1167results about "Conversion without intermediate conversion to dc" patented technology

A control system configured to control switching of taps of an on-load tap changer provided on an electric power transformer. The on-load tap changer includes switches that are controllable to switch between transformer taps. The control system includes a detector configured to detect an indication of a zero crossing of a transformer voltage of the transformer and a control signal generator configured to generate a control signal that controls a switching of the switches for performing a tap change to a new transformer tap. The control signal generator is configured to determine the timing of the control signal for changing the transformer tap based on the detected indication of the zero crossing of the transformer voltage such that the switching of at least one of the switches for performing the tap change occurs a predetermined time prior to a zero crossing of a tap voltage at the new transformer tap.

The invention relates to the field of transformer control, and discloses a solid-state distribution transformer control system and method for improving access of a distributed power supply, which are used for solving the problem that original controller parameters are not representative due to access change of the distributed power supply when the solid-state distribution transformer is controlled. The method comprises the following steps: constructing a solid-state distribution transformer with a multi-port power regulation capability, setting initial control parameters, obtaining equivalent impedance influenced data, evaluating according to the equivalent impedance influenced data to obtain an equivalent impedance change index, judging whether the equivalent impedance is changed according to the equivalent impedance change index, and if the equivalent impedance is judged to be changed, judging whether the equivalent impedance is changed or not. If yes, dynamically correcting the initial control parameter according to the equivalent impedance change index to obtain an actual control parameter, and adjusting the output of the solid-state transformer according to the actual control parameter, thereby effectively improving the accuracy of transformer control and the reliability of energy supply.

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

The invention discloses a non-isolated DC / DC power converter and a power conversion apparatus. The non-isolated DC / DC power converter comprises a power module comprising a first power conversion circuit, the first power conversion circuit being a non-isolated DC / DC conversion circuit, a first output end of the first power conversion circuit is connected with a first inductor, and a second output end of the first power conversion circuit is connected with a second inductor; and an oscillation suppression module comprising a second power conversion circuit, a first terminal of the second power conversion circuit coupled in parallel to an input end of the first power conversion circuit, a first terminal current of the second power conversion circuit being in phase with at least partial of AC components of an input voltage of the oscillation suppression module, and the second power conversion circuit being a bidirectional DC / DC conversion circuit.

The invention provides a backflow power suppression method, device and system of a converter and a readable storage medium, and the method comprises the steps: calculating a first modulation parameter of the converter based on the output voltage of the converter, and outputting a plurality of first target driving signals for driving a part of switching tubes to be switched on or switched off based on the first modulation parameter, therefore, closed-loop control on the output voltage of the converter is realized; after closed-loop control, calculating a second modulation parameter when the backflow power of the converter is smaller than or equal to a preset threshold value based on the first modulation parameter; wherein one of the first modulation parameter and the second modulation parameter is a phase shift ratio, and the other one is a modulation ratio; and respectively outputting a plurality of second target driving signals for driving the other switching tubes to be switched on or switched off based on the second modulation parameter, thereby controlling the backflow power in the switching period of the converter within a certain range. Through the implementation of the scheme, the efficiency and the service life of the converter can be remarkably improved.

The present disclosure relates to circuits for connecting components of a hydrogen plant to a power grid to power the components in an efficient manner. In one implementation, power-side alternate current (AC) to direct current (DC) converters may be connected to a source power grid without the need for an isolation transformer by providing separate buses between the power-side AC-DC converters and load-side DC-DC converters instead of a shared DC bus between the converters. Other implementations for connecting components of a hydrogen plant to a power grid may include an adjustable transformer, such as a tappable transformer or an autotransformer, to connect any number of auxiliary loads of the plant to the power grid. The adjustable transformer may provide for various types of auxiliary load devices to connect to the power provided by the transformer at the same time, including both three-phase devices and one-phase devices.

The invention discloses a 10kV distribution transformer on-load voltage regulation control method and system, and relates to the technical field of transformer on-load voltage regulation, and the method comprises the steps: collecting the three-phase voltage and current of a low-voltage side of a distribution transformer and a tap switch gear signal, and loading a preset voltage regulation control mode and an oscillation region parameter; based on the acquired three-phase voltage and current of the low-voltage side of the distribution transformer and the tap switch gear signal, calculating a feeder comprehensive impedance parameter and a load reactive power parameter, and outputting a transformer operation state index; according to the transformer operation state index, the voltage regulation control mode and the oscillation area rule, current voltage out-of-limit and reactive power deviation are judged, and a voltage regulation strategy triggering instruction is generated according to the judgment result; and calculating upper and lower limit values of feed line correction voltage based on the voltage regulation strategy trigger instruction, and controlling the tap switch to execute voltage regulation action. According to the method, a combined calculation scheme of feeder comprehensive impedance and load reactive power is fused, and dynamic optimization of the triggering condition of the voltage regulation strategy is achieved.

