Electric vehicle

Abstract

The invention relates to an electrically powered vehicle (13) with an electrical circuit (14) comprising an inverter (1) and an electric drive motor (2), wherein the inverter (1) is electrically connected to the drive motor (2) via a plurality of lines (3) in order to transmit an alternating voltage generated by the inverter (1) to the drive motor (2), wherein active power filtering is provided to increase the efficiency of the inverter (1) and / or the drive motor (2), wherein a power factor correction filter (5) is arranged as part of an on-board charger (8) for charging a high-voltage battery (9) of the vehicle (13) via a high-voltage on-board network (10), wherein a switching matrix (6) is arranged to selectively connect the power factor correction filter (5) to the lines (3) in a driving mode in order to implement the active power filtering, or to connect it to an AC charging station (7) in a charging mode.

Description

The invention relates to an electrically driven vehicle according to the preamble of claim 1.During the travel of a vehicle with an electric drive machine, losses in the form of transmission losses at the semiconductor components and in the form of switching losses arise in an inverter for controlling the drive machine. The switching losses should be reduced as much as possible.The switching losses are caused by the simultaneous presence of a voltage across the semiconductor and a current. The product of these two time-dependent variables and the integration over the duration of the switching process result in the energy loss per switching process. The switching loss power during travel consists of the sum of the power loss per switching process differentiated according to time. It can be reduced in different ways.Reduction of the clock frequency (of the switching processes per second): However, this increases the harmonic content of the AC voltage to the drive machine, as a result of which additional iron losses arise in the drive machine. In addition, the intermediate circuit capacitor is more stressed by the higher harmonic content and ages more quickly or has to be dimensioned larger. In addition, a reduction in the clock frequency results in an increase in the voltage ripple in the DC-high-voltage system, as a result of which other high-voltage components are stressed or disturbed in their function.Reduction of the DC voltage-high voltage to be switched: however, this results in additional complexity, for example the use of a three-level inverter instead of a two-level inverter or the use of a voltage converter which is connected upstream of the inverter.Shortening of the switching duration, whereby the loss energy can be made smaller by shortening the integration time: an increase in the values of dUlt or dl / dt ensures over-voltages on the semiconductor itself, which can destroy the semiconductor. In addition, the high dU / dt values damage the insulation of the stator windings in the drive machine.Circuits for reducing harmonics are known from the prior art, which make it possible to operate the inverter at the fundamental frequency clocking. Such filters are called integrated active filters (IAF) or active power filters (APF). The aim of these applications are solar inverters and PFC stages (power factor correction filters). They are suitable for reducing the switching losses and / or for reducing the capacitance of the intermediate circuit capacitor of the inverter.The function of the inverter is in the fundamental frequency timing, but without a phase shift between AC current and AC fundamental frequency voltage. The harmonic component is reduced by targeted feeding in of a compensation current. The compensation current is set in a DC / DC converter with storage choke and can assume both positive and negative values. Its time profile corresponds to a triangular current with three times the frequency of the AC fundamental frequency of the inverter. The power to be transmitted is adjusted via a downstream DC / DC converter. The power is therefore controlled via the voltage difference between the source and the drain. The selector assigns the current impressed in the choke to the correct AC phase. The integrated active filter (IAF) or active power filter (APF) thus also requires additional outlay on components, for example in the form of at least one inductor, six semiconductor switches as selector and two further fast-switching semiconductors for generating a triangular current in the coil. This additional outlay is comparable to the additional outlay of three-level inverters or additional DC / DC converters.JP 5713282 B2 describes providing a power conversion apparatus without electrolytic capacitors, which can reduce harmonic current flowing in a system power supply. The power conversion apparatus includes a three-phase inverter connected to a capacitor on a DC side and connected to a three-phase system on an AC side to convert current between the DC and AC sides, and a instantaneous reactive power compensator connected to the three-phase inverter on the AC side to compensate the instantaneous reactive power due to a harmonic current generated by the operation of the three-phase inverter to provide a sinusoidal system current for the three phases.T. Soeiro, T. Friedli and J. W. Kolar, "Three-phase high power factor mains interface receptors for Electric Vehicle battery charging systems," 2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC), Orlando, FL, USA, 2012, pp. 2603-2610, doi: 10.1109 / APEC.2012.6166190 describes the use of an active power filter in an electrically driven vehicle.The object of the invention is to specify a novel electrically driven vehicle.The object is achieved according to the invention by an electrically driven vehicle having the features of claim 1.Advantageous embodiments of the invention are the subject matter of the dependent claims.An electrically driven vehicle is proposed, having an electrical circuit comprising an inverter and an electrical drive machine, wherein the inverter is electrically connected to the drive machine via a plurality of lines in order to transmit an AC voltage generated by the inverter to the drive machine, wherein active power filtering is provided in order to increase an efficiency of the inverter and / or of the drive machine. The increase in efficiency can also be achieved, for example, by reducing switching losses of the inverter. According to the invention, a power factor correction filter is arranged as part of an on-board charger for charging a high-voltage battery of the vehicle via a high-voltage on-board power supply system, wherein a switching matrix is arranged to connect the power factor correction filter selectively to the lines in a driving mode in order to realize the active power filtering or to connect it to an AC voltage charging station in a charging mode.The inverter can be designed, for example, as a 2-level inverter or 3-level inverter, wherein the 3-level inverter can be designed, in particular, as a so-called T-type, NPC or ANPC.In one embodiment, the inverter includes a controller configured to operate the inverter in an operating mode at a fundamental frequency clocking.In one embodiment, the switching matrix has three changeover switches for switching over one phase each.In one embodiment, the power factor correction filter is designed as a bidirectional three-phase power factor correction filter.In one embodiment, the three-phase power factor correction filter is formed by three single-phase power factor correction filters.In one embodiment, the inverter is advantageously designed as a two-level inverter.In