Variable speed drive
First Claim
1. A converter module for a variable speed drive comprising:
- a plurality of switching modules, one switching module of the plurality of switching modules comprising a first semiconductor switch connected in anti-parallel or series with a second semiconductor switch, the second semiconductor switch being controllably switched during a precharge operation of the variable speed drive to limit an inrush current into the DC link, and the second semiconductor switch comprising a maximum current rating less than a maximum current rating of the first semiconductor switch;
wherein the first semiconductor switch is controlled by applying a first voltage, and the second semiconductor switch is controlled by a second voltage greater than the first voltage.
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Abstract
A converter module for a variable speed drive having a semiconductor device for precharge is described. The precharge circuit includes switching modules, one switching module with a first semiconductor switch connected in parallel or series with a second semiconductor switch. The second semiconductor switch is switched on and off during the precharge operation in order to limit the inrush current into the DC Link. After the precharge operation, the second semiconductor switch is turned on all the time and acts like a diode. The second semiconductor device may have a lower maximum current rating than the main semi-conductor devices. The lower current rated semiconductor device experience the same short circuit current as the higher current rated semiconductor device. The lower current rated semiconductor device can be supplied with a larger gate to emitter voltage than the higher current rated semiconductor device to equalize current between semiconductor devices.
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Citations
18 Claims
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1. A converter module for a variable speed drive comprising:
- a plurality of switching modules, one switching module of the plurality of switching modules comprising a first semiconductor switch connected in anti-parallel or series with a second semiconductor switch, the second semiconductor switch being controllably switched during a precharge operation of the variable speed drive to limit an inrush current into the DC link, and the second semiconductor switch comprising a maximum current rating less than a maximum current rating of the first semiconductor switch;
wherein the first semiconductor switch is controlled by applying a first voltage, and the second semiconductor switch is controlled by a second voltage greater than the first voltage. - View Dependent Claims (2, 3, 4, 5, 6)
- a plurality of switching modules, one switching module of the plurality of switching modules comprising a first semiconductor switch connected in anti-parallel or series with a second semiconductor switch, the second semiconductor switch being controllably switched during a precharge operation of the variable speed drive to limit an inrush current into the DC link, and the second semiconductor switch comprising a maximum current rating less than a maximum current rating of the first semiconductor switch;
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7. A variable speed drive comprising:
- a converter connected to an AC power source providing an input AC power, the converter being configured to convert the fixed input AC voltage to a DC voltage;
a DC link connected to the converter, the DC link being configured to filter the DC voltage and store energy from the converter; and
an inverter connected to the DC link, the inverter being configured to convert a DC voltage from the DC link into the output power having a variable voltage and a variable frequency; and
the converter comprises a precharge circuit, the precharge circuit comprising a plurality of switching modules, one switching module of the plurality of switching modules comprising a first semiconductor switch connected in anti-parallel or series with a second semiconductor switch, the second semiconductor switch being controllably switched during a precharge operation of the variable speed drive to limit an inrush current into the DC link, and the second semiconductor switch comprising a maximum current rating less than a maximum current rating of the first semiconductor switch;wherein the first semiconductor switch is controlled by applying a first voltage, and the second semiconductor switch is controlled by a second voltage greater than the first voltage. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
- a converter connected to an AC power source providing an input AC power, the converter being configured to convert the fixed input AC voltage to a DC voltage;
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15. A drive for a 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 converter connected to an AC power source providing an input AC power, the converter being configured to convert the fixed input AC voltage to a DC voltage;
a DC link connected to the converter, the DC link being configured to filter the DC voltage and store energy from the converter;
an inverter connected to the DC link, the inverter being configured to convert a DC voltage from the DC link into the output power having a variable voltage and a variable frequency; and
the converter comprises a precharge circuit, the precharge circuit comprising a plurality of switching modules, one switching module of the plurality of switching modules comprising a first semiconductor switch connected in anti-parallel or series with a second semiconductor switch, the second semiconductor switch being controllably switched during a precharge operation of the variable speed drive to limit an inrush current into the DC link, and the second semiconductor switch comprising a maximum current rating less than a maximum current rating of the first semiconductor switch;wherein the first semiconductor switch is controlled by applying a first voltage, and the second semiconductor switch is controlled by a second voltage greater than the first voltage. - View Dependent Claims (16, 17, 18)
- 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;
Specification