DC-DC resonant converter and control method thereof

Abstract

The present disclosure provides a DC-DC resonant converter and a control method thereof. The DC-DC resonant converter includes: m groups of primary-side stages connected in parallel, wherein each group of primary-side stages is identical and includes n layers of stacked circuits, where m is a positive integer and n is an integer greater than 1, and the m groups of primary-side stages receive an input voltage; n*m resonant circuits coupled to the primary-side stages; n*m transformers having a total of n*m primary-side windings and n*m secondary-side windings, wherein the primary-side windings are coupled to corresponding resonant circuits; p groups of secondary-side stages connected in parallel, wherein each group of secondary-side stages is identical and includes q (q=n*m / p) layers of stacked circuits, and the secondary-side stages are coupled to corresponding secondary-side windings; and a control circuit for controlling a primary-side switch according to an output voltage, an input voltage, and an input capacitor voltage.

Description

Technical Field

[0001] The present disclosure relates to a DC-DC resonant converter and a control method thereof, and in particular to a stacked bridge resonant converter that adopts a switching frequency control and voltage balancing strategy. Background Art

[0002] Resonant converters use resonant cavity circuits to shape the waveforms of the switching voltage and / or switching current to minimize switching losses and enable high-frequency operation. Due to their high efficiency, simple structure achieved through integrated magnetic components, soft switching on both the primary and secondary switches, and compatibility with a wide voltage range, they are widely used as isolated DC / DC converters.

[0003] For example, US Patent No. 6,344,979, entitled “LLC Series Resonant DC-DC Converter” and published on February 5, 2002, discloses an LLC resonant converter and its basic operating principle. Figure 1A and Figure 1B The control signals of the conventional full-bridge LLC resonant converter and its switches S1 to S4 and the primary-side full-bridge output voltage V are shown respectively under closed-loop voltage control. AB The output voltage V can be adjusted by controlling the switching frequency of the primary side switch. AB When the LLC resonant converter operates at the resonant frequency f r And the DC voltage gain M is equal to the transformer turns ratio N P / N S The highest efficiency can be achieved when the resonant frequency f r By the resonant inductor L r and resonant capacitor C r When the switching frequency f sw Greater than the resonant frequency f r When the switching frequency f sw Less than the resonant frequency f r When the switching frequency f sw Towards the resonant frequency f r To achieve the desired output voltage range, the LLC resonant converter should operate within its corresponding frequency range.

[0004] like Figure 1A and Figure 1B As shown, the resonant cavity contains an inductor L connected in series r and capacitor C r , the circuit in the figure can be regarded as a series resonant converter. If the excitation inductance L of the transformer TR mRelatively small (i.e. only the resonant inductance L r (several times of ), the converter can operate as an LLC series resonant converter. It should be noted that the secondary side diode rectifiers (including diodes D1, D2, D3 and D4) can use synchronous rectifiers (for example, low on-resistance MOSFETs) to improve efficiency. In addition, the controllable switches on both sides of the transformer allow power to flow in both directions, so the converter can operate in both directions. It should also be noted that the secondary side of the isolated resonant converter can use a center-tapped secondary winding instead of a Figure 1A The full-wave rectifier is shown.

[0005] Generally speaking, a resonant converter is controlled by variable switching frequency control. During operation above the resonant frequency, the primary-side switch of the resonant converter achieves zero-voltage switching (ZVS), while during operation below the resonant frequency, the resonant converter achieves zero-current switching (ZCS). For more details on the resonant converter topology and its control methods, please refer to reference [1].

[0006] Figure 1B Shown Figure 1A Typical timing of the switching control signals of a series resonant converter operating with zero voltage switching. Figure 1B As shown, all switches S1, S2, S3, and S4 operate with the same 50% duty cycle. The primary-side switches in the same leg (i.e., switches S1 and S2 in Leg A and switches S3 and S4 in Leg B) operate in a complementary manner to prevent cross-conduction. The frequency of the primary-side switching is determined by the feedback control loop used to regulate the output. To achieve zero-voltage switching in practice, a small delay (or dead time) is introduced between the turn-off and turn-on times of the complementary switches in the same leg, setting the duty cycle of the primary switches to a value slightly less than 50%. During this dead time, current is diverted from the off-state switch to the antiparallel diode of the other commutating device, creating the conditions for subsequent zero-voltage switching.

[0007] When using 1.2kV devices, the full-bridge structure is usually used in applications with a DC input voltage of less than 800V. In high input voltage applications, the three-level topology in reference [2] is more attractive because each switch device only needs to block half of the input voltage. The three-level topology is applied to the LLC converter in reference [3], and the proposed converter can achieve zero-voltage switching of the switches without additional auxiliary circuits. In reference [4], the three-level serial half bridge (SHB) topology (also known as stacked buck topology) was first proposed, which removes two clamping diodes compared to the traditional three-level topology in reference [2].

[0008] Figure 2A and Figure 2B An exemplary series-connected half-bridge resonant converter and its control signals of switches S1 to S4 and the primary-side full-bridge output voltage V are shown respectively. AB The series half-bridge resonant converter can also be controlled by variable switching frequency control. Figure 2A As shown, all switches S1, S2, S3, and S4 operate at the same 50% duty cycle. The primary-side switches in the same leg (i.e., switches S1 and S2 in Leg A and switches S3 and S4 in Leg B) operate in a complementary manner to prevent cross-conduction. Switches S1 and S4 have the same switching control signal, while switches S2 and S3 have the same switching control signal. The frequency of the primary-side switching is determined by the feedback control loop used to regulate the output.

[0009] Generally speaking, due to the power rating of the discrete components, the power of the full-bridge resonant converter based on discrete components is limited to several kilowatts. Reference [5] proposes a three-phase LLC resonant converter, which further improves the converter power by additionally setting a half-bridge phase bridge arm in parallel with the existing bridge arm in the primary side and a half-bridge phase bridge arm in parallel with the existing bridge arm in the secondary side. The three-phase converter can have three independent transformers or a single integrated transformer. The topology of a typical three-phase LLC converter and its switching control timing are shown in Figures 3A and 3B respectively. The switching control signals of each primary side half bridge are mostly interleaved with a phase shift of 120 degrees. This implementation can reduce current and voltage ripple, thereby reducing the stress on components.

[0010] Recently, power supplies with high input voltage (>2kV) have become increasingly attractive in high power applications (e.g., solid-state transformers) because they can deliver more power at the same input current. Reference [6] proposes a multi-phase multi-level LLC resonant converter with a star-connected transformer to meet the needs of high voltage and high power applications. The topology of the multi-phase multi-level LLC resonant converter with three modules and their switching control timing are respectively Figure 4A and Figure 4B As shown in FIG, the switching control signals of each primary side half-bridge arm are usually interleaved with a phase shift of 120 degrees. However, due to the stacked structure and star connection of the transformer, the resonant capacitor in each phase arm will be subjected to a DC bias. Furthermore, when the input voltage rises, the DC bias will increase further. In addition, reference [6] does not describe how to solve the voltage imbalance problem of the stacked capacitor and perform bidirectional operation. Therefore, it is necessary to develop a DC / DC bidirectional resonant converter that can operate in high input voltage and high power applications while retaining the advantages of traditional resonant converters. In addition, it is necessary to develop a voltage balancing control strategy for multi-phase multi-level LLC resonant converters.

[0011] References:

[0012] [1] B.Yang, FCLee, AJZhang and G.Huang, "LLC resonant converter for front end DC / DC conversion," APEC.Seventeenth Annual IEEE Applied PowerElectronics Conference and Exposition (Cat.No.02CH37335), Dallas, TX, USA, 2002.

[0013] [2]JRPinheiro and I.Barbi, "The three-level ZVS PWM converter-a new concept in high voltage DC-to-DC conversion," Proceedings of the1992International Conference on Industrial Electronics, Control, Instrumentation, and Automation, 1992.

[0014] [3]Y. Gu, Z. Lu, L. Hang, Z. Qian and G. Huang, “Three-level LLC series resonant DC / DC converter,” IEEE Transactions on Power Electronics, vol. 20, no. 4, pp. 781-789, July 2005.

[0015] [4]I. Barbi, R. Gules, R. Redl and N. O. Sokal, “DC-DC converter: four switches V / sub pk / =V / sub in / / 2, capacitive turn-off snubbing, ZV turn-on,” IEEE Transactions on Power Electronics, vol. 19, no. 4, pp. 918-927, July 2004.

[0016] [5]T. Jin and K. Smedley, “Multiphase LLC Series Resonant Converter for Microprocessor Voltage Regulation,” Conference Record of the 2006 IEEE Industry Applications Conference Forty-First IAS Annual Meeting, Tampa, FL, 2006, pp. 2136-2143.

[0017] [6]F. Jin, F. Liu, X. Ruan and X. Meng, “Multi-phase multi-level LLC resonant converter with low voltage stress on the primary-side switches,” 2014 IEEE Energy Conversion Congress and Exposition (ECCE), Pittsburgh, PA, 2014, pp. 4704-4710. Summary of the Invention

[0018] The present disclosure provides a DC-DC resonant converter with better performance. Specifically, by stacking multiple circuit elements connected in series, the resonant converter of the present disclosure is suitable for high power and high voltage applications.

[0019] According to one aspect of the present disclosure, an embodiment of the present disclosure provides a DC-DC converter comprising a primary side, a secondary side, and a control circuit. The primary side comprises at least two half-bridge inverter units stacked in series, wherein each half-bridge inverter unit comprises two active switches connected in series and two input capacitors connected in series, and the bridge arms containing the two active switches are connected in parallel with the bridge arms containing the two input capacitors to jointly form a first loop. Each half-bridge inverter unit is sequentially connected from a point between the two active switches to a resonant cavity circuit, a primary-side winding wound on a transformer core, and a point between the two input capacitors. The first end of any half-bridge inverter unit is connected to all bridge arms in the first loop, and the first end of any half-bridge inverter unit is directly connected to the second end of the corresponding stacked half-bridge inverter unit. A primary-side voltage is applied or generated between the first and second ends of all half-bridge inverter units that are not connected to another half-bridge inverter unit. The half-bridge inverter units may share a transformer core. The secondary side includes at least two sets of rectifier circuit elements, each of which is coupled to a secondary winding wound on a transformer core. The secondary winding shares the transformer core with a corresponding primary winding. The rectifier circuit elements are configured to rectify the induced current on the secondary side caused by current flowing through the corresponding primary winding. A secondary-side voltage is generated or applied to the secondary side. A control circuit is configured to actuate all active switches in the DC-DC converter to change the pulse frequency, pulse width, or phase shift angle of the voltage or current across the inverter unit or rectifier circuit elements.

[0020] According to another aspect of the present disclosure, one embodiment provides a DC-DC converter comprising a primary side, a secondary side, and a control circuit. The primary side comprises at least two half-bridge inverter units stacked in series, wherein each half-bridge inverter unit comprises two active switches connected in series and an input capacitor, and the bridge arms containing the two active switches are connected in parallel with the bridge arm containing the input capacitor to form a first loop. Each half-bridge inverter unit is sequentially connected from a point between the two active switches to a resonant cavity circuit, a first end of a primary winding wound on a transformer core, a second end of the primary winding, and a common star point for all half-bridge inverter units. The first end of any half-bridge inverter unit is connected to all bridge arms in the first loop, and the first end of any half-bridge inverter unit is directly connected to the second end of the corresponding stacked half-bridge inverter unit. A primary-side voltage is applied or generated between the first and second ends of all half-bridge inverter units that are not connected to another half-bridge inverter unit. The half-bridge inverter units may share a transformer core. The secondary side includes at least two sets of rectifier circuit elements, each of which is coupled to a secondary winding wound on a transformer core. The secondary winding shares the transformer core with a corresponding primary winding. The rectifier circuit elements are configured to rectify the induced current on the secondary side caused by current flowing through the corresponding primary winding. A secondary-side voltage is generated or applied to the secondary side. A control circuit is configured to actuate all active switches in the DC-DC converter to change the pulse frequency, pulse width, or phase shift angle of the voltage or current across the inverter unit or rectifier circuit elements.

[0021] According to another aspect of the present disclosure, one embodiment provides a DC-DC converter comprising a primary side, a secondary side, and a control circuit. The primary side comprises at least two stacked series half-bridge inverter units, each of which comprises a first half-bridge arm and a second half-bridge arm connected in series. The first half-bridge arm comprises a first input capacitor and two first active switches connected in series, with the first switch arm containing the two first active switches connected in parallel with the arm containing the first input capacitor to form a first loop. The second half-bridge arm comprises a second input capacitor and two second active switches connected in series, with the second switch arm containing the two second active switches connected in parallel with the arm containing the second input capacitor to form a loop. Each series half-bridge inverter unit is sequentially connected from a point between the two first active switches to a resonant cavity circuit, a primary winding wound on a transformer core, and a point between the two second active switches. The first end of each series half-bridge inverter unit is connected to all arms in the first loop, and the first end of each series half-bridge inverter unit is directly connected to the second end of the corresponding stacked series half-bridge inverter unit. A primary-side voltage is applied or generated between the first and second ends of all series-connected half-bridge inverter units that are not connected to another series-connected half-bridge inverter unit. The series-connected half-bridge inverter units can share a transformer core. The secondary side includes at least two groups of rectifier circuit elements, wherein each group of rectifier circuit elements is coupled to a secondary-side winding wound on the transformer core, and the secondary-side winding and a corresponding primary-side winding share the transformer core. The rectifier circuit element is configured to rectify the induced current generated on the secondary side due to the current flowing through the corresponding primary-side winding. A secondary-side voltage is generated or applied to the secondary side. The control circuit is configured to actuate all active switches in the DC-DC converter to change the pulse frequency, pulse width, or phase shift angle of the voltage or current on the inverter unit or the rectifier circuit element.

[0022] According to another aspect of the present disclosure, one embodiment provides a DC-DC converter comprising a primary side, a secondary side, and a control circuit. The primary side comprises at least two full-bridge inverter units stacked in series, wherein each full-bridge inverter unit comprises a capacitor bridge arm and two half-bridge bridge arms connected in parallel, and each half-bridge bridge arm comprises two active switches connected in series. Each full-bridge inverter unit is connected from a point between the two active switches of one half-bridge arm to a point between the two active switches of the other half-bridge arm via a resonant cavity circuit and a primary-side winding wound on a transformer core. A primary-side voltage is generated or applied between the two ends of all full-bridge inverter units stacked in series. In any full-bridge inverter unit, the first and second ends of the full-bridge inverter unit are respectively connected to the two ends of all bridge arms. The first end of any full-bridge inverter unit is directly connected to the second end of the corresponding stacked full-bridge inverter unit. The primary-side voltage is applied or generated between the first and second ends of all full-bridge inverter units that are not connected to another full-bridge inverter unit. The full-bridge inverter units may share a transformer core. The secondary side includes at least two sets of rectifier circuit elements, each of which is coupled to a secondary winding wound on a transformer core. The secondary winding shares the transformer core with a corresponding primary winding. The rectifier circuit elements are configured to rectify the induced current on the secondary side caused by current flowing through the corresponding primary winding. A secondary-side voltage is generated or applied to the secondary side. A control circuit is configured to actuate all active switches in the DC-DC converter to change the pulse frequency, pulse width, or phase shift angle of the voltage or current across the inverter unit or rectifier circuit elements.

