AC / DC bidirectional conversion circuit

Abstract

The utility model provides an AC / DC bidirectional conversion circuit, and the circuit comprises a DC side / AC side interface which is used for inputting DC / AC when serving as an input end, and outputting DC / AC when serving as an output end; the modulation driving module is connected between the direct current side interface and the alternating current side interface and is used for controlling an output current signal; the bidirectional conversion module is connected between the direct-current side interface and the alternating-current side interface, enables a circuit to work in an inversion state or a rectification state according to an input current signal under the control of the modulation driving module, and comprises a first full bridge and a second full bridge which share the same half-bridge structure; and the modulation driving module is connected with the alternating current side interface through the half-bridge structure, so that when the circuit works in an inversion / rectification state, a full-bridge inversion / rectification circuit is formed based on the first / second full bridge in the bidirectional conversion module. According to the circuit provided by the invention, a half-bridge structure is shared in the rectification and inversion processes, so that the number of power switch devices can be reduced, and the overall cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of circuit, especially, relate to rectification and inverter technology. BACKGROUND

[0002] With the increasing demand for energy and the growing emphasis on environmental protection, efficient and reliable energy conversion technology has become an important direction of today's scientific and technological development. In the field of power electronics, rectifier-inverter bidirectional converter as a kind of key equipment, can realize the efficient conversion between alternating current and direct current, plays an important role in many application scenarios.

[0003] For example, in the field of renewable energy, with the widespread application of solar energy, wind energy and other renewable energy, efficient bidirectional converter is needed to realize energy storage and feedback. For example, in photovoltaic power generation system, when the solar energy is sufficient, bidirectional converter can convert direct current into alternating current and enter the grid; while at night or insufficient light, it can get alternating current from the grid and convert it into direct current to charge the energy storage device.

[0004] In the microgrid system, since the microgrid is a small power system composed of distributed power supply, energy storage device, energy conversion equipment, load and other components, bidirectional converter can realize energy coordination and management between different power sources in the microgrid, improve the stability and reliability of the microgrid.

[0005] In the field of electric vehicles, the rapid development of electric vehicles puts forward higher requirements for charging technology. Bidirectional converter can realize the bidirectional flow of energy between electric vehicles and power grid, which can convert alternating current into direct current to charge the battery when charging, and can convert the direct current of the battery into alternating current to feed back to the grid when the vehicle brakes or descends, improving energy utilization efficiency.

[0006] Traditional rectifiers and inverters are usually independent devices, respectively used to convert alternating current into direct current (rectification) and direct current into alternating current (inversion). This one-way conversion method has limitations in many applications and cannot meet the needs of some scenes that require bidirectional energy flow.

[0007] Most of the rectifier-inverter bidirectional converters on the market adopt a large number of electronic devices in order to realize complex functions and meet different performance requirements. This not only increases the cost and size of the device, but also reduces the reliability of the system. Too many devices will lead to complex circuit layout, increasing the difficulty of design and debugging.

[0008] In addition, due to design defects, in the existing bidirectional converter, part of the devices may be in idle state for a long time in a specific working mode, and the vacancy rate is high. For example, in some working states, part of the power devices may only bear a small current or voltage, or even be in a state of not working, resulting in low utilization rate. This not only increases the cost of the system, wastes resources, but also may reduce the overall efficiency of the system. High vacancy rate may also cause heat dissipation problems of the system, increasing the maintenance cost of the equipment.

[0009] Therefore, it has important practical significance and broad market prospects to design a rectifying and inverting bidirectional converter with high efficiency, compactness and reliability. Content of the utility model

[0010] In order to solve at least one problem existing in the prior art, the utility model provides a bidirectional AC-DC conversion circuit, comprising:

[0011] The DC side interface is used for inputting DC power when serving as an input end, and is used for outputting DC power when serving as an output end.

[0012] The AC side interface is used for inputting AC power when serving as an input end, and is used for outputting AC power when serving as an output end.

[0013] The modulation driving module connected between the DC side interface and the AC side interface is used for controlling the output current signal.

[0014] The bidirectional conversion module connected between the DC side interface and the AC side interface makes the circuit work in an inverting state or a rectifying state according to the input current signal and under the control of the modulation driving module, and the bidirectional conversion module comprises a first full bridge and a second full bridge.

