Asymmetric half-bridge AC-DC single-stage converter
By designing an asymmetric half-bridge AC-DC single-stage converter, combining a rectifier bridge, an asymmetric half-bridge, a transformer, and a rectifier circuit, high power factor correction and stable DC output are achieved. This solves the problems of complex circuits, low efficiency, and high cost in existing technologies, and enables high power transmission and zero-voltage soft switching.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-22
- Publication Date
- 2026-03-27
AI Technical Summary
Existing high-power isolated AC-DC converters suffer from problems such as complex circuitry, low efficiency, poor reliability, high cost, and large size, and are difficult to achieve high-power transmission and soft switching.
An asymmetric half-bridge AC-DC single-stage converter is adopted, which utilizes a combination of rectifier bridge, asymmetric half-bridge, transformer, rectifier circuit, inductor and capacitor. Power factor correction and stable DC output are achieved through asymmetric complementary PWM control, and diode reverse voltage division equalization and multi-voltage output are achieved through inductive coupling or taps.
It achieves high power transmission, reduces bias current, improves conversion efficiency and reliability, simplifies circuit structure, reduces cost, and enables zero-voltage soft switching.
Smart Images
Figure CN224054100U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a kind of asymmetric half-bridge AC-DC single-stage converter, it is a switching power supply technology, belong to new energy power conversion and power electronics technical field. BACKGROUND
[0002] At present, the general technical scheme of high-power high-power factor isolated AC-DC converter is two-stage circuit topology. The first stage is high-power factor AC-DC non-isolated conversion, generally using Boot conversion topology; the second stage is DC-DC isolated conversion, mainly including phase-shifted full-bridge topology and LLC conversion topology.
[0003] This two-stage circuit scheme has inherent deficiencies: (1) complex circuit. (2) The whole machine efficiency is reduced. (3) Reliability is reduced. (4) Higher cost. (5) Larger size. These are caused by two-stage power conversion. In addition, the first stage of high-power factor AC-DC non-isolated converter is not easy to realize soft switching.
[0004] The so-called "single-stage PFC (Power Factor Correction) converter" is an isolated AC-DC converter, which can realize high power factor on the AC side and stable DC side output voltage with only one-stage power conversion.
[0005] For isolated single-stage PFC converter, flyback topology is mostly used. Flyback converter belongs to single-ended converter, and the transmitted power cannot be too large, generally used for small 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 has a narrow output voltage regulation range, and the active current component in the primary side is large. Full-bridge topology with phase-shifted control can also be used for isolated single-stage PFC conversion, but four switching tubes are needed for active control on the primary and secondary sides, which requires many devices and has high cost. Some so-called combined single-stage converters use the combination of Boot and bridge topologies, which have complex circuits and no obvious advantages. There are also asymmetric double-ended output single-stage topologies, but the voltage and current stress of the rectifier circuit is large, especially in low-voltage high-current applications, which has many disadvantages.
[0006] In addition, the existing isolated single-stage PFC converter topology generally uses the secondary winding taps of the transformer or increases the secondary winding when voltage division or multi-voltage output is needed, which is difficult to manufacture in high-power applications.
[0007] The above content is only used to assist in understanding the technical scheme of the utility model, and does not mean that the above is prior art. UTILITY MODEL CONTENT
[0008] The utility model discloses a purpose is, overcome above-mentioned prior art's insufficient, propose a kind of asymmetric half-bridge AC-DC single-stage converter.The converter is a kind of isolated single-stage PFC circuit, design compact rectifier filter topology, reduce or eliminate transformer's bias magnetic current.Inductive coupling or tap is utilized to realize diode reverse voltage division balance and multiple voltage output.The converter belongs to double-ended conversion, can transmit high power;And switching tube can realize ZVS soft switching, improve conversion efficiency.Converter uses asymmetric complementary PWM control, realizes power factor correction, and stable DC output.
[0009] The technical scheme of the utility model is as follows.
[0010] Asymmetric half-bridge AC-DC single-stage converter is formed by rectifier bridge, asymmetric half-bridge, transformer, rectifier circuit, inductance La and capacitor Cb.Rectifier bridge is four-terminal network, has positive output end, negative output end and two AC input ends.
[0011] Asymmetric half-bridge includes capacitor C1, C2 and switching tube Q1, Q2.Capacitor C1, C2 first end is connected as node Va, capacitor C2 second end is connected with switching tube Q2 drain as node Vd;Switching tube Q2 source and switching tube Q1 drain are connected as node Vb, and switching tube Q1 source and capacitor C1 second end are connected as node GND.
[0012] Transformer includes primary winding Np and secondary winding Ns, and primary winding Np has terminal P1 and P2, and secondary winding Ns has terminal S1 and S2;Terminal S1 and terminal P1 are same name end, and terminal S2 and terminal P2 are same name end.
[0013] Rectifier circuit includes diode D1, inductance Lo and capacitor Co.Diode D1 anode and inductance Lo first end are connected, as node V1, and diode D1 cathode and capacitor Co positive pole are connected, as positive terminal Vo+, and inductance Lo second end and capacitor Co negative pole are connected, as negative terminal Vo-.
[0014] The connection relationship of asymmetric half-bridge AC-DC single-stage converter is: AC power supply u sTwo AC input terminals of the rectifier bridge are connected to two ends, the negative output terminal of the rectifier bridge is connected to the node GND, the positive output terminal of the rectifier bridge (1) is connected to the first end of the inductor La, the second end of the inductor La is connected to the node Va or the node Vb of the asymmetric half-bridge, and the nodes Va and Vb of the asymmetric half-bridge are respectively connected to the terminals P2 and P1 of the primary winding Np of the transformer. The node V1 of the rectifier circuit is connected to the terminal S1 of the secondary winding Ns, the terminal S2 of the secondary winding Ns is connected to the first end of the capacitor Cb, and the second end of the capacitor Cb is connected to the positive terminal Vo+ or the negative terminal Vo-; or, the capacitor Cb is connected in series between the node V1 of the rectifier circuit and the terminal S1 of the secondary winding Ns, and the terminal S2 of the secondary winding Ns is connected to the positive terminal Vo+ or the negative terminal Vo-.
