116results about How to "Reduce voltage stress" patented technology

The embodiment of the invention discloses a midpoint potential control method based on a diode clamping type three-level grid-connected inverter and a related device. The method comprises the following steps: generating an initial three-phase modulation wave through a current loop closed-loop control method according to a collected three-phase current value and a three-phase voltage value of a power grid side of the diode-clamped three-level grid-connected inverter; according to an initial modulation waveform generated by the initial three-phase modulation wave, a three-phase current value and an acquired voltage value of a voltage dividing capacitor at the direct current side of the diode clamping type three-level grid-connected inverter, calculating a zero-sequence component required by neutral-point potential balance; superposing a zero-sequence component required by neutral-point potential balance with the initial modulation waveform to obtain a final modulation wave; and generating a driving signal matched with each phase of bridge arm in the diode clamping type three-level grid-connected inverter according to the final modulation wave. By adopting the invention, the neutral-point voltage can be balanced, the distortion of the output waveform at the alternating current side is reduced, the voltage stress of the device is reduced, and the service life of the power device is prolonged.

The invention discloses an operation control method of a low-power-consumption off-grid inverter, electronic equipment and a storage medium, and the operation control method comprises the steps: maintaining an output switch to be in a closed state when the output current of an AC output port is detected to be greater than or equal to a first preset current threshold value under the condition that the off-grid inverter is in a no-load low-power-consumption mode, the inverter side is controlled to close driving, and the driving duty ratio of the LLC low-voltage side is adjusted to be a first preset duty ratio, so that the voltage of the bus capacitor is increased to be a preset steady-state voltage; and when it is detected that the voltage of the bus capacitor reaches the preset steady-state voltage, the inverter side is controlled to start driving. According to the low-power-consumption off-grid inverter, the output switch is kept in the closed state, the inverter side is controlled to close driving, and the driving duty ratio of the LLC low-voltage side is correspondingly adjusted, so that the impact current input by the LLC low-voltage side is reduced, the capacitor voltage stress of the LLC high-voltage side and the stress of a power device of the low-voltage side are reduced, and the reliability of the low-power-consumption off-grid inverter can be remarkably improved.

The invention discloses a vehicle-mounted bidirectional power converter which comprises a pre-stage voltage stabilization module, a pre-stage driving circuit, a post-stage driving circuit, a post-stage filtering module and an electric vehicle battery module, the pre-stage voltage stabilization module is used for balancing circuit voltage and supporting reactive power, the pre-stage driving circuit is of a single-phase full-bridge AD-DC topological structure, and the post-stage filtering module is of a single-phase full-bridge AD-DC topological structure. The front-stage driving circuit is of a half-bridge type bidirectional DC-DC topological structure, the rear-stage driving circuit is of a half-bridge type bidirectional DC-DC topological structure, the front-stage driving circuit and the rear-stage driving circuit are connected together through a direct-current voltage-stabilizing bus, the size is small, the weight is light, a front stage and a rear stage do not interfere with each other, control is easy, the rear-stage filtering module is used for restraining direct-current side second harmonics, the harmonic quantity is prevented from influencing the stability of output direct-current voltage, and the output direct-current voltage is stable. According to the converter, a corresponding control method is designed, non-inductive decoupling control and a single-phase phase-locked loop of an improved loop filter are adopted, the phase of a power grid is accurately and efficiently obtained, and the converter works stably.

The invention relates to a distributed photovoltaic power station main converter and a control method thereof, and belongs to the field of photovoltaic power generation. The main current transformer comprises a T-type three-level current transformer and a Buck-Boost current transformer; the T-type three-level converter comprises three bridge arms, two output capacitors and the like; each bridge arm is provided with four power switch tubes; the two output capacitors are connected in series, and the connection point is called as the midpoint O of the T-type three-level converter. And one end of a direct-current inductor of the Buck-Boost converter is connected with the midpoint O. The T-type three-level converter adopts PI control and a carrier pulse width modulation strategy to realize alternating current side current harmonic wave minimization of the T-type three-level converter; the Buck-Boost converter adopts a PI control method to realize neutral-point potential automatic balance control. The method is small in current harmonic wave, low in cost and simple to control, and can realize quick and automatic balance of the neutral-point potential, thereby effectively coping with the influence of illumination and power grid voltage fluctuation on system control, and realizing quick and stable control of the distributed photovoltaic power station.

