Wide-load constant current constant voltage dual-T resonant DC-DC converter

Abstract

This invention relates to the field of DC-DC resonant converter technology and discloses a wide-load constant-current, constant-voltage dual-T resonant DC-DC converter, comprising: a full-bridge inverter module for converting the input DC voltage into a high-frequency AC square wave signal for use by the dual-T resonant cavity module; a dual-T resonant cavity module for adjusting the parameters of the resonant cavity, thereby supporting switching between constant-current and constant-voltage modes; and an uncontrolled full-bridge rectifier module for rectifying the AC voltage output from the resonant cavity into a DC voltage. This invention employs a dual-T resonant converter topology and, by introducing fixed-frequency control and switched-capacitor regulation technology, achieves constant-current and constant-voltage output over a wide load range. This invention avoids energy loss and electromagnetic interference caused by frequency offset. Furthermore, by precisely designing the resonant cavity parameters and dynamically adjusting the mode switching process, it ensures a smooth transition of load voltage and current, achieving efficient and reliable DC-DC conversion under wide load conditions.

Description

Technical Field

[0001] This invention relates to the field of DC-DC resonant converter technology, specifically a wide-load constant current constant voltage dual-T resonant DC converter. Background Technology

[0002] In the field of DC-DC converter technology, with the rapid development of third-generation semiconductor technology, high-frequency resonant converters have gradually become indispensable key equipment in aerospace, communications, transportation, and other fields. In particular, the charging requirements of devices such as lithium-ion batteries necessitate simultaneous support for constant current and constant voltage mode switching, while maintaining high efficiency under wide load conditions. To meet this requirement, LLC resonant converters have become a commonly used implementation solution due to their simple structure, wide soft-switching range, and electrical isolation. However, as the complexity of practical application scenarios increases, the limitations of existing LLC resonant converters are gradually becoming apparent.

[0003] Traditional LLC resonant converters exhibit high conversion efficiency near the resonant point, but this characteristic presents obvious limitations. Due to the narrow resonant gain range, the switching frequency must be adjusted to adapt to different output requirements. While this method can broaden the gain range to some extent, it also introduces a series of problems. Frequency adjustment causes the operating point to deviate from the resonant point, directly leading to the loss of soft-switching conditions. This means a significant increase in losses during the turn-on and turn-off processes of the power switching devices, and an increase in the circulating current in the resonant cavity, resulting in more severe energy loss. In other words, existing technologies inevitably sacrifice system efficiency while improving the gain range.

[0004] More complexly, the side effects of frequency regulation extend beyond reduced efficiency to include system reliability and electromagnetic compatibility issues. Dynamic frequency changes can trigger severe electromagnetic interference (EMI), interfering with peripheral equipment and adversely affecting the system's own drive control system. Furthermore, the design complexity of magnetic components such as transformers increases significantly to accommodate frequency regulation. This complex design not only increases R&D costs but also poses challenges to the system's mass production and long-term stable operation.

[0005] Especially in wide-load applications, such as lithium battery charging, LLC resonant converters need to simultaneously meet the switching requirements of constant current and constant voltage modes. In such scenarios, a key challenge for traditional technologies is the stability of mode switching. Due to the dynamic adjustment of the topology, current or voltage may fluctuate significantly during switching, directly affecting the safety of the load device. Furthermore, the significant increase in circulating current energy within the resonant cavity not only reduces system efficiency but also complicates the thermal design of components.

[0006] In summary, while existing LLC resonant converter technology has certain advantages, it has significant shortcomings in terms of efficiency, stability, and adaptability. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a wide-load constant current and constant voltage dual-T resonant DC-DC converter, which solves the problems of limited gain range, decreased efficiency, and poor stability of constant current and constant voltage mode switching in existing LLC resonant converters under wide load conditions.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a wide-load constant current constant voltage dual-T resonant DC-DC converter, comprising:

[0009] The full-bridge inverter module is used to convert the input DC voltage into a high-frequency AC square wave signal for use by the dual-T resonant cavity module;

[0010] The dual-T resonant cavity module is used to adjust the parameters of the resonant cavity, thereby supporting the switching between constant current mode and constant voltage mode;

[0011] An uncontrollable full-bridge rectifier module is used to rectify the AC voltage output from the resonant cavity into DC voltage, and then output the rectified DC voltage to the load.

[0012] The control module is used to monitor the voltage and current of the output load in real time, and control the on / off state of the AC switch and the equivalent capacitance value of the switched capacitor according to the monitoring results, thereby realizing the switching between constant current mode and constant voltage mode.

[0013] Preferably, the full-bridge inverter module includes:

[0014] The power switching unit includes four power switching transistors, which are used to convert the input DC voltage into a high-frequency AC square wave signal by alternating conduction.

[0015] The control unit is used to control the duty cycle of the switching transistor to 50%, thereby outputting a symmetrical AC voltage signal;

[0016] The output unit is used to provide alternating positive and negative AC voltage signals to the dual-T resonant cavity module.

[0017] Preferably, the dual-T resonant cavity module includes:

[0018] The first T-type resonant unit includes the first set of symmetrically designed inductors L 11 and L 12 and capacitor C 11 and C 12 , used to form the first resonant circuit;

[0019] The second T-type resonant unit includes a second set of symmetrically designed inductors L 21and L 22 and capacitor C 21 and C 22 , used to form a second resonant circuit;

[0020] An AC switching unit, connected in series in the branch of the second T-type resonant unit, is used to cut off or connect the second resonant unit and adjust the mode of the resonant cavity to support constant current or constant voltage operation.

