A buck-boost auxiliary soft-switching resonant network

Abstract

The application discloses a Buck-Boost auxiliary soft-switching resonant network, which comprises an input power supply side and an output power supply side, and an LC output filter circuit of the output power supply side is connected with an auxiliary soft-switching resonant network in parallel; an input end of the auxiliary soft-switching resonant network is connected with a BUCK state soft-switching auxiliary resonant network and a BOOST state soft-switching auxiliary resonant network in parallel, and then is connected with a saturated inductor in series to an output end. The BUCK state soft-switching auxiliary resonant network comprises Q3, D1 and C3; the BOOST state soft-switching auxiliary resonant network comprises Q4, D2 and C4; and the saturated inductor is connected with inductors L1 and L2 in series. The switching characteristic of the auxiliary resonant network is utilized, so that the normal power conversion in the whole range is realized, the soft turn-off of the main power tube is realized, the conversion efficiency of the whole system is effectively improved, the soft-switching characteristic has a lower turn-off voltage peak, and a better control effect is realized.

Description

Technical Field

[0001] This invention relates to Buck-Boost circuits for high-power DC power supplies, and more particularly to a Buck-Boost auxiliary soft-switching resonant network. Background Technology

[0002] With the continuous advancement of power electronics technology, the demand for high-power DC power supplies with high power density, high reliability, and high precision is becoming increasingly urgent. This is especially true in the advanced precision instrument measurement industry, where foreign technology holds a dominant position.

[0003] Currently, internationally, high-power DC power supplies typically achieve output voltage and current accuracy of one-thousandth or even one-ten-thousandth. Simultaneously, power density is continuously improving to meet the testing needs of various scenarios. Besides providing high accuracy like other instruments, high-power, high-precision power supplies also need to provide substantial power. Due to their high power, voltage, current, and power output, internal power components generate significant heat due to losses. This heat accumulation not only increases cooling costs but also reduces system reliability, frequently leading to system crashes and power supply failures due to internal overheating. Therefore, improving switching efficiency is a perpetual pursuit for switching power supplies.

[0004] Commonly used BUCK-BOOST circuit solutions include, for example Figure 1 As shown:

[0005] There are generally two existing low-loss BUCK-BOOST solutions:

[0006] The first approach uses advanced power devices with faster switching speeds and lower on-resistance to reduce switching losses. These devices are also very expensive. Higher switching frequencies and faster turn-on speeds also mean larger turn-off voltage spikes, which can negatively impact device reliability.

[0007] The second method uses synchronous rectification technology, selecting controllable devices such as silicon carbide and gallium nitride to replace diodes, thereby reducing system losses and improving conversion efficiency by utilizing lower turn-on losses.

[0008] The existing drawbacks of BUCK-BOOST:

[0009] 1) Mature and reliable, simple to control, but the turn-off voltage spike is large and the conversion efficiency is low.

[0010] 2) When using more advanced devices, the price is higher and the power is greater, there are not many types of devices to choose from.

[0011] In view of this, the present invention is hereby proposed. Summary of the Invention

[0012] The purpose of this invention is to provide a Buck-Boost assisted soft-switching resonant network to solve the aforementioned technical problems in the prior art.

[0013] The objective of this invention is achieved through the following technical solution:

[0014] The Buck-Boost auxiliary soft-switching resonant network includes an input power supply side and an output power supply side. The output power supply side is provided with an LC output filter circuit composed of an inductor L3 and a capacitor C5. The characteristic of the LC output filter circuit is that an auxiliary switching resonant network is connected in parallel.

[0015] The input terminal of the auxiliary switch resonant network consists of a BUCK state soft-switching auxiliary resonant network and a BOOST state soft-switching auxiliary resonant network connected in parallel, and then connected in series with a saturated inductor to the output terminal.

[0016] Compared with the prior art, the Buck-Boost auxiliary soft-switching resonant network provided by the present invention utilizes the switching characteristics of the auxiliary resonant network to not only achieve normal power conversion across the entire range, but also achieve soft turn-off of the main power transistors, effectively improving the overall system conversion efficiency. Under the soft-switching characteristics, it has a lower turn-off voltage spike and achieves better control performance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a commonly used Buck-Boost circuit topology in existing technologies;

[0018] Figure 2 This is a schematic diagram of the improved resonant soft-switching Buck-Boost circuit according to an embodiment of the present invention;

[0019] Figure 3 This is a timing diagram for soft switching according to an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them, and do not constitute a limitation on the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0021] First, the following explanations are provided for the terms that may be used in this article:

[0022] The terms “including,” “contains,” “comprising,” “having,” or other similar semantic descriptions shall be interpreted as non-exclusive inclusion.

