Mechanical system and method for operating a mechanical system

Abstract

A mechanical system (1) comprising an electric machine (2) and a plurality of half bridges (3) for controlling the electric machine (2), wherein the electric machine (2) has a stator winding (4) including two winding sections (4.1, 4.2), each having a winding strand (14) and a winding connection (10), the winding connection (10) of one winding section (4.1) being electrically connected to a phase connection (8) of a first group (13.1) of half bridges (3), and the winding connection (10) of the other winding section (4.2) being electrically connected to a phase connection (8) of a second group (13.1) of half bridges (3). a mechanical system (1) in which the phase connections (8) of the first group (13.1) of half bridges (3) are electrically connected to the phase connections (8) of the second group (13.2) of the half bridges (3), and each of the phase connections (8) of the first group (13.1) of half bridges (3) is electrically connectable to one of the phase connections (8) of the second group (13.2) of half bridges (3) via bridge connections (11) in order to electrically connect two winding connections (10) of different winding sections (4.1, 4.2), each bridge connection (11) being provided with a switchable switching device (12); the half-bridge (3) of the mechanical system (1) is a control half-bridge, each winding strand (14) of one of the two winding sections (4.1, 4.2) forms a strand pair (15) with one of the winding strands (14) of the other winding section (4.1, 4.2), the winding strands (14) of each strand pair (15) being 180 degrees out of phase with each other; Each bridge connection (11) is characterized in that it is switchable to conduct both current directions by a respective switching device (12).

Description

[Technical Field]

[0001] The invention starts from a mechanical system according to the attributes of the independent claims. [Background technology]

[0002] A machine system comprising a generator as electric machine and a number of uncontrolled half-bridges of an uncontrolled full-wave rectifier circuit is already known from DE 32 27 602 A1, in which the electric machine has a stator with a stator winding, the half-bridges each having two input nodes for connection to a DC voltage source, two switching elements each connected in series between the input nodes and one phase connection between the switching elements, the stator winding comprising two multi-phase winding sections with the same number of phases, in particular two three-phase winding sections, each winding section having a number of winding strands corresponding to the number of phases and a number of winding connections corresponding to the number of phases, the winding of one winding section being a multi-phase winding section ... the stator winding comprising two multi-phase winding sections with the same number of phases, the stator winding comprising two multi-phase winding sections with the same number of phases, the stator winding comprising two multi-phase winding sections with the same number of phases, the stator winding The line connection is electrically connected to the phase connection of a first group of half bridges, and the winding connection of the other winding section is electrically connected to the phase connection of a second group of half bridges, each group of half bridges having a number of half bridges corresponding to the number of phases of the respective winding sections, and each phase connection of the first group of half bridges is electrically connectable to one of the phase connections of the second group of half bridges via a bridge connection to form a half-bridge pair in order to electrically connect two winding connections of different winding sections, and each bridge connection is provided with a thyristor as a switchable switching device for interrupting the electrical bridge connection, but each bridge connection can only be switched to conduct current in one direction.

[0003] In series operation below a certain engine speed, the two winding sections of the stator winding are connected in series with each other and are equivalent to a single winding with a correspondingly larger number of turns. In parallel operation above a certain engine speed, the two winding sections of the stator winding are connected in parallel with each other and are equivalent to a single winding with a correspondingly smaller number of turns. In both system operations, all switching devices in the bridge connection are always open or closed together. The uncontrolled half-bridge of the rectifier circuit contains only diodes. The phase current is determined by the phase voltage induced in the stator winding. The bridge connection creates a so-called "opposite" connection, which results in a 60° (=180° - 120°) phase shift between the phase strands of each bridge-connected strand pair. The two winding sections of the winding are said to be "out-of-phase" with each other, meaning that the phase cycle directions of the two winding sections are opposite. This can be understood as the winding strands of the winding section according to FIG. 3 of DE 32 27 601 A1 being arranged on the stator in opposite directions of rotation.

[0004] The mechanical system includes a phase system having a plurality of phase subsystems, each of which is formed by one of the half-bridge pairs, a bridge connection of each half-bridge pair, and two winding connections connectable by each half-bridge pair. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] DE 3227602 [Patent Document 2] DE 3227601 A1 Summary of the Invention [Effects of the Invention]

[0006] The machine system according to the invention, which has the distinctive features of the independent claims, has the advantage over the prior art that it reduces the time-averaged line and switching losses in the semiconductors of the half-bridge, which allows for an increase in the phase current of the half-bridge and / or a reduction in the thermal load. Furthermore, the series connection of the winding sections allows for the impedance of the electric machine to be adapted depending on the operating point. By reducing the current ripple, the losses of the electric machine can be reduced. Furthermore, the torque ripple of the electric machine can be reduced, which increases the efficiency of the electric machine.

