# US 10,120,032 B2 · Device and method for estimating secondary cell status

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- Number: US 10,120,032 B2
- Document ID: US10120032B2
- Status: Granted
- Kind: B2
- Application number: 14/375,734
- Filed: 2012-09-18
- Published: 2015-02-12
- Granted: 2018-11-06
- Earliest claimed: 2012-03-13
- Assignees: Primearth Ev Energy Co., Ltd.
- Applicants: Primearth EV Energy Co., Ltd.
- Inventors: Naoshi Akamine
- Web page: https://patentgrep.com/patent/US10120032B2

## CPC

- B60L 58/10: for monitoring or controlling batteries
- G01R 31/3648: {comprising digital calculation means, e.g. for performing an algorithm}
- G01R 31/367: Software therefor, e.g. for battery testing using modelling or look-up tables
- H01M 10/425: {Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing (printed circuits H05K1/00)}
- H01M 10/48: Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569)
- H01M 10/482: {for several batteries or cells simultaneously or sequentially}
- H01M 10/486: {for measuring temperature}
- G01R 31/3842: combining voltage and current measurements
- G01R 31/396: Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
- H01M 2010/4271: {Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing}
- H02J 7/50: acting upon multiple batteries simultaneously or sequentially
- H02J 7/82: Control of state of charge [SOC]
- Y02E 60/10: Energy storage using batteries
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Provided is a device for estimating secondary cell status using multiple models. The device for estimating secondary cell status uses multiple models, model 1, model 2, and model 3, to estimate the status of respective secondary cells. An arithmetic unit compares the estimated voltage values obtained from model 1, model 2, and model 3 with measured voltage values, sets the model having the highest correlation as the optimal model, optimizes the parameters of such model, and estimates secondary cell status.

## Claims

### Claim 1

A secondary cell system for estimating a secondary cell status comprising:
a secondary rechargeable cell comprising a plurality of battery blocks connected in series;
voltage detection means connected to the secondary cell for detecting a voltage of the secondary cell;
current detection means connected to the secondary cell for detecting a current of the secondary cell;
a vehicle engine control unit (ECU) and a battery control unit; and
the battery electronic control unit is connected to the voltage detection means and the current detection means and that estimates the secondary cell status by use of a plurality of models, the battery electronic control unit performing steps including:
optimizing parameters used respectively in the plurality of models by use of the voltage value detected by the voltage detection means,
after optimizing the parameters, selecting, as an optimum model, a model involving least change in an amount of parameter correction from among the plurality of models having the optimized parameters, and
then estimating the secondary cell status by use of the selected optimum model, wherein the plurality of models is selected from at least two of the following:
a first model in which an estimated voltage is obtained by adding an estimated voltage drop due to an internal resistance (DCIR) of the secondary cell, an estimated linear polarization value and an estimated hysteresis value estimated by the use of a predetermined polarization voltage-model, and an electromotive voltage based on an SOC obtained by integrating a current of the secondary cell;
a second model in which the estimated voltage is obtained by adding the estimated DCIR voltage drop, an estimated short-term linear polarization value and an estimated long-term linear polarization value estimated by the use of the polarization voltage model, and the electromotive voltage based on the SOC; and
a third model in which the estimated voltage is obtained by adding the estimated DCIR voltage drop, the estimated short-term linear polarization value and the estimated long-term polarization value estimated by the use of the polarization voltage model, and an electromotive voltage obtained by the use of a predetermined dynamic battery model; and
transmitting, at least, the cell status to a vehicle ECU, wherein the vehicle ECU controls the charging and discharging of the secondary cell;
based at least on the cell status, the ECU outputs a control command discharging the secondary cell to an DC to AC inverter to power an electric motor;
based at least on the cell status, the ECU outputs a control command charging the secondary cell by actuating an engine and generator.

### Claim 2 (depends on 1)

The secondary cell system for estimating a secondary cell status according to claim 1, wherein the computation means optimizes the parameters used respectively in the plurality of models at every predetermined period and selects, as an optimum model, the model involving the least change in the amount of parameter correction acquired from the plurality of models having the optimized parameters.

### Claim 3 (depends on 1)

The secondary cell system for estimating a secondary cell status according to claim 1, wherein the parameter is optimized by means of any two or more selected from among the voltage value detected by the voltage detection means, a current value detected by current detection means, and a temperature detected by temperature detection means.

### Claim 4 (depends on 1)

The secondary cell system of claim 1, further comprising a vehicle electronic control unit, wherein the battery electronic control unit transmits the detected state of charge to the vehicle electronic control unit, and the vehicle electronic control unit controls charging the secondary cell status based on at least the detected state of charge.

### Claim 5 (depends on 1)

The secondary cell system of claim 1, wherein the plurality of models output an estimated voltage.

### Claim 6 (depends on 1)

A vehicle including the secondary cell system of claim 1, further comprising:
an engine;
a generator connected to the engine through a power splitting mechanism, wherein the generator charges the secondary cell;
a motor connected to an inverter, wherein the secondary cell is discharged through the inverter; and
a drive shaft connected to the engine through the power splitting mechanism and the drive shaft is connected to the motor.

### Claim 7 (depends on 1)

The secondary cell system for estimating a secondary cell status according to claim 1, wherein the polarization voltage model in the first model is formed by a parallel connection of a resistor and a capacitor.

### Claim 8 (depends on 1)

The secondary cell system for estimating a secondary cell status according to claim 1, wherein the electromotive voltage in the first model and the second model is obtained by the use of a relationship between the SOC and the electromotive voltage which is set in advance.

### Claim 9 (depends on 1)

The secondary cell system for estimating a secondary cell status according to claim 1, wherein the polarization voltage model in the second model and the third model is formed by a parallel connection of a short-term polarization resistor and a short-term polarization capacitor and a parallel connection of a long-term polarization resistor and a long-term polarization capacitor.

### Claim 10 (depends on 1)

The secondary cell system for estimating a secondary cell status according to claim 1, wherein the dynamic battery model in the third model is a model in which, when electric charges include bound charges QB and available charges QA, a capacity ratio of the bound charges is 1−C, and a capacity ratio of the available charges is C, voltages h1 and h2 are expressed as:
h1=QA/C, and
h2=QB/(1−C),
wherein, when i is a current and k is a parameter,
dQA/dt=−i+k(h2−h1), and
dQB/dt=−k(h2−h1).

### Claim 11 (depends on 1)

The secondary cell system for estimating a secondary cell status according to claim 1, wherein a parameter Θ(k) which is used respectively in the plurality of models is updated, in the optimizing step, by
Θ(k)=Θ(k−1)+G(k)[Vmeas(k)−Vemf(k)−ΘT(k)Θ(k−1)]
where k is a parameter of time-sequential data, Vmeas(k) is a time-sequential measured voltage, Vemf is a time-sequential electromotive voltage, Φ is a vector having an estimated value as a component, and G is a gain, and the amount of parameter correction is given by G(k)[Vmes(k)−Vemf(k)−ΦT(k)Θ(k−1)].

### Claim 12 (depends on 1)

The secondary cell system for estimating a secondary cell status according to claim 1, wherein the process further performs a step of determining an excessively charged secondary cell when the estimated state of charge value is in a vicinity of a predetermined lower limit or determining an excessively charged secondary cell when the estimated state of charge is in a vicinity of a predetermined upper limit, and, for a secondary cell that is not excessively charged or discharged, selecting an optimum model from the plurality of models by use of the voltage value detected by the voltage detection means, and then optimizing parameters in the selected optimum model.