Control system to control the slip frequency of an asynchronous dynamo electric machine

Claim 2

Control system to control the slip frequency of an asynchronous dynamoelectric machine 20, said machine being adapted to be connected to a power bus 22 capable of supplying, or absorbing electrical energy at a controllable frequency (f1), said control system comprising: a bidirectional digital counter 34; 46, 47, 49, said counter having a forward count input v and a backward count input r; means 28 to generate a first pulse train of a pulse repetition rate being a function of said controllable frequency, and being connected to one of said inputS to apply the pulses of said first pulse train thereto; means to generate a second pulse train of a pulse repetition rate being a function of shaft speed n of the machine and being connected to the other of said inputs to apply the pulses of said second pulse train thereto; means 39 connected to one of said pulse generating means to control the repetition rate of one of said pulse trains to be additionally a function of the desired slip frequency; and means 33, 31, 28 connected to said counter and responsive to the count thereof controlling the frequency of said power bus.

Claim 3

System according to claim 1 wherein said means to control the frequency of said power bus includes means 33 deriving an analogue output proportional to the count of said counter 34 and means responsive to said analogue output and including an integrating amplifier 32, connected to said power bus and controlling the frequency thereof.

Claim 4

System according to claim 2 wherein said means responsive to said analogue output includes an oscillator 31 connected to said integrating amplifier, said oscillator having a frequency of oscillation c . f1 controlled by the output of said integrating amplifier, said oscillator controlling the frequency f1 at said power bus.

Claim 5

System according to claim 1 having means FIG. 2, 15: 39, 61 generating pulses of a repetition rate c . f2'' preset to be proportional to the desired slip frequency; and said means to control the pulse repetition rate of one of said pulse trains is effective to increase the PRR of said one pulse train as a function of the PRR (c . f2'') of the pulses derived from said pulse generating means.

Claim 6

System according to claim 4 wherein the pulse repetition rate of the pulses derived from said pulse generating means 39, 61 - c . f2'' changes substantially linearly during changeover of the dynamoelectric machine from motor to generator mode of operation.

Claim 7

System according to claim 4 wherein the pulse repetition rate c . f2'' of said pulse generating means for permitted operating conditions and slip frequencies of the machine, is preset to be always greater than zero.

Claim 8

x, wherein x is a whole integer of the series 1, 2, 3, ..... .

Claim 9

x, wherein x is a whole integer of the series 1, 2, 3, ..... .

Claim 10

System according to claim 1 wherein the pulse repetition rate PRR of the input not additionally a function of the desired slip frequency has its rate increased by a predetermined number of pulses per unit time c . fm.

Claim 11

System according to claim 5 wherein the PRR of the input not additionally a function of the desired slip frequency has its rate increased by a predetermined number of pulses per unit time c . fm, said number of pulses per unit time c . fm being equal to the number of pulses per unit time provided by said pulse generating means 39, 61 when set for a desired slip frequency of zero.

Claim 12

System according to claim 1 further including a coincidence gate FIG. 2, 50 connected to have said first pulse train and said second pulse train applied thereto, and having its output connected to said counter 46, 47, 49, said coincidence gate suppressing overlapping pulses FIGS. 2, 6, 7, 15.

Claim 13

System according to claim 1 wherein said control system operates at a pulse repetition rate increased by a predetermined factor c over the frequencies occurring in said machine.

Claim 14

System according to claim 10, said system controlling a 3-phase machine, wherein said predetermined factor is a factor of

Claim 15

System according to claim 1 including means providing pulses having a repetition rate which is a function of the pulse repetition rates of separate pulse trains, each applied to an input, said means comprising an adding network FIG. 1: 35; FIG. 2: 55, 56; FIGS. 4, 5 having one separate pulse train of a first repetition rate and a separate pulse train of a second repetition rate, per unit time, applied thereto, said adding network having an output having a pulse repetition rate in the same unit of time formed of the sum of the pulses of said first and said second pulse train per unit time.

Claim 16

System according to claim 12, wherein two adding stages 55, 56 are provided: a. one of said adding stages 55 having pulses of a repetition rate representative of the frequency appearing at said bus c . f1; b. pulses of a repetition rate representative of desired slip frequency c . f2 applied thereto; c. the other adder stage 56 having pulses c . fn representative of shaft speed n of the machine; and d. pulses of a repetition rate of a predetermined frequency c . fm corresponding to the PRR representative of desired slip frequency when the slip frequency is zero FIGS. 3 & 13, applied thereto the pulses J1 derived from the output of one adder stage 55 being applied 50-47-49 to the count input v of said counter 46 for counting in one direction, and the pulses J2 derived from the output of said other adder stage 56 being connected to the other input r of said counter for counting in the opposite direction FIGS. 2, 3, 11, and 12.

