SPH-SCC-based IPOP-LLC resonant converter and control method

Abstract

The invention discloses an SPH-SCC-based IPOP-LLC resonant converter and a control method, and the resonant converter comprises a primary inverter bridge, a resonant inductor, an excitation inductor, a parallel switch capacitor unit, a half-wave series switch capacitor unit, a transformer, and a load. The primary side inverter bridge is electrically connected with the parallel switch capacitor unit, the parallel switch capacitor unit is electrically connected with the half-wave series switch capacitor unit, and the half-wave series switch capacitor unit is electrically connected with the primary side of the transformer; the primary side inverter bridge is further electrically connected with the resonant inductor, the resonant inductor is electrically connected with the excitation inductor, the excitation inductor is connected with the primary side of the transformer in parallel, the secondary side of the transformer is electrically connected with a load, and the parallel switch capacitor unit and the half-wave series switch capacitor unit are used for adjusting the duty ratio of an internal switch. And the equivalent capacitance of the half-wave series switch capacitor unit is further adjusted. According to the technical scheme, the resonance conditions of all phases can be adjusted within a similar range, and good steady-state current sharing performance is achieved.

Description

Technical Field

[0001] This invention relates to the field of LLC resonant converters, and more particularly to an IPOP-LLC resonant converter, system, control method, and readable storage medium based on SPH-SCC. Background Technology

[0002] With the accelerated electrification of high-voltage, high-power electric drive systems in non-road construction machinery and heavy-duty mining transportation, the demand for high-power DC-DC converters is increasing daily. Input-Parallel-Output-Parallel (IPOP) power systems are widely used in high-power applications due to their modularity, high redundancy, and low single-phase current. LLC resonant converters, with their high efficiency, wide gain range, soft-switching characteristics, and low electromagnetic interference, are one of the mainstream topologies of IPOP power systems. However, parameter differences (such as inductance and capacitance differences), drive signal delays, and parasitic parameter mismatches between parallel modules can easily lead to uneven current distribution. If not effectively balanced, some modules will be overloaded for extended periods, accelerating device aging and even failure, threatening system reliability. Therefore, researching current sharing techniques for IPOP LLC resonant converters has significant practical implications.

[0003] In existing current sharing control methods for resonant converters, the droop method achieves current sharing by adjusting the equivalent internal resistance of the module, allowing the output voltage to vary with the load current. However, it is difficult to simultaneously achieve high current sharing accuracy and dynamic response. The master-slave control method based on the envelope model, combined with a resonant current loop, achieves excellent current sharing under different load conditions and exhibits enhanced dynamics. However, severe hardware mismatch can lead to large deviations in resonant parameters, and frequency-based voltage gain adjustment can cause periodic oscillations in the output current during transient processes.

[0004] Existing resonant converter topology optimization methods suppress inherent parameter mismatches between modules at the hardware level by introducing coupling elements or reconstructing the circuit topology, thus reducing reliance on complex control algorithms. Magnetic components, utilizing their inherent current-sharing characteristics, are widely used in parallel converters. Coupled inductors can adaptively ensure autonomous current sharing between parallel modules; while coupled transformers can provide both current balance and sufficient leakage inductance to meet operational requirements. However, current balancing based on magnetic fields often has limited scalability. In multiphase LLC converters, switched-controlled capacitors (SCCs) can address scalability issues by adjusting capacitor values ​​to mitigate inter-phase parameter variations. However, the limited capacitor adjustment range restricts current sharing effectiveness when parameter differences are large. Series-Parallel Hybrid Switched Controlled Capacitors (SPH-SCCs) significantly extend the gain range of LLC converters through four modes, but suffer from inductor current asymmetry in the half-wave series section.

[0005] The above summary reveals that relying solely on control methods or topology design has certain limitations. Therefore, it is necessary to further improve the current structure and control methods of resonant converters. Summary of the Invention

[0006] To solve at least one of the above-mentioned technical problems, the main objective of this invention is to provide an IPOP-LLC resonant converter based on SPH-SCC and its control method.

[0007] To achieve the above objectives, one technical solution adopted by the present invention is as follows: An IPOP-LLC resonant converter based on SPH-SCC is provided. The LLC resonant converter has at least two phases. Each phase of the LLC resonant converter includes: a primary-side inverter bridge, a resonant inductor, a magnetizing inductor, a parallel switched capacitor unit, a half-wave series switched capacitor unit, a transformer, and a load. The primary-side inverter bridge has a first arm and a second arm. The midpoint of the first arm is electrically connected to the parallel switched capacitor unit, the parallel switched capacitor unit is electrically connected to the half-wave series switched capacitor unit, and the half-wave series switched capacitor unit is electrically connected to the primary side of the transformer. The midpoint of the second arm is electrically connected to the resonant inductor, the resonant inductor is electrically connected to the magnetizing inductor, the magnetizing inductor is connected in parallel with the primary side of the transformer, and the secondary side of the transformer is electrically connected to the load. The resonant inductor, the magnetizing inductor, the parallel switched capacitor unit, and the half-wave series switched capacitor unit form a resonant slot. The parallel switched capacitor unit is used to adjust the equivalent capacitance of the parallel switched capacitor unit by adjusting the duty cycle of the internal switch; the half-wave series switched capacitor unit is used to adjust the equivalent capacitance of the half-wave series switched capacitor unit by adjusting the duty cycle of the internal switch.

[0008] In one embodiment of this invention, the parallel switched capacitor unit includes a first resonant capacitor, a first auxiliary capacitor, and a first auxiliary switch; the half-wave series switched capacitor unit includes a second auxiliary capacitor and a second auxiliary switch, the first auxiliary capacitor and the first auxiliary switch are connected in series, the first resonant capacitor is connected in parallel with the series-connected first auxiliary capacitor and the first auxiliary switch; the second auxiliary capacitor and the second auxiliary switch are connected in parallel. Specifically, when adjusting the duty cycle of the first auxiliary switch, the duration of the first auxiliary capacitor being connected to the circuit can be controlled, thereby adjusting the equivalent capacitance of the parallel switched capacitor unit; when adjusting the duty cycle of the second auxiliary switch, the time interval during which the second auxiliary capacitor is excluded from the circuit can be controlled, thereby adjusting the equivalent capacitance of the half-wave series switched capacitor unit.

