Vehicle-mounted three-port converter control method

Abstract

The application discloses a kind of vehicle-mounted three-port converter control methods, when B port transmits power to C port: the upper bridge of the fourth bridge arm in B port circuit, lower bridge arm switch tube is complementary conduction with 50% duty ratio, the upper, lower bridge arm switch tube of fifth bridge arm is complementary conduction with 50% duty ratio, and the simultaneous conduction time of the upper bridge arm switch tube of fourth bridge arm with the lower bridge arm switch tube of fifth bridge arm and the simultaneous conduction time of the lower arm switch tube of fourth bridge arm with the upper arm switch tube of fifth bridge arm are the same as the zero time length;The upper, lower bridge arm switch tube of third bridge arm is not conducted;And by adjusting the on-off of the bridge arm switch tube of A port circuit, the bus capacitor of A port circuit is discharged to B port in reverse direction, to realize A port voltage reduction.This control method can avoid excessive energy flow to A port, cause A port overvoltage and cause bus capacitor damage.The control method will not produce excessive reactive current, and the influence on power conversion efficiency is smaller.

Description

Technical Field

[0001] This invention relates to circuits, and more particularly to a control method for an on-board three-port converter. Background Technology

[0002] With the rapid development of electric vehicles, on-board chargers (OBC / DCDC), as important components of electric vehicles, are trending towards integration and lower cost. Currently, the industry and universities are exploring more optimized solutions beyond physical integration to reduce size and cost.

[0003] Patent CN107623365A discloses a three-port vehicle charging topology, such as Figure 1 As shown, the on-board charger (OBC) and DC / DC converter are integrated by sharing the transformer core and the high-voltage battery side power switch. However, this integration method uses the shared transformer TX1, and there is magnetic coupling between the OBC and the DC / DC converter. The power cannot be completely decoupled and controlled. For example, when the DC / DC converter is working alone, that is, when the power is transmitted from port B to port C, additional power will be transferred to port A through the transformer TX1, causing overvoltage at port A and damaging the capacitor.

[0004] Patent CN110649813A discloses another three-port vehicle charging topology, such as... Figure 2 As shown, the OBC and DC / DC functions are integrated by sharing the high-voltage battery-side power bridge arm. Compared to Figure 1 The illustrated magnetically integrated three-port topology exhibits no magnetic coupling, resulting in low power coupling and relatively simpler control. When the DC-DC converter is transferring power from port B to port C, port A is an idle port and should not normally experience voltage build-up. Power between ports B and C is transferred via transformer TX2, ideally without coupling to transformer TX1 and then to port A. However, since the switches in this topology all contain parasitic junction capacitance, when switches S7 and S8 in the port B circuit are turned on / off, the midpoint voltage of the bridge arm formed by switches S7 and S8 abruptly changes, causing resonance in the junction capacitances of switches S5 and S6. This resonant voltage is coupled to port A through transformer TX1, causing resonance at the midpoint of the bridge arm in the port A circuit as well. When the resonant voltage at the midpoint of the two bridge arms in the port A circuit exceeds the current bus capacitance C of port A... BUS When the voltage is applied, the body diodes of the switching transistors S1 and S4 or S2 and S3 in the A-port circuit conduct to the A-port bus capacitor C. BUS During charging, the voltage at port A gradually increases. Over a long period, the voltage at port A will eventually exceed the bus capacitor C. BUS The withstand voltage value was insufficient, leading to overvoltage damage. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a control method for an on-board three-port converter, which can avoid excessive energy flow to port A, causing overvoltage at port A and damage to the bus capacitor, and will not generate excessive reactive circulating current, thus having a small impact on power conversion efficiency.

