Power converter and control method and controller thereof

Abstract

The embodiment of the invention relates to the technical field of power electronics, in particular to a power converter, a control method thereof and a controller. The power converter comprises a primary side circuit, a secondary side circuit, a resonance circuit and a controller. The primary side circuit comprises half-bridge circuits corresponding to a first upper bridge arm switching tube and a first lower bridge arm switching tube, the secondary side circuit comprises a full-bridge circuit with a second bridge arm and a third bridge arm, and the duty ratio of the switching tubes of the full-bridge circuit is fixed to be 0.5. Under the condition that the voltage gain is smaller than or equal to 1, the controller regulates and controls the duty ratio of the first upper bridge arm switch tube according to the corresponding progressive increase relation between the voltage gain and the duty ratio of the first upper bridge arm switch tube, and the phase shift angle in the secondary side circuit is 0; and under the condition that the voltage gain is greater than or equal to 1, the current secondary side inner phase shift angle is regulated and controlled according to the corresponding decreasing relation between the reciprocal of the voltage gain and the secondary side inner phase shift angle, and the duty ratio of the first upper bridge arm switch tube is fixed to be 0.5. Therefore, the effective value of the resonance current is reduced to the minimum, and the conduction loss of the switch is reduced.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to power converters and their control methods and controllers. Background Technology

[0002] With the development of power electronics technology, power converters have been widely used in power conversion in fields such as new energy power generation, energy storage systems, and electric vehicles due to their advantages such as high efficiency and soft-switching characteristics. In application scenarios such as low-voltage residential energy storage systems, the low-voltage side switching transistors where the battery cells are located often need to withstand currents of up to several hundred amperes, resulting in significant conduction losses and seriously affecting system efficiency and reliability. To reduce conduction losses, traditional control strategies often employ methods such as external phase shifting or dual phase shifting control. However, these methods are difficult to simultaneously optimize the resonant current waveform over a wide voltage gain range, easily generating additional circulating currents, leading to an excessively high effective value of the resonant current, which in turn increases the conduction losses of the switching transistors. Summary of the Invention

[0003] The purpose of this application is to provide a power converter and its control method and controller, which can effectively reduce the conduction loss of the switching transistors in the power converter.

[0004] The objective of this application is achieved through the following technical solution: Firstly, embodiments of this application provide a power converter, which includes a primary-side circuit, a secondary-side circuit, a resonant circuit, and a controller; a first-side port of the primary-side circuit is connected to a first terminal of the resonant circuit, and a second terminal of the resonant circuit is connected to a first-side port of the secondary-side circuit; the primary-side circuit includes a half-bridge circuit, which includes a first bridge arm, comprising a first upper bridge arm switch and a first lower bridge arm switch; the secondary-side circuit includes a full-bridge circuit, comprising a second bridge arm and a third bridge arm, with the upper and lower bridge arm switches of the same bridge arm complementaryly conducting, and the switches of the full-bridge circuit being idle. The voltage gain is fixed at 0.5; the controller is configured to: when the voltage gain is less than or equal to 1, adjust the duty cycle of the first upper bridge arm switch according to the increasing relationship between the voltage gain and the duty cycle of the first upper bridge arm switch, and the phase shift angle of the secondary circuit is 0; when the voltage gain is greater than or equal to 1, adjust the current phase shift angle of the secondary side according to the decreasing relationship between the reciprocal of the voltage gain and the phase shift angle of the secondary side, and the duty cycle of the first upper bridge arm switch is fixed at 0.5; wherein, the voltage gain is determined by the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit, and the duty cycle of the first upper bridge arm switch ranges from 0 to 0.5.

[0005] In some embodiments, the power converter further includes a transformer, and the resonant circuit is connected to the primary circuit through the transformer, or the resonant circuit is connected to the secondary circuit through the transformer; when the power converter includes the transformer, the voltage gain is determined by the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit, and the primary-to-secondary turns ratio of the transformer.

[0006] In some embodiments, the second bridge arm includes a second upper bridge arm switch and a second lower bridge arm switch, and the third bridge arm includes a third upper bridge arm switch and a third lower bridge arm switch; the midpoint of the first bridge arm is electrically connected to the first terminal of the resonant circuit, the second terminal of the resonant circuit is electrically connected to the midpoint of the second bridge arm, and the lower node of the first bridge arm is electrically connected to the midpoint of the third bridge arm.

[0007] In some embodiments, the duty cycle of the first upper arm switch is adjusted according to the increasing relationship between the voltage gain and the duty cycle of the first upper arm switch, specifically including: obtaining a first calculation result by taking the arcsine of the square root of the difference between 1 and the voltage gain and dividing it by π; determining the duty cycle of the first upper arm switch based on the difference between 0.5 and the first calculation result; or, determining the duty cycle of the first upper arm switch by multiplying 0.5 by the voltage gain.

[0008] In some embodiments, adjusting the current secondary side inward phase shift angle according to the decreasing relationship between the reciprocal of the voltage gain and the secondary side inward phase shift angle specifically includes: determining the secondary side inward phase shift angle by multiplying the square root of the reciprocal of the voltage gain by the arccosine and 2; or, determining the secondary side inward phase shift angle by multiplying the difference between 1 and the reciprocal of the voltage gain by 3.

[0009] In some embodiments, when the voltage gain is less than or equal to 1, the controller is further configured to: synchronize the turn-on times of the first upper bridge arm switch, the second upper bridge arm switch, and the third lower bridge arm switch when power is transferred from the primary side circuit to the secondary side circuit; and synchronize the turn-off times of the first upper bridge arm switch, the second upper bridge arm switch, and the third lower bridge arm switch when power is transferred from the secondary side circuit to the primary side circuit.

[0010] In some embodiments, when the voltage gain is greater than or equal to 1, the controller is further configured to: when power is transferred from the primary circuit to the secondary circuit, control the turn-on time of the second upper bridge arm switch to be synchronized with that of the first upper bridge arm switch; and when power is transferred from the secondary circuit to the primary circuit, control the turn-off time of the third lower bridge arm switch to be synchronized with that of the first upper bridge arm switch.

