CA2124766A1

CA2124766A1 - Generating set

Info

Publication number: CA2124766A1
Application number: CA002124766A
Authority: CA
Inventors: Rene Jeanneret
Original assignee: Rene Jeanneret; Smh Management Services Ag
Current assignee: Swatch Group Management Services AG
Priority date: 1993-06-02
Filing date: 1994-05-31
Publication date: 1994-12-03
Also published as: JPH077998A; KR950002180A; EP0627811A1; FR2706095A1; CN1100243A; FR2706095B1; BR9402121A

Abstract

ABSTRACT

The generating set (1) is intended to supply a.c.
electrical energy to any consuming device and comprises a motor (3) coupled to a generator (5) producing an a.c.
voltage (V2), a first converter (6) producing a d.c.
voltage (V3) from the a.c. voltage (V2), a rechargeable electrical energy source (7) connected in parallel with the first converter (6), and a second converter (9) producing the output a.c. voltage (V1) of the generating set (1) from the d.c. voltage (V3).
This arrangement enables the effective value (U1) and the frequency (f1) of the output voltage (V1) to be kept constant regardless of the variations in the electrical power absorbed by the consuming device (2) supplied by the generating set (1).

Description

212~766 Case 907 A GENEE~ATING SET

The present invention relates to a generating set for supplying electrical energy at a first voltage that is an a.c. voltage having a set effective value and a set frequency, comprising a motor and a generator mechanically coupled to said motor to produce said electrical energy.
Such a generating set is obviously intended to supply electrical energy to a consuming device of any kind, which will simply hereinafter be termed llthe consuming device~
The output a.c. voltage of a known generating set, i.e.
the voltage it supplies to the consuming device, is directly made up of the voltage produced by the generator of the generating set.
The frequency of this output voltage must of course be as constant as possible regardless of the electrical power that is absorbed by the consuming device and that the generating set is required to supply.
The generator of a known generating set must therefore practically be a generator of the synchronous type, i.e. a generator that produces a voltage having a frequency proportional to the rotational speed of its rotor, and this rotational speed must be adjusted to a constant value such that this frequency will have the required value.
The rotor being mechanically coupled to the output shaft of the generating set's motor, it is obviously the rotational speed of the motor that has to be set at a constant value.
Thus, for instance, in a generating set having a bipolar generator whose rotor is directly coupled to the output shaft of the motor, the latter's rotational speed must be set at 3 000 rpm for the frequency of the generating set~s output voltage to be 50 Hz, regardless of how much electrical power is being absorbed by the consuming device.
' ' '. .. ..

` 212~71i6 AS iS well known, it is difficult accurately to set the rotational speed of a motor, in particular of an internal combustion engine such as that generally used in a generating set, during rapid variations of the mechanical power the motor is required to supply.
But, in a generating set, this mechanical power obviously depends on the electrical power that is absorbed by the consuming device, which power may vary in a very short time between a low or even zero value, and a high value or even the value of the maximum power that can be supplied by the generating set, or conversely.
~ uring such variations in the power absorbed by the consuming device, the rotational speed of a known generating set~s motor, and hence the frequency of the latter's output voltage, cannot therefore in practice be kept at the required constant value.
Variations in the frequency of a generating set's output voltage caused by variations in its motor~s speed can be attenuated, but not completely eliminated, by fitting an inertia flywheel on the shaft that connects the motor to the generator. But such a flywheel suffers from the drawback of being a heavy and bulky component.
The effective value of a generating set~s output voltage must also remain constant regardless of the electrical power that is absorbed by the consuming device.
To adjust this output voltage, use is generally made in a known generating set of a generator having a rotor fitted with so-called excitation windings and of a suitable circuit for modifying the current flowing in these excitation windings in dependence on the electrical power absorbed by the consuming device.
But upon a rapid change of this electrical power, the current flowing in the excitation windings varies only relatively slowly because, in particular, of the windings~
inductivity thereby causing the value of the voltage '...'. .~.~--` 212~766 ': ' ' ' supplied by the generator and hence of the output voltage of the generating set to vary.
The voltage supplied by the generator being moreover dependent on the rotational speed of the latter~s rotor, the variation of this voltage upon a change in the power absorbed by the consuming device is further worsened by the rotational speed's variation that occurs at that time as mentioned earlier.
In short, neither the value nor the frequency of the voltage supplied by a known generating set remain constant upon a change in the electrical power absorbed by the consuming device it supplies.
An object of the invention is therefore to provide a generating set that does not suffer from these drawbacks, -~
i.e. a generating set supplying an a.c. voltage having an w effective value and a frequency that are constant even with large and/or rapid variations of the electrical power absorbed by the consuming device it supplies.
This object is achieved by the claimed generating --~
set, that is intended to supply electrical energy at a first voltage that is an a.c. voltage having a set effective value and a set frequency, which comprises a motor and a generator mechanically coupled to said motor to produce said electrical energy, and which is characterized in that said generator is arranged to ` -produce said electrical energy at a second voltage, and in that it comprises a first converter electrically coupled to said generator to convert said second voltage into a third voltage that is a d.c. voltage having a constant value, a rechargeable source of electrical energy coupled in parallel with said first converter, and a second converter electrically coupled to said first converter and to said rechargeable source of electrical energy to produce said first voltage from said third voltage.
` ' '~

-` 212~766 other objects and advantages of the invention will become apparent from the following description with reference to the accompanying drawings in which :
Figure 1 illustrates diagrammatically and by way of non-limiting example an embodiment of the generating set according to the invention;
Figure 2 is a graph illustrating the mechanical power supplied by a motor in dependence on its speed of rotation;
Figure 3 is a table summarizing the operation of a circuit of the Figure 1 generating set;
Figure 4 illustrates the variation in relation to time of some signals measured in the Figure 1 generating set;
Figure 5 illustrates diagrammatically and by way of non-limiting example another embodiment of the generating set according to the invention;
Figures 6, 7 and 8 diagrammatically illustrate various ways of using the Figure 5 generating set;
Figure 9 illustrates diagrammatically and again by way of non-limiting example a further embodiment of the generating set according to the invention; and Figure 10 diagrammatically illustrates a rechargeable source of electrical energy that can be used in a generating set according to the invention.
The generating set according to the present invention and illustrated diagrammatically and by way of non-limiting example in Figure 1, generally referenced 1, is intended to produce electrical energy in the form of an a.c. voltage V1 having an effective value U1 and a frequency fl.
This electrical energy is intended to supply a consuming device, of any kind, that is represented in a very diagrammatic manner in Figure 1 with reference 2.