A power receiving device performs a power supply control including repeatedly performing: first rectification mode in which in response to detection of an energization of a first bridge circuit, a first high-side and a second low-side switches are turned on and a first low-side and a second high-side switches are turned off; and second rectification mode in which in response to detection of an energization of a second bridge circuit, the first low-side and the second high-side switches are turned on and the first high-side and the second low-side switches are turned off, and a power adjustment control including: first commutation mode in which the first high-side switch is turned off and the first low-side switch is turned on during the first rectification mode; and second commutation mode in which the second high-side switch is turned off and the second low-side switch is turned on during the second rectification mode.

The invention relates to a degaussing power supply system based on a flywheel energy storage device, and belongs to the technical field of pulse power supplies. The degaussing power supply system comprises a middle-high voltage feeder cabinet, a transformer, a network side rectifier, a four-quadrant DC / DC converter, a flywheel energy storage device and a degaussing coil, the middle-high voltage feeder cabinet is sequentially connected with the transformer, the grid-side rectifier, the four-quadrant DC / DC converter and the degaussing coil after outgoing; one or more flywheel energy storage devices are provided; all the flywheel energy storage devices are connected in parallel to the direct current side of the grid-side rectifier; each flywheel energy storage device comprises at least one flywheel motor, flywheel side converters with the same number as the flywheel motors, and a bidirectional DC / DC converter; each flywheel motor is connected with the bidirectional DC / DC converter through a flywheel side converter; the degaussing coil can provide required pulse working current for the high-power degaussing coil, meanwhile, the impact of the degaussing coil on a power grid during working is remarkably reduced, and the degaussing coil is easy to popularize and apply.

The invention discloses a wide-voltage bidirectional charging and discharging device and a control method thereof, the wide-voltage bidirectional charging and discharging device comprises a first bidirectional inversion module, a first transformer, a second bidirectional inversion module, a first voltage conversion module and a control module, the first voltage conversion module is controlled to be switched to a boost conversion state or a buck conversion state according to the charging and discharging state, the voltage of the first direct current port, the voltage of the fourth direct current port and the turn ratio of the first transformer; according to the technical scheme, the voltage is monitored in real time, the step-up state or the step-down state is intelligently switched according to the turn ratio of the first transformer, bidirectional charging and discharging control in a wide voltage range is achieved, the problems that an existing device is single in function and limited in adaptation range are solved, and the service life of the device is prolonged. And moreover, the compatibility of batteries and loads with different voltage levels is greatly improved, the efficient and flexible charging and discharging requirements in multiple scenes are met, and good applicability and popularization value are achieved.

The present application relates to the technical field of offshore direct current transmission, and provides a parallel-type offshore wind power direct current transmission system, and a starting control method and apparatus. The system comprises: an onshore power grid, an onshore converter station, an offshore converter station, and an offshore wind farm; the onshore power grid is connected to the onshore converter station; the onshore converter station is connected to the offshore converter station, and the offshore converter station comprises an offshore auxiliary flexible direct current converter valve and a diode valve connected in parallel to the offshore auxiliary flexible direct current converter valve; a first bypass switch is connected between one end at the direct current side of the offshore auxiliary flexible direct current converter valve and one end at the direct current side of the diode valve; a second bypass switch is connected between the other end at the direct current side of the offshore auxiliary flexible direct current converter valve and the other end at the direct current side of the diode valve; and the offshore auxiliary flexible direct current converter valve and the diode valve are separately connected to the offshore wind farm. According to the present application, the size of the converter valve in the offshore converter station is reduced, thereby reducing the costs of the converter valve.