[0011] Secondly, embodiments of this application provide a control method for a power converter, the power converter including a primary-side circuit, a secondary-side circuit, a resonant circuit, and a controller; a first-side port of the primary-side circuit is connected to a first terminal of the resonant circuit, and a second terminal of the resonant circuit is connected to a first-side port of the secondary-side circuit; the primary-side circuit includes a half-bridge circuit, the half-bridge circuit including a first bridge arm, the first bridge arm including a first upper bridge arm switch and a first lower bridge arm switch; the secondary-side circuit includes a full-bridge circuit, the full-bridge circuit including a second bridge arm and a third bridge arm, the upper and lower bridge arm switches of the same bridge arm are complementary in conduction, and the duty cycle of the switches in the full-bridge circuit is fixed at 0.5; the method includes... The controller determines the voltage gain based on the ratio of the secondary-side port voltage of the secondary circuit to the primary-side port voltage of the primary circuit. When the voltage gain is less than 1, the controller adjusts the duty cycle of the first upper bridge arm switch according to the increasing relationship between the voltage gain and the duty cycle of the first upper bridge arm switch, and the phase shift angle of the secondary circuit is 0. When the voltage gain is greater than 1, the controller adjusts the current phase shift angle of the secondary side according to the decreasing relationship between the reciprocal of the voltage gain and the phase shift angle of the secondary side, and the duty cycle of the first upper bridge arm switch is fixed at 0.5. The duty cycle of the first upper bridge arm switch ranges from 0 to 0.5.

[0012] In some embodiments, the power converter further includes a transformer, and the resonant circuit is connected to the primary circuit through the transformer, or the resonant circuit is connected to the secondary circuit through the transformer; the method further includes: when the power converter includes the transformer, the controller determines the voltage gain based on the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit, and the primary-to-secondary turns ratio of the transformer.

[0013] In some embodiments, the second bridge arm includes a second upper bridge arm switch and a second lower bridge arm switch, and the third bridge arm includes a third upper bridge arm switch and a third lower bridge arm switch; the midpoint of the first bridge arm is electrically connected to the first terminal of the resonant circuit, the second terminal of the resonant circuit is electrically connected to the midpoint of the second bridge arm, and the lower node of the first bridge arm is electrically connected to the midpoint of the third bridge arm.

[0014] In some embodiments, the duty cycle of the first upper arm switch is adjusted according to the increasing relationship between the voltage gain and the duty cycle of the first upper arm switch, specifically including: obtaining a first calculation result by taking the arcsine of the square root of the difference between 1 and the voltage gain and dividing it by π; determining the duty cycle of the first upper arm switch based on the difference between 0.5 and the first calculation result; or, determining the duty cycle of the first upper arm switch by multiplying 0.5 by the voltage gain.

[0015] In some embodiments, when the voltage gain is less than or equal to 1, the method includes: when power is transferred from the primary circuit to the secondary circuit, the controller synchronizes the turn-on times of the first upper bridge arm switch with those of the second upper bridge arm switch and the third lower bridge arm switch; when power is transferred from the secondary circuit to the primary circuit, the controller synchronizes the turn-off times of the first upper bridge arm switch with those of the second upper bridge arm switch and the third lower bridge arm switch.

[0016] In some embodiments, when the voltage gain is greater than or equal to 1, the method includes: when power is transferred from the primary circuit to the secondary circuit, the controller controls the turn-on time of the second upper bridge arm switch to be synchronized with that of the first upper bridge arm switch; when power is transferred from the secondary circuit to the primary circuit, the controller controls the turn-off time of the third lower bridge arm switch to be synchronized with that of the first upper bridge arm switch.

[0017] Thirdly, embodiments of this application provide a controller for executing the control method of the power converter described in any one of the second aspects above.

[0018] This application provides a power converter and its control method and controller. Addressing the problem that traditional control strategies generate additional circulating current, leading to a high effective value of the resonant current and increased conduction losses of the switching transistors, this application addresses the issue by adjusting the duty cycle of the first upper-arm switching transistor according to the increasing relationship between the voltage gain and the duty cycle of the first upper-arm switching transistor when the voltage gain is less than or equal to 1. This ensures that the phase of the resonant current is essentially the same as the phase of the secondary voltage phasor. Alternatively, when the voltage gain is greater than or equal to 1, the current secondary-side inward phase shift angle is adjusted according to the decreasing relationship between the reciprocal of the voltage gain and the inward phase shift angle of the secondary side, ensuring that the phase of the resonant current is essentially the same as the phase of the primary voltage phasor. Therefore, the amplitude of the resonant current phasor is minimized, reducing the effective value of the resonant current and lowering the switching losses of the power converter. Attached Figure Description

[0019] This application will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] Figure 1 This is a schematic diagram of a power converter provided in an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of a power converter including a transformer provided in an embodiment of this application.

[0022] Figure 3 This is a schematic diagram of the specific structure of a power converter provided in an embodiment of this application.

[0023] Figure 4 This is a schematic diagram of another power converter provided in the embodiments of this application.

[0024] Figure 5 This is a schematic diagram illustrating the relationship between voltage gain and the duty cycle of the first upper bridge arm switch provided in an embodiment of this application.

[0025] Figure 6 This is a schematic diagram illustrating the relationship between voltage gain and the secondary side inward phase shift angle provided in an embodiment of this application.

[0026] Figure 7 This is a schematic diagram of a driving waveform and a resonant circuit current waveform provided in an embodiment of this application.

[0027] Figure 8 This is a schematic diagram of another driving waveform and resonant circuit current waveform provided in the embodiments of this application.

[0028] Figure 9 This is another driving waveform and resonant circuit current waveform diagram provided in the embodiments of this application.

[0029] Figure 10 This is another driving waveform and resonant circuit current waveform diagram provided in the embodiments of this application.

