CN106992701B

CN106992701B - Propulsion device and circuit arrangement for operating an electric machine with the aid of two energy stores

Info

Publication number: CN106992701B
Application number: CN201710151803.0A
Authority: CN
Inventors: T·延拜因
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-01-20
Filing date: 2017-01-19
Publication date: 2020-09-18
Anticipated expiration: 2037-01-19
Also published as: DE102016200668A1; CN106992701A

Abstract

The invention relates to a propulsion device and to a circuit arrangement for operating an electric motor (1). The circuit arrangement comprises: a multi-voltage inverter having: -a first interface (2) for a first power supply, -a second interface (3) for a second power supply, and-a third interface (4) for the electric machine (1); and-additional non-linear devices (T19, T20); wherein the additional non-linear device (T19, T20) divides a node (0) between the first interface (2) and the second interface (3) into an upper node (0b) assigned to the first interface and a lower node (0a) assigned to the second interface (3).

Description

Propulsion device and circuit arrangement for operating an electric machine with the aid of two energy stores

Technical Field

The invention relates to a propulsion device and an electrical device for operating an electric machine by means of two electrical energy accumulators. The invention relates in particular to the extension of the functional range and the structure of multi-voltage inverters known from the prior art, also referred to below as "multilevel inverters".

Background

Hybrid battery systems may be designed differently and built with different power electronic topologies. Systems with multilevel inverters are of great importance above all for hybrid applications. Different topologies also exist for multilevel inverters, wherein within the framework of the invention, in particular a multilevel inverter with a neutral connection point (neutral point clamped (NPC) -multilevel inverter) should be observed. NPC-multilevel inverters are basically known in the art and are typically constructed as shown in fig. 1, which will be discussed in depth later. Here, two energy sources are provided for operating the propulsion device or the respective propulsion device.

Disclosure of Invention

The object of the invention is to guide the energy of one energy source and/or of a second energy source to the electric motor, wherein as few ohmic losses as possible should be generated in the semiconductor.

A further object of the invention is to charge the energy store connected to the multilevel converter by means of a second energy store connected to the multilevel converter.

The above-identified object is achieved according to the invention by a circuit arrangement for operating an electric machine. The electric machine can be designed, for example, as a synchronous machine. The electric machine can be designed, for example, as a polyphase electric machine, in particular as a three-phase electric machine. The circuit arrangement substantially comprises a multilevel inverter as is substantially known in the prior art. The multilevel inverter has a first interface for a first power source (for example a battery, a fuel cell or the like) and a second interface for a second power source (for example a battery, a battery or the like). A third interface is provided for electrically contacting the motor. While the above-mentioned elements are known from the prior art, additional non-linear devices (e.g. diodes and/or switches, in particular controllable switches) are provided which separate the nodes between the first interface for the first power supply and the second interface for the second power supply. In other words, the node between the first interface/first power supply and the second interface/second power supply is divided and the additional non-linear device is switched in for subsequent electrical connection between parts of the node. In this way, a first (upper) node and a second (lower) node are obtained, which are (possibly) electrically connected to each other by means of the non-linear device. The circuit arrangement according to the invention as described above additionally knows the operating point of the "two power supplies connected in parallel" in relation to multilevel inverters known in the prior art which only know the operating point of "only the first battery is used for the operation of the electric machine", "only the second battery is used for the operation of the electric machine" and "two batteries are connected in series for the operation of the electric machine". For the parallel connection of the two energy sources, there is no precondition for the voltage level of the energy sources, but in the case of different voltage levels, the energy source with the higher voltage level is used first until both energy sources have almost the same voltage level. Energy is then drawn from both sources. In this way, high currents with the same voltage level can be drawn as desired by means of the invention. The voltage across the motor can be significantly increased by the superposition of the two battery voltages. Additionally, the charge balancing of the used energy storage device can be achieved without additional components and control complexity. Additionally, 650V-IGBTs may be used (e.g., where the energy source voltage levels are up to 450V, respectively). Finally, the battery cell life can be increased by the reduction in load, since the two energy sources are operated in parallel with half the current intensity of each energy source, respectively, instead of the full current intensity and therefore with significantly less losses in the battery and in the circuit. The voltage over the load, for example the motor, can be regulated by a predetermined switching of the switches comprised in the circuit arrangement according to the invention. Depending on the implementation and number of the branches or on the phases of the electric machine, corresponding switching patterns can be used within the basic features in order to achieve the advantages achieved according to the invention.

