Circuit and method to avoid high current spikes in stator windings

A circuit for driving current through the stator coils in a brushless dc motor comprising:

• comparator means for comparing an input voltage to a feedback voltage and having an output;
• means connected to the output of said comparator means for integrating the output of said comparator;
• stator coil drive circuit for driving the stator in response to the integrated output of the comparator;
• and
• switching means connected between the outout of said comparator means and said stator coil drive circuit for selectively enabling and disabling the stator coil drive circuit;
• and
• conducting means for discharging said integration means when said switching means has disabled said stator coil.

A method for minimizing current spikes in the stator windings of a brushless dc motor when the stator coils are switched comprising the steps of:

• comparing an input voltage to a feedback voltage,
• integrating the output of said comparison with an integration circuit,
• driving a stator coil in response to the integrated output of the comparator,
• enabling and disabling the stator coil circuit;
• and
• discharging said integration circuit when said stator coil is disabled.

A brushless, polyphase, direct-current motor having a rotor and stator coils, and a commutation circuit for providing sequencing signals, and stator coil driver circuit for minimizing current spikes through the stator coils, comprising:

• comparator means for comparing an input voltage to a feedback voltage and having an output;
• integration means connected to the output of said comparator means for integrating the output of said comparator;
• stator coil drive circuit for driving the stator in response to the integrated output of the comparator;
• switching means connected between the output of said comparator means and said stator coil drive circuit for selectively enabling and disabling the stator coil drive circuit;
• and,
• discharging means for discharging said integration means when stator coil drive circuit is disabled.