Low voltage, two-level, six-pulse induction motor controller driving a medium-to-high voltage, three-or-more-level AC drive inverter bridge

An adapter circuit for controlling a multiple-level inverter bridge with a two-level induction motor controller, the two-level induction motor controller outputting six modulated signals for controlling switching in a two-level inverter bridge, and the multiple-level inverter bridge having N≧12 switches divided into 3 branches, the adapter circuit, comprising:

• three pairs of modulated signal inputs A1b and A2b (bε ={1, 2, 3}), whereby the six modulated signals from the two-level induction motor controller are input;
• three sets of time-coordinated signal outputs S1b to S(N/3)b, wherein each set b of time-coordinated signals output via S1b to S(N/3)b is timed to control N/3 switches of branch b of the multiple-level inverter bridge;
• and
• timing circuitry comprising circuitry selected from the group consisting of combinatorial circuits, sequential circuits, delay elements, analog-based logic gates, programmable logic, and a combination thereof, generating time-coordinated signals output via S1b to S(N/6)b from modulated signals input via A1b, and generating time-coordinated signals output via S(N/6+1)b to S(N/3)b from modulated signals input via A2b, adding at least a turn-on delay or turn-off delay to each modulated signal input via A1b and A2b,
• wherein for each set b of time-coordinated signals output via S1b to S(N/3)b, never-less-than N/6 of the N/3 time-coordinated signals has a logical-off state.

An adapter for controlling a multiple-level inverter bridge with a two-level induction motor controller, the two-level induction motor controller outputting six modulated signals for controlling switching in a two-level inverter bridge, and the multiple-level inverter bridge having N≧12 switches divided into 3 branches, the adapter, comprising:

• three pairs of modulated signal inputs A1b and A2b (bε {1, 2, 3}), whereby the six modulated signals from the two-level induction motor controller are input;
• three sets of time-coordinated signal outputs S1b to S(N/3)b, wherein each set b of time-coordinated signals output via S1b to S(N/3)b is timed to control N/3 switches of branch b of the multiple-level inverter bridge;
• and
• first conversion means for generating time-coordinated signals output via S1b to S(N/6)b from a modulated signals input via A1b, adding at least a turn-on delay or turn-off delay to generate S1b to S(N/6)b from the modulated signal input via A1b,
• second conversion means for generating time-coordinated signals output via S(N/6+1)b to S(N/3)b from a modulated signal input via A2b, adding at least a turn-on delay or turn-off delay to generate S(N/6+1)b to S(N/3)b from the modulated signal input via A2b,
• wherein for each set b of time-coordinated signals output via S1b to S(N/3)b, never-less-than N/6. of the N/3 time-coordinated signals has a logical-off state.

An induction motor drive system for driving a three-phase motor, comprising:

• a two-level induction motor controller, outputting signals for controlling a two-level inverter bridge;
• a multiple-level inverter bridge, having N≧12 switches arranged to form 3 branches, each branch providing one phase of a three-phase output for driving the three-phase motor;
• and
• an adapter circuit, generating N time-coordinated signals controlling the N switches of the multiple-level inverter bridge from said signals output by the two-level induction motor controller.

A method of controlling a multiple-level inverter bridge with a two-level induction motor controller, the two-level induction motor controller comprising a regulator and an internal modulator for a two-level inverter bridge, command signals being output from the regulator for control of the internal modulator, the method comprising:

• outputting the command signals from the two-level induction motor controller via a first interface port of the two-level induction motor controller;
• transmitting the command signals output from said first interface port via a serial or parallel connection;
• inputting the transmitted command signals into an external adapter circuit via a second interface port, said adapter circuit comprising a modulator;
• and
• generating, in the modulator of the external adapter circuit and based on the command signals input via said second interface port, twelve-or-more time-coordinated signals for controlling an inverter bridge having three-or-more levels.