FR2490893A1 - STABILIZATION CIRCUIT FOR INVERTER-MOTOR CONTROL SYSTEM - Google Patents

Abstract

THE STABILIZED OPERATION OF AN INVERTER 25 AND OF AN ALTERNATIVE MOTOR 41 SUPPLIED BY THE INVERTER IS OBTAINED IN THE PRESENCE OF SUDDEN VARIATIONS IN LOAD BY CONTROL OF THE INVERTER AS THE AMPLITUDE AND FREQUENCY OF THE OUTPUT VOLTAGE OF THE INVERTER. THE UPS VARY WITH THE VOLTAGE OF THE BARS IN DC CURRENT: WHEN A BRUTAL VARIATION IN THE LOAD CAUSING A VARIATION IN THE VOLTAGE OF THE BARS, THERE IS A CHANGE OF FREQUENCY WHICH COMPENSATES THE VARIATION IN THE LOAD AND STABILIZES THE VOLTAGE OF THE BARS. BY USING THE TENSION OF THE BARS TO REGULATE THE FREQUENCY OF THE INVERTER, IN THE EVENT OF A BRUTAL DECREASE IN THE MECHANICAL LOAD 43, THE TENSION OF THE BARS WILL CAUSE THE FREQUENCY OF THE OUTPUT VOLTAGE OF THE INVERTER TO INCREASE, WHICH WILL DECREASE THE MOTOR SPEED, WHEREAS A REDUCTION IN THE VARIATION OF THE ELECTRICAL LOAD OF THE BARS 26, 27. THE VOLTAGE OF THE BARS THEN TENDED TO REMAIN RELATIVELY CONSTANT. IN THE EVENT OF NORMAL VARIATION IN THE LOAD, REQUIRING A DIFFERENT MOTOR SPEED, A REFERENCE VOLTAGE CAN BE SET TO CHANGE THE AMPLITUDE OF THE FREQUENCY OF THE OUTPUT VOLTAGE OF THE INVERTER AND TO BRING THEM TO THE LEVEL NECESSARY FOR THE DRIVE ENGINE AT THE SAME SPEED.

Description

249089J

1.

  The present invention relates to a communication system.

  command to stabilize the functioning of a system

  inverter-motor during transient phenomena or

  disturbances, which translates into significant improvement

  ration of dynamic behavior, as well as walking in

  constant conditions when the operating conditions-

  may cause the system to oscillate.

  Inverter-motor systems tend to oscillate

  ler at low frequencies under certain operating conditions

  during which the inverter seems to oppose

  negative resistance to the bus bars in cross current

  the supply voltage of the inverter.

  present invention allows the inverter to appear

  opposing me more positively, which allows

  reduce the tendency to oscillate.

  In addition, inverter-motor systems can have torques under load which vary suddenly, causing significant deviations from the tension of the bars,

  in direct current in constant operation. The present invention

  The object is also to reduce the effect of a varia-

  brutal load torque on the voltage of the DC busbars, thereby reducing the

  deviations from the desired tension of the bars.

2. 2490893

  The origin of undesirable variations in blood pressure

  bus bars can be attributed to the presence of the wire-

  tre, consisting of a coil connected in series and a condenser

  sator connected in parallel, which is generally incorporated in the DC power supply producing the voltage

  bars. During normal operation in the cons-

  as long as no average current flows in the filter capacitor and all of the current flows to the inverter, q and then the motor windings. If there is a sudden fall,

  for example, of the torque under load of the motor, the current of the mo-

  tor decreases sharply and the inductor current flows through the filter capacitor, charging it to a voltage

  much higher. As the bus bars in current

  tinu are coupled to the terminals of the capacitor, their voltage also increases significantly. The high voltage of the bars, in addition to its detrimental effect on the operation of the motor, can destroy the switching devices (which can be transistors) located in the inverter. To

  to avoid such destruction, switching devices

  tion oversized are general.c7n-rt employees whose ca-

  characteristics to withstand the highest tension of the bars which may occur in the event of variation

brutal charge.

