Control device for electric rotating machine and method of controlling the machine

• US 8,193,743 B2
• Filed: 11/30/2009
• Issued: 06/05/2012
• Est. Priority Date: 11/28/2008
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Yamada, Takahiro, Morioka, Tatsuru, Miyachi, Junji
• Primary Examiner(s): Ip, Paul
• Application Number:
  US12/627,494
• Publication Number:
  US 20100134053A1
• Time in Patent Office: 918 Days
• Field of Search: 318/400.24, 318/400.25, 318/400.33, 318/254, 318/434, 318/721, 318/162, 318/727, 318/811, 363/41, 363/98, 323/282
• US Class Current: 318/162
• CPC Class Codes: H02M 7/53875 with analogue control of three-phase output
• CPC Class Codes: H02P 2101/45 for motor vehicles, e.g. car alternators
• CPC Class Codes: H02P 2201/09 Boost converter, i.e. DC-DC step up converter increasing the voltage between the supply and the inverter driving the motor general aspects of plural converters in cascade H02M
• CPC Class Codes: H02P 2207/05 Synchronous machines, e.g. with permanent magnets or DC excitation
• CPC Class Codes: H02P 23/0027 using different modes of control depending on a parameter, e.g. the speed
• CPC Class Codes: H02P 27/08 with pulse width modulation

Abstract

A control device has a unit for preparing a pattern having first and second periods by comparing a triangular wave and a sine wave having an amplitude ratio set at each value of a modulation factor, and selecting one pattern corresponding to an instructed modulation factor, and a unit for applying a controlled voltage, set at low and high levels in response to first and second periods of the selected pattern, to a generator. The triangular wave has a cycle duration obtained by dividing the cycle duration of the generator by product of 3 and odd number, a crest having a level higher than the sine wave at a timing of each first period, and a trough having a level lower than the sine wave at a timing of each second period.

Claims

1. A control device which controls a controlled variable of an electric rotating machine by controlling a power inverter circuit applying a controlled voltage to the electric rotating machine, comprising:

a pattern preparing unit that prepares a pattern having a level changed with time for each of values of a modulation factor;

a determining unit that determines phase information of the controlled voltage and an instructed value of the modulation factor;

a selecting unit that selects the pattern, corresponding to the instructed value of the modulation factor, from the patterns of the pattern preparing unit; and

a pattern control unit that controls the controlled variable of the electric rotating machine by controlling the power inverter circuit such that the controlled voltage of the power inverter circuit is changed with time according to the selected pattern while adjusting a phase of the control led voltage according to the phase information,

wherein the pattern preparing unit prepares a triangular wave having a cycle duration, which is equal to a value obtained by dividing an electrical angle cycle duration of the electric rotating machine by an integral number, and prepares each pattern as a triangular wave quasi-comparison pattern so as to have both a first period of a first level, depending on the corresponding value of the modulation factor and including a timing synchronized with a crest point or a trough point of the triangular wave, and a second period of a second level, depending on the corresponding value of the modulation factor and including a timing synchronized with the other point of the triangular wave, and

wherein the pattern control unit controls the power inverter circuit to apply a low level of the controlled voltage to the electric rotating machine in response to the first period of the selected triangular wave quasi-comparison pattern and to apply a high level of the controlled voltage to the electric rotating machine in response to the second period of the selected triangular wave quasi-comparison pattern.

2. The control device according to claim 1, wherein each triangular wave quasi-comparison pattern corresponds to the electrical angle cycle duration of the electric rotating machine and has four quarter angle regions partitioned along a time direction of the electrical angle cycle duration, the triangular wave quasi-comparison pattern has a plurality of first periods and a plurality of second periods alternately placed in each quarter angle region, each first period depends on the corresponding value of the modulation factor and includes a timing synchronized with one crest or trough point of the triangular wave, each second period depends on the corresponding value of the modulation factor and includes a timing synchronized with the other point of the triangular wave, and each triangular wave quasi-comparison pattern in each quarter angle region is set in a first period arrangement, in which the first period is shortened in the time direction while the second period is lengthened in the time direction, or a second period arrangement in which the first period is lengthened in the time direction while the second period is shortened in the time direction.

