A full cycle conduction full wave rectifier circuit for low voltage high current output

Abstract

The present application belongs to the technical field of power electronic low-voltage high-current rectification, and relates to a full-cycle conduction full-wave rectification circuit for low-voltage high-current output, comprising a first secondary winding, a second secondary winding, a first synchronous rectifier, a second synchronous rectifier, a first output capacitor, an auxiliary current-sharing capacitor and a load; the first output capacitor is used for maintaining the output voltage of the load; the auxiliary current-sharing capacitor is used for providing an AC shunt channel between the output capacitor branches; the auxiliary current-sharing capacitor is connected between the like terminals of the first secondary winding and the second secondary winding, so that the auxiliary current-sharing capacitor and the first output capacitor form a parallel shunt structure in the AC channel, so that the first secondary winding and the second secondary winding participate in conduction in the positive half cycle and the negative half cycle of the switching cycle, and full-cycle conduction full-wave rectification is realized; the present application solves the problems of high loss and high temperature rise of the secondary winding in the full-wave rectification scheme, and has high practical application value.

Description

Technical Field

[0001] This invention belongs to the field of power electronics low-voltage high-current rectification technology, specifically relating to a full-cycle conduction full-wave rectifier circuit for low-voltage high-current output. Background Technology

[0002] With the upgrading of data center computing power, the large-scale application of artificial intelligence accelerator cards, and the high-power-density iteration of communication power supplies, downstream power supply equipment has placed stringent demands on isolated DC-DC converters, requiring low voltage, high current, high efficiency, low heat loss, and small size. In the circuit architecture of isolated DC-DC converters, the transformer secondary rectification stage is the core module for converting AC voltage to low-voltage DC voltage. Its circuit topology and current distribution characteristics directly determine the overall operating efficiency of the converter, the winding temperature rise performance, and the difficulty of overall thermal design. It is also a key bottleneck restricting the improvement of power density of low-voltage, high-current power supplies.

[0003] Currently, the mainstream rectification schemes for the secondary side of isolated DC-DC converters in the industry mainly adopt the traditional center-tapped full-wave rectifier topology, or a full-wave rectifier topology built with two independent secondary windings and synchronous rectifier diodes. A conventional full-wave rectifier circuit mainly consists of a first secondary winding W1, a second secondary winding W2, and a first synchronous rectifier diode SR. a Second synchronous rectifier tube SR b It consists of an output capacitor Co, and relies on the two sets of windings on the secondary side of the transformer to work in turn to complete AC rectification.

[0004] The existing traditional full-wave rectifier topology employs a half-cycle time-sharing operating logic: the first secondary winding W1 of the transformer operates only during the positive half-cycle of the AC voltage, while the second secondary winding W2 operates only during the negative half-cycle. The two sets of secondary windings alternate operation within a complete switching cycle. In this mode, a single secondary winding carries the output current for only about 50% of the time in a complete switching cycle, resulting in extremely low overall winding time utilization. Under low-voltage, high-current, and high-power output conditions, this inherent topology defect leads to multiple circuit losses and heat dissipation problems, the specific drawbacks of which are as follows: First, the effective value of the secondary winding current is too high, resulting in a significant increase in DC copper losses. Due to the single-winding half-cycle conduction mechanism, to meet the constant average output current demand from the downstream, the instantaneous output current during the half-cycle of winding conduction will increase significantly, directly leading to a simultaneous increase in the mean square current and the effective value of the current in the secondary winding. Winding copper losses are positively correlated with the square of the effective current value; therefore, the copper losses in the transformer's secondary winding will rise sharply. Especially since power supply equipment generally uses PCB planar windings and multi-layer laminated conductor structures, excessive winding losses will directly cause the secondary winding temperature to exceed the standard, worsening the overall heat dissipation conditions.

