Vehicle charger for charging high voltage battery
By optimizing the winding ratio of the primary and secondary inductors and the bridging circuit design, the problem of low efficiency in high-voltage battery chargers was solved, resulting in a more efficient charging process, simplified control, and improved voltage matching capability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- VOLKSWAGEN AG
- Filing Date
- 2025-11-20
- Publication Date
- 2026-05-22
AI Technical Summary
There is room for improvement in the efficiency of existing high-voltage battery chargers.
By employing a primary and secondary inductor configuration with a specific winding ratio, combined with a rectifier and inverter, it is designed as a 2L or 3L converter, using a half- or full-bridge circuit, and optimizing the charging process through a post-regulator or actively controlled bridge circuit.
It significantly improves the charging efficiency of high-voltage batteries, simplifies the control process, reduces system complexity, and enhances the ability to match charging voltage.
Smart Images
Figure CN122073392A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an on-board charger for charging high-voltage batteries. Background Technology
[0002] For example, a vehicle charger for charging a high-voltage battery is known from document US 2018 / 0222333 A1. It features a rectifier at the alternating voltage charging interface, followed by a bidirectional resonant DC / DC converter. The resonant converter has a primary inductor, wherein a secondary inductor for charging circuitry for the high-voltage battery is arranged on the secondary side. Additionally, another secondary inductor is arranged on the secondary side, by means of which a low-voltage battery can be charged.
[0003] Vehicle chargers for charging high-voltage batteries are known from documents WO 2024 / 233 745 A1, WO 2024 / 092 180 A1, and WO 2022 / 194 433A1, respectively. Each vehicle charger includes a rectifier and an inverter. The inverter is connected to a first primary inductor and a second primary inductor, with the first primary inductor associated with a first secondary inductor and the second primary inductor associated with a second secondary inductor. The first primary inductor is associated with a first rectifier, and the second primary inductor is associated with a second rectifier. The positive port of the first rectifier and the negative port of the second rectifier are connected to the high-voltage battery. An additional secondary inductor with a downstream rectifier is arranged on the secondary side of the first primary inductor, and another secondary inductor with a downstream rectifier is arranged on the secondary side of the second primary inductor. The rectifiers are connected to a vehicle network with at least one low-voltage battery.
[0004] Another on-board charger is known from documents DE 10 2014 013 039 A1, DE 10 2018 128 275 A1 and DE 10 2010006 125 A1, in which multiple secondary inductors are arranged on the secondary side of the inverter. Summary of the Invention
[0005] The technical problem of this invention is to improve the efficiency of on-board chargers used for charging high-voltage batteries.
[0006] The solution to this technical problem is derived by an on-board charger for charging high-voltage batteries according to the present invention. Further advantageous designs of the invention are derived from the specification.
[0007] The on-board charger for charging a high-voltage battery includes a rectifier and an inverter. The inverter is connected to a first primary inductor and a second primary inductor. The first primary inductor is associated with a first secondary inductor, and the second primary inductor is associated with a second secondary inductor. Additionally, the first secondary inductor is associated with a first rectifier, and the second secondary inductor is associated with a second rectifier. The positive terminal of the first rectifier and the negative terminal of the second rectifier are connected to the high-voltage battery. Here, the winding ratio of the primary and secondary inductors is selected such that the first converter, composed of the first primary and secondary inductors, transmits several times more power than the second converter, composed of the second primary and secondary inductors. Furthermore, two additional secondary inductors with downstream rectifiers are arranged on the secondary side of the first primary inductor, and two additional secondary inductors with downstream rectifiers are arranged on the secondary side of the second secondary inductor, wherein the rectifiers are connected to an on-board network with at least one low-voltage battery. Intuitively, the on-board charger has two branches for charging the high-voltage battery and two branches for charging the on-board network. Here, the main portion of the power used to charge the high-voltage battery is transmitted via the first branch, which is advantageous in terms of efficiency optimization.
