Auxiliary source starting method, auxiliary source starting device, converter and power supply system

Abstract

This application discloses an auxiliary power supply startup method, an auxiliary power supply startup device, a converter, and a power supply system, belonging to the field of power electronics technology. The method is used in an isolated converter, with the auxiliary power supply located in the secondary-side converter circuit. The method includes: when the primary-side full-bridge circuit is powered and the secondary-side converter circuit is not powered, outputting a target switching signal to the primary-side full-bridge circuit to drive it to alternately enter a first stage and a second stage to supply power to the auxiliary power supply; the target switching signal is a pulse width modulation signal, the frequency of the target switching signal is the switching frequency of the switching transistors in the primary-side full-bridge circuit, and the frequency of the target switching signal is greater than the target resonant frequency of the converter, which is the resonant frequency of the resonant capacitor and the resonant inductor. This method can reduce the voltage stress on the switching transistors in the converter during auxiliary power supply startup.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology, and in particular relates to an auxiliary power source starting method, an auxiliary power source starting device, a converter, and a power supply system. Background Technology

[0002] For power conversion devices (such as microinverters) employing isolated topologies, an auxiliary power supply is typically designed on the AC side. This auxiliary power source relies on the grid-connected AC power to power the device and initiate startup. However, before grid connection, these devices lack power, requiring a pulse from the DC side to supply the auxiliary power. Once the AC auxiliary power source establishes an effective voltage, a soft start is achieved. Currently, during startup powered by the auxiliary power source, excessive voltage stress on the switching transistors can easily occur, potentially leading to device damage. Summary of the Invention

[0003] This application aims to at least solve one of the technical problems existing in the prior art. To this end, this application proposes an auxiliary power source startup method, an auxiliary power source startup device, a converter, and a power supply system, which can reduce the voltage stress of the switching transistor during the auxiliary power source startup process and prevent excessive stress from causing device damage.

[0004] In a first aspect, this application provides an auxiliary power supply startup method for an isolated converter, the converter including a primary-side full-bridge circuit and a secondary-side conversion circuit, the secondary-side conversion circuit having a resonant capacitor and a resonant inductor, the primary-side full-bridge circuit including a first and a fourth switch arranged diagonally, and a second and a third switch arranged diagonally; the auxiliary power supply of the converter is disposed in the secondary-side conversion circuit; the method includes: When the primary-side full-bridge circuit is connected to a power source and the secondary-side conversion circuit is not connected to a power source, a target switching signal is output to the primary-side full-bridge circuit to drive the primary-side full-bridge circuit to alternately enter the first stage and the second stage to supply power to the auxiliary power source. Wherein, the target switching signal is a pulse width modulation signal, the frequency of the target switching signal is the switching frequency of the switching transistor in the primary-side full-bridge circuit, the frequency of the target switching signal is greater than the target resonant frequency of the converter, and the target resonant frequency is the resonant frequency of the resonant capacitor and the resonant inductor; In the first stage, the first switch and the fourth switch are turned on, and the second switch and the third switch are turned off; in the second stage, the second switch and the third switch are turned on, and the first switch and the fourth switch are turned off.

[0005] According to the auxiliary power source startup method of this application, the primary-side full-bridge circuit is driven by the target switching signal to alternately switch in the first and second stages, adjusting the switching mode of the primary-side full-bridge circuit of the converter. The frequency set for the target switching signal is greater than the target resonant frequency of the converter. The switching frequency of the switching transistor controls the current direction. Before the current oscillation decays, the opposite voltage is excited, reducing the voltage overstress caused by the reverse recovery of the body diode. This reduces the voltage stress on the converter switching transistor during the auxiliary power source startup process, prevents excessive stress from damaging the device, improves the reliability of the converter's auxiliary power source startup process, and helps extend the service life of the converter.

[0006] According to one embodiment of this application, the frequency of the target switching signal is positively correlated with the input voltage of the primary-side full-bridge circuit.

[0007] According to one embodiment of this application, the frequency of the target switching signal is a multiple of the target resonant frequency.

[0008] According to one embodiment of this application, the multiple relationship between the frequency of the target switching signal and the target resonant frequency is determined based on the auxiliary source setup time of the converter and the stress threshold of the secondary-side switch tube.

[0009] According to one embodiment of this application, the method further includes: Within the input voltage range of the primary-side full-bridge circuit, the frequency of the target switching signal is adjusted by linear interpolation, wherein the frequency of the target switching signal is determined based on the input voltage of the primary-side full-bridge circuit.

[0010] According to one embodiment of this application, the number of interpolation points for linear interpolation is determined based on the input voltage range.

[0011] Secondly, this application provides an auxiliary power supply startup device for an isolated converter. The converter includes a primary-side full-bridge circuit and a secondary-side conversion circuit. The secondary-side conversion circuit has a resonant capacitor and a resonant inductor. The primary-side full-bridge circuit includes a first and a fourth diagonally arranged switch transistor, and a second and a third diagonally arranged switch transistor. The auxiliary power supply of the converter is located in the secondary-side conversion circuit. The device includes: The processing module is used to output a target switching signal to the primary-side full-bridge circuit when the primary-side full-bridge circuit is connected to a power source and the secondary-side conversion circuit is not connected to a power source, thereby driving the primary-side full-bridge circuit to alternately enter the first stage and the second stage to supply power to the auxiliary power source. Wherein, the target switching signal is a pulse width modulation signal, the frequency of the target switching signal is the switching frequency of the switching transistor in the primary-side full-bridge circuit, the frequency of the target switching signal is greater than the target resonant frequency of the converter, and the target resonant frequency is the resonant frequency of the resonant capacitor and the resonant inductor; In the first stage, the first switch and the fourth switch are turned on, and the second switch and the third switch are turned off; in the second stage, the second switch and the third switch are turned on, and the first switch and the fourth switch are turned off.

[0012] Thirdly, this application provides a converter, which is an isolated converter, comprising: The primary-side full-bridge circuit and the secondary-side conversion circuit are provided. The secondary-side conversion circuit has a resonant capacitor and a resonant inductor. The primary-side full-bridge circuit includes a first switch and a fourth switch arranged diagonally, as well as a second switch and a third switch arranged diagonally. The auxiliary power supply of the converter is provided in the secondary-side conversion circuit. As described in the second aspect above, the auxiliary power supply starting device is used to control the primary-side full-bridge circuit to supply power to the auxiliary power supply.