2124766 ~:

AS Will hereinafter be made clear, the a.c. voltage vl may, depending on the way the generating set 1 is constructed, be monophase or polyphase, e.g. three-phase.
The output terminals of the generating set 1, whose number will of course depend on the number of phases of voltage V1 and to which the terminals of consuming device 2 are connected, have not been shown separately and are collectively referenced S.
The generating set 1 comprises a motor 3 which, in the present example, is an petrol engine supplied by a carburettor that is not shown separately.
The position of the carburettor~s butterfly valve, which determines the flow and the composition of the fuel and air mixture being fed to engine 3 and hence the mechanical power being supplied by the latter at each of its speeds of rotation, is controlled by the value of an electric adjustment signal SM, in a manner hereinafter described, via a control circuit 4.
Control circuit 4 will not be described in detail as it can be constructed without difficulty in several different ways by a specialist who knows the various functions it is required to fulfill, which functions will be discussed later. A man of the art will readily realize that this control circuit 4 may be constructed to advantage by, for example, combining a microcomputer with suitable interface circuits and by programming this microcomputer to perform the reguired functions.
The generating set 1 further comprises an electrical energy generator 5 having, in conventional manner, a stator and a rotor that ar,e not shown separately. The rotor of generator 5 is directly connected to the output shaft of motor 3 by a mechanical linkage symbolized by a double line.
Generator 5 may be any one of the several types of well-known generators that produce electrical energy in monophase or polyphase a.c. voltage form in response to :

;~ 212~766 rotation of its rotor in relation to its stator, and will therefore not be described in greater detail.
The a.c. voltage produced by generator 5 is identified in Figure 1 by reference V2 and its effective value and frequency will respectively be referenced U2 and f2.
As will hereinafter become evident, the number of phases of voltage V2 may very well be different from that of voltage V1. Moreover, the effective value U2 and the frequency f2 of voltage V2 are variable and generally different from the effective value U1 and of the frequency fl of voltage V1. -The output terminals of generator 5 across which -voltage V2 appears and whose number obviously depends on the number of voltage v2~s phases have not been shown separately and are collectively referenced 5.1.
The generating set 1 also comprises a first converter circuit 6 having a number of first terminals equal to that of generator 5's terminals 5.1, each connected to one of the latter. The first terminals of converter 6 have not been shown separately either and are collectively referenced 6.1. ~ -Converter 6 further comprises second terminals, two in number, which have not been shown separately either and which are referenced 6.2.
It should be noted here that each of the various -electrical connections between the elements of the generating set 1 described above or that will be described ~-below is only symbolized in Figure 1 by a single line, even when it consists of several conductive wires as is obviously the case, for example, with the connection between generator 5 and converter 6.
For a better understanding of Figure 1, the connections which, as will be seen later, serve to transfer electrical energy have been symbolized by lines that are thicker than those which, as will also be seen `~` 2124766 :

later, serve to transmit control, adjustment or measurement signals.
The above-mentioned converter 6 is arranged to produce a d.c. voltage V3 across its terminals 6.2 in response to the a.c. voltage V2 it receives from generator 5 when the latter is driven by motor 3. Converter 6 is moreover so arranged that the value U3 of voltage V3 is constant regardless of the effective value of voltage V2 which, as will be seen later on, may vary considerably.
Additionally, converter 6 is arranged to regulate the electrical power it supplies to the components that are connected thereto and which will be described below in dependence on the value of an adjustment signal SC it receives from control circuit 4.
In the present example and for a reason that will be made clear further on, signal SC can assume two distinct values SCO and SC1 in circumstances that will also be described further on. Further, converter 6 is arranged to transmit no electrical power at its outputs 6.2 when signal SC has its value SCO and to transmit at its outputs 6.2 all of the electrical power it receives from generator 5 when signal SC has its value SC1.
A converter like converter 6 is a circuit that is well-known to specialists and will therefore not be described in detail.
Suffice it to say that such a converter generally comprises a voltage stabilizer that produces the desired d.c. voltage from a rectified and possibly filtered voltage supplied by a rectifier which receives the a.c.
voltage that is applied to the converter, even when the peak value of the rectified voltage is less than the value that the the d.c. voltage is required to have.
The generating set 1 further comprises a rechargeable source of electrical energy, referenced 7, i.e. a device able to store and to give back a certain amount of electrical energy under d.c. voltage. Source 7 has a pair -`` 2124766 of terminals, collectively referenced 7.1, which are connected each to one of the output terminals 6.2 of converter 6. Source 7 is moreover so arranged that the voltage V4 it produces across its terminals 7.1 when the latter are not connected to the terminals 6.2 of converter 6 will be at least substantially equal to the voltage V3 produced by the latter.
When the terminals 7.1 of source 7 and the terminals 6.2 of converter 6 are connected, voltages V3 and V4 are of course exactly equal.
- It will be assumed, in the present example, that source 7 consists of a battery of conventional accumulators such as lead or cadmium-nickel accumulators.
It should however be noted that source 7 may also be differently constructed as in the example described further on.
The generating set 1 moreover comprises a monitoring circuit 8 which is connected to source 7 and arranged to supply to control circuit 4 a measurement signal SQ
representative of the state of charge of source 7, i.e. of the amount of electrical energy available in the latter.
It will be assumed, in the present example, that signal SQ
has a maximal value SQ1 when source 7 is fully charged, and decreases at the same time as source 7 discharges.
Monitoring circuit 8 and its connections with source 7 will not be described in detail as they can be made in various ways well known to specialists. Suffice it to say here that such a monitoring circuit generally includes at least two circuits that supply measurement signals which are respectively representative of the voltage across the terminals of the source with which it is associated and of the charging or discharging current of the latter, and possibly circuits that supply measurement signals which are representative of other parameters of the source such as its temperature or its age, i.e. the time that has elapsed since it was first put into operation. Such a -.' ::'.' ,-- 212~766 g ~:
:. ., .

monitoring circuit also of course includes a computing circuit able to produce the signal that is representative of the state of the source to which it is connected in dependence on the various above-mentioned measurement signals.
The generating set 1 furthermore comprises a second converter circuit, referenced 9.
Converter 9 has a pair of input terminals collectively referenced 9.1, each connected to one of the terminals 6.2 of converter 6, and output terminals collectively referenced 9.2. The output terminals 9.2 are equal in number to the output terminals S of the generating set 1 and are each connected to one of the latter via a measurement circuit 10 that will be described further on.
Converter 9 serves to produce the output a.c. voltage vl of the generating set 1 from the d.c. voltage V3.
Converter 9 is thus a circuit of the same kind as the circuits commonly termed inverters which are well known and will therefore not be described here in detail.
Suffice it to say that an inverter is a circuit intended to produce an a.c. voltage, which may be monophase or multiphase, from a d.c. voltage, the peak value of the a.c. voltage being at most equal to the value of the d.c. voltage. To this end, an inverter includes in particular electronic elements such as transistors and thyristors whose number and connection depend on the monophase or polyphase nature of the a.c. voltage it is required to produce. Additionally, each of the electronic elements is controlled by a signal formed of periodic pulses having a width that varies along a sinusoidal function. The various sinusoidal functions defining these pulse widths all have the same amplitude and same frequency, which respectively define the effective value and the frequency of the a.c. voltage produced by the inverter, but which are phase-shifted in relation to one : ' ~.