3. The control device according to claim 2, wherein a sum of the first periods is shorter than a sum of the second periods in one of the quarter angle regions set in the first period arrangement, a sum of the first periods is longer than a sum of the second periods in the other quarter angle region set in the first period arrangement, a sum of the first periods is shorter than a sum of the second periods in one of the quarter angle regions set in the second period arrangement, and a sum of the first periods is longer than a sum of the second periods in the other quarter angle region set in the second period arrangement.

4. The control device according to claim 2, wherein the pattern control unit controls the power inverter circuit according to a repeated pattern obtained by repeating the selected triangular wave quasi-comparison pattern, the first period is successively shortened in a first pair of two quarter angle regions successively placed in the repeated pattern, the first period is successively lengthened in a second pair of two quarter angle regions successively placed in the repeated pattern, the repeated pattern further has a specific period, regardless of any crest or trough point of the triangular wave, in one quarter angle region succeeding the other quarter angle region in the first pair as a first period to place the specific period at a position adjacent to a boundary between the quarter angle regions, the repeated pattern further has a specific period, regardless of any crest or trough point of the triangular wave, in one quarter angle region preceding the other quarter angle region in the first pair as a second period to place the specific period at a position adjacent to a boundary between the quarter angle regions, the repeated pattern further has a specific period, regardless of any crest or trough point of the triangular wave, in one quarter angle region preceding the other quarter angle region in the second pair as a first period to place the specific period at a position adjacent to a boundary between the quarter angle regions, and the repeated pattern further has a specific period, regardless of any crest or trough point of the triangular wave, in one quarter angle region succeeding the other quarter angle region in the second pair as a second period to place the specific period at a position adjacent to a boundary between the quarter angle regions.

5. The control device according to claim 1, wherein the first period of each triangular wave quasi-comparison pattern is set so as to place the timing synchronized with the crest or trough point of the triangular wave at a center of the first period, and the second period of each triangular wave quasi-comparison pattern is set so as to place the timing synchronized with the other point of the triangular wave at a center of the second period.

6. The control device according to claim 1, wherein the pattern preparing unit changeably sets the integral number, determining the cycle duration of the triangular wave, according to an electrical angular speed of the electric rotating machine relating to the electrical angle cycle duration of the electric rotating machine.

7. The control device according to claim 6, wherein the pattern preparing unit sets the integral number at a product of an odd number and 3.

8. The control device according to claim 1, further comprising:

a triangular wave comparison control unit that generates another triangular wave, produces a voltage, instructed to the electric rotating machine, so as to set a ratio of an amplitude of the instructed voltage to an amplitude of the triangular wave at the instructed value of the modulation factor, and sets the controlled voltage according to comparison of a level of the instructed voltage and a level of the triangular wave to control the controlled variable of the electric rotating machine, and

a selector that selects the control of the pattern control unit or the control of the triangular wave comparison control unit according to the instructed value of the modulation factor.

9. The control device according to claim 8, wherein the selector switches the selection to the control of the pattern control unit when the instructed value of the modulation factor is equal to or higher than a first value, and the selector switches the selection to the control of the triangular wave comparison control unit when the instructed value of the modulation factor is equal to or lower than a second value lower than the first value.

10. The control device according to claim 1, wherein the pattern preparing unit prepares the triangular wave quasi-comparison pattern having a plurality of first periods, set at different lengths, in a first angle region of the pattern, expresses magnitude of higher-order harmonic waves, existing in the controlled voltage and ranging to the order of a predetermined number, by the lengths of the first periods, and determines the lengths of the first periods such that the magnitude of higher-order harmonic waves is minimized.

11. The control device according to claim 10, wherein the pattern preparing unit weights an amplitude of each higher-order harmonic wave by a weighting factor such that the weighting factor is decreased with the order of the higher-order harmonic wave, and the pattern preparing unit determines the lengths of the first periods such that a sum of the weighted amplitudes of the higher-order harmonic waves is minimized.