[0021] The switched capacitor unit, consisting of an AC switch and a parallel linear resistor, is used to adjust the equivalent capacitance of the resonant cavity.

[0022] Preferably, the relationship between the equivalent capacitance value of the switched capacitor unit and the conduction angle α of the control switch is as follows:

[0023]

[0024] Among them, C SC α is the equivalent capacitance of the switched capacitor, C is the linear capacitance of the switched capacitor, and α is the conduction angle of the AC switch that lags behind the zero-crossing point of the input current.

[0025] Preferably, the uncontrollable full-bridge rectifier module includes:

[0026] The input unit is used to receive the high-frequency AC voltage signal output from the dual-T resonant cavity;

[0027] The rectifier unit, composed of a full-bridge diode, is used to rectify high-frequency AC signals into DC signals;

[0028] The output unit is used to provide rectified DC voltage and current signals to the load.

[0029] Preferably, the control module includes:

[0030] The voltage detection unit is used to detect the output voltage of the load in real time.

[0031] The current detection unit is used to detect the output current of the load in real time;

[0032] The mode determination unit is used to determine whether the operating conditions of constant current mode and constant voltage mode are met based on the real-time values ​​of the load output voltage and current.

[0033] The control signal output unit is used to send control signals to the dual-T resonant cavity module based on the result of the mode judgment unit, so as to adjust the working state of the AC switch and the switched capacitor.

[0034] The feedback regulation unit is used to smoothly adjust the output voltage or current during mode switching to ensure stable system operation.

[0035] Preferably, the switching conditions between constant current mode and constant voltage mode controlled by the mode determination unit include:

[0036] When the load voltage is less than the set threshold, the constant current mode is maintained, the AC switch is controlled to disconnect the branch of the second T-type resonant unit, and the switched capacitor is adjusted to a larger equivalent capacitance value.

[0037] When the load voltage reaches the set threshold, it switches to constant voltage mode, controls the AC switch to connect the branch of the second T-type resonant unit, and adjusts the switched capacitor to a smaller equivalent capacitance value.

[0038] A control method for a wide-load constant-current constant-voltage dual-T resonant DC-DC converter, used to control the aforementioned wide-load constant-current constant-voltage dual-T resonant DC-DC converter, includes the following steps:

[0039] The full-bridge inverter module will input DC voltage V dc Converted into a high-frequency AC square wave signal;

[0040] The dual-T resonant cavity module achieves constant current or constant voltage output by adjusting the conduction state of the AC switch and the equivalent capacitance value of the switched capacitor;

[0041] In constant current mode, the control AC switch is turned off, the resonant cavity switches to a single T-type topology, and outputs a constant current;

[0042] In constant voltage mode, the control AC switch is turned on, the resonant cavity switches to a double-T topology, and the output voltage is constant.

[0043] An uncontrollable full-bridge rectifier module rectifies the AC output of the resonant cavity into a DC signal;

[0044] The control module monitors the load voltage and current values ​​in real time. When the load voltage reaches the set threshold, it switches from constant current mode to constant voltage mode.

[0045] Preferably, the output current of the resonant cavity in the constant current mode is limited by the following formula:

[0046]

[0047] Among them, I b T is the average output current of the load. s The switching period is (i29t), the input current of the rectifier stage is (i29t), and I is (i29t). 2rms The effective value of the input current before rectification is determined by the fundamental equivalent impedance of the double-T resonant cavity.

[0048] This invention provides a wide-load constant-current constant-voltage dual-T resonant DC-DC converter. It has the following advantages:

[0049] 1. This invention adopts a dual-T resonant converter topology, which cascades two T-type resonant units and combines them with an AC switch topology design to achieve constant current and constant voltage output with a wide load range under fixed frequency conditions. Compared with the existing LLC resonant converters that use frequency modulation control, which leads to soft switching loss and large circulating current energy loss, the fixed frequency operating mode of this invention avoids frequency offset problems and improves the energy transmission efficiency and reliability of the system.

[0050] 2. This invention utilizes the combination of adjustable switched capacitor SCC and resonant cavity parameters to dynamically adjust the equivalent capacitance of the resonant cavity by controlling the conduction angle. Under wide load conditions, there is no need to add complex magnetic component design and testing procedures. This solves the shortcomings of existing LLC topologies, such as high requirements for transformer parameter design and large noise. In particular, the system can smoothly transition during the switching between constant current and constant voltage modes, ensuring the consistency of output characteristics.

[0051] 3. The dual-T resonant converter structure proposed in this invention achieves this through precise design of the resonant cavity parameter L. 13 and L 23 This invention enables the system to operate at the resonant point, achieving low switching losses and low electromagnetic interference. Compared to traditional solutions, it significantly reduces the circulating current energy consumption caused by resonant offset, addressing the shortcomings of excessive circulating current and decreased system efficiency in traditional solutions. Furthermore, the invention provides a rapid response and maintains stable output under varying load conditions, significantly improving the system's average energy efficiency and adaptability. Attached Figure Description

[0052] Figure 1 This is a framework diagram of the converter module of the present invention;

[0053] Figure 2 This is a schematic diagram of the topology of the wide-load constant current-constant voltage dual-T resonant converter of the present invention;

[0054] Figure 3 This is a schematic diagram of the topology of the AC switch of the present invention;

[0055] Figure 4 This is a schematic diagram of the topology of the switched capacitor SCC of the present invention;

[0056] Figure 5 This is the fundamental equivalent circuit diagram obtained by the fundamental wave analysis method in this invention;

