Adaptive overlapping communication control of modular AC-AC converter and integration with device module of multiple AC-AC switches

• US 5,892,677 A
• Filed: 06/02/1997
• Issued: 04/06/1999
• Est. Priority Date: 06/02/1997
• Status: Expired due to Term

• Current Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Original Assignee: Reliance Electric Industrial Company (ABB Limited)
• Inventors: Chang, Jie
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US08/867,125
• Time in Patent Office: 673 Days
• Field of Search: 363/152, 363/157, 363/163
• US Class Current: 363/152
• CPC Class Codes: H02M 5/293 using semiconductor devices only
• CPC Class Codes: H02M 5/297 for conversion of frequency

Abstract

A high power AC--AC converter having integrated adaptive commutation control and a new modularity design based on standard per-phase floating AC power-building modules. The per-phase floating AC power building modules designed with high voltage throughput and optimal partitioning differential output architecture which is suitable for multi-phase multi-module high power electronic systems. Now integrated and smart AC power switch modules are provided to reduce the gate control complexity, minimize circuit connection terminals and simplify power bus structure.

Claims

1. AC--AC converter building modules comprising:

a means to convert fixed-frequency and fixed-voltage multi-phase AC power to adjustable-frequency and variable-voltage single-phase floating power cells or a power phase bank;

a means for integrating the power cells or power phase bank at a system level, thereby forming multi-phase power electronic systems;

wherein the means for integrating forms an integrated multiple AC-switch power module which has less device power terminals, a reduced power bus structure and a simplified gate control complexity compared to a power circuit of a same power output which is not integrated ; and

wherein there is adaptive commutation control.

2. The AC--AC converter building modules according to claim 1 wherein:

the integrating means forms a three-to-one AC--AC converter which has a single-phase output stage with two output power terminals suitable for multi-module interconnections for high power systems.

3. The AC--AC converter building modules according to claim 1 wherein:

the AC--AC converter modules are configured with differential circuit architecture and differential modulation control, providing power cells with high voltage throughput and an output stage suitable for multi-module interconnections for high power systems.

4. The AC--AC converter building modules according to claim 1 further including:

a dielectric isolation between the power cells, obtained from isolation of secondary windings of a power transformer supplying the fixed-frequency and fixed-voltage multi-phase AC power.

5. The AC--AC converter building modules according to claim 1 further including,

adaptive commutation control to ensure safe and efficient commutation of the AC--AC converter modules, the adaptive commutation control having,

(a) an inverting-amplitude-absolute and VFC (voltage to frequency converter) circuit combination which converts an AC load current signal to an upside down full-rectified sinusoidal wave in superposition with a dc bias, which is fed to the voltage to frequency converter (VFC) to generate a clock pulse train whose period is in proportion to an amplitude of the load current, wherein the biased amplitude signal is for a minimum period of timing pulses measuring the state transition time.

6. The AC--AC converter building modules according to claim 5 further including,

a means for adaptive timing signal generation of timing signals t₁, t₂, t₃, in real time and controlled by a DSP or microprocessor, for controlling converter commutation state transition according instantaneous load current level, the means for adaptive timing signal generation further having,

(1) an adaptive clock-pulse train generation means which converts upside down full-rectified sinusoidal waves with a dc bias to a variable frequency clock and timing signals, t₁, t₂, t₃, by a set of loadable counters which are driven by the variable frequency clock;

(2) means for scaling and real-time control of the timing signals, t₁, t₂, t₃, which are controlled by the loadable counters and a DSP or microprocessor; and

incorporating means for incorporating the timing signals t₁, t₂, t₃, which are in proportion to the instantaneous load current level, into optimal sequence commutation control and gate mapping to adapt the variation of the load current and possible load parameter and switching power device changes for improving commutation control.

7. The AC--AC converter building modules according to claim 5, wherein the adaptive commutation control further includes a combination of optimal sequence commutation control means and AC switch gate mapping means, comprising:

a means for optimized switching, based on transient switching property of bi-directional power switches of the power cells or the power phase bank, which controls commutation switching in both incoming and outgoing phases to eliminate potential short circuiting path between two input phases during an overlapping commutation, while maintaining the continuity of output current at a same time.

