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

Abstract

The utility model 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 system is simple in topology, easy to control, low in cost and high in efficiency.

Description

Technical Field

[0001] This utility model relates to a voltage multiplier and current multiplier rectifier circuit for an asymmetric half-bridge AC-DC single-stage converter, which is a switching power supply technology and belongs to the field of new energy power conversion and power electronics technology. Background Technology

[0002] Currently, the common 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 converter, generally using a boot converter topology; the second stage is a DC-DC isolated converter, mainly using phase-shifted full-bridge topology and LLC converter topology.

[0003] This two-stage circuit scheme has inherent shortcomings: (1) complex circuitry. (2) reduced overall efficiency. (3) reduced reliability. (4) higher cost. (5) larger size. These are all due to the two-stage power conversion. In addition, the high power factor AC-DC non-isolated converter in the first stage is not easy to implement 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 a stable DC output voltage with only one stage of power conversion.

[0005] For isolated single-stage PFC converters, flyback topologies are mostly used. Flyback converters are single-ended converters, and the power they can transmit cannot be too large, generally used for low-power conversion. Resonant bridge topologies can also be used for isolated single-stage PFC conversion, but they are only suitable for voltage source outputs with a narrow output voltage regulation range and a large reactive current component on the primary side. Phase-shift controlled full-bridge topologies can also be used for isolated single-stage PFC conversion, but they require four switches for active control on both the primary and secondary sides, resulting in more components and higher costs. Some so-called combined single-stage converters use a combination of boot-type and bridge topologies, resulting in complex circuitry and no significant advantages. There are also asymmetrical double-ended output single-stage topologies, but these place high voltage and current stress on the rectifier circuit, which is disadvantageous in high-power applications, especially in low-voltage, high-current scenarios.

[0006] The above content is only used to help understand the technical solution of this utility model and does not mean that all of the above are prior art. Utility Model Content

[0007] The purpose of this invention is to overcome the shortcomings of the prior art by proposing an asymmetric half-bridge AC-DC single-stage converter voltage doubler and current doubler rectifier circuit. This circuit is an isolated single-stage PFC converter with a simplified symmetrical voltage doubler rectifier topology designed to reduce voltage stress on power devices and increase output voltage, while also reducing output current ripple. A symmetrical and simplified current doubler rectifier topology is constructed to reduce current stress on power devices and increase output current, making it suitable for low-voltage, high-current scenarios. This AC-DC single-stage converter is a two-terminal converter capable of transmitting high power; and the switching transistors can achieve ZVS soft switching, improving conversion efficiency. The converter employs asymmetric complementary PWM control to achieve power factor correction and stable DC output.

[0008] The technical solution of this utility model is as follows.

[0009] The asymmetric half-bridge AC-DC single-stage converter voltage multiplier and current multiplier rectifier circuit consists 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 and C2 and switching transistors Q1 and Q2. The first terminals of capacitors C1 and C2 are connected together as node Va, and the second terminal of capacitor C2 is connected to the drain of switching transistor Q2 as node Vd. The source of switching transistor Q2 is connected to the drain of switching transistor Q1 as node Vb, and the source of switching transistor Q1 is connected to the second terminal of capacitor C1 as 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. Terminal S1 and terminal P1 are the same type of terminal, and terminal S2 and terminal P2 are the same type of terminal.

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

[0013] The rectifier circuit uses a voltage doubler rectifier topology including: diodes D1 and D2, inductors Lo1 and Lo2, and capacitors C3 and C4. The cathode of diode D1 is connected to the negative terminal of capacitor C4, forming node V1. The anode of diode D2 is connected to the positive terminal of capacitor C3, forming node V2. The anode of diode D1 is connected to the negative terminal of capacitor C3, forming the DC negative terminal Vo-. The cathode of diode D2 is connected to the positive terminal of capacitor C4 and the first terminal of inductor Lo1, with the second terminal of inductor Lo1 serving as the DC positive terminal Vo+. Alternatively, the cathode of diode D2 is connected to the positive terminal of capacitor C4, forming the DC positive terminal Vo+, and the anode of diode D1 is connected to the negative terminal of capacitor C3 and the first terminal of inductor Lo1, with the second terminal of inductor Lo1 serving as the DC negative terminal Vo-. The two ends of inductor Lo2 are connected to nodes V1 and V2 respectively. Inductors Lo1 and Lo2 can be coupled or independent, or inductor Lo2 can be removed.

