Abstract: A field current control circuit for an alternating current generator includes a first voltage source and a time lag reduction circuit, which further includes a generator field that is in selective electrical communication with an energy storage component that is in electrical communication with a time lag reduction voltage source. The time lag reduction circuit may include an electronic controller and be a part of an electric drive machine that receives an operator acceleration command and thereby controls the electrical communication between the energy storage component and the generator field of the time lag reduction circuit. When the energy storage component and generator field are in electrical communication, the current passing through the generator field increases from a starting current to a target current with a reduced time lag compared to predecessor generators.

Abstract: A field current control circuit for an alternating current generator includes a first voltage source and a time lag reduction circuit, which further includes a generator field that is in selective electrical communication with an energy storage component that is in electrical communication with a time lag reduction voltage source. The time lag reduction circuit may include an electronic controller and be a part of an electric drive machine that receives an operator acceleration command and thereby controls the electrical communication between the energy storage component and the generator field of the time lag reduction circuit. When the energy storage component and generator field are in electrical communication, the current passing through the generator field increases from a starting current to a target current with a reduced time lag compared to predecessor generators.

Abstract: Systems and methods are disclosed for detecting a faulty ground strap connection for a machine hosting a high voltage system. In one embodiment, a fault detection and compensation system includes a ground strap, a DC power supply electrically referenced to a machine frame, a leakage detection switch connected to the machine frame, a current source controlled by the leakage detection switch, and a voltage measuring device that measures an offset voltage. The fault detection and compensation system further includes a leakage detection and compensation controller that compensates for the unbalanced fault condition by controlling the leakage detection switch and the current source, and determines whether the ground strap is properly connected to the machine frame.

Abstract: Systems and methods are disclosed for compensating electrical leakage and detecting balanced electrical leakage for a machine hosting an HV system. In one embodiment, a fault detection and compensation system includes a DC power supply electrically referenced to a machine frame, a leakage correction switch connected to the machine frame, a current source controlled by the leakage correction switch, and a voltage measuring device that measures an offset voltage reflecting whether the HV system is in an unbalanced fault condition. The fault detection and compensation system further includes a leakage detection and compensation controller that compensates for the unbalanced fault condition by controlling the leakage correction switch and the current source.

Abstract: Systems and methods are disclosed for detecting a faulty ground strap connection for a machine hosting a high voltage system. In one embodiment, a fault detection and compensation system includes a ground strap, a DC power supply electrically referenced to a machine frame, a leakage detection switch connected to the machine frame, a current source controlled by the leakage detection switch, and a voltage measuring device that measures an offset voltage. The fault detection and compensation system further includes a leakage detection and compensation controller that compensates for the unbalanced fault condition by controlling the leakage detection switch and the current source, and determines whether the ground strap is properly connected to the machine frame.

Abstract: An apparatus and method for transferring a signal from a first bus circuit to a second bus circuit. The apparatus and method includes a first constant current circuit connected to the first bus circuit, a first capacitor connected between the first bus circuit and the first constant current circuit, a second constant current circuit connected to the second bus circuit, a second capacitor connected between the second bus circuit and the second constant current circuit, and an opto-coupler connected between the first and second constant current circuits and providing signal transfer control from the first capacitor to the second capacitor.

Abstract: Systems and methods are disclosed for compensating electrical leakage and detecting balanced electrical leakage for a machine hosting an HV system. In one embodiment, a fault detection and compensation system includes a DC power supply electrically referenced to a machine frame, a leakage correction switch connected to the machine frame, a current source controlled by the leakage correction switch, and a voltage measuring device that measures an offset voltage reflecting whether the HV system is in an unbalanced fault condition. The fault detection and compensation system further includes a leakage detection and compensation controller that compensates for the unbalanced fault condition by controlling the leakage correction switch and the current source.

Abstract: An apparatus and method for transferring a signal from a first bus circuit to a second bus circuit. The apparatus and method includes a first constant current circuit connected to the first bus circuit, a first capacitor connected between the first bus circuit and the first constant current circuit, a second constant current circuit connected to the second bus circuit, a second capacitor connected between the second bus circuit and the second constant current circuit, and an opto-coupler connected between the first and second constant current circuits and providing signal transfer control from the first capacitor to the second capacitor.

Abstract: A method is provided for detecting electrical leakage between a power supply and a frame of a vehicle or machine. The disclosed method includes coupling a first capacitor between a frame and a first terminal of a power supply for a predetermined period of time. The current flowing between the frame and the first capacitor is limited to a predetermined current limit. It is determined whether the voltage across the first capacitor exceeds a threshold voltage. A first output signal is provided when the voltage across the capacitor exceeds the threshold voltage.

Abstract: A method is provided for detecting electrical leakage between a power supply and a frame of a vehicle or machine. The disclosed method includes coupling a first capacitor between a frame and a first terminal of a power supply for a predetermined period of time. The current flowing between the frame and the first capacitor is limited to a predetermined current limit. It is determined whether the voltage across the first capacitor exceeds a threshold voltage. A first output signal is provided when the voltage across the capacitor exceeds the threshold voltage.

Abstract: A resettable circuit breaker includes a current monitoring and interrupting circuit including an electrically conductive line carrying a current. A sensor outputs a voltage level indicative of the magnitude of the current. A comparator compares the voltage level to a reference potential and generates a circuit indicator signal. A logic-based current interrupter controls the current in the line in response to the circuit indicator signal.

