Multi-phase resonant power converter

Abstract

The present disclosure relates to a multi-phase resonant power converter comprising: a power stage at a primary side of the multi-phase resonant power converter, the power stage comprising bridge converter legs, each of the plurality of bridge converter legs configured to receive an AC input voltage and implement an individual phase of the power converter; a transformer device having a primary side winding for each bridge converter leg and a secondary side winding for each primary side winding; a power supply circuit electrically connected to a secondary side winding at a secondary side of the multi-phase resonant power converter; a secondary side controller configured to operate the bridge converter legs at a switching frequency; and a separate resonant tank electrically connected to a midpoint of each bridge converter leg. Each resonant tank includes a resonant capacitor in series with a primary side winding for a bridge converter leg. The resonant frequency of each resonant tank is tuned to be within + / -50% of the switching frequency.

Description

Technical Field

[0001] The present disclosure relates to the field of electrical devices, and more particularly, to a multi-phase resonant power converter. Background Art

[0002] Most commercially available isolated three-phase power converters typically include a non-isolated PFC (power factor correction) rectifier front end and require a second stage on the primary side for DC-DC conversion and isolation. A relatively new branch of research is the subject of single-stage three-phase isolated converters designed for direct connection to the grid. However, single-stage three-phase isolated converters typically require 1200V rated bidirectional switching devices and feature complex control concepts or fixed output voltages. Phase modular solutions utilize 600V / 650V rated bidirectional switching devices on the primary side, but a larger number (3×4) of bidirectional switching devices are required, and the current circulating through the transformer and switches is always determined by the grid phase carrying the highest current. Even if a phase momentarily provides a low level of power (for example near the zero crossing of the grid cycle), the switching devices and transformer windings of that phase still have to carry the same current as during the peak of the grid cycle, which is inefficient.

[0003] Therefore, there is a need for an improved multi-phase resonant power converter. Summary of the invention

[0004] According to an embodiment of a multi-phase resonant power converter, the multi-phase resonant power converter includes: a power stage on the primary side of the multi-phase resonant power converter, the power stage including a plurality of bridge converter legs, each of the plurality of bridge converter legs being configured to receive an AC input voltage and implement a separate phase of the multi-phase resonant power converter; a transformer device having a primary side winding for each bridge converter leg of the power stage and a secondary side winding for each primary side winding; a power supply circuit electrically connected to the secondary side winding of the transformer device on the secondary side of the multi-phase resonant power converter; a primary side controller configured to operate the bridge converter legs of the power stage at a switching frequency; and a separate resonant tank electrically connected to the midpoint of each bridge converter leg of the power stage, each resonant tank including a resonant capacitor connected in series with the primary side winding for the bridge converter leg, wherein the resonant frequency of each resonant tank is tuned to within + / -50% of the switching frequency.

[0005] According to an embodiment of a method of operating a multi-phase resonant power converter, the method includes: applying an AC input voltage to a bridge converter leg of a power stage; operating the bridge converter leg of the power stage at a switching frequency; and selecting the switching frequency so that the resonant frequency of each resonant tank is tuned to within + / - 50% of the switching frequency.

[0006] According to another embodiment of a multi-phase resonant power converter, the multi-phase resonant power converter includes: a plurality of primary side bridge converter legs on the primary side of the multi-phase resonant power converter, each primary side bridge converter leg being configured to receive an AC input voltage and implement a separate phase of the multi-phase resonant power converter; a plurality of secondary side bridge converter legs on the secondary side of the multi-phase resonant power converter, each secondary side bridge converter leg being configured to implement a separate phase of the multi-phase resonant power converter; a transformer device having a primary side winding for each primary side bridge converter leg and a secondary side winding for each secondary side bridge converter leg; at least one controller configured to operate the secondary side bridge converter leg and the primary side bridge converter leg at a switching frequency; and a separate resonant tank electrically connected to a midpoint of each secondary side bridge converter leg, each resonant tank including a resonant capacitor connected in series with the secondary side winding for the secondary side bridge converter leg, wherein the resonant frequency of each resonant tank is tuned to within + / -50% of the switching frequency.

[0007] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The elements in the figures are not necessarily to scale with each other. Similar reference numerals designate corresponding similar parts. Unless they are mutually exclusive, the features of the various illustrated embodiments may be combined. The embodiments are depicted in the figures and are described in detail in the following description.

[0009] Figure 1 A schematic diagram of a multi-phase resonant power converter according to an embodiment is illustrated.

[0010] Figure 2 Represents the 3-phase voltage system transformed to the stationary reference frame (α-β).

[0011] Figure 3 The primary side voltage and the secondary side voltage of a transformer device of a multiphase resonant power converter are illustrated respectively, wherein the resonant tank of the multiphase resonant power converter is generally represented as a single tank. Figure 3 Also illustrated is a SVM (Space Vector Modulation) control scheme for the switching devices of the secondary side power circuit.

[0012] Figure 4 The simulation results of a multi-phase resonant power converter operating in boost mode during a mains cycle and for a target output voltage of 500V are shown.

[0013] Figure 5 Pictured Figure 4 A time-scaled view of the

[0014] Figure 6The diagram shows Figure 4 The same waveforms, but for simulation of a multiphase resonant power converter operating in buck mode and for a target output voltage of 200V.

[0015] Figure 7 Picture shows Figure 6 A time-scaled view of the

[0016] Figure 8 An embodiment of a multi-phase resonant power converter is illustrated in which the AC input voltage has a single phase.

[0017] Fig. 9 An SVM control scheme is illustrated that creates a hexagonal pattern of voltage vectors in the α-β plane, where the voltage magnitudes are proportional to the single AC input voltage. Fig. 9 Also shown is a single phase of the AC input voltage varying over time.

[0018] Fig.10 Picture shows Figure 8 Simulation results of a multi-phase resonant power converter embodiment during a mains cycle and for a target output voltage of 400V.

[0019] Fig.11 Picture shows Fig.10 A time-scaled view of the

[0020] Fig.12 A multi-phase resonant power converter according to another embodiment is illustrated.

[0021] Fig.13 A multi-phase resonant power converter according to another embodiment is illustrated.

[0022] Fig.14 A multi-phase resonant power converter according to another embodiment is illustrated.

[0023] Fig.15 A multi-phase resonant power converter according to another embodiment is illustrated.

[0024] Fig.16A and Fig. 16B A multi-phase resonant power converter according to another embodiment is illustrated.

[0025] Fig.17 A schematic diagram of a power supply circuit on the secondary side of a multi-phase resonant power converter according to another embodiment is illustrated.

[0026] Fig.18 A schematic diagram of a power supply circuit on the secondary side of a multi-phase resonant power converter according to another embodiment is illustrated.

[0027] Fig.19A schematic diagram of a power supply circuit on the secondary side of a multi-phase resonant power converter according to another embodiment is illustrated.

[0028] Fig. 20 A schematic diagram of a power supply circuit on the secondary side of a multi-phase resonant power converter according to another embodiment is illustrated.

[0029] Fig.21 A schematic diagram of a power supply circuit on the secondary side of a multi-phase resonant power converter according to another embodiment is illustrated.

[0030] Fig. 22 Picture shows Fig.21 Simulation results of a diode rectifier power supply circuit embodiment during a mains cycle and for a target output voltage of 480V.

[0031] Fig.23 Picture shows Fig. 22 A time-scaled view of the

[0032] Fig.24 A multi-phase resonant power converter according to another embodiment is illustrated.

[0033] Fig.25 A schematic diagram of a transformer device of a multi-phase resonant power converter according to another embodiment is illustrated.

