Single-stage wide-input soft switching resonant power supply conversion device

Abstract

The utility model provides a single-stage wide-input soft switching resonant power supply conversion device. The single-stage wide-input soft switching resonant power supply conversion device is characterized by comprising a Buck-Boost circuit and an LLC circuit, the Buck-Boost circuit comprises a switching tube Q1 and a switching tube Q2, and one switching tube Q2 is multiplexed as a lower tube of the LLC circuit. The single-stage wide-input soft switching resonant power supply conversion device is small in stress, has obvious advantages in thermal design and efficiency, and is more convenient for product development in practical application.

Description

Technical Field

[0001] The utility model relates to a power converter, in particular to a single-stage wide-input soft-switch resonant power converter. Background Art

[0002] With the rapid development of semiconductor technology, the fourth generation of electric light source LED has been widely promoted and used. Compared with traditional electric light sources, LED has many incomparable advantages, such as long life, high efficiency, low power consumption, high brightness, small size, etc., so its application in the field of lighting is particularly prominent. The LED lighting system consists of two parts: LED driver power supply and LED lamps, and the core is the LED driver power supply. High-efficiency and energy-saving high-power LED driver power supply has become an important research direction in the industry.

[0003] High frequency and miniaturization are important indicators for the current design of switching power supplies. If the driver power supply works in hard switching mode, the increase in its switching frequency will produce large switching losses and reduce the conversion efficiency of the system. Therefore, soft switching technology aimed at reducing switching losses has also become an important research hotspot in the field of power electronics research.

[0004] Resonant converters, including series, parallel, and series-parallel resonant converters, are all common soft-switching converters. After reasonable design, the resonant converter can achieve zero voltage turn-on of the switch tube and zero current turn-off of the secondary rectifier diode in a wide load range, thereby reducing the loss of the switch tube and improving efficiency. The AC-DC conversion adopts the Buck-Boost topology, and the circuit works in discontinuous mode, automatically realizing the PFC function. It is a single-switch low-order up-down converter circuit, which realizes the up-down and down-down of the intermediate DC bus voltage, reducing the stress of the subsequent LLC switch tube and capacitor.

[0005] There are mainly two technical solutions in the prior art: 1. High power is a two-stage type, in which the first stage Boost realizes power factor correction and voltage regulation, and the second stage DCDC (isolated non-isolated topology) realizes output voltage regulation (and electrical isolation, etc.). This solution is mature in technology, but the system is complex, the cost is high, and the efficiency is low; 2. Low power single-stage PFC flyback, in which a single-stage flyback realizes input power factor correction and output voltage regulation at the same time, and is mainly used in low power LED drive power supplies. This solution is mature in technology, simple in system, low in cost, and high in efficiency, but the output has obvious power frequency ripple (which will cause the LED lamp to flicker), the input voltage range is narrow, and the lack of bus capacitors brings about lightning surge problems. Utility Model Content

[0006] The main technical problem to be solved by the utility model is to provide a single-stage wide-input soft-switching resonant power conversion device, which has small stress, obvious advantages in thermal design and efficiency, and is more convenient for product development in practical applications.

[0007] In order to solve the above technical problems, the utility model provides a single-stage wide-input soft-switching resonant power conversion device, including a Buck-Boost circuit and an LLC circuit; the Buck-Boost circuit includes two switch tubes Q1 and Q2, and one of the switch tubes Q2 is reused as the lower tube of the LLC circuit.

[0008] In a preferred embodiment: the switch tubes Q1 and Q2 are turned on or off at the same time.

[0009] In a preferred embodiment: the LLC circuit further includes an upper tube Q3, and the state of Q3 is opposite to that of Q1 and Q2.

[0010] In a preferred embodiment: the switch tubes Q1, Q2 and the upper tube Q3 are controlled by PWM or PFM.