Abstract: An apparatus and method for measuring a characteristic, such as speed, of a machine. A variable reluctance sensor (VRS) is coupled to a resistive element, which filters a portion of a basic output signal generated by the VRS having a frequency above a prescribed threshold level, thus removing high-frequency noise from the basic output signal. An amplifier amplifies the filtered output signal. The filtered, amplified output signal has an increased signal-to-noise ratio such that the machine characteristic, i.e. speed, can be more accurately measured during a slow speed operation. A controller generates a control signal received by a switching device to decouple the resistive element when machine speed exceeds a prescribed threshold level. Then, the basic output signal is used to measure the characteristic of the machine during normal machine operation.

Abstract: An apparatus and method for measuring a characteristic of a machine. A variable reluctance sensor (VRS) is coupled to the machine. A first switching device and capacitor, coupled in parallel with the VRS, boosts a variable amplitude of a basic output signal generated by the VRS to increase the signal-to-noise ratio. A control input of the first switching device receives signals, and a modified output signal is generated by the first switching device, having a variable amplitude that is substantially higher than the variable amplitude of the VRS. The modified output signal has an increased signal-to-noise ratio such that machine speed can be more accurately measured during a start-up phase.

Abstract: A power circuit includes a first electrically-energizable contactor configured to receive a first power input of 110-120 volts of alternating current (VAC), and a second electrically-energizable contactor configured to receive a second power input of 220-240 VAC. The first and second contactors are arranged such that when one of the first and second contactors is energized by the corresponding power input, the energized one of the first and second contactors prevents the other one of the first and second contactors from being energized.

Abstract: An apparatus and method for measuring a characteristic, such as speed, of a machine. A variable reluctance sensor (VRS) is coupled to a resistive element, which filters a portion of a basic output signal generated by the VRS having a frequency above a prescribed threshold level, thus removing high-frequency noise from the basic output signal. An amplifier amplifies the filtered output signal. The filtered, amplified output signal has an increased signal-to-noise ratio such that the machine characteristic, i.e. speed, can be more accurately measured during a slow speed operation. A controller generates a control signal received by a switching device to decouple the resistive element when machine speed exceeds a prescribed threshold level. Then, the basic output signal is used to measure the characteristic of the machine during normal machine operation.

Abstract: An apparatus and method for measuring a characteristic of a machine. A variable reluctance sensor (VRS) is coupled to the machine. A first switching device and capacitor, coupled in parallel with the VRS, boosts a variable amplitude of a basic output signal generated by the VRS to increase the signal-to-noise ratio. A control input of the first switching device receives signals, and a modified output signal is generated by the first switching device, having a variable amplitude that is substantially higher than the variable amplitude of the VRS. The modified output signal has an increased signal-to-noise ratio such that machine speed can be more accurately measured during a start-up phase.

Abstract: An apparatus for controlling a load lifting implement of a work vehicle in response to the condition of a motor brush is provided. The vehicle has a frame and the load lifting implement is connected to the frame and elevationally moveable relative to the frame between first and second directions. A brush wear indicator senses the wear of the motor brush and produces a warning signal in response to a predetermined amount of wear of the motor brush. A control system receives the warning signal and responsively controllably inhibits the elevational movement of the load lifting implement in at least one of the first and second directions.

Abstract: An apparatus is provided for precharging a filter capacitor to prevent damage to a set of contacts resulting from arcing across the contacts. Included is a coil, a set of contacts, and a battery, such that the contacts and filter capacitor are connected in series and the series connected combination is connected in parallel across the battery. Also included is a switch, and a microprocessor for producing a triggering signal responsive to the closure of the switch. A driving circuit receives the triggering signal and responsively produces a charging signal. A charging circuit receives the charging signal and responsively charges the filter capacitor. Thereafter, the microprocessor produces an energizing signal causing the coil to become energized and the contacts to responsively close. By precharging the filter capacitor before the closure of the contacts, the voltage potential across the contacts is reduced. Therefore, no damage occurs due to arcing across the contacts.

Abstract: An apparatus for dampening current in a coil has a switchable member which controls the current level in the coil and a flyback circuit that allows current in the coil to slowly dissipate when the switchable member changes from an "ON" to an "OFF" state. The flyback circuit has a high resistance when the switchable member changes from the "ON" to the "OFF" state so that the coil current is dampened as quickly as possible without creating a destructive voltage and low resistance when the switchable member is in the "ON" state to conserve energy. A signaling device creates a voltage signal as a function of current passing through the flyback circuit and a receiving device varies the resistance of the flyback circuit in response to the voltage signal. The apparatus is particularly suited for use in a motor control circuit.

Abstract: A thyristor pulse control circuit has a main thyristor, a commutation circuit including a commutating capacitor, and a bypass contactor connected across the main thyristor, and is provided with apparatus for applying a gating signal to the main thyristor immediately before the contacts of the bypass contactor close and also immediately before the contacts of the bypass contactor close to prevent arcing at the contacts. The application of the gating signal is inhibited if a comparison of the voltage across the commutating capacitor with the load current flowing immediately before the bypass contactor closes indicates that the load current is too great to be safely commutated by the commutating capacitor at the measured voltage.