[0009] As one embodiment of this invention, the equivalent capacitance of the parallel switched capacitor unit C eq_p The expression is: in, d a1 To depend solely on the duty cycle of the first auxiliary switch d The equivalent duty cycle of a parallel switched capacitor unit of 1, C r It is a resonant capacitor. C a1 This is the first auxiliary capacitor; The equivalent capacitance of the half-wave series switched capacitor unit C eq_s The expression is: in, d a2 It depends solely on the duty cycle of the second auxiliary switch. d The equivalent duty cycle of a 2-wave series switched capacitor unit. C a2 This is the second auxiliary capacitor; The equivalent capacitance of SPH-SCC after the parallel switched capacitor unit and the half-wave series switched capacitor unit are connected in series is... C scc The expression for the unified model is: .

[0010] As one implementation method of this embodiment, the equivalent load of the primary-side inverter bridge R eq The expression is: in, R L For load, n This refers to the turns ratio of the transformer. resonant frequency f r Equivalent capacitance of SPH-SCC C scc The relation is: The gain of the LLC resonant converter M scc The expression is: in, λ For resonant inductors L r With magnetizing inductor L m The ratio, f n For normalized frequency, f s The switching frequency of the primary-side inverter bridge. Q This is the quality factor.

[0011] To achieve the above objectives, another technical solution adopted by the present invention is: providing a control method for an IPOP-LLC resonant converter based on SPH-SCC, wherein the LLC resonant converter has two phases, and each phase of the LLC resonant converter includes an SPH-SCC composed of parallel switched capacitor units and half-wave series switched capacitor units, and the control method for the LLC resonant converter includes: After controlling the two-phase primary-side inverter bridge with the same switching frequency, the back end of the two-phase primary-side inverter is sampled to obtain the first sampling current and the second sampling current. The zero-crossing point of the first sampling current and the second sampling current is detected to determine the delay time of the two-phase SPH-SCC. Obtain the load output voltage and compare it with the reference voltage to obtain the switching cycle of the two-phase SPH-SCC; The two-phase output current is acquired and compared. The duty cycle of the first auxiliary switch is set to 0 based on the phase with the smaller current. Then, the initial duty cycle of the second auxiliary switch is determined by the PI controller. Iterative calculations are performed based on the minimum THD range of the equivalent capacitance of SPH-SCC and the total current to obtain the low THD duty cycle of the second auxiliary switch. The duty cycle of the second auxiliary switch is set to 0.5 based on the phase with the larger current. Then, the duty cycle of the first auxiliary switch is determined by the PI controller to obtain the low THD duty cycle of the two-phase auxiliary switches. The PWM signal of the SPH-SCC is generated based on the delay time of the two-phase SPH-SCC, the switching cycle of the two-phase SPH-SCC, and the duty cycle of the auxiliary switches of the two phases to control the operation of the two-phase SPH-SCC.

[0012] As one implementation of this solution, the step of iteratively calculating the minimum THD range of the equivalent capacitance and total current of the SPH-SCC to obtain the duty cycle of the second auxiliary switch with low THD specifically includes: Iterative calculations are performed based on the minimum THD range of the equivalent capacitance and total current of SPH-SCC to obtain the maximum or minimum duty cycle set of the second auxiliary switch, wherein each element in the duty cycle set corresponds to the minimum total harmonic distortion, while keeping the equivalent capacitance of SPH-SCC constant. Select one duty cycle element from the set of duty cycles of the second auxiliary switch as the duty cycle of the low THD of the second auxiliary switch.

[0013] As one implementation of this scheme, the minimum THD range of the total current is the duty cycle range of the second auxiliary switch corresponding to the interval where the THD is less than 50% of its maximum value, which are 0~0.158 and 0.375~0.5 respectively.

[0014] As one implementation of this solution, the control method further includes: Based on the average output current of the SPH-SCC LLC resonant converter I o_avg Define load sharing error σ load The expression is: The key waveforms of the SPH-SCC LLC resonant converter under full load and half load were detected based on the load current sharing error data.

[0015] To achieve the above objectives, another technical solution adopted by the present invention is as follows: a control system for an IPOP-LLC resonant converter based on SPH-SCC is provided, comprising an LLC resonant converter, a first PI controller, a second PI controller, a zero-crossing detector, and a data processor; the LLC resonant converter is electrically connected to the first PI controller, the zero-crossing detector, and the data processor respectively, and the second PI controller is electrically connected to the data processor. The first PI controller is used to determine the switching cycle of the two-phase SPH-SCC based on the comparison result between the load output voltage and the reference voltage. The second PI controller is used to determine the duty cycle of the second auxiliary switch according to the set duty cycle of the first auxiliary switch of the first phase, and to determine the duty cycle of the second auxiliary switch according to the set duty cycle of the first auxiliary switch of the second phase; The zero-crossing detector is used to detect the zero-crossing of the first sampling current and the second sampling current to determine the delay time of the two-phase SPH-SCC. The data processor is used to compare the output currents of two phases, set the duty cycle of the first auxiliary switch to 0 based on the phase with the smaller current, then determine the initial duty cycle of the second auxiliary switch according to the PI controller, and iterate based on the minimum THD range of the equivalent capacitance of SPH-SCC and the total current to obtain the duty cycle of the second auxiliary switch with low THD; set the duty cycle of the first auxiliary switch to 0.5 based on the phase with the larger current, and then determine the duty cycle of the second auxiliary switch according to the PI controller to obtain the duty cycle of the two-phase auxiliary switches; The data processor is connected to a memory that stores a computer program that can run on the data processor. When the data processor executes the computer program, it implements the step of determining the duty cycle of the two-phase auxiliary switch with low THD as described above.

[0016] To achieve the above objectives, another technical solution adopted by the present invention is to provide a readable storage medium on which a computer program is stored, wherein when the computer program is executed by a processor, the steps of the above method are implemented.

[0017] The LLC resonant converter of this invention mainly includes a primary-side inverter bridge, a resonant inductor, a magnetizing inductor, a parallel switched capacitor unit, a half-wave series switched capacitor unit, a transformer, and a load. The resonant inductor, magnetizing inductor, parallel switched capacitor unit, and half-wave series switched capacitor unit form a resonant slot. The parallel switched capacitor unit is used to adjust the equivalent capacitance of the parallel switched capacitor unit by adjusting the duty cycle of its internal switches. The half-wave series switched capacitor unit is also used to adjust the equivalent capacitance of the half-wave series switched capacitor unit by adjusting the duty cycle of its internal switches. By introducing the parallel switched capacitor unit and the half-wave series switched capacitor unit, this solution can adjust the resonant conditions of each phase within a similar range by adjusting the duty cycle of the internal switches, resulting in good steady-state current sharing performance.