[0013] According to one embodiment of this application, the secondary-side conversion circuit is a half-bridge frequency conversion circuit, which includes a first bridge arm and a second bridge arm connected to the midpoint of the half-bridge. The auxiliary power supply is connected to the midpoint of the half-bridge and the end point of the first bridge arm that is away from the midpoint of the half-bridge. Alternatively, the auxiliary power supply is connected to the midpoint of the half-bridge and the midpoint of the first bridge arm; Alternatively, the auxiliary power supply can be connected to the midpoint of the first bridge arm and the midpoint of the second bridge arm.

[0014] Fourthly, this application provides a power supply system, comprising: As described in the third aspect above, this is an isolated converter.

[0015] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0016] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart illustrating the auxiliary source startup method provided in the embodiments of this application; Figure 2This is a schematic diagram of the auxiliary power source starting device provided in the embodiments of this application; Figure 3 This is one of the circuit diagrams of the converter provided in the embodiments of this application; Figure 4 This is a second circuit diagram of the converter provided in the embodiments of this application; Figure 5 This is the third circuit diagram of the converter provided in the embodiments of this application; Figure 6 This is a schematic diagram of the switching transistor timing during the auxiliary power source startup process in related technologies; Figure 7 This is a current and voltage waveform diagram of the auxiliary power source startup process in related technologies; Figure 8 It is one of the equivalent circuit diagrams of the auxiliary power source startup process in related technologies; Figure 9 This is the second equivalent circuit diagram of the auxiliary power source startup process in related technologies; Figure 10 This is a schematic diagram of the switching transistor timing of the auxiliary power source startup method provided in the embodiments of this application; Figure 11 This is one of the current and voltage waveforms of the auxiliary power source startup method provided in the embodiments of this application; Figure 12 This is the second current and voltage waveform diagram of the auxiliary power source startup method provided in the embodiments of this application.

[0017] Figure label: Auxiliary power source start-up device 200, processing module 210, The primary-side full-bridge circuit is 310, the isolation unit is 320, the secondary-side conversion circuit is 330, and the auxiliary power supply is 340. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0019] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0020] The auxiliary power source startup method, auxiliary power source startup device 200, converter, power supply system, electronic equipment and readable storage medium provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios.

[0021] The auxiliary source startup method provided in this application embodiment can be used for isolated converters.

[0022] Among them, isolated converters refer to power conversion devices that achieve electrical isolation between input and output through isolation units 320 (such as isolation transformers), such as inverters and DC-DC converters.

[0023] The converter in this embodiment includes a primary-side full-bridge circuit 310 and a secondary-side conversion circuit 330, which are electrically isolated from each other by an isolation unit 320.

[0024] The primary-side full-bridge circuit 310 is located on the primary side of the isolation unit 320, and the secondary-side conversion circuit 330 is located on the secondary side of the isolation unit 320.

[0025] The primary-side full-bridge circuit 310 is located on the input side of the converter and includes a first and a fourth switch arranged diagonally, as well as a second and a third switch arranged diagonally. The four switches of the primary-side full-bridge circuit 310 form a bridge structure.

[0026] For example, such as Figure 3 , Figure 4 and Figure 5 As shown, the primary-side full-bridge circuit 310 includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4, wherein S1, S2, S3, and S4 form a bridge structure.

[0027] The secondary-side converter circuit 330 of the converter has a resonant capacitor and a resonant inductor.

[0028] The resonant capacitor can include the parasitic capacitance of the switching transistor in the secondary-side converter circuit 330, or it can include the parasitic capacitance of the switching transistor in the secondary-side converter circuit 330 and an external capacitor (such as...). Figure 3 Cr1 and Cr2 in Figure 4 and Figure 5 (Cr in the capacitor) Resonant capacitors can have functions such as resonance, voltage multiplication, and DC blocking.

[0029] The resonant inductor may include the leakage inductance of the isolation unit 320 (such as a transformer), or it may include the leakage inductance of the isolation unit 320 and an external inductor (such as...). Figure 3 , Figure 4 and Figure 5 Lr in the middle.

[0030] In this embodiment, the auxiliary power supply 340 of the converter is located in the secondary-side converter circuit 330.

[0031] In actual operation, when the secondary-side conversion circuit 330 is connected to a power source, the auxiliary power supply 340 can be powered by the power source connected to the secondary-side conversion circuit 330.

[0032] For example, the secondary-side converter circuit 330 is connected to the power grid, using grid power to supply power to the auxiliary power supply 340, maintaining the energy of the auxiliary power supply 340 without energy drop, reducing electromagnetic interference (EMI), thereby reducing costs and improving efficiency. In some embodiments, the secondary-side converter circuit 330 can be a half-bridge frequency converter circuit.

[0033] In this embodiment, the secondary-side conversion circuit 330 adopts a half-bridge cyclic converter topology, including at least four power switches. These switches form a half-bridge structure and work in conjunction with the primary-side full-bridge circuit 310 to realize the power conversion function of the converter.

[0034] The half-bridge frequency conversion circuit includes a first bridge arm and a second bridge arm connected at the midpoint of the half-bridge. The first bridge arm has at least two power switching transistors connected in series, and the second bridge arm has at least two power switching transistors connected in series.

[0035] For example, such as Figure 3 As shown, the secondary-side converter circuit 330 is a half-bridge frequency converter circuit. S5 and S6 are connected in series to form the first bridge arm, and S7 and S8 are connected in series to form the second bridge arm. The connection point of S6 and S7 is the midpoint of the half-bridge connecting the first bridge arm and the second bridge arm.

[0036] In practice, one of the first and second bridge arms can be used as the upper bridge arm, and the other can be used as the lower bridge arm.

[0037] It should be noted that for a single bridge arm, including the bridge arm endpoints and the bridge arm midpoint, the connection point of the two power switches connected in series can be called the bridge arm midpoint. For example, the connection point of S5 and S6 in the upper bridge arm can be called the bridge arm midpoint, and the connection point of S7 and S8 in the lower bridge arm can be called the bridge arm midpoint.

[0038] It is understandable that the first and second bridge arms, which are connected at the midpoint of the half-bridge, form the midpoint of the half-bridge by connecting one end of the first bridge arm with one end of the second bridge arm.

[0039] The auxiliary power supply 340 draws power from the secondary-side conversion circuit 330 in a circuit that can have at least one of the following structural forms: Firstly, the auxiliary power supply 340 connects the midpoint of the half-bridge to the end point of the first bridge arm that is furthest from the midpoint of the half-bridge.

[0040] Among them, the end point of the first bridge arm that is far from the midpoint of the half-bridge can be used as the positive or negative terminal of the secondary-side conversion circuit 330.