[0023] The term "composed of" excludes any technical features not expressly listed. When used in a claim, it closes the claim to exclude all technical features other than those expressly listed, except for associated conventional impurities. If the term appears only in a clause of a claim, it limits the claim to the elements expressly listed in that clause; elements recited in other clauses are not excluded from the overall claim.

[0024] The technical solution provided by this invention will be described in detail below. Contents not described in detail in the embodiments of this invention are prior art known to those skilled in the art. Where specific conditions are not specified in the embodiments of this invention, they shall be performed according to conventional conditions in the art or conditions recommended by the manufacturer. Reagents or instruments used in the embodiments of this invention whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0025] like Figure 1 As shown, a Buck-Boost auxiliary soft-switching resonant network includes an input power supply side and an output power supply side. The output power supply side is provided with an LC output filter circuit composed of an inductor L3 and a capacitor C5. An auxiliary switching resonant network is connected in parallel with the LC output filter circuit.

[0026] The input terminal of the auxiliary switch resonant network consists of a BUCK state soft-switching auxiliary resonant network and a BOOST state soft-switching auxiliary resonant network connected in parallel, and then connected in series with a saturated inductor to the output terminal.

[0027] The BUCK state soft-switching auxiliary resonant network includes a three-switch transistor Q3, a one-diode D1, and a three-capacitor C3.

[0028] The soft-switching auxiliary resonant network in the BOOST state includes four switching transistors (Q4), two diodes (D2), and four capacitors (C4).

[0029] The saturated inductor is composed of inductor L1 and inductor L2 connected in series.

[0030] The drain of the switching transistor Q3 is connected to the left input terminal, and the source is connected to the anode of diode D1 and the upper end of capacitor C3, and then connected to the saturated inductor.

[0031] The source of the four-phase switching transistor Q4 is connected to the left input terminal, and the drain is connected to the cathode of the two-phase diode D2 and the lower end of the four-phase capacitor C4, and then connected to the saturated inductor.

[0032] The following timing sequence is used to turn on and off the main switch transistor at zero voltage across the entire range:

[0033] At time t0, Q1 is turned on, and the current flows through L3 to provide energy to BT2. Q2 bears the entire bus voltage of BT1.

[0034] At time t1, Q4 is turned on, and the current flows through Q4, C4, L1, and L2 to charge capacitor C4. The capacitor is positive on the left and negative on the right, and the voltage rises slowly. The inductor current rises instantly to the saturation current of L1 and L2. C4 stores energy until it becomes a capacitor, and the charging voltage slowly reaches BT1. The voltage across Q2 slowly decreases, and the voltage across Q1 slowly increases.

[0035] At time t2, the voltage across Q2 drops to 0, and the voltage across Q1 rises to BT1;

[0036] At time t3, Q2 turns on, achieving zero-voltage turn-on (ZVS).

[0037] At time t6, Q3 will be launched;

[0038] At time t7, Q2 is turned off, achieving zero-voltage turn-off (ZVS). The voltage across Q2 begins to rise, while the voltage across Q1 begins to slowly decrease.

[0039] At time t8, the voltage across Q2 rises to BT1, and the voltage across Q1 drops to 0.

[0040] At time t9, Q1 turns on, and Q2 achieves zero-voltage (ZVS) turn-on.

[0041] In summary, the Buck-Boost auxiliary soft-switching resonant network of this invention mainly utilizes the switching characteristics of the auxiliary resonant network. It not only achieves normal power conversion across the entire range, but also achieves soft turn-off of all main power transistors, effectively improving the overall system conversion efficiency. Under the soft-switching characteristics, it has a lower turn-off voltage spike and achieves better control performance.

[0042] To more clearly demonstrate the technical solution and its effects provided by the present invention, the Buck-Boost assisted soft-switching resonant network provided by the embodiments of the present invention will be described in detail below with reference to specific examples.

[0043] Example 1

[0044] like Figure 2 , Figure 3 As shown:

[0045] The working principle of this invention is explained as follows: This invention adds an auxiliary resonant network to the original Buck-Boost basic topology to meet the requirements of full-range soft switching.

[0046] The main circuit of this circuit consists of Q1, Q2, L3, and C5 forming the basic functional framework. To achieve full-range soft switching, D1, D2, Q3, Q4, C3, C4, and saturated inductors L1 and L2 are added.

[0047] At time t0, Q1 is turned on, and the current flows through L3 to provide energy to BT2. Q2 bears the entire bus voltage of BT1.