[0015] 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 of the asymmetric half-bridge is connected to the node GND or is changed to be connected to the positive output terminal of the rectifier bridge. The control stability is improved, but the input current ripple is increased.
[0016] When the second end of the capacitor Cb or the terminal S2 of the secondary winding Ns is connected to the negative terminal Vo-, the capacitor Cb is retained or removed; when the second end of the capacitor Cb or the terminal S2 of the secondary winding Ns is connected to the positive terminal Vo+, the capacitor Co is retained or removed (if the capacitor Co is removed, the converter is used for current source output); when the capacitor Cb is removed, and the second end of the inductor La is connected to the node Vb of the asymmetric half-bridge, the inductor Lo is retained or removed.
[0017] The asymmetric half-bridge AC-DC single-stage converter described above can also adopt a reverse dual connection relationship, that is, the anode and cathode of the diode D1 in the rectifier circuit are exchanged in the connection position, the positive and negative poles of the capacitor Co are exchanged in the connection position, and the positive terminal Vo+ and the negative terminal Vo- are exchanged; at the same time, the terminals S1 and S2 of the secondary winding Ns of the transformer are exchanged in the connection position.
[0018] In order to realize AC-DC bidirectional energy flow or synchronous rectification, the rectifier bridge adopts bidirectional thyristor or switch tube, and the diode D1 of the rectifier circuit is replaced by a switch tube Q3; the replacement rule is that the drain and source of the switch tube correspond to the connection position of the cathode and anode of the diode respectively. The so-called bidirectional energy flow refers to the bidirectional flow of electrical energy between the AC side and the DC side.
[0019] In order to reduce the reverse voltage of the diode D1, a voltage division rectifier circuit is proposed to replace the rectifier circuit. In order to meet the demand of multiple voltage output, a multiple output rectifier circuit is proposed to replace the rectifier circuit.
[0020] The voltage dividing rectifier circuit comprises diodes D1 and D2, capacitors Co1 and Co2, and inductors Lo1 and Lo2. The inductors Lo1 and Lo2 are coupled. The anode of the diode D1 is connected to the first end of the inductor Lo1 as a node V1, and the cathode of the diode D2 is connected to the second end of the inductor Lo2 as a node V2. The negative electrode of the capacitor Co1 is connected to the positive electrode of the capacitor Co2 as a node Vo2. The positive electrode of the capacitor Co1 is the positive terminal Vo+, and the negative electrode of the capacitor Co2 is the negative terminal Vo-. The second end of the inductor Lo1 and the first end of the inductor Lo2 are connected to the node Vo2. The cathode of the diode D1 is connected to the positive terminal Vo+, and the anode of the diode D2 is connected to the negative terminal Vo-. Alternatively, the cathode of the diode D1 and the anode of the diode D2 are connected to the node Vo2. The first end of the inductor Lo2 is connected to the positive terminal Vo+, and the second end of the inductor Lo1 is connected to the negative terminal Vo-.
[0021] The connection relationship between the voltage dividing rectifier circuit and the transformer is that the terminal S1 of the secondary winding Ns of the transformer is connected to the node 1 of the voltage dividing rectifier circuit, and the capacitor Cb is connected in series between the node 2 and the terminal S2. Alternatively, the terminal S2 of the secondary winding Ns of the transformer is connected to the node 2 of the voltage dividing rectifier circuit, and the capacitor Cb is connected in series between the node 1 and the terminal S1. If the second end of the inductor Lo1 and the first end of the inductor Lo2 are connected to the node Vo2, the capacitor Cb is retained or removed.
[0022] The multi-output rectifier circuit comprises diodes D1 and D2, capacitors Co1 and Co2, and an inductor Lo. The inductor Lo has a first end, a second end, and a tap end. The first end of the inductor Lo is connected to the anode of the diode D1 as a node V1, and the tap end of the inductor Lo is connected to the anode of the diode D2. The second end of the inductor Lo is connected to the negative electrode of the capacitor Co2 as a negative terminal Vo-. The cathode of the diode D2 is connected to the positive electrode of the capacitor Co2 as a node Vo2. The cathode of the diode D1 is connected to the positive electrode of the capacitor Co1 as a positive terminal Vo+. The negative electrode of the capacitor Co1 is connected to the node Vo2 or the negative terminal Vo-.
[0023] The connection relationship between the multi-output rectifier circuit and the transformer is that the terminal S1 of the secondary winding Ns is connected to the node V1 or the tap end of the inductor Lo of the multi-output rectifier circuit. The terminal S2 of the secondary winding Ns is connected to the first end of the capacitor Cb. The second end of the capacitor Cb is connected to the positive terminal Vo+ or the negative terminal Vo- of the multi-output rectifier circuit. Alternatively, the terminal S1 of the secondary winding Ns is connected to the first end of the capacitor Cb. The second end of the capacitor Cb is connected to the node V1 or the tap end of the inductor Lo. The terminal S2 of the secondary winding Ns is connected to the positive terminal Vo+ or the negative terminal Vo-.
[0024] When the second end of the capacitor Cb or the terminal S2 of the secondary winding Ns is connected to the negative terminal Vo- of the multi-output rectifier circuit, the capacitor Cb is retained or removed.
[0025] The multi-output rectifier circuit adopts a reverse dual connection relationship, that is, the anode and cathode of diodes D1 and D2 are reversely connected, the positive and negative poles of capacitors Co1 and Co2 are reversely connected, the positive terminal Vo+ and the negative terminal Vo- are reversely connected, and the terminals S1 and S2 of the secondary winding Ns of the transformer are reversely connected.
[0026] When the voltage of the AC power supply us is low and the withstand voltage of the switch tube Q1 of the asymmetric half-bridge is high, the switch tube Q2 and the capacitor C2 are removed to simplify the circuit and reduce the cost.
