Vehicle battery charging system

Abstract

To provide a device for quickly charging a battery that has two inverter circuits respectively electrically connected to a three-phase electric motor.SOLUTION: In a device, a battery B has one side electrically connected to the positive sides of inverter circuits W1, W2 and the other side to the negative sides of the inverter circuits, the positive terminals of charging voltage connections A1, A2 are connected to a multiway switch MS2, and the negative terminals are connected to the negative side of both the inverter circuits or connected to a further multiway switch MS3, the positive sides of the two inverter circuits can be electrically connected via one multiway switch, and can electrically connect one or more inductors L1 to L3 of one three-phase electric motor M1, and one or more inductors L4 to L6 of the other three-phase electric motor can be electrically connected via one multiway switch or another multiway switch.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The invention relates to the technical field of power electronics, in particular to the fast charging of batteries according to claim 1, preferably automotive batteries according to claim 9. [Background technology]

[0002] An electric vehicle uses electrical energy as its main energy source. Therefore, an electric vehicle basically requires a high-voltage battery for storing electrical energy, at least one motor for converting electrical energy into kinetic energy, and at least one inverter. To improve the driving efficiency of an electric vehicle, it is preferable to use a high-voltage battery. Such a battery requires fast and efficient charging.

[0003] However, if an electric vehicle is to be charged at a charging station with a battery voltage of 800V, the output voltage of the charging station can be either 500V or 800V. At the 800V charging voltage, the battery can be charged directly. The 500V charging voltage must be boosted using a suitable step-up / boost converter. This is usually achieved by an on-board booster in addition to the inverter and electric motor. Summary of the Invention [Problem to be solved by the invention]

[0004] It would be desirable to provide a simpler and more cost-effective method for fast charging batteries. [Means for solving the problem]

[0005] Therefore, the present invention provides an electric motor having two inverter circuits each electrically connected to a three-phase electric motor, one battery electrically connected to the positive side of the inverter circuits and the other battery electrically connected to the negative side of the inverter circuits, and a charging voltage connection, the positive terminal of the charging voltage connection being connected to a multi-way switch, and the negative terminal of the charging voltage connection being connected to the negative sides of both of the inverter circuits or to a further multi-way switch, the positive sides of the two inverter circuits being electrically connectable via one multi-way switch, at least one inductor of one three-phase electric motor being electrically connectable, and at least one inductor of the other three-phase electric motor being electrically connectable via one multi-way switch or via the other multi-way switch.

[0006] The key point here is that the charging voltage is boosted from 500V to 800V without the need for an additional booster. The only components used to boost the charging voltage are those already installed in the electric vehicle (the inverter and electric motor). In particular, the proposed circuit uses only a small number of switches and diodes through which the charging current flows, significantly reducing electrical losses.

[0007] Advantageous further embodiments of the method according to the invention are set forth in the dependent claims.

[0008] According to a first advantageous embodiment, the positive side of the charging voltage connection and the negative side of the charging voltage connection can be electrically connected to separate multi-way switches, and one of the multi-way switches can electrically connect the inductor of one electric motor to the positive side of the inverter circuit, and the other multi-way switch can electrically connect the inductor of the other electric motor to the negative side of the inverter circuit, thereby simplifying the multi-way switch and reducing its cost.

[0009] According to a second advantageous embodiment, a multi-way switch is composed of three diodes or switches, each of which is electrically connected to a respective inverter circuit and a respective inductor of the electric motor. The switches can be designed as transistors, IGBT (insulated gate bipolar transistor) power semiconductors, or contactors. This circuit allows charging at a charging voltage of 500 V and charging at a charging voltage of 800 V.

[0010] According to a further advantageous embodiment, in charging operation at 800V or 500V, one multi-way switch consists of two diodes or two switches and can be electrically connected to the positive side of the inverter circuit via the switch of each of the inverter circuits, resulting in a particularly easy and cost-effective design of the device.

[0011] According to a further advantageous embodiment, it is provided that each of the capacitors electrically connects, preferably electrically switchably connects, the positive side of the inverter circuit with a node of one of the multi-way switches and / or the negative side of the inverter circuit with said node of one of the multi-way switches, which can be used in particular to smooth the input and output voltages of the inverter / inverter.

[0012] According to another advantageous embodiment, an additional inductor is provided in the input path of the charging current, thereby increasing the total number of inductors in the current path of the inverter. The additional inductor is preferably provided upstream or downstream of one of the multi-way switches in the current direction. In particular, it is preferred that only one inductor is inserted upstream of the multi-way switch.

[0013] In principle, the device can be used for fast charging batteries of any type of electric drive system, but it should preferably be used for fast charging vehicle batteries, in particular vehicle batteries of electric vehicles.

