Three Phase Active Rectifier System

• US 20130176753A1
• Filed: 01/10/2012
• Published: 07/11/2013
• Est. Priority Date: 01/10/2012
• Status: Active Grant

• Current Assignee: Yaskawa America, Inc. (Yaskawa Electric Corporation)
• Original Assignee: Yaskawa America, Inc. (Yaskawa Electric Corporation)
• Inventors: Swamy, Mahesh M.
• Granted Patent: US 9,099,934 B2
• Time in Patent Office: Days
• US Class Current: 363/37
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 1/4216 operating from a three-phase input voltage H02M1/4233 takes precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A voltage source inverter comprises a rectifier converting AC power to DC power at an output. An inverter receives DC power and converts the DC power to AC power. A link circuit is connected between the rectifier circuit and the inverter circuit and comprises a DC bus. A DC bus capacitor across the DC bus smoothes voltage ripple. An active filter circuit comprises a pair of filter capacitors in series across the first and second rails to create a midpoint. Bidirectional switches are connected between the rectifier input and the midpoint. A current sensor is connected between the bidirectional switches and the midpoint. An active switch controller controls a conduction angle of the bidirectional switches to maintain DC bus voltage at a desired reference level under a wide load range.

Claims

1. A voltage source inverter comprising:

a rectifier having an input for receiving multi phase AC power from an AC source and converting the AC power to DC power at an output;

an inverter for receiving DC power and converting the DC power to AC power;

a link circuit connected between the rectifier circuit and the inverter circuit and comprising a DC bus having first and second rails to provide a relatively fixed DC voltage for the inverter, and a DC bus capacitor across the first and second rails to smooth voltage ripple; and

an active filter circuit comprising a pair of filter capacitors in series across the first and second rails to create a midpoint, bidirectional switches connected between the rectifier input and the midpoint, a current sensor connected between the bidirectional switches and the midpoint and an active switch controller operatively connected to the AC source, the first and second rails and the current sensor for controlling a conduction angle of the bidirectional switches to maintain DC bus voltage at a desired reference level under a wide load range.

2. The voltage source inverter of claim 1 wherein the active filter circuit bidirectional switches comprise one for each phase.

3. The voltage source inverter of claim 2 wherein each bidirectional switch comprises two IGBTs having emitters connected together and gates controlled by the active switch controller.

4. The voltage source inverter of claim 2 wherein each bidirectional switch comprises a switch connected between nodes of a diode bridge.

5. The voltage source inverter of claim 1 wherein the active switch controller controls conduction angle in a range of 0°

to 30°

.

6. The voltage source inverter of claim 1 wherein the DC bus capacitor comprises an electrolytic capacitor and the filter capacitors comprise film capacitors.

7. The voltage source inverter of claim 1 further comprising a multi phase boost inductor connected between the AC source and the rectifier input.

8. The voltage source inverter of claim 1 wherein the active switch controller monitors ripple current and reduces the conduction angle if the ripple current increases.

9. The voltage source inverter of claim 1 further comprising a resistor network connected between the AC source and the active switch controller used as a reference voltage for detecting zero crossings.

10. The voltage source inverter of claim 9 wherein the resistor network is configured in a wye to phase shift the reference voltage if the AC source is configured in delta.

11. A boost converter comprising:

a rectifier having an input for receiving multi phase AC power from an AC source and converting the AC power to DC power at an output;

a link circuit connected to the rectifier circuit output and comprising a DC bus having first and second rails to provide a relatively fixed DC voltage for a load comprising plural DC/AC converters fed from a common DC voltage source with each DC/AC converter having a DC bus capacitor to smooth voltage ripple; and

an active filter circuit comprising a pair of filter capacitors in series across the first and second rails to create a midpoint, bidirectional switches connected between the rectifier input and the midpoint, a current sensor connected between the bidirectional switches and the midpoint and an active switch controller operatively connected to the AC source, the first and second rails and the current sensor for controlling a conduction angle of the bidirectional switches to maintain DC bus voltage at a desired reference level under a wide load range.

12. The boost converter of claim 11 wherein the active filter circuit bidirectional switches comprise one for each phase.

13. The boost converter of claim 12 wherein each bidirectional switch comprises two IGBTs having emitters connected together and gates controlled by the active switch controller.

14. The boost converter of claim 12 wherein each bidirectional switch comprises a switch connected between nodes of a diode bridge.

15. The boost converter of claim 11 wherein the active switch controller controls conduction angle in a range of 0°

to 30°

.

16. The boost converter of claim 11 wherein the DC bus capacitor comprises an electrolytic capacitor and the filter capacitors comprise film capacitors.

17. The boost converter of claim 11 further comprising a multi phase boost inductor connected between the AC source and the rectifier input.

18. The boost converter of claim 11 wherein the active switch controller monitors ripple current and reduces the conduction angle if the ripple current increases.

19. The boost converter of claim 11 further comprising a resistor network connected between the AC source and the active switch controller used as a reference voltage for detecting zero crossings.

20. The boost converter of claim 19 wherein the resistor network is configured in a wye to phase shift the reference voltage if the AC source is configured in delta.