Claim 17

System according to claim 13 including a coincidence gate 50 connected to have output pulse trains J1, J2 of said adder stages 55, 56 applied thereto, said coincidence gate being connected to said counter and suppressing pulses from both said adder networks which arrive simultaneously.

Claim 18

System according to claim 1 including: a coincident pulse suppression gate FIG. 2: 50; FIGS. 6 & 7 interconnecting said pulse trains and said inputs v, r of the counter 34; 46, said gate 50 having a pulse train applied each to a respective input 53, 54; means extending in time, separately, the pulses derived from both said inputs 10, 12; logic means 99 having said pulses 10, 12 applied thereto and having an output signal 10 & 12 forming the logical conjunction of the presence of one of said signals only and indicative of no time-overlap of signals; a first monostable multivibrator 91 triggered by the output from said logic means and providing an output information signal 16 of a time duration longer than said input pulses; conjunctive gates 93, 94 having the trailing edges 13'', 14'' of said time-extended pulses, as well as the information signal 16 applied thereto; and an output multivibrator 95, 96 connected to be triggered by the output from said conjunctive gates 93, 94 to provide a pulse only when said first monostable multivibrator 91 has no pulse, and simultaneously the trailing edge of a time-extended pulse is present.

Claim 19

System according to claim 12 wherein said adding means add, continuously, pulses of a first pulse train and of a second pulse train, the number of pulses per unit time at the output of the adder corresponding to the total number of pulses, per unit time, of said first and second pulse trains, said network comprising logic means generating four signals: a. a first signal, being present when the negative conjunction of input signals corresponding to both said pulse trains is present; b. the second signal being present when the logical conjunction of the pulse trains of both input signals is present; c. a third signal when logical conjunction of presence of an input signal from the first pulse train and no input signal of the second pulse train is present; d. a fourth signal when the logical conjunction of an input signal of said second pulse train and absence of a signal from the first pulse train is present; and e. output generating means responsive to the trailing edges of said four signals FIGS. 4 and 5.

Claim 20

System according to claim 16, said output generating means including a monostable flip-flop having a pulse duration time tp being less by a predetermined desired value tmin than the pulse duration T of the input pulses applied to said adder network, said predetermined value corresponding to a desired minimum time gap between successive pulses from said adder network.

Claim 21

System according to claim 1, said counter having a predetermined number of counting stages and holding the maximum count in either direction, if a greater number of pulses is applied that stages are provided.

Claim 22

System according to claim 18, said counter having means sensing the highest counting stage holding a count and means blocking application of additional pulses for control of said counter when the highest counting stage has been reached.

Claim 23

System according to claim 1, said counter having an output terminal supplying a pulse when the count in the counter passes zero and means controlling said control means for the frequency at said power bus to reverse the polarity of an operating parameter within said control means upon change in count in said counter between negative and positive counts.

Claim 24

System according to claim 20 wherein said control means for the frequency at said power bus includes a digital digital-analogue converter, the pulse from said counter upon change between positive and negative regions of said counter controlling the polarity of the output of said digital-analogue converter.

Claim 25

System according to claim 1 wherein said power bus includes a controlled rectifier-type inverter having an AC output of said controllable frequency, and means supplying DC power to said controlled rectifier-type inverter.

Claim 26

System according to claim 1, further including control means to set a desired slip frequency.

Claim 27

System according to claim 23, wherein said control means to set the desired slip frequency includes settable operating means 39 and a pulse generator 38, 61 having an output frequency c . f 2 com determined by said operating means.

Claim 28

System according to claim 1 including a control loop interconnected with said control system and means deriving pulses representative of speed of said dynamoelectric machine; said control loop regulating the speed of operation of said machine in said system 42, 43.

Claim 29

Control system to control the slip frequency of an asynchronous dynamoelectric machine, which machine is adapted to be connected to a power bus capable of supplying, or absorbing electrical energy at a controllable frequency f1 said system comprising: first means 28 generating pulses at a count per unit time representative of, and controlling said controllable frequency; second means 24 generating pulses at a count per unit time representative of shaft speed n of the machine; third means 39, 38 generating pulses at a count per unit time representative of desired slip frequency cf2com; cf2''; means 35 adding the pulses per unit time of said desired slip frequency to the pulses generated in one of said first or second pulse generating means to derive a pulse train having a composite count per unit time of pulses; a bidirectional counter 34 having pulses of the other of said first or second pulse generating means, and said derived pulse train applied to input terminals to count pulses applied to said input terminals in opposite direction, whereby when the pulses applied to said input terminals alternate, the count in the counter will oscillate about the count of zero; and output means 32, 31 controlled by said counter and providing a control signal representative of the state of count therein to modify the count per unit time of the pulses of said first means, and thus the frequency of said controllable frequency.