:. , . :

another by an amount which also depends on the monophase or multiphase nature of this a.c. voltage.
In the generating set 1, the various signals for controlling the electronic elements of the inverter constituting converter 9 are permanently produced by control circuit 4 with the result that converter 9 also operates permanently. So as not unduly to clutter up the drawing, all of the connections through which these control signals are transmitted from control circuit 4 to converter 9 have only been represented by a single line.
Also, so as not unnecessarily to complicate the following -description, all of these control signals will simply be termed the control signal of converter 9 and will be referenced SD.
The generating set 1 additionally comprises two measurement circuits respectively referenced 10 and 11. --Measurement circuit 10 is disposed between the output terminals 9.2 of converter 9 and the output terminals S of the generating set 1, and is arranged to supply to control circuit 4 a measurement signal SP representative of the electrical power supplied by the generating set 1 to the consuming device 2, which is obviously identical to the electrical power absorbed by the latter. These two powers being identical, they will hereinafter both be referenced Pe. -- -Measurement circuit 10 is moreover so arranged that the voltage V1 supplied by converter 9 is applied without modification to the output terminals S of the generating set 1.
Measurement circuit 10 will not be described in detail as it can be constructed in various ways well known to specialists. Suffice it to say here that circuit 10 ~
may include a pair of circuits that supply measurement ~ ;
signals that are respectively representative of the effective value of the voltage V1 and of the current absorbed by the consuming device 2, as well as the ~ , :, : ,.

::
`- 2124766 computing circuit that is necessary for producing the signal SP is response to these measurement signals.
Measurement circuit 11 has input terminals that are connected in the present example to the terminals 5.1 of generator 5, and is arranged to supply to the control circuit 4 a measurement signal SR that is representative of the rotational speed of the rotor of generator 5 and hence of the rotational speed of motor 3. This rotational speed will hereinafter be referenced R.
Measurement circuit 11 will not be described in detail either as it can be constructed in various ways well known to specialists. It will be assumed, in the present example, that circuit 11 is arranged for signal SR
to depend on the frequency f2 of voltage V2, which frequency is of course proportional to the rotational speed R of the rotor of generator 5 and of motor 3.
It should be noted that, if needed, protection means against any overcurrent consisting for instance of fuses or cut-outs may be provided between the measurement circuit 10 and the output terminals S of the generating circuit 1. Such protection means have not been shown as they have no direct bearing on the present invention.
As will be described in detail further on, the electrical power Pe that is absorbed by the consuming device 2 when the generating set 1 is operating is generally supplied, in mechanical power form, by motor 3.
This mechanical power, hereinafter referenced Pm, is transformed into electrical power by the generator 5 and transmitted to the consuming device 2 via converters 6 and .:
Part of the mechanical power Pm supplied by motor 3 is dissipated by generator 5 upon being transformed into electrical power, and part of the latter is dissipated by converters 6 and 9 upon being transmitted to the consuming device 2.
::. .

., :

~; 2124766 The power dissipated in generator 5 and in converters 6 and 9 is however generally low compared to the electrical power Pe supplied by the generating set 1 and will be neglected in the following detailed description of the operation of the generating set 1, as the man of the art will realise without difficulty how to dimension the various components of the generating set 1 to take into account, if necessary, this dissipated power.
Figure 2 diagrammatically illustrates the well-known variation of the mechanical power Pm supplied by motor 3 as a function of its rotational speed R for three different values SM0, SM1 and SM2 of signal SM. In the present example, the value SM0 is that for which the butterfly-valve of the carburettor of motor 3 is fully closed or, in other words, is in the position generally known as the idling position. When signal SM has this value SM0, motor 3 thus hardly supplies any mechanical power, whatever may be its rotational speed. Similarly, the value SM1 is that for which the butterfly-valve of the carburettor of motor 3 is fully open, i.e. the position in which motor 3 supplies, at each of its rotational speeds, the maximum power it can supply at this speed. Finally, the value SM2 is that for which the butterfly-valve is in a position such that motor 3 supplies, at each of its rotational speeds, a defined fraction of the maximum power it can supply at this speed. It will be assumed that this defined fraction is equal to 80% in the present example.
For a reason which will be made clear later on, the above-mentioned measurement circuits 10 and 11 are so arranged that signals SP and SR are of the same kind. For example, each of these signals SP and SR may consist of an electrical voltage. Further, measurement circuits 10 and 11 are so arranged that, whatever may be the electrical power Pe that is absorbed by the consuming device 2, signals SP and SR will be equal when signal SM has the above-defined value SM2 and when motor 3 rotates at the `~ 2124766 ::

speed at which the mechanical power Pm it supplies is equal to this electrical power Pe.
Moreover, control circuit 4 is arranged for signal SM
to have value SM0 when signal SP is less than signal SR
and value SMl when signal SP is greater than signal SR, and, when signals SP and SR are equal, for signal SM to have value SM2 if signal SQ is equal to SQl and value SMl if signal SQ is less than SQl. Control circuit 4 is further arranged for signal SC to have its value SCl when signal SP is less than or equal to signal SR and its value SC0 when signal SP is greater than signal SR.
This operation of control circuit 4 is summarised in the Figure 3 table.
The operation of the generating set 1 will hereafter be described by starting at an arbitrary instant when the electrical power Pe absorbed by the consuming device 2 has a value Pel other than zero, less than the maximum electric power the generating set 1 can supply and having remained unchanged for a certain length of time. It will -~
also be assumed that, at that same instant, source 7 is fully charged and that signal SQ thus has its value SQl.
Under these conditions and as will be made clear later on, motor 3 rotates at speed Rl for which signal SR
has a value SRl equal to the value SPl of signal S
corresponding to the value Pel of electrical power Pe. -;
Signal SM thus has value SM2 and motor 3 supplies a power Pml equal, on the one hand, to this electrical power Pel and, on the other hand, to 80% of the maximum mechanical power Pml' it can supply at speed Rl.
The electrical power produced by generator 5 thus also has value Pel.
Moreover, signal SC has value SCl, with the result that converter 6 transmits to converter 9 all of the electrical power Pel it receives from generator 5. As converter 9 operates permanently, this electrical power Pel is therefore fully transmitted to user device 2.

': . . - .-,, : . ,..................... ~ . .

