Method for determining rotation parameters of a rotation angle, and electric motor

An electric motor comprising a stator and a rotor which is rotatable relative to the stator by changing a rotation angle (γ) and has a rotation angle (γ) that can be determined by determining rotation parameters with a calculation algorithm including:

• determining a first phase voltage (ud) and a first phase current (id) in each case with respect to a d-direction and a second phase voltage (uq) and a second phase current (iq) in each case with respect to a q-direction of a rotor-fixed dq-coordinate system,
• using a calculation algorithm with a calculation of the first phase voltage (ud) as a modeled first phase voltage (ud,m) and the second phase voltage (uq) as a modeled second phase voltage (uq,m) at least according to the first and second phase current (id, iq), at least one electrical motor parameter (P), the rotational speed (ω) and the rotation angle (γ) and with an iterative calculation of the rotational speed (ω) as a calculated rotational speed (ωi) and the rotation angle (γ) as a calculated rotation angle (γi) according to the determined first and second phase voltage (ud, uq) and the modeled first and second phase voltage (ud,m, uq,m),
• outputting the calculated rotation angle (γi) as an output calculated rotation angle (γr) and
• calculating the rotational speed (ω) as an output calculated rotational speed (ωr) from the output calculated rotation angle (γr) without directly calculating from the calculated rotational speed (ωi),
• wherein
• the calculation algorithm uses a first relationship which specifies a first voltage difference (Δud) between the determined first phase voltage (ud) and the modeled first phase voltage (ud,m), and
• the iterative calculation of the rotation angle (γ) with the first relationship is carried out in that a rotation angle (γi-1) calculated previously in a preceding calculation step is used and is changed in a calculation step by a rotation angle difference (Δγ) to reduce the first voltage difference (Δud).