WO2012136395A1

WO2012136395A1 - Battery cycloconverter in a ring configuration

Info

Publication number: WO2012136395A1
Application number: PCT/EP2012/051440
Authority: WO
Inventors: Volker Schueren
Original assignee: Robert Bosch Gmbh
Priority date: 2011-04-05
Filing date: 2012-01-30
Publication date: 2012-10-11
Also published as: DE102011006762A1

Abstract

The invention relates to an electric drive system having an inverter for supplying power to an n-phase electric machine (11), wherein n ≥ 2, having a plurality of energy storage modules (2a, 2b, 2c, 2d) which are arranged in series connection in a ring line (1). Each of the plurality of energy storage modules (2a, 2b, 2c, 2d) comprises a first connection and a second connection, an energy storage cell that comprises at least one energy store (6a, 6b, 6c, 6d) and that is coupled between the first connection and the second connection, an annular switchgear (5a, 5b, 5c, 5d) that is designed to switchably connect the energy storage cell to the first connection of the energy storage module (2a, 2b, 2c, 2d), and a first coupling device (21a-21c; 22a-22c; 23a-23c; 24a-24c) that is designed to switchably connect a node between the second connection and the energy storage cell to one of the phase lines (11a, 11b, 11c) of the electric machine (11).

Description

Description title

Battery direct converter in ring configuration

The invention relates to a battery direct converter with energy storage modules, which are arranged in a ring configuration, for feeding an electric machine.

State of the art

It is becoming apparent that in the future, both in stationary applications, such as wind turbines, as well as in vehicles, such as hybrid or electric vehicles, increasingly electronic systems are used, the new

Combining energy storage technologies with electrical drive technology. In order to meet the given requirements for a given application in terms of performance and energy, usually several battery cells are connected in series. Since the current provided by such a drive system must flow through all the battery cells and a battery cell can only conduct a limited current, battery cells are often additionally connected in parallel in order to increase the maximum current.

The series connection of several battery cells in addition to a high total voltage involves the problem that the entire energy storage fails if a single battery cell fails, because then no battery power can flow. Such a failure of the energy storage can lead to a failure of the entire system. In a vehicle, failure of the traction battery can result in the vehicle "stalling". For other applications, such as the rotor blade adjustment of

Wind turbines, it may in unfavorable conditions, such. strong Wnd, even come to safety-threatening situations. Therefore, it is always high

Reliability of the energy storage, where "reliability" is the ability of a system to work for a given time error-free.

It is therefore possible to operate batteries with several battery module strings, which can be connected directly to phase lines of an electrical machine. The

Battery module strands have a plurality of series-connected Battery modules, wherein each battery module has at least one battery cell and an associated controllable coupling unit, which allows depending on control signals to interrupt the respective battery module strand, or to bridge the respectively associated at least one battery cell, or the respectively associated at least one battery cell in the respective Battery module strand to switch. By suitable control of the coupling units, for example by means of pulse width modulation, suitable phase signals for controlling the electrical machine can also be provided so that a separate pulse inverter can be dispensed with.

For example, document US 5,642,275 discloses a drive system for a three-phase electric machine with cascaded inverters, each of which is assigned a single battery cell. The document US 6,577,087 B2 discloses a multi-stage drive system with a pulse inverter and a strand of selectively bridgeable battery cells for

Supply of an electrical machine with graded supply voltages.

The publication JP 2000-0341964 A also discloses a drive system with multi-stage switchable supply voltage.

Disclosure of the invention

According to one embodiment, the present invention provides an inverter for supplying an n-phase electric machine, where n> 2, having a plurality of energy storage modules arranged in series in a loop, each of the plurality of energy storage modules having a first terminal and a second Connection, an energy storage cell, which at least one

Energy storage, and which is coupled between the first terminal and the second terminal, a ring switching device, which is adapted to the

Energy storage cell to connect to a first terminal of the energy storage module switchable, and a first coupling device which is adapted to connect a node between the second terminal and the energy storage cell switchably connected to one of the phase lines of the electric machine comprises.

