US 7,888,912 B2Granted

Battery SOC estimation program, wireless transit system, and method of charging the battery

AssigneeMitsubishi Heavy Industries, Ltd.

InventorsKatsuaki Morita, Masaya Mitake, Masahiro Yamaguchi, Hiroshi Yamashita, Masaomi Yamada, Kousuke Katahira

Life of this patent

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Abstract

Occurrence of overcharging and over discharging of batteries mounted on vehicles that travel on tracks in a wireless transit system is prevented by estimating a state of charge (SOC) of the batteries with accuracy. An equivalent circuit of the battery is composed of three circuit elements connected in series, including (i) a first component resistance R1 (ii) a component circuit which includes a capacitance C and a second component resistance R2 connected in parallel and (iii) an open circuit voltage of the battery. The open circuit voltage of the equivalent circuit is calculated using R1 calculated from measurements of current and voltage of the battery, as well as values k=R2/R1 and τ=C×R2. The SOC if the battery is calculated from the open circuit voltage.

Claims16

Dependent claims

A computer readable storage medium containing thereon a battery state of charge (SOC) estimation program execution by a computer to calculate an SOC of a battery mounted on a vehicle in a wireless transit system,

wherein an equivalent circuit of the battery is set in the program, the equivalent circuit being composed of three circuit elements connected in series, including:
(i) a first component resistance which is influenced by instantaneous current variation,
(ii) a component circuit which comprises a capacitance and a second component resistance connected in parallel, and which is influenced by slow and excessive response, and
(iii) an open circuit voltage of the battery, and wherein the program, when executed by the computer, causes the computer to calculate
(a) a value of the first component resistance from measurements of current and voltage of the battery,
(b) a value of the second component resistance from the calculated value of the first component resistance and a predetermined value of k, where
k=the second component resistance/the first component resistance,
(c) a value of the capacitance from the calculated value of the second component resistance and a predetermined value of τ, where
τ=the capacitance×the second component resistance,
(d) a potential of the component circuit from the calculated values of the second component resistance and the capacitance,
(e) a value of the open circuit voltage from the calculated potential of the component circuit, and
(f) the SOC from the calculated value of the open circuit voltage.

9 more elements

A wireless transit system, comprising:

a track;
a plurality of ground facilities distributed along the track, each said ground facility comprising
a charging power source device, and
a ground power supply device connected to the charging power source device;
and
a vehicle comprising a battery and adapted to travel on the track by electric power supplied from the battery, said vehicle further comprising
an in-vehicle power receiving device adapted to face the ground power supply device for charging the battery from the respective charging power source device when the vehicle makes a stop at any of the ground facilities,
a current and voltage detector for detecting current and voltage of the battery, and
a controller for calculating a state of charge (SOC) of the battery and for controlling the charging of the battery based on the SOC;
wherein an equivalent circuit of the battery is set as being composed of the three circuit elements connected in series, including:
(i) a first component resistance which is influenced by instantaneous current variation,
(ii) a component circuit which comprises a capacitance and a second component resistance connected in parallel, and which is influenced by slow and excessive response, and
(iii) an open circuit voltage of the battery, and
wherein the controller is configured to calculate
(a) a value of the first component resistance from the detected current and voltage of the battery,
(b) a value of the second component resistance from the calculated value of the first component resistance and a predetermined value of k, where
k=the second component resistance/the first component resistance,
(c) a value of the capacitance from the calculated value of the second component resistance and a predetermined value of τ, where
τ=the capacitance×the second component resistance,
(d) a potential of the component circuit from the calculated values of the second component resistance and the capacitance,
(e) a value of the open circuit voltage from the calculated potential of the component circuit, and
(f) the SOC from the calculated value of the open circuit voltage.

19 more elements

In a wireless transit system, a method of controlling charging of a battery mounted on a vehicle powered by the battery, wherein an equivalent circuit of the battery is set as being composed of three circuit elements connected in series, including:

(i) a first component resistance which is influenced by instantaneous current variation,
(ii) a component circuit which comprises a capacitance and a second component resistance connected in parallel, and which is influenced by slow and excessive response, and
(iii) an open circuit voltage of the battery, and said method comprising the following steps performed by a controller of the vehicle:
determining a state of charge (SOC) of the battery by calculating
(a) a value of the first component resistance from the detected current and a voltage of the battery,
(b) a value of the second component resistance from the calculated value of the first component resistance and a predetermined value of k, where
k=the second component resistance/the first component resistance,
(c) a value of the capacitance from the calculated value of the second component resistance and a predetermined value of τ, where
τ=the capacitance×the second component resistance,
(d) a potential of the component circuit from the calculated values of the second component resistance and the capacitance,
(e) a value of the open circuit voltage from the calculated potential of the component circuit, and
(f) the SOC from the calculated value of the open circuit voltage;
and controlling the charging of the battery based on the calculated SOC.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/302,851Filed 29 Nov 2007
Priority: JP 2006-32464330 Nov 2006
Published: US 2009/0195219 A16 Aug 2009
Granted: 15 Feb 2011
Term ends: Not estimatedThe source records don’t support an estimate.

Classification19 codes

B60L 3/0046
Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train: relating to electric energy…
B60L 53/11
Characterised by the energy transfer between the charging station and the vehicle: dC charging controlled by the charging station, e.g. mode 4
B60L 58/13
Responding to state of charge [SoC]: maintaining the SoC within a determined range
B60L 58/14
Responding to state of charge [SoC]: preventing excessive discharging