[0034] Fig.26 A transformer arrangement according to another embodiment is illustrated. DETAILED DESCRIPTION

[0035] This article describes circuits, topologies, and control embodiments for an isolated resonant power converter that is phase-modular, bidirectional, and has a single power stage on the primary side of the converter. The single primary side power stage includes multiple bridge converter legs, each of which is configured to receive an AC input voltage and implement a separate phase of a multi-phase resonant power converter. The transformer device isolates the primary side and secondary side currents of the multi-phase resonant power converter (i.e., there is no direct conduction path). The transformer device has a primary side winding for each bridge converter leg of the primary side power stage and a secondary side winding for each primary side winding. An active or passive power supply circuit on the secondary side of the multi-phase resonant power converter is electrically connected to the secondary side winding of the transformer device and outputs a DC voltage.

[0036] A separate resonant tank is provided on the primary side or the secondary side of each phase of the multi-phase resonant power converter. For example, if implemented on the primary side, a separate resonant tank is electrically connected to the midpoint of each bridge converter leg of the power stage, wherein each resonant tank has a resonant capacitor in series with the primary side winding for that bridge converter leg. If implemented on the secondary side instead, a separate resonant tank is electrically connected to the midpoint of each secondary side bridge converter leg, wherein each resonant tank has a resonant capacitor in series with the secondary side winding for that secondary side bridge converter leg. For both primary side and secondary side implementations, the resonant frequency of each resonant tank is tuned to within + / - 50% of the switching frequency at which the bridge converter leg of the primary side power stage operates. The switching frequency may be constant or variable.

[0037] The power converter circuits, topologies, and control embodiments described herein provide high frequency isolation, support switching using ZVS (zero voltage switching) on ​​the primary side, enable synchronous rectification and bidirectional power flow, support output voltage regulation, provide PFC (power factor correction) functionality, have low control complexity, require fewer primary side switching devices (e.g., only 6×600 / 650V bidirectional switching devices), can operate at a fixed switching frequency, provide single-phase and multi-interoperability, and allow a separate high frequency transformer to be integrated into a single magnetic device. Other advantages will become apparent as various embodiments are described in more detail below.

[0038] Exemplary embodiments of power converter circuits, topologies, and control embodiments are described next with reference to the figures.

[0039] Figure 1 A schematic diagram of a multiphase resonant power converter according to an embodiment is illustrated. The multiphase resonant power converter includes a power stage 100 on the primary side of the multiphase resonant power converter. The transformer device 102 isolates the primary side and the secondary side of the multiphase resonant power converter galvanically (i.e., there is no direct conduction path). The transformer device 102 can be implemented as a discrete high-frequency transformer with a separate magnetic device, or as a separate high-frequency transformer integrated into a single magnetic device.

[0040] The power stage 100 has a plurality of bridge converter legs 104, each bridge converter leg 104 being configured to receive an AC input voltage U abc , such as an AC grid voltage, and implements the individual phases of a multiphase resonant power converter. Figure 1 In the embodiment, each bridge converter leg 104 of the primary side power stage 100 is a half-bridge converter leg, which includes a bridge converter leg 104 at the midpoint of the bridge converter leg 104. Two power switching devices S connected in series n , S' nThe active control leg is formed, where the subscript 'n' indicates the phase number on the primary side and the capital subscript 'N' indicates the phase number on the secondary side. n In parallel with each active control leg 104. In one embodiment, for example, the power switch device S n , S' n Each has a voltage rating, which is determined by the AC input voltage U abc The phase-to-neutral voltage of the power supplies is defined instead of the line-to-line voltage, which may be 600V.

[0041] The transformer device 102 has a primary side winding 106 for each bridge converter leg 104 of the primary side power stage 100 and a secondary side winding 108 for each primary side winding 106. The power circuit 110 is electrically connected to the secondary side winding 108 of the transformer device 102 on the secondary side of the multi-phase resonant power converter. The power circuit 110 outputs a voltage across the output capacitor C dc The DC voltage U dc , where according to the primary side control mode, the DC voltage U dc The line-to-line voltage U of the transformer device 102 on the secondary side can be LLs Large (in boost mode) or low (in buck mode).

[0042] The individual resonant tanks 112 are electrically connected to Figure 1 The midpoint of each bridge converter leg 104 of the primary side power stage 100 Each resonant tank 112 includes a resonant capacitor C in series with the primary winding 106 for that bridge converter leg 104. sn .

[0043] The primary side controller 114_1 receives measurement inputs (not shown), such as current measurements, voltage measurements, etc., and operates the bridge converter leg 104 of the primary side power stage 100 at a switching frequency that may be constant or variable. sn is selected / sized so that the resonant frequency of each resonant tank 112 is tuned to within + / - 50% of the switching frequency at which the primary side controller 114_1 operates the bridge converter leg 104 of the power stage 100. The resonant frequency of each resonant tank 112 is determined by the resonant capacitor C sn The size of is determined by the leakage inductance of the transformer device 102. Therefore, the resonant capacitor C of each resonant tank 112 is snare selected / sized to be very different from conventional low frequency AC blocking capacitors which are selected / sized to prevent transformer saturation. This means that the resonant capacitor C of each resonant tank 112 is sn Having a capacitance value that is an order of magnitude different from (or greater than) that of conventional low frequency AC blocking capacitors.

[0044] In the case where the primary side controller 114_1 uses a constant or variable switching frequency and due to the AC input voltage U abc At low frequency, e.g. 50 Hz to 60 Hz for mains (power line) power, each phase has an AC input voltage U abc An approximately (quasi) rectangular voltage is applied to the corresponding resonant tank 112 of the envelope. Figure 1 The voltage envelope of the resonant tank 112 supporting the first ('a') phase is shown.

[0045] Also in Figure 1 , the power circuit 110 on the secondary side has a half-bridge rectifier leg 116 for each phase of the multi-phase resonant power converter, where the subscript 'N' indicates the number of phases on the secondary side. Each active switch half-bridge rectifier leg 116 on the secondary side includes a half-bridge rectifier leg 116 at the midpoint of the active switch. A pair of power switching devices S connected in series N , S' N , wherein the corresponding secondary winding 108 of the transformer device 102 is electrically connected to the midpoint The half-bridge rectifier legs 116 are electrically connected in parallel to form a single DC output U of the secondary side power circuit 110. dc .

[0046] The power switching device S included in the primary side power stage 100 n , S' n The power switching device S included in the secondary side power supply circuit 110 may be a bidirectional (dual gate) power switching device, such as a bidirectional GaN switching device. N , S' N It can be a unidirectional (single gate) device such as a power MOSFET (metal oxide semiconductor field effect transistor), IGBT (isolated gate bipolar transistor) or a unidirectional GaN device. For example, the primary side power switch device S n , S' n It can have a voltage rating of 600V / 650V. For example, according to the output voltage U dc , secondary side power switching device S N , S' N Can be either 600V or 1200V rated devices.

[0047] The switching device S of the secondary side power supply circuit 110 N , S' N It is controlled by space vector control or duty cycle control to apply a voltage on the secondary side of the transformer device 102 so that a resonant current can be seen in the transformer device 102 and a certain power level is delivered from each phase, thereby providing a PFC function. Since the PFC function is provided by generating a resonant or quasi-resonant current in the transformer device 102 and delivering a certain power level from each phase, a separate PFC stage is not required. Therefore, a single power stage 100 is used on the primary side of the multi-phase resonant power converter. EMI (electromagnetic interference) filter stage ( Figure 1 ) can be placed on the primary side power stage 100 and provide an AC input voltage U abc between the power grids.

[0048] In the case of boost operation, the primary side controller 114_1 operates the primary side power stage 100 without pulse skipping so that the DC output voltage U dc Higher than the line-to-line voltage u of the transformer device 102 on the secondary side LLs In the case of buck operation, the primary side controller 114_1 operates the primary side power stage 100 with pulse skipping which still provides a resonant or quasi-resonant transformer current iTa, iTb, iTc, but causes the DC output voltage U dc Lower than the line-to-line voltage u of the transformer device 102 on the secondary side LLs The PFC function occurs because the secondary side power circuit 110 operates in such a way that the amplitude of the resonant pulses within the grid / AC mains cycle is correctly adjusted to follow a sinusoidal envelope so that, together with the sinusoidal envelope of the transformer voltage, a sin 2 The power of shape.