According to a further embodiment, the present invention provides a system an inverter according to the invention and an n-phase electric machine, wherein n> 2, which is connected via n phase lines respectively to the first coupling means of the plurality of energy storage modules of the inverter. According to a further embodiment, the present invention provides a method for operating a system according to the invention. The method includes the steps of opening one of the ring switching devices of the plurality of energy storage modules while simultaneously closing the remaining ring switching devices, and selectively driving the first coupling devices to connect the n phase lines to each of the plurality of energy storage modules.

Advantages of the invention

An idea of the invention is to provide a battery powered drive system which can provide a stepped supply voltage to an n-phase electric machine. For this purpose, energy storage modules are arranged in a ring, which at freely selectable locations on switching devices in a chain of

Energy storage modules can be separated. Thereby can

Energy storage cells, which are arranged in the energy storage modules are variably connected in the chain for supplying power to phase lines of the electric machine.

This topology also allows a uniform load of all

Energy storage cells or all energy storage modules, so that to achieve a respective supply voltage value, the individual energy storage cells can be charged different current by appropriate connection and disconnection. Thus, on average over time, a uniform average load of all

Energy storage cells can be achieved. In addition, the system is against a failure or defect of a single

Energy storage cell or a single energy storage module robust, because each of the energy storage cells can be switched either via the ring switching devices permanently to the end of the power supply chain, where it does not bother or useful, or be bridged over one of the phase lines using the first coupling devices. In both cases, the drive system with the rest Energy storage modules are still safe to continue to operate, so that the

Reliability of the entire system is very high.

The number of times required to produce any three-phase systems required

Energy storage cells is very low in the system according to the invention, whereby a space-saving and cost-effective design is possible.

Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings.

Brief description of the drawings

1 shows a schematic representation of an embodiment of a

system according to the invention;

Fig. 1a is a schematic representation of an energy storage module of the system in Fig. 1 in greater detail according to another embodiment of the invention;

Fig. 2 is a schematic representation of another embodiment of a system according to the invention; Fig. 3 is a schematic representation of another embodiment of a system according to the invention; and

4 shows a schematic illustration of a method for operating a system according to the invention according to a further embodiment.

Fig. 1 shows an electric drive system 10 for supplying an electric machine 1 1 with a supply voltage. The electric machine 1 1 is an n-phase machine with n> 2. The electric drive system 10 therefore comprises n phase lines 1 1... 1 1 n, of which two phase lines 1 1 a and 1 1 n are shown by way of example in FIG are. To supply the electrical machine with electricity is a

Ring line 1 is provided in which a number m energy storage modules 2a ... 2m in series of which in Fig. 1 by way of example three energy storage modules 2a, 2b, 2m are shown. The number of energy storage modules 2a ... 2m is arbitrary. The energy storage modules 2a... 2m are each connected via supply connections 3a... 3n to the n phase lines 11a... 11n. By way of example, the phase line 1a is connected to each of the energy storage modules 2a, 2b, 2m via a respective supply terminal 3a. In this case, the number of supply connections 3a... 3n depends on the number of phase lines 11a... 11n.

In Fig. 1 a, the structure of an energy storage module 2 is shown in greater detail. The energy storage modules 2a... 2m of FIG. 1 can be constructed like the energy storage module 2 shown in FIG. The energy storage module 2 comprises a first connection 4a and a second connection 4b. Furthermore, this includes

Energy storage module 2, an energy storage cell 6. The energy storage cell 6 may include at least one energy storage, such as a battery. It can be provided that in the energy storage cell 6 more

Energy storage in series or in parallel. The number and arrangement of the energy storage in the energy storage cell 6 can be based on the requirements of the drive system 10. The energy storage module 2 further comprises a switching device 5, which connects the first terminal 4a of the energy storage module 2 switchable with the energy storage cell 6. The switching device 5 can also be referred to as a ring switching device 5, since it interrupts in the open state the ring, which is formed by the ring line 1 via all energy storage modules 2. The energy storage module 2 further comprises a node 7, which between the second terminal 4b and the

Energy storage cell 6 is arranged. Connected to the node 7 is a coupling device 8, which connects the supply connections 3a... 3n of the energy storage module 2 to the node 7. The coupling device 8 can, for example

Switching devices comprise, which each of the phase lines 11 a ... 1 1 n via the supply terminals 3a ... 3n separately and independently connected switchable with the node 7 can.

