An LLC resonant converter

Abstract

The utility model provides a kind of LLC resonant converter, including transformer primary side and transformer secondary side, the transformer primary side includes fractional order resonant network, the fractional order resonant network is constituted by one resonant inductance, one fractional order resonant capacitor, one excitation inductance. The utility model replaces fractional order resonant capacitor in traditional LLC resonant converter integer order resonant capacitor, by setting the order of fractional order resonant capacitor, it can effectively inhibit and maintain zero voltage switch (ZVS) state to surge current impact in LLC resonant converter starting stage, improve system efficiency.

Description

Technical Field

[0001] This utility model relates to the field of DC-DC converter technology, and in particular to an LLC resonant converter. Background Technology

[0002] The full-bridge LLC resonant converter, as an important topology in modern power electronics, has become a key technology for DC-DC power conversion due to its excellent energy efficiency and compact design. Based on the principle of resonant energy conversion, this technology uses a carefully designed LC resonant network to enable power switching devices to switch states under zero-voltage (ZVS) or zero-current (ZCS) conditions, effectively eliminating the losses caused by traditional hard switching and significantly improving the overall system efficiency. This advanced conversion technology, due to its superior performance, has been widely applied in various high-tech fields such as new energy vehicle power systems, large data center power supply architectures, and distributed renewable energy generation devices.

[0003] During the startup phase of an LLC resonant converter, significant inrush current surges often occur in the resonant circuit due to the need for the filter capacitor to establish an initial voltage and the low input impedance of the system. While traditional soft-start solutions are widely used to address the inrush current problem during LLC resonant converter startup, they still have significant shortcomings in practical applications: firstly, their effectiveness in suppressing inrush current surges is limited; secondly, the use of hard-switching operation mode prevents the maintenance of zero-voltage switching (ZVS) during startup, thus affecting system efficiency. Utility Model Content

[0004] The purpose of this invention is to provide an LLC resonant converter that has the advantages of maintaining a zero-voltage switching (ZVS) state during startup and effectively suppressing surge current impact.

[0005] To achieve the above-mentioned objectives of this utility model, the following technical solution is used:

[0006] An LLC resonant converter includes a primary side and a secondary side of a transformer. The primary side of the transformer includes a fractional-order resonant network, which consists of a resonant inductor, a fractional-order resonant capacitor, and a magnetizing inductor.

[0007] Furthermore, the LLC resonant converter is a full-bridge LLC resonant converter.

[0008] Furthermore, the fractional-order resonant capacitor is composed of an N-stage passive RC parallel network.

[0009] The beneficial effects of this invention are: it can effectively suppress surge current impacts and maintain zero-voltage switching (ZVS) state during the startup phase of LLC resonant converter, thereby improving system efficiency. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of an LLC resonant converter topology according to the present invention;

[0011] Figure 2 A schematic diagram of the equivalent circuit of a specific embodiment of a fractional-order resonant capacitor;

[0012] Figure 3 This is a waveform diagram of the output voltage of a specific embodiment of an LLC resonant converter according to this utility model;

[0013] Figure 4 This is a waveform diagram showing the maintenance of a zero-voltage switching (ZVS) state in a specific embodiment of an LLC resonant converter according to this utility model. Detailed Implementation Plan

[0014] To make the embodiments of this utility model clearer and more understandable, the technical solution of this utility model will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments described below are only some embodiments of this utility model and not all possible implementation cases. All equivalent implementation methods obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0015] Figure 1 This is a schematic diagram of the topology of an LLC resonant converter according to this utility model. Figure 1 As shown, the transformer includes the primary side and the secondary side. The primary side includes a fractional-order resonant network, which consists of a resonant inductor, a fractional-order resonant capacitor, and a magnetizing inductor. This embodiment of an LLC resonant converter replaces the integer-order resonant capacitor in a traditional LLC resonant converter with a fractional-order resonant capacitor. By setting the order of the fractional-order resonant capacitor, surge current impacts can be effectively suppressed during the LLC resonant converter's startup phase, maintaining a zero-voltage switching (ZVS) state and improving system efficiency.

