Control apparatus for three-phase rotary machine, and electric power steering apparatus

Patent metadata

Field	Value
Publication number	US-10532765-B2
Application number	US-201716077887-A
Country	US
Kind code	B2
Filing date	Jan 13, 2017
Priority date	Feb 17, 2016
Publication date	Jan 14, 2020
Grant date	Jan 14, 2020

Abstract

A control apparatus ( 10 ) for controlling a three-phase rotary machine ( 80 ) having two three-phase winding sets ( 801, 802 ) includes: two power converters ( 601, 602 ) outputting AC currents, having a same amplitude and a phase difference of (30±60×n) [deg], to the two winding sets; a harmonic component generator ( 20 ) superimposing a harmonic component on a phase current first harmonic component of a current command value; and two controllers ( 331, 332 ) calculating voltage command values for the two power converters according to the current command value. A combination of amplitudes of the phase current fifth and seventh harmonic components to reduce a peak of the phase current first harmonic component is defined as a fundamental amplitude. The harmonic component generator performs a harmonic amplitude reduction process to reduce a phase current peak reduction amount of the phase current first harmonic component from the fundamental amplitude according to a predetermined parameter, and to reduce an absolute value of an amplitude of the harmonic component.

First claim

The invention claimed is:

1. A control apparatus for controlling an operation of a three-phase rotary machine having two sets of three-phase windings, the control apparatus for the three-phase rotary machine comprising:
two power converters that respectively correspond to the two sets of the windings, and output AC currents, having a same amplitude and a phase difference of (30±60×n)[deg] between AC currents, to the two sets of the windings according to operations of a plurality of switching elements, n being an integer;
a harmonic component generator that generates at least one of a phase current fifth harmonic component having a frequency five times higher than a frequency of a phase current first harmonic component of a current command value flowing through the three-phase rotary machine and a phase current seventh harmonic component having a frequency seven times higher than the frequency of the phase current first harmonic component, as a harmonic component to be superimposed on the phase current first harmonic component; and
two controllers that respectively calculates voltage command values for the two power converters according to the current command value obtained by superimposing the harmonic component on the phase current first harmonic component, wherein:
a combination of an amplitude of the phase current fifth harmonic component and an amplitude of the phase current seventh harmonic component generated by the harmonic component generator to reduce a peak of the phase current first harmonic component is defined as a fundamental amplitude; and
the harmonic component generator performs a harmonic amplitude reduction process to reduce a phase current peak reduction amount, which is a peak reduction amount of the phase current first harmonic component, from the fundamental amplitude according to a predetermined parameter, and to reduce an absolute value of an amplitude of the harmonic component.

2. The control apparatus for a three-phase rotary machine according to claim 1 , wherein:
the harmonic component generator uses a parameter, relating to a tradeoff relationship between a reduction of the peak of the phase current first harmonic component and a reduction of a torque ripple generated in the three-phase rotary machine when the harmonic component is superimposed, as the predetermined parameter of the harmonic amplitude reduction process.

3. The control apparatus for a three-phase rotary machine according to claim 1 , wherein:
the harmonic component generator performs the harmonic amplitude reduction process when an element temperature of the switching elements is equal to or lower than a predetermined temperature threshold or when a current flowing through the three-phase rotary machine is equal to or lower than a predetermined current threshold.

4. The control apparatus for a three-phase rotary machine according to claim 1 , wherein:
the harmonic component generator performs the harmonic amplitude reduction process when a motor torque of the three-phase rotary machine is equal to or larger than a predetermined torque threshold.

5. The control apparatus for a three-phase rotary machine according to claim 1 , wherein:
the harmonic component generator performs the harmonic amplitude reduction process when a rotation speed of the three-phase rotary machine is equal to or higher than a predetermined rotation speed threshold.

6. The control apparatus for a three-phase rotary machine according to claim 1 , further comprising:
an element temperature estimator having:
a first-order delay calculator that calculates a first-order delay response using a gain and a time constant in response to an input of a current square value of a current relating to energization of the three-phase rotary machine or an input of a time average of an integrated value of the current square value, and outputs the first-order delay response as a temperature change amount;
a response constant determiner that determines a response constant, which is the gain and the time constant of the first-order delay calculator, according to the phase current peak reduction amount; and
an adder that adds the temperature change amount to an element detection temperature of the switching elements detected by one or more temperature sensors, and outputs an addition result as an element estimation temperature of the switching elements.

7. The control apparatus for a three-phase rotary machine according to claim 6 , wherein:
the response constant determiner increases the gain and reduces the time constant as the phase current peak reduction amount becomes smaller.

8. The control apparatus for a three-phase rotary machine according to claim 7 , further comprising:
a current limiter that limits the current command value according to the element estimation temperature calculated by the element temperature estimator.

9. The control apparatus for a three-phase rotary machine according to claim 7 , wherein:
the harmonic component generator uses the element estimation temperature calculated by the element temperature estimator as the parameter of the harmonic amplitude reduction process.

10. The control apparatus for a three-phase rotary machine according to claim 7 , wherein:
the element temperature estimator further includes a zero rotation determiner that determines a zero rotation state in which the three-phase rotary machine is energized and a rotation of the three-phase rotary machine is stopped; and
the response constant determiner determines the response constant according to the phase current peak reduction amount when the zero rotation determiner determines that the three-phase rotary machine is in the zero rotation state.

11. The control apparatus for a three-phase rotary machine according to claim 1 , wherein:
the harmonic component generator generates a harmonic component by combining the phase current fifth harmonic component and the phase current seventh harmonic component, and sets a largest reduction amount amplitude, which is a combination of an amplitude of the phase current fifth harmonic of 12.5% and an amplitude of the phase current seventh harmonic of 5.3% and at which the phase current peak reduction amount becomes a largest amount, as the fundamental amplitude.

12. The control apparatus for a three-phase rotary machine according to claim 11 , wherein:
in the harmonic amplitude reduction process, the harmonic component generator reduces an absolute value of the amplitude of the phase current fifth harmonic component and an absolute value of the amplitude of the phase current seventh harmonic component from the fundamental amplitude according to an optimal amplitude line, which is provided by combining the amplitude of the phase current seventh harmonic component with each amplitude of the phase current fifth harmonic component to maximize the phase current peak reduction amount.

13. The control apparatus for a three-phase rotary machine according to claim 12 , wherein:
in the harmonic amplitude reduction process, when a rotation speed of the three-phase rotary machine is lower than a predetermined rotation threshold, the harmonic component generator generates the harmonic component according to a combination of the amplitudes in a range where:
the amplitude of the phase current fifth harmonic is defined as x;
the amplitude of the phase current seventh harmonic is defined as y;
x is expressed in a percentage, and y is expressed in a percentage;
x and y satisfy a simultaneous inequality of:
8.1≤ x≤ 12.5;

y≤ 5.3; and
(0.54 x -3.8)≤ y ≤(1.00 x -5.0).

14. An electric power steering apparatus comprising:
a three-phas

Assignees

• Denso Corp

Inventors

• Kano Ryo
• Suzuki Takashi

Classifications

• H02P29/50

  Reduction of harmonics · CPC title

• B62D5/046

  Controlling the motor · CPC title

• B62D5/0463 Primary

  calculating assisting torque from the motor based on driver input · CPC title

• B60R16/0232

  for measuring vehicle parameters and indicating critical, abnormal or dangerous conditions · CPC title

• H02P25/22

  Multiple windings; Windings for more than three phases · CPC title