Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
  • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
  • G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
  • G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
  • G01R19/16542—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies for batteries
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
  • G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
  • G01R31/374—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] with means for correcting the measurement for temperature or ageing
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
  • G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits

Definitions

• This invention relates to a system for monitoring a bank of batteries.
• Batteries or more often banks of batteries, are often used as standby power supplies. When the mains are removed or are not present such standby batteries will take the load. Batteries may also be used for backup and starting a backup generator.
• a battery may be monitored by measuring the voltage while under charge. Several failure modes can be detected.
• the present invention consists in a battery measunng - module for a system for monitoring a plurality of batteries wherein said measuring module is associated with and measures parameters of one or more of a small number of physically proximate batteries, said measuring module comprising: at least one analogue input port which in use is connected to at least one battery, an analogue-to-digital converter connected to said at least one input port which produces digital values proportional to the voltage on said at least one input port, a device which stores said digital values, and a digital output port, said device presenting said digital values in serial form at the digital output port.
• the invention consists in a monitoring system for a bank of batteries comprising: a digital central processing unit which is capable of storing and processing digital parameters for each battery in the bank, said central processing unit having one or more serial input-output ports, one or more data buses, each connected to a respective serial input-output port on said central processing unit, and, connected to and in association with one or more of a small number of physically proximate batteries in said bank, a measuring module which may be polled by said central processing unit, said measuring module including: at least one analogue input port which in use is connected to at least one battery, an analogue-to-digital converter connected to said at least one input port which produces digital values proportional to the voltage on said at least one input port, a device which stores said digital values, and a digital input-output port, said device presenting said digital values in serial form at the digital input-output port upon receipt of a polling signal at said port, said digital input-output port of each measuring module being connected to said data bus or one
• FIG. 1 is a block diagram of a battery monitoring system according to the present invention
• Figure 2 is a block circuit diagram of a measuring module for a single battery
• Figure 3 is a waveform diagram illustrating the operation of the battery measurement module
• Figure 4 is a block diagram of a measuring module for a plurality of batteries with the voltages input through a multiplexer
• Figure 5 is a block diagram of a measuring module for a plurality of batteries with the voltages input through a resistive divider network.
• a battery bank 1 which may contain a number of batteries, has associated with a small group, preferably four, of batteries or cells a measurement module 2 which among other things measures the cell voltage and cell temperature, converts the values into digital form and supplies these values in serial form via a bus 3 to a central processing unit (CPU) 4 which stores and analyses the values and provides an indication of the status of each battery and produces alarms when appropriate.
• a number of measurement modules 2 may be connected to common buses and each central processing unit 4 may receive inputs from more than one bus. The communication protocol from each measurement module 2 to each central processing unit 4 will be described later.
• Central processing units may be networked by an RS485 serial interface and may optionally supply data to a personal computer 6 for further analysis via an RS232 serial interface 7.
• the measurement module works as follows.
• the measurement module 2 connected to each battery measures the battery voltage.
• the measurement module also measures a reference voltage inside the module along with the battery temperature.
• the CPU 4 converts the values that the measurement module transmits to a calibrated voltage.
• the calibration constants for each connected measurement module are stored at the CPU. There is no theoretical limit on the number of measurement modules that can be connected to a measurement module bus but the number connected does affect the sample speed. For practical reasons the present system has a maximum of 10 modules per bus delivering 5 samples per second. Operation of Measurement Module
• each measurement module 2 is connected to a single battery 8 and may be external to the battery or integrated with it as shown in Figure 2.
• the battery voltage is attenuated 9 by a voltage divider and supplied to the analogue multiplexer 10.
• the internal reference voltage 13 and the output of temperature sensor 14 are also inputs to the analogue multiplexer 10 and thus are also converted by the analogue-to-digital converter.
• FIG. 1 shows the timing diagram of the single slope analogue-to-digital conversion process implemented by the analogue- to-digital converter and micro-controller combination. These digital values are held by the micro-controller 12 and will be transmitted via the bus 3 upon command from the CPU 4.
