Regenerative variable frequency drive
OwnerLarry G. Meiners, Theodore Clifton Pettyjohn +2inventors
InventorsLarry G. Meiners, Theodore Clifton Pettyjohn, Jack Yongchen Yang, Peda V. Medagam
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Abstract
A regenerative variable frequency drive includes an active converter connected to an inverter. The converter has a filter capacitor, an inductor, two half bridges, bus bars that connect to the inverter and bus capacitors. The converter converts single phase AC power to DC power and DC power to single phase AC power, boosts the AC power, reduces input line harmonics, maintains input current in phase with utility voltage in order to achieve near unity power factor, and maintains constant DC voltage between the bus bars.
Claims22
A regenerative variable frequency drive for converting single phase AC power from a power grid to three phase, variable frequency AC power and said three phase, variable frequency AC power to single phase AC power, comprising:
- a single phase AC power source,
- an inverter that converts DC power to variable frequency, three phase AC power, and variable frequency, three phase AC power to DC power, and
- an active converter for converting single phase AC power to DC power and DC power to single phase AC power, including:
- first and second input lines connected to said source,
- a first inductor having a first coil connected to said first input line and a second coil connected to said second input line,
- an active half bridge first module having an input, a positive output, and a negative output, said input connecting to said first coil of said first inductor opposite said first input line,
- an active half bridge second module having an input, a positive output, and a negative output, said input connecting to said second coil of said first inductor opposite said second input line,
- a positive bus bar connected to said positive outputs of said first and second modules, and to said inverter,
- a negative bus bar connected to said negative outputs of said first and second modules, and to said inverter,
- a first bus capacitor connected between said positive and negative bus bars, and
- a controller connected to said first and second modules and driving said first and second modules with a pulse width modulated signal having a modulation index, said controller adjusting said index and controlling current at said first inductor to maintain a selected voltage between said positive and negative bus bars and to provide correctly phased sinusoidal current from and to said source.
An active converter for converting single phase AC power to DC power and DC power to single phase AC power, comprising:
- a single phase AC power source,
- first and second input lines connected to said source,
- a first inductor having a first coil connected to said first input line and a second coil connected to said second input line,
- an active half bridge first module having an input, a positive output, and a negative output, said input connecting to said first coil of said first inductor opposite said first input line,
- an active half bridge second module having an input, a positive output, and a negative output, said input connecting to said second coil of said first inductor opposite said second input line,
- a positive bus bar connected to said positive outputs of said first and second modules,
- a negative bus bar connected to said negative outputs of said first and second modules,
- a first bus capacitor connected between said positive and negative bus bars, and
- a controller connected to said first and second modules and driving said first and second modules with a pulse width modulated signal having a modulation index, said controller adjusting said index and controlling current at said first inductor to maintain a selected voltage between said positive and negative bus bars and to provide correctly phased sinusoidal current from and to said source.
Dependencies are inferred from the claim text.