A vehicle-mounted three-port converter

Abstract

The application relates to the technical field of circuit control, in particular to a vehicle-mounted three-port converter. The vehicle-mounted charging machine and the high-voltage direct-current converter are integrated with the high-voltage battery connection port. When the vehicle-mounted charging machine works alone, the voltage stress of a rectifier tube in a low-voltage port conversion circuit is reduced and energy recovery is realized by controlling the conduction of a clamping switch tube in a corresponding clamping circuit in the low-voltage port conversion circuit of the high-voltage direct-current converter for a preset time period within the conduction time period of the switch tube of the common bridge arm of the vehicle-mounted charging machine and the high-voltage direct-current converter, so that the energy stored in the clamping capacitor in the corresponding clamping circuit is released to the low-voltage battery through the clamping switch tube in the corresponding clamping circuit and the secondary winding of the transformer of the high-voltage direct-current converter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit control, in particular to a vehicle-mounted three-port converter. BACKGROUND

[0002] The vehicle-mounted power supply is a key component for energy conversion and transmission in a new energy electric vehicle, including an on-board charger (OBC) and a high-voltage direct current-direct current (DCDC). Since the OBC and the high-voltage DCDC are both connected to the high-voltage battery bus, there is a physical connection between the two, in order to improve the power density of the vehicle-mounted power supply and reduce the cost, the OBC and the high-voltage DCDC can be connected to the port of the high-voltage battery for integration, and the OBC and the high-voltage DCDC use independent transformers respectively, thereby forming an integrated vehicle-mounted three-port converter.

[0003] In the integrated vehicle-mounted three-port converter, since the OBC (ignoring the front-stage power factor correction circuit) and the high-voltage DCDC share a common bridge arm, and the switching tube is not actually an ideal switch, i.e., there is a parasitic capacitor, when the OBC works alone, the parasitic capacitor of the switching tube of the common bridge arm connected to the high-voltage battery and the non-working bridge arm will form a half-bridge inverter circuit, and the energy on the parasitic capacitor will be transmitted to the port connected to the low-voltage battery through the transformer of the high-voltage DCDC. At this time, the parasitic capacitor of the switching tube of the non-working bridge arm, the common bridge arm and the transformer of the high-voltage DCDC are equivalent to a constant current source, which continuously transmits energy to the port connected to the low-voltage battery when the OBC works alone, so that the rectifier tube of the port bears a large voltage stress, which may cause damage to the rectifier tube of the port, and this part of energy will also be lost in the form of switching loss, reducing the overall efficiency of the vehicle-mounted charger when it works alone. SUMMARY

[0004] In view of the above shortcomings of the prior art, the purpose of the present application is to provide a vehicle-mounted three-port converter, which can not only reduce the voltage stress of the rectifier tube in the conversion circuit of the port connected to the low-voltage battery, but also realize energy recovery and improve the overall efficiency of the vehicle-mounted charger when it works alone by using a special switching tube control logic when the OBC works alone.

[0005] To achieve the above object and other related objects, the present application provides a vehicle-mounted three-port converter, comprising:

[0006] The first conversion circuit, the second conversion circuit, the third conversion circuit, the first transformer and the second transformer are independent of each other.

[0007] The first transformer comprises a first winding and a second winding, the second transformer comprises a third winding and a fourth winding, and the fourth winding comprises a positive winding segment and a negative winding segment connected in series;

[0008] The first conversion circuit comprises a first bridge arm and a second bridge arm, the first winding is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm, and the two ends of the first bridge arm and the second bridge arm serve as a first port connected with a power factor correction circuit;

[0009] The second conversion circuit comprises a third bridge arm, a fourth bridge arm and a fifth bridge arm, the second winding is connected between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm, the third winding is connected between the midpoint of the fourth bridge arm and the midpoint of the fifth bridge arm, and the two ends of the third bridge arm, the fourth bridge arm and the fifth bridge arm serve as a second port connected with a high-voltage battery;

[0010] The third conversion circuit comprises a positive rectification loop connected with the positive winding segment, a negative rectification loop connected with the negative winding segment, a first clamping circuit connected in parallel with the two ends of a rectifier tube in the positive rectification loop, and a second clamping circuit connected in parallel with the two ends of a rectifier tube in the negative rectification loop, the positive rectification loop is used for rectifying alternating current in a positive half cycle, the negative rectification loop is used for rectifying alternating current in a negative half cycle, the positive rectification loop and the negative rectification loop share an output bus line drawn from between the negative winding segment and the positive winding segment, and the direct-current side of the third conversion circuit serves as a third port connected with a low-voltage battery, wherein the first clamping circuit and the second clamping circuit comprise a clamping switch tube and a clamping capacitor arranged in series;

[0011] When power is transmitted from the first port to the second port or power is transmitted from the second port to the first port, the voltage stress of a rectifier tube in the third conversion circuit is reduced and energy is recovered by controlling the clamping switch tube of the second clamping circuit / first clamping circuit to be turned on for a preset time period within the on time period of the upper switch tube / lower switch tube of the fourth bridge arm, so that the energy stored in the clamping capacitor of the second clamping circuit / first clamping circuit is released to the low-voltage battery through the clamping switch tube of the second clamping circuit / first clamping circuit and the negative winding segment / positive winding segment.

[0012] In an optional embodiment of the present application, the third conversion circuit comprises an eleventh switch tube, a twelfth switch tube, a first clamping switch tube, a second clamping switch tube, a first clamping capacitor, a second clamping capacitor, a low-voltage output capacitor and an output inductor.

[0013] An input end of the eleventh switch tube, an output end of the first clamping switch tube are commonly connected to a homonymic end of the positive winding section, an input end of the twelfth switch tube and an output end of the second clamping switch tube are commonly connected to an antonymic end of the negative winding section, an input end of the first clamping switch tube is connected to one end of the first clamping capacitor, an input end of the second clamping switch tube is connected to one end of the second clamping capacitor, an output end of the eleventh switch tube, an output end of the twelfth switch tube, the other end of the first clamping capacitor, the other end of the second clamping capacitor and one end of the low-voltage output capacitor are commonly connected to a negative electrode of a low-voltage battery, one end of the output inductor is connected to a homonymic end of the positive winding section and an antonymic end of the negative winding section respectively, the other end of the output inductor and the other end of the low-voltage output capacitor are commonly connected to a positive electrode of the low-voltage battery.