[0049] exist Figure 1 In the resonant converter topology, the bridge converter leg 104 on the primary side is connected in a Y-connection, and the Y-connection can be attached to the grid neutral conductor 105. With this Y-connection, the power switching device S n , S' n Only the line-to-neutral AC input voltage must be blocked. The half-bridge rectifier legs 116 of the active switches on the secondary side can also be connected in a Y configuration, such as Figure 1More generally, the bridge converter leg 104 of the primary side power stage 100 may be connected to the primary side winding 106 of the transformer device 102 in a wye configuration, a delta configuration, or a star configuration, and the rectifier leg 116 of the secondary side power circuit 110 may be connected to the secondary side winding 108 of the transformer device 102 in a wye configuration, a delta configuration, or a star configuration. The connection configurations on the primary side and the secondary side of the multi-phase resonant power converter may be of the same type or of different types.

[0050] Next, refer to Figures 2 to 7 Describe in more detail Figure 1 The operation of the multiphase resonant power converter is shown.

[0051] Figure 2 represents the three-phase voltage system transformed to the stationary reference frame (α-β), where the AC input voltage vector U abc Moving on a circle with a constant amplitude given by the amplitude of the grid voltage at a constant speed given by the grid frequency fn. Figure 3 The left hand side of the diagram shows the line-to-line voltage u on the primary and secondary sides of the transformer device. LLp 、u LLs , where the resonant slot is generally represented as a single slot C s / L s . Figure 3 The right-hand side of FIG. 1 illustrates a switching device S for the secondary side power supply circuit 110. N , S' N SVM (space vector modulation) control scheme.

[0052] The controller 114_2 for the secondary side receives measurement inputs (not shown), such as current measurements, voltage measurements, etc., and generates a PWM (Pulse Width Modulation) signal SVM_PWM_S N / S' N , for controlling the switching device S of the secondary side power supply circuit 110 by the SVM N , S' N The rectifier leg 116 of the secondary side power circuit 110 may be an actively switched half-bridge or full-bridge rectifier leg, and the secondary side controller 114_2 controls the actively switched half-bridge or full-bridge rectifier leg 116 of the power circuit 110 by the SVM so that a resonant or quasi-resonant current flows in the primary side winding 106 and the secondary side winding 108 of the transformer device 102 .

[0053] SVM defines multiple switching and zero voltage vectors. Figure 3 As shown, for example, in a 7-segment SVM, the switching voltage vector to They correspond to the SVM switch states

[100] ,

[110] ,

[010] ,

[011] ,

[001] and

[101] respectively. The zero voltage vector corresponds to the SVM switch states

[000] and

[111] .

[0054] Each switch voltage vector to A state in which the generated voltage vector of the secondary side power supply circuit 110 has a non-zero magnitude and phase is defined. Figure 3 The reference vector in the SVM shown in the space vector diagram of is approximately composed of a regular hexagon with sectors A to F. For example, Figure 3 The voltage space vector in sector A is With amplitude |V ref | and angle θ, and at the grid angular frequency ω n Rotate. Figure 2 and Figure 3 , 'R' represents the real axis, and 'I' represents the imaginary axis.

[0055] The secondary side controller 114_2 uses SVM-based closed-loop PWM control to track the power reference. For different SVM-based PWM modes, such as 7-segment SVM-based PWM, 5-segment SVM-based PWM, 3-segment SVM-based PWM, phase-shifted PWM based on 7, 5, 3-segment SVM PWM, and any other SVM-based PWM mode, the closed-loop control implemented by the secondary side controller 114_2 is very similar.

[0056] The primary side controller 114_1 operates the multiphase resonant power converter by switching the bridge converter leg 104 on the primary side within 50% of the resonant frequency, such as within 20% or less of the resonant frequency. The resonant frequency is determined by the resonant capacitor C sa , C sb , C sc The selection of and the leakage inductance of the transformer device 102 determine the primary side input capacitor C a , C b , C c are sized / designed to keep the respective bridge leg input voltage stable at the selected switching frequency. The input capacitor C a , C b , C c May form part of an EMI filter.

[0057] The secondary side of the multiphase resonant power converter essentially replicates the primary side voltage vector, where the length of the voltage space vector varies slightly to control power flow. The voltage vector applied by the SVM on the secondary side of the transformer device 102 can be adjustable so that bidirectional power flow can be achieved. For example, the amplitude of the local average value can be adjusted within half a switching cycle of the primary side converter stage voltage space vector. In another example, a phase shift can be adopted on the secondary side, for example, when reactive power is imported from the AC grid.

[0058] like Figure 2 As shown, the primary side switching device S n , S' n Basically at a constant frequency with the AC input voltage U abc The voltage space vector is in phase with the voltage space vector and the AC input voltage U abc The voltage space vector is shifted by 180°. The AC input voltage U abc Applied to the primary side of the resonant tank 112. The secondary side switching device S N , S' N use Figure 3 The vector of the SVM shown in the right hand portion of is used to apply a voltage on the secondary side of the transformer device 102 and drive a certain amount of power through the resonant tank 112 during the positive and negative primary side half switching cycles. n , S' n PWM signal PWM_S n / S' n synchronization, so that the primary side switching device S n , S' n Switch at the same time.

[0059] The secondary-side controller 114_2 generates a corresponding SVM-based PWM signal SVM_PWM_S N / S' N , for controlling the secondary side power supply circuit 110 by the SVM so as to apply a voltage on the secondary side, so that power is driven through one or more resonant tanks 112 on the primary side in each positive and negative primary side half-switching cycle of the primary side power stage 100. The secondary side controller 114_2 can adjust the voltage vector applied to the secondary side by space vector modulation to control the power flow on the secondary side, for example, the output voltage U in the boost mode dc The secondary side controller 114_2 may vary the length of the secondary side voltage vector to control the power flow and provide bidirectional power flow capability. Unless pulse skipping is applied when operating in buck mode, the primary side controller 114_1 may simply apply a defined pulse pattern to the switching device S of the power stage 100. n, S' n , and the secondary side controller 114 tracks the power reference using closed loop SVM control.

[0060] Figure 4 The diagram shows the operation of a multiphase resonant power converter in boost mode during a mains cycle and for a target output voltage U of 500 V. dc The simulation results are shown in Figure 2. Figure 4 The waveforms shown include the phase (grid) voltage u a 、u b 、u c , converter output voltage U dc , phase (grid) current i a 、i b 、i c , primary side transformer current iT a 、iT b 、iT c , primary side transformer winding voltage uT a ,uT b ,uT c , secondary side transformer winding voltage uT A ,uT B ,uT C , resonant capacitor voltage uC sa 、uC sb 、uC sc And the corresponding cycle average value uC sa_avg 、uC sb_avg 、uC sc_avg . Figure 5 The diagram shows Figure 4 The same simulation results are shown, but only for part of the mains cycle.

[0061] The primary side controller 114_1 converts the PWM signal PWM_S to n / S' n is applied to the bridge converter leg 104 of the power stage 100 to operate the primary side power stage 100 in boost mode so that the resonant power transfer cycle is not skipped and the secondary side power supply circuit 110 outputs a DC voltage U dc , the DC voltage U dc The line-to-line voltage u of the transformer device 102 on the secondary side LLs Big. Figure 4 and Figure 5 As shown, the converter output voltage U dc is controlled to a constant value, and the grid current i a 、i b 、i c With grid voltage u a 、u b、u c In phase, thus providing PFC function.

[0062] Similarly, the primary side transformer current iT a 、iT b 、iT c The magnitude of varies depending on the power drawn from each grid phase. This means that the transformer device 102 and the primary-side switching device S n , S' n The current stress in the circuit changes with the grid cycle, rather than the transformer device 102 and the primary side switch device S n , S' n The maximum current drawn from any of the three phases is always stressed.