- : ~

-` 21247~fi 1~

It should be noted that, in this situation, the rotational speed R of motor 3 does not vary since the mechanical power Pml it produces is equal to that which is absorbed by generator 5 to produce the electrical power Pel, and since tne driving torque supplied by motor 3 is therefore equal to the braking torque created by generator 5.
The generating group 1 is thus in a stable situation which remains unchanged as long as the electrical power Pe that is absorbed by consuming device 2 remains constant.
Let us now consider a case where the electrical power Pe that is absorbed by consuming device 2, after having remained at value Pel for a certain length of time, abruptly diminishes and takes on a new value Pe2 other than zero.
Signal SP then takes on a new value SP2 less than the previous value SP1. Control circuit 4 thus gives to signal SM value SM0 at which the butterfly-valve of the carburettor of motor 3 is in its idling position, but continues to give to signal SC value SC1.
Motor 3 thus practically supplies no mechanical power but continues to rotate, at a decreasing speed, in response to its kinetic energy and to that of generator 5.
The latter thus continues to supply electrical power and since signal SC has value SC1 this electrical power is equal to the electrical power Pe2 that is absorbed by consuming device 2.
When the rotational speed R of motor 3 reaches value R2 at which value SR2 of signal SR is equal to the new value SP2 of signal SP, control circuit 4 gives back to signal SM value SM2.
The mechanical power Pm2 that motor 3 then supplies is thus again equal to 80% of its maximum mechanical power Pm2', and this mechanical power Pm2 is moreover equal to the electrical power Pe2 absorbed by consuming device 2 --~ 212~76fi since the value SR2 of signal SR is equal to the value SP2 of signal SP.
The generating set 1 is thus again in a stable position which only differs from the previous one as regards the values of the rotational speed R of motor 3, of the mechanical power Pm it supplies, and of the electrical power that is produced by generator 5 and which is transmitted to consuming device 2 via converters 6 and 9.
This situation remains unchanged as long as the value of this electrical power Pe remains constant and equal to Pe2.
Let us now consider a case where the electrical power Pe that is absorbed by consuming device 2 abruptly increases after having remained at value Pe2 for a certain length of time and takes a new value Pe3.
Signal SP then takes on a new value SP3 greater than the previous value SP2. The control circuit 4 thus gives to signal SM value SM1 at which the butterfly-valve of the carburettor of motor 3 is fully open.
Simultaneously, control circuit 4 gives to signal SC
its value SCO at which converter 6 no longer supplies any electrical power at all.
The electrical power supplied by generator 5 thus also becomes zero, as also the braking torque exerted by generator 5 on motor 3. All of the mechanical power supplied by motor 3 is thus now available to accelerate the latter and the rotor of generator 5.
As converter 6 no longer supplies electrical power, the electrical power Pe3 that is absorbed by consuming device 2 is now supplied by source 7. The latter thus discharges and the value of signal SQ decreases and drops to less than SQ1.
When the rotational speed R of motor 3 reaches value R3 at which the value SR3 of signal SR is equal to the value SP3 of signal SP, control circuit 4 gives back to ... . . . . . . .. . . .. . .
- - . -: : - . - :- ~ -... .''. ~ .. ~ ~-' : ~:, . .

212476fi signal SC its value SCl but still maintains signal SM at its maximum value SMl, as signal SQ is less than SQl.
Under these conditions, motor 3 supplies its maximum mechanical power Pm3' and generator 5 supplies an electrical power equal to this mechanical power Pm3' and greater than the value Pe3 of the electrical power Pe that is absorbed by consuming device 2.
The difference between power Pm3', which is also the power that is supplied by converter 6 since signal SC has its value SCl, and power Pe3 that is absorbed by consuming device 2 is absorbed by source 7. In this connection, it will be recalled that source 7 is constituted in the present example by a battery of conventional accumulators, which battery is partially discharged at this instant as stated earlier.
As the terminals 7.1 of source 7 are linked directly to the output terminals 6.2 of converter 6, source 7 recharges itself under d.c. voltage, i.e. voltage V3, and the current it absorbs during charging progressively decreases as the amount of electrical energy it contains increases.
This reduction in the current being absorbed by source 7 results in a decrease of the mechanical power having to be supplied by motor 3 and in a tendency for the rotational speed R of motor 3 and the value of signal SR
to increase.
But as soon as the value of signal SR exceeds the value SP3 of signal SP, control circuit 4 gives back to signal SM value SMO with the result that the mechanical power Pm supplied by motor 3 almost drops to zero and its rotational speed R decreases. When the value of signal SR
again reaches value SR3 egual to value SP3, control circuit 4 gives back value SMl to signal SM and motor 3 again starts supplying its maximum power Pm3~.
This process is repeated several times but since the current being absorbed by source 7 continues to decrease ---.i 21247~6 the ratio between the length of time during which motor 3 supplies its maximum power Pm3' and the length of time during which it only supplies almost zero power decreases, with the result that the average mechanical power supplied by motor 3 progressively diminishes.
When source 7 is fully recharged, signal SQ again reaches value SQl. Control circuit 4 then gives back to signal SM its value SN2 when motor 3 rotates at speed R3 and the value SR3 of signal SR hence equals the value SP3 of signal SP.
The mechanical power Pm3 that motor 3 then supplies is therefore again equal to 80% of its maximum mechanical power Pm3', and this mechanical power Pm3 moreover equals the electrical power Pe3 that is absorbed by consuming device 2 since the value SR3 of signal SR equals the value SP3 of signal SP.
This situation remains unchanged as long as the electrical power Pe that is absorbed by consuming device 2 does not vary and remains equal to Pe3.
A process similar to one of those just described obviously takes place whenever the electrical power Pe that is absorbed by consuming device 2 changes.
Figure 4 diagrammatically illustrates the evolution of the various processes described above in relation to time t.
In Figure 4, graph a) shows by means of a continuous line the electrical power Pe that is absorbed by consuming device 2 and the corresponding signal SP and also shows by means of a broken line the signal SR representative of the rotational speed R of motor 3. As explained earlier, signals SR and SP only differ for very short spaces of time that follow each change in the value of the electrical power Pe. That is why the broken line representing signal SR is only visible in those parts of graph a) corresponding to these time spaces.

.. . .. . . ..

-` 2124766 Graphs b) to e) of Figure 4 respectively represent the values of signal SM, of the mechanical power Pm supplied by motor 3, of signal SC and of signal SQ.
It should be noted that the variations of signal SR
and of the mechanical power Pm are generally not linear as has been shown for purposes of simplification.
The various elements of the generating set 1 and in particular control circuit 4 may of course be so arranged that the generating set 1 will operate in a manner other than that just described.
For instance, control circuit 4 may be so arranged that, when the electrical power Pe being absorbed by consuming device 2 increases, signal SC does not take its value SCO as in the above-described example but another fixed value such that converter 6 may carry on working, while at the same time limiting the electrical power it transmits from its inputs 6.1 to its outputs 6.2 to a value other than zero set by this value of signal SC.
This limited electrical power is obviously produced by generator 5, so that the mechanical power supplied by motor 3 no longer exclusively serves to accelerate the latter and the rotor of generator 5, a part of this mechanical power still being converted into electrical power by generator 5. During this acceleration, source 7 is only required to supply that part of the electrical power Pe being absorbed by consuming device 2 which is no longer supplied by converter 6.
It is thus possible in such a case to so dimension source 7 that the maximum amount of electrical energy it must be able to store may be less than in the example described with reference to Figure 4, thereby lowering its cost price.
In a case similar to that just described, the value given to signal SC by control circuit 4 may not be fixed but depend on the value of the increase in the electrical power Pe that is absorbed by consuming device 2.

.,' : : ' ,"' --- 212~766 : -19 ,.

It will thus be seen that each variation in the electrical power Pe absorbed by consuming device 2 causes a variation in the rotational speed R of motor 3 and of generator 5, and hence a variation in the effective value U2 and in the frequency f2 of the a.c. voltage V2 produced by the latter.
But it will also be seen that these variations in the effective value U2 and in the frequency f2 of voltage V2 have no effect on the effective value U1 and on the frequency fl of voltage V1 produced by the generating set 1 since the effective value Ul and the frequency fl only depend on the value U3 of the d.c. voltage V3, which is constant, and on the characteristics of the signal SD
controlling converter 9, which are determined by control circuit 4 independently of the effective value U2 and of the frequency f2 of volta~e V2.
~ his property of the generating set 1 is a great advantage of the latter in relation to the known generating sets.
It wili further be seen that the effective value U1 and the frequency fl of voltage V1 may be chosen quite freely since it suffices to so arrange control circuit 4 that signal SD for controlling converter 9 will have the required characteristics. It is even possible to so arrange control circuit 4 that these characteristics of signal SD, and hence this effective value U1 and/or this frequency fl, depend for example on the position of one or more switches provided on a control-board of the generating set 1. For instance, in a case where voltage V1 is a monophase voltage, it is possible to provide a two-position switch on the control-board and so arrange control circuit 4 that the effective value U1 and the frequency fl of voltage V1 will respectively be 220V and 50 Hz or llOV and 60 Hz depending on whether the switch is in one or other of its positions.

