Phase current detection method, inverter control method, motor control method, and apparatuses used in these methods

• US 20040169488A1
• Filed: 07/29/2003
• Published: 09/02/2004
• Est. Priority Date: 09/29/2001
• Status: Active Grant

• Current Assignee: Daikin Industries Ltd
• Original Assignee: Daikin Industries Ltd
• Inventors: Maeda, Toshiyuki, Taniguchi, Tomoisa
• Granted Patent: US 7,173,393 B2
• Time in Patent Office: Days
• US Class Current: 318/801
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 7/53873 with digital control
• CPC Class Codes: H02M 7/53875 with analogue control of three-phase output
• CPC Class Codes: H02M 7/53876 based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times
• CPC Class Codes: H02M 7/5395 by pulse-width modulation
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 6/28 Arrangements for controlling current H02P6/10 takes precedence

Abstract

The phase current detection apparatus comprises an output time detection section 6a for receiving a voltage vector command as input, and for detecting a voltage vector which should be enlarged its output time, output time enlargement section 6bfor receiving the voltage vector command and the voltage vector detected by the output time detection section 6a as input, and for carrying out enlargement processing for output time (enlarge the output time up to a length allowing the current detector 5 to detect the voltage vector), subtraction section 6c for subtracting the length of actually output voltage vector from the voltage vector command, and for outputting an error, output error integrating section 6d for integrating the error from the subtraction section 6g and for calculating an integrated error of an output with respect to the voltage vector command, reverse vector generation section 6e for outputting a vector (reverse vector) which is obtained by replacing the ON/OFF in Table 1 for the enlarged voltage vector, and selection section 6f for carrying out the replacing operation depending upon the sign of the integrated error from the output error integrating section 6d so as to select the output from the output time enlargement section 6b and the output from the reverse vector generation section 6e . Therefore, decrease in cost, detection of a phase current with stability at a desired timing, and great decrease in distortion in voltage waveform are realized.

Claims

1. A phase current detection method is a method which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied and which restricts the minimum pulse width, which method is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the method comprising the step of:

adjusting a voltage to be applied by adding positive or reversed voltage in response to a fact that a desired duty has a small value.

4. A phase current detection method as set forth in one of claim 1 through claim 3, wherein the current detection is carried out by sampling the current at the center of a period when a current corresponding to a voltage vector is observed through a shunt resistor.

5. A phase current detection method as set forth in one of claim 1 through claim 3, wherein the current detection is carried out by sampling the current at the center of a period when a voltage vector is output.

6. A phase current detection method as set forth in one of claim 1 through claim 3, wherein the current detection is carried out by sampling the current at the center of a period which is a period obtained by removing a period for hardware becoming stable starting of the period when a current corresponding to a voltage vector is observed through the shunt resistor, from the period when a current corresponding to a voltage vector is observed through the shunt resistor.

7. A phase current detection method as set forth in one of claim 4 through claim 6, wherein the current detection is carried out by sampling the current at a timing which has passed a response time from the starting of the period in response to the fact that sampling at the center of the period is impossible due to the restriction of the response time.

2. A phase current detection method is a method which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied and which restricts the minimum pulse width, which method is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the method comprising the step of:

adjusting a voltage to be applied by varying a pulse application interval in response to a fact that a desired duty has a small value.

3. A phase current detection method is a method which detects a DC link current and calculates a phase current of a motor (4), which method is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the method comprising the steps of:

judging whether or not current detection is possible during the dead time, and

carrying out current detection in response to the judgement result representing that current detection is possible.

8. A phase current detection method is a method which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied, which method is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the method comprising the step of:

estimating a current from the past current values in response to the fact that an applied voltage vector is too short to measure the current.

9. A phase current detection method is a method which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied, which method is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the method comprising the step of:

estimating a current value at a desired timing by correcting a current detection value using a current estimation value generated from the past current detection values.

10. A phase current detection method as set forth in claim 9, wherein the correction of current detection value is carried out by adding an error current to the estimated current value at the desired timing.

11. A phase current detection method as set forth in claim 9, wherein the correction of current detection value is carried out by operating an amplitude error from the error current and by adding the amplitude error to the estimated current of the desired timing.

12. A phase current detection method is a method which estimates the current value by employing the method of claim 11 or the method of claim 10, in response to the size of the amplitude.

13. An inverter control method is a method which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied, which method is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), and which carries out current controlling or position-sensor-less controlling, the method comprising the step of:

carrying out the controlling using the current measurement values at two current measurement timings within a carrier interval.

14. A phase current detection apparatus is an apparatus which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied and which restricts the minimum pulse width, which apparatus is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the apparatus comprising:

adjusting means (6e) for adjusting a voltage to be applied by adding positive or reversed voltage in response to a fact that a desired duty has a small value.

17. A phase current detection apparatus as set forth in one of claim 14 through claim 16, wherein the current detection means (5)(7e)(7f) is means for sampling the current at the center of a period when a current corresponding to a voltage vector is observed through a shunt resistor (5a).

