Electrical transmission or interconnection systems – Plural supply circuits or sources – Substitute or emergency source
Reexamination Certificate
2001-04-19
2003-08-12
Sircus, Brian (Department: 2836)
Electrical transmission or interconnection systems
Plural supply circuits or sources
Substitute or emergency source
C363S037000
Reexamination Certificate
active
06605879
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to battery charging control circuits, and more particularly relates to battery charging control circuits in uninterruptible power supply (UPS) systems.
BACKGROUND OF THE INVENTION
As more and more segments of the business environment enter the information age, more and more computers and computing power are required. As businesses move from the old to the new economy their reliance on the processing, transference, and storage of digital information is becoming a more and more critical aspect of their overall business strategy. While in the past, computer crashes were seen as a mere nuisance, the loss of computing power and business data may well devastate a business's ability to survive in today's new economy. As such, the need for reliable, uninterruptible electric power to maintain the operational status of the computing equipment and the integrity of the digital data continues to rise.
To meet these requirements, uninterruptible power supplies (UPS) have been developed. These UPSs utilize a bank of electric storage batteries and solid state conversion and charging equipment to provide continuous electric power to a business's computer systems in the event of a loss of power from the utility or a deviation from the normal regulated utility specifications. The number of batteries contained within an UPS is dependent upon the business's length of time and its needs to operate in the event of a utility power system failure. Further, the number of power inverters required to supply the total load demand of a business also controls the size and number of inverters necessary in the UPS. The number of battery chargers is also somewhat dependent on these factors and the business's requirement for the speed at which discharged batteries are required to come back online.
Since each of these parameters are dependent upon the particular make-up, structure, and operational requirements of different businesses, the provision of any single UPS configuration will likely only completely meet the needs of a small segment of the overall business environment. As such, modular uninterruptible power supplies have been developed that allow, to some extent, the ability to reconfigure an UPS based upon the actual requirements of any particular business. For businesses that have only a small power output requirement but with a corresponding long duration need, their modular UPS may be configured with multiple battery banks and only a single inverter. Another business may have a larger power draw requirement necessitating the inclusion of multiple inverters.
Indeed, the particular requirements of any single business may change depending on the nature of their business. For example, while a business may have a short term high power requirement of its UPS, business operating procedures may dictate that non-essential computing equipment be taken off-line as it appears that a power failure may last an extended period of time. In such a situation, additional power inverters required during the short term power losses may then be replaced with additional battery banks to provide a long term power supply to critical computing equipment during the power outage event.
While an UPS will allow continued operation of the utilization equipment during a power loss, if this power loss lasts for an extended period of time the batteries of the UPS will become depleted. Once this has occurred, both the UPS and the utilization equipment will be shut down due to a lack of power. If the batteries become completely depleted, if batteries that have not been charged are installed in the UPS, or if the batteries are removed from the UPS, the UPS will be unable to resume or start operation when the main line power is restored. This is because typical UPS's require that their housekeeping circuitry be powered to operate. Since the typical UPS derives the power for the housekeeping circuitry from the batteries, this circuitry cannot operate when the batteries are discharged or missing.
To overcome this problem, prior UPS's require that fresh batteries be installed, or that an external battery charger be used to charge the depleted batteries before the UPS can resume operation. Until one of these is accomplished, the utilization equipment cannot be used, unless the UPS is taken out of the circuit and the utilization equipment is connected directly to the incoming line voltage. Once the batteries are charged, the utilization equipment must then be disconnected from the main line voltage and reconnected to the UPS in order to be protected from the future power outages. Not only is this manual reconfiguration of power lines is time consuming and unproductive, but it also requires that the very equipment that is meant to be protected from power outages must be de-powered to be reconnected to the UPS once it is again ready to operate. This greatly reduces the user experience of such systems.
BRIEF SUMMARY OF THE INVENTION
In view of the above, it is therefore and object of the present invention to provide a new and improved battery charger circuit for an uninterruptible power supply (UPS) system. More particularly, it is an object of the present invention to provide a new and improved battery charger circuit for an UPS system that is capable of starting the UPS with severely depleted batteries. It is a further object of the invention to provide a battery charger circuit that is capable of starting a UPS with no batteries installed. Preferably, this functionality is achieved without any control from the main battery charger control circuitry. Further, this functionality is achieved in a safe manner avoiding any overcharging of the batteries.
In one embodiment of the present invention, the battery charger circuit is operational when the main AC line power is restored or coupled to the UPS system. The circuit of the present invention charges the severely depleted batteries that are at or near 0 volts DC in a short time to a level where the housekeeping circuitry of the UPS can wake up to allow operation of the UPS. Additionally, if no batteries are installed in the UPS, the circuitry of the present invention charges the battery bus to a safe level to allow the housekeeping circuitry to wake up. This ability to maintain the battery bus voltage without batteries installed enables hot swapping of the batteries without taking the UPS off-line.
Operation of an embodiment of the battery charger circuitry of the present invention begins and may continue without functioning of the main battery charger control. During such a situation, the circuitry of the present invention will charge the batteries to near full capacity by limiting the voltage so that the batteries are not overcharged. Likewise, the circuitry of the present invention will regulate the battery bus voltage to maintain the housekeeping circuitry without the main control being operational. When the main UPS control becomes functional, the circuitry of the present invention will yield control of the battery charging and maintenance.
In one embodiment of the present invention, the modular UPS includes a number of power modules that are capable of supplying output AC power from either the input AC mains or from the battery. Each of the power modules in this embodiment include battery charging circuitry, including the circuitry of the present invention. This circuitry may be paralleled with the circuitry from the other power modules to charge the batteries and maintain the battery bus. This circuitry contains fail-safe circuitry to ensure that a failure in any one of the power modules will not overcharge the batteries or bring the battery bus down.
In a preferred embodiment an uninterruptible power supply (UPS) system comprises a power module having an input adapted to receive AC mains power, and an output adapted to supply AC power to utilization equipment. The power module has an input controlled rectifier adapted to generate a DC voltage on an internal DC bus, and a power inverter coupl
Koosmann Glenn A.
Wade Joseph R.
Zahrte, Sr. Donald K.
Leydig , Voit & Mayer, Ltd.
Polk Sharon A.
Powerware Corporation
Sircus Brian
LandOfFree
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