The present invention relates to a motor generator and a system for electricity production.

Motor generators (or "electricity generating units") can be of various types, however all comprise an endothermic motor as their primary source of mechan ical energy, and a system for converting the mechan ical energy produced by said motor into electricity.

Trad itional m otor generators are configured to provide a precise voltage/current value as output and, in particular, to convert most of the mechanical energy developed by the endothermic motor into a precise and sole voltage/current value.

I n greater detai l , depend ing on their method of transform ing the mechanical energy into electricity, traditional motor generators are divided into two main categories: those which use an electric machine consisting of a wound rotor and stator, and those which use permanent magnet alternators with relative electronic energy conversion units.

Traditional motor generators of the second type, i.e. with permanent m agnet alternators, are able to provide as output both AC voltage (for example, 1 1 5VAC, 230VAC, 400VAC . ) and DC voltage (for example 12VDC or 24VDC). However they are usually configured to provide a single voltage as output, corresponding substantia l ly to the rated m echan ica l power obtainable from the endothermic motor.

I n th is respect, in the current state, in appl ications where motor generators having an AC or DC voltage output are required at different times, both at ful l motor piston displacement, a num ber of motor generators are required equal to the number of different output values.

This represents a drawback, in particular in those cases where final installation is in difficultly accessible places, as a plurality of motor generators have to be transported.

Moreover, in applications in which motor generators are used for dom estic purposes (to i ntegrate or replace the external electric ma ins connection), different motor generator outputs are required at different periods of the day, with each output having a power close to the rated power of the endothermic motor of the required motor generator.

In addition, given that the various loads of domestic user items require mutually different feed voltages (for example, household electrical appliances with traditional electric motors or pumps require an AC voltage feed, while lighting systems or modern televisions require a DC voltage feed), the user must provided several motor generators, programm ing the motor generator output as DC during one part of the day and AC during a different part of the day.

Furthermore, in applications in which both single-phase and three- phase feed of equal power are required, in the current state two different motor generators are required, one for single-phase feed and one for three- phase feed. Finally, those motor generators with a three-phase voltage output are particularly heavy and hence difficult to transport, especially if in isolated places.

US 201 0/01 81 851 describes a motor generator consisting of a single integrated containment structure housing all the motor generator components. In particular, the motor generator is able to generate an output of different types of electrical voltage because of the presence of a specific control unit which is commanded by the main motor generator controller and acts on the alternator such as to select and set different connections depending on the requ ired output voltage. However, th is solution is rather com p l icated constructionally, from both the mechanical and electronic viewpoints, and consequently particularly costly. Moreover, the fact of consisting of a single integrated containing structure does not facilitate transport, nor its adaptability for use in different contexts, particularly because it requires the use of output connectors and filters specifically certified for those countries in which the motor generator is sold. Finally, the setting of the different connections is final, and in any event must be set up or be modified only by the constructor, with evident lim itations for the user if the characteristics of the generated electricity need to be modified due to changed utilization requirements.

An object of the invention is to provide an improved motor generator which is flexible and particularly usable in various applications.

Another object of the invention is to provide an im proved motor generator which is easy and comfortable to transport.

Another object of the invention is to provide a motor generator which is economically advantageous both for the producer and for the final user.

Another object of the invention is to provide a motor generator having an output power always close to the rated mechanical power obtainable from the endothermic motor. Another object of the invention is to provide a motor generator which enables the final user to be able to generate different types of output voltage without needing to purchase several complete motor generators.

Another object of the invention is to provide a motor generator of simple, quick and low-cost construction.

Another object of the invention is to provide an electricity production system able to provide either a three-phase or single-phase voltage as output.

These objects and others which wi ll be apparent from the ensuing description are attained, according to the invention, by a motor generator as indicated in claim 1 , and by an electricity production system , as indicated in claim 16.

