Vehicle-mounted charger system

Abstract

The invention, which belongs to the technical field of vehicle charging, relates to a vehicle-mounted charger system comprising a three-phase AC input, a rectifier bridge circuit, an SEPIC circuit, a DC bus capacitor and a load. The rectifier bridge circuit and the SEPIC circuit are arranged between each phase of input of the three-phase alternating current input and a load, the direct current bus capacitor and the load are connected in parallel, and the SEPIC circuit comprises an active clamping circuit and a transformer circuit. According to the invention, the efficiency and reliability of the OBC in a wide output voltage range are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle charging technology, and more particularly to an on-board charger system. Background Technology

[0002] Current on-board charger (OBC) technology focuses on high power density, high efficiency, and miniaturization. Existing solutions employ a topology combining power factor correction (PFC) and LLC resonant circuits to achieve efficient AC-DC conversion and support wide voltage input and intelligent communication.

[0003] Existing OBC solutions suffer from the following drawbacks: Low efficiency over a wide output voltage range: Mainstream post-stage isolation topologies exhibit significant efficiency drops when battery voltage varies widely, particularly under high-voltage input and low-voltage output conditions. Excessive device voltage stress: In topologies with wide range capabilities, the voltage stress on the switching transistors approaches the sum of the input and output voltages. In high-voltage bus and high-voltage battery scenarios, this stress far exceeds the levels of commonly used devices, leading to reduced OBC reliability.

[0004] Therefore, improving the efficiency and reliability of OBCs over a wide output voltage range has become a pressing technical problem that needs to be solved. Summary of the Invention

[0005] In view of this, it is necessary to provide an on-board charger system to solve the problem of low efficiency and reliability of existing OBCs over a wide output voltage range.

[0006] To address the above problems, the present invention provides an on-board charger system, comprising: Three-phase AC input, rectifier bridge circuit, SEPIC circuit, DC bus capacitor and load; The rectifier bridge circuit and SEPIC circuit are positioned between each phase of the three-phase AC input and the load. The DC bus capacitor is connected in parallel with the load. The SEPIC circuit contains an active clamping circuit and a transformer circuit.

[0007] In one possible implementation, the charging circuit structure for each phase between the three-phase AC input and the load is identical, including: AC input power supply, first diode, second diode, third diode, fourth diode, first switching transistor, second switching transistor, fifth diode, first capacitor, second capacitor, third capacitor, inductor, transformer, transformer leakage inductance and transformer magnetizing inductance; The negative terminal of the AC input power supply is connected to the negative terminals of the other two phases of the AC input power supply, and the positive terminal is connected to the positive terminal of the first diode and the negative terminal of the second diode. The positive terminal of the second diode is connected to the positive terminal of the fourth diode and the source terminal of the first switching transistor; The negative terminal of the fourth diode is connected to the negative terminal of the AC input power supply and the positive terminal of the third diode; The negative terminal of the third diode is connected to the negative terminal of the first diode and one end of the inductor; The inductor and the transformer leakage inductance are reverse-coupled, and the other end of the inductor is connected to the drain of the first switching transistor and the anode of the first capacitor. The cathode of the first capacitor is connected to the source of the second switching transistor and one end of the leakage inductance of the transformer. The other end of the transformer leakage inductance is connected to one end of the transformer magnetizing inductance and one end of the transformer primary winding. The drain of the second switching transistor is connected to the anode of the second capacitor; The cathode of the second capacitor is connected to the source of the first switching transistor, the positive terminal of the fourth diode, the other end of the transformer magnetizing inductor, and the other end of the transformer primary winding. One end of the transformer's secondary winding is connected to the anode of the fifth diode; The cathode of the fifth diode is connected to the anode of the DC bus capacitor and one end of the load; The other end of the transformer's secondary winding is connected to the cathode of the DC bus capacitor and the other end of the load; The third capacitor is connected in parallel with the first switching transistor.

[0008] In one possible implementation, when the first switch is turned on, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned off, the first capacitor discharges and the inductor and transformer leakage inductance are charged.

[0009] In one possible implementation, when the first switch is turned off, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned off, the first capacitor discharges, the third capacitor charges, the inductor charges and then discharges, and the leakage inductance of the transformer discharges.