[0008] The inverter and the first and second rectifiers can be configured as 2L or 3L converters and configured as half- or full-bridge circuits.
[0009] In one embodiment, a buck chopper is arranged at least after the rectifier of another secondary inductor of the primary inductor.
[0010] In another embodiment, the on-board charger is configured such that while charging the high-voltage battery, it also charges the on-board network at least via a secondary inductor of the primary inductor.
[0011] In another embodiment, a post-regulator is arranged after the rectifier of the second-stage inductor, wherein the on-board charger is configured such that the rectifiers of the first-stage and second-stage inductors operate with the same duty cycle and a fixed switching frequency, which significantly simplifies its operation, wherein the charging voltage for the high-voltage battery is matched by the post-regulator.
[0012] Preferably, the post-regulator includes a polarity selector (expander) and a buck chopper. The polarity selector can be omitted if it is ensured that the voltage of the first rectifier is always below the maximum permissible charging voltage of the high-voltage battery.
[0013] In an alternative embodiment, the inverter of the second primary inductor, the additional secondary inductor of the second secondary inductor, and the rectifier of the second secondary inductor are configured as an actively controlled bridge circuit (triple active bridge TAB). In this embodiment, the post-regulator can be omitted, wherein the charging voltage required for the high-voltage battery and the vehicle network battery is set by the actively controlled rectifier.
[0014] In another embodiment, the on-board charger is configured to charge the vehicle network from a high-voltage battery, wherein at least the charging process is carried out uncontrolled via a rectifier of a secondary inductor of the primary inductor.
[0015] In another embodiment, the on-board charger is configured such that the rectifier of the additional secondary inductor of the second secondary inductor is configured as a controlled rectifier or the control of the charging process is performed by a post-regulator. Attached Figure Description
[0016] The invention will now be described in more detail with reference to preferred embodiments. (See attached figures.) Figure 1 A general block diagram of the vehicle charger is shown; Figure 2 The circuit arrangement of the on-board charger in the first embodiment is shown when charging the high-voltage battery; Figure 3 This illustrates how charging the vehicle network from a high-voltage battery is done according to... Figure 2 Circuit layout; Figure 4 The circuit layout of the on-board charger in an alternative embodiment is shown; Figure 5 The circuit arrangement of the on-board charger in another alternative embodiment is shown when charging the high-voltage battery; and Figure 6 This illustrates how charging the vehicle network from a high-voltage battery is done according to... Figure 5 The circuit layout. Detailed Implementation
[0017] exist Figure 1The basic structure of the vehicle charger 1 is shown. The vehicle charger 1 has an alternating voltage charging interface 2 for connecting the vehicle charger 1 to an external alternating voltage source. Additionally, the vehicle charger 1 has a rectifier 3, which preferably has a PFC filter. Here, an additional EMV filter may also be arranged between the alternating voltage charging interface 2 and the rectifier 3. Furthermore, an inverter 4 is provided, which is used to convert the rectified output voltage of the rectifier 3 back into an alternating voltage. The inverter 4 is connected to a first primary inductor LP1 and a second primary inductor LP2. The first primary inductor LP1 is associated with a first primary inductor LS1, and the second primary inductor LP2 is associated with a second primary inductor LS2, which are respectively coupled through a common core. A rectifier 5 is arranged after the first primary inductor LS1, and an additional rectifier 6 is arranged after the second primary inductor LS2, and optionally a post-regulator 7 may be arranged after them. The positive terminal A- of the first rectifier 5 is connected to the positive terminal of the high-voltage battery 8, while the negative terminal A+ of the second rectifier 6 is connected to the negative terminal of the high-voltage battery 8. The first primary inductor LS1 is also associated with two additional secondary inductors LS3 and LS4. Similarly, the second secondary inductor LS2 is also associated with two additional secondary inductors LS5 and LS6, meaning they are coupled to the same core. Secondary inductors LS3 and LS4 are connected to rectifier 9, while secondary inductors LS5 and LS6 are connected to another rectifier 10, which may also include a buck chopper. On the output side, these two rectifiers 9 and 10 are connected to the vehicle network, which has at least one vehicle network battery LV.
