A switching power supply

Abstract

The application discloses a switching power supply, which comprises at least two primary circuits, each of which comprises a full-bridge module and a resonant tank module; the full-bridge module is used for converting direct current energy received from the input end into square wave energy; the resonant tank module is used for converting the square wave energy into sine wave energy by utilizing the resonant characteristic; a transformer comprises two primary windings and a secondary winding, and each primary winding is used for transmitting one of the sine wave energy to the secondary winding by the coupling effect of the transformer; and a control module is used for performing phase-shift control on the other full-bridge module when one full-bridge module is working, so as to inject reverse magnetic flux into the magnetic core of the transformer, change the magnetic flux change rate of the magnetic core of the transformer in a period, and realize output gain adjustment. The application realizes the increase of the output gain range without complex control.

Description

Technical Field

[0001] This invention belongs to the field of power supply technology, and specifically relates to a switching power supply. Background Technology

[0002] With the rapid development of new energy and power supply technologies, the demand for high output power and wide-range adjustable output voltage in related equipment is constantly increasing. To achieve wide-range adjustable output voltage, multi-stage topologies are often required for simultaneous adjustment during the design phase. This approach suffers from complex control methods and an increase in software and hardware failure points. While traditional resonant phase-shifting full-bridge circuits can achieve adjustable gain, they still have the following problems in practical applications:

[0003] (1) When the phase shift angle of a resonant phase-shifted full bridge such as PS-LLC or PS-LCC increases during phase shifting, the energy of the resonant cavity will continuously decrease, making it impossible to achieve soft switching of the MOS transistor. In order to control all MOS transistors to be in a soft-switching state, the maximum phase shift angle will be limited. The phase shift angle generally cannot reach 180°, so the minimum output gain cannot reach 0. (2) The control algorithm is complex. In order to maximize the phase shift angle and achieve soft switching of the MOSFET under the full load range, complex control strategies such as frequency conversion, dead time conversion, and phase conversion are often required during control. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a switching power supply, which at least partially solves one of the technical problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the technical solutions adopted in the embodiments of the present invention are as follows: A switching power supply, wherein at least: Two primary-side circuits, each including a full-bridge module and a resonant tank circuit module; the full-bridge module is used to receive DC energy from its input terminal and convert it into square wave energy; the resonant tank circuit module is used to realize soft switching of the switching transistor in the full-bridge module using its resonant characteristics, and convert the square wave energy into energy that tends to a sine wave. A transformer includes two primary windings and a secondary winding. Each primary winding is used to transfer a sinusoidal energy to the secondary winding through the coupling effect of the transformer. The control module is used to perform phase-shift control on another full-bridge module when one full-bridge module is working, thereby injecting reverse magnetic flux into the core of the transformer to change the rate of change of the core magnetic flux of the transformer within the cycle to achieve output gain adjustment.

[0006] Furthermore, in the full-bridge module, the first bridge arm includes a switch Q1 located at a high potential end and a switch Q2 located at a low potential end, and the second bridge arm includes a switch Q3 located at a high potential end and a switch Q4 located at a low potential end. The driving waveforms of the switches Q1 and Q4 are exactly the same and have a duty cycle of 50%. The driving waveforms of the switches Q2 and Q3 are exactly the same and have a duty cycle of 50%. The driving waveforms of the switches Q1 and Q2 are 180° out of phase. In the other full-bridge module, the first bridge arm includes a switch Q5 located at a high potential end and a switch Q6 located at a low potential end, and the second bridge arm includes a switch Q7 located at a high potential end and a switch Q8 located at a low potential end. The driving waveforms of the switches Q5 and Q8 are exactly the same and have a duty cycle of 50%. The driving waveforms of the switches Q6 and Q7 are exactly the same and have a duty cycle of 50%. The driving waveforms of the switches Q5 and Q6 are 180° out of phase.

[0007] Optionally, the phase-shifting control of one full-bridge module while the other is operating can be achieved by adjusting the phases of the switching transistors Q1 and Q5.

[0008] Optionally, each resonant tank circuit module can be independent.

[0009] Optionally, each resonant tank circuit module can be one of LLC, LCC, and LC resonant modes.

[0010] Optionally, a rectifier module and a sampling module are connected in sequence after the secondary winding. The rectifier module is used to convert the sinusoidal energy output by the secondary winding into DC energy. The sampling module is used to obtain a feedback signal characterizing the output voltage of the switching power supply and provide it to the control module. The control module adjusts the phase shift of another full-bridge module according to the feedback signal so that the output gain tends to the target.