  The control system of the present invention allows

  achieves significantly improved dynamic performance

  and solve the problem of instability by regulating

  actually the voltage of the bus bars in current

  bare in order to give the engine a certain stability, while avoiding the need to oversize the

  switching. In the present invention, the negative resistance

  ve of the inverter is made more positive so as to eli-

  undermine the tendency to oscillate. At the same time, the present

  The invention has an effect on the way in which the torque of the motor varies over time so as to reduce the deviations of the tension of the bars in direct current compared to the

desired value.

  The control system of the present invention allows

3. 2490893

  puts the control of the operation of a motor with al-

  ternative subject to the output of an alternating voltage of a

  inverter, which in turn is supplied by the voltage con-

  adjustable continuous bus bars, from

  from a controlled direct current source. The control system comprises a means supplying the voltage of a point

  control representing a desired amplitude and a frequency

  quence desired for the alternating voltage produced by the on-

  odor. Means make it possible to use the voltage of the set point in order to establish the output voltage of the inverter at the desired amplitude and its frequency at the desired level. A

  stabilization means, responding to an unwanted variation

  ble of the voltage of the bus bars in direct current, per-

  puts to vary the frequency of the inverter to control

  the electric charge across the bars of the direct current

  naked and maintain their tension at a relatively constant value

  aunt. The present invention will be well understood during

  the following description made in conjunction with the drawings

  attached in which FIG. 1 is a schematic representation of a control system, according to one of the embodiments of the present invention, and of the manner in which the control system is coupled to an inverter-motor system for controlling and stabilizing its operation; and

  Figures 2 and 3 show parts of the system

  control unit of FIG. 1, according to two variants of

  realization of the present invention.

  In connection with Figure 1, lines LI, L2 and

  L3 are input lines of a tri-

  classic phased which provide a three-phase voltage, that is to say three alternating voltages out of phase with each other of 1200 and have a frequency of 60 hertz. Each of the three-phase voltages is a line-to-line voltage and appears on one of the conductors L1, L2 and L3 relative to the other. The alternative energy present on the 4. lines is transformed into direct current energy by a

  controlled rectifier bridge 10 of known construction. More specific

  specifically, the bridge has a family of six rectifiers

  silicon ordered 11-16 which, when made con-

  conductors by a grid current from a device

  rectifier control unit 17, rectify the alternating

  ve applied, and give the positive and ne-

  gative of the bridge (represented by 18 and 19, respectively) a rectified voltage having an amplitude determined by the

  rectification conduction angles during each half-cycle

  key of the applied alternating voltage.

  By way of explanation, each silicon rectifier controlled from bridge 10 can be conductive during the positive half-cycle of the voltage applied by the power supply system

  in alternating current, when its anode is positive compared to

  port at its cathode. However, conduction does not occur during a positive half cycle as long as the gate current

  is not supplied at its door by the control device 17.

  At this instant, the controlled silicon rectifier enters into

  conduction and allows the charge current to flow through

  towards him until the end of the positive half-cydle. The larger the phase angle or delay between the start of a positive half cycle and the conduction of the rectifier, the smaller will be

  the conduction angle and the rectified average voltage and provides

  denies the charge. Naturally, the rectified voltage will have a

  positive polarity at terminal 18 with respect to terminal 19.

  A filter 20, consisting of a coil in series 21 and

  of a rectifier in shunt 22, filters the rectified voltage pro-

  coming from the bridge so as to give a continuous tension wire-

  input intended to be applied to an inverter 25 by bars

  res om dc current constituting lines 26 and 27. A dc voltage of positive polarity will be

  therefore present on line 26 with respect to the line

  gene 27 which is connected to a reference or neutral ground of the circuit, the voltage of which is zero in the mode of

  shown achievement. By controlling the angles of conduct-

  tion of rectifiers 11 to 16, the DC voltage

2490893

  applied to the inverter 25 via the lines 26,

27 is ordered.

