Suppressing phased motor voltage transients on disconnect

• US 7,994,747 B2
• Filed: 07/13/2007
• Issued: 08/09/2011
• Est. Priority Date: 07/13/2007
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Domingo, Frank P. Jr., Boling, Brian Dean, Dickeson, Michael Ernest
• Primary Examiner(s): Benson; Walter
• Assistant Examiner(s): Paul; Antony M
• Application Number:
  US11/777,897
• Publication Number:
  US 20090015186A1
• Time in Patent Office: 1,488 Days
• Field of Search: 318/400.01, 318/400.27, 318/430, 318/362, 318/507, 318/700, 318/400.36, 318/400.21, 318/400.22, 318/783, 324/765, 360/323, 361/23, 361/43, 361/56, 361/65, 361/199, 361/111, 257/479, 257/487, 257/603, 417/44.1, 323/276, 363/56.12
• US Class Current: 318/400.22
• CPC Class Codes: G11B 19/2054 Spindle motor power-up sequences
• CPC Class Codes: G11B 19/28 Speed controlling, regulating, or indicating G11B19/24 takes precedence
• CPC Class Codes: G11B 33/1493 Electro-Magnetic Interference [EMI] or Radio Frequency Interference [RFI] shielding; grounding of static charges

Abstract

A clamping circuit is included in a phased motor control circuit, particularly on an electrical connection connected to at least one electrostatic discharge cell and/or the driver control electronics of the phased motor control circuit. The clamping circuit triggers when a voltage that exceeds a clamping turn-on threshold occurs on the electrical connector, sourcing or sinking the discharge current so as to protect the electrostatic discharge cells and/or driver control electronics from destruction by said discharge current.

Claims

1. Motor control circuitry comprising:

at least one electrostatic discharge cell connected to an electrical connection that connect to a tap of a phased motor;

a clamping circuit connected to the at least one electrostatic discharge cell via the electrical connection, the clamping circuit having a turn-on threshold lower in magnitude than the turn-on thresholds of the at least one electrostatic discharge cell.

2. The motor control circuitry of claim 1 further comprising:

driver control electronics that control rotation of the phased motor and are coupled to the electrical connection, the driver control electronics having a breakdown threshold higher in magnitude than the turn-on threshold of the clamping circuit.

3. The motor control circuitry of claim 1 wherein the clamping circuit comprises:

a diode having a turn-on threshold lower in magnitude than the turn-on thresholds of the at least one electrostatic discharge cell.

4. The motor control circuitry of claim 1 wherein the clamping circuit comprises:

a transistor having a turn-on threshold lower in magnitude than the turn-on thresholds of the at least one electrostatic discharge cell.

5. The motor control circuitry of claim 1 wherein the clamping circuit comprises:

a transistor having a body diode with a turn-on threshold lower in magnitude than the turn-on thresholds of the at least one electrostatic discharge cell.

6. The motor control circuitry of claim 1 further comprising:

driver control electronics that control rotation of the phased motor and are coupled to the electrical connection, wherein a multiplicative product of anticipated discharge current and impedance of the clamping circuit is lower in magnitude than the lower of the turn-on thresholds of the at least one electrostatic discharge cell and a breakdown voltage of the driver control electronics.

7. The motor control circuitry of claim 1 wherein the clamping circuit carries discharge current from at least one winding of the phased motor if phase-current-induced flyback voltage on the electrical connection exceeds in magnitude the turn-on threshold of the clamping circuit.

8. The motor control circuitry of claim 1, wherein the tap is a center tap of the phased motor.

9. A method comprising:

connecting an electrical connection to a tap of a phased motor, the electrical connection being further connected to at least one electrostatic discharge cell and driver control electronics that control rotation of the phased motor;

rotating the phased motor via the driver control electronics;

discharging current generated by the rotating phased motor through a clamping circuit, the clamping circuit having a turn-on threshold lower in magnitude than the turn-on thresholds of the at least one electrostatic discharge cell.

10. The method of claim 9 further comprising:

connecting driver control electronics to the electrical connection, wherein the driver control electronics have a breakdown voltage higher in magnitude than the turn-on threshold of the clamping circuit.

11. The method of claim 9 wherein the clamping circuit includes a diode having a turn-on threshold lower in magnitude than the turn-on thresholds of the at least one electrostatic discharge cell.

12. The method of claim 9 wherein the clamping circuit comprises a transistor having a turn-on threshold lower in magnitude than the turn-on thresholds of the at least one electrostatic discharge cell.

13. The method of claim 9 wherein the clamping circuit comprises a transistor having a body diode with a turn-on threshold lower in magnitude than the turn-on thresholds of the at least one electrostatic discharge cell.

14. The method of claim 9 further comprising:

connecting driver control electronics to the electrical connection, wherein a multiplicative product of anticipated discharge current and impedance of the clamping circuit is lower in magnitude than the lower of the turn-on thresholds of the at least one electrostatic discharge cell and a breakdown voltage of the driver control electronics.

15. The method of claim 9 wherein the clamping circuit carries discharge current from at least one winding of the phased motor if phase-current-induced flyback voltage on the electrical connection exceeds in magnitude the turn-on threshold of the clamping circuit.

16. Motor control circuitry comprising:

driver control electronics that control rotation of a phased motor and are connected to an electrical connection adapted to connect to a tap of the phased motor;

a clamping circuit connected to the driver control electronics via the electrical connection, the clamping circuit having a turn-on threshold lower in magnitude than a breakdown voltage of the driver control electronics.

17. The motor control circuitry of claim 16 wherein the clamping circuit comprises:

a diode having a turn-on threshold lower in magnitude than the breakdown voltage of the driver control electronics.

18. The motor control circuitry of claim 16 wherein the clamping circuit comprises:

a transistor having a turn-on threshold lower in magnitude than the breakdown voltage of the driver control electronics.

19. The motor control circuitry of claim 16 wherein the clamping circuit comprises:

a transistor having a body diode with a turn-on threshold lower in magnitude than the breakdown voltage of the driver control electronics.

20. The motor control circuitry of claim 16 wherein a multiplicative product of anticipated discharge current and impedance of the clamping circuit is lower in magnitude than the breakdown voltage of the driver control electronics.

21. The motor control circuitry of claim 16 wherein the clamping circuit carries discharge current from at least one winding of the phased motor if a phase-current-induced flyback voltage on the electrical connection exceeds in magnitude the turn-on threshold of the clamping circuit.