Power conversion circuit and power conversion device

Abstract

The invention discloses a power conversion circuit and a power conversion device.The power conversion circuit comprises a capacitor bridge arm, a plurality of bidirectional bridge arms, a plurality of resonance modules and a plurality of rectification modules, the capacitor bridge arm, a bidirectional switch bridge arm, the resonance modules and the rectification modules are connected in sequence, and the circuit topology of a single-stage LLC type AC-DC converter is achieved; a high-capacity electrolytic capacitor can be eliminated under the condition of keeping a power factor correction function, so that the size is reduced, and the power density can be improved; compared with a single-stage matrix LLC type AC-DC converter, a bridge arm of the converter is composed of two-way switches, the source electrodes of the two-way switches in each group are not in common ground, the two-way bridge arms replace the original two-way switches, the midpoint of each two-way bridge arm and the midpoint of a capacitor bridge arm are connected to a common breakpoint, each group of two-way bridge arms adopts bootstrap driving, only one path of driving power supply is needed, and the cost is reduced. Not only can the cost of the driving power supply be reduced, but also the compactness degree is higher.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a power conversion circuit and a power conversion device. Background Technology

[0002] An AC-DC power supply is a power conversion device used to convert alternating current (AC) into direct current (DC). Alternating current is the common form of power supply in the power grid, while many electronic devices (such as computers and communication equipment) and chemical batteries (such as lithium batteries and lead-acid batteries) require direct current to operate, thus necessitating the conversion by an AC-DC power supply.

[0003] AC-DC power supplies designed for high-power applications require power factor correction (PFC) technology to meet the power grid's requirements for harmonic currents and power factor. PFC technology is used to improve the power factor of power equipment. To meet the power grid's requirements for harmonic currents and power factor, a typical two-stage topology is used, which achieves inter-stage decoupling by connecting a large-capacity electrolytic capacitor between the PFC stage and the DC-DC converter. However, the presence of large-capacity electrolytic capacitors leads to problems such as excessive size and reduced power density.

[0004] To address this issue, matrix LLC resonant converters have been used in recent years to design single-stage AC-DC circuits with PFC functionality. However, the matrix bridge arm in this single-stage AC-DC circuit consists of multiple bidirectional switches, thus requiring a multi-channel isolated drive power supply, resulting in high drive circuit costs and low circuit compactness. Summary of the Invention

[0005] This application provides a power conversion circuit and a power conversion device to alleviate at least some of the above-mentioned technical problems.

[0006] In a first aspect, this application provides a power conversion circuit, which includes a capacitor bridge arm, multiple bidirectional bridge arms, multiple resonant modules, and multiple rectifier modules. The two ends of the capacitor bridge arm are respectively connected to the two ends of a single-phase AC power supply. The two ends of each bidirectional bridge arm are respectively connected to the two ends of the capacitor bridge arm, and the midpoint of each bidirectional bridge arm is connected to the midpoint of the capacitor bridge arm. The first side of each resonant module is connected to a bidirectional bridge arm. The first side of each rectifier module is connected to the second side of a resonant module, and the second sides of the multiple rectifier modules are connected in parallel.

[0007] Optionally, the capacitor bridge arm includes a first capacitor and a second capacitor. The first end of the first capacitor is used to connect to the phase line of the single-phase AC power supply. The first end of the second capacitor is connected to the second end of the first capacitor and the midpoint of each bidirectional bridge arm. The second end of the second capacitor is used to connect to the neutral line of the single-phase AC power supply.

[0008] Optionally, each bidirectional bridge arm includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The drain of the first transistor is connected to the first terminal of the first capacitor; the drain of the second transistor is connected to the source of the first transistor; the source of the third transistor is connected to the source of the second transistor, the second terminal of the first capacitor, and the first terminal of the second capacitor; the source of the fourth transistor is connected to the drain of the third transistor, and the drain of the fourth transistor is connected to the second terminal of the second capacitor.

[0009] Optionally, each resonant module includes an inductor, a third capacitor, and a transformer. The first end of the inductor is connected to the source of the first transistor and the drain of the second transistor. The first end of the third capacitor is connected to the second end of the inductor. The first end of the primary winding of the transformer is connected to the second end of the third capacitor. The second end of the primary winding of the transformer is connected to the drain of the third transistor and the source of the fourth transistor. The secondary winding of the transformer is connected to the first side of a rectifier module.