[0015] The first full bridge and the second full bridge share the same half bridge structure, and the modulation driving module is connected with the AC side interface through the half bridge structure, so that:

[0016] When the circuit works in the inverting state, the first full bridge in the bidirectional conversion module constitutes a full bridge inverter circuit; and when the circuit works in the rectifying state, the second full bridge in the bidirectional conversion module constitutes a full bridge rectifier circuit.

[0017] The bidirectional AC-DC conversion circuit provided by the utility model realizes bidirectional energy flow, and the devices are repeatedly used in the process of rectification and inversion, thereby reducing the number of devices in the circuit and reducing the system power consumption. Compared with the case that different devices are used for rectification and inversion in the prior art, the utility model greatly improves the utilization rate of the devices and reduces the vacancy rate of the devices. Therefore, the bidirectional converter provided by the utility model has the advantages of small size and low cost.

[0018] In some embodiments of the utility model, the first full bridge includes a first half bridge and a second half bridge, the second full bridge includes the second half bridge and a third half bridge, wherein the series structure of the second half bridge and the modulation driving module, the first half bridge and the third half bridge are connected in parallel between the DC side interface and the AC side interface.

[0019] In the above-mentioned embodiments, the first half bridge includes a first switch device and a second switch device, the second half bridge includes a third switch device and a fourth switch device, and the third half bridge includes a fifth switch device and a sixth switch device; the first switch device and the fourth switch device are connected in series, the second switch device and the third switch device are connected in series, the first switch device and the second switch device are connected in parallel, and the third switch device and the fourth switch device are connected in parallel; the third switch device and the sixth switch device are connected in series, the fourth switch device and the fifth switch device are connected in series, and the fifth switch device and the sixth switch device are connected in parallel.

[0020] In some embodiments of the utility model, when the circuit works in the inverter state, the switch device in the third half bridge is in the off state; when the circuit works in the rectification state, the switch device in the first half bridge is in the off state.

[0021] In some embodiments of the utility model, the modulation control module is used for PWM modulation of the output voltage of the circuit according to the control signal input by the connected controller.

[0022] This embodiment can very accurately control the average voltage, current or power and other parameters of the output signal, and meet the fine adjustment requirements of parameters in different application scenarios.

[0023] In some embodiments of the utility model, the modulation driving module is a Buck / Boost circuit structure.

[0024] This embodiment can stabilize the output voltage within a certain range in the case of unstable input voltage, such as solar panels, batteries, etc. Even if the input voltage fluctuates, the output voltage can be kept relatively stable by adjusting the PWM duty cycle.

[0025] In some embodiments of the utility model, the modulation driving module includes an energy storage element, a first frequency control device and a second frequency control device, the first frequency control device and the second frequency control device are connected in parallel, the energy storage element and the parallel first frequency control device and second frequency control device are connected in series between the DC side interface and the common half bridge structure, and the energy storage element is connected with the AC side interface through the common half bridge structure.

[0026] In the above-mentioned embodiments, the energy storage element is an inductor.

[0027] In some embodiments of the utility model, the circuit further includes a voltage stabilizing module connected in parallel on both sides of the DC end or both sides of the AC end.

[0028] Further, the voltage stabilizing module is a capacitor element.

[0029] In some embodiments of the utility model, the first frequency control device is a MOSFET, the second frequency control device, the fifth switch device and the sixth switch device are diodes, the first switch device and the second switch device are IGBTs, the third switch device and the fourth switch device are blocking IGBT / SCR / IGBT series diodes, or the first switch device and the second switch device are MOSFETs, and the third switch device and the fourth switch device are MOSFET series diodes.

[0030] The AC-DC bidirectional conversion circuit provided by the utility model realizes bidirectional energy flow, and the number of devices in the circuit is reduced and the system power consumption is lowered due to repeated use of some devices in the rectification and inversion processes. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a structural schematic view of the AC-DC bidirectional conversion circuit provided by an embodiment of the utility model.

[0032] Figure 2 is a structural schematic view of the bidirectional conversion module in the AC-DC bidirectional conversion circuit of Figure 1

[0033] Figure 3 is a circuit connection diagram of the AC-DC bidirectional conversion circuit with the bidirectional conversion module in Figure 2

[0034] Figure 4 is a circuit structural schematic view of the AC-DC bidirectional conversion circuit provided by an embodiment of the utility model.