[0014] Further advantages, objects and features of the present invention will be explained with reference to the following description taken in conjunction with the accompanying drawings, in which: Similar elements may have the same reference numerals in the various embodiments. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a circuit diagram of a device according to the invention for fast charging a battery; [Figure 2] 3 is another circuit diagram of the device according to the invention for fast charging a battery; [Figure 3] The circuit diagram in Figure 1 shows the multi-way switch with the diodes replaced by switches. [Figure 4] The circuit diagram in Figure 1 replaces the three-diode multi-way switch with a multi-way switch using only two diodes. [Figure 5] Circuit diagram of Figure 1 with an additional capacitor. [Figure 6a] The circuit diagram of Figure 1 with an additional inductor after the current direction of the multi-way switch. [Figure 6b] The circuit diagram of Figure 1 with an additional inductor in front of the current direction of the multi-way switch. [Figure 6c] The circuit diagram of Figure 4 with an additional inductor in front of the current direction of the multi-way switch. DETAILED DESCRIPTION OF THE INVENTION

[0016] 1 is a circuit diagram of a device according to the invention for fast charging a battery B. In this case, the electric vehicle has at least two drives consisting of inverters (W1, W2) and electric motors (M1, M2).

[0017] In this circuit, power is supplied via the phases of the electric motors (M1, M2) rather than via the motor neutral point as in other designs. This has the advantage that the motor neutral point does not need to be derived. According to the invention, current flows from the charging station via the phases of the electric motors (M1, M2) to the neutral point of each electric motor (M1, M2). Starting from the neutral point of the electric motors (M1, M2), the current flows via the two-phase clocked half-bridge of the inverter (W1, W2) to the battery B. The motor inductances (L1...L6) are used as boost chokes.

[0018] Inverter W1 is configured as a half-bridge with switching elements (T1...T6) and can be controlled via a control device. The switching elements are preferably transistors. Preferably, the switching elements (T1...T6) are IGBT (insulated gate bipolar transistor) power semiconductors or SiC (silicon carbide) MOSFETs (metal oxide semiconductor field effect transistors). However, other suitable controllable switching elements are also contemplated. Motor inductor L1 is connected to a half-bridge consisting of switching elements (T1, T2). Motor inductor L2 is connected to a half-bridge consisting of switching elements (T3, T4). Motor inductor L3 is connected to a half-bridge consisting of switching elements (T5, T6). A similar configuration is used for inverter W2.

[0019] To achieve the boost function, a multi-way switch MS1 with diodes (D1, D2, D3) is installed between inverters W1 and W2. Switches (S1, S2) for switching the charging voltage connections (A1, A2) from the external power source are used to safely disconnect the charging contacts during operation.

[0020] In charging mode (500V or 800V), switches S1 and S2 are closed. In driving mode, they are open. In driving mode, diodes D1...D3 have no effect on inverters W1 and W2. In charging mode when the charging voltage is 800V, diode D1 is conductive, allowing charging current to charge battery B through switch S1, diode D1, and switch S2.

[0021] In charging mode with a charging voltage of 500V, diode D1 is blocked. To increase the charging voltage, the charging current of the left inverter / inverter W1 passes through diode D2, inductor L3, and inductors L1 / L2. Switches (T1...T4) increase the charging voltage to 800V, and switches T5 and T6 are disabled. In the right inverter W2, the current passes through diode D3, inductor L6, and inductors L5 / L4. Switches (T9...T12) increase the voltage to 800V.

[0022] The advantage of this is that fewer switches are required. Furthermore, for a charging voltage of 800V, the charging current only needs to flow through diode D1, which significantly reduces losses.

[0023] 2 is another circuit diagram of an apparatus according to the present invention for fast charging a battery B, in which the positive side of the charging voltage is connected via switch S1 to diodes D1 and D2 of multi-way switch MS2, and the negative side of the charging voltage is connected via switch S2 to diodes D3 and D4 of multi-way switch MS3.

[0024] In charging mode (500V or 800V), switches S1 and S2 are closed. In driving mode, they are open. In charging mode with a charging voltage of 800V, diodes D1 and D4 are conductive, and charging current charges battery B through switch S1 and diode D1 on the one hand, and switch S2 and diode D4 on the other hand.

[0025] In charging mode with a charging voltage of 500V, diodes D1 and D4 are blocked. To boost the charging voltage, the charging current of the left inverter / inverter W1 passes through diode D2, inductor L3, and inductors L11 / L2. Switches (T1...T4) are active, and switches T5 and T6 are disabled. In the right inverter W2, current flows through diode D3, inductor L6, and inductors L5 / L4. Switches (T9...T12) are active. Switches T7 and T8 are disabled. By properly operating switches (T1...T4) and (T9...T12), the input voltage is boosted to 800V.

[0026] In principle, the left side of the device, which includes the battery B, the multi-way switch MS2, the inverter W1, and the motor M1, can also be used as a quick charger that boosts the charging voltage from 500V to 800V.

[0027] FIG. 3 is the circuit diagram of FIG. 1 with a multi-way switch MS4 that allows for more targeted control by replacing the diodes (D1...D3) with switches (S3...S5).