[0018] The control method for an LLC resonant converter according to the present invention includes: firstly, after controlling two-phase primary-side inverter bridges at the same switching frequency, sampling the current at the back end of the two-phase primary-side inverters to obtain a first sampling current and a second sampling current, detecting the zero-crossing points of the first and second sampling currents, and determining the delay time of the two-phase SPH-SCC; then acquiring the load output voltage and comparing it with a reference voltage to obtain the switching period of the two-phase SPH-SCC; next, acquiring the two-phase output current and comparing them, setting the duty cycle of the first auxiliary switch to 0 based on the phase with the smaller current, and then determining the duty cycle of the second auxiliary switch according to the PI controller. The initial duty cycle of the switch is determined, and iterative calculations are performed based on the minimum THD range of the equivalent capacitance and total current of the SPH-SCC to obtain the low THD duty cycle of the second auxiliary switch. The duty cycle of the second auxiliary switch is set to 0.5 based on the phase with the larger current. Then, the duty cycle of the first auxiliary switch is determined according to the PI controller to obtain the low THD duty cycles of the two-phase auxiliary switches. Finally, the PWM signal of the SPH-SCC is generated based on the delay time of the two-phase SPH-SCC, the switching period of the two-phase SPH-SCC, and the duty cycle of the two-phase auxiliary switches to control the operation of the two-phase SPH-SCC. This method effectively compensates for the current imbalance problem caused by hardware parameter mismatch. Furthermore, the optimized duty cycle selection significantly reduces the current distortion introduced by the SPH-SCC series section. Compared with the traditional frequency-based control strategy used in parallel LLC resonant converters, this method adjusts the equivalent capacitance by controlling the duty cycle, which can adjust the resonance conditions of each phase within a similar range. This alleviates the control instability often observed in traditional methods due to large parameter mismatch, thereby ensuring good steady-state current sharing performance and significantly improving dynamic response. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the topology of a two-phase IPOP-LLC resonant converter based on SPH-SCC according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the equivalent AC circuit structure of an IPOP-LLC resonant converter based on SPH-SCC according to an embodiment of the present invention; Figure 3 This is a flowchart of a control method for an IPOP-LLC resonant converter based on SPH-SCC according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the duty cycle calculation and iteration process according to an embodiment of the present invention; Figure 5 The graph shows the fundamental sine wave of the total SDH-SCC and the RMSE of THD under different duty cycles of the second auxiliary switch in this embodiment. Figure 6a and Figure 6b The key waveforms of the IPOP-LLC resonant converter based on SPH-SCC in this embodiment under full load and half load are shown respectively. Figure 7a and Figure 7b The figures are dynamic performance curves of the control strategies of the IPOP-LLC converter based on SPH-SCC in this embodiment and the IPOP-SPH-SCC LLC converter in related technologies, respectively. Figure 8 The THD analysis results and fitting curves are shown for the second auxiliary switch in this embodiment of the invention when the duty cycle is 0.25~0.5. Figure 9 This is a grid diagram comparing the gain of the IPOP-LLC based on SPH-SCC and the traditional LLC resonant converter in this embodiment. Figure 10 A block diagram of a control system for an IPOP-LLC resonant converter based on SPH-SCC in one embodiment of the invention. Figure 11 This is a block diagram of the data processing module in the control system of an IPOP-LLC resonant converter based on SPH-SCC according to an embodiment of the present invention.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that the descriptions involving "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0024] Unlike LLC resonant converter technologies that rely solely on control methods or topology design and thus have limitations, this invention provides an IPOP-LLC resonant converter and its control method based on SPH-SCC. By optimizing the duty cycle control of the internal switches to adjust the equivalent capacitance, excellent steady-state current sharing performance is achieved. The specific structure of this SPH-SCC-based IPOP-LLC resonant converter, system, and control method is described in the following embodiments.

[0025] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the topology of a two-phase IPOP-LLC resonant converter based on SPH-SCC according to an embodiment of the present invention. In this embodiment, the LLC resonant converter based on SPH-SCC has at least two phases. Each phase of the LLC resonant converter includes: a primary-side inverter bridge and a resonant inductor. L r Magnetizing inductor L m Parallel switched capacitor unit, half-wave series switched capacitor unit, transformer and load R LThe primary-side inverter bridge has a first bridge arm and a second bridge arm. The midpoint of the first bridge arm is electrically connected to a parallel switched capacitor unit, which is electrically connected to a half-wave series switched capacitor unit. The half-wave series switched capacitor unit is electrically connected to the primary side of the transformer. The midpoint of the second bridge arm is connected to a resonant inductor. L r Electrical connection, the resonant inductor L r With magnetizing inductor L m Electrical connection, the excitation inductor L m The transformer is connected in parallel with the primary side, and the secondary side of the transformer is connected to the load. R L Electrical connection, the resonant inductor L r Magnetizing inductor L m Parallel switched capacitor units and half-wave series switched capacitor units form a resonant slot; The parallel switched capacitor unit is used to adjust the equivalent capacitance of the parallel switched capacitor unit by adjusting the duty cycle of the internal switch; the half-wave series switched capacitor unit is used to adjust the equivalent capacitance of the half-wave series switched capacitor unit by adjusting the duty cycle of the internal switch.

