One of NEC Electronics’ most recent developments is the V850E/Ix3™ line of six microcontrollers, which operate at 64 MHz, execute 86 Dhrystone MIPS and have two identical dedicated 3-phase inverter control functions able to drive two independent sinusoidal vector drives simultaneously. The new V850E/Ix3 microcontrollers provide a complete solution for a range of  advanced 3-phase inverter control applications.

At the heart of the system, the 16-bit inverter timer is an up/down
6 counter with four double-buffered compare registers, one for the
PWM carrier cycle and the rest for three waveforms with independent duty cycles. A variable dead-time interval can be inserted to prevent accidental shoot-through of the power transistors and the interrupts generated at the half-way point in the PWM cycle.

In vector control, precise current measurements must be performed within every PWM cycle. The V850E/IG3 microcontroller’s two high-speed 12-bit A/D circuits with independent sample and hold have multiple sources for triggering including the inverter timer. Two doublebuffered compare registers can be employed to produce A/D triggering at any two points within the PWM cycle. The A/D circuit is equipped with five double-buffered conversion result registers. In scan mode, five measurements can be performed within one PWM cycle and all measurements stored in separate buffers.

One of the more unique features of this microcontroller is the analog front end of embedded op amps and analog comparators. For motor safety, two sets of analog comparators are used to monitor A/D input voltage against two variable thresholds that can be set on the microcontroller pins and also to produce a total hardware shutdown if non-safe operating conditions are detected. All this in addition to standard safety functions such as Low VoltageInterrupt (LVI), Power on Clear (POC) and watchdog timer.