Isolated charging power supply

Abstract

An isolated charging power supply includes: an AC power supply for providing AC power; a first rectifier circuit, the first rectifier circuit is used to rectify the AC power provided by the AC power supply; at least two conversion circuits, the conversion circuits are connected in parallel with each other, and the input of the conversion circuit is connected to the output of the first rectifier circuit; at least two isolation transformers, the input of one isolation transformer is connected to the output of one conversion circuit; at least two second rectifier circuits, the input of one second rectifier circuit is connected to the output of one isolation transformer; a switching circuit, the switching circuit is connected between two adjacent second rectifier circuits, and the switching circuit is used to switch the connection structure between the second rectifier circuits between a series structure and a parallel structure. The output voltage range of the isolated charging power supply is expanded.

Description

Technical Field

[0001] The present invention relates to the field of charging power supplies, and in particular to an isolated charging power supply. Background Art

[0002] With the large-scale promotion of new energy vehicles by the country, the popularity of new energy vehicles is increasing. Unlike fuel vehicles that can be refueled at gas stations, new energy vehicles require charging piles for charging. With the popularity of new energy vehicles, the demand for charging piles is also growing rapidly.

[0003] Currently, common charging piles are divided into AC charging piles and DC charging piles. AC charging piles have low charging power and are difficult to meet the requirements of fast charging of new energy vehicles. Therefore, more and more newly installed charging piles tend to be DC charging piles. The basic function of DC charging piles is to isolate AC power and convert it into DC power to directly charge the battery.

[0004] With the development of battery technology, in order to increase the power of new energy vehicles, on the one hand, the current capacity of the battery is getting larger and larger, and on the other hand, the voltage of the battery is getting higher and higher. The battery voltage has increased from the initial 300V to more than 800V. This means that the battery voltage of new energy vehicles currently ranges from 300V to 800V, and the corresponding charging pile, as a charging power source, must also meet the charging voltage range of at least 200V to 800V. However, the existing charging power source cannot meet the design requirements of the charging pile. Summary of the invention

[0005] The problem solved by the present invention is to provide an isolated charging power supply so that the charging power supply can have a wider output range.

[0006] To solve the above problems, the present invention provides an isolated charging power supply, comprising: an AC power supply for providing AC power; a first rectifier circuit, the first rectifier circuit is used to rectify the AC power provided by the AC power supply; at least two conversion circuits, the conversion circuits are connected in parallel with each other, and the input of the conversion circuit is connected to the output of the first rectifier circuit; at least two isolation transformers, the input of one isolation transformer is correspondingly connected to the output of one conversion circuit; at least two second rectifier circuits, the input of one second rectifier circuit is correspondingly connected to the output of one isolation transformer; a switching circuit, the switching circuit is connected between two adjacent second rectifier circuits, and the switching circuit is used to switch the connection structure between the second rectifier circuits between a series structure and a parallel structure.

[0007] Optionally, there are two conversion circuits, two isolation transformers and two second rectifier circuits; the switching circuit includes a first switch tube, a second switch tube and a third switch tube; the first end of the first switch tube is connected to the positive end of the first second rectifier circuit; the second end of the first switch tube is connected to the positive end of the second second rectifier circuit; the first end of the second switch tube is connected to the positive end of the second second rectifier circuit; the second end of the second switch tube is connected to the ground end of the first second rectifier circuit; the first end of the third switch tube is connected to the ground end of the first second rectifier circuit; the second end of the third switch tube is connected to the ground end of the second second rectifier circuit; the third end of the first switch tube, the third end of the second switch tube and the third end of the third switch tube are connected to a control unit.

[0008] Optionally, the first switch tube, the second switch tube and the third switch tube are all NMOS tubes;

[0009] The first end of the first switch tube is a drain, the second end is a source, and the third end is a gate;

[0010] The first end of the second switch tube is a drain, the second end is a source, and the third end is a gate;

[0011] The first end of the third switch tube is a drain, the second end is a source, and the third end is a gate.

[0012] Optionally, the isolated charging power supply further includes an input filter capacitor, and the input filter capacitor is located at the front end of the conversion circuit.

[0013] Optionally, each isolation transformer further has a resonant inductor at its input end.

[0014] Optionally, the conversion circuit is a full-bridge circuit.

[0015] Optionally, the isolated charging power supply further includes an output filter capacitor, and the output filter capacitor is located at the rear end of the second rectifier circuit.