[0026] In this embodiment, the primary-side inverter bridge consists of four switching transistors, namely the first switching transistor. S 11 Second switching transistor S 12 Third switching transistor S 13 and the fourth switching transistor S 14 First switching transistor S 11 With the second switching transistor S 12 The connection forms the first bridge arm, and the third switching transistor. S 13 With the fourth switching transistor S 14 Form a second bridge arm to convert the input DC voltage V in The voltage is converted into a high-frequency square wave to provide AC excitation for the resonant cavity. The four switching transistors are all MOSFETs forming a full-bridge structure, alternately conducting to form positive and negative half-cycles. Through high-frequency switching, a high-frequency square wave excitation signal is generated at both ends of the resonant network. Specifically, the aforementioned switching transistors are metal MOSFETs, and this first switching transistor... S 11 Second switching transistor S 12 Third switching transistorS 13 and the fourth switching transistor S 14 Connect the full-bridge PWM signal. Resonant inductor. L r and excitation inductance L m These are either single inductors, or inductor units formed by multiple inductors connected in series or parallel. Resonant inductors. L r With resonant capacitor C r Together they form an LLC resonant network, achieving sinusoidal current waveform, and the resonant inductor L r Limiting the rate of change of current ensures a smooth current transition during commutation in the bridge arms, which is related to the resonant capacitor. C r The formation of series resonance determines the resonant frequency of the system. f r When the operating frequency is slightly higher than the resonant frequency f r At this time, the current lags behind the voltage, achieving ZVS (zero-voltage switching). Magnetizing inductor L m The magnetizing inductor provides excitation energy to the transformer and enables energy transfer. L m With resonant inductor L r The parallel connection determines the gain characteristics of the LLC; under light loads, the magnetizing current dominates energy transfer; the magnetizing inductor... L m The charging and discharging process helps achieve zero-voltage turn-on (ZVS) of the bridge arm MOSFETs, improving efficiency. Both parallel switched capacitor units and half-wave series switched capacitor units can adjust the equivalent capacitance of the half-wave series switched capacitor unit by optimizing the duty cycle of the internal switches. For the half-wave series switched capacitor unit, this significantly reduces the current distortion introduced by the half-wave series switched capacitor unit. Combining both, by adjusting the equivalent capacitance through duty cycle control, allows the resonant conditions of each phase to be adjusted within a similar range, mitigating the control instability often observed in traditional methods due to large parameter mismatches, thus ensuring good steady-state current sharing performance. Parallel switched capacitor units form dynamically controllable parallel resonant branches, achieving adjustable resonant parameters. Half-wave series switched capacitor units form half-wave series branches, expanding the gain adjustment range. Transformers are used to achieve electrical isolation and voltage transformation. Their primary side is excited by an LLC resonant network, and magnetic field energy is alternately transferred to the secondary side through the turns ratio. n Step down to a suitable output voltage, which is related to the magnetizing inductance. L mTogether, they determine the system's resonant characteristics and gain. This LLC resonant converter also includes a secondary rectifier bridge and a filter capacitor. The secondary rectifier bridge is electrically connected to the secondary side of the transformer, and the output of the secondary rectifier bridge is connected to the filter capacitor and the load. R L The secondary-side rectifier bridge consists of four switching transistors, which are diodes. Furthermore, according to... Figure 1 It can be seen that, V in It is the input voltage of the two-phase IPOP LLC. V o It is the output voltage of the two-phase IPOP LLC. I o It is the output current of the two-phase IPOP LLC. I o1 and I o2 It is the output current of a single-phase LLC. i p1 and i p2 It is the output current of the primary-side inverter bridge. R L The load is the resonant inductor described above. L r Including those located in the first phase L r1 and located in the second phase L r2 Magnetizing inductor L m Including those located in the first phase L m1 and located in the second phase L m2 .

[0027] In one specific embodiment, the parallel switched capacitor unit includes a first resonant capacitor. C r First auxiliary capacitor C a1 and the first auxiliary switch S a1 The half-wave series switched capacitor unit includes a second auxiliary capacitor. C a2 and the second auxiliary switch S a2 The first auxiliary capacitor C a1 With the first auxiliary switch S a1 The first resonant capacitor is connected in series. C r With the first auxiliary capacitor connected in series Ca1 and the first auxiliary switch S a1 Parallel connection; the second auxiliary capacitor C a2 With the second auxiliary switch S a2 in parallel; Among them, adjusting the first auxiliary switch S a1 When the duty cycle is set, the first auxiliary capacitor can be controlled. C a1 The duration of the adjustment, thereby adjusting the equivalent capacitance of the parallel switched capacitor unit; while adjusting the second auxiliary switch S a2 When the duty cycle is set, the second auxiliary capacitor can be controlled. S a2 The time interval excluded from the circuit is used to adjust the equivalent capacitance of the half-wave series switched capacitor unit.

[0028] In this embodiment, the aforementioned first auxiliary switch S a1 and the second auxiliary switch S a2 The controlled terminal (gate) is used to receive the PWM signal of SPH-SCC, and the first auxiliary switch is controlled according to the PWM signal of SPH-SCC. S a1 and the second auxiliary switch S a2 The opening and closing of the aforementioned first auxiliary capacitor. C a1 Including those located in the first phase C a11 and located in the second phase C a21 The aforementioned first auxiliary switch S a1 Including those located in the first phase S a11 and located in the second phase S a21 The aforementioned first resonant capacitor C r Including those located in the first phase C r1 and located in the second phase C r2 The aforementioned second auxiliary capacitor C a2 Including those located in the first phase C a12 and located in the second phase C a22 The aforementioned second auxiliary switch S a2Including those located in the first phase S a12 and located in the second phase S a22 First resonant capacitor C r The first auxiliary capacitor is the main energy storage and resonant element of the SPH-SCC, determining its resonant frequency and power transfer characteristics. C a1 As the control switch of the parallel switched capacitor unit, it determines the first auxiliary capacitor. C a1 Is it related to the resonant capacitor? C r Parallel connection. Specifically, when the first auxiliary switch... S a1 When turned on, the first auxiliary capacitor C a1 With the first resonant capacitor C r Parallel connection → Equivalent capacitance increases; when the first auxiliary switch S a1 When turned off, the circuit only has the first resonant capacitor. C r Participating in resonance → the equivalent capacitance decreases, thereby achieving dynamic control of the resonant frequency. This is achieved by controlling the second auxiliary capacitor. C a2 The duration of the circuit connection participates in the resonant branch during a specific period, achieving gain expansion and voltage boost. Second auxiliary switch. S a2 Used to control the second auxiliary capacitor C a2 The series conduction cycle enables a controllable series switched capacitor unit with "half-wave participation". When the second auxiliary switch... S a2 When turned on, the second auxiliary capacitor C a2 With the first resonant capacitor C r When connected in series, the equivalent capacitance decreases, and the resonant voltage increases.

[0029] In one specific embodiment, the equivalent capacitance of the parallel switched capacitor unit C eq_p The expression is: (1) (2) in, d a1 To depend solely on the duty cycle of the first auxiliary switch d The equivalent duty cycle of a parallel switched capacitor unit of 1, Cr It is a resonant capacitor. C a1 This is the first auxiliary capacitor; The equivalent capacitance of the half-wave series switched capacitor unit C eq_s The expression is: (3) (4) in, d a2 It depends solely on the duty cycle of the second auxiliary switch. d The equivalent duty cycle of a 2-wave series switched capacitor unit. C a2 This is the second auxiliary capacitor; Based on equations (1) and (3), after the parallel switched capacitor unit is connected in series with the half-wave series switched capacitor unit, the equivalent capacitance of SPH-SCC is... C scc The expression for the unified model is: (5).