[0010] Optionally, the power conversion circuit further includes a fourth capacitor, the first end of which is connected to the center tap of the secondary winding of the transformer; each rectifier module includes a first diode and a second diode, the cathode of the first diode is connected to the starting tap of the secondary winding; the cathode of the second diode is connected to the ending tap of the secondary winding; and the anode of the second diode is connected to the anode of the first diode and the second end of the fourth capacitor.

[0011] Optionally, the power conversion circuit also includes a controller connected to multiple bidirectional bridge arms. The controller obtains a drive signal for driving each transistor in each bidirectional bridge arm based on the voltage of the single-phase AC power supply, the input current of the multiple bidirectional bridge arms, and the voltage across the fourth capacitor.

[0012] Optionally, the controller obtains a voltage modulation signal based on the difference between the voltage across the fourth capacitor and a preset reference voltage.

[0013] Optionally, the controller obtains a first calculation result based on the difference between the voltage across the fourth capacitor and a preset reference voltage. After adjusting the first calculation result through a proportional-integral regulator, it performs amplitude limiting processing to obtain a voltage modulation signal.

[0014] Optionally, the controller obtains the absolute value of the phase sinusoid of the single-phase AC power supply based on the voltage of the single-phase AC power supply, and multiplies the voltage modulation signal with the absolute value of the phase sinusoid to obtain the absolute value of the sinusoidal current reference signal that matches the voltage phase of the single-phase AC power supply.

[0015] Optionally, the phase acquisition method for a single-phase AC power supply is a zero-crossing phase-locked loop method.

[0016] Optionally, the controller obtains the drive signal for driving each transistor in the bidirectional bridge arm based on the difference between the absolute value of the sinusoidal current reference signal and the absolute value of the input current of the bidirectional bridge arm.

[0017] Optionally, the controller obtains a second calculation result based on the difference between the absolute value of the sinusoidal current reference signal and the absolute value of the input current of the bidirectional bridge arm, and adjusts the second calculation result through a proportional resonant regulator to obtain a frequency modulation signal.

[0018] Optionally, the controller limits the frequency modulation signal and then performs integration to obtain phase information. The phase information is then processed using trigonometric functions to obtain a sine value, which is compared with a zero distribution to obtain the drive signal for each transistor in the bidirectional bridge arm.

[0019] Secondly, this application also provides a power conversion device, which includes the power conversion circuit described above.

[0020] Optionally, the power conversion device also includes a single-phase AC power supply and a battery, with the battery connected to the second side of the rectifier module.

[0021] The power conversion circuit and power conversion device provided in this application realize the circuit topology of a single-stage LLC AC-DC converter by sequentially connecting capacitor bridge arms, bidirectional switch bridge arms, resonant modules, and rectifier modules. This eliminates large-capacity electrolytic capacitors while maintaining power factor correction, reducing size and increasing power density. Compared to the single-stage matrix LLC AC-DC converter where the bridge arms are composed of bidirectional switches with non-common grounding sources, this application replaces the original bidirectional switches with bidirectional bridge arms. Furthermore, the midpoint of each bidirectional bridge arm is connected to a common breakpoint with the midpoint of the capacitor bridge arm. Each bidirectional bridge arm uses bootstrap drive, requiring only one drive power supply, which not only reduces the cost of the drive power supply but also increases the compactness. Attached Figure Description

[0022] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0023] Figure 1 This is a schematic block diagram of the power conversion circuit provided in an embodiment of this application.

[0024] Figure 2 The circuit diagram of the capacitor bridge arm provided in the embodiment of this application.

[0025] Figure 3 The circuit schematic diagram of the bidirectional bridge arm provided in the embodiments of this application.

[0026] Figure 4The circuit diagram of the resonant module provided in the embodiment of this application is shown.

[0027] Figure 5 The circuit schematic diagram of the rectifier module provided in the embodiments of this application.

[0028] Figure 6 The circuit schematic diagram of the controller provided in the embodiments of this application.

