Optimal DC motor/controller configuration

An electronic controller for a direct current traction motor, comprising:

• an H-bridge circuit for controlling a field current of the motor, the H-bridge circuit including four legs arranged in opposite pairs of an upper leg and a lower leg in each pair, each leg including a plurality of parallel connected power field effect transistors arranged for connection in series with a field of the motor;
• a field gate electrode of the power field effect transistors in each said plurality being connected to a discrete common control line for switching each said plurality of field effect transistors in an on/off cycle of conduction through each said plurality of field effect transistors;
• and
• the discrete control lines are driven so that when the plurality of power field effect transistors of one of a first pair of the legs is switched on, the plurality of field effect transistors in an other of the first pair of legs is switched off, and, in the opposite pair of legs, the power field effect transistors in a leg diagonally opposite the one of the first pair are switched in a pulse width modulated on/off cycle of conduction to energize the field while the plurality of power field effect transistors in an other leg of the opposite pair of legs is switched in a synchronous-rectification on/off cycle of conduction to commute the field current.

A motor/controller configuration for a direct current traction motor wherein the motor is a separately excited motor, the combination comprising:

• an H-bridge circuit for controlling a field current of the motor, the H-bridge circuit including four legs arranged in opposite pairs of an upper leg and a lower leg in each pair, each leg comprising a plurality of parallel connected power field effect transistors arranged for connection in series with the field;
• a field gate electrode of the power field effect transistors in each said plurality being connected to a discrete common control line for switching each said plurality of field effect transistors in an on/off cycle of conduction through the field effect transistors;
• and
• the separately excited motor having a field which is wound so that a rated field current is obtained at a field voltage equal to a peak voltage output of a direct current power source for the motor divided by a ratio of a peak operating current to a rated operating current of the motor.

An electronic controller for a direct current series-wound traction motor, comprising:

• a half-bridge circuit for controlling an armature current of the motor, the half-bridge circuit including a first plurality of parallel connected power field effect transistors connected in series with the armature of the motor and a second plurality of parallel connected power field effect transistors connected in parallel with the armature of the motor;
• an H-bridge circuit for controlling a field current of the motor, the H-bridge circuit including four legs arranged in opposite pairs of an upper leg and a lower leg in each pair, each leg comprising a plurality of parallel connected field effect transistors arranged for connection in series with the field, a field gate electrode of the power field effect transistors in each said leg being connected to a discrete common control line for switching the field effect transistors in each said leg in an on/off cycle of conduction;
• and
• a logic circuit connected with each discrete common control line, the logic circuit controlling the switching of each plurality of power field effect transistors in the half-bridge circuit and the H-bridge circuit in accordance with a predefined algorithm.

An electronic controller for a direct current separately excited traction motor, comprising:

• a half-bridge circuit for controlling an armature current of the motor, the half-bridge circuit including a first plurality of parallel connected power field effect transistors connected in series with the armature of the motor and a second plurality of parallel connected power field effect transistors connected in parallel with the armature of the motor;
• an H-bridge circuit for controlling a field current of the motor, the H-bridge circuit including four legs arranged in opposite pairs of an upper leg and a lower leg in each pair, each leg comprising a plurality of parallel connected field effect transistors arranged for connection in series with the field, a field gate electrode of the power field effect transistors in each said leg being connected to a discrete common control line for switching the plurality of field effect transistors in each said leg in an on/off cycle of conduction;
• and
• a logic circuit connected with each discrete common control line, the logic circuit controlling the switching of each plurality of power field effect transistors in the half-bridge and the H-bridge in accordance with a predefined algorithm.

A direct current separately excited traction motor and an electronic controller for the separately excited traction motor comprising, in combination:

• a separately excited traction motor having an armature and a field winding, the field winding being so constructed that a rated field current is obtained at a field voltage equal to a peak voltage output of a direct current power source for the motor divided by a ratio of a peak operating current to a rated operating current of the motor;
• a half-bridge circuit for controlling an armature current of the motor, the half-bridge circuit including a first plurality of parallel connected power field effect transistors connected in series with the armature of the motor and a second plurality of parallel connected power field effect transistors connected in parallel with the armature of the motor;
• an H-bridge circuit for controlling a field current of the motor, the H-bridge circuit including four legs arranged in opposite pairs of an upper leg and a lower leg in each pair, each leg comprising a plurality of parallel connected field effect transistors arranged for connection in series with the field, a field gate electrode of the power field effect transistors in each said plurality of field effect transistors being connected to a discrete common control line for switching each said plurality of field effect transistors in an on/off cycle of conduction;
• and
• a logic circuit connected with each discrete common control line, the logic circuit controlling the switching of each plurality of power field effect transistors in the half-bridge and the H-bridge in accordance with a predefined algorithm.

A method for braking the momentum of a vehicle driven by a direct current traction motor, comprising the steps of:

• detecting a brake condition by monitoring the condition of an accelerator potentiometer and/or a direction of travel indicator for controlling the speed and direction of the motor, respectively;
• on detecting a brake condition, reading a throttle potentiometer to obtain a brake torque set point;
• computing an armature current set point by multiplying the throttle position value by a user defined brake response constant;
• applying a pulse width modulated signal to control a current flow to the armature;
• testing the armature current to ascertain if the armature current has exceeded the armature current set point;
• adjusting the pulse width modulated signal to adjust the armature current upward until the armature current exceeds the set point or the pulse with modulated signal attains a maximum value;
• when the pulse with modulated signal reaches a maximum value, increasing a field current of the motor until the field current reaches a predetermined maximum value;
• and
• executing a wait state until the armature current drops below a predefined critical limit indicating that the momentum has been arrested.