Power conversion circuit and power supply system

Abstract

The invention relates to the technical field of electronic power transmission, and provides a power conversion circuit and a power supply system, and the power conversion circuit comprises a transformer which comprises a primary coil and a secondary coil; the primary side interface is used for accessing excitation current; the transformer is configured in the mode that when excitation current is connected to the primary side coil, the secondary side coil generates initial induction current; the secondary side interface is used for outputting induced current; the control unit is connected with the primary coil and the primary interface; the control unit is configured to control the primary side coil to access the excitation current from the primary side interface based on the first control signal; the output unit is connected with a secondary interface of the secondary coil; the output unit is configured to output induced current to the secondary side interface according to the initial induced current, and the induced current is continuous current; the embodiment of the invention is used for reducing the ripple of the output current of the power factor correction circuit (PFC).

Description

Technical Field

[0001] The present invention relates to the field of electronic power technology, and in particular to a power conversion circuit and a power supply system. Background Art

[0002] For high-power charging equipment, regulations have high requirements on the input harmonics of the charging equipment. In order to suppress current harmonics, a power factor correction (PFC) module is usually added to the charging line to perform power factor correction.

[0003] At present, most charging devices on the market use Boost converters for power factor correction, but Boost converters can only increase voltage, and their output voltage is limited by the input voltage; therefore, a DC / DC converter is usually added after the Boost converter for voltage regulation. However, such a two-stage architecture requires many devices, high cost, low energy efficiency and large energy waste.

[0004] With the development of new energy vehicles, high-power charging piles are becoming more and more popular, and people's performance requirements for charging piles are also increasing. Summary of the invention

[0005] The present invention provides a power conversion circuit and a power supply system to reduce the ripple of the output current of a power factor correction circuit (PFC).

[0006] In a first aspect, the present invention provides a power conversion circuit, comprising: a transformer, comprising a primary coil and a secondary coil; a primary interface for connecting an excitation current; the transformer is configured so that when the primary coil is connected to the excitation current, the secondary coil generates an initial induced current; the secondary interface is used to output the induced current; a control unit connected to the primary coil and the primary interface; the control unit is configured to control the primary coil to connect the excitation current from the primary interface based on a first control signal; an output unit connected to the secondary coil and the secondary interface; the output unit is configured to output the induced current to the secondary interface according to the initial induced current, and the induced current is a continuous current.

[0007] In some embodiments, the output unit includes: a conversion capacitor, wherein the first end of the conversion capacitor is connected to the first end of the secondary coil; a conversion inductor, wherein the first end of the conversion inductor is connected to the second end of the conversion capacitor; a current cutoff unit, wherein the input end of the current cutoff unit is connected to the second end of the secondary coil and forms a secondary interface with the second end of the conversion inductor, and the output end of the current cutoff unit is connected to the second end of the conversion capacitor; the current cutoff unit is configured to conduct the branch where the current cutoff unit is located based on a preset conduction direction.

[0008] In some embodiments, the control unit includes a control switch, which is arranged in series with the first end and / or the second end of the primary coil; the control switch is configured to turn on the branch where the primary coil is located based on the first control signal.

[0009] In some embodiments, the primary side interface is used to connect to a power supply, and the secondary side interface is used to connect to a load. The power conversion circuit also includes: an input energy storage capacitor, connected to the primary side interface and arranged in parallel with the power supply; an output energy storage capacitor, connected to the secondary side interface and arranged in parallel with the load.

[0010] In some embodiments, the output energy storage capacitor is configured based on an electrolytic capacitor.

[0011] In some embodiments, the power conversion circuit further includes: a feedback loop configured to adjust a duty cycle of the first control signal based on a comparison result of an output parameter of the secondary side interface and a preset parameter.

[0012] In some embodiments, the feedback loop includes: a first detection unit, configured to obtain the output parameter of the secondary side interface; a comparison unit, configured to generate a parameter adjustment value based on the comparison result between the output parameter of the secondary side interface and the preset parameter; and a processing unit, configured to adjust the duty cycle of the first control signal based on the parameter adjustment value.

