A system for simulating operation of an electrical device includes a printed circuit board assembly (PCBA) and a host machine. The PCBA includes a communications module, modular power switching modules (PSMs), and modular cells. Using an associated method, each PSM applies a predetermined pulse width modulation (PWM) duty cycle to AC input power to generate a calibrated DC output voltage. The cells, which are connected to a respective PSM, include a microcontroller. The host machine transmits a controller area network (CAN) cell state message to the communications module. The communications module converts the cell state messages into corresponding serial messages, and transmits the serial messages to the microprocessors of the cells to cause the cells to set their states to the desired simulation state. The cells generate the desired simulation state using PWM and transmit a cell status message back to the host machine via the communications module.