Adapter Circuit for Two-Level Controller Driving Multi-Level Inverter
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Solution Overview
Problem
The high cost and complexity of controlling multiple-level inverter bridges for medium-and-high voltage induction motors, due to the need for numerous power semiconductor switches and sophisticated timing of switch signals, limit the use of existing low-voltage controllers for these applications, resulting in more expensive and less capable controllers for medium-and-high voltage systems.
Innovation Solution
Adapting 'off-the-shelf' two-level induction motor controllers to drive three-or-more level inverter bridges by converting six modulated signals into twelve-or-more time-coordinated signals, using an adapter circuit with timing circuitry to control the switches, allowing existing low-voltage controllers to manage multiple-level inverter bridges effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple-level inverter bridges are used for medium-and-high voltage induction motors, then voltage capability and output power are improved, but device complexity and control difficulty increase due to numerous power semiconductor switches and sophisticated timing requirements
Solution Approach 1:
The patent segments the control function by separating the controller into two parts: an existing low-voltage two-level controller that generates six modulated signals, and a new adapter circuit that converts these into twelve-or-more time-coordinated signals for the multiple-level inverter. This segmentation allows the complex multiple-level control to be handled by a dedicated adapter while reusing the proven low-voltage controller.
Solution Approach 2:
The adapter circuit serves as an intermediary between the low-voltage two-level controller and the multiple-level inverter bridge. It receives six modulated signals from the controller and transforms them into twelve-or-more time-coordinated switch control signals, mediating the interface between incompatible control systems and enabling the use of existing controllers for multiple-level applications.
2Power
If multiple-level inverter bridges are used for medium-and-high voltage applications, then voltage capability is improved, but controller cost increases due to specialized control requirements
Solution Approach 1:
The adapter circuit provides universal compatibility by enabling existing low-voltage two-level controllers to control multiple-level inverter bridges. This multi-functionality allows a single adapter design to work with various controller and inverter combinations, eliminating the need for expensive specialized controllers and reducing manufacturing costs through reuse of proven components.
Solution Approach 2:
The patent copies the successful low-voltage two-level controller design and extends its applicability to multiple-level systems through the adapter circuit. Rather than creating entirely new specialized controllers, the solution copies and adapts existing proven controller architectures, reducing development and manufacturing costs while maintaining reliability.
3Ease of manufacture
If existing low-voltage controllers are adapted for multiple-level inverter bridges, then controller cost is reduced, but signal coordination complexity increases requiring precise timing of switch signals
Solution Approach 1:
The patent extracts the timing and coordination complexity from the main controller by placing it in a separate adapter circuit. The adapter specifically handles the complex signal transformation and timing coordination, while the existing controller focuses on generating the basic six modulated signals. This extraction simplifies the overall system architecture and maintains cost effectiveness.
Solution Approach 2:
The adapter circuit performs preliminary action by pre-coordinating the timing of all switch signals before they reach the inverter bridge. It calculates and establishes the proper timing relationships between twelve-or-more switch signals based on the six input modulated signals, ensuring proper coordination is achieved in advance rather than requiring complex real-time coordination during operation.
Data Source
AI summary
A method and circuit enabling off-the-shelf controllers designed for use with a two-level AC drive inverter bridge (1920) to drive inverter bridges with three-or-more levels. Signals from an ordinary induction motor controller or a two-level induction motor controller (2200) are used to drive the twelve-or-more switches of a three-or-more level inverter bridge (1920), as are used in medium-and-high voltage applications. The proper sequence and timing of switching for the three-or-more-level inverter bridge is based in-part upon either the output of the six pulse-width modulators, or the output of the flux and torque control device, or the voltage control device (2210), of the two-level controller (2200).