Voltage conversion circuit, charging station, and control method for charging station

Abstract

Provided in the present disclosure are a voltage conversion circuit, a charging station, and a control method for a charging station. The voltage conversion circuit comprises a transformer and a change-over switch module, wherein the transformer comprises a primary-side winding, a secondary-side winding and a free winding; the switch module comprises a primary-side change-over switch and a secondary-side change-over switch; a first end of the primary-side winding is used for connecting to an inverter circuit, and a second end of the primary-side winding is connected to the free winding or the inverter circuit by means of the primary-side change-over switch; a first end of the secondary-side winding is used for connecting to a rectifier circuit, and a second end of the secondary-side winding is connected to the free winding or the rectifier circuit by means of the secondary-side change-over switch; and by means of adjusting a connection state between the primary-side change-over switch and the secondary-side change-over switch, the free winding and the primary-side winding are connected in series, or the free winding and the secondary-side winding are connected in series, so as to change the turn ratio of the transformer. In the embodiments of the present disclosure, by means of controlling the states of switches, the turn ratio of a primary side to a secondary side of the transformer is bidirectionally changed in a low-cost manner, thereby expanding the output voltage range of the voltage conversion circuit.

Description

A variable voltage circuit, a charging pile and a control method of the charging pile

[0001] The present disclosure claims priority to the Chinese Patent Publication No. 202410741792.1, published on June 07, 2024, with the title of "A variable voltage circuit, a charging pile and a control method of the charging pile", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of transformers, and in particular to a variable voltage circuit, a charging pile and a control method of the charging pile. BACKGROUND

[0003] With the large-scale development of electric vehicles, even the same brand of electric vehicles have different requirements for charging voltage, and the requirements for charging piles are also increasing.

[0004] To meet the requirements of various electric vehicles for charging voltage, under the condition that the input power is given, the charging pile needs to convert the input voltage into charging voltage of different values. Therefore, the voltage output range of the variable voltage circuit inside the charging pile is crucial. SUMMARY

[0005] Based on the above problems, the present disclosure provides a variable voltage circuit, a charging pile and a control method of the charging pile, which provides a wider output voltage range to meet the requirements of various types of electronic devices for charging voltage.

[0006] In a first aspect, the present disclosure provides a variable voltage circuit, comprising: a transformer and a switching switch module; the transformer comprises a primary winding, a secondary winding and a free winding; the switching switch module comprises a primary switching switch and a secondary switching switch; a first end of the primary winding is used to connect an inverter circuit, a second end of the primary winding is connected to the free winding or the inverter circuit through the primary switching switch; a first end of the secondary winding is used to connect a rectifier circuit, a second end of the secondary winding is connected to the free winding or the rectifier circuit through the secondary switching switch; wherein by adjusting the connection state of the primary switching switch and the secondary switching switch, the free winding is connected in series with the primary winding, or the free winding is connected in series with the secondary winding, so as to change the turns ratio of the transformer.

[0007] In one implementation, in the case that the second end of the primary winding is connected to the free winding through the primary switching switch, and the second end of the secondary winding is connected to the rectifier circuit through the secondary switching switch, the free winding is connected in series with the primary winding.

[0008] In one implementation, in the case that the second end of the primary winding is connected to the inverter circuit through the primary switching switch, and the second end of the secondary winding is connected to the free winding through the secondary switching switch, the free winding is connected in series with the secondary winding.

[0009] In one implementation, the turns ratio of the transformer remains unchanged when the second end of the primary winding is connected to the inverter circuit through the primary switch, and the second end of the secondary winding is connected to the rectifier circuit through the secondary switch.

[0010] In one implementation, the primary switch and the secondary switch are a first single-pole double-throw switch and a second single-pole double-throw switch, respectively; the first end of the first single-pole double-throw switch is connected to the second end of the primary winding, and the second end of the first single-pole double-throw switch provides a first connection point and a second connection point; wherein the first connection point is used to connect the inverter circuit, and the second connection point is connected to the free winding; the first end of the second single-pole double-throw switch is connected to the second end of the secondary winding, and the second end of the second single-pole double-throw switch provides a third connection point and a fourth connection point; wherein the third connection point is used to connect the rectifier circuit, and the fourth connection point is connected to the free winding; when the first end of the first single-pole double-throw switch is connected to the second connection point, and the first end of the second single-pole double-throw switch is connected to the third connection point, the primary winding is connected in series with the free winding; when the first end of the first single-pole double-throw switch is connected to the first connection point, and the first end of the second single-pole double-throw switch is connected to the fourth connection point, the secondary winding is connected in series with the free winding; when the first end of the first single-pole double-throw switch is connected to the first connection point, and the first end of the second single-pole double-throw switch is connected to the third connection point, the turns ratio of the transformer remains unchanged.

[0011] In one implementation, the primary switch and the secondary switch are a first switch group and a second switch group, respectively; the first switch of the first switch group is connected to the second end of the primary winding and the inverter circuit, and the second switch of the first switch group is connected to the second end of the primary winding and the free winding; the first switch of the second switch group is connected to the second end of the secondary winding and the rectifier circuit, and the second switch of the second switch group is connected to the second end of the secondary winding and the free winding; when the first switch of the first switch group is open, and the second switch of the first switch group is closed, and the first switch of the second switch group is closed, and the second switch of the second switch group is open, the primary winding is connected in series with the free winding; when the first switch of the first switch group is closed, and the second switch of the first switch group is open, and the first switch of the second switch group is open, and the second switch of the second switch group is closed, the secondary winding is connected in series with the free winding; when the first switch of the first switch group is closed, and the second switch of the first switch group is open, and the first switch of the second switch group is closed, and the second switch of the second switch group is open, the turns ratio of the transformer remains unchanged.