[0030] The equivalent capacitances of the parallel switched capacitor unit and the half-wave series switched capacitor unit described above are derived based on the effective AC power supply and equivalent impedance of the SCC. By adjusting the duty cycle of the first auxiliary switch in the parallel switched capacitor unit, the duration of the first auxiliary capacitor's connection to the circuit can be controlled, thereby adjusting the equivalent capacitance of the parallel switched capacitor unit. By adjusting the duty cycle of the second auxiliary switch in the half-wave series switched capacitor unit, the time interval during which the second auxiliary capacitor is excluded from the circuit can be controlled.

[0031] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the equivalent AC circuit structure of an IPOP-LLC resonant converter based on SPH-SCC according to an embodiment of the present invention. In a specific embodiment, the equivalent load of the primary-side inverter bridge... R eq The expression is: (6) in, R L For load, n This refers to the turns ratio of the transformer. resonant frequency f r Equivalent capacitance of SPH-SCC C scc The relation is: (7) The gain of the LLC resonant converter M scc The expression is: (8) (9) in, λ For resonant inductors L r With magnetizing inductor L m The ratio, f n For normalized frequency, f s Q is the switching frequency of the primary-side inverter bridge, and Q is the quality factor.

[0032] In this embodiment, to facilitate the analysis of the output gain of the SPH-SCC LLC resonant converter, the AC equivalent circuit of the SPH-SCCLLC resonant converter is established as follows: Figure 2 As shown. v inFHA It is the equivalent AC input voltage of the primary-side inverter bridge based on the Fundamental Harmonic Approximation (FHA) method. n voFHA It is based on the equivalent AC output voltage of the primary-side inverter bridge. Based on equations (2), (4), (5), (6), (7), (8), and (9), due to the equivalent capacitance of SPH-SCC C scc Duty cycle of the first auxiliary switch d Duty cycle of 1 and second auxiliary switches d 2. Controlled, its capacitance value varies with the duty cycle, resulting in the resonant frequency. f r Variable. Therefore, given a fixed circuit parameter, the duty cycle of the first auxiliary switch of SPH-SCC can be controlled. d 1 and limiting the duty cycle of the second auxiliary switch d 2. To control the resonant frequency of the equivalent circuit. f r and quality factor Q This makes the gain of the LLC resonant converter... M scc It is no longer a single gain curve as in traditional LLC resonant converters, but a gain surface with a wide range.

[0033] Please refer to Figure 3 and Figure 4 , Figure 3This is a flowchart of a control method for an IPOP-LLC resonant converter based on SPH-SCC according to an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the duty cycle calculation and iteration process according to an embodiment of the present invention. In this embodiment, the control method for the SPH-SCC-based IPOP-LLC resonant converter uses a two-phase LLC resonant converter. Each phase of the LLC resonant converter includes an SPH-SCC composed of parallel switched capacitor units and half-wave series switched capacitor units. The control method for the LLC resonant converter includes the following steps: S100. After controlling the two-phase primary inverter bridge with the same switching frequency, the current at the back end of the two-phase primary inverter is sampled to obtain the first sampled current. i p1 With the second sampling current i p2 Detect the first sampling current i p1 Second sampling current i p2 The zero-crossing point is used to determine the delay time of the two-phase SPH-SCC. T s In this step, the two-phase primary-side inverter bridge is controlled with the same switching frequency, generating square waves of the same frequency and amplitude at the midpoint of the bridge arms. The back end of the aforementioned two-phase primary-side inverter is the SPH-SCC front end. This is achieved by controlling the delay time of the aforementioned two-phase SPH-SCC. T s It can achieve synchronous control of two-phase SPH-SCC.

[0034] S200: Obtain the load output voltage and compare it with the reference voltage to obtain the switching cycle of the two-phase SPH-SCC. Tθ In this step, the switching cycle of the two-phase SPH-SCC is used. Tθ It can achieve voltage closed-loop.

[0035] S300, obtain the two-phase output current, respectively io1 and io2The two-phase output currents are compared. The duty cycle of the first auxiliary switch is set to 0 based on the phase with the smaller current. Then, the initial duty cycle of the second auxiliary switch is determined using a PI controller. Iterative calculations are performed based on the minimum THD range of the equivalent capacitance of the SPH-SCC and the total current to obtain the low THD duty cycle of the second auxiliary switch. The duty cycle of the second auxiliary switch is set to 0.5 based on the phase with the larger current. The duty cycle of the first auxiliary switch is then determined using a PI controller, resulting in the low THD duty cycle of both auxiliary switches. In this step, different duty cycles are used with the SPH-SCC, and the low THD duty cycles of the two auxiliary switches are determined by comparing the magnitudes of the two-phase output currents. Specifically, for the phase with a smaller current, the duty cycle of the first auxiliary switch is first set to 0. Then, the initial duty cycle of the second auxiliary switch is determined using a PI controller. Next, iterative calculations are performed based on the equivalent capacitance relationship of SPH-SCC and the minimum THD (Total Harmonic Distortion) range to obtain the duty cycle of the second auxiliary switch with low THD. For the phase with a larger current, the duty cycle of the second auxiliary switch is set to 0.5, and then the duty cycle of the first auxiliary switch is determined using a PI controller.

[0036] S400, based on the delay time of the two-phase SPH-SCC Ts Switching cycle of two-phase SPH-SCC Tθ The duty cycle of the two-phase auxiliary switches generates the PWM signal for the SPH-SCC to control the operation of the two-phase SPH-SCC.

[0037] The implementation of the above embodiments effectively compensates for the current imbalance problem caused by hardware parameter mismatch. Furthermore, the optimized duty cycle selection significantly reduces the current distortion introduced by the SPH-SCC series section. Compared with the traditional frequency-based control strategy used in parallel LLC resonant converters, this method, by adjusting the equivalent capacitance through duty cycle control, can regulate the resonance conditions of each phase within a similar range, mitigating the control instability often observed in traditional methods due to large parameter mismatches. This ensures good steady-state current sharing performance while significantly improving dynamic response.

[0038] In one specific embodiment, the step of iteratively calculating the minimum THD range of the equivalent capacitance and total current of the SPH-SCC to obtain the duty cycle of the second auxiliary switch with low THD specifically includes: Iterative calculations are performed based on the minimum THD range of the equivalent capacitance and total current of SPH-SCC to obtain the maximum or minimum duty cycle set of the second auxiliary switch, wherein each element in the duty cycle set corresponds to the minimum total harmonic distortion, while keeping the equivalent capacitance of SPH-SCC constant. Select one duty cycle element from the set of duty cycles of the second auxiliary switch as the duty cycle of the low THD of the second auxiliary switch.