[0005] Secondly, high-frequency AC losses are exacerbated, and the topology itself suffers from an inherent current ripple problem that cannot be eliminated. The half-cycle pulse current output characteristic of traditional topologies generates a large local magnetomotive force peak within the PCB layered winding structure, thereby inducing significant current congestion and high-frequency proximity effects. These two types of high-frequency parasitic effects further amplify the high-frequency AC copper losses in the windings. Even with the use of high-performance synchronous rectifier power devices with extremely low on-resistance, the conduction losses of the synchronous rectifier tubes themselves can be effectively suppressed, but the inherent losses of the secondary windings still cannot be optimized. Winding losses become the core bottleneck limiting further improvements in the overall efficiency of low-voltage, high-current isolation converters.

[0006] Third, conventional loss optimization schemes have significant side effects, failing to balance low cost and high power density. To address the issues of high winding losses and temperature rise, conventional industry optimization methods include increasing the number of parallel branches in the secondary winding and thickening the copper foil on the PCB winding. However, these optimization methods directly increase the number of PCB layers, overall material costs, and the overall size of the power supply. Furthermore, the multi-layer PCB stacked structure further worsens internal heat dissipation conditions, increasing the difficulty of overall thermal design and contradicting the current trend towards miniaturization, high power density, and low cost in power supply equipment. In addition, some solutions optimize the winding current waveform by adding complex sampling circuits and closed-loop control strategies, but this significantly increases the computational load on the control chip, increases the complexity of the drive circuit, and raises the overall failure rate, thereby reducing power supply reliability.

[0007] In summary, existing traditional full-wave rectifier topologies suffer from numerous technical drawbacks, including low winding utilization, high winding losses, excessive temperature rise, and the need for conventional optimization schemes to sacrifice size and cost, as well as high complexity in control optimization schemes. The industry urgently needs a new type of full-wave rectifier circuit that can effectively distribute secondary winding current, reduce winding current stress, and reduce AC / DC copper losses without requiring a large number of additional main power devices or the introduction of complex control algorithms, while being suitable for low-voltage, high-current operating conditions. Summary of the Invention

[0008] This invention aims to...

[0009] This invention provides the following technical solution: a full-cycle conduction full-wave rectifier circuit for low-voltage, high-current output, comprising: a first secondary winding W1, a second secondary winding W2, and a first synchronous rectifier diode SR. a Second synchronous rectifier tube SR b First output capacitor C oa Auxiliary current sharing capacitor C ob and load R o First output capacitor C oa Used to maintain the load output voltage; auxiliary current sharing capacitor C ob Used to provide an AC shunt path between output capacitor branches.

[0010] The connection method of the full-cycle conduction full-wave rectifier circuit is as follows: the first output capacitor C oa With load R o Parallel connection. The first secondary winding W1 is connected to the first synchronous rectifier tube SR. a The first rectifier branch is formed by connecting the second secondary winding W2 and the second synchronous rectifier tube SR. b The first and second rectifier branches are connected in series to form the second rectifier branch. The first and second rectifier branches are then connected in parallel to the first output capacitor C. oa Both ends. Auxiliary current sharing capacitor C ob Connect the auxiliary current-sharing capacitor C between the corresponding terminals of the first secondary winding W1 and the second secondary winding W2. ob With the first output capacitor C oa A parallel shunt structure is formed in the AC path so that the first secondary winding W1 and the second secondary winding W2 participate in conduction in both the positive and negative half-cycles of the switching cycle, thereby achieving full-cycle conduction and full-wave rectification.

[0011] Preferably, the circuit includes a positive half-cycle operating mode and a negative half-cycle operating mode within one switching cycle. In the positive half-cycle operating mode, the first synchronous rectifier diode SR... a Turn on, second synchronous rectifier tube SR b When switched off, the rectifier branch containing the first secondary winding W1 directs power to the load R. o It transmits DC output current; simultaneously, the auxiliary current-sharing capacitor C ob With the first output capacitor C oa This forms an AC parallel shunt channel, allowing a portion of the AC current in the output capacitor branch to pass through the auxiliary current-sharing capacitor C. ob The current flows along the path of the second secondary winding W2. Thus, the first secondary winding W1 carries the superposition of the DC output current and half of the AC component, while the second secondary winding W2 carries the other half of the AC component.