[0006] To solve the above-mentioned technical problems, the present invention provides a vehicle-mounted three-port converter control method. The three-port vehicle-mounted charging circuit includes a first transformer TX1, a second transformer TX2, and A-port circuits, B-port circuits, and C-port circuits. In the A-port circuit, the midpoints of the first and second bridge arms are respectively connected to the two ends of the A-side winding W11 of the first transformer TX1, and the two ends of the first and second bridge arms are respectively connected to the bus capacitor C. BUS At both ends, bus capacitor C BUS Both ends are designated as ports A; in the B-port circuit, the third, fourth, and fifth bridge arms are each connected to the two ends of the high-voltage power battery BATHV and serve as ports B. The midpoint of the fourth bridge arm is connected to the opposite-named terminal of the B-port winding of the first transformer TX1 and the same-named terminal of the B-port winding W21 of the second transformer TX2. The midpoint of the third bridge arm is connected to the same-named terminal of the B-port winding W21 of the second transformer TX2. The midpoint of the fifth bridge arm is connected to the opposite-named terminal of the B-port winding W21 of the second transformer TX2. In the C-port circuit, the input terminal of the rectifier and filter circuit is connected to the C-port winding of the second transformer TX2, and the output terminal serves as port C, outputting a low-voltage operating voltage to the low-voltage battery BATLV. When power is transferred from port B to port C:

[0007] In the B-port circuit, the upper bridge arm switch S7 and the lower bridge arm switch S8 of the fourth bridge arm are complementaryly turned on with a 50% duty cycle, and the upper bridge arm switch S9 and the lower bridge arm switch S10 of the fifth bridge arm are complementaryly turned on with a 50% duty cycle. The simultaneous turn-on time of the upper bridge arm switch S7 of the fourth bridge arm and the lower bridge arm switch S10 of the fifth bridge arm, as well as the simultaneous turn-on time of the lower bridge arm switch S8 of the fourth bridge arm and the upper bridge arm switch S9 of the fifth bridge arm, are both zero duration T0. The upper bridge arm switch S5 and the lower bridge arm switch S6 of the third bridge arm are not turned on. By adjusting the on / off state of the switches of the bridge arms in the A-port circuit, the bus capacitor of the A-port circuit is reversed and discharged to the B-port.

[0008] Preferably, when the B port transfers power to the C port, the period during which the upper-arm switching transistor S1 of the first arm and the lower-arm switching transistor S4 of the second arm of the A-port circuit are simultaneously turned on is within the period during which the upper-arm switching transistor S7 of the fourth arm and the lower-arm switching transistor S10 of the fifth arm are simultaneously turned on; the period during which the upper-arm switching transistor S3 of the second arm and the lower-arm switching transistor S2 of the first arm of the A-port circuit are simultaneously turned on is within the period during which the upper-arm switching transistor S9 of the fifth arm and the lower-arm switching transistor S8 of the fourth arm are simultaneously turned on.

[0009] Preferably, when the B port transfers power to the C port, after the upper-arm switching transistor S7 of the fourth arm and the lower-arm switching transistor S10 of the fifth arm are simultaneously turned on, with a delay of the first time period T1, the upper-arm switching transistor S1 of the first arm and the lower-arm switching transistor S4 of the second arm of the A-port circuit are simultaneously turned on, where T1 < T2 < T0, and T2 is the duration of the period during which the upper-arm switching transistor S1 of the first arm and the lower-arm switching transistor S4 of the second arm of the A-port circuit are simultaneously turned on.

[0010] Preferably, when the B port transfers power to the C port, the phase of the switching transistors of the fourth arm leads or lags behind the phase of the switching transistors of the fifth arm; the time when the upper-arm switching transistor S3 of the second arm and the lower-arm switching transistor S2 of the first arm are simultaneously turned on leads or lags behind the time when the upper-arm switching transistor S1 of the first arm and the lower-arm switching transistor S4 of the second arm are simultaneously turned on by half a cycle, and the duration of the simultaneous turn-on is the same.

[0011] Preferably, the first time period T1 is within the range of 100 ns to 200 ns.

[0012] Preferably, when the B port transfers power to the C port, the upper-arm switching transistor S1 of the first arm and the upper-arm switching transistor S3 of the second arm in the A-port circuit are not turned on, and the lower-arm switching transistor S2 of the first arm and the lower-arm switching transistor S4 of the second arm remain continuously turned on, or the upper-arm switching transistor S1 of the first arm and the upper-arm switching transistor S3 of the second arm in the A-port circuit remain turned on, and the lower-arm switching transistor S2 of the first arm and the lower-arm switching transistor S4 of the second arm remain continuously not turned on.