[0011] In a preferred embodiment: it also includes a rectifier bridge, whose AC input end is connected to an AC power supply, and whose DC output end is connected to a high-frequency transformer T1 through the Buck-Boost circuit and the LLC circuit.

[0012] In a preferred embodiment: the primary winding Np of the high-frequency transformer T1 has the same direction as the like-named ends of the secondary windings Ns1 and Ns2.

[0013] In a preferred embodiment: the opposite ends of the secondary windings Ns1 and Ns2 are connected to the anodes of diodes D6 and D7 respectively, the cathodes of diodes D6 and D7 are connected to each other and grounded through the electrolytic capacitor C2, and are connected to the same ends of the secondary windings Ns1 and Ns2 through the load R1.

[0014] In a preferred embodiment: the switch tubes Q1, Q2 and the upper tube Q3 are power MOS tubes.

[0015] Compared with the prior art, the technical solution of the utility model has the following beneficial effects:

[0016] The utility model provides a single-stage wide-input soft-switching resonant power conversion device, in which two MOS tubes are arranged in the Buck-Boost circuit, so that the voltage stress of the MOS tube Q2 reused as the LLC circuit can be significantly reduced, and the stress of the added MOS tube Q1 is equal to the input voltage, so the selection of the MOS tube is more advantageous, and a 500V MOS tube with high cost performance can be selected, and the main circuit also has two fewer power diodes, so the cost of power semiconductor devices can be reduced. At the same time, the working principle of the LLC circuit part is exactly the same as the working principle of the conventional LLC circuit, and Q2 and Q3 can achieve ZVS within the full load range, which will have obvious advantages in thermal design and efficiency, and is more convenient for product development in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A circuit diagram of a preferred embodiment of the utility model;

[0018] Figure 2 This is a timing diagram of a preferred embodiment of the utility model;

[0019] Figure 3-Figure 10 It is an equivalent circuit diagram of the preferred embodiment of the utility model in each mode;

[0020] Figure 11-Figure 14 This is a simple replacement circuit diagram of a preferred embodiment of the utility model. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model; it is obvious that the described embodiments are only part of the embodiments of the utility model, rather than all of the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the utility model without making creative work are within the scope of protection of the utility model.

[0022] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present utility model, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "installed / connected", "connected", etc. should be understood in a broad sense. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the utility model can be understood according to specific circumstances.

[0024] refer to Figure 1 , this example provides a single-stage wide-input soft-switching resonant power conversion device, including a rectifier bridge, a Buck-Boost circuit, an LLC circuit, a high-frequency transformer T1 and a load R1;

[0025] The rectifier bridge is a full-bridge rectifier, including four diodes D1, D2, D3, and D4; the AC input end of the rectifier bridge is connected to the AC power supply, and the DC output end outputs pulsating DC power. The DC output positive electrode is connected to the cathode of the diode D5, and the anode of the diode D5 is connected to one end of the primary side Raozu Np of the high-frequency transformer T1; the DC output negative electrode is connected to the other end of the primary side Raozu Np of the high-frequency transformer T1 through the switch tube Q1, the high-frequency capacitor Cr, and the inductor Lr.

[0026] The cathode of the diode D5 is also connected to the anode of the diode D5 through the inductor L1 and the electrolytic capacitor C1; the same-name ends of the inductor L1 and the electrolytic capacitor C1 are also connected to the high-frequency capacitor Cr through the switch tube Q2, and the anode of the diode D5 is also connected to the high-frequency capacitor Cr through the switch tube Q3.

[0027] The opposite ends of the secondary windings Ns1 and Ns2 are connected to the anodes of diodes D6 and D7 respectively, the cathodes of diodes D6 and D7 are connected to each other and grounded through the electrolytic capacitor C2, and are connected to the same ends of the secondary windings Ns1 and Ns2 through the load R1.

