Rotation control apparatus and method and disk driving apparatus using the same

Patent metadata

Field	Value
Publication number	US-9329023-B2
Application number	US-201313773795-A
Country	US
Kind code	B2
Filing date	Feb 22, 2013
Priority date	Feb 22, 2012
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

A rotation control apparatus includes: a controller configured to supply test currents to a plurality of different paths of a motor when the motor is stopped; and a stop position detector configured to detect a rotational position of the motor based on an order of current values of the test currents. The controller causes one of the test currents to flow through one of the plurality of different paths, measure time taken until the corresponding detection voltage reaches a reference voltage, and set electrical conduction time of the test currents based on a result of the measurement.

First claim

What is claimed is:

1. A rotation control apparatus comprising:
a controller configured to supply test currents to a plurality of different paths of a motor including a stator having a plurality of coils and a magnetic rotor when the motor is stopped, the plurality of different paths including the plurality of coils; and
a stop position detector including:
an amplifier which has a selector which selectively outputs one of a plurality of output voltages as a select voltage based on the test currents, a current output amplifier which generates detection currents based on the select voltage and the test currents, and a current/voltage converter which converts the detection currents into detection voltages;
a sample/hold circuit receiving the detection voltages, and configured to hold the detection voltages;
a comparator which compares voltage values of the detection voltages held in the sample/hold circuit, and generate comparison signals for the plurality of paths, respectively, based on the comparison of the detection voltages and a reference voltage; and
a switch which is arranged between the comparator and the reference voltage, and makes an electrical connection and an electrical disconnection between an inverted input terminal of the comparator and the application terminal of the reference voltage,

the stop position detector determining an order of the detection voltages for the plurality of different paths and detecting a rotational position of the motor based on a combination of a path having a highest detection voltage and a path having a second-highest detection voltage in the order,
wherein the controller is further configured to supply one of the test currents to flow through one of the plurality of different paths, measure a time taken until the corresponding detection voltage reaches a reference voltage, and set an electrical conduction time of the test currents based on a result of the measurement.

2. The rotation control apparatus of claim 1 , wherein the reference voltage is set to a median value or its neighborhood value of an output range of the amplifier.

3. The rotation control apparatus of claim 2 , wherein input/output characteristics of the amplifier are changeable.

4. The rotation control apparatus of claim 1 , wherein the stop position detector further includes a table storing the order in association with the rotational position of the motor and detects the rotational position of the motor by referring to the table.

5. The rotation control apparatus of claim 1 , wherein, when the rotational position of the motor is detected when the motor is stopped, the controller supplies the test current, which is smaller than a current supplied to the path when the motor is being driven, to the path.

6. The rotation control apparatus of claim 1 , wherein, when the rotational position of the motor is detected when the motor is stopped, the controller supplies the test current to the path for a period of time which is shorter than a period of time for which a current is supplied to the path when the motor is being driven.

7. The rotation control apparatus of claim 1 , wherein the controller pre-charges the sample/hold circuit by supplying the test currents to the paths before measuring the test currents flowing through the plurality of paths.

8. The rotation control apparatus of claim 7 , wherein, upon pre-charging the sample/hold circuit, when the test current is flown, the controller measures time taken until the detection voltage reaches the reference voltage and sets the electrical conduction time of the test current based on a result of the measurement.

9. The rotation control apparatus of claim 1 , wherein, upon detecting the rotational position of the motor, when the test current is flown through a path first selected, the controller measures time taken until the detection voltage reaches the reference voltage and sets the electrical conduction time of the test current based on a result of the measurement.

10. The rotational control apparatus of claim 1 wherein:
the controller configured to supply test currents to at least three different paths of a motor including a stator having a plurality of coils and a magnetic rotor when the motor is stopped, the at least three different paths including the plurality of coils, and
the stop position detector is configured to convert the test currents flowing through the at least three different paths into the detection voltages for measurement, compare the voltage values of the detection voltages, determine an order of the detection voltages for the at least three different paths based on the comparison, and detect a rotational position of the motor based on the combination of the path having the highest detection voltage and the path having the second-highest detection voltage in the order.

11. A rotation control method comprising:
supplying test currents to a plurality of different paths of a motor including a stator having a plurality of coils and a magnetic rotor when the motor is stopped, the plurality of different paths including the plurality of coils;
selectively outputting one of a plurality of output voltages as a select voltage based on the test currents;
generating detection currents based on the select voltage and the test currents;
converting the detection currents into detection voltages;
making an electrical connection and an electrical disconnection between an inverted input terminal of the comparator and an application terminal of a reference voltage by a switch;
comparing voltage values of the detection voltages and determining an order of the detection voltages for the plurality of different paths based on the comparison;
detecting a rotational position of the motor based on a combination of a path having a highest detection voltage and a path having a second-highest detection voltage in the order; and
supplying one of the test currents to flow through one of the plurality of different paths, measuring a time taken until the corresponding detection voltage reaches the reference voltage, and setting electrical conduction time of the test currents based on a result of the measurement.

12. The rotation control method of claim 11 including:
supplying test currents to at least three different paths of a motor including a stator having a plurality of coils and a magnetic rotor when the motor is stopped, the at least three different paths including the plurality of coils;
selectively outputting one of a plurality of output voltages as a select voltage based on the test currents;
generating detection currents based on the select voltage and the test currents;
converting the detection currents into detection voltages;
making an electrical connection and an electrical disconnection between an inverted input terminal of the comparator and an application terminal of a reference voltage by a switch;
comparing voltage values of the detection voltages and determining an order of the detection voltages for the at least three different paths based on the comparison; and
detecting a rotational position of the motor based on a combination of the path having the highest current value and the path having the second-highest current value in the order.

13. A disk driving apparatus comprising:
a motor configured to rotate a disk, the motor including a stator having a plurality of coils and a magnetic rotor;
a rotation control apparatus configured to control rotation of the motor, the rotation control apparatus including:
a controller configured to test currents to a plurality of different paths of the motor when the motor is stopped, the plurality of different paths including th

Assignees

• Rohm Co Ltd

Inventors

• Kunida Yuji
• Maeda Norihiro

Classifications

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• H02P6/16

  Circuit arrangements for detecting position · CPC title

• H02P2205/01

  Current loop, i.e. comparison of the motor current with a current reference · CPC title

• G01B7/30 Primary

  for measuring angles or tapers; for testing the alignment of axes · CPC title

• H02P2203/11

  Determination or estimation of the rotor position or other motor parameters based on the analysis of high-frequency signals · CPC title