[0027] The asymmetric half-bridge AC-DC single-stage converter 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.
[0028] For the asymmetric half-bridge AC-DC single-stage converter, single-stage PFC conversion can be realized by applying asymmetric complementary PWM control to the asymmetric half-bridge, so that high power factor and stable DC output are realized. That is, two asymmetric and complementary PWM pulse signals containing dead time are used to drive the gates of the switch tubes Q1 and Q2 of the conversion bridge to control the switch tubes Q1 and Q2 to realize complementary on-off conversion. The asymmetric and complementary PWM pulse signals are not equal in duty cycle, and the sum of the two PWM pulse signals is equal to 1 when the dead time is ignored.
[0029] Compared with the prior art, the utility model has the following advantages.
[0030] 1) The utility model adopts AC-DC single-stage conversion, which realizes power factor correction and stable DC output.
[0031] 2) The utility model adopts asymmetric half-bridge complementary PWM control, which can realize zero voltage soft switching (ZVS).
[0032] 3) The topology of the utility model belongs to isolated double-ended conversion, which can transmit large power.
[0033] 4) The topology of the utility model can reduce or eliminate the bias magnetic current of the transformer.
[0034] 5) The utility model realizes diode reverse voltage division balance or multi-voltage output by using inductive coupling or tapping.
[0035] 6) The topology of the utility model is simple, easy to control, high in reliability, low in cost and high in efficiency. BRIEF DESCRIPTION OF DRAWINGS
[0036] Figure 1 The first embodiment schematic diagram of the asymmetric half-bridge AC-DC single-stage converter.
[0037] Figure 2 Second embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter.
[0038] Figure 3 Third embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter.
[0039] Figure 4 Fourth embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter.
[0040] Figure 5 Fifth embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter.
[0041] Figure 6 Sixth embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter.
[0042] Figure 7 First embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter voltage dividing rectifier circuit.
[0043] Figure 8 Second embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter voltage dividing rectifier circuit.
[0044] Figure 9 Third embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter voltage dividing rectifier circuit.
[0045] Figure 10 First embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter multi-output circuit.
[0046] Figure 11 Second embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter multi-output circuit.
[0047] Figure 12 Third embodiment schematic diagram of asymmetric half-bridge AC-DC single-stage converter multi-output circuit.
[0048] In the figure, 1 - rectifier bridge, 2 - asymmetric half-bridge, 3 - transformer, 4 - rectifier circuit, 5 - voltage dividing rectifier circuit, 6 - multi-output rectifier circuit; La - inductor, Cb - capacitor; Q1, Q2, Q3 - switch tube, D1, D2 - diode, C1, C2, Co, Co1, Co2 - capacitor, Lo, Lo1, Lo2 - inductor, Np - primary winding, Ns - secondary winding; us - AC power supply.
[0049] 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, GND, and Vo2 are the node symbols; Vo+ is the positive terminal, and Vo- is the negative terminal. Detailed Implementation
[0050] 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.
[0051] To reiterate, the serial numbers used in this patent application to designate devices or methods, such as "first," "second," etc., are solely 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.
[0052] 1. Preferred embodiments of the present invention.
[0053] like Figures 1-6 As shown, 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 a capacitor Cb.
[0054] Figure 1 The first embodiment 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 a capacitor Cb.
[0055] 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.
[0056] 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 together 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.
[0057] 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.
[0058] The rectifier circuit (4) comprises a diode D1, an inductor Lo and a capacitor Co. The anode of the diode D1 is connected to the first end of the inductor Lo as a node V1, the cathode of the diode D1 is connected to the positive pole of the capacitor Co as a positive terminal Vo+, and the second end of the inductor Lo is connected to the negative pole of the capacitor Co as a negative terminal Vo-.
[0059] The connection relationship of the asymmetric half-bridge AC-DC single-stage converter is that the AC power supply u s The two AC input terminals 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 the node GND, the positive output terminal of the rectifier bridge (1) is connected to the first end of the inductor La, the second end of the inductor La is connected to the node Va of the asymmetric half-bridge (2), and the nodes Va and Vb of the asymmetric half-bridge (2) are respectively connected to the terminals P2 and P1 of the primary winding Np of the transformer (3); the node V1 of the rectifier circuit (4) is connected to the terminal S1 of the secondary winding Ns, the terminal S2 of the secondary winding Ns is connected to the first end of the capacitor Cb, and the second end of the capacitor Cb is connected to the negative terminal Vo-.
[0060] In the first embodiment, when the second end of the inductor La is connected to the node Va, the function of the inductor is filtering, and the inductance is small. When the second end of the capacitor Cb is connected to the negative terminal Vo-, the function is only direct current isolation, and the average voltage of the capacitor Cb is zero in the steady state (therefore, the Cb can be removed). The current of the capacitor Co is discontinuous, that is, the output current is discontinuous and the ripple is large (which can be improved when two-way interleaved parallel connection is used). The transformer (3) has magnetic bias (if the second end of the inductor La is connected to the node Vb, there is no magnetic bias)
[0061] Figure 2 The second embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. Compared with the first embodiment Figure 1 The difference between the second embodiment and the first embodiment is that the second end of the inductor La is connected to the node Vb of the asymmetric half-bridge (2), and the second end of the capacitor Cb is connected to the positive terminal Vo+. The current of the capacitor Co is continuous, that is, the output current is continuous and the ripple is small. Note: If the transformer needs to be used as a current source output, the capacitor Co can be removed.
[0062] In the second embodiment, two points need to be explained: first, the second end of the inductor La is connected to the node Vb, at this time the function of the inductor La is energy storage, and the inductance is large (about 10 times of the first embodiment). Second, the function of the capacitor Cb is direct current isolation and energy storage, and the average voltage of the capacitor Cb is equal to that of the capacitor Co in the steady state (the capacitor Cb must be retained). With these two points as necessary conditions, the transformer (3) has no magnetic bias, that is, the positive and negative amplitudes of the excitation current are equal in each working period. Note: If the second end of the inductor La is connected to the node Va of the asymmetric half-bridge (2), the transformer (3) has magnetic bias.