[0007] This is due to the present invention. According to a first aspect of the invention, the half-bridge of the mechanical system is a controlled half-bridge for supplying a phase current or a phase voltage to a stator winding, According to a second feature of the invention, each winding strand of one of the two winding sections forms a wire pair with one of the winding strands of the other winding section, the winding strands of each wire pair being 180 degrees out of phase with each other; According to a third aspect of the invention, each bridge connection is switchable by a respective switching device to conduct both current directions. This is achieved by:

[0008] In accordance with a second aspect of the invention, the winding strands of each strand pair produce magnetic flux when energized in the same sense in the stator, and their contributions to the fundamental are 180 degrees phase shifted from one another.

[0009] According to a third aspect of the present invention, the bridge connection can be electrically interrupted by opening the switching device, or can be made conductive by closing the switching device.

[0010] Advantageous refinements and improvements of the mechanical systems described in the independent claims are possible by the measures recited in the dependent claims.

[0011] According to an advantageous embodiment, the switching elements of each half-bridge are semiconductor switches, in particular IGBT or MOSFET transistors, each of which is in particular assigned a freewheeling diode as a separate component connected in parallel or which essentially includes the function of a freewheeling diode. In this way, the current in the half-bridge can be controlled by pulse width modulation in interaction with the inductance, in particular the inductance of the stator.

[0012] Each bridge-connected switching device can advantageously comprise at least one semiconductor switch, in particular an IGBT transistor, a MOSFET transistor or a thyristor. According to an advantageous embodiment, the switching device can be formed by an anti-series connection of two transistors, in particular an IGBT transistor or a MOSFET transistor, or by an anti-parallel connection of two thyristors, in particular a triac.

[0013] Because the switching devices do not need to switch as frequently as the switching elements of a half-bridge, cost-effective semiconductor components can be used for the switching devices, and relatively high switching losses can be tolerated. The switching devices of a bridge connection are preferably switched on when a large phase current flows, in order to minimize the load on the half-bridge. Therefore, the switching devices must have a high current capacity. Because the switching devices are only periodically switched in series-connected operation, the switching device's ability to switch quickly and efficiently is not required. Because series-connected operation is only used at low to medium rotational speeds, a lower switching frequency is required.

[0014] It is particularly advantageous if the winding strands of each strand pair have the same number of voltage-carrying turns (relative to the fundamental) and / or the same conductor cross-section and / or the same inductance, so that during operation the power is distributed evenly to the winding sections, which is then optimally utilized, thereby achieving high efficiency.

[0015] It is highly advantageous if the two groups of half-bridges, and in particular the bridge connection including the switching devices, are part of the inverter. In this way, a space-saving design can be achieved. The placement of components on the cooling body allows for a cost-effective, highly integrated design, and the small distances between components reduce the wiring effort. The drive circuit can be integrated into the control device.

[0016] The winding strands of each winding section can be advantageously connected in a star or delta configuration, with one pair of strands being connected to one another in the case of a star configuration, or two pairs of strands being connected to one another in the case of a delta configuration, via respective bridge connections.

[0017] The mechanical system includes a controller for driving the switching elements of the half-bridge and for driving the switching devices of the bridge connection.

[0018] The present invention further relates to a method for operating a mechanical system according to the present invention, the mechanical system comprising a phase system having a plurality of phase subsystems, each phase subsystem being formed by one of half-bridge pairs, a bridge connection of the respective half-bridge pair, and two winding connections connectable by the respective bridge connection, the mechanical system being operable in response to one or more system operating parameters of the electric machine, in particular the rotational speed, torque, and / or efficiency, and / or fault parameters of the mechanical system, in one of a plurality of operating states, in particular series-connected operation, isolated operation, emergency operation, or active short-circuit operation. The operating state can be selected, for example, by a look-up table. Series-connected operation is particularly suitable for low and medium rotational speeds, and isolated operation is suitable for high rotational speeds.

[0019] In series connection operation, it is contemplated that, depending on at least one subsystem operating parameter, each one of the phase subsystems operates in a passive subsystem operation, or each remaining phase subsystem operates in an active subsystem operation.

[0020] In passive subsystem operation, both half bridges of each phase subsystem are deactivated to form a passive phase subsystem, and the bridge connections of the passive phase subsystem are made conductive by corresponding switching positions to allow current to flow in both directions from one of the two winding connections to the other of the two winding connections via the bridge connections of the passive phase subsystem.

[0021] In active subsystem operation, both half bridges of each phase subsystem are driven to form an active phase subsystem to provide two control phase currents that are 180 degrees out of phase with each other, specifically, identical in magnitude and shape but different in sign, and further, in active subsystem operation, the bridge connections of the active phase subsystem are electrically interrupted by the respective switching devices at corresponding switching positions.

