Asymmetric half-bridge AC-DC single-stage converter voltage-doubling and current-doubling rectifying circuit

Abstract

The invention provides a voltage-doubling and current-doubling rectifying circuit of an asymmetric half-bridge AC-DC single-stage converter, relates to an isolation type single-stage PFC technology in the field of power electronics / power conversion, and aims to realize power factor correction and stabilize direct current output. The device comprises a rectifier bridge, an asymmetric half bridge, a transformer, a rectifier circuit, an inductor La and capacitors Cb and Co, wherein the rectifier circuit adopts an innovative voltage-doubling rectifier topology or current-doubling rectifier topology; the voltage source comprises diodes D1 and D2, inductors Lo1 and Lo2 and capacitors C3 and C4, the voltage stresses of the diodes and the inductors are halved and balanced, and the current ripple is small; and the secondary winding comprises diodes D1 and D2 and inductors Lo1 and Lo2, and the current stress of the diodes, the inductors and the secondary winding is halved, so that the loss can be reduced. The converter belongs to double-end conversion and can transmit high power; asymmetric complementary PWM control is adopted, and ZVS soft switching is achieved. The method is simple in topology, easy to control, high in reliability, low in cost and high in efficiency.

Description

Technical Field

[0001] The invention relates to an asymmetric half-bridge AC-DC single-stage converter voltage doubler and current doubler rectifier circuit, which is a switching power supply technology and belongs to the field of new energy power conversion and power electronics technology. Background Art

[0002] At present, the general technical solution for high-power, high-power-factor isolated AC-DC converters is a two-stage circuit topology. The first stage is a high-power-factor AC-DC non-isolated conversion, which generally adopts the Boot conversion topology; the second stage is a DC-DC isolated conversion, which mainly includes a phase-shifted full-bridge topology and an LLC conversion topology.

[0003] The two-stage circuit scheme has inherent disadvantages: (1) The circuit is complex. (2) The overall efficiency is reduced. (3) The reliability is reduced. (4) The cost is high. (5) The volume is large. These are all caused by the two-stage power conversion. In addition, the high power factor AC-DC non-isolated converter of the first stage is not easy to achieve soft switching.

[0004] The so-called "single-stage PFC (Power Factor Correction) converter" is an isolated AC-DC converter that can achieve a high power factor on the AC side and stabilize the DC side output voltage with only one stage of power conversion.

[0005] For isolated single-stage PFC converters, most of them adopt flyback topology. Flyback converter is a single-ended converter, and the power transmitted cannot be too large. It is generally used for low-power conversion. Resonant bridge topology can also be used for isolated single-stage PFC conversion, but it is only suitable for voltage source output and the output voltage adjustment range is narrow, and the reactive current component of the primary side is large. The full-bridge topology with phase shift control can also be used for isolated single-stage PFC conversion, but both the primary and secondary sides require four switch tubes for active control, which requires many devices and is costly. Some so-called combined single-stage converters use a combination of Boot and bridge topologies. The circuit is complex and the superiority is not obvious. There are also single-stage topologies with asymmetric double-ended output, but the voltage and current stress of the rectifier circuit is large, which has many disadvantages in high-power applications, especially in low-voltage and high-current scenarios.

[0006] The above contents are only used to assist in understanding the technical solution of the present invention and do not represent that the above contents are all prior arts. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and propose an asymmetric half-bridge AC-DC single-stage converter voltage doubler and current doubler rectifier circuit. The circuit is an isolated single-stage PFC converter, which designs a streamlined and symmetrical voltage doubler rectifier topology to reduce the voltage stress of power devices and increase the output voltage, and reduce the output current ripple; constructs a symmetrical and streamlined current doubler rectifier topology to reduce the current stress of power devices and increase the output current, which is suitable for low-voltage and high-current scenarios. The AC-DC single-stage converter belongs to double-end conversion and can transmit high power; and the switch tube can realize ZVS soft switching to improve conversion efficiency. The converter adopts asymmetric complementary PWM control to achieve power factor correction and stabilize the DC output.

[0008] The technical solution of the present invention is as follows.

[0009] The asymmetric half-bridge AC-DC single-stage converter voltage and current doubler rectifier circuit is composed of a rectifier bridge, an asymmetric half-bridge, a transformer, a rectifier circuit, an inductor La, and capacitors Cb and Co. The rectifier bridge is a four-terminal network with a positive output terminal, a negative output terminal, and two AC input terminals.

[0010] The asymmetric half bridge includes capacitors C1, C2 and switches Q1, Q2. The first ends of capacitors C1 and C2 are connected as a node Va, the second end of capacitor C2 is connected to the drain of switch Q2 as a node Vd; the source of switch Q2 is connected to the drain of switch Q1 as a node Vb, and the source of switch Q1 is connected to the second end of capacitor C1 as a node GND.

[0011] The transformer includes a primary winding Np and a secondary winding Ns. The primary winding Np has terminals P1 and P2, and the secondary winding Ns has terminals S1 and S2. The terminal S1 and the terminal P1 are the same terminals, and the terminal S2 and the terminal P2 are the same terminals.

[0012] The rectifier circuit adopts a voltage doubler rectifier topology or a current doubler rectifier topology.

[0013] The voltage doubler rectifier topology adopted by the rectifier circuit includes: diodes D1 and D2, inductors Lo1 and Lo2, capacitors C3 and C4. The cathode of diode D1 is connected to the negative electrode of capacitor C4 as node V1, and the anode of diode D2 is connected to the positive electrode of capacitor C3 as node V2. The anode of diode D1 is connected to the negative electrode of capacitor C3 as the DC negative terminal Vo-, the cathode of diode D2 is connected to the positive electrode of capacitor C4 and the first end of inductor Lo1, and the second end of inductor Lo1 is used as the DC positive terminal Vo+; or the cathode of diode D2 is connected to the positive electrode of capacitor C4 as the DC positive terminal Vo+, the anode of diode D1 is connected to the negative electrode of capacitor C3 and the first end of inductor Lo1, and the second end of inductor Lo1 is used as the DC negative terminal Vo-. The two ends of inductor Lo2 are connected to node V1 and node V2 respectively. Inductors Lo1 and Lo2 are coupled or independent, or inductor Lo2 is removed.