Together with the coupling devices 8 form energy storage modules 2, which are connected in a ring line 1 according to the topology of FIG. 1 in series, an inverter, which supplied one of the energy storage cells 6 DC voltage via an active control of the coupling devices 8 in an AC voltage for can transform an electric machine. The granularity of the implementation of the digital drive signals for the coupling devices 8 of the energy storage modules 2 in an analog output AC voltage depends, inter alia, on the number of energy storage modules 2 used or the energy storage cells 6 used and the clock rate of the control of the coupling devices 8.

2 shows a schematic illustration of an embodiment of a drive system 20. The drive system 20 corresponds to the configuration of the drive system 10 shown in FIG. 1. The drive system 20 is used, for example, to generate three-phase current for a three-phase electrical machine 1 1 having three phase lines 11 a, 1 1 b, 1 1c, which can also be denoted by U, V and W. In this case, the drive system 20 comprises, by way of example, four energy storage modules 2 a, 2 b, 2 c, 2 d, which are connected in series in the ring line 1. Each of the energy storage modules 2a, 2b, 2c, 2d comprises a ring switching device 5a, 5b, 5c, 5d, an energy storage cell 6a, 6b, 6c, 6d and coupling devices for coupling the energy storage modules 2a, 2b, 2c, 2d with the respective phase lines 11 a , 11b, 1 1c.

The coupling devices each comprise three per energy storage module

Switching devices, which the ring line 1 in the respective

Power supply module with one of the three phase lines 1 1a, 1 1 b, 1 1c connect switchable. For example, the energy storage module 2a includes the switching devices 21a, 21b and 21c, wherein the switching device 21a switchably connects the phase line 11 a with the ring line 1 in the energy storage module 2a, the switching device 21 b the phase line 1 1 b switchable with the ring line 1 in the energy storage module 2a connects and the switching device 21 c, the phase line 1 1c switchable with the

Ring line 1 connects in the energy storage module 2a. Analog have the

Energy storage modules 2b, 2c, 2d respectively switching devices 22a, 22b, 22c, 23a, 23b, 23c and 24a, 24b and 24c. The ring switching devices 5a, 5b, 5c, 5d are used to interrupt the ring line 1 at a suitable location, so that in each case a chain of the power supply modules 2a, 2b, 2c, 2d arises. The switching devices of the coupling devices of the energy storage modules 2a, 2b, 2c, 2d can be controlled so that only one switching device is closed per phase line 11a, 11b, 11c. This results in each of the phase lines 1 1a, 1 1 b, 1 1c, a supply voltage from the respective closed switching device of the coupling devices and the point of interruption the ring line 1 through the respective ring switching device 5a, 5b, 5c, 5d is dependent. For example, is at the phase line 11 a with open ring switching device 5c and closed switching device 21 a to a supply voltage corresponding to the sum of the voltage provided by the energy storage cells 6a, 6b and 6c minus the voltage provided by the energy storage cells 6d voltage.

At the output voltage of the system 20, only the difference between the supply voltages of the individual phase lines 11a, 11b, 11c is relevant. Thus, with the system 20, a seven-stage setting of the output voltage as a difference between two phase line 11 a, 11 b, 11 c possible because the respectively open ring switching device 5a, 5b, 5c, 5d associated energy storage cell 6a, 6b, 6c and 6d can not be used for the output voltage difference. In general, it is possible to provide a (2m-1) -stepped output voltage when using m energy storage modules with energy storage cells of the same voltage.

By timely switching the switching devices of the coupling devices of the energy storage modules can approach the output voltage of a sine wave voltage. In this case, for example, intermediate values between the stages of the output voltage via corresponding back and forth between two

Switching adjustment of the switching devices can be realized, so that in the time average, an intermediate value of the output voltage is applied to the respective phase lines.

