Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
  • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
  • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
  • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M7/505—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
  • H02M7/515—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
  • H02M7/5152—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with separate extinguishing means

Definitions

• This invention relates to electric power converter circuits for variable-speed,switched, reluctance motors.
• Such motors and converters involve the use of phase windings on the stator poles, which are connected in series with thyristors across a d.v. supply, with the thyristors being switched on in 20. synchronism with the movement of the rotor in relation to the stator to provide driving torque.
• the thyristors are switched off, or commutated, at appropriate instants during rotor rotation, and the object of the present invention is to provide 25. an improved means for commutating the thyristors.
• an electric power converter circuit for supplying from a d.v. supply .w ic may ;be split into two portions in series -unidirectional " pulsating currents to each main
• each main winding a circuit including that main winding*" and at least one diode, whereby each main winding can return enery to the d.v. supply, or a portion of it, -triggering-means for switching on each main thyristor in synchronism with the relative movement
• the means whereby a main winding can return energy to the d.v. supply may include an auxiliary
• one portion of the supply - include a circuit containing the other portion of the supply, the main winding and one or more diodes.
• a transistor could be arranged to commutate all the thyristors connected between one side of the supply and half of the phase windings, while another transistor could be arranged 5. to commutate the other thyristors. It is also possible by providing a pair of additional thyristors, one or other of which is switched on when a single transistor is switched on, to have only a single transistor for commutating all the thyristors. 10.
• the invention is also applicable to a motor with bi-filar phase windings, each main winding being closely coupled to an auxiliary winding connected in series with a diode across the supply.
• the common transistor can .be used for commutating any or all of the main winding thyristors.
• the invention is also applicable to a three 20. phase motor in which each winding has two main thyristors (top and bottom thyristors) ,one connected between one end of the winding and the corresponding side of the supply. Then a single transistor could be used for commutating all the main thyristors connected 25. between one side of the supply and the corresponding ends of the main windings, and another transistor could be used for commutating the other thyristors. Once again, by use of two additional thyristors, a single transistor can be used for commutating all the main thyristors, but 30. not all at the same time; the top and bottom thyristors have to be
• the advantage of the invention lies in the use of a single transistor for commutating a number of thyristors. Whereas a transistor may be used as the
• main switching device for energising a winding in synchronism with rotor movement transistors tend to be expensive, as compared for example with thyristors .and hence thyristors are preferable as the main switching devices.
• thyristors require a separate commutation
• commutation relies for its own turn off on the discharge " of a commutation capacitor giving a reverse voltage time which reduces as the commutation current increases. Furthermore, the commutation capacitor must be recharged before a further commutation of a given main thyristor
• the present invention enables a single transistor to be used for commutating a number of
• FIGS. 5 are circuit diagrams of six power converter circuits and FIGURE 7 shows how a number of transistors can be used in combination as a single transistor common to a number of thyristors.
• batteries may in each case, comprise a relatively large capacitor or capacitors fed from the a.c. mains by a rectifier or controlled rectifier either directly or through an isolating transformer, or fed from an isolating d.c .
• d.c. convertor or may comprise a rectifier capacitor circuit whereby two series d.v. supplies may be generated from a single a.c. mains supply as disclosed in British Patent Specification No. (TASC " 2) or may consist of any know form of direct voltage supply.
• TASC British Patent Specification No.
• the direct voltage supply is a battery it may be necessary to connect a capacitor across the battery so as to bypass the a.c. component which would otherwise flow through the battery, the battery thereby supplying the d.c. component.
• the motor is a four-phase motor, having four main windings, A.B.C. and
• the cathodes of the thyristors T «r ⁇ and T_* are the cathodes of the thyristors T «r ⁇ and T_*.
• Two commutating d.v. supplies 17 and 18 are connected between respective sides 15 and 16 of the d.v. supply and the collector of a transistor 22 and the
• emitter of a transistor 23 respectively.
• the emitter of the transistor 22 is connected to the anodes of the commutating diodes D and D and similarly the collector of the transistor 23 is connected to the cathodes of the commutating diodes D_ and D_.