12. The control device according to claim 10, wherein the pattern preparing unit prepares the triangular wave quasi-comparison pattern having a plurality of second periods, set at different lengths, in a second angle region of the pattern, and determines the lengths of the second periods such that a pattern obtained by inverting the triangular wave quasi-comparison pattern of the second angle region is symmetric to the triangular wave quasi-comparison pattern in the first angle region with respect to a boundary between the first and second angle regions.

13. The control device according to claim 1, wherein the pattern preparing unit prepares each triangular wave quasi-comparison pattern by forming a sine wave in an electrical angle range from 0 to 2 π

radians corresponding to the electrical angle cycle duration of the electric rotating machine such that a ratio of an amplitude of the sine wave to an amplitude of the triangular wave is set at the corresponding value of the modulation factor, arranging the triangular wave and the sine wave in the electrical angle range of the sine wave so as to place a center of the amplitude of the sine wave at a center of the amplitude of the triangular wave, setting a plurality of first periods in a first angle region of the triangular wave quasi-comparison pattern, corresponding to the sine wave ranging from 0 to π

radians, such that a level of the sine wave at a timing of each first period synchronized with one crest or trough point of the triangular wave is lower than a level of the point of the triangular wave, setting a plurality of second periods in the first angle region other than regions set in the first periods, setting a plurality of second periods in a second angle region of the triangular wave quasi-comparison pattern, corresponding to the sine wave ranging from π

to 2π

radians, such chat a level of the sine wave at a timing of each second period synchronized with the other point of the triangular wave is higher than a level of the other point, and setting a plurality of first periods in the second angle region other than regions set in the second periods, and the pattern control unit controls the power inverter circuit to apply the low level of the controlled voltage to the electric rotating machine in response to each of the first periods of the triangular wave quasi-comparison pattern and to apply the high level of the controlled voltage to the electric rotating machine in response to each of the second periods of the triangular wave quasi-comparison pattern.

14. The control device according to claim 1, wherein the pattern control unit comprises:

a carrier signal producing block that calculates the electrical angle cycle duration of the electric rotating machine according to an electrical angle speed of the electric rotating machine and produces a carrier signal having the triangular wave such that the carrier signal has a maximum value, a minimum value, and a cycle duration equal to a value obtained by dividing the electrical angle cycle duration of the electric rotating machine by the integral number;

a pattern forming instruction signal producing block that produces a pattern forming instruction signal, defined in the electrical angle cycle duration of the electric rotating machine, such that a control signal having a waveform shaped in the selected triangular wave quasi-comparison pattern is produced by comparing a level of the pattern forming instruction signal and a level of the carrier signal, and

a control signal producing block that produces the control signal by comparing the pattern forming instruction signal and the carrier signal set together in the electrical angle cycle duration of the electric rotating machine and controls the power inverter circuit according to the control signal such that the power inverter circuit applies the high and low levels of the controlled voltage to the electric rotating machine.

15. The control device according to claim 14, wherein

the triangular wave quasi-comparison pattern of the control signal corresponds to the electrical angle cycle duration of the electric rotating machine and has four quarter angle regions partitioned along a time direction of the electrical angle cycle duration,

the triangular wave quasi-comparison pattern has a plurality of first periods and a plurality of second periods alternately-placed in each quarter angle region,

the triangular wave quasi-comparison pattern in each quarter angle region is set in a first period arrangement, in which the first period is shortened in the time direction while the second period is lengthened in the time direction, or a second period arrangement in which the first period is lengthened in the time direction while the second period is shortened in the time direction,

each first period depends on the instructed value of the modulation factor and includes a timing synchronized with one crest or trough point of the triangular wave in each quarter angle region, in which a sum of the first periods is smaller than a sum of the second periods, so as to place the point at a center of the first period,

each second period depends on the instructed value of the modulation factor and includes a timing synchronized with the other point of the triangular wave in each quarter angle region, in which a sum of the first periods is larger than a sum of the second periods, so as to place the other point at a center of the second period,

the pattern forming instruction signal producing block sets a level of the pattern forming instruction signal, in an instruction period including each of the first periods in the quarter angle regions of the triangular wave quasi-comparison pattern in which a sum of the second periods is longer than a sum of the first periods, at an instruction value equal to a product of the maximum value and a ratio of a subtracted value, obtained by subtracting the first period from a half of the cycle duration of the carrier signal, to the half of the cycle duration of the carrier signal, and

the pattern forming instruction signal producing block sets a level of the pattern forming instruction signal, in an instruction period including each of the second periods in the quarter angle regions of the triangular wave quasi-comparison pattern in which a sum of the second periods is shorter than a sum of the first periods, at an instruction value equal to a product of the minimum value and a ratio of a subtracted value, obtained by subtracting the second period from a half of the cycle duration of the carrier signal, to the half of the cycle duration of the carrier signal.

