SE534910C2 - Electrical apparatus including drive system and electric machine with switchable stator winding - Google Patents

Description

534 910 2 of an imaginary electric vehicle fl early morning will probably be charged at night from ordinary A sockets, which still gives a relatively long mileage during a night of 10 hours, probably more than what the battery on board can receive. With a large number of electric vehicles, however, it is likely that many of these also need to be “fast-charging” during the day, e.g. with 22 kW as from a 400 V 3 phase 32 A socket. Since the charging time for these will still be comparatively long (typically 30 to 60 minutes), it is probably not reasonable with special charging sockets as it would require very many compared to today's petrol stations. Instead, it is required that the vehicle can be charged from a normal electrical outlet, e.g. everything from 230 V 10 A 1 phase to 400 V 32 A 3 phase. Such can be mounted at a very low cost in very many places, e.g. at car parks at residential areas, shopping centers, offices, industrial properties etc.

STATE OF THE ART In order for a vehicle to be able to use a standard electrical outlet, it is required that the vehicle itself carries the necessary charging equipment. With a capacity for charging up to 400 V 32 A 3-phase, this means that a fairly heavy (> 100 kg) and expensive (> 10,000 SEK) equipment is needed on board. Since an electric vehicle is expensive from the start, mainly due to the cost of the batteries, it is burdened by the need for chargers for additional costs.

An example of a construction consisting of a divisible motor winding is shown and described in JP10248172. Part of the motor winding can be connected to the mains when charging. The design presupposes single-phase connection and drive with so-called "common mode" current, ie the same current in all three phases of the motor. US5341075 shows and describes a combined engine operation and battery charging system. Two of the motor's three phase windings are used as inductors for single-phase charging of an electric vehicle battery. A prerequisite is that the battery voltage is higher than the maximum instantaneous value of the mains voltage. A significant disadvantage is that no galvanic insulation between the mains and the battery can be achieved. A similar solution is described in US5099186. However, two completely separate 534 910 3 motor windings are used. Another similar solution is shown and described in US4920475. In accordance with the prior art described above, galvanic isolation in connection with the charging of the batteries is not possible. Another disadvantage is that the power made available for charging is too low. Special charging equipment can be used, but then both weight and costs increase.

THE INVENTION IN SUMMARY One way to reduce these costs is to use equipment that is already on board in a new way. An electric vehicle has at least one so-called electric drive system, including a power electronic converter and a traction motor. The traction motor is an electric machine / electric motor with a number of windings.

Through an advanced section and switching of the windings and other components, they can under certain circumstances be used as chargers.

The electric motor is provided with at least one three-phase winding, comprising a plurality of windings, which are connected via a set of switches. By setting the switches in different positions, the windings can be connected in series and connected in parallel in different ways in each phase. Thus, the electrical properties of the electric motor can be fundamentally changed.

In accordance with the invention, the traction motor is used as a transponder, a part of the windings being used as a primary winding, driven by the mains, and a part as a secondary winding. where the power electronic motor drive acts as a rectifier. A prerequisite is that the windings during normal motor operation can absorb the voltage that is adapted to the battery, and that the windings that in a connection point are connected to a three-phase network at the frequency 50 Hz (in some countries 60 Hz) keep the mains voltage at the connection point.

During charging, the mains drives the traction machine (as a motor) through the mains-connected winding. At the same time, the motor drive system brakes the traction machine (as a generator). Some of the power is transmitted via the rotor, but some is also transmitted via the magnetic coupling between what can be called primary and secondary winding of the divided windings. 534 910 4 The solution entails two significant advantages over prior art.

First, charging from a conventional three-phase mains socket is allowed. Secondly, complete galvanic insulation is achieved between the mains and the battery circuit. By special connection, single-phase charging can also be achieved. In the description below, the following are assumed to be known: the mains voltage through Un, [Volt RMS, Fas-Fas], the mains frequency through fn and the maximum output voltage of the motor drive system through Um, [Volt RMS, Fas-Fas] (often determined by the battery voltage).