[0035] Figures 5a-5d is a circuit principle schematic view of the AC-DC bidirectional conversion circuit in an inversion state provided by an embodiment of the utility model.

[0036] Figures 6a-6d is a circuit principle schematic view of the AC-DC bidirectional conversion circuit in a rectification state provided by an embodiment of the utility model.

[0037] Figure 7 ​​It is the circuit specific schematic view of the AC-DC bidirectional conversion circuit provided by an embodiment of the utility model.

[0038] Figure 8 It is the circuit specific schematic view of the AC-DC bidirectional conversion circuit provided by another embodiment of the utility model.

[0039] Figure 9 It is the circuit specific schematic view of the AC-DC bidirectional conversion circuit provided by still another embodiment of the utility model.

[0040] Figure 10 It is the circuit specific schematic view of the AC-DC bidirectional conversion circuit provided by still another embodiment of the utility model. Specific embodiments

[0041] In order to make the purpose, technical scheme and advantages of the utility model more clear, the utility model will be further explained in detail below by combining with the drawings and specific embodiments. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the utility model can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to facilitate a more thorough understanding of the utility model and to convey the complete concept of the utility model to those skilled in the art.

[0042] Reference Figure 1 , a structure schematic view of the AC-DC bidirectional conversion circuit provided by an embodiment of the utility model is shown. As Figure 1 The AC-DC bidirectional conversion circuit provided by the utility model mainly comprises a DC side interface 10, a modulation driving module 20, a bidirectional conversion module 30 and an AC side interface 40.

[0043] The DC side interface 10 is used for inputting DC power when serving as an input terminal, and is used for outputting DC power when serving as an output terminal. Similarly, the AC side interface 40 is used for inputting AC power when serving as an input terminal, and is used for outputting AC power when serving as an output terminal.

[0044] The modulation driving module 20 is connected between the DC side interface 10 and the AC side interface 40, and is used for controlling the output current signal. The modulation driving module 20 can also be used for controlling the output voltage signal and power signal according to requirements.

[0045] The bidirectional conversion module 30 is connected between the DC side interface 10 and the AC side interface 40, and comprises a first full bridge 31 and a second full bridge 32. Advantageously, the first full bridge 31 and the second full bridge 32 have the same half bridge, i.e., they share the same half bridge structure 300.

[0046] In addition, the modulation driving module 20 is connected with the AC side interface 40 through the half bridge structure 300.

[0047] The bidirectional conversion module 30 can make the circuit operate in an inverter state or a rectifier state according to the input current signal and under the control of the modulation drive module 20: when the circuit operates in the inverter state, the entire circuit constitutes a full-bridge inverter circuit based on the first full bridge 31 in the bidirectional conversion module 30; when the circuit operates in the rectifier state, the entire circuit constitutes a full-bridge rectifier circuit based on the second full bridge 32 in the bidirectional conversion module 30.

[0048] Therefore, the first full-bridge 31 and the second full-bridge 32 share the same half-bridge structure 300 , which means that they both use a set of hardware components, namely, a half-bridge, to implement their respective corresponding inversion or rectification functions.

[0049] Based on the above structure, the AC / DC bidirectional conversion circuit provided by the present invention realizes bidirectional energy flow while sharing a half-bridge structure in the rectification and inversion processes. Compared with designing corresponding modules or circuit structures for the inversion and rectification processes respectively and using different half-bridge structures in the corresponding modules, the shared half-bridge structure can reuse the switching devices in the inversion and rectification processes, saving the number of power switching devices and reducing the overall cost, thereby greatly improving the utilization rate of the devices and reducing the vacancy rate of the devices. At the same time, it can also reduce the space occupied by the circuit board, making the system more compact. Therefore, the bidirectional converter provided by the present application has the advantages of low cost and small size.

[0050] Furthermore, if Figure 2 As shown, it shows Figure 1 Specifically, the first full bridge 31 includes a first half-bridge 310 and a second half-bridge 300 , and the second full bridge 32 includes a second half-bridge 300 and a third half-bridge 320 . Figure 2 In the illustrated embodiment, the half-bridge structure shared by the first full bridge 31 and the second full bridge 32 is the second half-bridge 300 .

