Motor drive topologies for traction and charging in electrified vehicles
A motor drive system for an electrified vehicle includes a DC source, such as a battery, and an inverter, which includes one or more phase drivers, each configured to switch current from the DC source to generate AC power upon one or more output terminals using a hybrid of two or more different solid-state switches, each having a corresponding voltage rating. A nine-switch inverter includes three phase drivers, each including high, low, and middle solid-state switches, with Si-MOSFET high and low switches having a first voltage rating of half of the rated voltage of the system, and with Gallium Nitride (GaN) transistors rated to block a full rated voltage of the system used for the middle switches. A delay driver synchronizes timing between two different solid-state switches by energizing control terminals at different rates. The inverter can be operated using near-state pulse-width modulation (NSPWM) to reduce switching losses.
1. An inverter for converting between DC and AC power, comprising:
a DC link bus including a high-side conductor and a low-side conductor;
a phase driver configured to switch current from the DC link bus to generate the AC power upon an output terminal;
wherein the output terminal is one of a plurality of output terminals including a first output terminal and a second output terminal;
wherein the phase driver includes:
a high switch configured to selectively conduct current between the high-side conductor and the first output terminal;
a low switch configured to selectively conduct current between the low-side conductor and the second output terminal; and
a middle switch configured to selectively conduct current between the first output terminal and the second output terminal; and
wherein at least one of the high switch, the low switch, and the middle switch has a first voltage rating, and at least one of the high switch, the low switch, and the middle switch has a second voltage rating higher than the first voltage rating, and
wherein the phase driver is one of three phase drivers; and wherein each of the three phase drivers is controlled to generate an output voltage vector upon the output terminal using a near state pulse-width modulation (NSPWM) control method.
2. The inverter of claim 1 , wherein the middle switch has the first voltage rating, and wherein the high switch or the low switch has the second voltage rating higher than the first voltage rating.
3. The inverter of claim 1 , wherein the at least one of the high switch, the low switch, and the middle switch having the second voltage rating includes a wide-bandgap (WBG) device having a bandgap greater than 2.0 electron-volts (eV).
4. The inverter of claim 1 , wherein the at least one of the high switch, the low switch, and the middle switch having the first voltage rating includes one of an insulated gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET).
5. The inverter of claim 1 , wherein the at least one of the high switch, the low switch, and the middle switch having the first voltage rating includes a silicon metal-oxide-semiconductor field-effect transistor (Si-MOSFET), and wherein the first voltage rating is less than 400 volts.