[0014] When power is transmitted from the first port to the second port or power is transmitted from the second port to the first port, the energy stored in the second clamping capacitor / first clamping capacitor is released to the low-voltage battery through the second clamping switch tube / first clamping switch tube and the negative winding section / positive winding section by controlling the second clamping switch tube / first clamping switch tube to be turned on for a preset time period in the on period of the upper switch tube / lower switch tube of the fourth bridge arm, so as to reduce the voltage stress of the twelfth switch tube / eleventh switch tube and realize energy recovery.

[0015] In an optional embodiment of the present application, the third conversion circuit further comprises a thirteenth switch tube and a fourteenth switch tube.

[0016] An input end of the thirteenth switch tube is connected to a homonymic end of the positive winding section and an antonymic end of the negative winding section respectively, and an output end of the thirteenth switch tube is connected to a positive electrode of the low-voltage battery through the output inductor.

[0017] An input end of the fourteenth switch tube is connected between the thirteenth switch tube and the output inductor, and an output end of the fourteenth switch tube is connected to a negative electrode of the low-voltage battery.

[0018] When power is transmitted from the first port to the second port or power is transmitted from the second port to the first port, the energy stored in the second clamping capacitor / first clamping capacitor is released to the low-voltage battery through the second clamping switch tube / first clamping switch tube and the negative winding section / positive winding section by controlling the thirteenth switch tube to keep in the on state, the fourteenth switch tube to keep in the off state, and the second clamping switch tube / first clamping switch tube to be turned on for a preset time period in the on period of the upper switch tube / lower switch tube of the fourth bridge arm, so as to reduce the voltage stress of the twelfth switch tube / eleventh switch tube and realize energy recovery.

[0019] In an optional embodiment of the present application, the third conversion circuit further comprises a thirteenth switch tube and a fourteenth switch tube.

[0020] One end of the output inductor is connected to the output end of the thirteenth switch tube, and the input end of the thirteenth switch tube is connected to the positive pole of the low-voltage battery.

[0021] The input end of the fourteenth switch tube is connected between the thirteenth switch tube and the output inductor, and the output end of the fourteenth switch tube is connected to the negative pole of the low-voltage battery.

[0022] When power is transmitted from the first port to the second port or power is transmitted from the second port to the first port, the fourteenth switch tube is kept in an off state, and the second clamping switch tube / first clamping switch tube is controlled to be turned on for a preset time period during the on period of the upper switch tube / lower switch tube of the fourth bridge arm, so that the energy stored in the second clamping capacitor / first clamping capacitor is released to the low-voltage battery through the second clamping switch tube / first clamping switch tube and the negative winding section / positive winding section, so as to reduce the voltage stress of the twelfth switch tube / eleventh switch tube and realize energy recovery.

[0023] In an optional embodiment of the present application, the turn-on time of the upper switch tube / lower switch tube of the fourth bridge arm is the same as the turn-on time of the clamping switch tube of the second clamping circuit / first clamping circuit.

[0024] In an optional embodiment of the present application, the turn-on time of the upper switch tube / lower switch tube of the fourth bridge arm is different from the turn-on time of the clamping switch tube of the second clamping circuit / first clamping circuit.

[0025] In an optional embodiment of the present application, the first conversion circuit further comprises a resonant inductor and a resonant capacitor; the resonant inductor and the resonant capacitor are connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm.

[0026] In an optional embodiment of the present application, the second conversion circuit further comprises a DC blocking capacitor and a high-voltage output capacitor; the DC blocking capacitor is connected in series between the midpoint of the fourth bridge arm and the second winding, and the high-voltage output capacitor is connected in parallel across the fifth bridge arm.

[0027] In an optional embodiment of the present application, the preset time period is less than or equal to half of the switching period of the upper switch tube / lower switch tube of the fourth bridge arm.

[0028] In an optional embodiment of the present application, the length of the preset time period is a fixed value or is calculated according to the voltage of the high-voltage battery in a closed-loop manner.

[0029] The vehicle-mounted three-port converter of the application comprises a first conversion circuit, a second conversion circuit, a third conversion circuit, a first transformer and a second transformer, the first transformer and the second transformer are independent of each other; the first transformer comprises a first winding and a second winding, the second transformer comprises a third winding and a fourth winding, the fourth winding comprises a positive winding segment and a negative winding segment connected in series; the first conversion circuit comprises a first bridge arm and a second bridge arm, the first winding is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm, and the two ends of the first bridge arm and the second bridge arm serve as a first port connected with a power factor correction circuit; the second conversion circuit comprises a third bridge arm, a fourth bridge arm and a fifth bridge arm, the second winding is connected between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm, and the third winding is connected between the midpoint of the fourth bridge arm and the midpoint of the fifth bridge arm, the two ends of the third bridge arm, the fourth bridge arm and the fifth bridge arm serve as a second port connected with a high-voltage battery; the third conversion circuit comprises a positive rectification loop connected with the positive winding segment, a negative rectification loop connected with the negative winding segment, a first clamping circuit connected in parallel at the two ends of a rectifier tube in the positive rectification loop, and a second clamping circuit connected in parallel at the two ends of a rectifier tube in the negative winding segment, the positive rectification loop is used for rectifying alternating current in a positive half cycle, the negative rectification loop is used for rectifying alternating current in a negative half cycle, the positive rectification loop and the negative rectification loop share an output bus line drawn from between the negative winding segment and the positive winding segment, and the direct current side of the third conversion circuit serves as a third port connected with a low-voltage battery, wherein the first clamping circuit and the second clamping circuit comprise clamping switch tubes and clamping capacitors arranged in series; when power is transmitted from the first port to the second port, or power is transmitted from the second port to the first port, the clamping switch tubes of the second clamping circuit / first clamping circuit are turned on for a preset time period within the on time period of the upper switch tube / lower switch tube of the fourth bridge arm, so that the energy stored in the clamping capacitors of the second clamping circuit / first clamping circuit is released to the low-voltage battery through the clamping switch tubes of the second clamping circuit / first clamping circuit and the negative winding segment / positive winding segment, so as to reduce the voltage stress of the rectifier tube in the third conversion circuit and realize energy recovery, thereby improving the overall efficiency of the vehicle-mounted charger in the vehicle-mounted three-port converter when the vehicle-mounted charger works alone. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A circuit block diagram of the vehicle-mounted three-port converter of the application is shown.