[0063] Figure 4 and Figure 5 shows a 500V output voltage U dc An example of boost operation where no primary side pulses are skipped. Figure 4 and Figure 5 As shown, the SVM-based PWM closed-loop control implemented on the secondary side generates resonant or quasi-resonant currents iTa, iTb, iTc in the primary winding 106 of the transformer device 102 , which appear as resonant or quasi-resonant currents in the secondary winding 108 .

[0064] like Figure 4 and Figure 5 As shown, the primary side power stage 100 reduces the grid voltage level by half so that the transformer primary side voltage is within + / -0.5*U abc The transformer device 102 may have a non-unity winding ratio. In this case, the voltage u generated on the secondary side transformer winding 108 is LLs It is related to the minimum dc link voltage in boost operation without pulse skipping conditions, wherein the minimum dc link voltage for boost operation is defined by the line-to-line voltage of the transformer secondary winding 108 .

[0065] Figure 6 The diagram shows Figure 4 The same waveforms, but for the buck mode and for a target output voltage U of 200V dc Simulation of a multiphase resonant power converter. Figure 7 The diagram shows Figure 6 The same simulation results are shown, but only for part of the mains cycle.

[0066] Using the boost control scheme described above, in order to apply the appropriate voltage vector on the secondary side, the output voltage U dcmust be higher than the voltage uT applied on the primary side A ,uT B ,uT C , assuming a 1:1 transformer ratio. To enable buck (low voltage) operation, the primary side controller 114_1 switches the PWM signal PWM_S to n / S' n is applied to the bridge converter leg 104 of the power stage 100 to operate the primary side power stage 100 so that an integer number of resonant power transfer cycles are periodically skipped and the secondary side power supply circuit 100 outputs a DC voltage U dc , the DC voltage U dc The line-to-line voltage u of the transformer device 102 on the secondary side LLs By skipping an integer number (1, 2, 3, etc.) of primary-side resonant cycles, the average length of the primary-side voltage vector magnitude at the transformer terminals is reduced. This allows the output voltage U dc , while using SVM on the secondary side to control the power flow, as in the case of boost operation. Figure 6 and Figure 7 shows a 250V output voltage U dc An example of buck operation is shown in Figure 1, where Figure 7 As shown by the vertical dashed rectangle in FIG. 1 , one (1) out of every three (3) primary side pulses is skipped.

[0067] The AC input voltage U applied to the power stage 100 on the primary side of the multiphase resonant power converter abc It can be single-phase voltage or multi-phase voltage. Figure 1 In the case of AC input voltage U abc With three (3) phases u a 、u b 、u c . Also in Figure 1 In the embodiment, each bridge converter leg 104 of the primary side power stage 100 receives an AC input voltage U abc The individual phase u n , and includes a single pair of bidirectional switch devices S electrically connected in a half-bridge configuration a , S' a The primary side controller 114_1 synchronously operates the bridge converter leg 104 of the power stage 100 under PWM control with a duty cycle of 50%.

[0068] Figure 8 The diagram shows the AC input voltage U abc Embodiment of a multiphase resonant power converter with a single phase. According to this embodiment, the bridge converter legs 104 of the primary side power stage 100 are connected in parallel with each other and receive an AC input voltage Uabc The multiphase resonant power converter has P phases, where P is a positive integer greater than or equal to 1, and the multiphase resonant power converter can be operated on a single-phase grid by connecting all phase terminals a, b, c, etc. of the primary side power stage 100 in parallel to the single-phase electrical network. Each bridge converter leg 104 of the primary side power stage 100 can have a single pair of bidirectional switching devices S electrically connected in a half-bridge configuration. n , S' n (For example, Figure 8 According to this embodiment, the primary side controller 114_1 is controlled by PWM with a duty cycle of 50%. The bridge converter leg 104 of the primary side power stage 100 is operated in phase shift.

[0069] The phase shift adopted in single-phase operation ensures sufficient power transmission. In single-phase operation, all primary-side bridge converter legs 104 are connected to the same grid voltage U abc In this case, synchronous PWM with 50% on-time only generates the common-mode switch node voltage without transferring power to the secondary side; therefore, when using single-phase operation Phase shift.

[0070] exist Figure 8 In the example shown in Figure 1, P = 3 and the phase shift is 120° while still operating at a 50% duty cycle. Fig. 9 As shown in the lower part of the figure, this control scheme creates a hexagonal pattern of voltage vectors in the α-β plane, where the diameter of the pattern is proportional to the AC input voltage U abc The angle ωt is proportional to the grid frequency, that is, it grows and shrinks with twice the grid frequency. Fig. 9 The upper part shows the time variation of the AC input voltage U abc The secondary side controller 114 applies pulses on the secondary side with different duty cycles, where the length of the pulse depends on the phase angle ωt and the required power flow.

[0071] Fig.10 Pictured Figure 8 The multiphase resonant power converter embodiment is shown in FIG. 1 during a mains cycle and for a target output voltage U of 400 V. dc The simulation results are shown in Figure 2. Fig.10 The waveforms shown include the primary side transformer winding voltage uT a ,uT b ,uT c , Single-phase AC input voltage U abc , secondary side transformer winding voltage uT A ,uT B ,uTC , converter output voltage U dc , primary side transformer current iT a 、iT b 、iT c , resonant capacitor voltage uC sa 、uC sb 、uC sc and the power flow P for each phase of the multiphase resonant power converter a , P b , P c . Fig.11 The diagram shows Fig.10 The same simulation results are shown, but only for part of the mains cycle.

[0072] Fig.12 A multiphase resonant power converter according to another embodiment is shown. Fig.12 , with each active control leg S of the primary side power stage 100 n / S' n The parallel capacitor leg includes the upper capacitor C n1 , the upper capacitor C n1 At the midpoint of the capacitor legs The lower capacitor C n2 Each resonant tank 112 on the primary side is electrically connected to the midpoint of the capacitor leg for the corresponding phase of the power stage 100. and bridge converter leg midpoint between.

[0073] Fig.13 A multiphase resonant power converter according to another embodiment is shown. Fig.13 In the case of AC input voltage U abc With a single phase (such as Figure 8 As shown), and each active control leg S of the primary side power stage 100 n / S' n The parallel capacitor leg includes the upper capacitor C n1 , the upper capacitor C n1 At the midpoint of the capacitor legs The lower capacitor C n2 Series (such as Fig.13 Therefore, Fig.13 The embodiment shown will Figure 8 and Fig.12 feature combination.

[0074] Fig.14 A multiphase resonant power converter according to another embodiment is shown. Fig.14In the embodiment, the dual capacitor capacitor leg of the primary side is replaced by another active bridge leg. According to this embodiment, each bridge converter leg 104 of the primary side power stage 100 receives the AC input voltage U abc The individual phase u n , and having two pairs of bidirectional switching devices S electrically connected in a full-bridge configuration n1 / S' n1 , S n2 / S' n2 In this embodiment, the primary side controller 114_1 synchronously operates the bridge converter leg 104 of the power stage 100 under PWM control with a duty cycle of 50%. In one embodiment, for example, the power switching device S n1 / S' n1 , S n2 / S' n2 Each has a voltage rating, which is determined by the AC input voltage U abc The phase-to-neutral voltage is defined by the phase-to-neutral voltage, rather than by the line-to-line voltage which can be 600V.

[0075] Fig.15 A multiphase resonant power converter according to another embodiment is shown. Fig.15 In the example, a single pair of power switching devices S forming each bridge converter leg 104 of the primary side power stage 100 is provided. n / S' n It has unidirectional voltage blocking capability. Fig.15 The power switching device S forming each bridge converter leg 104 n / S' n Has a single gate. Fig.15 In an embodiment, the multiphase resonant power converter has P phases, where P is a positive integer greater than or equal to 2, and the primary side controller 114_1 synchronously operates the bridge converter legs 104 of the power stage 100 under PWM control with a duty cycle of 50%. For example, Fig.15 Unidirectional power switching device S n / S' n This can be a Si or SiC power MOSFET, single-phase GaN HEMT, etc., and has a voltage rating of >800V.