[0051] For example, Figure 3 Shown with Figure 2 The circuit connection diagram of the AC / DC bidirectional conversion circuit of the bidirectional conversion module in FIG. The series structure of the second half-bridge 300 and the modulation drive module 20 , the first half-bridge 310 , and the third half-bridge 320 are connected in parallel between the DC side interface 10 and the AC side interface 40 .

[0052] In other words, the two ends of the second half-bridge 300 are respectively connected to the AC side interface 40, and the middle node of the second half-bridge 300 is connected to the modulation drive module 20; the two ends of the first half-bridge 310 are respectively connected to the AC side interface 40, and the two ends of the third half-bridge 320 are also respectively connected to the AC side interface 40, and the middle node of the first half-bridge 310 and the middle node of the third half-bridge 320 are connected via the DC side interface 10.

[0053] Further exemplary, the first half bridge 310 can include a first switch device and a second switch device, the second half bridge 300 can include a third switch device and a fourth switch device, and the third half bridge 320 can include a fifth switch device and a sixth switch device. Wherein, the first switch device and the fourth switch device are connected in series, the second switch device and the third switch device are connected in series, the first switch device and the second switch device are connected in parallel, and the third switch device and the fourth switch device are connected in parallel; the third switch device and the sixth switch device are connected in series, the fourth switch device and the fifth switch device are connected in series, and the fifth switch device and the sixth switch device are connected in parallel. The specific structure can be referred to the circuit structure diagram below.

[0054] For the selection of each switch device in the circuit provided by the utility model, those skilled in the art can understand that the first, second, third and fourth switch devices in the utility model can be triodes, or alternatively MOS tubes. These switch devices can be the same type of switch device, for example, all MOS tubes or all triodes; alternatively, part of them can be MOS tubes and the other part can be triodes. Regardless of the type of each switch device, those skilled in the art can adapt the corresponding structure in the above-mentioned circuit according to the working principle of the corresponding switch device.

[0055] The AC-DC bidirectional conversion circuit provided by the above-mentioned embodiment, when the circuit works in the inverter state, the first full bridge 31, i.e. the first half bridge 310 and the second half bridge 300, works in the form of an inverter circuit, and the switch devices in the third half bridge 320 are in the off state; when the circuit works in the rectification state, the second full bridge 32, i.e. the second half bridge 300 and the third half bridge 320, works in the form of a rectification circuit, and the switch devices in the first half bridge 310 are in the off state. That is, the second half bridge participates in the work whether in the inverter state or in the rectification state.

[0056] Those skilled in the art can make corresponding settings on the specific structure of the first full bridge and the second full bridge according to actual needs. Those skilled in the art should understand that the first full bridge and the second full bridge can also correspondingly adopt other forms, as long as the same structure is shared by the "first full bridge" and the "second full bridge" during inverter and rectification. As for the structure shared by the first full bridge and the second full bridge, those skilled in the art can select the corresponding implementation mode according to actual needs and conditions. The present application will not make related description here.

[0057] Advantageously, the modulation control module 20 is used to perform PWM modulation on the output voltage of the circuit according to the control signal input by the connected controller. The advantage of PWM (Pulse Width Modulation) modulation is that it can effectively control whether the load is resistive, inductive or capacitive. And PWM can be applied to different types of motors, such as DC motors, AC motors, stepper motors, etc., to meet the motor control requirements in different application scenarios. At the same time, PWM signals can be easily generated by digital circuits, so PWM technology can be easily integrated with digital control systems to achieve intelligent control.

[0058] The controller in the above embodiments can be a combination logic controller, a single-chip microcomputer, a chip, a microcontroller (MCU), a programmable logic controller (PLC), a digital signal processor (DSP), an electronic control unit (ECU), a microprogrammed controller, a special-purpose controller, etc. Those skilled in the art can choose and use them according to the field and needs, which will not be described in detail herein.