[0057] Figure 6 This is a schematic diagram of the present invention in constant current mode, constant voltage mode, and mode switching scheme;

[0058] Figure 7 This is a transient waveform diagram of the oscilloscope output in constant current mode according to the present invention;

[0059] Figure 8 This is a transient waveform diagram of the oscilloscope output in constant voltage mode according to the present invention;

[0060] Figure 9 This is a steady-state waveform diagram of the oscilloscope output in constant current mode according to the present invention;

[0061] Figure 10 This is a transient output waveform of the oscilloscope in constant voltage mode according to the present invention;

[0062] Figure 11 This is a frame diagram of the full-bridge inverter module of the present invention;

[0063] Figure 12 This is a frame diagram of the dual-T resonant cavity module of the present invention;

[0064] Figure 13 This is a framework diagram of the uncontrollable full-bridge rectifier module of the present invention;

[0065] Figure 14 This is a framework diagram of the control module of the present invention;

[0066] Figure 15 This is a flowchart of the control method of the present invention. Detailed Implementation

[0067] The technical solutions in 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] Please see the appendix Figure 1 -Appendix Figure 10 This invention provides a wide-load constant current constant voltage dual-T resonant DC-DC converter, comprising:

[0069] The full-bridge inverter module is used to convert the input DC voltage into a high-frequency AC square wave signal for use by the dual-T resonant cavity module;

[0070] Please see the appendix Figure 11 The full-bridge inverter module includes:

[0071] The power switching unit includes four power switching transistors, which are used to convert the input DC voltage into a high-frequency AC square wave signal by alternating conduction.

[0072] The control unit is used to control the duty cycle of the switching transistor to 50%, thereby outputting a symmetrical AC voltage signal;

[0073] The output unit is used to provide alternating positive and negative AC voltage signals to the dual-T resonant cavity module.

[0074] Specifically, in this embodiment, the full-bridge inverter module mainly includes the following units:

[0075] Power switching unit: includes four power switching transistors (Q1, Q2, Q3, Q4), and adopts a full-bridge inverter topology.

[0076] The power switching transistors are arranged in a symmetrical structure, with Q1 and Q4 in one group and Q2 and Q3 in another group.

[0077] The function of this unit is to achieve DC voltage V by alternately turning on two sets of switching transistors. dc Converted into a high-frequency AC square wave voltage with alternating positive and negative values ​​v ab (t), for use in dual-T resonant cavity modules.

[0078] Control unit: Generates control signals to drive the power switching transistors, ensuring that the two sets of switches Q1, Q4 and Q2, Q3 are turned on alternately.

[0079] The duty cycle of the control signal is 50%, thus the output AC square wave signal has symmetry.

[0080] The frequency f of the control signal s It is set to a fixed value to match the resonant frequency of the double-T resonant cavity, ensuring stable system operation.

[0081] Output unit: Outputs the alternating positive and negative high-frequency AC signals generated by the power switching unit to the dual-T resonant cavity module.

[0082] The amplitude of the output signal is ±V dc It has low harmonic distortion, and its fundamental component is used by the resonant cavity as its operating voltage source.

[0083] In this embodiment, the full-bridge inverter module converts the input DC voltage into an amplitude of ±V using alternating pairs of power switches. dc An AC square wave signal. Its output voltage v ab The expression for (t) can be expanded using a Fourier series as follows:

[0084]

[0085] Among them, V dc The input DC voltage; ω s =2πf s f s is the switching frequency; k is the harmonic index (odd harmonic).

[0086] Fourier series expansion reveals that the output voltage consists of a DC component and multiple harmonic components, with the fundamental component having the most significant amplitude. (Fundamental component v) ab1The expression for (t) is:

[0087]

[0088] The effective value v of the fundamental component ab Expressed as:

[0089]

[0090] The above formula shows that the effective value of the fundamental component in the AC signal output by the full-bridge inverter is related to the input DC voltage V. dc Proportional to the switching frequency f s Furthermore, odd harmonic components of the output signal (such as the 3rd and 5th harmonics) are effectively filtered out in the subsequent double-T resonant cavity, thereby ensuring the stability and efficiency of the system output signal.

[0091] In this embodiment, the operation control strategy of the full-bridge inverter module is as follows:

[0092] Alternating conduction of power switching transistors:

[0093] Q1 and Q4 are switched on alternately, and Q2 and Q3 are switched on alternately. The duty cycle of each group of switches is T. s =1 / f s .

[0094] During one switching cycle, when Q1 and Q4 are on, the output voltage is +V. dc When Q2 and Q3 are turned on, the output voltage is -V. dc .

[0095] Design of control signals:

[0096] The duty cycle of the control signal is strictly set to 50% to ensure the positive and negative symmetry of the output square wave signal.

[0097] The conduction signals of the two sets of power switches are 180° out of phase to avoid shoot-through losses in the power transistors.

[0098] Frequency matching:

[0099] Switching frequency f s The resonant frequency f of the double-T resonant cavity r This ensures consistency, thereby guaranteeing that the system operates at the resonant point and reducing circulating current loss and harmonic interference.

[0100] In this embodiment, the output voltage v ab The harmonic characteristics of (t) are mainly composed of odd harmonics, including the following:

[0101] Advantages of the fundamental component: The fundamental component of the output voltage v ab1(t) is utilized by the dual-T resonant cavity module, and its frequency and effective value directly affect the system's resonance characteristics and output characteristics.

[0102] The impact of harmonic components: High-order harmonics (such as the 3rd and 5th harmonics) may interfere with subsequent circuits, but due to the resonant characteristics of the double-T resonant cavity, high-order harmonics at non-resonant frequencies will be significantly attenuated, thereby ensuring the purity of the system output signal.

