Principal Firmware Engineer - Power Conversion Control

Principal Firmware Engineer - Power Conversion Control

Please note that we are unable to provide visa sponsorship for this position.

Proper Voltage is unlocking the next generation of battery technology across robotics, data centers, and defense.

We're building intelligent battery systems that make advanced chemistries (sodium-ion, lithium-titanate, lithium-silicon) work in products that were never designed for them. Humanoid robots can upgrade power systems without redesigning their entire platform. Data centers get safer, cheaper backup power. Drones and autonomous vehicles get higher energy density without lengthy integration cycles.

If you want to work on hard engineering problems that matter this is the place.

Proper Voltage designs and builds safety-critical battery energy storage systems. This role owns the real-time control firmware for our bidirectional DC/DC power conversion stage — the code that closes current and voltage loops on multiphase interleaved converters, arbitrates operating modes, and commands a safe state when a fault occurs.

This is not a general embedded role that happens to touch PWM. You will be fluent in both the control theory and the silicon: able to derive a plant model and a discrete-time compensator, implement it within a sub-microsecond ISR budget with correct fixed-point scaling and correct ADC-to-PWM trigger phasing, then measure the resulting loop gain on the bench and explain why it does or does not match the model.

You will own our portable, MCU-agnostic DC/DC control library and its normative specifications, and become the primary technical authority on converter control firmware within the organization.

• Real-time control loop implementation for four-switch buck-boost power stages and successor topologies, including multiphase interleaved operation and phase current balancing.
• The portable DC/DC control library: compensator implementations, mode arbitration, scheduler and ISR architecture, and the platform abstraction layer.
• Converter protection firmware — cycle-by-cycle current limit, overvoltage and under voltage, thermal derating, gate-drive fault handling, and safe-state transitions.
• Control loop verification: model-to-measurement correlation, loop gain and stability margin characterization, transient response, and stability across the full operating envelope.
• Normative control specifications and the traceable verification evidence supporting UL 1973, UL 1998, and UL 9540 certification.

• Derive small-signal plant models for buck, boost, and four-switch buck-boost topologies, and design discrete-time compensators (PID, type II/III, 2p2z/3p3z) to meet bandwidth, phase margin, and gain margin targets.
• Implement control loops in C to fixed cycle budgets using fixed-point or single-precision arithmetic as appropriate, with explicit saturation, anti-windup, and bumpless mode transfer.
• Architect and maintain the control ISR and scheduler — fast control task and slower supervisory task — with deterministic timing, measured jitter, and documented worst-case execution time.
• Configure and validate the PWM, ADC, comparator, and DAC trigger architecture, including sampling instant placement relative to switching noise, trigger-to-response latency, dead-time, and hardware-independent cycle-by-cycle protection paths.
• Implement operating mode arbitration: constant current, constant voltage, constant power, current limit, soft-start, buck-to-boost transition, phase shedding, and charge/discharge direction reversal.
• Bring up new converter hardware in the lab, from first switching event through full envelope characterization, including gate-drive debug, dead-time optimization, and shoot-through avoidance.
• Measure and correlate loop gain by network analyzer injection, step-load transient response, ripple, efficiency, and thermal derating behavior.
• Build and maintain simulation and hardware-in-the-loop infrastructure sufficient to catch control regressions before hardware.
• Author and maintain specifications, requirements, and verification evidence to a standard that withstands certification-body review.
• Review control and embedded code written by others, and contribute to hardware design reviews covering the sense chain, ADC architecture, and protection paths.

• BS in Electrical Engineering, Computer Engineering, or equivalent demonstrated capability.
• Six or more years developing production embedded firmware in C for resource-constrained real-time systems.
• Direct, hands-on experience closing control loops in firmware on switched-mode power converters. You can name the topology, control mode, switching and sampling frequencies, compensator structure, and achieved crossover and phase margin for a converter you personally brought to validated hardware.
• Working command of discrete-time control: s-to-z mapping (bilinear/Tustin, zero-order hold), the effect of sampling and computational delay on phase margin, aliasing, and…