  UPS 25 has a good circuit configuration

  known. It includes three pairs of power transistors

  this bipolar NPN 31-36, each pair being connected in series between the bus bars 26, 27. The junctions 37, 38 and

  39 of the three pairs of transistors are connected to the

  bearings of an induction motor 41, including the output shaft

  42 causes a mechanical load 43. By providing a cou-

  control rant at the bases of the six bipolar transistors

  31-36 at prescribed times, the direct current voltage

  bare bus bars is transformed into alternating voltage which is applied to the motor windings, which has the effect of delivering alternating current to these windings and causing the motor 41 to rotate at a speed determined by the alternating output voltage of the which inverter

  directly proportional to the frequency of this voltage.

  For example, if the base control current is supplied simultaneously to the transistors 31 and 35 to put them in the saturation mode, the current will flow from the line 26 and will cross the following elements in the order conduction path emitter- collector of transistor 31,

  junction 37, motor winding 41, junction 38 and tra-

  emitter-collector conduction jet of transistor 35, to reach line 27 or mass. If transistors 31 and 35 are then made non-conductive and transistors 32 and 34 are made conductive, current will flow in the

  same motor winding but in the opposite direction. Natu-

  actually, the control circuit providing the current

  of the bases of transistors 31-36 to cause them to conduct-

  tion-non-conduction following the correct sequence, ins-

  both correct and at the correct frequency, so that either

  obtained the alternating current energy necessary for the ro-

  tation of the motor 41 and of the load drive 43 is well known to those skilled in the art. In the embodiment shown, this control circuit is represented by the

  block 45. Naturally, such a control circuit includes

  6.dra a logic circuit and a controlled oscillator which, in response to a control voltage from line 47, provides periodic synchronization pulses and

  programmed, or base control signals, to transist

  tors 31-36 so as to establish the frequency of the output voltage of the inverter and therefore the speed of the motor

  41. The frequency of repetition of the synchronization pulses

  This will depend on the control voltage present on line 47. Consequently, the frequency of the inverter is controlled by varying the amplitude of this voltage.

control.

  The transmitter-collector conduction path of

  one of the six power transistors 31-36 is shunted by a

  diode from a series of six reaction diodes with op-

  posed 51-56 whose function is to bring back the reactive current

  tif from the motor to the filter capacitor 22. The diodes

  51-56 are also used to fix the voltage across the terminals

  so that it never exceeds the bar tension

res omnibus in direct current.

  Although not shown in the figure, each tran-

  sistor 31-36 will preferably also be bypassed by a circuit

  cooked conventional damper whose function is to avoid damage to the transistors by the inductive energy of

  motor windings when these are made unconscious

  conductors through circuit 45 during normal operation

  wrong. While each bipolar power transistor 31-36 is shown as being a conventional NPN transistor (in order to simplify the figure), it would in reality be preferable for it to have the shape of a well known power Darlington transistor. In the Darlington layout, each

  transistor 31-36 includes a combination of two transist

  tors, while still having only three connections,

  ie the basic, emitter and collector connections as shown in the figure. Naturally,

  while bipolar power transistors are re-

  presented as constituting the switching devices,

7 2490893

  other devices such as thy-

  ristors, field effect transistors, etc. In order to control the operation of the

  rectifier control device 17 in order to adjust the am-

  plitude of the alternating voltage of the output of the

  and control the operation of the control circuit

  of 45 in order to regulate the frequency of the voltage

  the inverter, an adjustable set point or voltage

  dre ference is provided at the junction 57 d. a fixed resistor 58 and a variable resistor 59. As will appear, the voltage of the set point from the

  voltage divider 58, 59 determines the operating conditions

  operating in a constant state and represents an amplitude

  sirée and a desired frequency for the alternating voltage

  produced by inverter 25 and applied to motor 41. From pre-

  reference, the set point will be selected so that

  lay at the speed requested by the mechanical load 43. A comparator 61 compares the voltage of the set point with a voltage proportional to the voltage of the bus bars in direct current (due to the presence of the gain factor K62), in order to provide a error voltage which is a function of the difference between the compared voltages. K62 establishes the gain between the voltage of the DC bus bars