[0012] In one implementation, the transformer circuit includes three transformers, three first single-pole double-throw switches and three second single-pole double-throw switches; first ends of each first single-pole double-throw switch are connected to second ends of corresponding primary windings, respectively, second ends of each first single-pole double-throw switch provide first connection points and second connection points, respectively; wherein the first connection points are connected to each other, the second connection points are connected to first ends of corresponding free windings, respectively; first ends of each second single-pole double-throw switch are connected to second ends of corresponding secondary windings, respectively, second ends of each second single-pole double-throw switch provide third connection points and fourth connection points, respectively; wherein the third connection points are connected to each other, the fourth connection points are connected to first ends of corresponding free windings, respectively; second ends of each free winding are connected to each other; first ends of each first single-pole double-throw switch are connected to the second connection points, respectively, first ends of each second single-pole double-throw switch are connected to the third connection points, respectively, each free winding is connected in series with the corresponding primary winding; first ends of each first single-pole double-throw switch are connected to the first connection points, respectively, first ends of each second single-pole double-throw switch are connected to the fourth connection points, respectively, each free winding is connected in series with the corresponding secondary winding; first ends of each first single-pole double-throw switch are connected to the first connection points, respectively, first ends of each second single-pole double-throw switch are connected to the third connection points, respectively, and turns ratios of the transformers remain unchanged.

[0013] In one implementation, the transformer circuit includes three transformers, three first switch groups and three second switch groups; first ends of first switches of each first switch group are connected to second ends of corresponding primary windings, respectively, second ends of the first switches of the first switch groups are connected to each other, first ends of second switches of each first switch group are connected to second ends of corresponding primary windings, respectively, and second ends of the second switches of each first switch group are connected to first ends of corresponding free windings, respectively; first ends of first switches of each second switch group are connected to second ends of corresponding secondary windings, respectively, second ends of the first switches of the second switch groups are connected to each other, first ends of second switches of each second switch group are connected to second ends of corresponding secondary windings, respectively, and second ends of the second switches of each second switch group are connected to first ends of corresponding free windings, respectively; second ends of each free winding are connected to each other; the first switches of each first switch group are turned off and the second switches of each first switch group are turned on, the first switches of each second switch group are turned on and the second switches of each second switch group are turned off, and each free winding is connected in series with the corresponding primary winding; the first switches of each first switch group are turned on and the second switches of each first switch group are turned off, the first switches of each second switch group are turned off and the second switches of each second switch group are turned on, and each free winding is connected in series with the corresponding secondary winding; the first switches of each first switch group are turned on and the second switches of each first switch group are turned off, the first switches of each second switch group are turned on and the second switches of each second switch group are turned off, and turns ratios of the transformers remain unchanged.

[0014] In a second aspect, the embodiments of the present disclosure provide a charging pile, which includes an inverter circuit, a rectifier circuit and the transformer circuit in the foregoing embodiments.

[0015] In a third aspect, the embodiments of the present disclosure provide a control method of a charging pile, the charging pile comprising an inverter circuit, a rectifier circuit and the transformer circuit in the foregoing embodiments, and the method comprises: acquiring an output voltage of the rectifier circuit; and controlling connection states of the primary side switching switch and the secondary side switching switch according to the output voltage of the rectifier circuit, so as to connect the free winding with the primary winding in series or connect the free winding with the secondary winding in series, so as to change the turns ratio of the transformer.

[0016] In an implementation, the connection states of the primary side switching switch and the secondary side switching switch are controlled so as to connect the free winding with the primary winding in series or connect the free winding with the secondary winding in series, and specifically comprises: controlling the second end of the primary winding to be connected with the free winding through the primary side switching switch and the second end of the secondary winding to be connected with the rectifier circuit through the secondary side switching switch, so as to connect the free winding with the primary winding in series; or controlling the second end of the primary winding to be connected with the inverter circuit through the primary side switching switch and the second end of the secondary winding to be connected with the free winding through the secondary side switching switch, so as to connect the free winding with the secondary winding in series.

[0017] In an implementation, the control method of the charging pile further comprises: controlling the second end of the primary winding to be connected with the inverter circuit through the primary side switching switch and the second end of the secondary winding to be connected with the rectifier circuit through the secondary side switching switch, so that the turns ratio of the transformer remains unchanged.

[0018] In an implementation, the primary side switching switch and the secondary side switching switch are respectively a first single-pole double-throw switch and a second single-pole double-throw switch; wherein the first end of the first single-pole double-throw switch is connected with the second end of the primary winding, and the second end of the first single-pole double-throw switch provides a first connection point and a second connection point; wherein the first connection point is used for connecting the inverter circuit, and the second connection point is connected with the free winding; the first end of the second single-pole double-throw switch is connected with the second end of the secondary winding, and the second end of the second single-pole double-throw switch provides a third connection point and a fourth connection point; wherein the third connection point is used for connecting the rectifier circuit, and the fourth connection point is connected with the free winding.

[0019] The connection states of the primary side switching switch and the secondary side switching switch are controlled so as to connect the free winding with the primary winding in series or connect the free winding with the secondary winding in series, and specifically comprises: controlling the first end of the first single-pole double-throw switch to be connected with the second connection point and the first end of the second single-pole double-throw switch to be connected with the third connection point, so as to connect the primary winding with the free winding in series; or controlling the first end of the first single-pole double-throw switch to be connected with the first connection point and the first end of the second single-pole double-throw switch to be connected with the fourth connection point, so as to connect the secondary winding with the free winding in series; or controlling the first end of the first single-pole double-throw switch to be connected with the first connection point and the first end of the second single-pole double-throw switch to be connected with the third connection point, so as to keep the turns ratio of the transformer unchanged.