[0016] Optionally, one of the conversion circuits and a corresponding one of the resonant inductors, one of the isolation transformers, one of the second rectifier circuits and the output filter capacitor form a full-bridge LLC circuit or a full-bridge CLLC circuit.

[0017] Optionally, a MOS tube or an IGBT tube is used as a switch tube in the full-bridge circuit of the conversion circuit.

[0018] Optionally, the AC power supply is a three-phase AC power supply, and when the three-phase AC power supply is connected to the first rectifier circuit (110), a line corresponding to each phase has an inductor (L1 / L2 / L3).

[0019] In one aspect of the technical solution of the present invention, the isolated charging power supply switches the series-parallel connection of the second rectifier circuit through a switching circuit, so that the output voltage can be adjusted between multiple times of the minimum output voltage, thereby expanding the adjustment range of the output voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A topological circuit diagram provided by an embodiment of the present invention;

[0021] Figure 2 A topological circuit diagram provided by another embodiment of the present invention;

[0022] Figure 3 A topological circuit diagram provided by another embodiment of the present invention. DETAILED DESCRIPTION

[0023] In the existing charging power supply, after the AC power enters the circuit, the AC current is converted into DC current. Then, the DC power is converted into AC power that can pass through the isolation transformer. The converted power passes through the isolation transformer and then converted into DC power through the rectifier circuit to charge the battery pack.

[0024] Since the charging current of the charging pile is very large, the conversion circuit can use a full-bridge LLC circuit. When the battery is charged, the battery voltage has a process of rising from low voltage to rated voltage, so the output voltage of the LLC circuit also needs to rise from low voltage to high voltage. According to the principle of the LLC circuit, the output voltage is generally adjusted by adjusting the operating frequency of the conversion circuit. The specific principle is: when the battery voltage is low, the switching frequency of the LLC is high. As the battery voltage rises, the charging voltage of the charging circuit decreases; this is to reduce the LLC switching frequency to increase the power supply output voltage, thereby increasing the charging current to reach the rated charging current of the charging pile; until the battery voltage reaches the highest charging voltage, the LLC circuit increases the charging frequency and reduces the charging current, and the output is turned off until the charging current is zero.

[0025] According to the above principle, the voltage output range of a charging pile depends on the voltage output range of the LLC circuit. The wider the output voltage range of the LLC circuit, the lower the efficiency. Generally, the output voltage range is about 2:1 and will not be greater than 3:1. Due to the characteristics of the LLC circuit itself, the existing charging scheme improved by the LLC circuit itself can no longer meet the needs of charging piles. Therefore, the existing charging pile LLC charging circuit scheme has the problem of a narrow output voltage range.

[0026] To this end, the present invention provides a new isolated charging power supply to solve the above-mentioned shortcomings.

[0027] For a clearer representation, the present invention is described in detail below with reference to the accompanying drawings.

[0028] The embodiment of the present invention provides an isolated charging power supply, please refer to Figure 1 The isolated charging power supply includes:

[0029] AC power supply (not separately marked, such as Figure 1 The leftmost connected lines A, B and C are shown in FIG. 1 ) for providing AC power;

[0030] A first rectifier circuit 110, the first rectifier circuit 110 is used to rectify the AC power provided by the AC power source;

[0031] Two conversion circuits, namely, conversion circuit 121 and conversion circuit 122, which are connected in parallel to each other, and the inputs of conversion circuit 121 and conversion circuit 122 are both connected to the output of the first rectifier circuit 110; conversion circuit 121 and conversion circuit 122 are used to convert the output from the rectifier circuit 110 into alternating current;

[0032] Two isolation transformers, namely, isolation transformer T1 and isolation transformer T2. The input of one isolation transformer is connected to the output of a conversion circuit. Specifically, the input of isolation transformer T1 is connected to the output of conversion circuit 121, and the input of isolation transformer T2 is connected to the output of conversion circuit 122. The isolation transformer is connected between the conversion circuit and other subsequent circuits, so that the other subsequent circuits are electrically insulated from the AC power supply.