  and the tension of the set point. The control system

  of 17 rectifiers responds to the error voltage in order to

  produce correct rhythmic gate current pulses

  which are intended to be applied to the grids of

  rectifiers 11-16 in order to control their conduction angles

  tion and establish an amplitude of the tension between the li-

  genes 26 and 27 necessary for establishment and maintenance

  from the output voltage of the inverter to the desired value.

  If the voltage of the DC bus bars has reached

  dance to vary from the value corresponding to a

  constant state, the error voltage changes and brings the dis-

  control positive 17 to vary the driving angles

  to adjust the tension of the bars

  DC bus and recovery. level of am-

8. 2490893

correct flatness.

  In the meantime, the control voltage enabling the operation of the circuit 45 to be regulated is established by adding, in a summing circuit 63, the voltage of the set point and a voltage proportional to the error voltage. K64 represents a transfer function and indicates the gain of the feedback loop. The value of K64 is selected so that the performance is best. Too low a value will have a negative effect on the positive characteristic of the control system, so

  too high a value will cause instability. The ten-

  control will thus depend on the error voltage and the voltage of the set point, after which,

  base control or synchronization signals

  grammars applied to transistors 31-36 will have the frequency required to establish the frequency of the output voltage of the inverter at the level corresponding to the constant state. As

  the amplitude and frequency of the output voltage of the on-

  are both determined by the point tension

  of adjustment, these two characteristics of the voltage of the

  duleur will have a k; j L fixed between them when no tens-

  no error is present. This ratio can be adjusted by the gain factor 62. A fixed ratio is desirable to

  so as to avoid overheating of the motor 41 and to

  rer an output with constant torque whatever its speed-

  se. When there is a normal variation in the load demand, thereby dictating a different speed of the constant motor, the resistor 59 can be adjusted so as to vary the voltage of the set point for

  that the variation of the control voltage allows

  blir the frequency of the inverter voltage at the ne-

  stop driving the engine 41 for the new

  desired size. At the same time, the new point tension

  regulates the voltage of the bus bars

  continuous, so as to maintain a fixed relationship between

  the amplitude and frequency of the output voltage of the on-

9 2490893

  dleur. Naturally, while the engine speed can

  be changed by manually adjusting the varia-

  ble 59, the set point voltage can be obtained by detecting a parameter or a characteristic of the system

  to which the inverter-motor system belongs so as to

  automatically request engine speed in response to

this information.

  It should also be noted that the supply of

  continuous rant (i.e. the rectifier bridge 10 and the wire-

  tre 20) can operate in response to a mono- energy

  phased instead of three-phase energy. In the case of single-phase energy, line L3 and rectifiers 13 and 16

  would be omitted. Naturally, a positive tension of the bars-

  res omnibus in direct current will always be produced on line 26 compared to line 27. It will also be noted that the realization of the supply of direct current and

  of the inverter can have different shapes. For example-

  ple, direct current bus bars could be powered by a dc-powered converter

  itself by direct current bus bars.

  In the case where the mechanical load of the motor 41 will

  abruptly laughs, in the absence of the stabilization circuit of the invention, the voltage of the DC bus bars would be modified. By way of explanation, suppose that the load torque of the motor 41 abruptly decreases, or cancels out, causing an abrupt reduction in the average current

  circulating in the bus bars in direct current supplied

  both the inverter. The current from the filter coil then flows through the capacitor 22 so as to charge it up to a voltage substantially higher than the desired voltage of the bus bars. However, the tendency for tension

  bars to be increased will be compensated, in this in-

  vention, by increasing the speed of the motor in re-

  response to the increase in this voltage, so that the system

  the inverter-motor will not be affected and that a function-

  stable will follow. Indeed, the present invention 10.

  allows to maintain, in the case where one is present

  this of an abnormal abrupt variation in the load of the motor 41, an electric charge between the bars 26, 27 which causes

  the tension to remain relatively fixed.

