System and method for an inverter for self-excitation of an induction machine

Patent metadata

Field	Value
Publication number	US-10224849-B2
Application number	US-201715406639-A
Country	US
Kind code	B2
Filing date	Jan 13, 2017
Priority date	Jun 6, 2016
Publication date	Mar 5, 2019
Grant date	Mar 5, 2019

Abstract

A voltage difference is determined between the observed voltage and a reference direct current bus voltage. A quadrature-axis (q-axis) voltage command is outputted based on a current difference derived from the voltage difference. A commanded direct-axis (d-axis) voltage is determined based on a measured d-axis current and a determined d-axis reference current derived from a mathematical relationship between d-axis residual voltage, the observed voltage and the commanded q-axis voltage, where residual voltage is proportional to a function of the observed voltage and the commanded q-axis voltage. An inverse Parks transformation module or a data processor provides one or more phase voltage command based on inverse Parks transform of the commanded voltages.

First claim

The following is claimed:

1. A method of controlling an inverter coupled to a generator, the method comprising:
measuring an observed voltage across direct current voltage terminals;
determining a voltage difference between the observed voltage and a reference DC bus voltage;
outputting a quadrature-axis (q-axis) voltage command based on a current difference derived from the voltage difference;
determining a commanded direct-axis (d-axis) voltage based on a measured d-axis current and a determined d-axis reference current derived from a mathematical relationship between d-axis residual voltage, the observed voltage and the commanded q-axis voltage in which the d-axis residual voltage is proportional to a function of the observed voltage and the commanded q-axis voltage; and
providing phase voltage command based on inverse Parks transform of the commanded voltages.

2. The method according to claim 1 wherein outputting the q-axis voltage command further comprises:
generating a reference q-axis current command (I q ref ) based on the voltage difference difference between the observed voltage and the reference DC bus voltage;
measuring a q-axis current (I q measured ); and
determining the current difference between the measured q-axis command current and the reference q-axis current command (I q ref ).

3. The method according to claim 1 wherein the determining the commanded d-axis voltage (V d ) further comprises:
determining a d-axis residual voltage (V d residual ) in accordance with a following equation as the relationship:

V
d
residual

=

(

m
⁢

⁢

V

D
⁢

⁢
C

measured

)

2

3

-

V
q
2

where:
m is a modulation index which is between zero and approximately 1,
V DC measured is the measured voltage of or between the direct current terminals, and
V q is the quadrature-axis voltage command; and
determining the dxzd-axis reference current (I q ref ) for the corresponding residual d-axis voltage (V d residual ) based on a magnetizing curve or K-factor lookup table stored in a data storage device.

4. The method according to claim 1 wherein the relationship adheres to a following equation:

V
d
residual

=

(

m
⁢

⁢

V

D
⁢

⁢
C

measured

)

2

3

-

V
q
2

where:
m is a modulation index which is between zero and approximately 1,
V DC measured is the measured voltage of or between the direct current terminals, and
Vq is the quadrature-axis voltage command.

5. The method according to claim 2 wherein the providing the phase voltage commands further comprises determining the parks transformation in accordance with a following equation of the rotor field orientation:
θ e =θ rotor +∫ω slip dt,

where θ e is an electrical angular position of the rotor;
where θ rotor is a mechanical angular position of the rotor;
and ω slip is an angular slip velocity of the rotor.

6. A method of controlling an inverter coupled to a generator, the method comprising:
measuring an observed voltage across direct current voltage terminals;
determining a voltage difference between the observed voltage and a reference DC bus voltage;
generating, by a controller, a reference q-axis current command (I q ref ) based on the voltage difference;
measuring a q-axis current (I q measured );
determining a current difference between the measured q-axis command current and the reference q-axis current command (I q ref );
outputting, by a current regulator, a q-axis voltage command (V q ) based on input of the current difference;
determining a d-axis residual voltage (V d residual ) in accordance with a following equation:

V
d
residual

=

(

m
⁢

⁢

V

D
⁢

⁢
C

measured

)

2

3

-

V
q
2

,

where:
m is a modulation index,
V DC measured is the measured voltage of or between the direct current terminals, and
V q is the quadrature-axis voltage command;
determining d-axis reference current (I d ref ) for the corresponding residual d-axis voltage (V d residual ) based on a magnetizing curv

Assignees

• Deere & Co

Inventors

• Dutta Sumit
• Thyagarajan Lav
• Wu Long
• Wanner Kent D

Classifications

• H02P21/09

  Field phase angle calculation based on rotor voltage equation by adding slip frequency and speed proportional frequency · CPC title

• H02P9/08 Primary

  Control of generator circuit during starting or stopping of driving means, e.g. for initiating excitation · CPC title

• H02P9/38

  Self-excitation by current derived from rectification of both output voltage and output current of generator · CPC title

• H02P9/36 Primary

  using armature-reaction-excited machines · CPC title

• H02P27/08 Primary

  with pulse width modulation · CPC title