[0011] Optionally, the rectifier module is either a full-wave rectification method or a half-wave rectification method.

[0012] Optionally, the transformer core is a UY core, the two primary windings are wound sequentially on the first circular leg of the UY core, and the secondary winding is wound on the second circular leg.

[0013] Optionally, the two primary windings are wound in the same direction and have the same name at the same end.

[0014] Optionally, the arrangement of the two primary windings and the secondary winding is symmetrical.

[0015] This invention achieves a wide range of adjustable gain without the need for complex control, thereby reducing the complexity of the control method and increasing the reliability of the hardware. The specific beneficial effects are analyzed as follows: 1. Wide output gain range: Unlike traditional phase-shift control strategies that cannot achieve zero output gain, the phase-shifting method of the switching power supply in this embodiment involves injecting reverse magnetic flux into the transformer core through phase shifting when one full-bridge module is working. Output gain is adjusted by changing the rate of change of magnetic flux in the core within the cycle. When the phase shift angle reaches 180°, the magnetic flux in the core is completely canceled out, and the rate of change of magnetic flux in the core within the cycle is 0, resulting in zero energy transmission and achieving a zero output gain.

[0016] 2. Simple control: Although the switching power supply in this embodiment of the invention becomes two full-bridge modules, each full-bridge pair shares the drive between transistors. Therefore, a single full-bridge only requires two drive signals, and the two full-bridge pairs have a total of four drive signals, which is no different from the traditional single full-bridge.

[0017] 3. Excellent soft-switching characteristics: The phase shift of the switching power supply in this embodiment of the invention is a phase shift between two full-bridge modules. The resonant state between each full-bridge module is independent. Therefore, soft switching can be achieved in the full load range without changing the dead time. Attached Figure Description

[0018] Figure 1 This is a circuit schematic diagram of the switching power supply of the present invention; Figure 2 for Figure 1 Timing diagram of the switching power supply without phase shifting; Figure 3 for Figure 1 Timing diagram of the switching power supply with a 120° phase shift; Figure 4 for Figure 1 Simulation waveform of the switching power supply after phase shift by 120°; Figures 5-1 to 5-3 for Figure 1 Simulation waveform of the switching power supply after phase shift by 180°; Figure 6 This is a schematic diagram of the transformer structure of the switching power supply of the present invention. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the purposes of describing embodiments of this application herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] It should be understood that in the specification, claims, and drawings, when a step is described as continuing into another step, the step may directly continue into that other step or be continued into that other step through a third step; when an element / unit is described as being "connected" to another element / unit, the element / unit may be "directly connected" to that other element / unit or be "connected" to that other element / unit through a third element / unit.

[0023] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions thereof will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0024] Figure 1 The circuit schematic of the switching power supply of the present invention includes an input module 100, a full-bridge module 101, a full-bridge module 102, a resonant tank circuit module 103, a resonant tank circuit module 104, a transformer module 105, a rectifier module 106, a sampling module 107, a load module 108, and a control module 109.

[0025] The function of input module 100 is to provide a DC voltage source.

[0026] The first primary-side circuit includes a full-bridge module 101 and a resonant tank circuit module 103. The full-bridge module 101 is used to receive DC energy output from the input module 100 from its input terminal and convert it into first square wave energy. The resonant tank circuit module 103 is used to realize soft switching of the switching transistor in the full-bridge module 101 by utilizing its resonant characteristics and convert the first square wave energy into energy tending towards the first sine wave.

[0027] The second primary-side circuit includes a full-bridge module 102 and a resonant tank circuit module 104. The full-bridge module 102 is used to receive DC energy output from the input module 100 and convert it into second square wave energy. The resonant tank circuit module 104 is used to realize soft switching of the switching transistor in the full-bridge module 102 by utilizing its resonant characteristics and converting the second square wave energy into energy that tends to the second sine wave.

[0028] The transformer module 105 includes a primary winding P1, a primary winding P2, and a secondary winding S1. The primary winding P1 is used to transfer the first sine wave energy to the secondary winding S1 of the transformer module 105 through the coupling effect of the transformer module 105. The primary winding P2 is used to transfer the second sine wave energy to the secondary winding S1 of the transformer module 105 through the coupling effect of the transformer module 105.

[0029] A rectifier module 106 and a sampling module 107 are connected sequentially after the secondary winding S1. The rectifier module 106 is used to convert the sinusoidal energy output from the secondary winding S1 into DC energy. The sampling module 107 is used to obtain a feedback signal characterizing the output voltage of the switching power supply and provide it to the control module 109.