[0022] It is particularly advantageous if the half bridges of each active phase subsystem are driven in antiphase with respect to pulse-width modulation. Since the half bridges provide antiphase phase currents in their active state, the on-duty periods (duty cycles) set by the half bridges are also antiphase. Therefore, antiphase pulse-width modulation of the half bridges of a half-bridge pair (180° phase shift with respect to the PWM frequency between the centers of the on-duty periods) achieves approximately antiphase voltage profiles at the winding connections. This results in antiphase and canceling out the phase currents (displacement currents) flowing through the coupling capacitors of the windings, particularly for the rotor. The rotor voltage caused by capacitive coupling can be reduced, thus avoiding leakage currents that could damage the ball bearings. This also eliminates the need for rotor grounding or insulating ceramic bearings, which may be necessary.

[0023] The method according to the present invention achieves this by automatically generating an indirect control phase current in the series connection of two winding sections in response to the provision of a control phase current in the active phase subsystem, and the indirect control phase current flows in one of two directions through the bridge connection of the passive phase subsystem depending on its sign, thereby providing an appropriate phase current at each winding connection of each inactive phase subsystem.

[0024] Furthermore, in series connected operation, it is advantageous if all phase subsystems are sequentially changed to passive subsystem operation in a continuous sequence depending on subsystem operating parameters.

[0025] In this way, the reduction in thermal load on the half bridges is spread evenly over time.

[0026] It is highly advantageous if the subsystem operating parameter is the magnitude of the phase current in the phase subsystem, and the phase subsystem operates in a passive subsystem operation where the phase current exceeds a threshold value in terms of magnitude, in particular in the positive and negative current half-waves, respectively, in one-twelfth of an electrical period of the phase current around the peak value of the phase current, i.e., in the time interval from one-twelfth of an electrical period before the peak value to one-twelfth of an electrical period after the peak value.

[0027] In this way, the phase current is transferred from the bridge connection of one winding section to the other winding section during the time interval of maximum phase current, so that this phase current does not need to be controlled by the half-bridge of the passive phase subsystem. Since the power loss in the half-bridge is proportional to the current-time-area through which the current flows, setting the passive subsystem operation during this interval reduces the load on the half-bridge as much as possible.

[0028] Furthermore, it is advantageous if, in decoupled operation, the two winding sections are controlled separately by all bridge connections being interrupted by switching devices and by driving all half bridges of the first and second groups to provide controlled phase currents to all winding connections of the two winding sections.

[0029] In this way, in decoupling operation, the supply voltage can be optimally utilized to reduce the need for field weakening current and generate higher power at higher rotational speeds.

[0030] Furthermore, in emergency operation, it is advantageous if only one of the two winding sections is energized by driving only the half bridges of the first or second group to provide a controlled phase current to the winding connections of only one of the two winding sections, and in emergency operation, all bridge connections are interrupted by the switching devices.

[0031] In this way, for example, if one of the two winding sections has an insulation defect, the other of the two winding sections can still be energized, allowing limp-home operation.

[0032] In active short-circuit operation, it is also advantageous if all half-bridges of all phase subsystems are deactivated and all bridge connections are conductive in order to create an active short-circuit of the electric machine by means of the bridge connections.

[0033] In fault operation, all half-bridges are deactivated so that the two winding sections are not electrically connected to the voltage supply, which means that the winding sections are in an active short circuit with no potential (especially if the system is battery-powered), which puts one of the two winding sections in a safe state even in the event of an insulation fault.

[0034] It is also advantageous that in series connection operation and separation operation, the phase currents at the winding connections of the first winding section form a first three-phase current, and the phase currents at the winding connections of the second winding section form a second three-phase current, the two three-phase currents in the two winding sections being 180° out of phase with each other.

[0035] The two winding strands of each strand pair are accordingly configured 180 degrees out of phase with each other, and the phase currents of the individual active phase subsystems are 180 degrees out of phase with each other and are identical, particularly in magnitude and shape, but have different signs, to generate magnetic fluxes that are additively superimposed to generate torque in the stator. The first and second three-phase currents behave approximately like three-phase currents in the machine, with an amplitude corresponding to the sum of the amplitudes of the two three-phase currents.

[0036] The method according to the present invention reduces the power losses in the half bridge due to the inactive phases of the half bridge on a time average basis, resulting in a lower temperature of the half bridge with the same cooling. Therefore, it is possible to increase the phase current of the mechanical system with the same maximum semiconductor temperature. Because the phase current of the mechanical system can be increased, it is also possible to reduce the number of voltage-holding turns of the electric machine with the same maximum torque, which reduces the need for field-weakening current at higher rotational speeds. In other words, in decoupled operation, it is possible to move to an operating point at higher rotational speeds where a smaller proportion of the field-weakening current in the phase current is required, thereby allowing a larger proportion of the phase current to contribute to torque generation. Therefore, it is possible to significantly increase the power and efficiency of the electric machine at high rotational speeds.

