, or components B and C, are directly connected, but also cases in which they are indirectly connected via other components that do not substantially affect the electrical connection state between them or impair the functions or effects achieved by their combination.

[0019] 1 is a circuit diagram of an AC / DC converter 100 according to an embodiment. The AC / DC converter 100 receives an AC voltage V AC DC voltage V OUT Convert to.

[0020] The AC / DC converter 100 includes a rectifier circuit 200 and a DC / DC converter 300 .

[0021] The rectifier circuit 200 outputs AC voltage V AC is full-wave rectified and smoothed to produce a DC input voltage V IN The DC / DC converter 300 converts the DC input voltage V IN , the DC output voltage V OUT Convert to.

[0022] The rectifier circuit 200 includes input terminals IN1 and IN2, a full-bridge circuit 210, a smoothing capacitor C1, and a controller 220.

[0023] The first input terminal IN1 and the second input terminal IN2 of the rectifier circuit 200 are connected to an AC power source 2, and an AC voltage V AC The full-bridge circuit 210 is connected to a first input terminal IN1 and a second input terminal IN2. The voltage of the first input terminal IN1 relative to the ground line 102 is V ACP , the voltage of the second input terminal IN2 with respect to the ground line 102 is V ACN The full-bridge circuit 210 includes two high-side devices, two low-side devices, and two gate drivers 212 and 214. In this example, the two low-side devices are rectifier diodes D1 and D2, and the two high-side devices are bidirectional switches Q3 and Q4. The gate driver 212 drives the bidirectional switch Q3 in response to a control signal S1p. The driver 214 drives the bidirectional switch Q4 in response to a control signal S1n.

[0024] The smoothing capacitor C1 is connected to the full bridge circuit 210.

[0025] The controller 220 controls the AC voltage V AC and the voltage V across the smoothing capacitor C1 C1 Specifically, the controller 220 generates control signals S1p and S1n in response to the AC voltage V ACThe controller 220 alternately turns on the bidirectional switches Q3 and Q4 for each half cycle of one cycle of the bidirectional switch Q3. After turning on the bidirectional switch Q3, the controller 220 controls the voltage V C1 is a predetermined threshold V TH After turning on the bidirectional switch Q4, the controller 220 turns off the bidirectional switch Q3 so that the voltage V of the smoothing capacitor C1 does not exceed C1 is a predetermined threshold V TH The bidirectional switch Q4 is turned off so that the current does not exceed .

[0026] The method for generating the control signal S1 by the controller 220 is not particularly limited, and the voltage V between both ends of the smoothing capacitor C1 C1 However, it is sufficient to generate it so that it does not exceed a certain threshold.

[0027] The controller 220 ACN <V C1 When this occurs, the controller 220 changes the control signal S1p to a level (for example, high) that turns on the bidirectional switch Q3. C1 >V TH When this happens, the control signal S1p is changed to a level (for example, low) that turns off the bidirectional switch Q3.

[0028] The controller 220 ACP <V C1 When this occurs, the controller 220 changes the control signal S1n to a level (for example, high) that turns on the bidirectional switch Q4. C1 >V TH When this happens, the control signal S1n is changed to a level (for example, low) that turns off the bidirectional switch Q4.

[0029] The above is the configuration of the rectifier circuit 200. Next, the DC / DC converter 300 will be described.

[0030] There are no particular limitations on the topology of the DC / DC converter 300, and an isolated or non-isolated converter can be used. For example, the DC / DC converter 300 may be an asymmetrical half-bridge (AHB) converter.

[0031] The DC / DC converter 300 includes a half-bridge circuit 310, a transformer T1, a resonant capacitor C2, a diode D3, an output capacitor C3, a controller 320, and a gate driver 330. The half-bridge circuit 310 includes a high-side transistor Q1 and a low-side transistor Q2. The controller 320 controls the output voltage V OUT The gate driver 330 generates a control signal S2, which is a pulse signal, so that the gate voltage V of the high-side transistor Q1 and the low-side transistor Q2 approaches a target level. The method for generating the control signal S2 is not particularly limited, and pulse width modulation, pulse frequency modulation, etc. may be used. The gate driver 330 controls the gate voltage V of the high-side transistor Q1 and the low-side transistor Q2 in response to the control signal S2. G1 ,V G2 occurs.

[0032] The controller 220 and gate drivers 212 and 214 on the rectifier circuit 200 side and the controller 320 and gate driver 330 on the DC / DC converter 300 side may be integrated on a single semiconductor substrate to form a control IC (Integrated Circuit). The controller 220, the controller 320, and the gate driver 330 are connected to the ground line 102 common to the rectifier circuit 200, and operate based on a common reference voltage (ground voltage).

[0033] The above is the configuration of the AC / DC converter 100. Next, the operation thereof will be described.

[0034] 2 is a waveform diagram illustrating the operation of the AC / DC converter 100 of FIG. 2. In FIG. 2, from the top, the voltage V ACP , V ACN and the voltage V of the smoothing capacitor C1 C1 (Input voltage V IN), the charging current I flowing through the smoothing capacitor C1 C , a control signal S1p that instructs the bidirectional switch Q3 to be turned on or off, and a control signal S1n that instructs the bidirectional switch Q4 to be turned on or off are shown.

[0035] At time t0, V ACN <V C1 When this occurs, the control signal S1p becomes high and the bidirectional switch Q3 turns on. ONP At time t1, V ACP >V C1 Then, the charging current I C flows and charges the smoothing capacitor C1, and the voltage V C1 is the voltage V ACP It rises following the

[0036] At time t2, the voltage V C1 is the threshold voltage V TH When this occurs, the control signal S1p goes low and the bidirectional switch Q3 turns off.