[0030] The control module 109 is used to perform phase shift control on another full-bridge module when one full-bridge module is working, based on the feedback signal output by the sampling module 107. This injects reverse magnetic flux into the transformer core to change the rate of change of the transformer core magnetic flux within the cycle, thereby adjusting the output gain and making the output gain approach the target.

[0031] Please continue reading Figure 1 The full-bridge module 101 includes a first bridge arm with a switch Q1 located at a high potential end and a switch Q2 located at a low potential end, and a second bridge arm with a switch Q3 located at a high potential end and a switch Q4 located at a low potential end. The drive waveforms of the switches Q1 and Q4 are exactly the same and have a duty cycle of 50%. The drive waveforms of the switches Q2 and Q3 are exactly the same and have a duty cycle of 50%. The drive waveforms of the switches Q1 and Q2 are 180° out of phase.

[0032] Please continue reading Figure 1The full-bridge module 102 includes a first bridge arm consisting of a switch Q5 located at a high potential end and a switch Q6 located at a low potential end, and a second bridge arm consisting of a switch Q7 located at a high potential end and a switch Q8 located at a low potential end. The drive waveforms of switches Q5 and Q8 are exactly the same and have a duty cycle of 50%. The drive waveforms of switches Q6 and Q7 are exactly the same and have a duty cycle of 50%. The drive waveforms of switches Q5 and Q6 are 180° out of phase.

[0033] Those skilled in the art will understand that, in specific implementations, for Figure 1 The circuit can achieve phase-shift control of one full-bridge module while the other is working by adjusting the phases of switching transistors Q1 and Q5.

[0034] Figure 1 Although the circuit is divided into two full-bridge modules, each full-bridge pair shares the drive between transistors. Therefore, a single full-bridge only requires two drive signals, and the two full-bridge pairs have a total of four drive signals, which is no different from the traditional single full-bridge.

[0035] Furthermore, resonant tank circuit modules 103 and 104 are independent, meaning they have no electrical connection. The advantage of this design is that, under light no-load or large phase-shift angles, the available resonant energy of the lagging bridge arms is too small to charge / discharge the junction capacitance of the MOSFETs in each bridge arm to zero within the dead time, making it impossible to achieve soft-switching of all MOSFETs in each bridge arm. In contrast, non-phase-shift resonant topologies can achieve soft-switching of MOSFETs in each bridge arm throughout their switching frequency range. Therefore, by making the two resonant tank circuit modules independent and using inter-bridge phase-shift control, the advantages of both can be combined, better achieving soft-switching of all MOSFETs under light loads and 0~180°.

[0036] Figure 2 for Figure 1 Timing diagram of the switching power supply without phase shifting. Figure 3 for Figure 1 Timing diagram of the switching power supply with a 120° phase shift. Figure 4 for Figure 1 Voltage waveforms at the midpoints of each bridge arm and the primary winding of the transformer after a 120° phase shift in the switching power supply. Figure 2 and Figure 3 G1~G8 in the text are Figure 1 The drive signals for MOSFETs Q1~Q8 Figure 4 In the diagram, VB_1 is the midpoint voltage of the bridge arm of full-bridge module 1, VB_2 is the midpoint voltage of the bridge arm of full-bridge module 2, VP1 is the voltage across the primary winding P1, and VP2 is the voltage across the primary winding P2.

[0037] Figure 2When the phase is not shifted, the driving waveforms of switching transistors Q1 and Q4 are exactly the same, the driving waveforms of switching transistors Q2 and Q3 are exactly the same, the driving waveforms of switching transistors Q1 and Q2 are 180° out of phase, the driving waveforms of switching transistors Q5 and Q8 are exactly the same, the driving waveforms of switching transistors Q6 and Q7 are exactly the same, the driving waveforms of switching transistors Q5 and Q6 are 180° out of phase, and the phase angle of switching transistors Q1 and Q5 is 0.

[0038] Figure 3 When the phase shift is 120°, the driving waveforms of switches Q1 and Q4 are exactly the same, the driving waveforms of switches Q2 and Q3 are exactly the same, the driving waveforms of switches Q1 and Q2 are 180° out of phase, the driving waveforms of switches Q5 and Q8 are exactly the same, the driving waveforms of switches Q6 and Q7 are exactly the same, the driving waveforms of switches Q5 and Q6 are 180° out of phase, and the phase angles of switches Q1 and Q5 are offset by 120°.