[0031] Figure 2 A circuit topology diagram of the vehicle-mounted three-port converter of a specific embodiment of the application is shown.

[0032] Figure 3 A circuit topology diagram of the vehicle-mounted three-port converter of another specific embodiment of the application is shown. Figure 2 A switch tube driving time sequence of the vehicle-mounted three-port converter is shown.

[0033] Figure 4 A circuit topology diagram of the vehicle-mounted three-port converter of another specific embodiment of the application is shown.

[0034] Figure 5 A switching tube driving timing sequence of the vehicle-mounted three-port converter is shown. Figure 4 A switching tube driving timing sequence of the vehicle-mounted three-port converter is shown.

[0035] Figure 6 A circuit topology diagram of the vehicle-mounted three-port converter of yet another embodiment of the present application is shown. DETAILED DESCRIPTION

[0036] The above objects and other advantages of the present application will become more apparent by describing in detail the only embodiments thereof as illustrated in the accompanying drawings in which:

[0037] As used in the present application, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The term "or" is generally employed in its sense including "and / or" unless the content clearly dictates otherwise. The term "and / or" means both or either. The term "at least two" means two or more, unless the content clearly dictates otherwise. The terms "first," "second," "third," etc. are used only to describe one of a number of similar items and are not intended to denote relative importance or to imply that the indicated technical features are limited to a number of items. Thus, features defined with "first," "second," "third," etc. can explicitly or implicitly include one or at least two of the features. The terms "one end" and "the other end," and "proximal" and "distal" generally refer to two parts in correspondence, which include not only the end points, but also the relative positional relationship between the two parts. The terms "mounting," "connecting," and "connecting" should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through an intermediate medium; can be the internal connection of two elements or the interaction relationship between two elements. In addition, as used in the present application, a component disposed in another component generally only indicates that there is a connection, coupling, cooperation or transmission relationship between the two components, and the two components can be directly or indirectly connected, coupled, cooperated or transmitted through an intermediate component, and cannot be understood as indicating or implying the spatial positional relationship between the two components, i.e. one component can be in any orientation inside, outside, above, below or one side of another component, unless the content clearly indicates otherwise. 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.

[0038] It should be noted that in the present application, the expression "... A1 / A2..., B1 / B2..., C1 / C2..." refers to "... A1..., B1..., C1..." and / or "... A2..., B2..., C2...".

[0039] Figure 1 is a circuit block diagram of a vehicle-mounted three-port converter in an embodiment of the present application. As shown in Figure 1 , the integrated charger includes a power factor correction circuit, three-port circuit, a first transformer T1 and a second transformer T2, the three-port circuit being a first conversion circuit, a second conversion circuit and a third conversion circuit respectively. The first transformer T1 has a first magnetic core, a first winding n1 and a second winding n2, and the second transformer T2 has a second magnetic core, a third winding n3 and a fourth winding. The AC side of the power factor correction circuit is connected with the AC grid, and the DC side of the power factor correction circuit is connected with the DC bus through the DC bus, and the AC side of the first conversion circuit is connected with the first winding n1, and the AC side of the second conversion circuit is connected with the second winding n2 and the third winding n3 respectively, and the DC side of the second conversion circuit is connected with the high-voltage battery (a battery pack with an output voltage greater than 100V); the AC side of the third conversion circuit is connected with the fourth winding, and the DC side of the third conversion circuit is connected with the low-voltage battery (a battery pack with an output voltage less than 50V, such as a 12V storage battery), the first conversion circuit, the first transformer T1 and two of the two bridge arms of the second conversion circuit constitute a post-stage bidirectional DCDC converter of the OBC, which is used to convert AC into DC to charge the high-voltage battery or convert the output voltage of the high-voltage battery into AC output in cooperation with the power factor correction circuit; the third bridge arm of the second conversion circuit and one of the other two bridge arms, the second transformer T2 and the leakage inductance (L Figure 2 of the second transformer T2, lk ), the third conversion circuit constitutes a high-voltage DCDC converter, and the high-voltage battery is charged to the low-voltage battery through the high-voltage DCDC converter, and by integrating the vehicle-mounted charger and the high-voltage DC converter with the high-voltage battery connection port, a common bridge arm is shared, which can improve the power density of the vehicle-mounted power supply and reduce the cost.

[0040] Regarding the circuit structure of the first conversion circuit, in an embodiment, referring to Figure 2 , the first conversion circuit has two bridge arms, which are a first bridge arm and a second bridge arm, and the two ends of the first bridge arm and the second bridge arm are used as an A port (as a first port) for connecting the output end of the power factor correction circuit through the DC bus, and the first winding n1 is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm. Further, the first conversion circuit further includes an LC resonance network composed of a resonance inductor Lr and a resonance capacitor Cr1 and a bus electrolytic capacitor C bus, a resonant inductor Lr and a resonant capacitor Cr1 are connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm, and a bus electrolytic capacitor C bus It should be noted that, in other embodiments, the resonant network of the first conversion circuit can also be LLC, CLC, CLLC, or CLLLLC, etc.

[0041] Further, referring to Figure 2 The first conversion circuit includes a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4. The first switch Q1 and the second switch Q2 are connected in series to form a first bridge arm, and a midpoint of the first bridge arm is derived between the first switch Q1 and the second switch Q2. The third switch Q3 and the fourth switch Q4 are connected in series to form a second bridge arm, and a midpoint of the second bridge arm is derived between the third switch Q3 and the fourth switch Q4. Specifically, an input end of the first switch Q1 is connected to a positive bus, an output end of the first switch Q1 is connected to an input end of the second switch Q2, an output end of the second switch Q2 is connected to a negative bus, an input end of the third switch Q3 is connected to the positive bus, an output end of the third switch Q3 is connected to an input end of the fourth switch Q4, an output end of the fourth switch Q4 is connected to the negative bus, and the connection between the output end of the first switch Q1 and the input end of the second switch Q2 is the midpoint of the first bridge arm, and the connection between the output end of the third switch Q3 and the input end of the fourth switch Q4 is the midpoint of the second bridge arm. The control end of each of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 is connected to an external logic processor, and the logic processor is used to send control signals to control the conduction or turn-off of each of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4.