8. The AC--AC converter building modules according to claim 7 wherein said bi-directional power switch control includes the optimal sequence commutation control, and an inner gate mapping of the converter modules with a minimum 16 logic states and a symmetric control flow chart structure.

9. The AC--AC converter building module according to claim 1, further including a commutation snubber circuit to limit high-amplitude narrow current pulses circulating between outgoing and incoming phases during a semi-soft sequence commutation, wherein limiting the circulating current comprises:

(a) a means of using ultra fast reverse recovery of the bi-directional switches, and

(b) an external current limiting resistor in a R-C snubber circuit to reduce the circulating current to a safe level.

10. The AC--AC converter building module according to claim 1, wherein the multiple AC-switch power module includes:

(a) optimal circuit partitioning and bus interfacing to minimize the number of output power terminals; and

b) optimal inner circuit connection and circuit scheme of a 3-in-1 AC-switch power module, featuring a minimum number of output power and gate terminals.

11. The AC--AC converter building module according to claim 1 further including an integrated AC switch power module configuration and smart-AC switch power module design having an integrated adaptive commutation control circuit and an integrated multiple AC switch,

wherein optimal design of inner electrical connections and partitioning minimizes the number of output power terminals;

and

wherein the integration of the adaptive commutation control circuit into the power module of multiple AC switches for all phase circuits, simplifies gate control, and reduces gate terminals of the converter.

12. The AC--AC converter building module according to claim 1 being used to form configurations including,

3-in-1 integrated and smart AC switch power modules;

6-in-1 integrated and smart multiple AC switch power modules for differential per-phase module; and

9-in-1 integrated and smart multiple AC switch power modules.

13. The differential per-phase building module according to claim 1 further connected in at least one of a "star" or "delta" connection to achieve a higher power three phrase AC--AC conversion system.

14. A multi-module AC--AC converter comprising:

a multi-phase input power supply;

two output terminals in a per-phase power module,

a first phase switching network including an internal switching element connected between the multi-phase power supply and the output terminal, the internal switching element constructed such that during a commutation transient when a portion of the switching element is active a current path is maintained from the multi-phase power supply through the first phase switching network to the output terminal, and reverse current is blocked from flowing back through the first phase switching network, wherein, while in steady-state conduction the switch allows a bi-directional current flow;

a second phase switching network including an internal switching element connected between the multi-phase power supply and the output terminal, the internal switching element constructed such that it has the same switching property as the first phase switching element;

an alternative commutation current path network connected between the first phase switching network and the second phase switching network on a power input side, wherein current from outgoing phase networks are steered to increase an output of an incoming phase network; and

wherein there is adaptive commutation control.

15. The converter and converter building module according to claim 14 further including a third phase switching network including an internal switching element connected between the multi-phase power supply and the output terminal, the internal switching element constructed such that it has the same switching property as the first phase switching element;

and

the alternative commutation current path network further connected between the first phase switching network and the third phase switching network, and between the second phase switching network and the third phase switching network.

16. The converter building module according to claim 15, further including an adaptive commutation control circuit having,

(a) an inverting-amplitude-absolute and VFC (voltage to frequency converter) circuit combination which converts an AC load current signal to an upside down full-rectified sinusoidal wave in superposition with a dc bias, which is fed to the voltage to frequency converter (VFC) to generate a clock pulse train whose period is in proportion to an amplitude of the load current, wherein the biased amplitude signal is for a minimum period of timing pulses measuring the state transition time.

17. The converter building module according to claim 16 wherein the first through third phase switching networks and the adaptive commutation control circuit are physically integrated in a single multiple-AC-switch power module which comprises a first switching circuit bank.

18. The converter according to claim 17 further including a second switching circuit bank substantially identical to the first switching bank, wherein the first and second switching banks are connected to generate a differential output and form a 3-to-1 variable-voltage and variable-frequency converter or per-phase building module.

19. The converter according to claim 17, further including fourth through ninth phase switching networks, wherein the fourth through sixth phase switching networks have associated therewith a second adaptive commutation control circuit, and the seventh through the ninth phase switching networks have associated therewith a third adaptive commutation control unit.

20. The differential per-phase building module according to claim 18 further connected in at least one of a "star" or "delta" connection to achieve a higher power three phase AC--AC conversion system.