[0030] Figure 11 This is a schematic flowchart of a control method for a power converter provided in an embodiment of this application. Detailed Implementation

[0031] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] In the description of the embodiments of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0033] In applications such as low-voltage residential energy storage systems, the low-voltage side switching transistors housing the battery cells often need to withstand currents of up to several hundred amperes, resulting in significant conduction losses and severely impacting system efficiency and reliability. To reduce conduction losses, traditional control strategies often employ external phase-shifting or dual phase-shifting control methods. However, these methods struggle to simultaneously optimize the resonant current waveform over a wide voltage gain range, easily generating additional circulating currents that lead to an excessively high effective value of the resonant current, thereby increasing switching conduction losses.

[0034] See Figure 1 , Figure 1 This is a schematic diagram of a power converter provided in an embodiment of this application.

[0035] This application provides a power converter, which includes a primary circuit, a secondary circuit, a resonant circuit, and a controller. The first port of the primary circuit is connected to the first end of the resonant circuit, and the second end of the resonant circuit is connected to the first port of the secondary circuit. The primary circuit includes a half-bridge circuit, which includes a first bridge arm, a first upper bridge arm switch, and a first lower bridge arm switch. The secondary circuit includes a full-bridge circuit, which includes a second bridge arm and a third bridge arm. The upper and lower bridge arm switches of the same bridge arm are complementary in conduction, and the duty cycle of the switches in the full-bridge circuit is fixed at 0.5.

[0036] The controller is configured to: when the voltage gain is less than or equal to 1, adjust the duty cycle of the first upper bridge arm switch according to the increasing relationship between the voltage gain and the duty cycle of the first upper bridge arm switch, and the phase shift angle in the secondary circuit is 0; when the voltage gain is greater than or equal to 1, adjust the current phase shift angle in the secondary side according to the decreasing relationship between the reciprocal of the voltage gain and the phase shift angle in the secondary side, and the duty cycle of the first upper bridge arm switch is fixed at 0.5.

[0037] The voltage gain is determined by the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit, and the duty cycle of the first upper bridge arm switch ranges from 0 to 0.5.

[0038] In some embodiments, the primary-side circuit can be used to convert the input DC voltage V i It is converted into a high-frequency AC square wave voltage. The secondary circuit can be used to convert the incoming high-frequency AC power back into DC power.V o The power converter supplies power to the load. In a power converter, the voltage waveform across the resonant circuit is changed by controlling the driving waveform of the primary and secondary switching transistors, thereby controlling the resonant current waveform on the resonant circuit. The resonant circuit can include an LC resonant circuit or an LLC resonant circuit. For example, in the case where the resonant circuit includes an LC resonant circuit, the resonant circuit can include a resonant inductor L connected in series. r and resonant capacitor C r .

[0039] In some embodiments, the switching transistors included in the primary and secondary circuits may be, for example, metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), silicon carbide (SiCMOSFETs), and gallium nitride (GaN HEMTs).

[0040] In some embodiments, the controller may be a circuit in a microcontroller unit (MCU) or a circuit in a digital signal processor (DSP), for example, it may be used to drive the switching transistors in the primary and secondary circuits to turn on and off.

[0041] In some embodiments, the power transfer of the resonant circuit can be used This means that the phase of the resonant current is in phase with the phase of the voltage phasor. , When the resonant current reaches its maximum value, I can reach its minimum value, meaning the effective value of the resonant current can be minimized. Based on this, the phase of the resonant current can be made essentially the same as the phase of the secondary voltage phasor by adjusting the duty cycle of the first upper arm switch in the primary circuit, or by adjusting the inward phase shift angle of the secondary switch in the secondary circuit. This reduces the effective value of the resonant current and lowers the switching losses of the power converter.

[0042] For example, the logic for adjusting the duty cycle of the first upper arm switch can include: when the duty cycle of the first upper arm switch is 0.5, the primary circuit will generate a standard 50% square wave. At this time, the phase of the resonant current is determined by both the primary and secondary voltages, and their phases usually have a large difference, leading to severe circulating current. Therefore, when the voltage gain is less than 1, by reducing the duty cycle of the first upper arm switch, the primary circuit will generate a voltage waveform with a narrower pulse. This narrow pulse means that the fundamental component of the primary voltage is shorter. The resonant circuit is most sensitive to the fundamental frequency, specifically in that the waveform and phase of the resonant current are mainly determined by the fundamental components of the primary and secondary voltages. By controlling the width of the narrow pulse and combining it with the control method of synchronizing the turn-on or turn-off times of the switch, the fundamental component of the voltage phasor at both ends of the resonant circuit is made orthogonal to the fundamental component of the secondary voltage phasor, while the fundamental component of the resonant current phasor lags behind the voltage phasor at both ends of the resonant circuit by 90 degrees. Therefore, the phase of the resonant current can be controlled to be completely aligned with the phase of the secondary voltage. At this point, the effective value of the resonant current is minimized, effectively reducing the switching losses of the power converter. Therefore, the phase of its fundamental component is controlled by changing the duty cycle of the primary voltage waveform. Utilizing the characteristic that the current phase follows the voltage phase at the resonant point, the phase of the fundamental resonant current is indirectly controlled, ensuring it remains consistent with the fixed phase of the secondary voltage fundamental, thereby achieving... Approaching 1, it ultimately minimizes the effective value of the resonant current.

[0043] Thus, by adjusting the duty cycle of the first upper bridge arm switch in the primary circuit of the power converter or the phase shift angle of the secondary circuit, the resonant current of the resonant circuit is made to be in phase with the voltage across the two ends, thereby reducing the resonant current and thus reducing the conduction loss of the switch.

[0044] In some embodiments, the larger the absolute value of the difference between the voltage gain and 1, the higher the degree of mismatch between the primary and secondary voltage amplitudes.

