System for charging a vehicle battery

Abstract

The invention relates to a device for rapidly charging a battery B, comprising two inverter circuits W1, W2, each electrically connected to a three-phase electric motor M1, M2, wherein the battery B is electrically connected on the one hand to an inverter positive and on the other hand to an inverter negative of the inverter circuits W1, W2, and comprising a charging voltage connection A1, A2, the positive pole of which is connectable to a multi-way switch MS1, MS2, MS4, MS5, and the negative pole of which is connectable to the inverter negative of both inverter circuits W1, W2 or to a further multi-way switch MS3, wherein the inverter positive of the two inverter circuits W1, W2 can be electrically connected via the one multi-way switch MS1, MS2, MS4, M5, at least one inductance L1...L3 of one electric motor M1 is electrically connectable, and at least one inductance L4 ... L6 of the other electric motor M2 is electrically connectable via the one multi-way switch MS1, MS2, MS4, MS5 or via the further multi-way switch MS3. The invention also relates to the preferred use of the device.

Description

[0001] The invention relates to the technical field of power electronics and in particular to the rapid charging of a battery according to claim 1, preferably an automotive battery according to claim 9.

[0002] An electric vehicle uses electrical energy as its primary power source. Accordingly, the electric vehicle essentially requires a high-voltage battery to store electrical energy, at least one motor, and at least one inverter to convert the electrical energy into kinetic energy. To increase the efficiency of the electric vehicle's drive, high-voltage batteries are preferably used. Fast and efficient charging of such batteries is essential.

[0003] However, if an electric vehicle is to be charged at a charging station with a battery voltage of 800 V, the charging station's output voltage can be 500 V or 800 V. With a charging voltage of 800 V, the battery can be charged directly. A charging voltage of 500 V must be increased by a suitable voltage booster / step-up converter. This is usually achieved by a voltage booster installed in addition to the inverter and the electric motor.

[0004] The generic document DE 10 2023 126 877 A1 relates to a vehicle electrical system with two inverters for driving two electrical machines and a charging facility.

[0005] An object of the present invention is to realize a rapid charging of a battery in a simpler and more cost-effective manner.

[0006] This object is achieved by a device for quickly charging a battery, with two inverter circuits, each of which is electrically connected to a three-phase electric motor, the battery being electrically connected on the one hand to an inverter positive and on the other hand to an inverter negative of the inverter circuits, and with a charging voltage connection whose positive pole can be connected to a multi-way switch and whose negative pole can be connected to the inverter negative of both inverter circuits or to a further multi-way switch, the inverter positive of the two inverter circuits being electrically connectable via the one multi-way switch, and at least one inductance of one electric motor being electrically connectable, and at least one inductance of the other electric motor being electrically connectable via the one multi-way switch or via the further multi-way switch.

[0007] A key aspect is boosting the charging voltage from 500 V to 800 V without the need for an additional voltage booster. Only the components already installed in an electric car (inverter and electric motor) are used to boost the charging voltage. In particular, the charging current in the proposed circuit must flow through a small number of switches and diodes, significantly reducing electrical losses.

[0008] Advantageous developments of the method according to the invention are specified in the subclaims.

[0009] In a first advantageous embodiment, it is therefore provided that a charging voltage connection plus and a charging voltage connection minus can be electrically connected to separate multi-way switches, of which an inductance of one electric motor and an inverter plus can be electrically connected via one multi-way switch, and an inductance of the other electric motor and an inverter minus can be electrically connected via the other multi-way switch. This allows the multi-way switches to be designed more simply and cost-effectively.

[0010] In a second advantageous embodiment, the multi-way switch comprises three diodes or switches, via which the respective inverter circuits and the respective inductors of the electric motors can be electrically connected, thus enabling a simple and cost-effective provision of a multi-way switch. The switches can also be configured as transistors, IGBT (insulated-gate bipolar transistor) power semiconductors, or as contactors. With this circuit, charging at 500 V and 800 V charging voltages is possible.

[0011] In a further advantageous embodiment, it is provided that, during charging operation at 800 V or 500 V, the multi-way switch comprises two diodes or switches which can be electrically connected to the inverter plus via switches of a respective inverter circuit, thus resulting in a particularly simple and cost-effective construction of the device.

[0012] In a further advantageous embodiment, respective capacitors electrically connect, preferably in an electrically switchable manner, the inverter positive terminal of the inverters and a node of the multi-way switch and / or the inverter negative terminal of the inverters and the node of the multi-way switch. This can, in particular, smooth the input and output voltages of the inverters.

[0013] In a further advantageous embodiment, additional inductances are provided in the input path of a charging current, thereby increasing the total value of the inductances in the current paths of the inverters. It is preferred that the additional inductances are provided upstream or downstream of the multi-way switch in the current direction. Particularly preferred is only a single inductance inserted upstream of the multi-way switch.

[0014] In principle, the device for rapid charging a battery can be used in any type of electric drive system. However, it is preferably used for rapid charging an automotive battery, in particular an automotive battery of an electric vehicle.