3 shows a schematic representation of a drive system 30, which differs from the drive system 20 shown in FIG. 2 only in that one of the energy supply modules, shown by way of example in FIG. 3, the energy supply module 2d is equipped with an additional coupling device. The additional

Coupling device connects a node between the ring switching device 5d and the energy storage cell 6d of the power supply module 2d with the

Phase lines 1 1a, 1 1 b, 1 1c. For example, switching devices 34a, 34b and 34c may be provided for this purpose, which each connect one of the phase lines 1a, 1b and 11c to the ring line 1 in the energy supply module 2d. It is of course also possible, the coupling device in another of the

To arrange power supply modules 2a, 2b or 2c. The switching devices 34a, 34b and 34c can be controlled similarly to the coupling devices in FIG. They offer the advantage that even the energy storage cell 6d in the formation of the difference between the supply voltages of two

Phase lines 11 a, 11 b, 1 1 c can be considered if the

Ring switching device 5d is the opened ring switching device. In this way, it is possible with the system 30 to achieve a (2m + 1) -step output voltage setting, here by way of example in nine stages, compared to only one (2m-1) -step with the system 20 in FIG.

In the systems 10, 20 and 30 of Figs. 1, 2 and 3, it is also generally possible, the ring switching devices and the coupling devices for charging the

To control energy storage cells from a three-phase network.

4 shows a schematic representation of a method 40 for operating an electric drive system of one of the FIGS. 1, 2 or 3. In a first step 41, one of the ring switching devices of the energy storage modules is opened, while the others are closed in each case, around the ring line 1 to interrupt a site and provide a chain of power modules. In a second step

42 then the coupling devices can be controlled to produce a desired output voltage for the electric machine to the phase lines. In a step 43 it can be checked whether the setting of the ring switching devices should be changed. This can be done depending on the setting of the drive system. For example, it can be provided that always the same ring switching device should be opened, for example in the system 30 of FIG. 3, when the maximum output voltage is needed, which can be achieved only when opening the ring switching device 5d. In this case, the method returns to the checking step

43 back to the beginning of the procedure.

However, it can also be provided, for example, to change the open ring switching device at periodic intervals. This can be beneficial to the

Current load of the energy storage cells on average for each of the

Keep energy storage cells the same. For this purpose, in a step 44, the check is made as to whether the system is still in the normal operating state, that is, whether all

Energy storage cells or energy storage modules work properly. If this is the case, the ring switching device to be opened in step 41 can be changed in a step 45. It may be possible to adhere to a fixed sequence of the ring switch device change in step 45 in order to maximize one to achieve a uniform load on the energy storage cells over a longer period of time. The period with which the ring switching device is changed, it can be much longer than a switching period of the coupling devices of

Energy storage modules for generating a sine wave of the output voltage.

In certain chain formations, that is, when opening certain

Ringschalteinrichtungen continues to give the possibility of the same

To obtain supply voltages to the phase lines with different setting of the coupling devices of the energy storage modules. This is possible if the output voltage to be set is less than the maximum possible

Output voltage is, the selection of the three closed

Switching means for the three phase lines in relation to each other remains the same, but is moved along the chain between the ends. By uniform choice of the various equivalent settings of the coupling devices in step 42, it is possible to balance the current load of the individual energy storage cells in the time average.

If, however, it should be determined in step 44 that one of the energy storage cells or one of the energy storage modules is not in a normal operating state, for example defective, disturbed or failed, it may be provided to select between two alternative emergency operating states in a step 46. The selection may depend, for example, on the desired output voltage.

It can be provided, for example, in step 47, the change of

Give up ring switching devices. In this case, the ring switching device which is located in the energy storage module with the defective energy storage cell can be permanently selected as the ring switching device to be opened in step 41. In this case, the defective energy storage cell is permanently at the negative pole, which means that it is never integrated into the supply chain. For the special case that the energy storage cell 6d fails in the system 30 in FIG. 3, care must still be taken that the additional switching devices 34a, 34b, 34c are correspondingly driven in order to reliably keep the energy storage cell 6d out of the energy supply chain. Alternatively, for example, in step 48, the defective ones may be provided