The present invention is further clarified in the form of some preferred embodiments thereof with reference to the accompanying drawings, in which: Figure 1 shows schematically a motor generator according to the invention, Figure 2 shows schematically an example of a stator of the motor generator of Figure 1 ,

Figure 3 s h ows sch e m at i ca l l y a f i rst exam p l e of th e interconnection between the stator windings and the electronics,

Figure 4 shows schematically a second example of the interconnection between the stator windings and the electronics,

Figure 5 shows schematically a first embodiment of a combined system for electricity production according to the invention,

Figure 6 shows schematically an alternator of the system of Figure 5, Figure 7 shows schematically a second embodiment of a combined system for electricity production according to the invention, Figure 8 shows schematically an alternator of the system of Figure 7, Figure 9 shows a detail of the system of Figure 5 or 7 in the configuration arranged for supplying a sing le-phase voltage as the system output,

Figure 10 shows the pattern and tim ing of the voltage and synchronization systems for generating a three-phase voltage as the system output,

Figure 1 1 shows the pattern and tim ing of the voltage and synchronization systems for generating a single-phase voltage as the system output.

As can be seen from the figures, the motor generator 1 according to the invention com prises a first com ponent 2 and a second com ponent 1 0, wh ich are arranged to be engaged and coupled together during normal operation of the motor generator.

The first com ponent 2 com prises a first containment structure 1 00 housing internally a motor 4 and a permanent magnet multi-pole alternator 6, which is mechanically coupled to said motor.

By means of the end of its shaft 5, the motor 4 rotates the permanent magnet multi-pole alternator 6. An AC voltage/current is generated across the ends 31 , 32 of the windings 30 of the alternator 6 which, via a suitable cable is transm itted to the first i nterconnection m eans 8. Essentia l ly, the fi rst interconnection means 8 are electrically connected to the windings 30 of the alternator 6.

Advantageously, further auxiliary electrical signals 7 are also fed to the first interconnection means 8, relative for example to velocity control or to switch-off of the endotherm ic motor 4, or relative to the control of the motor generator itself.

The second component 1 0 comprises a second containment structure 1 02, internally housing an electronic conversion system 14 provided with at least one output connector 16.

The second com ponent 1 0 also com prises second interconnection means 12 mechanically couplable and electrically connectable to the first interconnection means 8 of the first component 2. In particular, the second interconnection means 12 are electrically connected by a suitable cable to the input of the electronic conversion system 14.

Preferably, the first interconnection m eans 8 and/or the second interconnection means 12 are accessible from the outside and are defined at the outer surface of the respective containment structure 100 and 102.

For example, the electronic conversion system 1 4 com prises at its input a rectifier bridge able to transform into DC voltage the three-phase voltage provided by the alternator 6 and DC-DC or DC-AC converter stages at the output.

The electricity (in the form of AC voltage/current) generated by the alternator 6 is transmitted by the first interconnection means 8 to the second interconnection m eans 1 2 and , i n th is m an ner, reaches the electron ic conversion system 14, where it is suitably transformed into electricity of the desired characteristics, to be then made available to the user via the output connector 16.

In particu lar, the voltage generated by the alternator 6 (which is variable by depending on the periodicity of the rotations of the motor 4) can be converted by the electronic system 14 into a single-phase voltage of normal amplitude and frequency (for example 230 Vac 50Hz or 1 14 Vac 60Hz).

As represented in Figure 2, the stator 1 9 of the multi-pole permanent magnet alternator 6 com prises a plurality of windings 30 wound about the teeth 18 of the stator 1 9. Most of or all the windings 30 have their initial end 31 and/or their term inal end 32 connected electrically to the first electric contacts 20', 20" defined in said first interconnection means 8. In particular, the first electric contacts 20, 20" of said first interconnection means 8 are accessible from the outside of said first containment structure 100.

The second interconnection m eans 1 2 com prise second electric contacts 21 ', 21 ", intended to be electrically coupled and connected to the first electric contacts 20', 20" of said first interconnection means 8.

Suitably, the first electric contacts 20 of the first interconnection means 8, and the second electric contacts 21 of the interconnection means 1 2 , can be d ivided between one or more connectors, depending on the number of windings 30 of the alternator 6.

The configuration of the connections between said second electric contacts 21 ', 21 " and said first electric contacts 20', 20", and between the second electric contacts 21 ', 21 " themselves, enables the voltage fed to the i nput of the electron ic convers ion system 1 4 to be varied (and hence optimized), as is therefore the voltage available at its output.

In particu lar, as is apparent from the two ensu ing exam ples, the second component 1 0 presents a different configuration of the connections defined between the second electric contacts 21 ', 21 " of the second interconnection means 12, depending on the value of the required voltage at the output connector 16.