[0059] Preferably, the modulation drive module 20 can be a Buck / Boost circuit structure. In particular, the BUCK function is used when converting power from the DC bus to the grid, and the BOOST function is used when converting from the grid to the DC bus. In fact, for the case of unstable input voltage, such as solar panels, batteries, etc., Buck / Boost circuit combined with PWM modulation can stabilize the output voltage within a certain range. Even if the input voltage fluctuates, the output voltage can be kept relatively stable by adjusting the PWM duty cycle. At the same time, it can also improve the power factor. By controlling the waveform of the input current to be closer to the waveform of the input voltage, it can reduce the reactive power and improve the overall efficiency of the system. In addition, through the feedback control mechanism, the output voltage can be monitored in real time, and the PWM duty cycle can be adjusted according to the feedback signal, so that the output voltage is always kept near the set value, thereby helping to improve the reliability and stability of the system.

[0060] Those skilled in the art should understand that there are many structures of modulation drive modules. The present application only exemplarily adopts one of the relatively simple ways, and the specific duty cycle setting, frequency control and implementation means can be set according to the specific requirements in actual application, which will not be described in detail herein.

[0061] Exemplarily, the modulation driving module 20 can comprise an energy storage element, a first frequency control device and a second frequency control device, for example. Specifically, the first frequency control device and the second frequency control device are connected in parallel, while the energy storage element is connected in series with the parallel structure of the first frequency control device and the second frequency control device between the DC side interface 10 and the shared half-bridge structure 300, and the energy storage element is connected with the AC side interface 40 through the shared half-bridge structure 300.

[0062] In particular, the energy storage element described above can be an inductor. The inductor has a hindering effect on the change of current and can smooth the fluctuation of current. In addition, the service life of the inductor is generally long and not easy to be damaged, so it can work stably for a long time under normal conditions and does not need to be replaced frequently.

[0063] Additionally, the circuit can further comprise a voltage stabilizing module connected in parallel on both sides of the DC end or both sides of the AC end. The voltage stabilizing module can be a capacitor element, for example.

[0064] Advantageously, the parallel connection of the energy storage capacitor at both ends of the conversion circuit suppresses the large voltage fluctuation caused by the discontinuity of the DC current. During the rectification process, the pulsed voltage after rectification is smoothed by utilizing the charging and discharging characteristics of the capacitor, so that a relatively stable DC voltage can be obtained.

[0065] Figure 4 The circuit structure schematic diagram of the AC-DC bidirectional conversion circuit provided by an embodiment of the present application is shown. The working principle of the circuit is shown in combination with Figures 5a-5d and Figures 6a-6d .

[0066] Figure 4 In the embodiment shown, the DC interface is a DC side interface, and the AC interface is an AC side interface. L1 is an energy storage element, S3 is a first frequency control device, S4 is a second frequency control device, and L1, S3 and S4 form a modulation driving module. The double-path selection switch S1 represents a first half-bridge, the double-path selection switch S2 represents a second half-bridge, and S5 and S6 together form a third half-bridge (S5 is a fifth switching device in the third half-bridge, and S6 is a sixth switching device in the third half-bridge). Among them, the left path in the double-path selection switch S1 represents the first switching device in the first half-bridge, and the right path represents the second switching device; the left path in the double-path selection switch S2 represents the third switching device in the second half-bridge, and the right path represents the fourth switching device. S1 and S2 form a first full-bridge, and S2, S5 and S6 form a second full-bridge.

[0067] When the circuit transmits energy from the DC side to the AC side to realize the inversion process:

[0068] As Figure 5a and 5bAs shown, in the positive half cycle of AC voltage, when the potential of L terminal is higher than that of N terminal, S1 is closed to L terminal, S2 is closed to N terminal, S5 and S6 are disconnected, S3 and S4 are high-frequency alternately switched, and the current of inductor L1 is modulated. The current path during high-frequency switching is shown by red dotted line in the figure.

[0069] When S3 is closed and S4 is disconnected, referring to Figure 5a , the current passes through S1 right path, AC interface L terminal, AC interface N terminal, S2 left path, L1, S3 in sequence from the positive terminal of DC power supply to the negative terminal. In this process, inductor L1 is in charging process, the current gradually increases, and the waveform corresponds to the first half of the positive half cycle of sine wave.

[0070] When S3 is disconnected and S4 is closed, referring to Figure 5b , inductor L1 acts as a power supply to discharge, and the current passes through S4, S1 right path, AC interface L terminal, AC interface N terminal, S2 left path in sequence to return to L1. In this process, the current gradually decreases, and the waveform corresponds to the second half of the positive half cycle of sine wave.