The invention belongs to the technical field of direct-current converters, and provides a direct-current converter with ultrahigh voltage gain and a control method thereof, and the main scheme is that the direct-current converter comprises a direct-current input source, an input inductor, a three-winding coupling inductor, a first switching tube, a second switching tube, a first diode, a second diode, a third diode and a fourth diode, a first clamping capacitor, a second clamping capacitor, a third clamping capacitor, a first output capacitor, a second output capacitor, a third output capacitor, a load and a three-winding coupling inductor are arranged, and a first winding, a second winding and a third winding form three windings and are integrated through a single magnetic core. According to the invention, ultrahigh output voltage gain can be realized, almost zero input current ripple can be realized, the semiconductor device can realize soft switching, the number of the devices is small, the cost is low, and the device is suitable for being applied to power conversion between a photovoltaic new energy power generation unit and a high-voltage direct-current bus.

The invention provides a single-pole inverter based on wide gain and low leakage current, and relates to the technical field of inverters. The single-pole inverter based on the wide gain and the low leakage current comprises a DC / DC conversion module of a dual structure, a bus capacitor, a DC / AC inverter and a filter circuit. Wherein the DC / DC conversion module comprises two DC / DC conversion units, the structures and performance parameters of the two DC / DC conversion units are the same, and the two DC / DC conversion units are connected in a symmetrical mode; the front stage of the inverter adopts a symmetrical structure, so that the voltage stress borne by a switching tube when the switching tube is switched off can be reduced, multi-level output is realized, meanwhile, the change frequency of common-mode voltage is greatly reduced, and the leakage current suppression effect is good.

The embodiment of the invention provides an energy conversion circuit, a control method based on the energy conversion circuit and a vehicle. The energy conversion circuit comprises a primary side bridge arm module, a resonance module, a secondary side bridge arm module and a control module. The primary side bridge arm module comprises a first bridge arm and a second bridge arm, and the secondary side bridge arm module comprises a first secondary side switch and a second secondary side switch; the control module controls a driving signal of the first bridge arm, a driving signal of the second bridge arm, a driving signal of the first secondary side switch and a driving signal of the second secondary side switch, so that the voltage between the first direct current positive electrode port and the first direct current negative electrode port is increased to a preset voltage; wherein in the process that the voltage between the first direct current positive electrode port and the first direct current negative electrode port is increased, the zero current of the switch in the secondary side bridge arm module is switched off. According to the embodiment of the invention, the voltage stress of the switch in the energy conversion circuit can be reduced.

The invention relates to a high-gain low-ripple DC-DC converter based on a coupling inductor and a control method. A topological structure of the high-gain low-ripple DC-DC converter comprises an interleaved Boost circuit and an H-bridge auxiliary boost circuit, the interleaving Boost circuit comprises a first coupling inductor, a second coupling inductor, a first switching tube branch and a second switching tube branch. One end of the first coupling inductor and one end of the second coupling inductor are connected in parallel and then connected with an input voltage source, and the first switching tube branch and the second switching tube branch are connected in parallel and then serve as the output end of the interleaved Boost circuit; primary sides of the first coupling inductor and the second coupling inductor are used as filter inductors of the interleaved Boost circuit, secondary sides of the first coupling inductor are connected in series in an anti-phase manner and then are connected with the H-bridge auxiliary boost circuit, and an output end of the H-bridge auxiliary boost circuit is connected with an output end of the interleaved Boost circuit in series and superposed and then is connected with a load. The method can be widely applied to the new energy fields of fuel cells, photovoltaics and the like.

The invention discloses a soft switching logic control circuit and method, an inverter and a storage medium, and relates to the technical field of inverter control, the circuit comprises a control module, a first logic module, an isolation driving module and a power module, the first logic module comprises a first fault detection unit and a first logic processing unit; the control module generates a pulse control signal, the first fault detection unit performs fault detection on a plurality of external hardware circuits and outputs a plurality of corresponding first detection signals, and the first logic processing unit performs logic OR processing according to the plurality of first detection signals and outputs a soft switching control signal. And the isolation driving module drives the power module to work normally according to the pulse control signal, and stops receiving the pulse control signal when receiving the soft switching control signal so as to drive the power module to execute soft switching operation according to the soft switching control signal. According to the invention, the switching loss under the normal operation condition is reduced, and the working efficiency of the inverter is improved.