[0076] Fig.16A and Fig. 16B A multiphase resonant power converter according to another embodiment is shown. Fig.16A and Fig. 16B In the embodiment, each bridge converter leg 104 of the primary side power stage 100 includes two pairs of power switching devices S with unidirectional voltage blocking capability. n1 / S' n2 For example, with Fig.15 Unidirectional power switching device S n / S' n compared to, Fig.16A and Fig. 16B Unidirectional power switching device S n1 / S' n2 May have voltage ratings >400V. Fig.16A and Fig. 16B Unidirectional power switching device S n1 / S' n2 It can be Si or SiC power MOSFET, single-phase GaN HEMT, etc.

[0077] Fig.17 FIG. 1 is a schematic diagram of a power supply circuit 110 on the secondary side of a multi-phase resonant power converter according to another embodiment. Fig.17 In , the multiphase resonant power converter has P phases, where P is a positive integer greater than or equal to 2, and the secondary side power supply circuit 110 has M half-bridge rectifier legs 116, where M is a positive integer greater than or equal to P+1. Fig.17 , the secondary side half-bridge rectifier legs 116 are shown as half-bridge rectifier legs 116, each of which is implemented as a single pair of unidirectional power switching devices S N / S' N , such as Si or SiC power MOSFET, unidirectional GaN HEMT, etc., the unidirectional power switching device S N / S' N At the midpoint of the half-bridge rectifier leg 116 of the active switch Electrically connected in series.

[0078] In either case, the additional secondary side rectifier leg(s) 116_d provide the secondary side controller 114_2 with one or more additional degrees of freedom (ie, more independence between phases) when implementing SVM-based closed-loop PWM. Fig.17 One additional secondary side rectification leg 116_d is shown. More generally, the secondary side power supply circuit 110 may have one or more additional secondary side rectification legs 116_d exceeding the number of phases supported by the multi-phase resonant power converter.

[0079] Fig.18 FIG. 1 is a schematic diagram of a power supply circuit 110 on the secondary side of a multi-phase resonant power converter according to another embodiment. Fig.18 , the bridge rectifier leg 116 of the secondary side power circuit 110 is connected to the secondary side winding 108 of the transformer device 102 in a delta configuration.

[0080] Fig.19FIG. 1 is a schematic diagram of a power supply circuit 110 on the secondary side of a multi-phase resonant power converter according to another embodiment. Fig.19 In the embodiment, the secondary side power supply circuit 110 has at least one additional secondary side rectifier leg 116_d exceeding the number of phases supported by the multi-phase resonant power converter, wherein four (or more) winding terminals are accessible instead of three and connected to four (or more) secondary side rectifier legs 116, which achieves a further degree of freedom.

[0081] Fig. 20 FIG. 1 is a schematic diagram of a power supply circuit 110 on the secondary side of a multi-phase resonant power converter according to another embodiment. Fig. 20 In the embodiment, the bridge rectifier leg 116 of the secondary side power supply circuit 110 is a full-bridge rectifier leg, and each full-bridge rectifier leg is implemented by: at the first midpoint of the full-bridge rectifier leg 116 of the active switch A first pair of unidirectional power switch devices S connected in series N1 / S' N1 , and at the second midpoint of the full-bridge rectifier leg 116 of the active switch The first pair of unidirectional power switch devices S N1 / S' N1 The second pair of unidirectional power switching devices S connected in parallel N2 / S' N2 The full-bridge rectifier legs 116 are electrically connected in parallel to form a single DC output U of the secondary side power circuit 110. dc The single-phase power switching device S forming the full-bridge rectifier leg 116 N1 / S' N1 , S N2 / S' N2 It can be Si or SiC power MOSFET, unidirectional GaN HEMT, etc. With a full-bridge implementation of the secondary side power supply circuit 110, the full-bridge rectifier leg 116 uses +Udc and -Udc, which allows to halve the transformer currents iTa, iTb, iTc. In case of high DC output voltages, zero intervals can be inserted. More generally, an additional degree of freedom of the SVM is achieved.

[0082] Fig.21 FIG. 1 is a schematic diagram of a power supply circuit 110 on the secondary side of a multi-phase resonant power converter according to another embodiment. Fig.21 In the embodiment, the secondary side power supply circuit 110 is a diode rectifier that does not require active control on the secondary side. The diode rectifier has a diode rectifier leg 200 for each phase of the multi-phase resonant power converter. Each diode rectifier leg 200 on the secondary side includes a diode rectifier leg 200 at the midpoint of the diode rectifier leg 200. A pair of diode devices D connected in series N , D' N .

[0083] Fig. 22 Picture shows Fig.21 The diode rectifier power supply circuit embodiment of the invention is used in the mains cycle and for a target output voltage U of about 480V. dc Simulation results. Fig. 22 The waveforms shown include the phase (grid) voltage u a 、u b 、u c , phase (grid) current i a 、i b 、i c , primary side transformer winding voltage uT a ,uT b ,uT c , primary side transformer current iT a 、iT b 、iT c , secondary side transformer winding voltage uT A ,uT B ,uT C , converter output voltage U dc , converter power output P out . Fig.23 The diagram shows Fig. 22 The same simulation results are shown, but only for part of the mains cycle.

[0084] According to this embodiment, the multi-phase resonant power converter has P phases, where P is a positive integer greater than or equal to 2. The primary side controller 114_1 is controlled by PWM with a duty cycle of 50%. The bridge converter leg 104 of the primary side power stage 100 is operated in phase shift so that a resonant or quasi-resonant current flows in the primary side winding 106 and the secondary side winding 108 of the transformer device 102. In this embodiment, no active control is performed directly on the secondary side. The primary side controller 114_1 can operate the bridge converter leg 104 of the primary side power stage 100 with pulse skipping to control the DC output voltage U of the secondary side power supply circuit 110. dc .

[0085] Fig.24 A multiphase resonant power converter according to another embodiment is shown. Fig.24 In the embodiment, the resonant tank 112 is on the secondary side of the power converter, rather than the primary side. According to this embodiment, each individual resonant tank 112 is electrically connected to the midpoint of the corresponding secondary side bridge converter leg 116. Each resonant tank 112 on the secondary side of the power converter includes a resonant capacitor C sn , resonant capacitor C sn is connected in series with the secondary winding 108 for the secondary side bridge converter leg 116. The resonant frequency of each resonant tank 112 is tuned to within + / - 50% of the switching frequency used by the primary side controller 114_1, as previously described. The primary side power stage 100 may have the aforementioned combination Figure 1 , Figure 8 and Figures 12 to 16A , Fig. 16B Any configuration described.

[0086] The multiphase resonant power converter may also include a separate low frequency AC blocking capacitor C bn , which is electrically connected to the midpoint of each primary side bridge converter leg 104 and in series with the primary side winding 106 for the primary side bridge converter leg 104. The low frequency AC blocking capacitor C ba , C bb , C bc The resonant frequency of the resonant tank 112 is not tuned to the secondary side. ba , C bb , C bc is selected / sized to provide low frequency AC blocking and thereby prevent saturation of the transformer device 102 .

[0087] AC blocking capacitor C ba , C bb , C bc presents sufficiently high impedance at the grid frequency so that little or no low frequency voltage components appear across transformer device 102, but they are large enough so that the AC blocking capacitors C ba , C bb , C bc Compared to the transformer leakage inductance, it is electrically invisible at the switching frequency. Therefore, the AC blocking capacitor C ba , C bb , C bc The selection / sizing of the resonant capacitor C on the secondary side sa , C sb , C sc The choice / sizing of the resonant capacitor C sa , C sb , C sc Possibly with AC blocking capacitor C ba , C bb , C bc The difference is at least an order of magnitude.