[0063] Figure 3The third embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. The third embodiment is based on the first embodiment Figure 1 The third embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. The third embodiment is based on the first embodiment
[0064] Figure 4 The fourth embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. The fourth embodiment is based on the first embodiment Figure 1 The fourth embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. The fourth embodiment is based on the first embodiment
[0065] Figure 5 The fifth embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. The fifth embodiment is based on the fourth embodiment Figure 4 The fifth embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. The fifth embodiment is based on the fourth embodiment
[0066] Figure 6 The sixth embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. The sixth embodiment is based on the fourth embodiment Figure 4 The sixth embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. The sixth embodiment is based on the fourth embodiment
[0067] Figure 7 The first embodiment of the asymmetric half-bridge AC-DC single-stage converter is shown. The first embodiment is based on the asymmetric half-bridge AC-DC single-stage converter
[0068] The voltage dividing rectifier circuit (5) comprises diodes D1 and D2, capacitors Co1 and Co2, and inductors Lo1 and Lo2. The inductors Lo1 and Lo2 are coupled. The anode of the diode D1 is connected to the first end of the inductor Lo1 as a node V1, and the cathode of the diode D2 is connected to the second end of the inductor Lo2 as a node V2. The negative electrode of the capacitor Co1 is connected to the positive electrode of the capacitor Co2 as a node Vo2, the positive electrode of the capacitor Co1 is the positive terminal Vo+, and the negative electrode of the capacitor Co2 is the negative terminal Vo-. The second end of the inductor Lo1 and the first end of the inductor Lo2 are connected to the node Vo2, the cathode of the diode D1 is connected to the positive terminal Vo+, and the anode of the diode D2 is connected to the negative terminal Vo-.
[0069] This embodiment 1 is based on the first embodiment shown in Figure 1 The rectifier circuit (4) is replaced by the voltage dividing rectifier circuit (5), and the capacitor Cb is connected in series between the terminal S2 of the secondary winding Ns and the node 2 of the voltage dividing rectifier circuit (5). The circuit topology, connection relationship and working principle of other parts remain unchanged.
[0070] In embodiment 1, the inductors Lo1 and Lo2 are directly connected, which is convenient for process manufacturing. The diodes D1 and D2 share the total reverse voltage. Since the inductors Lo1 and Lo2 are coupled and the capacitors Co1 and Co2 are clamped, the voltage division can be dynamically balanced.
[0071] Figure 8 As shown, the asymmetric half-bridge AC-DC single-stage converter voltage dividing rectifier circuit embodiment 2. This embodiment 2 is based on the second embodiment shown in Figure 2 The rectifier circuit (4) is replaced by the voltage dividing rectifier circuit (5), and the capacitor Cb is connected in series between the terminal S2 of the secondary winding Ns and the node 2 of the voltage dividing rectifier circuit (5). The circuit topology, connection relationship and working principle of other parts remain unchanged. The voltage dividing rectifier circuit (5) in this embodiment 2 is different from that in embodiment 1 in that the cathode of the diode D1 and the anode of the diode D2 are connected to the node Vo2, the first end of the inductor Lo2 is connected to the positive terminal Vo+, and the second end of the inductor Lo1 is connected to the negative terminal Vo-.
[0072] In embodiment 2, the diodes D1 and D2 are directly connected in series, which is convenient for semiconductor integration. Based on the same principle as embodiment 1, the reverse voltage division of the diodes D1 and D2 can be dynamically balanced.
[0073] Figure 9 As shown, the asymmetric half-bridge AC-DC single-stage converter voltage dividing rectifier circuit embodiment 3. This embodiment 3 is based on the embodiment 1 shown in Figure 7 The capacitor Cb is removed. The circuit is relatively simplified, and the basic characteristics of the circuit remain unchanged. The transformer (3) has changed in magnetic bias, which varies with the relative change of the inductance of the inductors Lo1 and Lo2 and the inductance of the transformer (3).
[0074] Figure 10 As shown in the asymmetric half-bridge AC-DC single-stage converter multi-output circuit embodiment one, it is composed of rectifier bridge (1), asymmetric half-bridge (2), transformer (3), multi-output rectifier circuit (6) and inductance La, capacitor Cb.
[0075] The multi-output rectifier circuit (6) comprises diodes D1 and D2, capacitors Co1 and Co2 and inductance Lo; the inductance Lo has a first end, a second end and a tap end; the first end of the inductance Lo is connected to the anode of the diode D1 as a node V1, the tap end of the inductance Lo is connected to the anode of the diode D2, and the second end of the inductance Lo is connected to the negative electrode of the capacitor Co2 as a negative terminal Vo-; the cathode of the diode D2 is connected to the positive electrode of the capacitor Co2 as a node Vo2, the cathode of the diode D1 is connected to the positive electrode of the capacitor Co1 as a positive terminal Vo+, and the negative electrode of the capacitor Co1 is connected to the node Vo2.
[0076] This embodiment one is in the asymmetric half-bridge AC-DC single-stage converter multi-output circuit embodiment one shown in the first embodiment, Figure 1 On the basis of the first embodiment, the rectifier circuit (4) is replaced by the multi-output rectifier circuit (6). The circuit topologies, connection relationships and working principles of other parts remain unchanged. The second end of the inductance La is connected to the node Va, and the function of the capacitor Cb is only to isolate direct current. The transformer (3) is magnetically biased.
[0077] The tap end of the inductance Lo is used, and the diode D2 and the capacitor Co2 are added to generate a voltage division output (i.e. a second output) Vo2. Compared with the voltage division rectifier circuit (5), there is only one diode in each voltage output loop, and the efficiency is higher.