[0041] In practice, the switching transistors on the first bridge arm, second bridge arm, and other bridge arms can be of the type Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), Insulated Gate Bipolar Transistor (IGBT), Gallium Nitride (GaN), etc., and this application does not limit them.

[0042] Taking the MOSFET as the switching transistor of the first bridge arm as an example, the bridge arm endpoint furthest from the midpoint of the half-bridge can be the drain of the first bridge arm.

[0043] For example, such as Figure 3 As shown, the secondary-side conversion circuit 330 is a half-bridge frequency conversion circuit, which consists of S5, S6, S7, and S8 forming a half-bridge topology. S5 and S6 form the upper bridge arm, and S7 and S8 form the lower bridge arm. The auxiliary power supply 340 is connected to the midpoint of the half-bridge and the drain of the upper bridge arm S5, and / or, the auxiliary power supply 340 is connected to the midpoint of the half-bridge and the drain of the lower bridge arm S8. After the auxiliary power supply 340 is started, it can directly output driving energy to the gate circuit through the gate driver, which has fast driving response speed and strong control timeliness.

[0044] Secondly, the auxiliary power supply 340 connects the midpoint of the half-bridge and the midpoint of the first bridge arm.

[0045] For example, such as Figure 4As shown, the auxiliary power supply 340 is connected to the midpoint of the half-bridge and the midpoint of the upper bridge arm (the common source node between S5 and S6), and / or, the auxiliary power supply 340 is connected to the midpoint of the half-bridge and the midpoint of the lower bridge arm (the common source node between S7 and S8). The auxiliary power supply 340 obtains the power supply potential from the midpoint of the half-bridge. The potential fluctuation of the midpoint of the half-bridge is small. Using this as a reference, the drive power supply is provided to the half-bridge switching transistors (S5-S8), which can avoid the potential offset between the drive signal and the main power circuit. The drive circuit is simpler and more reliable, and the stability and reliability of the auxiliary power supply 340 are effectively improved.

[0046] Third, the auxiliary power supply 340 is connected to the midpoint of the first bridge arm and the midpoint of the second bridge arm.

[0047] For example, such as Figure 5 As shown, the auxiliary power supply 340 is connected to the midpoint of the upper bridge arm (the common source node between S5 and S6) and the midpoint of the lower bridge arm (the common source node between S7 and S8). This can maintain the symmetry of the potential at the midpoint of the two bridge arms, so that the common-mode interference is canceled out at the midpoint of the bridge arms, effectively reducing the common-mode voltage difference and thus reducing electromagnetic interference.

[0048] In some embodiments, the secondary-side conversion circuit 330 may also be a full-bridge conversion circuit or a conversion circuit of other topologies, which is not limited herein.

[0049] It should be noted that when the secondary-side conversion circuit 330 is not connected to the power supply and the primary-side full-bridge circuit 310 is connected to the power supply, the auxiliary power supply 340 can be powered by the power supply connected to the primary-side full-bridge circuit 310. For example, the auxiliary power supply 340 can be started by controlling the output pulse of the switching transistor of the primary-side full-bridge circuit 310 to charge it.

[0050] For example, the primary-side full-bridge circuit 310 is connected to the photovoltaic module, the secondary-side conversion circuit 330 is connected to the grid, and the grid-connected relay of the converter is not closed. The power provided by the photovoltaic module can supply power to the auxiliary power supply 340 to start the auxiliary power supply 340.

[0051] This application provides an auxiliary power supply startup method. By supplying power to the auxiliary power supply 340 through the primary-side full-bridge circuit 310, the voltage stress of the switching transistors during the auxiliary power supply startup process can be reduced, preventing excessive stress from damaging the devices, improving the reliability of the converter's auxiliary power supply startup process, and helping to extend the service life of the converter.

[0052] The execution subject of this auxiliary source startup method can be an electronic device or a functional module or entity in an electronic device that can implement the auxiliary source startup method. The auxiliary source startup method provided in this application embodiment is described below using an electronic device as the execution subject.

[0053] like Figure 1As shown, the auxiliary source startup method includes: step 110.

[0054] Step 110: When the primary-side full-bridge circuit 310 is connected to power and the secondary-side conversion circuit 330 is not connected to power, output the target switching signal to the primary-side full-bridge circuit 310 to drive the primary-side full-bridge circuit 310 to alternately enter the first stage and the second stage to supply power to the auxiliary power supply 340.

[0055] The target switching signal is a pulse width modulation (PWM) signal.

[0056] In this embodiment, the frequency of the target switching signal is the switching frequency of the switching transistor in the primary-side full-bridge circuit 310. By adjusting the frequency of the target switching signal, the switching frequency of the switching transistor in the primary-side full-bridge circuit 310 can be changed.

[0057] When the primary-side full-bridge circuit 310 is connected to the power supply and the secondary-side conversion circuit 330 is not connected to the power supply, the target switching signal is output to the primary-side full-bridge circuit 310. The primary-side full-bridge circuit 310 responds to the target switching signal and alternately enters the first stage and the second stage, driving the switching transistors of the primary-side full-bridge circuit 310 to turn on and off in an orderly manner, so as to supply power to the auxiliary power supply 340.

[0058] In this embodiment, in the first stage, the first and fourth switches are turned on, and the second and third switches are turned off; in the second stage, the second and third switches are turned on, and the first and fourth switches are turned off.

[0059] It is understandable that when the primary-side full-bridge circuit 310 switches between the first and second stages, a sudden voltage is generated on the primary side to provide excitation for the auxiliary power supply 340, thereby enabling the power supply to the auxiliary power supply 340.

[0060] In actual operation, the primary-side full-bridge circuit 310 alternately enters the first and second stages, sending high-frequency pulse width modulation (PWM) signals to charge the auxiliary power supply 340 located in the secondary-side conversion circuit 330 through the isolation unit 320. After establishing the auxiliary source voltage (e.g., 12V) of the auxiliary power supply 340, it drives the switching transistor of the secondary-side conversion circuit 330 to perform soft start, closing the corresponding switch. For example, closing the grid-connected relay connects the secondary-side conversion circuit 330 to the power supply. If connected to the grid, the grid power is used to supply power to the auxiliary power supply 340, maintaining the energy of the auxiliary power supply 340 from dropping, so as to perform subsequent power control.

[0061] It should be noted that the primary-side full-bridge circuit 310 alternately enters the first stage and the second stage, and there are no other switching transistors conducting between the first stage and the second stage; when switching between the first stage and the second stage, a short time interval is allowed during which the first, second, third, and fourth switching transistors are all turned off.