212~7~6 Moreover, the fact that the effective value U1 of the a.c. voltage V1 produced by the generating set 1 is independent of the effective value U2 of the a.c. voltage V2 produced by generator 5 avoids having to regulate voltage V2.
As a result the generating set 1 has the additional advantage of comprising no device that is similar to the device that serves to adjust, in known generating sets, the strength of the current flowing through the excitation windings of the generator's rotor.
Furthermore, the rotor of generator 5 of the generating set 1 need not necessarily include such excitation windings, as these can be replaced to advantage by permanent magnets. This constitutes another advantage of the generating set 1 in relation to known generating sets, for it is known that a generator having a rotor fitted with permanent magnets is generally less bulky and less expensive than a generator having a rotor fitted with excitation windings.
From the above it will be apparent that whatever the rotational speed R of motor 3, the latter supplies most of the time a mechanical power which is a defined fraction of its maximum power at that speed. It is therefore possible to so dimension motor 3 that its efficiency is maximal or at least nearly so and that the amount of polluting gas it discharges is minimal or at least nearly so, when it supplies this defined fraction of its maximal power.
Such optimization of the efficiency and of the amount of polluting gases being discharged is not possible with the motors of known generating sets, since these motors must rotate at constant rotational speed while supplying a variable mechanical power and since they therefore hardly ever operate under optimal conditions of efficiency and polluting gas discharge.
In the embodiment diagrammatically illustrated in Figure 5, the generating set according to the present .: ,.
' ~ ': ~:

--- 212~766 invention, referenced 21, comprises a motor which is similar to the motor 3 of the generating set 1 in Figure 1 and which bears the same reference. The motor 3 of the generating set 21 comprises like the motor 3 of the generating set 1, a carburettor having a butterfly-valve whose position depends on the value of a signal, also referenced SM, that is produced by a control circuit 24.
Control circuit 24 will not be described in detail as it can be made in various ways and without difficulty by a man of the art who knows the operation of the generating set 21.
In particular, and as with control circuit 4 of Figure 1, control circuit 24 may for example be constructed by combining a microcomputer with suitable interface circuits and by programming this microcomputer to perform the requisite functions.
Motor 3 is mechanically coupled to the rotor, not shown, of a generator 25 whose stator includes, in this example, three windings 25a, 25b and 25c that are electrically insulated from one another.
The generating set 21 further comprises three groups of elements each including a first converter 6, a source 7, a monitoring circuit 8, a second converter 9 and a measurement circuit 10, these numerical references being completed with a letter a, b or c depending on the group to which each element belongs.
Each of these elements 6a to lOa, 6b to lOb and 6c to lOc is similar to the element bearing the same numerical reference in Figure 1 and, in each group, the elements are connected to one another like the corresponding elements in Figure 1. These elements and their connections will therefore not again be described here.
Suffice it to say that the inputs of converters 6a to 6c are respectively connected to the windings 25a to 25c of generator 25. Similarly, converters 9a to 9c are so arranged in this example that the a.c. voltages Vla, Vlb and Vlc they produce are monophase. It should however be noted that this feature is not mandatory and that, in other embodiments, converters 9a, 9b and 9c may be so arranged that one or several of voltages Vla, Vlb and Vlc are polyphase, e.g. three-phase, voltages.
By analogy with the Figure 1 case, the control signals of converters 6a to 6c and 9a to 9c, produced by control circuit 24, and the signals supplied to control circuit 24 by monitoring circuits 8a to 8c and by measurement circuits lOa to lOc are also referenced SC, SD, SQ and SP respectively, these references being completed by the same letter a, b or c as the numerical reference of the element concerned.
The generating set 21 further comprises output terminals Sla, S2a, Slb, S2b, Slc and S2c, which are each connected to an output of one of converters 9a to 9c via measurement circuits lOa to lOc. The a.c. voltages produced by converters 9a to 9c, respectively referenced Vla, Vlb and vlc, thus appear across terminals Sla and S2a, Slb and S2b, and Slc and S2c, respectively.
The generating set 21 also comprises a circuit for measuring the rotational speed of generator 25 which is similar to circuit 11 in Figure 1 and similarly referenced as the latter circuit. Measurement circuit 11 is connected to the winding 25a of generator 25 and supplies to control circuit 24 a signal, also referenced SR, which is representative of the frequency of voltage V2a produced by winding 25a in response to the rotation of the rotor of generator 25, and hence representative of the rotational speed of motor 3.
The operation of the generating set 21 will not be described in detail as it is very similar to that of generating set 1.
It should however be noted that the generating set 21 may be used to supply electrical energy to one or more consuming devices, as will be explained later, and that in ~ 2124766 this latter case, the consuming devices may absorb electrical powers that differ from one another.
Control circuit 24 is therefore so arranged that motor 3, whatever may be the total electrical power being consumed by the consuming devicets), will rotate most of the time at the speed for which the mechanical power it supplies, which is equal to the above total electrical power, is equal to a defined fraction, e.g. 80%, of its maximum mechanical power at that speed.
To ensure such adjustment, control circuit 24 permanently sums up signals SPa, SPb and SPc, compares this sum with the value of signal SR and determines in dependence on this comparison the value of signals SM, SCa, SCb and SCc in a manner similar to that described earlier in connection with the operation of the generating set 1.
The effective values and the frequencies of the three voltages Vla, Vlb and Vlc are obviously independent of the electrical power absorbed by the consuming device(s) supplied by the generating set 21 for the same above-mentioned reasons as in the case of voltage Vl produced by the generating set 1.
These three voltages Vla, Vlb and Vlc may of course have identical effective values and frequencies in which case the three signals SDa, SDb and SDc may also be identical.
But, and this is an additional advantage of the generating set 21, control circuit 24 may be so arranged that the characteristics of signals SDa, SDb and SDc are such that the effective value and/or the frequency of one of the three voltages Vla, Vlb and Vlc differ from the effective value and/or the frequency of the other two voltages, or even that the effective values and/or the frequency of all three voltages differ from one another.
Control circuit 24 may also be so arranged that the characteristics of signals SDa, SDb and SDc, and hence the ~::