[0103] Key design considerations for full-bridge inverter modules:

[0104] Selection of power switching devices: In this embodiment, a high-frequency, low-loss MOSFET is used as the power switching transistor to reduce switching losses and conduction losses and improve the system's conversion efficiency.

[0105] Control signal generation: The control unit is designed to generate a PWM signal with a fixed frequency and a 50% duty cycle to ensure that the output signal is symmetrical and stable, and to avoid output distortion caused by control signal distortion.

[0106] Module frequency matching: The switching frequency of the full-bridge inverter is precisely matched with the resonant frequency of the resonant cavity, which can reduce harmonic interference and improve the power conversion efficiency of the system.

[0107] The dual-T resonant cavity module is used to adjust the parameters of the resonant cavity, thereby supporting the switching between constant current mode and constant voltage mode;

[0108] Please see the appendix Figure 3 Appendix Figure 4 and attached Figure 12 The dual-T resonant cavity module includes:

[0109] The first T-type resonant unit includes the first set of symmetrically designed inductors L 11 and L 12 and capacitor C 11 and C 12 , used to form the first resonant circuit;

[0110] The second T-type resonant unit includes a second set of symmetrically designed inductors L 21 and L 22 and capacitor C 21 and C 22 , used to form a second resonant circuit;

[0111] An AC switching unit, connected in series in the branch of the second T-type resonant unit, is used to cut off or connect the second resonant unit and adjust the mode of the resonant cavity to support constant current or constant voltage operation.

[0112] The switched capacitor unit, consisting of an AC switch and a parallel linear resistor, is used to adjust the equivalent capacitance of the resonant cavity.

[0113] The relationship between the equivalent capacitance of the switched capacitor unit and the conduction angle α of the control switch is as follows:

[0114]

[0115] Among them, C SC α is the equivalent capacitance of the switched capacitor, C is the linear capacitance of the switched capacitor, and α is the conduction angle of the AC switch that lags behind the zero-crossing point of the input current.

[0116] Specifically, in this embodiment, the dual-T resonant cavity module includes the following units:

[0117] First T-type resonant unit: includes the first set of symmetrically designed inductors L 11 =L 12 and capacitors.

[0118] Function:

[0119] The first resonant circuit that constitutes the resonant cavity is mainly used for resonant operation in constant current mode;

[0120] The output current is constant, ensuring the stability of the resonant cavity in constant current mode.

[0121] Second T-type resonant unit: includes a second set of symmetrically designed inductors L 21 =L 22 .

[0122] Function:

[0123] The second resonant circuit, which constitutes the resonant cavity, works in conjunction with the first resonant circuit in constant voltage mode.

[0124] Adjust the output voltage to achieve the constant voltage working mode of the resonant cavity.

[0125] AC switching unit: Connected in series in the branch of the second T-type resonant unit, it consists of two MOSFETs connected in reverse series in a common-drain manner.

[0126] Function:

[0127] Used to disconnect or connect the branch of the second T-type resonant unit;

[0128] In constant current mode, the AC switch is turned off, causing the second resonant unit to disconnect from operation; in constant voltage mode, the AC switch is turned on, and the entire double-T resonant cavity participates in operation.

[0129] Switched capacitor unit: consists of an AC switch and a parallel linear resistor.

[0130] Function:

[0131] The equivalent capacitance of the resonant cavity is changed by adjusting the conduction angle of the AC switch to lag behind the phase angle of the zero-crossing point of the input current.

[0132] It is used to achieve dynamic adjustment of resonant cavity parameters to adapt to the working requirements of constant current mode and constant voltage mode.

[0133] In this embodiment, the equivalent capacitance value C of the switched capacitor unit is... SC The relationship with the conduction angle α of the AC switch is as follows:

[0134]

[0135] Among them, C SC α is the equivalent capacitance of the switched capacitor unit; C is the linear capacitance of the switched capacitor; α is the conduction angle of the AC switch lagging behind the zero-crossing point of the input current.

[0136] The dual-T resonant cavity module achieves dynamic parameter matching of the resonant cavity by adjusting the on / off state of the AC switch and the equivalent capacitance value of the switched capacitor unit, and supports switching between constant current mode and constant voltage mode.

[0137] 1. Constant Current Mode:

[0138] Work status:

[0139] When the AC switch is turned off, the second T-type resonant unit is detached from the resonant cavity, and only the first T-type resonant unit participates in the operation;

[0140] The switched capacitor unit is adjusted to the corresponding equivalent capacitance value C according to the constant current mode requirements. SC .

[0141] Technical Implementation:

[0142] In constant current mode, the output current I of the first T-type resonant unit b Expressed as:

[0143]

[0144] Where i2(t) is the input current of the rectifier circuit; I 2rms The effective value of the input current in the rectifier stage; It is the effective value of the current multiplied by a coefficient.

[0145]

[0146] Where i2(t) is the instantaneous value of the input current (AC signal) before rectification of the resonant cavity; I 2rms This is the effective value of the input current (related to the load power); ω represents the peak amplitude of the input current (the maximum value of the AC signal); s =2πf sV is the resonant angular frequency of the resonant cavity; φ is the phase difference between the current and the voltage, indicating that the current lags behind the input voltage V. cd The phase angle.

[0147] The impedance Z of the first T-type resonant unit 13 The output current, impedance, and inductance L of the resonant cavity were determined. 13 The relationship is:

[0148]

[0149] Among them, V dc ω is the input voltage of the resonant cavity; L is the angular frequency corresponding to the switching frequency; 13 I is the main resonant inductance of the resonant cavity; b This represents the average output current of the load.