[0014] The current doubling rectification topology adopted by the rectification circuit includes: diodes D1 and D2, inductors Lo1 and Lo2. The cathode of diode D1 is connected to the first end of inductor Lo1 as node V1, and the anode of diode D2 is connected to the second end of inductor Lo2 as node V2; the anode of diode D1 is connected to the first end of inductor Lo2 as DC negative terminal Vo-, and the cathode of diode D2 is connected to the second end of inductor Lo1 as DC positive terminal Vo+. Inductors Lo1 and Lo2 are coupled or independent. Alternatively, diode D3 is used to replace inductor Lo1 or replace inductor Lo2; the replacement rule is that the anode and cathode of switch tube D3 correspond to the connection positions of the first end and the second end of inductor Lo1 or Lo2 respectively.

[0015] The connection relationship of the various parts of the asymmetric half-bridge AC-DC single-stage converter voltage doubler and current doubler rectifier circuit is as follows: AC power supply u s The two ends are connected to the two AC input ends of the rectifier bridge, the negative output end of the rectifier bridge is connected to the node GND, the positive output end of the rectifier bridge is connected to the first end of the inductor La, and the second end of the inductor La is connected to the node Va or the node Vb of the asymmetric half bridge. The nodes Va and Vb of the asymmetric half bridge are respectively connected to the terminals P1 and P2 of the primary winding Np of the transformer; the terminal S1 of the secondary winding Ns is connected to the node V1 of the rectifier circuit, and the capacitor Cb is connected in series between the terminal S2 of the secondary winding Ns and the node V2 of the rectifier circuit; or, the terminal S2 of the secondary winding Ns is connected to the node V2 of the rectifier circuit, and the capacitor Cb is connected in series between the terminal S1 of the secondary winding Ns and the node V1 of the rectifier circuit. The positive and negative electrodes of the capacitor Co are respectively connected to the DC positive terminal Vo+ and the DC negative terminal Vo- of the rectifier circuit.

[0016] When the second end of the inductor La is connected to the node Vb of the asymmetric half bridge, the second end of the capacitor C1 is connected to the node GND or is connected to the positive output end of the rectifier bridge instead. The control stability is improved, but the input current ripple increases.

[0017] When the rectifier circuit adopts a voltage doubler rectifier topology, if the second end of the inductor Lo1 is used as the DC positive terminal Vo+, the negative electrode of the capacitor Co is connected to the DC negative terminal Vo- or connected to the node V2 of the rectifier circuit; if the second end of the inductor Lo1 is used as the DC negative terminal Vo-, the positive electrode of the capacitor Co is connected to the DC positive terminal Vo+ or connected to the node V1 of the rectifier circuit.

[0018] When the rectifier circuit adopts the voltage doubler rectifier topology, the capacitor Cb is retained or removed. When the rectifier circuit adopts the voltage doubler rectifier topology and the capacitor Cb is removed, the inductor Lo2 is retained or removed. When the rectifier circuit adopts the voltage doubler rectifier topology and is used as a current source output, the capacitor Co is removed.

[0019] When the AC power supply u sWhen the voltage is low and the asymmetric half-bridge switch tube Q1 has sufficient withstand voltage, the switch tube Q2 and capacitor C2 are removed to simplify the circuit and reduce costs.

[0020] In order to achieve bidirectional energy flow or synchronous rectification, the rectifier bridge uses bidirectional thyristors or switch tubes, and the switch tubes Q3, Q4, Q5 replace the diodes D1, D2, and D3 of the rectifier circuit; the replacement rule is that the drain and source of the switch tube correspond to the connection positions of the cathode and anode of the diode respectively. The so-called bidirectional energy flow refers to the bidirectional flow of electric energy between the AC and DC sides.

[0021] The asymmetric half-bridge AC-DC single-stage converter voltage and current doubler rectifier circuit becomes a DC-DC converter if the rectifier bridge is removed and a DC power supply is connected between the first end of the inductor La and the node GND of the asymmetric half-bridge.

[0022] For the above-mentioned asymmetric half-bridge AC-DC single-stage converter voltage doubler and current doubler rectifier circuit, by applying asymmetric complementary PWM control to the asymmetric half-bridge, single-stage PFC conversion can be completed to achieve high power factor and stable DC output. That is, two asymmetric and complementary PWM pulse signals containing dead time respectively drive the gates of the switching tubes Q1 and Q2 of the conversion bridge to control the switching tubes Q1 and Q2 to perform complementary on-off conversion. The so-called asymmetric and complementary means that the duty cycles of the two PWM pulses are generally not equal, and the sum of the two is equal to 1 when the dead time is ignored.

[0023] Compared with the prior art, the present invention has the following advantages.

[0024] 1) The present invention adopts AC-DC single-stage conversion, which not only realizes power factor correction but also stabilizes DC output.

[0025] 2) The present invention adopts asymmetric half-bridge complementary PWM control, which can achieve zero voltage soft switching (ZVS).

[0026] 3) The topology of the present invention belongs to an isolated double-terminal conversion and can transmit high power.

[0027] 4) The voltage doubler rectifier topology of the present invention reduces the voltage stress of the diode and the inductor by half and makes them balanced, and reduces the current ripple, which is beneficial to high voltage output applications.

