Control methods and systems for motors and generators operating in a stacked configuration

Patent metadata

Field	Value
Publication number	US-10090786-B2
Application number	US-201615016038-A
Country	US
Kind code	B2
Filing date	Feb 4, 2016
Priority date	Dec 19, 2013
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

While motors or generators stacked in series may allow for higher operating voltages, such motors or generators may also exhibit instability. To minimize instability, the motors or generators may be controlled to have an approximately equal current. An example motor system may include motor stacks connected in series, each motor stack exhibiting a respective stack voltage and a respective differential power (based on a difference in power between motors in the motor stack). A control system may average the stack voltages to generate an average stack voltage and generate a nominal stack power corresponding to each stack voltage. The control system may receive the differential powers, combine each differential power and nominal stack power for the respective motor stack to generate first and a second motor powers, and control each motor stack using the first and second motor powers.

First claim

We claim:

1. A system comprising:
a motor system comprising a plurality of motor stacks connected in series, wherein each motor stack comprises a first motor and a second motor, and wherein the motor system is configured to (i) exhibit a plurality of stack voltages, wherein each stack voltage corresponds to a respective motor stack in the plurality of motor stacks and (ii) exhibit a plurality of differential powers, wherein each differential power corresponds to a respective motor stack in the plurality of motor stacks, and wherein each differential power is given by one half of a power difference between the first motor and the second motor in the respective motor stack;
and a control system configured to (i) generate an average stack voltage of the plurality of stack voltages, (ii) generate a plurality of nominal stack powers based at least in part on the average stack voltage, wherein each nominal stack power corresponds to a respective motor stack, and (iii) control the motor system based at least in part on the plurality of stack voltages the plurality of nominal stack powers and based at least in part on the plurality of differential powers, such that the motor system exhibits a plurality of currents, wherein each current corresponds to a respective motor stack of the plurality of motor stacks and is approximately equal to the other currents of the plurality of currents so as to stabilize the motor system.

2. The system of claim 1 , wherein the control system comprises:
an averager configured to average the stack voltages to generate the average stack voltage;
a first circuit configured to generate, based at least in part on the average stack voltage, the nominal stack power corresponding to each stack voltage; and
a second circuit configured, for each motor stack, to combine the corresponding differential power and the corresponding nominal stack power to generate both: (a) a first motor power corresponding to the first motor in the motor stack and (b) a second motor power corresponding to the second motor in the motor stack.

3. The system of claim 2 , wherein, for each motor stack, the control system is configured to control the first and the second motors in the motor stack based on the first and second motor powers for the motor stack.

4. The system of claim 1 , wherein the system comprises an airborne wind turbine system configured to generate electrical energy from wind.

5. The system of claim 4 , further comprising:
a ground station;
an aerial vehicle; and
a tether connecting the aerial vehicle to the ground station.

6. The system of claim 5 , wherein the aerial vehicle is configured to transmit electrical energy to the ground station via the tether.

7. The system of claim 5 , wherein the ground station is configured to transmit electrical energy to the aerial vehicle via the tether.

8. The system of claim 5 , wherein the motor system is included in the ground station.

9. The system of claim 5 , wherein the motor system is included in the aerial vehicle.

10. A method comprising:
receiving a set of stack voltages from a motor system that comprises a plurality of motor stacks connected in series, wherein each motor stack comprises a first motor and a second motor, and wherein each stack voltage corresponds to a respective motor stack in the plurality of motor stacks, and wherein each differential power is given by one half of a power difference between the first motor and the second motor in the respective motor stack;
receiving a set of differential powers, wherein each differential power corresponds to a respective motor stack in the plurality of motor stacks;
generating an average stack voltage of the plurality of stack voltages;
generating a set of nominal stack powers based at least in part on the average stack voltage, wherein each nominal stack power corresponds to a respective motor stack;
and controlling the motor system based at least in part on the set of nominal stack powers and based at least in part on the set of differential powers, such that the motor system exhibits a plurality of currents, wherein each current corresponds to a respective motor stack of the plurality of motor stacks and is approximately equal to the other currents of the plurality of currents so as to stabilize the motor system.

11. The method of claim 10 , wherein generating the nominal stack power corresponding to each stack voltage comprises, for each stack voltage comprises:
subtracting the average stack voltage from the stack voltage to generate an error term,
determining a positive term based on the error term, and
summing the positive term with a nominal power for the motor to generate the nominal stack power;
and wherein controlling the motor system based at least in part on the set of nominal stack powers and based at least in part on the set of differential powers comprises:
for each motor stack, combining the corresponding differential power and the corresponding nominal stack power to generate both a first motor power corresponding to the first motor in the motor stack and a second motor power corresponding to the second motor in the motor stack; and
for each motor stack, (i) controlling the first motor based on the first motor power corresponding to the motor stack and (ii) controlling the second motor based on the second motor power corresponding to the motor stack.

12. The method of claim 11 , wherein generating both the first motor power and the second motor power comprises, for each differential power:
generating both a positive differential power and a negative differential power from the differential power;
summing the positive differential power with the nominal stack power generated for the respective motor stack to generate the first motor power; and
summing the negative differential power with the nominal stack power generated for the respective motor stack to generate the second motor power.

13. A non-transitory computer-readable medium having stored therein instructions executable by a computing device to cause the computing device to perform functions comprising:
receiving a set of stack voltages from a motor system that comprises a plurality of motor stacks connected in series, wherein each motor stack comprises a first motor and a second motor, and wherein each stack voltage corresponds to a respective motor stack in the plurality of motor stacks, and wherein each differential power is given by one half of a power difference between the first motor and the second motor in the respective motor stack;
receiving a set of differential powers, wherein each differential power corresponds to a respective motor stack in the plurality of motor stacks;
and generating an average stack voltage of the plurality of stack voltages;
generating a set of nominal stack powers based at least in part on the average stack voltage, wherein each nominal stack power corresponds to a respective motor stack; and controlling the motor system based at least in part on the set of nominal stack powers and based at least in part on the set of differential powers, such that the motor system exhibits a plurality of currents, wherein each current corresponds to a respective motor stack of the plurality of motor stacks and is approximately equal to the other currents of the plurality of currents so as to stabilize the motor system.

14. The non-transitory computer-readable medium of claim 13 , wherein each motor stack of the plurality of motor stacks comprises a first motor and a second motor, and wherein controlling the motor system based at least in part on the set of nominal stack powers and based at least in part on the s

Assignees

• X Dev Llc

Inventors

• Goessling Andrew David
• Casey Leo Francis

Classifications

• Y02E10/70

  Wind energy · CPC title

• H02S10/12

  Hybrid wind-PV energy systems · CPC title

• H02P5/685 Primary

  electrically connected in series, i.e. carrying the same current · CPC title

• F03D5/00

  Other wind motors (controlling thereof F03D7/00) · CPC title

• F03D9/30

  Wind motors specially adapted for installation in particular locations (means for mounting or supporting wind motors F03D13/20) · CPC title