US-12618878-B2 - Method and detector device for monitoring current sensors, and electric drive system

Abstract

The invention relates to current sensor diagnostics in an electric drive system. According to the invention, a net current is formed from the sensor values provided by the current sensors. If this net current deviates significantly from zero, a complex current sum can be calculated using the rotor angle of the electric machine. This complex current sum is based on the current RMS current in the electric drive system in order to indicate deviations in the current gain factors of the current sensors used.

Inventors

• Sebastian Paulus

Assignees

• ROBERT BOSCH GMBH

Dates

Publication Date

20260505

Application Date

20220725

Priority Date

20210927

Claims (7)

1. 1 . A method for monitoring current sensors ( 21 - 23 ) for phase currents in a multiphase electrical drive system, the method comprising the steps of: detecting (S 1 ) the sensor values for the phase currents, in each case one current sensor ( 21 - 23 ) determining a phase current of the multiphase electric drive system and providing a sensor value corresponding to the determined phase current; calculating (S 2 ) a current sum using the detected sensor values from the current sensors ( 21 - 23 ); determining (S 3 ) a real portion and an imaginary portion of a complex current sum using a rotor angle of the electric machine ( 2 ) in the electric drive system; calculating (S 4 ) a complex gain error from a quotient of the real portion of the complex current sum and a current effective phase current amplitude and a quotient of the imaginary portion of the complex current sum and the current effective phase current amplitude; and calculating (S 5 ) a magnitude of the complex gain error; comparing the calculated magnitude of complex gain error with a predetermined threshold value; and detecting a sensor error if the calculated magnitude of the complex gain error exceeds the predetermined threshold value.
2. 2 . The method according to claim 1 , comprising a step of filtering the calculated current sum, wherein the real portion and the imaginary portion of the complex current sum are calculated using the filtered current sum.
3. 3 . The method according to claim 1 , comprising the steps of: filtering the real portion and the imaginary portion of the complex current sum, determining an effective phase current, and filtering of a time curve of the effective phase current, wherein the real portion and the imaginary portion of the complex current sum and the time curve of the effective phase current are filtered with the same time constant, and wherein the calculation of a complex gain error is performed using the filtered real portion and the filtered imaginary portion of the complex current sum and the filtered effective phase current.
4. 4 . The method according to claim 2 , wherein the filtering of the current sum, the real portion and the imaginary portion of the complex current sum and/or the time curve of the effective phase current comprises averaging, low-pass filtering or combined low-pass filtering and band-pass filtering.
5. 5 . A detector device ( 10 ) for monitoring current sensors for phase currents in a multiphase electrical drive system, the detector comprising: an input interface ( 11 ) which is configured to detect sensor values for phase currents, in each case a current sensor ( 21 - 23 ) determining a phase current of the multiphase electrical drive system and providing a sensor value corresponding to the determined phase current; a computer ( 12 ) configured to calculate a current sum using the detected sensor values from the current sensors ( 21 - 23 ), to determine a real portion and an imaginary portion of a complex current sum using a rotor angle of the electric machine ( 2 ) in the electric drive system, to calculate a complex gain error from a quotient of the real portion of the complex current sum and a current effective phase current amplitude and a quotient of the imaginary portion of the complex current sum and the current effective phase current amplitude, to calculate a magnitude of the complex gain error, to compare the calculated magnitude of complex gain error with a predetermined threshold value, and to detect a sensor error if the calculated magnitude of the complex gain error exceeds the predetermined threshold value.
6. 6 . An electric drive system comprising: a multiphase electrical machine ( 2 ), a plurality of current sensors ( 21 - 23 ) each configured to detect an electrical phase current and to output a sensor value corresponding to the detected phase current; and a detector device ( 10 ) according to claim 5 .
7. 7 . The method according to claim 1 , further comprising switching the electric drive system to emergency operation.

Description

BACKGROUND The present invention relates to a method and a detector device for monitoring current sensors, in particular current sensors for phase currents in a multiphase electrical drive system. The present invention also relates to an electric drive system with such a device for monitoring current sensors. Electric drive systems are used in numerous areas of application. Electrical energy can be provided by an electrical energy source, such as a battery or similar. The supplied electrical energy can be converted by means of a power converter into a single-phase or multi-phase electrical voltage, which is supplied to the connections of an electrical machine in order to set a predetermined operating state. For example, the electrical currents from the power converter to the phase connections of the electrical machine can be detected to control the electrical drive system and to set predefined setpoint value specifications on the electrical machine. For this purpose, a current sensor can be provided for each phase of the electrical machine, which provides an analog or digital signal corresponding to the electrical current. The publication DE 10 2011 003 566 A1 describes a method and a device for calibrating a current sensor, in particular a current sensor for detecting a phase current of an electrical machine controlled by an inverter. For this purpose, it is proposed to compare a detected actual value or a variable derived from a detected actual value with a predefined setpoint value and to determine a deviation from a standard state. SUMMARY The present invention provides a method and a device for monitoring current sensors and an electric drive system with the features of the independent patent claims. Further advantageous embodiments are the subject matter of the dependent claims. Accordingly, the following is provided: A method for monitoring current sensors, in particular for monitoring current sensors for phase currents in a multiphase electrical drive system. The method comprises a step for detecting sensor values for the phase currents. In particular, a current sensor can determine a phase current of the multiphase electric drive system and provide a sensor value corresponding to the determined phase current. The method further comprises a step of calculating a current sum using the detected sensor values from the current sensors. Furthermore, the method comprises a step for determining a real portion and an imaginary portion of a complex current sum. Here, the real portion and the imaginary portion of the complex current sum can be determined using a rotor angle of the electric machine in the electric drive system. Furthermore, the method comprises a step for calculating a complex amplification error of the current sensors. The complex amplification error is calculated from a quotient of the real portion of the complex current sum and a current effective phase current amplitude, as well as a quotient of the imaginary portion of the complex current sum and the current effective phase current amplitude. Finally, the method comprises a step of calculating a magnitude of the complex amplification error. The following is furthermore provided: A detector device for monitoring current sensors, in particular for monitoring current sensors for phase currents in a multiphase electrical drive system. The detector device comprises an input interface and a computing unit. The input interface is designed to detect sensor values from current sensors, wherein a current sensor determines a phase current of the multiphase electric drive system and provides a sensor value corresponding to the determined phase current. In particular, sensor values from current sensors can be detected at the phase connections of an electric machine of the electric drive system. Alternatively, it is also possible to detect the phase currents at another point. The computing unit is designed to calculate a current sum using the sensor values detected by the current sensors. Furthermore, the computing unit is designed to calculate a real portion and an imaginary portion of a complex current sum. The real portion and the imaginary portion can be calculated using a rotor angle of the electric machine in the electric drive system. Furthermore, the computing unit is designed to calculate a complex amplification error. The complex amplification error is calculated from a quotient of the real portion of the complex current sum and a current effective phase current amplitude as well as a quotient of the imaginary portion of the complex current sum and the current effective phase current amplitude. Finally, the computing unit is designed to calculate a magnitude of the complex amplification error. Finally, the following is provided: An electric drive system with a multiphase electric machine, a plurality of current sensors and a detector device according to the invention. The current sensors are each designed to detect an electrical phase current