[0062] In this embodiment, the frequency of the target switching signal is greater than the target resonant frequency of the converter, which is the resonant frequency of the resonant capacitor and the resonant inductor.

[0063] The target resonant frequency can refer to the resonant frequency obtained by calculating the total equivalent resonant capacitance of all capacitor elements participating in the resonant process and the total equivalent resonant inductance of all inductor elements participating in the resonant process in the secondary-side converter circuit 330 of the converter, according to the resonant frequency calculation formula.

[0064] For example, the equivalent total capacitance (i.e., the equivalent resonant total capacitance) of the parasitic capacitance of the switching transistor and the external capacitance in the secondary-side converter circuit 330 is: The leakage inductance of the transformer (i.e., the equivalent resonant total inductance) is Then the target resonant frequency When the primary-side full-bridge circuit 310 is driven by the target switching signal to alternate between the first and second stages, the switching frequency of the switching transistor is greater than the target resonant frequency. .

[0065] It should be noted that the frequency of the target switching signal is greater than the target resonant frequency, which makes the switching frequency of the switching transistor in the primary-side full-bridge circuit 310 greater than the target resonant frequency. This allows for the excitation of an opposite voltage before the current oscillation in the previous stage (first stage or second stage) has decayed. By controlling the current direction through the signal frequency, the current direction in the next stage (second stage or first stage) is fixed, thus solving the problem of over-stress voltage in the switching transistor in the primary-side full-bridge circuit 310 caused by the reverse recovery of the body diode, and providing reliable power supply for the auxiliary power supply 340.

[0066] In related technologies, the upper and lower switches of the same bridge arm on the primary side (generally the DC side) are typically controlled to conduct alternately, and the phase shift angle of the adjacent bridge arm switches is adjusted to give the transformer three output voltage levels: positive voltage, zero voltage, and negative voltage. Among these, the duration of positive voltage and negative voltage is short, and the pulse width ratio is small. However, this method leads to the transformer current being in a slowly decreasing high-frequency oscillation state during the zero-voltage phase of a switching cycle. This makes it difficult to determine the magnitude and direction of the current at the moment the switch (such as a MOSFET) turns on, and it is easy for the body diode of the switch on the other bridge arm to still be in a freewheeling state when one bridge arm is turned on. Due to the reverse recovery effect of the body diode, the voltage stress of the switch may increase or even cause overvoltage damage to the device. At the same time, the voltage stress of the switch on the secondary side (generally the AC side) may also be superimposed on the power supply voltage connected to the secondary-side converter circuit 330 due to pulse excitation. If it is superimposed on the mains voltage, it will lead to overstress.

[0067] Taking a converter as an inverter, the power supply connected to the secondary side of the converter as the power grid, and the transformer primary side equipped with four switching transistors S1, S2, S3 and S4, forming a bridge structure, as an example.

[0068] The primary input voltage is Ui, and the secondary output voltage is Uo.

[0069] like Figure 6 As shown, in the related technology, after the primary side bridge arm pairs of tubes are alternately turned on, the switch is made to turn on the two upper tubes of the bridge arm or the two lower tubes of the bridge arm; wherein, in the P1 stage, S1 and S4 are turned on, and S2 and S3 are turned off; in the P2 stage, S2 and S3 are turned on, and S1 and S4 are turned off; in the P3 stage, S1 and S3 are turned on, and S2 and S4 are turned off (or S2 and S4 are turned on, and S1 and S3 are turned off).

[0070] In stages P1 and P2, positive and negative voltages appear on the primary side of the transformer, respectively. In stage P3, the primary side of the transformer is in a zero-voltage short-circuit state. When the current induced in stages P1 and P2 switches to stage P3, the inductor current will exhibit a slow and continuous oscillating decay.

[0071] like Figure 7 As shown, when the circuit is turned on in the next cycle, due to the inductor current I... in Slow and continuous oscillation, with the current direction not fixed at time t1, easily exhibiting the reverse recovery characteristic of the body diode ( Figure 7 The reverse recovery voltage U1 is shown as the voltage overstress condition of the switching transistor caused by the reverse recovery voltage; where Upri represents the three output states of the transformer: positive voltage, negative voltage, and zero voltage.

[0072] like Figure 8As shown, when the primary-side bridge arm switch switches from stage P3 of the previous cycle to stage P1 of the next cycle, that is, when S2 and S4 are switched to S1 and S4 are switched to conduct, the resonant current when the transformer primary side is in a zero-voltage short-circuit state still flows through the body diode of S2 (as shown by the red arrow in the figure). At this time, the voltage U that S2 bears is equivalent to the input voltage Ui superimposed on the reverse recovery voltage U1 of the body diode, which can easily cause the switch to be over-stressed and damaged.

[0073] During rapid startup in the relay engagement process, the voltage at the midpoint of the secondary bridge arm is superimposed on the inverter voltage. The entire superimposed voltage is applied to the secondary switching transistor, causing it to be damaged due to excessive voltage stress. Figure 9 As shown, the voltage U2 at the midpoint of the bridge arm is negative, and the output voltage Uo is positive. Therefore, the voltages U2 and Uo will be superimposed on S5, resulting in overstress of the voltage in S5.

[0074] In this embodiment, by adjusting the switching mode and frequency of the primary-side full-bridge circuit 310 of the converter, the primary-side full-bridge circuit 310 is driven by a target switching signal to alternately switch in the first and second stages. The frequency of the target switching signal is greater than the target resonant frequency. By controlling the current direction through frequency, an opposite voltage is excited before the current oscillation has decayed, making the output current direction controllable. That is, the current direction is determined when the next cycle is turned on. This solves the problem of over-stress voltage on the switching transistors in the primary-side full-bridge circuit 310 caused by the reverse recovery of the body diode, reduces the voltage stress on the converter switching transistors during the auxiliary power source startup process, prevents excessive stress from damaging the devices, improves the reliability of the converter's auxiliary power source startup process, and helps to extend the service life of the converter.

[0075] For example, such as Figure 10 As shown, when the primary-side full-bridge circuit 310 is powered on and the secondary-side conversion circuit 330 is not powered on, a target switching signal is output to the primary-side full-bridge circuit 310, driving the primary-side full-bridge circuit 310 to alternately enter the first stage T1 and the second stage T2. In stage T1, S1 and S4 are turned on, and S2 and S3 are turned off; in stage T2, S2 and S3 are turned on, and S1 and S4 are turned off; stages T1 and T2 alternate, as shown. Figure 11 As shown, Upri switches between positive and negative voltages; the frequency of the target switching signal is greater than the target resonant frequency, and the opposite voltage is applied before the current oscillation decays. When I turns on in the next cycle... in With the direction determined, the voltage Usec of the switching transistors in the primary-side full-bridge circuit 310 will not exhibit voltage superposition, thus avoiding overstress in the switching transistors (i.e., primary-side switching transistors) of the primary-side full-bridge circuit 310 and improving the safety and reliability of the converter operation.