[0028] 5) The current-doubling rectification topology of the present invention reduces the current stress of the diode, inductor and secondary winding by half, thereby reducing losses and facilitating high current output applications.

[0029] 6) The present invention has simple topology, easy control, high reliability, low cost and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1Schematic diagram of a first embodiment of an asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit.

[0031] Figure 2 Schematic diagram of a second embodiment of an asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit.

[0032] Figure 3 Schematic diagram of a third embodiment of an asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit.

[0033] Figure 4 A schematic diagram of a fourth embodiment of an asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit.

[0034] Figure 5 A fifth embodiment of the principle diagram of an asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit.

[0035] Figure 6 Schematic diagram of a sixth embodiment of an asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit.

[0036] Figure 7 Schematic diagram of Example 1 of an asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit.

[0037] Figure 8 Schematic diagram of Example 2 of an asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit.

[0038] Fig. 9 Schematic diagram of Example 3 of the current doubler rectifier circuit of an asymmetric half-bridge AC-DC single-stage converter.

[0039] Fig.10 Schematic diagram of Example 4 of an asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit.

[0040] Fig.11 Schematic diagram of Example 5 of an asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit.

[0041] Fig.12 Schematic diagram of Example 6 of an asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit.

[0042] In the figure, 1 is the rectifier bridge, 2 is the asymmetric half bridge, 3 is the transformer, 4 is the rectifier circuit; La is the inductor, Cb and Co are the capacitors; Q1, Q2, Q3 and Q4 are the switches, D1, D2 and D3 are the diodes, C1, C2, C3 and C4 are the capacitors, Lo1 and Lo2 are the inductors; Np is the primary winding, and Ns is the secondary winding. s —AC power supply.

[0043] In the figure, P1, P2 are terminal symbols of the primary winding, S1, S2 are terminal symbols of the secondary winding; V1, V2, Va, Vb, Vd, GND are node symbols; Vo+ is the DC positive terminal, Vo- is the DC negative terminal. DETAILED DESCRIPTION

[0044] The present invention will be described and analyzed in detail below with reference to the accompanying drawings and preferred embodiments. The described embodiments are only a part of the embodiments of the present invention and not all of them.

[0045] One more point to be made is that the serial numbers for devices or methods in this patent application, such as "first", "second", etc., are only used to distinguish the objects described, and do not have order or technical meanings, and cannot be understood as indicating their relative importance or implicitly indicating the number of technical features. The "connection" mentioned in this patent application, unless otherwise specified, includes direct and indirect connections.

[0046] 1. Preferred embodiments of the present invention

[0047] like Figures 1 to 12 As shown, the asymmetric half-bridge AC-DC single-stage converter voltage doubler and current doubler rectifier circuit is composed of a rectifier bridge (1), an asymmetric half-bridge (2), a transformer (3), a rectifier circuit (4), an inductor La and capacitors Cb and Co.

[0048] Figure 1 The figure shows a first embodiment of an asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit, which is composed of a rectifier bridge (1), an asymmetric half-bridge (2), a transformer (3), a rectifier circuit (4), an inductor La, and capacitors Cb and Co.

[0049] The rectifier circuit (4) adopts a voltage doubling rectifier topology, including diodes D1 and D2, inductors Lo1 and Lo2, and capacitors C3 and C4. The cathode of the diode D1 is connected to the negative electrode of the capacitor C4, serving as the node V1, and the anode of the diode D2 is connected to the positive electrode of the capacitor C3, serving as the node V2. The anode of the diode D1 is connected to the negative electrode of the capacitor C3, serving as the DC negative terminal Vo-, the cathode of the diode D2 is connected to the positive electrode of the capacitor C4 and the first terminal of the inductor Lo1, and the second terminal of the inductor Lo1 serves as the DC positive terminal Vo+. The two ends of the inductor Lo2 are connected to the node V1 and the node V2, respectively. The inductors Lo1 and Lo2 are coupled or independent.

[0050] The transformer (3) comprises a primary winding Np and a secondary winding Ns. The primary winding Np has terminals P1 and P2, and the secondary winding Ns has terminals S1 and S2. The terminal S1 and the terminal P1 are the same terminals, and the terminal S2 and the terminal P2 are the same terminals.

[0051] The asymmetric half bridge (2) comprises capacitors C1, C2 and switch tubes Q1, Q2. The switch tubes are MOSFET or IGBT, but not limited to them. The first ends of the capacitors C1 and C2 are connected to form a node Va, the second end of the capacitor C2 is connected to the drain of the switch tube Q2, and the node Vd; the source of the switch tube Q2 is connected to the drain of the switch tube Q1, and the node Vb; the source of the switch tube Q1 is connected to the second end of the capacitor C1, and the node GND.

[0052] The rectifier bridge (1) adopts but is not limited to a diode or a thyristor or a switch tube, which is a four-terminal network having a positive output terminal, a negative output terminal and two AC input terminals.

[0053] The connection relationship of the various parts is: AC power supply u s The two ends are connected to the two AC input ends of the rectifier bridge (1), the negative output end of the rectifier bridge (1) is connected to the node GND, the positive output end of the rectifier bridge (1) is connected to the first end of the inductor La, and the second end of the inductor La is connected to the node Vb of the asymmetric half bridge (2). The nodes Va and Vb of the asymmetric half bridge (2) are respectively connected to the terminals P1 and P2 of the primary winding Np of the transformer (3); the terminal S1 of the secondary winding Ns of the transformer (3) is connected to the node V1 of the rectifier circuit (4), the terminal S2 of the secondary winding Ns is connected to one end of the capacitor Cb, and the other end of the capacitor Cb is connected to the node V2 of the rectifier circuit (4). The positive electrode and the negative electrode of the capacitor Co are respectively connected to the DC positive terminal Vo+ and the DC negative terminal Vo- of the rectifier circuit (4).