• the transistor 22 can then be switched off, and if it was desired to commutate only one of the thyristors T and T_, the other can be immediately 5. turned on again. If, say, the main thyristor T has been commutated, then the current in the main winding A continues to flow through the diodes D E_ and DA to return energy to the supply until the current has decayed.
• the circuit enables fine control to be achieved 10. Because the transistor 22 can be switched as required and the commutating supply 17 is also always at the right polarity for commutating the thyristors A and T . What is more, this is achieved without having to have one transistor for each of the thyristors T and T .
• The. 15. transistor 23 operates in a similar manner for commutating the thyristors T and T .
• the free-wheeling thyristor T can be switched on if it is desired to allow the current in the main winding A or C to free-wheel when the thyristor T or 20.
• ⁇ _ is switched off through a circuit including the commutating diode D A or D .
• FIGURE 2 The circuit of FIGURE 2. is quite similar to that of FIGURE 1, but it shows how a single transistor shown at 24 can be used for commutating all of the main 25. thyristors T , T , T , and T . There is a single commutating direct source 25 and that is connected in series with the emitter collector path of the transistor 24 and commutating thyristors and T ⁇ across the d.v. supply 12. 3° « If when ' it is desired to commutate the thyristors
• the transistor 24 is switched on, it is A C necessary also to switch on the thyristor T , and then commutating voltage can be applied in reverse across the thyristors T ft and T from the positive side of
• the transistor 24 is shown with a snubber circuit connected
• Thyristor T having been deprived of current, turns off and only after sufficient time has elapsed for this turn off to be complete can transistor 24 be turned
• the circuit of FIGURE 3 is very like that of FIGURE 2, and a single transistor 24 can be used for commutating all of the main thyristors T , T_, and T .
• the circuit has some disadvantages, 5. but nevertheless may be useful in certain applications.
• the motor is a three phase motor, with phase windings, A , B , and " C-, each of which is connected in series with a main thyristor T , T , or T_ in series across the supply
• Each phase winding is closely coupled in a 1:1 transformer ratio with an auxiliary winding A., A_, or A g on the same stator pole, and connected in series with a diode DA.., DA-, or DA- across the supply 32.
• a thyristor is on its phase winding draws current from the supply, but as soon as it is commutated by switching on a transistor TR, so that a commutating supply provided by a battery S- is connected through commutating diodes D_, D and D_ in reverse across the thyristors,
• phase windings current in the phase windings is transferred firstly to the transistor and subsequently to the auxiliary windings and can flow to return energy to the supply 32.
• a single transistor is used for commutating all the thyristors, and if any thyristor is required to
• phase windings A , B , and C are shown with phase windings A , B , and C , each of which is connected across a d.v. .supply 31 in
• Commutating diodes D_. , D administrat, and D_ enable the thyristors 1, 2 and 3 to be commutated from a commutating supply19 when a transistor 22 is switched on, and similar diodes D 4., D5.. and D6, are used for
• phase winding A ' it can be seen that if thyristors 1 and 4 are on, the winding draws current from the source 31; if thyristors 1 and 4 10. are both off, current in the winding A can be returned to the source 31 by way of a current path including diodes D Marina and D.. , the winding A and diodes D. and D living; if thyristor 1 is on, and thyristor 4 is off, current can free-wheel through a current path including 15. diodes D. and D R , and the thyristor 1.
• a single transistor 22 or 23 is all that is supplied for commutating three thyristors 1, 2 and 3 or 4, 5 and 6.
• FIGURE 6 shows a motor with a single phase winding, A connected across a di-v.v supply 32 in ' ,series ' with 20. top and bottom thyristors 1 and 4-.
• the circuit is very similar to that of FIGURE 5, except that there is only a single phase winding, and the commutating circuit is similar to that of FIGURE 2.
• a transistor 24 is used in a similar manner 25. to that described with reference to FIGURE 3 for commutating both thyristors 1 and - - in dependence upon whether a thyristor T ⁇ or a thyristor T ⁇ is. fired at the same time as the transistor is switched on.
• FIGURES 1-6, 30 may be "replaced by a combination of transistors in series and /or parallel connected to act in unison as a single transistor , for example, as shown in FIGURE 7.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Electric Motors In General (AREA)
• Rectifiers (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=10518800

Family Applications (1)

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• 1981
  • 1981-09-08 JP JP56502959A patent/JPS58501450A/ja active Pending
  • 1981-09-08 WO PCT/GB1981/000183 patent/WO1983000957A1/en not_active Application Discontinuation
  • 1981-09-08 EP EP81902630A patent/EP0087415A1/en not_active Withdrawn
• 1983
  • 1983-05-06 DK DK2043/83A patent/DK204383D0/da not_active Application Discontinuation

Non-Patent Citations (1)

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