[0045] In some embodiments, when the voltage gain is less than 1, the smaller the voltage gain, the higher the primary voltage amplitude will be compared to the secondary voltage amplitude when referred to the same side. In this case, a smaller duty cycle is needed to reduce the primary voltage amplitude. Therefore, the voltage gain and duty cycle have an increasing relationship. Based on this, according to the increasing relationship between voltage gain and the duty cycle of the first upper-side switch, the width of the primary voltage square wave is changed by adjusting the current duty cycle of the switch in the primary circuit, making it a square wave with a width less than 50%. This reduces the fundamental amplitude of the primary voltage, matching it with the lower secondary voltage, thereby reducing the voltage difference across the resonant circuit and minimizing the resonant current, thus reducing conduction losses. Furthermore, during the adjustment process, the duty cycle of the first upper-side switch ranges from 0 to 0.5, and the phase shift angle within the secondary circuit is 0.

[0046] In some embodiments, when the voltage gain is greater than 1, the larger the voltage gain, the higher the amplitude of the secondary voltage after conversion to the same side compared to the primary voltage. In this case, a larger secondary phase shift angle is needed to reduce the equivalent secondary voltage amplitude. Therefore, the reciprocal of the voltage gain has a decreasing relationship with the secondary phase shift angle. Based on this, by adjusting the current secondary phase shift angle of the switching transistor in the secondary circuit, the width of the high and negative levels of the secondary voltage square wave is changed, and the amplitude and phase of the three-level square wave are controlled, thereby reducing the fundamental amplitude of the secondary voltage to match the lower primary voltage. This reduces the voltage difference across the resonant circuit, minimizing the resonant current and reducing conduction losses. During this process, the controller controls the first upper bridge arm switching transistor to operate with a fixed duty cycle of 0.5.

[0047] In some embodiments, the duty cycle of the full-bridge circuit switching transistors is fixed at 0.5. Specifically, this can be reflected in the controller generating a fixed set of drive signals for the secondary circuit. The second and third bridge arms are given drive signals with a duty cycle of 0.5, and the upper and lower bridge arm switching transistors of the same bridge arm are complementary in conduction.

[0048] Since there is no internal phase shift in the two arms of the secondary circuit, the secondary circuit does not perform internal phase shift control in this mode. That is to say, the internal phase shift angle of the secondary circuit is 0, and its output voltage is a standard 0.5 duty cycle square wave.

[0049] In some embodiments, the duty cycle of the first upper bridge arm switch is fixed at 0.5, specifically manifested in the controller generating a fixed drive signal for the primary circuit. The duty cycle of the first upper bridge arm switch is assigned a fixed drive signal with a duty cycle of 0.5. The duty cycle of the first lower bridge arm switch is assigned a drive signal with a duty cycle of 0.5 that is completely complementary to the first switch S1.

[0050] It is understandable that in practical applications, a dead time needs to be inserted between the upper and lower transistors of the same bridge arm to prevent shoot-through short circuits. The dead time is typically tens to hundreds of nanoseconds, relative to the switching cycle T. s This is negligible and not shown in the diagram. Therefore, due to the existence of the dead time, the duty cycle of the first upper bridge arm switch (and / or the first lower bridge arm switch) will have a certain error compared to 0.5. Similarly, the duty cycle of the full-bridge circuit switches will also have a certain error compared to 0.5. For ease of understanding, this application will describe the duty cycle as 0.5.

[0051] In some embodiments, the power converter may further include a transformer, through which the resonant circuit is connected to the primary circuit, or through a transformer, the resonant circuit is connected to the secondary circuit. When the power converter includes a transformer, the voltage gain is determined by the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit, and the primary-to-secondary turns ratio of the transformer.

[0052] The converter can be used to achieve electrical isolation between the primary and secondary circuits. When the power converter includes a transformer, its structural diagram can be shown as follows: Figure 2 As shown, the primary-to-secondary turns ratio of the transformer can be n:1.

[0053] In some embodiments, the second bridge arm includes a second upper bridge arm switch and a second lower bridge arm switch, and the third bridge arm includes a third upper bridge arm switch and a third lower bridge arm switch; the midpoint of the first bridge arm is electrically connected to the first end of the resonant circuit, the second end of the resonant circuit is electrically connected to the midpoint of the second bridge arm, and the lower node of the first bridge arm is electrically connected to the midpoint of the third bridge arm.

[0054] In some embodiments, where the power converter does not include a transformer, such as Figure 3 The diagram shows a specific structure of a power converter. The midpoint of the first bridge arm can be connected to the first end of the resonant circuit, the second end of the resonant circuit can be connected to the midpoint of the second bridge arm, and the lower node of the first bridge arm can be connected to the midpoint of the third bridge arm.

[0055] In some embodiments, when the power converter includes a transformer, the resonant circuit can be located on either the primary or secondary side of the transformer. Taking the resonant circuit device on the primary side of the transformer as an example, such as... Figure 4 The diagram shows another power converter with a specific structure. The midpoint of the first bridge arm is connected to the first end of the resonant circuit, the second end of the resonant circuit is connected to the first end of the primary winding of the transformer, and the second end of the primary winding of the transformer is connected to the node of the first lower bridge arm. The midpoint of the second bridge arm is connected to the first end of the secondary winding of the transformer, and the midpoint of the third bridge arm is connected to the second end of the secondary winding of the transformer.

[0056] It is understood that the control method mentioned in the embodiments of this application can be applied to the case where the power converter does not include a transformer, or to the case where the power converter includes a transformer. For ease of understanding, the embodiments of this application will not describe these two cases separately.

[0057] In some embodiments, in the primary-side circuit, the first upper bridge arm switch may include, for example, a first switch S1, and the first lower bridge arm switch may include, for example, a second switch S2. The primary-side circuit can generate a DC voltage at the input by controlling the first switch S1 and the second switch S2 to conduct complementaryly with a 0.5 duty cycle, at the midpoint (point A) of the connection between the two switches. V i Voltage waveform that jumps between 0 and 0.