[0018] exist Figure 2 The image shows a first embodiment of the on-board charger 1, which is charged from an external alternating voltage, wherein the rectifier 3 is not shown (see [reference]). Figure 1The arrows indicate the direction of energy flow, with the thickness of the arrow representing the amount of energy. It can be identified that the main portion of the energy is transferred via the first primary inductor LP1 and the second primary inductor LS1. Inverter 4 has two active half-bridges, connected to the first primary inductor LP1 and the second primary inductor LP2 respectively via switching element S1. Capacitors and coils are additionally arranged at inductors LP1 and LP2, respectively. Switching element S1 is closed during charging operation. The transistors of inverter 4 are operated with a fixed switching frequency and a fixed duty cycle. Rectifiers 5 and 6 at the first primary inductor LS1 and the second primary inductor LS2 also have two active half-bridges with transistors and idle diodes. Rectifiers 5 and 6 are also operated with a fixed switching frequency and duty cycle, where active matching of the charging voltage to the voltage of the high-voltage battery 8 is achieved by a post-regulator 7. For this purpose, the post-regulator 7 has a polarity selector 11 (expander) and a buck chopper 12. The positive port of rectifier 5 and the center tap of polarity selector 11 are located at the positive and negative ports of high-voltage battery 8 for charging. The negative port of rectifier 5 is abutted against the center tap of buck chopper 12. Simultaneously with charging high-voltage battery 8, the vehicle network is charged via rectifier 9, in this embodiment where a buck chopper is arranged after rectifier 9. For this purpose, the transistors of rectifier 9 are operated by the switching element S3 with a fixed switching frequency and duty cycle, thereby charging the vehicle network with a constant, unregulated power. Rectifier 10 is inactive and switching element S2 remains open. Regulation of the charging process is achieved only via the post-regulator 7.
[0019] exist Figure 3 The diagram illustrates the power flow during charging of the vehicle network from the high-voltage battery 8 via the onboard charger 1. Switching element S1 is opened here, thus preventing power flow towards the alternating voltage charging interface 2. Switching element S2 is permanently closed (in...). Figure 3 The diagram also shows the switch S3 being permanently closed. Rectifiers 9 and 10 operate as uncontrolled rectifiers. The rear regulator 7 regulates the power flow to the vehicle network, where most of the power is transmitted uncontrolled via rectifier 5, which operates as an inverter. Power transmission occurs inductively here from the primary inductor LS1 to the secondary inductors LS3 and LS4, and from the secondary inductor LS2 to the secondary inductors LS5 and LS6.
[0020] exist Figure 4 An alternative implementation is shown, wherein, according to Figure 2 and Figure 3 The only difference in this implementation is that the rectifier 9 does not have a buck chopper, i.e., the diode and choke are eliminated. In this implementation, the on-board network is not charged during alternating voltage charging, and the switching element S3 remains open.
[0021] exist Figure 5 and Figure 6 Another alternative embodiment of the on-board charger 1 is shown. Here, the regulator 7 is omitted, and the two rectifiers 5 and 6 are connected in series. Rectifier 5 operates at a fixed switching frequency, through which the main flow of energy passes. Rectifier 10 has an active bridge circuit, in which the bridge circuits of inverter 4, rectifier 6, and rectifier 10 operate as a triple active bridge (TAB) to regulate the charging power to the high-voltage battery 8 and the vehicle network. In alternating voltage charging, switching element S3 remains open while switching element S1 is closed. Alternatively, as in... Figure 4 This eliminates the need for a buck chopper, thus reducing the number of switches in the system, which, according to... Figures 2 to 4 Compared to the previous implementation plan, the transformer needs to be designed to be slightly larger.