[0010] In one possible implementation, when the first switch is off, the second switch is off, the first diode is off, the second diode is on, and the fifth diode is off, the first capacitor and the second capacitor are charged, and the inductor and the transformer leakage inductance are discharged.

[0011] In one possible implementation, when the first switch is off, the second switch is off, the first diode is off, the second diode is on, and the fifth diode is on, the first capacitor and the second capacitor are charged, and the inductor and the transformer leakage inductance are discharged.

[0012] In one possible implementation, with the first switch off, the second switch on, the first diode off, the second diode off, and the fifth diode on, the first capacitor is charged, the second capacitor is discharged, and the leakage inductance of the inductor and transformer is discharged.

[0013] In one possible implementation, when the first switch is off, the second switch is off, the first diode is off, the second diode is off, and the fifth diode is on, the first capacitor is charged, the third capacitor is discharged, the inductor is discharged, and the transformer leakage inductance is charged.

[0014] In one possible implementation, when the first switch is off, the second switch is off, the first diode is on, the second diode is off, and the fifth diode is on, the first capacitor is charged, the inductor is discharged, and the transformer leakage inductance is charged.

[0015] In one possible implementation, with the first switch on, the second switch off, the first diode off, the second diode off, and the fifth diode on, the first capacitor is charged and then discharged, while the inductor and the transformer leakage inductance are charged.

[0016] The beneficial effects of this invention are: the on-board charger system provided by this invention improves the stability of the wide output voltage range through the SEPIC circuit, ensuring the efficiency of the OBC in the wide output voltage range. At the same time, the active clamping circuit realizes the soft switching function, avoiding excessive voltage stress on the switching transistor, thereby improving the reliability of the OBC in the wide output voltage range. This invention effectively improves the efficiency and reliability of the OBC in the wide output voltage range. Attached Figure Description

[0017] Figure 1 A schematic diagram of an embodiment of the on-board charger system provided by the present invention; Figure 2 A schematic diagram of another embodiment of the on-board charger system provided by the present invention; Figure 3 A schematic diagram of an embodiment of the first equivalent circuit of the on-board charger system provided by the present invention; Figure 4 A schematic diagram of an embodiment of the second equivalent circuit of the on-board charger system provided by the present invention; Figure 5 A schematic diagram of an embodiment of the third equivalent circuit of the on-board charger system provided by the present invention; Figure 6 A schematic diagram of an embodiment of the fourth equivalent circuit of the on-board charger system provided by the present invention; Figure 7A schematic diagram of an embodiment of the fifth equivalent circuit of the on-board charger system provided by the present invention; Figure 8 A schematic diagram of an embodiment of the sixth equivalent circuit of the on-board charger system provided by the present invention; Figure 9 A schematic diagram of an embodiment of the seventh equivalent circuit of the on-board charger system provided by the present invention; Figure 10 This is a schematic diagram of an embodiment of the eighth equivalent circuit of the on-board charger system provided by the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] In the description of the embodiments of the present invention, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0020] The terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] This invention provides an on-board charger system, which will be described below.

[0023] Figure 1 This is a schematic diagram of an embodiment of the on-board charger system provided by the present invention, as shown below. Figure 1 As shown, the on-board charger system includes: Three-phase AC input, rectifier bridge circuit, SEPIC circuit, DC bus capacitor and load; The rectifier bridge circuit and SEPIC circuit are positioned between each phase of the three-phase AC input and the load. The DC bus capacitor is connected in parallel with the load. The SEPIC circuit contains an active clamping circuit and a transformer circuit.

[0024] It should be noted that the on-board charger system provided by this invention can be applied to equipment charging scenarios, especially high-power charging scenarios for vehicles.

[0025] This invention implements the OBC function by setting up a SEPIC circuit containing an active clamping circuit and a transformer circuit between the three-phase AC input and the load. The SEPIC circuit improves the stability of the wide output voltage range and ensures the efficiency of the OBC over a wide output voltage range. At the same time, the active clamping circuit realizes the soft switching function, avoiding excessive voltage stress on the switching transistor, thereby improving the reliability of the OBC over a wide output voltage range.

