For open loop phase pre-charge, an apparatus includes a Switching Mode Power Supply (SMPS) charging diode and a charge generator. The SMPS charging diode pre-charges an SMPS to a regulation set point from at least one phase of an Alternating Current (AC) voltage. The charge generator is powered by the pre-charged SMPS. In response to detecting the regulation set point iteratively, the charge generator detects a specified phase angle of the AC voltage. In response to the specified phase angle, the charge generator iteratively generates a charging voltage during positive voltage interval that charges a Direct Current (DC) bus capacitor to a target DC bus voltage within a charging time interval. At least a portion of the charge generator comprises one or more of hardware and executable code, the executable code stored on one or more computer readable storage media.

A method and line interface filter apparatus to couple a drive or group of drives to a shared multiphase AC bus, including individual phase circuits having an inductor coupled between a respective bus and drive phase lines, a resistor coupled to the respective drive phase line, and a capacitor coupled between the resistor and a common connection of the capacitors of the individual phase circuits, where the capacitance of the capacitors is 5 to 15 times a per-phase equivalent capacitance of the drive or group of drives, and the resistance of the resistors is two times a damping ratio times a square root of a ratio of the filter inductance to the filter capacitance, where the damping ratio is greater than or equal to 1.0 and less than or equal to 2.0.

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.

A power conversion apparatus capable of supplying a required reactive power while dynamically changing a dead band near 0 reactive current and maintaining a balance of DC voltage is provided. The power conversion apparatus comprises a three-level converter, a PWM controller for the three-level converter, an input current detector of the three-level converter, a coordinate converter that converts the current into a d-axis and q-axis current feedback, the reactive power control unit that controls a reactive power and outputs an reactive current reference, a d-axis current control unit having a dead band part for setting the d-axis current reference with hysteresis characteristics in the q-axis current feedback, and outputs the d-axis voltage reference, a q-axis current control unit that outputs a q-axis voltage reference based on the q-axis current reference, an inverse coordinate converter that outputs a three-phase AC voltage command based on the d-axis and q-axis voltage reference.

In order to suppress vibration with a motor a load torque of which periodically fluctuates, an output torque of the motor is controlled to be periodically changed. In this case, in order to increase a vibration suppressing component by a direct power conversion apparatus, at least one of first control and second control is performed. In the first control, an output torque having a waveform including a fundamental frequency component of the load torque a fundamental frequency of which is a frequency in accordance with a fluctuation period of the load torque and at least one of a fourth harmonic and a sixth harmonic of a power source frequency of an AC power source is generated. In the second control, the output torque having a waveform including at least one of a second harmonic and a third harmonic of the fundamental frequency of the load torque and a second harmonic of the power source frequency of the AC power source is generated.

A motor drive that outputs a sinusoidal waveform utilizes power switching devices operable at high switching frequencies. The switching devices may be operated, for example, between twenty kilohertz and one megahertz. A first filter is included at the output of the motor drive which has a bandwidth selected to attenuate voltage components at the output which are at the switching frequency or multiples thereof such that the output voltage waveform is generally sinusoidal. Additional filtering is included within the motor drive to establish a circulation path for common mode currents within the motor drive. Further, a shield is provided adjacent to those components within the motor drive that may experience voltage or current waveforms at the switching frequency or multiples thereof to cause radiated emissions to establish eddy currents within the EMI shield rather than passing through the shield into the environment.

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 order to suppress vibration with a motor a load torque of which periodically fluctuates, an output torque of the motor is controlled to be periodically changed. In this case, in order to increase a vibration suppressing component by a direct power conversion apparatus, at least one of first control and second control is performed. In the first control, an output torque having a waveform including a fundamental frequency component of the load torque a fundamental frequency of which is a frequency in accordance with a fluctuation period of the load torque and at least one of a fourth harmonic and a sixth harmonic of a power source frequency of an AC power source is generated. In the second control, the output torque having a waveform including at least one of a second harmonic and a third harmonic of the fundamental frequency of the load torque and a second harmonic of the power source frequency of the AC power source is generated.

A motor drive that outputs a sinusoidal waveform utilizes power switching devices operable at high switching frequencies. The switching devices may be operated, for example, between twenty kilohertz and one megahertz. A first filter is included at the output of the motor drive which has a bandwidth selected to attenuate voltage components at the output which are at the switching frequency or multiples thereof such that the output voltage waveform is generally sinusoidal. Additional filtering is included within the motor drive to establish a circulation path for common mode currents within the motor drive. Further, a shield is provided adjacent to those components within the motor drive that may experience voltage or current waveforms at the switching frequency or multiples thereof to cause radiated emissions to establish eddy currents within the EMI shield rather than passing through the shield into the environment.

Embodiments of the present disclosure relate to a heating, ventilating, air conditioning, and refrigeration (HVAC&R) system that includes a variable speed drive (VSD) configured to supply power to a motor configured to drive a compressor of the HVAC&R system, a rectifier of the VSD configured to receive alternating current (AC) power from an AC power source and convert the AC power to direct current (DC) power, a DC bus of the VSD electrically coupled to the rectifier, an inverter of the VSD electrically coupled to the DC bus, where the inverter is configured to convert the DC power to output AC power, the output AC power has a variable voltage and a variable frequency, and the output AC power is directed to the motor, and a battery electrically coupled to the DC bus, where the battery is configured to provide auxiliary DC power to the VSD.