[0022] exist Figure 6 The diagram illustrates the power flow when charging the vehicle network from the high-voltage battery 8. Preferably, the switching element S1 is turned on, transforming the triple active bridge TAB into a dual active bridge. Alternatively, a bridging circuit can be provided on the primary side of each capacitor, in which case the switching element S1 can be eliminated, since the voltage on the primary side can then be controlled by the triple active bridge TAB.
[0023] List of reference numerals 1 Car charger 2 Alternating voltage charging interface 3 Rectifier 4 Inverter 5 Rectifiers 6 Rectifiers 7. Rear regulator 8. High-voltage batteries 9 Rectifier 10 Rectifier 11. Polarity Selector 12. Buck Chopper LP1 First Primary Inductor LP2 Second Primary Inductor LSI primary inductor LS2 secondary inductor LS3-LS6 additional secondary inductors LV low-voltage battery S1 Switching Element S2 switching element S3 Switching element.
Claims
1. An on-board charger (1) for charging a high-voltage battery (8), wherein, The on-board charger (1) has a rectifier (3) and an inverter (4), wherein the inverter (4) is connected to a first primary inductor (LP1) and a second primary inductor (LP2), wherein the first primary inductor (LP1) is associated with a first secondary inductor (LS1) and the second primary inductor (LP2) is associated with a second secondary inductor (LS2), wherein the first secondary inductor (LS1) is associated with a first rectifier (5) and the second secondary inductor (LS2) is associated with a second rectifier (6), wherein the positive interface of the first rectifier (5) and the negative interface of the second rectifier (6) are connected to the high-voltage battery (8), wherein the primary inductor and the secondary inductor... The winding ratio of the inductors (LP1, LP2, LS1, LS2) is selected such that the first converter, consisting of the first primary and secondary inductors (LR1, LS1), transmits multiple times more power than the second converter, consisting of the second primary and secondary inductors (LP2, LS2). Two additional secondary inductors (LS3, LS4) with downstream rectifiers (9) are arranged on the secondary side of the first primary inductor (LS1), and two additional secondary inductors (LS5, LS6) with downstream rectifiers (10) are arranged on the secondary side of the second primary inductor (LP2). The rectifiers (9, 10) are connected to an onboard network with at least one low-voltage battery (LV).
2. The vehicle charger (1) according to claim 1, characterized in that, A buck chopper is arranged downstream of at least the secondary inductors (LS3, LS4) of the primary inductor (LS1) and the rectifier (9).
3. The vehicle charger (1) according to claim 2, characterized in that, The on-board charger (1) is configured such that while the high-voltage battery (8) is being charged, the on-board network carrying the at least one low-voltage battery (LV) is also being charged via at least one secondary inductor (LS3, LS4) of the primary primary inductor (LS1).
4. The vehicle charger (1) according to any one of the preceding claims, characterized in that, A rear regulator (7) is arranged after the second rectifier (6) of the second stage inductor (LS2), wherein the on-board charger (1) is configured such that the first and second rectifiers (5,6) of the first stage inductor (LS1) and the second stage inductor (LS2) operate with the same duty cycle and a fixed switching frequency.
5. The vehicle charger (1) according to claim 4, characterized in that, The post-regulator (7) has a polarity selector (11) and a buck chopper (12).
6. The vehicle charger (1) according to claim 1, characterized in that, The inverter (4) of the second primary inductor (LP2), the other secondary inductors (LS5, LS6) of the second secondary inductor (LS2) and the second rectifier (6) of the second secondary inductor (LS2) are configured as an actively controlled bridge circuit.
7. The vehicle charger (1) according to any one of the preceding claims, characterized in that, The on-board charger (1) is configured to charge the vehicle network from the high-voltage battery (8), wherein at least the charging process is carried out uncontrolled via a downstream rectifier (9) of another secondary inductor (LS3, LS4) of the primary inductor (LS1).
8. The vehicle charger (1) according to claim 7, characterized in that, The downstream rectifier (10) of the other secondary inductors (LS5, LS6) of the second secondary inductor (LS2) is configured as a controlled rectifier or the control of the charging process is performed by the post-regulator (7).