[0054] In the first embodiment, there are two points that need to be explained: First, the second end of the inductor La is connected to the node Vb of the asymmetric half bridge (2). At this time, the function of the inductor La is to store energy, and its inductance is relatively large. Second, the function of the capacitor Cb is to isolate the DC current, and the average voltage on the capacitor Cb is zero in the steady state. With these two points as necessary conditions, the transformer (3) has no bias magnetism, that is, the positive and negative amplitudes of the excitation current are equal in each working cycle. The average currents of the inductors Lo1 and Lo2 are equal.

[0055] Figure 2 FIG. 2 is a second embodiment of an asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit. Figure 1 Compared with the first embodiment shown in the figure, the difference is that the second end of the inductor La is connected to the node Va of the asymmetric half bridge (2), and the capacitor Cb is removed. The transformer (3) has a bias magnet, and the average current values ​​of the inductors Lo1 and Lo2 are not necessarily equal, but vary with the relative changes of the inductors Lo1, Lo2 and the inductance of the transformer (3). When the second end of the inductor La is connected to the node Va, its function is filtering, and the inductance is relatively small (about 1 / 10 of that in the first embodiment).

[0056] Figure 3The third embodiment of the asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit is shown in FIG. Figure 2 On the basis of the second embodiment shown, the rectifier bridge (1) adopts a switch tube, and the diodes D1 and D2 of the rectifier circuit (4) are replaced with switch tubes Q3 and Q4. The drain and source of the switch tube are respectively connected to the cathode and anode positions of the original diode. The converter circuit of the third embodiment can achieve AC-DC bidirectional energy flow. The transformer (3) has a bias magnet.

[0057] Figure 4 The fourth embodiment of the asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit is shown in FIG. Figure 2 On the basis of the second embodiment shown, the inductor Lo2 is further removed. The secondary winding Ns also serves as the original inductor Lo2, the DC component of its current will increase, and the bias magnetization of the transformer (3) will increase. The advantages of this embodiment are that the circuit is further simplified and the cost is lower.

[0058] Figure 5 The fifth embodiment of the asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit is shown in FIG. Figure 4 On the basis of the fourth embodiment shown, the switch tube Q2 and the capacitor C2 in the asymmetric half bridge (2) are further removed, and the negative electrode of the capacitor Co is connected to the node V2. The efficiency is improved, but the output ripple current increases. When the switch tube Q1 is turned off, its voltage spike is very high, and the leakage inductance of the transformer (3) needs to be reduced as much as possible.

[0059] Figure 6 FIG. 6 is a sixth embodiment of an asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit. Figure 5 Compared with the fifth embodiment shown, the difference is that the second end of the inductor La is connected to the node Vb of the asymmetric half bridge (2). The bias of the transformer (3) will be reduced, but the function of the inductor La becomes energy storage, and the required inductance is larger.

[0060] The fifth and sixth embodiments of the asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit are suitable for AC power supply u s When the voltage is low and the voltage resistance of the switch tube Q1 is high, the circuit can be simplified and the cost can be reduced.

[0061] Figure 7 As shown, Example 1 of an asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit is composed of a rectifier bridge (1), an asymmetric half-bridge (2), a transformer (3), a rectifier circuit (4), an inductor La, and capacitors Cb and Co.

[0062] The rectifier circuit (4) adopts a current doubling rectifier topology, including diodes D1 and D2, and inductors Lo1 and Lo2. Diodes D1 and D2, inductors Lo1 and Lo2. The cathode of diode D1 is connected to the first end of inductor Lo1 as node V1, and the anode of diode D2 is connected to the second end of inductor Lo2 as node V2; the anode of diode D1 is connected to the first end of inductor Lo2 as DC negative terminal Vo-, and the cathode of diode D2 is connected to the second end of inductor Lo1 as DC positive terminal Vo+. Inductors Lo1 and Lo2 are coupled or independent.

[0063] Embodiment 1 of this current doubler rectifier circuit and Figure 1 Compared with the first embodiment of the voltage doubler rectifier circuit shown in the figure, the difference is that the rectifier circuit (4) adopts the current doubler rectifier topology. The topology and connection relationship of other parts are the same, and the transformer (3) has no bias magnetism. The function of the inductor La is to store energy, and the required inductance is relatively large. The function of the capacitor Cb is to isolate DC and store energy. In steady state, the average voltages on the capacitors Cb and Co are equal, so the capacitor Cb is necessary.

[0064] Figure 8 The figure shows an embodiment 2 of an asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit. Figure 7 Compared with the embodiment 1 shown, the difference is that the second end of the inductor La is connected to the node Va of the asymmetric half bridge (2), and its function is filtering, and the inductance is small (about 1 / 10 of that in embodiment 1). The transformer (3) has a bias magnet. The capacitor Cb is necessary.

[0065] Fig. 9 The figure shows the embodiment 3 of the asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit. Figure 8 On the basis of the embodiment 2 shown, the rectifier bridge (1) uses a switch tube, and the diodes D1 and D2 of the rectifier circuit (4) are replaced with switch tubes Q3 and Q4. The drain and source of the switch tube are respectively connected to the cathode and anode positions of the original diode. The converter circuit of embodiment 3 is capable of AC-DC bidirectional energy flow. The transformer (3) has a bias magnet.

[0066] Fig.10 The figure shows an embodiment 4 of the asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit. This embodiment 4 is Figure 8 On the basis of the embodiment 2 shown, the switch tube Q2 and the capacitor C2 in the asymmetric half bridge (2) are removed. When the switch tube Q1 is turned off, its voltage spike is very high, and the leakage inductance of the transformer (3) needs to be reduced as much as possible.

