A chiller assembly is provided. The chiller assembly includes a compressor (102), a condenser (106), an expansion device and an evaporator (108) connected in a closed refrigerant circuit. The chiller assembly further includes a motor (104) connected to the compressor to power the compressor, and a variable speed drive (110) connected to the motor to power the motor. The variable speed drive is operable to provide a variable voltage to the motor and a variable frequency to power the motor. The variable speed drive includes multiple sensors and an input current estimator that determines an estimated RMS input current based on sensor data received from the sensors. The chiller assembly further includes a control panel to control operation of the variable speed drive.

Selectable current limiting for a power tool. One embodiment provides a method for selectable current limiting for a power tool including determining, using a current sensor, an average current and determining whether the average current exceeds a predetermined current threshold. The method also includes determining a deviation of the average current from the predetermined current threshold and reducing a PWM duty ratio proportional to the deviation of the average current from the predetermined current threshold. The PWM duty ratio corresponds to a PWM signal provided to an inverter bridge.

Provided is a semiconductor device including, a plurality of PN junction diodes each having a negative temperature characteristic and connected to each other in series; a plurality of resistance elements connected respectively to the PN junction diodes in parallel and connected to each other in series; and a Schottky barrier diode having a positive temperature characteristic and connected to the PN junction diodes in parallel.

An overcurrent protection system for a mobile irrigation system. The overcurrent protection system includes a number of control panels each including a controller configured to generate a motor control signal for activating one of the motors of the mobile irrigation system, transmit the motor control signal to the motor, determine a current magnitude of electrical current passing through a motor power branch line electrically connected to the motor, and restrict current to the motor if the current magnitude is above a current magnitude threshold. The controller is further configured to set the current magnitude threshold according to one of a plurality of motor operation stages. The current magnitude threshold can also be set remotely.

A motor driven appliance comprises a battery, a motor, at least one switch, a control unit, an abnormality detection unit, a determination unit, and a processing unit. The at least one switch comprises an operation switch. The control unit controls driving of the motor by controlling power supply from the battery to the motor when the operation switch is turned on. The abnormality detection unit detects abnormality of the appliance. The determination unit determines whether the detected abnormality is a first type abnormality that can be cleared when the operation switch is switched from on to off, or is a second type abnormality that cannot be cleared even if the operation switch is merely switched from on to off. The processing unit is configured to perform a specific process when it is determined that the detected abnormality is the second type abnormality.

The present invention relates to a method for operating a power generating assembly in the event of a fault, wherein the power generating assembly comprises a PMG comprising at least first and second sets of stator windings, wherein each set of stator windings is connected to a power converter via a controllable circuit breaker, the method comprising the steps of detecting a fault associated with the first set of stator windings, and lowering, such as interrupting, the current in the second set of stator windings, and, after a predetermined delay, lowering, such as interrupting, the current in the first set of stator windings. The present invention also relates to a power generating assembly being capable of handling such faults, and a wind turbine generator comprising such a power generating assembly.

An over-current protection circuit for a motor capable of selecting one of a plurality of connection states has a plurality of decision circuits, a combining circuit, and a nullifying circuit. The combining circuit combines results of the comparisons in the plurality of decision circuits. The nullifying circuit nullifies part of the comparisons in the plurality of decision circuits. The number of outputs of the over-current protection circuit is one, so that for controlling the driving and stopping of the inverter needs just one terminal is required for receiving the output of the combining circuit. Moreover, because the over-current protection circuit is formed of hardware, the protection can be performed at a high speed.

An overload control device for use with a floor machine having an electric motor is disclosed. The overload control device can include a power input and a power output connectable to the electric motor. The device can include a load detector, a current sensor operative to sense a current value supplied to the motor via the power output, and a cutoff relay interconnecting the power input and the power output. The cutoff relay being operative to supply power from the power input to the power output when activated, and interrupt power when deactivated. A controller receives a load present indication from the load detector and activates the cutoff relay if a load is present. The controller receives a current value from the current sensor, determines if the current value is greater than a threshold value, and deactivates the cutoff relay when the current value is greater than the threshold value.

In some examples, a rotary electric machine includes a stator having a plurality of stator coils arranged in a circular pattern around a central opening configured for receiving a rotor. The rotary electric machine further includes a respective dedicated inverter circuit associated with each respective stator coil. For instance, each respective inverter circuit may be configured to convert direct current power to alternating current power to provide to the respective stator coil.

The internal temperate of a transistor is determined by detecting a voltage though a terminal of an integrated circuit that is also used by an overcurrent detection circuit of the integrated circuit for detecting an overcurrent condition of the system. The overcurrent detection circuit is coupled to a current electrode of the transistor through the terminal of the integrated circuit. A determination of internal temperature is based on a voltage measurement taken from the terminal during an on phase of the transistor. The voltage measurement is converted to a digital value and is used to determine an internal temperature of the transistor.