Variable speed drive for a chiller system with a switched reluctance motor
First Claim
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1. A drive system for a compressor of a chiller system, the drive system comprising:
- a variable speed drive, the variable speed drive being configured to receive an input AC power at a fixed input AC voltage and a fixed input frequency and provide an output power at a variable voltage and variable frequency, the variable voltage having a maximum voltage greater in magnitude than the fixed input AC voltage and the variable frequency having a maximum frequency greater than the fixed input frequency, the variable speed drive comprising;
a pulse width modulated boost rectifier having insulated gate bipolar transistors connected to an AC power source providing the input AC power, the pulse width modulated boost rectifier being configured to convert the fixed input AC voltage to a boosted DC voltage, the boosted DC voltage being greater than the fixed input AC voltage;
a DC link connected to the pulse width modulated boost rectifier, the DC link being configured to filter the boosted DC voltage and store energy from the pulse width modulated boost rectifier; and
an inverter stage connected to the DC link, the inverter stage having a plurality of inverter legs, each inverter leg of the plurality of inverter legs including a first insulated gate bipolar transistor (IGBT) power switch and a second IGBT power switch the inverter stage being configured to convert the boosted DC voltage from the DC link into the output power having the variable voltage and the variable frequency; and
a switched reluctance motor having a plurality of stator windings each stator winding of the plurality of stator windings connected in series between the inverter leg first and second IGBT power switches of the inverter stage and powered by the output power from the inverter stage, the switched reluctance motor being connectable to a compressor of the chiller system to power the compressor.
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Abstract
A variable speed drive with a boost converter is provided for a chiller system driven by a switched reluctance motor. The boost converter can be a diode or thyristor rectifier followed by a boost DC/DC converter or a three-phase pulse width modulated boost converter. The boost converter provides a boosted voltage to the DC link, which results in a boosted voltage being applied to the switched reluctance motor by the inverter of the variable speed drive.
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Citations
20 Claims
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1. A drive system for a compressor of a chiller system, the drive system comprising:
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a variable speed drive, the variable speed drive being configured to receive an input AC power at a fixed input AC voltage and a fixed input frequency and provide an output power at a variable voltage and variable frequency, the variable voltage having a maximum voltage greater in magnitude than the fixed input AC voltage and the variable frequency having a maximum frequency greater than the fixed input frequency, the variable speed drive comprising;
a pulse width modulated boost rectifier having insulated gate bipolar transistors connected to an AC power source providing the input AC power, the pulse width modulated boost rectifier being configured to convert the fixed input AC voltage to a boosted DC voltage, the boosted DC voltage being greater than the fixed input AC voltage;
a DC link connected to the pulse width modulated boost rectifier, the DC link being configured to filter the boosted DC voltage and store energy from the pulse width modulated boost rectifier; and
an inverter stage connected to the DC link, the inverter stage having a plurality of inverter legs, each inverter leg of the plurality of inverter legs including a first insulated gate bipolar transistor (IGBT) power switch and a second IGBT power switch the inverter stage being configured to convert the boosted DC voltage from the DC link into the output power having the variable voltage and the variable frequency; and
a switched reluctance motor having a plurality of stator windings each stator winding of the plurality of stator windings connected in series between the inverter leg first and second IGBT power switches of the inverter stage and powered by the output power from the inverter stage, the switched reluctance motor being connectable to a compressor of the chiller system to power the compressor. - View Dependent Claims (2, 3, 5, 6, 7, 8, 9, 10)
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4. (canceled)
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11. A chiller system comprising:
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a compressor, a condenser, and an evaporator connected in a closed refrigerant loop;
a switched reluctance motor connected to the compressor to power the compressor; and
a variable speed drive connected to the switched reluctance motor, the variable speed drive being configured to receive an input AC power at a fixed input AC voltage and a fixed input frequency and provide an output power at a variable voltage and variable frequency to the switched reluctance motor, the variable voltage having a maximum voltage greater in magnitude than the fixed input AC voltage and the variable frequency having a maximum frequency greater than the fixed input frequency, the variable speed drive comprising;
a pulse width modulated boost rectifier having insulated gate bipolar transistors connected to an AC power source providing the input AC power, the pulse width modulated boost rectifier being configured to convert the fixed input AC voltage to a boosted DC voltage, the boosted DC voltage being greater than the fixed input AC voltage;
a DC link connected to the pulse width modulated boost rectifier, the DC link being configured to filter the boosted DC voltage and store energy from the pulse width modulated boost rectifier;
an inverter stage connected to the DC link, the inverter stage having a plurality of inverter legs, each inverter leg of the plurality of inverter legs including a first insulated gate bipolar transistor (IGBT) power switch and a second IGBT power switch the inverter stage being configured to convert the boosted DC voltage from the DC link into the output power having the variable voltage and the variable frequency; and
a switched reluctance motor having a plurality of stator windings each stator winding of the plurality of stator windings connected in series with one of the inverter leg first and second IGBT power switches of the inverter stage and powered by the output power from the inverter stage, the switched reluctance motor being connectable to a compressor of the chiller system to power the compressor. - View Dependent Claims (12, 13, 15, 16, 17, 18, 19, 20)
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14. (canceled)
Specification