Integrated motor driver/controller with sensorless or sensored commutation

• US 9,748,882 B1
• Filed: 03/28/2016
• Issued: 08/29/2017
• Est. Priority Date: 03/28/2016
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Breheny, Sean Hugh, Hayward, Shaun Steven, Trenholme, Kevin John, Garcen, Sean, Sullivan, William Joseph
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US15/082,534
• Time in Patent Office: 519 Days
• Field of Search: 318 34
• CPC Class Codes: B65G 1/0492 with cars adapted to travel in storage aisles
• CPC Class Codes: H02P 21/06 Rotor flux based control involving the use of rotor position or rotor speed sensors
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 3/06 for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter
• CPC Class Codes: H02P 6/14 Electronic commutators
• CPC Class Codes: H02P 6/185 using inductance sensing, e.g. pulse excitation
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A motor controller configured to control different types of electronically commutated motors (ECMs) includes a range of different rotor orientation signal inputs to accommodate differences between ECM motor types. The motor controller includes a control unit that receives motor operation commands and controls operation of the ECM in accordance with the motor operation commands. The control unit receives and stores data designating ECM type and estimates rotor position based on the designated ECM type.

Claims

1. A motor controller configured to control any designated one of at least three different types of electronically commutated motors (ECMs), the motor controller comprising:

a controller area network (CAN) connection;

a switching assembly configured to control current flow through a phase A stator coil of an ECM, a phase B stator coil of the ECM, and a phase C stator coil of the ECM;

a phase B current sensor configured to measure current flowing through the phase B stator coil;

a phase C current sensor configured to measure current flowing through the phase C stator coil;

rotor orientation signal inputs including;

one or more Hall sensor inputs configured to receive output generated by Hall sensors responsive to the ECM including the one or more Hall sensors configured to sense orientation of a rotor of the ECM; and

one or more encoder inputs configured to receive output generated by one or more encoders responsive to the ECM including the one or more encoders configured to sense orientation of the rotor; and

a control unit operatively coupled with the CAN connection, the rotor orientation signal inputs, the phase B current sensor, the phase C current sensor, and the switching assembly, the control unit being configured to;

receive D and Q axis current commands via the CAN connection;

receive data designating one of at least three different types of ECMs via the CAN connection and store the designated ECM type in memory, the at least three different types of ECMs including a) an ECM that includes one or more Hall sensors configured to sense rotor orientation, b) an ECM that includes one or more encoders configured to sense rotor orientation, and c) an ECM that does not include any sensors configured to sense rotor orientation; and

control the switching assembly to operate the ECM in accordance with the D and Q axis current commands using rotor orientation estimated based on at least one of a) the output generated by the one or more Hall sensors, b) the output generated by the one or more encoders, or c) outputs from the phase B current sensor and the phase C current sensor.

2. The motor controller of claim 1, further comprising at least one of:

a brake input operatively connected to the control unit and independent of the CAN connection, the control unit being configured to control the switching assembly to operate the ECM in a braking mode that resists rotation of the rotor in response to a brake signal received via the brake input;

a sleep input operatively connected to the control unit and independent of the CAN connection, the control unit being configured to enter a sleep mode in which the motor controller has an input current of less than 5 milliamps in response to a sleep signal received via the sleep input;

a coast input operatively connected to the control unit and independent of the CAN connection, the control unit being configured to control the switching assembly to operate the ECM in a coasting mode that enables free rotation of the rotor in response to a coast signal received via the coast input;

or

a safe boot input operatively connected to the control unit and independent of the CAN connection, the control unit being configured to control the switching assembly to not operate the ECM in response to a safe boot signal received via the safe boot input.

3. The motor controller of claim 1, wherein the control unit is configured to receive commands via the CAN connection and output responses via the CAN connection that are invariant of the designated ECM type.

4. The motor controller of claim 1, wherein the control unit is configured to control the switching assembly to employ field weakening for limited motor drive when line to line back electromotive force (EMF) exceeds a battery voltage used to drive the ECM.

5. A motor controller configured to control any designated one of a plurality of different types of electronically commutated motors (ECMs), the motor controller comprising:

an operational command connection;

a switching assembly configured to control current flow through a phase A stator coil of an ECM, a phase B stator coil of the ECM, and a phase C stator coil of the ECM;

rotor orientation signal inputs; and

a control unit operatively coupled with the operational command connection, the rotor orientation signal inputs, and the switching assembly, the control unit being configured to;

receive motor operation commands via the operational command connection;

receive data designating one of a plurality of different types of ECMs, the plurality of different types of ECMs including at least two of a) an ECM that includes one or more Hall sensors configured to generate output indicative of rotor orientation, b) an ECM that includes one or more encoders configured to generate output indicative of rotor orientation, and c) an ECM that does not include any sensors configured to generate output indicative of rotor orientation; and

control the switching assembly to operate the ECM in accordance with the motor operation commands using rotor orientation estimated based on at least two of a) the output generated by the one or more Hall sensors responsive to the designated ECM type including the one or more Hall sensors, b) the output generated by one or more encoders responsive to the designated ECM type including the one or more encoders, or c) outputs from a phase B current sensor and a phase C current sensor responsive to the designated ECM type not including any sensors.

6. The motor controller of claim 5, wherein the control unit is configured to estimate initial rotor orientation by measuring inductance of the ECM and selecting an initial rotor orientation based on the measured ECM inductance.

7. The motor controller of claim 5, wherein:

the operational command connection comprises a controller area network (CAN) connection; and

the control unit is configured to receive commands via the CAN connection and output responses via the CAN connection that are invariant of the designated ECM type.