[0020] In one implementation, the primary side switching switch and the secondary side switching switch are respectively a first switch group and a second switch group; wherein a first switch of the first switch group is connected to the second end of the primary side winding and the inverter circuit, a second switch of the first switch group is connected to the second end of the primary side winding and the free winding; a first switch of the second switch group is connected to the second end of the secondary side winding and the rectifier circuit, a second switch of the second switch group is connected to the second end of the secondary side winding and the free winding.

[0021] The connection state of the primary side switching switch and the secondary side switching switch is controlled to make the free winding in series with the primary side winding, or make the free winding in series with the secondary side winding, specifically including: controlling the first switch of the first switch group to be open, the second switch of the first switch group to be closed, the first switch of the second switch group to be closed, and the second switch of the second switch group to be open, so as to make the primary side winding in series with the free winding; or, controlling the first switch of the first switch group to be closed, the second switch of the first switch group to be open, the first switch of the second switch group to be open, and the second switch of the second switch group to be closed, so as to make the secondary side winding in series with the free winding; or, controlling the first switch of the first switch group to be closed, the second switch of the first switch group to be open, the first switch of the second switch group to be closed, and the second switch of the second switch group to be open, so as to make the turns ratio of the transformer remain unchanged.

[0022] In one implementation, the transformer circuit includes: three transformers, three first single-pole double-throw switches and three second single-pole double-throw switches; wherein the first end of each first single-pole double-throw switch is connected to the second end of the corresponding primary side winding, and the second end of each first single-pole double-throw switch provides a first connection point and a second connection point; wherein each first connection point is connected to each other, and each second connection point is connected to the first end of the corresponding free winding; the first end of each second single-pole double-throw switch is connected to the second end of the corresponding secondary side winding, and the second end of each second single-pole double-throw switch provides a third connection point and a fourth connection point; wherein each third connection point is connected to each other, and each fourth connection point is connected to the first end of the corresponding free winding; and the second end of each free winding is connected to each other.

[0023] The connection state of the primary side switching switch and the secondary side switching switch is controlled to make the free winding in series with the primary side winding, or make the free winding in series with the secondary side winding, specifically including: controlling the first end of each first single-pole double-throw switch to be connected to the second connection point, and the first end of each second single-pole double-throw switch to be connected to the third connection point, so as to make each free winding in series with the corresponding primary side winding; or, controlling the first end of each first single-pole double-throw switch to be connected to the first connection point, and the first end of each second single-pole double-throw switch to be connected to the fourth connection point, so as to make each free winding in series with the corresponding secondary side winding; or, controlling the first end of each first single-pole double-throw switch to be connected to the first connection point, the first end of each second single-pole double-throw switch to be connected to the third connection point, and the turns ratio of each transformer to remain unchanged.

[0024] In one implementation, the voltage transformation circuit includes three transformers, three first switch groups and three second switch groups; wherein the first ends of the first switches of each first switch group are respectively connected to the second ends of corresponding primary windings, the second ends of the first switches of the first switch groups are connected to each other, the first ends of the second switches of each first switch group are respectively connected to the second ends of corresponding primary windings, and the second ends of the second switches of each first switch group are respectively connected to the first ends of corresponding free windings; the first ends of the first switches of each second switch group are respectively connected to the second ends of corresponding secondary windings, the second ends of the first switches of the second switch groups are connected to each other, the first ends of the second switches of each second switch group are respectively connected to the second ends of corresponding secondary windings, and the second ends of the second switches of each second switch group are respectively connected to the first ends of corresponding free windings; and the second ends of the free windings are connected to each other.

[0025] The connection states of the primary side switching switches and the secondary side switching switches are controlled to connect the free windings in series with the primary windings or to connect the free windings in series with the secondary windings, and specifically includes: controlling the first switches of each first switch group to be turned off and the second switches of each first switch group to be turned on, and controlling the first switches of each second switch group to be turned on and the second switches of each second switch group to be turned off, so as to connect each free winding in series with a corresponding primary winding; or, controlling the first switches of each first switch group to be turned on and the second switches of each first switch group to be turned off, and controlling the first switches of each second switch group to be turned off and the second switches of each second switch group to be turned on, so as to connect each free winding in series with a corresponding secondary winding; or, controlling the first switches of each first switch group to be turned on and the second switches of each first switch group to be turned off, and controlling the first switches of each second switch group to be turned on and the second switches of each second switch group to be turned off, and keeping the turns ratio of each transformer unchanged.

[0026] The voltage transformation circuit in the embodiments of the present disclosure includes a transformer and a switching switch module; the transformer includes a primary winding, a secondary winding and a free winding; the switching switch module includes a primary side switching switch and a secondary side switching switch; the first end of the primary winding is used to connect an inverter circuit, and the second end of the primary winding is connected to the free winding or the inverter circuit through the primary side switching switch; the first end of the secondary winding is used to connect a rectifier circuit, and the second end of the secondary winding is connected to the free winding or the rectifier circuit through the secondary side switching switch; by adjusting the connection states of the primary side switching switch and the secondary side switching switch, the free winding is connected in series with the primary winding or the free winding is connected in series with the secondary winding, so as to change the turns ratio of the transformer. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0028] Fig. 1 is a structural schematic diagram of a transformer circuit according to an embodiment of the present disclosure;

[0029] Fig. 2 is a structural schematic diagram of a single-phase transformer circuit according to an embodiment of the present disclosure;

[0030] Fig. 3 is a structural schematic diagram of a three-phase transformer circuit according to an embodiment of the present disclosure;

[0031] Fig. 4 is a structural schematic diagram of another three-phase transformer circuit according to an embodiment of the present disclosure;

[0032] Fig. 5 is a structural schematic diagram of a charging pile according to an embodiment of the present disclosure;

[0033] Fig. 6 is a flowchart of a control method of a charging pile according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the present disclosure, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only some of the embodiments of the present disclosure, but not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present disclosure.