[0048] At time t1, Q4 is turned on, and the current flows through Q4, C4, L1, and L2 to charge capacitor C4. The capacitor is positive on the left and negative on the right, and the voltage rises slowly. The inductor current rises instantly to the saturation current of L1 and L2. C4 stores energy until the capacitor is fully charged, and the charging voltage slowly reaches BT1. The voltage across Q2 slowly decreases, and the voltage across Q1 slowly increases.

[0049] At time t2, the voltage across Q2 drops to 0, while the voltage across Q1 rises to BT1.

[0050] At time t3, Q2 turns on, achieving zero-voltage turn-on (ZVS).

[0051] At time t6, Q3 was launched.

[0052] At time t7, Q2 is turned off, achieving zero-voltage turn-off (ZVS). The voltage across Q2 begins to rise, while the voltage across Q1 begins to slowly decrease.

[0053] At time t8, the voltage across Q2 rises to BT1, and the voltage across Q1 drops to 0.

[0054] At time t9, Q1 turns on, and Q2 achieves zero-voltage (ZVS) turn-on.

[0055] The above achieves the turn-on and turn-off of the main switch with zero voltage (ZVS) across the entire range.

[0056] This invention addresses the shortcomings of existing technologies, such as the inability to achieve full-range soft switching and high switching losses. This design utilizes an auxiliary switching resonant network to achieve low-loss switching characteristics that enable ZVS (zero-voltage switching) turn-on and turn-off across the entire range.

[0057] The key technical points of this method are as follows:

[0058] 1) Figure 2 Q3, D1, and C3 constitute a soft-switching auxiliary resonant network in the BUCK state.

[0059] 2) Figure 2 The soft-switching auxiliary resonant network in BOOST state is composed of Q4, D1, and C4.

[0060] 3) Figure 2The saturated inductors L1 and L2 in the middle are combined with those in 1) and 2) to form a whole.

[0061] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A Buck-Boost assisted soft-switching resonant network, comprising an input power supply side and an output power supply side, wherein the output power supply side is provided with an LC output filter circuit composed of inductor L3 and capacitor C5, characterized in that, The LC output filter circuit is connected in parallel with an auxiliary switching resonant network; The input terminal of the auxiliary switch resonant network consists of a BUCK state soft-switching auxiliary resonant network and a BOOST state soft-switching auxiliary resonant network connected in parallel, and then connected in series with a saturated inductor to the output terminal.

2. The Buck-Boost assisted soft-switching resonant network according to claim 1, characterized in that: The BUCK state soft-switching auxiliary resonant network includes three switching transistors (Q3), one diode (D1), and three capacitors (C3). The BOOST state soft-switching auxiliary resonant network includes a four-switch transistor (Q4), a two-diode transistor (D2), and a four-capacitor transistor (C4). The saturated inductor is composed of inductor one (L1) and inductor two (L2) connected in series.

3. The Buck-Boost assisted soft-switching resonant network according to claim 2, characterized in that: The drain of the third switching transistor (Q3) is connected to the left input terminal, and the source is connected to the anode of the first diode (D1) and the upper end of the third capacitor (C3), and then connected to the saturated inductor; The source of the four-phase switching transistor (Q4) is connected to the left input terminal, and the drain is connected to the cathode of the second diode (D2) and the lower end of the fourth capacitor (C4), and then connected to the saturated inductor.

4. The Buck-Boost assisted soft-switching resonant network according to claim 3, characterized in that, The following timing sequence is used to turn on and off the main switch transistor at zero voltage across the entire range: At time t0, Q1 is turned on, and the current flows through L3 to provide energy to BT2. Q2 bears the entire bus voltage of BT1. At time t1, Q4 is turned on, and the current flows through Q4, C4, L1, and L2 to charge capacitor C4. The capacitor is positive on the left and negative on the right, and the voltage rises slowly. The inductor current rises instantly to the saturation current of L1 and L2. C4 stores energy until it becomes a capacitor, and the charging voltage slowly reaches BT1. The voltage across Q2 slowly decreases, and the voltage across Q1 slowly increases. At time t2, the voltage across Q2 drops to 0, and the voltage across Q1 rises to BT1; At time t3, Q2 turns on, achieving zero-voltage turn-on; At time t6, Q3 was launched; At time t7, Q2 is turned off, achieving zero-voltage turn-off. The voltage across Q2 begins to rise, while the voltage across Q1 begins to slowly decrease. At time t8, the voltage across Q2 rises to BT1, and the voltage across Q1 drops to 0. At time t9, Q1 turns on, and Q2 achieves zero-voltage turn-on.

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