[0071] As shown in Figure 5c and 5d , in the negative half cycle of AC voltage, when the potential of L terminal is lower than that of N terminal, S1 is closed to N terminal, S2 is closed to L terminal, S5 and S6 are disconnected, S3 and S4 are high-frequency alternately switched, and the current of inductor L1 is modulated. The current path during high-frequency switching is shown by red dotted line in the figure.

[0072] When S3 is closed and S4 is disconnected, referring to Figure 5c , the current passes through S1 left path, AC interface N terminal, AC interface L terminal, S2 right path, L1, S3 in sequence from the positive terminal of DC power supply to the negative terminal. In this process, inductor L1 is in charging process, the current gradually increases, and the current direction at AC interface is opposite to that in Figure 5a , and the waveform corresponds to the first half of the negative half cycle of sine wave.

[0073] When S3 is disconnected and S4 is closed, referring to Figure 5d , inductor L1 acts as a power supply to discharge, and the current passes through S4, S1 left path, AC interface N terminal, AC interface L terminal, S2 right path in sequence to return to L1. In this process, the current gradually decreases, and the current direction at AC interface is opposite to that in Figure 5b , and the waveform corresponds to the second half of the negative half cycle of sine wave.

[0074] When the circuit transmits energy from AC side to DC side to realize rectification process:

[0075] As shown in Figure 6a and 6bAs shown in the figure, during the positive half cycle of the AC voltage, when the potential at the L terminal is higher than that at the N terminal, S1 opens, S2 closes to the L terminal, S5 closes, S6 opens, and S3 and S4 alternately switch at high frequency, modulating the current in inductor L1. The red dashed line in the figure shows the current path during high-frequency switching.

[0076] When S3 is closed and S4 is open, refer to Figure 6a The current flows from the positive pole of the AC power supply through the AC interface L terminal, the right path of S2, L1, S3, S5, and finally to the AC interface N terminal. During this process, the current output by the AC interface gradually increases, and the waveform corresponds to the first half of the positive half cycle of the sine wave.

[0077] When S3 is open and S4 is closed, refer to Figure 6b The current flows through the AC interface L, the right path of S2, L1, S4, the DC positive and negative interfaces, S5, and returns to the AC interface N. During this process, the current output by the AC interface gradually decreases, and the waveform corresponds to the second half of the positive half cycle of the sine wave.

[0078] like Figure 6c and 6d As shown in the figure, during the negative half-cycle of the AC voltage, when the potential at the L terminal is lower than that at the N terminal, S1 opens, S2 closes to the N terminal, S5 opens, S6 closes, and S3 and S4 alternately switch at high frequency, modulating the current in inductor L1. The red dashed line in the figure shows the current path during high-frequency switching.

[0079] When S3 is closed and S4 is open, refer to Figure 6c , the current passes through the AC interface N end, S2 left, L1, S3, S6 to the AC interface L end. In this process, the current gradually increases, and the direction of the current output by the AC interface is the same as Figure 6a The flow direction is opposite, and the waveform corresponds to the first half of the negative half cycle of the sine wave.

[0080] When S3 is open and S4 is closed, refer to Figure 6d , the current passes through the AC interface N end, S2 left, L1, S4, DC interface, S6, and returns to the AC interface L end. In this process, the current output by the AC interface gradually decreases, and the current direction at the AC interface is the same as Figure 6b The current flow direction at the DC interface is opposite to that at the negative half cycle of the sine wave. Figure 6b The flow direction is the same.

[0081] In practical applications, various types of power semiconductor devices can be used as control switches. The specific configuration schemes are as follows:

[0082] Figures 7-10 Different embodiments of the AC / DC bidirectional conversion circuit provided by the present utility model are shown.

[0083] Reference Figure 7 IGBT (Q1~Q4) are selected in the first full bridge S1 and the second full bridge S2, wherein Q3 and Q4 in the second half bridge must be inverse resistance type IGBT, MOSFET (Q5) is selected for the first frequency control device S3, and diodes (D1~D3) are selected for the second frequency control device S4 and the third half bridge S5, S6.

[0084] Reference Figure 8 IGBT (Q1, Q2) is selected for the first full bridge S1, IGBT in series with diode (Q3, D4; Q4, D5) is selected for the second full bridge S2, MOSFET (Q5) is selected for the first frequency control device S3, and diodes (D1~D3) are selected for the second frequency control device S4 and the third half bridge S5, S6.

