ELECTRONICALLY COMMUTATED MOTOR (ECM) AND METHOD OF CONTROLLING AN ECM

• US 20070024225A1
• Filed: 07/14/2006
• Published: 02/01/2007
• Est. Priority Date: 07/28/2005
• Status: Abandoned Application

• 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: Hahn, Alexander, Schmid, Harald, Kisch, Michael
• Application Number:
  US11/457,532
• Publication Number:
  US 20070024225A1
• Time in Patent Office: Days
• US Class Current: 318/434
• CPC Class Codes: H02H 7/0838 with H-bridge circuit
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage
• CPC Class Codes: H02P 6/12 Monitoring commutation; Providing indication of commutation failure
• CPC Class Codes: H02P 6/28 Arrangements for controlling current H02P6/10 takes precedence

Abstract

An electronically commutated motor comprises a rotor (208); a stator (201) electromagnetically interacting with the rotor (208), which stator is formed with a stator winding (202, 204, 206); a power stage (122) controlling the currents flowing in the stator winding (202, 204, 206) during operation; at least one current measuring element (242, 244) for sensing a measured value for the currents (I_UPPER, I_LOWER) flowing in the power stage, and an overcurrent measuring element (152, 162) for evaluating an associated measured value and for sensing a current whose absolute value exceeds a predetermined limit value (I_MAX_UPPER, I_MAX_LOWER); a holding element (154, 164) associated with the overcurrent measuring element (152, 162), configured, when an overcurrent occurs in the associated current measuring element (242, 244), to generate an overcurrent signal (OC_UPPER, OC_LOWER), to store the signal, and to deliver a signal to the power stage (122).

Claims

1. An electronically commutated motor (ECM) comprising:

a rotor (208);

a stator (201) for electromagnetically interacting with the rotor (208), which stator is equipped with a stator winding arrangement (202, 204, 206);

a power stage (122) for controlling the currents flowing in the stator winding arrangement (202, 204, 206) during operation;

at least one current measuring element (242, 244) for sensing a measured value for the currents (I UPPER, I LOWER) flowing in the power stage;

an overcurrent measuring element (152, 162) for evaluating an associated measured value and for sensing a current whose absolute value exceeds a predetermined limit value (I_MAX_UPPER, I_MAX_LOWER); and

a holding element (154, 164) associated with the overcurrent measuring element (152, 162), which holding element is configured, upon occurrence of an overcurrent in the associated current measuring element (242, 244), to generate an overcurrent signal (OC_UPPER, OC_LOWER), to store it, and to deliver to the power stage (122) a corresponding signal in order to counteract the overcurrent.

2. The motor according to claim 1, wherein

a holding element (154, 164) is configured to store the overcurrent signal upon its occurrence.

3. The motor according to claim 1, wherein

a holding element (154, 164) is configured to store the overcurrent signal, upon its occurrence, for a predetermined time period.

4. The motor according to claim 1, further comprising

a reset element (270, 290) adapted to reset the holding element (154, 164).

5. The motor according to claim 4, wherein

the reset element (270, 290) is configured to reset the holding element (154, 164) after a predetermined time period.

6. The motor according to claim 4, wherein

the reset element (270, 290) is configured to reset the holding element (154, 164) in response to an external activation of the reset element.

7. The motor according to claim 1, further comprising

a control circuit (280) controlled by the holding element (154, 164), which circuit is configured to switch off the power stage (122) in the event of an overcurrent, in order to prevent damage to the motor, including its electronics, by the detected overcurrent.

8. The motor according to claim 1, wherein

the holding element comprises a differential amplifier (342, 382, 424) that has an input and an output and is configured to compare a signal derived from the current in the current measuring element (242, 244) with a maximum value, and to generate an overcurrent signal (OC_UPPER, OC_LOWER) when the current-derived signal exceeds the maximum value.