[0078] Figure 11 As shown in the asymmetric half-bridge AC-DC single-stage converter multi-output circuit embodiment two, this embodiment two is in the asymmetric half-bridge AC-DC single-stage converter multi-output circuit embodiment one shown in the first embodiment, Figure 2 On the basis of the second embodiment, the rectifier circuit (4) is replaced by the multi-output rectifier circuit (6). The circuit topologies, connection relationships and working principles of other parts remain unchanged. The second end of the inductance La is connected to the node Vb, and the function of the capacitor Cb is to isolate direct current and store energy. The transformer (3) is not magnetically biased.
[0079] Figure 12 As shown in the asymmetric half-bridge AC-DC single-stage converter multi-output circuit embodiment three, this embodiment three is in the asymmetric half-bridge AC-DC single-stage converter multi-output circuit embodiment one shown in the first embodiment, Figure 10 On the basis of the first embodiment, the capacitor Cb is removed. The circuit is relatively simplified, and the basic characteristics of the circuit remain unchanged. The magnetic bias of the transformer (3) changes with the relative change of the inductance of the inductance Lo and the transformer (3).
[0080] 2, the working principle of the utility model
[0081] For the above asymmetric half-bridge AC-DC single-stage converter, by applying asymmetric complementary PWM control to the asymmetric half-bridge (2), single-stage AC-DC conversion can be completed, high power factor can be realized, and stable DC output can be achieved. That is, two asymmetric and complementary PWM pulse signals containing dead time drive the gates of the switching tubes Q1 and Q2 of the conversion bridge respectively to control the complementary on-off conversion of the switching tubes Q1 and Q2. The so-called asymmetric and complementary refers to that the duty cycles of the two PWM pulses are generally not equal, and the sum of the two is equal to 1 under the condition of ignoring the dead time.
[0082] First, the working principle of the asymmetric half-bridge AC-DC single-stage converter is analyzed, and then the power relationship of the voltage division rectifier circuit and the multi-voltage output circuit is derived.
[0083] 2.1 Asymmetric half-bridge AC-DC single-stage converter
[0084] Sine AC power supply u s After the rectifier bridge (1), it is rectified into a sine half-wave pulsating DC voltage u a to the first end of the inductor La. The voltage u a The expression is:
[0085] (E-1)
[0086] In the formula, U s is the effective value of the AC power supply u s , and ω is the angular frequency of u s .
[0087] The voltage of the capacitor C1 is set to V a , the voltage of the capacitor C2 is V c , and the voltage between the node Vd and GND of the asymmetric half-bridge (2) is V d , then:
[0088] (E-2)
[0089] As shown in Figure 1 , if the second end of the inductor La is connected to the node Va, the voltage u a is added to the capacitor C1 after filtering by the inductor La, V a = u a . AsFigure 2 As shown, if the second end of the inductor La is connected to the node Vb, the voltage u a The voltage added to the capacitor C1 through the inductor La and the primary winding Np is the same as the balance relationship of volt-second value during the on-off conversion of the switch tubes Q1 and Q2 (see formula (E-5) below), and the same result is still obtained V a = u a .
[0090] Let the voltage of the capacitor Co (i.e. the DC output voltage) be V o , and the voltage of the capacitor Cb be V e Note: The set voltage refers to the average voltage excluding high-frequency ripple.
[0091] Let the voltage of the secondary winding Ns be V s , and the direction from S1 to S2 be positive; and the voltage of the primary winding Np be V p , and the direction from P1 to P2 be positive. Let the transformation ratio of the transformer (3) be n , and the leakage inductance of the transformer (3) be ignored, then:
[0092] (E-3)
[0093] 2.1.1 Electric quantity relationship when the second end of the capacitor Cb is connected to the negative terminal Vo-
[0094] In order to simplify the analysis, the on-resistance and the dead time of the on-off switching of the switch tubes Q1 and Q2 are ignored, and the on-voltage drop and the on-off switching time of the diodes D1 and D2 are ignored.
[0095] As shown in Figure 1 , when the switch tube Q2 is off and Q1 is on, the terminal P1 of the primary winding Np of the transformer (3) is connected to the node GND, and the voltage of the capacitor C1 u a is added to the primary winding Np, then V p = u a , the equivalent excitation current of the transformer (3) increases; and the voltage induced to the secondary winding Ns V s = n · u aAt this time, the diode D1 of the rectifier circuit (4) is off, and no current is output; the voltage of the secondary winding Ns in series with the capacitor Cb is applied to the inductor Lo, and the inductor Lo stores energy and the current increases.
[0096] When the switch tube Q1 is off and the Q2 is on, the terminal P1 of the primary winding Np of the transformer (3) is connected to the node Vd, and the voltage of the capacitor C2 V c is applied to the primary winding Np, then V p = V c The voltage induced to the secondary winding Ns V s = n · V c At this time, the diode D1 of the rectifier circuit (4) is on, and the inductor Lo flows through the diode D1 to the capacitor Co (i.e. the DC output end) to continue the current, and the inductor Lo releases energy and the current decreases. At the same time, the secondary winding Ns in series with the capacitor Cb also flows through the diode D1 to the capacitor Co to continue the current, and the secondary winding Ns is derived from the release of the equivalent excitation current. Note: the role of the capacitor C2 is to buffer the equivalent excitation current of the primary winding Np and clamp the flyback voltage.
[0097] When the diode D1 of the rectifier circuit (4) is on, the voltage of the capacitor Co (i.e. the output voltage) is equal to:
[0098] (E-4)
[0099] The on-duty ratio of the switch tube Q1 is set to D , and the on-duty ratio of the switch tube Q2 is (1- D ). According to the volt-second value balance principle of the switching conversion, the voltage relationship of the primary winding Np is obtained as:
[0100] (E-5)
[0101] The voltage applied to the inductor Lo of the rectifier circuit (4) satisfies the following relationship:
[0102] (E-6)
[0103] By combining equation (E-6), equation (E-5) and equation (E-4), we obtain:
[0104] (E-7)
[0105] From equation (E-7), the DC output voltage V o can be adjusted by adjusting the duty ratioD to adjust and stabilize; i.e. the duty cycle D of the average value of the output voltage, D the instantaneous variation of which realizes the power factor correction. The voltage V e is zero on average and can thus be eliminated.
