VARIABLE SPEED DRIVE

• US 20110141774A1
• Filed: 02/24/2011
• Published: 06/16/2011
• Est. Priority Date: 10/30/2007
• Status: Active Grant

• Current Assignee: Johnson Controls Tyco IP Holdings LLP (Johnson Controls International plc)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: ADIGA-MANOOR, Shreesha, BORISOV, Konstantin, KANE, Ajit W., TODD, Michael, JADRIC, Ivan
• Granted Patent: US 8,174,853 B2
• Time in Patent Office: Days
• US Class Current: 363/37
• CPC Class Codes: H02M 1/126 using passive filters
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections

Abstract

Systems and methods for improved VSDs are provided. One embodiment relates to an apparatus for common mode and differential mode filtering for motor or compressor bearing protection when operating with VSDs, including conducted EMI/RFI input power mains mitigation. Another embodiment relates to a method to extend the synchronous operation of an Active Converter to the AC mains voltage during complete line dropout. Another embodiment relates to an Active Converter-based Variable Speed Drive system with Improved Full Speed Efficiency.

Claims

1. A variable speed drive configured to receive an input AC power at a fixed AC input voltage magnitude and frequency and provide an output AC power at a variable voltage and variable frequency, the variable speed drive comprising:

a converter connected to a three phase AC power source providing the input AC voltage, the converter being configured to convert the input AC voltage to a boosted DC voltage;

a DC link connected to the converter, the DC link being configured to filter and store the boosted DC voltage from the converter;

an inverter connected to the DC link, the inverter being configured to convert the boosted DC voltage from the DC link into the output AC power having the variable voltage and the variable frequency; and

a filter comprising;

a three-phase input capacitor bank comprising three capacitors connected in a wye configuration, each capacitor of the three capacitors being connected at a first end to one phase of the three phase AC power source and at a second end to a common point with the other two capacitors;

a grounding capacitor connected between the common point and earth ground; and

wherein the three-phase input capacitor bank is configured to filter line to ground voltages of the three phase AC power source to reduce or substantially eliminate high frequency distortion across the converter stage.

2. The variable speed drive of claim 1, wherein the converter comprises active devices located at an input side of the converter.

3. The variable speed drive of claim 1, further comprising a three-phase inductor, the three-phase inductor comprising a phase winding for each phase of the three phase AC power source, wherein each winding of the three-phase inductor having a center tap dividing each phase winding into a pair of inductor sections;

and each of the three capacitors of the input capacitor bank being connected at the first end to a respective one of the center taps of the three phase induction.

4. The variable speed drive of claim 3, wherein each of the pairs of inductor sections comprises a line side inductor and a load side inductor being connected at one end to the center tap, wherein the line side inductor being connected to the AC power source at a second end opposite the center tap, and the load side inductor being connected to the converter at a second end opposite the center tap.

5. The variable speed drive of claim 1, further comprising a three-phase line reactor connected to the AC power source, the line reactor configured to limit an input current of the converter, to filter an input waveform and to attenuate electrical noise and harmonics associated with the variable speed drive.

6. The variable speed drive of claim 1, further comprising an output filter connected at an output of the inverter, the output filter configured to filter the output waveform of the variable speed drive and to attenuate electrical noise and harmonics associated with the inverter.

7. The variable speed drive of claim 6, wherein the converter further includes at least two semiconductor switches for each phase of the AC power source.

8. The variable speed drive of claim 7, wherein each of the at least two semiconductor switches comprises a pair of reverse blocking IGBTs inversely connected in parallel.

9. The variable speed drive of claim 8, wherein each semiconductor switch comprises an inverse parallel connection of the pair of the reverse blocking IGBTs.

10. The variable speed drive of claim 9, wherein each of the reverse blocking IGBTs is controllable by a controller to completely extinguishing a ground fault current.

11. The variable speed drive of claim 10, wherein the controller is configured to extinguish bi-directional current flow in a first semiconductor switch and a second semiconductor switch, for each of the three legs of the converter, to ensure a complete disconnect of the variable speed drive from a motor load connected to an output of the variable speed drive.

12. The variable speed drive of claim 9, wherein one reverse blocking IGBT of the pair of reverse blocking IGBTs of each semiconductor switch is controlled to permit only small pulses of inrush current to reach the DC link.

18. The filter of claim 1, wherein the inverter is connected to an output capacitor bank of three capacitors, each capacitor connected in a wye configuration to an output phase of the inductor;

each of the three capacitors of the output capacitor bank being connected in common at an end opposite the output phase connection;

the common capacitor connection also being connected to earth.

19. The filter of claim 1, further comprising:

an output inductor having three output phase windings connected in series with the output phase of the inverter; and

a second output capacitor bank of three capacitors, each capacitor of the second output capacitor bank being connected in a wye configuration to a load side of the output inductor;

wherein currents induced by differential mode voltage components are removed from the load side of the output inductor and prevented from flowing to a load connected to the output inductor.

13. A filter for reducing or eliminating high frequency distortion of line to ground voltages in a variable speed drive, the filter comprising:

a three-phase inductor having three windings, wherein each winding of the three-phase inductor further comprising a center tap, the center tap dividing each winding of the three-phase inductor into a pair of inductor sections;

a three-phase capacitor bank having three capacitors connected in a wye configuration to the three center taps at one end, and to a common point at an opposite end; and

a grounding capacitor connected between the common point and earth ground;

wherein the three-phase capacitor bank is configured to filter line to ground voltages to substantially eliminate high frequency voltage transients across an input of a converter of a variable speed drive.

14. The filter of claim 13, wherein each pair of inductor sections comprises a line side inductor portion and a load side inductor portion connected at one end to the center tap, and the line side inductor portion being connected to an AC power source at a second end opposite the center tap, and the load side inductor portion being connected to the converter of the variable speed drive at a second end opposite the center tap.

15. The filter of claim 13, wherein the three-phase inductor is a five legged inductor comprising:

a core element having at least three leg portions, each leg portion being wound with a pair of electric current carrying coils, and a flux portion, the flux portion connecting the at least three leg portions in a continuous magnetic path, the flux portion having a pair of vertical legs connected at a top end by a top leg and at a bottom end by a bottom leg to form a substantially rectangular frame portion, the three leg portions being positioned within and in magnetic communication with the frame portion.

16. The filter of claim 13, wherein the three phase inductor is a four legged inductor, comprising:

a core element having at least three leg portions, each leg portion being wound with a pair of electrical coils, and a flux portion, the flux portion connecting the three leg portions in a continuous magnetic path, the flux portion providing a common flux path, the flux path being excited by common mode current components flowing through the electrical coils.

17. The filter of claim 13, wherein the filter is connected between an AC power source and the converter.