Abstract: A fan drive circuit for a variable speed fan motor in a cooling system, includes an inverter configured to supply a current signal to stator windings of the variable speed fan motor, a frequency detection circuit coupled to an output stage of an inverter of a compressor motor of the cooling system and configured to detect a first frequency of a compressor current signal at the output stage of a variable speed compressor drive circuit and generate a frequency signal, and a digital signal processor (DSP) coupled to the inverter and the frequency detection circuit. The DSP is configured to receive the frequency signal corresponding to the first frequency from the frequency detection circuit, select a second frequency corresponding to the first frequency at which to operate the variable speed fan motor, and transmit control signals to the inverter to supply current to the stator windings at the second frequency.

Abstract: A method of additive manufacturing includes providing a substrate material at a location proximate a surface of a part and forming the substrate material into an additive layer on top of the surface by exposing the substrate material to a first laser beam having a first power level. After forming the additive layer on the part, the method includes cooling at least a portion of the additive layer from a first temperature reached at the completion of the forming step to a second temperature. After cooling, the method includes exposing the additive layer to a second laser beam having a second power level, wherein the second power level is lower than the first power level.

Abstract: A fan drive circuit for a variable speed fan motor in a cooling system, includes an inverter configured to supply a current signal to stator windings of the variable speed fan motor, a frequency detection circuit coupled to an output stage of an inverter of a compressor motor of the cooling system and configured to detect a first frequency of a compressor current signal at the output stage of a variable speed compressor drive circuit and generate a frequency signal, and a digital signal processor (DSP) coupled to the inverter and the frequency detection circuit. The DSP is configured to receive the frequency signal corresponding to the first frequency from the frequency detection circuit, select a second frequency corresponding to the first frequency at which to operate the variable speed fan motor, and transmit control signals to the inverter to supply current to the stator windings at the second frequency.

Abstract: A method of additive manufacturing includes providing a substrate material at a location proximate a surface of a part and forming the substrate material into an additive layer on top of the surface by exposing the substrate material to a first laser beam having a first power level. After forming the additive layer on the part, the method includes cooling at least a portion of the additive layer from a first temperature reached at the completion of the forming step to a second temperature. After cooling, the method includes exposing the additive layer to a second laser beam having a second power level, wherein the second power level is lower than the first power level.

Abstract: A fan drive circuit for a variable speed fan motor in a cooling system, includes an inverter configured to supply a current signal to stator windings of the variable speed fan motor, a frequency detection circuit coupled to an output stage of an inverter of a compressor motor of the cooling system and configured to detect a first frequency of a compressor current signal at the output stage of a variable speed compressor drive circuit and generate a frequency signal, and a digital signal processor (DSP) coupled to the inverter and the frequency detection circuit. The DSP is configured to receive the frequency signal corresponding to the first frequency from the frequency detection circuit, select a second frequency corresponding to the first frequency at which to operate the variable speed fan motor, and transmit control signals to the inverter to supply current to the stator windings at the second frequency.

Abstract: A fan drive circuit for a variable speed fan motor in a cooling system, includes an inverter configured to supply a current signal to stator windings of the variable speed fan motor, a frequency detection circuit coupled to an output stage of an inverter of a compressor motor of the cooling system and configured to detect a first frequency of a compressor current signal at the output stage of a variable speed compressor drive circuit and generate a frequency signal, and a digital signal processor (DSP) coupled to the inverter and the frequency detection circuit. The DSP is configured to receive the frequency signal corresponding to the first frequency from the frequency detection circuit, select a second frequency corresponding to the first frequency at which to operate the variable speed fan motor, and transmit control signals to the inverter to supply current to the stator windings at the second frequency.

Abstract: A motor controller for an electric motor includes a drive circuit that regulates power supplied to a stator of the electric motor to turn a rotor. The motor controller includes a communication interface that receives coefficients. The motor controller includes a processor coupled to the drive circuit. The processor receives an airflow rate demand, computes a speed, computes a torque set point as a function of at least a sum of first and second terms. The first term is defined as the first coefficient multiplied by the airflow rate demand raised to a power greater than one, and the second term is defined as the second coefficient multiplied by the speed raised to a power greater than one. The processor controls the drive circuit based on the torque set point to supply electrical power to the electric motor.

Abstract: A method of controlling an electrical machine. The electrical machine includes a stator having a core and a plurality of windings, and a rotor disposed adjacent to the stator to interact with the stator. The method includes configuring an amplitude value and frequency values of a three-phase alternating current (AC) voltage startup signal having an amplitude and a frequency, providing the three-phase alternating current (AC) voltage startup signal to the plurality of windings, and altering the frequency of the three-phase AC voltage startup signal according to a preprogrammed frequency ramp function defined by the frequency values. The method further includes discontinuing the three-phase AC voltage startup signal after the frequency ramp function has completed, and switching to a back electromotive force (BEMF) control mode after discontinuing the three-phase AC voltage startup signal.

Abstract: A loss-less snubber drive for a permanent magnet motor. The motor system includes a first motor phase with a primary winding and an auxiliary winding. A controllable switch is positioned between the primary winding and ground such that current passes through the primary winding to ground when the controllable switch is closed. A capacitor is configured to accumulate charge when the controllable switch is opened. The auxiliary winding is configured such that charge stored by the capacitor causes current to pass through the auxiliary winding when the controllable switch is closed.

Abstract: A method of controlling an electrical machine. The electrical machine includes a stator having a core and a plurality of windings, and a rotor disposed adjacent to the stator to interact with the stator. The method includes configuring an amplitude value and frequency values of a three-phase alternating current (AC) voltage startup signal having an amplitude and a frequency, providing the three-phase alternating current (AC) voltage startup signal to the plurality of windings, and altering the frequency of the three-phase AC voltage startup signal according to a preprogrammed frequency ramp function defined by the frequency values. The method further includes discontinuing the three-phase AC voltage startup signal after the frequency ramp function has completed, and switching to a back electromotive force (BEMF) control mode after discontinuing the three-phase AC voltage startup signal.

Abstract: A loss-less snubber drive for a permanent magnet motor. The motor system includes a first motor phase with a primary winding and an auxiliary winding. A controllable switch is positioned between the primary winding and ground such that current passes through the primary winding to ground when the controllable switch is closed. A capacitor is configured to accumulate charge when the controllable switch is opened. The auxiliary winding is configured such that charge stored by the capacitor causes current to pass through the auxiliary winding when the controllable switch is closed.

Abstract: A temperature control circuit which is capable of operating a microprocessor on a very low voltage source. The temperature control circuit uses a pair of field effect transistors and a zener diode in an oscillator circuit to amplify the source voltage. A microprocessor is supplied by the amplified source voltage, and is connected through a transistor to a temperature sensing portion of the circuit. The microprocessor uses the transistor to turn the power to the temperature sensing circuit portion off between temperature samples. By turning the temperature sensing circuit power off between samples, the average power drain by the control circuit is an amount that can be met by the amplified voltage from the low voltage source.