[0026] In summary, the on-board charger system provided by this invention improves the stability of the wide output voltage range through the SEPIC circuit, ensuring the efficiency of the OBC within the wide output voltage range. At the same time, the active clamping circuit realizes the soft switching function, avoiding excessive voltage stress on the switching transistor, thereby improving the reliability of the OBC within the wide output voltage range. This invention effectively improves the efficiency and reliability of the OBC within the wide output voltage range.

[0027] In some embodiments of the present invention, the charging circuit structure of each phase between the three-phase AC input and the load is the same, including: AC input power supply, first diode, second diode, third diode, fourth diode, first switching transistor, second switching transistor, fifth diode, first capacitor, second capacitor, third capacitor, inductor, transformer, transformer leakage inductance and transformer magnetizing inductance; The negative terminal of the AC input power supply is connected to the negative terminals of the other two phases of the AC input power supply, and the positive terminal is connected to the positive terminal of the first diode and the negative terminal of the second diode. The positive terminal of the second diode is connected to the positive terminal of the fourth diode and the source terminal of the first switching transistor; The negative terminal of the fourth diode is connected to the negative terminal of the AC input power supply and the positive terminal of the third diode; The negative terminal of the third diode is connected to the negative terminal of the first diode and one end of the inductor; The inductor and the transformer leakage inductance are reverse-coupled, and the other end of the inductor is connected to the drain of the first switching transistor and the anode of the first capacitor. The cathode of the first capacitor is connected to the source of the second switching transistor and one end of the leakage inductance of the transformer. The other end of the transformer leakage inductance is connected to one end of the transformer magnetizing inductance and one end of the transformer primary winding. The drain of the second switching transistor is connected to the anode of the second capacitor; The cathode of the second capacitor is connected to the source of the first switching transistor, the positive terminal of the fourth diode, the other end of the transformer magnetizing inductor, and the other end of the transformer primary winding. One end of the transformer's secondary winding is connected to the anode of the fifth diode; The cathode of the fifth diode is connected to the anode of the DC bus capacitor and one end of the load; The other end of the transformer's secondary winding is connected to the cathode of the DC bus capacitor and the other end of the load; The third capacitor is connected in parallel with the first switching transistor.

[0028] It should be noted that in this invention, the charging circuit structure for each phase between the three-phase AC input and the load is identical, and the specific circuit structure for each phase will not be described in detail here. The drive signals for the first and second switching transistors are complementary, resulting in a dead time. Furthermore, to reduce the size of the magnetic components, the inductor and transformer leakage inductance are designed with reverse coupling.

[0029] In some embodiments of the present invention, when the first switch is turned on, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned off, the first capacitor discharges and the inductor and the transformer leakage inductance are charged.

[0030] It should be noted that when the first switch is turned on, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned off, the first capacitor discharges, and the inductor and the transformer leakage inductance are charged.

[0031] In some embodiments of the present invention, when the first switch is turned off, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned off, the first capacitor discharges, the third capacitor charges, the inductor charges first and then discharges, and the leakage inductance of the transformer discharges.

[0032] It should be noted that when the first switch is turned off, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned off, the first capacitor discharges, the third capacitor charges, the inductor charges first and then discharges, and the leakage inductance of the transformer discharges.

[0033] In some embodiments of the present invention, when the first switch is off, the second switch is off, the first diode is off, the second diode is on, and the fifth diode is off, the first capacitor and the second capacitor are charged, and the inductor and the transformer leakage inductance are discharged.

[0034] It should be noted that when the first switch is turned off, the second switch is turned off, the first diode is turned off, the second diode is turned on, and the fifth diode is turned off, the first capacitor and the second capacitor are charged, and the inductor and the transformer leakage inductance are discharged.

[0035] In some embodiments of the present invention, when the first switch is off, the second switch is off, the first diode is off, the second diode is on, and the fifth diode is on, the first capacitor and the second capacitor are charged, and the inductor and the transformer leakage inductance are discharged.

[0036] It should be noted that when the first switch is turned off, the second switch is turned off, the first diode is turned off, the second diode is turned on, and the fifth diode is turned on, the first capacitor and the second capacitor are charged, and the inductor and the transformer leakage inductance are discharged.

