Method of controlling the commutation in an electronically commutated motor, and an electronically commutated motor for carrying out said method

• US 20040056617A1
• Filed: 05/19/2003
• Published: 03/25/2004
• Est. Priority Date: 08/10/2001
• Status: Active Grant

• Current Assignee: Ebm-Papst St Georgen GmbH & Company KG (Ebm-Papst Mulfingen GmbH & Company KG)
• Original Assignee: Ebm-Papst St Georgen GmbH & Company KG (Ebm-Papst Mulfingen GmbH & Company KG)
• Inventors: Vond Der Heydt, Thomas, Kuner, Arnold, Jeske, Frank, Berroth, Hansjorg, Strasser, Gunther, Layes, Paul, Schondelmaier, Hans-Dieter
• Granted Patent: US 6,995,534 B2
• Time in Patent Office: Days
• US Class Current: 318/439
• CPC Class Codes: H02P 6/20 Arrangements for starting H02P6/08 takes precedence
• CPC Class Codes: H02P 6/28 Arrangements for controlling current H02P6/10 takes precedence

Abstract

The invention concerns a method for controlling the commutation in an electronically commutated motor (20) which comprises a stator having at least one phase (24, 26), and a permanent-magnet rotor (22), and with which a current limiter (36, 58) and a controller (18) for regulating a motor variable are associated. The current limiter (36, 58) serves to limit the current (I) in the at least one phase (24, 26) to a setpoint value. The regulation by means of the controller (18) is accomplished by modifying the distance in time (W) between switching on (t1) and switching off (t2) of the current (i₁, i₂) in the at least one phase. In this method, the setpoint value to which the current limiter limits the current (i₁, i₂) in the relevant phase is modifiable. It is modified substantially as a function of a ratio of two times (W/T), namely as a function of the ratio of the distance in time (W) between switching on (t1) and switching off (t2) of the current (i₁, i₂) in the relevant phase (24, 26) to the time period (T) required by the rotor, at the instantaneous rotation speed, to rotate through a specified rotation angle. A decrease in noise at low rotation speeds is thereby made possible. A corresponding motor is also described.

Claims

1. A method for controlling the commutation in an electronically commutated motor (20) which comprises a stator having at least one phase (24, 26), and a permanent-magnet rotor (22), and with which

a current limiter (36, 58) and

a controller (18) for regulating a motor variable are associated, wherein

the current limiter (36, 58) is implemented to limit the current (I) in the at least one phase (24, 26) to a setpoint value, and

the regulation by means of the controller (18) is accomplished by modifying the distance in time (W) between switching on (t1) and switching off (t2) of the current (i₁, i₂) in the at least one phase, comprising the following step:

the setpoint value to which the current limiter limits the current (i₁, i₂) in the at least one phase is modified substantially as a function of the percentage ratio (W/T) of

the distance in time (W) between switching on (t1) and switching off (t2) of the current (i₁, i₂) in the at least one phase (24, 26) to

the duration (T) of a rotation of the rotor (22) through a specified rotation angle.

2. The method according to claim 1,

wherein the setpoint value for the current limiter is elevated as the value of said percentage ratio (W/T) increases.

3. The method according to claim 1 or 2,

wherein the setpoint value (FIG. 7d:

u_C) is set, during the duration of a current pulse (i₁, i₂) flowing in the at least one phase, to an increasing value in a first time period (FIG. 7e;

t5 . . . t6), and to a decreasing value in a second time period (FIG. 7e;

t6 . . . t7) subsequent thereto.

4. The method according to one of the preceding claims,

wherein the setpoint value is controlled by means of a current limiting control signal (FIGS. 6, 7:

84) which, with reference to the instantaneous frequency of a signal (S31, S33) serving to control the commutation, has a frequency which is greater by an integral factor.

5. The method according to claim 4,

wherein the current limiting control signal (FIGS. 6, 7:

84) has a frequency that is equal to at least twice the frequency of a signal (S31, S33) serving to control the commutation.

6. The method according to claim 4 or 5,

wherein the current limiting control signal (84) has a pulse duty factor (X*W/T′

) which is at least similar to the pulse duty factor (W/T) of a signal (S31, S33) serving to control the commutation.

7. A method for controlling the commutation in an electronically commutated motor (20) which comprises a stator having at least one phase (24, 26), and a permanent-magnet rotor (22), comprising the following steps:

in order to control switching on and off of the current (i₁) in said at least one winding phase (24, 26), a first signal (S31) is generated which has a frequency (1/T) determined by the rotation speed of the motor, and a specified pulse duty factor (W/T);

in order to control the shape of the current (i₁) in said winding phase (24, 26), a second signal (84) is generated which has twice the frequency (2/T) of the first signal (S31) and a pulse duty factor (X*W/T′

) similar thereto.

