Abstract: A protection circuit for protecting a load, such as a winch motor, from an overcurrent as well as from a circuit fault including welded primary switch contacts and a failure of its MOS/FET component. A power MOS/FET is used as a current mirror for sensing load current. A secondary switch is series connected to control the primary switch. A control circuit including a programmable data processor controls the MOS/FET and the secondary switch and senses the current through the MOS/FET's secondary source terminal and senses the voltage at its primary source terminal. The programmable data processor determines whether an overcurrent exists by comparing the sensed power circuit current to a stored overcurrent value and also senses whether the contacts of the primary switch are welded closed and whether the MOS/FET has been damaged. Additional conditions are sensed. Application of power to the load is prevented when such conditions are detected.

Abstract: A high current, solid state, electrical switch has switch terminal blocks on opposite sides of one or more arrays of parallel connected, solid state, high current, power switching devices mounted on a support. A first terminal of each switching device of each array is directly electrically and thermally bonded to a switch terminal block. A bus bar thermal bridge is directly electrically and thermally bonded to a second terminal of the switching device of each array. A thermally conductive heat sink panel is contoured in alignment with, and has a surface in spaced juxtaposition from, a surface of the bus bar thermal bridge and from surfaces of each of the switch terminal blocks. A thermally conductive, electrically insulating thermal interface material thermally contacts and extends between all said surfaces for conducting heat from the switch terminal blocks and from the thermal bridge to the heat sink panel.

Abstract: A battery protection circuit for connection to a vehicle's auxiliary battery, auxiliary battery load and chassis battery that is connected to the vehicle's alternator. A switching control circuit, including a digital processor, has a voltage sensing circuit connected to the alternator, a voltage sensing circuit connected to the auxiliary battery, a ground terminal for connection to the vehicle's common ground and outputs for controlling switches. An electrically controlled first switch is interconnected between the alternator and the auxiliary load. The first switch has a control input terminal connected to an output of the control circuit for being switched between a closed state and an open state. An electrically controlled second switch is interconnected between the auxiliary load and the auxiliary battery. The second switch has a control input terminal connected to an output of the control circuit for being switched between a closed state and an open state.

Abstract: An improvement for a smart, highside, high current, power switch module formed in an integrated circuit having at least one composite MOS/FET transistor switch connected to controlling and protection circuits. The power switch module has a load terminal (L), a battery input terminal (B), a control input terminal (C) and a diagnostic feedback terminal (M). The improvement provides overcurrent protection from a substantially instantaneous short circuit across an electrical load connected to the load terminal of the power switch module. The improvement is a capacitive circuit element connected between the battery input terminal (B) and the diagnostic feedback terminal (M).

Abstract: A circuit for controlling at least one circuit breaker switch that is series connected between a source of electrical power and an electrical load. The circuit includes a programmed controller having at least two inputs and at least one output. A current sensor senses the current between the source and the load and has an output connected to a controller input. Another controller input is connected to the control input of a load power switch. The control output of the controller is connected to the control input of the circuit breaker switch. The circuit is operated by sensing the current between the source of electrical power and the electrical load and monitoring the control input of the load power switch to detect whether the load power switch is commanded to be closed or open. If the load power switch is commanded to be open, the circuit breaker switch will be opened if the sensed current value is greater than a first maximum current value.

Abstract: A circuit and method for detecting an operating transition of a mechanical apparatus driven by a hydraulic prime mover comprising a hydraulic pump driven by an electric motor, the operating transition causing a change in the force applied by the mechanical apparatus on the prime mover. A motor current sensing circuit is connected in a motor power supply circuit to provide a motor current signal representing motor current. A bandpass filter receives the motor current signal and provides a filtered motor current signal consisting essentially of motor current signal components in the frequency range from a lower frequency boundary greater than zero Hz to an upper frequency boundary below substantially all the motor noise frequencies. A comparison circuit compares the filtered motor current signal to a first selected threshold level and outputs a signal representing the occurrence of the operating transition when the filtered motor current signal exceeds the selected threshold level.

Abstract: A circuit for controlling at least two power switches that are series connected between a source of electrical power and an electrical load, for energizing the load in response to a signal at a control input. The circuit includes a programmed controller having an input as the control input and a voltage sensor circuit connected to sense the voltage between the power switches and apply a voltage signal to a controller input. It may also have a sensor for sensing the current through the switches and applying a current signal to the controller. The controller inputs the voltage between the switches or the current through the switches to provide a sensed first value. It compares the sensed first value to an expected first value that exists if both switches are turned off. One of the two switches is turned on if the sensed first value is equal to the expected first value.