The invention relates to the technical field of power electronics, and discloses a dielectric barrier discharge high-voltage series resonance system and a control method thereof. The system comprises a high-voltage series resonance circuit, an upper computer and a hardware circuit. The upper computer is electrically connected with the hardware circuit, and the hardware circuit is electrically connected with the high-voltage series resonance circuit; wherein the high-voltage series resonance circuit comprises a PFC circuit, a Buck circuit, an LC series resonance circuit, a high-voltage pulse transformer and a dielectric barrier discharge load which are connected in sequence, the high-voltage series resonance circuit converts alternating current into high-frequency high-voltage pulse voltage and provides the high-frequency high-voltage pulse voltage for the dielectric barrier discharge load, and stable dielectric barrier discharge is generated; the upper computer is used for setting parameters, the hardware circuit controls the on-off state of the Buck circuit and the LC series resonance circuit according to the parameters set by the upper computer, accurate generation and control of high-voltage pulse voltage in the dielectric barrier discharge process are achieved, and the response speed and the control precision of the system are also improved.

The invention discloses a transformer-based analog quantity isolation transmission device and method. The transformer-based analog quantity isolation transmission device comprises an analog quantity input module, a symmetric square wave transformation module, a transformer module, a rectifier module and an analog quantity output module, the analog quantity input module is used for inputting analog quantity; the symmetrical square wave conversion module is used for converting the input analog quantity into symmetrical alternating-current square waves; the transformer module is used for transmitting the converted alternating-current square wave from the primary side of a transformer to the secondary side of the transformer, and isolation of analog quantity is achieved through the transformer; the rectifier module is used for rectifying the alternating-current square wave isolated by the transformer to realize analog quantity reduction; and the analog quantity output module is used for outputting analog quantity. According to the invention, the analog quantity can be directly transmitted based on the transformer.

The invention discloses a parallel discharge circuit and an electric flame stove. The parallel discharge circuit comprises a transformer and at least two groups of discharge branches, and the two groups of discharge branches comprise a first discharge branch and a second discharge branch. The scheme that a single transformer replaces multiple transformers is adopted, multi-time conversion loss of electric energy-magnetic energy-electric energy is reduced, electromagnetic interference is reduced, meanwhile, a stove body does not need to be provided with a large number of transformers, the size is more compact, and the parallel connection requirement of hundreds of discharging devices of the high-power electric flame stove is met; according to the invention, continuous control of asynchronous breakdown and independent charging and discharging of multiple discharging branches is realized, the method is adaptive to the breakdown threshold value difference of discharging devices among the discharging branches and the charging speed deviation of voltage-multiplying capacitors, extra voltage-sharing control is not needed, and it is ensured that all the discharging branches can stably complete charging and discharging closed loop, discharging failure is avoided, and mutual interference is avoided; the wide-voltage input circuit is suitable for various voltage inputs, and wide-voltage input is achieved.

The invention relates to the technical field of air purification, and discloses a negative oxygen ion generator and a method thereof.The negative oxygen ion generator comprises an external shell used for providing installation positions for related parts; the power supply input module is mounted in the external shell, is internally provided with a filtering unit, and is used for receiving external direct current; the direct current and alternating current inversion module is electrically connected with the output end of the power supply input module, is internally provided with a switch assembly and is used for converting the direct current into high-frequency alternating current; a primary winding, a secondary winding and a feedback winding are arranged in the boosting transformer. A boosting transformer is arranged between a direct current and alternating current inversion module and a high-voltage double-voltage rectification module, so that the voltage is effectively boosted, more importantly, the magnetic field coupling characteristics of a primary winding and a secondary winding are utilized, reliable electrical isolation is constructed, and a physical path from a high-voltage side circuit to a low-voltage side circuit is blocked.

According to the control method of the three-phase decoupling series connection type power flow regulation and control equipment, the equipment comprises a three-phase four-bridge-arm inverter and three single-phase transformers, the three-phase output end of the inverter is connected with the primary sides of the three transformers respectively, neutral points of the primary sides of the three transformers are connected with the zero line phase output end of the inverter, and the neutral points of the primary sides of the three transformers are connected with the zero line phase output end of the inverter. The secondary sides of the three transformers are respectively connected with a normally open switch, the normally open switches are connected in series on a power distribution network line connected with the two three-phase alternating current sources, when the normally open switches are kept in an off state, the power flow regulation and control equipment can carry out power flow regulation and control on A-end and B-end network sides formed by the two three-phase alternating current sources, and when the power flow regulation and control equipment does not work, the power flow regulation and control equipment can carry out power flow regulation and control on the A-end and B-end network sides. And the normally open switch is closed. The invention can effectively solve the problems that the traditional parallel power flow regulation and control equipment has strict requirements on the voltage resistance of devices, and the traditional series power flow regulation and control equipment cannot independently regulate and control the interphase power or has a large number of devices.

