Abstract: A switched reluctance generator is controlled such that flux growth in a phase winding occurs at a faster rate during the initial part of the phase inductance cycle and at a second, slower rate during the subsequent part of the phase inductance cycle. The difference between flux growth and decay may be achieved either by applying different voltages during the two parts of the phase inductance cycle or by applying the same voltage over only part of the phase winding during the initial part of the phase inductance cycle and then applying that voltage across the phase winding thereafter. It is advantageous to make the increase in flux more rapid than its decay because minimizing the length of time that the flux is present while the phase inductance is rising will minimize the production of unwanted (motoring) torque.

Abstract: A control circuit for an inductive load, such as a phase winding of a reluctance motor, includes a boost flyback converter. The controller includes a dc link capacitor switchable across the load by means of a control switch and a suppressor switch for controlling the application of rectified current to the dc link capacitor. The suppressor switch is operated independently of the control switch in order to control the rectified current so that it follows the sinusoidal input voltage waveform. By this technique, the harmonics generated by switching the rectified input current are substantially suppressed.

Abstract: A switching circuit for a switched reluctance motor or generator comprises positive and negative power lines, a string of smoothing capacitors serially connected between them and two pairs of gate turn-off thyristors connected to either end of a phase winding of the motor or generator. Circulating diodes are connected between the ends of the winding and the opposite power line and further circulating diodes are connected between each pair of thyristors. A mid-point between the capacitors is connected between the further diodes. At switch-off one of the outer GTO's is first opened so that one of the diodes conducts and current in the winding is routed via the mid-point. Then the other outer GTO is opened so that current now circulates through both of the diodes and substantially no voltage is dropped across the winding. The first inner GTO is then opened causing one of the diodes to conduct. Thereafter the second inner GTO can be opened.

Abstract: A regenerative ac to dc convertor includes a thyristor bridge invertor and a rectifier having a dc link capacitor. A second capacitor is connected across the invertor. In a regenerative braking mode of the motor the invertor is arranged to return energy from the second capacitor to the ac supply. Circulating currents are inhibited by diodes connecting the dc link and second capacitor. A first diode is arrange to conduct from the positive terminal of the second capacitor to the positive terminal of the dc link capacitor. A second diode is arranged so that it conducts from the negative terminal of the dc link capacitor to the negative terminal of the second capacitor.

Abstract: Current derived from an indium arsenide current generating photodetector is determined accurately, despite the presence of a variable resistance between terminals of the photodetector and the photodetector having leads with appreciable resistance connected to the detector terminals. Two leads are connected to each detector terminal. The two leads connected to one of the detector terminals are respectively connected to an inverting input terminal of an operational amplifier and to one terminal of a feedback resistor of the amplifier; the other terminal of the feedback resistor is connected to the amplifier output terminal. The two leads connected to the other terminal of the photodetector are respectively connected to the operational amplifier non-inverting input terminal and to ground. The operational amplifier derives an output voltage that accurately represents the output current of the photodetector, independently of the photodetector resistance and the lead wire resistance.

Abstract: A multi-phase switched reluctance motor is driven from a tow-point d.v. supply (11) in which capacitors (12) and (13) are provided across the supply with their common point (14) constituting a third power supply point. The load windings W.sub.1, W.sub.3, W.sub.5 and W.sub.2, W.sub.4, W.sub.6 are connected in two different load circuits connected across the different capacitors. In order to prevent the voltage of the third point wandering because the currents in the the two load circuits are not the same, control means (21) can control the distribution of current between the various load windings by appropriate control of semi-conductor switches in the various load circuits.

Abstract: A multi-phase switched variable-reluctance motor having a number of phase windings (A, B, C) each connected in series with at least one main thyristor (1,2,3,4,5,6) across a D.C. supply (V.sub.5) has commutating means (23) responsive to the current in the different windings, the angular position of the rotor, the state of the main thyristors, the motor speed, and the desired operating condition, to control the firing and commutation of the main thyristors. Two modes of operation described in detail are a chopping mode in which chopping is controlled independently in two adjacent phases at the same time, and a single pulse mode with free-wheeling.

Abstract: A variable reluctance electric motor system includes a variable reluctance motor having a main winding for each phase and a power converter circuit including a main thyristor in series with each main winding connected across a direct voltage source from which the main windings are supplied sequentially with uni-directional current pulses, characterized by a commutating thyristor (16) for starving the main thyristor (12) of the current flowing through one main winding (11) while charging a capacitor unit (51,52) in one sense, and a commutating thyristor (26) for starving the main thyristor (22) of the next phase winding (21) of the current flowing through the next main winding (21) while charging the capacitor unit in the other sense.

Abstract: A variable reluctance motor control system has for each main phase winding (11) a power converter circuit including a main thyristor (12) across a D.V. source (50) and a commutating circuit including a capacitor (51,52) and a commutating thristor (16), arranged to resonantly reverse the charge on the capacitor in preparation for energizing the next main phase winding (21) by passing a current through the other main phase winding.

Abstract: A variable reluctance electric motor system including a variable reluctance motor having main windings (A,B,C,D) and auxiliary windings closely coupled to the main windings, a main storage battery for driving the motor terminals (10,11) (that will be referred to as DC supply terminals), and a power converter circuit (FIG. 2) for charging the battery from the DC supply, in which the motor is included in the power converter circuit to function as an isolating transformer to isolate the battery from the supply when on charge.

Abstract: In a variable reluctance electric drive system motor the fractions of a cycle during which the winding inductance of a phase increases with movement in either direction are such that the motor is self starting in either direction. The timing of the power converter in relation to the cycle of inductance is such that the current increases from its minimum value to substantially its maximum value while the winding inductance is substantially at its minimum value and thereafter substantially decreases before the power converter disconnects the winding from the supply. This can be achieved by making the switch-on and commutation of current occur at predetermined positions so related to the variation of inductance that the peak current ip at maximum power and maximum speed, is greater than I, where I=E/(R+dL/dt), E is the supply voltage, R the winding resistance and dL/dt is the maximum rate of increase of inductance before the commutation point.