[0028] The primary winding Np of the high-frequency transformer T1 is in the same direction as the same-named ends of the secondary windings Ns1 and Ns2. The switch tubes Q1, Q2, and Q3 are power MOS tubes. The above-mentioned single-stage wide-input soft-switching resonant power conversion device integrates the Buck-Boost circuit and the LLC circuit together, reuses the MOS tube Q2, and makes the open MOS tube Q2 both the switch tube of the Buck-Boost circuit and the upper tube of the LLC circuit.

[0029] In terms of control, Q1, Q2, and Q3 use PWM\PFM control, Q1 and Q2 are turned on and off at the same time, and Q3 is driven complementary to Q1\Q2. D5, D6, and D7 are power diodes, which are used to rectify the high-frequency AC voltage of the secondary winding of T1 into DC. L1 and Lr are high-frequency inductors, C1 and C2 are electrolytic capacitors, and Cr is a high-frequency capacitor. T1 is a high-frequency transformer, and its primary winding Np is in the same direction as the same-named end of the secondary winding Ns1 and Ns2.

[0030] The working mode is divided into the following 7 modes:

[0031] Mode 1 [t0~t1]: Before t0, the current i of inductor L1 is L has dropped to 0. At the same time, since the body diode of Q2 is turned on, at t0, Q2 is turned on with zero voltage and zero current, and Q1 is turned on with zero current. in The Buck-Boost inductor L1 is charged through MOS tubes Q1 and Q2. The current i L With slope u in / L1 increases linearly. At the same time, the DC bus capacitor C1 provides energy to the LLC circuit through the MOS tube Q2. At this stage, the resonant inductor L in the LLC circuit r , resonant capacitor C r Participate in resonance, the resonant frequency is The secondary diode D7 is turned on, charging the output capacitor C2 and supplying power to the output load R1. It also clamps the primary winding of the transformer, so the excitation inductance of the transformer T1 does not participate in the resonance at this stage. Lm With slope nV o / L m Linear increase.

[0032] Mode 2 [t1~t2]: At t1, the resonant current is equal to the excitation current. At this time, the current of the secondary diode D8 drops to zero and turns off. The primary winding of the transformer is no longer clamped by the output voltage, and the excitation inductance participates in the resonance. The resonant frequency is MOS tubes Q1 and Q2 are still conducting, and the current i of inductor L1 L Continue to increase linearly.

[0033] Mode 3 [t2~t3]: At t2, MOS tubes Q1 and Q2 are turned off and enter the dead time. Inductor L1 starts to discharge, and its current i L The DC bus capacitor C1 is charged through the power diode D5, and the current i L The excitation inductance Lm, the resonant inductance Lr, and the resonant capacitor Cr form a series resonant circuit with a resonant frequency Resonance, the resonant current charges the junction capacitance of MOS tube Q2, and discharges the junction capacitance of MOS tube Q3, until the voltage across the junction capacitance of MOS tube Q3 drops to 0. At this stage, the resonant current is still equal to the excitation current, and the secondary diode continues to be turned off.

[0034] Mode 4 [t3~t4]: At t3, the resonant current flows through the body diode of MOS tube Q3, and MOS tube Q3 meets the zero voltage turn-on condition. In this stage, the resonant inductor Lr and the resonant capacitor Cr are at the resonant frequency. Resonance, the resonant current is greater than the excitation current, and the secondary diode D6 is turned on. The voltage across the primary winding of the transformer is clamped at -nVo, and the excitation current is at a slope of nV o / L m At this stage, the current i of inductor L1 increases linearly. L Continue to decrease.

[0035] Mode 5 [t4-t5]: At t4, the current i L in the inductor L in the Buck-Boost circuit drops to zero. MOS tube Q3 continues to conduct, and the resonant inductor L r and the resonant capacitor Cr continue to conduct at the resonant frequency. Resonance, the resonant current is greater than the excitation current, and the secondary diode D6 is turned on.

