ADVANCED MATRIX CONVERTER AND METHOD FOR OPERATION

• US 20080285314A1
• Filed: 05/09/2008
• Published: 11/20/2008
• Est. Priority Date: 05/14/2007
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: KOJORI, HASSAN ALI
• Granted Patent: US 7,848,121 B2
• Time in Patent Office: Days
• US Class Current: 363/37
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/344 Active dissipative snubbers
• CPC Class Codes: H02M 5/271 from a three phase input voltage
• CPC Class Codes: H02M 5/273 with digital control
• CPC Class Codes: H02M 5/293 using semiconductor devices only

Abstract

A matrix converter may be provided with AC switches that comprise bi-directional sets of semiconductor switches that are gated with a common gating link. A low loss diode-bridge based snubber may facilitate introduction of time delay between sequential operations of the bi-directional set of semiconductor switches. The matrix converter may be operated in a three-phase mode with only one gating signals for each AC switch, in contrast to prior-art matrix converters which may require use multiple gating signals for each AC switch.

Claims

1. A matrix converter comprising:

a plurality of at least N by M (N×

M) bidirectional alternating current (AC) switches, wherein

N corresponds to the number of AC system phases at an input of the matrix converter and M corresponds to the number of required phases at an output of the matrix converter, and

each of the AC switches includes multiple switching devices, each of the switching devices with a common gating pattern.

2. The matrix converter of claim 1, wherein the N switching devices in each of the M AC Switch Blocks, are bidirectional semiconductor switching devices.

3. The matrix converter of claim 1 comprising:

three-phase inputs;

three-phase outputs; and

at a desired frequency and voltage of output is produced by operation of gate driver signals for main switches of the matrix converter.

4. The matrix converter of claim 3, further comprising:

a bidirectional set of semiconductor switches coordinated to operate sequentially with a time-delay between sequential operations; and

a snubber absorbing energy during the time delay where all the N switches of one of the M blocks are in the off-position.

5. The matrix converter of claim 1 further comprising:

a time-delay incorporated for the AC switches;

the time-delay is introduced at every turn-on of their respective AC switches to prevent short-circuit of the source-side AC phases.

6. The matrix converter of claim 1 wherein there is a snubber circuit across each of the AC switches to ensure that no open-circuit condition happens at an output side of the matrix converter, causing current chopping.

7. The matrix converter of claim 5 wherein the snubber comprises:

a diode-bridge;

a capacitor;

a resistor; and

auxiliary switch resulting in a dissipative energy discharge circuit connected in series between positive and negative terminals of the diode-bridge and allowing to regulate the capacitor within an upper-lower voltage level through a bang-bang control.

8. The matrix converter of claim 1, further comprising an energy recovery circuit, wherein the energy recovery circuit is one of a) a DC-DC converter to convert recovered energy into a regulated DC bus for use of other loads;

b) a DC-AC converter to convert recovered energy for achieving active filtering/damping at an input side of the matrix converter;

or c) a DC-AC converter to convert recovered energy for achieving active filtering/damping at an output side of the matrix converter.

9. The matrix converter of claim 1, wherein the switching device is a MOSFET-Based AC switch with multiple MOSFETS in parallel resulting in reduction of Rds and with ability to operate at high switching frequency

10. An AC switch for a matrix converter comprising:

a diode-bridge based snubber;

a time-delay unit;

a bidirectional set of semiconductor switches coordinated to operate sequentially with a time-delay between sequential operations; and

the snubber absorbing energy during the time delay.

11. The AC switch of claim 10 wherein the sub-devices of the bi-directional set of semiconductor switches is provided with a common gating link.

12. The AC switch of claim 10 wherein the snubber comprises a full-wave diode rectifier made of fast recovery diodes configured with low impedance path to effectively route recovered energy during delay-time to the said snubber capacitor.

13. The AC switch of claim 10 wherein for a N×

1 matrix converter, as a minimum only N common gate-driver signals are required at any time for safe and reliable operation of the AC switches.

14. A method for providing electrical power at a desired controlled frequency and voltage from a variable voltage variable frequency source comprising the steps of:

supplying AC power to a matrix converter;

operating multiple semiconductor switches simultaneously with common gating; and

introducing time-delay between successive operations of the semiconductor switches to preclude short-circuit of supply voltages or open circuit conditions at an output of the matrix converter.

15. The method of claim 14 further comprising the step of absorbing energy in at least one diode-bridge based snubber during the time-delay, wherein each of said snubbers can work individually independent from each other, or integrated together to form a common Aux DC Bus, with common bus voltage and energy recovery circuit.

16. The method of claim 15 further comprising the step of managing stored energy, in which the recovered energy from the individual snubbers or an integrated snubber system with one common auxiliary DC Bus can be either a) dissipated in an individual/integrated snubber resistor or b) recovered by an energy recovery circuit.

17. The method of claim 14 wherein electrical power is provided from the source as three-phase power;

and

wherein a desired output voltage at a certain frequency is produced with nine gating signals as a minimum for each cycle of operation of the matrix converter.

18. The method of claim 17 wherein the matrix converter operates with snubber gating patterns which are either the same as gating patterns for the sets of bi-directional semiconductors, when it is intended to fully discharge the capacitor voltage, or are determined in such a way to regulate the Aux DC Bus voltage well above natural rectification of the AC system to minimize energy flow to and circulation into the snubber circuit.