For example, if a low voltage is required at the output connector 16, to ach ieve a good conversion efficiency the first electric contacts 20' , 20" connected to the windings 30 of the alternator 6 should be connected such as to provide as input to the electronic conversion system 14 an input voltage, preferably three-phase, having a peak value substantially close to that of the required output voltage at the connector 16.

In particular, in this case the first electric contacts 20' , 20" of the windings 30 of the alternator 6 are com bined in such a m anner as to be connected in paral lel and, in greater detai l , all the in itial ends 31 of the windings 30 are carried to a first group 20' of electric contacts, while all the term inal ends 32 of the windings 30 are carried to a second group of electric contacts 20".

As shown in Figure 3, the second interconnection means 12 comprise:

- a first group of second electric contacts 21 ' which is complementary to the first group of contacts 20' of the first means 8 and is configured such as to short-circuit together all the initial ends 31 of the windings 30, and

- a second group of second electric contacts 21 " which is complementary to the second group of contacts 20" of the first means 8 and is configured such as to set in parallel all the corresponding phases of the stator 1 9 of the multi-pole permanent magnet alternator 6.

Hence in this manner, the phases P1 , P2 and P3 obtained at the second group of electric contacts 21 " provide, as input to the electronic conversion system 14, a voltage which is optimal for generating a low voltage as output.

Likewise, to obtain a high output voltage at the connector 16, the first electric contacts 20' and 20" of the first connection means 8 are connected to the windings 30 of the alternator 6 as in the preceding case. In particularly, all the initial ends 31 of the windings 30 are carried to the first group of electric contacts 20', while all the final ends 32 of the windings 30 are carried to the second group of electric contacts 20".

That which varies compared with the preceding case is however the arrangement of the electric contacts 21 of the second means 12 (see Figure 4). In particularly, the electric contacts 21 ' of the first group are configured such as to short-circuit together only the contacts S1 , S2 and S3 of the stator 19 and, together with the electric contacts 21 " of the second group, are configured to set in series all the corresponding phases of the stator 19 of the multi-pole permanent magnet alternator 6. Hence in this manner, the phases P1 , P2 and P3 obtained at the second group of electric contacts 21 " provide, as input to the electronic conversion system 14, a voltage which is optimal for generating a high voltage as output.

Essentially, to obtain at the output connector 16 a high voltage value or a low voltage value, or any other voltage value between these, or to obtain mutually independent voltage values, the same first component 2 is always used, whereas the second component 10 varies according to the required voltage at the connector 16. In greater detail, the specificity of the second component 10 derives from the configuration of the connections between the electric contacts 21 of the second interconnection means 12. Furtherm ore, independently of the characteristics of the second component 10, the power of the electricity generated at its output by the motor generator 1 , at the output connector 16, always corresponds substantially to the rated mechanical power of the motor 4 of the first component 2.

The auxiliary signals 7 relative to the functionality of the endotherm ic motor 4 or relative to the motor generator control are also fed to the electronic conversion system 14 via the connection between the electric contacts 20', 20" of the first interconnection means 8 and the electric contacts 21 ', 21 " of the second interconnection means 12. The electronic conversion system 14 of the second elements 10 again suitably comprises the same type of control as said auxiliary signals 7 such as to always obtain the same control setting for the motor generator 1 , independently of the second component 10 used by the final user.

Advantageously, the stator 1 9 of the permanent magnet alternator 6 can present further windings (not represented) in order to generate auxiliary voltages.

For exam ple, these further windings can be provided on the main windings 30 and can also involve several teeth together. Preferably, these auxiliary voltages are used to charge a possible battery provided in the first component 2 for the purpose of electrically starting the endotherm ic motor 4 when required.

The i n itia l and term i na l ends of the auxi l iary wi nd i ngs can be connected to the first electric contacts 20', 20" of the first interconnection means 8 to enable access thereto from the outside, or can be disconnected from first contacts to be used exclusively inside the first component 2. Advantageously, the electronic conversion system 1 4 of the second component 10 is provided with its own cooling elements 15 (for example fins) orientated such as to utilize the air flow fed by the fan of the first component 2, which is normally used to cool the endothermic motor 4. In particular, the fan of the first component 2 can be disposed and configured such as to draw in external air and feed it towards the second component 1 0 in such a manner as to make it pass through the cool ing elements 1 5 associated with the electronic conversion system 14.