[0042] For example, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are all NMOS tubes, the input end of each of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 is the drain of the NMOS tube, the output end of each of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 is the source of the NMOS tube, and the control end of each of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 is the gate of the NMOS tube. Alternatively, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 can also all be PMOS tubes, or NPN triodes or IGBT tubes connected in reverse parallel with diodes.

[0043] Regarding the circuit structure of the second conversion circuit, in an embodiment, referring to Figure 2, the second conversion circuit has three bridge arms, which are a third bridge arm, a fourth bridge arm (as a common bridge arm of the on-board charger and the high-voltage DC converter) and a fifth bridge arm; two ends of the third bridge arm, the fourth bridge arm and the fifth bridge arm are used as a B port (as a second port) for connecting a high-voltage battery Bat HV , the second winding n2 is connected between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm, the third winding n3 is connected between the midpoint of the fourth bridge arm and the midpoint of the fifth bridge arm, and the second winding n2 and the third winding n3 are connected in series. Further, the second conversion circuit further comprises a DC blocking capacitor C iso and a high-voltage output capacitor C HV , the DC blocking capacitor C iso is connected in series between the midpoint of the fourth bridge arm and the second winding, and the high-voltage output capacitor C HV is connected in parallel to the two ends of the fifth bridge arm.

[0044] Further, referring to Figure 2 , the second conversion circuit B comprises a fifth switch Q5, a sixth switch Q6, a seventh switch Q7, an eighth switch Q8, a ninth switch Q9 and a tenth switch Q10, the fifth switch Q5 and the sixth switch Q6 are connected in series to form the third bridge arm, and the midpoint of the third bridge arm is led out between the fifth switch Q5 and the sixth switch Q6; the seventh switch Q7 and the eighth switch Q8 are connected in series to form the fourth bridge arm, and the midpoint of the fourth bridge arm is led out between the seventh switch Q7 and the eighth switch Q8; the ninth switch Q9 and the tenth switch Q10 are connected in series to form the fifth bridge arm, and the midpoint of the fifth bridge arm is led out between the ninth switch Q9 and the tenth switch Q10. Specifically, the input end of the fifth switch Q5 is connected to the positive end of the high-voltage battery Bat HV , the output end of the fifth switch Q5 is connected to the input end of the sixth switch Q6, the output end of the sixth switch Q6 is connected to the negative end of the high-voltage battery Bat HV , and the connection between the output end of the fifth switch Q5 and the input end of the sixth switch Q6 is the midpoint of the third bridge arm; the input end of the seventh switch Q7 is connected to the positive end of the high-voltage battery Bat HV , the output end of the seventh switch Q7 is connected to the input end of the eighth switch Q8, the output end of the eighth switch Q8 is connected to the negative end of the high-voltage battery Bat HV , and the connection between the output end of the seventh switch Q7 and the input end of the eighth switch Q8 is the midpoint of the fourth bridge arm; the input end of the ninth switch Q9 is connected to the positive end of the high-voltage battery Bat HV , the output end of the ninth switch Q9 is connected to the input end of the tenth switch Q10, and the output end of the tenth switch Q10 is connected to the negative end of the high-voltage battery Bat HVThe connection between the negative end of the first switch tube Q1, the output end of the second switch tube Q2 and the input end of the third switch tube Q3 is the midpoint of the fourth bridge arm. The control end of each of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 is connected to an external logic processor, which is used to send a control signal to control the conduction or turn-off of each of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4.

[0045] For example, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are all NMOS tubes, the input end of each of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 is the drain of the NMOS tube, the output end of each of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 is the source of the NMOS tube, and the control end of each of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 is the gate of the NMOS tube. Alternatively, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 can all be PMOS tubes, or NPN triodes or IGBT tubes in reverse parallel connection with diodes.

[0046] As to the circuit structure of the second conversion circuit, in an embodiment, as shown in Figure 2 ,

[0047] The third conversion circuit comprises a positive rectifier circuit connected with the positive winding section n5, a negative rectifier circuit connected with the negative winding section n4, a first clamping circuit connected in parallel with the rectifier tube (the eleventh switch tube Q F ) of the positive rectifier circuit, and a second clamping circuit connected in parallel with the rectifier tube (the twelfth switch tube Q E ) of the negative rectifier circuit. The positive rectifier circuit is used for rectifying the alternating current in the positive half cycle, and the negative rectifier circuit is used for rectifying the alternating current in the negative half cycle. The positive rectifier circuit and the negative rectifier circuit share an output bus line drawn from between the negative winding section n5 and the positive winding section n4. The direct current side of the third conversion circuit is connected with the port C of the low-voltage battery Bat LV . The first clamping circuit and the second clamping circuit comprise clamping switch tubes and clamping capacitors arranged in series.

[0048] Further, continuing to refer to Figure 2, the fourth winding comprises a negative winding section n4 and a positive winding section n5 connected in series, the like end of the negative winding section n4 and the unlike end of the positive winding section n5 are connected, the third conversion circuit comprises an eleventh switch tube Q F , a twelfth switch tube Q E , a first clamping switch tube Q H , a second clamping switch tube Q G , a first clamping capacitor C ClampF , a second clamping capacitor C LV , a low-voltage output capacitor C F and an output inductor Lo. The input end of the eleventh switch tube Q H , the output end of the first clamping switch tube Q E are commonly connected to the unlike end of the positive winding section n5, the input end of the twelfth switch tube Q G and the output end of the second clamping switch tube Q H are commonly connected to the like end of the negative winding section n4, the input end of the first clamping switch tube Q ClampF is connected to one end of the first clamping capacitor C G , the input end of the second clamping switch tube Q ClampE is connected to one end of the second clamping capacitor C F , the output end of the eleventh switch tube Q E , the output end of the twelfth switch tube Q ClampF , the other end of the first clamping capacitor C ClampE and the other end of the second clamping capacitor C LV and one end of the low-voltage output capacitor C LV are commonly connected to the negative electrode of a low-voltage battery Bat LV , one end of the output inductor Lo is connected to the like end of the positive winding section n5 and the unlike end of the negative winding section n4 respectively, the other end of the output inductor Lo and the other end of the low-voltage output capacitor C LV are commonly connected to the positive electrode of the low-voltage battery Bat H , the first clamping switch tube Q ClampF and the first clamping capacitor C G constitute a first clamping circuit, the second clamping switch tube Q ClampE and the second clamping capacitor C F constitute a second clamping circuit. The control end of the eleventh switch tube Q E , the twelfth switch tube Q H , the first clamping switch tube Q G and the second clamping switch tube Q F is connected to an external logic processor, the logic processor is used to send control signals to control the eleventh switch tube Q E , the twelfth switch tube Q H , the first clamping switch tube Q Gare respectively turned on or turned off. It can be understood that in other embodiments, the third conversion circuit can also adopt other rectifier circuit topologies capable of short-circuiting the same-named end of the negative winding section n4 and the different-named end of the positive winding section n5.