[0037] In the case of the current-controlled half-bridge of the active phase subsystem, based on the conductive bridge connection in the passive phase subsystem, the winding section appears as a load with a larger inductance, a larger ohmic resistance, and a larger pole wheel voltage, which allows for a larger duty cycle to be set, thereby reducing the current ripple or distortion factor and torque ripple. Furthermore, the iron losses of the electric machine are also reduced. [Brief explanation of the drawings]

[0038] Exemplary embodiments of the invention are shown in simplified form in the drawings and are explained in more detail in the description below.

[0039] [Figure 1]2A to 2C, and FIG. 3 is an equivalent circuit diagram of a mechanical system according to the invention, comprising an electric machine according to a first exemplary embodiment, operating in series connection operation according to the invention, and at a time point Y according to FIGS. 2A to 2C; [Figure 1A] FIG. 2 shows one of the half-bridges according to FIG. 1; [Figure 2] Figure 2A is a diagram showing phase current profiles during active and passive subsystem operation of series-connected operation of phase subsystem 21V according to Figure 1. Figure 2B is a diagram showing phase current profiles during active and passive subsystem operation of series-connected operation of phase subsystem 21U according to Figure 1. Figure 2C is a diagram showing phase current profiles during active and passive subsystem operation of series-connected operation of phase subsystem 21W according to Figure 1. [Figure 3] 2 is an equivalent circuit diagram of the mechanical system according to the invention of FIG. 1 operating in decoupling operation according to the invention; [Figure 4] 4 shows the profile of the phase currents at the phase connections of the respective half-bridges of each phase subsystem of the mechanical system operating in decoupled operation according to FIG. 3. FIG. [Figure 5] 2 is an equivalent circuit diagram of the mechanical system according to the invention of FIG. 1 operating in emergency operation according to the invention; [Figure 6] 2 is an equivalent circuit diagram of the mechanical system according to the invention of FIG. 1 operating in active short-circuit operation according to the invention; [Figure 7] 4 is an equivalent circuit diagram of a mechanical system according to the invention, comprising an electric machine according to a second exemplary embodiment, and operating in series connection operation according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0040] FIG. 1 shows an equivalent circuit diagram of a mechanical system according to the invention, comprising an electric machine according to a first exemplary embodiment and operating in series connection operation according to the invention.

[0041] The mechanical system 1 according to the invention comprises an electric machine 2 and a number of half bridges 3 arranged in an electric circuit for controlling the electric machine 2. The electric machine 2 has a stator with a stator winding 4. According to Fig. 1A, each half bridge 3 of the mechanical system 1 according to the invention has two input nodes 5 for connection to a DC voltage source 6, such as a vehicle battery, two switching elements 7 respectively connected in series between the input nodes 5, and one phase connection 8 between each of the two switching elements 7.

[0042] The stator winding 4 includes two multi-phase, particularly three-phase, winding sections 4.1, 4.2 with the same number of phases, and each winding section 4.1, 4.2 has a corresponding number of winding strands 14 and a corresponding number of winding connections 10. Each winding strand 14 may have parallel sub-strands.

[0043] The winding connection 10 of one winding section 4.1 of the stator winding 4 is electrically connected to the phase connection 8 of a first group 13.1 of half bridges 3, and the winding connection 10 of the other winding section 4.2 is electrically connected to the phase connection 8 of a second group 13.2 of half bridges 3. The first group 13.1 of half bridges 3 includes a number of half bridges 3 corresponding to the number of phases of the winding section 4.1. Similarly, the second group 13.2 of half bridges 3 includes a number of half bridges 3 corresponding to the number of phases of the winding section 4.2. Each winding connection 10 of each winding section 4.1, 4.2 is electrically connected to another half bridge 3 of the respective group 13.1, 13.2 of half bridges 3.

[0044] Each phase connection 8 of the first group 13.1 of half bridges 3 is electrically connectable via a bridge connection 11 to one of the phase connections 8 of the second group 13.2 of half bridges 3, forming a half-bridge pair 23, in order to electrically (directly) connect two winding connections 10 of different winding sections 4.1, 4.2 of the stator winding 4. Each bridge connection 11 is provided with a switchable switching device 12 for interrupting the respective electrical bridge connection 11.

[0045] According to the present invention, the phase current I u , I v , I w Alternatively, it is intended that the half-bridges 3 of the machine system 1 are controlled half-bridges in order to supply the phase voltages to the stator windings 4 respectively.

[0046] Furthermore, according to the invention, it is contemplated that each winding strand 14 of one of the two winding sections 4.1, 4.2 forms a strand pair 15 with one of the winding strands 14 of the other winding section 4.1, 4.2, respectively, and that the winding strands 14 of each strand pair 15 are 180 degrees out of phase with each other.

[0047] Furthermore, according to the invention, it is provided that each bridge connection 11 is switchable by a respective switching device 12 so as to be conductive for both current directions, i.e. each bridge connection 11 is switchable to a state that is conductive for both current directions in the respective bridge connection 11. Depending on the respective switching position of the switching device 12, the respective bridge connection 11 is either conductive or electrically interrupted.