From the aforegoing, the motor generator according to the invention is shown to be particularly advantageous in that, being divided into two elements, it is simpler to transport and, moreover, enables the final user to generate several types of output voltages without having to forcibly acquire several complete motor generators. For example, the final user can acquire a second component suitable for generating an AC voltage output, and another second component suitable for generating a DC voltage output, and can then connect them at different times to the same first com ponent containing the endothermic motor.

Moreover, in this manner, the final user can acqu ire a single first component provided with the most suitable motor for actual use and can then combine this (and hence acquire) the most suitable second components for the particular and multiple future needs of the user. In the same manner, if the final user wishes to change motor type, only a new first component has to be acquired, as the second component or components previously acquired are usab l e w ith d ifferent f i rst com po nents . M o reover, if one of th e two components is damaged, the final user need acquire or replace only the damaged component, while maintaining in use the sti ll properly operating component.

Furthermore, the motor generator according to the present invention is econom ically advantageous even for the producer, in that the producer can construct a large quantity of identical unique first components suitable for all world markets while at the same time constructing different types of second components, each of which is specific for a certain output voltage and hence for a specific geographical area of use.

The present invention also relates to an electricity production system able to generate both a single-phase voltage and a three-phase voltage.

In a first embodiment, shown in Figure 5, the system 50 comprises a combination of three motor generators 1 each of which comprises its own motor 103-1 , 103 ₂ 103 ₃ (hereinafter 103,), its own electrical alternator 25i , 25 ₂ 25 ₃ (hereinafter 25,) and its own electronic conversion unit 14-i , 14 ₂ 14 ₃ (hereinafter 14,).

Each electrical alternator 25, is coupled directly to the transmission shaft of the corresponding motor 103, and is preferably a permanent magnet multi-pole alternator of the type shown in Figure 2. Advantageously, the system 50 can com p rise th ree fi rst com pone nts 2, and three second components 10,; in greater detail, in this case each first component 2, comprises a first containment structure 100, for a motor 103, and an electrical alternator 25, and is provided with first interconnection means 8, which can be mechanically coupled with and electronically connected to the interconnection means 12, of the corresponding second component 10,, which comprises a second containment structure 102, for one of the three electronic conversion units 14-1 , 14 ₂ 14 ₃ . Essentially, each of the three motor generators 1 , comprises a first component 2, and a second component 10, of the previously described type, each presenting first interconnection means 8, and second interconnection means 12, of the previously described type.

Alternatively, each of the three m otor generators can com prise a single containment structure (without interconnection means) housing internally the motor 103, the electrical alternator 25, and the corresponding electronic conversion unit 14,. In this case, each electrical alternator 25, can be of the type shown in Figure 6. In greater detail, in this case, each alternator 25, comprises an external rotor 52 provided with a plurality of permanent magnets 53, and a stator 54 provided with a plurality of teeth 55 facing said magnets 53. On each tooth 55 of the stator 54 a winding is disposed, connected to the other windings such as to form a single three- phase power circuit 56. In particular, the three initial ends 57 of this winding 56 are short-circuited together, while the three terminal ends 58 are connected, via their own cable 59, to the corresponding electronic conversion

In greater detail, in the first embodiment of the system 50, the stator 54 of each of the three permanent magnet alternators 25i , 25 ₂ 25 ₃ is connected to the corresponding electronic conversion unit 14i , 14 ₂ 14 ₃ by its own cable 59,, 59 ₂ and 59 ₃ (see Figure 5).

Each electronic conversion unit 14, is configured to convert generic voltages at variable frequency, generated by the three-phase circuit 56 of the corresponding alternator 6, _, into a standard single-phase output voltage (for example 230 VAC 50Hz). In particular, each electronic conversion unit 14, comprises two output contacts, 60, and 61 ,, which represent respectively the line contact and the neutral contact for the output voltage.

In a second embodiment, shown in Figure 7, the system 50 comprises a motor generator 1 with a single motor 105, a corresponding electric alternator 80, and three electronic conversion units 14i , 14 ₂ 14 ₃ .

