Device and method for measuring the charge state of a nickel-cadmium accumulator
First Claim
1. Method for measuring the charge state S of a nickel-cadmium accumulator, comprising the steps of:
- (a) discharging the nickel-cadmium accumulator with a constant discharge current I;
(b) measuring the imaginary portion ZI of the complex impedance of the accumulator at a fixed frequency during discharge;
(c) using a quantity proportional to the imaginary portion ZI measured during said discharge as a parameter representative of the charge state of the accumulator, said parameter representative of the charge state being defined by Γ
=ZI-2 f-3/2, where f is said fixed frequency and ZI is the imaginary portion of the complex impedance of the accumulator measured at said fixed frequency during discharge.
0 Assignments
0 Petitions
Accused Products
Abstract
The battery (3), which powers an apparatus (2), supplies an auxiliary circuit for a short time (5). A test and control component (6) of the device superimposes a low amplitude current interference Δi onto the discharge current (1). The interference signal frequency f is chosen acccording to the capacity and the discharge current of the battery (3). Processing of the frequency response of the battery (3) by the test and control component provides an indication of the combined impedence of the battery at that frequency. The value ZI =(ΔV/ΔI) sin (Δφ) of the imaginary part of the impedence so measured, or advantageously the value of the quantity Γ=ZI-2 f-3/2 thereby indicates the state of charge of the battery.
-
Citations
7 Claims
-
1. Method for measuring the charge state S of a nickel-cadmium accumulator, comprising the steps of:
-
(a) discharging the nickel-cadmium accumulator with a constant discharge current I; (b) measuring the imaginary portion ZI of the complex impedance of the accumulator at a fixed frequency during discharge; (c) using a quantity proportional to the imaginary portion ZI measured during said discharge as a parameter representative of the charge state of the accumulator, said parameter representative of the charge state being defined by Γ
=ZI-2 f-3/2, where f is said fixed frequency and ZI is the imaginary portion of the complex impedance of the accumulator measured at said fixed frequency during discharge. - View Dependent Claims (2)
-
-
3. Device for measuring the charge state of a nickel-cadmium accumulator, comprising:
-
(a) an intensiostatic circuit enabling the accumulator to be discharged under a test with a constant discharge current I and superimposing on this discharge current an alternative component at a fixed frequency; (b) a conditioner to condition a first signal at the terminals of the accumulator, said first signal consisting of a direct tension of the accumulator and of an alternative tension and having an output terminal; (c) a resistor serially connected to said accumulator; (d) a second signal at the terminals of said resistor, said second signal consisting of the discharge current and of the alternative current; (e) lock-samplers having output terminals to sample a signal at said output terminal of the conditioner; (f) a multiplexer having an output terminal to multiplex signals at an output terminal of the lock-samplers; (g) analog/digital converters to analog/digital convert signals at the output terminal of the multiplexer; and (h) control command means having a program housed in a memory allowing for required sequencing of the lock-samplers, of the multiplexer and of the analog/digital converters, calculation of the imaginary portion of the impedance from digitalized signals and extraction of the value of the charge state. - View Dependent Claims (4, 5, 6, 7)
-
Specification