[0029] Figure 7 The circuit diagram of the power conversion device provided in the embodiments of this application is shown. Detailed Implementation

[0030] The technical solutions of 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. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0031] Furthermore, 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 technical features indicated. Features thus defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more unless otherwise explicitly specified.

[0032] In traditional two-stage topologies, a large-capacity electrolytic capacitor is required between the PFC stage and the DC-DC converter for inter-stage decoupling to smooth the DC bus voltage. However, large electrolytic capacitors are bulky, have short lifespans, and exhibit significant equivalent series resistance in high-frequency applications, leading to increased losses.

[0033] The bridge arms of a traditional single-stage matrix LLC AC-DC converter are composed of bidirectional switches. The sources of each group of bidirectional switches are not grounded, so a multi-channel isolated drive power supply is required, resulting in high cost of the drive circuit and low circuit compactness.

[0034] This application eliminates the large electrolytic capacitor on the bus by using a single-stage LLC AC-DC converter, which not only reduces the size but also improves the power density of the circuit. The bridge arms of the single-stage common-ground matrix LLC AC-DC converter are all composed of bidirectional bridge arms. Each group of bidirectional bridge arms adopts bootstrap drive, and each parallel bidirectional bridge arm is connected to a common breakpoint. Only one drive power supply is needed, resulting in low cost of the drive circuit and high circuit compactness.

[0035] like Figure 1As shown, this embodiment provides a power conversion circuit 100, which includes a capacitor bridge arm 10, multiple bidirectional bridge arms 20, multiple resonant modules 30, and multiple rectifier modules 40. The two ends of the capacitor bridge arm 10 are respectively connected to the two ends of a single-phase AC power supply Vac; the two ends of each bidirectional bridge arm 20 are respectively connected to the two ends of the capacitor bridge arm 10, and the midpoint of each bidirectional bridge arm 20 is connected to the midpoint of the capacitor bridge arm 10; the first side of each resonant module 30 is connected to a bidirectional bridge arm 20; the first side of each rectifier module 40 is connected to the second side of a resonant module 30, and the second sides of the multiple rectifier modules 40 are connected in parallel.

[0036] It is understood that the power conversion circuit 100 provided in this embodiment, through the sequential connection of capacitor bridge arm 10, bidirectional switch bridge arm, resonant module 30 and rectifier module 40, realizes the circuit topology of a single-stage LLC AC-DC converter. It can eliminate large-capacity electrolytic capacitors while maintaining the power factor correction function, which not only reduces the size but also improves the power density. Compared with the single-stage matrix LLC AC-DC converter, whose bridge arms are composed of bidirectional switches, the sources of each group of bidirectional switches are not grounded. By replacing the original bidirectional switches with bidirectional bridge arms 20, and connecting the midpoint of each bidirectional bridge arm 20 to the midpoint of the capacitor bridge arm 10 to a common break point, each group of bidirectional bridge arms 20 adopts bootstrap drive, requiring only one drive power supply, which not only reduces the cost of the drive power supply but also increases the compactness.

[0037] In some embodiments, such as Figure 2 As shown, the capacitor bridge arm 10 includes a first capacitor C1 and a second capacitor C2. The first end of the first capacitor C1 is used to connect to the phase line (L) of the single-phase AC power supply Vac. The first end of the second capacitor C2 is connected to the second end of the first capacitor C1 and the midpoint of the bidirectional bridge arm 20. The second end of the second capacitor C2 is used to connect to the neutral line (N) of the single-phase AC power supply Vac.

[0038] It should be noted that the first terminal of the second capacitor C2 is connected to the second terminal of the first capacitor C1 and the midpoint of the bidirectional bridge arm 20, so that the midpoint of the bidirectional bridge arm 20 can provide a stable reference potential, thereby suppressing common-mode noise. The first capacitor C1 and the second capacitor C2 form a voltage divider filter network, which can reduce the voltage withstand requirement of each capacitor. The midpoint of the capacitor bridge arm 10 is the connection point between the first capacitor C1 and the second capacitor C2.