[0150] 2. Constant pressure mode:

[0151] Work status:

[0152] When the AC switch is turned on, the second T-type resonant unit works in conjunction with the first T-type resonant unit.

[0153] The dual-T resonant cavity operates as a whole, outputting a constant voltage V. b .

[0154] Technical Implementation:

[0155] The input voltage V of the resonant cavity i With output voltage V b The relationship is:

[0156]

[0157] Among them, L 23 The inductance is for the second T-type resonant unit.

[0158] The parameter design of the second T-type resonant unit satisfies:

[0159]

[0160] Among them, L 23 The second-stage inductor of the resonant cavity; V b I is the load output voltage; b This represents the average output current of the load.

[0161] Parameter matching ensures output voltage V in constant voltage mode b Constant.

[0162] 3. Dynamic adjustment of switched capacitors:

[0163] Equivalent capacitance value:

[0164] In constant current mode, by adjusting the conduction angle α, the switched capacitor unit is adjusted to the required equivalent capacitance value C. SC This ensures that the first T-type resonant unit operates at the resonant point.

[0165] In constant voltage mode, the equivalent capacitance of the switched capacitor unit is matched with the overall output parameters of the dual-T resonant cavity to support the stable operation of the resonant cavity.

[0166] Dynamic switching principle:

[0167] When the output voltage reaches the set constant voltage value V b At this time, the controller switches the AC switch based on the sensor detection results and adjusts the equivalent value of the switching capacitor to make the resonant cavity enter the constant voltage working mode;

[0168] After the constant voltage mode ends, the AC switch is turned off, and the switched capacitor is adjusted back to the value required for the constant current mode.

[0169] Technical features of the dual-T resonant cavity module:

[0170] Wide load range adaptability: The coordinated operation of the first and second T-type resonant units enables constant current and constant voltage output over a wide load range.

[0171] Flexibility in mode switching: Through dynamic adjustment of AC switches and switched capacitor units, the resonant cavity parameters can be quickly switched between constant current and constant voltage modes.

[0172] Optimized parameter design: The inductance and capacitance parameters of the resonant cavity are designed according to the load requirements to ensure that the resonant operating point always meets the constant current and constant voltage characteristics.

[0173] High-efficiency operation: The module operates at the resonant point, reducing switching losses and circulating current losses, and improving system conversion efficiency.

[0174] An uncontrollable full-bridge rectifier module is used to rectify the AC voltage output from the resonant cavity into DC voltage, and then output the rectified DC voltage to the load.

[0175] Please see the appendix Figure 13 The uncontrollable full-bridge rectifier module includes:

[0176] The input unit is used to receive the high-frequency AC voltage signal output from the dual-T resonant cavity;

[0177] The rectifier unit, composed of a full-bridge diode, is used to rectify high-frequency AC signals into DC signals;

[0178] The output unit is used to provide rectified DC voltage and current signals to the load.

[0179] Specifically, in this embodiment, the uncontrollable full-bridge rectifier module consists of the following units:

[0180] Input unit: Receives the high-frequency AC voltage signal v output from the dual-T resonant cavity. cd (t).

[0181] The input unit is directly connected to the output of the dual-T resonant cavity to ensure that the high-frequency AC voltage output by the resonant cavity can be completely transmitted to the rectifier unit.

[0182] Rectifier unit: Composed of a full-bridge diode, used to rectify the input high-frequency AC signal into a DC signal.

[0183] The rectifier unit is the core of the module. It uses an uncontrolled full-bridge rectifier circuit composed of four diodes to rectify the positive and negative half-cycles of the high-frequency sinusoidal AC signal into unidirectional pulsating DC signals.

[0184] Output unit: Converts the rectified DC voltage V o and current I o Provided to the load.

[0185] The output unit is connected to the load to ensure that the DC voltage and current signals meet the constant current or constant voltage requirements of the load.

[0186] The uncontrolled full-bridge rectifier module completes the conversion of high-frequency AC to DC signals through the following working principle:

[0187] Input signal characteristics:

[0188] The high-frequency AC voltage signal v output by the dual-T resonant cavity cd (t) is:

[0189]

[0190] Among them, V b ω is the effective value of the output voltage of the resonant cavity. s =2πf s f s φ is the switching frequency; φ is the phase angle.

[0191] Full-bridge rectification process: The diode full-bridge circuit operates using the positive and negative half-cycles of the high-frequency signal: During the positive half-cycle, two forward-conducting diodes transmit the positive half-cycle of the AC signal as a unidirectional current; during the negative half-cycle, another pair of forward-conducting diodes perform the same function.

[0192] The average voltage V of the output pulsating DC signal o It is a function of the effective value of the fundamental component of the input signal.

[0193] Output DC voltage and current characteristics:

[0194] The output DC voltage V of the rectifier module o for:

[0195]

[0196] The rectified voltage and current satisfy the constant current I of the load. b Or constant voltage V b need.

[0197] Key design considerations for uncontrollable full-bridge rectifier modules:

[0198] Input and output interface design: The input interface must be compatible with the output of the dual-T resonant cavity and be able to receive high-frequency AC voltage signals. The output interface connects to the load to ensure stable transmission of DC signals.

[0199] Diode selection for the rectifier unit: The diode must have high-frequency operating capability to handle the high-frequency AC signal output from the resonant cavity; the reverse withstand voltage of the diode must be higher than the peak voltage of the resonant cavity output signal to ensure operational safety.