18. A phase current detection apparatus as set forth in one of claim 14 through claim 16, wherein the current detection means (5)(7e)(7f) is means for sampling the current at the center of a period when a voltage vector is output, as the current detection means.

19. A phase current detection apparatus as set forth in one of claim 14 through claim 16, wherein the current detection means (5)(7e)(7f) is means for sampling the current at the center of a period which is a period obtained by removing a period for hardware becoming stable starting of the period when a current corresponding to a voltage vector is observed through the shunt resistor (5a), from the period when a current corresponding to a voltage vector is observed through the shunt resistor (5a).

20. A phase current detection apparatus as set forth in one of claim 17 through claim 19, wherein the current detection means (5)(7e)(7f) is means for sampling the current at a timing which has passed a response time from the starting of the period in response to the fact that sampling at the center of the period is impossible due to the restriction of the response time, as the current detection means.

15. A phase current detection apparatus is an apparatus which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied and which restricts the minimum pulse width, which apparatus is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the apparatus comprising:

adjusting means (6c)(7b) for adjusting a voltage to be applied by varying a pulse application interval in response to a fact that a desired duty has a small value.

16. A phase current detection apparatus is an apparatus which detects a DC link current and calculates a phase current of a motor (4), which apparatus is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the apparatus comprising:

current detection means (5)(7e)(7f) for judging whether or not current detection is possible during the dead time, and for carrying out current detection in response to the judgement result representing that current detection is possible.

21. A phase current detection apparatus is an apparatus which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied, which apparatus is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the apparatus comprising:

current estimation means (8b)(8d)(8h) for estimating a current from the past current values in response to the fact that an applied voltage vector is too short to measure the current.

22. A phase current detection apparatus is an apparatus which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied, which apparatus is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the apparatus comprising:

current estimation means (8i)(8j) for estimating a current value at a desired timing by correcting a current detection value using a current estimation value generated from the past current detection values.

23. A phase current detection apparatus as set forth in claim 22, wherein the current estimation means (8i)(8j) is means for correcting the current detection value by adding an error current to the estimated current value at the desired timing.

24. A phase current detection apparatus as set forth in claim 22, wherein the current estimation means (8i)(8j) is means for correcting the current detection value by operating an amplitude error from the error current and by adding the amplitude error to the estimated current of the desired timing.

25. A phase current detection apparatus as set forth in claim 22, wherein the current estimation means (8i)(8j) is means for calculating an amplitude error from the error current and for correcting the detection current value by adding the amplitude error to the estimation current of the desired timing, in response to the fact that the amplitude has a great value, and for correcting the current detection value by adding the error current to the estimation current value of the desired timing, in response to the fact that the amplitude has a small value.

26. An inverter control apparatus is an apparatus which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied, which apparatus is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), and which carries out current controlling or position-sensor-less controlling, the apparatus comprising:

control means (9a)(9b)(9c)(9d)(9e) for carrying out the controlling using the current measurement values at two current measurement timings within a carrier interval.

27. A phase current detection method is a method which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied and which restricts the minimum pulse width, which method is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the method comprising the steps of:

estimating direction of the current at the current detection timing, and

varying the minimum pulse width based upon the estimation result.

28. A phase current detection method as set forth in claim 27, wherein the pulse width is a gate-pulse width.

29. A phase current detection method as set forth in claim 28, wherein a period is calculated when current appears on the DC link, from the current flowing direction and the vector pattern to be output, and the gate-pulse width is determined so that the calculated period becomes the minimum vector output period for current detection on the DC link.

30. A phase current detection method as set forth in claim 28 or claim 29, wherein the pattern of switch operation for causing varying in output vector is estimated, and the minimum gate-pulse width is varied based upon the estimation result.

31. A phase current detection method as set forth in one of claim 28 through claim 30, wherein a response time is determined in correspondence with the switching devices constituting the PWM inverter, and the minimum gate-pulse width is varied to match the switching devices which cause current varying.

32. A phase current detection method as set forth in one of claim 28 through claim 31, wherein the direction of the current is estimated from the phase information of the current.

33. A phase current detection method as set forth in one of claim 28 through claim 31, wherein the direction of the current is estimated from the sequence of the current values.

34. A phase current detection method as set forth in one of claim 28 through claim 31, wherein the processing for estimating the direction of the current from the phase information of the current and the processing for estimating the direction of the current from the sequence of the current values are changed over, in response with the rotation speed of the motor.

35. A phase current detection method as set forth in one of claim 28 through claim 34, wherein pulse width restriction is applied to the vector output period excluding the dead time, in response with the fact that the estimated current is within the current estimation error.

36. A phase current detection method as set forth in one of claim 28 through claim 34, wherein one of the switching devices constituting the PWM inverter is turned off for a time required for current detection.