[0036] Mode 6 [t5-t6]: At t5, the current in Lr is equal to the current in Lm, the secondary rectifier diode D6 is turned off with zero current, the output voltage no longer clamps the transformer, Lm becomes a free resonant inductor and participates in the resonance, the magnetizing inductor Lm, the resonant inductor Lr, and the resonant capacitor Cr form a series resonant circuit with a resonant frequency Resonance: Since the magnetizing inductance Lm is very large, the resonance period is very large. The resonance current is consistent with the magnetizing current at this stage and is approximately a constant value.

[0037] Mode 7 [t6~t7]: At t6, MOS tube Q3 is turned off. Entering the dead time, as in mode 6, the excitation inductance Lm, the resonant inductance Lr, and the resonant capacitor Cr are at the resonant frequency. Resonance, at this stage, the resonant current is still equal to the excitation current, and the secondary rectifier diode is turned off. The resonant current discharges the junction capacitance of the MOS tube Q2 and charges the junction capacitance of the MOS tube Q3 until the voltage across the junction capacitance of the MOS tube Q2 drops to 0.

[0038] like Figure 11-14 As a simple replacement of this embodiment, the input AC power supply can be changed from two-phase AC to three-phase AC, the inductor Lr in embodiment 1 can also be integrated into the transformer T1, and the MOS tube Q1 can also be adjusted from the DC negative side of embodiment 1 to the DC positive side. The rectifier diodes D6 and D7 of the secondary winding of the transformer can also be changed to MOS tubes to achieve output synchronous rectification, etc. As long as the Buck-Boost circuit of the power conversion device includes two switch tubes Q1 and Q2, and one of the switch tubes Q2 is reused as the lower tube of the LLC circuit, no matter how the other parts are transformed, they are all simple replacements of this embodiment.

[0039] The above is only a preferred specific implementation method of the utility model, but the design concept of the utility model is not limited to this. Any technician familiar with the technical field who uses this concept to make non-substantial changes to the utility model within the technical scope disclosed by the utility model shall be deemed to infringe the protection scope of the utility model.

Claims

1. A single-stage wide input soft switching resonant power conversion device, characterized in that: It includes a Buck-Boost circuit and an LLC circuit; the Buck-Boost circuit includes two switch tubes Q1 and Q2, and one of the switch tubes Q2 is multiplexed as the lower tube of the LLC circuit.

2. A single-stage wide input soft switching resonant power conversion device according to claim 1, characterized in that: The switch tubes Q1 and Q2 are turned on or off at the same time.

3. A single-stage wide input soft switching resonant power conversion device according to claim 2, characterized in that: The LLC circuit further includes an upper tube Q3 , and the state of Q3 is opposite to that of Q1 and Q2 .

4. The single-stage wide input soft switching resonant power conversion device according to claim 3, characterized in that: The switch tubes Q1, Q2 and the upper tube Q3 are controlled by PWM or PFM.

5. A single-stage wide input soft-switching resonant power conversion device according to any one of claims 1 to 4, characterized in that: It also includes a rectifier bridge, whose AC input end is connected to an AC power supply, and whose DC output end is connected to a high-frequency transformer T1 through the Buck-Boost circuit and the LLC circuit.

6. A single-stage wide input soft-switching resonant power conversion device according to claim 5, characterized in that: The primary winding Np of the high-frequency transformer T1 has the same direction as the like-named ends of the secondary windings Ns1 and Ns2.

7. The single-stage wide input soft switching resonant power conversion device according to claim 6, characterized in that: The opposite ends of the secondary windings Ns1 and Ns2 are connected to the anodes of diodes D6 and D7 respectively, the cathodes of diodes D6 and D7 are connected to each other and grounded through the electrolytic capacitor C2, and are connected to the same ends of the secondary windings Ns1 and Ns2 through the load R1.

8. The single-stage wide input soft switching resonant power conversion device according to claim 5, characterized in that: The switch tubes Q1, Q2 and the upper tube Q3 are power MOS tubes.

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