9. The motor according to claim 8, wherein

the output of the differential amplifier (342, 382, 424) is fed back to its non-inverting input (−

) in order to bring about self-holding, by way of the feedback, upon generation of an overcurrent signal at the output of the differential amplifier.

10. The motor according to claim 1, wherein

the current measuring element (242, 244) is implemented as a measuring resistor.

11. The motor according to claim 1, wherein

the current measuring element (242, 244) is arranged between a supply voltage source (+U_B, GND) and the power stage (122) in order to sense a signal describing the power-stage current.

12. The motor according to claim 1, wherein

the power stage (122) comprises at least one semiconductor switch that can be switched off, at least for a time interval, upon occurrence of an overcurrent signal.

13. The motor according to claim 1, wherein

said stator winding arrangement has at least one stator phase (202, 204, 206);

the power stage has, for stator phase control, a full bridge having upper and lower semiconductor switches (212, 214, 216, 222, 224, 226), and

the control circuit (280) is configured to render all the upper and lower semiconductor switches non-conductive, in order to switch off the power stage.

14. The motor according to claim 13, wherein

at least one first overcurrent measuring element (162) is connected to a first measuring resistor (244), arranged between ground and the lower semiconductor switches (222, 224, 226) of the power stage, in order to sense a first signal describing the power-stage current;

and

at least one second overcurrent measuring element (152) is connected to a second measuring resistor (242), arranged between a supply voltage source (+U_B) and the upper semiconductor switches (222, 224, 226) of the power stage, to sense a second signal describing the power-stage current.

15. The motor according to claim 14, wherein

the first overcurrent measuring element (162) has associated therewith a first holding element (164) which is configured to generate a first overcurrent signal (OC_LOWER) when an overcurrent is detected at the first measuring resistor (244);

and

the second overcurrent measuring element (152) has associated therewith a second holding element (154) which is configured to generate a second overcurrent signal (OC_UPPER) when an overcurrent is detected at the second measuring resistor (242).

16. The motor according to claim 15, wherein

the first and the second holding element (164, 154) are respectively connected to the control circuit (280), which is configured to switch off the power stage of the motor, upon reception of at least one of the first and the second overcurrent signals (OC_LOWER, OC_UPPER).

17. The motor according to claim 1, wherein generation of the overcurrent signal (OC_UPPER, OC_LOWER) by the overcurrent measuring element (152, 162) from the sensed value is accomplished within 500 ns.

18. A method of controlling an electronically commutated motor having:

a rotor (208) and a stator (201) for interacting electromagnetically with the rotor (208), which stator is equipped with a stator winding arrangement (201); and

a power stage (122) for controlling the currents flowing in the stator winding (202, 204, 206) during operation;

comprising the steps of;

A) measuring a current value for at least one current (I UPPER;

I LOWER) flowing in the power stage (122);

B) comparing said measured current value to a predetermined limit value (I_MAX_UPPER;

I_MAX_LOWER);

C) if the measured value exceeds the predetermined limit value, determining the absolute value of the difference between said measured and limit values, and designating said absolute value as an overcurrent;

D) upon occurrence of an overcurrent, generating an overcurrent signal (OC_UPPER, OC_LOWER);

E) storing the overcurrent signal; and

F) delivering a signal corresponding to the overcurrent signal to the power stage (122), in order to counteract the overcurrent there.

19. The method according to claim 18, further comprising,

upon occurrence of said overcurrent signal, storing said overcurrent signal for a predetermined time period.

20. The method according to claim 18, further comprising

generating a reset signal (RESET UPPER, RESET LOWER) in order to cancel the overcurrent signal.

21. The method according to claim 20, further comprising

automatically generating said reset signal (RESET UPPER, RESET LOWER) a predetermined time period after receipt of said overcurrent signal.

22. The method according to claim 20, further comprising generating said the reset signal (RESET UPPER, RESET LOWER) in response to an external instruction.

23. The method according to claim 18, further comprising, upon occurrence of an overcurrent, switching off the power stage (122), in order to prevent said overcurrent from damaging the motor and its control circuits.