The stator winding can be connected in two different operating modes, either traction or charging. During drive, the stator winding is divided into a number (ngph) groups of three-phase windings (n3 ,,,, = 1, 2, 3, ...), each group consisting of npd parallel-connected and md series-connected sections in each phase winding. These three-phase windings can be connected in either a Y or D coupling to match the voltage of the motor drive system.

When charging, one of two alternatives can be used: l) One or more of the groups of three-phase windings, a total of ngphß, are separated to be connected to the mains. The remaining three-phase groups (njph-ngphj) are used by the motor drive system. ll) The windings in one or more of the groups of three-phase windings are switched to two electrically separate three-phase windings, one of which is connected to the three-phase mains and the other is connected to the motor drive system.

The part that is connected to the three-phase mains consists of npcg parallel-connected and nug series-connected winding sections. The winding can then be connected in either a Y or Delta connection. The number of series and parallel-connected winding sections is selected so that the voltage across these windings at a motor speed corresponding to the mains frequency (usually 50 Hz, in some countries 60 Hz) is quite close to the nominal mains voltage. This varies in different countries. In Europe, it is 400 V main voltage.

The part connected to the motor drive system consists of npcd parallel-connected and nm, series-connected winding sections. The clutch is selected so that 534 910 they form a three-phase system with as high a voltage as possible, however lower than the highest voltage that the motor drive system can emit.

Charging can in accordance with the invention after switching according to the previous description take place in the following manner. |) u) lll) V) VI) The traction engine is disengaged from the vehicle's transmission by placing the gearbox in neutral and opening any clutches.

The motor drive system detects voltage and phase sequence at the connection point in the mains from which it is intended to charge.

The motor drive system speeds up the traction motor to the speed and phase position corresponding to the mains frequency and the mains voltage phase position.

The motor drive system adjusts the voltage of the traction motor in the three-phase winding to be connected to the mains so that the voltage across the three-phase winding corresponds to the mains voltage.

The motor drive system then connects the three-phase winding to be connected to the mains during charging.

The motor drive system finally loads the mains by braking the traction motor by controlling its currents, whereby electrical power flows from the mains via the traction motor to the battery.

BRIEF DESCRIPTION OF THE DRAWINGS In order to describe in an easy-to-understand manner how the above and other advantages and objects of the invention are achieved, a more detailed description of the above-described invention is given with reference to particular embodiments thereof, which will be apparent from the following drawings.

It should be noted that the figures show only particular embodiments of the invention and should not be construed as limiting its scope. With this in mind, the invention will be described and explained in more detail and in detail with the aid of the accompanying figures, in which Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 6 Fig. 7 Fig. 8 Fig. 10 534 910 6 schematically shows a vehicle with a battery and drive system, which are connected via a switching device to an electrical network for charging the battery, schematically shows a drive system connected for propulsion of a vehicle by means of current from a battery, schematically shows it in Fig. 1 shown the drive system, but now connected for charging the battery, is a block diagram showing an electrical appliance in accordance with the invention connected to a battery, shows the electrical appliance in Fig. 4 connected in a first position intended for operation, shows the electrical apparatus in Fig. 4 connected in a second position intended for charging, schematically shows an embodiment in accordance with the invention with a stator winding Y-connected for driving, schematically shows an embodiment in accordance with according to the invention with a stator winding divided into two Y-coupled three-phase windings connected to the three-phase network and the drive system, respectively, each comprising a plurality of series and parallel-connected winding sections, schematically shows an embodiment in accordance with the invention with a stator winding divided into a D-coupled three-phase winding for connection to the three-phase network and a Y-coupled three-phase winding connected to the drive system, which three-phase windings each comprise a number of series and parallel connected winding sections and schematically show an embodiment according to the invention with two separate stator windings divided into a D-coupled three-phase winding. for connection to the three-phase network and a Y-connected three-phase winding connected to the drive system, which three-phase windings each comprise a number of series and parallel connected winding sections.

INVENTION 534 910 7 In the embodiment shown in Fig. 1, a vehicle 10 is provided with an electrical apparatus 12 in accordance with the invention. The electrical apparatus 12 includes a drive system 14 and an electric machine 16 for propelling the vehicle. A battery 18 is provided in the vehicle for driving the electrical appliance. The battery 18 can be charged by connecting to a three-phase network 20. In the embodiment shown in Fig. 1, the battery is connected to the three-phase network 20 via a so-called charging pole 22 constituting the connection point and the electrical device 12. The electrical device 12 also includes a switching device. 24 and at least one stator winding 26.