[0048] The switching elements 7 of each half-bridge 3 are electronic semiconductor switches, in particular IGBT or MOSFET transistors. Each semiconductor switch 7 can be assigned a separate freewheeling diode 9 connected in parallel. Alternatively, each semiconductor switch 7 can inherently include the functionality of a freewheeling diode.

[0049] The two groups 13.1, 13.2 of half-bridges 3 are part of an inverter 16. According to an exemplary embodiment, the bridge connection 11 (including the switching devices 12) is also part of the inverter 16, for example.

[0050] The winding strands 14 of each strand pair 15, when energized, generate magnetic flux in the machine, the fundamental components of which are designed to be 180 degrees out of phase with each other.

[0051] For example, the winding strands 14 of each wire pair 15 can be offset from one another by the angle of the stator pole. Alternatively, the winding strands 14 of each wire pair 15 can be identically operating strands, but with reversed start and end windings. Approximately the same voltage is induced in the winding strands 14 of each wire pair 15.

[0052] The switching devices 12 of each bridge connection 11 comprise, for example, at least one semiconductor switching element, in particular an IGBT transistor, a MOSFET transistor or a thyristor.

[0053] The winding strands 14 of each strand pair 15 may have the same number of voltage-carrying turns and / or the same conductor cross-sectional area and / or the same inductance.

[0054] The winding strands 14 of each winding section 4.1, 4.2 are connected in a star connection according to the first exemplary embodiment in accordance with Figures 1 to 6 and in a delta connection according to the second exemplary embodiment in accordance with Figure 7. Two specific winding connections 10 of different winding sections 4.1, 4.2 can be electrically connected via respective bridge connections 11, and the two specific winding connections 10 form a connection pair of the winding connections 10. The connection pair of the winding connections 10 can connect one pair of strands 15 together in the case of a star connection or two pairs of strands 15 in the case of a delta connection.

[0055] The mechanical system 1 further comprises a control device 17 for driving the switching elements 7 of the half-bridge 3 and for driving the switching devices 12 of the bridge connection 11 .

[0056] The mechanical system 1 includes a plurality of phase subsystems 21, e.g., 21 u ,twenty one v ,twenty one w The number of phase subsystems 21 corresponds to the number of phases of one of the winding sections 4.1, 4.2 of the stator winding 4.

[0057] Each phase subsystem 21 is formed by one of the half-bridge pairs 23, the bridge connection 11 of the respective half-bridge pair 23 and two winding connections 10 of two winding sections 4.1, 4.2 that can be (directly) connected by the respective bridge connections 11.

[0058] Depending on one or more system operating parameters, in particular the rotational speed, torque and / or efficiency of the electric machine 2, and / or fault parameters of the mechanical system 1, the mechanical system 1 may operate in one of a number of operating states, in particular series connection operation, isolation operation, emergency operation or active short circuit operation.

[0059] According to FIG. 1, the machine system 1 is in series connection operation, and the state of the machine system 1 in FIG. 1 is exemplarily shown for a time point Y according to FIGS. 2A to 2C.

[0060] In series connection operation, depending on at least one subsystem operating parameter, either one of the phase subsystems 21 is in passive subsystem operation "passive" or each remaining phase subsystem is in active subsystem operation "active."

[0061] In passive subsystem operation, the two half bridges 3 of each phase subsystem 21 are deactivated or switched inactive to form a passive phase subsystem 21, and the bridge connection 11 of the passive phase subsystem 21 is made conductive by the corresponding switching positions of the switching devices 12 to allow current to flow in both directions from one of the two winding connections 10 to the other of the two winding connections 10 via the bridge connection 11 of the passive phase subsystem 21.

[0062] In active subsystem operation, two control phase currents I are 180 degrees out of phase with each other, specifically, identical in magnitude and shape but different in sign. u , I v , Iw In order to provide this, the two half bridges 3 of each phase subsystem 21 are driven to form an active phase subsystem 21. The bridge connections 11 of the active phase subsystem 21 are electrically disconnected or disconnected by means of respective switching devices 12 in corresponding switching positions.

[0063] FIG. 2A shows the phase current profiles for the active and passive subsystems operating in series connection versus electrical phase angle for the phase subsystem 21V according to FIG.

[0064] especially, FIG. 2Aa shows the phase current I at the winding connection 10 of the phase subsystem 21V. v shows the profile of FIG. 2Ab shows the phase current I at the phase connection 8 of the two half-bridges 3 of the phase subsystem 21V. v shows the profile of Figure 2Ac shows the phase current I in the bridge connection 11 of the phase subsystem 21V. br shows the profile of FIG. 2Ad illustrates the change between the active subsystem operation "active" and the passive subsystem operation "passive" of phase subsystem 21V relative to the electrical phase angle.

[0065] FIG. 2B shows the phase current profiles for the active and passive subsystems operating in series connection versus electrical phase angle for the phase subsystem 21U according to FIG.

