Derating vehicle electric drive motor and generator components

• US 9,018,878 B2
• Filed: 07/23/2012
• Issued: 04/28/2015
• Est. Priority Date: 07/23/2012
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Hendrickson, Matthew, Xie, Bo
• Primary Examiner(s): DUDA, RINA I
• Application Number:
  US13/555,563
• Publication Number:
  US 20140021898A1
• Time in Patent Office: 1,009 Days
• Field of Search: 318/461, 318/471, 318/432, 318/139
• US Class Current: 318/461
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 15/007 Physical arrangements or structures of drive train converters specially adapted for the propulsion motors of electric vehicles
• CPC Class Codes: B60L 2200/36 Vehicles designed to transport cargo, e.g. trucks
• CPC Class Codes: B60L 2210/30 AC to DC converters
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2220/44 Wheel Hub motors, i.e. integrated in the wheel hub
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/425 Temperature
• CPC Class Codes: B60L 2240/427 Voltage
• CPC Class Codes: B60L 2240/429 Current
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/527 Voltage
• CPC Class Codes: B60L 2240/529 Current
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 3/0023 Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
• CPC Class Codes: B60L 3/0061 relating to electrical machines
• CPC Class Codes: B60L 3/04 : Cutting off the power supply under fault conditions protective devices and circuit arrangements in general H01H; H02H
• CPC Class Codes: B60L 3/12 : Recording operating variables ; Monitoring of operating variables
• CPC Class Codes: B60L 50/13 : using AC generators and AC motors
• CPC Class Codes: B60L 7/006 : Dynamic electric braking by reversing current, i.e. plugging
• CPC Class Codes: B60L 7/06 : for vehicles propelled by ac motors
• CPC Class Codes: H02P 27/04 : using variable-frequency supply voltage, e.g. inverter or converter supply voltage
• CPC Class Codes: H02P 29/028 : the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault
• CPC Class Codes: H02P 29/032 : Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
• CPC Class Codes: H02P 29/60 : Controlling or determining the temperature of the motor or of the drive H02P29/02 takes precedence
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

A machine propelled by an electric motor and subject to a deration scheme is described wherein deration is specified by a combination of a temperature signal indicating a degree to which a machine component is overheating. The machine includes an electronic controller that receives a temperature signal indicative of a current temperature status of the electric motor. The electronic controller receives a motor speed signal indicative of a current speed status of the electric motor. The electronic controller calculates, in accordance with a derating scheme, a deration value for the electric motor, the deration value being determined by applying a set of current operating state parameter values to the derating scheme. The set of current operating state parameters include: a motor speed parameter value; and a temperature parameter value.

Claims

1. A machine propelled by an electric motor, the machine comprising:

a drive wheel connected to a rotating interface of the electric motor for operating at least in a propel mode wherein the electric motor delivers rotational force to the drive wheel;

an electronic controller configured with computer executable instructions for performing the steps of;

receiving a temperature signal indicative of a current temperature status of the electric motor;

receiving a motor speed signal indicative of a current speed status of the electric motor;

calculating, in accordance with a derating scheme, a deration value for the electric motor, the deration value being determined by applying values of a set of current operating state parameters to the derating scheme, the set of current operating state parameters comprising;

a motor speed parameter having a value derived from the motor speed signal; and

a temperature parameter having a value derived from temperature signal

wherein, during the calculating step, the deration value specifies a torque limit for the electric motor when the current speed status corresponds to a low motor speed range,

wherein, during the calculating step, the deration value specifies a power limit for the electric motor when the current speed status corresponds to a high motor speed range, and

wherein, during the calculating step, the deration value is a constant, non-zero, value over a specified range for the temperature parameter value.

2. The machine of claim 1 wherein the electronic controller is configured to convert the power limit to a torque limit.

3. The machine of claim 1 wherein, during the calculating step, the deration value is a constant value over a specified range for the motor speed parameter value.

4. The machine of claim 3 wherein the specified range for the motor speed parameter value constitutes a middle motor speed range.

5. The machine of claim 4 wherein the constant value, when the motor speed parameter value corresponds to the middle motor speed range, specifies a zero level of derating the electric motor.

6. The machine of claim 1 wherein the set of current operating state parameters comprises a temperature direction parameter value indicating whether the temperature value is lowering.

7. The machine of claim 6 wherein the deration scheme specifies:

relatively smaller deration values when the temperature direction parameter indicates an increasing temperature trend, and

relatively larger deration values when the temperature direction parameter indicates a decreasing temperature trend.

8. The machine of claim 1 wherein the set of current operating state parameters comprises a motor mode parameter value indicating whether the motor is operating in a propel or retard mode.

9. The machine of claim 1 wherein the electronic controller includes a motor temperature control that enters a motor overheating state at a higher temperature than a temperature at which the motor temperature control leaves the motor overheating state.

10. The machine of claim 1 wherein the machine further comprises:

a temperature sensor positioned proximate the electric motor, the temperature sensor being configured to sense a temperature of a motor component susceptible to overheating, and wherein the temperature sensor provides a signal corresponding to the temperature signal indicative of a current temperature status of the electric motor.

11. The machine of claim 1 wherein the temperature signal is rendered from a thermo model.

12. The machine of claim 1 wherein during the calculating, for a particular value of the temperature parameter, a particular deration schedule is selected based upon a current value of the motor speed parameter.