[0023] In the specification and claims of the present disclosure, the word "a" used after the words "comprises", "includes", "has" etc. may mean one, one or more or at least one. Regardless of whether each aspect is described separately in the specification or multiple aspects are described in the form of "and / or", when the aspect is connected with the word "or" in the claim, unless it is clearly limited that only one of the aspects can be selected or the aspects are mutually exclusive, the word "or" used in the claim means "and / or". On the other hand, the features and advantages of the invention disclosed in the present disclosure will become more apparent through the detailed description below. It should be understood that the embodiments and specific examples described in detail in the present disclosure are for illustrative purposes, and the present disclosure may be modified in various ways by those skilled in the art, but all of them are within the scope of protection as claimed in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1A and Figure 1B The control signals of the conventional full-bridge LLC resonant converter and its switches S1 to S4 and the primary-side full-bridge output voltage V are shown respectively under closed-loop voltage control. AB timing.

[0025] Figure 2A and Figure 2B The control signals of an exemplary series-connected half-bridge resonant converter and its switches S1 to S4 and the primary-side full-bridge output voltage V are shown respectively. AB timing.

[0026] Figure 3A and Figure 3B The topology of a typical three-phase LLC converter and its switching control timing are shown respectively.

[0027] Figure 4A and Figure 4B The topology of a multi-phase multi-level LLC resonant converter with three modules and its switching control timing are shown respectively.

[0028] Figure 5A A three-layer stacked half-bridge LLC resonant converter according to an embodiment of the present disclosure is shown.

[0029] Figure 5B This shows an embodiment of the present disclosure Figure 5A The switching control signals GS1 to GS6 of the converter, the resonant cavity input voltage V AB 、V CD and V EF , resonant capacitor voltage V cr1 、V cr2 and V cr3 And the resonant current i r1 、i r2 and i r3 Timing when performing variable frequency control.

[0030] Figure 5C An embodiment of the present disclosure shows Figure 5A The switching control signals GS1 to GS6 of the converter, the resonant capacitor voltage V cr1 To V cr3 And the resonant current i r1 to i r3 Timing when performing variable duty cycle control.

[0031] Figure 6A A three-layer stacked half-bridge LLC resonant converter according to an embodiment of the present disclosure is shown, which has active switches on the secondary side for achieving bidirectional operation.

[0032] Figure 6B This shows an embodiment of the present disclosure Figure 6A The switching control signals GS1 to GS12 of the converter, the resonant capacitor voltage V cr1 To V cr3 And the resonant current i r1 to i r3 Timing for variable frequency control and phase shift control.

[0033] Figure 7A An n-layer stacked half-bridge resonant converter according to an embodiment of the present disclosure is shown.

[0034] Figure 7B An n-layer stacked half-bridge resonant converter with integrated transformer is shown.

[0035] Figure 7C An n-layer stacked half-bridge resonant converter is shown with active switches on the secondary side for achieving synchronous rectification and bidirectional operation.

[0036] Figure 8A A three-layer stacked series half-bridge resonant converter with a three-phase diode bridge rectifier in one embodiment of the present disclosure is shown.

[0037] Figure 8B Shows the Figure 8A The switching control signals GS1 to GS6 of the converter, the full-bridge output voltage V AB To V EF , resonant capacitor voltage V cr1 To V cr3 And the resonant current i r1 to i r3 Timing when performing variable frequency control.

[0038] Figure 8C A three-layer stacked series half-bridge resonant converter according to an embodiment of the present disclosure is shown, which has three full-wave diode bridge legs connected in parallel for rectification.

[0039] Figure 9A An n-layer stacked series half-bridge resonant converter according to an embodiment of the present disclosure is shown, which has n full-wave diode bridge arms connected in parallel for rectification.

[0040] Figure 9B An n-layer stacked series half-bridge resonant converter with an integrated transformer in one embodiment of the present disclosure is shown.

[0041] Figure 9C An n-layer stacked series half-bridge resonant converter according to an embodiment of the present disclosure is shown, which has an active switch on the secondary side for achieving synchronous rectification and bidirectional operation.

[0042] Figure 9D An n-layer stacked series half-bridge resonant converter according to an embodiment of the present disclosure is shown, which has n full-wave diode bridge arms connected in parallel for rectification.

[0043] Figure 10A FIG2 is a schematic diagram of duty cycle-based voltage balancing control for a stacked half-bridge resonant converter according to an embodiment of the present disclosure.

[0044] Figure 10B FIG2 is a schematic diagram of duty cycle-based voltage balancing control for a stacked half-bridge resonant converter with a star-connected transformer according to an embodiment of the present disclosure.

[0045] Figure 10C FIG1 is a flow chart of a phase-shift-based voltage balancing control for a three-layer stacked half-bridge resonant converter according to an embodiment of the present disclosure.

[0046] Figure 10D FIG1 is a flow chart of phase-shift-based voltage balancing control for a three-layer stacked half-bridge resonant converter with a star-connected transformer in accordance with an embodiment of the present disclosure.

[0047] Figure 10E FIG1 is a flow chart of a voltage balancing control method based on a hybrid approach for a stacked half-bridge resonant converter according to an embodiment of the present disclosure.

[0048] Figure 11A A three-layer stacked full-bridge resonant converter according to an embodiment of the present disclosure is shown.

[0049] Figure 11B Shows the Figure 11A The switching control signals GS1 to GS12 of the converter full-bridge output voltage V AB To V EF , resonant capacitor voltage V cr1 To V cr3 And the resonant current i r1 to i r3 Timing when performing variable frequency control.

[0050] Figure 11C An n-layer stacked full-bridge resonant converter according to an embodiment of the present disclosure is shown.

[0051] Figure 11D An n-layer stacked full-bridge resonant converter with an integrated transformer in one embodiment of the present disclosure is shown.

[0052] Figure 11E An n-layer stacked full-bridge resonant converter according to an embodiment of the present disclosure is shown, which has active switches on the secondary side for achieving synchronous rectification and bidirectional operation.

[0053] Figure 12A A three-layer stacked half-bridge rectifier for a three-phase resonant converter having a star-connected transformer in one embodiment of the present disclosure is shown.

[0054] Figure 12B Shows the Figure 12A The switching control signals GS1 to GS6 of the converter, the primary resonant current i r1 to i r3 , secondary current is1 to i s3 , secondary blocking capacitor voltage V cs1 To V cs3 , output capacitor voltage V CO1 To V CO3 And the output voltage V O Timing when performing variable frequency control.

[0055] Figure 12C An n-layer stacked half-bridge rectifier used in an n-phase resonant converter and having a star-connected transformer in an embodiment of the present disclosure is shown.

[0056] Figure 12D An n-layer stacked half-bridge rectifier for an n-phase resonant converter with an integrated transformer in an embodiment of the present disclosure is shown, wherein the n-layer stacked half-bridge rectifier has a star-connected transformer.

[0057] Figure 12E An n-layer stacked active half-bridge rectifier for an n-phase resonant converter with a star-connected transformer is shown in one embodiment of the present disclosure, which is used to achieve synchronous rectification and bidirectional operation.

[0058] Figure 13A A three-layer stacked half-bridge rectifier for a three-phase resonant converter in one embodiment of the present disclosure is shown.

[0059] Figure 13B Shows the Figure 13A The switching control signals GS1 to GS6 of the converter, the primary resonant current i r1 to i r3 , secondary current i s1 to i s3 , output capacitor voltage V CO1 To V CO6 And the output voltage V O Timing when performing variable frequency control.

[0060] Figure 13C An n-layer stacked half-bridge rectifier for an n-phase resonant converter in one embodiment of the present disclosure is shown.

[0061] Figure 13D An n-layer stacked half-bridge rectifier for an n-phase resonant converter with an integrated transformer in one embodiment of the present disclosure is shown.

[0062] Figure 13E An n-layer stacked active half-bridge rectifier for an n-phase resonant converter in an embodiment of the present disclosure is shown.

[0063] Figure 14A A three-layer stacked full-bridge rectifier for a three-phase resonant converter in one embodiment of the present disclosure is shown.

[0064] Figure 14B An n-layer stacked full-bridge rectifier for an n-phase resonant converter in one embodiment of the present disclosure is shown.

[0065] Figure 14C An n-layer stacked full-bridge rectifier for an n-phase resonant converter with an integrated transformer in one embodiment of the present disclosure is shown.

[0066] Figure 14D An n-layer stacked active full-bridge rectifier for an n-phase resonant converter in one embodiment of the present disclosure is shown, which is used to achieve synchronous rectification and bidirectional operation.

[0067] Figure 15A A three-layer stacked series half-bridge rectifier used in a three-phase resonant converter in an embodiment of the present disclosure is shown.

[0068] Figure 15B An n-layer stacked series half-bridge rectifier for an n-phase resonant converter in one embodiment of the present disclosure is shown.

[0069] Figure 15C An n-layer stacked series half-bridge rectifier applied to an n-phase resonant converter with an integrated transformer in an embodiment of the present disclosure is shown.

[0070] Figure 15D An n-layer stacked series half-bridge rectifier used in an n-phase resonant converter according to an embodiment of the present disclosure is shown, which is used to achieve synchronous rectification and bidirectional operation.

[0071] Figure 16 A general stacked resonant converter according to an embodiment of the present disclosure is shown.

[0072] Figure 17 A universal stacked resonant converter according to an embodiment of the present disclosure is shown, which includes multiple circuits connected in parallel on both the primary side and the secondary side.

[0073] The description of the accompanying drawings is as follows:

[0074] S1, S2, S3, S4, S5, S6: switches

[0075] V AB :Voltage

[0076] f r : Resonant frequency

[0077] M: Voltage gain

[0078] N P 、N S : Number of turns

[0079] L r , Lr1 , L r2 , L r3 : Resonant inductor

[0080] C r 、C r1 、C r2 、C r3 : Resonant capacitor

[0081] f sw : Switching frequency

[0082] D1, D2, D3, D4, D5, D6: diodes

[0083] V in 、V O 、V C1 、V C2 、V C3 、V C4 、V C5 、V C6 :Voltage

[0084] L m , L m1 , L m2 , L m3 :inductance

[0085] C in 、C O 、C in1 、C in2 , C1, C2, C3, C4, C5, C6: capacitors

[0086] TR, TR1, TR2, TR3: Transformers

[0087] i Lr 、i Lm 、i r1 、i r2 、i r3 : Current

[0088] R: Load

[0089] GS1, GS2, GS3, GS4, GS5, GS6: control signals

[0090] 500: Converter

[0091] V AB 、V CD 、V EF : Input voltage

[0092] V cr1 、V cr2 、V cr3 :Voltage

[0093] 501, 502, 503: half-bridge arms

[0094] A, B, C, D, E, F, O: Point

[0095] 600: Converter

[0096] S7, S8, S9, S10, S11, S12: switches

[0097] GS7, GS8, GS9, GS10, GS11, GS12: control signal

[0098] 700: Converter

[0099] C (2n-1) 、C (2n) :capacitance

[0100] S (2n-1) 、S (2n) :switch

[0101] C r(n) : Resonant capacitor

[0102] L r(n) : Resonant inductor

[0103] L m(n) :inductance

[0104] TR n :transformer

[0105] D (2n-1) 、D (2n) :diode

[0106] S O1 、S O2 、S O3 、S O4 、S O(2n-1) 、S O(2n) :switch

[0107] 800: Converter

[0108] 801, 802, 803: Series half-bridge arms

[0109] 820: Three-phase diode bridge arm

[0110] C 1a 、C 1b 、C 2a 、C 2b 、C 3a 、C 3b 、C nb 、C nb :capacitance

[0111] S 1a 、S 1b 、S 1c 、S 1d 、S 2a 、S 2b 、S 2c 、S 2d 、S 3a 、S 3b 、S 3c 、S 3d 、S na 、S nb 、S nc 、S nd :switch

[0112] D 1a 、D 1b 、D 1c 、D 1d 、D 2a 、D 2b 、D 2c 、D 2d 、D 3a 、D 3b 、D 3c 、D 3d 、D na 、D nb 、D nc 、D nd :diode

[0113] GS1a, GS1b, GS1c, GS1d, GS2a, GS2b, GS2c, GS2d, GS3a, GS3b, GS3c, GS3d: Control signals

[0114] S O1a 、S O1b 、S O2a 、S O2b 、S Ona 、S Onb :switch

[0115] 1100: Converter

[0116] 1101, 1102, 1103: full bridge arms

[0117] 1120: Three-phase diode bridge arm

[0118] S (4n) 、S (4n-1) 、S (4n-2) 、S (4n-3) :switch

[0119] D (4n) 、D (4n-1) 、D (4n-2) 、D(4n-3) :diode

[0120] C r(1,1) 、C r(1,2) : Resonant capacitor

[0121] L r(1,1) 、L r(1,2) 、L r(n,m) : Resonant inductor

[0122] L m(1,1) 、L m(1,2) 、L m(n,m) :inductance

[0123] TR (1,1) , TR (1,2) , TR (n,m) :transformer DETAILED DESCRIPTION

[0124] Some typical embodiments that embody the features and advantages of the present disclosure will be described in detail in the following description. It should be understood that the present disclosure can have various changes in different aspects, which do not depart from the scope of the present disclosure, and the descriptions and illustrations therein are essentially used for illustrative purposes, rather than for limiting the present disclosure. For example, if the following disclosure of this specification describes forming a first feature on or above a second feature, it means that it includes an embodiment in which the formed first feature and the second feature are in direct contact, and also includes an embodiment in which an additional feature can be formed between the first feature and the second feature, so that the first feature and the second feature may not be in direct contact. In addition, different embodiments in the description of the present invention may use repeated reference symbols and / or words. These repeated symbols or words are for the purpose of simplicity and clarity, and are not used to limit the relationship between the various embodiments and / or the described appearance structures. Furthermore, in order to conveniently describe the relationship between an element or feature element and another (plural) element or (plural) feature element in the drawings, spatial relative terms may be used, such as "beneath", "below", "lower", "above", "upper" and similar terms. It is understood that in addition to the orientation shown in the drawings, spatial relative terms cover different orientations of the device in use or operation. The device may also be positioned differently (for example, rotated 90 degrees or located in other orientations), and the description of the spatial relative terms used should be interpreted accordingly. When an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or an additional element may be present therein. Although the numerical ranges and parameters of the broad scope of the present disclosure are approximate, the numerical values are stated as precisely as possible in the specific examples. While it is understood that terms such as "first," "second," and "third" may be used in the claims to describe various elements, these elements should not be limited by these terms. In the embodiments, the elements described accordingly are used to represent different reference numbers. These terms are merely used to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the embodiments. The terms "and / or" as used herein include any and all combinations of one or more of the associated listed aspects. Furthermore, numerical ranges or parameters inherently contain errors that occur in individual test measurements. Furthermore, when the terms "approximately" or "substantially" appear in this document, they generally mean within 10%, 5%, 1%, or 0.5% of a given value or range. Alternatively, the terms "approximately" or "substantially" mean within an acceptable error range for a person skilled in the art.Except in the examples of operation / work, or unless explicitly stated, all numerical ranges, amounts, values and percentages disclosed herein (such as the amount of materials disclosed herein, time, temperature, operating conditions, usage ratios and the like) should be understood as being modified by the term "about" or "substantially" in all embodiments. Accordingly, unless otherwise indicated, the numerical parameters stated in this disclosure and the appended claims are approximate values that may vary as needed. For example, each numerical parameter should be interpreted at least in accordance with the number of significant figures described and by applying ordinary rounding principles. Ranges can be expressed herein as from one endpoint to the other or between two endpoints. All ranges disclosed herein include endpoints unless otherwise specified.