[0033] Two second rectifier circuits, namely a second rectifier circuit 131 and a second rectifier circuit 132, wherein the input of one second rectifier circuit is connected to the output of an isolation transformer, specifically, the input of the second rectifier circuit 131 is connected to the output of the isolation transformer T1, and the input of the second rectifier circuit 132 is connected to the output of the isolation transformer T2; the second rectifier circuit rectifies the output of the isolation transformer and outputs it to the corresponding battery BA to be charged;

[0034] The switching circuit 140 is connected between two adjacent second rectifier circuits, that is, in this embodiment, connected between the second rectifier circuit 131 and the second rectifier circuit 132. The switching circuit 140 is used to switch the connection structure between the second rectifier circuit 131 and the second rectifier circuit 132 between a series structure and a parallel structure.

[0035] After passing through the switching circuit, the isolated charging power supply can be used to charge the corresponding battery BA to be charged, such as Figure 1 shown.

[0036] It can be seen from the above structure that in this embodiment, the input ends of the two isolation transformers (isolation transformer T1 and isolation transformer T2) are connected in parallel through the conversion circuit (conversion circuit 121 and conversion circuit 122), and the output ends of the two isolation transformers (isolation transformer T1 and isolation transformer T2) are respectively connected to a rectifier circuit (isolation transformer T1 is connected to the second rectifier circuit 131, and isolation transformer T2 is connected to the second rectifier circuit 132), and the two rectifier circuits (second rectifier circuit 131 and second rectifier circuit 132) are connected together through the switching circuit 140. This structure enables the isolated charging power supply of this embodiment to achieve a wider output voltage range to meet the requirements of new energy vehicles for charging piles.

[0037] In this embodiment, the input ends of the isolation transformers are connected in parallel through the conversion circuits, that is, the input ends of the isolation transformers T1 and T2 are connected in parallel and then connected to the output ends of the corresponding conversion circuits 121 and 122 respectively.

[0038] It should be noted that the switching circuit of the present invention is connected between two adjacent second rectifier circuits, wherein the switching circuit is connected between two adjacent second rectifier circuits means that if there are K (K is an integer greater than 2) second rectifier circuits, then there can be K-1 switching circuits, but there can also be an overall switching circuit, and this overall switching circuit is a circuit that unifies K-1 individual switching circuits. In short, the switching circuit is to ensure that the switching between series and parallel structures can be achieved between different second rectifier circuits.

[0039] Please refer to Figure 1 In this embodiment, the switching circuit 140 includes a first switch tube Q23, a second switch tube Q24, and a third switch tube Q25. The first end of the first switch tube Q23 is connected to the positive end of the second rectifier circuit 131. The second end of the first switch tube Q23 is connected to the positive end of the second rectifier circuit 132. The first end of the second switch tube Q24 is connected to the positive end of the second rectifier circuit 132. The second end of the second switch tube Q24 is connected to the ground end of the second rectifier circuit 131. The first end of the third switch tube Q25 is connected to the ground end of the second rectifier circuit 131. The second end of the third switch tube Q25 is connected to the ground end of the second rectifier circuit 132.

[0040] It should be noted that, although not shown in the figure, the third end of the first switch tube Q23, the third end of the second switch tube Q24 and the third end of the third switch tube Q25 are connected to the control unit, which may be a processor (not shown) of the isolated charging power supply.

[0041] Please refer to Figure 1In this embodiment, the first switch tube Q23, the second switch tube Q24 and the third switch tube Q25 are all NMOS tubes (N-channel MOS tubes). The first end of the first switch tube Q23 is the drain (D), the second end is the source (S), and the third end is the gate (G).

[0042] Similarly, the first end of the second switch tube Q24 is a drain, the second end is a source, and the third end is a gate. The first end of the third switch tube Q25 is a drain, the second end is a source, and the third end is a gate.

[0043] It should be noted that, in other embodiments, the first switch tube Q23, the second switch tube Q24 and the third switch tube Q25 may all be PMOS tubes. Figure 1 Other device structures of the overall topology structure can be replaced accordingly according to the replacement of this device.

[0044] In this embodiment, the isolated charging power supply further includes an input filter capacitor C1 , and the input filter capacitor C1 is located at the front end of the conversion circuit 121 and the conversion circuit 122 .

[0045] In this embodiment, each isolation transformer also has a resonant inductor at its input end. Specifically, the isolation transformer T1 also has a resonant inductor L4 at its input end, and the isolation transformer T2 also has a resonant inductor L5 at its input end.

[0046] In this embodiment, the first rectifier circuit 110 includes a corresponding bridge rectifier circuit, specifically including an upper arm, a middle arm and a lower arm. The upper arm has a corresponding series-connected switch tube Q1 and a switch tube Q2, the middle arm has a corresponding series-connected switch tube Q3 and a switch tube Q4, and the lower arm has a corresponding series-connected switch tube Q5 and a switch tube Q6.