[0067] Fig.11 The figure shows an embodiment 5 of the asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit. This embodiment 5 is Figure 8On the basis of the embodiment 2 shown, the inductor Lo2 is replaced by a diode D3, and the anode and cathode of the diode D3 are connected to the anodes of the diodes D1 and D2 respectively. The inductor Lo2 with a relatively large volume is omitted, but the circuit is no longer symmetrical.

[0068] Fig.12 The figure shows an embodiment 6 of the asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit. This embodiment 6 is Figure 8 On the basis of the embodiment 2 shown, the inductor Lo1 is replaced by a diode D3, and the switch tube Q2 and the capacitor C2 in the asymmetric half bridge (2) are removed.

[0069] Embodiments 4 and 6 of the asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit are suitable for AC power supply u s When the voltage is low and the voltage resistance of the switch tube Q1 is high, the circuit can be simplified to reduce costs.

[0070] All embodiments of the asymmetric half-bridge AC-DC single-stage converter voltage-doubler and current-doubler rectifier circuit are formed by removing the rectifier bridge (1), and connecting the first end of the inductor La and the node GND of the asymmetric half-bridge (2) to the positive and negative electrodes of the DC power supply respectively, thereby forming a DC-DC converter.

[0071] 2. Working Principle of the Invention

[0072] For the above-mentioned asymmetric half-bridge AC-DC single-stage converter voltage-doubler and current-doubler rectifier circuit, by applying asymmetric complementary PWM control to the asymmetric half-bridge (2), single-stage AC-DC conversion can be completed to achieve high power factor and stable DC output. That is, two asymmetric and complementary PWM pulse signals containing dead time respectively drive the gates of the switching tubes Q1 and Q2 of the conversion bridge to control the switching tubes Q1 and Q2 to perform complementary on-off conversion. The so-called asymmetric and complementary means that the duty cycles of the two PWM pulses are generally not equal, and the sum of the two is equal to 1 when the dead time is ignored.

[0073] The working principle of the voltage-doubler and current-doubler rectifier circuits of the asymmetric half-bridge AC-DC single-stage converter can be analyzed in detail according to the specific topology adopted by the rectifier circuit (4).

[0074] 2.1 Asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit

[0075] Sinusoidal AC power supply u s After passing through the rectifier bridge (1), it is rectified into a sinusoidal half-wave pulsating DC voltage u a , applied to the first end of the inductor La. Voltage u a The expression is:

[0076]

[0077] Where U s For AC power u s The effective value of ω is u s angular frequency.

[0078] Set the voltage of capacitor C1 to V a , the voltage of capacitor C2 is V c , the voltage between the node Vd and GND of the asymmetric half bridge (2) is V d , then:

[0079] V a =u a , V d =V a +V c (E-2)

[0080] like Figure 2 As shown, if the second end of the inductor La is connected to the node Va, the voltage u a After being filtered by inductor La, it is added to capacitor C1, V a =u a .like Figure 1 As shown, if the second end of the inductor La is connected to the node Vb, the voltage u a After being added to capacitor C1 through inductor La and primary winding Np, during the transformation of switch tubes Q1 and Q2, the volt-second balance relationship satisfied by inductor La and primary winding Np is the same (see equation (E-5) below), and V is still obtained. a =u a .

[0081] Assume the voltage of capacitor Cb is V e , the voltage of capacitor Co (i.e. DC output voltage) is V o , the voltage of capacitor C3 is V3, and the voltage of capacitor C4 is V4. Note: The set voltage refers to the average voltage excluding high-frequency ripple.

[0082] Set the voltage of the secondary winding Ns to V s , and the direction from S1 to S2 is positive; the voltage of the primary winding Np is V p , and the direction from P1 to P2 is positive. Assuming the transformation ratio of transformer (3) is n, ignoring the leakage inductance of transformer (3), we have:

[0083] V s =n·V p (E-3)

[0084] In order to simplify the analysis, the on-resistance and on-off switching dead time of the switch tubes Q1 and Q2 are ignored, and the on-voltage drop and on-off switching time of the diodes D1 and D2 are ignored.

[0085] When the switch Q2 is turned off and Q1 is turned on, the terminal P2 of the primary winding Np of the transformer (3) is connected to the node GND, and the voltage u of the capacitor C1 a Added to the primary winding Np, then V p =u a ; The voltage induced to the secondary winding Ns is V s =n·u a At this time, the diodes D1 and D2 of the rectifier circuit (4) are cut off; the secondary winding Ns is connected in series with the capacitor Cb to apply a voltage to the inductor Lo2, and the secondary winding Ns is connected in series with the capacitors Cb, C3, C4 and Co to apply a voltage to the inductor Lo1, and the inductors Lo1 and Lo2 store energy; at the same time, the secondary winding Ns is connected in series with the capacitors Cb, C3, C4 to transmit current to the capacitor Co (i.e., the DC output end), and the capacitors C3 and C4 discharge.

[0086] When the switch Q1 is turned off and Q2 is turned on, the terminal P2 of the primary winding Np of the transformer (3) is connected to the node Vd, and the voltage V c Added to the primary winding Np, then V p =-V c ; The voltage induced to the secondary winding Ns is V s =-n·V c At this time, the diodes D1 and D2 of the rectifier circuit (4) are turned on; the secondary winding Ns is freewheeling through the diodes D1, D2 and the capacitors C3, C4, and the inductors Lo2 and Lo1 are freewheeling through the diodes D1, D2 to the capacitor Co (i.e., the DC output end), and the inductors Lo1 and Lo2 release energy. The sum of the currents of the secondary winding Ns and the inductor Lo2 exceeds the current of the inductor Lo1, and charges the capacitors C3 and C4.