[0125] A. Stacked Half-Bridge Resonant Converter

[0126] Three-layer stacked half-bridge resonant converter

[0127] Figure 5A A stacked half-bridge resonant converter 500 according to an embodiment of the present disclosure is shown. Figure 5B This shows an embodiment of the present disclosure Figure 5A The switching control signals GS1 to GS6 of the converter, the resonant cavity input voltage V AB 、V CD and V EF , resonant capacitor voltage V cr1 、V cr2 and V cr3 And the resonant current i r1 、i r2 and i r3 Timing when performing variable frequency control. Figure 5C This shows an embodiment of the present disclosure Figure 5A The switching control signals GS1 to GS6 of the converter, the resonant capacitor voltage V cr1 To V cr3 And the resonant current i r1 to i r3 Timing when performing variable duty cycle control.

[0128] In this embodiment, a DC-DC converter 500 includes a primary side, a secondary side, a control circuit, a transformer stage, and at least one resonant cavity circuit, wherein the transformer stage is electrically connected to the primary side and the secondary side, and the resonant cavity circuit is electrically connected between the primary side and the transformer stage. The primary side includes at least two half-bridge inverter units 501, 502, and 503 stacked in series (i.e., half-bridge arms 501, 502, and 503). The inverter unit 501 includes two active switches S1 and S2 connected in series and two input capacitors C1 and C2 connected in series, wherein the arm containing the two active switches S1 and S2 is connected in parallel to the arm containing the two input capacitors C1 and C2. The inverter unit 502 includes two active switches S3 and S4 connected in series and two input capacitors C3 and C4 connected in series, wherein the arm containing the two active switches S3 and S4 is connected in parallel to the arm containing the two input capacitors C3 and C4. The inverter unit 503 includes two active switches S5 and S6 connected in series and two input capacitors C5 and C6 connected in series. The bridge arm containing the two active switches S5 and S6 is connected in parallel with the bridge arm containing the two input capacitors C5 and C6. In this embodiment, the transformer stage includes a first transformer TR1, a second transformer TR2, and a third transformer TR3. The at least one resonant cavity circuit includes a first resonant cavity circuit, a second resonant cavity circuit, and a third resonant cavity circuit. In this embodiment, each of the first transformer TR1, the second transformer TR2, and the third transformer TR3 includes a transformer core and primary and secondary windings wound around the transformer core. The control circuit architecture is configured to actuate the active switches S1, S2, S3, S4, S5, and S6 to change the pulse frequency, pulse width, or phase shift angle of the voltage or current across the inverter unit or rectifier circuit elements.

[0129] It should be noted that the terms “rectifier”, “rectifier circuit element” and “rectifier unit” mentioned in this disclosure have the same actual meaning in some embodiments, and all refer to components that can be used to provide rectification function.

[0130] The converter 500 includes three half-bridge inverter units 501, 502, and 503 stacked on the primary side and six input capacitors C1, C2, C3, C4, C5, and C6 stacked on each other, wherein the three half-bridge inverter units 501, 502, and 503 include switches S1 to S6. Figure 5A As shown, the first half-bridge inverter unit 501 includes switches S1 and S2 connected in series and input capacitors C1 and C2 connected in series. Switches S1 and S2 are connected in series with input capacitors C2 and C1 to form a first circuit loop. Point A between switches S1 and S2 is connected to one end of the first resonant cavity, where the first resonant cavity includes a resonant capacitor C r1 and resonant inductor L r1The other end of the first resonant cavity is connected to one end of the primary winding of the transformer TR1. The other end of the primary winding of the transformer TR1 is connected to point B between the input capacitors C1 and C2.

[0131] Similarly, if Figure 5A As shown, the second half-bridge inverter unit 502 includes switches S3 and S4 connected in series and input capacitors C3 and C4 connected in series. Switches S3 and S4 and input capacitors C4 and C3 are connected in series to form a second circuit loop. Point C between switches S3 and S4 is connected to one end of the second resonant cavity, where the second resonant cavity includes a resonant capacitor C r2 and resonant inductor L r2 The other end of the second resonant cavity is connected to one end of the primary winding of the transformer TR2. The other end of the primary winding of the transformer TR2 is connected to point D between the input capacitors C3 and C4.

[0132] Furthermore, if Figure 5A As shown, the second half-bridge inverter unit 503 includes switches S5 and S6 connected in series and input capacitors C5 and C6 connected in series. Switches S5 and S6 and input capacitors C6 and C5 are connected in series to form a third circuit loop. Point E between switches S5 and S6 is connected to one end of the third resonant cavity, where the third resonant cavity includes a resonant capacitor C r3 and resonant inductor L r3 The other end of the third resonant cavity is connected to one end of the primary winding of the transformer TR3. The other end of the primary winding of the transformer TR3 is connected to point F between the input capacitors C5 and C6.

[0133] In summary, in this embodiment, three independent transformers TR1, TR2, and TR3 are used. One end of the primary winding of each transformer is connected to a corresponding resonant cavity, where the resonant cavity is connected to the midpoint between the corresponding switches. The other end of the primary winding of each transformer is coupled to the midpoint between the corresponding input capacitors.

[0134] In some embodiments, the first terminal of the first half-bridge inverter unit 501 (located between the switch S1 and the input capacitor C1) is connected to the input voltage V in The positive electrode of the first half-bridge inverter unit 501, the second end (located between the switch S2 and the input capacitor C2) is connected to the first end (located between the switch S3 and the input capacitor C3) of the second half-bridge inverter unit 502. The second end (located between the switch S4 and the input capacitor C4) of the second half-bridge inverter unit 502 is connected to the first end (located between the switch S5 and the input capacitor C5) of the third half-bridge inverter unit 503. The second end (located between the switch S6 and the input capacitor C6) of the third half-bridge inverter unit 503 is connected to the input voltage V inIn other words, the first, second and third half-bridge inverter units 501, 502 and 503 are vertically stacked to form a stacked half-bridge arm, wherein each half-bridge arm forms a circuit loop.

[0135] In some embodiments, the secondary side includes at least two sets of rectifier circuit elements, wherein each set of rectifier circuit elements is coupled to a secondary winding of a transformer, and the secondary winding and the corresponding primary winding share the transformer core. The rectifier circuit elements are configured to rectify the induced current generated on the secondary side due to the current flowing through the corresponding primary winding. The secondary side voltage V o In some embodiments, a conventional three-phase diode bridge leg (including diodes D1, D2, D3, D4, D5, and D6) is disposed on the secondary side to provide a rectification function.

[0136] Variable switching frequency control for three-layer stacked half-bridge resonant converter

[0137] Figure 5B This shows an embodiment of the present disclosure Figure 5A The switch control signals GS1 to GS6 of the converter 500, the resonant cavity input voltage V AB 、V CD and V EF , resonant capacitor voltage V cr1 、V cr2 and V cr3 And the resonant current i r1 、i r2 and i r3 Timing of variable frequency control. Switch control signals GS1 to GS6 are control signals for switches S1 to S6, respectively. In this embodiment, variable switching frequency control is used to adjust the output voltage and output power of the stacked half-bridge resonant converter 500.

[0138] like Figure 5B As shown, all switches operate at the same switching frequency (e.g., 100kHz) and have the same duty cycle of approximately 50%. In order to achieve zero voltage switching of the complementary primary-side switches in the same bridge leg, a small dead time is introduced between the turn-on and turn-off moments of the complementary switches. The switch control signals in each half-bridge leg are interleaved with a phase shift of 120 degrees. For example, the phases of the switch control signals GS1 and GS2 are shifted by 120 degrees relative to the phases of the switch control signals GS3 and GS4. In this embodiment, the resonant cavity input voltage V AB 、V CD and V EF is a square wave without DC bias. Similarly, the resonant capacitor voltage V cr1 、V cr2 and V cr3is a sine wave without DC bias. If the resonant converter operates at its resonant frequency and the excitation current is negligible, the resonant current i of all three resonant cavities is r1 、i r2 and i r3 All are pure sine waves. Because the switching control signals are interleaved, the resonant currents interleave with a 120-degree phase shift. This interleaved current generates minimal ripple on the components, further improving converter performance.

[0139] Pulse width modulation (PWM) for stacked half-bridge resonant converters

[0140] If a wide input voltage range and / or a wide output voltage range are required in certain applications (e.g., battery charging applications), variable switching frequency control alone may not be able to achieve the desired gain range. In such cases, PWM or variable duty cycle control can be used to adjust the resonant tank gain when the switching frequency control reaches its upper limit.

[0141] Figure 5C This shows an embodiment of the present disclosure Figure 5A The switching control signals GS1 to GS6 of the converter 500, the resonant capacitor voltage V cr1 To V cr3 And the resonant current i r1 to i r3 The timing of variable duty cycle control. The switch control signals GS1 to GS6 are the control signals of switches S1 to S6 respectively. Figure 5C As shown, the switching control signals in each half-bridge leg are interleaved with a 120-degree phase shift. For example, the phase of the switching control signals GS1 and GS2 in the first half-bridge inverter unit 501 is offset by a 120-degree phase shift from the phase of the switching control signals GS3 and GS4 in the second half-bridge inverter unit 502. The duty cycle of the switching control signals GS1 to GS6 is reduced from the rated 50% to 40% to further reduce the output voltage. In this modulation, the resonant current i r1 to i r3 May become discontinuous.

[0142] Phase shift modulation of stacked half-bridge resonant converter

[0143] Figure 6A A stacked half-bridge LLC resonant converter 600 according to an embodiment of the present disclosure is shown, which has active switches S7 to S12 on the secondary side for achieving bidirectional operation. Figure 6A The converter 600 with Figure 5A The converter 500 is substantially the same as Figure 5A Converter 500, Figure 6A The converter 600 replaces the diode with three active half-bridge legs connected in parallel on the secondary side to achieve bidirectional operation, wherein the three active half-bridge legs include switches S7 to S12.

[0144] Figure 6B This shows an embodiment of the present disclosure Figure 6A The switching control signals GS1 to GS12 of the converter 600, the resonant capacitor voltage V cr1 To V cr3 And the resonant current i r1 to i r3 The timing sequence of variable frequency control and phase shift control. The switch control signals GS1 to GS12 are control signals of switches S1 to S12 respectively.

[0145] Variable switching frequency control is commonly used to regulate the output voltage and output power of a resonant converter. If a wide input voltage range and / or a wide output voltage range are required in certain applications (e.g., battery charging applications), variable switching frequency control alone may not be able to achieve the required gain range. In this case, phase shift modulation can be used to achieve a wide input voltage range and / or a wide output voltage range as well as bidirectional operation. Figure 6B As shown, all switches operate at the same switching frequency and have the same duty cycle of approximately 50%. To achieve zero-voltage switching of the complementary primary-side switches in the same leg, a small dead time can be introduced between the turn-on and turn-off instants of the complementary switches.

[0146] On the primary side, the switch control signals in each half-bridge arm are interleaved with a phase shift of approximately 120 degrees. On the secondary side, the switch control signals in each half-bridge arm are also interleaved with a phase shift of approximately 120 degrees. In addition, in some embodiments, there is a phase shift between the control signal of the first bridge arm on the primary side and the control signal of the first bridge arm on the secondary side. This phase shift angle becomes another key control variable in addition to the switching frequency. In other words, the output voltage and power are controlled by the switching frequency and the phase shift angle. In this embodiment, the primary side circuit structure is such that the resonant capacitor voltage V cr1 To V cr3 There is no DC bias in the circuit. Since the switch control signals are interleaved, the resonant current i r1 to i r3 The phases of the two phases are interleaved by 120 degrees. This interleaving of the currents produces minimal ripple on the components, further improving converter performance.

[0147] n-layer stacked half-bridge resonant converter

[0148] Figure 7AFIG. 7 shows an n-layer stacked half-bridge resonant converter 700 according to an embodiment of the present disclosure. The converter 700 uses n stacked half-bridge arms on the primary side, wherein the n half-bridge arms include 2n switches S1 to S2. (2n) and 2n input capacitors C1 to C (2n) . n is a natural number, and its size corresponds to the phase or number of resonant cavities of the converter 700. The midpoint of each half-bridge arm is connected to a resonant cavity including a resonant capacitor and a resonant inductor. A total of n phase-independent transformers are provided in the converter 700, wherein each transformer has a primary side winding and a secondary side winding. The first end of the primary side winding of each transformer is connected to the midpoint between the corresponding input capacitors, and the second end of the primary side winding of each transformer is connected to the other end of the corresponding resonant cavity. In addition, a total of n half-wave diode bridge arms connected in parallel with each other are provided in the converter 700 for rectification on the secondary side.