  This immunization to sudden or transient variations in the load torque is obtained by command of

  the frequency of the inverter so that it varies directly-

  with the voltage of the bus bars in direct current.

  If this tension tends to increase, during the fall of the

  load torque, the error voltage will increase and cause

  ra the increase in the control voltage, as a result of which the control circuit 45 of the inverter will cause a

  increasing the frequency of the on-output voltage

  odor. This will result in an increase in engine speed and this increase will cause an increase in the electrical load on the bus bars which will have the effect

  to compensate for the decrease in electrical charge occurring

  health when the mechanical load decreases itself. In short, the motor will accelerate each time there is a fall in the mechanical load, presenting a reduced variation of the

  electrical load on bus bars. The error voltage se-

  ra then brought to zero by the bar regulation circuit

  res omnibus, and the system will work again at

  frequency and voltage imposed by the voltage of the set point. The gain of the ratio of the transient variation or deviation of the tension of the busbars compared to the deviation

  resulting frequency for the inverter will be adjusted by the fac-

  gain sensor K64 and can be adjusted differently

  te, and independent, of the gain factor 62 in the constant state.

  Naturally, if the motor 41 is subjected to an increase

  brutal statement of the load torque resulting in an increase in the electric charge and a reduction in the voltage of the bus bars in direct current, the voltage

* error will occur and cause a decrease in the frequency

  this from the inverter and the motor speed so that the electrical load on the bus bars will decrease and their

tension will increase.

He.

  To summarize the operation of the embodiment

  tion of the present invention shown in Figure 1, in the case of constant normal conditions, the device

  command 17 is used to reset the error voltage to zero. The ten-

  The DC bus bars are then linked to the set point voltage by the gain factor K62. At that time, the control voltage, which determines the frequency

  of the inverter, is equal to the voltage of the set point.

  Therefore, the ratio between the tension of the omni bars

  DC bus and frequency of 1Volverter can

  be adjusted by K62. Under operating conditions-

  transient, the error voltage will not be zero. The

  gain factor K64 determines the value of the difference in voltage

  control position in relation to the set point which is pro-

  will yield for a given error voltage. K64 therefore determines the magnitude of the frequency deviation from

  the constant state value that will occur under conditions

  transitional conditions. The relationship between the tensin deviation of

  DC bus bars vis-à-vis the set value

  constant state and the frequency deviation of the on-

  of the desired value in the constant state is,

  therefore, adjusted by the gain factor K64.

  sulte, that the ratio between the voltage of the busbars to

  the constant state and frequency of the inverter can be-re-

  set independently of the relationship between the difference in the voltage of the bus bars and the difference in the frequency of the inverter

under transitional conditions.

  It will be understood that the present invention can be practiced in various ways so as to cause a deviation of the frequency control voltage proportional to the deviation of the voltage of the bus bars in direct current with respect to the value desired, In the embodiment of Figure 1, transient changes in voltage

  bus bars translate into transitive changes

  error voltage roofs, which are then used to

  vary the frequency of the inverter. The means of stabilization

  The present invention can, of course, respond

12. 2490893

  dre directly to a transient variation of the voltage of the bus bars in direct current. This is shown in the embodiment of Figure 2. In this embodiment, the feedback loop between the bus bars and the inverter excludes the comparator 61, unlike the case of Figure 1. In addition, depending on the mode As shown in FIG. 2, K64 is preceded by a bandpass filter 65 so as to eliminate any effect in the constant state of the

  ordered. With such a filter, the stabilization circuit

  will only respond to transient variations in voltage

  bus bars. In other words, during a function-

  normally normal o the inverter-motor system operates under different constant state conditions, no voltage

  is applied, via the filter 65, to the circuit

  summed up 63 and the frequency of the inverter is

  blie entirely by the tension of the set point. However

  However, when the tension of the bus bars undergoes a variation

  transient undesirable, this variation will be trans-

  se by the filter 65 to the summing circuit 63. [n effect, the

  summing circuit 63 does not respond to relative variations

  the tension of the bus bars but at

  relatively rapid variations.

  taken by the summation circuit, will therefore be

  and the frequency of the inverter changed, according to the pre-

  invention, so as to compensate for a sudden change

the voltage of the bus bars.