[0039] In some embodiments, such as Figure 3As shown, each bidirectional bridge arm 20 includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The drain of the first transistor is connected to the first terminal of the first capacitor C1; the drain of the second transistor is connected to the source of the first transistor; the source of the third transistor is connected to the source of the second transistor, the second terminal of the first capacitor C1, and the first terminal of the second capacitor C2; the source of the fourth transistor is connected to the drain of the third transistor, and the drain of the fourth transistor is connected to the second terminal of the second capacitor C2.

[0040] It should be noted that since the source of the second transistor and the source of the third transistor in each bidirectional bridge arm 20 are connected to the midpoint of the capacitor bridge arm 10, the source of the second transistor and the source of the third transistor in the bidirectional bridge arm 20 can be connected to a common ground, thereby reducing the number of drive power supplies.

[0041] The plurality of bidirectional bridge arms 20 may exemplary include a first bidirectional bridge arm and a second bidirectional bridge arm. The first bidirectional bridge arm may include a first transistor (Sa1), a second transistor (Sa2), a third transistor (Sa3), and a fourth transistor (Sa4). The second bidirectional bridge arm may include a first transistor (Sb1), a second transistor (Sb2), a third transistor (Sb3), and a fourth transistor (Sb4).

[0042] In some embodiments, such as Figure 4 As shown, each resonant module 30 includes an inductor, a third capacitor, and a transformer. The first end of the inductor is connected to the source of the first transistor and the drain of the second transistor. The first end of the third capacitor is connected to the second end of the inductor. The first end (PRa1 / PRb1) of the primary winding of the transformer is connected to the second end of the third capacitor. The second end (PRa2 / PRb2) of the primary winding of the transformer is connected to the drain of the third transistor and the source of the fourth transistor. The secondary winding of the transformer is connected to the first side of a rectifier module 40.

[0043] It should be noted that the transformer can be high-frequency. The inductor receives the high-frequency energy output from the bidirectional bridge arm 20, which is then input to the primary winding of the transformer after resonance with the third capacitor. The inductor, the third capacitor, and the transformer can form an LLC resonant circuit, eliminating the need for large-capacity electrolytic capacitors, thereby reducing the size and increasing the power density.

[0044] The plurality of resonant modules 30 may exemplary include a first resonant module and a second resonant module, wherein the first resonant module includes an inductor (Lra), a third capacitor (Cra), and a transformer (Ta), and the second resonant module includes an inductor (Lrb), a third capacitor (Crb), and a transformer (Tb).

[0045] In some embodiments, such as Figure 5As shown, the power conversion circuit 100 also includes a fourth capacitor Co, the first end of which is connected to the middle tap (SRa2 / SRb2) of the secondary winding of the transformer; each rectifier module 40 includes a first diode and a second diode, the cathode of the first diode is connected to the starting tap (SRa1 / SRb1) of the secondary winding; the cathode of the second diode is connected to the ending tap (SRa3 / SRb3) of the secondary winding; and the anode of the second diode is connected to the anode of the first diode and the second end of the fourth capacitor Co.

[0046] It should be noted that the fourth capacitor Co is used for high-frequency filtering to reduce fluctuations in the rectified DC output voltage, i.e., the voltage (Vo) across the fourth capacitor Co. Here, io can be the output current of the power conversion circuit 100.

[0047] Compared to using a full-bridge rectifier, this embodiment uses two diodes for rectification, which reduces conduction losses and the PCB footprint. In conjunction with the soft-switching characteristics of the LLC resonant circuit, the diodes naturally commutate when the current crosses zero, thus achieving zero-current turn-off (ZCS) with no reverse recovery losses.

[0048] The plurality of rectifier modules 40 may include a first rectifier module and a second rectifier module. The first rectifier module includes a first diode (Da1) and a second diode (Da2), and the second rectifier module includes a first diode (Db1) and a second diode (Db2).

[0049] In some embodiments, such as Figure 6 As shown, the power conversion circuit 100 also includes a controller 50 connected to multiple bidirectional bridge arms 20. The controller 50 obtains a drive signal for driving each transistor in each bidirectional bridge arm 20 based on the voltage (Vac) of the single-phase AC power supply Vac, the input current (Iac_a / Iac_b) of the multiple bidirectional bridge arms 20, and the voltage (Vo) across the fourth capacitor Co.

