Method for dynamically measuring the state of health and charge of a car battery and device for implementing said method

• US 6,876,174 B1
• Filed: 12/31/1999
• Issued: 04/05/2005
• Est. Priority Date: 12/31/1999
• Status: Expired due to Fees

• Current Assignee: Lear Automotive EEDS Spain SL (Lear Corporation)
• Original Assignee: Lear Automotive EEDS Spain SL (Lear Corporation)
• Inventors: Giro Roca, Jordi, Puig Vidal, Manuel, Samittier Marti, Josep, Ruiz Sanchez, Oscar, Bigorra Vives, Jordi, Guasch Murillo, Daniel
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US10/169,128
• Time in Patent Office: 1,922 Days
• Field of Search: 320/128, 320/132, 320/149, 324/426, 324/430, 324/433
• US Class Current: 320/132
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

Based on the measurement of the increase of sinusoidal voltage ΔV=V_maxsine(2πft) on adding a sinusoidal current ΔI=I_maxsine(2πft+φ) to the battery current, where f is the frequency and I_max, the amplitude of the superimposed current, with whose magnitudes the electrochemical impedance of the battery Z(f)=V_max/I_maxe^jφ is calculated, comprising the application of a first sinusoidal signal of prefixed frequency to the battery which generates an alternate voltage component superimposed over the direct one; eliminating the direct component of the response signal; applying a second periodic voltage signal with a frequency identical to that of said first signal and carrying out a synchronous detection of the alternate component generated by the application of said first signal to obtain the voltage proportional to the electrochemical impedance and evaluate the state of health and charge of the battery.

Claims

1. A method for a dynamic measurement of the state of health and charge of a vehicle battery, based on the measure of sinusoidal voltage increase Δ

V=V_maxsine(2π

ft) when a sinusoidal current, Δ

I=I_maxsine(2π

ft+φ

) is added to the normal charge and discharge current of the battery, where f is the frequency and I_max, the amplitude of the superimposed sinusoidal current, by whose magnitudes the electrochemical impedance of the battery Z(f)=V_max/I_maxe^jφ

is calculated, characterised on comprising the following stages;

Application of a first sinusoidal current signal of a prefixed frequency to the battery terminals, generating a voltage response in said terminals as an alternate voltage component superimposed over the direct current, together with other alternate voltage components generated by different electric and electronic devices supplied by said battery and/or connected to it;

elimination of the continuous component of the response signal leaving only the alternate voltage components;

application of a second high precision voltage signal, for reference, having an identical frequency to that of the mentioned first sinusoidal current signal and execution of a synchronous detection of the alternate voltage component generated by the application to the battery terminals of that first sinusoidal current signal to only obtain a voltage proportional (modulus and phase) to the electrochemical impedance of the battery, and

evaluation as from said electrochemical impedance value, at any moment of battery operation in the vehicle, of the state of health and state of charge of the battery, by comparing with modulus/frequency diagrams pre-analysed and stored in memory for different types of battery.

2. A method according to claim 1, characterised in that the mentioned stage of synchronous detection comprises the application of those alternate voltage components of the battery terminals and a second high precision periodic voltage signal to an amplification and frequency discrimination assembly.

3. A method according to claim 2, characterised in that said amplification and frequency discrimination assembly comprises a multiplier and a low-pass filter generating in its output a third periodic voltage signal, proportional to the elctrochemical impedance of the battery.

4. A method according to claim 1, characterised in that the mentioned sinusoidal signal applied in the form of current and the mentioned second periodic high precision reference voltage signal are obtained from a power unit with a single high precision sinusoidal wave shape.

5. A device for the dynamic measurement of the state of health and charge of a vehicle battery, based on the measurement of the increase of sinusoidal voltage Δ

V=V_maxsine(2π

ft) when a sinusoidal current Δ

I=I_maxsine(2π

ft+φ

) is added to the normal charge and discharge current of the battery, where f is the frequency and I_max, the amplitude of the superimposed sinusoidal current, by whose magnitudes the electrochemical impedance of the battery Z(f)=V_max/I_maxe^jφ

is calculated, characterised on comprising a generating device of high precision sinusoidal wave form which controls a current source foreseen to apply a first sinusoidal current signal, with a frequency corresponding to said wave form power unit, to the terminals of the battery and a multiplication and frequency amplification assembly to which is supplied the voltage in said battery terminals and a reference voltage signal coming from said sinusoidal wave form power unit, for the synchronous detection in said multiplier and filter assembly, of the alternate voltage component generated by the application of that first sinusoidal current signal to the battery terminals.

6. A method according to claim 5, characterised in that said amplification and frequency discrimination assembly comprises a multiplier and a low-pass filter generating at its output a third periodic voltage signal, proportional to the electrochemical impedance of the battery.