[0014] The rectifier circuit uses a current-doubling rectifier topology including diodes D1 and D2, and inductors Lo1 and Lo2. The cathode of diode D1 is connected to the first terminal of inductor Lo1, forming node V1; the anode of diode D2 is connected to the second terminal of inductor Lo2, forming node V2. The anode of diode D1 is connected to the first terminal of inductor Lo2, forming the DC negative terminal Vo-, and the cathode of diode D2 is connected to the second terminal of inductor Lo1, forming the DC positive terminal Vo+. Inductors Lo1 and Lo2 can be coupled or independent. Alternatively, diode D3 can replace inductor Lo1 or inductor Lo2; the replacement rule is that the anode and cathode of the switching transistor D3 correspond to the connection positions of the first and second terminals of inductors Lo1 and Lo2, respectively.

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

[0016] When the second terminal of inductor La is connected to node Vb of the asymmetric half-bridge, the second terminal of capacitor C1 can be connected to node GND or, instead, to the positive output terminal of the rectifier bridge. This improves control stability but increases input current ripple.

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

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

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

[0020] To achieve bidirectional energy flow or synchronous rectification, the rectifier bridge uses bidirectional thyristors or switching transistors, replacing diodes D1, D2, and D3 in the rectifier circuit with switching transistors Q3, Q4, and Q5. The replacement rule is that the drain and source of the switching transistors correspond to the cathode and anode of the diodes, respectively. Bidirectional energy flow refers to the bidirectional flow of electrical energy between the AC and DC sides.

[0021] If the voltage multiplier and current multiplier rectifier circuit of the asymmetric half-bridge AC-DC single-stage converter 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, it becomes a DC-DC converter.

[0022] For the voltage multiplier and current multiplier rectifier circuits of the aforementioned asymmetric half-bridge AC-DC single-stage converter, single-stage PFC conversion can be achieved by applying asymmetric complementary PWM control to the asymmetric half-bridge, resulting in high power factor and stable DC output. Specifically, two asymmetric and complementary PWM pulse signals with dead time drive the gates of the switching transistors Q1 and Q2 of the converter bridge, respectively, to control the complementary on / off switching of Q1 and Q2. The term "asymmetric and complementary" means that the duty cycles of the two PWM pulses are generally not equal, and their sum equals 1 when dead time is ignored.

[0023] Compared with the prior art, this utility model has the following advantages.

[0024] 1) This utility model adopts a single-stage AC-DC conversion, which can achieve both power factor correction and stable DC output.

[0025] 2) This utility model adopts asymmetric half-bridge complementary PWM control, which can realize zero-voltage soft switching (ZVS).

[0026] 3) The topology of this utility model belongs to the isolated double-ended conversion, which can transmit high power.

[0027] 4) The voltage doubler rectifier topology of this invention halves and balances the voltage stress of the diode and inductor, reduces current ripple, and is beneficial for high voltage output applications.

[0028] 5) The current-doubling rectifier topology of this utility model halves the current stress of the diode, inductor and secondary winding, thereby reducing losses and making it beneficial for high current output applications.

[0029] 6) This utility model has a simplified topology, is easy to control, has high reliability, and is low-cost and highly efficient. Attached Figure Description

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

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

[0032] Figure 3 The schematic diagram of the third embodiment of the voltage doubler rectifier circuit of the asymmetric half-bridge AC-DC single-stage converter.

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

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

[0035] Figure 6 The sixth embodiment of the voltage doubler rectifier circuit for an asymmetric half-bridge AC-DC single-stage converter is shown in the schematic diagram.

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

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

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

[0039] Figure 10 Schematic diagram of Example 4 of the current-doubling rectifier circuit for an asymmetric half-bridge AC-DC single-stage converter.

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

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

[0042] In the diagram, 1—rectifier bridge, 2—asymmetrical half-bridge, 3—transformer, 4—rectifier circuit; La—inductor, Cb, Co—capacitors; Q1, Q2, Q3, Q4—switching transistors, D1, D2, D3—diodes, C1, C2, C3, C4—capacitors, Lo1, Lo2—inductors; Np—primary winding, Ns—secondary winding. s —Alternating current power supply.