[0013] In some embodiments, the feedback loop also includes: a second detection unit, configured to obtain the output parameter of the secondary coil; a judgment unit, configured to judge whether the output parameter of the secondary coil is a valley value, and if the output parameter is a valley value, providing a trigger signal; and the processing unit is configured to provide a first control signal based on the trigger signal.

[0014] In a second aspect, the present invention provides a power supply system, which is used for a power supply to supply power to a load. The power supply system includes a power conversion circuit as in the first aspect, wherein a primary side interface of the power conversion circuit is connected to a power supply, and a secondary side interface is connected to a load.

[0015] In some embodiments, the power supply system includes multiple power conversion circuits, the primary side interfaces of the multiple power conversion circuits are arranged in parallel and connected to the power supply, and the secondary side interfaces of the multiple power conversion circuits are arranged in parallel and connected to the load.

[0016] For the power conversion circuit provided in this embodiment, an output unit is set in the secondary side circuit of the transformer so that the secondary side of the transformer can output a continuous output signal under the intermittent input signal of the primary side of the transformer, thereby reducing the ripple of the secondary side circuit of the transformer.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic diagram of the structure of a power conversion circuit provided by an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of a specific structure of a power conversion circuit provided by an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of the specific structure of another power conversion circuit provided by an embodiment of the present invention;

[0022] Figure 4 A schematic diagram of the working timing of the power conversion circuit provided by an embodiment of the present invention;

[0023] Figure 5 A schematic structural diagram of a power conversion circuit of a feedback loop provided by an embodiment of the present invention;

[0024] Figure 6 A schematic structural diagram of another power conversion circuit of a feedback loop provided by an embodiment of the present invention;

[0025] Figure 7 A schematic diagram of the working timing of the power conversion circuit in the critical conduction mode provided by an embodiment of the present invention;

[0026] Figure 8 A schematic diagram of the structure of a power supply system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0028] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] In the present invention, the word "exemplary" is used to mean "used as an example, illustration or description". Any embodiment described as "exemplary" in the present invention is not necessarily to be construed as being preferred or advantageous over other embodiments. The following description is given to enable any technician in the field to implement and use the present invention. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present invention can be implemented without using these specific details. In other examples, well-known structures and processes will not be elaborated in detail to avoid obscuring the description of the present invention with unnecessary details. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features invented by the present invention.

[0030] At the same time, the present invention uses specific words to describe the embodiments of the present invention. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present invention. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of the present invention can be appropriately combined.

[0031] Similarly, it should be noted that in order to simplify the description of the disclosure of the present invention and thus facilitate the understanding of one or more application embodiments, in the above description of the embodiments of the present invention, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the subject matter of the present invention requires more features than those mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0032] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, numerical parameters should consider specifying significant digits and adopting a general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of the range in some embodiments of the present invention are approximate values, in specific embodiments, such numerical values ​​are set as accurately as possible within the feasible range.

[0033] Each patent, patent application, patent application invention and other materials, such as articles, books, specifications, publications, documents, etc., cited in this invention are hereby incorporated by reference in their entirety, except for application history documents that are inconsistent with or conflicting with the present invention, and documents that limit the broadest scope of the claims of this invention (currently or later attached to this invention). It should be noted that if the descriptions, definitions, and / or use of terms in the accompanying materials of this invention are inconsistent or conflicting with the examples of this invention, the descriptions, definitions, and / or use of terms in this invention shall prevail.

[0034] An embodiment of the present invention provides a power conversion circuit to reduce the ripple of the output current of a power factor correction circuit (PFC). The power conversion circuit provided by the embodiment is described in detail below with reference to the accompanying drawings.

[0035] refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a power conversion circuit provided in this embodiment. The power conversion circuit 100 includes: a transformer, a control unit 200 and an output unit 300.

[0036] The transformer includes a primary coil W1 and a secondary coil W2 , and the primary coil W1 and the secondary coil W2 are coupled to each other.

[0037] It should be noted that in Figure 1 In the example diagram shown, the primary coil W1 and the secondary coil W2 are coupled with the same name, which does not constitute a limitation of the present embodiment; those skilled in the art can adjust the specific connection structure of the corresponding circuit based on the difference between the same name coupling and the opposite name coupling in the transformer to obtain an embodiment suitable for the opposite name coupling of the primary coil W1 and the secondary coil W2.