[0039] The above method can be used to achieve flow control based on duty cycle adjustment.

[0040] Please refer to Figure 5 , Figure 5 This is a graph showing the fundamental sine wave of the total SDH-SCC and the RMSE of THD under different duty cycles of the second auxiliary switch in this embodiment. In a specific embodiment, the minimum THD range of the total current is the range of duty cycle values ​​of the second auxiliary switch corresponding to the interval where THD is less than 50% of its maximum value, which are 0~0.158 and 0.375~0.5, respectively.

[0041] In this step, for the half-wave series SCC section, there is an asymmetry in the total current of SPH-SCC, which is significantly related to the duty cycle of the second auxiliary switch. To analyze the relationship between the duty cycle of the second auxiliary switch and the asymmetry, a Fast Fourier Transform (FFT) analysis was performed on the total current of SPH-SCC under different duty cycles of the second auxiliary switch, and the root mean square error (RMSE) was compared with that of the fundamental sine wave. The fitted curves and analysis results are as follows. Figure 5 As shown, the total harmonic distortion (THD) and RMSE of the total current in the SPH-SCC exhibit a pattern of high values ​​in the middle and low values ​​at both ends, reaching their maximum values ​​of 7.96% and 0.057A respectively when d2 = 0.27. To reduce the asymmetry of the total current in the SPH-SCC, using THD as a benchmark, the range of d2 values ​​corresponding to the intervals where THD is less than 50% of its maximum value is selected, specifically 0~0.158 and 0.375~0.5.

[0042] The specific process of iterative operation is as follows: 1. Input sampling Sample two-phase output current and .

[0043] 2. Current Comparison Determine the magnitude of the two-phase current: If this is true, it means that the current in the first phase is too small, and its equivalent capacitance (or equivalent gain) needs to be increased. If this is not the case, then the second phase current is smaller.

[0044] 3. Initial Condition Settings like :set up That is, the parallel SCC section is turned off, and then adjusted through the PI controller. Control the series SCC section.

[0045] like :set up That is, the series SCC section is fully conductive, and then adjusted by the PI controller. Control the parallel SCC section.

[0046] 4. PI Adjustment By adjusting the corresponding duty cycle using a proportional-integral (PI) controller, the target current error (difference between two-phase currents) is reduced.

[0047] The control output is the initial duty cycle estimate for the next iteration.

[0048] 5. According to Figure 9 Gain surface iterative optimization use Figure 9 SPH-SCC LLC gain surface relationship ( According to equation (5): Perform iterative calculations and adjustments This results in: equivalent capacitance Maintain a constant level while falling at the lowest THD level. Within the range (i.e., 0~0.158 or 0.375~0.5, from...) Figure 4 (Analysis results).

[0049] 6. Iterative Convergence and Output Repeat the above steps until the output current error meets the current sharing requirement (or the THD converges to the minimum).

[0050] Final output and The combination of these technologies achieves low THD and current balance.

[0051] In one specific embodiment, the control method further includes: Based on the average output current of the SPH-SCC LLC resonant converter I o_avg Define load sharing error σ load The expression is: (10) The key waveforms of the SPH-SCC LLC resonant converter under full load and half load were detected based on the load current sharing error data.

[0052] In related technologies, LLC resonant converters suffer from the problem of balancing current sharing accuracy and dynamic response, as well as periodic oscillations of the output current during transient processes. Please refer to... Figure 6a and Figure 6b , Figure 6a and Figure 6b The key waveforms of the IPOP-LLC resonant converter based on SPH-SCC in this embodiment under full load and half load are shown respectively. To verify the current sharing performance of the present invention, a two-phase 600W prototype with an input voltage of 160V was built. To evaluate the current sharing capability, the load current sharing error can be defined based on the average output current of the IPOP SPH-SCCLLC resonant converter. The key waveforms of the IPOP SPH-SCC LLC resonant converter under full load and half load are shown below. Figure 6a and 6b As shown. In Figure 6a and 6b The proposed IPOP-LLC resonant converter based on SPH-SCC exhibits excellent current sharing capability under both full-load and half-load conditions, achieving current sharing errors of 0.14% and 0.08%, respectively.

[0053] Please refer to Figure 7a and Figure 7b , Figure 7a and Figure 7b The figures show the dynamic performance curves of the control strategies for the IPOP-LLC converter based on SPH-SCC in this embodiment and the IPOP SPH-SCC LLC converter in related technologies. Figure 7a and Figure 7b The dynamic performance of the proposed SPH-SCC control strategy was compared with that of the traditional LLC PI control strategy. Among them, Figure 7a To illustrate the dynamic performance of the IPOP-LLC converter control strategy based on SPH-SCC in this embodiment, Figure 7b This paper presents the dynamic performance of the IPOP SPH-SCCLLC converter control strategy in related technologies. Compared with traditional frequency-based PI control, when the load jumps from full load to half load, the two-phase current stabilizes within 13ms under SPH-SCC control, while traditional frequency-based control requires 335.8ms. The proposed control strategy significantly shortens the settling time, exhibits excellent dynamic performance, and effectively suppresses current oscillations caused by large parameter mismatch.

[0054] In related technologies, the series-parallel hybrid switched-controlled capacitor (SPH-SCC) suffers from inductor current asymmetry in the half-wave series section. Please refer to... Figure 8 , Figure 8 This document presents the THD analysis results and fitting curves for the second auxiliary switch in this embodiment of the invention when its duty cycle is 0.25~0.5. To reduce the asymmetry of the total current in the SPH-SCC, THD is used as a metric, and the range of d2 values ​​corresponding to the interval where THD is less than 50% of its maximum value is selected. Figure 8 The figure shows the THD analysis results and fitting curves when d2 is between 0.25 and 0.5. It can be seen that the optimized duty cycle selection significantly reduces the current distortion introduced by the SPH-SCC series connection.

[0055] In related technologies, the limited capacitance adjustment range of switched-controlled capacitors (SCCs) restricts their current sharing effect when parameter differences are large. Please refer to... Figure 9 , Figure 9 This is a mesh diagram comparing the gain of the SPH-SCC-based IPOP-LLC resonant converter with that of a conventional LLC resonant converter in this embodiment. In this scheme, given fixed circuit parameters, the resonant frequency and quality factor of the equivalent circuit are adjusted by regulating the duty cycle of the first auxiliary switch of the SPH-SCC and limiting the duty cycle of the second auxiliary switch, thereby increasing the gain of the SPH-SCC LLC resonant converter. M scc It is no longer a single gain curve as in traditional LLC resonant converters, such as M con Instead, it is a wide-range gain surface, such as Figure 9 The grid diagram is shown below.