8. The motor controller of claim 5, wherein the control unit is configured to control the switching assembly to operate the ECM in a braking mode that resists rotation of the rotor in response to a brake signal received via a brake signal input.

9. The motor controller of claim 5, wherein the control unit is configured to enter a sleep mode in which the motor controller has an input current of less than 5 milliamps in response to a sleep signal received via a sleep input.

10. The motor controller of claim 5, wherein the control unit is configured to control the switching assembly to operate the ECM in a coasting mode that enables free rotation of the rotor in response to a coast signal received via a coast signal input.

11. The motor controller of claim 5, wherein the control unit is configured to load a recovery-mode firm-ware image from memory in response to a safe boot signal received via a safe boot input.

12. The motor controller of claim 5, wherein the control unit is configured to control the switching assembly to employ field weakening for limited motor drive when line to line back electromotive force (EMF) exceeds a battery voltage used to drive the ECM.

13. The motor controller of claim 5, further comprising the phase B current sensor configured to measure current flowing through the phase B stator coil and the phase C current sensor configured to measure current flowing through the phase C stator coil, and wherein the control unit is configured to estimate rotor orientation based on the outputs from the phase B current sensor and the phase C current sensor responsive to the designated ECM type not including any sensors configured to generate output indicative of rotor orientation.

14. The motor controller of claim 5, wherein the control unit is configured to monitor the operational command connection for periodic heartbeat signals and operate the ECM in a coasting mode that enables free rotation of the rotor in response to a non-occurrence of one or more of the periodic heartbeat signals.

15. An inventory management system, comprising:

an inventory holder configured to store inventory items;

a mobile drive unit configured to transport the inventory holder, the mobile drive unit comprising;

a drive wheel configured to propel the mobile drive unit;

a lifting platform configured to lift the inventory holder;

a lifting actuator connected to the lifting platform and operable to lift the lifting platform;

a rotation actuator operable to rotate the lifting platform;

a first integrated drive assembly comprising a first electronically commutated motor (ECM) and a first ECM controller operatively connected to the first ECM, the first ECM being drivingly coupled with the drive wheel, the first ECM controller being configured to control flow of current through stator coils of the first ECM in accordance with first D and Q axis current commands received by the first ECM controller;

a second integrated drive assembly comprising a second ECM and a second ECM controller operatively connected to the second ECM, the second ECM being drivingly coupled with the lifting platform, the second ECM controller being configured to control flow of current through stator coils of the second ECM in accordance with second D and Q axis current commands received by the second ECM controller;

a third integrated drive assembly comprising a third ECM and a third ECM controller operatively connected to the third ECM, the third ECM being drivingly coupled with the rotation actuator, the third ECM controller being configured to control flow of current through stator coils of the third ECM in accordance with third D and Q axis current commands received by the third ECM controller;

a controller area network (CAN) communicatively coupled with the first ECM controller, the second ECM controller, and the third ECM controller;

a control unit communicatively coupled with the CAN and configured to;

control operation of the first integrated drive assembly by at least transmitting the first D and Q axis current commands to the first ECM controller via the CAN;

control operation of the second integrated drive assembly by at least transmitting the second D and Q axis current commands to the second ECM controller via the CAN; and

control operation of the third integrated drive assembly by at least transmitting the third D and Q axis current commands to the third ECM controller via the CAN; and

a management module configured to at least instruct the mobile drive unit to at least one of lift, move or rotate the inventory holder.

16. The inventory management system of claim 15, wherein each of the first, second, and third ECM controllers have the same configuration and are programmable to designate one of a plurality of different types of ECMs to be controlled by the respective ECM controller, the plurality of different types of ECMs including at least two of a) an ECM that includes one or more Hall sensors configured to generate output indicative of rotor orientation, b) an ECM that includes one or more encoders configured to generate output indicative of rotor orientation, and c) an ECM that does not include any sensors configured to generate output indicative of rotor orientation.

17. The inventory management system of claim 16, wherein the third ECM is a different type of the plurality of different types of ECMs than that of at least one of the first or second ECMs.

18. The inventory management system of claim 16, wherein:

each of the first, second, and third ECM controllers comprises a phase B current sensor configured to measure current flowing through a phase B stator coil of the respective ECM and a phase C current sensor configured to measure current flowing through the phase C stator coil of the respective ECM; and

each of the first, second, and third ECM controllers is configured to estimate rotor orientation based on outputs from the phase B current sensor and the phase C current sensor responsive to the designated ECM type not including any sensors.

19. The inventory management system of claim 15, wherein each of the first, second and third ECM controllers is configured to perform at least one of:

operate the respective ECM in a braking mode that resists rotation of the respective drive wheel in response to a brake signal received via a brake signal input;

enter a sleep mode having an input current of less than 5 milliamps in response to a sleep signal received via a sleep input;

operate the respective ECM in a coasting mode that enables free rotation of the respective drive wheel in response to a coast signal received via a coast signal input;

load a recovery-mode firm-ware image from memory in response to a safe boot signal received via a safe boot input;

or

employ field weakening for limited motor drive when line to line back electromotive force (EMF) exceeds a battery voltage used to drive the respective ECM.

20. The inventory management system of claim 15, wherein each of the first, second and third ECM controllers is configured to monitor the CAN for periodic heartbeat signals and operate the respective ECM in a coasting mode that enables free rotation of the respective drive wheel in response to a non-occurrence of one or more of the periodic heartbeat signals.