Modular power systems

Abstract

Modular power systems, smart battery modules, and monitoring and control systems are described herein. A modular power system comprises at least one mains converter connected between a mains supply and a DC bus, a monitoring and control system connected to the DC bus, and a plurality of smart battery modules configured to be removably connected in parallel to the DC bus. Each battery module comprises a decoupling unit configured to electrically disconnect, or connect the battery module to, or from, the DC bus. The monitoring and control system is configured to monitor supply of mains power to the mains converter, the voltage of the DC bus, the terminal voltage of each smart battery module, and the magnitude of the load is that is present on the DC bus. The monitoring and control system is configured to control the DC output voltage of the mains converter; and control the decoupling unit of each smart battery module to be in one of at least a connected mode and a disconnected mode.

What is claimed is: 
     
         1 . A modular power system comprising:
 at least one mains converter connected between a mains supply and a DC bus;   a monitoring and control system connected to the DC bus; and   a plurality of smart battery modules configured to be removably connected in parallel to the DC bus;   wherein each smart battery module comprises a decoupling unit configured to electrically disconnect the smart battery module from, or connect the smart battery module to, the DC bus;   wherein the monitoring and control system is configured to:
 monitor supply of mains power to the at least one mains converter; 
 monitor a voltage of the DC bus; 
 monitor a terminal voltage of each smart battery module; 
 monitor a magnitude of a load that is present on the DC bus; 
 control a DC output voltage of the at least one mains converter; 
 control the decoupling unit of each smart battery module to be in one of at least: a connected mode, and a disconnected mode; and 
   wherein each smart battery module further comprises a buck-boost circuit configured to permit each smart battery module to be tested by discharging into a load of the buck-boost circuit (i) without altering voltage of the DC bus and (ii) without discharging the smart battery module into the DC bus.   
     
     
         2 . The modular power system of  claim 1 , wherein the at least one mains converter is a hot-swappable AC/DC rectifier. 
     
     
         3 . The modular power system of  claim 1 , where functions of the monitoring and control system are distributed between two or more members selected from the group consisting of: the plurality of smart battery modules, the at least one mains converter, and at least one control and monitoring module of the monitoring and control system. 
     
     
         4 . The modular power system of  claim 1 , wherein the modular power system is configured to schedule periodic testing of each smart battery module of the plurality of smart battery testing module. 
     
     
         5 . The modular power system of  claim 1 , wherein the monitoring and control system is configured to set at least one reference value within a memory of at least one smart battery module of the plurality of smart battery modules, wherein the at least one reference value comprises one or more items selected from the group consisting of: nominal charging current, trickle charging current, maximum charging current, nominal terminal voltage, low voltage disconnect voltage, self-discharge threshold, and connection threshold. 
     
     
         6 . The modular power system of  claim 1 , wherein each smart battery module is configured to selectively operate in a charging mode. 
     
     
         7 . The modular power system of  claim 6 , wherein the monitoring and control system is configured to adjust the DC bus voltage while smart battery modules of the plurality of smart battery modules are in the charging mode, to provide a charging current that does not exceed a maximum charging current of the smart battery modules. 
     
     
         8 . The modular power system of  claim 1 , wherein in the harmonization mode each smart battery module is configured to:
 determine deviation of its terminal voltage from the terminal voltage of other smart battery modules operating in the harmonization mode in the system; and   control charge current in the smart battery module if the deviation is outside a predetermined voltage range, until the deviation is within the predetermined voltage range.   
     
     
         9 . The modular power system of  claim 1 , wherein the monitoring and control system is configured to communicate with the at least one mains converter at least one item selected from the group consisting of: DC voltage set point levels for the DC bus, and disable/enable commands. 
     
     
         10 . The modular power system of  claim 1 , wherein the monitoring and control system is configured to communicate with the smart battery modules at least one item selected from the group consisting of: connect/disconnect commands for the decoupling unit, set values for the amount of self-discharge allowable during a float mode before the smart battery module reconnects to the DC bus to recharge, terminal voltage set points, low voltage disconnect thresholds, maximum charge current, and maximum discharge current. 
     
     
         11 . The modular power system of  claim 1 , wherein the buck-boost circuit is provided in the decoupling unit. 
     
     
         12 . A method for using a modular power system according to  claim 1 , the method comprising periodically testing each smart battery module by discharging at least a portion of charge of the smart battery module into the buck-boost circuit without altering voltage of the DC bus and without discharging the smart battery module into the DC bus. 
     
     
         13 . A smart battery module for a modular power system, the smart battery module comprising:
 a hot pluggable interface for connecting to a corresponding interface including a DC bus of the modular power system;   a plurality of battery cells;   a decoupling unit configured to electrically connect the battery cells to, or disconnect the battery cells from, the hot pluggable interface, and   a buck-boost circuit configured to permit the smart battery module to be tested by discharging into a load of the buck-boost circuit without (i) altering voltage of the DC bus and (ii) without discharging the smart battery module into the DC bus   a battery module monitoring and control system, wherein the battery module monitoring and control system is configured to:
 determine a terminal voltage of the plurality of battery cells; and 
 control the decoupling unit to either disconnect, or connect, the battery cells in order to allow the supply of power to, or allow receipt of power from, the DC bus of the modular power system through the hot pluggable interface. 
   
     
     
         14 . The smart battery module of  claim 13 , wherein the battery module monitoring and control system is further configured to:
 switch the decoupling unit from connected to disconnected according to one or more of:
 a current flowing out of the battery cells exceeding a predefined discharge current threshold; or 
 based on a combination of the magnitude of an over-current and a duration of the over-current; 
   detect a presence of other smart battery modules connected to the modular power system; and   after switching the decoupling unit from connected to disconnected, in response to detecting the presence of other smart battery modules, switch the decoupling unit from disconnected to connected.   
     
     
         15 . The smart battery module of  claim 13 , wherein a default mode of the decoupling unit is to disconnect the smart battery module from the DC bus. 
     
     
         16 . The smart battery module of  claim 14 , wherein the smart battery module is configured to enter into a float mode when the terminal voltage is within a predetermined voltage range of one or more of the other smart battery modules. 
     
     
         17 . The smart battery module of  claim 14 , wherein the smart battery module is controllable to operate in a harmonization mode in which the battery module monitoring and control system is configured to:
 determine deviation of its terminal voltage from the terminal voltage of one or more of the other smart battery modules operating in the harmonization mode; and   control charge current to the plurality of battery cells if the deviation is outside a predetermined voltage range, until the deviation is within the predetermined voltage range.   
     
     
         18 . The smart battery module of  claim 14 , wherein the battery module monitoring and control system is configured to control the decoupling unit to connect the battery cells to the DC bus when the DC bus voltage drops below the terminal voltage by a predefined threshold. 
     
     
         19 . The smart battery module of  claim 14 , wherein the decoupling unit is configured to be controllable to operate in a harmonization mode in which a limited current flow is permitted. 
     
     
         20 . The smart battery module of  claim 19 , wherein the battery module monitoring and control system is configured to switch the decoupling unit from the connected mode to the harmonization mode if the current flowing into the smart battery module exceeds a predefined discharge current threshold. 
     
     
         21 . The smart battery module of  claim 13 , wherein the buck-boost circuit is provided in the decoupling unit.