[0056] Please refer to Figure 10 , Figure 10 This is a block diagram of a control system for an IPOP-LLC resonant converter based on SPH-SCC, according to one embodiment of the invention. In this embodiment, the control system for the IPOP-LLC resonant converter based on SPH-SCC includes an LLC resonant converter, a first PI controller, a second PI controller, a zero-crossing detector, and a data processor. The LLC resonant converter is electrically connected to the first PI controller, the zero-crossing detector, and the data processor, respectively, and the second PI controller is electrically connected to the data processor.

[0057] The first PI controller is used to determine the switching cycle of the two-phase SPH-SCC based on the comparison result between the load output voltage and the reference voltage. The second PI controller is used to determine the duty cycle of the second auxiliary switch according to the set duty cycle of the first auxiliary switch of the first phase, and to determine the duty cycle of the second auxiliary switch according to the set duty cycle of the first auxiliary switch of the second phase; The zero-crossing detector is used to detect the zero-crossing of the first sampling current and the second sampling current to determine the delay time of the two-phase SPH-SCC. The data processor is used to compare the output currents of two phases, set the duty cycle of the first auxiliary switch to 0 based on the phase with the smaller current, then determine the initial duty cycle of the second auxiliary switch according to the PI controller, and iterate based on the minimum THD range of the equivalent capacitance of SPH-SCC and the total current to obtain the duty cycle of the second auxiliary switch with low THD; set the duty cycle of the first auxiliary switch to 0.5 based on the phase with the larger current, and then determine the duty cycle of the second auxiliary switch according to the PI controller to obtain the duty cycle of the two-phase auxiliary switches; The data processor is connected to a memory that stores a computer program that can run on the data processor. When the data processor executes the computer program, it implements the step of determining the duty cycle of the two-phase auxiliary switch with low THD as described above.

[0058] Figure 10 middle, i p1 and i p2 This represents the resonant current of the two-phase IPOP LLC. i o1 and i o2 This indicates the output current of the two-phase IPOP LLC. V in It is the input voltage of the two-phase IPOP LLC. V o It is the output voltage of the two-phase IPOP LLC. V ref It is the reference output voltage of the two-phase IPOP LLC. f s For the switching frequency of the two-phase IPOP LLC, T s For the switching cycle of two-phase IPOP LLC, T θ This refers to the delay time of the SPH-SCC. The two-phase SPH-SCC uses different duty cycles for control. d 11 The first auxiliary switch in the first phase parallel switched capacitor unit S a11 duty cycle, d 12The second auxiliary switch for the first phase half-wave series switched capacitor unit S a12 Duty cycle; d 21 The first auxiliary switch in the second phase parallel switched capacitor S a21 duty cycle, d 22 The second auxiliary switch for the second phase half-wave series switched capacitor unit S a22 Duty cycle.

[0059] Please see Figure 11 , Figure 11 This is a block diagram of the data processing module in a control system for an IPOP-LLC resonant converter based on SPH-SCC, according to an embodiment of the present invention. This control system for the IPOP-LLC resonant converter based on SPH-SCC can be used to implement the control method for the IPOP-LLC resonant converter based on SPH-SCC described in the aforementioned embodiments. Figure 11 As shown, the data processing module includes a memory 301, a processor 302, a bus 303, and a computer program stored in the memory 301 and executable on the processor 302. The memory 301 and the processor 302 are connected via the bus 303. When the processor 302 executes the computer program, it implements the functions described in the foregoing embodiments. The number of processors can be one or more.

[0060] The memory 301 can be a high-speed random access memory (RAM) or a non-volatile memory, such as a disk storage device. The memory 301 is used to store executable program code, and the processor 302 is coupled to the memory 301.

[0061] Furthermore, embodiments of this application also provide a computer-readable storage medium, which may be an IPOP-LLC resonant converter based on SPH-SCC disposed in the above embodiments, and the computer-readable storage medium may be the aforementioned Figure 11 The memory in the illustrated embodiment.

[0062] The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the control method for the SPH-SCC-based IPOP-LLC resonant converter described in the foregoing embodiments. Furthermore, the computer-readable storage medium can also be various media capable of storing program code, such as a USB flash drive, external hard drive, read-only memory (ROM), RAM, magnetic disk, or optical disk.

[0063] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0064] The modules described as separate components may or may not be physically separate. Similarly, the components shown as modules may or may not be physical modules; they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0065] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0066] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned readable storage medium includes various media capable of storing program code, such as USB flash drives, external hard drives, ROM, RAM, magnetic disks, or optical disks.

[0067] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0068] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0069] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An IPOP-LLC resonant converter based on SPH-SCC, wherein the LLC resonant converter has at least two phases, characterized in that, Each phase of the LLC resonant converter includes: a primary-side inverter bridge, a resonant inductor, a magnetizing inductor, a parallel switched capacitor unit, a half-wave series switched capacitor unit, a transformer, and a load; the primary-side inverter bridge has a first bridge arm and a second bridge arm, the midpoint of the first bridge arm is electrically connected to the parallel switched capacitor unit, the parallel switched capacitor unit is electrically connected to the half-wave series switched capacitor unit, and the half-wave series switched capacitor unit is electrically connected to the primary side of the transformer; the midpoint of the second bridge arm is electrically connected to the resonant inductor, the resonant inductor is electrically connected to the magnetizing inductor, the magnetizing inductor is connected in parallel with the primary side of the transformer, and the secondary side of the transformer is electrically connected to the load; the resonant inductor, the magnetizing inductor, the parallel switched capacitor unit, and the half-wave series switched capacitor unit form a resonant slot; The parallel switched capacitor unit is used to adjust the equivalent capacitance of the parallel switched capacitor unit by adjusting the duty cycle of the internal switch; the half-wave series switched capacitor unit is used to adjust the equivalent capacitance of the half-wave series switched capacitor unit by adjusting the duty cycle of the internal switch.