[0050] It should be noted that this embodiment adopts a multivariable closed-loop control strategy, which can not only reduce total harmonic distortion (THD) but also adapt to load changes, thereby improving conversion efficiency.

[0051] In some embodiments, the controller 50 obtains a voltage modulation signal (Vc) based on the difference between the voltage across the fourth capacitor Co and a preset reference voltage (Vref).

[0052] In some embodiments, the controller 50 obtains a first calculation result (Verror) based on the difference between the voltage across the fourth capacitor Co and a preset reference voltage (Vref). After adjusting the first calculation result (Verror) through a proportional-integral regulator (PI), it performs amplitude limiting to obtain a voltage modulation signal (Vc).

[0053] It should be noted that the proportional-integral (PI) controller is exemplarily an incremental PI controller, and its adjustment expression is as follows:

[0054] Voerr0 = Verror

[0055] Uk=Uk+Kp1×(Voerr0-Voerr1)+Ki1×Voerr0

[0056] Voerr1=Voerr0

[0057] Vc=Uk

[0058] Among them, Voerr0, Uk, and Voerr1 are intermediate variables, and Kp1 and Ki1 are proportional and integral coefficients, respectively.

[0059] The minimum voltage limit is 0, and the maximum value is the peak value of the input current of a single LLC resonant circuit under the maximum allowable power.

[0060] In some embodiments, the controller 50 obtains the absolute value of the phase sinusoidal value (|sin(PH)|) of the single-phase AC power supply Vac based on the voltage (Vac) of the single-phase AC power supply Vac, and multiplies the voltage modulation signal (Vc) with the absolute value of the phase sinusoidal value (|sin(PH)|) to obtain the absolute value of the sinusoidal current reference signal (|Iref|) that matches the voltage phase (PH) of the single-phase AC power supply Vac.

[0061] In some embodiments, the phase acquisition method for the single-phase AC power supply Vac is a zero-crossing phase-locked loop method.

[0062] It should be noted that the zero-crossing phase-locked loop (PLL) method can extract the phase of the AC voltage at the zero-crossing point, thereby generating the absolute value of the phase sine (|sin(PH)|). This enables grid frequency fluctuation tracking, thereby reducing phase error.

[0063] In some embodiments, the controller 50 obtains the drive signal for driving each transistor in the bidirectional bridge arm 20 based on the difference between the absolute value of the sinusoidal current reference signal (|Iref|) and the absolute value of the input current (Iac_a / Iac_b) of the bidirectional bridge arm 20.

[0064] In some embodiments, the controller 50 obtains a second calculation result (Ierror_a / Ierror_b) based on the difference between the absolute value of the sinusoidal current reference signal (|Iref|) and the absolute value of the input current (Iac_a / Iac_b) of the bidirectional bridge arm 20, and adjusts the second calculation result through a proportional resonant regulator (PI) to obtain a frequency modulation signal (Vfma / Vfmb).

[0065] It should be noted that in this embodiment, the proportional resonant regulator (PI) achieves zero steady-state error tracking of the input current to a current reference signal at a given power frequency through digital filtering. Taking the adjustment of Ierror_a as an example, the expression is as follows:

[0066] PR_ic=Kpr×0.0006279178×ierror-Kpr×0.0006279178×PR_ierror2

[0067] +1.9987047×PR_ic1-0.99874416×PR_ic2

[0068] PR_ierror2=PR_ierror1

[0069] PR_ierror1 = Ierror

[0070] PR_ic2=PR_ic1

[0071] PR_ic1=PR_ic

[0072] ikc = ierror × Kr

[0073] Vfma = PR_ic + ikc

[0074] The proportional resonant regulator used is a second-order bandpass filter with a center frequency of 100Hz and a bandwidth of 10Hz. PR_ic, PR_ierror1, PR_ierror2, PR_ic1, and PR_ic2 are intermediate variables, and Kr and Kpr are the proportional and resonant coefficients, respectively.

[0075] In some embodiments, the controller 50 limits the frequency modulation signal (Vfma / Vfmb) and then performs integration to obtain phase information (VPHa, VPHb). The phase information is then processed by trigonometric functions to obtain sine values ​​(sin(VPHa), sin(VPHb)). These values ​​are then compared with the zero distribution to obtain the drive signals for each transistor in the bidirectional bridge arm 20.

