Design and implement digital control loops (voltage, current, PLL, droop, etc.) for the rectifier, inverter, and DC/DC stages of Online UPS systems.
Develop and tune control algorithms such as PI/PID, state feedback, repetitive control, and feedforward compensation for power conversion topologies.
Implement high-frequency PWM/SVPWM generation, ADC sampling, and interrupt-driven real-time control on DSP/MCU platforms.
Develop firmware for full UPS operating modes — online (double-conversion), eco, battery, and bypass — including seamless mode transitions.
Implement battery charger control (CC/CV charging, charge/discharge management) and coordinate with the BMS for safe battery operation.
Optimize control performance for transient response, output THD, efficiency, and stability across line and load conditions.
Design firmware-level protection and fault-handling logic (OV/UV/OC/OTP, short-circuit, inrush, output overload).
Perform bring-up, debugging, and waveform analysis using oscilloscopes, current probes, and emulators.
Collaborate with power hardware, magnetics, and system engineers to co-tune control loops with the physical plant.
Support compliance testing (efficiency, THD, hold-up time, EMI) and resolve firmware-related issues.

Bachelor's or Master's degree in Electrical Engineering, Power Electronics, Control Engineering, or a related field.
7+ years of firmware development experience focused on digital power conversion.
Proven track record of shipping Online UPS firmware — hands-on experience with rectifier, inverter, and bypass control is essential.
Strong hands-on experience implementing digital control loops for switching power converters (PFC, inverter, bidirectional DC/DC, LLC, phase-shift full-bridge, etc.).
Deep understanding of Power Factor Correction techniques — average current mode control, bridgeless / totem-pole PFC, interleaved PFC.
Working knowledge of battery charge/discharge control, including CC/CV charging profiles, charger-to-BMS coordination, and battery protection.
Proficiency with real-time control DSPs/MCUs (e.g., TI C2000, STM32 G4/H7, Infineon XMC, or equivalent); strong understanding of ePWM, ADC, and trip-zone style peripherals.
Strong grasp of control theory: s-domain / z-domain analysis, Bode plot tuning, discretization (Tustin, ZOH), and loop compensation.
Proficient in C/C++ and real-time, interrupt-driven embedded programming.
Experience working with power stage waveforms and debugging closed-loop control issues on real hardware.

Experience with 3-phase UPS, parallel/redundant UPS operation, or modular UPS architectures.
Familiarity with MATLAB/Simulink, PLECS, or PSIM for control modeling and offline simulation; experience with model-based design or auto-code generation is a plus.
Knowledge of advanced techniques such as digital PLL for grid synchronization, resonant control, or model predictive control (MPC).
Experience addressing EMI/EMC issues through firmware (e.g., switching pattern shaping, spread spectrum).
Familiarity with UPS-relevant safety and regulatory standards (IEC 62040, UL 1778, IEC 61000, etc.).
Experience with version control (Git) and firmware architecture design for safety-critical, real-time systems.
Ability to read power electronics schematics and collaborate closely with hardware engineers on loop tuning and stability.

Ubiquiti Inc. is hiring a Firmware Engineer (Power Tech)