The invention discloses a buck-boost circuit, a frequency converter, electric equipment and a control method. The buck-boost circuit comprises a buck module, the input end of which is connected with a DC power supply and the output end of which is connected with a load; the input end of the boosting module is connected with the direct-current power supply, and the output end is connected with a load; and the change-over switch is arranged between the step-down module and the step-up module and is used for controlling one of the step-down module and the step-up module to be switched on according to the output voltage of the direct-current power supply and the target direct-current bus voltage. According to the invention, the voltage stress of the switching device can be reduced, thereby reducing the switching loss and the reverse recovery time of the diode, achieving the reduction of the heating of the switching tube, breaking through the frequency limitation of the switching tube, widening the switching frequency range of the switching tube, and widening the output voltage range.

The invention discloses a multi-mode switching control method suitable for a grid-connected isolation inverter, and the method comprises the steps: in each half power grid voltage period, according to a power grid instantaneous voltage phase Theta g outputted by a phase-locked loop in the isolation inverter, the phase Theta g is within [0, pi], then the phase Theta g is compared with given power grid voltage phases Theta g1 and Theta g2, the Theta g1 and Theta g2 meet the condition that Theta g1 is smaller than or equal to Theta g2, and the Theta g1 is smaller than or equal to Theta g2; a variable-frequency discontinuous conduction mode, namely a variable-frequency DCM mode, is adopted in the ranges of 0 < theta g < theta g 1 and pi-theta g 2 < theta g < pi, a main switching tube of a flyback converter in the isolation inverter is controlled to be switched on when the period is larger than a given switching period and the drain-source voltage valley value, and a critical conduction mode, namely a BCM mode, is adopted in the range of theta g 1 < theta g < pi-theta g 2. And controlling a main switch tube of the flyback converter to be switched on at the drain-source voltage valley value. Different working modes are adopted under different output voltages, so that the switching loss of the isolation inverter in a full-load range is reduced, and the energy conversion efficiency of the isolation inverter is greatly improved.

A port-reuse bidirectional charger and an application method thereof, comprising: a plurality of switching switches, a rectifier, a plurality of isolated bidirectional DC / DC converters and a charging interface; the rectifier is connected to the AC power of a power grid and is used to convert the AC power into DC power; the input sides of the plurality of isolated bidirectional DC / DC converters are connected in parallel to the rectifier, and the output sides are respectively connected to the charging interface through the switching switches; the storage battery to be charged / discharged is connected to the charging interface, and the number and connection mode of the output isolated bidirectional DC / DC converters are selected by setting the on / off of the switching switch to meet the charging and discharging power requirements of the storage battery. The switching switch is placed on the output side of the charger to realize port reuse. When the power requirements are different, different numbers of chargers can be used in parallel without redesigning the circuit, which is convenient for use.

The invention relates to the technical field of power electronic direct-current converters, in particular to an input and output common-ground high-gain boost converter which comprises a direct-current voltage source Vin, diode components D0-D4, capacitor components C0-C4, a first coupling inductor L1, a second coupling inductor L2, a first mosfet tube S1, a second mosfet tube S2 and a resistor R. The two main loops operate in a staggered mode, so that input current is continuous, input current ripples are small, relatively stable energy is continuously provided for the circuit, the voltage multiplication unit is adopted, the amplification factor of the circuit is increased, the duty ratio of the mosfet tubes S1 and S2 is adjusted, and small current ripples can be kept even under the condition that the boost factor is large. The device has the advantages of high step-up ratio, low device stress, high efficiency, easiness in control and implementation, lower cost and the like, and is suitable for a new energy power generation scene needing high direct current bus voltage grid-connected output under a low input voltage condition.

The present invention aims to provide a vehicle-mounted auxiliary power DC-DC converter, including an input capacitor C1, a Buck converter, a Boost converter, an output capacitor C2, and an LLC resonant converter; the Buck converter and the Boost converter are respectively composed of two branches, and the two branches of the Buck converter are connected in series with the two branches of the Boost converter in a one-to-one correspondence to form two groups of parallel Buck-Boost branch structures; the Buck-Boost branch structure is connected to the vehicle power battery in parallel with the input capacitor C1, and the Buck-Boost branch structure is connected to the input end of the LLC resonant converter in parallel with the output capacitor C2. The present invention also provides an integrated digital control method for a vehicle-mounted auxiliary power DC-DC converter. The converter overcomes the defects of the prior art and has the characteristics of a wide input voltage range, low conduction loss, and low cost.