[0076] based on Figure 6 This embodiment also provides a power conversion control method, including the following steps:

[0077] S1. Collect the input current (Iac_a) of the bidirectional switch bridge arm a and the input current (Iac_b) of the bidirectional switch bridge arm b, the voltage (Vac) of the single-phase AC power supply Vac, the voltage across the output filter capacitor (Co), and the phase information (PH) of the single-phase AC power supply Vac.

[0078] S2. Subtract the output voltage (Vo) from the preset reference voltage (Vref) to obtain the calculation result (Verror); adjust the calculation result (Verror) through a proportional-integral regulator and then perform amplitude limiting to obtain the voltage modulation signal (Vc).

[0079] S3. Multiply the voltage modulation signal (Vc) by the absolute value of the phase sinusoid of the single-phase AC power supply Vac (|sin(PH)|) to obtain the absolute value of the sinusoidal current reference signal (|Iref|) that matches the voltage phase of the single-phase AC power supply Vac; then subtract the absolute value of the sinusoidal current reference signal (|Iref|) from the absolute value of the input current of the bidirectional switch bridge arm a (|Iac_a|) and the absolute value of the input current of the bidirectional switch bridge arm b (|Iac_b|) to obtain the calculation results (Ierror_a, Ierror_b); adjust the calculation results (Ierror_a, Ierror_b) through the proportional resonant regulator to obtain the frequency modulation signals (Vfma, Vfmb).

[0080] S4. After limiting the frequency modulation signal (Vfma, Vfmb), integrate it to obtain phase information (VPHa, VPHb). Then, perform trigonometric function calculations to obtain sine values ​​(sin(VPHa), sin(VPHb)). Compare these values ​​with the 0 distribution to obtain the drive signal for each MOS transistor.

[0081] In some embodiments, such as Figure 7 As shown, this embodiment also provides a power conversion device 200, which includes the power conversion circuit 100 described above.

[0082] It is understood that, since the power conversion device 200 provided in this embodiment includes the power conversion circuit 100 described above, it can also be connected sequentially through capacitor bridge arm 10, bidirectional switch bridge arm, resonant module 30 and rectifier module 40, realizing the circuit topology of a single-stage LLC AC-DC converter. It can eliminate large-capacity electrolytic capacitors while maintaining the power factor correction function, which not only reduces the size but also increases the power density. Compared with the single-stage matrix LLC AC-DC converter, whose bridge arms are composed of bidirectional switches, the sources of each group of bidirectional switches are not grounded. By replacing the original bidirectional switches with bidirectional bridge arms 20, and connecting the midpoint of each bidirectional bridge arm 20 to the midpoint of the capacitor bridge arm 10 to a common break point, each group of bidirectional bridge arms 20 adopts bootstrap drive, requiring only one drive power supply, which not only reduces the cost of the drive power supply but also increases the compactness.

[0083] In some embodiments, such as Figure 7 As shown, the power conversion device 200 also includes a single-phase AC power supply Vac and a battery Bat, which is connected to the second side of the rectifier module 40.

[0084] It should be noted that the battery Bat can be a lithium battery, lead-acid battery, or other type of chemical battery. The positive terminal of the battery Bat is connected to the positive terminal of the fourth capacitor Co, and the negative terminal of the battery Bat is connected to the negative terminal of the fourth capacitor Co. In other embodiments, electronic devices (such as computers, communication equipment, etc.) can be used instead of the battery Bat.

[0085] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0086] The power conversion circuit 100 and power conversion device 200 provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A power conversion circuit, characterized in that, The power conversion circuit includes: A capacitor bridge arm, the two ends of which are respectively connected to the two ends of a single-phase AC power supply. Multiple bidirectional bridge arms, each bidirectional bridge arm having its two ends connected to the two ends of the capacitor bridge arm, and the midpoint of each bidirectional bridge arm being connected to the midpoint of the capacitor bridge arm. Multiple resonant modules, each of which has a first side connected to a bidirectional bridge arm; Multiple rectifier modules are provided, with a first side of each rectifier module connected to a second side of a resonant module, and the second sides of the multiple rectifier modules are connected in parallel.

