Patent GB-417655-A (GB)
Title: Improvements in electro-mechanical power plant for locomotive vehicles
IPC: H02P9/00
Filed: 1933-03-31
Abstract: 417,655. Supply systems; control of D.C. motors. PESTARINI, G. M., 4, Tapton House Road, Sheffield. March 31, 1933, Nos. 9798/33 and 9307 /34. [Classes 35 and 38 (iv).] Equalizing load on generators ; boosting by dynamo - electric machines ; systems for transmitting mechanical power ; starting prime-movers ; exciting.-A dynamo DY driven from a prime mover or equivalent source of energy, supplies a load M1-M5 in series with the secondary armature of a " metadyne" transformer MT or a motor generator, the " primary " armature brushes P1, P2 of which are connected to a storage battery 2 and the " secondary " armature brushes S1, S2 are connected to a load M1, M2, M3, M4, M5, the excitation arrangements of the auxiliary machine being such that the current in the secondary circuit is maintained at a constant value which may be adjustable by hand or in accordance with other quantities. In the case of a motor load M1-M5, e.g. on a Diesel-electric vehicle, the motors and the generator may have a constant excitation so that the power output of the prime mover 1 driving the generator DY is maintained constant. In this case excess of load demand over the power available from the prime mover is supplied by the battery 2 and during regeneration, or when the power supply exceeds the load demand, the battery is charged. The motor may be connected in each of the leads to the " secondary " brushes of the auxiliary machine and the mid-point of the battery may be earthed. When the auxiliary machine is a motor generator, the excitation of that part which is in the load circuit includes a constant excitation opposed by excitation proportional to the load current, and preferably, a shunt field winding, Fig. 6, shows a " metadyne " type of arrangement in which three motors M1, M2, M3 are supplied from the generator DY in series with the " metadyne " transformer MT a controller C being provided giving three " forward " and three " reverse " positions for three settings of the power output of the prime mover. In this arrangement the motor excitation is obtained from an exciter EX excited by two windings 13, 14 one of which, 14, is energized by the voltage across the motors and the other 13 in series with the main exciting winding A of the generator DY, the coil of a relay GR controlling the governor setting of the prime mover, a " variator " winding 7 on the metadyne transformer for controlling the value of the motor current, and a resistance 16 through the controller C from across the battery 2. Thus, movement of the controller C to one of its three forward or reverse positions cuts out more or less of the resistance 16 and controls the ouput of the generator DY, the setting of the prime mover governor the load current and the motor excitation so as to obtain a new setting of power output. The winding 14 has the effect of reducing the motor torque as the motor speeds rise. Starting of the " metadyne " is controlled by switches 10, 11, a resistance 12 and a contactor C1 which interlocks a contact C1k in the circuit of the generator winding A to prevent excitation thereof until the " metadyne is running and the auxiliary machine may be used to start the prime mover. The load may be supplied from the battery alone by short circuiting the generator DY or the generator may only charge the battery 12 by shortcircuiting the 2 motors by a switch 20. As the motor torque is reduced with increase of the speed thereof the motor current may also be reduced as by means disclosed in Specification 404,739, [Group XXXVII], and the generator voltage increased to maintain the power output constant by exciting it in part by the voltage across the load or from an exciter coupled to the engine and the critical speed of which coincides with the desired speed of operation of the internal-combustion engine, or the generator may be excited from an exciter in series with a source of constant voltage the exciter being excited in part by a coil carrying the load current. In a modification, Fig. 9, the battery supplies only the peaks in the load, the generator being excited largely by the voltage across the load by a coil A and being arranged to saturate at a particular value of excitation so that below this value the generator supplies voltage in excess of the load voltage and thus charges the battery, but above this voltage the excess load is supplied by the battery. A polarized relay 26, 27 operates to open the generator field circuit during regeneration so that regenerative energy is supplied to the battery 2 only. In a further modification the internal-combustion engine is arranged to supply the whole of the power between certain upper and lower limits, the battery supplying or absorbing excess of energy. In this arrangement the generator field has a constant excitation and is also excited from a winding supplied from an exciter which is excited by two opposing fields, one constant, and one proportional to the load voltage the arrangement being such that when either field predominates the exciter is excited to saturation in one or other direction. The speed and power of the engine is varied according to the power required therefrom by additional known means.