[0149] The variable switching frequency control can be used to adjust the output voltage and output power of the resonant converter 700. The switches S1 to S (2n) They operate at the same switching frequency and have the same duty cycle of approximately 50%. To achieve zero-voltage switching for the complementary primary-side switches in the same half-bridge leg, a small dead time is introduced between the turn-on and turn-off times of the complementary switches. The switch control signals in each half-bridge leg are interleaved with a phase shift of 360 / n degrees, where n represents the number of phases in converter 700. When resonant converter 700 operates at its resonant frequency, the resonant currents in all resonant cavities are sinusoidal if the magnetizing current is negligible. Because the switching control signals are interleaved, the resonant currents are interleaved with a phase shift of 360 / n degrees. This interleaved current generates minimal ripple in the components, further improving converter performance.

[0150] n independent transformers can be integrated into a number of transformers less than n. For example, Figure 7B An n-layer stacked half-bridge resonant converter 700 employing only one integrated transformer is shown, wherein the integrated transformer has a total of n windings on the primary side and a total of n windings on the secondary side.

[0151] Figure 7C FIG. 7 shows an n-layer stacked half-bridge resonant converter 700 having active switches on the secondary side for achieving synchronous rectification and bidirectional operation. Figure 7C As shown, it is based on 2n active switches S O1 To S O(2n) replace Figure 7A and Figure 7B 2n diodes on the secondary side enable synchronous rectification to improve operating efficiency. In this case, the resonant converter can also provide bidirectional power flow through active switching.

[0152] All control methods disclosed in this disclosure are applicable to an n-layer stacked half-bridge resonant converter.

[0153] B. Stacked Series Half-Bridge Resonant Converter

[0154] Three-layer stacked series half-bridge resonant converter

[0155] Figure 8A FIG. 8 shows a three-layer stacked series half-bridge resonant converter 800 with a three-phase diode bridge rectifier in one embodiment of the present disclosure. The resonant converter 800 includes three stacked series half-bridge inverter units 801, 802, and 803 to replace Figure 5A The stacked half-bridge resonant converter 500 includes half-bridge inverter units 501, 502, and 503 as basic components. In the series-connected half-bridge inverter units 801, 802, and 803, each series-connected half-bridge inverter unit includes two half-bridge arms (i.e., an upper half-bridge arm and a lower half-bridge arm) connected in series to form a stacked structure.

[0156] like Figure 8A As shown, the first series half-bridge inverter unit 801 includes four active switches S 1a 、S 1b 、S 1c and S 1d And two input capacitors C 1a and C 1b The switch S that constitutes the upper half of the bridge arm 1a and S 1b With input capacitor C 1a The switches S forming the lower half bridge arm are connected in parallel to form a circuit loop. 1c and S 1d With input capacitor C 1b are connected in parallel to form another circuit loop. Similarly, the second series half-bridge inverter unit 802 includes four active switches S 2a 、S 2b 、S 2c and S 2d And two input capacitors C 2a and C 2b The switch S that constitutes the upper half of the bridge arm 2a and S 2b With input capacitor C 2a The switches S forming the lower half bridge arm are connected in parallel to form a circuit loop. 2c and S 2d With input capacitor C 2b In addition, the third series half-bridge inverter unit 803 includes four active switches S 3a 、S 3b 、S 3c and S3d And two input capacitors C 3a and C 3b The switch S that constitutes the upper half of the bridge arm 3a and S 3b With input capacitor C 3a The switches S forming the lower half bridge arm are connected in parallel to form a circuit loop. 2c and S 2d With input capacitor C 2b Connect in parallel to form another circuit loop.

[0157] like Figure 8A As shown, the midpoint (i.e., point A) of the upper half-bridge arm of the first series half-bridge inverter unit 801 is connected to a resonant cavity, wherein the resonant cavity includes a series-connected resonant capacitor C r1 and resonant inductor L r1 The midpoint of the upper half-bridge arm of the second series half-bridge inverter unit 802 (i.e., point C) is connected to a resonant cavity, wherein the resonant cavity includes a series-connected resonant capacitor C r2 and resonant inductor L r2 The midpoint of the upper half-bridge arm of the third series half-bridge inverter unit 803 (ie, point E) is connected to a resonant cavity, wherein the resonant cavity includes a series-connected resonant capacitor C r3 and resonant inductor L r3 .

[0158] In this embodiment, three independent phase transformers, TR1, TR2, and TR3, are used. Each transformer has a primary winding and a secondary winding. The first end of each transformer's primary winding is connected to the midpoint of the lower half-bridge arm of the corresponding series-connected half-bridge inverter unit (i.e., point B, D, or F). The second end of each transformer's primary winding is coupled to the other side of the corresponding resonant cavity. A parallel three-phase diode bridge leg 820 performs secondary-side rectification.

[0159] Variable switching frequency control can be used to adjust the output voltage and output power of the stacked series half-bridge resonant converter 800 . Figure 8B Shows the Figure 8A The switch control signals GS1 to GS6 of the converter 800, the full-bridge output voltage V AB To V EF , resonant capacitor voltage V cr1 To V cr3 And the resonant current i r1 to i r3 The timing when performing variable frequency control. Figure 8BAs shown, all switches operate at the same switching frequency and have the same duty cycle of approximately 50%. To achieve zero voltage switching of the complementary primary-side switches in the same bridge arm, a small dead time is introduced between the turn-on and turn-off moments of the complementary switches. The switch control signals in each series half-bridge inverter unit are interleaved with a phase shift angle of 120 degrees. The peak-to-peak output voltage of each series half-bridge inverter unit is 1 / 3 of the input voltage. The resonant capacitor voltage v cr1 to v cr3 With a DC bias voltage equal to 1 / 6 of the input voltage, the resonant currents in all three resonant cavities are sinusoidal if the magnetizing current is negligible. Because the switching control signals are interleaved, the resonant currents interleave with a 120-degree phase shift. This interleaved current generates minimal ripple in the components, further improving converter performance.

[0160] Figure 8C FIG. 8 shows a three-layer stacked series half-bridge resonant converter 800 according to an embodiment of the present disclosure, which has three full-wave diode bridge arms 830 connected in parallel for rectification. Figure 8B As shown, to reduce Figure 8B The current stress of the secondary side diode is to set up three full-wave diode bridge arms on the secondary side. The control signal of the primary side switch is Figure 8B Same as shown in .

[0161] n-layer stacked series half-bridge resonant converter

[0162] Figure 9A The n-layer stacked series half-bridge resonant converter 900 according to an embodiment of the present disclosure is shown, which has n full-wave diode bridge legs connected in parallel for rectification. The resonant converter 900 includes n stacked series half-bridge bridge legs, wherein each series half-bridge bridge leg includes two half-bridge bridge legs connected in series. The mth series half-bridge bridge leg includes four active switches S ma 、S mb 、S mc and S md And two input capacitors C ma and C mb -, where m can be any positive integer not greater than n. One of the two midpoints of the mth series half-bridge arm is connected to the resonant cavity, where the resonant cavity includes a series-connected resonant capacitor C rm and resonant inductor L rmConverter 900 includes n independent transformers, each with a primary winding and a secondary winding. The first end of each transformer's primary winding is connected to the other midpoint of the corresponding series half-bridge leg, and the second end of each transformer's primary winding is connected to the other side of the corresponding resonant cavity. The n half-wave diode legs connected in parallel provide secondary-side rectification.

[0163] Variable switching frequency control can be used to adjust the output voltage and output power of the stacked series half-bridge resonant converter 900. All switches operate at the same switching frequency and have the same duty cycle of approximately 50%. To achieve zero-voltage switching of the complementary primary-side switches in the same leg, a small dead time is introduced between the turn-on and turn-off times of the complementary switches. The switch control signals in each series half-bridge leg are interleaved with a phase shift of 360 / n degrees. For example, the four control signals in the first series half-bridge leg are interleaved with the four control signals in the second series half-bridge leg with a phase shift of 360 / n degrees. When the resonant converter 900 operates at its resonant frequency, if the excitation current is negligible, the resonant currents in all n resonant cavities are sinusoidal. Because the switching control signals are interleaved, the resonant currents are interleaved with a phase shift of 360 / n degrees. This interleaved current generates minimal ripple on the components, further improving converter performance.

[0164] n independent transformers can be integrated into a number of transformers less than n. For example, Figure 9B An n-layer stacked series half-bridge resonant converter with an integrated transformer in one embodiment of the present disclosure is shown.

[0165] Figure 9B All secondary-side diodes in the MOSFET can be replaced with active switches to perform synchronous rectification and improve converter efficiency. The resonant converter 900 can provide bidirectional power flow through active switches on both the input and output sides. Figure 9C FIG1 shows an n-layer stacked series half-bridge resonant converter according to an embodiment of the present disclosure, which has an active switch on the secondary side for realizing synchronous rectification and bidirectional operation. Figure 9C As shown, it is replaced by 2n active switches Figure 9B 2n diodes on the secondary side.

[0166] Figure 9D The present invention shows an n-layer stacked series half-bridge resonant converter according to an embodiment of the present invention, which has n full-wave diode bridge arms connected in parallel for rectification. A total of n full-wave diode bridge arms (i.e., a total of 4n diodes) are provided on the secondary side to reduce Figure 9A The current stress on the secondary side diode in the primary side switch. The control signal of the primary side switch is Figure 9AIn this embodiment, the transformer can also be integrated and the diode in the secondary side can be replaced by an active switch.

[0167] C. Input capacitor voltage balance control method

[0168] Voltage balancing control method for stacked half-bridge resonant converter

[0169] One challenge in operating a stacked half-bridge resonant converter is how to balance the input capacitor voltages when mismatches occur in a practical circuit, such as capacitor equivalent series resistance (ESR) mismatch, switch gate signal timing mismatch, or resonant parameter mismatch within a practical tolerance range.

[0170] There are several possible ways to balance the input capacitor voltage in different primary-side stack configurations. The first is to adjust the duty cycle of the switch control signal. Figure 10A In one embodiment of the present disclosure, Figure 7A Schematic diagram of voltage balance control based on duty cycle of stacked half-bridge resonant converter. The voltages of the two capacitors of the mth half-bridge unit are sensed and used as V Cma and V Cmb Calculate the average value of the capacitor voltage of each half bridge unit and compare it with the reference voltage V R When the difference is greater than the preset threshold voltage V th When the duty cycle is adjusted appropriately, a dedicated controller is used to generate the duty cycle and use it to balance the capacitor voltage. Figures 4A-4B Since each half-bridge unit is coupled to only one input capacitor, the capacitor voltage can be directly sensed and compared with a reference voltage. Figure 10B FIG2 is a schematic diagram of duty cycle-based voltage balancing control for a stacked half-bridge resonant converter with a star-connected transformer according to an embodiment of the present disclosure.

[0171] Another way is to adjust the phase shift angle between the control signals of each half bridge unit. Ideally, the phase shift angle between the control signals of each half bridge unit is 360 / n degrees. When the voltage imbalance sensed by the sensing circuit is greater than the preset threshold voltage V th When , a properly adjusted duty cycle can be used in each phase bridge arm to balance the capacitor voltage by changing the power transferred from each phase capacitor to the resonant cavity.

[0172] Figure 10C FIG. 1 is a flow chart of voltage balancing control based on phase shift for a three-layer stacked half-bridge resonant converter according to an embodiment of the present disclosure. Figure 10CAs shown, the voltage of six input capacitors is sensed and the unbalanced voltage ΔV in each phase is calculated. A , ΔV B and ΔV C If any unbalanced voltage is greater than the threshold voltage V th , then an appropriately adjusted duty cycle is used in each phase bridge arm.

[0173] Figure 10D This is a flow chart of voltage balance control based on phase shift for a three-layer stacked half-bridge resonant converter with a star-connected transformer in one embodiment of the present disclosure. Figure 10D As shown, the voltage on the three input capacitors is sensed and the unbalanced voltage ΔV in each phase is calculated. A , ΔV B and ΔV C If any unbalanced voltage is greater than the threshold voltage V th , then an appropriately adjusted duty cycle is used in each phase bridge arm.

[0174] Voltage balancing control method for stacked series half-bridge resonant converter

[0175] A hybrid control method is used to balance the input capacitor voltage of a stacked series half-bridge resonant converter, which includes two control loops. Figure 10E This is a flow chart of a hybrid voltage balancing control scheme for a stacked half-bridge resonant converter according to one embodiment of the present disclosure. The first control loop of the hybrid control scheme is an internal voltage balancing loop within each series-connected half-bridge unit. The first control loop is designed to balance the voltages of the two capacitors within each unit. The voltages of the two capacitors in each series-connected half-bridge unit are sensed and compared. If the voltage difference between the two capacitors is greater than a predetermined threshold voltage V th , a dedicated controller generates a phase shift angle command to adjust the phase shift angle between the switching control signals of the first and second half-bridge legs. In other words, each series-connected half-bridge cell has an internal phase shift angle between the switching signals of its first and second half-bridge legs, where the phase shift angle is calculated based on the voltage difference between the first input capacitor voltage and the second input capacitor voltage.

[0176] The second control loop in the hybrid control scheme is an external voltage balancing loop between all series-connected half-bridge cells. This second control loop is designed to balance the average capacitor voltage of each battery. The voltages of the two capacitors in each series-connected half-bridge cell are sensed, and the average voltage across each cell is calculated. This average voltage is then compared with a reference voltage. If the voltage difference exceeds a preset threshold voltage, a dedicated controller generates an additional duty cycle. This generated additional duty cycle is implemented in all four switch control signals in the corresponding series-connected half-bridge cell. In other words, each series-connected half-bridge cell has its own additional duty cycle, calculated based on the voltage difference between its average capacitor voltage and the reference voltage.

[0177] D. Stacked Full-Bridge Resonant Converter

[0178] Three-layer stacked full-bridge resonant converter

[0179] Figure 11A A three-layer stacked full-bridge resonant converter 1100 according to one embodiment of the present disclosure is shown. Converter 1100 utilizes three stacked full-bridge inverter units 1101, 1102, and 1103, along with three series-connected input capacitors C1 to C3 to block DC input voltages. In this embodiment, three independent transformers TR1, TR2, and TR3 are used, each with a primary winding and a secondary winding.

[0180] like Figure 11A As shown, the first full-bridge inverter unit 1101 includes four switches S1, S2, S3 and S4. A point A between switches S1 and S3 is connected to one end of the resonant cavity, where the resonant cavity includes a resonant capacitor C connected in series. r1 and resonant inductor L r1 A first end of the primary winding of the transformer TR1 is connected to the other side of the resonant cavity. A second end of the primary winding of the transformer TR1 is connected to point B between switches S2 and S4.

