Drive control circuit for three-phase brushless motor, motor-driven blower and electric vacuum cleaner

• US 20020185987A1
• Filed: 05/15/2002
• Published: 12/12/2002
• Est. Priority Date: 05/15/2001
• Status: Active Grant

• Current Assignee: Toshiba Tec Corporation (Toshiba Corporation)
• Original Assignee: Toshiba Tec Corporation (Toshiba Corporation)
• Inventors: Kushida, Hiroyuki, Takanose, Tsuyoshi
• Granted Patent: US 6,624,606 B2
• Time in Patent Office: Days
• US Class Current: 318/599
• CPC Class Codes: H02P 6/20 Arrangements for starting H02P6/08 takes precedence

Abstract

The present invention aims to first start the rotation of a rotor according to a first sequence for causing currents to flow in armature windings of three phases U, V and W upon startup of a three-phase brushless motor to thereby reduce an inrush current at the startup thereof, thus making it possible to lighten an electrical load on each electronic part used for control. Also the present invention aims to perform switching to an original second sequence for causing currents to flow in the armature windings of the two phases U and V, V and W or W and U of the three-phase brushless motor after the startup of the three-phase brushless motor to thereby provide a period for an open state of each terminal and make dead band control or the like unnecessary, thus making control of the three-phase brushless motor easier.

Claims

1. A drive control circuit of a three-phase brushless motor, comprising:

means which generates a pulse signal, based on a detected signal of rotational position detecting means detecting each rotational position of the three-phase brushless motor to thereby control an inverter circuit which drives the three-phase brushless motor;

memory which stores therein a first sequence for generating pulse signals for causing currents to flow in armature windings of three phases of the three-phase brushless motor, and a second sequence for generating pulse signals for causing currents to flow in the armature windings of the two phases of the three-phase brushless motor; and

startup sequence switching means which generates pulse signals according to the first sequence to control the inverter circuit when the three-phase brushless motor is started up, and thereafter performs switching to the second sequence to generate pulse signals to thereby control the inverter circuit.

2. The drive control circuit according to claim 1, wherein the sequence switching means performs switching between the first sequence and the second sequence during an interrupt process including a process for detecting each rotational position of the three-phase brushless motor.

3. The drive control circuit according to claim 2, wherein the process for detecting the rotational position of the three-phase brushless motor is carried out at a prestage of the interrupt process.

4. The drive control circuit according to claim 2, wherein the detected signal of the rotational position detecting means is triggered to execute the interrupt process.

5. The drive control circuit according to claim 1, wherein the pulse signals are PWM signals, and when the first sequence is switched to the second sequence, the sequence switching means satisfies a relationship of Da≧

Db in which duty Db of the PWM signal generated according to the second sequence is less than or equal to duty Da of the PWM signal generated according to the first sequence.

6. A motor-driven blower, comprising:

a three-phase brushless motor;

an air blower coupled to the three-phase brushless motor;

rotational position detecting means which detects each rotational position of the three-phase brushless motor;

a drive control circuit which generates each of pulse signals, based on a detected signal-obtained from the rotational position detecting means, the drive control circuit comprising;

memory which stores therein a first sequence for generating pulse signals for causing currents to flow in armature windings of three phases of the three-phase brushless motor, and a second sequence for generating pulse signals for causing currents to flow in the armature windings of the two phases of the three-phase brushless motor; and

startup sequence switching means which generates pulse signals according to the first sequence to control an inverter circuit when the three-phase brushless motor is started up, and thereafter performs switching to the second sequence to generate pulse signals thereby controlling the inverter circuit; and

the inverter circuit which drives the three-phase brushless motor based on the pulse signals.

7. The drive control circuit according to claim 6, wherein the sequence switching means performs switching between the first sequence and the second sequence during an interrupt process including a process for detecting each rotational position of the three-phase brushless motor.

8. The drive control circuit according to claim 7, wherein the process for detecting the rotational position of the three-phase brushless motor is carried out at a prestage of the interrupt process.

9. The drive control circuit according to claim 7, wherein the detected signal of the rotational position detecting means is triggered to execute the interrupt process.

10. The drive control circuit according to claim 6, wherein the pulse signals are PWM signals, and when the first sequence is switched to the second sequence, the sequence switching means satisfies a relationship of Da≧

Db in which duty Db of the PWM signal generated according to the second sequence is less than or equal to duty Da of the PWM signal generated according to the first sequence.

11. An electric vacuum cleaner, comprising:

a housing; and

a motor-driven motor held in the housing, comprising;

a three-phase brushless motor;

an air blower coupled to the three-phase brushless motor;

rotational position detecting means which detects each rotational position of the three-phase brushless motor;

a drive control circuit which generates each of pulse signals, based on a detected signal obtained from the rotational position detecting means, the drive control circuit comprising;

memory which stores therein a first sequence for generating pulse signals for causing currents to flow in armature windings of three phases of the three-phase brushless motor, and a second sequence for generating pulse signals for causing currents to flow in the armature windings of the two phases of the three-phase brushless motor; and

startup sequence switching means which generates pulse signals according to the first sequence to control an inverter circuit when the three-phase brushless motor is started up, and thereafter performs switching to the second sequence to generate pulse signals to thereby control the inverter circuit; and

the inverter circuit which drives the three-phase brushless motor based on the pulse signals.

12. The electric vacuum cleaner according to claim 11, wherein the drive control circuit switches the first sequence to the second sequence before the average number of revolutions of the motor-driven blower in each operation mode is reached.

13. The electric vacuum cleaner according to claim 11, wherein the drive control circuit switches the first sequence to the second sequence before average input power of the motor-driven blower in each operation mode is reached.