The dependent claims show preferred embodiments of the invention.

The non-linear device may comprise a diode, thereby simplifying the structure of the additional non-linear device, especially in case the diode is the only additional non-linear device. In order to additionally enable the first power supply to be charged by the second power supply, the additional non-linear device may have at least one controlled first switch. In practice, two Insulated Gate Bipolar Transistors (IGBTs) connected in series with one another in opposite directions are often used, which insulated gate bipolar transistors comprise a freewheeling diode.

Alternatively or additionally, a respective controllable switch may be connected in parallel with the diode of each bridge branch of the multilevel inverter. Under suitable pulse control of the controllable switch, a plurality of operating states can be realized, which are explained in detail with reference to the drawings.

An example of a possible control of the circuit arrangement proposed according to the invention is described by the table contained in claim 3. The rows respectively contained in the operating states I to IV are, for example, passed from top to bottom in chronological order, so that a corresponding time sequence can be derived for the states of the contained elements. The switches T1 to T12 are assigned to the individual half bridges (1.HB (first half bridge), 2.HB (second half bridge), 3.HB (third half bridge)) or branches. The table shown is therefore a switching illustration for the case in which three half-bridges are provided in the circuit arrangement according to the invention (for example for the operation of a three-phase motor). The switching states of the switches T19, T20, which are exemplary components of additional non-linear devices, in combination with the operating state III show the main differences from the prior art. In the table according to claim 3, blank cells mean open switches, D denotes operation as freewheeling diode, and 1 denotes closed (conducting) switches.

In order to be able to use the circuit arrangement according to the invention in addition to the charging of the first battery by the second battery (in driving operation or in stopping operation, in which case the electric machine does not rotate), an inductance can be provided as a storage choke in at least one bridge branch of the multilevel inverter. The inductance or storage choke may, for example, be arranged between the first interface of the first power source and a third interface of the electrical machine (e.g. a respective branch of the multilevel inverter). Alternatively or additionally, the inductance or storage choke may be arranged, for example, between the second interface of the second power source and the third interface of the electrical machine (e.g. the respective branch of the multilevel inverter). By means of the inductance, the current can also be driven counter to higher voltage levels by: first the power supply driving the current through the inductor is cut off or separated from the inductor. In this way, for example, a first battery having a lower voltage level may be used in order to charge a second battery having a higher voltage level.

In order to be able to regulate the output voltage at the third interface of the electric machine by means of the inductance independently of the voltage level of the respective power supply, the device can be configured to operate the predefined switches of the multilevel inverter in pulses. An example of the way in which a circuit arrangement with an additional inductance or a storage choke can be operated is shown by the table according to claim 6, to which the statements made in connection with the table according to claim 3 apply. The operating state IV now relates to the case in which the voltage applied to the first interface is substantially equal to the voltage applied to the second interface, while the operating states V, VI and VII enable new operating states (operating states V and VI) for operating the electric machine in parallel using two power supplies with different voltage levels or in which the energy store connected to the second interface is charged by the energy store connected to the first interface, the voltage applied to the first interface being substantially greater than the voltage applied to the second interface (operating state VII).

In addition to the table according to claim 3, the following names are contained in the table according to claim 6: "FDT" denotes a rectification by the free-wheeling diode of the respective switch during the pulsed operation, "T" denotes the pulsed operation of the respective switch, and "k" is a parameter of the duty cycle during the pulsed operation of the respective switch. In this regard, all percentages between 0 and 100 divisible by 10 are disclosed as possible range limitations of the duty cycle.

