A circuit for detecting a status of a ground connection in an electric motor includes a rectifier, a converter, a voltage conditioning circuit, a leakage circuit, and a comparator. The rectifier couples to an AC line within the motor and generates a first DC voltage. The converter steps-down the first DC voltage to a second DC voltage. The voltage conditioning circuit couples to the converter, leakage circuit, and comparator, and generates a reference DC voltage signal and a leakage voltage from the second DC voltage. The leakage circuit includes an impedance coupled to ground, and applies the leakage voltage to the impedance and generates a measurement signal representing a leakage current through the impedance to ground. The comparator couples to the leakage circuit and generates a logic signal, indicating a status of the ground connection, based on a voltage difference between the reference DC voltage signal and the measurement signal.

A hybrid air-gap/solid-state device protection device (PD) for use in an electrical power distribution system includes an air-gap disconnect unit connected in series with a solid-state device, a sense and drive circuit, and a microcontroller. Upon the sense and drive circuit detecting an impending fault or exceedingly high and unacceptable overvoltage condition in the PD's load circuit, the sense and drive circuit generates a gating signal that quickly switches the solid-state device OFF. Meanwhile, the microcontroller generates a disconnect pulse for the air-gap disconnect unit, which responds by forming an air gap in the load circuit. Together, the switched-OFF solid-state device and air gap protect the load and associated load circuit from being damaged. They also serve to electrically and physically isolate the source of the fault or overload condition from the remainder of the electrical power distribution system.

A combination motor control device includes a power circuit (180) structured to sense voltage and/or current flowing through the combination motor control device, a semiconductor switching and interruption circuit (170) including a number of solid state transistors and being operable to turn on to allow power to flow through the combination motor control device and to turn off to stop allowing power to flow through the combination motor control device, and a control circuit (190) structured detect faults in power flowing through the combination motor control device based on the sensed voltage and/or current, to control the semiconductor switching and interruption circuit (170) to provide a motor starter and/or motor controller functionality, and to control the semiconductor switching and interruption circuit (170) to turn off in response to detecting a fault in power flowing through the combination motor control device.

A power conversion device according to an embodiment of the present invention includes a first inverter to which one end of each of n phase windings (n is an integer of three or more) included in an electric motor is coupled, a second inverter to which the other end of each phase winding is coupled, and a switch circuit having at least one of: a first switch element that switches between connection and disconnection of the first inverter and ground, and a second switch element that switches between connection and disconnection of the second inverter and ground.

A thermal management system is provided. The system includes a temperature sensor, a fan, an electronic circuit breaker (ECB) coupled to the fan to provide electric power to the fan. The system includes a controller coupled to the temperature sensor and the ECB, to direct the ECB to turn off the electric power to the fan responsive to detecting a temperature, from the temperature sensor less than a temperature threshold based on a temperature rating of the fan.

An electronic control device for use in a motor vehicle includes an electronic housing for accommodating an electronics system that includes a circuit board, and a resistance sensor for detecting water that has penetrated into the electronic housing. The resistance sensor includes at least two sensor electrodes, each of which is present, at least in one section, in an uninsulated state with respect to the interior of the electronic housing, and a control unit that is configured to detect and evaluate a measured resistance value between the two sensor electrodes. The control unit is further configured to output a trigger signal when the detected measured resistance value or its deviation from a normal value meets a trigger criterion that is characteristic of a contact closure between the two sensor electrodes that is caused by the presence of water in the electronic housing.

A method and controller to automatically determine a grounding condition of a motor drive, in which an inverter is operated at a predetermined frequency while a load resistor is connected between a single phase of a motor drive inverter output and a reference node, a leakage flux linkage value is computed according to a neutral-ground voltage of the motor drive, and a processor determines whether the motor drive is solid grounded, high-resistance grounded, or floating according to the leakage flux linkage value. In certain examples, the processor automatically turns the inverter off while the load resistor is connected between the single phase of the inverter output and the reference node, and automatically determines whether the motor drive is delta corner grounded according to the neutral-ground voltage.

Method for measuring torque in rotating-equipment, turbo-machinery, pumps, turbines, and compressors. The measured torque can be used as an input to control torque, power, or energy efficiency. The method can also measure force (or torque) in traversing-machinery or vehicles such as automobiles, ships, aircraft, bicycles and motorcycles. The method takes real-time rotating (or linear) speed measurements, applies the discrete form of equations of motion, captures the natural decay curve(s) of the machine to estimate the torque (or force) associated with the losses of the power sink, and then solves for the driving torque of the power source. The method relates to monitoring and control systems used to safely and efficiently operate rotating-equipment and traversing-machinery. The method can be used to determine a health index of a machine to make predictive and corrective maintenance, reliability, performance, safety, and efficiency-related decisions. It is accurate, robust, lightweight, space-saving, and low cost.

A central vacuum cleaning system comprising a vacuum source including: a motor within a motor housing, a receptacle extending from the motor housing for receiving dirt, and a motor control circuit connected to the motor; a handle to be held by an operator, a flexible hose for releasably connecting the handle to a conduit system that is connected to the vacuum source, such that when the motor is activated during use of the system, dirt is drawn by a vacuum created by the vacuum source through the attachment, handle, hose, and conduits, and into the receptacle; a user input interface at an input location on the handle for controlling an operation of the motor through the motor control circuit; and a communications system to transfer control signals from the user input interface to the motor control circuit wherein the communications system comprises an RF wireless transceiver in the handle, and an RF wireless transceiver at the motor control circuit.