Electronically commutated DC motor

• US 6,456,024 B1
• Filed: 11/27/2000
• Issued: 09/24/2002
• Est. Priority Date: 11/27/1999
• Status: Expired due to Fees

• Current Assignee: Ebm-Papst St Georgen GmbH & Company KG (Ebm-Papst Mulfingen GmbH & Company KG)
• Original Assignee: Papst-Motoren GmbH & Company KG (Ebm-Papst Mulfingen GmbH & Company KG)
• Inventors: Lukenich, Stefan, Schmider, Fritz
• Primary Examiner(s): Dang, Khanh
• Application Number:
  US09/722,181
• Time in Patent Office: 666 Days
• Field of Search: 318/138, 318/254, 318/439, 318/801, 363/17, 363/41, 363/132, 363/133, 310/63, 310/156.12, 417/423.7
• US Class Current: 318/400.29
• CPC Class Codes: F04D 25/0653 the motor having a plane air gap, e.g. disc-type
• CPC Class Codes: H02K 29/03 with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
• CPC Class Codes: H02K 29/12 using detecting coils using the machine windings as detecting coil
• CPC Class Codes: H02P 6/085 in a bridge configuration
• CPC Class Codes: H02P 6/22 in a selected direction of rotation

Abstract

An electronically commutated direct-current motor has a permanent-magnet rotor (19), a stator (2) that has at least one drive winding (25), and an H-bridge circuit (52) in which two bridge elements are configured as transistors (54, 56) and the other two bridge elements as resistors (58, 60), the drive winding (25) being arranged on the diagonal of said H-bridge circuit (52); and it has a commutation circuit for alternate activation and deactivation of the two transistors (54, 56) of the H-bridge circuit (52). The motor operates quietly and with unusual reliability, and is well adapted for driving a fan.

Claims

1. An electronically commutated direct-current motor comprising a first lead for connection to one of the polarities of a direct current source, and a second lead for connection to the other of said polarities, further comprising:

a permanent magnet rotor;

a stator associated with said rotor and comprising at least one drive winding having two terminals;

a commutation circuit comprising an H-bridge circuit having bridge elements for controlling current flow in said at least one drive winding,

two of said bridge elements being configured as transistors, one transistor being arranged in a current path from said one winding terminal and one of said leads, the other transistor being arranged in a current path from said other winding terminal and said one of said leads,

each transistor serving for controlling the connection between an associated one of said winding terminals and one of said leads,

said transistors being adapted to be activated and deactivated, in alternation, by said commutation circuit;

and two others of said bridge elements being configured as resistors, one resistor being arranged in a current path from said one winding terminal to the other one of said leads, and the other resistor being arranged in a current path from the other winding terminal to the other one of said leads.

2. The motor according to claim 1, further comprising

a constant-current element (77) connected in series with the H-bridge circuit (52).

3. The motor according to claim 1, further comprising, on the stator (2), at least one ferromagnetic part (34) that, when the motor is in a zero-current state, pulls the rotor (19) into a predefined starting position.

4. The motor according to claim 1, further comprising, on the stator (2), at least one ferromagnetic part (34) that, when the motor is in a zero-current state, pulls the rotor (19) into one of a plurality of predefined starting positions.

5. The motor according to claim 3, wherein the at least one ferromagnetic part is configured as a permanent magnet (34).

6. The motor according to claim 1, wherein the commutation circuit is configured in such a way that after starting up, a predefined transistor (54) of the H-bridge circuit (52) is activated and the other transistor (56) is inhibited.

7. The motor according to claim 1, further comprising

a sensor winding (26), arranged on said stator (2) such that the permanent-magnet rotor (19) induces a sensor voltage in said sensor winding as the rotor rotates;

and in which said commutation circuit includes a current mirroring circuit (84, 86) with which the sensor winding (26) is electrically connected in such a way that, in the absence of a sensor voltage at the sensor winding (26), the current mirroring circuit (84, 86) brings about a predefined switching state of the H-bridge circuit (52).

8. The motor according to claim 7, wherein the current mirroring circuit comprises two transistors (84, 86) between whose bases the sensor winding (26) is arranged, one of the transistors (84) being connected as a diode and the other transistor (86) serving to control the H-bridge circuit (52).

9. The motor according to claim 8, wherein

the other transistor (86) of the current mirroring circuit is connected in series with a collector resistor (90), and

the current mirroring circuit is designed in such a way that, when the motor is stationary, the potential, between the other transistor (86) and its collector resistor (90), is on the order of half the operating voltage of said motor.

10. The motor according to claim 1, further comprising

a semiconductor bypass switch (106) which, when the motor (12) is switched on, is briefly caused to be conductive and thereby bypasses an element (60), configured as a resistor, of the H-bridge circuit (52), in order to raise a starting current of the motor.

11. The motor according to claim 2, further comprising

a semiconductor bypass switch (106) which, when the motor is switched on, is briefly caused to be conductive, to thereby bypass said constant-current element and an element, configured as a resistor, of said H-bridge circuit, in order to enable a higher starting current as the motor starts up.

12. The motor according to claim 10, wherein the semiconductor bypass switch (106) has, associated therewith, a timer which causes said semiconductor bypass switch to be conductive only for a predefined time period after the motor is switched on.

13. The motor according to claim 12 wherein, during the predefined time period, that bridge element of the H-bridge circuit which is configured as a transistor, and is connected in series with the semiconductor bypass switch, is blocked.

14. The motor according to claim 13, which is configured for directly driving a fan wheel.

15. The motor according to claim 14, wherein the fan wheel is coupled to a permanent magnet forming a part of the rotor of the motor.

16. The motor according to claim 4, wherein the at least one ferromagnetic part is configured as a permanent magnet (34).

17. A method of operating an electronically commutated dc motor, said motor having a stator comprising a drive winding connected to a driver circuit,

said stator being coupled with the stationary part of a radial fan comprising a rotatable radial fan component;

said motor further comprising a permanent magnet rotor interacting with said stator and being directly coupled with said rotatable radial fan component;

comprising the step of

operating the electronically commutated direct current motor by applying thereto, in operation, a constant current adapted to a desired rotation speed range of the radial fan.

18. An electronically commutated direct-current motor for a driving a radial fan arrangement having a fan wheel, said motor comprising

a permanent-magnet rotor (19) configured as a constituent of the fan wheel of the radial fan arrangement;

a stator comprising at least one drive winding;

a current limiting arrangement which is continually active when the motor is in operation, to substantially maintain a drive current flowing through the motor at a predefined value; and

a deactivation apparatus for the current limiting arrangement, for automatically deactivating the latter for a predefined time period after the motor is switched on.

19. The motor according to claim 18, further comprising a timer (108, 110) for controlling the predefined time period.