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

[0044] The present invention will now be described and analyzed in detail 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] To reiterate, the serial numbers used in this patent application to designate devices or methods, such as "first," "second," etc., are merely for distinguishing the described objects and do not have any sequential or technical meaning. They should not be construed as indicating their relative importance or implicitly specifying the number of technical features. Unless otherwise specified, the term "connection" in this patent application includes both direct and indirect connections.

[0046] 1. Preferred embodiment of the present invention

[0047] like Figures 1-12 As shown, the voltage multiplier and current multiplier rectifier circuit of the asymmetric half-bridge AC-DC single-stage converter consists 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 first embodiment of the voltage doubler rectifier circuit of the asymmetric half-bridge AC-DC single-stage converter is shown, which consists 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 doubler rectifier topology, including diodes D1 and D2, inductors Lo1 and Lo2, and capacitors C3 and C4. The cathode of diode D1 is connected to the negative terminal of capacitor C4, serving as node V1. The anode of diode D2 is connected to the positive terminal of capacitor C3, serving as node V2. The anode of diode D1 is connected to the negative terminal of capacitor C3, serving as the DC negative terminal Vo-. The cathode of diode D2 is connected to the positive terminal of capacitor C4 and the first terminal of inductor Lo1. The second terminal of inductor Lo1 serves as the DC positive terminal Vo+. The two ends of inductor Lo2 are connected to nodes V1 and V2 respectively. Inductors Lo1 and Lo2 can be coupled or independent.

[0050] The transformer (3) 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. Terminal S1 and terminal P1 are the same type of terminal, and terminal S2 and terminal P2 are the same type of terminal.

[0051] The asymmetric half-bridge (2) includes capacitors C1 and C2 and switching transistors Q1 and Q2. The switching transistors are, but are not limited to, MOSFETs or IGBTs. The first ends of capacitors C1 and C2 are connected as node Va, and the second end of capacitor C2 is connected to the drain of switching transistor Q2 as node Vd. The source of switching transistor Q2 is connected to the drain of switching transistor Q1 as node Vb, and the source of switching transistor Q1 is connected to the second end of capacitor C1 as node GND.

[0052] The rectifier bridge (1) uses, but is not limited to, diodes, thyristors or switching transistors. It is a four-terminal network with a positive output terminal, a negative output terminal and two AC input terminals.

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

[0054] In the first embodiment, two points need to be explained: First, the second end of inductor La is connected to node Vb of the asymmetric half-bridge (2). At this time, the function of inductor La is energy storage, and its inductance is relatively large. Second, the function of capacitor Cb is DC blocking, and the average voltage across capacitor Cb is zero in steady state. With these two points as necessary conditions, 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 current values ​​of inductors Lo1 and Lo2 are equal.

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

[0056] Figure 3The diagram shows a third embodiment of the voltage doubler rectifier circuit for an asymmetric half-bridge AC-DC single-stage converter. This third embodiment is... Figure 2 Based on the second embodiment shown, the rectifier bridge (1) uses a switching transistor, and the diodes D1 and D2 in the rectifier circuit (4) are replaced with switching transistors Q3 and Q4. The drain and source of the switching transistors are connected to the cathode and anode of the original diodes, respectively. The converter circuit of the third embodiment is capable of bidirectional AC-DC power flow. The transformer (3) has a bias magnetism.

[0057] Figure 4 The diagram shows a fourth embodiment of the voltage doubler rectifier circuit for an asymmetric half-bridge AC-DC single-stage converter. This fourth embodiment is... Figure 2 Based on the second embodiment shown, the inductor Lo2 is further removed. The secondary winding Ns takes on the function of the original inductor Lo2, and the DC component of its current increases, resulting in increased bias magnetism of the transformer (3). The advantages of this embodiment are further circuit simplification and lower cost.

[0058] Figure 5 The image shows a fifth embodiment of the voltage doubler rectifier circuit for an asymmetric half-bridge AC-DC single-stage converter. This fifth embodiment is... Figure 4 Based on the fourth embodiment shown, the switching transistor Q2 and capacitor C2 in the asymmetric half-bridge (2) are further removed, and the negative terminal of capacitor Co is connected to node V2. The efficiency is improved, but the output ripple current increases. When the switching transistor Q1 is turned off, its voltage spike is very high, so the leakage inductance of the transformer (3) needs to be minimized.

