Motor drive apparatus, integrated circuit, and motor drive method

• US 20050168181A1
• Filed: 01/28/2005
• Published: 08/04/2005
• Est. Priority Date: 01/29/2004
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Morita, Hirotaka, Okumura, Takekiyo
• Granted Patent: US 7,053,573 B2
• Time in Patent Office: Days
• US Class Current: 318/268
• CPC Class Codes: H02P 6/17 and for generating speed information

Abstract

A motor drive apparatus which drives a motor by controlling conduction/non-conduction of a drive transistor for causing a current to flow through a drive coil of the motor based on a pulse signal indicating a relative position between the rotor and stator of the motor, generated by a position detector, and on a rotation speed setting voltage for setting the rotation speed of the motor. The apparatus comprises a control circuit that generates a pulse-delayed signal by delaying the pulse signal by delay time according to the voltage level of the rotation speed setting voltage.

Claims

1. A motor drive apparatus which drives a motor by controlling conduction/non-conduction of a drive transistor for causing a current to flow through a drive coil of the motor based on a pulse signal indicating a relative position between the rotor and stator of the motor, generated by a position detector, and on a rotation speed setting voltage for setting the rotation speed of the motor, the apparatus comprising:

a control circuit that generates a pulse-delayed signal by delaying the pulse signal by delay time according to the voltage level of the rotation speed setting voltage.

2. The motor drive apparatus according to claim 1, wherein the control circuit generates the pulse-delayed signal by delaying the pulse signal by delay time proportional to the voltage level of the rotation speed setting voltage.

3. The motor drive apparatus according to claim 1, wherein the control circuit comprises:

a capacitor that is charged and discharged;

a charge/discharge reference voltage generation circuit that generates two different charge/discharge reference voltages based on the rotation speed setting voltage and a predetermined voltage;

a charge/discharge circuit that switches charge/discharge of the capacitor at edge timings of the pulse signal, and charges and discharges the capacitor within a voltage range between the two charge/discharge reference voltages; and

a comparator that compares the charge/discharge voltage of the capacitor with a comparison reference voltage in between the two charge/discharge reference voltages,

wherein the pulse-delayed signal is generated based on the comparing result of the comparator.

4. The motor drive apparatus according to claim 3, wherein in the control circuit the comparator generates the pulse-delayed signal by delaying the pulse signal by delay time that the charge/discharge voltage, starting from one of the two charge/discharge reference voltages, takes to reach the comparison reference voltage.

5. The motor drive apparatus according to claim 3, wherein the charge/discharge reference voltage generation circuit comprises a limiter circuit that limits one, generated based on the rotation speed setting voltage, of the two charge/discharge reference voltages so as to be at or below a predetermined upper limit voltage, or to be at or above a predetermined lower limit voltage.

6. The motor drive apparatus according to claim 5, wherein the charge/discharge reference voltage generation circuit comprises a series resistor having a first voltage supplied to one terminal thereof and a second voltage lower than the first voltage supplied to the other terminal thereof,

wherein the voltage of a first connection of the series resistor is a higher one of the two charge/discharge reference voltages,

wherein the voltage of a second connection of the series resistor is a limit for a lower one of the two charge/discharge reference voltages, the second connection being at the second voltage side, and

wherein the rotation speed setting voltage limited to be at or below the limit by the limiter circuit is the lower one of the two charge/discharge reference voltages.

7. The motor drive apparatus according to claim 5, wherein the charge/discharge reference voltage generation circuit comprises a series resistor having a first voltage supplied to one terminal thereof and a second voltage lower than the first voltage supplied to the other terminal thereof,

wherein the voltage of a first connection of the series resistor is a limit for a higher one of the two charge/discharge reference voltages,

wherein the voltage of a second connection of the series resistor is a lower one of the two charge/discharge reference voltages, the second connection being at the second voltage side, and

wherein the rotation speed setting voltage limited to be at or above the limit by the limiter circuit is the higher one of the two charge/discharge reference voltages.

8. The motor drive apparatus according to claim 6, wherein the series resistor is made up of resistors having the same characteristic.

9. The motor drive apparatus according to claim 7, wherein the series resistor is made up of resistors having the same characteristic.

10. The motor drive apparatus according to claim 3, wherein the comparison reference voltage is a voltage of a predetermined connection of a series resistor having the rotation speed setting voltage supplied to one terminal thereof and the predetermined voltage supplied to the other terminal thereof.

11. The motor drive apparatus according to claim 10, wherein the series resistor is made up of resistors having the same characteristic.

12. The motor drive apparatus according to claim 3, wherein when the motor is a three-phase motor, the control circuit has the capacitor, the charge/discharge circuit, and the comparator which are provided for each phase, and the charge/discharge reference voltage generation circuit is shared between the phases.

13. The motor drive apparatus according to claim 1, which is configured as an integrated circuit.

14. A motor drive method for a motor drive apparatus which drives a motor by controlling conduction/non-conduction of a drive transistor for causing a current to flow through a drive coil of the motor based on a pulse signal indicating a relative position between the rotor and stator of the motor, generated by a position detector, and on a rotation speed setting voltage for setting the rotation speed of the motor, the method comprising:

generating a pulse-delayed signal by delaying the pulse signal by delay time according to the voltage level of the rotation speed setting voltage.