[0013] Preferably, both ends of the A-side winding W11 of the first transformer TX1 are connected to the midpoints of the first arm and the second arm via a resonant network;

[0014] The resonant network includes a resonant inductor Lr, an exciting inductor Lm, and a resonant capacitor Cr;

[0015] The resonant inductor Lr is connected between one end of the A-side winding W11 of the first transformer TX1 and the midpoint of the first arm;

[0016] The resonant capacitor Cr is connected between the other end of the A-side winding W11 of the first transformer TX1 and the midpoint of the second bridge arm.

[0017] The magnetizing inductor Lm is connected between the two ends of the A-side winding W11 of the first transformer TX1.

[0018] Preferably, a high-voltage capacitor C is connected between the two ends of port B. HV ;

[0019] A DC blocking capacitor C is connected between the B-port winding W21 of the second transformer TX2 and the B-port winding W12 of the first transformer TX1, and the midpoint of the fourth bridge arm. iso ;

[0020] There is a leakage inductance Llk between the midpoint of the fifth bridge arm and the B-port winding W21 of the second transformer TX2.

[0021] Preferably, the C-port winding of the second transformer TX2 includes a first C-port winding W22 and a second C-port winding W23 in positive series.

[0022] The C-port circuit includes a first switching transistor SR1, a second switching transistor SR2, a filter inductor Lo, and a filter capacitor Co;

[0023] The source and drain of the first switching transistor SR1 are connected to the non-series terminal of the second C-port side winding W23 and the negative terminal of the low-voltage battery BATLV, respectively. The source and drain of the second switching transistor SR2 are connected to the non-series terminal of the first C-port side winding W22 and the negative terminal of the low-voltage battery BATLV, respectively.

[0024] The filter inductor Lo is connected in series between the connection point of the first C-port side winding W22 and the second C-port side winding W23 and the positive terminal of the low-voltage battery BATLV.

[0025] The two ends of the filter capacitor Co are connected to the positive and negative terminals of the low-voltage battery BATLV, respectively.

[0026] The vehicle-mounted three-port converter control method of the present invention integrates and multiplexes the secondary side of the high-voltage DC / DC converter and the primary side of the low-voltage DC / DC converter (fourth bridge arm) in the three-port vehicle-mounted charging circuit. When power is transferred from port B to port C, the switches S7 to S10 of the fourth and fifth bridge arms in the B-port circuit operate in phase-shifting mode. That is, the upper bridge arm switch S7 and the lower bridge arm switch S8 of the fourth bridge arm in the B-port circuit are complementaryly turned on with a 50% duty cycle, and the upper bridge arm switch S9 and the lower bridge arm switch S10 of the fifth bridge arm are complementaryly turned on with a 50% duty cycle. Furthermore, the simultaneous turn-on time of the upper bridge arm switch S7 of the fourth bridge arm and the lower bridge arm switch S10 of the fifth bridge arm, as well as the simultaneous turn-on time of the lower bridge arm switch S8 of the fourth bridge arm and the upper bridge arm switch S9 of the fifth bridge arm, are both the same. At zero duration T0, neither the upper bridge arm switch S5 nor the lower bridge arm switch S6 of the third bridge arm is turned on. Simultaneously, the magnitude of the zero duration T0 determines the amount of power transferred from port B to port C. The value of zero duration T0 can be calculated in real-time based on the voltage value at port C using a voltage closed-loop controller. When power is transferred from port B to port C, the conduction mode of the switches in the bridge arms of the A and B ports is adjusted to cause the bus capacitor of the A port circuit to discharge in the reverse direction to port B. This reduces the voltage at port A, preventing excessive energy flow to port A and avoiding overvoltage at port A, which could damage the bus capacitor C. BUS Damage. This control method does not generate excessive reactive circulating current and has a relatively small impact on power conversion efficiency. Attached Figure Description

[0027] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention 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 effort.

[0028] Figure 1 This is a three-port DC / DC topology diagram disclosed in Chinese patent document CN107623365A;

[0029] Figure 2 This is a three-port DC / DC topology diagram disclosed in Chinese patent document CN110649813A;

[0030] Figure 3 This is a topology diagram of a three-port vehicle charging circuit according to an embodiment of the vehicle-mounted three-port converter control method of the present invention;

[0031] Figure 4 This is the driving timing sequence of the switching transistors of each bridge arm of the A-port circuit and the B-port circuit in an embodiment of the vehicle-mounted three-port converter control method of the present invention.

