Integrated drive system

Claim 1

An electronic control system adapted to control at least two mechanically coupled DC motors whose input is connected to an AC source and whose output is comprising control means connected for electrically controlling a semiconductive switching logic means and a motor speed logic means, a reference circuit means connected to said switching logic means and said motor speed logic means, said reference circuit means connected to a variable DC voltage generating means adapted to apply a variable DC voltage to said motors, said variable DC voltage generator means is further provided armature bridge means connected between said amplifier means and said DC motors, there being an armature bridge means for each of said motors, said armature bridge being adapted to provide a variable DC output voltage to said armatures, there being one trigger generator whose output is connected to each of said amplifier means whereby substantially equal armature voltages are maintained in said armatures in each of said motors, said variable DC voltage generating means being also provided with current sensing means connected between said armature bridge means and said armatures adapted to generate a signal representative of the current flowing to each of said armatures, and a load sharing means connected between said current sensing means adapted to maintain prescribed loading between each of said DC motors, said load sharing means is provided with load sharing circuit means which is connected between said current sensing means and a field trigger generator, said field trigger generator being connected to the output of a field bridge, the output of said field bridge being connected to the field windings of said DC motors, said reference circuit means adapted to combine a signal directly representative of the counter EMF in the armatures in said motors, a reference voltage signal as generated by said motor speed logic means, and a signal representative of the current in said armatures, to generate an error signal representative of said motor''s actual speed and output torque with respect to a reference speed and output torque, said variable DC voltage generating means further includes a trigger generator whose input is connected to said reference circuit means and said output is connected to said armatures of saiD DC motors, said trigger generator being adapted to generate a variable width pulse synchronized with the frequency of said AC source, said variable DC voltage generator means is further provided with amplifier means connected between said trigger generator and said motors and adapted to amplify said variable width pulses, said signals generated by said current sensing means are inputted to said load sharing circuit means, said load sharing means being adapted to compare any differences between said signals and generate a signal representative of any such differences the generated signal inputted to said field trigger generator to in turn vary the DC output voltage of said field bridge to maintain a predetermined load sharing level between each of said DC motors, there being one field trigger generator and one field bridge for each DC motor in said system, there being only one load sharing circuit means it being connected to each of said field trigger generators, said variable DC voltage generating means includes a constant torque braking means switchably connected across said armature, said constant torque braking means includes braking resistors adapted to be switchably connected by a contacting means, across said armature to dissipate, at a constant rate, the current flowing in said armature by the generator action of said motors during the braking cycle, said braking resistors generate a signal during the braking cycle representative of the voltage in said armature, said signal being inputted to said field trigger generators to maintain voltage generated during the braking cycle substantially constant.