Motor control unit provided with anti-burning device

A power supply control device for preventing burning in a motor control apparatus, comprising:

• rotational detection means for detecting whether the rotational speed of a motor is below a predetermined value and for detecting when said motor fails to rotate;
• power supply limiting means for limiting current to said motor according to the rotational speed of said motor when the rotational speed is detected to be below said predetermined value by said rotational detection means;
• current supply means for charging a capacitor;
• discharging means for discharging said capacitor when the difference between the rotational speed detected by said rotational detection means and a capacitance load of said capacitor is greater than said predetermined value;
• cyclic power supply means for supplying current to said motor for a predetermined cycle before the rotation of said motor is re-initiated for automatically providing a cyclic power supply until said capacitance load exceeds said predetermined value responsive to said rotational detection means detecting that said motor has failed to rotate;
• and
• power supply discontinuing means for discontinuing current supplied from said cyclic power supply to said motor when said capacitance load of said capacitor exceeds said predetermined value;
• wherein said cyclic power supply means is arranged for supplying current to said motor at said predetermined cycle responsive to said rotational detection means detecting that said motor has failed to rotate and said power supply limiting means is arranged to limit the current to said motor in response to the rotational speed detected to be below said predetermined value.

A motor control apparatus for preventing burning, comprising:

• a motor having a magnet rotor and first and second exciting coils;
• and
• power supply control means including,
• rotational detection means for detecting whether the rotational speed of said motor is below a predetermined value and for detecting when said motor fails to rotate and for developing negative logical pulse signals having a cycle corresponding to the rotational cycle of said magnet rotor of said motor,
• power supply limiting means for limiting current to said motor according to the rotational speed of said motor when the rotational speed is detected to be below said predetermined value by said rotational detection means,
• current supply means for charging a capacitor,
• cyclic power supply means for supplying current to said motor for a predetermined cycle before the rotation of said motor is re-initiated for automatically providing a cyclic power supply until a capacitance load of said capacitor exceeds said predetermined value responsive to said rotational detection means detecting that said motor has failed to rotate,
• discharging means for discharging said capacitor when the difference between the rotational speed detected by said rotational detection means and said capacitance load of said capacitor is greater than said predetermined value, and
• power supply discontinuing means for discontinuing the current supplied from the power supply to said exciting coils of said motor when said capacitance load of said capacitor exceeds said predetermined value.