Method and apparatus for estimating a temperature contribution of an inverter for an electrical machine

An apparatus (50) for estimating a temperature contribution of an inverter used for supplying an electric machine with current comprising:

• a device for calculating oscillating temperature swings of components of the inverter;
• and
• a device for determining an upper envelope of an amplitude of a sum of the calculated oscillating temperature swings, as an estimated temperature contribution of the inverter;
• wherein the inverter comprises components of a first switch type configured as IGBTs, and components of a second switch type configured as diodes;
• and the oscillating temperature swings for the components of the first switch type and the oscillating temperature swings for the components of the second switch type are calculated according to the same parameterized calculation specification, but with different parameter values for the two switch types.

An electric vehicle or hybrid vehicle having an electric drive coupled to the vehicle wheels or the output without a speed converter,

• wherein a temperature contribution of an inverter used for supplying an electric machine with current is estimated by:
• calculating oscillating temperature swings of components of the inverter;
• and
• determining an upper envelope (ΔT(ω), ΔTi(ω), (ΔTd(ω)) of an amplitude of a sum of the calculated oscillating temperature swings, as an estimated temperature contribution of the inverter;
• wherein the inverter comprises components of a first switch type configured as IGBTs, and components of a second switch type configured as diodes;
• and the oscillating temperature swings for the components of the first switch type and the oscillating temperature swings for the components of the second switch type are calculated according to the same parameterized calculation specification, but with different parameter values for the two switch types, and
• wherein the temperature contribution is used therein for self-protection purposes of a power electronic system controlling or driving the electric vehicle, for driving scenarios such as low driving speeds, starting from a standstill, and starting on a hill.