Feedback field control for an electric vehicle

An electric vehicle comprising:

• a direct current drive motor;
• a separately excited field winding disposed within said direct current drive motor;
• throttle means for controlling the speed of said direct current drive motor;
• armature current feedback means connected to said direct current drive motor to provide a feedback signal proportional to the armature current flowing through said direct current drive motor;
• armature current reference means connected to said throttle providing an armature demand reference signal dependent on the position of said throttle;
• error amplifier means connected to said armature current feedback means and said armature current reference means for comparing the armature feedback signal and the armature demand reference signal and providing a field demand signal dependent on the difference between the feedback signal and the reference signal;
• field current output amplifier means connected to said error amplifier and said separately excited field winding providing current flow through said separately excited field winding in response to the error signal received from said error amplifier means;
• said direct current drive motor operable in a driving mode and a regenerative braking mode;
• a power supply connected to said direct current drive motor for supplying power when said direct current drive motor is operating in a driving mode and for receiving power when said direct current drive motor is operable in a regenerative braking mode;
• and,
• overvoltage regulating means connected to limit the power being supplied to said power supply when the voltage of said power supply exceeds a predetermined level.

An electric vehicle comprising:

• a direct current drive motor;
• a separately excited field winding disposed within said direct current drive motor;
• throttle means for controlling the speed of said direct current drive motor;
• armature current feedback means connected to said direct current drive motor to provide a feedback signal proportional to the armature current flowing through said direct current drive motor;
• armature current reference means connected to said throttle providing an armature demand reference signal dependent on the position of said throttle;
• error amplifier means connected to said armature current feedback means and said armature current reference means for comparing the armature feedback signal and the armature demand reference signal and providing a field demand signal dependent on the difference between the feedback signal and the reference signal;
• field current output amplifier means connected to said error amplifier and said separately excited field winding providing current flow through said separately excited field winding in response to the error signal received from said error amplifier means;
• said direct current drive motor operable in a driving mode and a regenerative braking mode;
• a power supply connected to said direct current drive motor for supplying power when said direct current drive motor is operating in a driving mode and for receiving power when said direct current drive motor is operating in a regenerative braking mode;
• and,
• under voltage regulating means connected to limit the power being supplied from said power supply when the voltage of said power supply falls below a predetermined value.

An electric vehicle comprising:

• a direct current drive motor;
• a separately excited field winding disposed within said direct current drive motor;
• throttle means for controlling the speed of said direct current drive motor;
• armature current feedback means connected to said direct current drive motor to provide a feedback signal proportional to the armature current flowing through said direct current drive motor;
• armature current reference means connected to said throttle providing an armature demand reference signal dependent on the position of said throttle;
• error amplifier means connected to said armature current feedback means and said armature current reference means for comparing the armature feedback signal and the armature demand reference signal and providing a field demand signal dependent on the difference between the feedback signal and the reference signal;
• field current output amplifier means connected to said error amplifier and said separately excited field winding providing current flow through said separately excited field winding in response to the error signal received from said error amplifier means;
• and,
• weak field regulating means connected to said armature current reference means for reducing the armature demand reference signal when the excitation of said separately excited field winding falls below a predetermined level.

An electric vehicle comprising:

• a direct current drive motor;
• a separately excited field winding disposed within said direct current drive motor;
• throttle means for controlling the speed of said direct current drive motor;
• armature current feedback means connected to said direct current drive motor to provide a feedback signal proportional to the armature current flowing through said direct current drive motor;
• armature current reference means connected to said throttle providing an armature demand reference signal dependent on the position of said throttle;
• error amplifier means connected to said armature current feedback means and said armature current reference means for comparing the armature feedback signal and the armature demand reference signal and providing a field demand signal dependent on the difference between the feedback signale and the reference signal;
• field current output amplifier means connected to said error amplifier and said separately excited field winding providing current flow through said separately excited field winding in response to the error signal received from said error amplifier means;
• said throttle means supplies an output signal to said armature current reference means which is proportional to the position of said throttle means;
• speed-dependent characteristic modifier means connected to said throttle means to shift the output signal of said throttle means as a function of the speed of said direct current drive motor.

An electric vehicle comprising:

• a direct current drive motor;
• a separately excited field winding disposed within said direct current drive motor;
• throttle means for controlling the speed of said direct current drive motor;
• armature current feedback means connected to said direct current drive motor to provide a feedback signal proportional to the armature current flowing through said direct current drive motor;
• armature current reference means connected to said throttle providing an armature demand reference signal dependent on the position of said throttle;
• error amplifier means connected to said armature current feedback means and said armature current reference means for comparing the armature feedback signal and the armature demand reference signal and providing a field demand signal dependent on the difference between the feedback signal and the reference signal;
• field current output amplifier means connected to said error amplifier and said separately excited field winding providing current flow through said separately excited field winding in response to the error signal received from said error amplifier means;
• a battery for supplying power to the electric vehicle;
• said field current output amplifier means uses pulsewidth modulation of the excitation voltage for supplying excitation to said separately excited field winding in response to the error signal received from said error amplifier means;
• and,
• minimum field excitation means connected to said field current output amplifier means causing said field current output amplifier to supply a minimum pulse-width excitation voltage wave for a some minimum field excitation.

An electric vehicle comprising:

• a direct current drive motor;
• a separately excited field winding disposed within said direct current drive motor;
• armature current feedback means connected to said direct current drive motor to provide a feedback signal proportional to the armature current flowing through said direct current drive motor;
• armature current reference means connected to said throttle providing an armature demand reference signal dependent on the position of said throttle;
• error amplifier means connected to said armature current feedback means and said armature current reference means for comparing the armature feedback signal and the armature demand reference signal and providing a field demand signal dependent on the difference between the feedback signal and the reference signal;
• field current output amplifier means connected to said error amplifier and said separately excited field winding providing current flow through said separately excited field winding in response to the error signal received from said error amplifier means;
• key means positionable in an on position, allowing power to be supplied to said direct current drive motor, and an off position, preventing power from being supplied to said direct current drive motor;
• and,
• idling means connected to said direct current drive motor for supplying power and field excitation to said direct current drive motor when said key means is on and the electric vehicle is stopped, to keep said direct current drive motor revolving at a predetermined idling speed.

A battery powered electric vehicle comprising:

• a direct current drive motor operable in a driving mode and a regenerative braking mode;
• a separately excited field winding disposed within said direct current drive motor;
• a power supply connected to said direct current drive motor for supplying power when said direct current drive motor is operating in a driving mode and for receiving power when said direct current drive motor is operable in a regenerative braking mode;
• overvoltage regulating means connected to limit the power being supplied to said power supply when the voltage of said power supply exceeds a predetermined level;
• a field current output amplifier means connected to said separately excited field winding to apply current to said separately excited field winding in response to a operator and vehicle operating parameter;
• and,
• field current compensating means connected to said field current output amplifier means to compensate the field current excitation for changing battery voltage.