The dual-output energy conversion device, modulation method and power supply equipment provided by the present invention can greatly improve the bus voltage boosting capability of the conversion device by adopting the first electrical energy storage module, so that it can be used within a wider input voltage range. The first conversion output circuit and the second conversion output circuit are provided, and the voltage stress of all switch tubes is reduced to half of the DC bus voltage, which can greatly reduce the system EMI of the conversion device in high-frequency applications and improve the power conversion efficiency of the device. Compared with the traditional multi-stage structure, which needs to realize the midpoint voltage clamping of the front stage and the rear stage and other controls at the same time, and the control structure is complicated, the dual-output energy conversion device provided by the present invention only needs to realize the control of one-stage power conversion, and the control structure is simple.

This invention discloses a phase-shifted full-bridge plasma power supply based on all SiC devices, belonging to the field of special power supply technology. It includes: a rectifier unit with a power factor correction circuit; an inverter unit containing a phase-shifted full-bridge topology composed of SiC power devices and an energy storage inductor, achieving zero-voltage switching through phase-shift control; a transformer unit; an output unit including an output filter capacitor; and a control unit that uses an incremental PID algorithm to generate phase-shift control signals. This invention analyzes the differences in zero-voltage switching between the leading and lagging bridge arms, utilizes the low output capacitance characteristics and dynamic dead-time adjustment of SiC devices, broadens the soft-switching range under light loads, effectively reduces output current ripple, and improves dynamic response speed and overall efficiency.

The present invention provides a zero-crossing resonance ZVS control circuit of a four-switch buck-boost converter, which enables some switches to work in a ZCS state to reduce the loss of circuit switch components. i >V o When the inductor current changes from negative to positive, Q4 is turned off, so that Q4 is turned off with zero current; when V i <V o When the inductor current changes from positive to negative, Q1 is turned off, so that Q1 is turned off with zero current. The present invention uses an inductor current zero-crossing control method for a four-switch buck-boost converter, breaking the limitation of the ZVS current. Under the same output current condition, the effective value of the inductor current can be reduced, and the circuit loss can be reduced; and a lower switching frequency can be obtained when the same power is output, which is beneficial to reducing the loss of the switching device; at the same time, the corresponding switching device can be turned off at the current zero-crossing point, which is beneficial to reducing the switching loss and voltage stress of the switching device, and further improving the conversion efficiency of the circuit.

The present invention provides a unipolar inverter based on wide gain and low leakage current, and relates to the technical field of inverters. The unipolar inverter based on wide gain and low leakage current of the present invention comprises a DC / DC conversion module with a dual structure, a bus capacitor, a DC / AC inverter and a filter circuit; wherein the DC / DC conversion module comprises two DC / DC conversion units, the structures and performance parameters of the two DC / DC conversion units are the same, and the two DC / DC conversion units are connected in a symmetrical manner; the front stage of the inverter adopts a symmetrical structure, which can reduce the voltage stress of the switch tube when it is turned off, realize multi-level output, and at the same time, greatly reduce the change frequency of the common mode voltage, and the leakage current suppression effect is good.

The utility model provides a double-end flyback circuit and a power supply. The double-end flyback circuit comprises a first absorption unit, a second absorption unit and a transformer, the transformer comprises a secondary winding, a first primary winding and a second primary winding, wherein the first primary winding and the second primary winding are connected in series. The second end of the first absorption unit is in one-way conduction with the first end of the first absorption unit and is used for freewheeling of the first primary winding when the path is disconnected; the second end of the second absorption unit is unidirectionally conducted to the first end of the second absorption unit and is used for freewheeling the second primary winding when the path is disconnected; the first absorption unit and the second absorption unit are further used for being connected in series when the access is disconnected and jointly form follow current for the first primary winding and the second primary winding. Three follow current loops can be formed when the access is disconnected, the peak voltage of the transformer can be well absorbed through the three follow current loops, the difference of the number of turns of the two primary windings does not affect the absorption of the peak voltage, and the performance of the circuit is effectively improved.

The present invention discloses an ultra-high voltage gain DC / AC converter based on synchronous PWM control, including a synchronous PWM control module and a three-port half-bridge inverter unit, wherein the three-port half-bridge inverter unit includes a dual three-port boost unit; the synchronous PWM control module controls the output voltage by adjusting the duty cycle of two switch tubes; the dual three-port boost unit is used to achieve ultra-high voltage gain; the three-port half-bridge inverter converts direct current into alternating current to connect to the power grid. Ultra-high voltage gain is achieved by staggered charging and discharging between capacitors. The converter includes two sets of coupled inductors, and the input current ripples of the two branches are complementary, so that low ripple continuous input current can be achieved. The converter is an isolated converter, and can output positive and negative equal or unequal bipolar voltages, which can effectively reduce the leakage current caused by the parasitic capacitance of the input side photovoltaic panel, so that it can be used in the field of photovoltaic power generation and grid connection.