[0012] Under the negative half-cycle operating mode, the second synchronous rectifier SR b Power on, first synchronous rectifier tube SR a When switched off, the rectifier branch containing the second secondary winding W2 directs power to the load R. o It transmits DC output current; simultaneously, the auxiliary current-sharing capacitor C ob With the first output capacitor C oa This continues to form an AC parallel shunt channel, allowing a portion of the AC current in the output capacitor branch to pass through the auxiliary current-sharing capacitor C. ob The current flows along the path of the first secondary winding W1. Thus, the second secondary winding W2 carries the superposition of the DC output current and half of the AC component, while the first secondary winding W1 carries the other half of the AC component.

[0013] Preferably, under the operating condition that the resonant current or the secondary rectified current can be approximated as the absolute value of a sinusoidal current, the output DC load current is defined as I. dc The switching period is T s The angular frequency is ω=2π / T s The secondary rectified current is I AC (t), the AC current in the output capacitor branch is I ac (t), then we have:

[0014]

[0015] When the first output capacitor C oa With auxiliary current sharing capacitor C ob When the equivalent AC impedances of the AC branches are approximately equal, the output AC component is approximately evenly distributed between the two branches. At this time, during the positive half-cycle, the first secondary winding W1 carries I... dc +1 / 2I ac (t), the second secondary winding W2 carries 1 / 2I ac (t); During the negative half-cycle, the first secondary winding W1 carries -1 / 2I ac (t), the second secondary winding W2 carries -(I dc +1 / 2I ac (t)).

[0016] Preferably, after substituting the above AC component expression into the winding segmented current relationship, the winding currents of the first secondary winding W1 and the second secondary winding W2 during a complete switching cycle are respectively:

[0017]

[0018] Therefore, the effective value of the current in a single secondary winding satisfies:

[0019]

[0020] Compared to the half-cycle conduction full-wave rectifier circuit, the average squared current of a single secondary winding is approximately 0.617I. dc 2 The present invention can reduce the average squared current of a single secondary winding.

[0021] Preferably, the auxiliary current sharing capacitor C ob The first secondary winding W1 and the second secondary winding W2 are connected to the load R. o A parallel electrical circuit is formed, and the current flows through the auxiliary current-sharing capacitor C. obThe current generates magnetomotive forces in opposite directions in the first secondary winding W1 and the second secondary winding W2. Their equivalent relationship can be expressed as:

[0022]

[0023] This allows for AC current splitting without introducing additional series inductance.

[0024] Preferably, the first synchronous rectifier tube SR a Second synchronous rectifier tube SR b It is a power MOSFET or a gallium nitride controlled rectifier device.

[0025] Preferably, the first output capacitor C oa Auxiliary current sharing capacitor C ob Each is composed of one or more low equivalent series inductors and capacitors connected in parallel.

[0026] Preferably, the auxiliary current sharing capacitor C ob The terminals of the first secondary winding W1 and the second secondary winding W2 are located close to each other to reduce parasitic inductance.

[0027] The present invention provides a full-cycle conduction full-wave rectifier circuit for low-voltage high-current output, which is applied to the secondary side rectification of the transformer in LLC resonant converters, series resonant converters, or isolated DC / DC converters.