The voltage across the motor can be regulated by suitable control of the switches of the circuit arrangement according to the invention. In order to achieve a sinusoidal current flow in the motor, the decision switches of the circuit arrangement must be operated in a suitable manner in pulsed fashion. The switches to be pulsed may be connected in common mode, for example. The duty cycle of the switching mode may be selected in dependence on the voltage levels of the two power supplies on the first interface and the second interface. Even in an arrangement with a storage choke or when operating according to the table in claim 6, the switches of the additional non-linear component can be replaced by diodes, as long as the charging of the first energy store by the second energy store cannot be carried out at will. The operating mode defined by the table according to claim 6 can be adjusted in a corresponding manner by the expert depending on the circuit variant to be adjusted, without this requiring explicit specification. Preferably, a fourth interface can be provided between the inductance (storage choke) and the third interface as a network interface. In order to be able to charge batteries from different energy source types (alternating current, direct current, single phase, three phase, etc.) with as few components as possible, the circuit arrangement according to the invention makes use of the network filter capacitors which are always present in practice at the network interface. In other words, at the fourth interface (which, like the third interface, can be designed as single-phase or polyphase), electrical connection lines to the energy network can be connected, wherein with three network filter capacitors, the battery connected at the first interface can be charged with a three-phase energy source, while with only one network filter capacitor, the battery at the first interface can be charged with a two-phase energy source, and without additional components, the battery at the first interface can be charged with a dc power supply whose voltage level is less than or equal to the voltage level of the battery at the first interface.

According to a second aspect of the invention, a propulsion device (for example a car, a transport vehicle, a truck, an air and/or water vehicle) is proposed, which has a circuit arrangement according to the initially described inventive aspect. The circuit arrangement may be used to power a traction motor or other motor of the propulsion device. The features, combinations of features and advantages derived therefrom correspond obviously to those of the inventive aspects mentioned at the outset, so that reference is made to the above embodiments in order to avoid repetitions.

Drawings

Embodiments of the present invention are described in detail below with reference to the attached drawings. In the drawings:

FIG. 1 is a circuit diagram of one embodiment of a multilevel inverter with neutral connection (NPC-MLI) having two batteries as DC power sources and a three-phase motor;

FIG. 2 is a circuit diagram of a first variant according to the invention of the NPC-MLI according to FIG. 1;

FIG. 3 is a circuit diagram of a second variant according to the invention of the NPC-MLI according to FIG. 1;

FIG. 4 is a circuit diagram of a third variant according to the invention of the NPC-MLI according to FIG. 1;

FIG. 5 is a circuit diagram of a fourth variant according to the invention of the NPC-MLI according to FIG. 1;

FIG. 6 is a circuit diagram of a fifth modification according to the invention of the NPC-MLI according to FIG. 1; and

fig. 7 is a schematic diagram illustrating the components of an embodiment of the propulsion device according to the invention.

Detailed Description

FIG. 1 shows an NPC-MLI with a battery B1 as having an internal resistance R at the first interface 2_i1And a second battery B2 as having an internal resistance R on the second electrical interface 3_i2The direct current power supply of (1). The NPC MLI is coupled on the output side to a three-phase electric machine 1, which has three inductances L1, L2, L3 and, in series with these inductances, ohmic resistors R1, R2, R3, respectively, which represent ohmic losses. The first branch SI connected to the first interface 2 has a first switch T1, a second switch T2, a third switch T3 and a fourth switch T4. In the circuit shown, all switches are designed as insulated gate bipolar transistors ("IGBTs"). A first diode D1 is connected between the second connection of the first switch T1 and the first connection of the second switch T2, said diode being connected on the other side to the neutral connection 0. The flow direction of the diode D1 is oriented in the direction of the first switch T1. Between the second electrical connection 3 and the second switch T2, a third switch T3 and a fourth switch T4 are provided, wherein a second diode D2 is connected between the second connection of the third switch T3 and the first connection of the fourth switch T4, and the other side is electrically connected to the neutral connection 0. The flow direction of the second diode D2 is oriented in the direction of the neutral connection point 0. One phase of the motor 1 is connected between the second port of the second switch T2 and the first port of the third switch T3. The structure of the two remaining branches SII, SIII connected in parallel to the first branch SI with respect to the

electrical interfaces

2, 3 of the NPC-MLI corresponds to the structure of the above-mentioned branch SI, respectively, so that reference is made to the above implementation in order to avoid repetitions.

Fig. 2 shows a first variant according to the invention of an NPC-MLI as already described in detail in connection with fig. 1. Part of the modification is that the neutral connection point 0(NPC) has been divided into an upper node 0b and a lower node 0a by a first IGBT T19 and a second IGBT T20 which are integral parts of the nonlinear device. In other words, the branches SI, SII, SIII which are connected in parallel to the respective battery B1, B2 are designed to be first separated at the same connection point 0 and then electrically connectable to one another again via IGBTT19, T20. In addition, the diodes D1 to D6 are replaced by respective IGBTs T13 to T18 which, in terms of the orientation of their intrinsic diodes, coincide with the IGBTs T2, T3, T6, T7, T10, T11 assigned to the respective third connection point 4. The pulsed operation according to the states listed in the table according to claim 6 enables a parallel operation of the batteries B1, B2 to supply energy to the electric machine 1.