[0181] Similarly, the second full-bridge inverter unit 1102 includes four switches S5, S6, S7, and S8. A point C between switches S5 and S7 is connected to one end of the resonant cavity, where the resonant cavity includes a resonant capacitor C connected in series. r2 and resonant inductor L r2 A first end of the primary winding of the transformer TR2 is connected to the other side of the resonant cavity. A second end of the primary winding of the transformer TR2 is connected to point D between switches S6 and S8.

[0182] Furthermore, the third full-bridge inverter unit 1103 includes four switches S9, S 10 、S 11 and S 12 . Switches S9 and S 11The point E between them is connected to one end of the resonant cavity, where the resonant cavity includes a resonant capacitor C connected in series. r3 and resonant inductor L r3 The first end of the primary winding of the transformer TR3 is connected to the other side of the resonant cavity. The second end of the primary winding of the transformer TR3 is connected to the switch S 10 and S 12 Point F between them.

[0183] The parallel three-phase diode bridge leg 1120 performs secondary-side rectification, which is coupled to the secondary-side windings of the three transformers TR1 , TR2 , and TR3 .

[0184] Variable switching frequency control can be used to adjust the output voltage and output power of the three-layer stacked full-bridge resonant converter. Figure 11A The switching control signals GS1 to GS12 of the converter full-bridge output voltage V AB To V EF , resonant capacitor voltage V cr1 To V cr3 And the resonant current i r1 to i r3 Timing for variable frequency control. As shown in Figure 11B, all switches operate at the same switching frequency and have the same duty cycle of approximately 50%. In order to achieve zero voltage switching of the complementary primary side switches in the same bridge arm, a small dead time can be introduced between the turn-on and turn-off moments of the complementary switches. The switch control signals of each full-bridge inverter unit are interleaved with a phase shift of 120 degrees. For example, the switch control signals GS1 and GS4 have a phase shift angle of 120 degrees relative to the switch control signals GS5 and GS8. Since each transformer is directly connected to the corresponding resonant cavity, the resonant cavity input voltage V AB 、V CD and V EF There is no DC bias in the resonant capacitor. Similarly, the resonant capacitor voltage V cr1 、V cr2 and V cr3 There is no DC bias in the resonant converter. If the resonant converter operates at its resonant frequency and the magnetizing current is negligible, the resonant currents in all three resonant cavities are pure sinusoidal. Because the switching control signals are interleaved, the resonant currents interleave with a 120-degree phase shift. This interleaving of currents produces minimal ripple in the components, further improving converter performance.

[0185] n-layer stacked full-bridge resonant converter

[0186] Figure 11C An n-layer stacked full-bridge resonant converter according to an embodiment of the present disclosure is shown. Figure 11CThe converter in FIG1 uses n full-bridge arms stacked on top of each other and n input capacitors C1 to C2 connected in series. n , thereby blocking the DC input voltage. One of the two midpoints of each full-bridge leg is connected to a corresponding resonant cavity, which contains a resonant capacitor and a resonant inductor connected in series. The converter comprises n independent transformers, each with a primary winding and a secondary winding. The first end of each transformer's primary winding is connected to the other midpoint of the corresponding full-bridge leg, and the second end of each transformer's primary winding is connected to the other side of the corresponding resonant cavity. The n half-wave diode legs connected in parallel provide secondary-side rectification.

[0187] Variable switching frequency control can be used to regulate the output voltage and output power of an n-layer stacked full-bridge resonant converter. All switches operate at the same switching frequency and have the same duty cycle of approximately 50%. To achieve zero-voltage switching of the complementary primary-side switches in the same leg, a small dead time is introduced between the turn-on and turn-off times of the complementary switches. The switch control signals in each full-bridge leg are interleaved with a phase shift of 360 / n degrees. When the resonant converter operates at its resonant frequency, if the magnetizing current is negligible, the resonant currents in all n resonant cavities are sinusoidal. Because the switching control signals are interleaved, the resonant currents are interleaved with a phase shift of 360 / n degrees. This interleaving of the currents produces minimal ripple in the components, further improving converter performance.

[0188] N independent transformers can be integrated into a number less than n transformers to reduce the complexity of the underlying system. For example, Figure 11D shows an n-layer stacked full-bridge resonant converter with a single integrated transformer in accordance with an embodiment of the present disclosure, where the integrated transformer has a total of n windings on the primary side and a total of n windings on the secondary side.

[0189] Figure 11E FIG1 shows an n-layer stacked full-bridge resonant converter according to an embodiment of the present disclosure, which has an active switch on the secondary side for realizing synchronous rectification and bidirectional operation. Figure 11E As shown in Figure 1, 2n active switches replace 2n diodes to achieve synchronous rectification and improve operating efficiency. The resonant converter can provide bidirectional power flow through active switches on the input and output sides.

[0190] Stacked half-bridge rectifier with star-connected transformer

[0191] Figure 12AA three-layer stacked half-bridge rectifier with a star-connected transformer for use in a three-phase resonant converter according to one embodiment of the present disclosure is shown. In this embodiment, the three-phase resonant converter includes a primary side, a secondary side, a transformer stage, a control circuit, and at least one resonant tank circuit. The transformer stage is electrically coupled between the primary and secondary sides, and the resonant tank circuit is electrically connected between the primary and secondary sides. In this embodiment, the transformer stage includes a first transformer TR1, a second transformer TR2, and a third transformer TR3. The at least one resonant tank circuit includes a first resonant tank circuit, a second resonant tank circuit, and a third resonant tank circuit. In this embodiment, each of the first transformer TR1, the second transformer TR2, and the third transformer TR3 includes a transformer core and primary and secondary windings wound around the transformer core. The primary side includes at least two half-bridge inverter units stacked in series, wherein each half-bridge inverter unit includes two active switches (i.e., S1 and S2, S3 and S4, or S5 and S6) connected in series and an input capacitor (i.e., C1, C2, or C3). The bridge arms where the two active switches are located are connected in parallel with the bridge arm where the input capacitor is located to jointly form a first loop. Each half-bridge inverter unit is sequentially connected to the corresponding resonant cavity circuit, the first end of the primary winding of the corresponding transformer, the second end of the primary winding, and a common star connection point (i.e., point O) of the two half-bridge inverter units from a point between the two active switches, wherein the first end of any half-bridge inverter unit is connected to all bridge arms in the first loop, and the first end of any half-bridge inverter unit is directly connected to the second end of the corresponding stacked half-bridge inverter unit. A primary-side voltage V is applied or generated between the first and second ends of all half-bridge inverter units that are not connected to another half-bridge inverter unit. in . The half-bridge inverter unit can share the transformer core. In some embodiments, the transformer cores of transformers TR1, TR2 and TR3 can be integrated so that the half-bridge inverter unit shares the transformer core. The secondary side includes at least two groups of rectifier circuit elements, wherein each group of rectifier circuit elements is coupled to the secondary side winding of the transformer, and the secondary side winding and the corresponding primary side winding share the transformer core. The rectifier circuit element structure is used to rectify the induced current generated on the secondary side due to the current flowing through the corresponding primary side winding. The secondary side voltage V o is generated or applied in the secondary side.

[0192] The resonant rectifier uses three stacked half-bridge legs (including diodes D1 to D6) on the secondary side. The first diode leg including diodes D1 and D2 and the first output capacitor C O1 The second diode bridge arm including diodes D3 and D4 and the second output capacitor C O2 The third diode bridge arm including diodes D5 and D6 and the third output capacitor C O3 Connect in parallel. Output capacitor C O1 、CO2 and C O3 connected in series to provide an output voltage V O The midpoint of the first diode bridge arm, which includes diodes D1 and D2, is connected to the load R by a blocking capacitor C. s1 Connected to one end of the secondary winding of the first transformer TR1. The midpoint of the second diode bridge arm including diodes D3 and D4 is connected to the secondary winding of the first transformer TR1 through a blocking capacitor C s2 Connected to one end of the secondary winding of the second transformer TR2. The midpoint of the third diode bridge arm including diodes D5 and D6 is connected to the secondary winding of the second transformer TR2 through a blocking capacitor C s3 Connected to one end of the secondary winding of the third transformer TR3. The other end of each transformer's secondary winding is connected to form point P, which is defined as the transformer adopting star connection. Blocking capacitor C s1 、C s2 and C s3 The architecture is used to establish the DC bias voltage required for the normal operation of the rectifier.

[0193] Variable switching frequency control can be used to adjust the output voltage and output power of the stacked half-bridge resonant converter having three-layer stacked half-bridge rectifiers in one embodiment of the present disclosure. Figure 12B Shows the Figure 12A The switching control signals GS1 to GS6 of the converter, the primary resonant current i r1 to i r3 , secondary current i s1 to i s3 , secondary blocking capacitor voltage V cs1 To V cs3 , output capacitor voltage V CO1 To V CO3 And the output voltage V O Timing sequence when variable frequency control is performed. The secondary current i of the transformer s1 to i s3 It is a sine wave and is in resonance with the primary current i r1 to i r3 In phase. Blocking capacitor C s1 With positive DC bias, blocking capacitor C s3 With negative DC bias, blocking capacitor C s2 As shown in Figure 12B, the three output capacitor voltages V CO1 To V CO3 It is in a self-balancing state. The output voltage is three times the voltage of any output capacitor.

[0194] Figure 12C An n-layer stacked half-bridge rectifier having a star-connected transformer and used in an n-phase resonant converter according to an embodiment of the present disclosure is shown. Figure 12CIn this example, n half-bridge legs are stacked together to form the rectifier stage of an n-layer stacked half-bridge resonant converter. The output voltage is n times the voltage of any output capacitor.

[0195] n independent transformers can be integrated into a number of transformers less than n. For example, Figure 12D FIG. 1 shows an n-layer stacked half-bridge rectifier for an n-phase resonant converter with an integrated transformer in an embodiment of the present disclosure, which has a transformer with a star connection. Figure 12D As shown, the n-layer stacked half-bridge rectifier uses only one integrated transformer, wherein the integrated transformer has a total of n windings on the primary side and a total of n windings on the secondary side.

[0196] Figure 12E An n-layer stacked active half-bridge rectifier for an n-phase resonant converter with a star-connected transformer is shown in one embodiment of the present disclosure, which is used to achieve synchronous rectification and bidirectional operation. Figure 12E In this topology, active switches replace all diodes in an n-layer stacked half-bridge rectifier to achieve synchronous rectification. The resonant converter provides bidirectional power flow. Phase-shift modulation, which is common in stacked half-bridge resonant converters, can also be applied to this topology.

[0197] Stacked half-bridge rectifier

[0198] Figure 13A A three-layer stacked half-bridge rectifier for a three-phase resonant converter in one embodiment of the present disclosure is shown. Figure 13A The resonant rectifier in the circuit uses three stacked half-bridge legs (including diodes D1 to D6) on the secondary side. The first diode leg including diodes D1 and D2 and two output capacitors C O1 and C O2 The second diode bridge arm, which includes diodes D3 and D4, and two output capacitors C O3 and C O4 The third diode bridge arm, which includes diodes D5 and D6, and two output capacitors C O5 and C O6 Connected in parallel. A total of six output capacitors C O1 、C O2 、C O3 、C O4 、C O5 and C O6 connected in series to provide an output voltage V O Preload R.

[0199] The midpoint of the first diode bridge arm, comprising diodes D1 and D2, is connected to one end of the secondary winding of the first transformer TR1. The midpoint of the second diode bridge arm, comprising diodes D3 and D4, is connected to one end of the secondary winding of the second transformer TR2. The midpoint of the third diode bridge arm, comprising diodes D5 and D6, is connected to one end of the secondary winding of the third transformer TR3. The other end of the secondary winding of the first transformer TR1 is connected to the output capacitor C. O1 and C O2 The other end of the secondary winding of the second transformer TR2 is connected to the output capacitor C O3 and C O4 The other end of the secondary winding of the third transformer TR3 is connected to the output capacitor C O5 and C O6 midpoint.

[0200] Variable switching frequency control can be used to adjust the output voltage and output power of a three-phase resonant converter having a three-layer stacked half-bridge rectifier in an embodiment of the present disclosure. Figure 13B Shows the Figure 13A The switching control signals GS1 to GS6 of the converter, the primary resonant current i r1 to i r3 , secondary current i s1 to i s3 , output capacitor voltage V CO1 To V CO6 And the output voltage V O Timing sequence when variable frequency control is performed. The secondary current i of the transformer s1 to i s3 It is a sine wave and is in resonance with the primary current i r1 to i r3 In phase. Figure 13B As shown, the six output capacitor voltages V CO1 To V CO6 It is in a self-balancing state. The output voltage is six times the voltage of any output capacitor.

[0201] Figure 13C FIG. 1 shows an n-layer stacked half-bridge rectifier for an n-phase resonant converter according to an embodiment of the present disclosure. Figure 13C In this scheme, n half-bridge legs are stacked together to form the rectifier stage of an n-phase resonant converter. The output voltage is 2n times the voltage of any output capacitor.

[0202] Figure 13C The n independent transformers shown can be integrated into a number of transformers less than n. For example, Figure 13D An n-layer stacked half-bridge rectifier for an n-phase resonant converter with an integrated transformer in one embodiment of the present disclosure is shown. Figure 13DIn the embodiment of the present invention, the n-layer stacked half-bridge rectifier adopts only one integrated transformer, wherein the integrated transformer has a total of n windings on the primary side and a total of n windings on the secondary side.

[0203] Figure 13E An n-layer stacked active half-bridge rectifier for an n-phase resonant converter in one embodiment of the present disclosure is shown, which is used to achieve synchronous rectification and bidirectional operation. Figure 13E In this topology, active switches replace all diodes in an n-layer stacked half-bridge rectifier to achieve synchronous rectification. The resonant converter provides bidirectional power flow. Phase-shift modulation, which is common in stacked half-bridge resonant converters, can also be applied to this topology.

[0204] Stacked full-bridge rectifier

[0205] Figure 14A A three-layer stacked full-bridge rectifier for a three-phase resonant converter in one embodiment of the present disclosure is shown. Figure 14A The resonant rectifier in the secondary side uses three stacked full-bridge legs (including diodes D1 to D 12 The first full-bridge arm including diodes D1 to D4 and the first output capacitor C O1 The second full bridge arm including diodes D5 to D8 and the second output capacitor C O2 Connected in parallel. Contains diodes D9 to D 12 The third full-bridge arm and the third output capacitor C O3 Connect in parallel. Output capacitor C O1 、C O2 and C O3 connected in series to provide an output voltage V O Preload R.

