Abstract: A battery monitoring apparatus that obtains a current measurement for a current in a conductive element. The battery monitoring apparatus includes conductive lines configured to couple to a conductive element having an electrical current, a filter coupled to the conductive lines and configured to filter noise from a signal derived from a voltage difference between the conductive lines, an analog-to-digital converter that converts the signal filtered by the filter and outputs a digital signal, and a controller that receives the digital signal from the analog-to-digital converter.

Abstract: The battery charger is modular and reconfigurable. It includes charging modular power stages that are configured to receive an alternating current (AC) input and provide a direct current (DC) output for charging a battery. These modular power stages include an inverter coupled to a rectifier circuit that outputs a battery charging current. The modular power stages can also each include a current mode controller coupled to the output of the rectifier circuit and configured to provide a current control signal for the modular power stage, a voltage mode controller coupled to the output of the rectifier circuit and configured to provide a voltage control signal for the modular power stage, and a droop sharing control and configured to ensure current sharing between a plurality of modular power stages under constant voltage operation. A system controller is configured to interface with the modular power stages.

Abstract: The battery charger is modular and reconfigurable. It includes charging modular power stages that are configured to receive an alternating current (AC) input and provide a direct current (DC) output for charging a battery. These modular power stages include an inverter coupled to a rectifier circuit that outputs a battery charging current. The modular power stages can also each include a current mode controller coupled to the output of the rectifier circuit and configured to provide a current control signal for the modular power stage, a voltage mode controller coupled to the output of the rectifier circuit and configured to provide a voltage control signal for the modular power stage, and a droop sharing control and configured to ensure current sharing between a plurality of modular power stages under constant voltage operation. A system controller is configured to interface with the modular power stages.

Abstract: A simple and flexible battery charger for charging high voltage battery strings includes a DC-to-AC converter that drives the primary of a transformer having multiple secondaries. Each secondary winding has a corresponding output stage formed of a rectification circuit, output inductor, and output capacitor. The output terminals of the output stages are connectable either in parallel or series. In either configuration, inductor current and capacitor voltage automatically balance among the output stage circuits. A controller normally regulates output terminal voltage by operating in voltage mode, but limits current by operating in a current mode when the average of inductor currents exceeds a specified limit. Reconfiguration from parallel to series, or vice versa, is obtained physical reconnection of the output stage terminals and adjustment of a single voltage feedback scaling factor.

Abstract: Activity based battery monitoring is carried out with a minimal requirement for data memory capacity by determining events defined between changes in the battery states of charge, discharge and open circuit. Battery parameters are sampled at high sampling rates but only a relatively small number of memory data fields are stored in a non-volatile memory and updated after each event. In operation, battery current is monitored to determine a change in battery state. At the end of an event, at which time the battery changes state, a limited number of data fields, which nonetheless accurately categorizes the event, can be stored to the non-volatile memory, including the event type, the event start time, total ampere hours during the event, and various transient conditions during the event such as maximum voltage, current and temperature and minimum voltage, their times of occurrence, and any alarms that are triggered during the event.

Abstract: A simple and flexible battery charger for charging high voltage battery strings includes a DC-to-AC converter that drives the primary of a transformer having multiple secondaries. Each secondary winding has a corresponding output stage formed of a rectification circuit, output inductor, and output capacitor. The output terminals of the output stages are connectable either in parallel or series. In either configuration, inductor current and capacitor voltage automatically balance among the output stage circuits. A controller normally regulates output terminal voltage by operating in voltage mode, but limits current by operating in a current mode when the average of inductor currents exceeds a specified limit. Reconfiguration from parallel to series, or vice versa, is obtained physical reconnection of the output stage terminals and adjustment of a single voltage feedback scaling factor.

Abstract: Battery charge equalization is carried out utilizing modules connectable in staggered relation between pairs of batteries in a series connected string of batteries. Each module is standardized and has the same construction as the other modules. The modules may be constructed to provide unidirectional charge distribution down the string from a more highly charged battery to a lower charged battery and from a more highly charged last battery in the string back to a less highly charged first battery in the string, or may be constructed to provide bi-directional charge redistribution up or down the string of batteries. The charge equalizer modules are forward-based and reduce the charging current as the voltages on the two batteries to which the module is connected equalize.

Abstract: A coaxial winding transformer is cooled by having heat transfer members connected to an outer conductor of the transformer to receive heat therefrom. The heat transfer members form a heat transfer conducting path from the outer conductor of the transformer to a surface of a heat sink. The heat sink may have fins to maximize transfer of the heat from the heat sink to the ambient air. The outer conductor can include a metal strap member in contact with the surface of extending sections of tubular straight leg sections to electrically connect the tubular sections and transfer heat therefrom. Heat is then transferred from the strap of the outer conductor through the heat transfer members to an available surface of the heat sink.

Abstract: A DC-to-DC converter for high current outputs is provided having an input side circuit, including two converter bridges, and an output side circuit, including two diode rectifier configurations. The input and output circuits are preferably connected by a co-axial winding transformer (CWT). Switches in the input side bridges alternately connect and disconnect a DC input voltage to and from the primary side of the transformer. The waveform appearing on the secondary of the transformer is rectified by the output side rectifier configurations. A switched-in bias voltage in each input side converter bridge provides for reversal of the current in the bridge after the bridge is switched off, and before the other bridge is switched on. This current reversal allows a current in one of the rectifier configurations of the output side circuit to be brought softly to zero before being reversed biased by the switching on of the other converter bridge. Thus, a reverse recovery spike in the output circuit is avoided.

Abstract: A simple, low-cost technique for charge equalization of a series connected string of battery cells is provided. The secondary windings of a transformer having a single primary winding and multiple secondary windings are connected across each battery cell to be equalized. A single power converter applies a charging signal to the primary of the transformer, inducing a charging current in each secondary which is inversely related to the charge on the battery cells to be equalized. The transformer is preferably implemented as a coaxial winding transformer having low secondary-to-secondary winding coupling. The power converter is preferably implemented as a forward converter supplied with DC power from an adjustable DC power source. A source voltage provided by the DC source may preferably be adjusted during the course of charge equalization to preferentially direct charge to weaker cells.