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

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

[0061] Figure 7 The diagram shows an embodiment 1 of an asymmetric half-bridge AC-DC single-stage converter current multiplier rectifier circuit, which consists 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, and inductors Lo1 and Lo2. The cathode of diode D1 is connected to the first terminal of inductor Lo1 as node V1, and the anode of diode D2 is connected to the second terminal of inductor Lo2 as node V2; the anode of diode D1 is connected to the first terminal of inductor Lo2 as the DC negative terminal Vo-, and the cathode of diode D2 is connected to the second terminal of inductor Lo1 as the DC positive terminal Vo+. Inductors Lo1 and Lo2 can be coupled or independent.

[0063] Example 1 of this current-doubling rectifier circuit and Figure 1 Compared to the first embodiment of the voltage doubler rectifier circuit shown, the difference is that the rectifier circuit (4) adopts a current doubler rectifier topology. The topology and connection relationships 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 block DC and store energy. In steady state, the average voltage across the capacitor Cb and Co is equal, so the capacitor Cb is necessary.

[0064] Figure 8 The diagram shows Example 2 of an asymmetric half-bridge AC-DC single-stage converter current multiplier rectifier circuit. This Example 2 is related to... Figure 7 Compared to Example 1, the difference is that the second end of the inductor La is connected to node Va of the asymmetric half-bridge (2), and its function is filtering; the inductance is smaller (approximately 1 / 10 of that in Example 1). The transformer (3) has a bias magnetism. The capacitor Cb is necessary.

[0065] Figure 9 The diagram shows Example 3 of an asymmetric half-bridge AC-DC single-stage converter current multiplier rectifier circuit. This Example 3 is... Figure 8 Based on Example 2, the rectifier bridge (1) uses a switching transistor, and the diodes D1 and D2 in the rectifier circuit (4) are replaced with switching transistors Q3 and Q4. The drain and source of the switching transistors are connected to the cathode and anode of the original diodes, respectively. The converter circuit of Example 3 is capable of bidirectional AC-DC power flow. The transformer (3) has a bias magnetism.

[0066] Figure 10 The diagram shows Example 4 of an asymmetric half-bridge AC-DC single-stage converter current multiplier rectifier circuit. This Example 4 is... Figure 8 Based on the illustrated embodiment 2, the switching transistor Q2 and capacitor C2 in the asymmetric half-bridge (2) are removed. When the switching transistor Q1 is turned off, its voltage spike is very high, so the leakage inductance of the transformer (3) needs to be minimized.

[0067] Figure 11 The diagram shows Example 5 of an asymmetric half-bridge AC-DC single-stage converter current multiplier rectifier circuit. This Example 5 is... Figure 8Based on Example 2 shown, inductor Lo2 is replaced by diode D3, with the anode and cathode of diode D3 connected to the anodes of diodes D1 and D2, respectively. This eliminates the need for the bulky inductor Lo2, but the circuit no longer possesses symmetry.

[0068] Figure 12 The diagram shows Example 6 of an asymmetric half-bridge AC-DC single-stage converter current multiplier rectifier circuit. This Example 6 is... Figure 8 Based on the embodiment 2 shown, the inductor Lo1 is replaced by diode D3, and the switching transistor Q2 and capacitor C2 in the asymmetric half-bridge (2) are removed.

[0069] Examples 4 and 6 of the asymmetric half-bridge AC-DC single-stage converter current multiplier rectifier circuit are applicable to AC power supply u. s When the voltage is low, but the switching transistor Q1 has a high voltage rating, the circuit can be simplified and the cost reduced.

[0070] All embodiments of the voltage multiplier and current multiplier rectifier circuit of the asymmetric half-bridge AC-DC single-stage converter are described below. The rectifier bridge (1) is removed, and the first end of the inductor La and the node GND of the asymmetric half-bridge (2) are connected to the positive and negative terminals of the DC power supply, respectively, thus forming a DC-DC converter.