[0016] Furthermore, the LLC resonant converter is a full-bridge LLC resonant converter, such as... Figure 1 As shown, the full-bridge LLC resonant converter uses four power switches Q1, Q2, Q3, and Q4 to form a bridge circuit on the primary side of the transformer, with an input voltage U. in The full-bridge LLC resonant converter features high efficiency, high power, wide input range, excellent voltage regulation capability, and fast dynamic response characteristics.

[0017] Furthermore, such as Figure 1 As shown, the fractional-order resonant network consists of a resonant inductor L r A fractional-order resonant capacitor Cα and a magnetizing inductor L m Composition. Where α is the order of the fractional-order resonant capacitor.

[0018] Furthermore, the fractional-order resonant capacitor is composed of an N-level passive resistor-capacitor parallel network.

[0019] exist Figure 1 The transformer secondary side shown consists of a rectifier-filter network and an output network. The rectifier-filter network comprises freewheeling diodes D1 and D2, and the output filter capacitor C. f The output network consists of load R L Output voltage U o constitute.

[0020] In specific embodiments, the parameters of each device can be configured according to actual applications. Preferably, some parameter configurations provided in this embodiment are as follows: input rated voltage of 400V, fractional-order resonant capacitor Cα of 5.223nF, order α of fractional-order resonant capacitor of 0.98, and resonant inductor L... r The magnetizing inductance is 485uH. m The voltage is 1.94mH, the resonant frequency is 100kHz, the transformer turns ratio is 17:1, and the output load resistance is R. L It has an impedance of 2.88Ω and a rated power of 200W.

[0021] The present invention is implemented as follows:

[0022] Figure 2 This is a schematic diagram of a fractional-order resonant capacitor equivalent to a four-stage passive resistor-capacitor parallel network constructed using the s-domain best rational approximation method when α equals 0.98. The resistor and capacitor are 247Ω and 1.63×10⁻⁶Ω, respectively. 14 Ω, 6.13 × 10 -9 F, 2.2 × 10 10 Ω, 4.13 × 10 -8 F, 2.28 × 10 7 Ω, 3.55×10 -8 F, 23607Ω, 1.71×10 -7 F.

[0023] The power switches Q1 and Q4 have the same switching signal, and the switches Q2 and Q3 have the same switching signal. Q1 and Q4 are turned on in a complementary manner with Q2 and Q3 with a fixed duty cycle of 0.5.

[0024] Figure 3This is a simulation experiment output voltage waveform diagram of an embodiment of this utility model. Figure 4 This is a waveform diagram of the zero-voltage switching (ZVS) state of the fourth power switch Q4 described in the simulation experiment of this utility model embodiment. During the startup process of the LLC resonant converter, the output voltage U... o The voltage reached a stable value of 16.6V, and the surge current impact was well suppressed, with a smooth waveform and the disappearance of spikes; the pulse signal U of the fourth power switch Q4... g4 and the voltage U at both ends d4 The system maintains a zero-voltage switching (ZVS) state throughout the startup process of the LLC resonant converter, thereby improving system efficiency.

[0025] For those skilled in the art, the embodiments described above are merely illustrative and not intended to limit the scope of protection of this utility model. Those skilled in the art may make various modifications, optimizations, or adjustments to this utility model. Such modifications are all within the scope and recommendations of this utility model and should be considered consistent with the spirit and protection scope of the embodiments of this utility model.

Claims

1. An LLC resonant converter, comprising a primary side of a transformer and a secondary side of a transformer, characterized in that, The primary side of the transformer includes a fractional-order resonant network, which consists of a resonant inductor, a fractional-order resonant capacitor, and a magnetizing inductor.

2. The LLC resonant converter as described in claim 1, characterized in that, The LLC resonant converter described is a full-bridge LLC resonant converter.

3. An LLC resonant converter as described in claim 1, characterized in that, The fractional-order resonant capacitor is composed of an N-level passive resistor-capacitor parallel network.

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