[0206] One end of the secondary winding of the first transformer TR1 is connected to the midpoint between diodes D1 and D3, while the other end of the secondary winding of the first transformer TR1 is connected to the midpoint between diodes D2 and D4. One end of the secondary winding of the second transformer TR2 is connected to the midpoint between diodes D5 and D7, while the other end of the secondary winding of the second transformer TR2 is connected to the midpoint between diodes D6 and D8. One end of the secondary winding of the third transformer TR3 is connected to the midpoint between diodes D9 and D10. 11 The other end of the secondary winding of the third transformer TR3 is connected to the diode D 10 and D 12 The variable switching frequency control can be used to adjust the output voltage and output power of the stacked half-bridge resonant converter having the three-layer stacked full-bridge rectifier. No blocking capacitor is required in this rectifier.

[0207] Figure 14BFIG. 1 shows an n-layer stacked full-bridge rectifier for an n-phase resonant converter according to an embodiment of the present disclosure. Figure 14B In this example, n full-bridge arms are stacked together to form the rectifier stage of an n-layer stacked half-bridge resonant converter. The output voltage is n times the voltage of any output capacitor.

[0208] n independent transformers can be integrated into a number of transformers less than n. For example, Figure 14C FIG. 1 shows an n-layer stacked full-bridge rectifier for an n-phase resonant converter with an integrated transformer in an embodiment of the present disclosure. Figure 14C As shown, the n-layer stacked full-bridge rectifier uses only one integrated transformer, wherein the integrated transformer has a total of n windings on the primary side and a total of n windings on the secondary side.

[0209] Figure 14D An n-layer stacked active full-bridge rectifier for an n-phase resonant converter in one embodiment of the present disclosure is shown, which is used to achieve synchronous rectification and bidirectional operation. Figure 14D In this topology, 4n active switches replace all diodes in an n-layer stacked full-bridge rectifier to achieve synchronous rectification. The resonant converter provides bidirectional power flow. Phase-shift modulation, similar to that used in stacked half-bridge resonant converters, can also be applied to this topology.

[0210] Stacked series half-bridge rectifier

[0211] Figure 15A A three-layer stacked series half-bridge rectifier used in a three-phase resonant converter in an embodiment of the present disclosure is shown. Figure 15A The resonant rectifier in the circuit uses three stacked half-bridge arms (including diodes D1 to D 12 The first half-bridge leg comprising diodes D1 to D4 and two output capacitors C O1 and C O2 The second series half-bridge leg consisting of diodes D5 to D8 and two output capacitors C O3 and C O4 Connected in parallel. Contains diodes D9 to D 12 The third half-bridge arm is connected in series with two output capacitors C O5 and C O6 Connected in parallel. A total of six output capacitors C O1 、C O2 、C O3 、C O4 、C O5 and C O6 connected in series to provide an output voltage V O Preload R.

[0212] One end of the secondary winding of the first transformer TR1 is connected to the midpoint between diodes D1 and D3, while the other end of the secondary winding of the first transformer TR1 is connected to the midpoint between diodes D3 and D4. One end of the secondary winding of the second transformer TR2 is connected to the midpoint between diodes D5 and D6, while the other end of the secondary winding of the second transformer TR2 is connected to the midpoint between diodes D7 and D8. One end of the secondary winding of the third transformer TR3 is connected to the midpoint between diodes D9 and D10. 10 The other end of the secondary winding of the third transformer TR3 is connected to the diode D 11 and D 12 The midpoint between.

[0213] Variable switching frequency control can be used to adjust the output voltage and output power of the stacked half-bridge resonant converter with three stacked series half-bridge rectifiers in one embodiment of the present disclosure. Figures 15A-15D In the figure, a blocking capacitor C is set s1 to C s3 To establish the DC bias voltage required for the normal operation of the rectifier. The six output capacitor voltages V CO1 To V CO6 In a self-balancing state.

[0214] Figure 15B FIG1 shows an n-layer stacked series half-bridge rectifier for an n-phase resonant converter in one embodiment of the present disclosure. Figure 15B In this example, n series-connected half-bridge legs are stacked together to form the rectifier stage of an n-layer stacked half-bridge resonant converter. The output voltage is n times the voltage of any output capacitor.

[0215] n independent transformers can be integrated into a number of transformers less than n. Figure 15C An n-layer stacked series half-bridge rectifier applied to an n-phase resonant converter with an integrated transformer in an embodiment of the present disclosure is shown.

[0216] like Figure 15C As shown, the n-layer stacked series half-bridge rectifier uses only one integrated transformer, wherein the integrated transformer has a total of n windings on the primary side and a total of n windings on the secondary side.

[0217] Figure 15D An n-layer stacked series half-bridge rectifier used in an n-phase resonant converter in an embodiment of the present disclosure is shown, which is used to achieve synchronous rectification and bidirectional operation. Figure 15D In this scheme, all diodes in an n-layer stacked series half-bridge rectifier are replaced by a total of 4n active switches to achieve synchronous rectification. The resonant converter provides bidirectional power flow.

[0218] Summary of stacked resonant converters

[0219] In the foregoing, various resonant converters and rectifiers based on stacked half-bridge legs, stacked full-bridge legs, and stacked series half-bridge legs have been described. Figure 16 The general stacked resonant converter of one embodiment of the present disclosure is shown. A total of n independent transformers are provided, with a total of n primary windings and n secondary windings. On the primary side, four different topologies can be used as the inverter stage. The first topology is an n-layer stacked half-bridge structure with transformers connected in star. The second topology is an n-layer stacked half-bridge structure, which is Figure 7A The third topology is the n-layer stacked series half-bridge structure, which is Figure 9A The fourth topology is the n-layer stacked full-bridge structure, which is Figure 11C The primary side topology in .

[0220] On the secondary side, five different topologies can be used as rectifiers. The first topology is an n-layer stacked half-bridge structure with a star-connected transformer, which is Figure 12C The rectifier topology in the rectifier, when using this topology, needs to set a blocking capacitor on the secondary side to ensure the normal operation of the rectifier. The second topology is an n-layer stacked half-bridge structure, which is Figure 13C The third topology is the n-layer stacked full-bridge structure, which is Figure 14B The fourth topology is the n-layer stacked series half-bridge structure, which is Figure 15B The rectifier topology in [1] requires a blocking capacitor on the secondary side to ensure proper operation of the rectifier. The fifth topology is a traditional n-phase diode bridge structure, which can be a half-wave or full-wave structure.

[0221] N independent phase transformers are used to provide the required turns ratio and electrical isolation. These n transformers can be further integrated into fewer than n transformers. Diodes in the rectifier stage can be replaced by active switches to achieve synchronous rectification and bidirectional operation. Variable switching frequency control, PWM duty cycle modulation, and phase-shift modulation can be used to regulate the system's output voltage and output power.

[0222] Figure 17 A general stacked resonant converter according to an embodiment of the present disclosure is shown, which includes multiple circuits connected in parallel on both the primary and secondary sides. On the primary side, a total of m stacked structures are connected in parallel to the input voltage, where each stacked structure includes n layers of basic elements stacked together, which is the primary side architecture shown in Figure 16. Therefore, there are a total of m*n basic elements on the primary side, connected in a specific series and parallel manner. The converter is provided with a total of m*n independent transformers TR (1,1) to TR (n,m), which includes a total of m*n primary windings and m*n secondary windings. If the stacked basic elements are half-bridge legs of a transformer with a star connection, one end of each primary winding is connected to the same point to form a star connection, and the other end of each primary winding is coupled to the midpoint of the corresponding half-bridge leg through the corresponding resonant cavity. In addition, all m*n primary windings are directly coupled to the basic element through the resonant cavity.

[0223] On the secondary side, a total of p stacked structures are connected in parallel, with each stack comprising q stacked layers of basic elements, similar to the rectifier stage in Figure 16. For proper rectification, the product of p and q (i.e., p*q) equals the product of m and n (i.e., m*n). Similarly, if the stacked basic elements are half-bridge legs of a star-connected transformer, one end of each secondary winding is connected to the same point to form a star connection, while the other end of each secondary winding is coupled to the midpoint of the corresponding half-bridge leg via a blocking capacitor. Furthermore, all m*n secondary windings are directly coupled to the basic elements via blocking capacitors. Variable switching frequency control, PWM duty cycle modulation, and phase-shift modulation can all be used to regulate the system's output voltage and power. To simplify the system, the m*n transformers can be integrated into a smaller number of transformers. The diodes in the rectifier stage can be replaced by active switches to achieve synchronous rectification and bidirectional operation.

[0224] To facilitate description and definition of the technical content of this disclosure, terms such as "substantially," "approximately," "slightly," and "relatively" are used to indicate an inherent degree of uncertainty, which may arise from quantitative comparisons, numerical values, sensing, and other factors. These terms generally mean that the deviation from a given value or range is within 10%, 5%, 1%, or 0.5%, and that such deviation does not affect the basic function of the corresponding technical feature. Unless otherwise specified, the numerical parameters stated in this disclosure are values that can be regarded as specific values or values within a range of error.

[0225] It should be noted that the above examples are merely illustrative of the present disclosure and are not limited to the aforementioned examples. The scope of the present disclosure is determined by the appended claims. Furthermore, the present disclosure may be modified in various ways by those skilled in the art, without departing from the scope of the claims.

Claims

1. A DC-DC converter comprising: A primary side comprising at least two half-bridge inverter units stacked in series, wherein each half-bridge inverter unit comprises two active switches connected in series and two input capacitors connected in series. The bridge arms containing the two active switches are connected in parallel with the bridge arms containing the two input capacitors to form a first loop. Each half-bridge inverter unit is sequentially connected from a point between the two active switches to a resonant cavity circuit, a primary-side winding wound on a transformer core, and a point between the two input capacitors. The first end of each half-bridge inverter unit is connected to the bridge arm in the first loop, and the first end of any half-bridge inverter unit is directly connected to the second end of the corresponding stacked half-bridge inverter unit. A primary-side voltage is applied or generated between the first and second ends of the at least two half-bridge inverter units that are not connected to another half-bridge inverter unit. The at least two half-bridge inverter units may share the transformer core. a secondary side comprising at least two sets of rectifier circuit elements, wherein the rectifier circuit elements are coupled to a secondary winding wound on the transformer core, the secondary winding sharing the transformer core with a corresponding primary winding, the rectifier circuit elements being configured to rectify an induced current generated on the secondary side due to current flowing through the corresponding primary winding, thereby generating or applying a secondary voltage to the secondary side; and a control circuit configured to actuate the active switch in the DC-DC converter to change the pulse frequency, pulse width or phase shift angle of the voltage or current on the inverter unit or the rectifier circuit element; in, The control circuit is configured to execute a first control mode and / or a second control mode. In the first control mode, for any of the half-bridge inverter units, the control circuit determines whether a difference between an average value of the voltages on the two input capacitors of the half-bridge inverter unit and a reference voltage is greater than a threshold voltage. If the determination result is yes, the control circuit balances the capacitor voltages by controlling the duty cycles of the two active switches. In the second control mode, the control circuit determines whether the difference between the measured average voltage on the two input capacitors of each half-bridge inverter unit and the reference voltage is greater than the threshold voltage. If the determination result is yes, the control circuit determines the largest difference among the half-bridge inverter units and adjusts the phase shift angle in each phase bridge arm by controlling the active switch according to the largest difference to balance the capacitor voltages.

2. The DC-DC converter of claim 1 , wherein each of the rectifier circuit elements comprises a half-bridge rectifier unit, the half-bridge rectifier unit comprising two diodes connected in series in a bridge arm and having the same conduction direction, wherein one of the diodes is located between a connection point connected to the corresponding secondary-side winding and a first common point of the half-bridge rectifier unit, and the other diode is located between the connection point and a second common point of the half-bridge rectifier unit, a capacitor bridge arm is connected in parallel between the first common point and the second common point, and the secondary-side voltage is generated between the two common ends of the parallel-connected bridge arms.

3. The DC-DC converter of claim 1 , wherein each of the rectifier circuit elements comprises an active half-bridge rectifier unit, the active half-bridge rectifier unit comprising two active switches connected in series in the same bridge arm, the active switches being controlled by the control circuit, one of the active switches being located between a connection point connected to the corresponding secondary-side winding and a first common point of all the active half-bridge rectifier units, and the other of the active switches being located between the connection point and a second common point of all the active half-bridge rectifier units, a capacitor bridge arm being connected in parallel between the first common point and the second common point, and the secondary-side voltage being generated or generated between the two common ends of the parallel-connected bridge arms.

4. The DC-DC converter of claim 1 , wherein each of the rectifier circuit elements comprises a full-bridge rectifier unit, the full-bridge rectifier unit comprising two diode arms connected in parallel, each diode arm comprising two diodes connected in series and having the same conduction direction, each of the full-bridge rectifier units being sequentially connected from a point between the two diodes in one of the diode arms to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two diodes in another of the diode arms, the two common points of the diode arms being connected in parallel to the two ends of a parallel capacitor arm, and the secondary-side voltage being generated between the two common ends of the parallel-connected arms.

5. The DC-DC converter of claim 1 , wherein each of the rectifier circuit elements comprises a full-bridge rectifier unit, the full-bridge rectifier unit comprising two switching arms connected in parallel, each of the switching arms comprising two active switches connected in series and controlled by the control circuit, each of the full-bridge rectifier units being sequentially connected from a point between the two active switches of one of the switching arms to a first end of the corresponding secondary-side winding, a second end of the corresponding secondary-side winding, and a point between the two active switches of another of the switching arms, two common points of the switching arms being connected in parallel to two ends of a capacitor arm, and the secondary-side voltage being generated or applied between the two common ends of the parallel-connected arms.

6. The DC-DC converter of claim 1 , wherein the rectifier circuit elements form a plurality of half-bridge rectifier units stacked in series, each half-bridge rectifier unit comprising two diodes connected in series and having the same conduction direction and two output capacitors connected in series, the bridge arms containing the two diodes being connected in parallel to the bridge arms containing the two output capacitors to jointly form a second loop, and each half-bridge rectifier unit is sequentially connected from a point between the two diodes to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two output capacitors, wherein the first end of any half-bridge rectifier unit is connected to the bridge arm in the second loop, and the first end of any half-bridge rectifier unit is directly connected to the second end of the stacked corresponding half-bridge rectifier unit, and the secondary-side voltage is generated between the first end and the second end of the half-bridge rectifier unit that is not connected to another half-bridge rectifier unit in the plurality of half-bridge rectifier units.

