# US 11,121,652 B2 · Determination of an interrupted motor phase of an electric motor

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- Number: US 11,121,652 B2
- Document ID: US11121652B2
- Status: Granted
- Kind: B2
- Application number: 16/724,736
- Filed: 2019-12-23
- Published: 2020-07-02
- Granted: 2021-09-14
- Earliest claimed: 2018-12-27
- Assignees: Robert Bosch GmbH
- Applicants: Robert Bosch GmbH
- Inventors: Dominik Denz; Haithem Fkaier
- Web page: https://patentgrep.com/patent/US11121652B2

## CPC

- H02P 6/186: {using difference of inductance or reluctance between the phases}
- H02P 29/0243: {the fault being a broken phase}
- H02P 6/182: using back-emf in windings
- H02P 8/36: Protection against faults, e.g. against overheating or step-out; Indicating faults
- H02P 29/0241: {the fault being an overvoltage}
- H02P 29/025: {the fault being a power interruption}
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## Abstract

A method for determining an interrupted motor phase of an electric motor having at least three windings by means of a control unit is disclosed, wherein voltages induced in the windings are determined on outer conductors of the electric motor by means of at least one measuring unit, wherein the measuring unit is connected to at least one outer conductor of the electric motor via at least one resistor, the induced voltages of the outer conductors of the electric motor are compared with one another, and an interrupted motor phase is registered if the induced voltage differs or if a frequency of the induced voltage differs. A control unit, a computer program and a machine-readable storage medium are also disclosed.

## Claims

### Claim 1

A method for determining an interrupted motor phase of an electric motor (2) having at least three windings (6) by a control unit (4), the method comprising:
determining voltages induced in the windings (6) on outer conductors (U, V, W) of the electric motor (2) by at least one measuring unit (14), wherein the measuring unit (14) is connected to at least one outer conductor (U, V, W) of the electric motor (2) via at least one resistor (R),
comparing induced voltages of the outer conductors (U, V, W) of the electric motor (2) with one another, and
registering an interrupted motor phase when the induced voltage differs or when a frequency of the induced voltage differs.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the electric motor (2) is at least temporarily deactivated or is operated with a reduced current if an interrupted motor phase (U, V, W) is registered.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the control unit (4) is in the form of at least one BEMF comparator (14) or in the form of an electric motor controller with at least one BEMF comparator (14), wherein the induced voltage is measured in the form of a signal from the BEMF comparator (14) and the determined signals of the outer conductors (U, V, W) are compared with one another.

### Claim 4 (depends on 1)

The method according to claim 1, wherein an interrupted motor phase (U, V, W) is registered if the frequency of the induced voltage is at least doubled in comparison with a reference frequency on at least one outer conductor (U, V, W).

### Claim 5 (depends on 1)

The method according to claim 1, wherein an interrupted motor phase (U, V, W) is registered if the frequency of the induced voltage differs from the reference frequency on at least one outer conductor (U, V, W).

### Claim 6 (depends on 1)

The method according to claim 1, wherein an interrupted motor phase (U, V, W) is registered if no induced voltage can be measured on at least one outer conductor U, V, W).

### Claim 7 (depends on 1)

The method according to claim 1, wherein the electric motor (2) is an electric motor (2) of an engine cooling system.

### Claim 8 (depends on 1)

A control unit (4), wherein the control unit (4) is configured to carry out the method according to claim 1.

### Claim 9 (depends on 8)

The control unit according to claim 8, wherein the control unit (4) is a comparator (14) or a measuring unit of an electric motor controller.

### Claim 10 (depends on 8)

The control unit according to claim 8, wherein the control unit (4) is a comparator (14) or a measuring unit of a pulse width modulator.

### Claim 11 (depends on 1)

A non-transitory machine-readable storage medium (16) having a computer program comprising instructions which, when the computer program is executed by a computer or a control unit (2), cause the latter to carry out a method (1) according to claim 1.