[0037] In some embodiments of the present invention, when the first switch is off, the second switch is on, the first diode is off, the second diode is off, and the fifth diode is on, the first capacitor is charged, the second capacitor is discharged, and the leakage inductance of the inductor and the transformer is discharged.

[0038] It should be noted that when the first switch is off, the second switch is on, the first diode is off, the second diode is off, and the fifth diode is on, the first capacitor is charged, the second capacitor is discharged, and the leakage inductance of the inductor and transformer is discharged.

[0039] In some embodiments of the present invention, when the first switch is turned off, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned on, the first capacitor is charged, the third capacitor is discharged, the inductor is discharged, and the leakage inductance of the transformer is charged.

[0040] It should be noted that when the first switch is turned off, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned on, the first capacitor is charged, the third capacitor is discharged, the inductor is discharged, and the transformer leakage inductance is charged.

[0041] In some embodiments of the present invention, when the first switch is off, the second switch is off, the first diode is on, the second diode is off, and the fifth diode is on, the first capacitor is charged, the inductor is discharged, and the leakage inductance of the transformer is charged.

[0042] It should be noted that when the first switch is turned off, the second switch is turned off, the first diode is turned on, the second diode is turned off, and the fifth diode is turned on, the first capacitor is charged, the inductor is discharged, and the leakage inductance of the transformer is charged.

[0043] In some embodiments of the present invention, when the first switch is turned on, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned on, the first capacitor is charged and then discharged, and the inductor and the leakage inductance of the transformer are charged.

[0044] It should be noted that when the first switch is turned on, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned on, the first capacitor is charged and then discharged, while the inductor and the leakage inductance of the transformer are charged.

[0045] Combination Figure 2 As can be seen, the three-phase charging circuits with the same structure together constitute the on-board charger system provided by this invention. The influence of each switch state on the charging and discharging state of each flying capacitor is shown in the table below:

[0046] Combination Figure 3 Let's look at the switching transistor. On, switching transistor Turn off, diode The capacitor is in the off state. Discharge, while capacitor and capacitor Unaffected, inductor and inductor They're all charging.

[0047] Combination Figure 4 Let's look at the switching transistor. and switching transistor All off, diodes The capacitor is in the off state. Discharge, capacitor Unaffected, capacitor Charging, Inductor Charge first, then discharge; inductor Discharge (inductance) and inductor (Almost unaffected).

[0048] Combination Figure 5 Let's look at the switching transistor. and switching transistor All off, diodes When in the off state, the switching transistor anti-parallel diode It is in the conducting state. Capacitor. and capacitor Both are charging, while the capacitors... Unaffected, inductor and inductor They all discharge.

[0049] Combination Figure 6 Let's look at the switching transistor. and switching transistor All off, diodes When in the ON state, the switching transistor anti-parallel diode It is in the conducting state. Capacitor. and capacitor Both are charging, while the capacitors... Unaffected, inductor and inductor They all discharge.

[0050] Combination Figure 7 Let's look at the switching transistor. Turn off, switching transistor On, diode It is in the conducting state. Capacitor. Charging, capacitor Discharge, while capacitor Unaffected, inductor and inductor They all discharge.

[0051] Combination Figure 8 Let's look at the switching transistor. and switching transistor All off, diodes It is in the conducting state. Capacitor. Charging, capacitor Unaffected, but capacitors Discharge, Inductance Discharge, Inductance Charge.

[0052] Combination Figure 9 Let's look at the switching transistor. and switching transistor All off, diodes When in the ON state, the switching transistor anti-parallel diode It is in the conducting state. Capacitor. Charging, capacitor and capacitor Unaffected, inductor Discharge, Inductance Charge.

[0053] Combination Figure 10 Let's look at the switching transistor. On, switching transistor Turn off, diode It is in the conducting state. Capacitor. Charge first, then discharge; capacitor and capacitor Unaffected, inductor and inductor They're all charging.

[0054] This invention employs an active clamp SEPIC power factor correction circuit, which solves the efficiency problem of the OBC stage and the problem of key power devices withstanding ultra-high voltage stress under high power (11kW) and wide output voltage range (200-1000V) by soft switching and buck-boosting capabilities.