The present invention provides a power converter, a resisting method in inductive load switching, and a power generation system. The power converter includes a direct current input end, an alternating current output end, a bus capacitor, a DC / AC power conversion circuit, and a controller. The direct current input end is configured to connect to a direct current source. The alternating current output end is configured to connect to a load. The bus capacitor includes a positive bus capacitor and a negative bus capacitor that are connected in series. The positive bus capacitor is connected to a positive direct current bus. The negative bus capacitor is connected to a negative direct current bus. The DC / AC power conversion circuit is connected in parallel between the positive direct current bus and the negative direct current bus, and configured to convert a direct current from the direct current source into an alternating current, and transmit the alternating current to the load through the alternating current output end. The controller is configured to control, based on an even harmonic current on a connection line between the DC / AC power conversion circuit and the load, an output voltage at which the power converter outputs the alternating current, to reduce an absolute value of a voltage difference between the positive bus capacitor and the negative bus capacitor.

The invention discloses an efficient new energy transformer and an electric energy control system, and relates to the technical field of transformers, an input power conversion module is used for converting a direct current or alternating current variable voltage source into high-frequency alternating current for output, and a high-frequency isolation transformer module adopts a nanocrystalline-amorphous alloy mixed magnetic core. The windings are arranged in a three-layer staggered mode and provided with an oil dual-cooling system, and the output rectification inversion module is used for converting high-frequency alternating current into needed direct current or alternating current to be output and integrates the multi-phase synchronous rectification function and the active filtering function. By designing the nanocrystalline-amorphous alloy mixed magnetic core and the three-layer staggered winding, leakage inductance is reduced, the coupling coefficient is increased, the problems of leakage inductance and nonuniform magnetic flux caused by serious iron loss, large leakage inductance and unreasonable coil arrangement of a traditional single-material low-frequency iron core at medium and high frequencies are solved, hysteresis and eddy-current loss are effectively inhibited, and the service life of the low-frequency iron core is prolonged. The leakage inductance is minimized, the high-frequency transformation efficiency is improved, and the size and the weight are reduced.

The invention discloses an anti-countercurrent control method and system for an energy storage transformer driven by bidirectional power regulation, and relates to the technical field of anti-countercurrent control of transformers, and the method comprises the steps: collecting the active power of a gateway ammeter, the active power of a load, the capacity of a transformer and a power factor of a power grid power supply grid-connected point in real time, and constructing a real-time operation data set; energy storage discharge countercurrent risk identification is carried out, segmented discharge is triggered to reduce protection, and segmented power adjustment is carried out in the discharge direction; according to the real-time operation data set, overload risk identification of the energy storage charging transformer is carried out, segmented charging demand reduction protection is triggered, and segmented power adjustment is executed in the charging direction. The technical problems that in the prior art, countercurrent is likely to happen during discharging of the energy storage transformer, overload is likely to happen during charging, and consequently equipment operation is not safe and a power grid is not stable are solved, and the technical effect that the operation safety of the energy storage transformer and the stability of the power grid are improved through the segmented power adjustment and power slow rising strategy is achieved.

The invention provides a soft switching control method, device and system of a converter and a readable storage medium, and the method comprises the steps: calculating a first modulation parameter of the converter, and generating a plurality of first target driving signals based on the first modulation parameter, so as to control the connection or disconnection of a corresponding first target switching tube through each first target driving signal, the closed-loop control of the output voltage and the input current of the converter is realized; calculating a second modulation parameter of the converter after closed-loop control based on the first modulation parameter; wherein one of the first modulation parameter and the second modulation parameter is a modulation ratio, and the other one is a phase shift ratio; generating a plurality of second target driving signals based on the second modulation parameter; wherein the driving signal corresponding to the modulation ratio is used for controlling each switching tube of the matrix circuit to be switched on or switched off, and the driving signal corresponding to the phase shift ratio is used for controlling each switching tube of the full-bridge circuit to be switched on or switched off. By implementing the scheme of the invention, soft switching of all switching tubes within a full voltage range and a full load range can be realized.