[0038] The primary interface A of the power conversion circuit 100 is used to connect the excitation current. The transformer is configured so that when the primary coil W1 is connected to the excitation current, the secondary coil W2 generates an initial induced current. The secondary interface B of the power conversion circuit 100 is used to output the induced current.

[0039] Specifically, the excitation current connected to the primary interface A generates a magnetic field when passing through the primary coil W1 of the transformer. The secondary coil W2 generates an initial induced current based on the magnetic field generated by the primary coil W1. The output unit 300 adjusts the initial induced current and outputs the induced current. The induced current is output at the secondary interface B.

[0040] The control unit 200 is connected to the primary coil W1 and the primary interface A. The control unit 200 is configured to control the primary coil W1 to access the excitation current from the primary interface A based on the first control signal.

[0041] It can be seen from the description of the control unit 200 that the function of the control unit 200 can be regarded as a "switch". When the "switch" is started, the excitation current can flow through the primary coil W1 of the transformer; when the "switch" is not started, the excitation current cannot flow through the primary coil W1 of the transformer.

[0042] The output unit 300 is connected to the secondary coil W2 and the secondary interface B. The output unit 300 is configured to output an induced current to the secondary interface B according to the initial induced current, and the induced current is a continuous current.

[0043] Specifically, when the excitation current passes through the primary coil W1 intermittently, the magnetic field generated by the primary coil W1 is also intermittent, and the secondary coil W2 generates a discontinuous initial induced current according to the intermittent magnetic field; the purpose of setting the output unit 300 is to make the initial induced current continuous, so that the secondary coil outputs a continuous induced current.

[0044] For the power conversion circuit 100 provided in this embodiment, an output unit is set in the secondary side circuit of the transformer so that the secondary side of the transformer can output a continuous output signal under the intermittent input signal of the primary side of the transformer, thereby reducing the ripple of the secondary side circuit of the transformer.

[0045] Combination Figure 1 And refer to Figure 2 and Figure 3 , Figure 2 and Figure 3 A schematic diagram of the specific structure of the power conversion circuit provided for the present embodiment. In some embodiments, the primary interface A is used to connect a power supply. In one example, the power supply includes an AC power supply Vin and a rectifier module, and the primary interface A is connected to the output end of the rectifier module; wherein the rectifier module is used to rectify the AC power output by the AC power supply Vin to output DC power, and the DC power output by the rectifier module is the excitation current required to be connected to the primary interface A. Specifically, the rectifier module can be implemented based on a rectifier bridge; wherein the rectifier bridge includes but is not limited to a full-bridge circuit or a half-bridge circuit, etc. In another example, the power supply can be directly set based on a DC power supply, and the primary interface A is connected to the output end of the DC power supply, and the DC power of the DC power supply is the excitation current required to be connected to the primary interface A.

[0046] In some embodiments, the power conversion circuit 100 further includes an input energy storage capacitor Cin; wherein, if the power supply is based on a DC power supply, the input energy storage capacitor Cin is connected to the primary side interface A and is arranged in parallel with the DC power supply; if the power supply is based on an AC power supply and a rectifier module, the input energy storage capacitor Cin is arranged at the output end of the rectifier module. The input energy storage capacitor Cin is used for input filtering to reduce the voltage ripple of the input voltage.

[0047] In some embodiments, the control unit 200 includes a control switch, which is arranged in series at the first end and / or the second end of the primary coil W1; the control switch is configured to turn on the branch where the primary coil W1 is located based on the first control signal. It should be noted that for the first control signal described in this example, the first control signal is controlled and sent by the controller of the device where the power conversion circuit 100 is located.

[0048] Specifically, when the control switch is turned on, the power supply, the primary coil W1 and the control switch form a path, and the excitation current provided by the power supply passes through the primary coil W1, so that the primary coil W1 generates a magnetic field. When the control switch is turned off, the power supply, the primary coil W1 and the control switch cannot form a path, and the excitation current provided by the power supply cannot pass through the primary coil W1.

[0049] Specifically, when the control switch is turned off, the power supply and the primary coil W1 form a path, and the excitation current provided by the power supply passes through the primary coil W1, so that the primary coil W1 generates a magnetic field. When the control switch is turned on, the power supply and the control switch form a path, and the excitation current provided by the power supply cannot pass through the primary coil W1.