[0055] The on-board charger system provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An on-board charger system, characterized in that, include: Three-phase AC input, rectifier bridge circuit, SEPIC circuit, DC bus capacitor and load; The rectifier bridge circuit and SEPIC circuit are positioned between each phase of the three-phase AC input and the load. The DC bus capacitor is connected in parallel with the load. The SEPIC circuit contains an active clamping circuit and a transformer circuit.

2. The on-board charger system according to claim 1, characterized in that, The charging circuit structure for each phase between the three-phase AC input and the load is identical, including: AC input power supply, first diode, second diode, third diode, fourth diode, first switching transistor, second switching transistor, fifth diode, first capacitor, second capacitor, third capacitor, inductor, transformer, transformer leakage inductance and transformer magnetizing inductance; The negative terminal of the AC input power supply is connected to the negative terminals of the other two phases of the AC input power supply, and the positive terminal is connected to the positive terminal of the first diode and the negative terminal of the second diode. The positive terminal of the second diode is connected to the positive terminal of the fourth diode and the source terminal of the first switching transistor; The negative terminal of the fourth diode is connected to the negative terminal of the AC input power supply and the positive terminal of the third diode; The negative terminal of the third diode is connected to the negative terminal of the first diode and one end of the inductor; The inductor and the transformer leakage inductance are reverse-coupled, and the other end of the inductor is connected to the drain of the first switching transistor and the anode of the first capacitor. The cathode of the first capacitor is connected to the source of the second switching transistor and one end of the leakage inductance of the transformer. The other end of the transformer leakage inductance is connected to one end of the transformer magnetizing inductance and one end of the transformer primary winding. The drain of the second switching transistor is connected to the anode of the second capacitor; The cathode of the second capacitor is connected to the source of the first switching transistor, the positive terminal of the fourth diode, the other end of the transformer magnetizing inductor, and the other end of the transformer primary winding. One end of the transformer's secondary winding is connected to the anode of the fifth diode; The cathode of the fifth diode is connected to the anode of the DC bus capacitor and one end of the load; The other end of the transformer's secondary winding is connected to the cathode of the DC bus capacitor and the other end of the load; The third capacitor is connected in parallel with the first switching transistor.

3. The on-board charger system according to claim 2, characterized in that, When the first switch is on, the second switch is off, the first diode is off, the second diode is off, and the fifth diode is off, the first capacitor discharges, and the inductor and the transformer leakage inductance are charged.

4. The on-board charger system according to claim 2, characterized in that, When the first switch is turned off, the second switch is turned off, the first diode is turned off, the second diode is turned off, and the fifth diode is turned off, the first capacitor discharges, the third capacitor charges, the inductor charges first and then discharges, and the transformer leakage inductance discharges.

5. The on-board charger system according to claim 2, characterized in that, When the first switch is off, the second switch is off, the first diode is off, the second diode is on, and the fifth diode is off, the first capacitor and the second capacitor are charged, and the inductor and the transformer leakage inductance are discharged.

6. The on-board charger system according to claim 2, characterized in that, When the first switch is off, the second switch is off, the first diode is off, the second diode is on, and the fifth diode is on, the first capacitor and the second capacitor are charged, and the inductor and the transformer leakage inductance are discharged.

7. The on-board charger system according to claim 2, characterized in that, When the first switch is off, the second switch is on, the first diode is off, the second diode is off, and the fifth diode is on, the first capacitor is charged, the second capacitor is discharged, and the leakage inductance of the inductor and transformer is discharged.

8. The on-board charger system according to claim 2, characterized in that, When the first switch is off, the second switch is off, the first diode is off, the second diode is off, and the fifth diode is on, the first capacitor is charged, the third capacitor is discharged, the inductor is discharged, and the transformer leakage inductance is charged.

9. The on-board charger system according to claim 2, characterized in that, When the first switch is off, the second switch is off, the first diode is on, the second diode is off, and the fifth diode is on, the first capacitor is charged, the inductor is discharged, and the transformer leakage inductance is charged.

10. The on-board charger system according to claim 2, characterized in that, When the first switch is on, the second switch is off, the first diode is off, the second diode is off, and the fifth diode is on, the first capacitor charges first and then discharges, while the inductor and the transformer leakage inductance are charged.

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