an embodiment, the inverter comprises three half bridges formed of semiconductor switches, wherein the controller is configured such that a duty cycle of the individual semiconductor switches is 0.5 and the three half bridges are phase shifted from each other by 120° in timing.In one embodiment, the controller is configured to effect power control of the inverter via control of phase offset between an alternating current and generation of a fundamental alternating voltage wave by the timing of the semiconductor switches.In one embodiment, the on-board charger further comprises a bulk capacitor and an insulated DC / DC converter for feeding into the high-voltage on-board power supply system, wherein the DC / DC converter is active only during the charging mode and inactive during the driving mode.In one embodiment, the electric drive machine is designed as a permanently excited synchronous machine, a separately excited synchronous machine or an asynchronous machine.By operating the inverter at a fundamental frequency timing and using the power factor correction filter (PFC) of the onboard charger as an active power filter (APF) or an integrated active filter (IAF), the efficiency or the efficiency of the electric drive during driving is increased.The fundamental frequency clocking in the inverter enables a considerable reduction in the switching losses of the inverter. Associated possible disadvantages (magnetization losses in the electric machine, impermissible voltage ripple, faster aging of the intermediate circuit capacitor) are compensated for by the APF filter function. This APF filter function is adopted by the power factor correction filter of the onboard charger, which is not normally in operation during running. To ensure the voltage freedom at an AC charging socket of the vehicle, switching elements, in particular a switching matrix, are used.The use of the power factor correction filter of the onboard charger, which filter is already contained in the vehicle, for the IAF / APF function reduces the hardware outlay.The inverter may be operated at operating points with weaker AC currents at the fundamental frequency timing. This may be important in the real driving behavior of the customer. This allows an increase in efficiency to be achieved (reduction in the clock frequency and thus reduction in the switching power loss). Additional iron losses in the drive machine can be avoided. It is also advantageous to use the power factor correction filter of the on-board charger, which filter is already present in the vehicle in any case, as an active power filter (APF). The only additional element required is the switching matrix.Exemplary embodiments of the invention are explained in more detail below with reference to drawings.The following are shown: FIG. 1 shows a schematic view of an electrical circuit having an inverter for driving an electric drive machine of a vehicle, and FIG. 2 is a schematic view of an electrically driven vehicle.Corresponding parts are provided with the same reference numerals in all figures.FIG. 1 is a schematic view of an electrical circuit 14 having an inverter 1, for example a two-level inverter, for controlling an electric drive machine 2 of a vehicle 13 shown in FIG. 2, for example a passenger car, a commercial vehicle or a bus.In an alternative embodiment of the invention which is not illustrated, the inverter can also be designed, for example, as a 3-level inverter, wherein the 3-level inverter can be designed, in particular, as a so-called T-type, NPC or ANPC.The electric drive machine 2 can be designed, for example, as a permanently excited synchronous machine, a separately excited synchronous machine or an asynchronous machine.The inverter 1 is electrically connected to the engine 2 via a plurality of lines 3 to transmit an AC voltage from the inverter 1 to the engine 2. A bidirectional three-phase power factor correction filter 5 (PFC) is connected to the lines 3 via further lines 4. The power factor correction filter 5 is depicted as three-phase by way of example. Instead, however, the three-phase power factor correction filter 5 may also be formed by three single-phase power factor correction filters 5, for example.Furthermore, a circuit 6 is arranged to connect the power factor correction filter 5 selectively in a driving mode via the further lines 4 to the lines 3 between the inverter 1 and the drive machine 2 or in a charging mode to an AC voltage charging station 7. The switching matrix 6 can have, for example, three changeover switches for switching over one phase each, which can preferably be switched together. The changeover switches can be designed as relays or as semiconductor switches.The inverter 1 is in the operating mode of a fundamental frequency clocking, i.e. its clock frequency is identical to a rotational frequency of the drive machine 2. the inverter 1 has a plurality of semiconductor switches S 1 to S 6, for example MOSFETs or IGBTs, which form three half bridges and are controlled by a controller 15. A duty cycle (duty cycle) of the individual semiconductor switches S 1 to S 6 is 0.5. The three half bridges are phase-shifted with respect to one another by 120° in terms of timing.The power control of the inverter 1 is effected by controlling the phase offset between an alternating current and the generation of an alternating voltage fundamental wave by the clocking of the semiconductor switches S 1 to S 6 (or in other words: by controlling a torque-forming current iq). This is different from the prior publications relating to integrative active filters (IAF) and / or active power filters (APF), where the power is regulated via a downstream DC / DC converter.The power factor correction filter 5 is part of an on-board charger 8 for charging a high-voltage battery 9 of the vehicle 13 via a high-voltage on-board power supply 10. The DC / DC converter 12 is active only during the charging mode and inactive during the driving mode.The power factor correction filter 5 adds a compensating current to the drive machine 2 during the driving operation to each current on the lines 3, as a result of which a sinusoidal current is achieved in the drive machine 2. Since no power is transmitted via the harmonics, the isolated DC / DC converter 12 in the onboard charger 8 may remain passive or deactivated. The bulk capacitor 11 serves as an energy storage for providing an AC compensation current through the power factor correction filter 5.The inverter 1 can be operated at operating points with weaker AC currents in the fundamental frequency clocking. This may be important in the real driving behavior of the customer. This allows an increase in efficiency to be achieved (reduction in the clock frequency and thus reduction in the switching power loss). Additional iron losses in the drive machine 2 can be avoided. It is also advantageous to use the power factor correction filter 5 of the onboard charger 8, which is already present in the vehicle 13 in any case, as an active power filter (APF). The only additional element required is the switching matrix 6.FIG. 2 is a schematic view of an electrically powered vehicle 13 in which the electrical circuit 14 of FIG. 1 may be disposed.List of reference characters1 Inverter 2 Drive machine 3 Lines 4 Further lines 5 Power factor correction filter 6 Changeover matrix 7 Alternating voltage charging station 8 On-board charger 9 High-voltage battery 10 High-voltage on-board power supply system 11 Bulk capacitor 12 DC / DC converter 13 Vehicle 14 Electrical circuit 15 Controller S 1 to S 6 Semiconductor switchesReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 5713282 B2