[0032] Figure 5a This is the current path during the S1 / S4 conduction period of the A-port circuit in an embodiment of the vehicle-mounted three-port converter control method of the present invention;

[0033] Figure 5b This is the discharge path during the S2 / S3 conduction period of the A-port circuit in an embodiment of the vehicle-mounted three-port converter control method of the present invention;

[0034] Figure 6 This is the driving timing sequence of the switching transistors of each bridge arm of the A-port circuit and B-port circuit in another embodiment of the vehicle-mounted three-port converter control method of the present invention.

[0035] Figure 7 This is the current path of the vehicle-mounted three-port converter control method of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The terms "first," "second," and similar words used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Words such as "including" or "comprising" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0040] Example 1

[0041] Control methods for on-board three-port converters, such as Figure 3As shown, the three-port on-board charging circuit includes a first transformer TX1, a second transformer TX2, and A-port, B-port, and C-port circuits. The A-port circuit has its first and second bridge arms connected to the two ends of the A-side winding W11 of the first transformer TX1, respectively, and its first and second bridge arms connected to the bus capacitor C. BUS At both ends, bus capacitor C BUS Both ends are designated as ports A (AC ports); the B port circuit has its third, fourth, and fifth bridge arms connected to the two ends of the high-voltage (above 100V) power battery BATHV and serving as ports B (high-voltage ports). The midpoint of the fourth bridge arm is connected to the opposite-named terminal of the B port winding of the first transformer TX1 and the same-named terminal of the B port winding W21 of the second transformer TX2. The midpoint of the third bridge arm is connected to the same-named terminal of the B port winding W21 of the second transformer TX2. The midpoint of the fifth bridge arm is connected to the opposite-named terminal of the B port winding W21 of the second transformer TX2. The C port circuit has its rectifier and filter circuit input connected to the C port winding of the second transformer TX2, and outputs a low-voltage operating voltage (below 50V) to the low-voltage battery BATLV (low-voltage port).

[0042] When power is transferred from port B to port C:

[0043] In the B-port circuit, the upper bridge arm switch S7 and the lower bridge arm switch S8 of the fourth bridge arm are complementaryly turned on with a 50% duty cycle, and the upper bridge arm switch S9 and the lower bridge arm switch S10 of the fifth bridge arm are complementaryly turned on with a 50% duty cycle. The simultaneous turn-on time of the upper bridge arm switch S7 of the fourth bridge arm and the lower bridge arm switch S10 of the fifth bridge arm, as well as the simultaneous turn-on time of the lower bridge arm switch S8 of the fourth bridge arm and the upper bridge arm switch S9 of the fifth bridge arm, are both zero duration T0. The upper bridge arm switch S5 and the lower bridge arm switch S6 of the third bridge arm are not turned on. By adjusting the on / off state of the switches of the bridge arms in the A-port circuit, the bus capacitor of the A-port circuit discharges in reverse to the B-port, thereby reducing the voltage at the A-port.

