# US 2013/0154524 A1 · Motor Control System For Limiting Regenerative Current

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- Number: US 2013/0154524 A1
- Document ID: US20130154524A1
- Status: Published application
- Kind: A1
- Application number: 13/327,327
- Filed: 2011-12-15
- Published: 2013-06-20
- Earliest claimed: 2011-12-15
- Assignees: Nexteer (Beijing) Technology Co., Ltd.
- Inventors: Julie A. Kleinau
- Web page: https://patentgrep.com/patent/US20130154524A1

## CPC

- H02P 3/18: for stopping or slowing an AC motor
- B60L 7/14: for vehicles propelled by AC motors
- H02P 21/0089: {using field weakening}
- Y02T 10/64: Electric machine technologies in electromobility
- Y02T 90/16: Information or communication technologies improving the operation of electric vehicles
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A motor control system is provided, including a motor and a control module. The motor operates at a rotational velocity, and creates a regenerative current. The motor has a target field weakening current that is configured for limiting the regenerative current to a threshold value. The control module is in communication with the motor. The control module receives a motor torque command. The control module includes control logic for identifying the target field weakening current based upon the motor torque command and the rotational velocity of the motor.

## Claims

### Claim 1

A motor control system, comprising:
a motor operating at a rotational velocity, the motor operating to create a regenerative current, the motor having a target field weakening current that is configured for limiting the regenerative current to a threshold value, the motor having a plurality of motor circuit parameters; and
a control module in communication with the motor, the control module receiving a motor torque command, comprising:
a control logic for identifying the target field weakening current based upon the motor torque command and the rotational velocity of the motor;
a control logic for determining a phase advance angle to generate the target field weakening current; and
a control logic for determining a motor voltage command based on the motor torque command, the rotational velocity and the plurality of motor circuit parameters, the motor voltage command applied at the phase advance angle.

### Claim 2 (depends on 1)

The motor control system as recited in claim 1, wherein the memory of the control module stores a 3D lookup table that is used to identify target field weakening current, wherein the 3D lookup table includes values for the target field weakening current based on the motor torque command and the rotational velocity of the motor.

### Claim 3 (depends on 1)

The motor control system as recited in claim 1, wherein the plurality of motor circuit parameters include a motor voltage constant Ke that is measured in volts/radian/second, a motor and control module output circuit resistance R that is measured in Ohms, and a motor synchronous inductance L that is measured in Henries, and wherein the phase advance angle based on at least the plurality of motor circuit parameters.

### Claim 4 (depends on 3)

The motor control system as recited in claim 3, wherein the control module includes control logic for calculating the target field weakening current, and wherein the target field weakening current is based on a value of the phase advance angle when a field weakening current is about zero amps.

### Claim 5 (depends on 4)

The motor control system as recited in claim 4, wherein the value of the phase advance angle when the field weakening current is about zero amps is calculated using the following equations:
T
CMD
=
K
e

I
q
V
q
=
RI
q
+
K
e

ω
m
V
d
=
-
ω
e

LI
q
δ
=
Tan
-
1

(
-
V
d
V
q
)
wherein TCMD is the motor torque command, Iq is a torque producing current, Vq is a q-axis applied motor voltage of the motor, and Vd is a d-axis applied motor voltage of the motor, ωm is a mechanical velocity of the motor, ωe is an electrical velocity of the motor, and δ is the phase advance angle.

### Claim 6 (depends on 5)

The motor control system as recited in claim 5, wherein the mechanical velocity ωm is the rotational velocity of the motor, and wherein the electrical velocity ωe is calculated by multiplying the mechanical velocity ωm by a number of poles Np of the motor, and dividing a product of the mechanical velocity ωm and the number of poles Np by two.

### Claim 7 (depends on 5)

The motor control system as recited in claim 5, wherein the motor voltage command is calculated using the following equation:
VLL=Sign(Vq)√{square root over (Vq2+Vd2)}
wherein VLL is the motor voltage command.

### Claim 8 (depends on 3)

The motor control system as recited in claim 3, wherein the target field weakening current is further based on a motor output power, wherein the motor output power is calculated using the following equation:
P
=
3
2

V
LL

I
p


k

Cos

(
α
-
δ
)
wherein Ipk is a peak motor current magnitude, α is a peak motor current angle, δ is the phase advance angle, and P is the motor output power.

### Claim 9 (depends on 8)

The motor control system as recited in claim 8, wherein the target field weakening current is further based on a gain factor, wherein the gain factor represents a relationship between a square root of an absolute value of the motor output power P when a field weakening current is zero to obtain the target field weakening current IdTARGET, and wherein the gain factor is calculated using the following equation:
IdTARGET=G√{square root over (|P|)}
wherein G is the gain factor.