r~` 2 1 2 ~ 7 6 ~

effective value and/or the frequency of each of voltages Vla, Vlb and Vlc depend, separately for each of these signals, on the position of one or more switches disposed on a control-board of the generating set 21. Thus, for example, the control-board may be provided with three two-position switches and control circuit 24 may be so arranged that each one of voltages Vla, Vlb and Vlc has an effective value of 220V and a frequency of 50 Hz or an effective value of llOV and a frequency of 60 Hz according to the position of one of these switches. ~
These properties of the generating set 21 enable it ~ -to be used to supply three separate consuming devices.
Such a case is shown in Figure 6 wherein the generating set 21 is merely represented by its output terminals Sla, S2a, Slb, S2b, Slc and S2c and wherein the three consuming devices are referenced 31, 32 and 33.
As mentioned earlier, the generating set 21 can readily supply these three consuming devices 31, 32 and 33 even if the latter require supply voltages having ~ -effective values and/or frequencies different from one another.
The maximum electrical power that can be supplied by each of the groups of elements 6a to lOa, 6b to lOb and 6c to lOc of the generating set 21 is obviously limited by the constitution of these elements.
But the above-mentioned properties of the generating set 21 enable the latter to be used to supply a consuming device that operates under monophase voltage and which absorbs more electrical power than the maximum electrical power that can be supplied by each of these groups of elements. ~ -Figure 7 illustrates such a case wherein the generating set 21, which again is merely represented by its output terminals Sla, S2a, Slb, S2b, Slc and S2c, is used to supply a consuming device, referenced 34, that absorbs more electrical power than the maximum electrical :. ~,:

: . - . . . . .. ~ , , -~ 2124766 ~ ~

power that each group of elements 6a to 10a and 6b to 10b can supply, but less than or equal to the sum of these maximum powers.
In this case, the terminals Sla and Slb of the generating set 21 are connected, together, to one of the supply terminals of the consuming device 34, and the terminals S2a and S2b of the generating set 21 are connected, together, to the other supply terminal of the consuming device 34. The electrical power consumed by the latter is thus supplied by the two groups of elements 6a to 10a and 6b to 10b operating in parallel.
In such a case, the control circuit 24 of the generating set 21 must of course be so arranged that the signals SDa and SDb that are applied to the converters 9a and 9b are identical for the two voltages Vla and Vlb to have the same effective value and the same frequency and to be moreover in phase with one another.
Still in such a case, a second consuming device, referenced 35, may also be supplied by the generating set 21. Obviously, it would then be possible for the voltage Vlc produced by the latter across its terminals Slc and S2c, to which is connected the consuming device 35, to have an effective value and/or a frequency that are different from those of voltages Vla and Vlb.
In a similar manner, not shown, the generating set 21 may be used to supply a consuming device that operates under monophase voltage and which absorbs greater electrical power than that which is absorbed by consuming device 34 in the preceding example, but less than or equal to the sum of the maximum powers that can be supplied respectively by the groups of elements 6a to 10a, 6b to 10b and 6c to 10c.
In such a case, the terminals Sla, Slb and Slc of the generating set 21 arP connected, together, to one of the supply terminals of the consuming device, and the terminals S2a, S2b and S2c of the generating set 21 are .

... : : ~ ~ : ; ::

2124766 ::

connected, together, to the other terminal of the consuming device.
The electrical power absorbed by the latter is then supplied by the three groups of elements 6a to lOa, 6b to lOb and 6c to lOc operating in parallel.
Further, the control circuit 24 of generating set 21 must of course be arranged, in this case, for the signals SDa, SDb and SDc being applied to converters 9a, 9b and 9c to be identical for the three voltages Vla, vlb and Vlc to have the same effective value and the same frequency and to be in phase with one another.
The above-mentioned properties of the generating set 21 also enable the latter to be used to supply a consuming device operating under three-phase star voltage.
Such a case is illustrated in Figure 8 wherein the generating set 21 is again merely represented by its output terminals Sla, S2a, Slb, S2b, Slc and S2c and wherein the consuming device it supplies is referenced 36.
In this case, the neutral terminal N of consuming device 36 is connected to the three terminals Sla, Slb and Slc of the generating set 21, and the other three terminals R, S and T of consuming device 36 are respectively connected to the terminals S2a, S2b and S2c of the generating set 21. Moreover, the control circuit 2~ of the latter is arranged for the signals SDa, SDb and SDc being applied to converters 9a, 9b and 9c to be such that voltages Vla, Vlb and Vlc have the same effective value and the same frequency, but with each of these three voltages being out of phase by 120 in relation to the other two.
Still in this case, the electrical power that is absorbed by consuming device 36 is of course supplied by the three groups of elements 6a to lOa, 6b to lOb and 6c to lOc operating in parallel. The electrical power that is absorbed by consuming device 36 can therefore be at most equal to the sum of the maximum electrical powers - : ,. : : . . : - . : . : - . ~ -.

-` 212~76fi that the groups of elements 6a to lOa, 6b to lOb and 6c to lOc can respectively supply.
In the examples described above and illustrated by Figures 6 to 8, the various connections that are needed for the generating set 21 to supply one or more consuming devices in one or other of the described manners are made outside the generating set 21.
These connections may also be made inside the generating set 21.
Whenever the generating set 21 is intended to supply a definite number of consuming devices in a manner that is also definite, these connections may be fixed. But these connections may also be made with a multiposition switch disposed on the control-board of the generating set 21 and so connected to the output terminals of the latter and to the outputs of converters 9a, 9b and 9c that, in each of these positions, it establishes the necessary connections for one of the above-described uses of the generating set 21. The switch may also be connected to the control circuit 24 and the latter may be adapted to produce signals SDa, SDb and SDc with the requisite characteristics in each position of the switch.
In the embodiment diagrammatically represented in Figure 9, the generating set according to the invention, referenced 41, serves to supply a consuming device 2 and -comprises a motor 3, a control circuit 4, a generator 5 and measurement circuits 10 and 11. These various elements are similar to the elements bearing the same references in Figure 1 and will therefore not be described again. ;
The a.c. voltage V2 produced by generator 5 when its rotor is driven by motor 3 is applied to the input of a converter 6' having three output terminals 6'a, 6~b and 6'c.
Converter 6' is arranged to produce across its terminals 6'a and 6'b a d.c. voltage V3 similar to voltage - - , - :

,............ . .- - - , ... .:

--- 2~24766 28 ~
': ' .
~. .~ , .
v3 produced by the converter 6 of the generating set 1.
Converter 6' is moreover arranged to produce across its terminals 6~a and 6~c a second d.c. voltage, referenced V3', having the same value U3 as voltage v3 but of opposite sign, meaning that if terminal 6'b is for instance positive in relation to terminal 6~a, terminal 6~c is negative in relation to this same terminal 6'a.
Further, as with the converter 6 of the generating set 1, -~
converter 6' is arranged for the value U3 of voltages V3 and V3' to be substantially constant whatever may be the -effective value of voltage V2, and arranged to adjust the ~ -electrical power it supplies to the elements connected thereto in dependence on the value of an adjustment signal, also referenced SC.
Converter 6' will not be described in greater detail as it is also a circuit that is well known to specialists.
The generating set 41 also comprises a rechargeable source of electrical energy, referenced 7', having three output terminals 7'a, 7'b and 7'c respectively connected to terminals 6'a, 6'b and 6'c of converter 6. Source 7' is arranged to produce across its terminals 7~a and 7'b a first voltage having substantially the same value U3 and the same polarity as voltage V3, and to produce across this selfsame terminal 7'a and its terminal 7'c a second voltage having the same value U3 and the same polarity as voltage V3'.
Such a source 7' may for example be constituted by a battery of conventional accumulators having two extreme terminals respectively constituting terminals 7'b and 7'c and an intermediate terminal constituting terminal 7'a.
The generating set 41 further comprises a monitoring circuit, also referenced 8, which is connected to source 7' to supply a signal, also termed SQ, and that is representative of the amount of electrical energy contained in source 7'. This monitoring circuit is ., ~ .