7. The DC-DC converter of claim 1 , wherein the rectifying circuit elements form a plurality of half-bridge rectifier units stacked in series, each half-bridge rectifier unit comprising two active switches connected in series and controlled by the control circuit, and two output capacitors connected in series. In any half-bridge rectifier unit, the bridge arms containing the two active switches are connected in parallel to the bridge arms containing the two output capacitors to jointly form a second loop. Each half-bridge rectifier unit is sequentially connected from a point between the two active switches to the first end of the corresponding secondary winding, the second end of the corresponding secondary winding, and a point between the two output capacitors. The first end of any half-bridge rectifier unit is connected to the bridge arm in the second loop, and the first end of any half-bridge rectifier unit is directly connected to the second end of the corresponding stacked half-bridge rectifier unit. The secondary-side voltage is generated between the first and second ends of the half-bridge rectifier units not connected to another half-bridge rectifier unit in the plurality of half-bridge rectifier units.

8. The DC-DC converter of claim 1 , wherein the rectifier circuit elements form a plurality of full-bridge rectifier units stacked in series, each of the full-bridge rectifier units comprising two diode arms connected in parallel and a capacitor arm, the diode arms comprising two diodes connected in series and having the same conduction direction, wherein in any of the full-bridge rectifier units, the full-bridge rectifier unit is sequentially connected from a point between the two diodes in one of the diode arms to a first end of the corresponding secondary-side winding, a second end of the corresponding secondary-side winding, and a point between the two diodes in another of the diode arms, wherein a first common point of the arms connected in parallel in any of the full-bridge rectifier units is directly connected to a second common point of the arms connected in parallel in the stacked corresponding full-bridge rectifier unit, and the secondary-side voltage is generated or applied between the first common point and the second common point of the plurality of full-bridge rectifier units not connected to another of the full-bridge rectifier units.

9. The DC-DC converter of claim 1 , wherein the rectifier circuit elements form a plurality of full-bridge rectifier units stacked in series, each of the full-bridge rectifier units comprising two switching arms connected in parallel and a capacitor arm, the switching arms comprising two active switches connected in series and controlled by the control circuit, wherein in any of the full-bridge rectifier units, the full-bridge rectifier unit is sequentially connected from a point between the two active switches of one of the switching arms to a first end of the corresponding secondary-side winding, a second end of the corresponding secondary-side winding, and a point between the two active switches of another of the switching arms, wherein a first common point of the parallel-connected arms of any of the full-bridge rectifier units is directly connected to a second common point of the parallel-connected arms of the corresponding stacked full-bridge rectifier unit, and the secondary-side voltage is generated or applied between the first common point and the second common point of the plurality of full-bridge rectifier units not connected to another full-bridge rectifier unit.

10. The DC-DC converter of claim 1 , wherein the rectifier circuit elements form a plurality of series-connected half-bridge rectifier units stacked in series, each of the series-connected half-bridge rectifier units comprising a first output capacitor, a second output capacitor, and a first diode bridge arm and a second diode bridge arm connected in series, the first diode bridge arm comprising two diodes connected in series and having the same conduction direction, the first diode bridge arm being connected in parallel to the first output capacitor to form a second loop, the second diode bridge arm comprising two diodes connected in series and having the same conduction direction, the second diode bridge arm being connected in parallel to the second output capacitor. A capacitor is used to form a third loop. In any of the series half-bridge rectifier units, the series half-bridge rectifier unit is connected to the first end of the corresponding secondary-side winding via a blocking capacitor from a point between the two diodes of the first diode bridge arm, and is connected to a point between the two diodes of the second diode bridge arm via the second end of the corresponding secondary-side winding, wherein the first common point of the second or third loop is directly connected to the second common point of the stacked third or second loop, and the secondary-side voltage is generated between the first common point and the second common point of all the second and third loops that are not connected to another loop.

11. The DC-DC converter of claim 1 , wherein the rectifier circuit elements form a plurality of series-connected half-bridge rectifier units stacked in series, each of the series-connected half-bridge rectifier units comprising a first output capacitor, a second output capacitor, and a first switching arm and a second switching arm connected in series, the first switching arm comprising two active switches connected in series and controlled by the control circuit, the first switching arm being connected in parallel to the first output capacitor to form a second loop, the second switching arm comprising two active switches connected in series and controlled by the control circuit, the second switching arm being connected in parallel to the second output capacitor to form a second loop. A third loop is formed. In any of the series half-bridge rectifier units, the series half-bridge rectifier unit is connected to the first end of the corresponding secondary-side winding via a blocking capacitor from a point between the two active switches of the first switching bridge arm, and is connected to a point between the two active switches of the second switching bridge arm via the second end of the corresponding secondary-side winding, wherein the first common point of the second or third loop is directly connected to the second common point of the stacked third or second loop, and the secondary-side voltage is generated or applied between the first common point and the second common point of all the second and third loops that are not connected to another loop.

12. A DC-DC converter comprising: A primary side comprising at least two half-bridge inverter units stacked in series, wherein each half-bridge inverter unit comprises two active switches connected in series and an input capacitor, the bridge arms containing the two active switches being connected in parallel with the bridge arm containing the input capacitor to jointly form a first loop, and each half-bridge inverter unit being sequentially connected, from a point between the two active switches, to a resonant cavity circuit, a first end of a primary-side winding wound on a transformer core, a second end of the primary-side winding, and a common star connection point of the at least two half-bridge inverter units. The first end of any half-bridge inverter unit is connected to the bridge arm in the first loop, and the first end of any half-bridge inverter unit is directly connected to the second end of the corresponding stacked half-bridge inverter unit. A primary-side voltage is applied or generated between the first and second ends of the at least two half-bridge inverter units that are not connected to another half-bridge inverter unit, and the at least two half-bridge inverter units may share the transformer core; a secondary side comprising at least two sets of rectifier circuit elements, wherein the rectifier circuit elements are coupled to a secondary winding wound on the transformer core, the secondary winding sharing the transformer core with a corresponding primary winding, the rectifier circuit elements being configured to rectify an induced current generated on the secondary side due to current flowing through the corresponding primary winding, thereby generating or applying a secondary voltage to the secondary side; and a control circuit configured to actuate the active switch in the DC-DC converter to change the pulse frequency, pulse width or phase shift angle of the voltage or current on the inverter unit or the rectifier circuit element; in, The control circuit is configured to execute a first control mode and / or a second control mode. In the first control mode, for any of the half-bridge inverter units, the control circuit determines whether the difference between the measured voltage on the input capacitor of the half-bridge inverter unit and a reference voltage is greater than a threshold voltage. If the determination result is yes, the control circuit balances the capacitor voltage by controlling the duty cycle of the two active switches. In the second control mode, the control circuit determines whether the difference between any measured average voltage on the input capacitor of each half-bridge inverter unit and the reference voltage is greater than the threshold voltage. If the determination result is yes, the control circuit determines the largest difference among the half-bridge inverter units and adjusts the phase shift angle in each phase bridge arm by controlling the active switch according to the largest difference to balance the capacitor voltage.

13. The DC-DC converter of claim 12 , wherein the rectifying circuit elements form a plurality of half-bridge rectifier units stacked in series, each half-bridge rectifier unit comprising two diodes connected in series and having the same conduction direction and an output capacitor, the bridge arms containing the two diodes being connected in parallel with the bridge arm containing the output capacitor to jointly form a second loop, each half-bridge rectifier unit being connected to the first end of the corresponding secondary-side winding via a blocking capacitor from a point between the two diodes, and being connected to a common star connection point of the plurality of half-bridge rectifier units via the second end of the corresponding secondary-side winding, wherein the first end of any half-bridge rectifier unit is connected to the bridge arm in the second loop, and the first end of any half-bridge rectifier unit is directly connected to the second end of the stacked corresponding half-bridge rectifier unit, and the secondary-side voltage is generated between the first end and the second end of the half-bridge rectifier unit not connected to another half-bridge rectifier unit in the plurality of half-bridge rectifier units.

14. The DC-DC converter of claim 12 , wherein the rectifying circuit elements form a plurality of half-bridge rectifier units stacked in series, each half-bridge rectifier unit comprising two active switches connected in series and controlled by the control circuit, and an output capacitor. The bridge arms of the two active switches are connected in parallel with the bridge arm of the output capacitor to form a second loop. Each half-bridge rectifier unit is connected to the first end of the corresponding secondary winding via a blocking capacitor at a point between the two active switches, and is connected to a common star point of the plurality of half-bridge rectifier units via the second end of the corresponding secondary winding. The first end of any half-bridge rectifier unit is connected to the bridge arm in the second loop, and the first end of any half-bridge rectifier unit is directly connected to the second end of the corresponding stacked half-bridge rectifier unit. The secondary-side voltage is generated between the first and second ends of the half-bridge rectifier units that are not connected to another half-bridge rectifier unit in the plurality of half-bridge rectifier units.

15. A DC-DC converter comprising: A primary side includes at least two stacked series half-bridge inverter units, wherein each of the series half-bridge inverter units includes a first half-bridge arm and a second half-bridge arm connected in series, the first half-bridge arm includes a first input capacitor and two first active switches connected in series, and a first switch arm where the two first active switches are located is connected in parallel with the arm where the first input capacitor is located to form a first loop, the second half-bridge arm includes a second input capacitor and two second active switches connected in series, and a second switch arm where the two second active switches are located is connected in parallel with the arm where the second input capacitor is located to form a loop, each of the series half-bridge inverter units includes a first half-bridge arm and a second half-bridge arm, wherein the first half-bridge arm includes a first input capacitor and two second active switches connected in series, and the second switch arm where the two second active switches are located is connected in parallel with the arm where the second input capacitor is located to form a loop, The units are sequentially connected from a point between the two first active switches to a resonant cavity circuit, a primary-side winding wound on a transformer core, and a point between the two second active switches, wherein the first end of any of the series half-bridge inverter units is connected to the bridge arm in the first loop, and the first end of any of the series half-bridge inverter units is directly connected to the second end of the stacked corresponding series half-bridge inverter unit, and a primary-side voltage is applied or generated between the first end and the second end of the at least two series half-bridge inverter units that are not connected to another series half-bridge inverter unit, wherein the at least two series half-bridge inverter units may share the transformer core; a secondary side comprising at least two sets of rectifier circuit elements, wherein each set of rectifier circuit elements is coupled to a secondary winding wound on the transformer core, the secondary winding and a corresponding primary winding sharing the transformer core, the rectifier circuit elements being configured to rectify an induced current generated on the secondary side due to current flowing through the corresponding primary winding, thereby generating or applying a secondary voltage to the secondary side; and a control circuit configured to actuate the active switch in the DC-DC converter to change the pulse frequency, pulse width or phase shift angle of the voltage or current on the inverter unit or the rectifier circuit element; in, The control circuit is configured to execute a first control mode and / or a second control mode. In the first control mode, for each of the series half-bridge inverter units, the control circuit determines whether a voltage difference between the sensed first and second input capacitors is greater than a threshold voltage, and adjusts the phase shift angle by controlling the four active switches in the series half-bridge inverter unit if the determination result is yes. In the second control mode, for each of the series half-bridge inverter units, the control circuit determines whether the difference between an average voltage sensed across the first and second input capacitors and a reference voltage is greater than the threshold voltage, and generates an additional duty cycle by controlling the four active switches in the series half-bridge inverter unit if the determination result is yes.

16. The DC-DC converter of claim 15 , wherein each of the rectifier circuit elements is a half-bridge rectifier unit, the half-bridge rectifier unit comprising two diodes connected in series in a bridge arm and having the same conduction direction, wherein one of the diodes is located between a connection point connected to the corresponding secondary-side winding and a first common point of the half-bridge rectifier unit, and the other diode is located between the connection point and a second common point of the half-bridge rectifier unit, a parallel capacitor bridge arm is connected in parallel between the first common point and the second common point, and the secondary-side voltage is generated between the two common ends of the parallel bridge arms.

17. The DC-DC converter of claim 15 , wherein each of the rectifier circuit elements is an active half-bridge rectifier unit, the active half-bridge rectifier unit comprising two active switches connected in series in the same bridge arm, the active switches being controlled by the control circuit, one of the active switches being located between a connection point connected to the corresponding secondary-side winding and a first common point of the active half-bridge rectifier unit, and the other active switch being located between the connection point and a second common point of the active half-bridge rectifier unit, a capacitor bridge arm being connected in parallel between the first common point and the second common point, and the secondary-side voltage being generated or generated between the two common ends of the parallel-connected bridge arms.

18. The DC-DC converter of claim 15 , wherein each of the rectifier circuit elements is a full-bridge rectifier unit, the full-bridge rectifier unit comprising two diode arms connected in parallel, each diode arm comprising two diodes connected in series and having the same conduction direction, each of the full-bridge rectifier units being connected in sequence from a point between the two diodes in one of the diode arms to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two diodes in another of the diode arms, the two common points of the diode arms being connected in parallel to the two ends of a parallel capacitor arm, and the secondary-side voltage being generated between the two common ends of the parallel-connected arms.

19. The DC-DC converter of claim 15 , wherein each of the rectifier circuit elements is a full-bridge rectifier unit, the full-bridge rectifier unit comprising two switching arms connected in parallel, each of the switching arms comprising two active switches connected in series and controlled by the control circuit, each of the full-bridge rectifier units being connected in sequence from a point between the two active switches of one of the switching arms to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two active switches of another of the switching arms, the two common points of the switching arms being connected in parallel to the two ends of a capacitor arm, and the secondary-side voltage being generated or applied between the two common ends of the parallel-connected arms.

20. A DC-DC converter as claimed in claim 15, wherein the rectifier circuit elements form a plurality of half-bridge rectifier units stacked in series, each of the half-bridge rectifier units including two diodes connected in series and having the same conduction direction and two output capacitors connected in series, the bridge arms where the two diodes are located are connected in parallel to the bridge arms where the two output capacitors are located to jointly form a second loop, each of the half-bridge rectifier units is connected in sequence from a point between the two diodes to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two output capacitors, wherein the first end of any half-bridge rectifier unit is connected to the bridge arm in the second loop, and the first end of any half-bridge rectifier unit is directly connected to the second end of the stacked corresponding half-bridge rectifier unit, and the secondary-side voltage is generated between the first end and the second end of the half-bridge rectifier unit that is not connected to another half-bridge rectifier unit in the plurality of half-bridge rectifier units.

21. The DC-DC converter of claim 15 , wherein the rectifying circuit elements form a plurality of half-bridge rectifier units stacked in series, each of the half-bridge rectifier units comprising two active switches connected in series and controlled by the control circuit, and two output capacitors connected in series. In any of the half-bridge rectifier units, the bridge arms containing the two active switches are connected in parallel to the bridge arms containing the two output capacitors to jointly form a second loop. Each of the half-bridge rectifier units is sequentially connected from a point between the two active switches to the first end of the corresponding secondary winding, the second end of the corresponding secondary winding, and a point between the two output capacitors. The first end of any half-bridge rectifier unit is connected to the bridge arm in the second loop, and the first end of any half-bridge rectifier unit is directly connected to the second end of the stacked corresponding half-bridge rectifier unit. The secondary-side voltage is generated between the first and second ends of the half-bridge rectifier units that are not connected to another half-bridge rectifier unit.

