Voltage balancing circuits with integrated braking chopper for series connected inverters

A drive system for an alternating current (AC) multiphase machine, the drive system comprising

• a first inverter comprising a first capacitor;
• a second inverter comprising a second capacitor, wherein the first and second capacitors are coupled in series to form a first branch, and wherein the first and second capacitors have a first node disposed therebetween;
• and
• an integrated voltage balancing and braking chopper circuit, comprising:
• first, second, third, and fourth power switches coupled in series to form a second branch, wherein the second branch is in parallel with the first branch;
• a first brake resistor coupled in series with a first chopper switch to form a third branch, wherein the third branch is coupled between a terminal of the first capacitor and a second node disposed between the first and second power switches, and wherein the third and fourth power switches have a third node disposed therebetween;
• a second brake resistor coupled in series with a second chopper switch to form a fourth branch, wherein the fourth branch is coupled between a terminal of the second capacitor and a fourth node disposed between the third and fourth power switches;
• and
• a third capacitor and/or an inductor forming a fifth branch, wherein the fifth branch is coupled between (i) the second node and the fourth node, or (ii) the first node and the third node.

An integrated voltage balancing and braking chopper circuit, comprising:

• a first power switch coupled between a positive terminal of a first capacitor and a first node;
• a second power switch coupled between the first node and a second node;
• a third power switch coupled between the second node and a third node;
• a fourth power switch coupled between the third node and a negative terminal of a second capacitor, wherein the first and second capacitors are coupled in series;
• a first breaking chopper coupled between the first node and one of the positive terminal of the first capacitor and a negative terminal of the first capacitor;
• a second breaking chopper coupled between the third node and one of a positive terminal of the second capacitor and the negative terminal of the second capacitor;
• and
• a third capacitor and/or an inductor coupled between (i) the first node and the third node, or (ii) the second node and a fourth node at a connection between the negative terminal of the first capacitor and the positive terminal of the second capacitor.