[0039] Unlike traditional phase-shift control strategies for the conduction angle between bridge arms, this invention performs phase-shift control on one full-bridge module while the other is operating. Figure 4 for Figure 1 Simulation waveform of the switching power supply after a 120° phase shift, as shown below. Figure 4 As shown, VP1 is the voltage across the primary winding P1, VP2 is the voltage across the primary winding P2, and VB_1 is... Figure 1 The voltage between nodes A and B, VB_2 is Figure 1 The voltage between nodes C and D can be obtained from the formula for the voltage across the transformer windings: (Formula 1) In Formula 1, U is the voltage across the winding, dφ is the magnetic flux through the cross-sectional area of ​​the core, dt is the time variation, and n is the number of turns of the winding on the core.

[0040] Figure 4 The horizontal axis, between time t0 and t1, represents the phase-shifting region. Figure 4 As can be seen from the diagram, within the phase-shifted region: VB_2 is 400V, therefore the primary winding P2 is forward-energized; VB_1 is -400V, therefore the primary winding P1 is reverse-energized. Within the phase-shifted region, the magnetic flux generated by the primary windings P1 and P2 in the core is equal in magnitude and opposite in direction. The magnetic flux generated by the two phases (i.e., primary windings P1 and P2) cancels each other out, resulting in dφ=0. Therefore, the voltage across windings P1 and P2 is 0 within the phase-shifted region. Figure 4During the time interval t1~t2, the voltages of VB_1 and VB_2 are both -400V. Therefore, both the primary windings P1 and P2 are reverse-energized to transfer energy to the secondary side. Thus, by adjusting the phase shift angle θ between full-bridge modules 101 and 102, the effective conduction pulse width of the transformer's primary side can be controlled, thereby changing the average transmission voltage and achieving gain regulation. The output voltage gain formula is: (Formula 2) In Formula 2, Vo is the output voltage, Vin is the input voltage, N is the turns ratio of the transformer primary and secondary windings, and θ is the shift angle (in radians). The gain decreases linearly as the shift angle increases, so the output gain can be adjusted through the principle of magnetic flux cancellation.

[0041] It should be noted that in this invention, the positive voltage across the primary winding is defined as forward excitation and the negative voltage is defined as reverse excitation. Those skilled in the art will understand that these two definitions can be interchanged, and the two definitions are essentially the same.

[0042] Figures 5-1 to 5-3 for Figure 1 The simulation waveform diagram of the switching power supply after a 180° phase shift, where VP1 is the voltage across the primary winding P1, VP2 is the voltage across the primary winding P2, and VB_1 is... Figure 1 The voltage between nodes A and B, VB_2 is Figure 1 The voltage between nodes C and D, Q1 is Figure 1 The driving voltage of MOSFET Q1, Vds_Q1, is Figure 1 The voltage between the drain, base, and source of MOSFET Q1, and the voltage between Q2 are... Figure 1 The driving voltage of MOSFET Q2, Vds_Q2, is Figure 1 The voltage between the drain, base, and source of MOSFET Q2, and the voltage of Q3 are... Figure 1 The driving voltage of MOSFET Q3, Vds_Q3 is Figure 1 The voltage between the drain, base, and source of MOSFET Q3, and the voltage of Q4 are... Figure 1 The driving voltage of MOSFET Q4, Vds_Q4, is Figure 1 The voltage between the drain, base, and source of MOSFET Q4, and the voltage of Q5 are... Figure 1 The driving voltage of MOSFET Q5, Vds_Q5 is Figure 1 The voltage between the drain, base, and source of MOSFET Q5, and the voltage of Q6 are... Figure 1 The driving voltage of MOSFET Q6, Vds_Q6, is Figure 1 The voltage between the drain, base, and source of MOSFET Q6, and the voltage of Q7 are... Figure 1 The driving voltage of MOSFET Q7, Vds_Q7, is Figure 1 The voltage between the drain, base, and source of MOSFET Q7, and the voltage between Q8 are... Figure 1 The driving voltage of MOSFET Q8, Vds_Q8 is Figure 1 The voltage between the drain, base, and source of MOSFET Q8. Figure 1 In the circuit, when the phase shift angle of one full-bridge module relative to another reaches 180°, as shown in Figure 5, during the entire switching cycle, since VB_1 and VB_2 are equal in magnitude and opposite in direction, the primary winding P1 and the primary winding P2 are either positively or negatively energized. As a result, the magnetic flux generated in the core is equal in magnitude and opposite in direction, and the magnetic flux in the core completely cancels out. The magnetic flux density of the transformer core is 0, there is no energy transfer, and the output gain is 0. At the same time, the MOSFETs Q1~Q8 are still in the soft-on state.