[0035] Referring to Fig. 1, which is a structural schematic diagram of a transformer circuit according to an embodiment of the present disclosure.

[0036] As shown in Fig. 1, the transformer circuit comprises a transformer 101 and a switching switch module 102; the transformer 101 comprises a primary winding, a secondary winding and a free winding; the switching switch module 102 comprises a primary switching switch S1 and a secondary switching switch S2.

[0037] A first end of the primary winding is used to connect an inverter circuit, and a second end of the primary winding is connected to the free winding or the inverter circuit through the primary switching switch S1; a first end of the secondary winding is used to connect a rectifier circuit, and a second end of the secondary winding is connected to the free winding or the rectifier circuit through the secondary switching switch S2.

[0038] The connection state of the primary switching switch S1 and the secondary switching switch S2 is adjusted to connect the free winding in series with the primary winding, or to connect the free winding in series with the secondary winding, so as to change the turns ratio of the transformer 101.

[0039] In a possible implementation, the primary side switching switch S1 and the secondary side switching switch S2 can each be a single-pole double-throw switch. The first end of the primary side switching switch S1 is connected to the second end of the primary winding, and the second end of the primary side switching switch S1 provides a first connection point and a second connection point, wherein the first connection point is connected to the inverter circuit, and the second connection point is connected to the free winding. The first end of the secondary side switching switch S2 is connected to the second end of the secondary winding, and the second end of the secondary side switching switch S2 provides a third connection point and a fourth connection point, wherein the third connection point is connected to the rectifier circuit, and the fourth connection point is connected to the free winding.

[0040] As an example, in the case where the first end of the primary side switching switch S1 is connected to the second connection point (the second end of the primary winding is connected to the free winding), and the first end of the secondary side switching switch S2 is connected to the third connection point (the second end of the secondary winding is connected to the rectifier circuit), the primary winding and the free winding are connected in series, and the number of turns of the primary winding is increased. For example, in the transformer TR1, the numbers of turns of the primary winding, the secondary winding, and the free winding are N1, N2, and N3 respectively, and in the case where the free winding and the primary winding are connected in series, the primary-secondary winding ratio is (N1+N3):N2.

[0041] As an example, in the case where the first end of the primary side switching switch S1 is connected to the first connection point (the second end of the primary winding is connected to the inverter circuit), and the first end of the secondary side switching switch S2 is connected to the fourth connection point (the second end of the secondary winding is connected to the free winding), the secondary winding and the free winding are connected in series, and the number of turns of the secondary winding is increased. For example, in the transformer TR1, the numbers of turns of the primary winding, the secondary winding, and the free winding are N1, N2, and N3 respectively, and in the case where the free winding and the primary winding are connected in series, the primary-secondary winding ratio is N1:(N2+N3).

[0042] As an example, in the case where the first end of the primary side switching switch S1 is connected to the first connection point (the second end of the primary winding is connected to the inverter circuit), and the first end of the secondary side switching switch S2 is connected to the third connection point (the second end of the secondary winding is connected to the rectifier circuit), the number of turns of the primary winding and the secondary winding is unchanged. For example, in the transformer TR1, the numbers of turns of the primary winding, the secondary winding, and the free winding are N1, N2, and N3 respectively, and in the case where the free winding and the primary winding are connected in series, the primary-secondary winding ratio is N1:N2.

[0043] In a possible implementation, as shown in FIG. 2, the primary side switching switch and the secondary side switching switch can each be a single-pole single-throw switch group, which are a first switch group Z1 and a second switch group Z2 respectively. It can be understood that each switch group can include two single-pole single-throw switches. In the first switch group Z1, the first switch is connected to the second end of the primary winding and the inverter circuit, and the second switch is connected to the second end of the primary winding and the free winding. In the second switch group Z2, the first switch is connected to the second end of the secondary winding and the rectifier circuit, and the second switch is connected to the second end of the secondary winding and the free winding.

[0044] As an example, in the case that the first switch in the first switch group Z1 is closed, the second switch is open, the first switch in the second switch group Z2 is closed, and the second switch is open, the primary winding and the free winding are connected in series, and the number of turns of the primary winding is increased.

[0045] As an example, in the case that the first switch in the first switch group Z1 is closed, the second switch is open, the first switch in the second switch group Z2 is closed, and the second switch is open, the secondary winding and the free winding are connected in series, and the number of turns of the secondary winding is increased.

[0046] As an example, in the case that the first switch in the first switch group Z1 is closed, the second switch is open, the first switch in the second switch group Z2 is closed, and the second switch is open, the primary winding and the free winding are connected in series, and the number of turns of the primary winding is increased.

[0047] It should be noted that in the single-phase transformer circuit in the foregoing embodiments, the second end of the free winding is connected to the inverter circuit or the rectifier circuit through two switches (S3 and S4).

[0048] In the case that the second end of the primary winding is connected to the free winding through the primary switching switch, the switch S3 at the second end of the free winding is closed, and the switch S4 is open. In the case that the second end of the secondary winding is connected to the free winding through the secondary switching switch, the switch S3 at the second end of the free winding is open, and the switch S4 is closed.

