Control device for an electric machine, a vehicle, and a method

• US 10,148,208 B2
• Filed: 08/13/2015
• Issued: 12/04/2018
• Est. Priority Date: 10/07/2014
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Goetting, Gunther, Chouk, Lanouar
• Primary Examiner(s): Santana, Eduardo Colon
• Assistant Examiner(s): Joseph, Devon
• Application Number:
  US15/516,847
• Publication Number:
  US 20170302205A1
• Time in Patent Office: 1,209 Days
• Field of Search: 318400
• CPC Class Codes: H02P 21/14 Estimation or adaptation of machine parameters, e.g. flux, current or voltage
• CPC Class Codes: H02P 29/66 Controlling or determining the temperature of the rotor
• CPC Class Codes: H02P 29/68 based on the temperature of a drive component or a semiconductor component

Abstract

The invention relates to a control device for an electric machine with a stator and a rotor, comprising a temperature detection device which is designed to detect the temperature of the stator and the temperature of the rotor, as well as a calculation device which is designed to adjust the operating point of said electric machine on the basis of a specified torque, the detected temperature of the stator, the detected temperature of the rotor, and a predefined thermal load distribution of said stator and rotor. The invention also relates to a vehicle and to a corresponding method for controlling an electric machine.

Claims

1. A control device (1) for an electric machine (2) including a stator (3) and a rotor (4), the control device comprising:

a temperature detection device (5) which is configured to detect a temperature (6-1) of the stator (3) and a temperature (6-2) of the rotor (4);

a computing device (7) which is configured to set an operating point (8) of the electric machine (2) based on a torque specification (9), the detected temperature (6-1) of the stator (3), the detected temperature (6-2) of the rotor (4) and a predefined distribution (10) for a thermal load of the stator (3) and the rotor (4) by calculating a d-axis component (11) of a current vector (13-1 to 13-3) and a q-axis component (12) of the current vector (13-1 to 13-3) in a field-oriented coordinate system;

a memory (14) configured to store a machine-specific characteristic curve field (15) for the electric machine (2), which specifies a resulting motor current (16) and a resulting torque (17) and a resulting magnetic flux (30) in the electric machine (2) for predefined values of the d-axis component (11) and the q-axis component (12) of the current vector (13-1 to 13-3); and

a current controller (21) which is coupled to the computing device (7) and is configured to calculate control voltages (22-1 to 22-3) for the phases (23-1 to 23-3) of the electric machine (2) based on the operating point (8) set by the computing device (7),

wherein the computing device (7) is configured to adjust the d-axis component (11) of the current vector (13-1 to 13-3) with respect to the q-axis component (12) of the current vector (13-1 to 13-3), and to adjust the q-axis component (12) of the current vector (13-1 to 13-3) in such a way that the torque predefined by the torque specification (9) is reached in the electric machine (2) if the thermal load of the rotor (4) is to be decreased with respect to the thermal load of the stator (3), and

wherein the computing device (7) is configured to increase the d-axis component (11) of the current vector (13-1 to 13-3) with respect to the q-axis component (12) of the current vector (13-1 to 13-3), to decrease the q-axis component (12) of the current vector (13-1 to 13-3) with respect to the d-axis component (11) of the current vector (13-1 to 13-3), or both when the thermal load of the rotor (4) is decreased with respect to the thermal load of the stator (3).

2. The control device as claimed in claim 1,

wherein the computing device (7) is configured to increase the d-axis component (11) of the current vector (13-1 to 13-3) and to decreased the q-axis component (12) of the current vector (13-1 to 13-3), so that the resulting current vector (13-1 to 13-3) is shifted to a characteristic curve having a constant torque (17).

3. The control device as claimed in claim 1,

wherein the computing device (7) is configured to decrease the magnitude of the current vector (13-1 to 13-3) if the thermal load of the stator (3) is to be decreased.