Fig. 3 and 4 show a preferred variant of the circuit arrangement shown in fig. 2, in which the respective inductances L are arranged in the respective three switches T1, T2, T13 in fig. 3; t5, T6, T15; t9, T10, T17 or the respective three switches T3, T4, T14 in fig. 4; t7, T8, T16; the star point of T11, T12, T18 and the corresponding third connection point 4 of the electric machine 1. By pulse control according to the table in claim 6, the inductance L can be used to achieve parallel operation at different voltage levels of the batteries B1, B2 and/or charging operation of one battery by the respective other battery.

Fig. 5 and 6 show a modification of the circuit arrangement according to fig. 3 or 4 as a network interface by inserting an additional fourth interface 5 between the inductance and the third interface. Via the fourth interface 5, an external energy supply interface can be coupled to the circuit arrangement according to the invention. The network filter capacitors which are always present in commercial power supply interfaces, in conjunction with the respective choke coils L, form respective resonant circuits, by means of which the circuit arrangement according to the invention can be provided for charging batteries with particularly few components by means of a plurality of different energy source types (for example, ac voltage, dc voltage, single-phase, three-phase or multi-phase).

Fig. 7 shows a schematic view of an embodiment of a propulsion device 10 according to the invention, in which the motor 1 is used as traction motor. The three phases of the electric machine 1 are electrically connected to a circuit arrangement 6 according to the invention, the first and second connections of which are electrically connected to the respective battery B1, B2, and the fourth connection of which is electrically connected as a network connection to a network plug 7. In this way, the propulsion device 10 shown can have the same features, operating conditions and advantages as have been described in detail previously in connection with the circuit arrangement according to the invention.

Claims

1. Circuit arrangement for operating an electric machine (1), comprising:

multi-voltage inverter, hereinafter referred to as "multi-level inverter", having:

-a first interface (2) for a first power supply,

-a second interface (3) for a second power supply, and

-a third interface (4) for the electric machine (1); and

-additional non-linear devices (T19, T20);

wherein the additional non-linear device (T19, T20) divides a node (0) between the first interface (2) and the second interface (3) into an upper node (0b) assigned to the first interface and a lower node (0a) assigned to the second interface (3), and

wherein the upper node (0b) and the lower node (0a) are electrically connectable to each other via the additional non-linear device (T19, T20) such that the circuit arrangement additionally has an operating point in which the two power supplies are connected in parallel.

2. The circuit arrangement of claim 1,

-the non-linear device (T19, T20) comprises a diode, and/or

-the diodes (D1-D6) of each bridge branch of the multilevel inverter are connected in parallel with the respective controllable switch (T13-T18).

3. Circuit arrangement according to claim 1, wherein the non-linear device (T19, T20) comprises a controllable switch.

4. Circuit arrangement according to claim 3, wherein the controllable switches are IGBTs, wherein the controllable switches are arranged for assuming switching states according to the table described below,

in the table, it is shown that,

- "I" denotes a first operating state in which the device is operated solely with the first power supply (B1) connected to the first interface (2);

- "II" denotes a second operating state in which the device is operated solely with a second power supply (B2) connected to the second interface (3);

- "III" denotes a third operating state in which the device is operated with a first power supply (B1) connected on the first interface (2) in series with a second power supply (B2) connected on the second interface (3);

- "IV" denotes a fourth operating state in which the device is operated with a first power supply (B1) connected on the first interface (2) in parallel with a second power supply (B2) connected on the second interface (3);

- "1. HB" denotes a first half-bridge of the multilevel inverter;

- "2. HB" denotes the second half-bridge of the multilevel inverter;

- "3. HB" denotes the third half-bridge of the multilevel inverter;

- "U _ R1" denotes a first voltage for the first branch of the electrical machine (1) on the third interface (4);

- "U _ R2" represents a second voltage for a second branch of the electrical machine (1) on a third interface (4);

- "U _ R3" represents a third voltage for a third branch of the electrical machine (1) on a third interface (4);

- "S _ B1" denotes the switching state of the first IGBT within the controllable switch;

- "S _ B2" denotes the switching state of the second IGBT within the controllable switch;

- "1" represents the on state;

- "D" denotes the operation of the diode as a freewheeling diode;

- "T1" to "T12" denote the switches of the half-bridge of the multilevel inverter; and

- "u" represents the maximum voltage at the third interface (4).