[0049] In the embodiments of the present disclosure, the free winding inside the inverter is multiplexed, that is, the free winding can be connected in series with the primary winding to increase the number of turns of the primary winding, and can also be connected in series with the secondary winding to increase the number of turns of the secondary winding, by controlling the state of the switch in the same device, thereby reducing the cost of the transformer circuit. In addition, by changing the number of turns of the primary winding and the secondary winding, the present disclosure further changes the primary winding ratio, so that the output voltage range of the transformer circuit is bidirectionally expanded (the boost range and the buck range are expanded), and the application range of the transformer circuit is improved.

[0050] Through the foregoing embodiments, how to change the primary winding ratio and the secondary winding ratio of the transformer through the connection relationship of the switch in the single-phase transformer circuit is introduced. In the following embodiments of the present disclosure, how to change the primary winding ratio and the secondary winding ratio of the transformer through the connection relationship of the switch in the three-phase transformer circuit will be introduced.

[0051] In a possible implementation, as shown in FIG. 3, the three-phase transformer circuit includes: three transformers (TR1, TR2 and TR3), three first single-pole double-throw switches (S1, S3 and S5) and three second single-pole double-throw switches (S2, S4 and S6). Wherein, the first end of each first single-pole double-throw switch is connected to the second end of the corresponding primary winding, and the second end of each first single-pole double-throw switch provides a first connection point and a second connection point, respectively; wherein, each first connection point is connected to each other, and each second connection point is connected to the first end of the corresponding free winding; the first end of each second single-pole double-throw switch is connected to the second end of the corresponding secondary winding, and the second end of each second single-pole double-throw switch provides a third connection point and a fourth connection point, respectively; wherein, each third connection point is connected to each other, and each fourth connection point is connected to the first end of the corresponding free winding; and the second end of each free winding is connected to each other.

[0052] As an example, the first end of each first single-pole double-throw switch (S1, S3 and S5) is connected to the second connection point, the first end of each secondary switching switch (S2, S4 and S6) is connected to the third connection point, and each free winding is connected in series with the corresponding primary winding (the primary winding N1 of TR1 is connected in series with the free winding N3, the primary winding N4 of TR2 is connected in series with the free winding N6, and the primary winding N7 of TR3 is connected in series with the free winding N9).

[0053] As an example, the first end of each primary switching switch (S1, S3 and S5) is connected to the first connection point, the first end of each secondary switching switch (S2, S4 and S6) is connected to the fourth connection point, and each free winding is connected in series with the corresponding secondary winding (the secondary winding N2 of TR1 is connected in series with the free winding N3, the secondary winding N5 of TR2 is connected in series with the free winding N6, and the secondary winding N8 of TR3 is connected in series with the free winding N9).

[0054] As an example, the first end of each primary switching switch (S1, S3 and S5) is connected to the first connection point, the first end of each secondary switching switch (S2, S4 and S6) is connected to the third connection point, and the turns ratio of each transformer remains unchanged (the primary-secondary turns ratio of TR1, TR2 and TR3 remains unchanged).

[0055] It should be noted that the number of turns of the primary winding of TR1, the number of turns of the primary winding of TR2 and the number of turns of the primary winding of TR3 are equal, the number of turns of the secondary winding of TR1, the number of turns of the secondary winding of TR2 and the number of turns of the secondary winding of TR3 are equal, and the number of turns of the free winding of TR1, the number of turns of the free winding of TR2 and the number of turns of the free winding of TR3 are equal.

[0056] In a possible implementation, as shown in FIG. 4, in a three-phase transformer circuit, there are three transformers (TR1, TR2 and TR3), three first switch groups (Z1, Z3 and Z5) and three second switch groups (Z2, Z4 and Z6). It can be understood that each switch group can include two single-pole single-throw switches, wherein the first ends of the first switches of each first switch group are connected to the second ends of the corresponding primary windings respectively, the second ends of the first switches of the first switch groups are connected to each other, the first ends of the second switches of each first switch group are connected to the second ends of the corresponding primary windings respectively, and the second ends of the second switches of each first switch group are connected to the first ends of the corresponding free windings respectively; the first ends of the first switches of each second switch group are connected to the second ends of the corresponding secondary windings respectively, the second ends of the first switches of the second switch groups are connected to each other, the first ends of the second switches of each second switch group are connected to the second ends of the corresponding secondary windings respectively, and the second ends of the second switches of each second switch group are connected to the first ends of the corresponding free windings respectively; and the second ends of the free windings are connected to each other.

[0057] For example, the first switches in each first switch group are turned off and the second switches are turned on, and the first switches in each second switch group are turned on and the second switches are turned off, so that the primary windings and the free windings are connected in series, that is, the primary winding N1 of TR1 and the free winding N3 are connected in series, the primary winding N4 of TR2 and the free winding N6 are connected in series, and the primary winding N7 of TR3 and the free winding N9 are connected in series, thereby increasing the number of turns of the primary windings.

[0058] For example, the first switches in each first switch group are turned on and the second switches are turned off, and the first switches in each second switch group are turned off and the second switches are turned on, so that the secondary windings and the free windings are connected in series, that is, the secondary winding N2 of TR1 and the free winding N3 are connected in series, the secondary winding N5 of TR2 and the free winding N6 are connected in series, and the secondary winding N8 of TR3 and the free winding N9 are connected in series, thereby increasing the number of turns of the primary windings.