The electric alternator 80 is coupled directly to the transmission shaft of the motor 105 and is, preferably, a permanent magnet multi-pole alternator of the type shown in Figure 2.

Advantageously, the system 50 can comprise a single first component 2 and three second components 10,; in greater detail, said first component 2 comprises a first containment structure 100 for the motor 105 and alternator 80 and is provided with first interconnection means 8 which can be mechanically coupled with and electronically connected to the interconnection means 12, of the three second components 10,, each of which comprises a second containment structure 102, for one of the three electronic conversion units 14-1 , 14 ₂ 14 ₃ . Essentially, in this case, a single motor generator 1 is provided comprising a first component 2 and three second components 10 of the aforedescribed type, each of which presents respectively first interconnection means 8 and second interconnection means 12, of the aforedescribed type.

Alternatively, the motor generator can comprise a single containment structure (without interconnection means) internally housing the motor 105, the alternator 80 and the three electronic conversion units 14,. In this case the electric alternator 80 suitably presents a number of teeth suitable to divide it into three galvanically isolated three-phase windings, it being preferably of the type represented in Figure 8.

In greater detail, the alternator 80 comprises a rotor 71 , provided with a plurality of permanent magnets 72, and a stator 73 provided with a plurality of teeth 74 facing said magnets 72.

A winding 75 is disposed on each tooth 74 of the stator 73, the various windings being connected such as to form three three-phase circuits, respectively 75i , 75 ₂ and 75 ₃ (hereinafter 75,), which are similar but are galvanically isolated from each other. In particular, the three initial ends 76 of each circuit 75, are electrically connected together, while the three terminal ends 77 of each circuit 75, are connected via their own cable 78, to the corresponding electronic conversion unit 14,.

In greater detail, in the second embodiment of the system 50, the stator 73 of the single alternator 80 is connected to the three electronic conversion units 14i , 14 ₂ , 14 ₃ by thee cables 78-i _, 78 ₂ and 78 ₃ , each of which is connected to the three terminations 77 of the three circuits 75,.

In this embodiment, each of the electronic conversion units 14, is configured to convert the generic variable frequency voltages, produced by a single three-phase circuit 75, of the alternator 80, into a single-phase standard voltage (for exam ple 230 VAC 50 Hz), avai lable at the output across the contacts 60, and 61 ,, which represent respectively the line contact and neutral contact for the output voltage.

In both the embodiments, the neutral contacts 61 -i _, 61 ₂ and 61 ₃ at the output of the three electronic conversion units 14-i , 14 ₂ , 14 ₃ are connected together by a cable 86 to form the common neutral reference 90. Furthermore, in both the embodiments, the three electronic units 14-i , 14 ₂ , 14 ₃ present the same characteristics. Preferably, the three electronic units 14-1 , 14 ₂ , 14 ₃ are mutually identical.

The system 50 also comprises means for connecting together the three electronic conversion units 14i , 14 ₂ , 14 ₃ . In particular, these means can comprise a cable 87 insertable into a corresponding connector 85i , 85 ₂ , 85 ₃ provided in each of said units, or can comprise wireless transmission systems.

The system also suitably comprises means for controlling/setting the system operation, and in particular for defining and setting the type of voltage to be generated as output from the system 50, i.e. whether three-phase or single-phase type.

In addition, the system also comprises means for differentiating between the three electronic conversion units 14,, by assigning uniquely to one of them (defined hereinafter as the "dominant unit") the task of controlling the operation of the other two (defined hereinafter as "dependent unit 1 " and "dependent unit 2").

Preferably, the same cable 87 used to connect the three electronic conversion units 14, together can be used (for example by inserting suitable connectors) for setting the method of system operation, and for differentiating between the three electronic conversion units 14,.

Preferably, the three electronic conversion units 14i , 14 ₂ , 14 ₃ are connected together and communicate with each other directly, however, according to a variant, not represented herein, said units can be connected together and mutually synchronized by a central electronic supervising and control unit (not represented) which interfaces individually with each of said three electronic units 14-i , 14 ₂ , 14 ₃ .

The system 50, in both its embodiments, provides two modes of operation: one for generating a standard three-phase voltage output (see Figures 5 and 7 ) and one for generating a standard single-phase voltage output (see Figure 9).

