Inverter for controlling an electric machine without prior characterization

Patent metadata

Field	Value
Publication number	US-11689142-B2
Application number	US-202117643831-A
Country	US
Kind code	B2
Filing date	Dec 12, 2021
Priority date	May 20, 2021
Publication date	Jun 27, 2023
Grant date	Jun 27, 2023

Abstract

A control module comprises software instructions for execution by an electronic data processor. An inductance estimator is configured to estimate direct inductance and quadrature inductance associated with the electric machine based on a first set of equations that assume constant rotor resistance and constant magnetic flux. A torque estimator is configured to estimate an observed torque associated with a rotor of the electric machine based a commanded direct-axis voltage and a commanded quadrature-axis voltage, where the observed torque is proportional to the observed power consumption of the electric machine. A pulse-width-modulation (PWM) module is configured to provide pulse-width modulated signals to the electric machine based on the commanded direct-axis voltage and a commanded quadrature-axis voltage. A back-electromotive force adjustment is derived from an estimated, observed torque and a commanded torque.

First claim

The following is claimed:

1. An inverter for controlling an electric machine, the inverter comprising:
a switching circuit comprising a low-side switch and a high-side switch, the low-side switch and the high-side switching each having a control terminal and two switched terminals;
a driver circuit for providing control signals to the control terminals of the switching circuit;
an electronic data processor;
a data storage device in communication with the electronic data processor;
a control module stored in the data storage device, the control module comprising software instructions for execution by the electronic data processor, the control module comprising:
an inductance estimator to estimate direct inductance and quadrature inductance associated with the electric machine based on a first set of equations that assume constant rotor resistance and constant magnetic flux;
a torque estimator to estimate an observed torque associated with a rotor of the electric machine based a commanded direct-axis voltage and a commanded quadrature-axis voltage, where the observed torque is proportional to the observed power consumption of the electric machine;
a pulse width modulation module for provided pulse-width modulated signals to the electric machine based on the commanded direct-axis voltage and a commanded quadrature-axis voltage;
and
a back-electromotive force module configured to determine an adjustment derived from an estimated, observed torque and a commanded torque.

2. The inverter according to claim 1 wherein the first set of equations for estimation of the direct inductance (Ld) and quadrature inductance (Lq) comprise the following:

v
d

=

R
s

⁢

i
d

-

L
q

⁢

i
q

⁢

ω
e

⁢

L
q

=

R
s

⁢

i
d

-

v
d

i
q

⁢

ω
e

⁢

v
q

=

R
s

⁢

i
q

+

L
d

⁢

i
d

⁢

ω
e

+

λ
f

⁢

ω
e

⁢

L
d

=

v
q

-

λ
f

⁢

ω
e

-

R
s

⁢

i
q

ω
e

⁢

i
d

where:
L d is direct-axis inductance; L q is quadrature-axis inductance; v d or V d is direct-axis voltage; vq or V q means quadrature-axis voltage; R s is stator resistance; i d or I d is direct-axis current; i q or I q is quadrature-axis current; λ f is the back emf constant; and ω e is the electrical speed of the rotor.

3. The inverter according to claim 1 wherein upon electrically connecting an electric machine to a controller, the inverter operates based on initial electric machine parameters that are read or retrieved from a data storage device.

4. The inverter according to claim 3 wherein during operation of the electric machine based on the initial electric machine parameters, the inductance estimator of the controller is configured to estimate an estimated direct inductance and an estimated quadrature inductance associated with the electric machine based on a first set of equations that assume a default or initial rotor resistance and a default or initial magnetic flux, or a combination of default or initial back emf constant and number pole pairs.

5. The inverter according to claim 1 wherein the inductance estimation module estimates the estimated direct inductance and estimated quadrature inductance to be consistent with an operational point or region of the maximum torque per amp curve, a field weakening region, or both based on respective commanded direct-axis voltage (or current) and a commanded quadrature-axis voltage (or current).

6. The inverter according to claim 1 wherein the torque estimator is configured to estimate an observed torque measurement associated with a rotor of the electric machine based on measured direct-axis current at the electric machine terminals, measured quadrature-axis current at the electric machine terminals, estimated electrical rotor speed, the respective commanded direct-axis voltage (or current) and a commanded quadrature-axis voltage (or current) that are associated with a commanded torque, where the observed torque measurement is gen

Assignees

• Deere & Co

Inventors

• White Lauren M
• Wu Long
• Thyagarajan Lav
• Li Danielle
• Johnson Scott C

Classifications

• H02P23/14

  Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage · CPC title

• H02P27/08 Primary

  with pulse width modulation · CPC title

• H02P21/22 Primary

  Current control, e.g. using a current control loop · CPC title

• H02P21/14

  Estimation or adaptation of machine parameters, e.g. flux, current or voltage · CPC title