[0087] When the diodes D1 and D2 of the rectifier circuit (4) are turned on, the voltages of the capacitors C3 and C4 satisfy the following relationship:

[0088] V3=V4=n·V c +V e (E-4)

[0089] If the on-duty ratio of the switch tube Q1 is set to D, the on-duty ratio of the switch tube Q2 is (1-D). According to the volt-second balance principle of the switch conversion, the voltage relationship of the primary winding Np is:

[0090] u a D = V c (1-D)(E-5)

[0091] The voltages applied to the inductors Lo2 and Lo1 of the rectifier circuit (4) satisfy the following relationships:

[0092] (n·ua -V e )·D=V3·(1-D) (E-6)

[0093] (n·u a -V e +2V3-V o )·D=(V o -V3)·(1-D) (E-7)

[0094] The combined equations (E-7) to (E-4) lead to the following:

[0095]

[0096] From formula (E-8), we can see that the DC output voltage V o It can be adjusted and stabilized by adjusting the duty cycle D; that is, the average value of the duty cycle D adjusts the average value of the output voltage, and the instantaneous change of D realizes power factor correction. The "2 times" relationship in the formula just shows that it is "voltage doubling rectification". The average voltage of capacitor Cb is zero, so it can be removed.

[0097] Assume the current of inductor Lo1 is I o (that is, the output current), the current of inductor Lo2 is I o2 , the forward current of the secondary winding Ns of transformer (3) is I s+ , negative current is I s- (Outflow from terminal S1 is positive, inflow is negative); the discharge current of capacitor C3 is I 3+ , the charging current is I 3- , the discharge current of capacitor C4 is I 4+ , the charging current is I 4- The charge / discharge current of capacitor Cb is equal to the forward / reverse current of secondary winding Ns respectively.

[0098] When the switch tube Q2 is turned off and Q1 is turned on, the diodes D1 and D2 are cut off, and the current relationship is:

[0099]

[0100] When the switch tube Q1 is turned off and Q2 is turned on, the diodes D1 and D2 are turned on, and the current relationship is:

[0101] (I s- +I o2 -I 3- -I 4- )·(1-D)=I o (1-D)(E-10)

[0102] In order to maintain the charge and discharge balance of capacitors C3, C4 and Cb, the following relationship must be satisfied:

[0103]

[0104] Combining equations (E-9), (E-10) and (E-11) we can deduce:

[0105]

[0106] It can be seen from formula (E-12) that if the capacitor Cb is retained, the average currents of the inductors Lo1 and Lo2 are equal. When the second end of the inductor La is connected to the node Va, the transformer (3) has a bias and is relatively constant, and the instantaneous average value of its bias current (excluding high-frequency ripple) is basically consistent with the current of the inductor La. When the second end of the inductor La is connected to the node Vb, the transformer (3) has no bias (if the capacitor Cb is removed), and the transformer (3) can be smaller; but at this time, the role of the inductor La is to store energy, and the inductance is larger, about 10 times that when it is connected to the node Va.

[0107] If the capacitor Cb is removed, the average currents of the inductors Lo1 and Lo2 may not be equal, and the bias magnetism of the transformer (3) may also change. These changes vary with the relative changes of the inductors Lo1, Lo2 and the inductance of the transformer (3).

[0108] like Figure 4 As shown, the capacitor Cb and the inductor Lo2 are removed at the same time, and the secondary winding Ns also plays the role of the inductor Lo2, the DC component of its current will increase, and the bias magnetization of the transformer (3) will increase. The advantages are: the circuit is simplified and the cost is lower. The current state of the secondary winding Ns is analyzed in detail below.

[0109] I in formula (E-9) and formula (E-10) o2 =0, it can be deduced that:

[0110]

[0111] Average value of DC component of secondary winding Ns Equal to the average current of inductor Lo1:

[0112]

[0113] Next, the maximum operating voltage of the switch tubes Q1, Q2 and the diodes D1, D2 is analyzed.

[0114] The maximum operating voltage of the switch tubes Q1 and Q2 is the maximum value V between the node Vd of the asymmetric half bridge (2) and GND. dM , combining equation (E-2) and equation (E-8) yields:

[0115]

[0116] The reverse voltage of diodes D1 and D2 is denoted as V R , V R =V3+n·u a , its maximum value V RM for:

[0117]

[0118] According to equations (E-15) and (E-16), by adjusting the transformation ratio n of the transformer (3), the maximum operating voltages of the switch tubes Q1, Q2 and the diodes D1, D2 in the voltage doubler rectifier circuit can be balanced.

[0119] 2.2 Asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit

[0120] like Figure 8 and Fig. 9 As shown, the asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit is different from the voltage doubler rectifier circuit in that the rectifier circuit (4) adopts the current doubler rectifier topology, while the circuit topology, connection method and electrical relationship of other parts are the same. Therefore, the power relationship of the current doubler rectifier topology is analyzed here based on some formulas in the previous section.

[0121] When the switch tube Q2 is turned off and Q1 is turned on, the diodes D1 and D2 of the rectifier circuit (4) are turned off. The secondary winding Ns is connected in series with the capacitors Cb and Co to apply voltage to the inductors Lo1 and Lo2 in series, and the inductors Lo1 and Lo2 store energy; at the same time, the capacitor secondary winding Ns is connected in series with the capacitor Cb to transmit current to the capacitor Co (i.e., the DC output end), and the capacitor Cb discharges.

[0122] When the switch tube Q1 is turned off and Q2 is turned on, the diodes D1 and D2 of the rectifier circuit (4) are turned on. The inductors Lo1 and Lo2 respectively provide freewheeling current to the capacitor Co (i.e., the DC output end) through the diodes D1 and D2, and the inductors Lo1 and Lo2 release energy; at the same time, the secondary winding Ns charges the capacitors Cb and Co in series through the diodes D1 and D2.