[0071] 2. Working principle of this utility model

[0072] For the voltage multiplier and current multiplier rectifier circuits of the above-mentioned asymmetric half-bridge AC-DC single-stage converter, by applying asymmetric complementary PWM control to the asymmetric half-bridge (2), a single-stage AC-DC conversion can be completed, achieving a high power factor and stable DC output. That is, two asymmetric and complementary PWM pulse signals containing dead time drive the gates of the switching transistors Q1 and Q2 of the converter bridge respectively, so as to control the switching transistors Q1 and Q2 to perform complementary on-off switching. 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 multiplier and current multiplier 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 Voltage Doubler Rectifier Circuit for Asymmetric Half-Bridge AC-DC Single-Stage Converter

[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 The voltage u is applied to the first terminal of inductor La. a The expression is:

[0076]

[0077] In the formula, U s AC power supply u s The effective value of ω is u s angular frequency.

[0078] Set the voltage across capacitor C1 to V. a The voltage across capacitor C2 is V. c The voltage between node Vd and GND of the asymmetric half-bridge (2) is V. d Then we have:

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

[0080] like Figure 2 As shown, if the second terminal of inductor La is connected to node Va, then the voltage u a After being filtered by inductor La, the current is applied to capacitor C1, V a =u a .like Figure 1 As shown, if the second terminal of inductor La is connected to node Vb, then the voltage u a After being connected to capacitor C1 via inductor La and primary winding Np, the volt-second balance relationship between inductor La and primary winding Np remains the same during the switching process of transistors Q1 and Q2 (see equation (E-5) below), thus still yielding V. a =u a .

[0081] Let the voltage across capacitor Cb be V. e The voltage across capacitor Co (i.e., the DC output voltage) is V. o The voltage across capacitor C3 is V3, and the voltage across capacitor C4 is V4. Note: The voltages set refer 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. Let the turns ratio of transformer (3) be n, and ignore the leakage inductance of transformer (3), then we have:

[0083] V s =n·V p (E-3)

[0084] To simplify the analysis, we ignore the on-resistance and dead time of switching transistors Q1 and Q2, and the on-voltage drop and switching time of diodes D1 and D2.

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

[0086] When switch Q1 is off and Q2 is on, terminal P2 of the primary winding Np of transformer (3) is connected to node Vd, and the voltage V of capacitor C2 is... c When added to the primary winding Np, V p =-V c The induced voltage on the secondary winding Ns is V. s =-n·V c At this time, diodes D1 and D2 of the rectifier circuit (4) are turned on; the secondary winding Ns continues to flow through diodes D1 and D2 and capacitors C3 and C4, and inductors Lo2 and Lo1 continue to flow through diodes D1 and D2 to capacitor Co (i.e., the DC output terminal), and inductors Lo1 and Lo2 release energy. The portion of the sum of the currents in the secondary winding Ns and inductor Lo2 that exceeds the current in inductor Lo1 charges capacitors C3 and C4.

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

[0088] V3 = V4 = n·V c +V e (E-4)

[0089] If the duty cycle of switch Q1 is set to D, then the duty cycle of switch Q2 is (1-D). Based on the volt-second balance principle of switching, the voltage relationship of the primary winding Np is obtained as follows:

[0090] u a ·D=V c ·(1-D)(E-5)

[0091] The voltages applied to inductors Lo2 and Lo1 in 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] By combining equations (E-7) to (E-4), we can derive:

[0095]

[0096] As can be seen from equation (E-8), the DC output voltage V o The voltage can be adjusted and stabilized by regulating 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 achieves power factor correction. The "2 times" relationship in the formula precisely illustrates that it is a "voltage doubler rectification". The average voltage of capacitor Cb is zero, so it can be removed.

[0097] Let the current in inductor Lo1 be I. o (That is, the output current), the current in inductor Lo2 is I. o2 The forward current of the secondary winding Ns of transformer (3) is I. s+ The negative current is I s- (Flow out of terminal S1 is positive, flow in 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 charging / discharging current of capacitor Cb is equal to the forward / reverse current of the secondary winding Ns, respectively.

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

[0099]

[0100] When switching transistor Q1 is off and Q2 is on, diodes D1 and D2 are conducting, and the current relationship is as follows:

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

[0102] To maintain the charging and discharging balance of capacitors C3, C4, and Cb, the following relationship must be satisfied:

[0103]

[0104] By combining equations (E-9), (E-10), and (E-11), the following can be derived:

[0105]

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

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

[0108] like Figure 4 As shown, by removing both capacitor Cb and inductor Lo2, the secondary winding Ns takes on the role of inductor Lo2, increasing the DC component of its current and thus increasing the bias magnetism of transformer (3). The advantages are: simplified circuit and lower cost. The current state of the secondary winding Ns will be analyzed in detail below.