• the measurement module derives its power from the battery it is measuring and where the nominal battery voltage being monitored is too low for this purpose, the measuring module will include a step-up converter.
• the micro-controller serial output port is isolated from the serial bus 3 by an optical isolation stage 15.
• the measurement module 2 provides isolation at the battery itself ensuring that the serial bus 3 is isolated with respect to ground.
• micro-controller 12 in conjunction with CPU 4 provides data transfer from each measurement module by serial transmission.
• CPU 4 polls the microcontroller 12 in each measurement module to cause transfer of the stored voltage and temperature values to CPU4.
• a single set of values may be stored by micro-controller 12 or alternatively many sets of values may be stored in which case the polling frequency may be reduced.
• Each measurement module 2 has an 8 bit address. To initially configure the measurement bus 2 the CPU 4 polls each address from 0 to 254, then compiles a table of valid addresses. This takes around 20 seconds. These addresses are then used for future communication. Replacing a measurement module simply requires the CPU 4 to re-scan all addresses on a measurement bus port. At 5760 baud this will take less than 6 seconds.
• the CPU 4 does not receive a response to a poll during normal operation, it will wait 10 seconds then run a complete address poll.
• the measurement module with the new address should inherit the configuration from the missing module. Data is transferred most significant byte first. Asynchronous protocol follows
• the measurement modules must use timing to synchronise to the measurement bus protocol as there is no delimiter support in the measurement bus protocol. After receiving the address byte, the measurement module looks for the start condition of the second byte. If this has not occurred within 4 bit times then the measurement module starts looking for another address byte.
• the CPU 4 must send messages with inter-packet delays of greater than 8 bit times.
• the delay between transmitted bytes in the same packet should not exceed 3 bit times.
• each measurement module is connected to a small group of batteries 16, preferably four as shown in Figure 4.
• An analogue multiplexer 17 connects each battery 16, as instructed by the micro controller 12, to a signal conditioning module 18 which provides attenuation to a voltage suitable for an analogue-to-digital converter 19, and low pass filtering for noise reduction.
• An analogue temperature sensor 20 is attached to the case of each battery 16 to indicate exterior battery temperature. Both the output of each temperature sensor 20 and the output of the signal conditioning module 18 are connected to the inputs of the analogue-to-digital converter 19.
• the analogue-to-digital converter 19 used may be of the commercially available variety, and its output is connected to the input of the micro controller 12, which will store and transfer the data to the CPU 4. In this embodiment a fault in a connection between adjacent batteries 21 can be detected by analysing the voltage drop between the terminals of those adjacent batteries.
• each measurement module is connected to a small group of batteries 16, preferably four as shown in Figure 5.
• a signal conditioning module 22 provides attenuation of all the voltages from the group of batteries 16 to a voltage suitable for an analogue-to-digital converter 19, and low pass filtering for noise reduction.
• An analogue temperature sensor 20 is attached to the case of each battery 16 to indicate exterior battery temperature. Both the output of each temperature sensor 20 and the outputs of the signal conditioning module 22 are connected to the inputs of the analogue-to-digital converter 19.
• a range of reference voltages 23 are required to compensate for the different voltage that each battery is referenced at. These reference voltages 23 are connected to another analogue multiplexer 24 which is connected to the input of the analogue-to-digital converter 19.
• the micro controller 12 will decide which of the reference voltages 23 to switch in based upon the overall voltage.
• the analogue- to-digital converter 19 used may be of the commercial available variety, and its output is connected to the input of the micro controller 12, which will store and transfer the data to the CPU 4.
• This embodiment has the advantage of speed over the second embodiment. However the second embodiment is more accurate, using the full resolution of the analogue to digital converter 19 over each battery, whereas for the third embodiment the analogue-to-digital converter 19 resolution spans over the overall voltage.
• the present invention provides a battery monitoring system which has many advantages over conventional systems. Isolation provided near each battery ensures that no battery potential is connected to the central processing unit. Further, only one data cable pair is required for every ten (or in the case of the second and third embodiment up to forty) batteries and each measurement module can accommodate batteries from between 2 to 12 volts. For large battery banks the central processing units may be provided with additional serial ports to allow the monitoring of further multiples often (or forty) batteries. Because the measuring module is intended to be either located physically to the battery or integrated within the battery case, battery temperature may be measured without the need for separate outboard circuitry.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Tests Of Electric Status Of Batteries (AREA)
• Secondary Cells (AREA)

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• 1998
  • 1998-11-19 WO PCT/NZ1998/000168 patent/WO1999027628A1/en not_active Application Discontinuation
  • 1998-11-19 AU AU16961/99A patent/AU724902B2/en not_active Ceased
  • 1998-11-19 EP EP98961698A patent/EP1040546A4/de not_active Withdrawn

Patent Citations (5)

Non-Patent Citations (1)

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