2. The power conversion circuit according to claim 1, characterized in that, The capacitor bridge arm includes: A first capacitor, the first end of which is used to connect to the phase line of the single-phase AC power supply. The second capacitor has its first end connected to the second end of the first capacitor and the midpoint of each of the bidirectional bridge arms. The second end of the second capacitor is used to connect to the neutral terminal of the single-phase AC power supply.

3. The power conversion circuit according to claim 2, characterized in that, Each of the aforementioned bidirectional bridge arms includes: The first transistor, the drain of the first transistor is connected to the first terminal of the first capacitor; The drain of the second transistor is connected to the source of the first transistor; The source of the third transistor is connected to the source of the second transistor, the second terminal of the first capacitor, and the first terminal of the second capacitor. The fourth transistor has its source connected to the drain of the third transistor, and its drain connected to the second terminal of the second capacitor.

4. The power conversion circuit according to claim 3, characterized in that, Each of the resonant modules includes: An inductor, wherein a first terminal of the inductor is connected to the source of the first transistor and the drain of the second transistor; A third capacitor, wherein the first terminal of the third capacitor is connected to the second terminal of the inductor; The transformer has a primary winding whose first end is connected to the second end of the third capacitor, the second end of the primary winding connected to the drain of the third transistor and the source of the fourth transistor, and the secondary winding connected to the first side of the rectifier module.

5. The power conversion circuit according to claim 4, characterized in that, The power conversion circuit also includes a fourth capacitor, the first end of which is connected to the center tap of the secondary winding of the transformer. Each of the rectifier modules includes: A first diode, the cathode of which is connected to the starting tap of a secondary winding; The second diode has its cathode connected to the end tap of the secondary winding, and its anode connected to the anode of the first diode and the second terminal of the fourth capacitor.

6. The power conversion circuit according to claim 5, characterized in that, The power conversion circuit also includes a controller connected to the plurality of bidirectional bridge arms. The controller obtains a drive signal for driving each transistor in each of the bidirectional bridge arms based on the voltage of the single-phase AC power supply, the input current of the plurality of bidirectional bridge arms, and the voltage across the fourth capacitor.

7. The power conversion circuit according to claim 6, characterized in that, The controller obtains a voltage modulation signal based on the difference between the voltage across the fourth capacitor and a preset reference voltage.

8. The power conversion circuit according to claim 7, characterized in that, The controller obtains a first calculation result based on the difference between the voltage across the fourth capacitor and a preset reference voltage. After adjusting the first calculation result through a proportional-integral regulator, it performs amplitude limiting processing to obtain the voltage modulation signal.

9. The power conversion circuit according to claim 7, characterized in that, The controller obtains the absolute value of the phase sinusoid of the single-phase AC power supply based on the voltage of the single-phase AC power supply, and multiplies the voltage modulation signal with the absolute value of the phase sinusoid to obtain the absolute value of the sinusoidal current reference signal that matches the voltage phase of the single-phase AC power supply.

10. The power conversion circuit according to claim 9, characterized in that, The phase acquisition method for the single-phase AC power supply is the zero-crossing phase-locked loop method.

11. The power conversion circuit according to claim 9, characterized in that, The controller obtains the driving signal for each transistor in the bidirectional bridge arm based on the difference between the absolute value of the sinusoidal current reference signal and the absolute value of the input current of the bidirectional bridge arm.

12. The power conversion circuit according to claim 11, characterized in that, The controller obtains a second calculation result based on the difference between the absolute value of the sinusoidal current reference signal and the absolute value of the input current of the bidirectional bridge arm. The controller then adjusts the second calculation result through a proportional resonant regulator to obtain a frequency modulation signal.

13. The power conversion circuit according to claim 12, characterized in that, The controller limits the amplitude of the frequency modulation signal and performs integration to obtain phase information. It then uses trigonometric functions to calculate a sine value from the phase information and compares it with a zero distribution to obtain the driving signal for each transistor in the bidirectional bridge arm.

14. A power conversion device, characterized in that, The power conversion device includes the power conversion circuit as described in any one of claims 1-13.

15. The power conversion device according to claim 14, characterized in that, The power conversion device also includes the single-phase AC power supply and a battery, with the battery connected to the second side of the rectifier module.

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