[0015] Further advantages, objects, and features of the present invention will be explained in the following description of the accompanying figures. Similar components may have the same reference numerals in the various embodiments. They show: Fig. 1 is a circuit diagram of a device according to the invention for rapidly charging a battery; Fig. 2 shows an alternative circuit diagram of a device according to the invention for rapid charging of a battery; Fig. 3 the circuit diagram of the Fig. 1 with a multi-way switch in which the diodes are replaced by switches; Fig. 4 the circuit diagram of the Fig. 1 with a multi-way switch, with only two instead of three diodes; Fig. 5 the circuit diagram of the Fig. 1 with additional capacitors; Fig. 6a the circuit diagram of the Fig. 1 with additional inductances, in the current direction behind the multi-way switch; Fig. 6b the circuit diagram of the Fig. 1 with additional inductances, in the current direction before the multi-way switch, and Fig. 6c the circuit diagram of the Fig. 4 with additional inductances, in the current direction before the multi-way switch.

[0016] The Fig. 1 shows a circuit diagram of a device according to the invention for fast charging a battery B. In this case, an electric car has at least two drives, each consisting of an inverter W1, W2 and an electric motor M1, M2.

[0017] In this circuit, power is not fed in via a motor star point - as in other designs - but via a phase of the electric motors M1, M2. This has the advantage that the motor star point does not have to be brought out. According to the invention, the current flows from a charging station via a phase of the electric motors M1, M2 to the star point of the respective electric motors M1, M2. Starting from the star point of the electric motors M1, M2, the current flows via two phases and clocked half-bridges of the inverter W1, W2 to the battery B. The motor inductors L1 ... L6 are advantageously used as boost chokes.

[0018] The power inverter W1 comprises half-bridges with the switching elements T1 to T6, which can be controlled via a control device. The switching elements are preferably transistors. Preferably, the switching elements T1 to T6 are IGBT (Insulated-Gate Bipolar Transistor) power semiconductors or SIC (Silicon Carbide) MOSFETS (Meta-Oxide Semiconductor Field-Effect Transistor). However, other suitable controllable switching elements are also conceivable. The motor inductance L1 is connected to the half-bridge comprising the switching elements T1 and T2. The motor inductance L2 is connected to the half-bridge comprising the switching elements T3 and T4. The motor inductance L3 is connected to the half-bridge comprising the switching elements T5 and T6. The same applies to the power inverter W2.

[0019] To implement the boost function, a multi-way switch MS1 with diodes D1, D2, and D3 is installed between the inverters W1 and W2. To ensure safe isolation of the charging contacts during driving, switches S1 and S2 are used, which connect the charging voltage terminals A1 and A2 to the external power supply.

[0020] During charging (at 500 V or 800 V), switches S1 and S2 are closed. During driving, they are open. During driving, diodes D1 ... D3 have no effect on inverters W1 and W2. During charging with a charging voltage of 800 V, diode D1 becomes conductive, and the charging current can charge battery B via switch S1 and diode D1 as well as switch S2.

[0021] During charging at a charging voltage of 500 V, diode D1 is blocked. To boost the charging voltage, the charging current in the left inverter W1 is conducted via diode D2, inductor L3, and inductors L1 / L2. Switches T1 ... T4 boost the charging voltage to 800 V. Switches T5 and T6 are blocked. In the right inverter W2, the current is conducted via diode D3 and inductors L6, L5 / L4. Switches T9 ... T12 boost the voltage to 800 V. Switches T7 and T8 are blocked.

[0022] The advantage is the reduced number of switches required. Furthermore, at a charging voltage of 800 V, the charging current only needs to flow through diode D1, significantly reducing losses.

[0023] The Fig. Figure 2 shows an alternative circuit diagram of a device according to the invention for rapid charging a battery B. The device provides that a positive charging voltage is connected via S1 to the diodes D1 and D2 of a multi-way switch MS2. The negative charging voltage is connected via switch S2 to the diodes D3 and D4 of a multi-way switch MS3.

[0024] During charging (at 500 V or 800 V), switches S1 and S2 are closed. During driving, they are open. During charging at a charging voltage of 800 V, diodes D1 and D4 become conductive, allowing the charging current to charge battery B via S1 and D1 on the one hand, and S2 and D4 on the other.

[0025] During charging with a charging voltage of 500 V, diodes D1 and D4 are blocked. To boost the charging voltage, the charging current in the left inverter W1 is conducted via diode D2, inductor L3, and inductors L1 / L2. Switches T1...T4 are activated. Switches T5 and T6 are blocked. In the right inverter W2, the current is conducted via diode D3 and inductors L6, L5 / L4. Switches T9...T12 are activated. Switches T7 and T8 are blocked. By appropriately controlling switches T1...T4 and T9...T12, the input voltage is boosted to 800 V.

[0026] In principle, the left side of the device with battery B, multi-way switch MS2, inverter W1 and motor M1 could also be used as a fast charging device to boost a charging voltage from 500 V to 800 V.

[0027] The Fig. 3 shows the circuit diagram of the Fig. 1 with a multi-way switch MS4, in which the diodes D1 ... D3 have been replaced by switches S3 ... S5, which allows more targeted control of the switches S3 ... S5.

