Motor control for stability and power supply protection

Patent metadata

Field	Value
Publication number	US-9553528-B2
Application number	US-201514801398-A
Country	US
Kind code	B2
Filing date	Jul 16, 2015
Priority date	Jul 2, 2013
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

A method and apparatus for controlling a motor. The motor comprises windings. A switch bridge comprising a plurality of switches is configured to couple a power source to the windings. A motor controller is configured to control the plurality of switches. An undesired condition identifier is configured to identify an undesired condition when the motor is providing power to the power source, wherein the undesired condition is defined with respect to a characteristic of the power source. An undesired condition reducer is configured to reduce the undesired condition in response to identifying the undesired condition by the undesired condition identifier.

First claim

What is claimed is:

1. An apparatus, comprising:
a motor comprising windings;
a switch bridge comprising a plurality of switches configured to couple a power source to the windings;
a motor controller configured to control the plurality of switches and a duty cycle, wherein a number of the plurality of switches in the switch bridge is closed during the duty cycle to provide a current between the power source and the windings in response to a commanded current;
an undesired condition identifier configured to identify an undesired condition in the apparatus when the motor is providing power to the power source, wherein the undesired condition is defined with respect to a characteristic of the power source, and wherein the undesired condition is identified when the commanded current is greater than a current limit for the power source; and
an undesired condition reducer configured to reduce the undesired condition in response to identifying the undesired condition in the apparatus by the undesired condition identifier, wherein the undesired condition reducer is configured to set the commanded current based on the current limit for the power source when the undesired condition is identified when the commanded current is greater than the current limit for the power source.

2. The apparatus of claim 1 , wherein:
in being configured to identify the undesired condition in the apparatus when the motor is providing the power to the power source, the undesired condition identifier is configured to identify the undesired condition in the apparatus when a voltage across the windings is greater than a first voltage threshold, wherein the first voltage threshold is defined with respect to an output voltage of the power source; and
in being configured to reduce the undesired condition in response to identifying the undesired condition in the apparatus, the undesired condition reducer is configured to direct a current in the windings to ground via a resistor in response to identifying the undesired condition in the apparatus.

3. The apparatus of claim 2 , wherein the first voltage threshold is approximately equal to the output voltage of the power source.

4. The apparatus of claim 2 , wherein:
the undesired condition identifier is further configured to identify when the voltage across the windings is less than a second voltage threshold, wherein the second voltage threshold is lower than the first voltage threshold; and
the undesired condition reducer is configured to cease directing the current in the windings to ground in response to identifying when the voltage across the windings is less than the second voltage threshold.

5. The apparatus of claim 2 , wherein:
the resistor is a variable resistor; and
the undesired condition reducer is further configured to select a resistance of the variable resistor in response to a level of the current in the windings.

6. The apparatus of claim 5 , wherein:
the resistor comprises a plurality of resistors in parallel; and
the undesired condition reducer is further configured to select a number of resistors in the plurality of resistors through which the current in the windings is directed to ground based on temperatures of the plurality of resistors.

7. The apparatus of claim 1 , wherein:
the current limit for the power source is variable;
the power source comprises a battery; and
the undesired condition identifier is further configured to select a value for the current limit based on feedback from a cell balancer circuit for the battery.

8. The apparatus of claim 1 , wherein the apparatus is on an aircraft.

9. A method of controlling a motor comprising:
controlling a plurality of switches in a switch bridge to couple a battery to windings of the motor, wherein a duty cycle during which a number of the plurality of switches are closed to provide a current between the battery and the windings is limited such that the current between the battery and the windings does not exceed a variable current limit for the battery, wherein a value for the variable current limit is selected based on feedback from a cell balancer circuit for the battery.

10. The method of claim 9 further comprising:
determining when a commanded current is greater than the value for the variable current limit for the battery;
setting the commanded current based on the value for the variable current limit for the battery when the commanded current is greater than the value for the variable current limit for the battery; and
controlling the duty cycle in response to the commanded current.

11. The method of claim 9 , wherein the current between the battery and the windings is the current between the motor and the battery when the motor is providing power to the battery.

12. The method of claim 9 , wherein the current between the battery and the windings is the current between the battery and the motor when power is provided from the battery to the motor.

13. An apparatus comprising:
a motor comprising windings;
a switch bridge comprising a plurality of switches configured to couple the windings to a battery having a variable current limit, wherein a value for the variable current limit is selected based on feedback from a cell balancer circuit for the battery;
a motor controller configured to limit a current between the battery and the windings during a duty cycle by controlling the plurality of switches such a number of the plurality of switches are closed to provide a current between the battery and the windings that does not exceed the value for the variable current limit.

14. The apparatus of claim 13 further comprising:
an undesired condition identifier configured to identify when a commanded current is greater than the value for the variable current limit; and
wherein the motor controller is further configured to set the commanded current based on the value for the variable current limit when the commanded current is greater than the value for the variable current limit, and to control the duty cycle in response to the commanded current.

15. The apparatus of claim 13 , wherein the current between the battery and the windings is the current between the motor and the battery when the motor is providing power to the battery.

16. The apparatus of claim 13 , wherein the current between the battery and the windings is the current between the battery and the motor when power is provided from the battery to the motor.

17. A method of controlling a motor comprising:
controlling a plurality of switches in a switch bridge according to a duty cycle, wherein a number of the plurality of switches in the switch bridge is closed during the duty cycle to provide a current between a power source and windings of the motor in response to a commanded current;
identifying an undesired condition when the motor is providing power to the power source, wherein the undesired condition is defined with respect to a characteristic of the power source, wherein the undesired condition comprises a condition when the commanded current is greater than a current limit for the power source; and
in response to identifying the undesired condition comprising the commanded current being greater than a current limit for the power source, setting the commanded current based on the current limit for the power source to reduce the undesired condition.

18. The method of claim 17 , further comprising:
identifying the undesired condition when the motor is providing power to the power source, wherein the undesired condition comprises a condition when a voltage across the windi

Assignees

• Boeing Co

Inventors

• Benson Christopher Pete
• Cameron Douglas C

Classifications

• H02P6/085

  in a bridge configuration · CPC title

• B60L58/22

  Balancing the charge of battery modules · CPC title

• H02P29/032

  Preventing damage to the motor, e.g. setting individual current limits for different drive conditions · CPC title

• B60L2240/529

  Current · CPC title

• B60L3/003

  relating to inverters · CPC title