Abstract: A voltage to current converter is provided for use with a current measuring device, said current measuring device being operable to provide an output voltage which is an analog of a current to be measured. The converter is arranged to provide an output current which is an analog of the current to be measured. The converter comprises an electronic controller, a switching amplifier and means for measuring the output current as an analog voltage and providing a measure of said analog voltage to the electronic controller.

Abstract: A voltage to current converter is provided for use with a current measuring device, said current measuring device being operable to provide an output voltage which is an analogue of a current to be measured. The converter is arranged to provide an output current which is an analogue of the current to be measured. The converter comprises an electronic controller, a switching amplifier and means for measuring the output current as an analogue voltage and providing a measure of said analogue voltage to the electronic controller.

Abstract: A control system is provided for use with an actuator in a load-positioning assembly. The actuator and its load are quickly and accurately driven to a target position using dual control modes. When the distance from the target position is large, a speed control mode is used. In this mode, the actuator is operated according to a speed demand profile which is a function of a programmable maximum speed and the distance remaining to the target position. When the distance to the target position is small, a stepping mode is selected for final positioning of the actuator and its load.

Abstract: A control system for and method of controlling a switched reluctance generator to maintain stable control of the generator in the continuous current mode. This is achieved by sensing the load on the generator, the speed of the rotor and the position of the rotor with respect to each phase winding in order to derive switching command signals to maintain the volt-seconds applied to the winding in each phase period so as to inhibit progressive flux growth in the phase windings by actuation of the controller switches.

Abstract: A control system for and method of controlling a switched reluctance generator to maintain stable control of the generator in the continuous current mode. This is achieved by sensing the load on the generator, the speed of the rotor and the position of the rotor with respect to each phase winding in order to derive switching command signals to maintain the volt-seconds applied to the winding in each phase period so as to inhibit progressive flux growth in the phase windings by actuation of the controller switches.

Abstract: A control system for and method for controlling a switched reluctance generator to maintain stable control of the generator in the continuous current mode. This is achieved by sensing the load on the generator, the speed of the rotor and the position of the rotor with respect to each phase winding in order to derive switching command signals to maintain the volt-seconds applied to the winding in each phase period so as to inhibit progressive flux growth in the phase windings by actuation of the controller switches.

Abstract: A sensorless rotor position measurement system comprises a digital processor (6) which receives signals from current and flux sensors (7, 8) of the current and flux associated with a phase winding of the machine. The measurement of the current and flux is enabled at a predicted reference rotor position. The measurements are compared with stored values of current and flux and an error between the actual and the predicted reference position calculated. The calculated rotor position can then be used to predict the instant the rotor will reach the next reference position.

Abstract: A portable microcomputer inventory system including a plurality of components and a support for supporting the components on an user as the user inventories items that have a bar code disposed thereon. The components include a microcomputer, a handheld bar code scanner for scanning the bar code on items to be inventoried, a visual display device carried on the user to display information relative to the item being inventoried, a keypad for accessing the computer and a rechargeable battery pac for supplying electrical power to the components of the inventory system.

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.