[0076] According to the auxiliary power source startup method provided in this application embodiment, the primary-side full-bridge circuit 310 is driven by the target switching signal to alternately switch in the first and second stages, adjusting the switching mode of the primary-side full-bridge circuit 310 of the converter. The frequency set for the target switching signal is greater than the target resonant frequency of the converter. The switching frequency of the switching transistor controls the current direction. Before the current oscillation decays, the opposite voltage is excited, reducing the over-stress of the switching transistor voltage in the primary-side full-bridge circuit 310 caused by the reverse recovery of the body diode. This reduces the voltage stress on the converter switching transistor during the auxiliary power source startup process, prevents excessive stress from damaging the device, improves the reliability of the converter's auxiliary power source startup process, and helps extend the service life of the converter.

[0077] In some embodiments, the frequency of the target switching signal is positively correlated with the input voltage of the primary-side full-bridge circuit 310.

[0078] In this embodiment, the frequency of the target switching signal is dynamically adjusted according to the input voltage of the primary-side full-bridge circuit 310. The higher the input voltage of the primary-side full-bridge circuit 310, the higher the frequency of the target switching signal, which can enable the switching transistors of the converter to work stably within the full operating voltage range (that is, the input voltage range of the primary-side full-bridge circuit 310), effectively ensuring the safety of the devices and the reliable operation of the system.

[0079] Understandably, the target switching signal is a PWM signal. When the target switching signal frequency is high, the duration of a single pulse is short, and the excitation time is correspondingly shortened; when the target switching signal frequency is low, the duration of a single pulse is long, and the excitation time is correspondingly extended. When the input voltage of the primary-side full-bridge circuit 310 is high, a higher switching signal frequency is selected to shorten the excitation pulse width and avoid overvoltage; when the input voltage of the primary-side full-bridge circuit 310 is low, a lower switching signal frequency is selected to extend the excitation time and ensure that the auxiliary power supply 340 can be reliably established.

[0080] For example, such as Figure 11 As shown, when the input voltage of the primary-side full-bridge circuit 310 is low, the frequency of the target switching signal is reduced, and the duration of the first and second stages within one square wave cycle is extended accordingly. The excitation pulse width is wide enough to ensure the stable establishment of the auxiliary power supply 340 under low-voltage conditions.

[0081] like Figure 12 As shown, when the input voltage of the primary-side full-bridge circuit 310 is high, the frequency of the target switching signal is increased, shortening the duration of the first and second stages within one square wave cycle. This ensures that the auxiliary power supply 340 is stably established while effectively controlling the voltage stress of the secondary-side switching transistors, thus avoiding overvoltage damage.

[0082] In this embodiment, the frequency of the target switching signal (i.e., the switching frequency) is adjusted according to the input voltage to reduce the stress on the secondary-side switching transistor, solve the problem of over-stress on the switching transistor across the entire operating voltage range, and ensure the stable operation of the entire converter system.

[0083] In some embodiments, the frequency of the target switching signal is a multiple of the target resonant frequency.

[0084] In this embodiment, when the input voltage of the primary-side full-bridge circuit 310 is high, the multiple of the target switching signal frequency to the target resonant frequency is W1, and when the input voltage of the primary-side full-bridge circuit 310 is low, the multiple of the target switching signal frequency to the target resonant frequency is W2, wherein W1 > W2.

[0085] For example, Given the target resonant frequency, when the input voltage of the primary-side full-bridge circuit 310 is Ui1, the frequency of the target switching signal is 6. When the input voltage of the primary-side full-bridge circuit 310 is Ui2, the frequency of the target switching signal is 12. , where Ui2 > Ui1.

[0086] In some embodiments, the multiple relationship between the frequency of the target switching signal and the target resonant frequency is determined based on the auxiliary source setup time of the converter and the stress threshold of the secondary-side switch.

[0087] Among them, the auxiliary power supply establishment time limit refers to the maximum time required from the start of power supply to the auxiliary power supply 340 until the voltage of the auxiliary power supply 340 reaches the stable working requirements; the secondary-side switching transistor stress threshold refers to the maximum electrical stress limit that the switching transistor in the secondary-side conversion circuit 330 can withstand safely for a long time.

[0088] For example, the auxiliary source setup time is 150 milliseconds (ms), and the stress threshold of the secondary-side switch is 130 volts (V).

[0089] In this embodiment, based on the target resonant frequency, the frequency of the target switching signal is set, and the primary-side full-bridge circuit 310 is driven to alternately enter the first stage and the second stage through the target switching signal, so as to stabilize the auxiliary source within the auxiliary source establishment time limit, while avoiding the stress of the switching transistor of the secondary-side conversion circuit 330 from exceeding the stress threshold of the secondary-side switching transistor.

[0090] In some embodiments, the secondary source startup method further includes: Within the input voltage range of the primary-side full-bridge circuit 310, the frequency of the target switching signal is adjusted by linear interpolation, wherein the frequency of the target switching signal is determined based on the input voltage of the primary-side full-bridge circuit 310.

[0091] In this embodiment, multiple operating points are selected within the input voltage range of the primary-side full-bridge circuit 310, and the frequency of the target switching signal (hereinafter referred to as signal frequency) corresponding to each operating point is calculated. Then, based on the voltage of two adjacent operating points and the corresponding signal frequency, a linear interpolation algorithm is used to calculate the signal frequency under any input voltage. Within the input voltage range, the signal frequency is continuously and adaptively adjusted with the input voltage, thereby improving the stability and reliability of the auxiliary power supply 340 during startup.

[0092] For example, selecting 6 operating points within the input voltage range, the target switching signal frequencies are 6... 7 8 9 10 11 12 Among them, the frequency of the target switching signal at the lowest operating point with the lowest voltage is 6. The frequency of the target switching signal at the highest operating point with the highest voltage is 12. Within the input voltage range, the signal frequency is adjusted by linear interpolation so that the signal frequency corresponding to any input voltage can be adapted to the control requirements of the auxiliary source setup time and the stress threshold of the secondary switch tube under that input voltage.

[0093] In some embodiments, the number of interpolation points for linear interpolation is determined based on the input voltage range.