[0044] The on-vehicle three-port converter control method of Embodiment 1 integrates and multiplexes the secondary side of a high-voltage DC / DC and the primary circuit (the fourth bridge arm) of a low-voltage DC / DC. When the B port transfers power to the C port, the switching tubes S7 to S10 of the fourth bridge arm and the fifth bridge arm in the B-port circuit operate in a phase-shift mode. That is, in the fourth bridge arm in the B-port circuit, the upper-bridge-arm switching tube S7 and the lower-bridge-arm switching tube S8 are complementarily turned on with a 50% duty cycle. In the fifth bridge arm, the upper-bridge-arm switching tube S9 and the lower-bridge-arm switching tube S10 are complementarily turned on with a 50% duty cycle. Also, the simultaneous conduction time of the upper-bridge-arm switching tube S7 of the fourth bridge arm and the lower-bridge-arm switching tube S10 of the fifth bridge arm, as well as the simultaneous conduction time of the lower-arm switching tube S8 of the fourth bridge arm and the upper-bridge-arm switching tube S9 of the fifth bridge arm, are both the zero-duration T0. The upper-bridge-arm switching tube S5 and the lower-bridge-arm switching tube S6 of the third bridge arm are both not turned on. The magnitude of the zero-duration T0 determines the amount of power transferred from the B port to the C port. The value of the zero-duration T0 can be calculated in real time by a voltage closed-loop controller based on the voltage value of the C port. When transferring power from the B port to the C port, by adjusting the conduction modes of the switching tubes of the bridge arms of the A-port circuit and the B-port circuit, the bus capacitor of the A-port circuit discharges in the reverse direction to the B port, thereby reducing the voltage of the A port and avoiding excessive energy flowing to the A port, which may cause overvoltage of the A port and damage the bus capacitor C BUS from being damaged. This control method does not generate excessive reactive circulating current and has a relatively small impact on the power conversion efficiency.

[0045] Embodiment 2

[0046] Based on the on-vehicle three-port converter control method of Embodiment 1, when the B port transfers power to the C port, as Figure 4 shown, the period during which the upper-bridge-arm switching tube S1 of the first bridge arm of the A-port circuit and the lower-bridge-arm switching tube S4 of the second bridge arm are simultaneously turned on is within the period during which the upper-bridge-arm switching tube S7 of the fourth bridge arm and the lower-bridge-arm switching tube S10 of the fifth bridge arm are simultaneously turned on, that is, T2 < T0, where T2 is the duration during which the upper-bridge-arm switching tube S1 of the first bridge arm of the A-port circuit and the lower-bridge-arm switching tube S4 of the second bridge arm are simultaneously turned on; the period during which the upper-bridge-arm switching tube S3 of the second bridge arm of the A-port circuit and the lower-bridge-arm switching tube S2 of the first bridge arm are simultaneously turned on is within the period during which the upper-bridge-arm switching tube S9 of the fifth bridge arm and the lower-bridge-arm switching tube S8 of the fourth bridge arm are simultaneously turned on.

[0047] Preferably, when the B port transfers power to the C port, after the upper-arm switch S7 of the fourth bridge arm and the lower-arm switch S10 of the fifth bridge arm are turned on simultaneously, after a first time period T1 (where T1 < T2 < T0), the upper-arm switch S1 of the first bridge arm and the lower-arm switch S4 of the second bridge arm of the A-port circuit are turned on simultaneously, so that the upper-arm switch S1 of the first bridge arm and the lower-arm switch S4 of the second bridge arm are turned on near zero voltage. Preferably, the first time period T1 is within the range of 100 ns to 200 ns.

[0048] Preferably, when the B port transfers power to the C port, the phase of the switch of the fourth bridge arm is advanced or delayed relative to the switch of the fifth bridge arm; the time when the upper-arm switch S3 of the second bridge arm and the lower-arm switch S2 of the first bridge arm are turned on simultaneously is delayed or advanced by half a cycle relative to the time when the upper-arm switch S1 of the first bridge arm and the lower-arm switch S4 of the second bridge arm are turned on simultaneously, and the conduction time periods are the same.

[0049] Preferably, the time when the upper-arm switch S3 of the second bridge arm and the lower-arm switch S2 of the first bridge arm are turned on simultaneously is delayed by half a cycle relative to the time when the upper-arm switch S1 of the first bridge arm and the lower-arm switch S4 of the second bridge arm are turned on simultaneously.

