United States Patent [19] Shinkawa et al.

US005780983A

5,780,983 Jul. 14, 1998

[11] Patent Number:

[45] Date of Patent:

[54] BRUSHLESS DC MOTOR DRIVE APPARATUS

[75] Inventors: Osamu Shinkawa; Akihito Uetake. both of Suwa. Japan

[73] Assignee: Seiko Epson Corporation. Tokyo. Japan

[21] Appl. No.: 623,347

[22] Filed: Mar. 27, 1996

[30] Foreign Application Priority Data

Man 15, 1994 [JP] Japan .................................... .. 6-44142 Mar. 31, 1995 [JP] Japan .. ..... .. 7-076711.

Jan. 10, 1996 [JP] Japan .................................. .. 8-002690

[51] Int. (:1.6 ...................................................... .. A02P 6/02

[52] U.S.Cl. ......................... .. 318/254;318/138; 318/439

[58] Field of Search ................................... .. 318/254. 138. 318/439

[56] References Cited

U.S. PATENT DOCUMENTS

4,700,116 10/1987 4,712,050 12/1987 4,743,815 5/1988 4,928,043 5/1990 5,367,234 11/1994 5,486,743 l/ 1996 5,491 ,393 2/1996

OTHER PUBLICATIONS

“Wide Speed Control of Interior Permanent Magnet Syn chronous Motor” Shigeo Morimoto. et al.. lEE Japan. vol. l14-D. No. 6. 1994. (partial translation).

Primary Examiner-David S. Martin

Attorney, Agent, or Firm—Mark P. Watson

[57] ABSTRACT

A brushless DC motor drive apparatus according to the invention comprises a stator and a rotor, the stator including multi-phase armature windings which are connected in a star formation and generate a plurality of terminal voltages at respective terminals of the armature windings. and the rotor including a plurality of permanent magnets which form pairs of magnetic poles. The motor drive apparatus also includes an inverter coupled to the rotor for adjusting the speed of the rotor, a rotor position detection means for detecting the terminal voltages generated in the armature windings and for generating a position signal indicative of a magnetic pole position of the rotor. The rotor position detection means includes a line voltage generation means for generating line voltages corresponding to the terminal voltages of the arma ture windings and comparison means for comparing signals derived from the line voltages in predetermined combina tions and outputting comparison signals as the positional signal. The motor drive apparatus also includes a drive control means for controlling and driving the inverter according to the position signal generated by the rotor position detection means. the drive control means including PWM (Pulse Width Modulation) chopper control means for generating a PWM chopper control signal to control the inverter. The motor drive apparatus according to the present invention can always detect accurate rotor position without being affected by the rotational frequency or load of the brushless DC motor. Furthermore. the motor drive apparatus can easily expand the operational range of a brushless DC motor. particularly that of a brushless DC motor possessing an embedded magnet-type rotor structure. Additionally. the motor drive apparatus can easily and accurately operate a brushless DC motor according to its motor characteristics and control method.

24 Claims, 26 Drawing Sheets

80a

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US. Patent Jul. 14, 1998 Sheet 1 0f 26 5,780,983

-[>|- INVERTER

A

f7 f- 8

INVERTER DRIVE CIRCUIT

I KTQ v (‘5 OUTPUT RoToR PATTERN POSITION

GENERATION T DETECTION CIRCUIT MEANS

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11 — CONTROL

CIRCUIT

FIG._ 1 (PRIOR ART)

32 k

22

FIG. _2 (PRIOR ART)

US. Patent Jul. 14, 1998 Sheet 2 of 26 5,780,983

FIG._4 FIG._3

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30

LEAD ANGLE (deg)

3.5 2.5 m

US. Patent Jul. 14, 1998 Sheet 3 of 26 5,780,983

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US. Patent Jul. 14, 1998 Sheet 5 0f 26 5,780,983

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US. Patent Jul. 14, 1998 Sheet 6 of 26 5,780,983

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US. Patent Jul. 14, 1998 Sheet 8 of 26 5,780,983

Vv-w (GAIN)

FIG._ 14

APPLICATION VOLTAGE

DETERMINATION MEANS

U.S. Patent Jul. 14, 1998 Sheet 9 0f 26 5,780,983

FIG._ 16 FIG._ 15

s4

s3

S2

S1

TORQUE 2 _ N-m

10000 9000 7000 8000

REVOLUTION SPEED 6000

(mm)

FIG._ 17

US. Patent Jul. 14, 1998 Sheet 10 of 26 5,780,983

FIG._ 18 9° ' ' '

MOTOR EFFICIENCY 88 _

("/o) _ E1 _

s7 — -

86 I I l

20 30 4o

LEAD ANGLE (deg)

FIG._ 19

INVERTER EFFICIENCY

(%)

95.4 I | I

20 30 4O LEAD ANGLE

(deg)

U.S. Patent Jul. 14, 1998 Sheet 11 0f 26 5,780,983

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U.S. Patent Jul. 14, 1993 Sheet 13 0f 26 5,780,983

TORQUE 2 _ N-m

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REVOLUTION SPEED FIG._24 (rpm)

S3 S2 S2 OPEN PHASE MODE

L L L Wps- 5

L L H Vps+ 4

L H L Ups- 3

L H H Wps+ 2

H L L Vps- 1

H L H Ups+ 0

FIG._28

US. Patent Jul. 14, 1998 Sheet 14 0f 26 5,780,983

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FIG. _25

US. Patent Jul. 14, 1998 Sheet 16 of 26 5,780,983

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US. Patent Jul. 14, 1998 Sheet 17 of 26 5,780,983

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US. Patent Jul. 14, 1998 Sheet 13 0f 26 5,780,983

S101\ MEASURE REVOLUTION SPEED FROM DETECTION SIGNAL P4

S102\ l SELECT PHASE SHIFT

BY REFERENCING TABLE BASED ON REVOLUTION SPEED

AND MOTOR CURRENT

S103\ I SET TIMER TIME

S104\ I. TIMER COUNT

IS TIME UP

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OUTPUT COMMUTATION

SIGNAL

FIG._30

US. Patent Jul. 14, 1998 Sheet 19 of 26 5,780,983

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