[0059] For example, the first switches in each first switch group are turned on and the second switches are turned off, and the first switches in each second switch group are turned on and the second switches are turned off, so that the primary winding and the secondary winding of each transformer remain unchanged, that is, the primary winding and the secondary winding of TR1, TR2 and TR3 remain unchanged.

[0060] In combination with the single-phase transformer circuit and the three-phase transformer point circuit, the embodiment of the present disclosure increases the number of turns of the primary winding or the number of turns of the secondary winding by switching, so that the output voltage range of the transformer circuit is bidirectionally increased. For example, the number of turns of the primary winding of the inverter is N1, the number of turns of the secondary winding is N2, and the number of turns of the free winding is N3, and the transformer ratio is N1+N2:N3 or N1:N2+N3, thereby making the output voltage range of the transformer circuit larger and improving the applicability of the transformer circuit. In addition, the embodiment of the present disclosure can realize the above functions by switching, thereby reducing the cost of the transformer circuit.

[0061] In addition, the embodiment of the present disclosure also provides a charging pile, and a structural schematic diagram of the charging pile is shown in FIG. 5.

[0062] As shown in FIG. 5, the charging pile includes an inverter circuit 501, a rectifier circuit 503, and a transformer circuit 502 as in the foregoing embodiment.

[0063] By using the transformer circuit in the foregoing embodiment, the output voltage range of the charging pile is expanded to meet the requirements of various electric vehicles for charging voltage.

[0064] Referring to FIG. 6, which is a flowchart of a control method of a charging pile provided by the embodiment of the present disclosure.

[0065] As shown in FIG. 6, the method includes:

[0066] Step S601: Obtain the output voltage of the rectifier circuit.

[0067] It should be understood that the output voltage of the rectifier circuit in the embodiment of the present disclosure is equal in value to the charging voltage of the rear-end vehicle.

[0068] The way of obtaining the output voltage of the rectifier circuit is not specifically limited in the embodiment of the present disclosure, for example, the output voltage of the rectifier circuit (the actual output voltage of the rectifier circuit) can be obtained by a voltage sampling circuit, and the output voltage of the rectifier circuit (the theoretical output voltage of the rectifier circuit) can also be obtained according to a given voltage.

[0069] Step S602: According to the output voltage of the rectifier circuit, control the connection state of the primary switching switch and the secondary switching switch, so that the free winding is connected in series with the primary winding or the free winding is connected in series with the secondary winding, to change the turn ratio of the transformer.

[0070] In the embodiment of the present disclosure, the increase of the number of turns of the primary winding and the increase of the number of turns of the secondary winding of the transformer are realized at the same time in a low-cost manner, that is, the primary-secondary multiplexing of the free winding is realized by switching, so that the output voltage range of the transformer circuit is larger and the applicability of the transformer circuit is improved.

[0071] In one implementation, the connection state of the primary side switching switch and the secondary side switching switch is controlled to connect the free winding in series with the primary winding, or to connect the free winding in series with the secondary winding, specifically including: controlling the second end of the primary winding to connect the free winding through the primary side switching switch, and the second end of the secondary winding to connect the rectifier circuit through the secondary side switching switch, so as to connect the free winding in series with the primary winding; or, controlling the second end of the primary winding to connect the inverter circuit through the primary side switching switch, and the second end of the secondary winding to connect the free winding through the secondary side switching switch, so as to connect the free winding in series with the secondary winding.

[0072] In one implementation, the control method of the charging pile further includes: controlling the second end of the primary winding to connect the inverter circuit through the primary side switching switch, and the second end of the secondary winding to connect the rectifier circuit through the secondary side switching switch, and keeping the turns ratio of the transformer unchanged.

[0073] In one implementation, the primary side switching switch and the secondary side switching switch are respectively a first single-pole double-throw switch and a second single-pole double-throw switch; wherein the first end of the first single-pole double-throw switch is connected to the second end of the primary winding, and the second end of the first single-pole double-throw switch provides a first connection point and a second connection point; wherein the first connection point is used to connect the inverter circuit, and the second connection point is connected to the free winding; the first end of the second single-pole double-throw switch is connected to the second end of the secondary winding, and the second end of the second single-pole double-throw switch provides a third connection point and a fourth connection point; wherein the third connection point is used to connect the rectifier circuit, and the fourth connection point is connected to the free winding.

[0074] The connection state of the primary side switching switch and the secondary side switching switch is controlled to connect the free winding in series with the primary winding, or to connect the free winding in series with the secondary winding, specifically including: controlling the first end of the first single-pole double-throw switch to connect the second connection point, and the first end of the second single-pole double-throw switch to connect the third connection point, so as to connect the primary winding in series with the free winding; or, controlling the first end of the first single-pole double-throw switch to connect the first connection point, and the first end of the second single-pole double-throw switch to connect the fourth connection point, so as to connect the secondary winding in series with the free winding; or, controlling the first end of the first single-pole double-throw switch to connect the first connection point, and the first end of the second single-pole double-throw switch to connect the third connection point, so as to keep the turns ratio of the transformer unchanged.

[0075] In one implementation, the primary side switching switch and the secondary side switching switch are respectively a first switch group and a second switch group; wherein the first switch of the first switch group is connected to the second end of the primary winding and the inverter circuit, and the second switch of the first switch group is connected to the second end of the primary winding and the free winding; the first switch of the second switch group is connected to the second end of the secondary winding and the rectifier circuit, and the first switch of the second switch group is connected to the second end of the secondary winding and the free winding.

