Method and device for detecting a speed in a generator unit

• US 10,411,625 B2
• Filed: 10/28/2016
• Issued: 09/10/2019
• Est. Priority Date: 11/18/2015
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Magini, Fabio, Mueller, Manuel, Wohlfarth, Michael, Riederer, Miriam
• Primary Examiner(s): Cuevas, Pedro J
• Application Number:
  US15/776,962
• Publication Number:
  US 20180331642A1
• Time in Patent Office: 1,047 Days
• Field of Search: 322 11, 322 28, 322 46, 310114
• CPC Class Codes: G01P 3/48 by measuring frequency of generated current or voltage in general G01R23/00
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: H02P 2101/25 for combustion engines
• CPC Class Codes: H02P 2203/09 Motor speed determination based on the current and/or voltage without using a tachogenerator or a physical encoder
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage
• CPC Class Codes: H02P 9/006 Means for protecting the generator by using control H02H7/06 takes precedence; control effected upon generator excitation circuit to reduce harmful effects of overloads or transients H02P9/10
• CPC Class Codes: H02P 9/08 Control of generator circuit during starting or stopping of driving means, e.g. for initiating excitation

Abstract

A method for determining a speed (nG) of a generator unit which has an electric machine (100) with a rotor winding (110) and a stator winding (120) and a rectifier (130) connected thereto, via which rectifier the electric machine (100) is connected to an electrical system (150) of a motor vehicle, the speed (nG) being determined depending on the plot of an excitation current (IE) flowing through the rotor winding (110) of the electric machine (100). In particular, the speed is determined from a known relationship between the speed, the frequency of the excitation current, the number of pole pairs and optionally the number of phases when there is an error that leads to a constant phase voltage being output.

Claims

1. A method for determining a speed of a generator unit which has an electric machine with a rotor winding and a stator winding and a rectifier connected thereto, via which rectifier the electric machine is connected to an electrical system of a motor vehicle, the method comprising:

determining the speed based on a plot of an excitation current flowing through the rotor winding of the electric machine.

2. The method according to claim 1, wherein the speed is determined depending on the plot of the excitation current if an error is present in the generator unit.

3. The method according to claim 2, wherein the speed is determined depending on a plot of a phase voltage if an error is not present in the generator unit.

4. The method according to claim 1, wherein the speed is determined depending on the plot of the excitation current (IE) if the phase voltage is fixed to a constant value.

5. The method according to claim 4, wherein the speed is determined depending on the value of the phase voltage.

6. The method according to claim 5, wherein the speed is determined equal to a frequency of the excitation current divided by the number of pole pairs.

7. The method according to claim 5, wherein the speed is determined equal to a frequency of the excitation current divided by the number of pole pairs multiplied by twice the phase number of the generator if the phase voltage lies between a high-side voltage level and a low-side voltage level of the vehicle electrical system.

8. The method according to claim 1, wherein the speed is detected depending on an analysis of a frequency spectrum of the plot of the excitation current or depending on an edge detection in the plot of the excitation current.

9. The method according to claim 1, wherein a start-up of the generator unit is initiated if it is detected that a frequency of the excitation current lies above a speed threshold.

10. The method according to claim 9, wherein the generator unit is started in a secured operation if an oscillation of the excitation current is greater than a threshold value and the frequency of the excitation current lies above an emergency start frequency.

11. The method according to claim 9, wherein the generator unit is started in a normal operation if an oscillation of the excitation current is smaller than a threshold value and the frequency of the excitation current lies above an emergency start frequency.

12. A generator controller for determining a speed of a generator unit which has an electric machine with a rotor winding and a stator winding and a rectifier connected thereto, via which rectifier the electric machine is connected to an electrical system of a motor vehicle, the generator controller configured to determining the speed based on a plot of an excitation current flowing through the rotor winding of the electric machine.

13. A machine-readable storage medium having a computer program, that when executed by a computer, cause the computer to

determine a speed of a generator unit, which has an electric machine with a rotor winding and a stator winding and a rectifier connected thereto, via which rectifier the electric machine is connected to an electrical system of a motor vehicle, based on a plot of an excitation current flowing through the rotor winding of the electric machine.