[0028] The beneficial effects of this invention are: 1. This invention can reduce the effective value of winding current, decrease DC copper losses in the windings, and improve the overall conversion efficiency. This invention adds an auxiliary current-sharing capacitor and optimizes the topology connection, enabling both sets of secondary windings to conduct simultaneously throughout the entire cycle, sharing the load current. Simultaneously, the auxiliary current-sharing capacitor provides an additional shunt path for the AC component of the output current, further distributing the winding current load. Current theory analysis verifies that this scheme can reduce the average square value of the current in a single secondary winding from 0.617I in the traditional topology. dc 2 Reduced to 0.558I dc 2 The reduction reached 9.5%. The DC copper loss of the winding is positively correlated with the square of the current. This topology can effectively reduce the DC copper loss of the secondary winding from a mechanism perspective, adapt to low-voltage and high-current operating conditions, and effectively improve the overall working efficiency of the converter.

[0029] 2. This invention optimizes the magnetomotive force distribution of the windings, suppresses high-frequency parasitic effects, and reduces AC copper losses. Through a dual-winding full-cycle current-sharing operating mode, the two windings continuously share the output current, effectively smoothing out current pulse spikes caused by half-cycle operation, significantly reducing the peak value of local magnetomotive force within the secondary conductor, balancing the magnetic field distribution of each layer of conductors in the windings, and making the current distribution within the windings more uniform. This design effectively suppresses current congestion and proximity effects, significantly reduces high-frequency AC copper losses in the windings, and solves the industry problem that high-frequency losses in traditional topologies cannot be optimized through device selection.

[0030] 3. This invention reduces the temperature rise of the secondary winding, optimizes the overall thermal design, and improves the reliability of the power supply. Simultaneously, it reduces both DC and high-frequency AC copper losses in the winding, reducing the heat generated by the winding from both major loss sources. This effectively reduces the steady-state temperature rise of the transformer's secondary winding and alleviates the overall heat dissipation pressure. It meets the heat dissipation requirements of high-power-density power supplies without requiring additional heat dissipation devices or increasing the size of the heat dissipation structure, ensuring long-term stable operation of the converter.

[0031] 4. This invention features minimal topology changes, simple control, and a balance between cost and power density, offering strong engineering adaptability. Unlike existing passive optimization schemes that reduce losses by increasing the number of parallel windings, thickening copper foil, or increasing PCB layers, this invention only adds an auxiliary current-sharing capacitor to the same terminals of the two secondary windings, optimizing only the wiring positions of the original power branches without requiring additional main power switching devices, resulting in minimal increase in hardware costs. Simultaneously, the circuit retains the original synchronous rectification drive logic, eliminating the need for complex current sampling circuits, closed-loop current-sharing control algorithms, and additional drive logic. The control strategy remains unchanged, and the control chip requires no upgrade. Furthermore, the loss optimization effect of this invention is an inherent mechanistic effect resulting from topology reconstruction, independent of specific prototype parameters and special transformer winding structures. It is compatible with mainstream transformer structures such as conventional PCB planar windings and wound-rotor transformers, exhibiting strong versatility and direct compatibility with the hardware architecture of existing low-voltage high-current isolation converters, making mass production and deployment easier.

[0032] 5. This invention retains all the advantages of the original full-wave rectifier circuit without any additional side effects. While achieving full-cycle current sharing and loss reduction in dual windings, this invention fully retains all the original advantages of the traditional full-wave rectifier circuit, such as low output voltage ripple, simple circuit structure, low device stress, and compatibility with the secondary rectification scenario of isolation transformers. It does not introduce negative problems such as increased output ripple, increased device voltage and current stress, or decreased circuit stability. While improving winding current stress and losses, it ensures that the basic working performance of the rectifier circuit is not affected. Attached Figure Description

[0033] Figure 1This is a topology diagram of a full-cycle conduction full-wave rectifier circuit for low-voltage high-current output according to the present invention. Figure 2 This is a diagram illustrating the evolution of the full-cycle conduction full-wave rectification topology of the present invention. Figure 3 This is a diagram showing the actual parallel connection between the first output capacitor, the auxiliary current-sharing capacitor, and the load according to the present invention. Figure 4 The diagrams show the AC / DC current distribution under the positive and negative half-cycles of the present invention; wherein, (a) is the AC / DC current distribution under the positive half-cycle, and (b) is the AC / DC current distribution under the negative half-cycle. Figure 5 The diagram shows the node voltage distribution under the positive and negative half-cycles of the present invention; wherein, (a) is the node voltage distribution under the positive half-cycle, and (b) is the node voltage distribution under the negative half-cycle. Figure 6 This is a comparison diagram of the winding current waveform of the present invention and the winding current waveform of a conventional full-wave rectifier.

