Battery System

• US 20170141589A1
• Filed: 06/15/2015
• Published: 05/18/2017
• Est. Priority Date: 06/30/2014
• Status: Active Grant

• Current Assignee: Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Original Assignee: Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Inventors: MATSUMOTO, Tetsuya, INOUE, Takeshi, YAMADA, Keizo
• Granted Patent: US 10,461,545 B2
• Time in Patent Office: Days
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 53/62 in response to charging parameters, e.g. current, voltage or electrical charge
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: B60R 16/033 characterised by the use of electrical cells or batteries for propulsion puposes B60K1/04; supplying batteries to, or removing batteries from, vehicles B60S5/06; testing of charge state G01R31/36
• CPC Class Codes: B60Y 2300/91 Battery charging
• CPC Class Codes: B60Y 2400/112 Batteries
• CPC Class Codes: H02J 5/00 Circuit arrangements for transfer of electric power between ac networks and dc networks H02J3/36 takes precedence
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: H02P 1/00 Arrangements for starting electric motors or dynamo-electric converters starting of synchronous motors with electronic commutators H02P6/20, H02P6/22; starting dynamo-electric motors rotating step by step H02P8/04; vector control H02P21/00
• CPC Class Codes: H02P 9/008 wherein the generator is controlled by the requirements of the prime mover
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 : Electric charging stations
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 : Information or communication technologies improving the operation of electric vehicles

Abstract

In a battery system that connects a plurality of types of batteries through a switch SW, when the switch SW is switched at a voltage (charge rate), it has been possible to increase a stored charge during charging, depending on the DC resistance of the battery. An object of the present invention is to provide switch SW switching control so that the stored charge can further be increased. A first feature of the present invention is to provide a battery system in which a first battery and a second battery are connected in parallel through the switch SW, including an estimator which estimates the charging current by measuring the resistance and OCV of each battery. The battery system can further increase the stored charge by switching to a switch SW combination that can increase the stored charge.

Claims

1. A battery system that connects a first battery and a second battery in parallel through a switch SW, the battery system comprising:

an estimator which estimates a charging current of the first battery at least from an internal resistance of the first battery; and

an estimator which estimates a charging current of the second battery at least from an internal resistance of the second battery,

wherein the switch SW is switched by a procedure in which a sum of a stored charge in the first battery and a stored charge in the second battery increases, based on the charging current of the first battery and the charging current of the second battery.

2. The battery system according to claim 1,

wherein the switch SW includes a first switch SW and a second switch SW,

wherein the first switch SW and the second switch SW are connected in parallel,

wherein the first battery is connected to a load through the first switch SW, and

wherein the second battery is connected to the load through the second switch SW.

3. The battery system according to claim 1,

wherein, during a discharge, the second battery first discharges, and the second battery is switched to the first battery and the first battery discharges when the second battery reaches a. predetermined voltage or a charge rate, or

the first battery first discharges, and the first battery is switched to the second battery and the second battery discharges when the first battery reaches a predetermined voltage or a charge rate.

4. The battery system according to claim 1,

wherein the procedure is to switch the switch SW once during a regenerative charging,

wherein, under an assumption that a regeneration time is T, a charging time of the second battery is τ

(T>

τ

), and a first charging time is T−

τ

, the second battery first is charged, and the switch SW is switched to the first battery at the timing τ

at which a charge amount of the first battery and a charge amount of the second battery are the maximum.

5. The battery system according to claim 4,

wherein τ

is a time t from a start of charge, in which i1(t)=i2 (a charge completion time−

t) by estimating a current time series of the first battery (i1(t)) and a current time series of the second battery (i2(t)), and the second battery is first charged, and the switch SW is switched so as to select the first battery after t has elapsed from the start of charge.

6. The battery system according to claim 4,

wherein when the regenerative charging time T is unknown, a time t is obtained at which the current time series of the first battery is equal to the current convergence value of the second battery, and defines the time t as the τ

.

7. The battery system according to claim 1,

wherein the procedure is to switch the switch SW two or more times during a regenerative charging, and

wherein an estimated charging current of the first battery is compared with an estimated current of the second battery, and the switch SW is switched so that the battery is selected with the larger of the two estimated currents.

8. The battery system according to claim 7,

wherein the switch SW is switched at regular intervals and each battery is charged until the individual charging of either the first battery or the second battery attains to a constant voltage charge.

9. The battery system according to claim 8,

wherein a time rate of the switch SW of the first battery is initially set to 1 when the first battery is charged with a constant current, and the time rate of the switch SW of the first battery is changed to (voltage in constant voltage charging of alternator−

open circuit voltage of first voltage)/(current of alternator during constant current charging×

polarization resistance) after the first battery is in a constant current charge completion state,

10. The battery system according to claim 8,

wherein the load is an alternator, and

wherein the time rate of the switch SW of the first battery is controlled so that the following equation is true when the first battery is charged with a constant current:

Current in constant current charging of alternator=Polarization voltage of second battery/(polarization resistance of second battery*(1+polarization capacity of second battery/capacity of second battery))+Polarization voltage of first battery vp(t)/Polarization resistance of first battery.

11. The battery system according to claim 1,

wherein the procedure is to switch the switch SW two or more times during a regenerative charging,

wherein when the switch SW is switched two or more times while a simultaneous connection is permitted during a charging, the charging current of the first battery and the charging current of the second battery for three following cases are estimated:

an individual charging of the first battery;

an individual charging of the second battery; and

connection to both of the first and second batteries, and when the first battery or the second battery discharges, the switch SW is switched so that the battery with the larger of the two charging currents between the first and second batteries is connected, and otherwise, when a constant voltage charging takes place with the battery alone, both the first and second batteries are connected, and further otherwise, the rate of the switch SW ON time of the first battery alone, the rate of the switch SW ON time of the second battery alone, and the rate of the switch SW time for connecting both batteries are controlled, in order to perform a constant current charging.

15. The battery system according to claim 1,

comprising a measure which measures a voltage and current of the first battery, a voltage current of the second battery, and a voltage of the alternator and auxiliary equipment,

wherein the DC resistance of the first battery, the resistance of the switch SW, the polarization capacity, the polarization resistance, the polarization voltage, the open circuit voltage, and the capacity of the second battery are measured.

16. The battery system according to claim 15,

wherein the DC resistance of the battery and the resistance of the switch SW are obtained from the change in the voltage and current before and after the switch SW changes from ON to OFF, or before and after the switch SW changes from OFF to ON, and the open circuit voltage of the battery is obtained as Battery voltage−

DC resistance×

Current.

18. The battery system according to claim 15,

wherein the parameters are estimated as Polarization voltage=−

Polarization voltage before measurement time×

(1−

measurement time step size/(polarization resistance×

polarization capacity))+Measurement current×

Measurement time step size/Polarization capacity.

19. The battery system according to claim 16,

wherein the open circuit voltage of the battery to be in a steady state is defined as Measured open circuit voltage−

Polarization voltage.

12-14. -14. (canceled)

17. (canceled)

20-24. -24. (canceled)