[0049] The eleventh switch Q F , the twelfth switch Q E , the first clamping switch Q H and the second clamping switch Q G are all NMOS tubes. The eleventh switch Q F , the twelfth switch Q E , the first clamping switch Q H and the second clamping switch Q G respectively have their input ends as the drain of the NMOS tube. The eleventh switch Q F , the twelfth switch Q E , the first clamping switch Q H and the second clamping switch Q G respectively have their output ends as the source of the NMOS tube. The eleventh switch Q F , the twelfth switch Q E , the first clamping switch Q H and the second clamping switch Q G respectively have their control ends as the gate of the NMOS tube. Alternatively, the eleventh switch Q F , the twelfth switch Q E , the first clamping switch Q H and the second clamping switch Q G may all be PMOS tubes, or NPN triodes or IGBT tubes in reverse parallel connection with diodes.

[0050] When the on-board three-port converter is in the OBC single working state, power is transmitted from the power factor correction circuit to the A port, and is inverted into alternating current by the first conversion circuit and then transmitted to the B port through the first transformer T1. After being rectified by the fifth switch Q5, the sixth switch Q6, the seventh switch Q7 and the eighth switch Q8 of the second conversion circuit, the alternating current is supplied to the high-voltage battery Bat HVCharging, at this time, high-voltage DCDC converter does not work, that is, C port is an idle port. Ideally, no energy is transferred from the B port to the C port, but the physical structure and manufacturing process of the semiconductor switch tube causes the existence of parasitic capacitance at both ends of the switch tube. When the OBC works alone, the seventh switch tube Q7 and the eighth switch tube Q8 in the B port rectifier bridge are alternately turned on according to the preset control mode (phase shift control or frequency conversion control), and the ninth switch tube Q9 and the tenth switch tube Q10 are not in action, then the seventh switch tube Q7 and the eighth switch tube Q8 alternately in action and the ninth switch tube Q9 and the tenth switch tube Q10 not in action constitute a half-bridge inverter circuit. The midpoint D of the fourth bridge arm composed of the seventh switch tube Q7 and the eighth switch tube Q8 alternately in action has a voltage v D The voltage of the high-voltage battery Bat HV jumps between the voltage of the high-voltage battery Bat DE and 0V, and the voltage jump of the D point is coupled to the midpoint E of the fifth bridge arm composed of the ninth switch tube Q9 and the tenth switch tube Q10 through the third winding n3 of the second transformer T2. Due to the existence of the second transformer T2 and the impedance of the line, the voltage changes of the D point and the E point are not synchronous, that is, the voltage v F between the D point and the E point exists a mutation. In a switching period of the seventh switch tube Q7 and the eighth switch tube Q8 in action, the energy on the parasitic capacitance of the ninth switch tube Q9 and the tenth switch tube Q10 will be transmitted to the C port through the second transformer T2, and then charged to the low-voltage output capacitor C E after rectification. LV At this time, the seventh switch tube Q7 and the eighth switch tube Q8, the parasitic capacitance of the ninth switch tube Q9 and the tenth switch tube Q10, the second transformer T2, the eleventh switch tube Q F and the twelfth switch tube Q E constitute a parasitic constant current source, which continuously transmits the energy on the parasitic capacitance to the C port. Due to the existence of the transformer leakage inductance and the line parasitic inductance, the voltage stress borne by the rectifier tube (the eleventh switch tube Q F and the twelfth switch tube Q E ) of the C port increases with the increase of the current when the OBC works, which may exceed the maximum value of the allowable safe working of the rectifier tube of the C port, and at the same time, part of the energy is lost in the form of switching loss.

[0051] Based on this, the switch tube driving time sequence as shown in Figure 3 may be used to control the working of each switch tube in the third conversion circuit when the OBC works alone to reduce the voltage stress of the rectifier tube in the third conversion circuit, realize energy recovery, and improve the overall efficiency when the vehicle-mounted charger works alone.

[0052] As shown in Figure 3As shown, when the OBC works alone, the power flows from the A port to the B port, and the seventh switch Q7 and the eighth switch Q8 are in an alternating conduction state, and the modulation mode is determined by the OBC rear DCDC converter topology. The ninth switch Q9 and the tenth switch Q10 are not conductive to close the power flow to the third port. Since the parasitic capacitance is small, the current transmitted to the C port by the parasitic constant current source is not large, so the eleventh switch Q F and the twelfth switch Q E may not be turned on, and the internal parasitic anti-parallel diode is used for non-controlled rectification to charge the low-voltage battery Bat LV (such as a 12V storage battery). However, as the current of the B port increases, the voltage stress on the rectifier tube (the eleventh switch Q F and the twelfth switch Q E ) converted to the C port through the second transformer T2 may exceed the maximum allowable value. Due to the presence of the clamping circuit, the voltage stress of the rectifier tube of the C port can charge the clamping capacitor, but since the clamping tube is not driven, the clamping capacitor has no discharge circuit, and the voltage of the clamping capacitor can also reflect the voltage stress of the rectifier tube of the C port. Therefore, the first clamping switch Q H and the second clamping switch Q G can be driven according to the driving logic shown in Figure 3 to be turned on for ΔT time (a preset period), and in the ΔT time, the energy stored in the clamping capacitor is released to the low-voltage battery Bat LV through the clamping tube and the fourth winding of the second transformer T2 to charge, so as to reduce the voltage stress of the rectifier tube of the C port and realize energy recovery.