[0050] In some embodiments, the control switch is set based on the first MOS transistor Q1, wherein the gate of the first MOS transistor Q1 is used to receive the first control signal. Figure 2 and Figure 3 The control switch is controlled by taking the first MOS tube Q1 interface as an example, which does not constitute a limitation on this embodiment. In other embodiments, the control switch may also be directly set based on a switch or a switch structure such as a relay.

[0051] In some embodiments, the output unit 300 includes a conversion capacitor C1, a conversion inductor L1, and a current cutoff unit. The first end of the conversion capacitor C1 is connected to the first end of the secondary coil W2; the first end of the conversion inductor L1 is connected to the second end of the conversion capacitor C1; the input end of the current cutoff unit is connected to the second end of the secondary coil W2 and forms a secondary interface B with the second end of the conversion inductor L1, and the output end is connected to the second end of the conversion capacitor C1; the current cutoff unit is configured to conduct the branch where the current cutoff unit is located based on a preset conduction direction.

[0052] Specifically, the purpose of setting the current intercepting unit is to prevent the current from flowing in one direction from the input end to the output end. Figure 2 The current interception unit can be directly set based on the diode D, and the diode can directly ensure the unidirectional flow of current from the input end to the output end. In other embodiments, specific reference is made to Figure 3, the current interception unit can be directly set based on the second MOS tube Q2, and the gate of the second MOS tube Q2 is used to receive the second control signal to ensure the unidirectional flow of current by opening and closing the circuit branch. Specifically, when a current with a preset conduction direction needs to pass, the second MOS tube Q2 is controlled to be turned on by the second control signal; when a current with no preset conduction direction needs to pass, the second MOS tube Q2 is controlled to be turned off by the second control signal. It should be noted that for the second control signal described in this embodiment, the second control signal is controlled and sent by the controller of the device where the power conversion circuit 100 is located.

[0053] In some embodiments, the secondary side interface B of the power conversion circuit 100 is used to connect to a load Ro so as to supply the electric energy provided by the power supply to the load Ro, so as to complete the power supply to the load Ro.

[0054] In some embodiments, the power conversion circuit 100 further includes an output energy storage capacitor Co, which is connected to the secondary side interface B and in parallel with the load Ro. The output energy storage capacitor Co is used for output filtering to reduce the voltage ripple of the output voltage.

[0055] for Figure 2 The power conversion circuit shown in the figure has a working principle reference Figure 4 , Figure 4 A schematic diagram of the working timing of the power conversion circuit provided in this embodiment. Among them, i_L1 represents the current flowing through the conversion inductor L1, i_CO represents the current flowing through the output energy storage capacitor Co, i_Q1 represents the current flowing through the first MOS tube Q1, VDS_Q1 represents the source-drain voltage of the first MOS tube Q1, and PWM_Q1 represents the waveform of the first control signal corresponding to the first MOS tube Q1.

[0056] For the primary circuit of the transformer, when the first MOS tube Q1 is turned on, that is, PWM_Q1 is at a high level, the excitation current flows through the primary coil W1 and the first MOS tube Q1, thereby generating a current flowing through the first MOS tube Q1, and i_Q1 increases instantly. However, due to the existence of the primary coil W1, the loop current cannot jump to the maximum instantly, but is a slowly increasing change process, that is, the current flowing through the primary coil W1 and the first MOS tube Q1 gradually increases, and i_Q1 gradually increases during the process of PWM_Q1 being high. When the first MOS tube Q1 is turned off, the excitation current cannot flow through the primary coil W1 and the first MOS tube Q1, and i_Q1 returns to zero instantly.

[0057] In addition, when the first MOS tube Q1 is turned on, the impedance of the first MOS tube Q1 is close to 0, and the first MOS tube Q1 can be regarded as a wire, so the source-drain power supply VDS_Q1 of the first MOS tube Q1 is 0; when the first MOS tube Q1 is turned off, the impedance of the first MOS tube Q1 is very large, so the source-drain power supply VDS_Q1 of the first MOS tube Q1 is close to the power supply voltage, and as the primary coil W1 discharges, the divided voltage of the primary coil W1 gradually decreases, and the source-drain power supply VDS_Q1 of the first MOS tube Q1 slowly increases to the power supply voltage.