[0106] The maximum operating voltage of the switching transistors Q1, Q2 is the maximum value of the voltage between the node Vd of the asymmetrical half-bridge (2) and GND V dM , from which, together with equation (E-2) and equation (E-7), it follows that
[0107] (E-8)
[0108] The reverse voltage of the diode D1 is designated by V R , V R = V o + n · u a The maximum value of which is V RM :
[0109] (E-9)
[0110] According to equation (E-8) and equation (E-9), the transformation ratio of the transformer (3) n can be chosen so that the maximum operating voltages of the switching transistors Q1, Q2 and the diode D1 in the converter are equalized.
[0111] Let the current through the inductance Lo be I L , the current through the diode D1 be I D (this is the output current I o ), the forward current through the secondary winding Ns of the transformer (3) be I S+ and the reverse current be I S- (outgoing from the terminal S2 is forward, incoming is reverse). The charge / discharge current of the capacitor Cb is equal to the forward / reverse current of the secondary winding Ns, respectively.
[0112] When the switching transistor Q2 is switched off and Q1 is switched on, the diode D1 is blocked and the current relationships are:
[0113] (E-10)
[0114] When the switch tube Q1 is off and Q2 is on, the diode D1 is on, and the current relationship is:
[0115] (E-11)
[0116] To keep the charge and discharge balance of the capacitor Cb, the following relationship should be met:
[0117] (E-12)
[0118] The formula (E-10), formula (E-11) and formula (E-12) are derived from the simultaneous equations:
[0119] (E-13)
[0120] The average value of the direct current output current is :
[0121] (E-14)
[0122] The charge and discharge currents of the capacitor Co are respectively set as I Co+ and I Co- When the rectified output end is connected to a constant direct current load, the ripple current (i.e. the charge and discharge current) of the capacitor Co is:
[0123] (E-15)
[0124] 2.1.2 The electric quantity relationship when the second end of the capacitor Cb is connected to the positive end Vo+
[0125] As shown in Figure 2 , when the switch tube Q2 is off and Q1 is on, the voltage added to the primary winding Np is V p = u a , the equivalent excitation current of the transformer (3) is increased; the voltage induced to the secondary winding Ns is V s = n · u a At this time, the diode D1 of the rectifier circuit (4) is cut off, the secondary winding Ns applies voltage to the inductor Lo in series with the capacitors Cb and Co, the inductor Lo stores energy and the current increases, at the same time, the capacitor Cb discharges.
[0126] When the switch tube Q1 is off and Q2 is on, the voltage added to the primary winding Np is V p = V cThe voltage induced in the secondary winding Nsis V s =- n · V c At this time, the diode Dl of the rectifier circuit (4) is turned on, and the inductor Lo is charged through the diode Dl to the capacitor Co (i.e. the output terminal), and the inductor Lo releases energy and the current decreases. At the same time, the secondary winding Ns is charged through the diode Dl to the capacitor Cb, and the equivalent excitation current of the transformer (3) decreases.
[0127] When the diode Dl of the rectifier circuit (4) is turned on, the voltage of the capacitor Cb is equal to:
[0128] (E-16)
[0129] According to the switching transformation volt-second balance principle, the voltage added to the inductor Lo satisfies the following relationship:
[0130] (E-17)
[0131] By combining equations (E-16), (E-17) and (E-5), we obtain:
[0132] (E-18)
[0133] From equation (E-18), it can be seen that the average voltages of capacitors Cb and Co are equal, so Cb is necessary. By combining (E-18) and equation (E-7), it is concluded that the voltage transfer functions of the two connection modes of the transformer (3) and the rectifier circuit (4) are the same.
[0134] It is concluded that (omitted), the maximum working voltage of the switch tubes Ql, Q2 and the diode Dl also meets equations (E-8) and (E-9). The positive / negative current of the secondary winding Ns and the current of the diode Dl I D Also meets equation (E-13).
[0135] Let the charge / discharge current of the capacitor Cb be I Cb+ and I Cb- The ripple current (i.e. charge / discharge current) of the capacitor Cb can be derived as:
[0136] (E-19)
[0137] 2.2 Voltage dividing rectifier circuit and multi-output rectifier circuit
[0138] Based on the working principle of the asymmetric half-bridge AC-DC single-stage converter, from equation (E-8) and equation (E-9), the maximum working voltage of the switch Q1, Q2 and diode D1 is determined by the input voltage u a , the output voltage V o and the transformer ratio n .
[0139] Because the switch Q1 and Q2 are active controllable semiconductor devices, and the diode D1 is a passive uncontrollable semiconductor device, the working voltage requirement of the switch Q1 and Q2 should be met first. When the output voltage is high, the transformer ratio V dM is selected to meet the requirement of the maximum working voltage of the switch Q1, Q2 n . After that, the maximum working voltage of the diode D1 may exceed its maximum reverse voltage range. At this time, the diodes need to be connected in series for voltage division. In order to balance the reverse voltage division of the series diodes, a voltage division rectifier circuit (5) is proposed.
[0140] When the inductors Lo1 and Lo2 are tightly coupled, Lo1 and Lo2 can be equivalent to a transformer, and the equivalent ratio n L of the equivalent transformer is equal to the ratio of their turns.
[0141] (E-20)
[0142] In the formula, m 1 , m 2 and L o1 , L o2 are the turns and inductance of the inductors Lo1, Lo2 respectively.
