Electric Machine

• US 20200136547A1
• Filed: 06/07/2018
• Published: 04/30/2020
• Est. Priority Date: 07/21/2017
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Kurfiss, Jochen, Vollmer, Ulrich
• Granted Patent: US 11,196,376 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters
• CPC Class Codes: H02P 21/22 Current control, e.g. using a current control loop
• CPC Class Codes: H02P 23/00 Arrangements or methods for the control of AC motors characterised by a control method other than vector control
• CPC Class Codes: H02P 25/22 Multiple windings; Windings for more than three phases
• CPC Class Codes: H02P 27/08 with pulse width modulation

Abstract

An electric machine has at least two sub-machines, each having the same number of phases and being designed to generate a magnetic rotary field independently of one another to rotate the rotor. The machine has a power output stage for each sub-machine, each being designed to energize the sub-machines independently of one another. The machine also has at least one or only one control unit which is connected to the power output stages and is designed to generate a PWM signal in order to actuate the power output stages. The control unit is designed to generate the PWM signal for the sub-machines such that each of the PWM pulses for a sub-machine begins at a starting time of a PWM period and/or to generate the PWM pulses for another sub-machine such that each of the PWM pulses ends at an end time of the PWM period for the other sub-machine.

Claims

1. An electric machine comprising:

a stator;

a rotor;

at least two sub-machines, each of the at least two sub-machines having a same number of phases, each of the at least two sub-machines including a portion of stator coils of the stator, each of the at least two sub-machines being configured to generate, independently of each other, a rotating magnetic field to rotate the rotor;

at least two power output stages, each of the at least two power output stages corresponding to a respective one of the at least two sub-machines; and

at least one control unit connected to the at least two power output stages, and configured to generate at least one PWM signal to actuate the at least two power output stages, the at least one control unit being configured to generate the at least one PWM signal such that PWM pulses of the at least one PWM signal for a first sub-machine of the at least two sub-machines each start at a start time of a first PWM period for the first sub-machine.

2. The electric machine as claimed in claim 1, wherein the at least one control unit is configured designed to generate the at least one PWM signal such that the PWM pulses of the at least one PWM signal for a second sub-machine of the at least two sub-machines each end at an end time of a second PWM period for the second sub-machine.

3. The electric machine as claimed in claim 2, wherein the at least one control unit is configured to generate the first PWM period and the second PWM period phase-shifted relative to each other.

4. The electric machine as claimed in claim 1 further comprising:

at least one current sensor connected to the at least one control unit, the at least one current sensor being configured to detect a phase current of at least one phase the at least two sub-machines,

wherein the at least one control unit is configured to detect the phase current of the at least one phase of the at least two sub-machine during a common pulse pause of PWM periods of the at least two sub-machines.

5. The electric machine as claimed in claim 1, wherein the at least one control unit is configured to one of lengthen and shorten a duty cycle for all phases of a sub-machine of the at least two sub-machines by a pre-determined time interval.

6. The electric machine as claimed in claim 5, wherein the at least one control unit is configured to one of lengthen and shorten a pulse duration of a high-side pulse and of a low-side pulse in an alternating manner to each other.

7. The electric machine as claimed in claim 1, wherein the at least one control unit is configured to (i) generate a current detection interval during a common pulse pause of the at least two sub-machines and (ii) detect a current during the current detection interval.

8. A method for actuating an electric machine including at least two sub-machines, each having a same number of stator coils, the method comprising:

generating pulse-width-modulated pulse patterns having a plurality of PWM pulses to actuate the stator coils of each of the at least two sub-machines, PWM pulses of the plurality of PWM pulses for a first sub-machine of the at least two sub-machines each starting at a start time of a first PWM period for the first sub-machine and PWM pulses of the plurality of PWM pulses for a second sub-machine of the at least two sub-machines each ending at an end time of a second PWM period for the second sub-machine.

9. The method as claimed in claim 8 further comprising:

detecting a current flowing through at least one of the stator coils of the at least two sub-machines within a current detection interval during a common pulse pause of the plurality of PWM pulses for the at least two sub-machines.

10. The method as claimed in claim 8, wherein the first PWM period and the second PWM period are each phase-shifted relative to each other.