[0050] For the vehicle-mounted three-port converter control method of the second embodiment, the switches of the first bridge arm and the second bridge arm of the A-port circuit operate in a symmetric PWM mode. The time period T2 when the upper-arm switch S1 of the first bridge arm and the lower-arm switch S4 of the second bridge arm of the A-port circuit are turned on simultaneously is within the time period T0 when the upper-arm switch S7 of the fourth bridge arm and the lower-arm switch S10 of the fifth bridge arm are turned on simultaneously. During the time period T2 when the upper-arm switch S1 of the first bridge arm and the lower-arm switch S4 of the second bridge arm of the A-port circuit are turned on simultaneously, the bus capacitor C of the A-port circuit BUS discharges in the reverse direction to the B port to reduce the voltage of the A port. The magnitude of the time period T2 can be calculated in real time by the A-port voltage control loop or set as a fixed value in an open-loop manner. The larger the value of the time period T2, the bus capacitor C BUS has a longer discharge time, that is, the finally stabilized voltage of the A port will be lower. Figures 5(a) and 5(b) show schematic diagrams of the current paths during the time period T2 of this vehicle-mounted three-port converter control method. As can be seen from Figure 5(a), during the time period T2 when the upper-arm switch S1 of the first bridge arm and the lower-arm switch S4 of the second bridge arm of the A-port circuit are turned on simultaneously, the channels of the upper-arm switch S1 of the first bridge arm and the lower-arm switch S4 of the second bridge arm of the A-port circuit, and the body diode of the upper-arm switch S5 of the third bridge arm and the channel of the upper-arm switch S7 of the fourth bridge arm of the B-port circuit form the bus capacitor C BUSThe discharge path; as shown in Figure 5(b), during the time period when the upper bridge arm switch S3 of the second bridge arm and the lower bridge arm switch S2 of the first bridge arm of the A-port circuit are simultaneously turned on, the channels of the upper bridge arm switch S3 of the second bridge arm and the lower bridge arm switch S2 of the first bridge arm of the A-port circuit, as well as the body diode of the lower bridge arm switch S6 of the third bridge arm and the channel of the lower bridge arm switch S8 of the fourth bridge arm of the B-port circuit, form the bus capacitor C. BUS The discharge path is optimized to prevent the continuous rise of the voltage at port A from affecting the bus capacitor C. BUS Caused damage.

[0051] Example 3

[0052] Based on the vehicle-mounted three-port converter control method of Embodiment 1, when power is transferred from port B to port C, the upper bridge arm switch S1 of the first bridge arm and the upper bridge arm switch S3 of the second bridge arm in the circuit of port A are not turned on, while the lower bridge arm switch S2 of the first bridge arm and the lower bridge arm switch S4 of the second bridge arm remain continuously turned on; or, the upper bridge arm switch S1 of the first bridge arm and the upper bridge arm switch S3 of the second bridge arm in the circuit of port A remain turned on, while the lower bridge arm switch S2 of the first bridge arm and the lower bridge arm switch S4 of the second bridge arm remain continuously turned off.

[0053] In the vehicle-mounted three-port converter control method of Example 3, when power is transferred from port B to port C, the midpoint of the two bridge arms of the circuit at port A is short-circuited, thereby cutting off the flow to the bus capacitor C at port A. BUS The current path. For example... Figure 6 As shown, a short circuit at the midpoint of the two bridge arms in the A-port circuit cuts off the current path to the A-port bus capacitor. Figure 7 As shown, since the lower bridge arm switch S2 of the first bridge arm and the lower bridge arm switch S4 of the second bridge arm remain continuously conducting, no current flows into the bus capacitor at port A. Furthermore, since the upper bridge arm switch S5 and the lower bridge arm switch S6 of the third bridge arm are not conducting, power does not flow from port B into port A. Therefore, the circulating current generated by this method of short-circuiting the midpoint of the two bridge arms in the port A circuit of Embodiment 3 is very small and has virtually no impact on the switching efficiency between ports B and C.

[0054] Example 4

[0055] Based on the vehicle-mounted three-port converter control method of Embodiment 1, the two ends of the A-side winding W11 of the first transformer TX1 are connected to the midpoint of the first bridge arm and the midpoint of the second bridge arm via a resonant network.

[0056] The resonant network includes the resonant inductor Lr, the magnetizing inductor Lm, and the resonant capacitor Cr;

[0057] The resonant inductor Lr is connected between one end of the A-side winding W11 of the first transformer TX1 and the midpoint of the first bridge arm.

[0058] The resonant capacitor Cr is connected between the other end of the A-side winding W11 of the first transformer TX1 and the midpoint of the second bridge arm.

[0059] The magnetizing inductor Lm is connected between the two ends of the A-side winding W11 of the first transformer TX1.