[0076] The connection state of the primary side switching switch and the secondary side switching switch is controlled to connect the free winding with the primary winding in series or connect the free winding with the secondary winding in series, and specifically includes: controlling the first switch of the first switch group to be turned off and the second switch to be turned on, and the first switch of the second switch group to be turned on and the second switch to be turned off, so as to connect the primary winding with the free winding in series; or, controlling the first switch of the first switch group to be turned on and the second switch to be turned off, and the first switch of the second switch group to be turned off and the second switch to be turned on, so as to connect the secondary winding with the free winding in series; or, controlling the first switch of the first switch group to be turned on and the second switch to be turned off, and the first switch of the second switch group to be turned on and the second switch to be turned off, so as to keep the turns ratio of the transformer unchanged.

[0077] In one implementation, the transformer circuit includes: three transformers, three first single-pole double-throw switches and three second single-pole double-throw switches; wherein the first end of each first single-pole double-throw switch is connected to the second end of the corresponding primary winding, and the second end of each first single-pole double-throw switch provides a first connection point and a second connection point; wherein the first connection points are connected to each other, and the second connection points are respectively connected to the first end of the corresponding free winding; the first end of each second single-pole double-throw switch is connected to the second end of the corresponding secondary winding, and the second end of each second single-pole double-throw switch provides a third connection point and a fourth connection point; wherein the third connection points are connected to each other, and the fourth connection points are respectively connected to the first end of the corresponding free winding; and the second ends of the free windings are connected to each other.

[0078] The connection state of the primary side switching switch and the secondary side switching switch is controlled to connect the free winding with the primary winding in series or connect the free winding with the secondary winding in series, and specifically includes: controlling the first end of each first single-pole double-throw switch to be connected to the second connection point, and the first end of each second single-pole double-throw switch to be connected to the third connection point, so as to connect each free winding with the corresponding primary winding in series; or, controlling the first end of each first single-pole double-throw switch to be connected to the first connection point, and the first end of each second single-pole double-throw switch to be connected to the fourth connection point, so as to connect each free winding with the corresponding secondary winding in series; or, controlling the first end of each first single-pole double-throw switch to be connected to the first connection point, and the first end of each second single-pole double-throw switch to be connected to the third connection point, so as to keep the turns ratio of each transformer unchanged.

[0079] In one implementation, the transformer circuit includes three transformers, three first switch groups and three second switch groups; wherein the first ends of the first switches of each first switch group are connected to the second ends of the corresponding primary windings respectively, the second ends of the first switches of the first switch groups are connected to each other, the first ends of the second switches of each first switch group are connected to the second ends of the corresponding primary windings respectively, and the second ends of the second switches of each first switch group are connected to the first ends of the corresponding free windings respectively; the first ends of the first switches of each second switch group are connected to the second ends of the corresponding secondary windings respectively, the second ends of the first switches of the second switch groups are connected to each other, the first ends of the second switches of each second switch group are connected to the second ends of the corresponding secondary windings respectively, and the second ends of the second switches of each second switch group are connected to the first ends of the corresponding free windings respectively; and the second ends of the free windings are connected to each other.

[0080] The connection states of the primary side switching switches and the secondary side switching switches are controlled to connect the free windings with the primary windings in series or connect the free windings with the secondary windings in series, and specifically includes: controlling the first switches of each first switch group to be turned off and the second switches of each first switch group to be turned on, and controlling the first switches of each second switch group to be turned on and the second switches of each second switch group to be turned off, so as to connect each free winding with the corresponding primary winding in series; or, controlling the first switches of each first switch group to be turned on and the second switches of each first switch group to be turned off, and controlling the first switches of each second switch group to be turned off and the second switches of each second switch group to be turned on, so as to connect each free winding with the corresponding secondary winding in series; or, controlling the first switches of each first switch group to be turned on and the second switches of each first switch group to be turned off, and controlling the first switches of each second switch group to be turned on and the second switches of each second switch group to be turned off, and keeping the turns ratio of each transformer unchanged.

[0081] It should be noted that each of the embodiments in the present specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the difference from other embodiments. Especially, for the method embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the related parts can be referred to the part of the method embodiments. The method embodiments described above are only illustrative, and the units described as separate components can be or can not be physically separated, and the components indicated as units can be or can not be physical units, that is, they can be located in one place or distributed on multiple network units. According to actual needs, part or all of the modules can be selected to achieve the purpose of the present embodiment. Those skilled in the art can understand and implement without creative labor.

[0082] The above merely describes one specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present disclosure, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A voltage conversion circuit, characterized by, The transformer comprises a primary winding, a secondary winding and a free winding; the switch module comprises a primary switch and a secondary switch; The first end of the primary winding is used for connecting an inverter circuit, and the second end of the primary winding is connected to the free winding or the inverter circuit through the primary switch; the first end of the secondary winding is used for connecting a rectifier circuit, and the second end of the secondary winding is connected to the free winding or the rectifier circuit through the secondary switch; The free winding is connected in series with the primary winding or the secondary winding by adjusting the connection state of the primary switch and the secondary switch, so as to change the turns ratio of the transformer.

2. The voltage conversion circuit according to claim 1, characterized by When the second end of the primary winding is connected to the free winding through the primary switch, and the second end of the secondary winding is connected to the rectifier circuit through the secondary switch, the free winding is connected in series with the primary winding.

3. The voltage conversion circuit of claim 1, wherein, When the second end of the primary winding is connected to the inverter circuit through the primary switch, and the second end of the secondary winding is connected to the free winding through the secondary switch, the free winding is connected in series with the secondary winding.

4. The variable voltage circuit of claim 1, wherein, When the second end of the primary winding is connected to the inverter circuit through the primary switch, and the second end of the secondary winding is connected to the rectifier circuit through the secondary switch, the turns ratio of the transformer remains unchanged.

