Patent GB-1166533-A (GB)
Title: Circuit Arrangements having Signal Summing Motors
IPC: H02P25/18
Filed: 1967-04-04
Abstract: 1,166,533. Adding and subtracting motors. WESTINGHOUSE AIR BRAKE CO. 4 April, 1967 [5 April, 1966], No. 15385/67. Heading G4G. [Also in Division H2] An induction signal summing motor 11 comprises an outer casing 12 carrying a stator winding 14 receiving multiphase A.C. energization of variable frequency (or alternatively D.C. energization) within which is a rotor 16 supported on bearings 17, 19 carrying a rotor winding 22, whereby the rotor 16 is rotated at a rate dependent on the frequency of stator energization. An inner winding 23 carried by the rotor 16 is energized over slip rings 15, 20, 25 and brushes 35, 36, 37 with variable multiphase A.C energization (or D.C. energization). Within rotor 16 is a further wound rotor 26 with output shaft 27 independently rotatable on bearings 28, 31, and if winding 23 is D.C. energized and winding 14 is A.C. energized, (or vice versa) rotor 16 will rotate with rotor 26 at a rotational speed proportional to the frequency of energization. If winding 14 and winding 23 are A.C. energized in phase coincidence, shaft 27 will rotate at a speed proportional to the frequency sum, and if energized in phase opposition, at a speed proportional to frequency difference. The shaft drives alternator 45 generating on leads 46, 47, 48 an A.C. whose frequency is proportional to the sum (or difference) of the input frequencies, or to the input frequency when one input is D.C. energized. Signal generating means 60 comprises first and second variable frequency multiphase A.C. sources 61, 80 and D.C. source 70, and signal selection control means 90 comprising a selector lever 91 movable through four positions to operate ganged switches 94, 95, 96, 97, which co-operate with relays 102, 103, DR and their associated banks of contacts, whereby in the first position the relay 102 is energized and relays 103, DR released so that windings 14, 23 of the motor are energized in phase coincidence, and the rotational speed of the shaft 27 represents the sum of the input frequencies. In the second position relay DR is energized and relays 102, 103 released so that winding 14 is D.C. energized from source 70 and winding 23 is energized from A.C. source 80, and the shaft rotational speed represents the frequency of this source. In the third position, switch 94 is disconnected to release relay DR, and winding 23 is D.C. energized while winding 14 is energized from A.C. source 61, so that the shaft speed represents its frequency. In the fourth position, relays DR and 102 are released and relay 103 is energized so that winding 14 is A.C. energized from source 61 ] and winding 23 is energized from source 80 with phase opposition, so that the rotational speed of shaft 27 represents the difference between the first and second input frequencies. In a modification (Fig. 2, not shown) a first A.C. multiphase variable frequency source energizes a stator winding within which is rotatable a rotor connected over a hollow shaft to a winding energizable over slip rings from a second A.C. multiphase variable frequency source. Within this winding a further rotor is rotatable integral with the output shaft, and the shaft rotational speed is made proportional as before to the sum of the input frequencies; the first and second respective input frequencies; or to the difference of the input frequencies. In a further modification (Fig. 3, not shown) wherein three A.C. multiphase variable frequency sources are used, individually replaceable with D.C. energization; a first source energizes a stator winding within which is rotatable a rotor which shaft drives a winding energized from a second source, within which is rotatable a rotor which shaft drives a winding energized from a third source, within which is rotatable a rotor driving an output shaft. The output shaft rotational speed may represent the algebraic sum of the three input frequencies, the difference between the algebraic sum of of two input frequencies and the third input frequency, or the three input frequencies in sequence; depending on phase connection and D.C. energization of the windings. A synchronous motor may replace an induction motor for signal summation and the apparatus is utilized in a vehicle propulsion rate of change control system as described in Specification 1,156,539, wherein one variable frequency input represents vehicle speed while another represents an incremental signal to be added or subtracted.