[0094] In this embodiment, the number of interpolation points is determined based on the input voltage range. When the input voltage range is wide, the voltage fluctuation may be large, so the number of interpolation points can be increased to improve control accuracy. When the input voltage range is small, the voltage fluctuation is limited, so the number of interpolation points can be reduced to simplify the control logic.

[0095] The auxiliary source startup method provided in this application can be executed by an auxiliary source startup device 200. This application uses the auxiliary source startup device 200 executing the auxiliary source startup method as an example to illustrate the auxiliary source startup device 200 provided in this application.

[0096] This application embodiment also provides an auxiliary power supply startup device 200, which is used for an isolated converter. The converter includes a primary-side full-bridge circuit 310 and a secondary-side conversion circuit 330. The secondary-side conversion circuit 330 has a resonant capacitor and a resonant inductor. The primary-side full-bridge circuit 310 includes a first switch and a fourth switch arranged diagonally, as well as a second switch and a third switch arranged diagonally. The auxiliary power supply 340 of the converter is disposed in the secondary-side conversion circuit 330.

[0097] like Figure 2 As shown, the auxiliary power source starting device 200 includes: The processing module 210 is used to output a target switching signal to the primary-side full-bridge circuit 310 when the primary-side full-bridge circuit 310 is connected to a power source and the secondary-side conversion circuit 330 is not connected to a power source, thereby driving the primary-side full-bridge circuit 310 to alternately enter the first stage and the second stage to supply power to the auxiliary power supply 340.

[0098] The target switching signal is a pulse width modulation signal, the frequency of the target switching signal is the switching frequency of the switching transistor in the primary-side full-bridge circuit 310, the frequency of the target switching signal is greater than the target resonant frequency of the converter, and the target resonant frequency is the resonant frequency of the resonant capacitor and the resonant inductor.

[0099] In the first stage, the first and fourth switches are turned on, while the second and third switches are turned off; in the second stage, the second and third switches are turned on, while the first and fourth switches are turned off.

[0100] According to the auxiliary power supply startup device 200 provided in the embodiments of this application, the primary-side full-bridge circuit 310 is driven to switch alternately in the first and second stages by a target switching signal. The switching mode of the switching transistors of the primary-side full-bridge circuit 310 of the converter is adjusted. The frequency set for the target switching signal is greater than the target resonant frequency of the converter. The current direction is controlled by the switching frequency of the switching transistors. Before the current oscillation has decayed, the opposite voltage is excited, which reduces the over-stress of the switching transistors in the primary-side full-bridge circuit 310 caused by the reverse recovery of the body diode. This reduces the voltage stress on the switching transistors of the converter during the auxiliary power supply startup process, prevents the device from being damaged due to excessive stress, improves the reliability of the auxiliary power supply startup process of the converter, and helps to extend the service life of the converter.

[0101] In some embodiments, the frequency of the target switching signal is positively correlated with the input voltage of the primary-side full-bridge circuit 310.

[0102] In some embodiments, the frequency of the target switching signal is a multiple of the target resonant frequency.

[0103] In some embodiments, the multiple relationship between the frequency of the target switching signal and the target resonant frequency is determined based on the auxiliary source setup time of the converter and the stress threshold of the secondary-side switch.

[0104] In some embodiments, the processing module 210 is further configured to: Within the input voltage range of the primary-side full-bridge circuit 310, the frequency of the target switching signal is adjusted by linear interpolation, wherein the frequency of the target switching signal is determined based on the input voltage of the primary-side full-bridge circuit 310.

[0105] In some embodiments, the number of interpolation points for linear interpolation is determined based on the input voltage range.

[0106] The auxiliary power source starting device 200 in the embodiments of this application can be an electronic device or a component in an electronic device, such as an integrated circuit or a chip.

[0107] The auxiliary source starting device 200 provided in this application embodiment can realize the various processes implemented in the above-described auxiliary source starting method embodiment. To avoid repetition, it will not be described again here.

[0108] This application also provides a converter that is isolated.

[0109] The converter includes a primary-side full-bridge circuit 310, a secondary-side conversion circuit 330, and an auxiliary power supply start-up device 200 as described above. The auxiliary power supply start-up device 200 is used to control the primary-side full-bridge circuit 310 to supply power to the auxiliary power supply 340.

[0110] Electrical isolation between the primary-side full-bridge circuit 310 and the secondary-side conversion circuit 330 is achieved through the isolation unit 320.

[0111] The primary-side full-bridge circuit 310 is located on the primary side of the isolation unit 320, and the secondary-side conversion circuit 330 is located on the secondary side of the isolation unit 320.

[0112] The primary-side full-bridge circuit 310 is located on the input side of the converter and includes a first and a fourth switch arranged diagonally, as well as a second and a third switch arranged diagonally. The four switches of the primary-side full-bridge circuit 310 form a bridge structure.

[0113] For example, such as Figure 3 , Figure 4 and Figure 5 As shown, the primary-side full-bridge circuit 310 includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4, wherein S1, S2, S3, and S4 form a bridge structure.

[0114] The secondary-side converter circuit 330 of the converter has a resonant capacitor and a resonant inductor.

[0115] The resonant capacitor can include the parasitic capacitance of the switching transistor in the secondary-side converter circuit 330, or it can include the parasitic capacitance of the switching transistor in the secondary-side converter circuit 330 and an external capacitor (such as...). Figure 3 Cr1 and Cr2 in Figure 4 and Figure 5 (Cr in the capacitor) Resonant capacitors can have functions such as resonance, voltage multiplication, and DC blocking.

[0116] The resonant inductor may include the leakage inductance of the isolation unit 320 (such as a transformer), or it may include the leakage inductance of the isolation unit 320 and an external inductor (such as...). Figure 3 , Figure 4 and Figure 5 Lr in the middle.

[0117] In this embodiment, the auxiliary power supply 340 of the converter is located in the secondary-side converter circuit 330.

[0118] In actual operation, when the secondary-side conversion circuit 330 is connected to a power source, the auxiliary power supply 340 can be powered by the power source connected to the secondary-side conversion circuit 330.

[0119] For example, the secondary-side conversion circuit 330 is connected to the power grid, and the grid power is used to supply power to the auxiliary power supply 340, maintaining the energy of the auxiliary power supply 340 without dropping, reducing the impact of electromagnetic interference (EMI), which can reduce costs and improve efficiency.

[0120] In some embodiments, the secondary-side conversion circuit 330 can be a half-bridge frequency conversion circuit.

[0121] In this embodiment, the secondary-side conversion circuit 330 adopts a half-bridge cyclic converter topology, including at least four power switches. These switches form a half-bridge structure and work in conjunction with the primary-side full-bridge circuit 310 to realize the power conversion function of the converter.