[0088] The transformer device 102 included in the multiphase resonant power converter can be implemented as a separate transformer for each phase supported by the multiphase resonant power converter. According to this embodiment, each separate transformer includes a separate magnetic core and a primary winding 106 and a secondary winding 108 for the phase wound on the magnetic core.

[0089] Fig.25 FIG. 1 shows a schematic diagram of a transformer device 102 according to another embodiment. Fig.25 In the embodiment of the present invention, the primary side winding 106 and the secondary side winding 108 of the transformer device 102 are integrated with a single magnetic structure 300. The magnetic structure has a magnetic leg 302 for each phase n of the power converter. For each phase of the power converter, the primary winding 106 and the secondary winding 108 of the transformer device 102 are wound on the same magnetic leg 302. In this way, low rated power switching devices (e.g., 650V) can be used in a half-bridge configuration for a lower component count while also integrating the primary side winding and the secondary side winding 106, 108 into a single transformer structure. This approach provides a multi-phase resonant power converter solution with reduced cost and a smaller footprint.

[0090] Fig.26 A transformer arrangement 102 according to another embodiment is illustrated. Fig.26 The embodiments shown in Fig.25 However, in Fig.26 In the embodiment of the present invention, the single magnetic structure 300 has at least one additional magnetic leg 304 for adjusting the leakage flux of the transformer device 102 and thereby adjusting the resonant frequency of the resonant tank 112. No winding is wound around the additional magnetic leg(s) 304. Fig.26 Two (2) additional magnetic legs 304_a, 304_b are shown. More generally, a single magnetic structure 300 may have one or more additional magnetic legs 304.

[0091] Although the present disclosure is not so limited, the following numbered examples demonstrate one or more aspects of the present disclosure.

[0092] Example 1. A multiphase resonant power converter comprising: a power stage on the primary side of the multiphase resonant power converter, the power stage including a plurality of bridge converter legs, each of the plurality of bridge converter legs being configured to receive an AC input voltage and implement a separate phase of the multiphase resonant power converter; a transformer device having a primary side winding for each bridge converter leg of the power stage and a secondary side winding for each primary side winding; a power supply circuit electrically connected to the secondary side winding of the transformer device on the secondary side of the multiphase resonant power converter; a primary side controller configured to operate the bridge converter legs of the power stage at a switching frequency; and a separate resonant tank electrically connected to a midpoint of each bridge converter leg of the power stage, each resonant tank comprising a resonant capacitor connected in series with the primary side winding for the bridge converter leg, wherein the resonant frequency of each resonant tank is tuned to within + / -50% of the switching frequency.

[0093] Example 2. A multiphase resonant power converter according to Example 1, wherein each bridge converter leg of the power stage includes a plurality of switching devices, and wherein the primary side controller is configured to operate the switching devices at a constant switching frequency between a voltage space vector that is in phase with a voltage space vector of the AC input voltage and a voltage space vector that is shifted 180° from the voltage space vector of the AC input voltage.

[0094] Example 3. A multiphase resonant power converter according to Example 2, wherein the secondary side controller is configured to control the power circuit through space vector modulation to apply a voltage on the secondary side so that power is driven through one or more resonant tanks on the primary side during each positive and negative primary side half-switching cycle of the power stage.

[0095] Example 4. The multiphase resonant power converter of Example 3, wherein the secondary side controller is configured to adjust a voltage vector applied to the secondary side by space vector modulation to control power flow on the secondary side.

[0096] Example 5. A multi-phase resonant power converter according to any one of Examples 1 to 4, wherein the AC input voltage has multiple phases, wherein each bridge converter leg of the power stage is configured to receive a separate phase of the AC input voltage and includes a single pair of bidirectional switching devices electrically connected in a half-bridge configuration, and wherein the primary side controller is configured to synchronously operate the bridge converter legs of the power stage under PWM (pulse width modulation) control with a duty cycle of 50%.

[0097] Example 6. A multi-phase resonant power converter according to any one of Examples 1 to 4, wherein the AC input voltage has multiple phases, wherein each bridge converter leg of the power stage is configured to receive a separate phase of the AC input voltage and includes two pairs of bidirectional switching devices electrically connected in a full-bridge configuration, and wherein the primary side controller is configured to synchronously operate the bridge converter legs of the power stage under PWM (pulse width modulation) control with a duty cycle of 50%.

[0098] Example 7. A multi-phase resonant power converter according to any one of Examples 1 to 4, wherein the AC input voltage has multiple phases, wherein each bridge converter leg of the power stage is configured to receive a separate phase of the AC input voltage and includes a single pair of power switching devices having a unidirectional voltage blocking capability and electrically connected in a half-bridge configuration or two pairs of power switching devices having a unidirectional voltage blocking capability and electrically connected in a full-bridge configuration, wherein the multi-phase resonant power converter has P phases, and P is a positive integer greater than or equal to 2, and wherein the primary side controller is configured to synchronously operate the bridge converter legs of the power stage under PWM (pulse width modulation) control with a duty cycle of 50%.

[0099] Example 8. A multiphase resonant power converter according to any one of Examples 1 to 4, wherein the AC input voltage has a single phase, wherein the bridge converter legs of the power stage are connected in parallel with each other and are configured to receive a single phase of the AC input voltage, wherein the multiphase resonant power converter has P phases, and P is a positive integer greater than or equal to 1, and wherein the primary side controller is configured to control the AC input voltage at a duty cycle of 50% under PWM (pulse width modulation) control. Phase-shifted operation of the power stage of the bridge converter leg.

[0100] Example 9. A multiphase resonant power converter according to Example 8, wherein each bridge converter leg of the power stage includes a single pair of bidirectional switch devices electrically connected in a half-bridge configuration or two pairs of bidirectional switch devices electrically connected in a full-bridge configuration.

[0101] Example 10. A multi-phase resonant power converter according to any one of Examples 1 to 5 and 7 to 9, wherein each bridge converter leg of the power stage is a half-bridge converter leg, comprising: an active control leg formed by two power switching devices electrically connected in series at a midpoint of the bridge converter leg; and a capacitor leg connected in parallel with the active control leg.

[0102] Example 11. A multiphase resonant power converter according to any one of Examples 1 to 10, wherein the primary side controller is configured to operate the power stage in a boost mode by applying a PWM (pulse width modulation) signal to a bridge converter leg of the power stage without pulse skipping so that a resonant power transfer cycle is not skipped and the power supply circuit outputs a DC voltage greater than a line-to-line voltage of a transformer device on the secondary side.

[0103] Example 12. A multiphase resonant power converter according to any one of Examples 1 to 11, wherein the primary side controller is configured to operate the power stage in a buck mode by applying a PWM (pulse width modulation) signal to a bridge converter leg of the power stage with pulse skipping so that an integer number of resonant power transfer cycles are periodically skipped and the power supply circuit outputs a DC voltage that is lower than the line-to-line voltage of a transformer device on the secondary side.

[0104] Example 13. A multiphase resonant power converter according to any one of Examples 1 to 12, wherein the power supply circuit includes a half-bridge or full-bridge rectifier leg of an active switch for each phase of the multiphase resonant power converter, and wherein the secondary side controller is configured to control the half-bridge or full-bridge rectifier leg of the active switch of the power supply circuit through space vector modulation so that a quasi-resonant current flows in the primary side winding and the secondary side winding of the transformer device.

[0105] Example 14. A multiphase resonant power converter according to any one of Examples 1 to 12, wherein the power supply circuit is a diode rectifier, wherein the multiphase resonant power converter has P phases, and P is a positive integer greater than or equal to 2, and wherein the primary side controller is configured to control the primary side of the multiphase resonant power converter under PWM (pulse width modulation) control with a duty cycle of 50%. Phase-shifted operation of the power stage of the bridge converter leg.

[0106] Example 15. A multiphase resonant power converter according to any one of Examples 1 to 12 and 14, wherein the power circuit is a diode rectifier and wherein the primary side controller is configured to operate a bridge converter leg of the power stage with pulse skipping to control the DC output of the power circuit.