[0058] For the secondary circuit of the transformer, when the primary coil W1 generates a magnetic field based on the excitation current and the secondary coil W2 generates an initial induced current based on the magnetic field, the diode D1 is cut off, the conversion capacitor C1 is discharged, the conversion inductor L1 is charged, and the current i_L1 flowing through the conversion inductor L1 increases. The current flowing through the conversion inductor L1 increases, and the current flowing through the load Ro increases, and the current i_CO flowing through the output conversion capacitor Co increases. When the primary coil W1 no longer generates a magnetic field and the secondary coil W2 no longer generates an induced current, the diode D1 is turned on, the conversion capacitor C1 is charged, and the conversion inductor L1 enters a freewheeling state, and the current i_L1 flowing through the conversion inductor L1 decreases. The current flowing through the conversion inductor L1 decreases, and the current flowing through the load Ro decreases, and the current i_CO flowing through the output conversion capacitor Co decreases.

[0059] In short, the function of the output unit 300 can be regarded as the function of a boost circuit, which is used for boost discharge. However, the output unit 300 provided in this embodiment splits the components in the original boost circuit and partially sets them in the secondary output loop of the transformer to reduce the ripple of the secondary output current.

[0060] In some embodiments, the output energy storage capacitor Co is set based on an electrolytic capacitor; the capacitance of the electrolytic capacitor can be set higher than that of an ordinary capacitor, but as the capacitance increases, the circuit area and device cost occupied by it will increase significantly; in the power conversion circuit 100 provided in this embodiment, since the ripple of the secondary side line is reduced, the capacitance of the required output energy storage capacitor Co is reduced, and the output energy storage capacitor Co configured based on the electrolytic capacitor no longer needs to be set to a larger capacitance, which greatly reduces the circuit area occupied by the output energy storage capacitor Co and greatly reduces the circuit cost.

[0061] Based on the foregoing, it can be known that when the control unit 200 controls the primary coil W1 to be connected to the excitation current, the output parameter of the secondary interface B increases; when the control unit 200 controls the primary coil W1 not to be connected to the excitation current, the output parameter of the secondary interface B decreases.

[0062] In some embodiments, the power conversion circuit 100 further includes a feedback loop 400. The feedback loop 400 is configured to adjust the duty cycle of the first control signal based on a comparison result between an output parameter of the secondary interface B and a preset parameter. The output parameter of the secondary interface B may include an output current, an output voltage, etc., and the preset parameter may also be a preset current, a preset voltage, etc.

[0063] The feedback loop 400 outputs the duty cycle of the first control signal by comparing the output current of the secondary interface B with the preset current, or the output voltage of the secondary interface B with the preset voltage. The duty cycle of the first control signal determines the conduction time of the control unit 200, thereby adjusting the output parameter size of the secondary interface B.

[0064] In the power conversion circuit 100 provided in this embodiment, the feedback loop 400 is provided to stabilize the output of the power conversion circuit 100 , and the output parameter of the power conversion circuit 100 approaches the preset parameter.

[0065] Specific reference Figure 5 In some embodiments, the feedback loop 400 includes a first detection unit, a comparison unit 401 and a processing unit. The first detection unit is configured to obtain an output parameter of the secondary interface B; the comparison unit 401 is configured to generate a parameter adjustment value based on a comparison result between the output parameter of the secondary interface B and a preset parameter; and the processing unit is configured to adjust the duty cycle of the first control signal based on the parameter adjustment value.

[0066] For the first detection unit, in one example, the first detection unit can directly read the output parameters of the secondary interface B by means of a voltmeter or an ammeter; in another example, the first detection unit can obtain the output parameters of the secondary interface B by means of a probe or the like.

[0067] For the comparison unit 401, in some embodiments, after the first detection unit obtains the output voltage Vo of the secondary interface B, the difference between the output voltage Vo and the reference voltage Vref is adjusted by the compensation network to generate a first compensation voltage VEA, the first compensation voltage VEA is adjusted by the input voltage Vin to generate a compensation current Iref, and the difference between the compensation current Iref and the input current Iin is adjusted by the compensation network to generate a parameter adjustment value VFB.