[0058] In some embodiments, in the secondary-side circuit, the second upper bridge arm switch may include a third switch Q1, the second lower bridge arm switch may include a fourth switch Q2, the third upper bridge arm switch may include a fifth switch Q3, and the third lower bridge arm switch may include a sixth switch Q4. The controller can perform synchronous rectification by controlling the conduction sequence of the four switches. For example, turning on the third switch Q1 and the sixth switch Q4 allows current to flow through the load; when the voltage direction reverses, turning on the fourth switch Q2 and the fifth switch Q3 ensures that the direction of the current flowing through the load remains unchanged.

[0059] In some embodiments, the duty cycle of the first upper arm switch is adjusted according to the increasing relationship between the voltage gain and the duty cycle of the first upper arm switch. Specifically, this may include: obtaining a first calculation result by taking the arcsine of the square root of the difference between 1 and the voltage gain and dividing it by π; and determining the duty cycle of the first upper arm switch based on the difference between 0.5 and the first calculation result; or, determining the duty cycle of the first upper arm switch by multiplying 0.5 by the voltage gain.

[0060] To address this, taking the adjustment of the duty cycle of the first upper bridge arm switch as an example, the controller can adjust the primary-side port voltage based on real-time sampling. V i and secondary port voltage V o The voltage gain M is calculated. Then, based on the increasing relationship between the voltage gain M and the duty cycle of the first upper bridge arm switch, the current duty cycle of the first upper bridge arm switch S1 is adjusted to determine the duty cycle D1 of the first upper bridge arm switch. Here, the duty cycle D1 of the first upper bridge arm switch can represent the duty cycle of the first upper bridge arm switch S1 in one switching cycle T. s The ratio of the internal conduction time to the entire switching cycle, the duty cycle D1 of the first upper bridge arm switch tube ranges from 0 to 0.5.

[0061] In some embodiments, the arcsine of the square root of the difference between 1 and the voltage gain is divided by π to obtain a first calculation result. The duty cycle of the first upper bridge arm switch is determined based on the difference between 0.5 and the first calculation result, that is, according to the formula... The duty cycle D1 of the first upper bridge arm switch was determined. The relationship between the duty cycle D1 of the first upper bridge arm switch and the voltage gain M can be shown in the curve below. Figure 5 As shown, the duty cycle D1 of the first upper bridge arm switch exhibits a monotonically increasing relationship with the voltage gain M. The closer the voltage gain M is to 0, the closer the duty cycle D1 of the first upper bridge arm switch is to 0. The closer the voltage gain M is to 1, the closer the duty cycle D1 of the first upper bridge arm switch is to 0.5.

[0062] In other embodiments, the duty cycle of the first upper arm switch can also be determined by multiplying 0.5 by the voltage gain. That is, the duty cycle D1 of the first upper arm switch can be determined according to the linear approximation formula D1=0.5M. To balance control stability and engineering practice, the actual value of the duty cycle D1 of the first upper arm switch can have an error tolerance of ±0.05 around the calculated value.

[0063] Furthermore, based on the duty cycle D1 of the first upper bridge arm switch, the controller can generate a drive signal for the primary circuit. For the first switch S1, the controller can generate a pulse width modulation (PWM) wave with a duty cycle of D1 to drive the first switch S1 to turn on and off. For the second switch S2, the controller can generate a PWM wave complementary to the drive signal of the first switch S1 to drive the second switch S2 to turn on and off. That is, when the first switch S1 is on, the second switch S2 is off, and when the first switch S1 is off, the second switch S2 is on.

[0064] It can be understood that driving the primary circuit with a determined first upper bridge arm switch duty cycle is equivalent to driving the primary circuit with a determined first lower bridge arm switch duty cycle, and the duty cycle of the first lower bridge arm switch has a gradually decreasing relationship with the voltage gain M.

[0065] In some embodiments, the current secondary side inward phase shift angle is adjusted according to the decreasing relationship between the reciprocal of the voltage gain and the secondary side inward phase shift angle. Specifically, this may include: determining the secondary side inward phase shift angle by multiplying the product of the arccosine of the square root of the reciprocal of the voltage gain and 2; or, determining the secondary side inward phase shift angle by multiplying the product of the difference between 1 and the reciprocal of the voltage gain and 3.

[0066] To address this, taking the control from the perspective of the sixth switch Q4 as an example, the controller can adjust the primary-side port voltage based on real-time sampling. V i and secondary port voltage V oCalculate the voltage gain M, and then calculate its reciprocal 1 / M. Subsequently, the controller can adjust the current secondary side internal phase shift angle according to the decreasing relationship between the secondary side internal phase shift angle and the reciprocal of the voltage gain, thus obtaining the secondary side internal phase shift angle θ. In this case, the secondary side internal phase shift angle θ can be expressed as the phase angle of the sixth switch Q4 lagging behind the third switch Q1 in the secondary circuit, and the value of θ ranges from 0 to π.

[0067] In some embodiments, the secondary phase shift angle can be determined by multiplying the inverse square root of the voltage gain by its arccosine and then by 2. That is, according to the formula... The secondary side inward phase shift angle θ is obtained. The schematic diagram of the relationship between the secondary side inward phase shift angle θ and the voltage gain M can be shown as follows: Figure 6 As shown, the secondary side inward phase shift angle θ exhibits a monotonically decreasing relationship with the reciprocal of the voltage gain 1 / M. The closer 1 / M is to 0, the closer the secondary side inward phase shift angle θ is to π. The closer the reciprocal of the voltage gain 1 / M is to 1, the closer the secondary side inward phase shift angle θ is to 0.

[0068] In other embodiments, the secondary side inward phase shift angle can also be determined by multiplying the difference between 1 and the reciprocal of the voltage gain by 3, that is, according to the approximate formula. This yields the secondary side inward phase shift angle θ. In some practical applications, to balance control stability and engineering practice, the actual value of the secondary side inward phase shift angle θ can have an error tolerance of ±0.05 around the calculated value.