[0085] Reference Figure 9 MOSFET (Q1, Q2) is selected for the first full bridge S1, MOSFET in series with diode (Q3, D4; Q4, D5) is selected for the second full bridge S2, MOSFET (Q5) is selected for the first frequency control device S3, and diodes (D1~D3) are selected for the second frequency control device S4 and the third half bridge S5, S6.

[0086] Reference Figure 10 IGBT (Q1, Q2) is selected for the first full bridge S1, SCR (Q3, Q4) is selected for the second full bridge S2, MOSFET (Q5) is selected for the first frequency control device S3, and diodes (D1~D3) are selected for the second frequency control device S4 and the third half bridge S5, S6.

[0087] In addition, in the field of application related to the commercial power, the first full bridge S1 and the second full bridge S2 can be switched according to the polarity direction of the commercial power, so that the switching frequency is the same as the frequency of the alternating current, which is generally 50Hz or 60Hz; the first frequency control device S3 is modulated by SPWM according to the phase of the commercial power, and the switching frequency is determined according to the bearing capacity of the specific switching device and the actual working temperature rise, if the MOSFET is selected for S3, the switching frequency is generally 50~100kHz.

[0088] By setting the DC interface input DC voltage to be at least higher than the instantaneous peak voltage of the alternating current, for example, the alternating voltage is 220V (AC), the input DC voltage should be no less than 310V (DC), if the maximum duty ratio of S3 is set to 0.9, it can be concluded that the DC input voltage is about 345V, so the AC / DC bidirectional conversion circuit provided by the application can not need a transformer.

[0089] It should be noted that for the switching device, those skilled in the art can understand that for the NPN type transistor, the current flowing through the collector (c), base (b), and emitter (e) is: Ie = Ib + Ic, Ic = β * Ib. When Ube > 0.7V, that is, the emitter junction voltage Ube is forward biased, the transistor is turned on. When Ube < 0.7V, that is, the emitter junction voltage Ube is reverse biased, the transistor is in the off state, which is equivalent to the switch being turned off. Among them, the transistor turn-on voltage and other parameters are determined by the specific device selected. Correspondingly, the parameters of each voltage dividing circuit are also selected according to the specification requirements of the device, which is the common sense of those skilled in the art and will not be repeated. Similarly, for the PNP type transistor, when Ube < -0.7V, the transistor is turned on. When Ube > -0.7V, the transistor is turned off. Similarly, the specific circuit parameters need to be determined according to the specification requirements of the selected transistor.

[0090] Those skilled in the art should understand that: the MOS tube needs to meet the condition that |Vg-Vs|>|Vgs(TH)| to be turned on. Specifically, for the NMOS tube, Vg-Vs>Vgs(TH), Vgs(TH) is the threshold voltage of the MOS tube, that is, the voltage difference between the G pole (gate) and the S pole (source) is greater than a certain value, and the MOS tube will be turned on, but the voltage difference cannot be too large, otherwise the MOS tube will be burned out. Among them, the opening voltage and other parameters need to be selected according to the specification of the specific device. Similarly, for the PMOS tube, Vg-Vs<Vgs(TH), that is, the voltage difference between the G pole and the S pole is less than a certain value, and the MOS tube will be turned on (for the PMOS tube, Vgs(TH) is negative). Similarly, the specific parameters need to be referred to the specification of the specific device.

[0091] Those skilled in the art should understand that the specific parameters of the circuit device of the utility model can be adjusted according to the actual situation. Diodes and transistors can also be replaced by other components that can achieve the same function.

[0092] In summary, the utility model provides a kind of AC-DC bidirectional conversion circuit, while realizing the energy bidirectional flow, since half bridge structure is shared in the process of rectification and inversion, compared with the corresponding module or circuit structure is designed for the two processes of inversion and rectification respectively and different half bridge structures are used in the corresponding module, shared half bridge structure can be reused in the two processes of inversion and rectification for switching device, save the number of power switching device, reduce overall cost, thereby greatly improve the utilization rate of device, reduce the vacancy rate of device. At the same time, it can also reduce the occupation of circuit board space, make the system more compact. Therefore, the bidirectional converter provided by the present application has the advantages of low cost, small size and the like.