[0068] It should be noted that Figure 5 The specific structures of the comparison unit 401 and the processing unit illustrated in the figure do not constitute a limitation of this embodiment. Those skilled in the art can set the structure of the specific feedback loop 400 accordingly based on the text description of the comparison unit 401 and the processing unit and the functions required by the feedback loop 400.

[0069] Regarding the processing unit, in one example, the processing unit generates a first control signal based on the parameter adjustment value VFB and the initial control pulse, wherein the parameter adjustment value VFB is used to adjust a duty cycle of the generated first control signal.

[0070] refer to Figure 6 In some embodiments, the feedback loop 400 further includes: a second detection unit 402 and a judgment unit. The second detection unit 402 is configured to obtain the output parameter of the secondary coil W2; the judgment unit is configured to judge whether the output parameter of the secondary coil W2 is a valley value, and provide a trigger signal if the output parameter is a valley value; the processing unit is configured to provide a first control signal based on the trigger signal.

[0071] Specifically, the second detection unit 402 detects whether the output parameter of the secondary coil W2 is a valley value, so as to trigger the critical conduction mode (CRM) of the power conversion circuit 100 according to the present embodiment.

[0072] It should be noted that Figure 6 The valley bottom detection circuit composed of a coil and a resistor in parallel is used to implement the functions of the second detection unit 402 and the judgment unit in the example, and does not constitute a limitation of this embodiment. Those skilled in the art can select other detection and judgment methods based on the description of the second detection unit 402 and the judgment unit; for example, the output parameters of the secondary coil W2 are directly read by a voltmeter or an ammeter, or the output parameters of the secondary coil W2 are obtained by detection by a probe or the like.

[0073] For critical conduction mode, its working principle refers to Figure 7 , combined with Figure 4 , Figure 4 The relevant description will not be repeated in this embodiment. Figure 7 and Figure 4 The difference is that: in the critical conduction mode, the on-time and off-time of the control unit 200 just make the output parameter of the secondary coil W2 reach the peak / valley value; when the output parameter of the secondary coil W2 reaches the peak / valley value, the input parameter of the primary coil W1 also reaches the peak / valley value accordingly; therefore, after the current i_Q1 flowing through the first MOS tube Q1 gradually increases to the peak value, the first MOS tube Q1 is turned off, and PWM_Q1 jumps to a low level.

[0074] For the power conversion circuit 100 provided in this embodiment, an output unit is set in the secondary side circuit of the transformer so that the secondary side of the transformer can output a continuous output signal under the intermittent input signal of the primary side of the transformer, thereby reducing the ripple of the secondary side circuit of the transformer.

[0075] It should be noted that the ripple mentioned in the above description of this embodiment, if used to characterize voltage ripple, represents the difference between the maximum value and the minimum value of the voltage; if used to characterize current ripple, represents the difference between the maximum value and the minimum value of the current.

[0076] It should be noted that, in the absence of conflict, the inventive features of the power conversion circuit provided in the above embodiments can be randomly combined to obtain a new power conversion circuit embodiment.

[0077] Another embodiment of the present invention also provides a power supply system, which is used for a power supply to supply power to a load. The power supply system includes a power conversion circuit as provided in the above embodiment, wherein the primary side interface of the power conversion circuit is connected to the power supply, and the secondary side interface of the power conversion circuit is connected to the load.

[0078] In some embodiments, the power supply system includes multiple power conversion circuits, the primary side interfaces of the multiple power conversion circuits are arranged in parallel and connected to the power supply, and the secondary side interfaces of the multiple power conversion circuits are arranged in parallel and connected to the load.

[0079] Specific reference Figure 8 , Figure 8 This is a structural schematic diagram of the power supply system given in this embodiment; the primary side interfaces of multiple power conversion circuits are connected to the same power supply, and the secondary side interfaces are connected to the same load, thereby realizing the parallel setting of multiple power conversion circuits to further improve the power supply parameters such as the power supply voltage and power supply power of the power supply system.

[0080] It should be noted that Figure 8 In the example of the invention, the primary side interfaces of the multiple power conversion circuits are connected to the same power supply. In other embodiments, the primary side interfaces of the multiple power conversion circuits may be connected to different power supplies.