[0069] Furthermore, based on the secondary side's internal phase shift angle θ, the controller can generate drive signals for the secondary circuit. The internal phase shift is achieved by introducing a phase difference between the drive signals of the second and third bridge arms. For the second bridge arm, the controller can generate a set of standard complementary PWM signals with a duty cycle of 0.5 to drive the third switch Q1 and the fourth switch Q2. For the third bridge arm, the controller can generate another set of complementary PWM signals with a duty cycle of 0.5 to drive the fifth switch Q3 and the sixth switch Q4.

[0070] Specifically, the phase of the drive signal of the third bridge arm lags behind the drive signal of the second bridge arm, and the phase lag angle is the secondary side inward phase shift angle θ. In particular, the rising edge of the drive signal of the fifth switch Q3 lags behind the rising edge of the drive signal of the third switch Q1 by a phase angle θ. Similarly, a preset dead time must be inserted between all complementary drive signals.

[0071] It is understood that in the process of driving the secondary circuit with the phase shift angle θ of the secondary side of the sixth switch Q4, it is also equivalent to driving the secondary circuit with the phase shift angle of the secondary side of other switches in the secondary circuit. Therefore, the process of using other switches in the secondary circuit as switches in the above embodiment can be referred to the above embodiment, and will not be elaborated further here.

[0072] It is understood that, in the above embodiments, when the power converter includes a transformer, the voltage gain M can be based on the formula In the case where the power converter does not include a transformer, the voltage gain M can be obtained based on the formula. get.

[0073] In some embodiments, when the voltage gain is less than or equal to 1, the controller may also be configured to: synchronize the turn-on times of the first upper bridge arm switch with those of the second upper bridge arm switch and the third lower bridge arm switch when power is transferred from the primary circuit to the secondary circuit; and synchronize the turn-off times of the first upper bridge arm switch with those of the second upper bridge arm switch and the third lower bridge arm switch when power is transferred from the secondary circuit to the primary circuit.

[0074] In some embodiments, to ensure efficient energy transfer and minimize circulating current, the drive signals of the primary and secondary sides need to be time-aligned. For example... Figure 7 and Figure 8 The diagram shows a driving waveform and a schematic diagram of the resonant circuit current waveform.

[0075] exist Figure 7 In the case of power transfer from the primary circuit to the secondary circuit (forward power transfer), the controller can precisely align the rising edge (turn-on moment) of the drive signal of the first switch S1 with the rising edge of the drive signal of the third switch Q1 (and the sixth switch Q4). This alignment method ensures that the rising edge of the primary voltage square wave is synchronized with the rising edge of the secondary voltage square wave.

[0076] exist Figure 8 In the case of power transfer from the secondary circuit to the primary circuit (reverse power transfer), the timing alignment needs to be adjusted. At this time, the controller can precisely align the falling edge (turn-off moment) of the drive signal of the first switch S1 with the falling edge of the drive signal of the third switch Q1 (and the sixth switch Q4).

[0077] Through the above implementation method, when the voltage gain is less than 1, by adjusting the duty cycle of the first upper bridge arm switch and fixing the working state of the secondary circuit, the resonant current waveform is optimized, which helps to reduce the switching conduction loss.

[0078] The synchronization reference between the primary and secondary circuits needs to be adjusted according to the characteristics of the internal phase-shift control, such as... Figure 9 and Figure 10 The diagram shows another driving waveform and a schematic diagram of the resonant circuit current waveform.

[0079] In some embodiments, when the voltage gain is greater than or equal to 1, the controller is further configured to: synchronize the turn-on time of the second upper bridge arm switch with that of the first upper bridge arm switch when power is transferred from the primary circuit to the secondary circuit; and synchronize the turn-off time of the third lower bridge arm switch with that of the first upper bridge arm switch when power is transferred from the secondary circuit to the primary circuit.

[0080] exist Figure 9 As shown, in the case of power transfer from the primary circuit to the secondary circuit (forward power transfer), the controller can precisely align the rising edge of the drive signal of the first switch S1 with the rising edge of the drive signal of the third switch Q1. Using this as a time reference, the drive signal of the second bridge arm in the secondary circuit is then delayed by an angle. This alignment method ensures that the starting edge of the primary side voltage square wave is synchronized with the voltage edge of the secondary side reference bridge arm, establishing a correct starting point for power flow under internal phase-shift control.

[0081] exist Figure 10 As shown, in the case of power transfer from the secondary circuit to the primary circuit (reverse power transfer), the timing alignment changes. In this case, the controller can align the falling edge of the drive signal for the first switch S1 with the rising edge of the drive signal for the sixth switch Q4 (or equivalently, with the falling edge of the fifth switch Q3). This alignment is more suitable for the phase characteristics of the resonant current during reverse power transfer, helping to maintain soft switching and optimize performance.

[0082] Through the above implementation method, when the voltage gain is greater than 1, by adjusting the phase shift angle of the secondary side and fixing the working state of the primary side, the net voltage applied to both ends of the resonant circuit is effectively controlled, thereby optimizing the resonant current waveform and realizing high-efficiency energy transfer under high voltage gain conditions.

[0083] See Figure 11 , Figure 11 This is a schematic flowchart of a control method for a power converter provided in an embodiment of this application.

[0084] This application provides a control method for a power converter. The power converter includes a primary circuit, a secondary circuit, a resonant circuit, and a controller. The first port of the primary circuit is connected to the first end of the resonant circuit, and the second end of the resonant circuit is connected to the first port of the secondary circuit. The primary circuit includes a half-bridge circuit, which includes a first bridge arm, a first upper bridge arm switch, and a first lower bridge arm switch. The secondary circuit includes a full-bridge circuit, which includes a second bridge arm and a third bridge arm. The upper and lower bridge arm switches of the same bridge arm are complementary in conduction, and the duty cycle of the switches in the full-bridge circuit is fixed at 0.5.

[0085] The method includes steps S101-S102: S101: The controller determines the voltage gain based on the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit.