[0006] Cited Non-Patent LiteratureT. Soeiro, T. Friedli and J. W. Kolar, "Three-phase high power factor mains interface receptors for Electric Vehicle battery charging systems," 2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC), Orlando, FL, USA, 2012, pp. 2603-2610, doi: 10.1109 / APEC.2012.6166190

[0007]

Claims

Electrically driven vehicle (13) having an electrical circuit (14), comprising an inverter (1) and an electrical drive machine (2), wherein the inverter (1) is electrically connected to the drive machine (2) via a plurality of lines (3) in order to transmit an AC voltage generated by the inverter (1) to the drive machine (2), wherein active power filtering is provided in order to increase the efficiency of the inverter (1) and / or of the drive machine (2), characterized in that a power factor correction filter (5) is arranged as part of an on-board charger (8) for charging a high-voltage battery (9) of the vehicle (13) via a high-voltage on-board power supply system (10), wherein a switching matrix (6) is arranged in order to connect the power factor correction filter (5) selectively to the lines (3) in a driving mode in order to realize the active power filtering, or in a charging mode to an AC voltage charging station (7).The electrically driven vehicle (13) according to claim 1, characterized in that the inverter (1) comprises a controller (15) configured to operate the inverter (1) in an operating mode with a fundamental frequency clocking.Electrically driven vehicle (13) according to Claim 1 or 2, characterized in that the changeover matrix (6) has three changeover switches for changeover of in each case one phase.Electrically driven vehicle (13) according to one of the preceding claims, characterized in that the power factor correction filter (5) is designed as a bidirectional three-phase power factor correction filter (5).Electrically driven vehicle (13) according to claim 4, characterised in that the three-phase power factor correction filter (5) is formed by three single-phase power factor correction filters (5).Electrically driven vehicle (13) according to one of the preceding claims, characterized in that the inverter (1) is designed as a two-level inverter.Electrically driven vehicle (13) according to one of Claims 2 to 6, characterized in that the inverter (1) has three half bridges formed from semiconductor switches (S1 to S6), wherein the controller (15) is configured such that a duty cycle of the individual semiconductor switches (S1 to S6) is 0.5 and the three half bridges are phase-shifted with respect to one another by 120%0020̊ in terms of timing.Electrically driven vehicle (13) according to one of Claims 2 to 7, characterized in that the controller (15) brings about power regulation of the inverter (1) by regulating the phase offset between an alternating current and the generation of an alternating voltage fundamental wave by the clocking of the semiconductor switches (S1 to S6).Electrically driven vehicle (13) according to one of the preceding claims, characterized in that the on-board charger (8) further comprises a bulk capacitor (11) and an insulated DC / DC converter (12) for feeding into the high-voltage on-board power supply system (10), wherein the DC / DC converter (12) is active only during the charging mode and inactive during the driving mode.Electrically driven vehicle (13) according to one of the preceding claims, characterized in that the electric drive machine (2) is designed as a permanently excited synchronous machine, a separately excited synchronous machine or an asynchronous machine.

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