[0028] FIG. 4 shows the circuit diagram of the multi-way switch MS5 of FIG. 1, but with only two diodes (D2, D3) instead of three (D1...D3). This circuit is configured without the third diode D1, and in charging mode, the current flows through diode D2 and switch T5 on the one hand, and through diode D3 and switch T7 on the other, with a voltage of 800 V. This circuit allows charging at charging voltages of 500 V and 800 V. The difference from the circuit of FIG. 1 is that when charging at 800 V, the charging current flows through more components: diode D2 and switch T5, and diode D3 and switch T7. However, with the advantage that diode D1 is not required, charging at a charging voltage of 500 V functions exactly like the circuit of FIG. 1, resulting in a particularly simple and cost-effective multi-way switch MS5.

[0029] Figure 5 shows the circuit diagram of Figure 1 with additional capacitors (C1, C2) connected to node K1 to smooth the input and output voltages of the boost circuit. The capacitors (C1, C2) can be connected to node K1 directly or switchably via switches.

[0030] FIG. 6a is a circuit diagram of FIG. 1 with additional inductors (L7, L8) in the downstream of the multi-way switch MS1 in the current direction. By adding an additional inductor to the input path of the charging current, the total inductance of the two boost circuits can be increased. The additional inductors (L7, L8) can be inserted between node K1 and diodes D2 and D3, or between the center tap of the half-bridge and diodes D2 and D3. FIG. 6b is a circuit diagram of FIG. 1 with additional inductors (L7, L8) in the upstream of the multi-way switch MS1 in the current direction.

[0031] Figure 6c shows the circuit diagram of Figure 4 with a single additional inductor L7 in front of the multi-way switch MS5, inserted between the anodes of diodes D2 and D3 and node K1. Diode D1 is connected between node K1 and the positive side of battery B.

[0032] Overall, the device according to the invention for fast charging batteries results in a simple, flexible charging system that is cost-effective and particularly suitable for electric vehicles where voltages of 500V or 800V are readily available. [Explanation of symbols]

[0033] B Battery C1, C2 capacitors MS1…MS5 Multi-way Switch K1 Node L1...L8 inductors M1, M2 electric motors A1, A2 Charging voltage connection S1…S5 switches T1…T12 switches W1,W2 Inverter circuit / inverter

Claims

1. a battery (B) electrically connected to the positive side of the inverter circuits (W1, W2) and the negative side of the inverter circuits (W1, W2), and having charging voltage connections (A1, A2), the positive terminals of the charging voltage connections (A1, A2) being connected to multi-way switches (MS1, MS2, MS4, MS5), and the negative terminals of the charging voltage connections (A1, A2) being connected to the negative sides of both inverter circuits (W1, W2) or to a further multi-way switch (MS3); The positive sides of the two inverter circuits (W1, W2) can be electrically connected via one multi-way switch (MS1, MS2, MS4, MS5), and at least one inductor (L1...L3) of one three-phase electric motor (M1) can be electrically connected, and at least one inductor (L4...L6) of the other three-phase electric motor (M2) can be electrically connected via one multi-way switch (MS1, MS2, MS4, MS5) or via the other multi-way switch (MS3), in this fast charging device for a battery (B).

2. 2. The device of claim 1, wherein the positive side (A1) of the charging voltage connection and the negative side (A2) of the charging voltage connection can be electrically connected to separate multi-way switches (MS2, MS3), one of which can electrically connect an inductor (L3) of one electric motor (M1) to the positive side of the inverter circuit, and the other multi-way switch (MS3) can electrically connect an inductor (L6) of the other electric motor (M2) to the negative side of the inverter circuit.

3. 2. The device of claim 1, wherein one multi-way switch (MS1) is composed of three diodes (D1...D3) or switches (S3...S5), and electrically connects each of the inverter circuits (W1, W2) to each of the inductors (L3, L6) of the electric motors (M1, M2).

4. 2. The device of claim 1, wherein in a charging operation at 800V or 500V, one multi-way switch (MS5) is composed of two diodes (D1, D2) and can be electrically connected to the positive side of each of the inverter circuits (W1, W2) via the switches (T5, T7) of the inverter circuits.

5. 5. The device according to claim 1, wherein each of the capacitors (C1, C2) electrically connects, preferably electrically switchably connects, the positive side of the inverter circuit (W1, W2) to a node (K1) of one multi-way switch (MS1) and / or the negative side of the inverter circuit (W1, W2) to the node (K1) of one multi-way switch (MS1).

6. The device according to any one of claims 1 to 5, comprising additional inductors (L7, L8) in the input path of the charging current.

7. 7. The device according to claim 6, wherein the additional inductors (L7, L8) are provided upstream or downstream in the current direction of one multi-way switch (MS1).

8. 7. The device according to claim 6, wherein one additional inductor (L7) is provided upstream of one multi-way switch (MS4) in the current direction.

9. A method of using a charging device for fast charging vehicle batteries, in particular vehicle batteries of electric vehicles, using a device according to any one of claims 1 to 8.

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