:.

-- 2~24766 identical to the circuit 8 of the generating set 1 and will therefore not again be described.
The output terminals 6~a, 6'b and 6~c of converter 6~
are respectively connected to the inputs 9'a, 9'b and 9'c of a second converter 9' arranged to produce the output a.c. voltage of the generating set 31, also referenced V1, in response to the d.c. voltages V3 and v3~.
Like the converter 9 of the generating set 1, converter 9~ is a circuit of the same kind as the circuits commonly known as inverters and will therefore not be described here either. Suffice it to say that converter 9~, like the converter 9 of the generating set 1, includes electronic elements such as transistors and thyristors.
Further, the electronic elements of converter 9~ are controlled by signals of the same kind as the signals for controlling the electronic elements of converter 9 and are collectively identified by the same reference SD as these latter elements.
It should however be noted that because converter 9 receives two voltages V3 and V3~ of opposite sign, it can comprise half as many electronic elements as converter 9.
This is a clear advantage of the generating set 41 over the generating set l since such electronic elements, which have to stand high voltages and large currents, are expensive elements.
The operation of the generating set 41 will not be described as it is identical to that of the generating set 1 in Figure 1.
Obviously converters 6a to 6c, sources 7a to 7c and converters 9a to 9c of a generating set such as the generating set 21 of Figure 5 may also respectively be similar to converter 6~, source 7~ and converter 9~ just described, with the same advantage.
As already indicated, the rechargeable source of electrical energy 7 of the generating group 1 may consist - 2~24766 .
~.
of a battery of conventional, e.g. lead or cadmium-nickel, accumulators. - -It is however known that the peak value of the a.c. -voltage supplied by a converter such as converter 9 is at most equal to the value of the d.c. voltage applied to ~ -this converter.
Thus, for example, if the voltage Vl produced by generating set 1 must have an effective value of 220V, the value U3 of the d.c. voltage V3 must be at least equal to ~r2 . 220 volts, i.e. about 312V.
To supply such a voltage, a battery of conventional, e.g. lead, accumulators must number at least 142 elements since each of them delivers a voltage of about 2.2 volts.
Such a battery of accumulators is therefore expensive and - -cumbersome.
Figure 10 illustrates an example of a device that may be used to advantage to realize the source 7 of the generating set 1 as it is very much cheaper and considerably less cumbersome than a battery of conventional accumulators.
The source of electrical energy that is ~ `
diagrammatically shown in Figure 10 by way of non-limiting example and which is also referenced 7, comprises a battery of accumulators 71 that delivers across its positive terminal 71a and its negative terminal 71b a d.c.
voltage V5 having a value U5 distinctly less than the value U3 of voltage V3. The value U5 of voltage V5 may for example be 12V or 24V.
Source 7 also comprises a voltage amplifier 72 whose input terminals 72a and 72b are respectively connected to terminals 71a and 71b of the battery of accumulators 71.
Voltage amplifier 72 also comprises a pair of output terminals 72c and 72d which are connected to the terminals 7.la and 7.lb of source 7, these being the terminals that are collectively referenced 7.1 in Figure 1. -. . :: : : - ... i . . . .

3 l Voltage amplifier 72 will not be described in detail as it is a circuit that is well known to specialists.
Suffice it to say that it is arranged to produce across its terminals 72c and 72d, from voltage V5, a d.c. voltage having a value at least substantially equal to the value of voltage V3 when terminals 72c and 72d are connected to no other element. This d.c. voltage, which is that referenced V4 in Figure 1, is of course strictly equal to voltage V3 when terminals 72c and 72d are connected to the output terminals of converter 6 via the terminals 7.la and 7.lb of source 7.
The arrows extending from terminals 7.la and 7.lb of Figure 10 symbolize the connections of source 7 with converters 6 and 9 of Figure 1.
Source 7 of Figure 10 further comprises a battery charger 73 whose inputs 73a and 73b are respectively connected to the outputs 72c and 72d of voltage amplifier 72 and whose outputs 73c and 73d are respectively connected to the terminals 71a and 71b of the accumulator battery 71.
Battery charger 73 will not be described in detail either as it is a well-known device. Suffice it to say that battery charger 73 is arranged such as to be capable of supplying to accumulator battery 71 the current needed for its recharging, at a voltage obviously equal to voltage V5. For a reason that will be made clear later, battery charger 73 is further arranged to supply the current needed for recharging accumulator battery 71 or to interrupt this current according to whether a signal Ss it receives on a control input 73e is in a first or second state.
As explained hereabove, source 7 supplies to consuming device 2 the electrical power that the latter no longer receives when converter 6 is blocked, totally or partially, i.e. after any increase in the electrical power .: - ~: -'. :. ~

- 212~7~6 ~

: . ' -: : -~.
Pe and until the rotational speed R of motor 7 has reached its new value.
It has also been explained that, once the rotational speed R of motor 3 has reached this new value, source 7 is recharged until the signal SQ representative of the amount of electrical energy it contains reaches its maximum value SQ1.
When source 7 is constituted as shown in Figure 10, control circuit 4 is arranged to supply to battery charger 73 the above-mentioned signal Ss and to give to signal SB
its first state when source 7 must be recharged, i.e. in the circumstances just described, and its second state for the remainder of the time.
It will readily be seen that when the electrical power Pe absorbed by consuming device 2 increases and that when converter 6 is totally or partially blocked as described above, the difference between this electrical power Pe and that which is still being supplied by converter 6 is supplied by the battery of accumulators 71 at a voltage V5 and transmitted to converter 9 at a voltage V3 by voltage amplifier 72.
Signal SB is then in its second state so that charger 73 supplies no current to the accumulator battery 71.
When the rotational speed R of motor 3 reaches its new value and converter 6 again starts to supply all of the electrical power produced by generator 5, control circuit 4 gives to signal SB its first state whereby charger 73 starts recharging the accumulator battery 71, the electrical power that is needed for this recharging operation being of course supplied in mechanical form by motor 3 which then supplies its full mechanical power as described earlier.
When the signal SQ that is produced by monitoring circuit 8, not shown in Figure 10, reaches its maximum value SQ1 thereby indicating that accumulator battery 71 is fully recharged, control circuit 4 returns signal SB to -- 212476~

its second state, thereby interrupting the recharging operation of battery 71, and at the same time gives to signal SM its value SM2 as has been described earlier.
As regards source 7, the above-described process repeats itself of course after each increase in the electrical power Pe absorbed by consuming device 2.
It will be apparent that a rechargeable source of electrical energy like that of Figure 10 uses an accumulator battery having only a reduced number of elements to produce the relatively high voltage V3 needed for the generating set 1 to work. As a result such a source is clearly less bulky and cheaper than an equivalent device consisting solely of a battery of accumulators that produces voltage V3 directly, even after taking into account the bulk and cost of voltage amplifier 72 and charger 73.
A rechargeable source of electrical energy like that of Figure 10 may obviously be used in all of the embodiments of the generating set according to the present invention, particularly to constitute each of the sources 7a, 7b and 7c of the generating set 21 in Figure 5.
The generating set according to the present invention may be modified in many ways within the framework of the latter.
For instance, motor 3, which as will be recalled consists in the described examples of a petrol engine fed by a carburettor, may be replaced by any kind of internal combustion engine, provided of course that the mechanical power supplied by the motor may be adjusted in dependence on the value of a signal similar to signal SM described hereinabove. Such a motor may for instance also be a petrol engine but one fed by an injection system, or a Diesel engine or a gas turbine, etc.
Motor 3 may also be constituted, still by way of example, by a steam or water turbine.