[0028] The Fig. 4 shows the circuit diagram of the Fig. 1 with a multi-way switch MS5, with only two instead of three diodes D2, D3. This circuit is therefore constructed without a third diode D1, whereby the current in charging mode with a voltage of 800 V is conducted on the one hand via diode D2 and switch T5, and on the other hand via diode D3 and switch T7. In this circuit, charging at 500 V and 800 V charging voltage is possible. The difference to the circuit in Fig. 1 is that when charging with 800 V, the charging current flows through more components such as diode D2 and switch T5 or diode D3 and switch T7. However, the advantage is that diode D1 is not needed, and charging with 500 V charging voltage works the same as in the circuit in Fig. 1. This results in a particularly simple and cost-effective multi-way switch MS5.

[0029] The Fig. 5 shows the circuit diagram of the Fig. 1 with additional capacitors C1, C2. These are connected to node K1 to smooth the input and output voltage of the booster circuits. The capacitors C1, C2 can be connected directly to node K1 or switchably connected via a switch.

[0030] The Fig. 6a shows the circuit diagram of the Fig. 1 with additional inductors L7, L8, in the current direction behind the multi-way switch MS5. By adding additional inductors in the input path of the charging current, the total value of the inductances of the two booster circuits can be increased. The additional inductors L7 and L8 can be inserted either between the node K1 and D2 and D3 or between the center tap of the half-bridges and D2 and D3. Fig. 6b shows the circuit diagram of the Fig. 1 with additional inductances, in the current direction before the multi-way switch MS1.

[0031] The Fig. 6c shows the circuit diagram of the Fig. 4 with an additional single inductor L7, upstream of the multi-way switch MS4. This is inserted here between the anode of diode D2 and diode D3 and node K1. Diode D1 is connected between node K1 and a battery positive.

[0032] Overall, the device according to the invention for fast charging a battery results in a simple and flexible, cost-effective charging system that is particularly suitable for electric vehicles and can easily use provided voltages of 500 V or 800 V. List of reference symbols B battery C1, C2 capacitors MS1 ... MS5 multi-way switch K1 junction L1 ... L8 inductors M1, M2 electric motors A1, A2 charging voltage connection S1 ... S5 switch T1 ... T12 switch W1, W2 inverter circuits / inverters

Claims

[1] Device for fast charging a battery (B), with two inverter circuits (W1, W2), each electrically connected to a three-phase electric motor (M1, M2), and with a charging voltage connection (A1, A2), the positive pole of which can be connected to a multi-way switch (MS1, MS2, MS4, MS5), and the negative pole of which can be connected to the inverter negative of both inverter circuits (W1, W2) or to a further multi-way switch (MS3), wherein the inverter positive of the two inverter circuits (W1, W2) can be electrically connected via one multi-way switch (MS1, MS2, MS4, M5), and at least one inductance (L1 ... L3) of one electric motor (M1) can be electrically connected via one multi-way switch (MS1, MS2, MS4, MS5) or via the further multi-way switch (MS3), at least one inductance (L4 ... L6) of the other electric motor (M2) can be electrically connected, characterized bythat the battery (B) is electrically connected on the one hand to an inverter plus and on the other hand to an inverter minus of the inverter circuits (W1, W2). [2] Device according to claim 1, characterized by that a charging voltage connection plus (A1) and a charging voltage connection minus (S2) can be electrically connected to separate multi-way switches (MS2, MS3), of which an inductance (L3) of one electric motor (M1) and an inverter plus can be electrically connected via one multi-way switch (MS2), and an inductance (L6) of the other electric motor (M2) and an inverter minus can be electrically connected via the further multi-way switch (MS3). [3] Device according to claim 1, characterized bythat the one multi-way switch (MS1) comprises three diodes (D1 ... D3) or switches (S3 ... S5), via which the respective inverter circuits (W1, W2) and the respective inductances (L3, L6) of the electric motors (M1, M2) can be electrically connected. [4] Device according to claim 1, characterized by that during charging operation at 800 V or 500 V, one multi-way switch (MS5) comprises two diodes (D1, D2) which can be electrically connected to the inverter plus of a respective inverter circuit (W1, W2) via switches (T5, T7). [5] Device according to one of the preceding claims, characterized by that respective capacitors (C1, C2) electrically, preferably electrically switchably, connect the inverter plus of the inverters (W1, W2) and a node (K1) of one multi-way switch (MS1) and / or the inverter minus of the inverters (W1, W2) and the node (K1) of one multi-way switch (MS1) to one another. [6] Device according to one of the preceding claims, characterized by that additional inductances (L7, L8) are provided in the input path of a charging current. [7] Device according to claim 6, characterized by that the additional inductances (L7, L8) are provided in the current direction before or after the one multi-way switch (MS1). [8] Device according to claim 6, characterized by that a single additional inductance (L7) is provided in the current direction before the one multi-way switch (MS4). [9] Use of a device according to one of the preceding claims for rapid charging of an automobile battery, in particular the automobile battery of an electric vehicle.

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