[0122] The half-bridge frequency conversion circuit includes a first bridge arm and a second bridge arm connected at the midpoint of the half-bridge. The first bridge arm has at least two power switching transistors connected in series, and the second bridge arm has at least two power switching transistors connected in series.

[0123] For example, such as Figure 3 As shown, the secondary-side converter circuit 330 is a half-bridge frequency converter circuit. S5 and S6 are connected in series to form the first bridge arm, and S7 and S8 are connected in series to form the second bridge arm. The connection point of S6 and S7 is the midpoint of the half-bridge connecting the first bridge arm and the second bridge arm.

[0124] In practice, one of the first and second bridge arms can be used as the upper bridge arm, and the other can be used as the lower bridge arm.

[0125] It should be noted that for a single bridge arm, including the bridge arm endpoints and the bridge arm midpoint, the connection point of the two power switches connected in series can be called the bridge arm midpoint. For example, the connection point of S5 and S6 in the upper bridge arm can be called the bridge arm midpoint, and the connection point of S7 and S8 in the lower bridge arm can be called the bridge arm midpoint.

[0126] It is understandable that the first and second bridge arms, which are connected at the midpoint of the half-bridge, form the midpoint of the half-bridge by connecting one end of the first bridge arm with one end of the second bridge arm.

[0127] The auxiliary power supply 340 draws power from the secondary-side conversion circuit 330 in a circuit that can have at least one of the following structural forms: Firstly, the auxiliary power supply 340 connects the midpoint of the half-bridge to the end point of the first bridge arm that is furthest from the midpoint of the half-bridge.

[0128] Among them, the end point of the first bridge arm that is far from the midpoint of the half-bridge can be used as the positive or negative terminal of the secondary-side conversion circuit 330.

[0129] In practice, the switching transistors on the first bridge arm, second bridge arm, and other bridge arms can be of the type Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), Insulated Gate Bipolar Transistor (IGBT), Gallium Nitride (GaN), etc., and this application does not limit them.

[0130] Taking the MOSFET as the switching transistor of the first bridge arm as an example, the bridge arm endpoint furthest from the midpoint of the half-bridge can be the drain of the first bridge arm.

[0131] For example, such as Figure 3 As shown, the secondary-side conversion circuit 330 is a half-bridge frequency conversion circuit, which consists of S5, S6, S7, and S8 forming a half-bridge topology. S5 and S6 form the upper bridge arm, and S7 and S8 form the lower bridge arm. The auxiliary power supply 340 is connected to the midpoint of the half-bridge and the drain of the upper bridge arm S5, and / or, the auxiliary power supply 340 is connected to the midpoint of the half-bridge and the drain of the lower bridge arm S8. After the auxiliary power supply 340 is started, it can directly output driving energy to the gate circuit through the gate driver, which has fast driving response speed and strong control timeliness.

[0132] Secondly, the auxiliary power supply 340 connects the midpoint of the half-bridge and the midpoint of the first bridge arm.

[0133] For example, such as Figure 4 As shown, the auxiliary power supply 340 is connected to the midpoint of the half-bridge and the midpoint of the upper bridge arm (the common source node between S5 and S6), and / or, the auxiliary power supply 340 is connected to the midpoint of the half-bridge and the midpoint of the lower bridge arm (the common source node between S7 and S8). The auxiliary power supply 340 obtains the power supply potential from the midpoint of the half-bridge. The potential fluctuation of the midpoint of the half-bridge is small. Using this as a reference, the drive power supply is provided to the half-bridge switching transistors (S5-S8), which can avoid the potential offset between the drive signal and the main power circuit. The drive circuit is simpler and more reliable, and the stability and reliability of the auxiliary power supply 340 are effectively improved.

[0134] Third, the auxiliary power supply 340 is connected to the midpoint of the first bridge arm and the midpoint of the second bridge arm.

[0135] For example, such as Figure 5As shown, the auxiliary power supply 340 is connected to the midpoint of the upper bridge arm (the common source node between S5 and S6) and the midpoint of the lower bridge arm (the common source node between S7 and S8). This can maintain the symmetry of the potential at the midpoint of the two bridge arms, so that the common-mode interference is canceled out at the midpoint of the bridge arms, effectively reducing the common-mode voltage difference and thus reducing electromagnetic interference.

[0136] It should be noted that when the secondary-side conversion circuit 330 is not connected to the power supply and the primary-side full-bridge circuit 310 is connected to the power supply, the auxiliary power supply 340 can be powered by the power supply connected to the primary-side full-bridge circuit 310. For example, the auxiliary power supply 340 can be started by controlling the output pulse of the switching transistor of the primary-side full-bridge circuit 310 to charge it.

[0137] For example, the primary-side full-bridge circuit 310 is connected to the photovoltaic module, the secondary-side conversion circuit 330 is connected to the grid, and the grid-connected relay of the converter is not closed. The power provided by the photovoltaic module can supply power to the auxiliary power supply 340 to start the auxiliary power supply 340.

[0138] In actual operation, the primary-side full-bridge circuit 310 alternately enters the first and second stages, sending high-frequency PWM signals to charge the auxiliary power supply 340 located in the secondary-side conversion circuit 330 through the isolation unit 320. After establishing the auxiliary source voltage (e.g., 12V) of the auxiliary power supply 340, it drives the switching transistor of the secondary-side conversion circuit 330 to perform soft start and close the corresponding switch. For example, closing the grid-connected relay connects the secondary-side conversion circuit 330 to the power supply. If connected to the grid, the grid power is used to supply power to the auxiliary power supply 340, maintaining the energy of the auxiliary power supply 340 from dropping, so as to perform subsequent power control.

[0139] According to the converter provided in the embodiments of this application, the primary-side full-bridge circuit 310 is driven by the target switching signal to alternately switch in the first and second stages, adjusting the switching mode of the primary-side full-bridge circuit 310. The frequency set for the target switching signal is greater than the target resonant frequency of the converter. The switching frequency of the switching transistor controls the current direction. Before the current oscillation decays, the opposite voltage is excited, reducing the over-stress of the switching transistor in the primary-side full-bridge circuit 310 caused by the reverse recovery of the body diode. This reduces the voltage stress on the converter switching transistor during the auxiliary power source startup process, prevents excessive stress from damaging the device, improves the reliability of the converter's auxiliary power source startup process, and helps extend the service life of the converter.

[0140] This application also provides a power supply system including an isolated converter as described above.