[0053] Wherein, the length of ΔT time can be set as a fixed value in an open-loop manner, the greater the ΔT, the smaller the voltage stress of the rectifier tube of the C port, the less the energy on the clamping capacitor, and the more the energy recovery. Of course, the length of ΔT time can also be calculated in real time according to the voltage of the high-voltage battery in a closed-loop manner. Therefore, the length of ΔT time is at most 0.5*T s , that is, the preset period is less than or equal to half of the switching period T s of the upper switch (the seventh switch Q7) / the lower switch (the eighth switch Q8) of the fourth bridge arm, and at the same time, it is also necessary to ensure that there is no current flowing through the rectifier tube connected in parallel with it in the ΔT time to prevent the clamping capacitor from being short-circuited, that is, the eleventh switch Q F and the first clamping switch Q H , the twelfth switch Q E and the second clamping switch Q G cannot be turned on at the same time.

[0054] It should be noted that Figure 3The clamp switch control mode shown is not only applicable to the OBC forward working mode, that is, power is transmitted from the A port to the B port, but also applicable to the OBC reverse working mode, that is, power is transmitted from the B port to the A port, and can also achieve the effects of reducing the voltage stress of the rectifier tube of the C port and energy recovery. In other words, in the present application, when power is transmitted from the A port to the B port or power is transmitted from the B port to the A port, by controlling the second clamp switch Q G / first clamp switch Q H to be turned on for a preset time period ΔT to store energy in the second clamp capacitor C ClampE / first clamp capacitor C ClampF The energy stored is released to the low-voltage battery Bat G through the second clamp switch Q H / first clamp switch Q LV and the negative winding section n4 / positive winding section n5, so as to reduce the voltage stress of the twelfth switch Q E / eleventh switch Q F and achieve energy recovery.

[0055] It should be noted that the turn-on time of the upper switch (seventh switch Q7) / lower switch (eighth switch Q8) of the fourth bridge arm and the turn-on time of the second clamp switch Q G / first clamp switch Q H may be the same as shown in Figure 3 , or may be different, as long as the seventh switch Q7 turns on the second clamp switch Q G and the eighth switch Q8 turns on the first clamp switch Q H .

[0056] Figure 4 Another topology of a vehicle-mounted three-port converter is shown, which is different from the topology of the vehicle-mounted three-port OBC converter shown in Figure 2 in that the third conversion circuit additionally introduces a thirteenth switch Q S and a fourteenth switch Q T , and the overall control logic is basically the same, except that the control logic of the thirteenth switch Q S and the fourteenth switch Q T is added.

[0057] Please refer to Figure 4 , the third conversion circuit includes an eleventh switch Q F , a twelfth switch Q E , a first clamp switch Q Hthe second clamping switch Q G the first clamping capacitor C ClampF the second clamping capacitor C ClampE the low-voltage output capacitor C LV the output inductor Lo, the thirteenth switch Q S and the fourteenth switch Q T , wherein the input end of the thirteenth switch Q S is connected with the same end of the positive winding section n5 and the different end of the negative winding section n4 respectively, the output end of the thirteenth switch Q S is connected with the positive pole of the low-voltage battery Bat LV through the output inductor Lo, the input end of the fourteenth switch Q T is connected between the thirteenth switch Q S and the output inductor Lo, and the output end of the fourteenth switch Q T is connected with the negative pole of the low-voltage battery Bat LV , and the connections of other components are the same as those shown in Figure 2 , which will not be described herein.

[0058] Figure 4 The vehicle-mounted three-port converter shown in Figure 5 may also use the switch driving timing sequence shown in to control the operation of each switch in the third conversion circuit when the OBC works alone, so as to reduce the voltage stress of the rectifier in the third conversion circuit, realize energy recovery, and improve the overall efficiency when the vehicle-mounted charger works alone.

[0059] Specifically, referring to Figure 5 , when power is transmitted from the A port to the B port or power is transmitted from the B port to the A port, the thirteenth switch Q S is kept in the conduction state, the fourteenth switch Q T is kept in the off state, and the second clamping switch Q G / the first clamping switch Q H is turned on for a preset time period ΔT during the conduction period of the upper switch (the seventh switch Q7) / the lower switch (the eighth switch Q8) of the fourth bridge arm, so as to release the energy stored in the second clamping capacitor C ClampE / the first clamping capacitor C ClampF to the low-voltage battery Bat G through the second clamping switch Q H / the first clamping switch Q LV and the negative winding section n4 / the positive winding section n5, so as to reduce the voltage stress of the twelfth switch Q E / the eleventh switch Q F and realize energy recovery.

[0060] Figure 6The topology of the third type of vehicle-mounted three-port converter is shown, and... Figure 2 Compared to the topology of the onboard three-port OBC converter shown, the difference is that the third conversion circuit adds an additional thirteenth switch, Q. S and the fourteenth switch Q T The overall control logic is basically the same, the only difference being the addition of a thirteenth switch, Q. S and the fourteenth switch Q T The control logic.

[0061] Please see Figure 6 The third conversion circuit includes the eleventh switching transistor Q. F The twelfth switch Q E First clamping switch Q H Second clamping switch Q G First clamping capacitor C ClampF Second clamping capacitor C ClampE Low-voltage output capacitor C LV Output inductor Lo, thirteenth switching transistor Q S and the fourteenth switch Q T The other end of the output inductor Lo is connected to the thirteenth switch Q. S The output terminal is connected to the thirteenth switch Q. S The input terminal is connected to the low-voltage battery Bat. LV The positive terminal is connected to the fourteenth switch Q. T The input terminal is connected to the thirteenth switch Q. S Between the output inductor Lo and the fourteenth switch Q T The output terminal is connected to the low-voltage battery Bat LV The negative terminal connection, and the connections of other components are... Figure 2 The same applies, so I won't go into details here.

[0062] Figure 6 The vehicle-mounted three-port converter shown can also be used as follows: Figure 5 The switching transistor driving timing shown is used to control the operation of each switching transistor in the third conversion circuit when the OBC is working alone, thereby reducing the voltage stress on the rectifier in the third conversion circuit and realizing energy recovery, thus improving the overall efficiency of the on-board charger when it is working alone.