[0047] Meanwhile, the corresponding AC power supply of this embodiment is a three-phase AC power supply. When the three-phase AC power supply is connected to the first rectifier circuit 110, each phase of the line corresponding to the three-phase AC power supply has an inductance, such as Figure 1 As shown in FIG, the three-phase AC power supply is divided into line A, line B and line C, which are respectively connected with inductance L1, inductance L2 and inductance L3. Line A, line B and line C are respectively connected to the middle of the upper arm, the middle arm and the lower arm.

[0048] In this embodiment, the first rectifier circuit 110 is made of various NMOS transistors and can simultaneously realize the function of a PFC (Power Factor Correction) circuit to perform power factor correction.

[0049] In this embodiment, the conversion circuit 121 and the conversion circuit 122 are full-bridge circuits. Figure 1The full bridge circuit of the conversion circuit 121 includes a switch tube Q7, a switch tube Q8, a switch tube Q11 and a switch tube Q12. The full bridge circuit of the conversion circuit 122 includes a switch tube Q9, a switch tube Q10, a switch tube Q13 and a switch tube Q14.

[0050] In this embodiment, silicon carbide MOS tubes are used as corresponding switch tubes in the full bridge circuits of the conversion circuit 121 and the conversion circuit 122. That is, the switch tubes Q7, Q8, Q11, Q12, Q9, Q10, Q13 and Q14 are all made of silicon carbide MOS tubes, and specifically NMOS tubes are used. Furthermore, silicon carbide MOS tubes with a voltage of 1200V can be used as switch tubes of the conversion circuit.

[0051] In other embodiments, the full bridge circuits of the conversion circuit 121 and the conversion circuit 122 may also use structures such as gallium nitride MOS tubes. In terms of high-frequency rectification characteristics, silicon carbide MOS tubes and gallium nitride MOS tubes are superior to silicon MOS tubes. However, in other embodiments, these full bridge circuits may also use silicon MOS tubes or IGBT tubes.

[0052] As described above, when each switch tube of the conversion circuit 121 is an NMOS tube, the drain of the switch tube Q8, the source of the switch tube Q7, the source of the switch tube Q11 and the drain of the switch tube Q12 in the conversion circuit 121 are connected to the primary side of the isolation transformer T1 (that is, the input end of the isolation transformer T1), that is, the output end of the conversion circuit 121 is connected to the input end of the isolation transformer T1.

[0053] As described above, when each switch tube of the conversion circuit 122 is an NMOS tube, the drain of the switch tube Q10, the source of the switch tube Q9, the source of the switch tube Q13 and the drain of the switch tube Q14 in the conversion circuit 122 are connected to the primary side of the isolation transformer T2 (that is, the input end of the isolation transformer T2), that is, the output end of the conversion circuit 122 is connected to the input end of the isolation transformer T2.

[0054] In this embodiment, the second rectifier circuit 131 and the second rectifier circuit 132 adopt a bridge rectifier circuit, which both include two upper and lower arms in parallel, and each upper arm and lower arm include two rectifier elements in series. In this embodiment, the rectifier element is a diode. The upper arm of the second rectifier circuit 131 includes a diode D1 and a diode D3, and the lower arm of the second rectifier circuit 131 includes a diode D2 and a diode D4. The output of the isolation transformer T1 is connected between the upper arm and the lower arm of the second rectifier circuit 131. The upper arm of the second rectifier circuit 132 includes a diode D5 and a diode D7, and the lower arm of the second rectifier circuit 132 includes a diode D6 and a diode D8. The output of the isolation transformer T2 is connected between the upper arm and the lower arm of the second rectifier circuit 132.

[0055] In this embodiment, the isolated charging power supply further includes an output filter capacitor C5 , and the output filter capacitor C5 is located at the rear end of the second rectifier circuit 131 and the second rectifier circuit 132 .

[0056] In this embodiment, the output filter capacitor C5 is further installed at the rear end of the switching circuit 140 , that is, the output filter capacitor C5 is located between the battery to be charged BA and the second rectifier circuit 131 and the second rectifier circuit 132 .