[0060] Preferably, a high-voltage capacitor C is connected between the two ends of port B. HV ;

[0061] A DC blocking capacitor C is connected between the B-port winding W21 of the second transformer TX2 and the B-port winding W12 of the first transformer TX1, and the midpoint of the fourth bridge arm. iso ;

[0062] There is a leakage inductance Llk between the midpoint of the fifth bridge arm and the B-port winding W21 of the second transformer TX2.

[0063] Preferably, the C-port winding of the second transformer TX2 includes a first C-port winding W22 and a second C-port winding W23 in positive series.

[0064] The C-port circuit includes a first switching transistor SR1, a second switching transistor SR2, a filter inductor Lo, and a filter capacitor Co;

[0065] The source and drain of the first switching transistor SR1 are connected to the non-series terminal of the second C-port side winding W23 and the negative terminal of the low-voltage battery BATLV, respectively. The source and drain of the second switching transistor SR2 are connected to the non-series terminal of the first C-port side winding W22 and the negative terminal of the low-voltage battery BATLV, respectively.

[0066] The filter inductor Lo is connected in series between the connection point of the first C-port side winding W22 and the second C-port side winding W23 and the positive terminal of the low-voltage battery BATLV.

[0067] The two ends of the filter capacitor Co are connected to the positive and negative terminals of the low-voltage battery BATLV, respectively.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control method for an on-board three-port converter, wherein the three-port on-board charging circuit includes a first transformer (TX1), a second transformer (TX2), and A-port circuit, B-port circuit, and C-port circuit; wherein the midpoint of the first bridge arm and the midpoint of the second bridge arm of the A-port circuit are respectively connected to the two ends of the A-side winding (W11) of the first transformer (TX1), and the two ends of the first bridge arm and the second bridge arm are respectively connected to the bus capacitor (C). BUS At both ends, the bus capacitor (C) BUS The circuit is characterized by the following: The first transformer (TX1) has its third, fourth, and fifth bridge arms connected to the two ends of the high-voltage power battery (BATHV) and serving as B ports. The midpoint of the fourth bridge arm is connected to the opposite-named terminal of the B-port winding of the first transformer (TX1) and the same-named terminal of the B-port winding (W21) of the second transformer (TX2). The midpoint of the third bridge arm is connected to the same-named terminal of the B-port winding (W21) of the second transformer (TX2). The midpoint of the fifth bridge arm is connected to the opposite-named terminal of the B-port winding (W21) of the second transformer (TX2). The second transformer (TX2) has its C-port circuit, where the input terminal of the rectifier and filter circuit is connected to the C-port winding of the second transformer (TX2), and the output terminal serves as the C port to output a low-voltage operating voltage to the low-voltage battery (BATLV). When the B port transfers power to the C port: When the B port transfers power to the C port, the upper-arm switching transistor (S7) and the lower-arm switching transistor (S8) of the fourth leg in the B-port circuit conduct complementary with a duty cycle of 50%, and the upper-arm switching transistor (S9) and the lower-arm switching transistor (S10) of the fifth leg conduct complementary with a duty cycle of 50%. Also, the simultaneous conduction time of the upper-arm switching transistor (S7) of the fourth leg and the lower-arm switching transistor (S10) of the fifth leg, and the simultaneous conduction time of the lower-arm switching transistor (S8) of the fourth leg and the upper-arm switching transistor (S9) of the fifth leg are both the zero-duration T0. The upper-arm switching transistor (S5) and the lower-arm switching transistor (S6) of the third leg are both non-conductive. And by adjusting the on / off of the switching transistors of the legs in the A-port circuit, the bus capacitor of the A-port circuit discharges in the reverse direction to the B port; When the B port transfers power to the C port, the period during which the upper-arm switching transistor (S1) of the first leg and the lower-arm switching transistor (S4) of the second leg in the A-port circuit conduct simultaneously is within the period during which the upper-arm switching transistor (S7) of the fourth leg and the lower-arm switching transistor (S10) of the fifth leg conduct simultaneously. The period during which the upper-arm switching transistor (S3) of the second leg and the lower-arm switching transistor (S2) of the first leg in the A-port circuit conduct simultaneously is within the period during which the upper-arm switching transistor (S9) of the fifth leg and the lower-arm switching transistor (S8) of the fourth leg conduct simultaneously.