  Naturally, any transient change in the

  busbar tension will also appear as chan-

  transient control of motor voltage or voltage

  output of the inverter, which are essentially the same.

  Therefore, the present invention can be practiced by establishing a feedback loop between a current motor

  41 and the inverter 25 so as to adjust the frequency

  this from the inverter in response to transient changes in the output voltage of the inverter. This is represented

  in the embodiment of FIG. 3. The three-

  phase produced by the inverter 25 and rectified by a rectifier-

13. 2490893

  seur 67 so as to give a direct current voltage which

  will have substantially the same amplitude as the tension of the bars

  res omnibus applied to the inverter. In addition, any

  transient tion of the DC busbar voltage will manifest itself as a transient variation in the voltage

  DC output of rectifier 67. By cons

  sequent, such a direct current voltage can be app-

  applied to comparator 61 and the system will function sensi-

  in a manner analogous to that of FIG. 1.

  It thus appears that the present invention not only makes it possible to stabilize the operation of an inverter-motor system, but also by avoiding the increase in

  the voltage of the DC output bars in response to

  to a sudden drop in the load torque, not to over-

  dimension the transistors of the inverter.

  The present invention is not limited to the exemplary embodiments which have just been described, it is on the contrary

  subject to modifications and variations

  which will appear to those skilled in the art.

14. 2490893

Claims (11)