The present invention discloses a high-stability, low-ripple high-voltage DC converter. The high-voltage DC converter includes a full-bridge inverter circuit, a resonant filter circuit, a transformer, and a voltage doubler rectifier circuit connected in sequence: wherein the voltage doubler rectifier circuit is formed by cascading a plurality of voltage doubler modules; the output ends of a plurality of the voltage doubler modules are connected in series to form a high-voltage DC output; each of the voltage doubler modules is formed by connecting a plurality of voltage doubler units in parallel and output in series and then connecting them in parallel with a bus capacitor; all bus capacitors are connected in series in sequence and then connected to the load. The voltage doubler rectifier circuit in the scheme of the present invention reduces the average current value and voltage variation on the capacitor and reduces the output ripple without increasing the device voltage level; at the same time, it reduces the total output voltage variation when the load changes, reduces the voltage regulation range of the resonant cavity, and improves the output voltage stability.

The invention provides further optimization for a six-switch flying capacitor step-down conversion circuit and a four-switch flying capacitor step-down conversion circuit applied to an intermediate bus converter. On one hand, the power conversion device is provided, the voltage spike of the switching tube is absorbed by optimizing the clamping circuit and the layout of the clamping circuit, the voltage stress of the switching tube is reduced, extra loss is not generated, and therefore the conversion efficiency of the power conversion device is improved. On the other hand, by optimizing the current sampling circuit, the monitoring and control performance related to the current is optimized, and the size of the power conversion device is reduced.

The application relates to a flyback power supply circuit and a power supply. The flyback primary side circuit comprises a primary side winding connected with a high-voltage power supply. The flyback secondary side circuit comprises a secondary side winding, a switching unit, an energy buffer unit and a charging unit. The switching unit is connected with the secondary side winding. The energy buffer unit is connected with the switching unit, the charging unit and a power supply output end respectively. The charging unit is used for charging the energy buffer unit before the flyback primary side circuit is connected with the high-voltage power supply. The charging unit arranged in the flyback secondary side circuit can charge the energy buffer unit in the flyback secondary side circuit before the flyback power supply circuit is connected with the high-voltage power supply, so that negative voltage of the flyback secondary side circuit is avoided. The application can reduce voltage stress of the switching unit when the flyback secondary side circuit starts, and improve stability and reliability of the flyback power supply circuit.

The invention discloses a voltage regulating circuit and an inverter system, the voltage regulating circuit comprises a first capacitor C1, a voltage dividing branch and a voltage stabilizer D which are connected in parallel between a first node and a second node, a second capacitor C2 and a resistor R0 are connected in parallel between the second node and a third node, and the voltage between the first node and the third node is the total voltage Vs; partial voltage of the total voltage Vs at the first node and the third node is used as driving voltage of the switching tube; a voltage dividing point of the voltage dividing branch is connected to the voltage stabilizer D, and the voltage stabilizer D adjusts the voltage drop of the resistor R0 based on the voltage V2 of the voltage dividing point; the voltage monitoring module is used for monitoring the bus voltage of the inverter system, and when the bus voltage is smaller than a voltage threshold value, the partial voltage of the first node serves as the first driving voltage Vout1; when the bus voltage is larger than the voltage threshold value, the partial voltage of the first node serves as the second driving voltage Vout2, and the first driving voltage Vout1 is larger than the second driving voltage Vout2.

The invention discloses a converter circuit for suppressing output voltage spikes. The converter circuit comprises a transformer module, an input module, a rectification output module, a first capacitive suppression module and a second capacitive suppression module, wherein the input module is arranged on a primary winding of the transformer module; the rectification output module, the first capacitive suppression module and the second capacitive suppression module are arranged on a secondary winding of the transformer module; the first capacitive suppression module is bridged at the two ends of a first path inductor, and the first path inductor is located between the first end of the secondary winding and the first end of the rectification output module; the second capacitive suppression module is bridged at the two ends of a second path inductor, and the second path inductor is located between the second end of the secondary winding and the second end of the rectification output module; the capacitive suppression module only comprises a capacitor. According to the invention, the junction capacitance parasitic oscillation in the turn-on and turn-off processes of the rectification device in the output rectification module can be suppressed, and the output voltage spike of the output rectification module can be greatly reduced, so that the voltage stress of the output rectification module is reduced, and the circuit stability is improved.