[0123] When the diodes D1 and D2 of the rectifier circuit (4) are turned on, the voltages of the capacitors Cb and Co satisfy the following relationship:

[0124] V o +V e =n·V c (E-17)

[0125] The inductance of inductors Lo1 and Lo2 should be equal and can be coupled or independent. Set the on-duty ratios of switches Q1 and Q2 to D and (1-D) respectively. According to the volt-second balance principle of switch conversion, the voltages applied to inductors Lo1 and Lo2 are the same and satisfy the following relationship:

[0126]

[0127] Combining equations (E-18), (E-17) and (E-5) we can deduce:

[0128]

[0129] From formula (E-19), we can see that the DC output voltage V o It can be adjusted and stabilized by adjusting the duty cycle D; that is, the average value of the duty cycle D adjusts the average value of the output voltage, and the instantaneous change of D realizes power factor correction. The average voltage of capacitors Cb and Co is equal, so Cb is necessary.

[0130] The currents of inductors Lo1 and Lo2 are equal, denoted as I L When the switch tube Q2 is turned off and Q1 is turned on:

[0131] I s+ ·D=I L ·D(E-20)

[0132] In order to maintain the charge and discharge balance of capacitor Cb, the following relationship must be satisfied:

[0133] I s+ ·D=I s- (1-D)(E-21)

[0134] Combining equations (E-20) and (E-21), the total current I flowing to capacitor Co (i.e., DC output end) is oΣ for:

[0135]

[0136] The total DC output current I oΣ The average for:

[0137]

[0138] It can be seen from formula (E-23) that the output current is twice the inductor current, which corresponds to the topology name of "voltage doubler rectification".

[0139] In the asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit, the maximum operating voltage of the switch tubes Q1 and Q2 can be obtained from equations (E-2) and (E-19):

[0140]

[0141] The reverse voltage of diodes D1 and D2 is V R =(V o+V e +n·u a ) / 2, its maximum value V RM for:

[0142]

[0143] According to equations (E-24) and (E-25), by adjusting the transformation ratio n of the transformer (3), the maximum operating voltages of the switches Q1, Q2 and the diodes D1, D2 in the current doubler rectifier circuit can be balanced. When the inductors Lo1 and Lo2 are coupled, it is more conducive to the dynamic balance of the reverse voltages of the diodes D1, D2.

[0144] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent topological transformations made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit, comprising a rectifier bridge (1), an asymmetric half-bridge (2), a transformer (3), a rectifier circuit (4), an inductor La and capacitors Cb and Co; the rectifier bridge (1) is a four-terminal network having a positive output terminal, a negative output terminal and two AC input terminals; The asymmetric half bridge (2) comprises capacitors C1, C2 and switch tubes Q1, Q2; the first ends of the capacitors C1 and C2 are connected to form a node Va, the second end of the capacitor C2 is connected to the drain of the switch tube Q2 to form a node Vd, the source of the switch tube Q2 is connected to the drain of the switch tube Q1 to form a node Vb, and the source of the switch tube Q1 is connected to the second end of the capacitor C1 to form a node GND; or the switch tube Q2 and the capacitor C2 are removed; The transformer (3) comprises a primary winding Np and a secondary winding Ns, the primary winding Np has terminals P1 and P2, the secondary winding Ns has terminals S1 and S2, the terminal S1 and the terminal P1 are the same terminals, and the terminal S2 and the terminal P2 are the same terminals; Features: The rectifier circuit (4) adopts a voltage doubling rectifier topology, which includes: diodes D1 and D2, inductors Lo1 and Lo2, capacitors C3 and C4; the cathode of the diode D1 is connected to the negative electrode of the capacitor C4, serving as a node V1, the anode of the diode D2 is connected to the positive electrode of the capacitor C3, serving as a node V2; the anode of the diode D1 is connected to the negative electrode of the capacitor C3, serving as a DC negative terminal Vo. - , the cathode of diode D2 is connected to the positive electrode of capacitor C4 and the first end of inductor Lo1, and the second end of inductor Lo1 is used as the DC positive end Vo + ; or the cathode of diode D2 is connected to the positive electrode of capacitor C4, serving as the DC positive terminal Vo + The anode of diode D1 is connected to the cathode of capacitor C3 and the first end of inductor Lo1, and the second end of inductor Lo1 is used as the negative DC terminal Vo. - ; The two ends of the inductor Lo2 are connected to the node V1 and the node V2 respectively, and the inductor Lo2 and Lo1 are coupled or independent; The connection relationship of the various parts of the asymmetric half-bridge AC-DC single-stage converter doubler rectifier circuit is as follows: AC power supply u s The two ends are connected to two AC input ends of a rectifier bridge (1), the negative output end of the rectifier bridge (1) is connected to a node GND, the positive output end of the rectifier bridge (1) is connected to a first end of an inductor La, and the second end of the inductor La is connected to a node Va or a node Vb of an asymmetric half bridge (2); the nodes Va and Vb of the asymmetric half bridge (2) are respectively connected to terminals P1 and P2 of a primary winding Np of a transformer (3); the terminal S1 of a secondary winding Ns is connected to a node V1 of a rectifier circuit (4), and a capacitor Cb is connected in series between a terminal S2 of a secondary winding Ns and a node V2 of a rectifier circuit (4); or the terminal S2 of a secondary winding Ns is connected to a node V2 of a rectifier circuit (4), and a capacitor Cb is connected in series between a terminal S1 of a secondary winding Ns and a node V1 of a rectifier circuit (4); the positive and negative electrodes of the capacitor Co are respectively connected to a DC positive terminal Vo of the rectifier circuit (4). + and DC negative terminal Vo - ; When the second end of the inductor La is connected to the node Vb of the asymmetric half bridge (2), the second end of the capacitor C1 is connected to the node GND or is connected to the positive output end of the rectifier bridge (1).

