Patent GB-1462674-A (GB)
Title: Method and arrangement for the control of a rotor load angle  of a converter machine of synchronous construction
IPC: H02P25/024
Filed: 1974-04-03
Abstract: 1462674 Control of A.C. motors LICENTIA PATENT-VERWALTUNGS GmbH 3 April 1974 [4 April 1973] 14833/74 Heading H2J A synchronous machine 9 has its three phase stator windings supplied from a thyristor converter 5 connected through a rectifier to an A.C. supply U.V.W., the rotor load angle for four quadrant operation of the machine (i.e. motor or generator, forward or reverse) being controlled by a circuit 35 to which are fed the signals a, #, γ and 8 produced by a detector 10 rotatable with the shaft 34 of the machine, the signals α, #, γ being of static coarse track type representative of rotor position and the signal 8 being of dynamic fine track type representative of rotor speed, and the circuit 35 including a logic unit 3 producing for the converter 5 release signals a-f corresponding to 120‹ electrical ignition ranges staggered by 60‹ electrical with respect to each other, a rotary angle logic unit 1 producing signals SMα#γ, SGα#γ (M-motor operation, G-generator operation) corresponding to ranges displaced with respect to those of the signals α#γ by an angle dependent on the signal #, and a gate logic unit 2 which produces signals ABC determining the signals a-f and being determined by the ranges of signals α#γ for low speeds of the machine and by the ranges of signals SMα#γ, SGα#γ for higher machine speeds, the unit 1 consisting of six logic modules (11-16), Figure 2 (not shown) respectively producing the signals SMα, SGα, SM#, SG#, SMγ and SGγ, the module (11) being shown in Figure 3 and comprising monostable stages 110, 111 receiving the signal α (or α for reverse rotation of machine), summing and monostable stages 113, 114 producing signals ZRα defining the range of signal a, Figures 4b and c (not shown), a counter 115 receiving the signals # and ZRα and supplying its count ZQαmM, Fig. 4d (not shown) to a comparator 116 also receiving from synchronizer 117 a signal SQαmM, Fig. 4e (not shown) representative of a preselected rotor load angle VQmM, and a store 118 receiving the outputs of stages 110, 111, signal α and the output signal of comparator 116, the latter output signal IMα, Fig. 4f (not shown) occurring each time the count in counter 115 equals the signal SQαmM and the store 118 producing the signal SMα, Fig. 4g (not shown) whose range is defined by the signals IMα and phase displaced from the range of signal α by an angle #α. If signal SQαmM exceeds the count produced by the counter 115 in its period defined by signals ZRα, the signal IMα does not appear and the store 118 is switched by the output signals Tαe, Tαa of stages 110, 111 to provide open-loop limiting control. The circuit 35 also includes first and second angle of rotation signal inverters 30, 31, a direction of rotation senser 32, an open loop or closed loop control 33 whose controls are superimposed on the rotor angle open loop control, a member 8 whose output signal indicates whether motor (M) or generator (M) drive is present, a stage 7 producing preselected values VQM, VQG of rotor load angle and a member 6 emitting trigger or blocking signals N, N according to the speed of the machine. The unit 1 may be simplified, Fig. 5 (not shown) by using three modules (17, 18, 19) having common members 112, 115, 116, 117, selector elements (120) receiving a signal α#γ from a different phase and a common summing element (119). Detector 10 may be of magnetic, optical, Hall-effect, capacitive or phototransistor type. It is adjusted, at standstill, for a load angle such that the machine 9 operates in a capacitive manner (for reasons of commutation of the converter 5), the required lag or load of the stator flux with machine speed variations being provided by variation of the displacement angle #α between the signals α and SMα.