[0037] At time t3, V ACP <V C1 When this occurs, the control signal S1n becomes high and the bidirectional switch Q4 turns on. ONN At time t4, V ACN >V C1 Then, the charging current I C flows and charges the smoothing capacitor C1, and the voltage V C1 is the voltage V ACN It rises following the

[0038] At time t5, the voltage V C1 is the threshold voltage V TH When this occurs, the control signal S1n goes low and the bidirectional switch Q4 turns off.

[0039] The period T when both the bidirectional switches Q3 and Q4 are off OFFThe smoothing capacitor C1 is discharged by the input current of the DC / DC converter 300 and decreases over time.

[0040] This is the operation of the AC / DC converter 100. In this AC / DC converter 100, the voltage V across the smoothing capacitor C1 C1 By clamping the smoothing capacitor C1, the withstand voltage required for the smoothing capacitor C1 can be lowered. This allows the use of a small electrolytic capacitor as the smoothing capacitor C1, making it possible to reduce the size and cost of the device.

[0041] Furthermore, by replacing two of the four elements that make up the rectifier bridge circuit with bidirectional switches, the rectification function and the function of clamping the voltage of the smoothing capacitor can be realized in a single circuit, which makes it possible to reduce the circuit area compared to when the diode bridge circuit and voltage clamp circuit are configured separately.

[0042] Furthermore, compared to when a diode bridge circuit is used as the rectifier bridge circuit, the on-resistance (voltage drop) is smaller, which reduces loss.

[0043] Although the embodiments of the present disclosure have been described using specific terms, this description is merely an example to facilitate understanding and does not limit the scope of the present disclosure or the claims, and the scope of the present invention is defined by the claims. Furthermore, not only the embodiments but also embodiments, examples, and modifications not described herein are included in the scope of the present invention.

[0044] (Variation 1) 3 is a circuit diagram of an AC / DC converter 100A according to Modification 1. The DC / DC converter 300 at the subsequent stage is the same as that in FIG.

[0045] The following describes the differences between the rectifier circuit 200A in Fig. 3 and the rectifier circuit 200 in Fig. 1. In Fig. 3, in the full bridge circuit 210, the low-side elements are bidirectional switches Q3 and Q4, and the high-side elements are rectifier diodes D1 and D2.

[0046] In this configuration, the sources of the bidirectional switches Q3 and Q4 are connected to the ground line 102 and have a fixed potential. Therefore, the gate drivers 212 and 214 that drive the bidirectional switches Q3 and Q4 can have a simple, non-insulated configuration.

[0047] (Variation 2) The circuit topology of the DC / DC converter 300 is not particularly limited, and can be selected to suit the power and application of the AC / DC converter 100. For example, the DC / DC converter 300 may be a flyback converter, a forward converter, or a full-bridge converter. In applications that do not require isolation, the DC / DC converter 300 can be a non-insulated converter such as a buck converter, a boost converter, or a buck-boost converter.

[0048] (Addendum) One aspect of the technology disclosed in this specification can be understood as follows.

[0049] (Item 1) a first input terminal and a second input terminal for receiving an AC voltage generated by an AC power supply; a full bridge circuit connected to the first input terminal and the second input terminal, including a pair of high-side elements and a pair of low-side elements, one of the pair of high-side elements and the pair of low-side elements being configured with a bidirectional switch and the other being configured with a rectifier diode; a smoothing capacitor connected to the full bridge circuit; a controller that controls the on / off of the bidirectional switch in accordance with the AC voltage and the voltage across the smoothing capacitor; A rectifier circuit comprising:

[0050] (Item 2) Item 2. The rectifier circuit of item 1, wherein the pair of high-side elements is configured as a bidirectional switch.

[0051] (Item 3) Item 1. The rectifier circuit according to item 1, wherein the pair of low-side elements is configured as a bidirectional switch.

[0052] (Item 4) A rectifier circuit according to any one of items 1 to 3; a DC / DC converter connected to the rectifier circuit; An AC / DC converter comprising: [Explanation of symbols]

[0053] 2...AC power supply, 100...AC / DC converter, 102...ground line, 200...rectifier circuit, 210...full bridge circuit, 212...gate driver, Q3, Q4...bidirectional switch, C1...smoothing capacitor, D1...rectifier diode, 220...controller, C2...resonant capacitor, C3...output capacitor, T1...transformer, Q1...high-side transistor, Q2...low-side transistor, 300...DC / DC converter, 310...half bridge circuit, S1...control signal, 320...controller, 330...gate driver

Claims

1. a first input terminal and a second input terminal for receiving an AC voltage generated by an AC power supply; a full bridge circuit connected to the first input terminal and the second input terminal, including a pair of high-side elements and a pair of low-side elements, one of the pair of high-side elements and the pair of low-side elements being configured with a bidirectional switch and the other being configured with a rectifier diode; a smoothing capacitor connected to the full bridge circuit; a controller that controls the on / off of the bidirectional switch in accordance with the AC voltage and the voltage across the smoothing capacitor; A rectifier circuit comprising:

2. The rectifier circuit according to claim 1 , wherein the pair of high-side devices are configured as bidirectional switches.

3. The rectifier circuit according to claim 1 , wherein the pair of low-side devices are configured as bidirectional switches.

4. A rectifier circuit according to any one of claims 1 to 3; a DC / DC converter connected to the rectifier circuit; An AC / DC converter comprising:

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