[0034] In the diagram, W1 is the first secondary winding, W2 is the second secondary winding, and SR a As the first synchronous rectifier tube, SR b C is the second synchronous rectifier tube. oa C is the first output capacitor. ob As an auxiliary current-sharing capacitor, R o For load, I dc To output DC load current, I ac This refers to the AC current component of the output capacitor branch. Detailed Implementation

[0035] The related technologies of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] like Figures 1-6 As shown, this embodiment presents a full-cycle conduction full-wave rectifier circuit. The circuit includes a first secondary winding W1, a second secondary winding W2, and a first synchronous rectifier diode SR. a Second synchronous rectifier tube SR b First output capacitor C oa Auxiliary current sharing capacitor C ob and load R o First output capacitor C oa Connected to the DC output terminal to maintain the load output voltage; auxiliary current sharing capacitor C obConnected between the same-named terminals of W1 and W2, it is used to provide an AC shunt path between the output capacitor branches.

[0037] This circuit can be derived from a traditional full-wave rectifier circuit. The first step is to maintain the winding polarity of the second secondary winding W2 and the second synchronous rectifier diode SR... b Under the condition that the conduction direction and the output connection remain unchanged, SR b The positional relationship between the branch containing W1 and the branch containing W2 is adjusted to release the corresponding terminal node of W2. The second step is to connect an auxiliary current-sharing capacitor C between the corresponding terminals of W1 and W2. ob This forms C. oa C ob With load R o Parallel relationship in the sense of communication.

[0038] In the above connection relationship, C oa It still serves as the output filter, C ob This provides an additional path for the AC component in the output current. Because C ob Connected between the same-name terminals of the two sets of secondary windings, flowing through C ob The current flows in from the same terminal of W1 and out from the same terminal of W2. When the current passes through the two connecting paths formed by W1 and W2, it generates magnetic flux components in opposite directions in the core or winding window. Therefore, it mainly manifests as current sharing and connecting conductors, without introducing unwanted series inductance.

[0039] To explain the current distribution mechanism of this invention, one switching cycle can be divided into two basic operating modes: the positive half-cycle operating mode and the negative half-cycle operating mode. Let the output DC load current be I... dc The secondary rectified current is I AC (t), The AC current component in the output capacitor branch is I ac (t) will be explained. Under the operating condition that the resonant current or the secondary rectified current can be approximated as the absolute value of the sinusoidal current, let ω = 2π / T. s And let the average value of the secondary rectified current be equal to I. dc Then we have:

[0040]

[0041] In traditional full-wave rectification, W1 and W2 are only turned on for half a cycle each; in the circuit of this invention, C oa With C ob A parallel AC path is formed. When the equivalent AC impedances of the two AC branches are close, the AC components can be approximately equally distributed between the two branches, so that W1 and W2 participate in conduction in both the positive and negative half-cycles.

[0042] The first operating mode is the positive half-cycle operating mode, corresponding to Figure 4 (a) and Figure 5 (a). In this mode, the polarity of the transformer secondary voltage causes the first synchronous rectifier diode SR to... a The second synchronous rectifier tube SR is in the on state. b In the off state. First secondary winding W1, first synchronous rectifier tube SR a First output capacitor C oa and load R o This forms the main rectified output path, with W1 transmitting DC output current to the output terminal. Simultaneously, the auxiliary current-sharing capacitor C... ob With the first output capacitor C oa This forms an AC parallel shunt structure, where a portion of the AC current in the output capacitor branch passes through C. ob The flow along the path of the second secondary winding W2 causes W2 to also participate in conduction during the positive half-cycle.