13. A machine propelled by an electric motor, the machine comprising:

a drive wheel connected to a rotating interface of the electric motor for operating at least in a propel mode wherein the electric motor delivers rotational force to the drive wheel;

an electronic controller configured with computer executable instructions for performing the steps of;

receiving a temperature signal indicative of a current temperature status of the electric motor;

receiving a motor speed signal indicative of a current speed status of the electric motor;

calculating, in accordance with a derating scheme, a deration value for the electric motor, the deration value being determined by applying values of a set of current operating state parameters to the derating scheme, the set of current operating state parameters comprising;

a motor speed parameter having a value derived from the motor speed signal, and

a temperature parameter having a value derived from temperature signal,

wherein, during the calculating step, a motor overload index-based deration value is further specified in accordance with a sensed phase current level over a period of time and a thermal model representative of the electric motor operating under high load conditions for an period of time.

14. A machine propelled by an electric motor, the machine comprising:

a drive wheel connected to a rotating interface of the electric motor for operating at least in a propel mode wherein the electric motor delivers rotational force to the drive wheel;

an electronic controller configured with computer executable instructions for performing the steps of;

receiving a temperature signal indicative of a current temperature status of the electric motor;

receiving a motor speed signal indicative of a current speed status of the electric motor;

calculating, in accordance with a derating scheme, a deration value for the electric motor, the deration value being determined by applying values of a set of current operating state parameters to the derating scheme, the set of current operating state parameters comprising;

a motor speed parameter having a value derived from the motor speed signal, and

a temperature parameter having a value derived from temperature signal; and

a generator providing power for the electric motor, and wherein, during the calculating step, a generator temperature-based deration value is rendered based upon a generator temperature signal.

15. The machine of claim 14 wherein the electronic controller includes a generator thermo control that enters a generator overheating state at a higher temperature than a temperature at which the generator thermo control leaves the generator overheating state.

16. A machine propelled by an electric motor, the machine comprising:

a drive wheel connected to a rotating interface of the electric motor for operating at least in a propel mode wherein the electric motor delivers rotational force to the drive wheel;

an electronic controller configured with computer executable instructions for performing the steps of;

receiving a temperature signal indicative of a current temperature status of the electric motor;

receiving a motor speed signal indicative of a current speed status of the electric motor;

calculating, in accordance with a derating scheme, a deration value for the electric motor, the deration value being determined by applying values of a set of current operating state parameters to the derating scheme, the set of current operating state parameters comprising;

a motor speed parameter having a value derived from the motor speed signal, and

a temperature parameter having a value derived from temperature signal,

wherein a final torque limit value is calculated by the electronic controller by comparing torque limits rendered by a set of deration values generated by at least two controls from the set consisting of;

a generator thermo control, a motor temperature control, and a motor overload index control.

17. A method carried out on a machine propelled by an electric motor, the machine further comprising a drive wheel connected to a rotating interface of the electric motor for operating at least in a propel mode wherein the electric motor delivers rotational force to the drive wheel and an electronic controller configured with computer executable instructions, wherein the method comprises the steps of:

receiving a temperature signal indicative of a current temperature status of the electric motor;

receiving a motor speed signal indicative of a current speed status of the electric motor;

calculating, in accordance with a derating scheme, a deration value for the electric motor, the deration value being determined by applying values of a set of current operating state parameters to the derating scheme, the set of current operating state parameters comprising;

a motor speed parameter having a value derived from the motor speed signal; and

a temperature parameter having a value derived from temperature signal,

wherein, during the calculating step, the deration value specifies a torque limit for the electric motor when the current speed status corresponds to a low motor speed range,

wherein, during the calculating step, the deration value specifies a power limit for the electric motor when the current speed status corresponds to a high motor speed range, and

wherein, during the calculating step, the deration value is a constant, non-zero, value over a specified range for the temperature parameter value.

18. The method of claim 17 wherein during the calculating, for a particular value of the temperature parameter, a particular deration schedule is selected based upon a current value of the motor speed parameter.

19. A non-transitory computer-readable medium including computer-executable instructions performed by an electronic controller on a machine propelled by an electric motor, the machine further comprising a drive wheel connected to a rotating interface of the electric motor for operating at least in a propel mode wherein the electric motor delivers rotational force to the drive wheel, and wherein the computer-executable instructions facilitate performing, by the electronic controller, the method comprising the steps of:

receiving a temperature signal indicative of a current temperature status of the electric motor;

receiving a motor speed signal indicative of a current speed status of the electric motor;

calculating, in accordance with a derating scheme, a deration value for the electric motor, the deration value being determined by applying values of a set of current operating state parameters to the derating scheme, the set of current operating state parameters comprising;

a motor speed parameter having a value derived from the motor speed signal; and

a temperature parameter having a value derived from temperature signal,

wherein, during the calculating step, the deration value specifies a torque limit for the electric motor when the current speed status corresponds to a low motor speed range,

wherein, during the calculating step, the deration value specifies a power limit for the electric motor when the current speed status corresponds to a high motor speed range, and

wherein, during the calculating step, the deration value is a constant, non-zero, value over a specified range for the temperature parameter value.

20. The non-transitory computer-readable medium of claim 19 wherein during the calculating, for a particular value of the temperature parameter, a particular deration schedule is selected based upon a current value of the motor speed parameter.