United Technologies Automotive Inc.

United Technologies Corporation

Bruce R Wrenbeck

David L Juzswik

Jeffrey T Kelley

David A Parker

Pedro A Perez

A pulse width modulation circuit includes a transistor pass element alternately switched on and off by an oscillator and connecting a power source to a load. Current through the transistor pass element is compared to a reference signal by a comparator. If the current through the transistor pass element exceeds the reference signal, the comparator generates a fault signal, and the transistor pass element is switched off for the remainder of the cycle. After a predetermined number of faults, the transistor pass element is switched off for a plurality of cycles. The pulse width modulation circuit prevents damage to the transistor pass element caused by the low initial resistance of the load and supplies sufficient current to slowly heat the load to steady state operation. This also allows for downsizing of the pass element for steady state conditions thereby saving product cost.

Pulse width modulation and protection circuit

An improved current sensing circuit is provided in, or for use with, a power delivery circuit having a current controlling device of the type which includes auxiliary current sensing terminals. The current sensing circuit is particularly useful in conjunction with a respective current sensing power MOSFET located in the 'high side' of a switching circuit, such as an H-bridge switch for a bidirectional load. The current sensing circuit has two branches connected to the current sensing MOSFET and to a reference potential and constructed to provide an output voltage signal representative of the main current through the current sensing MOSFET. The first branch includes at least two transistors and a resistor serially connected between a current sense terminal of the MOSFET and a reference potential. The second branch also includes at least two serially connected transistors connected between a terminal of the MOSFET and the reference potential. The transistors are cross-connected between branches and provide an inverted current mirror and a current mirror. Fifth and sixth transistors may also be included as part of the current sensing circuit.

Device in a power delivery circuit

A power window system employs a computer based control that receives signals from a window position sensor. As the window moves, the position sensor produces periodic signals as an output. The computer cyclically looks for a change in the frequency of the signals as an indication that the window is obstructed and decelerating. Based on the instantaneous deceleration, the computer recalls a stored value for motor force. The recalled forces are accumulated in synchronism with the position sensor output during the deceleration, manifesting the force applied to the obstruction as the window presses on it. The window is reversed when the accumulated force exceeds a stored value. The uppermost window position is a stored value for the position sensor output obtained when the window is closed for the first time. Each time the window is closed thereafter, an offset is added to that value, the sum defining the point at which the window engages the window seal. The offset is the change in the position sensor output signal as the window is slowed by the seal until the motor stops when a stored value of force is applied to the seal.

Adaptive window lift control with pinch force based on object rigidity

Power dissipation across the coils in a relay control system is controlled by regulating the voltage across all the coils with a regulator that senses the voltage and varies the conduction time of the switch carrying the total coil current. The regulator includes timing and logic elements that sense if the switch is operating correctly. Another switch is operated by the logic elements to shunt the first switch when the first switch is not operating correctly. This ensures that normal coil function is available in the event of a first switch failure.

Power control in relay coils

Current sensing circuit for use with a current controlling device in a

A fail-operational control system utilizes low current switches for controlling vehicle high current loads. In a normal mode of operation, the control system utilizes a CPU to control the loads in response to input signals provided to the CPU by the low current switches. In a fail-operational mode of operation, during failure or removal of the CPU, certain high current loads are switched directly by corresponding low current switches to provide continued operation of the certain high current loads.

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Dearborn, MI, United States of America

Bruce R Wrenbeck