[0107] Example 16. A multiphase resonant power converter according to any one of Examples 1 to 15, wherein the multiphase resonant power converter has P phases, and P is a positive integer greater than or equal to 2, and wherein the power supply circuit includes M half-bridge or full-bridge rectifier legs, and M is a positive integer greater than or equal to P+1.

[0108] Example 17. A multiphase resonant power converter according to any one of Examples 1 to 16, wherein each bridge converter leg of the power stage includes a single pair of switching devices electrically connected in a half-bridge configuration or two pairs of switching devices electrically connected in a full-bridge configuration, and wherein for each bridge converter leg of the power stage, the voltage rating of each switching device included in the bridge converter leg of the power stage is defined by the relative neutral point voltage of the AC input voltage.

[0109] Example 18. A multiphase resonant power converter according to any one of Examples 1 to 17, wherein the primary side winding and the secondary side winding of the transformer device are integrated with a single magnetic structure.

[0110] Example 19. A multiphase resonant power converter according to Example 18, wherein a single magnetic structure has a magnetic leg for each phase of the power converter, and wherein for each phase of the power converter, the primary winding and the secondary winding of the transformer device are wound on the same magnetic leg.

[0111] Example 20. A multiphase resonant power converter according to Example 18 or 19, wherein the single magnetic structure has at least one additional magnetic leg for adjusting the leakage flux of the transformer device and thus adjusting the resonant frequency of the resonant slot.

[0112] Example 21. A multi-phase resonant power converter according to any one of Examples 1 to 20, wherein the power circuit includes a separate half-bridge or full-bridge rectifier leg for each phase of the power stage, wherein the bridge converter legs of the power stage are connected to the primary side winding of the transformer device in a Y configuration, a triangle configuration, or a star configuration, and wherein the half-bridge or full-bridge rectifier legs of the power circuit are connected to the secondary side winding of the transformer device in a Y configuration or a triangle configuration.

[0113] Example 22. A multiphase resonant power converter according to any one of Examples 1 to 21, wherein the power circuit includes a separate half-bridge or full-bridge rectifier leg for each phase of the power stage, wherein the half-bridge or full-bridge rectifier legs are electrically connected in parallel to form a single DC output of the power circuit, and wherein the primary side winding and the secondary side winding of the transformer device are integrated with a single magnetic structure.

[0114] Example 23. A method of operating a multiphase resonant power converter, the multiphase resonant power converter comprising: a power stage on the primary side of the multiphase resonant power converter, the power stage comprising a plurality of bridge converter legs, each of the plurality of bridge converter legs being configured to implement a separate phase of the multiphase resonant power converter; a transformer device having a primary side winding for each bridge converter leg of the power stage and a secondary side winding for each primary side winding; a power supply circuit electrically connected to the secondary side winding of the transformer device on the secondary side of the multiphase resonant power converter; and a separate resonant tank electrically connected to the midpoint of each bridge converter leg of the power stage, each resonant tank comprising a resonant capacitor connected in series with the primary side winding for the bridge converter leg, the method comprising: applying an AC input voltage to the bridge converter legs of the power stage; operating the bridge converter legs of the power stage at a switching frequency; and selecting the switching frequency so that the resonant frequency of each resonant tank is tuned to within + / -50% of the switching frequency.

[0115] Example 24. A multiphase resonant power converter, comprising: a plurality of primary side bridge converter legs on the primary side of the multiphase resonant power converter, each primary side bridge converter leg being configured to receive an AC input voltage and implement a separate phase of the multiphase resonant power converter; a plurality of secondary side bridge converter legs on the secondary side of the multiphase resonant power converter, each secondary side bridge converter leg being configured to implement a separate phase of the multiphase resonant power converter; a transformer device having a primary side winding for each primary side bridge converter leg and a secondary side winding for each secondary side bridge converter leg; at least one controller configured to operate the secondary side bridge converter legs and the primary side bridge converter legs at a switching frequency; and a separate resonant tank electrically connected to a midpoint of each secondary side bridge converter leg, each resonant tank comprising a resonant capacitor connected in series with the secondary side winding for the secondary side bridge converter leg, wherein the resonant frequency of each resonant tank is tuned to within + / -50% of the switching frequency.

[0116] Example 25. The multi-phase resonant power converter of Example 24 further includes: a separate low-frequency AC blocking capacitor electrically connected to the midpoint of each primary side bridge converter leg and in series with the primary side winding for that primary side bridge converter leg, wherein the low-frequency AC blocking capacitor is not tuned to the resonant frequency of the resonant tank on the secondary side.

[0117] Terms such as "first", "second", etc. are used to describe various elements, regions, parts, etc., and are not intended to be limiting. Throughout the specification, similar terms refer to similar elements.

[0118] As used herein, the terms "having", "comprising", "including", "comprising", etc. are open terms, indicating the presence of stated elements or features, but not excluding additional elements or features. The articles "a", "an", and "the" are intended to include both the singular and the plural, unless the context clearly indicates otherwise.

[0119] The wording "and / or" should be interpreted as including all possible conjunctions and disjunctions, unless expressly stated otherwise. For example, the wording "A and / or B" should be interpreted as meaning only A, only B, or A and B. The wording "at least one of" should be interpreted in the same manner as "and / or". For example, the wording "at least one of A and B" should be interpreted as meaning only A, only B, or A and B.

[0120] It should be understood that the features of the various embodiments described herein may be combined with each other, unless specifically stated otherwise.

[0121] Although specific examples have been illustrated and described herein, it will be appreciated by those skilled in the art that various alternative and / or equivalent embodiments may be substituted for the specific examples shown and described without departing from the scope of the present invention. This application is intended to cover any changes or variations of the specific embodiments discussed herein. Therefore, the present invention is intended to be limited only to the claims and their equivalents.

Claims

1. A multiphase resonant power converter, comprising: a power stage on the primary side of the multiphase resonant power converter, the power stage comprising a plurality of bridge converter legs, each of the plurality of bridge converter legs being configured to receive an AC input voltage and implement a separate phase of the multiphase resonant power converter; a transformer device having a primary side winding for each bridge converter leg of said power stage and a secondary side winding for each primary side winding; a power circuit electrically connected to the secondary side winding of the transformer device on the secondary side of the multi-phase resonant power converter; a primary side controller configured to operate the bridge converter leg of the power stage at a switching frequency; and a separate resonant tank electrically connected to a midpoint of each bridge converter leg of the power stage, each resonant tank comprising a resonant capacitor connected in series with the primary side winding for the bridge converter leg, The resonant frequency of each resonant tank is tuned to within + / - 50% of the switching frequency.

2. A multiphase resonant power converter according to claim 1, wherein each bridge converter leg of the power stage includes a plurality of switching devices, and wherein the primary side controller is configured to operate the switching devices at a constant switching frequency, between a voltage space vector that is in phase with a voltage space vector of the AC input voltage and a voltage space vector that is shifted 180° from the voltage space vector of the AC input voltage.

3. A multi-phase resonant power converter according to claim 2, wherein the secondary side controller is configured to control the power supply circuit through space vector modulation to apply a voltage on the secondary side so that power is driven through one or more of the resonant tanks on the primary side during each positive and negative primary side half-switching cycle of the power stage.

4. The multiphase resonant power converter of claim 3, wherein the secondary side controller is configured to adjust a voltage vector applied to the secondary side by the space vector modulation to control a power flow of the secondary side.

5. The multi-phase resonant power converter of claim 1 , wherein the AC input voltage has multiple phases, wherein each bridge converter leg of the power stage is configured to receive a separate phase of the AC input voltage and includes a single pair of bidirectional switch devices electrically connected in a half-bridge configuration, and wherein the primary side controller is configured to synchronously operate the bridge converter legs of the power stage under pulse width modulation (PWM) control with a duty cycle of 50%.