[0200] Signal conversion efficiency optimization: The design of the full-bridge rectifier circuit should minimize the conduction loss and reverse recovery loss of the diodes to improve the rectification efficiency; the temperature rise caused by high-frequency operation should be controlled by a well-designed heat dissipation system.

[0201] Technical characteristics of uncontrollable full-bridge rectifier modules:

[0202] Matching with the dual-T resonant cavity: The rectifier module directly receives the high-frequency sinusoidal AC signal output from the dual-T resonant cavity, and its input-output characteristics are closely matched with the resonant cavity.

[0203] High-efficiency rectification: The module adopts an uncontrolled diode full-bridge circuit, which achieves high-efficiency AC to DC conversion through rectification of the positive and negative half cycles.

[0204] Output stability: The polarity of the output signal is fixed after rectification, which can provide stable DC voltage and current to the load and meet the constant current or constant voltage output requirements of a wide load range.

[0205] The control module is used to monitor the voltage and current of the output load in real time, and control the on / off state of the AC switch and the equivalent capacitance value of the switched capacitor according to the monitoring results, thereby realizing the switching between constant current mode and constant voltage mode.

[0206] Please see the appendix Figure 6 and attached Figure 14 The control module includes:

[0207] The voltage detection unit is used to detect the output voltage of the load in real time.

[0208] The current detection unit is used to detect the output current of the load in real time;

[0209] The mode determination unit is used to determine whether the operating conditions of constant current mode and constant voltage mode are met based on the real-time values ​​of the load output voltage and current.

[0210] The control signal output unit is used to send control signals to the dual-T resonant cavity module based on the result of the mode judgment unit, so as to adjust the working state of the AC switch and the switched capacitor.

[0211] The feedback regulation unit is used to smoothly adjust the output voltage or current during mode switching to ensure stable system operation.

[0212] The switching conditions between constant current mode and constant voltage mode controlled by the mode determination unit include:

[0213] When the load voltage is less than the set threshold, the constant current mode is maintained, the AC switch is controlled to disconnect the branch of the second T-type resonant unit, and the switched capacitor is adjusted to a larger equivalent capacitance value.

[0214] When the load voltage reaches the set threshold, it switches to constant voltage mode, controls the AC switch to connect the branch of the second T-type resonant unit, and adjusts the switched capacitor to a smaller equivalent capacitance value.

[0215] Specifically, in this embodiment, the control module includes the following units:

[0216] Voltage detection unit: Real-time detection of the load's output voltage V o .

[0217] The output voltage signal at the load end is collected and provided to the mode determination unit to determine the working mode.

[0218] Current detection unit: Real-time detection of the load's output current I o .

[0219] The output current signal at the load end is collected and used as the input parameter of the mode judgment unit for system mode switching determination and feedback adjustment.

[0220] Mode determination unit: Based on the load output voltage V o and current I o The real-time value is used to determine whether the system currently meets the operating conditions of constant current or constant voltage mode, and to decide on the mode switch.

[0221] Switching logic:

[0222] When the load voltage V o Less than the set threshold V th During this time, maintain constant current mode;

[0223] When the load voltage V o Reaching the set threshold V th When the time comes, switch to constant pressure mode.

[0224] Control signal output unit: Based on the result of the mode judgment unit, it sends a control signal to the dual-T resonant cavity module to dynamically adjust the on / off state of the AC switch and the equivalent capacitance value of the switched capacitor.

[0225] The control AC switch connects or disconnects the second T-type resonant unit branch and adjusts the operating state of the switched capacitor unit to meet the operating requirements of constant current or constant voltage mode.

[0226] Feedback regulation unit: During mode switching, it smoothly adjusts the output voltage or current to avoid sudden changes that could cause system instability.

[0227] The input and output states of the dual-T resonant cavity are dynamically adjusted by a closed-loop control algorithm to ensure the stability of the system during switching.

[0228] The control module acquires the output status of the load in real time through voltage and current detection units, and determines the current operating mode and switching timing based on the logic of the mode judgment unit. The following is a detailed explanation of the control module's working principle:

[0229] Constant current mode:

[0230] Judgment condition: When the load voltage V o <V th At that time, the system is in constant current mode.

[0231] Control signal output:

[0232] The control AC switch is turned off, and the second T-type resonant unit is removed from the resonant cavity;

[0233] The control switch capacitor unit is adjusted to a larger equivalent capacitance value C. SC To support the resonant conditions of the constant current mode.

[0234] Constant pressure mode:

[0235] Judgment condition: When the load voltage V o ≥V th At that time, the system switches to constant pressure mode.

[0236] Control signal output:

[0237] When the control switch is turned on, the second T-type resonant unit participates in the operation of the resonant cavity;

[0238] The control switch capacitor unit is adjusted to a smaller equivalent capacitance value C. SC This satisfies the resonance condition of the constant voltage mode.

[0239] Feedback adjustment:

[0240] Constant current to constant voltage mode switching: when the load voltage reaches the threshold V thAt that time, the output current I is dynamically and smoothly adjusted through the feedback adjustment unit. o and voltage V o This ensures that there are no sudden changes during the switching process.

[0241] Constant voltage to constant current mode switching: when the load voltage is below the threshold V th At this time, the system gradually reduces the participation of the second resonant unit and increases the equivalent value of the switched capacitor, smoothly returning to the constant current working mode.

[0242] Mode switching conditions:

[0243] Constant current mode holding conditions:

[0244] V o <V th

[0245] The control AC switch is turned off, and the switched capacitor unit is adjusted to a larger equivalent capacitance value.

