Method for determining an ageing parameter, a state of charge parameter and a temperature of a rechargeable battery, especially a lithium rechargeable battery

A method for determining a state of charge parameter KSOC of a rechargeable battery of a vehicle, the method comprising:

• (a) applying, by a control system of the vehicle, an electric current to the rechargeable and detecting an impedance Z of the rechargeable battery at different frequencies f, so that a Nyquist plot is obtained;
• (b) determining at least one of the following SOC parameters:
• (i) a first SOC parameter (pSOC1) in the form of the first waveform parameter (pSOH1),
• (ii) a second SOC parameter (pSOC2) in the form of the second waveform parameter (pSOH2),
• (iii) a third SOC parameter (pSOC3) in the form of the third waveform parameter (pSOH3),
• (iv) a fourth SOC parameter (pSOC4) in the form of the real part of the impedance at the sensitivity frequency fsens,
• (v) a fifth SOC parameter (pSOC5) in the form of the imaginary part of the impedance at the sensitivity frequency fsens,
• (vi) a sixth SOC parameter (pSOC6) in the form of a difference from:
• the fourth SOC parameter (pSOC4) (=the real part of the impedance at the sensitivity frequency fsens) and
• the real part of the impedance at a fixed adjacent frequency fN, which is greater than the local minimum frequency fLM in an unaged rechargeable battery and is adjacent to said frequency and is smaller than the center frequency fZ, and
• (vii) a seventh SOC parameter (pSOC7) in the form of a phase (φ) of the impedance at a center frequency fZ, which lies in a central third between the semi-circular maximum frequency fHbM and the local minimum frequency fLM′
• (c) establishing an SOC row vector P from the SOC parameters and all mixed terms of the form pSOC,m·pSOC,n, m=1, . . . , 7, n=1, . . . , m;
• and
• (e) multiplying the SOC row vector {right arrow over (PSOC)} by a saved SOC calibration vector {right arrow over (ASOC)}, thereby obtaining the state of charge parameter KSOC,
• wherein a message is emitted when the state of charge drops below a predetermined nominal state of charge.

A method for determining a temperature of a rechargeable battery of a vehicle, the method comprising:

• (a) applying, by a control system of the vehicle, an electric current to the rechargeable and detecting an impedance Z of the rechargeable battery at different frequencies f, so that a Nyquist plot is obtained;
• (b) determining at least one of the following T parameters:
• (i) a first T parameter (pT1) in the form of the fourth SOC parameter (pSOC4),
• (ii) a second T parameter (pT2) in the form of the fifth SOC parameter (pSOC5),
• (iii) a third T parameter (pT3) in the form of the eighth SOH parameter (pSOH8),
• (iv) a fourth T parameter (pT4) in the form of the ninth SOH parameter (pSOH9), and
• (v) a fifth T parameter (pT5) in the form of an axial section frequency (fAS), at which the imaginary part of the impedance Z is zero and which is greater than the semi-circular maximum frequency (fHbM);
• (c) establishing a T row vector {right arrow over (PT)} from the T parameters and all mixed terms of the form pT,m·pT,n, m=1, . . . , 5, n=1, . . . , m;
• and
• (d) multiplying the T row vector {right arrow over (PT)} by a saved calibration vector {right arrow over (AT)}, thereby obtaining the temperature T,
• wherein a message is emitted or a power of the vehicle is reduced when the temperature drops below a predetermined maximum temperature.