In both operating modes, the cable 87 is suitable connected to the corresponding connectors 85, such that the electronic conversion unit 14i acquires the role of "dominant", the electronic conversion unit 14 ₂ that of "dependent 1 " and the electronic conversion unit 14 ₃ that of "dependent 2".

Once the user has selected by an external control (for example present on the control panel), the first operating mode (i.e. that suitable for generating a standard three-phase voltage output), the three motors 1 03, are started (in the case of the system 50 of the first embodiment) or the single motor 1 05 (in the case of the system 50 of the second embodiment). The "dominant" electronic conversion unit 14i then begins to generate the voltage V ₆ o-i across its output terminals 60i and 61 -i , and at the same time feeds via the cable 87 or via a wireless connection a synchronization signal 91 to the other electronic units 14 ₂ and 14 ₃ .

In the first operating mode (see Figure 1 0), the electronic conversion unit 14 ₂ is programmed to begin to generate the voltage V ₆ o-2 across its output terminals 60 ₂ and 61 ₂ , against the rising edge 92 of the synchronization signal 91 , while the electronic conversion unit 14 ₃ is programmed to begin to generate the voltage V ₆ o-3 across its output terminals 60 ₃ and 61 ₃ , against the falling edge 93 of the synchronization signal 91 . In this operating mode (see Figure 10), the synchronization signal 91 is generated such that the time 94 between passage of the voltage V ₆ o-i through zero (i.e. with respect to the reference 90) and the rising edge 92 is of 120 electrical degrees, and that the time 95 between the rising edge 92 and the falling edge 93 is also of 120 electrical degrees.

In this manner, the system 50 provides a standard three-phase voltage (in this case of 400 Vac 50Hz) across the terminals 60i , 60 ₂ and 60 ₃ of the three electronic units 14,.

I n the second operating mode ( i.e. that suitable for generating a single-phase output voltage) represented in Figure 9, the output terminals 60i , 60 ₂ and 60 ₃ of the three electronic conversion units 1 4i , 14 ₂ , 14 ₃ are connected together by a further cable 88.

Once the user has selected by an external control (for example present on the control panel), the second operating mode (i.e. that suitable for generating a single-phase voltage output), the three motors 103, are started (in the case of the system 50 of the first embodiment) or the single motor 1 05 (in the case of the system 50 of the second embodiment).

The "dominant" electronic conversion unit 1 4i then begins to generate the voltage V ₆ o-i across its output terminals 60i and 61 -i , and at the same time feeds a synchronization signal 97 to the other two electronic units 14 ₂ and 14 ₃ .via the cable 87 or via a wireless connection.

Again in this second operating mode (see Figure 1 1 ), the electronic conversion unit 14 ₂ is programmed to begin to generate the voltage V ₆ o-2 across its output terminals 60 ₂ and 61 ₂ , against the rising edge 92 of the synchronization signal 97, while the electronic conversion unit 14 ₃ is programmed to begin to generate the voltage V ₆ o-3 across its output terminals 60 ₃ and 61 ₃ , against the falling edge 93 of the synchronization signal 97.

However, in this second operating mode, the synchronization signal 97 is generated such that the time 98 between passage of the voltage V ₆ o-i through zero (i.e. with respect to the reference 90) and the rising edge 92 is of 180 electrical degrees, and that the time between the rising edge 92 and the falling edge 93 is of 180 electrical degrees.

The standard single-phase voltages V ₆ o-2 and V ₆ o-3 generated respectively by the electronic units 14 ₂ and14 ₃ are added to the voltage V ₆ o-i generated by the "dominant" electronic conversion unit 14i to obtain at the output terminal 96 a standard single-phase voltage of power equal to three times that deliverable by the single electronic conversion unit 14.

Preferably, the system 50 is portable and can be assembled on site, at the moment of use.

The system according to the invention is particularly advantageous in that:

- the power of the deliverable single-phase voltage is not one third of the three-phase, but is substantially equal thereto,

- it is flexible, economical, and is particularly suitable for situations in which the use of three-phase voltage is required only for certain time periods, while for the remaining periods a single-phase voltage of equal power is required,

- it is easier to transport and control given that it consists of the combination of th ree s ing le m otor generators rather than one heavy vol um i nous assembly.