An electric motor system is described. The electric motor system includes a drive circuit configured to supply variable frequency current and a contactor configured to supply line frequency current, wherein the drive circuit includes a three-phase inverter and an H-bridge including two phases of the inverter. The electric motor system also includes an electric motor and a controller. The controller is configured to control the inverter to supply variable frequency current to the electric motor over a first duration and determine to control the drive circuit to transition from supplying variable frequency current to supplying line frequency current. The controller is also configured to determine a polarity of a sensed alternating current (AC) voltage, disable at least two switches of the H-bridge, and control the contactor to close, thereby preventing the contactor and the inverter from energizing the electric motor at the same time once the contactor is closed.

The invention relates to a control apparatus for a refrigerator compressor having at least one two-phase AC asynchronous motor (K1, K2), having mains connection means (10) for connection to a preferably public voltage supply network which nominally provides a mains AC voltage of between 85 V and 264 V, in particular between 100 V and 230 V, first voltage converter means (14) which are connected downstream of the mains connection means and are intended to generate an intermediate voltage, in particular an intermediate DC voltage, from the mains AC voltage, second voltage converter means (16-1, 16-2) which are connected downstream of the first voltage converter means and are intended to generate an output signal which is independent of a level and a mains frequency of the mains AC voltage, in particular has a constant voltage and/or frequency in periods, and is intended to control the refrigerator compressor with an AC voltage of a plurality of differently predefinable voltage levels, wherein the mains connection means are assigned voltage detector means (12) for capturing the mains AC voltage, the detector output signal from which can be evaluated by the second voltage converter means or control means (24) assigned to the latter for the purpose of generating a mains-voltage-dependent maximum value for a current of the output signal.

The invention relates to a control apparatus for a refrigerator compressor having at least one two-phase AC asynchronous motor (K1, K2), having mains connection means (10) for connection to a preferably public voltage supply network which nominally provides a mains AC voltage of between 85 V and 264 V, in particular between 100 V and 230 V, first voltage converter means (14) which are connected downstream of the mains connection means and are intended to generate an intermediate voltage, in particular an intermediate DC voltage, from the mains AC voltage, second voltage converter means (16-1, 16-2) which are connected downstream of the first voltage converter means and are intended to generate an output signal which is independent of a level and a mains frequency of the mains AC voltage, in particular has a constant voltage and/or frequency in periods, and is intended to control the refrigerator compressor with an AC voltage of a plurality of differently predefinable voltage levels, wherein the mains connection means are assigned voltage detector means (12) for capturing the mains AC voltage, the detector output signal from which can be evaluated by the second voltage converter means or control means (24) assigned to the latter for the purpose of generating a mains-voltage-dependent maximum value for a current of the output signal.

An electric motor system is described. The electric motor system includes a drive circuit configured to supply variable frequency current and a contactor configured to supply line frequency current, wherein the drive circuit includes a three-phase inverter and an H-bridge including two phases of the inverter. The electric motor system also includes an electric motor and a controller. The controller is configured to control the inverter to supply variable frequency current to the electric motor over a first duration and determine to control the drive circuit to transition from supplying variable frequency current to supplying line frequency current. The controller is also configured to determine a polarity of a sensed alternating current (AC) voltage, disable at least two switches of the H-bridge, and control the contactor to close, thereby preventing the contactor and the inverter from energizing the electric motor at the same time once the contactor is closed.

A motor controller for an electric motor is provided. The motor controller includes an inverter configured to supply current to stator windings of the electric motor. The motor controller further includes a plurality of sensors configured to generate a sensor signal in response to detecting a parameter. The sensor signal represents a measured parameter. The motor controller further includes a processor coupled in communication with the inverter and with the plurality of sensors. The processor is configured to, in a first mode, transmit a control signal to the inverter to operate the electric motor at a first frequency. The processor is further configured to receive the sensor signal from the plurality of sensors. The processor is further configured to determine a first fault condition is present at the electric motor based on the measured parameter represented by the sensor signal.

A hard start capacitor replacement unit has a plurality of capacitors in a container sized to fit in existing hard start capacitor space. The capacitors are 4 metallized film capacitors wound in a single cylindrical capacitive element. The container has a common terminal and capacitors value terminals for the plurality of capacitors, which may be connected singly or in combination to provide a selected capacitance. An electronic or other relay connects the selected capacitance in parallel with a motor run capacitor. The hard start capacitor replacement unit is thereby adapted to replace a wide variety of hard start capacitors.

A hard start capacitor replacement unit has a plurality of capacitors in a container sized to fit in existing hard start capacitor space. The capacitors are 4 metallized film capacitors wound in a single cylindrical capacitive element. The container has a common terminal and capacitors value terminals for the plurality of capacitors, which may be connected singly or in combination to provide a selected capacitance. An electronic or other relay connects the selected capacitance in parallel with a motor run capacitor. The hard start capacitor replacement unit is thereby adapted to replace a wide variety of hard start capacitors.

A motor controller includes a motor control part controlling a motor having a three-phase coil by a control signal, an inverter applying a drive voltage supplied from a power source to the three-phase coil based on an output signal from the motor control part, a drive voltage line supplying the drive voltage to the inverter, a common line electrically connected with a neutral point of the three-phase coil, an inductor electrically connected in series with the drive voltage line, a first capacitor between a portion between the inverter and the inductor in the drive voltage line and a ground, a second capacitor between a portion on an input side with respect to the first capacitor in the drive voltage line and the ground, and a third capacitor between the second capacitor and the ground. The common line is electrically connected between the second capacitor and the third capacitor.

A system and method for detecting failures in a single-phase AC motor is disclosed. After a startup sequence, the motor is unpowered and a measurement is taken across terminals in the motor to detect a signal from residual magnetism in the iron core of the rotor. If the rotor was successfully started, the signal will be above a predetermined threshold. The signal may be measured across either a main stator winding or a start stator winding. Where the signal does not exceed the predetermined threshold, the startup sequence may be re-initiated and/or a failure message may be sent to an operator.

A highly energy efficient circuit for an AC ceiling fan motor in high speed gear, which comprises a speed regulator and a ceiling fan motor whose output torque at full voltage exceeds a required torque at rated load. Two ends of a winding of the ceiling fan motor are connected to a voltage-regulating capacitor bank and a zero line, respectively. The voltage-regulating capacitor bank comprises a first capacitor bank for enabling low speed operation of the ceiling fan motor by stepping down by a third capacitor, a second capacitor bank for enabling medium speed operation of the ceiling fan motor by stepping down by a second capacitor and the third capacitor in parallel, and a third capacitor bank for enabling high speed operation of the ceiling fan motor by stepping down by a first capacitor, the second capacitor and the third capacitor in parallel.