Energy storage cell in the chain to bridge. For this purpose, it may be provided that open the defective energy storage cell associated ring switching device in addition to the openable for the interruption of the ring line 1 ring switching device and to bridge the defective energy storage cell using two coupling devices via one of the phase lines. If, for example, the energy storage cell 5c is defective, the ring switching device 5c can additionally be opened. So that the circuit is closed again, a bridging of the energy storage cell 5c via one of the phase lines 1 1a, 1 1 b, 1 1c done. For example, the switching devices 24a and 23a can be permanently closed. In this case, the current flows from the (intact) energy storage cell 6d via the switching device 24a, the phase line 1a and the switching device 23a to the ring switching device 5b, whereby the opened ring switching device 5c and the defective energy storage cell 6c have been bridged. However, the phase line 1 1a can not be controlled in this case for a change in the output voltage, because except the

Switching devices 24a and 23a no more switching device to the phase line 1 1a may be closed more. The maximum output voltage is thus at a bridging a defective energy storage cell on the appropriate

Voltage of the energy storage cell lower. If several energy storage cells should be defective at the same time, bridging via coupling devices and phase lines can only take place if directly adjacent energy storage cells fail.

Claims

Claims 1. An inverter for supplying an n-phase electric machine (1 1), where n> 2, having a plurality of energy storage modules (2) arranged in series in a loop (1), each of the plurality of energy storage modules (1). 2) comprises:

a first terminal (4a) and a second terminal (4b);

an energy storage cell (6), which at least one energy store (6a, 6b, 6c,

6d), and which is coupled between the first terminal (4a) and the second terminal (4b);

a ring switching device (5) which is designed to switchably connect the energy storage cell (6) to the first terminal (4a) of the energy storage module (2); and

a first coupling device (8) which is designed to connect a node (7) between the second connection (4b) and the energy storage cell (6) switchably to one of the phase lines (11a, 11b, 11c) of the electrical machine (1 1) to connect.

2. The inverter according to claim 1, wherein the first coupling devices (8) in each case for each phase line (11 a, 11 b, 11 c) of the electric machine (1 1) a controllable semiconductor switch (21 a, 21 b, 21 c, 22 a, 22 b, 22c, 23a, 23b, 23c, 24a, 24b, 24c).

3. Inverter according to one of claims 1 or 2, wherein the energy storage cell (6) comprises a plurality of series or parallel connected batteries (6a, 6b, 6c, 6d).

4. An inverter according to one of the preceding claims, wherein one of the plurality of energy storage modules (2d) further comprises:

a second coupling device (34a, 34b, 34c) which is adapted to a

Node between the ring switching device (5d) and the energy storage cell (6d) switchable with one of the phase lines (11 a, 11 b, 1 1 c) of the electrical machine (1 1) to connect.

5. System (10; 20; 30), with:

an inverter according to one of the preceding claims; and an n-phase electric machine (1 1), wherein n> 2, which via n phase lines (1 1a, 1 1 b, 1 1c) each with the first coupling means (8) of the plurality of

Energy storage modules (2) of the inverter is connected.

A method (40) for operating a system (10; 20; 30) according to claim 5, comprising the steps of:

Opening one of the ring switching devices (5) of the plurality of energy storage modules (2) while simultaneously closing the remaining ring switching devices (5); and

selectively driving the first coupling means (8) to connect the n

Phase lines (1 1a, 1 1 b, 1 1c) each having one of the plurality of

Energy storage modules (2).

The method (40) of claim 6, wherein in the step of opening one of

Ring switching devices (5) the open ring switching device (5) is periodically interchanged between all ring switching devices (5) of the plurality of energy storage modules (2).

The method (40) of claim 6, further comprising the steps of:

Detecting a failure of an energy storage cell (6) of one of the plurality of

Energy storage modules (2); and

permanent opening of the ring switching device (5) of that energy storage module (2), in whose energy storage cell (6) a defect is detected.

The method (40) of claim 6, further comprising the steps of:

Detecting a failure of an energy storage cell (6) of one of the plurality of

Energy storage modules (2); and

permanent bridging of the defective energy storage cell (6) via one of

Phase lines (11 a, 1 1 b, 1 1c) by driving the first coupling device (8) of the energy storage module (2) with the defective energy storage cell (6) and the first coupling device (8) of the energy storage module (2) with the defective

Energy storage cell (6) adjacent energy storage module (2).