[0246] Constant voltage mode switching conditions:

[0247] V o ≥V th

[0248] When the AC switch is turned on, the switched capacitor unit is adjusted to a smaller equivalent capacitance value.

[0249] Logical relationship:

[0250] When the load voltage V o Less than the set threshold V th At this time, the control module ensures that the system operates in constant current mode and outputs a constant current I. b .

[0251] When the load voltage V o Reaching the set threshold V th At this time, the control module switches the system to constant voltage mode and outputs a constant voltage V. b .

[0252] Key design considerations for the control module:

[0253] Real-time monitoring: Voltage and current detection units need to have high accuracy and fast response capabilities to acquire the load output status in real time.

[0254] Dynamic control: The mode judgment unit needs to accurately determine the working mode based on the detected real-time data and through threshold comparison.

[0255] The control signal output unit needs to enable rapid dynamic adjustment of the AC switch and the switched capacitor.

[0256] Smooth switching: The feedback control unit eliminates abrupt changes during mode switching through a closed-loop control algorithm, ensuring the stability and continuity of the system.

[0257] System stability: During mode switching, voltage or current overshoot or oscillation must be avoided to ensure reliable operation of the load.

[0258] Technical features of the control module:

[0259] Real-time monitoring and rapid response: The control module monitors the output voltage and current in real time and responds quickly to load changes to ensure stable operation of the system in different modes.

[0260] Automated mode switching: Based on the threshold judgment of load voltage, the control module automatically switches between constant current and constant voltage modes without external intervention.

[0261] Dynamic adjustment and stability: Through the feedback adjustment unit, the output changes during the control mode switching process are smoothed to avoid system instability caused by output fluctuations.

[0262] The control method of the wide-load constant current constant voltage double-T resonant DC converter described below can be referred to in correspondence with the wide-load constant current constant voltage double-T resonant DC converter described above.

[0263] Please see the appendix Figure 5 and attached Figure 15 A control method for a wide-load constant-current constant-voltage dual-T resonant DC-DC converter, comprising the following steps:

[0264] The full-bridge inverter module will input DC voltage V dc Converted into a high-frequency AC square wave signal;

[0265] The dual-T resonant cavity module achieves constant current or constant voltage output by adjusting the conduction state of the AC switch and the equivalent capacitance value of the switched capacitor;

[0266] In constant current mode, the control AC switch is turned off, the resonant cavity switches to a single T-type topology, and outputs a constant current;

[0267] In constant voltage mode, the control AC switch is turned on, the resonant cavity switches to a double-T topology, and the output voltage is constant.

[0268] An uncontrollable full-bridge rectifier module rectifies the AC output of the resonant cavity into a DC signal;

[0269] The control module monitors the load voltage and current values ​​in real time. When the load voltage reaches the set threshold, it switches from constant current mode to constant voltage mode.

[0270] The output current of the resonant cavity in constant current mode is limited by the following formula:

[0271]

[0272] Among them, I b T is the average output current of the load. s The switching period is i2(t), the input current of the rectifier circuit is i2(t), and I is I2(t). 2rms The effective value of the input current before rectification is determined by the fundamental equivalent impedance of the double-T resonant cavity.

[0273] In this invention, constant current and constant voltage output functions under wide load conditions are achieved through the coordinated operation of a full-bridge inverter module, a dual-T resonant cavity module, an uncontrolled full-bridge rectifier module, and a control module. The full-bridge inverter module converts the input DC voltage into a high-frequency AC square wave signal, providing input power for the subsequent operation of the resonant cavity. The dual-T resonant cavity module flexibly switches between constant current and constant voltage modes by adjusting the conduction state of the AC switch and the equivalent capacitance value of the switched capacitor. In constant current mode, the AC switch is open, and the resonant cavity switches to a single-T topology, providing a constant output current; in constant voltage mode, the AC switch is closed, and the resonant cavity switches to a dual-T topology, outputting a stable voltage. The uncontrolled full-bridge rectifier module rectifies the AC signal output from the resonant cavity into a DC signal for the load. The control module automatically judges and switches modes by real-time monitoring of the voltage and current values ​​at the load end, ensuring the system operates in optimal condition.

[0274] In this embodiment, the full-bridge inverter module receives the input DC voltage V. dc A high-frequency AC square wave signal v is generated by alternately conducting switching transistors Q1, Q2, Q3, and Q4. ab (t). Generally, the Fourier series expression for this signal is:

[0275]

[0276] Where, ω s =2πf s f s This is the switching frequency. Alternatively, its fundamental component v... ab1 (t) is:

[0277]

[0278] The effective value of the fundamental component can be further expressed as:

[0279]

[0280] The high-frequency AC signal output by the full-bridge inverter serves as the input to the dual-T resonant cavity module, driving it to operate in a resonant state.

[0281] In this embodiment, the dual-T resonant cavity module consists of two cascaded T-type topologies. The switching state of the AC switch and the equivalent capacitance C of the switched capacitor are adjusted accordingly. SC This enables switching between constant current and constant voltage modes. Under normal circumstances:

[0282] In constant current mode, the AC switch is open, and the resonant cavity switches to a single-T topology. Specifically, the output current I of the resonant cavity at this time... b The relationship with the input current i2(t) of the rectifier stage can be expressed as:

[0283]

[0284] Among them, I b T represents the average output current of the load. s =1 / f s i is the switching period; i2(t) is the input current of the rectifier stage; I 2rms This is the effective value of the rectified current.

