Uninterruptible power supplies having cooled components

Abstract

Methods and apparatus for uninterruptible power supply (UPS) systems are provided. The UPS systems are configured to provide the advantages of an in-line device, and operate in a quasi-standby mode. The UPS includes a rectifier unit and inverter arranged to nominally deliver a portion (e.g. up to about 20%) of the primary AC power supply to a critical load through an output transformer. The rectifier unit preferably includes internal energy storage capabilities, such as a capacitor and inductor. The remaining portion of the AC power supply is nominally supplied directly to the critical load and is controlled by a transfer switch and the output transformer. When a fault is detected in the main AC power supply, the transfer switch switches to a faulted position and power is supplied from the rectifier inductor and capacitor or from a battery to the load through the inverter. Electronic switches such as MOSFETs are provided in the system to control the supply of power from the battery (or other energy storage device) to the inverter and to control the charging and discharging of the battery. The inverter and MOSFETs are designed to withstand transient overpower and overcurrent operation without deleterious consequences by liquid cooling the inverter or the inverter and the MOSFETs under predetermined conditions to temperatures between about 60 K and 270 K.