Method for estimating a torque of a three-phase drive motor for a vehicle

摘要

A method for estimating a torque of a three-phase motor for a vehicle includes measuring a respective current strength in at least two of three phase lines, wherein the three-phase motor is supplied with power by a converter, and wherein the three phase lines lead from the converter to the three-phase motor of the vehicle, measuring a respective voltage at each of the three phase lines, determining a rotating field frequency as a function of the measured current strengths or the measured voltages; and determining an estimated value for the torque as a function of the measured current strengths, the measured voltages and the determined rotating field frequency.

主权项

1. A method for estimating a torque of a three-phase motor for a vehicle comprising the steps of:
measuring a respective current strength in at least a first one and a second one of three phase lines, wherein the three phase motor is supplied with power by a converter, and wherein the three phase lines lead from the converter to the three-phase motor of the vehicle; measuring a respective voltage at each of the three phase lines; determining a rotating field frequency as a function of the measured current strengths or the measured voltages; determining an estimated value for the torque as a function of the measured current strengths, the measured voltages and the determined rotating field frequency, said determining comprising calculating a power value as a sum of a first and of a second partial power value, wherein the first partial power value corresponds to the product of the current strength in the first phase line and a first line-to-line voltage between the first phase line and a third one of the three phase lines, and wherein the second partial power value corresponds to the product of the current strength in the second phase line and a second line-to line voltage between the second phase line and the third phase line; filtering the power value by using a low-pass filter for obtaining an average electrical active power of the converter; providing a power loss model for losses in a drive motor; obtaining a power loss with the power loss model; determining a rotating, field power by subtracting the power loss from the average electrical active power of the converter; and estimating the torque as a function of the rotating field power.