[0066] especially, FIG. 2Ba shows the phase current I at the winding connection 10 of the phase subsystem 21U. u shows the profile of FIG. 2Bb shows the phase current I at the phase connection 8 of the two half-bridges 3 of the phase subsystem 21U. u shows the profile of Figure 2Bc shows the phase current I in the bridge connection 11 of the phase subsystem 21U. brshows the profile of FIG. 2Bd illustrates the change between the active subsystem operation "active" and the passive subsystem operation "passive" of phase subsystem 21U relative to the electrical phase angle.

[0067] FIG. 2C shows the phase current profiles for the active and passive subsystems operating in series connection versus electrical phase angle for the phase subsystem 21W according to FIG.

[0068] especially, FIG. 2Ca shows the phase current I at the winding connection 10 of the phase subsystem 21W. w shows the profile of FIG. 2Cb shows the phase current I at the phase connection 8 of the two half-bridges 3 of the phase subsystem 21W. w shows the profile of Figure 2Cc shows the phase current I in the bridge connection 11 of the phase subsystem 21W. br shows the profile of FIG. 2Cd illustrates the change between the active subsystem operation "active" and the passive subsystem operation "passive" of phase subsystem 21W relative to the electrical phase angle.

[0069] From Figures 2Aa to 2Cd, it can be seen that in series connection operation, depending on at least one subsystem operating parameter, either one of the phase subsystems 21 operates in passive subsystem operation "passive" or each of the remaining phase subsystems operates in active subsystem operation "active."

[0070] Phase current I at phase connection 8 of half-bridge 3 u , I v , I w The profile of shows, according to Figures 2Ab, 2Bb and 2Cb, an abrupt change to the value 0 in the time interval dt.

[0071] In series connection and separation operation, the phase current I in the winding connection 10 of the first winding section 4.1 u , I v , I w form a first three-phase current at any time or in any state. Furthermore, the phase currents at the winding connection 10 of the second winding section 4.2 form a second three-phase current at any time, and the two three-phase currents in the two winding sections 4.1, 4.2 are 180° out of phase with each other. The phase current I of each of the two three-phase currents u , I v , I w are each 120 degrees out of phase with each other and may be, for example, a wave or sinusoidal waveform.

[0072] Control phase current I according to Figures 2Ab, 2Bb, and 2Cb in the active phase subsystem 21 u , I v , I w In response to the provision of the phase current I, the bridge connection 11 of the passive phase subsystem 21 is made conductive by the corresponding switching position of the switching device 12. br flows in one of both directions through the bridge connection 11 of the passive phase subsystem 21 depending on its sign, the remaining phase currents (not directly controlled by the half-bridge 3) are indirectly controlled in the series connection of the two winding sections 4.1, 4.2 by the phase current I u , I v , I w This occurs automatically as

[0073] At time Y according to FIGS. 2A to 2C of the mechanical system 1, for example, the phase subsystem 21 v ,twenty one w is in active subsystem operation, and phase subsystem 21 u is in passive subsystem operation. That is, the active phase subsystem 21 v ,twenty one w , half-bridge 3 is actively operated, resulting in a phase current I v , I w is provided. Passive Phase Subsystem 21 u, half-bridge 3 is inactive, resulting in a phase current I u is not provided. Two active phase subsystems 21 v ,twenty one w Control phase current I v , I w In response to the provision of the indirect control phase current I, the bridge connection 11 of the passive phase subsystem 21 is made conductive by the corresponding switching position of the switching device 12, so that the series connection of the two winding sections 4.1, 4.2 is respectively supplied with the indirect control phase current I u automatically occurs, and the phase current I br However, depending on the sign, the passive phase subsystem 21 u in one of two directions through the bridge connection 11 of the phase subsystem 21 u Therefore, the phase current I u has a waveform, for example a sinusoidal profile, despite the temporary deactivation of half-bridge 3 in passive subsystem operation.

[0074] The automatic generation of phase currents in each passive phase subsystem 21 occurs by applying Kirchhoff's first law (the sum of all phase currents equals zero) to each winding section 4.1, 4.2, respectively. Thus, one of the phase currents in the winding sections 4.1, 4.2 is determined by the remaining phase current, respectively, thereby eliminating the need to actively control one of the phase currents.

[0075] In series connection operation, all phase subsystems 21 are sequentially changed to passive subsystem operation in succession according to the subsystem operating parameters.

[0076] The subsystem operating parameters are, for example, the phase current I in the phase subsystem 21. u , I v , I w and the phase current I u , Iv , I w exceeds the threshold X in magnitude, in particular the phase current I before the peak value S u , I v , I w The phase current I u , I v , I w The phase subsystem 21 operates in passive subsystem operation during the time interval dt up to 1 / 12 of the electrical period after the peak value S of the phase signal.

[0077] Each phase current I u , I v , I w For each electrical period, the bridge connection 11 of the associated phase subsystem 21 is conductive for two time intervals dt, for which two switch-on and two switch-off processes are contemplated for each switching device 12, which can be achieved by appropriate control.