2. The asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit according to claim 1, characterized in that: If the second end of the inductor Lo1 is used as the DC positive terminal Vo + , then the negative electrode of capacitor Co is connected to the negative DC terminal Vo - Or connected to the node V2 of the rectifier circuit (4); if the second end of the inductor Lo1 is used as the DC negative terminal Vo - , then the positive electrode of capacitor Co is connected to the DC positive terminal Vo + Or it is connected to the node V1 of the rectifier circuit (4); when the rectifier circuit (4) outputs as a current source, the capacitor Co is removed.

3. The asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit according to any one of claims 1 and 2, characterized in that: If the capacitor Cb is removed, the terminal S1 and the terminal S2 of the secondary winding Ns are respectively connected to the node V1 and the node V2 of the rectifier circuit (4); when the capacitor Cb is removed, the two ends of the inductor Lo2 are respectively connected to the node V1 and the node V2 of the rectifier circuit (4), or the inductor Lo2 is removed.

4. The asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit according to any one of claims 1 to 3, characterized in that: The diodes D1 and D2 of the rectifier circuit (4) are replaced by switch tubes Q3 and Q4, and the replacement rule is that the drain and source of the switch tube correspond to the connection positions of the cathode and anode of the diode respectively; the rectifier bridge (1) uses a diode or a thyristor or a switch tube, and the switch tube uses but is not limited to MOSFET or IGBT.

5. The asymmetric half-bridge AC-DC single-stage converter voltage doubler rectifier circuit according to any one of claims 1 to 4, characterized in that: The rectifier bridge (1) is removed, and a DC power source is connected between the first end of the inductor La and the node GND of the asymmetric half bridge (2), thereby forming a DC-DC converter.

6. An asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit, comprising a rectifier bridge (1), an asymmetric half-bridge (2), a transformer (3), a rectifier circuit (4), an inductor La and capacitors Cb and Co; the rectifier bridge (1) is a four-terminal network having a positive output terminal, a negative output terminal and two AC input terminals; The asymmetric half bridge (2) comprises capacitors C1, C2 and switch tubes Q1, Q2; the first ends of the capacitors C1 and C2 are connected to form a node Va, the second end of the capacitor C2 is connected to the drain of the switch tube Q2 to form a node Vd, the source of the switch tube Q2 is connected to the drain of the switch tube Q1 to form a node Vb, and the source of the switch tube Q1 is connected to the second end of the capacitor C1 to form a node GND; or the switch tube Q2 and the capacitor C2 are removed; The transformer (3) comprises a primary winding Np and a secondary winding Ns, the primary winding Np has terminals P1 and P2, the secondary winding Ns has terminals S1 and S2, the terminal S1 and the terminal P1 are the same terminals, and the terminal S2 and the terminal P2 are the same terminals; Features: The rectifier circuit (4) adopts a current doubling rectifier topology, which includes: diodes D1 and D2, inductors Lo1 and Lo2; the cathode of the diode D1 is connected to the first end of the inductor Lo1, serving as a node V1, and the anode of the diode D2 is connected to the second end of the inductor Lo2, serving as a node V2; the anode of the diode D1 is connected to the first end of the inductor Lo2, serving as a DC negative terminal Vo-, and the cathode of the diode D2 is connected to the second end of the inductor Lo1, serving as a DC positive terminal Vo+; the inductors Lo1 and Lo2 are coupled or independent; The connection relationship of the various parts of the asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit is as follows: AC power supply u s The two ends are connected to two AC input ends of a rectifier bridge (1), the negative output end of the rectifier bridge (1) is connected to a node GND, the positive output end of the rectifier bridge (1) is connected to a first end of an inductor La, and the second end of the inductor La is connected to a node Va or a node Vb of an asymmetric half bridge (2); the nodes Va and Vb of the asymmetric half bridge (2) are respectively connected to terminals P1 and P2 of a primary winding Np of a transformer (3); the terminal S1 of a secondary winding Ns is connected to a node V1 of a rectifier circuit (4), and a capacitor Cb is connected in series between a terminal S2 of a secondary winding Ns and a node V2 of a rectifier circuit (4); or the terminal S2 of a secondary winding Ns is connected to a node V2 of a rectifier circuit (4), and a capacitor Cb is connected in series between a terminal S1 of a secondary winding Ns and a node V1 of a rectifier circuit (4); the positive and negative electrodes of the capacitor Co are respectively connected to a DC positive terminal Vo of the rectifier circuit (4). + and DC negative terminal Vo - ; When the second end of the inductor La is connected to the node Vb of the asymmetric half bridge (2), the second end of the capacitor C1 is connected to the node GND or is connected to the positive output end of the rectifier bridge (1).

7. The asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit according to claim 6, characterized in that: The diode D3 is used to replace the inductor Lo1 or the inductor Lo2; the replacement rule is that the connection positions of the anode and cathode of the switch tube D3 correspond to the connection positions of the first end and the second end of the inductor Lo1 or Lo2 respectively.

8. The asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit according to any one of claims 6 and 7, characterized in that: The diodes D1, D2, and D3 of the rectifier circuit (4) are replaced by switch tubes Q3, Q4, and Q5, and the replacement rule is that the drain and source of the switch tube correspond to the connection positions of the cathode and anode of the diode respectively; the rectifier bridge (1) uses a diode or a thyristor or a switch tube, and the switch tube uses but is not limited to MOSFET or IGBT.

9. The asymmetric half-bridge AC-DC single-stage converter current doubler rectifier circuit according to any one of claims 6 to 8, characterized in that: The rectifier bridge (1) is removed, and a DC power source is connected between the first end of the inductor La and the node GND of the asymmetric half bridge (2), thereby forming a DC-DC converter.

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