[0109] In equations (E-9) and (E-10), I o2 =0, from which we can deduce:

[0110]

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

[0112]

[0113] Next, we will analyze the maximum operating voltages of the switching transistors Q1 and Q2 and the diodes D1 and D2.

[0114] The highest operating voltage of switching transistors Q1 and Q2 is the maximum voltage V between node Vd and GND of the asymmetric half-bridge (2). dM Combining equations (E-2) and (E-8), we obtain:

[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 turns ratio n of transformer (3), the highest operating voltages of switching transistors Q1 and Q2 and diodes D1 and D2 in the voltage multiplier rectifier circuit can be balanced.

[0119] 2.2 Current-doubling rectifier circuit for asymmetric half-bridge AC-DC single-stage converter

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

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

[0122] When the switching transistor 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 provide freewheeling current to the capacitor Co (i.e., the DC output terminal) through the diodes D1 and D2, respectively, 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 diodes D1 and D2 in rectifier circuit (4) are turned on, the voltages across capacitors Cb and Co satisfy the following relationship:

[0124] V o +V e =n·V c (E-17)

[0125] The inductances of inductors Lo1 and Lo2 should be equal, and they can be coupled or independent. The duty cycles of switches Q1 and Q2 are set to D and (1-D), respectively. According to the volt-second balance principle of switching, the voltages applied to inductors Lo1 and Lo2 are the same and satisfy the following relationship:

[0126]

[0127] By combining equations (E-18), (E-17), and (E-5), the following can be derived:

[0128]

[0129] As can be seen from equation (E-19), the DC output voltage V o The voltage can be adjusted and stabilized by regulating 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 achieves power factor correction. The average voltages of capacitors Cb and Co are equal, therefore Cb is necessary.

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

[0131] I s+ ·D=I L ·D(E-20)

[0132] To maintain the charging and discharging 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., the DC output terminal) oΣ for:

[0135]

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

[0137]

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

[0139] In the current-doubling rectifier circuit of the asymmetric half-bridge AC-DC single-stage converter, the maximum operating voltages of the switching transistors 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), adjusting the turns ratio n of transformer (3) can balance the highest operating voltages of switching transistors Q1 and Q2 and diodes D1 and D2 in the current-doubling rectifier circuit. When inductors Lo1 and Lo2 are coupled, it is more conducive to the dynamic balancing of the reverse voltages of diodes D1 and D2.