8. An electronically commutated motor (20)

having a stator which comprises at least one winding phase (24, 26), and

having a permanent-magnet rotor (22),

a first semiconductor element (30, 32) controllable by means of a first control signal (S31, S33), and a measuring member (36) for sensing the current (i₁, i₂) flowing through said winding phase (24, 26) being provided in series with said winding phase (24, 26),

further comprising a second semiconductor element (58) which is controllable by the voltage (U_R) at said measuring member (36) and which, as a function of its state, influences the magnitude of the control signal (S31, S33) that is supplied to the first semiconductor element (30, 32) in order, upon a rise in the current (I) through the resistor (36), to reduce the conductivity of said first semiconductor element (30, 32) and thereby to limit said current (I) to a maximum,

and comprising a third controllable semiconductor element (66) which, as a function of its state, influences the conductivity of the second semiconductor element (58), the conductivity of said third semiconductor element (66) being controllable by means of an additional control signal (u_C) in order, in addition to the influencing of the second semiconductor element (58) by the voltage (u_R) at the measuring member (36), also to enable an influencing of the second semiconductor element (58) by the additional control signal (u_C).

9. The motor according to claim 8,

wherein the conductivity of the third semiconductor element (66) is controllable as a function of the information content of a control signal (S31) which is conveyed to a control electrode of the first semiconductor element (30, 32) while the motor (20) is in operation, in order to control the commutation of said semiconductor element (30, 32).

10. The motor according to claim 9,

wherein the signal (S31, S33) supplied to the control electrode of the first semiconductor element (30, 32) is supplied through a filtering member (70, 76, 78) to the third semiconductor element (66) as an additional control signal (u_C).

20. The motor according to one of claims 8 through 19, whose rotation speed is controlled by a temperature in such a way that the rotation speed of the motor is lower at a low temperature than at a higher temperature.

21. The motor according to one of claims 8 through 20, associated with which is a rotation speed controller which regulates the motor rotation speed to a specified value (n_soll).

22. The motor according to claim 21,

wherein the specified value (n_soll) is a function of a temperature.

11. An electronically commutated motor

having a stator which comprises at least two winding phases (24, 26), and

having a permanent-magnet rotor (22), a semiconductor element (30, 32) controllable by means of an associated first control signal (S31, S33) being provided in series with each winding phase (24, 26) for controlling the phase current (i₁, i₂) flowing through said winding phase,

and a shared measuring member (36) being provided for sensing the current (I) flowing in the winding phases,

further having a semiconductor element (58) which is associated with the shared measuring member (36) and controllable by the voltage (U_R) thereat and which as a function of its state influences, via a respective diode (54, 56), the magnitude of that control signal (S31, S33) supplied to the presently conducting semiconductor element (30, 32) for control of the phase current (i₁, i₂) associated therewith, in order, upon a rise in the current (I) through the measuring member (36), to reduce the conductivity of said presently conducting semiconductor element (30, 32) and thereby to limit that current (I) to a maximum.

12. The motor according to claim 11,

wherein an additional controllable semiconductor element (66) is provided which, as a function of its state, influences the conductivity of the semiconductor element (58) associated with the measuring member (36), the conductivity of said additional semiconductor element (66) being controllable by means of an additional control signal (84;

u_C) in order also to make possible, in addition to the influencing of the semiconductor element (58) associated with the measuring member (36) by means of the voltage (U_R) at the measuring member (36), an influencing of said semiconductor element (58) by the additional control signal (84;

u_C).

13. The motor according to claim 12,

wherein the conductivity of the additional semiconductor element (66) is influenced by the pulse duty factor (W/T) of the first control signal (S31, S33).

14. The motor according to claim 12 or 13,

wherein the conductivity of the additional semiconductor element (66) is controllable by means of an additional control signal (84), derived from a first control signal (S31, S33), which has a frequency that is at a specified ratio to the frequency of the first control signal (S31, S33) and is higher than the latter.

15. The motor according to claim 14,

wherein the information content of the additional control signal (84) is substantially determined by the information content of the first control signal (S31, S33).

16. An electronically commutated motor (20)

having a stator which comprises at least one winding phase (24, 26), and

having a permanent-magnet rotor (22),

a semiconductor element (30, 32), controllable by means of a first control signal (S31, S33) that has a frequency (1/T) determined by the motor rotation speed and has a specified pulse duty factor, being provided in series with the at least one winding phase (24, 26), the first signal (S31) controlling the switching on and off of that semiconductor element (30, 32),

and having a signal source (27) for a second signal (84) whose frequency (1/T′

) is an integral multiple of the frequency (1/T) of the first signal (S31) and which serves to influence the shape of the current (i₁) flowing through the at least one winding phase (24).

17. The motor according to claim 16,

wherein the pulse duty factor (X*W/T′

) of the second signal (84) is similar to the pulse duty factor (W/T) of the first signal (S31).

18. The motor according to claim 16 or 17,

wherein the frequency (1/T′

) of the second signal (84) is twice the frequency (1/T) of the first signal (S31).

19. The motor according to one of claims 16 through 18,

wherein an additional controllable semiconductor element (66) is provided which, as a function of the second signal (84), influences the conductivity of the controllable semiconductor element (30) connected in series with the at least one winding phase (24) when the latter element is switched on by the first signal (S31).