[0057] In this embodiment, a conversion circuit and a corresponding resonant inductor, an isolation transformer, a second rectifier circuit and an output filter capacitor C5 constitute a full-bridge LLC circuit. Specifically, the conversion circuit 121 and the corresponding resonant inductor L4, the isolation transformer T1, the second rectifier circuit 131 and the output filter capacitor C5 constitute a full-bridge LLC circuit. The conversion circuit 122 and the corresponding resonant inductor L5, the isolation transformer T2, the second rectifier circuit 132 and the output filter capacitor C5 constitute a full-bridge LLC circuit. The full-bridge LLC circuit has a high power density and is suitable for high-power occasions. It should be noted that in other embodiments, by adding a capacitor in addition to a conversion circuit and a corresponding resonant inductor, an isolation transformer, a second rectifier circuit and an output filter capacitor C5, a full-bridge CLLC circuit can be further formed, and the full-bridge CLLC circuit can achieve bidirectional voltage output.

[0058] In this embodiment, the turns ratio of the primary coil and the secondary coil of the isolation transformer T1 and the isolation transformer T2 can be 2.5:1.

[0059] In other embodiments, the turns ratio of the isolation transformer may also be other values.

[0060] The principle of the isolated charging power supply provided in this embodiment to achieve a wide output range is as follows:

[0061] Two different connection structures are realized by the switching circuit 140;

[0062] In the first connection structure, the first switch tube Q23 and the third switch tube Q25 are turned on, and the second switch tube Q24 is turned off. At this time, the second rectifier circuit 131 and the second rectifier circuit 132 are connected in parallel for output. That is to say, if the maximum output voltage range of one output is calculated as 3:1, the output voltage after parallel connection is still 3:1.

[0063] In the second connection structure, the second switch tube Q24 is turned on, and the first switch tube Q23 and the third switch tube Q25 are turned off. At this time, the second rectifier circuit 131 and the second rectifier circuit 132 are output in series. That is to say, if the maximum output voltage range of one output is calculated as 3:1, the output voltage becomes 6:1 after series connection. Obviously, the output voltage range of the series structure is significantly widened.

[0064] It can be seen that the topology structure provided by the present invention can effectively broaden the output voltage range and can provide at least two different output voltage ranges.

[0065] As mentioned above, in this embodiment, the conversion circuit 121 and the corresponding resonant inductor L4, the isolation transformer T1, the second rectifier circuit 131 and the output filter capacitor C5 constitute a full-bridge LLC circuit; the conversion circuit 122 and the corresponding resonant inductor L5, the isolation transformer T2, the second rectifier circuit 132 and the output filter capacitor C5 constitute a full-bridge LLC circuit. Based on this circuit structure, when the input is a 380V three-phase AC power supply, when the full-bridge LLC circuit of this embodiment enters full resonance, the output voltage of the single-channel second rectifier circuit is about 256V to 360V. By adjusting the operating frequency of the full-bridge LLC circuit to achieve a 2-fold gain change, the output voltage of the single-channel second rectifier circuit is 192V to 450V.

[0066] At this point, it can be seen that when the isolated charging power supply is switched to the first connection structure mentioned above, the entire charging power supply provides two charging outputs, and in each charging output, the charging voltage range of the second rectifier circuit output is 192V~450V; on the contrary, when the isolated charging power supply is switched to the second connection structure mentioned above, the rectifier circuit and are connected in series, and the output charging voltage range is 384V~900V.

[0067] Therefore, by switching the different switch controls of the switching circuit 140, in combination with the frequency modulation control of the LLC circuit and the bus voltage regulation control of the PFC circuit, the output voltage range of the isolated charging power supply is increased to 192V to 900V. Compared with the output voltage range of 192V to 450V when the output circuit is directly connected in parallel, the charging output voltage range of this embodiment is expanded by 2.74 times, that is, (900-192) / (450-192)=2.74, or in other words, the maximum floating range of the output voltage after parallel connection is 900-192=708V, while the maximum floating range of the original output voltage is 450-192=258V, and 708V is 2.74 times of 258V.

[0068] In summary, the output voltage adjustment range of a general LLC circuit is only about 1:3 (such as 450 / 192=2.34 in the previous example), so the maximum output voltage of the rectifier output circuit is only about 3 times the minimum output voltage. However, when the isolated charging power supply provided in this embodiment is switched to connect the second rectifier circuits in series, the corresponding output voltage can be changed to about 2 to 6 times the single minimum voltage (such as 900 / 192=4.69 in the previous example). Therefore, the isolated charging power supply provided in this embodiment switches the series-parallel connection of the second rectifier circuit through the switching circuit 140, so that the output voltage can be adjusted between 1 and 6 times the minimum output voltage, thereby expanding the adjustment range of the output voltage.