2. The IPOP-LLC resonant converter based on SPH-SCC as described in claim 1, characterized in that, The parallel switched capacitor unit includes a first resonant capacitor, a first auxiliary capacitor, and a first auxiliary switch; the half-wave series switched capacitor unit includes a second auxiliary capacitor and a second auxiliary switch, the first auxiliary capacitor and the first auxiliary switch are connected in series, the first resonant capacitor is connected in parallel with the series-connected first auxiliary capacitor and the first auxiliary switch; the second auxiliary capacitor and the second auxiliary switch are connected in parallel. Specifically, when adjusting the duty cycle of the first auxiliary switch, the duration of the first auxiliary capacitor being connected to the circuit can be controlled, thereby adjusting the equivalent capacitance of the parallel switched capacitor unit; when adjusting the duty cycle of the second auxiliary switch, the time interval during which the second auxiliary capacitor is excluded from the circuit can be controlled, thereby adjusting the equivalent capacitance of the half-wave series switched capacitor unit.

3. The IPOP-LLC resonant converter based on SPH-SCC as described in claim 2, characterized in that, The equivalent capacitance of the parallel switched capacitor unit C eq_p The expression is: in, d a1 To depend solely on the duty cycle of the first auxiliary switch d The equivalent duty cycle of a parallel switched capacitor unit of 1, C r It is a resonant capacitor. C a1 This is the first auxiliary capacitor; The equivalent capacitance of the half-wave series switched capacitor unit C eq_s The expression is: in, d a2 It depends solely on the duty cycle of the second auxiliary switch. d The equivalent duty cycle of a 2-wave series switched capacitor unit. C a2 This is the second auxiliary capacitor; The equivalent capacitance of SPH-SCC after the parallel switched capacitor unit and the half-wave series switched capacitor unit are connected in series is... C scc The expression for the unified model is: 。 4. The IPOP-LLC resonant converter based on SPH-SCC as described in claim 2, characterized in that, The equivalent load of the primary-side inverter bridge R eq The expression is: in, R L For load, n This refers to the turns ratio of the transformer. resonant frequency f r Equivalent capacitance of SPH-SCC C scc The relation is: The gain of the LLC resonant converter M scc The expression is: in, λ For resonant inductors L r With magnetizing inductor L m The ratio, f n For normalized frequency, f s The switching frequency of the primary-side inverter bridge. Q This is the quality factor.

5. A control method for an IPOP-LLC resonant converter based on SPH-SCC, wherein the LLC resonant converter has two phases, characterized in that, Each phase of the LLC resonant converter includes an SPH-SCC composed of parallel switched capacitor units and half-wave series switched capacitor units. The control method of the LLC resonant converter includes: After controlling the two-phase primary-side inverter bridge with the same switching frequency, the back end of the two-phase primary-side inverter is sampled to obtain the first sampling current and the second sampling current. The zero-crossing point of the first sampling current and the second sampling current is detected to determine the delay time of the two-phase SPH-SCC. Obtain the load output voltage and compare it with the reference voltage to obtain the switching cycle of the two-phase SPH-SCC; The two-phase output current is acquired and compared. The duty cycle of the first auxiliary switch is set to 0 based on the phase with the smaller current. Then, the initial duty cycle of the second auxiliary switch is determined by the PI controller. Iterative calculations are performed based on the minimum THD range of the equivalent capacitance of SPH-SCC and the total current to obtain the low THD duty cycle of the second auxiliary switch. The duty cycle of the second auxiliary switch is set to 0.5 based on the phase with the larger current. Then, the duty cycle of the first auxiliary switch is determined by the PI controller to obtain the low THD duty cycle of the two-phase auxiliary switches. The PWM signal of the SPH-SCC is generated based on the delay time of the two-phase SPH-SCC, the switching cycle of the two-phase SPH-SCC, and the duty cycle of the auxiliary switches of the two phases to control the operation of the two-phase SPH-SCC.

6. The control method for the IPOP-LLC resonant converter based on SPH-SCC as described in claim 5, characterized in that, The iterative calculation based on the minimum THD range of the equivalent capacitance and total current of SPH-SCC to obtain the duty cycle of the second auxiliary switch with low THD specifically includes: Iterative calculations are performed based on the minimum THD range of the equivalent capacitance and total current of SPH-SCC to obtain the maximum or minimum duty cycle set of the second auxiliary switch, wherein each element in the duty cycle set corresponds to the minimum total harmonic distortion, while keeping the equivalent capacitance of SPH-SCC constant. Select one duty cycle element from the set of duty cycles of the second auxiliary switch as the duty cycle of the low THD of the second auxiliary switch.

7. The control method for the IPOP-LLC resonant converter based on SPH-SCC as described in claim 5, characterized in that, The minimum THD range of the total current is the duty cycle range of the second auxiliary switch corresponding to the interval where the THD is less than 50% of its maximum value, which are 0~0.158 and 0.375~0.5 respectively.

8. The control method for the IPOP-LLC resonant converter based on SPH-SCC as described in claim 5, characterized in that, The control method further includes: Based on the average output current of the SPH-SCC LLC resonant converter I o_avg Define load sharing error σ load The expression is: The key waveforms of the SPH-SCC LLC resonant converter under full load and half load were detected based on the load current sharing error data.

9. A control system for an IPOP-LLC resonant converter based on SPH-SCC, characterized in that, It includes an LLC resonant converter, a first PI controller, a second PI controller, a zero-crossing detector, and a data processor; the LLC resonant converter is electrically connected to the first PI controller, the zero-crossing detector, and the data processor respectively, and the second PI controller is electrically connected to the data processor; The first PI controller is used to determine the switching cycle of the two-phase SPH-SCC based on the comparison result between the load output voltage and the reference voltage. The second PI controller is used to determine the duty cycle of the second auxiliary switch according to the set duty cycle of the first auxiliary switch of the first phase, and to determine the duty cycle of the second auxiliary switch according to the set duty cycle of the first auxiliary switch of the second phase; The zero-crossing detector is used to detect the zero-crossing of the first sampling current and the second sampling current to determine the delay time of the two-phase SPH-SCC. The data processor is used to compare the output currents of the two phases, set the duty cycle of the first auxiliary switch to 0 according to the phase with the smaller current, then determine the initial duty cycle of the second auxiliary switch according to the PI controller, and iterate according to the minimum THD range of the equivalent capacitance of SPH-SCC and the total current to obtain the duty cycle of the second auxiliary switch with low THD. The duty cycle of the first auxiliary switch is set to 0.5 based on the phase with the larger current. Then, the duty cycle of the second auxiliary switch is determined according to the PI controller, thus obtaining the duty cycles of the two auxiliary switches. The data processor is connected to a memory that stores a computer program that can run on the data processor. When the data processor executes the computer program, it performs the step of determining the duty cycle of the two-phase auxiliary switch with low THD as described in any one of claims 5-8.

10. A readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 5-8.

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