Apparatus and methods for supplying DC power to control circuitry of a matrix converter is provided. In certain embodiments, a matrix converter includes an array of switches having AC inputs for receiving a multi-phase AC input voltage and AC outputs for providing a multi-phase AC output voltage to a load, such as an electric motor. The matrix converter further includes control circuitry for opening or closing individual switches of the array, and a clamp circuit connected between the AC inputs and AC outputs of the array and operable to dissipate energy of the load in response to an overvoltage condition, such as an overvoltage condition arising during shutdown. The clamp circuit includes a switched mode power supply operable to generate a DC supply voltage for the control circuitry.

An apparatus includes a first inverter circuit and a second inverter circuit. The first invertor circuit is configured to couple an alternator and a load device to deliver a driving signal from the alternator to the load device. The second invertor circuit is configured to couple the alternator to the load device to deliver a driving signal from the alternator to the load device and configured to couple a battery to the alternator to deliver a charging signal from the alternator the battery

An apparatus includes a first inverter circuit and a second inverter circuit. The first invertor circuit is configured to couple an alternator and a load device to deliver a driving signal from the alternator to the load device. The second invertor circuit is configured to couple the alternator to the load device to deliver a driving signal from the alternator to the load device and configured to couple a battery to the alternator to deliver a charging signal from the alternator the battery

A variety of methods, controllers and electric machine systems are described for pulse control of electric machines (e.g., electric motors and generators). To improve the energy conversion efficiency of the machine, pulse control involves determining if the machine should operate in a continuous mode or pulse mode, and if the latter, defining a magnitude, duty cycle, and frequency for the pulses. One or more tables, indexing by a wide range of speeds and torque requests, is/are used to define the pulsing frequency or a pulsing frequency pattern.

An aircraft propulsion system (10) comprises at least first and second electrical generators (15a, 15b), each being configured to provide electrical power to a respective first and second AC electrical network (16a, 16b). The system (10) further comprises at least first and second AC electrical motors (19a, 19b) directly electrically coupled to a respective AC network (16a, 16b) and coupled to a respective propulsor (4), and a DC electrical network electrically coupled to the first and second AC networks (16a, 16b) via respective first and second AC to DC converters (17a, 17b), and to a further electrical motor 19c), the further electrical motor (19c) being coupled to a propulsor (4).

Unique systems, methods, techniques and apparatuses of motor starters are disclosed. One exemplary embodiment is a synchronous machine including a plurality of stator phase windings, a rotor, a motor starter, and a controller. The motor starter includes a plurality of wye semiconductor switches and a plurality of delta semiconductor switches. The controller is structured to operate the plurality of wye semiconductor switches and the plurality of delta semiconductor switches so as to couple the plurality of stator phase windings in a delta configuration while an angular speed of the rotor is less than a synchronous speed, and structured to operate the plurality of wye semiconductor switches and the plurality of delta semiconductor switches so as to couple the plurality of stator phase windings in a wye configuration in response to the angular speed of the rotor being equal to the synchronous speed.

An apparatus includes a first inverter circuit and a second inverter circuit. The first invertor circuit is configured to couple an alternator and a load device to deliver a driving signal from the alternator to the load device. The second invertor circuit is configured to couple the alternator to the load device to deliver a driving signal from the alternator to the load device and configured to couple a battery to the alternator to deliver a charging signal from the alternator the battery.

An apparatus includes a first inverter circuit and a second inverter circuit. The first invertor circuit is configured to couple an alternator and a load device to deliver a driving signal from the alternator to the load device. The second invertor circuit is configured to couple the alternator to the load device to deliver a driving signal from the alternator to the load device and configured to couple a battery to the alternator to deliver a charging signal from the alternator the battery.

A power conversion system converts an input alternating-current voltage having a first frequency into an output alternating-current voltage having a second frequency lower than the first frequency. The power conversion system includes a voltage converter, a PDM controller, and a feedback controller. The voltage converter converts the input alternating-current voltage into the output alternating-current voltage in accordance with control signals and outputs the output alternating-current voltage to a load. The PDM controller performs pulse density modulation of an output voltage command value of the output alternating-current voltage to generate the control signals and outputs the control signals to the voltage converter. The feedback controller generates the output voltage command value based on an output current value of the voltage converter and a state of the load and outputs the output voltage command value to the PDM controller.

In an air conditioner that uses a refrigerant mixture containing at least 1,2-difluoroethylene, high efficiency is achieved. The motor rotation rate of a compressor (100) can be changed in accordance with an air conditioning load, and thus a high annual performance factor (APF) can be achieved. In addition, an electrolytic capacitor is not required on an output side of a rectifier circuit (21), and thus an increase in the size and cost of the circuit is suppressed.