[0069] From the above, it can be seen that this embodiment provides an isolated charging power supply with a wide output range. When the input voltage of the isolated charging power supply is 380V AC power, after the three-phase PFC structure provided by this embodiment, the final rectified output bus DC voltage range can be 640V~900V.

[0070] Another embodiment of the present invention provides another isolated charging power supply, please refer to Figure 2 , the isolated charging power supply of this embodiment is Figure 1 The isolated charging power supply structures shown are basically the same.

[0071] This embodiment and Figure 1 The difference is that, in this embodiment, the second rectifier circuit 131 includes switch tubes Q15, Q16, Q19 and Q20, which are not diodes, but are specifically corresponding NMOS tubes; the second rectifier circuit 132 includes switch tubes Q17, Q18, Q21 and Q22, which are not diodes, but are specifically corresponding NMOS tubes.

[0072] In the second rectifier circuit 131, the drain of the switch tube Q16, the source of the switch tube Q15, the source of the switch tube Q19 and the drain of the switch tube Q20 are connected to the secondary side of the isolation transformer T1 (i.e., the output end of the isolation transformer T1), and the output end of the second rectifier circuit 131 is connected to the switching circuit 140.

[0073] In the second rectifier circuit 132, the drain of the switch tube Q18, the source of the switch tube Q17, the source of the switch tube Q21 and the drain of the switch tube Q22 are connected to the secondary side of the isolation transformer T2 (i.e., the output end of the isolation transformer T1), and the output end of the second rectifier circuit 132 is connected to the switching circuit 140.

[0074] In this embodiment, the corresponding second rectifier circuit 131 and the second rectifier circuit 132 are implemented using NMOS switch tubes, which can achieve better rectification effect. At this time, the average value and polarity of the DC voltage output by the rectifier circuit can be adjusted by controlling the conduction status of the element.

[0075] Another embodiment of the present invention provides another isolated charging power supply, please refer to Figure 3 , the isolated charging power supply of this embodiment is Figure 2 The isolated charging power supply structures shown are basically the same.

[0076] This embodiment and Figure 2 The difference is that, in this embodiment, three conversion circuits are included, that is, in addition to the conversion circuit 121 and the conversion circuit 122, a conversion circuit 123 is also included.

[0077] This embodiment and Figure 2 The difference is that, accordingly, in this embodiment, three isolation transformers are included, that is, in addition to the transformer T1 and the isolation transformer T2, a transformer T3 is also included.

[0078] This embodiment and Figure 2 The difference is that, accordingly, in this embodiment, three second rectifier circuits are included, that is, in addition to the second rectifier circuit 131 and the second rectifier circuit 132 , a second rectifier circuit 133 is also included.

[0079] This embodiment and Figure 2 The difference is that, accordingly, in this embodiment, two switching circuits are included, that is, in addition to the switching circuit 140 , a switching circuit 150 is also included.

[0080] That is to say, the isolated charging power supply of this embodiment adds one circuit, and at the same time, adds a corresponding switching circuit 150, and the switching circuit 150 links this circuit with other circuits to form a switchable structure that can be adjusted to series or parallel.

[0081] The switching circuit 150 added in this embodiment includes a fourth switch tube Q23, a fifth switch tube Q24 and a sixth switch tube Q25. The connection relationship between them and the second rectifier circuit 132 and the second rectifier circuit 133 can be referred to. Figure 3 And reference may be made to the corresponding contents of the aforementioned embodiments (reference may be made to the corresponding contents of the first switch tube Q23, the second switch tube Q24 and the third switch tube Q25).

[0082] The second rectifier circuit 133 added in this embodiment includes a switch tube Q31 , a switch tube Q32 , a switch tube Q35 and a switch tube Q36 , and the corresponding contents of the second rectifier circuit 131 and the second rectifier circuit 132 may be referred to.

[0083] The conversion circuit 123 added in this embodiment includes a switch tube Q29, a switch tube Q30, a switch tube Q33 and a switch tube Q34, and the corresponding contents of the conversion circuit 121 and the conversion circuit 122 may be referred to.

[0084] In this embodiment, a resonant inductor L6 is further provided at the input end of the isolation transformer T3.

