A rotor of line start permanent magnet synchronous motor is provided. The rotor includes bars of cage windings. The rotor includes an additional inductance coupled to the cage windings and located on a first end of the bars. The rotor includes an end ring located on a second end of the bars. The additional inductance provides a reactance to reduce a starting current during an asynchronous starting of the line start permanent magnet synchronous motor.

A motor case (10) has connectors (30) fixed at motor case mounting holes (11), and an inverter case (50) has connectors (60) radially movable at inverter case mounting holes (65). The inverter case (50) is mounted on the motor case (10) so that the connectors (30, 60) fit together. A surface seal (45) is disposed on a lower surface of a flange (42) at an outer periphery of a housing (35) of the motor-side connectors (30), and is compressed elastically against an upper surface of the motor case (10) at an outer periphery of the motor case mounting holes (11). A metal pressing member (20) is fixed on the motor case (10) and presses the flange (42). An axial seal (47) is fit on the outer periphery of the housing (35) and is compressed elastically between the outer periphery and an inner periphery of the second mounting hole (65).

A dual-drive electric motor control system configured to drive a first electric motor and a second electric motor is provided. The system includes a shared front-end motor drive circuit for converting AC input voltage from an AC voltage source to a DC-link voltage. A first control system has a first inverter coupled to the shared front-end motor drive circuit, and a first switch device configured to couple the AC voltage source directly to the first electric motor. The system further includes a second control system having a second inverter coupled to the shared front-end motor drive circuit, and a second switch device configured to couple the AC voltage source directly to the second electric motor.

A load control device may control power delivered from a power source, such as an alternating-current (AC) power source, to at least two electrical loads, such as a lighting load and a motor load. The load control device may include multiple load control circuit, such as a dimmer circuit and a motor drive circuit, for controlling the power delivered to the lighting load and the motor load, respectively. The load control device may adjust the rotational speed of the motor load in a manner so as to minimize acoustic noise generated by the load control device and reduce the amount of time required to adjust the rotational speed of the motor load. The load control device may remain powered when one of the electrical loads (e.g., the lighting load) has been removed (e.g., electrically disconnected or uninstalled) and/or has failed in an open state (has burnt out or blown out).

A load control device may control power delivered from a power source, such as an alternating-current (AC) power source, to at least two electrical loads, such as a lighting load and a motor load. The load control device may include multiple load control circuit, such as a dimmer circuit and a motor drive circuit, for controlling the power delivered to the lighting load and the motor load, respectively. The load control device may adjust the rotational speed of the motor load in a manner so as to minimize acoustic noise generated by the load control device and reduce the amount of time required to adjust the rotational speed of the motor load. The load control device may remain powered when one of the electrical loads (e.g., the lighting load) has been removed (e.g., electrically disconnected or uninstalled) and/or has failed in an open state (has burnt out or blown out).

A circuit includes phase windings, a power switch circuit comprising at least one power switch at a midpoint of the phase windings, a direct current (DC) supply circuit at the midpoint of the phase windings, and one or more non-collapsing DC power supply components to prevent the DC power supply from collapsing when the at least one power switch is on and conducting during one or more portions of a cycle. The one or more non-collapsing DC power supply components each may include one or more of a tap from one of the phase windings electrically connected to the DC power supply, a secondary phase coil winding connected to the DC power supply to power the power supply, one or more resistors between the one of the phase windings and the power switch circuit, one or more Zener diodes between one of the phase windings and the power switch circuit, and/or an electrical component to create a voltage drop between one of the phase windings and the power switch circuit to prevent the power supply from collapsing when the at least one power switch in the power switch circuit is on and conducting.

Embodiments of the invention provide a variable frequency drive system and a method of controlling a pump driven by a motor with the pump in fluid communication with a fluid system. The drive system and method can provide one or more of the following: a sleep mode, pipe break detection, a line fill mode, an automatic start mode, dry run protection, an electromagnetic interference filter compatible with a ground fault circuit interrupter, two-wire and three-wire and three-phase motor compatibility, a simple start-up process, automatic password protection, a pump out mode, digital input/output terminals, and removable input and output power terminal blocks.

A phase windings circuit for a motor includes at least two phase windings forming one half of motor phase windings of the circuit and at least two other phase windings forming another half of the motor phase windings of the circuit. A direct current (DC) power supply is located at least approximately at a midpoint of the motor phase windings to receive alternating current (AC) power transferred from one or more of the phase windings and convert the AC power to DC power. A first stage power switch circuit comprises at least one power switch outside of the DC power supply and is electrically connected at least approximately at a midpoint between phase windings on each half of the circuit. A second stage power switch circuit comprises at least one other power switch outside of the DC power supply and is electrically connected at least approximately at the midpoint of the divided phase windings to receive AC power from the motor divided phase windings. A non-collapsing DC power supply component prevents the DC power supply from collapsing when the at least one power switch or the at least one other power switch is on and conducting.

An electric drive system includes an induction machine and a power converter electrically coupled to the induction machine to drive the induction machine. The power converter comprising a plurality of silicon carbide (SiC) switching devices. The electric drive system further includes a controller that is electrically coupled to the power converter and that is programmed to transmit switching signals to the plurality of SiC switching devices at a given switching frequency such that a peak-to-peak current ripple is less than approximately five percent.

An power management unit receives AC power and, via an AC-DC-AC converter, provides an AC motor signal to a three-phase induction motor. Sensors in the power management unit provide data to a digital signal processor (DSP). The data includes a current of the AC motor signal. The DSP generates a PWM carrier signal to modulate a voltage amplitude of the AC motor signal, thereby improving the operating efficiency of the motor. The motor terminal voltage is reduced until limit conditions are reached, such as reaching a motor rated efficiency or when the motor current fluctuates.