[0043] Therefore, in the positive half-period t∈[0,T] s Within [ / 2], the first secondary winding W1 bears the superimposed current of the DC output current and half of the AC component, and the second secondary winding W2 bears the other half of the AC component. Its winding current is:

[0044] In this mode, C ob The branch current forms a parallel AC loop through W1 and W2, and generates magnetic flux components in opposite directions in the two sets of secondary windings. Therefore, this AC shunt loop mainly changes the winding current distribution, without introducing additional series inductance into the main power circuit of the load.

[0045] The second operating mode is the negative half-cycle operating mode, corresponding to Figure 4 (b) and Figure 5 (b) In this mode, the polarity of the transformer secondary voltage is reversed, causing the second synchronous rectifier diode SR to... b In the on state, the first synchronous rectifier tube SR a In the off state. Second secondary winding W2, second synchronous rectifier tube SR b First output capacitor C oa and load R o This forms the main rectified output path, with W2 transferring DC output current to the output terminal. Simultaneously, the auxiliary current-sharing capacitor C... ob Continue with the first output capacitor C oa This forms an AC parallel shunt structure, where a portion of the AC current in the output capacitor branch passes through C. ob The flow along the path of the first secondary winding W1 causes W1 to also participate in conduction during the negative half-cycle.

[0046] Therefore, in the negative half-period t∈[T] s / 2,T s Within the [unclear context], the second secondary winding W2 bears the superimposed current of the DC output current and half of the AC component, while the first secondary winding W1 bears the other half of the AC component. Its winding current is:

[0047] Therefore, the two secondary windings are no longer turned on by half-cycle pulses, but are turned on continuously throughout the complete switching cycle. Figure 4 This is only used to illustrate the distribution of AC and DC current components and does not limit the actual positional relationship of devices or windings.

[0048] Will I ac Substituting (t) into the above piecewise expression, and utilizing the sign characteristics of sin(ωt)>0 in the positive half-cycle and sin(ωt)<0 in the negative half-cycle, we can obtain the expression for the continuous winding current throughout the entire switching cycle:

[0049]

[0050] By taking the root mean square of the current in a continuous winding, the effective value of the current in a single secondary winding can be obtained as follows:

[0051] Therefore, the average squared current of a single secondary winding is:

[0052] In a traditional full-wave rectifier circuit with half-cycle conduction, the effective value of the current in a single secondary winding is approximately π / 4 I. dc The corresponding average squared current is approximately 0.617I. dc 2 Therefore, the present invention can reduce the average squared current of a single secondary winding; this reduction is directly significant for winding copper losses, which are proportional to the squared current.

[0053] In the specific arrangement, W1, W2, and SR can be used. a SR b C oa and C ob Set on the same PCB or adjacent conductive layers, and preferentially shorten the corresponding terminals of W1 and W2 to C. ob The loop path. The synchronous rectifier can be a low on-resistance MOSFET or other controllable rectifier devices suitable for this voltage and current level; C oa and C obIt can be composed of one or more parallel capacitors to meet output ripple, AC impedance, temperature rise and layout requirements.

[0054] The full-cycle conduction full-wave rectifier circuit of this invention can be replaced in several equivalent ways without changing the core connection relationship. Auxiliary current sharing capacitor C ob A single capacitor can be used, or multiple ceramic capacitors, film capacitors, or other low equivalent series inductance capacitors connected in parallel can be used; the capacitance and number can be determined according to the operating frequency, output ripple, current sharing ratio, and temperature rise requirements. First output capacitor C oa With auxiliary current sharing capacitor C ob The actual position of C can be adjusted according to the PCB layout, but it is preferred to make C ob Place it close to the terminals of W1 and W2 with the same name to reduce parasitic inductance and improve AC shunt performance. C oa It can be placed near the output terminal, or it can be distributed by multiple sets of capacitors to reduce the output circuit impedance.