[0078] FIG. 3 shows an equivalent circuit diagram of the mechanical system according to the invention of FIG. 1, operated in decoupling mode according to the invention.

[0079] In isolation operation, the two winding sections 4.1, 4.2 are switched off by the switching devices 12, with all bridge connections 11 of the mechanical system being or being switched off, and all half-bridges 3 of the first and second groups 13.1, 13.2 being active, i.e., all winding connections 10 of the two winding sections 4.1, 4.2 are supplied with a controlled phase current I u , I v , I w are separately controlled by being driven to provide

[0080] FIG. 4 shows the profile of the phase currents of all phase subsystems of a mechanical system operating in decoupling operation according to FIG. 3 versus the electrical phase angle.

[0081] FIG. 5 shows an equivalent circuit diagram of the mechanical system according to the invention of FIG. 1 operating in emergency operation according to the invention.

[0082] In emergency operation, the control phase current I flows through the winding connection 10 of one of the two winding sections 4.1, 4.2. u , I v , I w In order to provide the phase current I, only one of the two winding sections 4.1, 4.2 is energized by driving only the half-bridges 3 of the first or second group 13.1, 13.2. In this case, all bridge connections 11 are interrupted by the corresponding switching positions using the switching devices 12. In emergency operation, the phase subsystem 21 is in a "semi-active" state, in which one half-bridge 3 of the half-bridge pair 23 supplies the controlled phase current I u , I v , I w while the other half-bridge 3 is passive.

[0083] FIG. 6 shows an equivalent circuit diagram of the mechanical system according to the invention of FIG. 1, operated in active short-circuit operation according to the invention.

[0084] In active short-circuit operation, all half-bridges 3 of all phase subsystems 21 are passive or deactivated, and all bridge connections 11 of the mechanical system 1 are made conductive by corresponding switching positions using switching devices 12 to generate an active short-circuit of the electric machine 2 by the bridge connections 11.

Claims

1. A mechanical system (1) comprising an electric machine (2) and a plurality of half-bridges (3) for controlling said electric machine (2), the electric machine (2) having a stator including a stator winding (4); The half bridges (3) each have two input nodes (5) for connection to a DC voltage source (6), two switching elements (7) connected in series between the input nodes (5), and one phase connection (8) between the switching elements (7), The stator winding (4) includes two multi-phase winding sections (4.1, 4.2) having the same number of phases, in particular two three-phase winding sections, each having a number of winding strands (14) corresponding to the number of phases and a number of winding connections (10) corresponding to the number of phases, the winding connections (10) of one of the winding sections (4.1) being electrically connected to the phase connections (8) of a first group (13.1) of half bridges (3), and the winding connections (10) of the other winding section (4.2) being electrically connected to the phase connections (8) of a second group (13.2) of half bridges (3), each group (13.1, 13.2) of half bridges (3) being connected to the phase connections (8) of the previous group (13.1, 13.2) of half bridges (3). the number of half bridges (3) corresponds to the number of phases of each of the winding sections (4.1, 4.2), and each of the phase connections (8) of a first group (13.1) of half bridges (3) is electrically connectable to one of the phase connections (8) of a second group (13.2) of half bridges (3) via a bridge connection (11) to form a half-bridge pair (23) in order to electrically connect two winding connections (10) of different winding sections (4.1, 4.2), and each of the bridge connections (11) is provided with a switchable switching device (12) for interrupting the electrical bridge connection (11). In a mechanical system (1), - the phase current (I ｕ , I ｖ , I ｗ ) or phase voltage, the half-bridge (3) of the mechanical system (1) is a controlled half-bridge, each winding strand (14) of one of the two winding sections (4.1, 4.2) forms a strand pair (15) with one of the winding strands (14) of the respective other winding section (4.1, 4.2), the winding strands (14) of each strand pair (15) being 180 degrees out of phase with each other; - each said bridge connection (11) is switchable to conduct in both current directions by said respective switching device (12); A mechanical system (1).

2. 2. The mechanical system according to claim 1, wherein the switching elements (7) of each half-bridge (3) are semiconductor switches, in particular IGBT or MOSFET transistors, and each semiconductor switch is assigned a freewheeling diode (9), in particular as a separate component connected in parallel, or the each semiconductor switch essentially includes the function of a freewheeling diode.

3. 3. A mechanical system according to claim 1 or 2, characterized in that the two groups (13.1, 13.2) of half-bridges (3), and in particular the bridge connection (11), are part of an inverter (16).

4. 4. The mechanical system according to claim 1, wherein the switching devices (12) of each bridge connection (11) comprise at least one semiconductor switch, in particular an IGBT transistor, a MOSFET transistor or a thyristor.

5. 5. The mechanical system according to claim 4, characterized in that the switching device (12) is formed by an anti-series connection of two transistors, in particular IGBT or MOSFET transistors, or by an anti-parallel connection of two thyristors, in particular a triac.