[0063] Specifically, see Figure 5 When power is transferred from port A to port B, or from port B to port A, the fourteenth switch Q is controlled. T Always remain in the off state (thirteenth switch Q) S It can be like Figure 5 The thirteenth switch Q can remain in the ON state or the OFF state at all times. Sthe state of the first bridge arm (i.e. the state of the first bridge arm does not affect the energy transfer), the fourteenth switch Q T is always kept off, during the on period of the upper switch (the seventh switch Q7) / lower switch (the eighth switch Q8) of the fourth bridge arm, the second clamping switch Q G / the first clamping switch Q H is turned on for a preset period ΔT to discharge the energy stored in the second clamping capacitor C ClampE / the first clamping capacitor C ClampF to the low-voltage battery Bat G through the second clamping switch Q H / the first clamping switch Q LV and the negative winding section n4 / positive winding section n5 to the low-voltage battery Bat E to reduce the voltage stress of the twelfth switch Q F / the eleventh switch Q

[0064] In summary, the vehicle-mounted three-port converter comprises a first conversion circuit, a second conversion circuit, a third conversion circuit, a first transformer and a second transformer, the first transformer and the second transformer are independent of each other; the first transformer comprises a first winding and a second winding, the second transformer comprises a third winding and a fourth winding, the fourth winding comprises a positive winding segment and a negative winding segment connected in series; the first conversion circuit comprises a first bridge arm and a second bridge arm, the first winding is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm, and the two ends of the first bridge arm and the second bridge arm serve as a first port connected with a power factor correction circuit; the second conversion circuit comprises a third bridge arm, a fourth bridge arm and a fifth bridge arm, the second winding is connected between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm, the third winding is connected between the midpoint of the fourth bridge arm and the midpoint of the fifth bridge arm, and the two ends of the third bridge arm, the fourth bridge arm and the fifth bridge arm serve as a second port connected with a high-voltage battery; the third conversion circuit comprises a positive rectification loop connected with the positive winding segment, a negative rectification loop connected with the negative winding segment, a first clamping circuit connected in parallel at the two ends of a rectifier tube of the positive rectification loop, and a second clamping circuit connected in parallel at the two ends of a rectifier tube of the negative winding segment, the positive rectification loop is used for rectifying alternating current in a positive half cycle, the negative rectification loop is used for rectifying alternating current in a negative half cycle, the positive rectification loop and the negative rectification loop share an output bus line drawn from between the negative winding segment and the positive winding segment, and the direct current side of the third conversion circuit serves as a third port connected with a low-voltage battery, wherein the first clamping circuit and the second clamping circuit comprise clamping switch tubes and clamping capacitors arranged in series; when power is transmitted from the first port to the second port, or power is transmitted from the second port to the first port, the clamping switch tubes of the second clamping circuit / first clamping circuit are turned on for a preset time period within the on time period of the upper switch tube / lower switch tube of the fourth bridge arm, so that the energy stored in the clamping capacitors of the second clamping circuit / first clamping circuit is released to the low-voltage battery through the clamping switch tubes of the second clamping circuit / first clamping circuit and the negative winding segment / positive winding segment, so as to reduce the voltage stress of the rectifier tube in the third conversion circuit and realize energy recovery, thereby improving the overall efficiency of the vehicle-mounted charger in the vehicle-mounted three-port converter when the vehicle-mounted charger works alone.

[0065] In the description herein, numerous specific details are provided, such as examples of components and / or methods, to provide a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the application can be practiced without one or more of the specific details, or with other devices, systems, assemblies, methods, components, materials, parts, and / or the like.

[0066] It should also be understood that one or more of the elements illustrated in the figures, or even a subset of the elements, can also be implemented in more separated or even more integrated manners than illustrated. That is, one or more elements depicted as single integrated elements can be implemented as separate elements, and one or more elements depicted as separate elements can be implemented as integrated elements. The same can also apply to other system elements discussed in the disclosure.

[0067] In addition, any arrows in the drawings are merely exemplary and do not limit the scope of the application. Further, unless otherwise indicated, the terms "or" and "and" as used herein are generally intended to mean "and / or" in the absence of a specific indication to the contrary. Combinations of components or steps will also be perceived as being contemplated unless a specific to the contrary is indicated.

[0068] The above description of the illustrated embodiments of the application (including what is in the Abstract) is not intended to be exhaustive or to limit the application to the precise forms disclosed. While specific embodiments of, and examples for, the application are described herein for illustrative purposes, various equivalent modifications are possible within the spirit and scope of the application, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications can be made to the application in light of the foregoing description of the described embodiments of the application and

[0069] The systems and methods have been described generally to facilitate an understanding of the details of the application. Moreover, various specific details have been given for providing a thorough understanding of embodiments of the application. However, one skilled in the relevant art will recognize and appreciate that the application can be practiced without one or more of the specific details, or with other devices, systems, assemblies, methods, components, materials, parts, and the like. In other instances, well-known structures, materials, and / or operations have not been shown or described in detail to avoid obscuring aspects of embodiments of the application.

[0070] Accordingly, although the application has been described herein in reference to specific embodiments thereof, many modifications, alterations and changes can be suggested to one skilled in the art and it is intended to include all such modifications, alterations and changes in the scope of the present application. Accordingly, the scope of the present application is intended to be limited only by the following claims and their equivalents.