When driving the vehicle 10, the electrical device 12 is switched on and controlled so that it corresponds to that in Figs. 2 showed the circuit diagram. The stator winding 26 is D-connected with two pairs of series and parallel connected winding sections L1-L12 in three phases. The drive system 14 comprises a converter 28, which converts the DC voltage available from the battery 18 to an alternating voltage adapted to the electrical machine 16. The drive system 14 is controlled by a control unit 30, which is actuated by a driver of the vehicle with a control 32. The electric machine is used in this position as a traction motor.

When charging the battery 18 in the vehicle 10, the electrical apparatus 12 is connected and controlled so that it corresponds to the circuit diagram shown in Fig. 3. The stator winding 26 is divided by means of the switching device into a Y-coupled first part and a D-coupled second part. Both parts of the stator winding 26 are magnetically coupled to each other in that the Y-coupled first part functions as a primary winding and the D-coupled second part functions as a secondary winding.

The primary winding with the winding sections L1-L6 is connected to the three-phase network 20 and the secondary winding to the winding sections L7-L12 is connected to the battery via a rectifier 34 of the drive system 14. During charging, the three-phase network drives the electric machine as a motor through the mains-connected primary winding. The controlled drive system 14 brakes the traction motor as a generator. Part of the power is transmitted magnetically via a rotor and another part of the power is transmitted via the direct magnetic coupling between primary and secondary winding, which is indicated by the arrow C. Preferably, the winding sections are distributed so that primary winding and secondary winding has the same effect.

Fig. 4 alternatively shows an electrical apparatus 12 in accordance with the invention connected to an electrical network 20 and a battery 18. The drive system 14 with its control unit 30 adjusts the stator winding 26 via the switching device 24 in a suitable manner for driving and charging, respectively. the switching device 24 preferably comprises mechanical switches, but also different types of electronic switches and semiconductor switches can be used.

The electrical apparatus 12 shown in Fig. 4 is connected in the circuit diagram in Fig. 5 for driving. With the appropriate selection of connection points of the switching device 24, the stator winding 26 is Y-connected with four parallel-connected pairs of series-connected winding sections in each phase. The battery 18 operates via the drive system 14 and the converter 28 in a per se conventional manner. The three-phase network 20 is in this position not connected to the electrical apparatus. The stator winding can also be D-connected.

In the example in Fig. 6, instead, the electrical apparatus 12 is connected for charging. The same set of winding sections as in the embodiment according to Fig. 5 is after switching of the coupling device 24 divided into a Y-coupled primary winding and a Y-coupled secondary winding. The primary winding comprises four series-connected winding sections in each phase, as well as the secondary winding. One or both windings can also be D-connected.

Fig. 7 shows an example of connection of an electrical appliance in accordance with the invention with a three-phase system Y-connected for drive. In each phase, npd parallel-connected groups of new, series-connected winding sections are connected to the drive system 14. All winding sections are included in the stator winding 26. In Fig. 8, the electrical apparatus according to the invention is connected for charging. A Y-coupled primary winding with nmg groups of nm, series-connected winding sections is connected to the three-phase network 20. A Y-connected secondary winding with npcd groups of now, series-connected winding sections is 534 S10 9 connected to the drive system 14. All winding sections are included in the stator winding 26. Which of the windings, or both windings, can instead be D-connected. Charging from a single-phase system is also possible in accordance with the invention. In the case that the primary winding is Y-connected, the zero of the three-phase network can also be connected, which is indicated at A in Fig. 8, and two of the three phases in the primary winding can be connected, which are indicated at B and C, respectively, also in Fig. 8. In the event that the primary winding is instead D-connected, one of the three phases in the primary winding may be connected.