[0285] Based on the fundamental equivalent resistance analysis, the resonant cavity output current can also be expressed as:

[0286]

[0287] In order for the system to operate at the resonant point in constant current mode, the resonant inductance L of the resonant cavity... 13 The value of must satisfy the following formula:

[0288]

[0289] In one possible implementation, the parameter design needs to take into account the load current requirements and input voltage conditions to ensure that the output current is constant.

[0290] In constant voltage mode, the AC switch is turned on, and the resonant cavity switches to a double-T topology. At this time, the input voltage V of the resonant cavity is... i With output voltage V b The relationship is:

[0291]

[0292] Further calculations show that the second-stage inductance L of the resonant cavity... 23 The sensitivity is:

[0293]

[0294] This design ensures stable constant voltage output from the resonant cavity under wide load conditions.

[0295] In one possible implementation, the switched capacitor unit (SCC) achieves the equivalent capacitance value C by adjusting the conduction angle α. SCThe dynamic change of is expressed mathematically as follows:

[0296]

[0297] Specifically:

[0298] In constant current mode, the equivalent capacitance of the switched capacitor is adjusted to a larger C. C To satisfy the impedance characteristics of the single-T topology of the resonant cavity:

[0299] The following impedance conditions must be met:

[0300]

[0301] The following definition is made using impedance:

[0302]

[0303] Simplifying the above formula, we obtain the expression for λ as follows:

[0304]

[0305] Using the impedance definition method, C C This can be expressed as:

[0306]

[0307] Among them, C C The equivalent switched capacitor in constant current mode; α is the control angle; β 21 is the coupling coefficient.

[0308] The above parameters are adjusted in real time by the control module to ensure that the system operates efficiently in constant current mode.

[0309] In constant voltage mode, the equivalent capacitance of the switched capacitor is adjusted to a smaller C. V To adapt to the resonance conditions of the double-T topology:

[0310]

[0311] The dynamic adjustment of the aforementioned switched capacitors depends on the signal output of the control module.

[0312] In this embodiment, the uncontrolled full-bridge rectifier module rectifies the high-frequency AC signal output from the dual-T resonant cavity into a DC signal. The input voltage v of the rectifier stage... cd1 (t) can be expressed as:

[0313]

[0314] Rectified output voltage V o With fundamental voltage V cd The relationship is:

[0315]

[0316] Meanwhile, the rectified input current i2(t) is:

[0317]

[0318] Here, I 2rma This represents the effective value of the input current, and is related to the load power P. b Related.

[0319] Further calculate the equivalent load resistance R eq Value:

[0320]

[0321] Or expressed as load power P b Format:

[0322]

[0323] Among them, V cd I is the fundamental input voltage before rectification in the resonant cavity (the fundamental component of the AC voltage from the resonant cavity); 2rms V is the effective value of the input current before rectification in the resonant cavity; b I is the output voltage at the load terminal. b This is the output current at the load end.

[0324] The control module monitors the load voltage V in real time. o and current I b When V o Less than the set threshold V th When V is constant current, the system maintains constant current mode; when V is constant current, the system maintains constant current mode. o Reaching V th When switching to constant voltage mode, the control module achieves smooth mode switching by adjusting the operating states of the AC switch and switched capacitor. A feedback regulation algorithm is used to avoid voltage or current fluctuations during mode switching, ensuring stable system operation.

[0325] This design enables efficient operation over a wide load range, achieving smooth switching between constant current and constant voltage, while avoiding the frequency offset and circulating current energy loss problems present in traditional LLC topologies.

[0326] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wide load constant current constant voltage dual T resonant DC converter, characterized by, The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. a first T-type resonant unit including a first set of symmetrically designed inductors and , and a capacitor and for forming a first resonant loop; a second T-shaped resonant unit including a second set of symmetrically designed inductors and , and a capacitor and for forming a second resonant loop; The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter.

2. The wide load constant current constant voltage dual T resonant DC converter of claim 1, wherein, The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter.

3. The wide load constant current constant voltage dual T resonant DC converter of claim 1, wherein, The relationship between the equivalent capacitance value of the switch capacitor unit and the conduction angle of the control switch is: ​ ； wherein, Ceq is the equivalent capacitance value of the switched capacitor, C is the linear capacitance value of the switched capacitor, is the phase angle of the conduction angle of the AC switch lagging behind the zero crossing of the input current.

4. The wide load constant current constant voltage dual T resonant DC converter of claim 1, wherein, The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter.

5. The wide load constant current constant voltage dual T resonant DC converter of claim 1, wherein, The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter.

6. The wide load constant current constant voltage dual T resonant DC converter of claim 5, wherein, The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter.

7. A control method of a wide load constant current constant voltage dual-T resonant DC converter, characterized by, The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The full-bridge inverter module converts an input DC voltage into a high-frequency AC square wave signal; The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T resonant DC converter. The application relates to a wide-load constant-current constant-voltage double-T reson In the constant voltage mode, the AC switch is turned on, and the resonant cavity switches to the double-T type topology, and a constant voltage is output; The uncontrolled full-bridge rectification module rectifies the AC output of the resonant cavity into a DC signal; The control module detects the load voltage and current value in real time, and when the load voltage reaches the set threshold value, it switches from the constant current mode to the constant voltage mode.

8. The control method of the wide load constant current constant voltage dual-T resonant DC converter according to claim 7, characterized by, The output current of the resonant cavity in the constant current mode is defined by the following formula: ； wherein, is the average output current of the load, is the switching period, is the input current to the rectification stage, is the RMS value of the input current before rectification, determined by the fundamental equivalent impedance of the double-T resonant cavity.

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