6. The multi-phase resonant power converter of claim 1 , wherein the AC input voltage has multiple phases, wherein each bridge converter leg of the power stage is configured to receive a separate phase of the AC input voltage and comprises two pairs of bidirectional switch devices electrically connected in a full-bridge configuration, and wherein the primary side controller is configured to synchronously operate the bridge converter legs of the power stage under pulse width modulation (PWM) control with a duty cycle of 50%.

7. A multi-phase resonant power converter according to claim 1, wherein the AC input voltage has multiple phases, wherein each bridge converter leg of the power stage is configured to receive a separate phase of the AC input voltage and includes a single pair of power switching devices having a unidirectional voltage blocking capability and electrically connected in a half-bridge configuration or two pairs of power switching devices having a unidirectional voltage blocking capability and electrically connected in a full-bridge configuration, wherein the multi-phase resonant power converter has P phases, and P is a positive integer greater than or equal to 2, and wherein the primary side controller is configured to synchronously operate the bridge converter legs of the power stage under pulse width modulation (PWM) control with a duty cycle of 50%.

8. The multiphase resonant power converter of claim 1 , wherein the AC input voltage has a single phase, wherein the bridge converter legs of the power stage are connected in parallel with each other and are configured to receive the single phase of the AC input voltage, wherein the multiphase resonant power converter has P phases, and P is a positive integer greater than or equal to 1, and wherein the primary side controller is configured to operate at a duty cycle of 50% under pulse width modulation (PWM) control. The bridge converter legs of the power stage are operated in phase shift.

9. The multiphase resonant power converter of claim 8, wherein each bridge converter leg of the power stage comprises a single pair of bidirectional switch devices electrically connected in a half-bridge configuration or two pairs of bidirectional switch devices electrically connected in a full-bridge configuration.

10. The multiphase resonant power converter of claim 1 , wherein each bridge converter leg of the power stage is a half-bridge converter leg, comprising: an actively controlled leg formed by two power switching devices electrically connected in series at said midpoint of said bridge converter leg; as well as A capacitor leg is connected in parallel with the active control leg.

11. The multiphase resonant power converter of claim 1 , wherein the primary side controller is configured to operate the power stage in a boost mode by applying a pulse width modulation (PWM) signal to the bridge converter leg of the power stage without pulse skipping, so that a resonant power transfer cycle is not skipped and the power supply circuit outputs a DC voltage greater than a line-to-line voltage of the transformer device on the secondary side.

12. The multiphase resonant power converter of claim 1 , wherein the primary side controller is configured to operate the power stage in a buck mode by applying a pulse width modulated (PWM) signal to the bridge converter leg of the power stage with pulse skipping, such that an integer number of resonant power transfer cycles are periodically skipped and the power supply circuit outputs a DC voltage lower than a line-to-line voltage of the transformer device on the secondary side.

13. A multi-phase resonant power converter according to claim 1, wherein the power supply circuit includes an actively switched half-bridge or full-bridge rectifier leg for each phase of the multi-phase resonant power converter, and wherein the secondary side controller is configured to control the actively switched half-bridge or full-bridge rectifier leg of the power supply circuit through space vector modulation so that a quasi-resonant current flows in the primary side winding and the secondary side winding of the transformer device.

14. The multiphase resonant power converter according to claim 1, wherein the power supply circuit is a diode rectifier, wherein the multiphase resonant power converter has P phases, and P is a positive integer greater than or equal to 2, and wherein the primary side controller is configured to control the primary side of the multiphase resonant power converter with a duty cycle of 50% under a pulse width modulation (PWM) control. The bridge converter legs of the power stage are operated in phase shift.

15. The multiphase resonant power converter of claim 1, wherein the power circuit is a diode rectifier, and wherein the primary side controller is configured to operate the bridge converter leg of the power stage with pulse skipping to control the DC output of the power circuit.

16. A multi-phase resonant power converter according to claim 1, wherein the multi-phase resonant power converter has P phases, and P is a positive integer greater than or equal to 2, and wherein the power supply circuit includes M half-bridge or full-bridge rectifier legs, and M is a positive integer greater than or equal to P+1.

17. A multi-phase resonant power converter according to claim 1, wherein each bridge converter leg of the power stage includes a single pair of switching devices electrically connected in a half-bridge configuration or two pairs of switching devices electrically connected in a full-bridge configuration, and wherein for each bridge converter leg of the power stage, the voltage rating of each switching device included in the bridge converter leg of the power stage is defined by the relative neutral point voltage of the AC input voltage.

18. The multiphase resonant power converter of claim 1, wherein the primary side winding and the secondary side winding of the transformer device are integrated with a single magnetic structure.

19. A multi-phase resonant power converter according to claim 18, wherein the single magnetic structure has a magnetic leg for each phase of the power converter, and wherein for each phase of the power converter, the primary winding and the secondary winding of the transformer device are wound on the same magnetic leg.

20. The multi-phase resonant power converter of claim 18, wherein the single magnetic structure has at least one additional magnetic leg for adjusting the leakage flux of the transformer device, thereby adjusting the resonant frequency of the resonant tank.

21. A multi-phase resonant power converter according to claim 1, wherein the power supply circuit includes a separate half-bridge or full-bridge rectifier leg for each phase of the power stage, wherein the bridge converter legs of the power stage are connected to the primary side winding of the transformer device in a Y configuration, a triangle configuration or a star configuration, and wherein the half-bridge or full-bridge rectifier legs of the power supply circuit are connected to the secondary side winding of the transformer device in a Y configuration or a triangle configuration.

22. A multi-phase resonant power converter according to claim 1, wherein the power supply circuit includes a separate half-bridge or full-bridge rectifier leg for each phase of the power stage, wherein the half-bridge or full-bridge rectifier legs are electrically connected in parallel to form a single DC output of the power supply circuit, and wherein the primary side winding and the secondary side winding of the transformer device are integrated with a single magnetic structure.

23. A method of operating a multiphase resonant power converter, the multiphase resonant power converter comprising: a power stage on the primary side of the multiphase resonant power converter, the power stage comprising a plurality of bridge converter legs, each leg being configured to implement a separate phase of the multiphase resonant power converter; a transformer device having a primary side winding for each bridge converter leg of the power stage and a secondary side winding for each primary side winding; a power circuit electrically connected to the secondary side winding of the transformer device on the secondary side of the multi-phase resonant power converter; and a separate resonant tank electrically connected to a midpoint of each bridge converter leg of the power stage, each resonant tank comprising a resonant capacitor connected in series with the primary side winding for the bridge converter leg, the method comprising: applying an AC input voltage to the bridge converter leg of the power stage; operating the bridge converter leg of the power stage at a switching frequency; and The switching frequency is selected such that the resonant frequency of each resonant tank is tuned to within + / - 50% of the switching frequency.

24. A multiphase resonant power converter, comprising: a plurality of primary side bridge converter legs on a primary side of the multi-phase resonant power converter, each primary side bridge converter leg configured to receive an AC input voltage and implement a separate phase of the multi-phase resonant power converter; a plurality of secondary side bridge converter legs on a secondary side of the multi-phase resonant power converter, each secondary side bridge converter leg configured to implement a separate phase of the multi-phase resonant power converter; a transformer device having a primary side winding for each primary side bridge converter leg and a secondary side winding for each secondary side bridge converter leg; at least one controller configured to operate the secondary side bridge converter leg and the primary side bridge converter leg at a switching frequency; and a separate resonant tank electrically connected to a midpoint of each secondary side bridge converter leg, each resonant tank comprising a resonant capacitor connected in series with the secondary side winding for the secondary side bridge converter leg, The resonant frequency of each resonant tank is tuned to within + / - 50% of the switching frequency.

25. The multiphase resonant power converter of claim 24, further comprising: a separate low frequency AC blocking capacitor electrically connected to the midpoint of each primary side bridge converter leg and in series with the primary side winding for that primary side bridge converter leg, Wherein the low frequency AC blocking capacitor is tuned to the resonant frequency of the resonant tank on the secondary side.

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