[0143] As Figure 7 and Figure 8 shown, when the switch Q1 is off and Q2 is on, the diodes D1, D2 of the voltage division rectifier circuit (5) are turned on, then the inductors Lo1, Lo2 charge the capacitors Co1, Co2 through the diodes D1, D2, and the ratio of the voltages V Co1 , V Co2 of the capacitors Co1 and Co2 is:
[0144] (E-21)
[0145] When the switch tube Q2 is off and Q1 is on, the diodes D1 and D2 of the voltage dividing rectifier circuit (5) are off, and the voltage of the secondary winding Ns in series with Cb is added to the inductors Lo1 and Lo2 V Lo1 、 V Lo2 The ratio of the voltage of the secondary winding Ns in series with Cb to the voltage of the inductor Lo2 is:
[0146] (E-22)
[0147] Therefore, the reverse voltage of the diodes D1 and D2 of the voltage dividing rectifier circuit (5) is V R1 、 V R2 The relationship between the reverse voltage of the diodes D1 and D2 of the voltage dividing rectifier circuit (5) and the voltage of the inductor Lo2 is:
[0148] (E-23)
[0149] As can be seen from the formula, the ratio of the number of turns of the inductors Lo1 and Lo2 n L determines the reverse voltage division ratio of the diodes D1 and D2, and can maintain dynamic balance.
[0150] In order to meet the demand of multi-voltage output of the circuit, a multi-output rectifier circuit (6) is proposed. The following refers to Figure 10 and Figure 11 to analyze the electrical quantity relationship and circuit characteristics.
[0151] The inductor Lo with a tap end can be equivalent to a autotransformer. Let the total number of turns of the inductor Lo be m , and the number of turns between the tap end and the second end be m 2. Let the voltage between the positive terminal Vo+ and the negative terminal Vo- of the multi-output rectifier circuit (6) be V o1 , and the voltage between the node Vo2 and the negative terminal Vo- be V o2 .
[0152] When the diodes D1 and D2 of the multi-output rectifier circuit (6) are on, the inductor Lo charges the capacitors Co1 and Co2 through the diodes D1 and D2, and the voltage V o1 and V o2 The ratio of the voltage of the secondary winding Ns in series with Cb to the voltage of the inductor Lo2 is:
[0153] (E-24)
[0154] Referring to the aforementioned principle analysis, it can be concluded that the maximum reverse voltage of the diodes D1 and D2 V RM1 and VRM2 :
[0155] (E-25)
[0156] From formula (E-25), the reverse voltage of diodes D1 and D2 in the voltage dividing rectifier circuit (5) is proportional to the output voltage V o1 and V o2 , and cannot share the total reverse voltage. But the advantage is that there is only one diode in the loop of output voltage V o1 and V o2 , and the efficiency is higher.
[0157] Another circuit characteristic of the voltage dividing rectifier circuit (5) is that the output voltage V o1 and V o2 can be simultaneously loaded and individually loaded. This is determined by the self-coupling characteristic of the inductor Lo tap.
[0158] The above only describes the preferred embodiments of the present application, and does not limit the patent range of the present application. Any equivalent topological transformation made by using the content of the present application specification and drawings, or direct or indirect application in other related technical fields under the innovative concept of the present application, is included in the patent protection range of the present application.
Claims
1. An asymmetric half-bridge AC-DC single-stage converter, comprising a rectifier bridge (1), an asymmetric half-bridge (2), a transformer (3), a rectifier circuit (4), an inductor La and a capacitor Cb; the rectifier bridge (1) is a four-terminal network, having a positive output terminal, a negative output terminal and two AC input terminals; characterized in that: the asymmetric half-bridge (2) comprises capacitors C1 and C2 and switching tubes Q1 and Q2; the first terminals of the capacitors C1 and C2 are connected to form a node Va, the second terminal of the capacitor C2 is connected to the drain of the switching tube Q2 to form a node Vd, the source of the switching tube Q2 is connected to the drain of the switching tube Q1 to form a node Vb, and the source of the switching tube Q1 is connected to the second terminal of the capacitor C1 to form a node GND; 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 is the same name terminal as the terminal P1, and the terminal S2 is the same name terminal as the terminal P2; the rectifier circuit (4) comprises a diode D1, an inductor Lo and a capacitor Co; the anode of the diode D1 is connected to the first terminal of the inductor Lo to form a node V1, the cathode of the diode D1 is connected to the positive electrode of the capacitor Co to form a positive terminal Vo+, and the second terminal of the inductor Lo is connected to the negative electrode of the capacitor Co to form a negative terminal Vo-; An asymmetric half-bridge AC-DC single-stage converter, the connection relationship of each part is: an AC power supply u s Two AC input terminals of a two-terminal connection rectifier bridge (1), a negative output terminal of the rectifier bridge (1) is connected to a node GND, a positive output terminal of the rectifier bridge (1) is connected to a first terminal of an inductor La, a second terminal 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 P2 and P1 of a primary winding Np of a transformer (3); a node V1 of a rectifier circuit (4) is connected to a terminal S1 of a secondary winding Ns, a terminal S2 of the secondary winding Ns is connected to a first terminal of a capacitor Cb, a second terminal of the capacitor Cb is connected to a positive terminal Vo+ or a negative terminal Vo-; or the capacitor Cb is connected in series between the node V1 of the rectifier circuit (4) and the terminal S1 of the secondary winding Ns, and the terminal S2 of the secondary winding Ns is connected to the positive terminal Vo+ or the negative terminal Vo-. when the second terminal of the inductor La is connected to the node Vb of the asymmetric half-bridge (2), the second terminal of the capacitor C1 of the asymmetric half-bridge (2) is connected to the node GND or is changed to be connected to the positive output terminal of the rectifier bridge (1); when the second terminal of the capacitor Cb or the terminal S2 of the secondary winding Ns is connected to the negative terminal Vo-, the capacitor Cb is retained or removed; when the second terminal of the capacitor Cb or the terminal S2 of the secondary winding Ns is connected to the positive terminal Vo+, the capacitor Co is retained or removed; when the capacitor Cb is removed, and the second terminal of the inductor La is connected to the node Vb of the asymmetric half-bridge (2), the inductor Lo is retained or removed; or a voltage dividing rectifier circuit (5) is used to replace the rectifier circuit (4) to reduce the reverse voltage of the diode; or a multi-output rectifier circuit (6) is used to replace the rectifier circuit (4) to meet the demand of multi-voltage output.