Claims

1. A vehicle-mounted three-port converter, characterized by, include: The circuit comprises a first conversion circuit, a second conversion circuit, a third conversion circuit, a first transformer, and a second transformer, wherein the first transformer and the second transformer are independent of each other. The first transformer includes a first winding and a second winding, and the second transformer includes a third winding and a fourth winding, wherein the fourth winding includes a positive winding segment and a negative winding segment connected in series. The first conversion circuit includes a first bridge arm and a second bridge arm. The first winding is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm. The two ends of the first bridge arm and the second bridge arm serve as first ports connected to the power factor correction circuit. The second conversion circuit includes a third bridge arm, a fourth bridge arm, and a fifth bridge arm. The second winding is connected between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm. The third winding is connected between the midpoint of the fourth bridge arm and the midpoint of the fifth bridge arm. The two ends of the third bridge arm, the fourth bridge arm, and the fifth bridge arm serve as second ports for connecting to the high-voltage battery. The third conversion circuit includes a positive rectifier circuit connected to the positive winding section, a negative rectifier circuit connected to the negative winding section, a first clamping circuit connected in parallel to the two ends of the rectifier tube in the positive rectifier circuit, and a second clamping circuit connected in parallel to the two ends of the rectifier tube in the negative winding section. The positive rectifier circuit is used to rectify the AC current in the positive half-cycle, and the negative rectifier circuit is used to rectify the AC current in the negative half-cycle. The positive rectifier circuit and the negative rectifier circuit share an output bus that is led out from between the negative winding section and the positive winding section. The DC side of the third conversion circuit serves as a third port for connection to a low-voltage battery. The first clamping circuit and the second clamping circuit include a clamping switch and a clamping capacitor connected in series. When power is transmitted from the first port to the second port, or from the second port to the first port, the clamping switch of the second clamping circuit / first clamping circuit is controlled to be turned on for a preset period of time during the conduction period of the upper / lower switch of the fourth bridge arm. This releases the energy stored in the clamping capacitor of the second clamping circuit / first clamping circuit to the low-voltage battery through the clamping switch of the second clamping circuit / first clamping circuit and the negative winding section / positive winding section, thereby reducing the voltage stress of the rectifier tube in the third conversion circuit and realizing energy recovery.

2. The on-board three-port converter according to claim 1, characterized in that The third conversion circuit includes an eleventh switching transistor, a twelfth switching transistor, a first clamping switching transistor, a second clamping switching transistor, a first clamping capacitor, a second clamping capacitor, a low-voltage output capacitor, and an output inductor. An input end of the eleventh switch tube, an output end of the first clamping switch tube are commonly connected to a homonymic end of the positive winding section, an input end of the twelfth switch tube and an output end of the second clamping switch tube are commonly connected to a homonymic end of the negative winding section, an input end of the first clamping switch tube is connected to one end of the first clamping capacitor, an input end of the second clamping switch tube is connected to one end of the second clamping capacitor, an output end of the eleventh switch tube, an output end of the twelfth switch tube, the other end of the first clamping capacitor, the other end of the second clamping capacitor and one end of the low-voltage output capacitor are commonly connected to a negative electrode of a low-voltage battery, one end of the output inductor is connected to a homonymic end of the positive winding section and a homonymic end of the negative winding section respectively, the other end of the output inductor and the other end of the low-voltage output capacitor are commonly connected to a positive electrode of the low-voltage battery; When power is transmitted from the first port to the second port or power is transmitted from the second port to the first port, the energy stored in the second clamping capacitor / first clamping capacitor is released to the low-voltage battery through the second clamping switch tube / first clamping switch tube and the negative winding section / positive winding section by controlling the second clamping switch tube / first clamping switch tube to be turned on for a preset time period in the on period of the upper switch tube / lower switch tube of the fourth bridge arm, so as to reduce the voltage stress of the twelfth switch tube / eleventh switch tube and realize energy recovery.

3. The on-board three-port converter according to claim 2, characterized in that The third conversion circuit further comprises a thirteenth switch tube and a fourteenth switch tube; An input end of the thirteenth switch tube is connected to a homonymic end of the positive winding section and a homonymic end of the negative winding section respectively, and an output end of the thirteenth switch tube is connected to a positive electrode of a low-voltage battery through the output inductor; An input end of the fourteenth switch tube is connected between the thirteenth switch tube and the output inductor, and an output end of the fourteenth switch tube is connected to a negative electrode of the low-voltage battery; When power is transmitted from the first port to the second port or power is transmitted from the second port to the first port, the energy stored in the second clamping capacitor / first clamping capacitor is released to the low-voltage battery through the second clamping switch tube / first clamping switch tube and the negative winding section / positive winding section by controlling the thirteenth switch tube to keep in the on state, the fourteenth switch tube to keep in the off state, and the second clamping switch tube / first clamping switch tube to be turned on for a preset time period in the on period of the upper switch tube / lower switch tube of the fourth bridge arm, so as to reduce the voltage stress of the twelfth switch tube / eleventh switch tube and realize energy recovery.

4. The on-board three-port converter according to claim 2, characterized in that, The third conversion circuit further comprises a thirteenth switch tube and a fourteenth switch tube; The other end of the output inductor is connected to an output end of the thirteenth switch tube, and a positive electrode of a low-voltage battery is connected to an input end of the thirteenth switch tube; An input end of the fourteenth switch tube is connected between the thirteenth switch tube and the output inductor, and an output end of the fourteenth switch tube is connected to a negative electrode of the low-voltage battery; When power is transmitted from the first port to the second port, or power is transmitted from the second port to the first port, the fourteenth switch is kept in an off state, and the second clamping switch / first clamping switch is controlled to be turned on for a preset time period during the on period of the upper switch / lower switch of the fourth bridge arm, so as to release the energy stored in the second clamping capacitor / first clamping capacitor to the low-voltage battery through the second clamping switch / first clamping switch and the negative winding segment / positive winding segment, so as to reduce the voltage stress of the twelfth switch / eleventh switch and realize energy recovery.

5. The on-board three-port converter according to claim 1, characterized in that, The turn-on time of the upper switch / lower switch of the fourth bridge arm is the same as the turn-on time of the clamping switch of the second clamping circuit / first clamping circuit.

6. The on-board three-port converter according to claim 1, characterized in that, The turn-on time of the upper switch / lower switch of the fourth bridge arm is different from the turn-on time of the clamping switch of the second clamping circuit / first clamping circuit.

7. The on-board three-port converter according to claim 1, characterized in that, The first conversion circuit further comprises a resonant inductor and a resonant capacitor; the resonant inductor and the resonant capacitor are connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm.

8. The on-board three-port converter according to claim 1, characterized in that, The second conversion circuit further comprises a DC blocking capacitor and a high-voltage output capacitor; the DC blocking capacitor is connected in series between the midpoint of the fourth bridge arm and the second winding; and the high-voltage output capacitor is connected in parallel across the fifth bridge arm.

9. The vehicle-mounted three-port converter according to claim 1, characterized by The preset time period is less than or equal to half of the switching period of the upper switch / lower switch of the fourth bridge arm.

10. The on-board three-port converter according to claim 1, characterized in that, The length of the preset time period is a fixed value or is calculated according to the voltage of the high-voltage battery in a closed-loop manner.

Images