In Fig. 9, the electrical appliance is connected for charging in accordance with the invention. A D-coupled primary winding with npcg groups of nscg series-connected winding sections is connected to the three-phase network 20. A Y-connected secondary winding with npcd groups of nm, series-connected winding sections is connected to the drive system 14. All winding sections are included in the stator winding 26.

In the exemplary embodiment shown in Fig. 10, two three-phase systems are used. A first three-phase system is D-connected and constitutes a primary winding connected to the three-phase network 20. The primary winding comprises npcg groups of nscg series-connected winding sections. A separate second three-phase system is Y-connected and constitutes a secondary winding connected to the drive system 14. The secondary winding comprises npcd groups of nm, series-connected winding sections. In the description above, certain specific embodiments have been described. However, it should be obvious to a person skilled in the art that current modifications can easily be made within the scope of the concept of invention. Subsequent claims should therefore not be considered to be limited to what is shown in the description, but should be interpreted so that they include such equivalents that are obvious to the person skilled in the art.

Claims (12)

10 15 20 25 30 534 910 10 PATENT REQUIREMENTS An electrical apparatus (12), comprising a drive system (14) and an electric machine (16) for propelling a vehicle (10), the electric machine comprising at least one rotor and at least one stator winding (26) and via a connection point can be connected to a three-phase network (20), characterized in that the stator winding is switchable between at least a first position, in which it is electrically controlled by the drive system (14) when propelling the vehicle, and a second position, in which it is divided into at least two separately and magnetically directly, and indirectly via the rotor, coupled three-phase windings for converting an voltage level available in the three-phase network, that a divided first and a first set of windings consisting of three-phase winding at a rotor speed corresponding to the three-phase network has a voltage that a divided and three-phase winding consisting of a second set of windings is electrically adapted to the drive system system and that the windings in the first set and the windings in the second set are respectively connected to the same switching device. An electrical apparatus according to claim 1, comprising a converter (28) for converting direct current to alternating current. An electrical apparatus according to claim 1, comprising a rectifier (34) for rectifying the alternating current available from the three-phase network to direct current. An electrical apparatus according to claim 1, wherein the electrical machine comprises a stator winding, which stator winding is divisible into a first three-phase winding which can be connected separately to the three-phase network and a second three-phase winding connected to the drive system. 10 15 20 25 30 534 910 11 An electrical apparatus according to claim 1, wherein the electrical machine comprises at least two stator windings, at least one of which stator windings are divisible into a first three-phase winding separately connectable to the three-phase network and at least one second three-phase winding connected to remaining drive stator windings. . Electrical apparatus according to claim 4 or claim 5, wherein the winding divided for connection to the three-phase network is connected only with its zero and one of the three phase connections. Electrical apparatus according to any one of the preceding claims, wherein the electrical machine is a permanently magnetized synchronous machine. An electrical apparatus according to any one of the preceding claims, wherein the electrical machine is an asynchronous machine. An electrical apparatus according to any one of the preceding claims, wherein the electrical machine is an electrically magnetized synchronous machine. An electrical appliance according to any one of the preceding claims, wherein the electrical machine is a synchronous reluctance machine. An electrical apparatus according to any one of the preceding claims, wherein the electrical machine is a switched reluctance machine. A method of generating rectified charging current from an electric drive system (14), the drive system being connected to a stator winding included in an electric machine (16), characterized in that the stator winding is switched from a first position, in which it is connected as a motor for propelling a vehicle (10), to a second position, that the electric machine in the second position is disconnected from the vehicle, that the electric machine in the second position is connected at a connection point to a three-phase network, In that in the second position the stator winding in the second position is divided into at least two separate and magnetically coupled three-phase windings for conversion of an voltage level available in the in-phase network, the electrical machine is rotated up to speed and phase position corresponding to the network frequency and phase position of the three-phase network, the voltage across a divided first and three-phase winding consisting of a first set of windings, by controlling the currents through a duck three-phase winding is adjusted to a voltage corresponding to the voltage level of the three-phase network at the connection point, the first set of windings forms a primary winding and is connected to the three-phase network, the current through the second set of windings is controlled so that the electric machine is braked. whereby electrical power is transmitted from the three-phase network through the second set of windings acting as a secondary winding and a current emanating from the secondary winding is rectified.