  1 - System for controlling the operation of a mo-   alternating current supplied by the alternating output voltage of an inverter which is supplied by the adjustable voltage of direct current bus bars connected to a controlled direct current supply, characterized in that it comprises: - means (57 -59) to provide a voltage of a set point representing a desired amplitude and a   desired frequency for the alternative current voltage   picked up by the inverter; - means (61, 17, 62, 64, 63, 45) for using the voltage of the set point to establish the output voltage of the inverter at the desired amplitude, and its frequency at the desired level; - And a stabilization means (62, 61, 64, 63, 45), responding to an undesired variation of the voltage of the bus bars in direct current, to vary the frequency of the inverter and control the electrical load of the bars   omnibus in order to maintain the tension of these bars at a their relatively constant.   2 - System for controlling the operation of a mo-   AC tor powered by the AC output voltage   tie of an inverter supplied by the adjustable voltage of bar-   DC bus res, connected to a power supply   in controlled direct current, characterized in that it comprises   takes - a means (57-59) for supplying a point voltage   of adjustment representing a desired amplitude in the cons-   as long as a desired frequency in constant state for the voltage   alternative voltage produced by the inverter; - a means (61) for comparing the tension of the point of   adjustment at a voltage proportional to the tension of the bars   res omnibus in direct current to produce a voltage   error which is a function of the difference between the   compared sions; - a means (17) for using the error voltage 15. 2490893   in order to establish the output voltage from the inverter to the amplifier   desired study in a constant state; - means (63, 45) for using the voltage of the set point to establish the frequency of the output voltage of the inverter at the desired level in a constant state; - And a stabilization means (62, 61, 64, 63,) responding to a transient variation in the voltage of the bus bars in direct current, in order to vary the frequency of the inverter and control the electrical load of the bus bars in direct current and maintain voltage   bars at a relatively constant value.   3 - System according to claim 2, characterized in that the stabilization means comprises a loop of   reaction (61-64, 45) between the bus bars and the inverter.   4 - System according to claim 2, characterized in that a transient variation in the voltage between the bus bars results in a transient variation in the error voltage and in that the stabilization means is controlled by the error voltage.   5 - System according to claim 2, character-   dried in that the stabilization means comprises a filter (65) so as to respond only to transient variations   of the voltage of the bus bars in direct current.   6 - System for controlling the operation of a mo-   AC current supplied by the AC output voltage of an inverter supplied by the adjustable voltage of DC bus bars connected to a power supply   in controlled direct current, characterized in that it comprises   takes: - means (57-59) for supplying a set point voltage representing a desired amplitude and a   desired frequency for AC voltage pro- picked up by the inverter;   - a means (17, 61-64, 45) for using the voltage   setting point to establish the output voltage   of the inverter at the desired amplitude and at the desired frequency   rée; i6. - And a stabilization means (61-64, 45) comprising a feedback loop between the direct current bus bars and the inverter, for adjusting the frequency of the inverter in response to transient variations in the voltage of the bou_ es omnibus in direct current so as to compensate for these variations and provide a relatively constant voltage between the bars.   7 - dF, r, system. rcnde du Furlctionnemenl r '' eur in alternating current supplied by the output voltage in   alternating current of an inverter supplied by the voltage   glable of direct current bus bars, connected to a "controlled direct current power supply, characterized in that it comprises: - a means (57-59) for supplying a checkpoint voltage. - "re] à'r cfr," and a desired frequency in a constant state for the alternating current voltage produced by the inverter; - means (61) for comparing the voltage of the point of   i f'q- i at a tensir'Vr; i; r, i at the voltage 'n b: r-   res omnibus in order to produce an error voltage which is functional   t.r 'of the difference itr,: ..: (ib.ui S: oIppail'C, _; - a means (17) for using the error voltage in order to adjust the voltage of the bars in direct current according to   necessary in order to establish the output voltage of the on-   dul'ur at the desired amplitude in the constant state; - a means (63, 45) for using the stitch tension   setting to set the frequency of the output voltage   tie de 'mir au niéen ie the constant state .; - the system having a predetermined gain factor for operating conditions in the constant state which determines the ratio between the voltage of the bus bars in direct current and the frequency of the inverter; - and a stabilization means (61-64, 45), responding to   a transient deviation from the voltage of the bus bars   continuous rant, to deflect the frequency of the inverter in order to control the electrical load of the bus bars and maintain the tension of the bars at a relatively 17. 2490893 constant;   - the system having a gain factor in con-   transitional editions which can be set independently of the   constant state gain factor to provide a ratio   different port between the voltage difference of the omni- bars   DC bus and the frequency deviation of the undu- their.   -8 - System for controlling the operation of a mo-   alternating current supplied by the output voltage   tie in alternating current of an inverter supplied by the   adjustable sion of the bus bars connected to a power supply   in controlled direct current, characterized in that it comprises   takes: - a means (57-59) for supplying a point voltage   control representing a desired amplitude and a frequency   this desired for the alternating current voltage produced by the inverter; - a means (17, 61-64, 45) for using the voltage of the adjustment point in order to establish the output voltage of the inverter at the desired amplitude and its frequency at the desired level;   - and a stabilization means (61-64,45), including   nant a feedback loop between the motor in al-   and the inverter, to adjust the frequency of the inverter   their in response to transient variations in the output voltage of the inverter in order to compensate for these variations and provide a relatively constant output voltage of the inverter.   