The invention relates to a flexible loop closing device and a flexible loop closing method. The flexible loop closing device is arranged between a first power distribution network and a second power distribution network, and comprises a three-phase full-bridge inverter and a three-phase transformer, the three-phase output end of the three-phase full-bridge inverter is connected with the primary side of the three-phase transformer. The secondary side of the three-phase transformer is connected with a control switch, and each control switch is connected in series between the first power distribution network and the second power distribution network; and the flexible loop closing device controls the control switch to be closed under the condition that the actual output voltage of the flexible loop closing device meets a preset condition, so that flexible loop closing of the first power distribution network and the second power distribution network is realized. By adopting the device, the switch can be controlled to be switched on under the condition that the actual output voltage of the flexible loop closing device meets the preset condition, at the moment, flexible loop closing of the first power distribution network and the second power distribution network is achieved, and large impact current generated by direct loop closing is restrained.

The invention discloses an improved single-bridge arm power electronic transformer topological structure, which belongs to the field of power electronic converters and comprises a three-phase alternating current filter inductor Lg, a phase main bridge arm circuit, a three-phase common half-bridge circuit, a high-frequency series inductor capacitor L1 / C1, a high-frequency isolation transformer, a low-voltage side rectifier and a common isolation DC-DC converter. The topological structure belongs to a single-stage structure, each phase only needs a string of bridge arms, alternating-current and direct-current side power transmission is realized by directly adopting hybrid frequency conversion, the number of devices of a power electronic transformer can be reduced, and the cost is reduced; a three-phase common half-bridge circuit is introduced, so that the multi-frequency coupling degree of a bridge arm is reduced, and control is simplified; and the reasonable circuit parameter design is combined, the number of the main bridge arm sub-modules is optimized, and the efficiency can be improved. The topology is suitable for all application occasions needing conversion from medium-voltage alternating current to low-voltage direct current.

According to the power supply equipment and the base station provided by the invention, the port matched with the terminal equipment can be selected, namely, the matching relationship between the port and the terminal equipment can be determined, so that the workload is reduced, and unnecessary loss caused by mistaken turn-off of the terminal equipment is avoided. The power supply device may include a first bus, a plurality of inductors, a plurality of acquisition units, a plurality of switches, a plurality of ports, and a controller. And the plurality of inductors, the plurality of acquisition units, the plurality of switches and the plurality of ports are in one-to-one correspondence. Each of the plurality of ports may be connected with the first bus through an acquisition unit and an inductor. Each of the plurality of switches may be connected between the first bus and the port. Each acquisition unit can be used for acquiring the output current of the port and transmitting the output current to the controller. The controller can be used for selecting a first port in a state of supplying power to the terminal equipment from the plurality of ports according to the respective output current of the plurality of ports, and transmitting an alternating current signal to the terminal equipment by controlling the switches corresponding to the first port to be closed in sequence; and selecting a port matched with the terminal equipment according to the obtained amplitude and address information of the alternating current signal of the terminal equipment.

The invention provides an AC-AC converter control parameter setting method, and belongs to the field of power electronic control. In order to solve the problems that traditional PID control parameters are lagged in adjustment and large in overshoot under the dynamic working condition, an AC-AC converter small-signal model of a single-tube reverse series bidirectional electronic switch topology is established, and the control parameters are optimized in combination with frequency domain characteristics. The method specifically comprises the following steps: establishing a state-space equation by adopting a switching period averaging method, performing linearization processing, and deducing a system dynamic transfer function; introducing duty ratio disturbance based on a steady-state working point to construct a small-signal model, and forming a three-order open-loop system through a serial PI controller; and according to a closed-loop pole configuration matching characteristic equation coefficient, analyzing and solving proportion and integral parameters. By dynamically optimizing the phase margin and the gain margin, the response speed and stability of the converter under input fluctuation and load abrupt change are remarkably improved, and the method has high engineering application value.

A method of generating a timing control signal for controlling the timing of a change of a transformer tap of a transformer is provided. The transformer includes an on-load tap changer including plural respective transformer taps. The method includes monitoring a voltage on a primary side and / or on a secondary side of the transformer to obtain a monitoring signal and deriving, from the monitoring signal, an intermediate signal that is indicative of at least one zero crossing of a tap voltage at the transformer tap. Deriving the intermediate signal includes estimating, based on the monitoring signal, a phase of the monitored voltage to obtain a phase signal and applying to the phase signal a phase correction for a phase shift between the monitoring signal or a signal derived therefrom and the tap voltage at the transformer tap. The timing control signal is derived from the intermediate signal.