[0055] Synchronous rectifier tube SR a and SR b Silicon MOSFETs, gallium nitride devices, or other controllable rectifier devices can be used; in some low-cost or low-power applications, diode rectification can also be used to achieve the same winding and capacitor connection logic. W1 and W2 can be PCB planar windings, copper busbar windings, lead windings, or other equivalent secondary conductors, as long as their corresponding terminal relationships and C... ob The connection relationship must satisfy the solution of this invention.

[0056] As an alternative, the first secondary winding W1 and the first synchronous rectifier tube SR can be interchanged simultaneously. a The positions are then interchanged, and the second secondary winding W2 and the second synchronous rectifier tube SR are simultaneously swapped. b The positions. After the interchange, as long as the same-name terminal relationship of the two sets of secondary windings, the conduction direction of the synchronous rectifier tube, the polarity of the output terminal, and C are maintained... oa and C ob With the corresponding connection relationships unchanged, the circuit can still form an equivalent full-cycle conduction full-wave rectification working mode.

[0057] Furthermore, the circuit of this invention can be applied to LLC resonant converters, series resonant converters, other isolated DC / DC converters, or full-wave rectification scenarios with two sets of equivalent secondary windings. The above substitutions do not change the core of this invention: by connecting an auxiliary current-sharing capacitor between the corresponding terminals of the two sets of secondary windings, the two sets of secondary windings are simultaneously conducting and sharing the AC current throughout the complete cycle.

[0058] In summary, this invention reconstructs the current path of the secondary-side rectification topology by adding an auxiliary current-sharing capacitor between the corresponding terminals of the two sets of secondary windings in a traditional full-wave rectifier circuit. This allows both the first and second secondary windings to participate in conduction during both the positive and negative half-cycles of the switching cycle, achieving full-cycle current sharing and shunting. This effectively reduces the effective value of the current in the secondary windings and the copper losses, while also optimizing the winding magnetomotive force distribution, suppressing high-frequency parasitic effects, and reducing winding temperature rise. It balances cost, power density, and operational reliability, requires minimal topology modification, has simple control logic, strong engineering adaptability, retains all the advantages of traditional full-wave rectifier circuits, and has no additional negative side effects. It is highly suitable for secondary-side rectification scenarios of low-voltage, high-current output isolation converters, solving the industry pain points of high secondary winding losses and large temperature rise in traditional full-wave rectifier solutions, and has high practical application value.

[0059] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A full-cycle conduction full-wave rectifier circuit for low-voltage, high-current output, characterized in that, include: First secondary winding W1, second secondary winding W2, first synchronous rectifier diode SR a Second synchronous rectifier tube SR b First output capacitor C oa Auxiliary current sharing capacitor C ob and load R o The first output capacitor C oa The auxiliary current-sharing capacitor C is used to maintain the load output voltage; ob Used to provide an AC shunt path between output capacitor branches; The connection method of the full-cycle conduction full-wave rectifier circuit is as follows: First output capacitor C oa With load R o Parallel connection; The first secondary winding W1 and the first synchronous rectifier SR a The first rectifier branch is formed by connecting them in series; the second secondary winding W2 and the second synchronous rectifier tube SR b The two rectifier branches are connected in series to form the second rectifier branch. The first rectifier branch and the second rectifier branch are connected in parallel and then connected to the first output capacitor C. oa Both ends; The auxiliary current sharing capacitor C ob Connect the auxiliary current-sharing capacitor C between the corresponding terminals of the first secondary winding W1 and the second secondary winding W2. ob With the first output capacitor C oa A parallel shunt structure is formed in the AC path so that the first secondary winding W1 and the second secondary winding W2 participate in conduction in both the positive and negative half-cycles of the switching cycle, thereby achieving full-cycle conduction and full-wave rectification.