2. The asymmetrical half bridge AC-DC single stage converter of claim 1, wherein: The rectifier circuit (4) and the transformer (3) adopt a reverse dual connection relationship: the anode and the cathode of the diode D1 in the rectifier circuit (4) are exchanged in the connection position, the positive electrode and the negative electrode of the capacitor Co are exchanged in the connection position, and the positive terminal Vo+ and the negative terminal Vo- are exchanged in the position; at the same time, the terminal S1 and the terminal S2 of the secondary winding Ns of the transformer (3) are exchanged in the connection position.
3. The asymmetrical half bridge AC-DC single stage converter of claim 1, wherein: The voltage dividing rectifier circuit (5) is used to replace the rectifier circuit (4); the voltage dividing rectifier circuit (5) comprises diodes D1 and D2, capacitors Co1 and Co2, and inductors Lo1 and Lo2; the inductors Lo1 and Lo2 are coupled. The anode of diode D1 is connected with the first end of inductor Lo1 as node V1, and the cathode of diode D2 is connected with the second end of inductor Lo2 as node V2; the negative pole of capacitor Co1 is connected with the positive pole of capacitor Co2 as node Vo2, the positive pole of capacitor Co1 is the positive terminal Vo+, and the negative pole of capacitor Co2 is the negative terminal Vo-; the second end of inductor Lo1 and the first end of inductor Lo2 are connected with node Vo2, the cathode of diode D1 is connected with the positive terminal Vo+, and the anode of diode D2 is connected with the negative terminal Vo-; or, the cathode of diode D1 and the anode of diode D2 are connected with node Vo2, the first end of inductor Lo2 is connected with the positive terminal Vo+, and the second end of inductor Lo1 is connected with the negative terminal Vo-. The connection relationship between the voltage division rectifier circuit (5) and the transformer (3) is as follows: the terminal S1 of the secondary winding Ns of the transformer (3) is connected with node 1 of the voltage division rectifier circuit (5), and the capacitor Cb is connected in series between node 2 and the terminal S2; or, the terminal S2 of the secondary winding Ns is connected with node 2 of the voltage division rectifier circuit (5), and the capacitor Cb is connected in series between node 1 and the terminal S1; if the second end of inductor Lo1 and the first end of inductor Lo2 are connected with node Vo2, the capacitor Cb is kept or removed.
4. The asymmetrical half bridge AC-DC single stage converter of claim 1, wherein: The rectifier circuit (4) is replaced by a multi-output rectifier circuit (6); The multi-output rectifier circuit (6) comprises diodes D1 and D2, capacitors Co1 and Co2, and an inductor Lo; the inductor Lo has a first end, a second end and a tap end; the first end of the inductor Lo is connected with the anode of diode D1 as node V1, the tap end of the inductor Lo is connected with the anode of diode D2, and the second end of the inductor Lo is connected with the negative pole of capacitor Co2 as the negative terminal Vo-; the cathode of diode D2 is connected with the positive pole of capacitor Co2 as node Vo2, the cathode of diode D1 is connected with the positive pole of capacitor Co1 as the positive terminal Vo+, and the negative pole of capacitor Co1 is connected with node Vo2 or the negative terminal Vo-; The connection relationship between the multi-output rectifier circuit (6) and the transformer (3) is as follows: the terminal S1 of the secondary winding Ns is connected with node V1 or the tap end of the inductor Lo of the multi-output rectifier circuit (6), the terminal S2 of the secondary winding Ns is connected with the first end of the capacitor Cb, and the second end of the capacitor Cb is connected with the positive terminal Vo+ or the negative terminal Vo- of the multi-output rectifier circuit (6); or, the terminal S1 of the secondary winding Ns is connected with the first end of the capacitor Cb, the second end of the capacitor Cb is connected with node V1 or the tap end of the inductor Lo, and the terminal S2 of the secondary winding Ns is connected with the positive terminal Vo+ or the negative terminal Vo-. When the second end of the capacitor Cb or the terminal S2 of the secondary winding Ns is connected with the negative terminal Vo- of the multi-output rectifier circuit (6), the capacitor Cb is kept or removed; Or, the multi-output rectifier circuit (6) and the transformer (3) adopt a reverse dual connection relationship: the anode and the cathode of diodes D1 and D2 in the multi-output rectifier circuit (6) are exchanged in the connection position, the positive pole and the negative pole of capacitors Co1 and Co2 are exchanged in the connection position, and the positive terminal Vo+ and the negative terminal Vo- are exchanged in the position; at the same time, the terminal S1 and the terminal S2 of the secondary winding Ns of the transformer (3) are exchanged in the connection position.
5. The asymmetrical half bridge AC-DC single stage converter according to any one of claims 1 and 2, characterized in that: The diode D1 of the rectifier circuit (4) is replaced by a switch tube Q3, and the replacement rule is that the connection positions of 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) adopts a diode or a thyristor or a switch tube, and the switch tube adopts but is not limited to a MOSFET or an IGBT.
6. The asymmetrical half bridge AC-DC single stage converter of any of claims 1 to 4, characterized in that: When the negative terminal Vo- of the rectifier circuit (4) is connected to the second terminal of the capacitor Cb or the terminal S2 of the secondary winding Ns, or the rectifier circuit (4) is replaced by the voltage division rectifier circuit (5), or the rectifier circuit (4) is replaced by the multi-output rectifier circuit (6); the switch tube Q2 and the capacitor C2 of the asymmetric half-bridge (2) are removed.
7. The asymmetrical half bridge AC-DC single stage converter of any of claims 1 to 4, characterized in that: 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), thereby becoming a DC-DC converter.