Battery-state monitoring system

• US 9,297,859 B2
• Filed: 10/17/2012
• Issued: 03/29/2016
• Est. Priority Date: 11/08/2011
• Status: Expired due to Fees

• Current Assignee: Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Original Assignee: Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Inventors: Mukaitani, Ichiro, Kofuse, Takashi, Kanoh, Mitsuyoshi, Mizusugi, Shinya, Shibata, Yasuhiro
• Primary Examiner(s): DIAO, M BAYE
• Application Number:
  US14/356,785
• Publication Number:
  US 20140285156A1
• Time in Patent Office: 1,259 Days
• Field of Search: 320/134, 320/136, 324/426, 324/430, 324/434
• US Class Current: 1/1
• CPC Class Codes: G01R 31/371 with remote indication, e.g. on external chargers
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin

Abstract

A battery-state monitoring system for precisely and efficiently estimating the state and service life of each of a plurality of storage batteries while suppressing variations in voltage between the batteries in a large-scale power-supply system that is provided with the storage batteries charged with power generated by utilizing natural energy is provided. The system includes a power supply control device that detects a current in each storage battery, an end device that measures temperature, voltage, and internal resistance of each battery, the internal resistance being measured by using at least two or more kinds of frequencies, and a prime monitoring device that acquires measurement data from the end device corresponding to each battery and issues an instruction related to an operation to the power supply control device and the end device. The prime monitoring device estimates degradation of each battery based on one or more of temperature, voltage, internal resistance.

Claims

1. A battery-state monitoring system which monitors a state of each of a plurality of storage batteries in an equipment provided with an assembled battery composed of the storage batteries connected in series and a power generation facility utilizing natural energy, the system comprising:

a current detecting unit which detects a current in each of the storage batteries;

a state measuring unit which measures a temperature, a voltage, and internal resistance of each of the storage batteries, the internal resistance being measured by using at least two or more kinds of frequencies including at least a first frequency of lower than 200 Hz and a second frequency of 200 Hz or higher to lower than 2000 Hz; and

a prime monitoring unit which acquires measurement data from the state measuring unit corresponding to each of the storage batteries and issues an instruction related to an operation to the current detecting unit and the state measuring unit,

wherein the prime monitoring unit estimates degradation of each of the storage batteries based on at least one or more values of the temperature, the voltage, and the internal resistance measured by the state measuring unit and a DC resistance of each of the storage batteries obtained from a ratio between a change in a current value detected by the current detecting unit and a change in a voltage value measured by the state measuring unit during discharging and charging of each of the storage batteries, and the prime monitoring unit applies a constant current from the state measuring unit to the storage battery whose voltage is higher than a predetermined value, thereby decreasing the voltage.

2. The battery-state monitoring system according to claim 1, comprising:

a control unit which controls discharging from the storage battery to a load and charging to the storage battery with surplus power from the power generation facility,

wherein the prime monitoring unit instructs the control unit to connect the storage battery to a discharge circuit to the load when a measurement value of the voltage of the storage battery acquired from the state measuring unit is equal to or higher than a predetermined overdischarge preventive voltage, and instructs the control unit to disconnect the storage battery from the discharge circuit when the measurement value of the voltage is lower than the overdischarge preventive voltage, and

the prime monitoring unit instructs the control unit to connect the storage battery to a charge circuit from the power generation facility when the measurement value of the voltage is equal to or lower than a predetermined overcharge preventive voltage and when the measurement value of the voltage is higher than the overcharge preventive voltage and a charge current value to the storage battery detected by the current detecting unit is equal to or larger than a predetermined value, and instructs the state measuring unit to acquire a value of internal resistance of the storage battery and also instructs the control unit to disconnect the storage battery from the charge circuit when the measurement value of the voltage is higher than the overcharge preventive voltage and the charge current value to the storage battery detected by the current detecting unit is smaller than the predetermined value.

3. The battery-state monitoring system according to claim 2,

wherein the prime monitoring unit instructs the control unit to disconnect the storage battery from the discharge circuit and also instructs the state measuring unit to extend a measurement interval of a parameter of the storage battery when the measurement value of the voltage of the storage battery acquired from the state measuring unit is lower than the overdischarge preventive voltage.

4. The battery-state monitoring system according to claim 1,

wherein, when measuring the internal resistance of the storage battery, the state measuring unit applies a current through the storage battery, thereby decreasing the voltage of the storage battery.

5. The battery-state monitoring system according to claim 1,

wherein the state measuring unit measures the internal resistance of the storage battery by using three kinds of frequencies including the first frequency set to be lower than 100 Hz, the second frequency set to be 350 Hz or higher to lower than 2000 Hz, and a third frequency of 100 Hz or higher to lower than 350 Hz.

6. The battery-state monitoring system according to claim 1,

wherein, when a temperature value and/or a voltage value of the storage battery measured by the state measuring unit exceed a given value or decrease below a given value, it is determined that the storage battery has a problem, and

degradation of the storage battery is estimated based on internal resistance of the storage battery measured by the state measuring unit and/or a change rate of a DC resistance value from an initial value during discharging of the storage battery.

7. The battery-state monitoring system according to claim 1, comprising:

an end device composed of the state measuring unit;

a prime monitoring device composed of the prime monitoring unit; and

a station device which relays a communication between the prime monitoring device and the end device,

wherein one or more station devices are connected to the prime monitoring device so as to enable communication therebetween, and

one or more end devices are connected to each of the station devices so as to enable communication therebetween.

8. The battery-state monitoring system according to claim 7,

wherein the communication between the station device and the end device is radio communication.

9. The battery-state monitoring system according to claim 7,

wherein the end device measures internal resistance of the storage battery based on an instruction from the prime monitoring device sent through the station device.

10. The battery-state monitoring system according to claim 7,

wherein the end device does not carry out transmission of measurement data through the station device to the prime monitoring device when a given time has not passed from previous transmission.

11. The battery-state monitoring system according to claim 7,

wherein the end device is fixedly installed to the storage battery.