2. The vehicle-mounted three-port converter control method according to claim 1, wherein: When the B port transfers power to the C port, after the simultaneous conduction of the upper-arm switching transistor (S7) of the fourth leg and the lower-arm switching transistor (S10) of the fifth leg starts, with a delay of the first duration T1, the upper-arm switching transistor (S1) of the first leg and the lower-arm switching transistor (S4) of the second leg in the A-port circuit are made to conduct simultaneously, where T1 < T2 < T0, and T2 is the duration of the period during which the upper-arm switching transistor (S1) of the first leg and the lower-arm switching transistor (S4) of the second leg in the A-port circuit conduct simultaneously.

3. The vehicle-mounted three-port converter control method according to claim 2, wherein: When the B port transfers power to the C port, the phase of the switching transistors of the fourth leg is advanced or retarded with respect to the switching transistors of the fifth leg; the time when the upper-arm switching transistor (S3) of the second leg and the lower-arm switching transistor (S2) of the first leg conduct simultaneously is retarded or advanced by half a cycle with respect to the time when the upper-arm switching transistor (S1) of the first leg and the lower-arm switching transistor (S4) of the second leg conduct simultaneously, and the duration of the simultaneous conduction is the same.

4. The vehicle-mounted three-port converter control method according to claim 1, wherein: When power is transferred from port B to port C, the upper bridge arm switch (S1) of the first bridge arm and the upper bridge arm switch (S3) of the second bridge arm in the circuit of port A are not turned on, and the lower bridge arm switch (S2) of the first bridge arm and the lower bridge arm switch (S4) of the second bridge arm remain turned on. Alternatively, the upper bridge arm switch (S1) of the first bridge arm and the upper bridge arm switch (S3) of the second bridge arm in the circuit of port A remain turned on, and the lower bridge arm switch (S2) of the first bridge arm and the lower bridge arm switch (S4) of the second bridge arm remain turned off.

5. The vehicle-mounted three-port converter control method according to claim 1, characterized in that, The two ends of the A-side winding (W11) of the first transformer (TX1) are connected to the midpoint of the first bridge arm and the midpoint of the second bridge arm via a resonant network; The resonant network includes a resonant inductor (Lr), a magnetizing inductor (Lm), and a resonant capacitor (Cr). The resonant inductor (Lr) is connected between one end of the A-side winding (W11) of the first transformer (TX1) and the midpoint of the first bridge arm; The resonant capacitor (Cr) is connected between the other end of the A-side winding (W11) of the first transformer (TX1) and the midpoint of the second bridge arm. The magnetizing inductor (Lm) is connected between the two ends of the A-side winding (W11) of the first transformer (TX1).

6. The vehicle-mounted three-port converter control method according to claim 1, characterized in that, A high-voltage capacitor (C) is connected between the two ends of port B. HV ); A DC blocking capacitor (C) is connected between the B-port winding (W21) of the second transformer (TX2) and the B-port winding (W12) of the first transformer (TX1) and the midpoint of the fourth bridge arm. iso ); There is leakage inductance (Llk) between the midpoint of the fifth bridge arm and the B-port winding (W21) of the second transformer (TX2).

7. The vehicle-mounted three-port converter control method according to claim 1, characterized in that, The C-port winding of the second transformer (TX2) includes a first C-port winding (W22) and a second C-port winding (W23) in positive series. The C-port circuit includes a first switching transistor (SR1), a second switching transistor (SR2), a filter inductor (Lo), and a filter capacitor (Co); The source and drain of the first switching transistor (SR1) are connected to the non-series terminal of the second C-port side winding (W23) and the negative terminal of the low-voltage battery (BATLV), respectively. The source and drain of the second switching transistor (SR2) are connected to the non-series terminal of the first C-port side winding (W22) and the negative terminal of the low-voltage battery (BATLV), respectively. The filter inductor (Lo) is connected in series between the connection point of the first C-port side winding (W22) and the second C-port side winding (W23) and the positive terminal of the low-voltage battery (BATLV); The two ends of the filter capacitor (Co) are connected to the positive and negative terminals of the low-voltage battery (BATLV).

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