[0086] S102: When the voltage gain is less than 1, the controller adjusts the duty cycle of the first upper bridge arm switch according to the increasing relationship between the voltage gain and the duty cycle of the first upper bridge arm switch, and the phase shift angle in the secondary circuit is 0.

[0087] S103: When the voltage gain is greater than 1, the controller adjusts the current secondary side internal phase shift angle according to the decreasing relationship between the reciprocal of the voltage gain and the secondary side internal phase shift angle. The duty cycle of the first upper bridge arm switch is fixed at 0.5.

[0088] The duty cycle of the first upper bridge arm switch ranges from 0 to 0.5.

[0089] In some embodiments, the power converter further includes a transformer, and the resonant circuit is connected to the primary circuit through the transformer, or the resonant circuit is connected to the secondary circuit through the transformer; the method further includes: when the power converter includes a transformer, the controller determines the voltage gain based on the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit, and the primary-to-secondary turns ratio of the transformer.

[0090] In some embodiments, the second bridge arm includes a second upper bridge arm switch and a second lower bridge arm switch, and the third bridge arm includes a third upper bridge arm switch and a third lower bridge arm switch; the midpoint of the first bridge arm is electrically connected to the first end of the resonant circuit, the second end of the resonant circuit is electrically connected to the midpoint of the second bridge arm, and the lower node of the first bridge arm is electrically connected to the midpoint of the third bridge arm.

[0091] In some embodiments, the duty cycle of the first upper arm switch is adjusted according to the increasing relationship between the voltage gain and the duty cycle of the first upper arm switch. Specifically, this includes: obtaining a first calculation result by taking the arcsine of the square root of the difference between 1 and the voltage gain and dividing it by π; and determining the duty cycle of the first upper arm switch based on the difference between 0.5 and the first calculation result; or, determining the duty cycle of the first upper arm switch by multiplying 0.5 by the voltage gain.

[0092] In some embodiments, the current secondary side inward phase shift angle is adjusted according to the decreasing relationship between the reciprocal of the voltage gain and the secondary side inward phase shift angle. Specifically, this includes: determining the secondary side inward phase shift angle by multiplying the product of the arccosine of the square root of the reciprocal of the voltage gain and 2; or, determining the secondary side inward phase shift angle by multiplying the product of the difference between 1 and the reciprocal of the voltage gain and 3.

[0093] In some embodiments, when the voltage gain is less than or equal to 1, the method includes: when power is transferred from the primary circuit to the secondary circuit, the controller controls the turn-on time of the first upper bridge arm switch to be synchronized with that of the second upper bridge arm switch and the third lower bridge arm switch; when power is transferred from the secondary circuit to the primary circuit, the controller controls the turn-off time of the first upper bridge arm switch to be synchronized with that of the second upper bridge arm switch and the third lower bridge arm switch.

[0094] In some embodiments, when the voltage gain is greater than or equal to 1, the method includes: when power is transferred from the primary circuit to the secondary circuit, the controller controls the turn-on time of the second upper bridge arm switch to be synchronized with that of the first upper bridge arm switch; when power is transferred from the secondary circuit to the primary circuit, the controller controls the turn-off time of the third lower bridge arm switch to be synchronized with that of the first upper bridge arm switch.

[0095] This application provides a controller for executing the control method of the power converter mentioned in any of the above embodiments.

[0096] It is understood that the specific examples in this application are only intended to help those skilled in the art better understand the implementation of this application, and are not intended to limit the scope of protection of this application.

[0097] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of this application.

[0098] It is understood that the various implementation methods described in this application can be implemented individually or in combination, and this application does not limit them.

[0099] Unless otherwise stated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "one or more" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0100] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0101] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes and beneficial effects of the embodiments described above can be referred to the corresponding processes and beneficial effects in other embodiments, and will not be repeated here.

[0102] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0103] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the technical solution in this application, depending on actual needs.

[0104] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0105] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, essentially, or the part that contributes to the prior art, or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0106] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A power converter, characterized in that, The power converter includes a primary-side circuit, a secondary-side circuit, a resonant circuit, and a controller. A first port of the primary-side circuit is connected to a first terminal of the resonant circuit, and a second terminal of the resonant circuit is connected to a first port of the secondary-side circuit. The primary-side circuit includes a half-bridge circuit, which includes a first bridge arm and a first upper bridge arm switch. The secondary-side circuit includes a full-bridge circuit, which includes a second bridge arm and a third bridge arm. The upper and lower bridge arm switches of the same bridge arm are complementary in conduction. The duty cycle of the switches in the full-bridge circuit is fixed at 0.

5. The controller is configured to: when the voltage gain is less than or equal to 1, adjust the duty cycle of the first upper bridge arm switch according to the increasing relationship between the voltage gain and the duty cycle of the first upper bridge arm switch, and the phase shift angle of the secondary circuit is 0; when the voltage gain is greater than or equal to 1, adjust the current phase shift angle of the secondary side according to the decreasing relationship between the reciprocal of the voltage gain and the phase shift angle of the secondary side, and the duty cycle of the first upper bridge arm switch is fixed at 0.

5. The voltage gain is determined by the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit, and the duty cycle of the first upper bridge arm switch ranges from 0 to 0.

5.

2. The power converter according to claim 1, characterized in that, The power converter further includes a transformer, and the resonant circuit is connected to the primary circuit through the transformer, or the resonant circuit is connected to the secondary circuit through the transformer; In the case where the power converter includes the transformer, the voltage gain is determined by the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit, and the primary-to-secondary turns ratio of the transformer.

3. The power converter according to claim 1 or 2, characterized in that, The second bridge arm includes a second upper bridge arm switch and a second lower bridge arm switch, and the third bridge arm includes a third upper bridge arm switch and a third lower bridge arm switch. The midpoint of the first bridge arm is electrically connected to the first end of the resonant circuit, the second end of the resonant circuit is electrically connected to the midpoint of the second bridge arm, and the lower node of the first bridge arm is electrically connected to the midpoint of the third bridge arm.

