| 摘要 |
1,230,564. Control of A.C. motors. ROLLSROYCE Ltd. 16 May, 1968 [19 May, 1967], No. 23372/67. Heading H2J. A two-phase induction motor 10 is supplied from an oscillator 11 which is connected to reference winding 13 through phase-shifter 16, and is connected to control winding 15 through unit 18 receiving direction and speed control signals 19, 20. A wave-squaring and frequencydoubling unit 17 produces an operating signal 21 for the unit 18 and a register 22. The latter comprises a number of flip-flops 25 receiving digits on data lines 27 from a computer 26 which is adapted to generate binary control numbers each defining a speed at which the motor is to operate. The control number is loaded into the computer by successive starting signals at predetermined intervals 28, the register being counted down by one digit per pulse of current supplied to the motor so that, when the register is at zero, the supply to the motor is stopped. If the control number is less than that corresponding to maximum speed, the motor is disconnected, after receiving a number of pulses, until the next starting signal occurs. The signal on each data line 27 is introduced to its associated flip-flop 25 through AND- gates 29, 30 which are enabled by the signal 28. This signal is further applied through a monostable device 31 whose output signal 28A is connected to the flip-flops for transferring the input signals to the outputs. The signal 28A is also connected through an inverter to the flip-flops which are thereby cleared at the beginning of the delay period of the monostable device. The outputs of the flip-flops 25 are connected through an OR-gate 32 and AND-gate 33 to provide the signal 20. The gate 33 has an input from flip-flop 34 so that a partial pulse is not included in the count-down of the register 22. The count-down commences when the signal 20 is connected to the first flip-flop 25 defining the least significant digit of the control number. The connection is made through OR-gate 36. The flip-flops 25 are interconnected through OR- gates 37 whereby a transition of the signal 20 reverses the output of the first flip-flop followed by similar action of the next flip-flop until the register is counted down to zero. The direction control signal 19 is connected to a flip-flop 40 associated with AND-gates 41, 42, which are enabled by the signal 20. A supply transformer 47 is connected to semi-conductor switches 45, 46, for energizing the motor reversibly. The motor may drive a fuel control valve for a gas turbine engine, the computer receiving a feedback signal representing the position of the valve which is set in accordance with a control number. The computer may also receive a feedback signal signifying the speed of the engine, Fig. 3 (not shown). |