5. The voltage conversion circuit according to any one of claims 1 to 4, characterized by, The primary switch and the secondary switch are respectively a first single-pole double-throw switch and a second single-pole double-throw switch; The first end of the first single-pole double-throw switch is connected to the second end of the primary winding, and the second end of the first single-pole double-throw switch provides a first connection point and a second connection point; wherein the first connection point is used for connecting the inverter circuit, and the second connection point is connected to the free winding; the first end of the second single-pole double-throw switch is connected to the second end of the secondary winding, and the second end of the second single-pole double-throw switch provides a third connection point and a fourth connection point; wherein the third connection point is used for connecting the rectifier circuit, and the fourth connection point is connected to the free winding; When the first end of the first single-pole double-throw switch is connected to the second connection point, and the first end of the second single-pole double-throw switch is connected to the third connection point, the primary winding is connected in series with the free winding; when the first end of the first single-pole double-throw switch is connected to the first connection point, and the first end of the second single-pole double-throw switch is connected to the fourth connection point, the secondary winding is connected in series with the free winding; when the first end of the first single-pole double-throw switch is connected to the first connection point, and the first end of the second single-pole double-throw switch is connected to the third connection point, the turns ratio of the transformer remains unchanged.

6. The voltage conversion circuit according to any one of claims 1 to 4, characterized by The primary switch and the secondary switch are respectively a first switch group and a second switch group; The first switch of the first switch group is connected with the second end of the primary winding and the inverter circuit, and the second switch of the first switch group is connected with the second end of the primary winding and the free winding; the first switch of the second switch group is connected with the second end of the secondary winding and the rectifier circuit, and the second switch of the second switch group is connected with the second end of the secondary winding and the free winding; In the case that the first switch of the first switch group is turned off and the second switch of the first switch group is turned on, the first switch of the second switch group is turned on and the second switch of the second switch group is turned off, the primary winding is connected with the free winding in series; In the case that the first switch of the first switch group is turned on and the second switch of the first switch group is turned off, the first switch of the second switch group is turned off and the second switch of the second switch group is turned on, the secondary winding is connected with the free winding in series; In the case that the first switch of the first switch group is turned on and the second switch of the first switch group is turned off, the first switch of the second switch group is turned on and the second switch of the second switch group is turned off, the turns ratio of the transformer remains unchanged.

7. The variable voltage circuit of claim 5, wherein, The transformer circuit comprises three transformers, three first single-pole double-throw switches and three second single-pole double-throw switches; The first end of each first single-pole double-throw switch is connected with the second end of the corresponding primary winding, and the second end of each first single-pole double-throw switch provides a first connection point and a second connection point; wherein the first connection points are connected with each other, and the second connection points are connected with the first end of the corresponding free winding; the first end of each second single-pole double-throw switch is connected with the second end of the corresponding secondary winding, and the second end of each second single-pole double-throw switch provides a third connection point and a fourth connection point; wherein the third connection points are connected with each other, and the fourth connection points are connected with the first end of the corresponding free winding; the second ends of the free windings are connected with each other; The first end of each first single-pole double-throw switch is connected with the second connection point, the first end of each second single-pole double-throw switch is connected with the third connection point, and each free winding is connected with the corresponding primary winding in series; the first end of each first single-pole double-throw switch is connected with the first connection point, the first end of each second single-pole double-throw switch is connected with the fourth connection point, and each free winding is connected with the corresponding secondary winding in series; the first end of each first single-pole double-throw switch is connected with the first connection point, the first end of each second single-pole double-throw switch is connected with the third connection point, and the turns ratio of each transformer remains unchanged.

8. The variable voltage circuit of claim 6, wherein, The transformer circuit comprises three transformers, three first switch groups and three second switch groups; The first end of the first switch of each of the first switch groups is connected to the second end of the corresponding primary winding, the second end of the first switch of the first switch group is connected to each other, the first end of the second switch of each of the first switch groups is connected to the second end of the corresponding primary winding, and the second end of the second switch of each of the first switch groups is connected to the first end of the corresponding free winding. The first end of the first switch of each of the second switch groups is connected to the second end of the corresponding secondary winding, the second end of the first switch of the second switch group is connected to each other, the first end of the second switch of each of the second switch groups is connected to the second end of the corresponding secondary winding, and the second end of the second switch of each of the second switch groups is connected to the first end of the corresponding free winding.

9. A charging station, characterized in that The second end of each of the free windings is connected to each other. The first switch of each of the first switch groups is turned off, the second switch is turned on, the first switch of each of the second switch groups is turned on, and the second switch is turned off, and each of the free windings is connected in series with the corresponding primary winding.

10. A control method of a charging pile, characterized by, The first switch of each of the first switch groups is turned on, the second switch is turned off, the first switch of each of the second switch groups is turned off, and the second switch is turned on, and each of the free windings is connected in series with the corresponding secondary winding. The first switch of each of the first switch groups is turned on, the second switch is turned off, the first switch of each of the second switch groups is turned on, and the second switch is turned off, and the turns ratio of each of the transformers remains unchanged. The charging pile comprises an inverter circuit, a rectifier circuit, and a transformer circuit as claimed in any one of claims 1-8. The output end of the rectifier circuit is used for connecting a device to be charged. The method comprises: Obtaining the output voltage of the rectifier circuit; According to the output voltage of the rectifier circuit, the connection state of the primary side switching switch and the secondary side switching switch is controlled, so that the free winding is connected in series with the primary winding, or the free winding is connected in series with the secondary winding, so as to change the turns ratio of the transformer.

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