22. A DC-DC converter as described in claim 15, wherein the rectifier circuit elements form a plurality of full-bridge rectifier units stacked in series, each of the full-bridge rectifier units including two diode bridge arms and a capacitor bridge arm connected in parallel to each other, the diode bridge arm including two diodes connected in series and having the same conduction direction, in any of the full-bridge rectifier units, the full-bridge rectifier unit is connected in sequence from a point between the two diodes in one of the diode bridge arms to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two diodes in another of the diode bridge arms, wherein a first common point of the bridge arms connected in parallel in any of the full-bridge rectifier units is directly connected to a second common point of the bridge arms connected in parallel in the stacked corresponding full-bridge rectifier unit, and the secondary-side voltage is generated or applied between the first common point and the second common point of the plurality of full-bridge rectifier units that are not connected to another full-bridge rectifier unit.

23. The DC-DC converter of claim 15 , wherein the rectifier circuit elements form a plurality of full-bridge rectifier units stacked in series, each of the full-bridge rectifier units comprising two switch arms connected in parallel and a capacitor arm, the switch arms comprising two active switches connected in series and controlled by the control circuit, wherein in any of the full-bridge rectifier units, the full-bridge rectifier unit is sequentially connected from a point between the two active switches of one of the switch arms to a first end of the corresponding secondary-side winding, a second end of the corresponding secondary-side winding, and a point between the two active switches of another of the switch arms, wherein a first common point of the parallel-connected arms of any of the full-bridge rectifier units is directly connected to a second common point of the parallel-connected arms of the corresponding stacked full-bridge rectifier unit, and the secondary-side voltage is generated or applied between the first common point and the second common point of the plurality of full-bridge rectifier units that are not connected to another of the full-bridge rectifier units.

24. The DC-DC converter of claim 15 , wherein the rectifier circuit elements form a plurality of series-connected half-bridge rectifier units stacked in series, each of the series-connected half-bridge rectifier units comprising a first output capacitor, a second output capacitor, and a first diode bridge arm and a second diode bridge arm connected in series, the first diode bridge arm comprising two diodes connected in series and having the same conduction direction, the first diode bridge arm being connected in parallel to the first output capacitor to form a second loop, the second diode bridge arm comprising two diodes connected in series and having the same conduction direction, the second diode bridge arm being connected in parallel to the second output capacitor to form a second loop. An output capacitor is provided to form a third loop. In any of the series half-bridge rectifier units, the series half-bridge rectifier unit is connected to the first end of the corresponding secondary-side winding via a blocking capacitor from a point between the two diodes of the first diode bridge arm, and is connected to a point between the two diodes of the second diode bridge arm via the second end of the corresponding secondary-side winding, wherein the first common point of the second or third loop is directly connected to the second common point of the stacked third or second loop, and the secondary-side voltage is generated between the first common point and the second common point of all the second and third loops that are not connected to another loop.

25. The DC-DC converter of claim 15 , wherein the rectifier circuit elements form a plurality of series-connected half-bridge rectifier units stacked in series, each of the series-connected half-bridge rectifier units comprising a first output capacitor, a second output capacitor, and a first switching bridge arm and a second switching bridge arm connected in series, the first switching bridge arm comprising two active switches connected in series and controlled by the control circuit, the first switching bridge arm being connected in parallel to the first output capacitor to form a second loop, the second switching bridge arm comprising two active switches connected in series and controlled by the control circuit, the second switching bridge arm being connected in parallel to the second output capacitor to form a second loop. A third loop is formed. In any of the series half-bridge rectifier units, the series half-bridge rectifier unit is connected to the first end of the corresponding secondary-side winding via a blocking capacitor from a point between the two active switches of the first switching bridge arm, and is connected to a point between the two active switches of the second switching bridge arm via the second end of the corresponding secondary-side winding, wherein the first common point of the second or third loop is directly connected to the second common point of the stacked third or second loop, and the secondary-side voltage is generated or applied between the first common point and the second common point of all the second and third loops that are not connected to another loop.

26. A DC-DC converter comprising: A primary side includes at least two full-bridge inverter units stacked in series, wherein each of the full-bridge inverter units includes a capacitor bridge arm and two half-bridge bridge arms connected in parallel to each other, and each of the half-bridge bridge arms includes two active switches connected in series. Each of the full-bridge inverter units is connected from a point between the two active switches of one of the half-bridge bridge arms to a point between the two active switches of the other half-bridge bridge arm via a resonant cavity circuit and a primary-side winding wound on a transformer core. A primary-side voltage is generated or applied to the series Between two ends of the at least two stacked full-bridge inverter units, wherein in any one of the full-bridge inverter units, a first end and a second end of the full-bridge inverter unit are respectively connected to the two ends of the bridge arm, the first end of any one of the full-bridge inverter units is directly connected to the second end of the corresponding stacked full-bridge inverter unit, and the primary-side voltage is applied or generated between the first end and the second end of the at least two full-bridge inverter units that are not connected to another full-bridge inverter unit, wherein the at least two full-bridge inverter units may share the transformer magnetic core; a secondary side comprising at least two sets of rectifier circuit elements, wherein each set of rectifier circuit elements is coupled to a secondary winding wound on the transformer core, the secondary winding and a corresponding primary winding sharing the transformer core, the rectifier circuit elements being configured to rectify an induced current generated on the secondary side due to current flowing through the corresponding primary winding, thereby generating or applying a secondary voltage to the secondary side; and a control circuit configured to actuate the active switch in the DC-DC converter to change the pulse frequency, pulse width or phase shift angle of the voltage or current on the inverter unit or the rectifier circuit element; in, The control circuit is configured to execute a first control mode and / or a second control mode. In the first control mode, for any of the full-bridge inverter units, the control circuit determines whether the difference between an average value of the voltage of the capacitor in the capacitor bridge arm of the full-bridge inverter unit measured and a reference voltage is greater than a threshold voltage. If the determination result is yes, the control circuit balances the capacitor voltage by controlling the duty cycle of the two active switches. In the second control mode, the control circuit determines whether the difference between any measured average voltage on the capacitor bridge arm of each full-bridge inverter unit and the reference voltage is greater than the threshold voltage. If the determination result is yes, the control circuit determines the largest difference among the full-bridge inverter units and adjusts the phase shift angle in each phase bridge arm by controlling the active switch based on the largest difference to balance the capacitor voltage.

27. The DC-DC converter of claim 26 , wherein each of the rectifier circuit elements is a half-bridge rectifier unit, the half-bridge rectifier unit comprising two diodes connected in series in a bridge arm and having the same conduction direction, wherein one of the diodes is located between a connection point connected to the corresponding secondary-side winding and a first common point of the half-bridge rectifier unit, and the other diode is located between the connection point and a second common point of the half-bridge rectifier unit, a capacitor bridge arm is connected in parallel between the first common point and the second common point, and the secondary-side voltage is generated between the two common ends of the bridge arms connected in parallel.

28. The DC-DC converter of claim 26 , wherein each of the rectifier circuit elements is an active half-bridge rectifier unit, the active half-bridge rectifier unit comprising two active switches connected in series in the same bridge arm, the active switches being controlled by the control circuit, one of the active switches being located between a connection point connected to the corresponding secondary-side winding and a first common point of the active half-bridge rectifier unit, and the other active switch being located between the connection point and a second common point of the active half-bridge rectifier unit, a capacitor bridge arm being connected in parallel between the first common point and the second common point, and the secondary-side voltage being generated or generated between the two common ends of the bridge arms connected in parallel.

29. The DC-DC converter of claim 26 , wherein each of the rectifier circuit elements is a full-bridge rectifier unit, the full-bridge rectifier unit comprising two diode arms connected in parallel, each of the diode arms comprising two diodes connected in series and having the same conduction direction, each of the full-bridge rectifier units being connected in sequence from a point between the two diodes in one of the diode arms to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two diodes in another of the diode arms, the two common points of all of the diode arms being connected in parallel to the two ends of a parallel capacitor arm, and the secondary-side voltage being generated between the two common ends of the arms connected in parallel.

30. The DC-DC converter of claim 26 , wherein each of the rectifier circuit elements is a full-bridge rectifier unit, the full-bridge rectifier unit comprising two switching bridge arms connected in parallel, each of the switching bridge arms comprising two active switches connected in series and controlled by the control circuit, each of the full-bridge rectifier units being connected in sequence from a point between the two active switches of one of the switching bridge arms to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two active switches of another of the switching bridge arms, the two common points of the switching bridge arms being connected in parallel to the two ends of a capacitor bridge arm, and the secondary-side voltage being generated or applied between the two common ends of the bridge arms connected in parallel.

31. A DC-DC converter as described in claim 26, wherein the rectifier circuit elements form a plurality of half-bridge rectifier units stacked in series, each of the half-bridge rectifier units including two diodes connected in series and having the same conduction direction and two output capacitors connected in series, the bridge arms where the two diodes are located are connected in parallel to the bridge arms where the two output capacitors are located to jointly form a second loop, each of the half-bridge rectifier units is connected in sequence from a point between the two diodes to the first end of the corresponding secondary side winding, the second end of the corresponding secondary side winding and a point between the two output capacitors, wherein the first end of any half-bridge rectifier unit is connected to the bridge arm in the second loop, and the first end of any half-bridge rectifier unit is directly connected to the second end of the stacked corresponding half-bridge rectifier unit, and the secondary side voltage is generated between the first end and the second end of the half-bridge rectifier unit that is not connected to another half-bridge rectifier unit in the plurality of half-bridge rectifier units.

32. The DC-DC converter of claim 26 , wherein the rectifying circuit elements form a plurality of half-bridge rectifier units stacked in series, each of the half-bridge rectifier units comprising two active switches connected in series and controlled by the control circuit, and two output capacitors connected in series. In any of the half-bridge rectifier units, the bridge arms containing the two active switches are connected in parallel to the bridge arms containing the two output capacitors to jointly form a second loop. Each of the half-bridge rectifier units is sequentially connected from a point between the two active switches to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two output capacitors. The first end of any half-bridge rectifier unit is connected to the bridge arm in the second loop, and the first end of any half-bridge rectifier unit is directly connected to the second end of the stacked corresponding half-bridge rectifier unit. The secondary-side voltage is generated between the first end and the second end of the half-bridge rectifier unit that is not connected to another half-bridge rectifier unit in the plurality of half-bridge rectifier units.

33. A DC-DC converter as described in claim 26, wherein the rectifier circuit elements form a plurality of full-bridge rectifier units stacked in series, each of the full-bridge rectifier units comprising two diode bridge arms and a capacitor bridge arm connected in parallel to each other, the diode bridge arm comprising two diodes connected in series and having the same conduction direction, in any of the full-bridge rectifier units, the full-bridge rectifier unit is connected in sequence from a point between the two diodes of one of the diode bridge arms to the first end of the corresponding secondary side winding, the second end of the corresponding secondary side winding, and a point between the two diodes of another diode bridge arm, wherein the first common point of the bridge arms connected in parallel to each other in any of the full-bridge rectifier units is directly connected to the second common point of the bridge arms connected in parallel to each other in the stacked corresponding full-bridge rectifier unit, and the secondary side voltage is generated or applied between the first common point and the second common point of the plurality of full-bridge rectifier units that are not connected to another full-bridge rectifier unit.

34. A DC-DC converter as described in claim 26, wherein the rectifier circuit elements form a plurality of full-bridge rectifier units stacked in series, each of the full-bridge rectifier units including two switch bridge arms connected in parallel to each other and a capacitor bridge arm, the switch bridge arm including two active switches connected in series and controlled by the control circuit, in any of the full-bridge rectifier units, the full-bridge rectifier unit is sequentially connected from a point between the two active switches of one of the switch bridge arms to the first end of the corresponding secondary-side winding, the second end of the corresponding secondary-side winding, and a point between the two active switches of another of the switch bridge arms, wherein a first common point of the bridge arms connected in parallel to each other in any of the full-bridge rectifier units is directly connected to a second common point of the bridge arms connected in parallel to each other in the stacked corresponding full-bridge rectifier unit, and the secondary-side voltage is generated or applied between the first common point and the second common point of the plurality of full-bridge rectifier units that are not connected to another full-bridge rectifier unit.

35. The DC-DC converter of claim 26, wherein the rectifier circuit elements form a plurality of series-connected half-bridge rectifier units stacked in series, each of the series-connected half-bridge rectifier units comprising a first output capacitor, a second output capacitor, and a first diode bridge arm and a second diode bridge arm connected in series, the first diode bridge arm comprising two diodes connected in series and having the same conduction direction, the first diode bridge arm being connected in parallel to the first output capacitor to form a second loop, the second diode bridge arm comprising two diodes connected in series and having the same conduction direction, the second diode bridge arm being connected in parallel to the second output capacitor to form a second loop. An output capacitor is provided to form a third loop. In any of the series half-bridge rectifier units, the series half-bridge rectifier unit is connected to the first end of the corresponding secondary-side winding via a blocking capacitor from a point between the two diodes of the first diode bridge arm, and is connected to a point between the two diodes of the second diode bridge arm via the second end of the corresponding secondary-side winding, wherein the first common point of the second or third loop is directly connected to the second common point of the stacked third or second loop, and the secondary-side voltage is generated between the first common point and the second common point of all the second and third loops that are not connected to another loop.

36. The DC-DC converter of claim 26, wherein the rectifier circuit elements form a plurality of series-connected half-bridge rectifier units stacked in series, each of the series-connected half-bridge rectifier units comprising a first output capacitor, a second output capacitor, and a first switching bridge arm and a second switching bridge arm connected in series, the first switching bridge arm comprising two active switches connected in series and controlled by the control circuit, the first switching bridge arm being connected in parallel to the first output capacitor to form a second loop, the second switching bridge arm comprising two active switches connected in series and controlled by the control circuit, the second switching bridge arm being connected in parallel to the second output capacitor to form a second loop. A third loop is formed. In any of the series half-bridge rectifier units, the series half-bridge rectifier unit is connected to the first end of the corresponding secondary-side winding via a blocking capacitor from a point between the two active switches of the first switching bridge arm, and is connected to a point between the two active switches of the second switching bridge arm via the second end of the corresponding secondary-side winding, wherein the first common point of the second or third loop is directly connected to the second common point of the stacked third or second loop, and the secondary-side voltage is generated or applied between the first common point and the second common point of all the second and third loops that are not connected to another loop.

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