4. The control device as claimed in claim 1,

wherein the computing device (7) is configured to calculate the operating point (8) based on a stator frequency (19), which specifies the frequency of the control voltage of the stator.

5. The control device as claimed in claim 1,

wherein the temperature detection device (5) is configured to calculate the temperature (6-1) of the stator (3), the temperature (6-2) of the rotor (4), or both;

and

wherein the temperature detection device (5) includes at least one temperature sensor (20) for detecting the temperature (6-1) of the stator (3), the temperature (6-2) of the rotor (4), or both.

6. A vehicle (26) comprising:

an electric machine (2) which includes a stator (3) and a rotor (4);

a drive train (24) of the vehicle (26) that is coupled with the electric machine for driving the vehicle; and

a control device (1) which is coupled to the electric machine (2) and is configured to control the electric machine (2), the control device including

a temperature detection device (5) which is configured to detect a temperature (6-1) of the stator (3) and a temperature (6-2) of the rotor (4); and

a computing device (7) which is configured to set an operating point (8) of the electric machine (2) based on a torque specification (9), the detected temperature (6-1) of the stator (3), the detected temperature (6-2) of the rotor (4), a predefined distribution (10) for a thermal load of the stator (3) and the rotor (4), and a stator frequency (19),

wherein the computing device (7) is configured to adjust a d-axis component (11) of a current vector (13-1 to 13-3) with respect to a q-axis component (12) of the current vector (13-1 to 13-3), and to adjust the q-axis component (12) of the current vector (13-1 to 13-3) in such a way that the torque predefined by the torque specification (9) is reached in the electric machine (2) if the thermal load of the rotor (4) is to be decreased with respect to the thermal load of the stator (3), and

wherein the computing device (7) is configured to increase the d-axis component (11) of the current vector (13-1 to 13-3) with respect to the q-axis component (12) of the current vector (13-1 to 13-3), to decrease the q-axis component (12) of the current vector (13-1 to 13-3) with respect to the d-axis component (11) of the current vector (13-1 to 13-3), or both when the thermal load of the rotor (4) is decreased with respect to the thermal load of the stator (3).

7. The vehicle as claimed in claim 6,

wherein the computing device (7) is configured to calculate the operating point (8) based on the stator frequency (19) that specifies the frequency of the control voltage of the stator.

8. The vehicle as claimed in claim 6,

including an internal combustion engine (25) which is mechanically coupled to the drive train (24) and is configured to drive the vehicle (26) alone or in connection with the electric machine (2).

9. A method for controlling an electric machine (2) including a stator (3) and a rotor (4), including:

detecting (S1) a temperature (6-1) of the stator (3) and a temperature (6-2) of the rotor (4);

setting (S2) an operating point (8) of the electric machine (2) with a computing device based on a torque specification (9), the detected temperature (6-1) of the stator (3), the detected temperature (6-2) of the rotor (4), and a predefined distribution (10) for a thermal load of the stator (3) and the rotor (4) by calculating a d-axis component (11) of a current vector (13-1 to 13-3) and a q-axis component (12) of the current vector (13-1 to 13-3) in a field-oriented coordinate system; and

calculating control voltages (22-1 to 22-3) for phases (23-1 to 23-3) of the electric machine (2) based on the operating point (8),

wherein when setting, the d-axis component (11) of the current vector (13-1 to 13-3) is increased with respect to the q-axis component (12) of the current vector (13-1 to 13-3), and wherein the q-axis component (12) of the current vector (13-1 to 13-3) is decreased with respect to the d-axis component (11) of the current vector (13-1 to 13-3), if the thermal load of the rotor (4) is to be decreased with respect to the thermal load of the stator (3); and

wherein when setting, the magnitude of the current vector (13-1 to 13-3) is decreased if the thermal load of the stator (3) is to be decreased.

10. The method as claimed in claim 9, wherein the setting of the operating point is based further on a stator frequency (19) that specifies the frequency of the control voltage of the stator.