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

• US 6,995,534 B2
• Filed: 07/20/2002
• Issued: 02/07/2006
• Est. Priority Date: 08/10/2001
• Status: Expired due to Fees

• 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: Kuner, Arnold, Jeske, Frank, Strasser, Günther, Berroth, Hansjörg, Layes, Paul, Schondelmaier, Hans-Dieter, Von Der Heydt, Thomas
• Primary Examiner(s): IP, SHIK LUEN PAUL
• Application Number:
  US10/432,444
• Publication Number:
  US 20040056617A1
• Time in Patent Office: 1,298 Days
• Field of Search: 318/139, 318/254, 318/434, 318/439, 318/138, 318/700, 318/701, 318/707, 388/800, 388/806, 388/811, 388/815, 388/821, 388/822
• US Class Current: 318/400.22
• 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

A method is disclosed 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.

Claims

1. A method of controlling the commutation of an electronically commutated motor which comprises a stator having at least one winding phase, and a rotor arranged for interaction with said stator, said motor having associated therewith a controller adapted for controlling a motor variable by controlling distance in time between switching-on and switching-off the current in said winding phase, and having further associated therewith a current limiter implemented to limit the current in said phase to a selectable setpoint value, said method comprising the steps of:

determining a factor, characterizing the relationship between said distance in time, and the time span needed by the rotor for rotation through a specified rotation angle at the rotor'"'"'s current speed, and

modifying the setpoint value, as a function of said factor.

2. The method according to claim 1,

further comprising elevating the setpoint value for the current limiter as the value of said factor increases.

3. The method according to claim 1,

further comprising setting the setpoint value, during the duration of a current pulse flowing in the at least one phase, to an increasing value in a first time period, and to a decreasing value in a second time period subsequent thereto.

4. The method according to claim 1,

further comprising controlling the setpoint value by means of a current limiting control signal which, with reference to the instantaneous frequency of a signal 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 has a frequency that is equal to at least twice the frequency of a signal serving to control the commutation.

6. The method according to claim 4,

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

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

7. A method of controlling the commutation in an electronically commutated motor which comprises a stator having

at least one winding phase,

a permanent-magnet rotor arranged for interaction with said stator, a speed controller for controlling motor speed to a setpoint rotation speed,

computer means for generating a first switching signal having a frequency determined by the actual rotation speed of the motor, and

a pulse duty factor determined by a difference between the setpoint rotation speed and the actual rotation speed, comprising the steps of:

using the first signal to control switching on and switching off the current in said winding phase,

generating a second signal which has twice the frequency of the first signal and a pulse duty factor similar thereto; and

using the second signal to control the shape of the current in the winding phase.

8. An electronically commutated motor (20) comprising

a stator having at least one winding phase

a permanent-magnet rotor,

a speed controller for generating a first control signal for controlling the rotation speed of said motor,

a first semiconductor element controllable by the first control signal, and

a measuring member (36), for sensing the current (i1, i2) flowing through said winding phase, being provided in series with said winding phase,

a second semiconductor element (58) which is controllable by the voltage (uR) 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 predetermined value,

and a third controllable semiconductor element for controlling said predetermined value, as a function of a motor parameter.

9. The motor according to claim 8,

wherein the conductivity of the third controllable semiconductor element is controllable as a function of the information content of a control signal which is applied to a control electrode of the first semiconductor element while the motor is in operation, in order to control commutation of said semiconductor element.

10. The motor according to claim 9,

wherein the signal applied to the control electrode of the first semiconductor element is applied through a filtering member to the third controllable semiconductor element (66) as an additional control signal.

11. The motor according to claim 8, 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.

12. The motor according to claim 8, further comprising a rotation speed controller which regulates the motor rotation speed to a specified value (nsoll).

13. The motor according to claim 12,

wherein the rotation speed controller is implemented to set the specified value (nsoll) as a function of a temperature.

14. An electronically commutated motor comprising

a stator which comprises at least two winding phases,

a permanent-magnet rotor,

a semiconductor element controllable by means of an associated first control signal (S31, S33), being provided in series with each winding phase, for controlling the phase current (il, i2) flowing through said winding phase and for controlling the rotational steed of the motor to a setpoint speed,

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

a semiconductor element (58) associated with the shared measuring member (36) and controllable by the voltage (uR) 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 (il, 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 predetermined value, and

an additional controllable semiconductor element for controlling said predetermined value as a function of a motor parameter.

15. The motor according to claim 14,

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).

16. The motor according to claim 14,

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.

17. The motor according to claim 16,

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

18. An electronically commutated motor (20) comprising

a stator which comprises at least one winding phase,

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, said semiconductor element being provided in series with the at least one winding phase, the first signal (S31) controlling the switching on and off of that semiconductor element (30, 32),

and 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, in operation, the shape of the current (i1) flowing through the at least one winding phase (24).

19. The motor according to claim 18,

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).

20. The motor according to claim 18,

wherein the frequency of the second signal (84) is twice the frequency of the first signal (S31).

21. The motor according to claim 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).