### Claim 10 (depends on 1)

The motor control system as recited in claim 1, wherein the threshold value for the regenerative current is about 15 Amps.

### Claim 11 (depends on 1)

The motor control system as recited in claim 1, wherein the control module includes control logic for sending the motor voltage command that is applied at the phase advance angle to the motor.

### Claim 12

A motor control system, comprising:
a motor operating at a rotational velocity, the motor operating to create a regenerative current, the motor having a target field weakening current that is configured for limiting the regenerative current to a threshold value in a second quadrant and a fourth quadrant of operation, the motor having a plurality of motor circuit parameters, a torque producing current, and a field weakening current; and
a control module in communication with the motor, the control module receiving a motor torque command, comprising:
a control logic for identifying the target field weakening current based upon the motor torque command and the rotational velocity of the motor;
a control logic for monitoring the motor for the torque producing current and the field weakening current;
a control logic for calculating a target torque producing current based on the motor torque command;
a control logic for comparing the torque producing current with the target torque producing current and the field weakening current with the target field weakening current;
a control logic for determining a phase advance angle to generate the target field weakening current; and
a control logic for determining a motor voltage command based on the motor torque command, the rotational velocity and the plurality of motor circuit parameters, the motor voltage command applied at the phase advance angle.

### Claim 13 (depends on 12)

The motor control system as recited in claim 12, wherein the memory of the control module stores a 3D lookup table that is used to identify target field weakening current, wherein the 3D lookup table includes values for the target field weakening current based on the motor torque command and the rotational velocity of the motor.

### Claim 14 (depends on 12)

The motor control system as recited in claim 12, wherein the plurality of motor circuit parameters include a motor voltage constant Ke that is measured in volts/radian/second, a motor and control module output circuit resistance R that is measured in Ohms, and a motor synchronous inductance L that is measured in Henries, and wherein the phase advance angle based on at least the plurality of motor circuit parameters.

### Claim 15 (depends on 14)

The motor control system as recited in claim 14, wherein the control module includes control logic for calculating the target field weakening current, and wherein the target field weakening current is based on a value of the phase advance angle when a field weakening current is about zero amps.

### Claim 16 (depends on 15)

The motor control system as recited in claim 15, wherein the value of the phase advance angle when the field weakening current is about zero amps is calculated using the following equations:
T
CMD
=
K
e

I
q
V
q
=
RI
q
+
K
e

ω
m
V
d
=
-
ω
e

LI
q
δ
=
Tan
-
1

(
-
V
d
V
q
)
wherein TCMD is the motor torque command, Iq is the torque producing current, Vq is a q-axis applied motor voltage of the motor, and Vd is a d-axis applied motor voltage of the motor, ωm is a mechanical velocity of the motor, ωe is an electrical velocity of the motor, and δ is the phase advance angle, and wherein the control module includes control logic for adjusting the values of the of the q-axis applied motor voltage and the d-axis applied motor voltage based on the target torque producing current and the target field weakening current.

### Claim 17 (depends on 16)

The motor control system as recited in claim 16, wherein the mechanical velocity ωm is the rotational velocity of the motor, and wherein the electrical velocity ωe is calculated by multiplying the mechanical velocity ωm by a number of poles Np of the motor, and dividing a product of the mechanical velocity ωm and the number of poles Np by two.

### Claim 18 (depends on 16)

The motor control system as recited in claim 16, wherein the motor voltage command is calculated using the following equation:
VLL=Sign(Vq)√{square root over (Vq2+Vd2)}
wherein VLL is the motor voltage command, and wherein the control module includes control logic for sending the motor voltage command that is applied at the phase advance angle to the motor.

### Claim 19 (depends on 15)

The motor control system as recited in claim 15, wherein the target field weakening current is further based on a motor output power, wherein the motor output power is calculated using the following equation:
P
=
3
2

V
LL

I
p


k

Cos

(
α
-
δ
)
wherein Ipk is a peak motor current magnitude, α is a peak motor current angle, δ is the phase advance angle, and P is the motor output power.

### Claim 20 (depends on 19)

The motor control system as recited in claim 19, wherein the target field weakening current is further based on a gain factor, wherein the gain factor is calculated by scaling a square root of an absolute value of the motor output power P to obtain the target field weakening current IdTARGET, and wherein the gain factor is calculated using the following equation:
IdTARGET=G√{square root over (|P|)}
wherein G is the gain factor.