Partial-load phase deactivation of polyphase electric machine

Patent metadata

Field	Value
Publication number	US-2020162005-A1
Application number	US-201816195101-A
Country	US
Kind code	A1
Filing date	Nov 19, 2018
Priority date	Nov 19, 2018
Publication date	May 21, 2020
Grant date	—

Abstract

An electrical system includes a multi-level traction power inverter module (TPIM), a polyphase electric machine, and a controller. The TPIM has multiple switching sets collectively operable for inverting a DC voltage on a DC voltage bus into an AC voltage on an AC voltage bus. The electric machine has (m) multiple electrical phases. Each of the (m) multiple electrical phases is connected to and driven by a respective one of the switching sets of the TPIM. The controller determines when the electric machine enters a predetermined partial-load region of operation, and, responsive to entry into the predetermined partial-load region, selectively deactivates a predetermined number (n) of the (m) multiple electrical phases. This is done via switching state signals to corresponding ones of the switching sets, with n≤m−2.

First claim

What is claimed is:

1 . An electrical system comprising:
an AC voltage bus; a DC voltage bus; a multi-level traction power inverter module (TPIM) connected to the DC voltage bus, and having multiple switching sets collectively operable for inverting a DC voltage on the DC voltage bus into an AC voltage on the AC voltage bus, and vice versa; a polyphase electric machine having (m) multiple electrical phases, wherein each of the (m) multiple electrical phases is connected to and driven by a respective one of the multiple switching sets; and a controller configured to determine when the electric machine enters a predetermined partial-load region of operation, and, responsive to entry into the predetermined partial-load region, to selectively deactivate a predetermined number (n) of the (m) multiple electrical phases via switching state signals to a corresponding switching set of the multiple switching sets, wherein n≤m−2.

2 . The electrical system of claim 1 , wherein

n
=

m
2

.

3 . The electrical system of claim 1 , wherein m≥4.

4 . The electrical system of claim 3 , wherein m=6.

5 . The electrical system of claim 1 , wherein individual switches comprising each of the multiple switching sets are semiconductor switches.

6 . The electrical system of claim 1 , wherein the controller is programmed with a lookup table of electrical losses indexed by a speed and a torque of the electric machine, and to determine when the electric machine enters the partial-load region of operation by comparing data from the lookup table to a calibrated threshold value.

7 . The electrical system of claim 6 , wherein the electrical losses in the lookup table of electrical losses are a ratio of core losses to copper losses of the electric machine.

8 . The electrical system of claim 6 , wherein the electrical losses in the lookup table of electrical losses are a ratio of switching losses to conductive losses of the multi-level TPIM.

9 . The electrical system of claim 1 , wherein the controller is configured to receive a mode selection signal indicative of a requested deactivation ramp-in rate, and responsive to the mode selection signal, to ramp in deactivation of the up to half of the multiple electrical phases at the requested deactivation ramp-in rate.

10 . The electrical system 1 , wherein the controller is configured, when n≠m/ 2 , to automatically reference a deactivation schedule to determine an order of deactivation of the (n) phases which minimizes deactivation-based torque ripple of the electric machine.

11 . The electrical system of claim 1 , wherein the polyphase electric machine includes a rotor coupled to a set of drive wheels of a motor vehicle.

12 . A method for use with an electrical system having a multi-level traction power inverter module (TPIM) connected to a direct current (DC) voltage bus and a polyphase electric machine, the polyphase electric machine having (m) multiple electrical phases connected to and driven by a respective switching set of the TPIM and coupled to a driven load, the method comprising:
determining, via a controller, when the polyphase electric machine enters a predetermined partial-load region of operation; and responsive to entry of the polyphase electric machine into the predetermined partial-load region of operation, selectively deactivating a predetermined number (n) of the (m) multiple electrical phases via transmission of switching state signals from the controller to corresponding one of the switching sets, wherein n≤m−2.

13 . The method of claim 12 , the method further comprising: powering the driven load via the electric machine, wherein the driven load is a set of road wheels of a motor vehicle.

14 . The method of claim 12 , wherein m≥4.

15 . The method of claim 14 , wherein m=6.

16 . The method of claim 12 , wherein the controller is programmed with a lookup table of electrical losses indexed by a speed and a torque of the electric machine, wherein determining when the electric machine enters the partial-load region of operation includes comparing data from the lookup table to a calibrated threshold value.

17 . The method of claim 16 , wherein the electrical losses in the lookup table of electrical losses are a ratio of core losses to copper losses of the electric machine.

18 . The method of claim 16 , wherein the electrical losses in the lookup table of electrical losses are a ratio of switching losses to conductive losses of the TPIM.

19 . The method of claim 12 , the method further comprising:
receiving, via the controller from an external device, a mode selection signal indicative of a requested deactivation ramp-in rate; and responsive to receipt of the mode selection signal, ramping in a deactivation of the predetermined number (n) of the (m) multiple electrical phases at the requested deactivation ramp-in rate.

20 . The method of claim 12 , the method further comprising:
when

n
≠

m
2

,

automatically referencing a deactivation schedule to determine an order of deactivation of the (n) phases which minimizes deactivation-based torque ripple of the electric machine.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Fatemi Alireza
• Lahr Derek F

Classifications

• H02P23/02 Primary

  specially adapted for optimising the efficiency at low load · CPC title

• B60Y2200/92

  Hybrid vehicles · CPC title

• H02P23/04

  specially adapted for damping motor oscillations, e.g. for reducing hunting · CPC title

• B60W50/00

  Details of control systems for road vehicle drive control not related to the control of a particular sub-unit {, e.g. process diagnostic or vehicle driver interfaces} · CPC title

• B60Y2400/60

  Electric Machines, e.g. motors or generators · CPC title