The invention discloses a magnetic flux coupling regulation type hybrid transformer and a control method thereof, and relates to the technical field of power distribution network voltage regulation equipment. The magnetic flux coupling regulation and control type hybrid transformer is composed of three three-column four-winding transformers and a voltage source type back-to-back converter. The three three-column four-winding transformers are the same in structure, and four windings are respectively an input winding, an output winding, an energy taking winding and a voltage regulating winding. The back-to-back converter is composed of a rectification unit, an inversion unit and a direct current capacitor. The rectification unit realizes stable control of DC voltage through controlling port current, and carries out reactive power and harmonic compensation on an input port of the hybrid transformer. And the inversion unit realizes flexible adjustment of the voltage of the output winding port of the hybrid transformer by controlling the output voltage of the inversion side. The method has the characteristic that the line fault current does not directly flow through the converter, and can reduce the voltage and current resistance level of a converter power device and the equipment protection difficulty, thereby reducing the cost of the hybrid transformer.

The invention discloses an isolated resonant converter and a control method thereof, and belongs to the technical field of electric energy conversion, and the method comprises the steps: comparing a primary side current i1 with a current reference value iref, carrying out PI adjustment, and adding the primary side current i1 with the current reference value iref to obtain a target current value it; comparing the external phase shift angle alpha with an external phase shift angle reference value alpha ref, and adding a feed-forward frequency fd after PI adjustment to obtain a switching frequency fs; and reactive current Irq and active current Irp of the primary side of the resonant cavity are calculated, a voltage phase difference phi and an internal phase shift angle theta are calculated according to the target current value it and the switching frequency fs, and a switch of the isolated resonant converter is driven according to the voltage phase difference phi, the internal phase shift angle theta, the external phase shift angle alpha and the switching frequency fs. According to the isolated resonant converter and the control method thereof, accurate control of transmission power and zero-voltage switching-on of all switches can be realized, and the efficiency of the converter is remarkably improved.

The invention discloses a topological structure of a single-phase isolation type integrated vehicle-mounted charging system without an electrolytic capacitor and a control method of the topological structure, the system multiplexes a driving motor stator winding on the basis of an open winding driving system of an electric vehicle, and when the system is switched from a driving operation mode to a charging operation mode, the driving motor stator winding is switched to the charging operation mode. An open winding permanent magnet motor driving system is reconstructed into an isolated AC / DC converter without an electrolytic capacitor through a change-over switch, the isolated AC / DC converter comprises a synchronous rectifier, a dual-active-bridge converter and an active filtering device, phase shifting is controlled through matching of transmission power and network side input power, power factor correction is achieved, and power factor correction is achieved through winding inductive current control. According to the vehicle-mounted power battery integrated vehicle-mounted charging system, the inherent secondary power pulsation is filtered out to realize active filtering, and the torque pulsation suppression of a multiplexing motor winding is realized through a magnetic flux balance method, so that the vehicle-mounted power battery integrated vehicle-mounted charging system with an isolation charging characteristic is obtained, the integrated design of a driving charging function is realized, and the reliability and the safety of the integrated charging system are improved.

An AC-to-AC converter includes input terminals for connection to an AC source, output terminals for connection to a load, a transformer having a primary winding and a secondary winding, a primary-side switch, a pair of secondary-side switches, and a control circuit to control the switches. Closing the primary-side switch causes a primary current to be drawn from the AC source and through the primary winding to store energy in the transformer. Closing one of the secondary-side switches causes a secondary current to be output at the output terminals to transfer energy from the transformer to the load. The secondary current has the same polarity as the primary current when a first of the secondary-side switches is closed, and the opposite polarity when a second of the secondary-side switches is closed. The control circuit is operable to control the switches such that an alternating current is output at the output terminals.

The present application provides an on-board charger and a control method thereof. Since the transformer side of the AC / AC conversion circuit is connected to the AC side of the AC / DC conversion circuit via a transformer, the on-board charger has a single-stage structure. Furthermore, since the instantaneous sampling value of the grid-side current is equal to its instantaneous reference value when stable, and the instantaneous reference value of the grid-side current is determined by the phase of the instantaneous sampling value of the grid-side voltage and the reference peak value of the grid-side current, the on-board charger has a PFC function. Furthermore, since the battery-side charging power can be indirectly controlled by controlling the grid-side current, the on-board charger has a battery-side voltage and current control function. Furthermore, since phase shift control is performed on the two conversion circuits, and the phase shift control enables soft switching of the power devices in the two conversion circuits, and the single-stage structure reduces the current flowing through the devices, efficiency is improved. Therefore, the single-stage structure efficiently implements the PFC and battery-side voltage and current control functions of the two-stage isolated on-board charger.