16. The control device according to claim 15, wherein

the first period is successively shortened in a first pair of two quarter angle regions, successively placed through a first boundary in a repeated pattern obtained by repeating the quarter angle regions of the triangular wave quasi-comparison pattern, in the time direction,

the first period is successively lengthened in a second pair of two quarter angle regions, successively placed through a second boundary in the repeated pattern, in the time direction,

the triangular wave quasi-comparison pattern further has a specific period at a position, adjacent to the first boundary in one quarter angle region succeeding the other quarter angle region in the first pair, as a first period,

the triangular wave quasi-comparison pattern further has a specific period at a position, adjacent to the first boundary in one quarter angle region preceding the other quarter angle region in the first pair, as a second period,

the triangular wave quasi-comparison pattern further has a specific period at a position, adjacent to the second boundary in one quarter angle region preceding the other quarter angle region in the second pair, as a first period,

the triangular wave quasi-comparison pattern further has a specific period at a position, adjacent to the second boundary in one quarter angle region succeeding the other quarter angle region in the second pair as a second period,

when the specific period is longer than the quarter of the cycle duration of the carrier signal, the pattern forming instruction signal producing block sets a level of the pattern forming instruction signal, in an instruction period including each of the specific periods in the quarter angle regions of the triangular wave quasi-comparison pattern in which a sum of the second periods is longer than a sum of the first periods, at an instruction value which is lower than the maximum value by a product of the maximum value and a ratio of a subtracted value, obtained by subtracting a quarter of the cycle duration of the carrier signal from the specific period, to the quarter of the cycle duration of the carrier signal, and at another instruction value which is lower than the maximum value by a product of the maximum value and a ratio of a subtracted value, obtained by subtracting the specific period from a quarter of the cycle duration of the carrier signal, to the quarter of the cycle duration of the carrier signal, when the specific period is shorter than the quarter of the cycle duration of the carrier signal,

when the specific period is shorter than the quarter of the cycle duration of the carrier signal, the pattern forming instruction signal producing block sets a level of the pattern forming instruction signal, in an instruction period including each of the specific periods in the quarter angle regions of the triangular wave quasi-comparison pattern in which a sum of the second periods is shorter than a sum of the first periods, at an instruction value which is higher than the minimum value by a product of the minimum value and a ratio of a subtracted value, obtained by subtracting a quarter of the cycle duration of the carrier signal from the specific period, to the quarter of the cycle duration of the carrier signal, when the specific period is longer than the quarter of the cycle duration of the carrier signal, and at another instruction value which is higher than the minimum value by a product of the minimum value and a ratio of a subtracted value, obtained by subtracting the specific period from a quarter of the cycle duration of the carrier signal, to the quarter of the cycle duration of the carrier signal,

a first intersection among a plurality of intersections, at which the pattern forming instruction signal intersects the carrier signal, is placed to be closest to each boundary,

a second intersection among the intersections is placed to be closest to each boundary, next to the first intersection,

a third intersection among the intersections is placed to be close to each boundary, next to the second intersection,

when the specific period is longer than the quarter of the cycle duration of the carrier signal, the control signal producing block changes a level of the control signal to another level, in synchronization with each of the boundaries of the repeated pattern, and continues the changed level of the control signal until a timing of the second intersection, and

when the specific period is shorter than the quarter of the cycle duration of the carrier signal, the control signal producing block changes a first level of the control signal to a second level, in synchronization with each of the boundaries of the repeated pattern, continues the changed level of the control signal until a timing of the first intersection, changes the second level of the control signal to the first level in synchronization with the timing of the first intersection, and continues the level of the control signal until a timing of the third intersection.

