Electric traction systems and vehicles comprising such systems

Claim 2

Electric traction system comprising a separate excitation d.c. motor, an armature current control device, an excitation current control device, and between the motor armature and the d.c. supply source, several armature current switches (4-1...4-n) in parallel each made up of one or more transistors connected in parallel (30, 31, 32) characterized in that in order to avoid possible non-synchronization of the switches each switch is connected at one terminal to an induction coil (5-1...5-n) and in series with the armature of said motor, and at the other terminal with a diode (8-1...8-n) shunting said induction coil and armature of the motor.

Claim 3

Electric traction system according to claim 1 wherein each of the armature current switches in series to its respective resistor (7-1...7-4) characterized in that in order to provide a signal to open the switches when a voltage proportional to the armature current passing through the switches is too large and exceeds a predetermined value, the system includes diodes (21-1...21-n) having like terminals connected to a common point (28) where the voltage proportional to the armature current may be detected, and whose other terminals are branched each being connected to one of the armature current switches between the switch and its series resistance (7-1...or 7-n).

Claim 4

Electric traction system according to claim 2 characterized in that the excitation current control device comprises, on the one hand, at least a transistor (70) acting as the excitation current switch and a threshold system (72) which, connected its output (73) to the base of the transistor (70) controls the conduction of said transistor, in other words, the opening and closing of this excitation current switch, and, on tHe other hand, a unit comprising at least a saw-toothed pulse generator (76), an amplifier (77) of the voltage proportional to the armature current, taken from the common point (28) of the cathodes of the diodes (36, 37, 38) mounted below the armature current switches and an adder (78) whose two inputs (80 and 83) are respectively connected to the output (79) of said saw-toothed generator and to the junction point between the charge capacitance (82) and the output of said amplifier (77) and whose output (84) is connected to the input (74) of this threshold system (72).

Claim 5

Electric traction system according to claim 3, characterized in that it comprises in the control of the threshold system (72), on the one hand, a potentiometer (86) giving the threshold voltage and whose slide contact is connected through a diode (85) to the input (75) of a threshold system (72) and, on the other hand, a unit comprising a potentiometer (87) whose slide contact is controlled by an acceleration pedal (20) and connected through a diode (88) to the input (75) of the threshold system (72), a threshold system (89) feeding by its output (92) said potentiometer (87) as soon as a tachymetric element (91), connected to its input (10), displays a predetermined rotation condition of the armature (1) of the motor.

Claim 6

Electric traction system according to claim 3 provided with an energy recovery system during braking, characterized in that this energy recovery system comprises, on the one hand, a recovery diode (92) whose anode is connected to the negative pole of the current source (3) and the cathode is connected to the common point of the induction coils (5-1...5-n) and the terminal of the armature (1) of the motor and, on the other hand, a subassembly made up of a voltage comparator (93), a potentiometer (94) whose slide contact is connected to a brake pedal (95) and an input of this comparator (93), a connecting diode (97) whose anode is connected to another input of the comparator (93) and the cathode to the cathode of the recovery diode (92) and an amplifier (96) whose input is connected to the output of the comparator (93) and the output is connected to the input (83) of the adder (78) of the excitation current control device of the motor of the electric traction system.

Claim 7

Electric traction system according to claim 1 wherein (each of) the armature current switches has transistors (30, 31, 32) connected in parallel and each of said transistors is connected in series with its respective resistor characterized in that the system can detect a voltage proportional to the armature current through the transistors (30, 31, 32) to provide a signal to be used to render said transistors non-conducting when said proportional voltage exceeds a predetermined value, said system comprising diodes (36, 37, 38) having like terminals connected to a common point (28) at which the proportional voltage to the armature current can be detected and having their other terminals branched each connected to one of said transistors (30, 31, 32) between the transistor and its series resistor (33, 34, 35).

Claim 8

Electric traction system comprising a separate excitation d.c. motor, an armature current control device, an excitation current control device, and between the motor armature and the d.c. supply source, several armature current switches (4-1...4-n) in parallel each made up of one or more transistors connected in parallel (30, 31, 32) characterized in that the armature current control device comprises an electronic flip-flop (12) with two stable electric states controlling the transistor or transistors (39) for controlling the armature current switches (4-1...4-n) made up of transistors in parallel (30, 31, 32) and three pulse generators operating said electronic flip-flop (12), namely, a fixed frequency pulse generator (10) cyclically imposing the closing of the switches (4-1...4-n), a variable frequency pulse generator (9) controlling the opening, at will, of these switches, a Threshold pulse generator (11) causing the automatic opening of said switches protecting them against any predetermined overload.

Claim 9

Electric traction system comprising a separate excitation d.c. motor, an armature current control device, an excitation current control device, and between the motor armature and the d.c. supply source, several armature current switches (4-1...4-n) in parallel each made up of one or more transistors connected in parallel (30, 31, 32) characterized in that the armature current control device comprises an electronic flip-flop (12) with two stable electric states controlling the transistor or transistors (39) for controlling the armature current switches (4-1...4-n) made up of transistors in parallel (30, 31, 32) and three pulse generators operating said electronic flip-flop (12), namely, a fixed frequency pulse generator (10) cyclically imposing the closing of the switches (4-1...4-n), a variable frequency pulse generator (9) controlling the opening, at will, of these switches, a Threshold pulse generator (11) causing the automatic opening of said switches protecting them against any predetermined overload.

Claim 10

Electric traction system according to claim 7 wherein the variable frequency pulse generator (9) is provided with a unijunction transistor (44) and a capacitance (52) shunting the emitter (50) and the base (45) of this transistor and whose discharge through the emitter (50) base (45) region of this transistor gives a pulse at its output (21), the base (45) being connected to the negative pole of the current source (3), characterized in that the variable frequency pulse generator (9) comprises between the capacitance (52) - emitter (50) junction point of the unijunction transistor (44) and the positive pole of the current source (3), a potentiometer (19) variable by means of a pedal (20).

Claim 11

Electric traction system according to claim 7 wherein the variable frequency pulse generator (9) is provided with a unijunction transistor (44) and a capacitance (52) shunting the emitter (50) and the base (45) of this transistor and whose discharge through the emitter (50) - base (45) region gives a pulse at its output (21), the base (45) being connected to the negative pole of the current source (3), characterized in that this variable frequency pulse generator (9) comprises a transistor (53) whose collector and emitter shunting the capacitance (52) and the base is connected through a diode (54) to the terminal (23) of this generator (9) which is connected to the output (17) of the fixed frequency pulse generator (10).

Claim 12

Electric traction system according to claim 7 wherein the threshold pulse generator (11) is provided with a unijunction transistor (55) and a capacitance (61) shunting the emitter (60) and the base (56) of this transistor and whose charge is controlled by the potential of a terminal (26) connected to the output (15) of the electronic flip-flop (12) and whose discharge through the emitter (60) - base (56) region gives a pulse at its output (24), the base (56) being connected to the negative pole of the current source (3), characterized in that this threshold pulse generator comprises, on the one hand, a potentiometer (27) connected through a diode (65) to the junction point of the capacitance (61) and the emitter (60) of the unijunction transistor, and, on the other hand, a transistor (66) whose collector and emitter shunting the bases (56, 57) of the unijunction transistor (55) and whose base is connected to a terminal (25) connected to the common point (28) of the cathodes of the diodes (36, 37, 38) mounted below the armature current switches.