Claim 30

Control system to control the slip frequency of an asynchronous dynamoelectric machine, which machine is adapted to be connected to a power bus capable of supplying, or absorbing electrical energy at a controllable frequency f1 said system comprising: first means 28 generating pulses at a count per unit time representative of, and controlling said controllable frequency; second means 24 generating pulses at a count per unit time representative of shaft speed n of the machine; third means 39, 38 generating pulses at a count per unit time representative of desired slip frequency cf2com; cf2''; means 35 adding the pulses per unit time of said desired slip frequency to the pulses generated in one of said first or second pulse generating means to derive a pulse train having a composite count per unit time of pulses; a bidirectional counter 34 having pulses of the other of said first or second pulse generating means, and said derived pulse train applied to input terminals to count pulses applied to said input terminals in opposite direction, whereby when the pulses applied to said input terminals alternate, the count in the counter will oscillate about the count of zero; and output means 32, 31 controlled by said counter and providing a control signal representative of the state of count therein to modify the count per unit time of the pulses of said first means, and thus the frequency of said controllable frequency.

Claim 31

System according to claim 26 wherein said adding means 35 is connected to said second and third means FIG. 1. 28 System according to claim 26 wherein said adding means is connected to said first and third means FIG. 2.

Claim 32

System according to claim 26 including means 64, 56 adding pulses of a predetermined count per unit time cfm To the pulses derived from said second means 24 to provide for smooth transition between motor and generator mode of operation.

Claim 33

System according to claim 26 further including a coincidence gate 50 having the output of the other of said first or second pulse generating means, and said derived pulses applied thereto, said coincidence gate suppressing pulses which have a time overlap to prevent simultaneous application of pulses tending to cause said bidirectional counter to count in opposite directions.

Claim 34

System according to claim 26 wherein said output means includes integrating means integrating the state of said counter over a period of time.

Claim 35

Method of controlling, by digital counts, the slip frequency of asynchronous machines comprising: deriving a first pulse train having a count per unit time representative of frequency of a power source, or sink, connected to said asynchronous machine; deriving a second pulse train cfn having a count per unit time representative of the speed of the machine; generating a third pulse train having a count per unit time representative of desired slip frequency (cf2com; cf2'') ; adding pulses of said third pulse train to one of said first or second pulse trains to obtain a composite pulse train; counting the pulses of the other of said first or second pulse trains in a first direction, and counting said composite pulse trains, in opposite algebraic direction to the first direction; storing a count representative of said number of pulses, whereby pulses of the other of said first or second pulse trains will set the counter to a value in one direction and a subsequent pulse from said composite pulse train will reset the counter in the opposite direction; deriving an output signal representative of the number of pulses stored at any time; and modifying the frequency of the power source, or sink by said output signal.

Claim 36

Method of controlling, by digital counts, the slip frequency of asynchronous machines comprising: deriving a first pulse train having a count per unit time representative of frequency of a power source, or sink, connected to said asynchronous machine; deriving a second pulse train cfn having a count per unit time representative of the speed of the machine; generating a third pulse train having a count per unit time representative of desired slip frequency (cf2com; cf2'') ; adding pulses of said third pulse train to one of said first or second pulse trains to obtain a composite pulse train; counting the pulses of the other of said first or second pulse trains in a first direction, and counting said composite pulse trains, in opposite algebraic direction to the first direction; storing a count representative of said number of pulses, whereby pulses of the other of said first or second pulse trains will set the counter to a value in one direction and a subsequent pulse from said composite pulse train will reset the counter in the opposite direction; deriving an output signal representative of the number of pulses stored at any time; and modifying the frequency of the power source, or sink by said output signal.

Claim 37

Method according to claim 32 including the step of generating a fourth pulse train of a predetermined count per unit time and adding said fourth pulse train cfm to the pulses of said second pulse train.

Claim 38

System according to claim 1 including: a coincident pulse suppression gate (FIG. 2: 50; FIGS. 6 & 7 interconnecting said pulse trains and said inputs v, r of the counter 34; 46, said gate 50 having a pulse train applied each to a respective input 53, 54; means extending in time, separately, the pulses derived from said inputs 10, 12; logic means 90 having said pulses 10, 12 applied thereto and having an output signal 10 & 12 forming the logical conjunction of the presence of one of said signals only and indicative of no time-overlap of signals; a first monostable multivibrator 91 triggered by the output from said logic means and providing an output information signal 16 of a time duration longer than said input pulses; conjunctive gates 93, 94 having the trailing edges 13'', 14'' of said time-extended pulses, as well as the information signal 16 applied thereto; and output pulse generating circuits 95, 96, connected each, to a conjunctive gate, said output pulse generating circuits being activated by said conjunctive gates to provide a pulse if and only if said first monostable multivibrator has no pulse, and simultaneously the trailing edge of a time-extended pulse is present.