5. The circuit arrangement of claim 1, wherein

-providing an inductance (L) within at least one bridge branch of the multilevel inverter.

6. Circuit arrangement according to claim 5, wherein the inductance (L) is arranged at

-between a first interface (2) for a first power source (B1) and a third interface (4) for the electric machine (1), and/or

-a second interface (3) for a second power supply (B2) and a third interface (4) for the electric machine (1).

7. Circuit arrangement according to claim 5, wherein the arrangement is arranged for operating predefined switches of the multilevel inverter in pulses.

8. Circuit arrangement according to claim 7, wherein the arrangement is arranged for pulse-running of the predefined switches according to the table depicted below,

in the table, it is shown that,

- "II" denotes a second operating state in which the device is operated solely with the second power supply (B2) connected to the second interface (3);

- "IV" denotes a fourth operating state in which the device is operated with a first power supply (B1) connected to the first interface (2) in parallel with a second power supply (B2) connected to the second interface (3), wherein the voltage applied to the first interface (2) is equal to the voltage applied to the second interface (3);

- "V" denotes a fifth operating state in which the device operates with a first power supply (B1) connected to the first interface (2) in parallel with a second power supply (B2) connected to the second interface (3), wherein the voltage applied to the first interface (2) is lower than the voltage applied to the second interface (3);

- "VI" denotes a sixth operating state in which the device operates with a first power supply (B1) connected on the first interface (2) in parallel with a second power supply (B2) connected on the second interface (3), wherein the voltage applied on the first interface (2) is greater than the voltage applied on the second interface (3);

- "VII" denotes a seventh operating state in which the device is operated such that electrical energy is transmitted from the first interface (2) to the second interface (3), wherein the voltage applied to the first interface (2) is greater than the voltage applied to the second interface (3);

- "VIII" denotes an eighth operating state in which the device is operated such that electrical energy is transmitted from the first interface (2) to the second interface (3), wherein the voltage applied to the first interface (2) is lower than the voltage applied to the second interface (3);

- "IX" denotes a ninth operating state in which the device is operated such that electrical energy is transmitted from the second interface (3) to the first interface (2), wherein the voltage applied at the first interface (2) is smaller than the voltage applied at the second interface (3);

-X represents a tenth operating state in which the device is operated so that electrical energy is transferred from the second interface (3) to the first interface (2), wherein the voltage applied across the first interface (2) is greater than the voltage applied across the second interface (3);

- "1. HB" denotes a first half-bridge of the multilevel inverter;

- "2. HB" denotes the second half-bridge of the multilevel inverter;

- "3. HB" denotes the third half-bridge of the multilevel inverter;

"U _ R1" represents a first voltage for a first branch of the electrical machine (1) on the third interface (4);

"U _ R2" represents a second voltage for a second branch of the electrical machine (1) on a third interface (4);

"U _ R3" represents a third voltage for a third branch of the electrical machine (1) on a third interface (4);

"S _ B1" represents the switching state of the first IGBT within the controllable switch;

"S _ B2" represents the switching state of the second IGBT within the controllable switch;

"1" indicates an on state;

"D" represents the operation of the diode as a freewheeling diode;

"T1" to "T12" represent switches of a half bridge of the multilevel inverter;

"u" represents the maximum voltage on the third interface (4);

"FDT" means rectification by a freewheeling diode when a pulse-operated switch is turned off;

"+" indicates a positive DC voltage in the corresponding branch;

"-" indicates a negative dc voltage in the corresponding branch;

"T" represents the pulsed operation of the corresponding switch; and

"k" represents the duty cycle for the switching pulse operation.

9. Circuit arrangement according to claim 5, 6, 7 or 8, wherein a fourth interface (5) is provided as a grid interface between the inductance (L) and the third interface (4).

10. Circuit arrangement according to one of the preceding claims 1-8,

the electric motor (1) is a synchronous motor and/or a traction motor of the propulsion device.

11. Circuit arrangement according to one of the preceding claims 1 to 8, wherein the third interface (4) is arranged three-phase and the electric machine (1) is a three-phase electric machine.

12. A propulsion device comprising a circuit arrangement according to any of the preceding claims 1-11.