4. The power converter according to claim 1, characterized in that, The duty cycle of the first upper bridge arm switch is adjusted according to the increasing relationship between the voltage gain and the duty cycle of the first upper bridge arm switch, specifically including: The arcsine of the square root of the difference between 1 and the voltage gain is divided by π to obtain the first calculation result. The duty cycle of the first upper bridge arm switch is determined based on the difference between 0.5 and the first calculation result; or, The duty cycle of the first upper bridge arm switch is determined by the product of 0.5 and the voltage gain.

5. The power converter according to claim 1, characterized in that, The current secondary side inward phase shift angle is adjusted according to the decreasing relationship between the reciprocal of the voltage gain and the secondary side inward phase shift angle, specifically including: The secondary side inward phase shift angle is determined by multiplying the product of the inverse square root of the voltage gain (arccosine) and 2; or, The secondary side inward phase shift angle is determined by multiplying the difference between 1 and the reciprocal of the voltage gain with 3.

6. The power converter according to claim 3, characterized in that, When the voltage gain is less than or equal to 1, the controller is also configured to: When power is transferred from the primary circuit to the secondary circuit, the conduction times of the first upper bridge arm switch, the second upper bridge arm switch, and the third lower bridge arm switch are synchronized. When power is transferred from the secondary circuit to the primary circuit, the turn-off times of the first upper bridge arm switch, the second upper bridge arm switch, and the third lower bridge arm switch are synchronized.

7. The power converter according to claim 3, characterized in that, When the voltage gain is greater than or equal to 1, the controller is also configured to: When power is transferred from the primary circuit to the secondary circuit, the conduction time of the second upper bridge arm switch is synchronized with that of the first upper bridge arm switch. When power is transferred from the secondary circuit to the primary circuit, the turn-off time of the third lower bridge arm switch is synchronized with that of the first upper bridge arm switch.

8. A control method for a power converter, characterized in that, The power converter includes a primary-side circuit, a secondary-side circuit, a resonant circuit, and a controller. A first port of the primary-side circuit is connected to a first terminal of the resonant circuit, and a second terminal of the resonant circuit is connected to a first port of the secondary-side circuit. The primary-side circuit includes a half-bridge circuit, which includes a first bridge arm and a first upper bridge arm switch. The secondary-side circuit includes a full-bridge circuit, which includes a second bridge arm and a third bridge arm. The upper and lower bridge arm switches of the same bridge arm are complementary in conduction. The duty cycle of the switches in the full-bridge circuit is fixed at 0.

5. The method includes: The controller determines the voltage gain based on the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit. When the voltage gain is less than 1, the controller adjusts the duty cycle of the first upper bridge arm switch according to the increasing relationship between the voltage gain and the duty cycle of the first upper bridge arm switch, and the phase shift angle in the secondary circuit is 0. When the voltage gain is greater than 1, the controller adjusts the current secondary side internal phase shift angle according to the decreasing relationship between the reciprocal of the voltage gain and the secondary side internal phase shift angle, and the duty cycle of the first upper bridge arm switch is fixed at 0.

5. The duty cycle of the first upper bridge arm switch is in the range of 0 to 0.

5.

9. The control method for the power converter according to claim 8, characterized in that, The power converter further includes a transformer, and the resonant circuit is connected to the primary circuit through the transformer, or the resonant circuit is connected to the secondary circuit through the transformer; the method further includes: When the power converter includes the transformer, the controller determines the voltage gain based on the ratio of the secondary port voltage of the secondary circuit to the primary port voltage of the primary circuit, and the primary-to-secondary turns ratio of the transformer.

10. The control method for the power converter according to claim 8 or 9, characterized in that, The second bridge arm includes a second upper bridge arm switch and a second lower bridge arm switch, and the third bridge arm includes a third upper bridge arm switch and a third lower bridge arm switch. The midpoint of the first bridge arm is electrically connected to the first end of the resonant circuit, the second end of the resonant circuit is electrically connected to the midpoint of the second bridge arm, and the lower node of the first bridge arm is electrically connected to the midpoint of the third bridge arm.

11. The control method for the power converter according to claim 8, characterized in that, The duty cycle of the first upper bridge arm switch is adjusted according to the increasing relationship between the voltage gain and the duty cycle of the first upper bridge arm switch, specifically including: The arcsine of the square root of the difference between 1 and the voltage gain is divided by π to obtain the first calculation result. The duty cycle of the first upper bridge arm switch is determined based on the difference between 0.5 and the first calculation result; or, The duty cycle of the first upper bridge arm switch is determined by the product of 0.5 and the voltage gain.

12. The control method for the power converter according to claim 8, characterized in that, The current secondary side inward phase shift angle is adjusted according to the decreasing relationship between the reciprocal of the voltage gain and the secondary side inward phase shift angle, specifically including: The secondary side inward phase shift angle is determined by multiplying the product of the inverse square root of the voltage gain (arccosine) and 2; or, The secondary side inward phase shift angle is determined by multiplying the difference between 1 and the reciprocal of the voltage gain with 3.

13. The control method for the power converter according to claim 10, characterized in that, When the voltage gain is less than or equal to 1, the method includes: When power is transferred from the primary circuit to the secondary circuit, the controller controls the first upper bridge arm switch to be synchronized with the second upper bridge arm switch and the third lower bridge arm switch. When power is transferred from the secondary circuit to the primary circuit, the controller synchronizes the turn-off times of the first upper bridge arm switch with those of the second upper bridge arm switch and the third lower bridge arm switch.

14. The control method for the power converter according to claim 10, characterized in that, When the voltage gain is greater than or equal to 1, the method includes: When power is transferred from the primary circuit to the secondary circuit, the controller controls the second upper arm switch to be synchronized with the first upper arm switch in terms of their turn-on timing. When power is transferred from the secondary circuit to the primary circuit, the controller synchronizes the turn-off time of the third lower bridge arm switch with that of the first upper bridge arm switch.

15. A controller, characterized in that, The controller is used to execute the control method of the power converter according to any one of claims 8-14.

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