[0144] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent topological transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. Asymmetric half-bridge AC-DC single-stage converter voltage multiplier and current multiplier rectifier circuit, including rectifier bridge (1), asymmetric half-bridge (2), transformer (3), rectifier circuit (4), inductor La and capacitors Cb and Co; rectifier bridge (1) is a four-terminal network with positive output terminal, negative output terminal and two AC input terminals; The asymmetric half-bridge (2) includes capacitors C1 and C2 and switching transistors Q1 and Q2; the first ends of capacitors C1 and C2 are connected as node Va, the second end of capacitor C2 is connected to the drain of switching transistor Q2 as node Vd, the source of switching transistor Q2 is connected to the drain of switching transistor Q1 as node Vb, and the source of switching transistor Q1 is connected to the second end of capacitor C1 as node GND; or the switching transistor Q2 and capacitor C2 are removed. The transformer (3) 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. Terminal S1 and terminal P1 are the same type of terminal, and terminal S2 and terminal P2 are the same type of terminal. Its features are: The rectifier circuit (4) adopts a voltage doubler rectifier topology or a current doubler rectifier topology; The voltage multiplier rectifier topology used in the rectifier circuit (4) includes: diodes D1 and D2, inductors Lo1 and Lo2, and capacitors C3 and C4; the cathode of diode D1 is connected to the negative terminal of capacitor C4 as node V1, the anode of diode D2 is connected to the positive terminal of capacitor C3 as node V2; the anode of diode D1 is connected to the negative terminal of capacitor C3 as the DC negative terminal V. o - The cathode of diode D2 is connected to the positive terminal of capacitor C4 and the first terminal of inductor Lo1. The second terminal of inductor Lo1 serves as the DC positive terminal V. o +; or the cathode of diode D2 is connected to the positive terminal of capacitor C4, serving as the positive DC terminal V. o +, The anode of diode D1 is connected to the cathode of capacitor C3 and the first terminal of inductor Lo1. The second terminal of inductor Lo1 serves as the DC negative terminal V. o -; Inductor Lo2 is connected to nodes V1 and V2 respectively. Inductor Lo2 and Lo1 can be coupled or independent. The current-doubling rectifier topology used in the rectifier circuit (4) includes: diodes D1 and D2, inductors Lo1 and Lo2; the cathode of diode D1 is connected to the first terminal of inductor Lo1 as node V1, and the anode of diode D2 is connected to the second terminal of inductor Lo2 as node V2; the anode of diode D1 is connected to the first terminal of inductor Lo2 as the DC negative terminal V. o - The cathode of diode D2 is connected to the second terminal of inductor Lo1, serving as the DC positive terminal V. o +; Inductors Lo1 and Lo2 can be coupled or independent; The connection relationships of the components in the voltage multiplier and current multiplier rectifier circuit of the asymmetric half-bridge AC-DC single-stage converter are as follows: AC power supply u s The two ends are connected to the two AC input terminals of the rectifier bridge (1). The negative output terminal of the rectifier bridge (1) is connected to node GND. The positive output terminal of the rectifier bridge (1) is connected to the first terminal of inductor La. The second terminal of inductor La is connected to node Va or node Vb of the asymmetric half-bridge (2). Nodes Va and Vb of the asymmetric half-bridge (2) are respectively connected to terminals P1 and P2 of the primary winding Np of the transformer (3). Terminal S1 of the secondary winding Ns is connected to node V1 of the rectifier circuit (4). Capacitor Cb is connected in series between terminal S2 of the secondary winding Ns and node V2 of the rectifier circuit (4). Alternatively, terminal S2 of the secondary winding Ns is connected to node V2 of the rectifier circuit (4). Capacitor Cb is connected in series between terminal S1 of the secondary winding Ns and node V1 of the rectifier circuit (4). The positive and negative terminals of capacitor Co are respectively connected to the DC positive terminal V of the rectifier circuit (4). o + and DC negative terminal V o -; When the second end of inductor La is connected to node Vb of the asymmetric half-bridge (2), the second end of capacitor C1 is connected to node GND or is changed to be connected to the positive output terminal of rectifier bridge (1).

2. The voltage multiplier and current multiplier rectifier circuit for the asymmetric half-bridge AC-DC single-stage converter according to claim 1, characterized in that: When the rectifier circuit (4) adopts a voltage doubler rectifier topology, if the second terminal of inductor Lo1 is used as the DC positive terminal V o +, then the negative terminal of capacitor Co is connected to the negative DC terminal V. o -Or connect node V2 of the rectifier circuit (4); if the second end of inductor Lo1 is used as the DC negative terminal V o - Then the positive terminal of capacitor Co is connected to the positive DC terminal V. o + or connect node V1 of rectifier circuit (4); when rectifier circuit (4) is used as current source output, remove capacitor Co.

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

4. The voltage multiplier and current multiplier rectifier circuit for the asymmetric half-bridge AC-DC single-stage converter according to claim 1, characterized in that: When the rectifier circuit (4) adopts a current-doubling rectifier topology, the diode D3 replaces the inductor Lo1 or the inductor Lo2. The replacement rule is that the connection positions of the anode and cathode of the switching transistor D3 correspond to the connection positions of the first and second ends of the inductor Lo1 or Lo2, respectively.

5. The voltage multiplier and current multiplier rectifier circuit for the asymmetric half-bridge AC-DC single-stage converter according to claim 1, characterized in that: The diodes D1 and D2 in the rectifier circuit (4) are replaced with switching transistors Q3 and Q4. The replacement rule is that the drain and source of the switching transistor correspond to the connection positions of the cathode and anode of the diode, respectively. The rectifier bridge (1) uses diodes, thyristors, or switching transistors. The switching transistors are, but are not limited to, MOSFETs or IGBTs.

6. The voltage multiplier and current multiplier rectifier circuit for the asymmetric half-bridge AC-DC single-stage converter according to claim 1, characterized in that: If the rectifier bridge (1) 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 (2), it becomes a DC-DC converter.

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