Solid-State, High-Voltage Pulse Generator with Microcontroller Control

The development of a solid state high-voltage pulse generator for a spark-gap triggered Marx generator is discussed. The control board features a microcontroller to provide added flexibility and safety. A PIC16 microcontroller and two fiber-optic cables are critical to the design. Optically isolated serial communication between the device and a remote PC is used to control every aspect of the output pulses. This allows for more specific configuration of the pulser and provides remote adjustment of the pulse generator. The design uses the microcontroller's digital I/O pins and SPI/UART peripherals to send and receive operating data over fiber-optic, control the output pulse repetition rate, interface with a digital potentiometer to change the signal amplitude, and activate components that send optically isolated signals to disable/enable the high voltage power supply. In the case of microcontroller failure, the design includes a backup circuit that reconfigures the fiber-optic receiver to trigger an output pulse instead of interpreting UART communication signals. This permits the operator to still trigger the Marx generator remotely in a “single-shot” mode. The successful operation of this device involves configuring the PIC16 to send a 4 kV pulse at repetition rates up to 1 kHz. The flexibility provided by the microcontroller allows customization of several aspects of the output pulse, leaving the design useful in almost any application requiring high voltage pulses.