[0141] The primary-side full-bridge circuit 310 of the converter can be connected to power sources such as photovoltaic modules and energy storage devices, while the secondary-side conversion circuit 330 of the converter can be connected to the power grid, generator, or load.

[0142] When the secondary-side conversion circuit 330 is not connected to the power supply and the primary-side full-bridge circuit 310 is connected to the power supply, the auxiliary power supply 340 can be powered by the power supply connected to the primary-side full-bridge circuit 310. For example, the auxiliary power supply 340 can be started by controlling the output pulse of the switching transistor of the primary-side full-bridge circuit 310 to charge it.

[0143] According to the power supply system provided in the embodiments of this application, the primary-side full-bridge circuit 310 is driven by the target switching signal to alternately switch in the first and second stages, adjusting the switching mode of the primary-side full-bridge circuit 310 of the converter. The frequency set for the target switching signal is greater than the target resonant frequency of the converter. The switching frequency of the switching transistor controls the current direction. Before the current oscillation decays, the opposite voltage is excited, reducing the over-stress of the switching transistor voltage in the primary-side full-bridge circuit 310 caused by the reverse recovery of the body diode. This reduces the voltage stress on the converter switching transistor during the auxiliary power supply startup process, prevents excessive stress from damaging the device, improves the reliability of the converter's auxiliary power supply startup process, and helps extend the service life of the converter.

[0144] In some embodiments, this application also provides an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor. When the program is executed by the processor, it implements the various processes of the above-described auxiliary source startup method embodiments and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0145] It should be noted that the electronic devices in the embodiments of this application include the mobile electronic devices and non-mobile electronic devices described above.

[0146] This application also provides a non-transitory computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the various processes of the above-described auxiliary source startup method embodiments and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0147] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0148] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described auxiliary source startup method.

[0149] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0150] This application embodiment also provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement the various processes of the above-described auxiliary source startup method embodiments and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0151] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0152] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0153] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the related technology, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0154] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0155] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0156] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An auxiliary source starting method, characterized by, The method is used for an isolated converter, which includes a primary-side full-bridge circuit and a secondary-side conversion circuit. The secondary-side conversion circuit has a resonant capacitor and a resonant inductor. The primary-side full-bridge circuit includes a first and a fourth switch arranged diagonally, as well as a second and a third switch arranged diagonally. The auxiliary power supply of the converter is located in the secondary-side conversion circuit. The method includes: When the primary-side full-bridge circuit is connected to a power source and the secondary-side conversion circuit is not connected to a power source, a target switching signal is output to the primary-side full-bridge circuit to drive the primary-side full-bridge circuit to alternately enter the first stage and the second stage to supply power to the auxiliary power source. Wherein, the target switching signal is a pulse width modulation signal, the frequency of the target switching signal is the switching frequency of the switching transistor in the primary-side full-bridge circuit, the frequency of the target switching signal is greater than the target resonant frequency of the converter, and the target resonant frequency is the resonant frequency of the resonant capacitor and the resonant inductor; In the first stage, the first switch and the fourth switch are turned on, and the second switch and the third switch are turned off; in the second stage, the second switch and the third switch are turned on, and the first switch and the fourth switch are turned off.

2. The method of auxiliary source starting of claim 1, wherein, The frequency of the target switching signal is positively correlated with the input voltage of the primary-side full-bridge circuit.

3. The method of auxiliary source starting of claim 2, wherein, The frequency of the target switching signal is a multiple of the target resonant frequency.

4. The method of auxiliary source starting of claim 3, wherein, The multiple relationship between the frequency of the target switching signal and the target resonant frequency is determined based on the auxiliary source setup time of the converter and the stress threshold of the secondary-side switching transistor.

5. The method of starting an auxiliary power source according to any one of claims 1 to 4, characterized by, The method further includes: Within the input voltage range of the primary-side full-bridge circuit, the frequency of the target switching signal is adjusted by linear interpolation, wherein the frequency of the target switching signal is determined based on the input voltage of the primary-side full-bridge circuit.

6. The method of auxiliary start-up of claim 5, wherein, The number of interpolation points for linear interpolation is determined based on the input voltage range.

7. An auxiliary source starting apparatus characterized by comprising: The device is used in an isolated converter, the converter including a primary-side full-bridge circuit and a secondary-side conversion circuit, the secondary-side conversion circuit having a resonant capacitor and a resonant inductor, the primary-side full-bridge circuit including a first and a fourth diagonally arranged switch, and a second and a third diagonally arranged switch; the auxiliary power supply of the converter is disposed in the secondary-side conversion circuit; the device includes: The processing module is used to output a target switching signal to the primary-side full-bridge circuit when the primary-side full-bridge circuit is connected to a power source and the secondary-side conversion circuit is not connected to a power source, thereby driving the primary-side full-bridge circuit to alternately enter the first stage and the second stage to supply power to the auxiliary power source. Wherein, the target switching signal is a pulse width modulation signal, the frequency of the target switching signal is the switching frequency of the switching transistor in the primary-side full-bridge circuit, the frequency of the target switching signal is greater than the target resonant frequency of the converter, and the target resonant frequency is the resonant frequency of the resonant capacitor and the resonant inductor; In the first stage, the first switch and the fourth switch are turned on, and the second switch and the third switch are turned off; in the second stage, the second switch and the third switch are turned on, and the first switch and the fourth switch are turned off.

8. A converter, characterized by The converter is an isolated type, and the converter includes: The primary-side full-bridge circuit and the secondary-side conversion circuit are provided. The secondary-side conversion circuit has a resonant capacitor and a resonant inductor. The primary-side full-bridge circuit includes a first switch and a fourth switch arranged diagonally, as well as a second switch and a third switch arranged diagonally. The auxiliary power supply of the converter is provided in the secondary-side conversion circuit. The auxiliary power supply starting device as described in claim 7 is used to control the primary-side full-bridge circuit to supply power to the auxiliary power supply.

9. The variator of claim 8, wherein, The secondary-side conversion circuit is a half-bridge frequency conversion circuit, which includes a first bridge arm and a second bridge arm connected to the midpoint of the half-bridge. The auxiliary power supply is connected to the midpoint of the half-bridge and the end point of the first bridge arm that is away from the midpoint of the half-bridge. Alternatively, the auxiliary power supply is connected to the midpoint of the half-bridge and the midpoint of the first bridge arm; Alternatively, the auxiliary power supply can be connected to the midpoint of the first bridge arm and the midpoint of the second bridge arm.

10. A power supply system characterized by comprising: include: The isolated converter as described in claim 8 or 9.

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