6. The mechanical system according to any one of claims 1 to 5, characterized in that the winding strands (14) of each strand pair (15) have the same number of voltage-holding turns and / or the same conductor cross-sectional area and / or the same inductance.

7. 7. The mechanical system according to claim 1, wherein the winding strands (14) of each of the winding sections (4.1, 4.2) are connected in a star or delta configuration, and wherein the respective bridge connections (11) can connect one pair of strands (15) together in the star configuration or two pairs of strands (15) together in the delta configuration.

8. 8. The mechanical system according to any one of claims 1 to 7, characterized in that a control device (17) is provided for driving the switching elements (7) of the half-bridge (3) and for driving the switching devices (12) of the bridge connection (11).

9. A method for operating a mechanical system (1) according to any one of claims 1 to 8, comprising: the mechanical system (1) comprises a phase system (20) having a plurality of phase subsystems (21), each of the phase subsystems (21) being formed by one of the half-bridge pairs (23), the bridge connection (11) of the respective half-bridge pair (23) and two winding connections (10) connectable by the respective bridge connection (11); the mechanical system (1) is operable in one of a plurality of operating states, in particular series connection operation, separation operation, emergency operation or active short-circuit operation, depending on one or more system operating parameters of the electric machine, in particular rotational speed, torque and / or efficiency, and / or fault parameters of the mechanical system; method.

10. In the series connection operation, one of the phase subsystems (21) operates in a passive subsystem operation (passive) or the remaining phase subsystems (21) operate in an active subsystem operation (active) in response to at least one subsystem operation parameter; - in the passive subsystem operation (passive), both half-bridges (3) of each phase subsystem (21) are deactivated to form a passive phase subsystem (21), and the bridge connections (11) of the passive phase subsystem (21) are conductive to allow current to flow in both directions from one of the two winding connections (10) to the respective other of the two winding connections (10) via the bridge connections (11) of the passive phase subsystem (21); In the active subsystem operation (active), two control phase currents (I ) are generated which are 180 degrees out of phase with each other, in particular identical in magnitude and shape, but different in sign. ｕ , I ｖ , I ｗ 10. The method of claim 9, wherein both half-bridges (3) of the respective phase subsystems (21) are driven to form an active phase subsystem (21) to provide a phase-shift-inverter (PWM) and the bridge connection (11) of the active phase subsystem (21) is electrically interrupted by the respective switching device (12).

11. The control phase current (I ｕ , I ｖ , I ｗ 11. The method according to claim 10, characterized in that, in response to the provision of a phase current control signal, an indirect control phase current is automatically generated in the series connection of the two winding portions (4.1, 4.2), and the indirect control phase current flows in one of the two directions through the bridge connection (11) of the passive phase subsystem (21) depending on its sign.

12. 12. The method according to claim 10 or 11, characterized in that in the series connection operation, all phase subsystems (21) are sequentially changed to the passive subsystem operation (passive) in a continuous sequence according to the subsystem operation parameters.

13. The subsystem operating parameters are the phase current (I ｕ , I ｖ , I ｗ ) and in the passive subsystem operation (passive), the phase current (I ｕ , I ｖ , I ｗ ) exceeds a threshold value (X) in terms of magnitude, in particular the phase current (I ｕ , I ｖ , I ｗ 13. The method according to claim 10, wherein the phase subsystem (21) operates in a time interval (dt) of 1 / 12 of the electrical period of the phase current around the peak value (S) of the phase current.

14. In the separation operation, a control phase current (I ｕ , I ｖ , I ｗ 10. The method according to claim 9, characterized in that the two winding portions (4.1, 4.2) are controlled separately by all bridge connections (11) being interrupted by the switching device (12) and by driving all half-bridges (3) of the first and second groups (3.1, 3.2) to provide a

15. In the emergency operation, a control phase current (I) is supplied to only the winding connection (10) of one of the two winding sections (4.1, 4.2). ｕ , I ｖ , I ｗ 10. The method according to claim 9, characterized in that only the half-bridges (3) of the first group (3.1) or the second group (3.2) are driven to provide a synchronous motor, so that only one of the two winding portions (4.1, 4.2) is energized, and in the emergency operation all bridge connections (11) are interrupted by the switching devices (12).

16. 10. The method according to claim 9, characterized in that in the active short-circuit operation, all half-bridges (3) of all phase subsystems (21) are deactivated and all bridge connections (11) are conductive in order to generate an active short-circuit of the electric machine (2) by the bridge connections (11).

17. During the series connection and separation operations, the phase current (I ｕ , I ｖ , I ｗ ) forms a first three-phase current, and the phase current (I ｕ , I ｖ , I ｗ 15. The method according to claim 10, wherein the first winding portion (4.1) forms a second three-phase current, and the two three-phase currents in the two winding portions (4.1, 4.2) are 180° out of phase with each other.

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