2. The full-cycle conduction full-wave rectifier circuit for low-voltage high-current output according to claim 1, characterized in that: During the positive half-cycle, the first synchronous rectifier diode SR a Turn on, second synchronous rectifier tube SR b When turned off, the first secondary winding W1 carries the superposition of the DC output current and half of the AC component, while the second secondary winding W2 carries the other half of the AC component. During the negative half-cycle, the second synchronous rectifier diode SR b Power on, first synchronous rectifier tube SR a When the circuit is turned off, the second secondary winding W2 carries the superimposed current of the DC output current and half of the AC component, while the first secondary winding W1 carries the other half of the AC component. Under the operating condition that the resonant current or the secondary rectified current can be approximated as the absolute value of a sinusoidal current, let the output DC load current be I. dc The switching period is T s The angular frequency is ω=2π / T s The secondary rectified current is I AC (t), the AC current in the output capacitor branch is I ac (t), then we have: When the first output capacitor C oa With auxiliary current sharing capacitor C ob When the equivalent AC impedances of the AC branches are equal or approximately equal, the AC current I of the output capacitor branch is... ac (t) is approximately evenly distributed in the two AC branches; During the positive half-period t∈[0,T] s Within [ / 2], the currents of the first secondary winding W1 and the second secondary winding W2 respectively satisfy: During the negative half-period, t∈[T] s / 2,T s Within [the specified context], the currents in the first secondary winding W1 and the second secondary winding W2 respectively satisfy: Will I ac (t) Substituting the piecewise current expressions for the first secondary winding W1 and the second secondary winding W2, the continuous current expressions for the first secondary winding W1 and the second secondary winding W2 during the entire switching cycle are as follows: Based on the aforementioned continuous current expression, the effective value of the current in a single secondary winding satisfies: And the average squared current of a single secondary winding satisfies: The effective value I of the single secondary winding current in a half-cycle alternating conduction full-wave rectifier circuit W,trad,rms =π / 4 I dc and its average squared current I W,trad,rms 2 ≈0.617I dc 2 In comparison, the full-cycle conduction full-wave rectifier circuit reduces the average squared current of a single secondary winding.

3. The full-cycle conduction full-wave rectifier circuit for low-voltage high-current output according to claim 1, characterized in that, The auxiliary current sharing capacitor C ob The first secondary winding W1 and the second secondary winding W2 are connected to the load R. o A parallel circuit is formed, and the current flows through the first secondary winding W1 and the second secondary winding W2 to generate magnetic flux components in opposite directions, without introducing additional series inductance. Among them, the current flows through the auxiliary current sharing capacitor C ob The current is denoted as i ob When the first secondary winding W1 and the second secondary winding W2 have approximately the same number of turns or equivalent magnetic flux path and opposite directions in the parallel circuit, their equivalent magnetomotive force satisfies: Or the equivalent magnetic flux component satisfies: This ensures that no additional series inductance is introduced when the parallel circuit achieves AC current splitting.

4. The full-cycle conduction full-wave rectifier circuit for low-voltage high-current output according to claim 1, characterized in that, The first synchronous rectifier tube SR a Second synchronous rectifier tube SR b It is a power MOSFET or a gallium nitride controlled rectifier device.

5. A full-cycle conduction full-wave rectifier circuit for low-voltage, high-current output according to claim 1, characterized in that, The first output capacitor C oa Auxiliary current sharing capacitor C ob Each is composed of one or more low equivalent series inductors and capacitors connected in parallel.

6. A full-cycle conduction full-wave rectifier circuit for low-voltage, high-current output according to claim 1, characterized in that, The auxiliary current sharing capacitor C ob The terminals of the first secondary winding W1 and the second secondary winding W2 are located close to each other to reduce parasitic inductance.

7. A full-cycle conduction full-wave rectifier circuit for low-voltage high-current output according to any one of claims 1 to 6, characterized in that, The circuit is used for rectification of the transformer secondary side in LLC resonant converters, series resonant converters, or isolated DC / DC converters.

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