9 - System for controlling the operation of a mo-   AC current supplied by the AC output voltage of an inverter which is supplied by the adjustable voltage of DC bus bars, connected to a controlled DC power supply, characterized in that it comprises: - means ( 57-59) to provide a point voltage   control representing a desired amplitude and a frequency   quence desired for the alternating current voltage produced te by the inverter; 18. 2490893   - a means (61) for comparing the point tension   output at a voltage proportional to the voltage of the bars   res omnibus in direct current to produce a voltage   error which is a function of the difference between the   compared sions; - a means (17) for using the error voltage   in order to establish the output voltage from the inverter to the amplifier   desired study; - and means (63, 45) for using the error voltage and the voltage of the set point to establish the frequency of the output voltage of the inverter at the desired level; - the error voltage stabilizing the operation   of the inverter-motor system by bringing the frequency of the inverter   their to vary each time that the tension of the busbars undergoes an undesired variation of amplitude, from which it results   that there is control of the electrical charge of the omni-   bus in order to keep the busbar tension at a re- laterally constant.   10 - System for controlling the operation of a mo-   AC current supplied by the AC output voltage of an inverter supplied by the adjustable voltage of   direct current bus bars, connected to a power supply   controlled DC current, the amplitude of the voltage   alternative output of the inverter being determined by the am-   fullness of the voltage of the bus bars in direct current   while the frequency of the inverter voltage is   terminated by the frequency of synchronization pulses applied to the inverter, characterized in that it comprises - means (57-59) for supplying a set point voltage representing a desired amplitude and a   desired frequency for AC voltage pro-   picked up by the inverter; - a comparator (61) for comparing the voltage of the set point with a voltage proportional to the voltage of the bus bars in direct current in order to produce an error voltage which is a function of the difference between 2490E93 19. the tensions compared;   - a control device (17), actuated by   in response to the error voltage, to control the supply of DC power in order to adjust the voltage of the DC bus bars to the level necessary for setting the AC voltage from the inverter output to the desired amplitude;   - a summing means (63) to provide a tension   control from the error voltages and the set point;   - and an inverter control circuit (45) ac-   operated in response to the control voltage to provide   synchronization pulses occurring periodically   only to the inverter in order to establish the alternating voltage.   ve output of this inverter at the desired frequency, which has the effect of adjusting the motor speed to a n; r, desired; - the error voltage leading to the frequency of   the inverter to vary with, and in the same direction, the varia-   voltage of the bus bars in direct current so as to control the electrical load of the bus bars,   as a result, the tension on the bus bars is main-   held at a relatively constant value and I operate   inverter-motor stability system.   II - Control system according to claim 10, characterized in s lu ee control circuit of the 'inverter comprises a logic circuit and an oscillator controlled from   way to provide the synchronization pulses occur   periodically to regulate the frequency of the inverter.   12 - control system according to claim, characterized in that the DC power supply   controlled includes a bridge of silicon rectifiers   ordered, phase controlled (10) and a filter (20) for   develop the tensinn rim bus bars in direct current from alternating current energy   an AC power system.   13 - control system according to claim 20. 2490893   10, characterized in that the summing means (63) comprises   takes a summing circuit to which the voltage is applied   setting point and a voltage proportional to the error voltage, the two voltages being added by the summing circuit so as to produce the control voltage. 14 - control system according to claim 10,   characterized in that the summation means responds to   Relatively rapid error voltage riations produced by transient changes in busbar voltage.   - Motor operation control system   alternating current powered by alternating voltage   output of an inverter supplied by the regulated voltage   ble of direct current bus bars connected to a supply   controlled direct current statement, characterized in that it comprises: - means (57-59) for supplying a set point voltage representing a desired amplitude in the constant state and a desired frequency in the constant state for the alternating current voltage produced by the inverter; - means (61) for comparing the voltage of the set point with a voltage proportional to the voltage of the DC bus bars so as to produce an error voltage which is a function of the difference between the compared voltages; - a means (17) for using the error voltage   in order to establish the output voltage of the inverter at the amplifier   desired study in a constant state; - a means (63-45) to use the stitch tension   output to establish the frequency of the output voltage   tie the inverter to the desired level in a constant state;   - and a means (61-64, 45) to stabilize the function   operation of the inverter-motor system, during transient conditions, causing the frequency of the inverter to vary   whenever the tension of the bus bars undergoes a   unwanted amplitude, which has the effect of 21. 249OQ93   order the electrical charge from the bus bars to maintain   keep the tension of the bars at a relatively constant value aunt.