[0081] For the power supply system provided in this embodiment, an output unit is set in the secondary side circuit of the transformer so that when the primary side of the transformer is subjected to an intermittent input signal, the secondary side of the transformer can output a continuous output signal, thereby reducing the ripple of the secondary side circuit of the transformer.

[0082] In addition, the power supply system provided in this embodiment can be applied to a vehicle power supply system. The vehicle can be a fuel vehicle, a plug-in hybrid vehicle, or a new energy vehicle, etc. The present invention does not specifically limit this.

[0083] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the detailed description of other embodiments above, and will not be repeated here.

[0084] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of the present invention. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and corrections to the present invention. Such modifications, improvements and corrections are suggested in the present invention, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of the present invention.

[0085] The power conversion circuit and power supply system provided by the embodiments of the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A power conversion circuit, characterized in that: include: A transformer, including a primary coil and a secondary coil; Primary side interface, used to access the excitation current; The transformer is configured such that when the primary coil is connected to the excitation current, the secondary coil generates an initial induced current; Secondary side interface, used to output the sensing current; A control unit, connected to the primary coil and the primary interface; The control unit is configured to control the primary coil to access the excitation current from the primary interface based on the first control signal; An output unit is connected to the secondary coil and the secondary interface; the output unit is configured to output the induced current to the secondary interface according to the initial induced current, and the induced current is a continuous current.

2. The power conversion circuit according to claim 1, characterized in that: The output unit comprises: A conversion capacitor, a first end of the conversion capacitor is connected to a first end of the secondary coil; A conversion inductor, a first end of the conversion inductor connected to a second end of the conversion capacitor; A current cutoff unit, wherein an input end of the current cutoff unit is connected to the second end of the secondary coil and forms the secondary interface with the second end of the conversion inductor, and an output end of the current cutoff unit is connected to the second end of the conversion capacitor; The intercepting unit is configured to conduct the branch where the intercepting unit is located based on a preset conducting direction.

3. The power conversion circuit according to claim 1, characterized in that: The control unit includes a control switch, which is arranged in series with the first end and / or the second end of the primary coil; the control switch is configured to turn on the branch where the primary coil is located based on the first control signal.

4. The power conversion circuit according to claim 1, characterized in that: The primary side interface is used to connect to a power source, the secondary side interface is used to connect to a load, and the power conversion circuit further includes: An input energy storage capacitor is connected to the primary side interface and is arranged in parallel with the power supply; The output energy storage capacitor is connected to the secondary side interface and is arranged in parallel with the load.

5. The power conversion circuit according to claim 4, characterized in that: The output energy storage capacitor is arranged based on an electrolytic capacitor.

6. The power conversion circuit according to claim 1, characterized in that: The power conversion circuit further includes: a feedback loop configured to adjust a duty cycle of the first control signal based on a comparison result between an output parameter of the secondary side interface and a preset parameter.

7. The power conversion circuit according to claim 6, characterized in that: The feedback loop includes: A first detection unit is configured to obtain an output parameter of the secondary side interface; A comparison unit, configured to generate a parameter adjustment value based on a comparison result between the output parameter of the secondary side interface and the preset parameter; The processing unit is configured to adjust the duty cycle of the first control signal based on the parameter adjustment value.

8. The power conversion circuit according to claim 7, characterized in that: The feedback loop also includes: A second detection unit is configured to obtain an output parameter of the secondary coil; a judging unit configured to judge whether the output parameter of the secondary coil is a valley value, and provide a trigger signal if the output parameter is the valley value; The processing unit is configured to provide the first control signal based on the trigger signal.

9. A power supply system, used for a power source to supply power to a load, characterized in that: The power supply system comprises the power conversion circuit according to any one of claims 1 to 8, wherein a primary side interface of the power conversion circuit is connected to the power source, and a secondary side interface of the power conversion circuit is connected to the load.

10. The power supply system according to claim 9, characterized in that: It comprises a plurality of the power conversion circuits, wherein the primary side interfaces of the plurality of the power conversion circuits are arranged in parallel and connected to the power source, and the secondary side interfaces of the plurality of the power conversion circuits are arranged in parallel and connected to the load.

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