- 21247~6 Among the modifications that may be made to the generating set according to the invention, one may still mention that which consists in replacing the measurement circuit ll by a device comprising a disc concentrically fixed to the shaft connecting motor 3 to generator 5 or 25, a photo-electrical or magnetic sensor producing pulses in response to teeth or holes regularly arranged at the periphery of the disc and travelling past the sensor, and an electronic circuit supplying the signal SR in response to these pulses.
Similarly, a generating set such as that described with reference to Figure l may be modified by replacing generator 5 by a generator of a type, that is also well-known, such that voltage V2 is a d.c. voltage and not an a.c. voltage as before. In such a case, converter 6 must obviously be arranged to produce the constant d.c. voltage v3 whatever value voltage v2 may have. Further, the measurement circuit ll producing the signal SR
representative of the rotational speed R of motor 3 must be adapted accordingly, e.g. by making it in the manner just set forth, i.e. with a disc fixed to the shaft connecting motor 3 to generator 5, a sensor and a suitable electronic circuit.
A generating set such as the one described with reference to Figure 9 may clearly be modified in the same way.
A generating set like that described with reference to Figure l may also be modified by adding thereto one or more converters similar to converter 9, and by connecting the inputs of the additional converter(s) to the outputs of converter 6 and source 7, the control circuit 4 of this generating set being of course adapted to supply the control signals, similar to signal SD, needed for the operation of the additional converters. A generating set thus modified may therefore supply one or more consuming - 212~766 devices, like the generating set 21 in Figure 5, while being simpler than the latter.
It is also possible to make each of the rechargeable sources of electrical energy 7 (Figure 1), 7a to 7c (Figure 5) or 7' (Figure 9) in the form of a set of capacitors, e.g. electrolytic capacitors.
But it is well known that, unlike an accumulator, a capacitor only releases the energy it contains if the voltage across its terminals can drop.
Consequently, when sources 7, 7a to 7c or 7~ consist of capacitors, the respective converters 6 (Figure 1), 6a to 6c (Figure 5) or 6' (Figure 9) must be so adapted that the voltages V3, V3a to V3c or V3' they supply decrease while they are blocked after an increase in the electrical power Pe.

Claims

1. A generating set (1; 21; 41) for supplying electrical energy at a first voltage (V1; V1a, V1b, V1c) that is an a.c. voltage having a set effective value and a set frequency, comprising a motor (3) and a generator (5;
25) mechanically coupled to said motor (3) to produce said electrical energy, characterized in that said generator (5; 25) is arranged to produce said electrical energy at a second voltage (V2; V2a, V2b, V2c), and in that said generating set (1; 21; 31) comprises a first converter (6;
6a, 6b, 6c; 6') electrically coupled to said generator (5;
25) to convert said second voltage (V2; V2a, V2b, V2c) into a third voltage (V3; V3a, V3b, V3c; V3, V3') that is a d.c. voltage having a constant value (U3), a rechargeable source of electrical energy (7; 7a, 7b, 7c;
7') coupled in parallel with said first converter (6; 6a, 6b, 6c; 6'), and a second converter (9; 9a, 9b, 9c; 9') electrically coupled to said first converter (6; 6a, 6b, 6c; 6') and to said rechargeable source of electrical energy (7; 7a, 7b, 7c; 7') to produce said first voltage (V1; V1a, V1b, V1c) from said third voltage (V3; V3a, V3b, V3c; V3, V3').

2. A generating set (1; 21; 41) according to claim 1, characterized in that it further comprises means for adjusting the rotational speed (R) of said motor (3) in dependence on the electrical power (Pe) supplied by said generating set (1; 21; 41).

3. A generating set (1; 21; 41) according to claim 2, characterized in that said adjusting means is so arranged that said motor (3), at each particular value (Pe1, Pe2, Pe3) of said electrical power (Pe), rotates at the particular rotational speed (R1, R2, R3) at which it supplies a mechanical power (Pm) having a value equal, firstly, to said particular value (Pe1, Pe2, Pe3) of said electrical power (Pe) and, secondly, to a defined fraction of the value (Pm1', Pm2', Pm3') of the maximum mechanical power it can supply at this particular rotational speed (R1, R2, R3).

4. A generating set (21) according to claim 1, characterized in that it is intended to supply said electrical energy at a plurality of first a.c. voltages (V1a, V1b, V1c) each having a set effective value and a set frequency, by the fact that said generator (25) includes a plurality of windings (25a, 25b, 25c) to produce said electrical energy at a plurality of second a.c. voltages (V2a, V2b, V2c) each produced by one of said windings (25a, 25b, 25c), and by the fact that said generating set (21) comprises a plurality of first converters (6a, 6b, 6c) electrically coupled each to one of said windings (25a, 25b, 25c) to convert one of said a.c. voltages (V2a, V2b, V2c) into a d.c. voltage (V3a, V3b, V3c), a plurality of rechargeable sources of electrical energy (7a, 7b, 7c) coupled each in parallel with one of said converters (6a, 6b, 6c), and a plurality of second converters (9a, 9b, 9c) electrically coupled each to one of said first converters (6a, 6b, 6c) and to one of said rechargeable sources of electrical energy (7a, 7b, 7c) to produce one of said first a.c. voltages (V1a, V1b, V1c) from one of said d.c. voltages (V3a, V3b, V3c).

5. A generating set according to claim 1, characterized in that it is intended to supply said electrical energy at a plurality of a.c. voltages (V1a, V1b, V1c) each having a set effective value and a set frequency, and by the fact that it comprises a plurality of second converters (9a, 9b, 9c) electrically coupled to said first converter (6) and to said rechargeable source of electrical energy (7) to produce each one of said first a.c. voltages (V1a, V1b, V1c) from said third voltage (V3).

6. A generating set (1; 21; 41) according to claim 1, characterized in that said rechargeable source of electrical energy (7; 7a, 7b, 7c) comprises a battery of accumulators (71) to produce a fourth voltage (V5) that is a d.c. voltage having a value less than the value of said third voltage (V3), a voltage amplifier (72) coupled to said battery of accumulators (71) to produce from said fourth voltage (V5) a fifth voltage (V4) that is a d.c.
voltage having a value at least substantially equal to the value of said third voltage (V3), and a battery charger (73) coupled to said voltage amplifier (72) and to said battery of accumulators (71) to recharge said battery of accumulators (71) from said third voltage (V3).