40. A phase current detection method as set forth in one of claim 28 through claim 31, wherein the gate-pulse width is calculated so that the length of the command voltage vector and the vector output period are equal to one another, in response with the fact that the vector output period is longer than the minimum vector output period.

37. A motor controlling method is a method which calculates a motor voltage from a DC link voltage and a gate-pulse width, detects a phase current from a DC link current and a vector pattern to be applied, and controls a motor (4) based upon the calculated motor voltage and the detected phase current, the method comprising the step of:

controlling the DC link voltage to be higher or lower in response with either condition of the voltage required by the motor is higher or lower, respectively.

38. A motor controlling method as set forth in claim 37, wherein the method lowers the power factor and raises the output voltage or the output current when the rotation speed is lower or the load is lighter.

39. A motor controlling method as set forth in claim 37, wherein the method calculates the switching pattern of the voltage varying timing from the direction of the current and the output vector pattern, calculates the delay time of the devices based upon the calculation result, and corrects the motor voltage.

41. A phase current detection method is a method which calculates a phase current from the current of DC link and vector pattern to be applied, the method comprising the steps of:

connecting the converter for carrying out switching operation to the PWM inverter (3) in series, and

prohibiting switching of the converter and the PWM inverter at the current detection timing.

42. A phase current detection method as set forth in claim 41, the converter current and the inverter current are detected by providing a current detection section which is in series with respect to the smoothing condenser on the DC link.

43. A phase current detection apparatus is an apparatus which detects a phase current of a motor (4) based upon a DC link current and a vector pattern to be applied and which restricts the minimum pulse width, which apparatus is included in a motor driving apparatus for driving a motor (4) by supplying outputs from a PWM inverter (3) to the motor (4), the apparatus comprising:

minimum pulse width varying means for estimating direction of the current at the current detection timing, and for varying the minimum pulse width based upon the estimation result.

44. A phase current detection apparatus as set forth in claim 43, wherein the minimum pulse width varying means is means for calculating the period when the current appears on the DC link from the current flowing direction and the vector pattern to be output, and for determining the gate-pulse width so that the calculated period becomes the minimum vector output period for current detection on the DC link.

45. A phase current detection apparatus as set forth in claim 43 or claim 44, wherein the minimum pulse width varying means is means for estimating the pattern of switch operation for causing varying in output vector, and for varying the minimum gate-pulse width based upon the estimation result.

46. A phase current detection apparatus as set forth in one of claim 43 through claim 45, wherein the minimum pulse width varying means is means for determining a response time in correspondence with the switching devices constituting the PWM inverter, and for varying the minimum gate-pulse width to match the switching devices which cause current varying.

47. A phase current detection apparatus as set forth in one of claim 43 through claim 46, wherein the minimum pulse width varying means is means for estimating the direction of the current from the phase information of the current.

48. A phase current detection apparatus as set forth in one of claim 43 through claim 46, wherein the minimum pulse width varying means is means for estimating the direction of the current from the sequence of the current values.

49. A phase current detection apparatus as set forth in one of claim 43 through claim 46, wherein the minimum pulse width varying means is means for changing over the processing for estimating the direction of the current from the phase information of the current and the processing for estimating the direction of the current from the sequence of the current values, in response with the rotation speed of the motor.

50. A phase current detection apparatus as set forth in one of claim 43 through claim 49, wherein the minimum pulse width varying means is means for applying pulse width restriction to the vector output period excluding the dead time, in response with the fact that the estimated current is within the current estimation error.

51. A phase current detection apparatus as set forth in one of claim 43 through claim 49, wherein the minimum pulse width varying means is means for turning off one of the switching devices constituting the PWM inverter for a time required for current detection, as the minimum pulse width varying means.

55. A phase current detection apparatus as set forth in one of claim 43 through claim 50, wherein the minimum pulse width varying means is means for calculating the gate-pulse width so that the length of the command voltage vector and the vector output period are equal to one another, in response with the fact that the vector output period is longer than the minimum vector output period.

56. A phase current detection apparatus as set forth in one of claim 43 through claim 50, wherein the converter for carrying out switching operation is connected to the PWM inverter in series.

52. A motor controlling apparatus is an apparatus which calculates a motor voltage from a DC link voltage and a gate-pulse width, detects a phase current from a DC link current and a vector pattern to be applied, and for controlling a motor based upon the calculated motor voltage and the detected phase current, the apparatus comprising:

motor voltage control means for controlling the DC link voltage to be higher or lower in response with either condition of the voltage required by the motor is higher or lower, respectively.

53. A motor controlling apparatus as set forth in claim 52, wherein motor voltage control means is means for lowering the power factor and for raising the output voltage or the output current when the rotation speed is lower or the load is lighter.

54. A motor controlling apparatus as set forth in claim 52, wherein the motor voltage control means is means for calculating the switching pattern of the voltage varying timing from the direction of the current and the output vector pattern, for calculating the delay time of the devices based upon the calculation result, and for correcting the motor voltage.