[0093] It should be noted that the hardware circuit provided by the embodiments of the present application can solve the technical problems existing in the prior art, and does not limit the software design that may be involved. Those skilled in the art can design software according to the hardware circuit provided by the present application to achieve the required function.

[0094] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "an embodiment", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0095] In the present application, the terms "connected", "connected", and the like should be understood in a broad sense, for example, "connected" can be fixedly connected, or detachably connected, or integrally connected; "connected" can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. An AC / DC bidirectional conversion circuit, characterized in that: The circuit comprises: a direct current side interface for inputting direct current when serving as an input terminal and for outputting direct current when serving as an output terminal; an alternating current side interface for inputting alternating current when serving as an input terminal and for outputting alternating current when serving as an output terminal; a modulation driving module connected between the direct current side interface and the alternating current side interface, for controlling an output current signal; a bidirectional conversion module connected between the direct current side interface and the alternating current side interface, for operating the circuit in an inverting state or a rectifying state according to the input current signal and under the control of the modulation driving module, the bidirectional conversion module comprising a first full bridge and a second full bridge, wherein the first full bridge and the second full bridge share a same half bridge structure, and the modulation driving module is connected to the alternating current side interface through the half bridge structure, so that: when the circuit operates in the inverting state, a full bridge inverting circuit is formed based on the first full bridge in the bidirectional conversion module; and when the circuit operates in the rectifying state, a full bridge rectifying circuit is formed based on the second full bridge in the bidirectional conversion module.

2. The AC-DC bidirectional conversion circuit according to claim 1, characterized by, The first full bridge comprises a first half bridge and a second half bridge, and the second full bridge comprises a second half bridge and a third half bridge, wherein the second half bridge and the modulation driving module are connected in series, the first half bridge and the third half bridge are connected in parallel between the direct current side interface and the alternating current side interface.

3. The AC-DC bidirectional conversion circuit according to claim 2, characterized by, The first half bridge comprises a first switching device and a second switching device, the second half bridge comprises a third switching device and a fourth switching device, and the third half bridge comprises a fifth switching device and a sixth switching device, wherein the first switching device and the fourth switching device are connected in series, the second switching device and the third switching device are connected in series, the first switching device and the second switching device are connected in parallel, and the third switching device and the fourth switching device are connected in parallel; the third switching device and the sixth switching device are connected in series, the fourth switching device and the fifth switching device are connected in series, and the fifth switching device and the sixth switching device are connected in parallel.

4. The AC-DC bidirectional conversion circuit according to claim 2, characterized by, When the circuit operates in the inverting state, the switching devices in the third half bridge are in an off state; and when the circuit operates in the rectifying state, the switching devices in the first half bridge are in the off state.

5. The AC-DC bidirectional conversion circuit according to claim 1, wherein The modulation control module is configured to perform PWM modulation on an output voltage of the circuit according to a control signal input by a connected controller.

6. The AC-DC bidirectional conversion circuit according to claim 1, wherein The modulation driving module is a Buck / Boost circuit structure.

7. The AC-DC bidirectional conversion circuit according to claim 3, wherein The modulation driving module comprises an energy storage element, a first frequency control device and a second frequency control device, the first frequency control device and the second frequency control device are connected in parallel, the energy storage element is connected in series with the first frequency control device and the second frequency control device connected in parallel between the direct current side interface and the shared half bridge structure, and the energy storage element is connected to the alternating current side interface through the shared half bridge structure.

8. The AC-DC bidirectional conversion circuit according to claim 7, wherein The energy storage element is an inductor.

9. The AC-DC bidirectional conversion circuit according to claim 1, wherein The circuit further comprises a voltage stabilizing module connected in parallel on both sides of the direct current terminal or both sides of the alternating current terminal.

10. The AC-DC bidirectional conversion circuit according to claim 9, wherein The voltage stabilizing module is a capacitor element.

11. The AC-DC bidirectional conversion circuit according to claim 7, wherein The first frequency control device is a MOSFET, the second frequency control device, the fifth switching device and the sixth switching device are diodes, the first switching device and the second switching device are IGBTs, the third switching device and the fourth switching device are reverse blocking IGBTs / SCRs / IGBT series diodes, and / or ​ The first and second switching devices are MOSFETs, and the third and fourth switching devices are MOSFETs in series with diodes.

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