The invention discloses a self-adaptive space energy system, and the system comprises a power management unit which controls an electromagnetic induction type wireless charging device, a graphene battery pack or a ground power supply to supply power to a spacecraft through transmitting a power control signal to a power distribution module according to the working mode information transmitted by an external main control computer, charging and discharging of the graphene battery pack are controlled; wake-up control of the graphene battery pack is carried out through a wake-up instruction sent by the wake-up module or an internal timing wake-up signal; detecting a power supply state according to the working state information fed back by the power distribution module; the electromagnetic induction type wireless charging device charges the graphene battery pack in a wireless charging mode; the wake-up module is used for performing signal conversion on the external light wake-up signal, generating a wake-up instruction and sending the wake-up instruction to the power management unit; the power distribution module supplies power to equipment needing power supply; and the working state information is fed back to the power management unit. According to the invention, the reliability problem of a single wake-up mode in a long-time sleep mode is solved.

The application discloses a three-level full-bridge dual active bridge converter and a midpoint potential balance control method. The converter comprises a high-frequency transformer, a DC input voltage source is arranged on the primary side of the high-frequency transformer, and series-connected upper and lower capacitors are connected between the positive and negative electrodes of the DC input voltage source. Three-level half-bridge A and three-level half-bridge B are connected in parallel, a node between the upper and lower capacitors is connected to the midpoint of two clamping diodes of the two three-level half-bridges, the center point of the three-level half-bridge A is connected to one end of the primary side of the high-frequency transformer through a power transmission inductor, and the center point of the three-level half-bridge A is connected to the other end of the primary side of the high-frequency transformer through a DC isolation capacitor. In the control method, the primary side power device is divided into a fixed 50% duty ratio basic bridge arm and a non-symmetrical duty ratio adjusting bridge arm, a PI voltage balance loop is constructed by taking the voltage difference of the two capacitors as feedback, the duty ratio of the adjusting bridge arm is dynamically adjusted, the average value of the midpoint current is changed, and the midpoint potential balance is realized.

The utility model discloses a kind of magnetic integrated type secondary side low-voltage side winding circuit, it includes primary side full bridge part, secondary side high-voltage side and secondary side low-voltage side, the secondary side low-voltage side is connected with M9NNMOS pipe, M10NNMOS pipe and M12NNMOS pipe in parallel, the secondary side low-voltage side is accessed primary side full bridge part after a plurality of first resistors and a plurality of capacitors are connected in parallel and then with M11NNMOS pipe series connection.In this application, when the NMOS pipe of secondary side high-voltage side opens, the secondary side low-voltage side M11NNMOS pipe is opened simultaneously to reduce winding floating voltage and reduce the voltage stress of M9 and M10 NMOS.

The present invention discloses a unidirectional multi-string photovoltaic inverter circuit control device and control method, the device includes: a unidirectional multi-string photovoltaic inverter circuit and a switching regulator, wherein the unidirectional multi-string photovoltaic inverter circuit includes a solar cell array component, a high-frequency AC link and a three-phase AC inverter, and the switching regulator is used to control the input circuit switch tube in the solar cell array component according to the input reference current output after the MPPT operation of several solar cell array strings in the solar cell array component, and is used to control the output circuit switch tube in the three-phase AC inverter according to the output reference current of the three-phase AC inverter. The present invention can reduce the voltage stress on the power electronic switch in the inverter circuit, and can improve the conversion efficiency and power density of the photovoltaic system, and can make the solar cell array string work under different operating conditions and realize the isolation of different working modes.

This invention discloses a variable frequency low-voltage stress control system and its control method based on autonomous resonance. The control system includes: a DC voltage source, a primary-side inverter unit, a secondary-side inverter unit, a primary-side resonant branch, a secondary-side resonant branch, a secondary-side rectifier unit, an energy storage branch, a filter capacitor, and a load. The DC voltage source is connected to the primary-side inverter unit; the energy storage branch is connected to the secondary-side inverter unit; the primary-side inverter unit is connected to the secondary-side inverter unit through the primary-side resonant branch; the secondary-side resonant branch is connected to the secondary-side rectifier unit; and the secondary-side rectifier unit is connected in parallel with the filter capacitor and the load. This invention not only reduces the voltage stress on the energy storage capacitor and related power devices, reducing the risk of device damage and extending the system's service life, but also improves the system's energy utilization efficiency without requiring additional energy-consuming absorption circuits, thus possessing significant engineering application value.