[0085] In this embodiment, the conversion circuit 123 and the corresponding resonant inductor L6, isolation transformer T3, second rectifier circuit 133 and output filter capacitor C5 also form a full-bridge LLC circuit. Reference can be made to the other two full-bridge LLC circuits formed by other structures and the corresponding contents of the above embodiments.

[0086] The isolated charging power supply provided in this embodiment includes three circuit structures that can be connected in series and parallel. Therefore, compared with the power supplies of the above two embodiments, the power supply provided in this embodiment can further provide three different output voltage ranges. Still using the corresponding conditions of the above embodiments, in this embodiment, three different output voltage ranges such as 192V~450V, 384V~900V and 576V~1350V can be further provided, that is, a charging voltage range of 192V~1350V can be provided.

[0087] Combined with the analysis of other principles of the aforementioned embodiments, it can be seen that the isolated charging power supply provided in this embodiment switches the series-parallel connection of each second rectifier circuit through the switching circuit 140 and the switching circuit 150, so that the output voltage can be adjusted between 1 and 9 times the minimum output voltage, thereby expanding the adjustment range of the output voltage.

[0088] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. An isolated charging power supply, characterized in that: include: An AC power supply, used for providing AC power; a first rectifier circuit (110), the first rectifier circuit being used to rectify the AC power provided by the AC power source; at least two conversion circuits (121 / 122, 121 / 122 / 123), the conversion circuits are connected in parallel with each other, and the input of the conversion circuit is connected to the output of the first rectifier circuit; At least two isolation transformers (T1 / T2, T1 / T2 / T3), the input of one of the isolation transformers correspondingly connected to the output of one of the conversion circuits; At least two second rectifier circuits (131 / 132, 131 / 132 / 133), an input of one of the second rectifier circuits correspondingly connected to an output of the isolation transformer; a switching circuit (140, 140 / 150), the switching circuit being connected between two adjacent second rectifier circuits, the switching circuit being used to switch the connection structure between the second rectifier circuits between a series structure and a parallel structure; The number of each of the conversion circuit (121 / 122), the isolation transformer (T1 / T2) and the second rectifier circuit (131 / 132) is two; The switching circuit (140) comprises a first switch tube (Q23), a second switch tube (Q24) and a third switch tube (Q25); A first end of the first switch tube (Q23) is connected to a positive end of a first of the second rectifier circuits (131); The second end of the first switch tube (Q23) is connected to the positive end of the second second rectifier circuit (132); A first end of the second switch tube (Q24) is connected to a positive end of a second second rectifier circuit (132); The second end of the second switch tube (Q24) is connected to the ground end of the first second rectifier circuit (131); A first end of the third switch tube (Q25) is connected to a ground end of a first of the second rectifier circuits (131); The second end of the third switch tube (Q25) is connected to the ground end of the second second rectifier circuit (132); The third end of the first switch tube (Q23), the third end of the second switch tube (Q24) and the third end of the third switch tube (Q25) are connected to a control unit; The first switch tube (Q23), the second switch tube (Q24) and the third switch tube (Q25) are all NMOS tubes; The first end of the first switch tube (Q23) is a drain, the second end is a source, and the third end is a gate; The first end of the second switch tube (Q24) is a drain, the second end is a source, and the third end is a gate; The first end of the third switch tube (Q25) is a drain, the second end is a source, and the third end is a gate; Each of the isolation transformers (T1 / T2) also has a resonant inductor (L4 / L5) at its input end; The conversion circuit (121 / 122) is a full-bridge circuit; It also includes an output filter capacitor (C5), and the output filter capacitor (C5) is located at the rear end of the second rectifier circuit (131 / 132); A conversion circuit (121 / 122) and a corresponding resonant inductor (L4 / L5), an isolation transformer (T1 / T2), a second rectifier circuit (131 / 132) and an output filter capacitor (C5) form a full-bridge LLC circuit or a full-bridge CLLC circuit.

2. The isolated charging power supply according to claim 1, characterized in that: It also includes an input filter capacitor (C1), and the input filter capacitor (C1) is located at the front end of the conversion circuit (121 / 122).

3. The isolated charging power supply according to claim 1, characterized in that: The full-bridge circuit of the conversion circuit (121 / 122) adopts MOS tubes or IGBT tubes as switch tubes.

4. The isolated charging power supply according to claim 1, characterized in that: The AC power source is a three-phase AC power source. When the three-phase AC power source is connected to the first rectifier circuit (110), a line corresponding to each phase has an inductor (L1 / L2 / L3).

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