Note: The job is a remote job and is open to candidates in USA. Proper Voltage is developing intelligent battery energy storage systems for robotics, data centers, and defense. The company is seeking a Principal Firmware Engineer to own real-time control firmware for bidirectional DC/DC power conversion, including control loops, converter protection, verification, and certification evidence.
Responsibilities
- 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
Skills
- 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 quantization
- Fluency with the peripherals that make digital power work: high-resolution PWM, PWM-triggered ADC with programmable sample instants, analog comparators and DACs for fast fault paths, and DMA
- Fixed-point arithmetic competence — Q-format scaling, range and overflow analysis, saturating behavior — and the ability to justify a fixed-point versus floating-point decision on execution-time grounds
- Deterministic ISR design under hard timing constraints, including the ability to measure and defend worst-case execution time rather than estimate it
- Independent lab capability with oscilloscopes, isolated and differential probes, current probes, electronic loads, bidirectional supplies, and a network or frequency response analyzer for loop gain measurement
- Version control, code review, and a demonstrated track record of writing specifications and test evidence, not only
- * ****dsPIC experience (significant advantage)****
- Production firmware on dsPIC33C, dsPIC33CK, or dsPIC33CH digital signal controllers for power conversion, including high-resolution PWM generators with PCI-based synchronization, dedicated and shared ADC core configuration, early interrupt generation, alternate working register sets, DSP MAC instruction use in compensator inner loops, and MPLAB X / XC16 toolchain depth
- Familiarity with Microchip's digital power reference ecosystem — Digital Power Development Board, Digital Power Plug-In Modules, and the PowerSmart Digital Control Library Designer
- Bidirectional and multiphase interleaved converter control, including current sharing and phase balancing between paralleled phases
- Average current mode control implementation specifically, as distinct from voltage mode or peak current mode
- Wide-bandgap power stages (GaN, SiC) and the firmware-visible consequences of fast switching edges — sense chain noise, blanking, dead-time sensitivity, and gate-drive fault behavior
- ARM Cortex-M devices with advanced timer peripherals in addition to dsPIC; we value portability across both architectures
- Battery energy storage, EV charging, photovoltaic inverter, or grid-interactive converter experience, including charge profile management and BMS interaction such as current limit negotiation, precharge, and contactor sequencing
- Functional safety and certification exposure: IEC 61508 or ISO 26262 concepts, UL 1973, UL 1998, UL 9540, FMEA/FMEDA, and software safety requirements traceability
- MISRA C, static analysis, on-target unit testing, and hardware- or processor-in-the-loop infrastructure
- Modeling and simulation in SPICE/LTspice, PLECS, or MATLAB/Simulink, with the ability to build the model rather than only run an existing one
- CAN and CANopen, and firmware update over an embedded bus
- Contributions to reusable, portable control libraries with clean hardware abstraction, as opposed to one-off application firmware
Benefits
- Equity options as part of the compensation package.
- Comprehensive healthcare benefits (medical, dental, vision).
- Generous paid time off and paid holidays (PTO) policy.
Company Overview