[0043] Figure 6 This is a schematic diagram of the transformer structure of the switching power supply of the present invention, Figure 5 and... Figure 1 The windings in the figure are connected with the same number and the same-name terminals are connected with the same-name terminals. The UY magnetic core used in Figure 5 has a long magnetic column and a large window area, which is suitable for winding in slots. The primary winding P1 and primary winding P2 are wound sequentially on the first circular support leg of the UY magnetic core, and the secondary winding S1 is wound on the second circular support leg. The two primary windings are wound in the same direction and the same-name terminals are consistent, which reduces the potential difference, reduces parasitic capacitance, and increases the heat dissipation effect. The arrangement of the two primary windings and the secondary windings is symmetrical, the magnetic circuit is balanced, the leakage inductance is consistent, and the process consistency is high.

[0044] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention. For example, the resonant tank circuit can be specifically selected as LLC, LCC, or other resonant tank circuit types, and the rectification module rectification method can be full-wave, half-wave, etc. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A switching power supply, characterized in that, At least including: Two primary-side circuits, each including a full-bridge module and a resonant tank circuit module; the full-bridge module is used to receive DC energy from its input terminal and convert it into square wave energy; the resonant tank circuit module is used to realize soft switching of the switching transistor in the full-bridge module using its resonant characteristics, and convert the square wave energy into energy that tends to a sine wave. A transformer includes two primary windings and a secondary winding. Each primary winding is used to transfer a sinusoidal energy to the secondary winding through the coupling effect of the transformer. The control module is used to perform phase-shift control on another full-bridge module when one full-bridge module is working, thereby injecting reverse magnetic flux into the core of the transformer to change the rate of change of the core magnetic flux of the transformer within the cycle to achieve output gain adjustment.

2. The switching power supply according to claim 1, characterized in that: The first bridge arm of the full-bridge module includes a switch Q1 located at a high potential end and a switch Q2 located at a low potential end; the second bridge arm includes a switch Q3 located at a high potential end and a switch Q4 located at a low potential end. The driving waveforms of the switches Q1 and Q4 are exactly the same and have a duty cycle of 50%. The driving waveforms of the switches Q2 and Q3 are exactly the same and have a duty cycle of 50%. The driving waveforms of the switches Q1 and Q2 are 180° out of phase. In the other full-bridge module, the first bridge arm includes a switch Q5 located at a high potential end and a switch Q6 located at a low potential end, and the second bridge arm includes a switch Q7 located at a high potential end and a switch Q8 located at a low potential end. The driving waveforms of the switches Q5 and Q8 are exactly the same and have a duty cycle of 50%. The driving waveforms of the switches Q6 and Q7 are exactly the same and have a duty cycle of 50%. The driving waveforms of the switches Q5 and Q6 are 180° out of phase.

3. The switching power supply according to claim 1, characterized in that: The phase-shifting control of one full-bridge module while the other is operating is achieved by adjusting the phases of the switching transistors Q1 and Q5.

4. The switching power supply according to claim 1, characterized in that: Each resonant channel module is independent.

5. The switching power supply according to claim 1, characterized in that: Each resonant tank circuit module is one of LLC, LCC and LC resonant modes.

6. The switching power supply according to claim 1, characterized in that: A rectifier module and a sampling module are connected in sequence after the secondary winding. The rectifier module is used to convert the sinusoidal energy output by the secondary winding into DC energy. The sampling module is used to obtain a feedback signal characterizing the output voltage of the switching power supply and provide it to the control module. The control module adjusts the phase shift of another full-bridge module according to the feedback signal so that the output gain tends to the target.

7. The switching power supply according to claim 6, characterized in that: The rectifier module is either a full-wave rectifier or a half-wave rectifier.

8. The switching power supply according to claim 1, characterized in that: The transformer has a UY core, and the two primary windings are wound sequentially on the first circular support leg of the UY core, while the secondary winding is wound on the second circular support leg.

9. The switching power supply according to claim 8, characterized in that: The two primary windings are wound in the same direction and have the same name at the same end.

10. The switching power supply according to claim 8, characterized in that: The arrangement of the two primary windings and the secondary windings is symmetrical.

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