17. The control device according to claim 14, wherein the carrier signal producing block has a correcting unit that corrects a phase of the carrier signal according to a rotational angle of the machine.

18. The control device according to claim 14, wherein the pattern control unit further comprises;

an angle-based PWM signal producing section that controls the power inverter circuit such that the controlled voltage of the power inverter circuit is changed with time according to the selected triangular wave quasi-comparison pattern and a rotational angle of the machine, and

a selector which switches the control of the angle-based PWM signal producing section to the control of the control signal producing block when a time resolution in a detection of the rotational angle is longer than a predetermined value.

19. The control device according to claim 18, wherein the pattern control unit controls the selector to switch the control of the angle-based PWM signal producing section to the control of the control signal producing block in response to a first switching condition and to switch the control of the angle-based PWM signal producing section to the control of the control signal producing block in response to a second switching condition differing from the first switching condition.

20. The control device according to claim 1, wherein the power inverter circuit has a first switching element, connected with a positive electrode of a direct current power source to apply the high level of the controlled voltage to the electric rotating machine during an on period of the first switching element, and a second switching element electrically connected with a negative electrode of the direct current power source to apply the low level of the controlled voltage to the electric rotating machine during an on period of the second switching element, and the pattern control unit sets the first switching element in the on period in response to the first period of the selected triangular wave quasi-comparison pattern and sets the second switching element in the on period in response to the second period of the selected triangular wave quasi-comparison pattern.

21. A method of controlling a controlled variable of an electric rotating machine by controlling a power inverter circuit applying a controlled voltage to the electric rotating machine, comprising the steps of:

preparing a pattern having a level changed with time for each of values of a modulation factor;

determining phase information of the controlled voltage and an instructed value of the modulation factor;

selecting the pattern, corresponding to the instructed value of the modulation factor, from the patterns; and

controlling the controlled variable of the electric rotating machine by controlling the power inverter circuit such that the controlled voltage of the power inverter circuit is changed with time according to the selected pattern while adjusting a phase of the controlled voltage according to the phase information,

wherein the preparing step includes;

preparing a triangular wave having a cycle duration, which is equal to a value obtained by dividing an electrical angle cycle duration of the electric rotating machine by an integral number, and

preparing each pattern as a triangular wave quasi-comparison pattern so as to have both a first period of a first level, depending on the corresponding value of the modulation factor and including a timing synchronized with a crest point or a trough point of the triangular wave, and a second period of a second level, depending on the corresponding value of the modulation factor and including a timing synchronized with the other point of the triangular wave, and

wherein the controlling step includes;

controlling the power inverter circuit to apply a low level of the controlled voltage to the electric rotating machine in response to the first period of the selected triangular wave quasi-comparison pattern and to apply a high level of the controlled voltage to the electric rotating machine in response to the second period of the selected triangular wave quasi-comparison pattern.

22. The method according to claim 21, wherein the preparing step further includes:

preparing each triangular wave quasi-comparison pattern having a plurality of first periods, set at different lengths, in a first angle region of the pattern,

expressing magnitude of higher-order harmonic waves, existing in the controlled voltage and ranging to the order of a predetermined number, by the lengths of the first periods, and

determining the lengths of the first periods such that the magnitude of higher-order harmonic waves is minimized.

23. The method according to claim 22, wherein the preparing step further includes:

weighting an amplitude of each higher-order harmonic wave by a weighting factor such that the weighting factor is decreased with the order of the higher-order harmonic wave, and

determining the first periods of each triangular wave quasi-comparison pattern such that a sum of the weighted amplitudes of the higher-order harmonic waves is minimized.

24. The method according to claim 22, wherein the preparing step further includes:

preparing each triangular wave quasi-comparison pattern having a plurality of second periods, set at different lengths, in a second angle region of the pattern; and

determining the lengths of the second periods such that a pattern obtained by inverting the triangular wave quasi-comparison pattern having the first periods set at the first level and the second periods set at the second level in the second angle region is symmetric to the triangular wave quasi-comparison pattern in the first angle region with respect to a boundary between the first and second angle regions.