Control Engineer

Controls Engineer (Specialist)

sonnen US is hiring a Controls Engineer (Specialist) to own the control design of our residential and commercial battery inverters, from model to firmware. You will design, simulate and implement the control loops for every power stage in the inverter (DC/DC, DC/AC and auxiliary converters), using MATLAB/Simulink and Texas Instruments microcontrollers.

This is a hands-on specialist role. You will take control algorithms from analysis through code generation or hand-written embedded C, then validate them on HIL and real hardware in the lab.

Key responsibilities include:

• DC/DC control: Design current and voltage loops for bidirectional battery converters (buckboost, dual active bridge, LLC). Cover battery charge/discharge, DC-link regulation and mode transitions.
• DC/AC control: Design inverter control for single- and three-phase systems, both grid-tied (current control, PLL, active/reactive power) and off-grid (voltage control, droop, virtual impedance).
• Grid functions: Implement grid-support and protection features to meet IEEE 1547, UL 1741 SA/SB and utility rules. This includes ride-through, volt-var, frequency-watt and anti-islanding.
• System coordination: Define the supervisory state machine that sequences the power stages through start-up, grid/off-grid transfer, faults and shutdown. Cover parallel operation and backup mode.
• Modeling and design: Build plant models (averaged and switching) in MATLAB/Simulink and PLECS or Simscape. Do the loop design and tuning (PI, PR, state-space/LQR) with stability margins checked across operating points.
• Embedded implementation: Implement control on TI C2000 MCUs, by hand in C or through Embedded Coder with the C2000 support package. Use the CLA and dual-core partitioning to optimize performance.
• Verification: Verify every controller in three stages, each passed before the next: (1) Simulink simulation, model- and software-in-the-loop, across operating points and faults; (2) HIL, running the real C2000 firmware against a real-time plant model; (3) the real inverter in the power lab. Measure Bode plots, step response, THD and efficiency at each stage, and document results.
• Debugging and support: Root-cause field and lab issues from captured waveforms and firmware logs. Support certification testing and the transfer to production.
• Documentation and mentoring: Write control design specs and test reports. Review other engineers' designs and code, and mentor junior engineers on controls methods.

Required qualifications include:

• PhD or MSc in Electrical Engineering or a related field, specialized in control systems.
• Minimum of 4 years of proven experience designing digital control for power converters, with at least one inverter or DC/DC product shipped or brought to certification.
• Strong grounding in control theory: small-signal modeling, frequency-domain design, discretization, and digital control effects such as delay, sampling and quantization.
• Proven ability to verify controllers through the full chain: Simulink simulation first, then a HIL system, then the real power hardware, and to correlate results between the three stages.
• Hands-on experience with grid-connected inverter control: PLLs, current control in dq or stationary frames, and grid synchronization.
• Expert use of MATLAB/Simulink for modeling, loop design and simulation.
• Embedded C on TI C2000 MCUs (F2837x, F2838x, F28004x or similar), including interrupt-driven control loops, PWM/ADC configuration and fixed/floating-point trade-offs.
• Comfortable in a high-voltage power lab: oscilloscopes, differential and current probes, power analyzers, grid simulators and DC sources.
• Clear written and spoken English, and the ability to explain design decisions to firmware, hardware and certification teams.

Preferred qualifications include:

• Published work in power converter control.
• Model-based design with Embedded Coder and the C2000 Microcontroller Blockset, including code-generation tuning and processor-in-the-loop testing.
• Experience with the C2000 CLA, dual-core (CPU1/CPU2) or Concerto architectures, and interprocessor communication.
• Advanced control methods: LQR or state feedback, repetitive or resonant harmonic compensation, active damping of LCL filters, grid-forming control.
• Off-grid and microgrid operation: seamless transfer, parallel inverters, generator integration.
• Battery energy storage systems (BESS), including BMS interaction and state-of-charge-aware power control.
• HIL platforms (Typhoon HIL, OPAL-RT or dSPACE) and automated test scripting in Python.
• Working knowledge of IEEE 1547, UL 1741 and Rule 21 certification testing.
• CAN or Modbus communication with system controllers.

Tools and technologies include:

• Modeling and simulation: MATLAB, Simulink, Simscape Electrical, Control System Toolbox, PLECS
• Code generation: Embedded Coder, C2000 Microcontroller Blockset
• Microcontrollers: TI C2000: Delfino F2837xD, F2838xD, Piccolo/F28004x, Concerto F28M35x; CLA
• Embedded toolchain: Code Composer Studio, C2000Ware, digital power SDK, Git
• Test and validation: Typhoon HIL or similar, oscilloscopes, power analyzers, grid simulators
• Communication: CAN, Modbus, SCI/UART

Success in the first year includes:

• First 3 months: Learn the existing inverter platform and control architecture, and take ownership of one power stage's control loops.
• First 6 months: Deliver a validated control improvement or new feature (for example a grid-support function or improved transfer behavior) from Simulink model to tested firmware.
• First 12 months: Act as the technical owner for inverter control across DC/DC and DC/AC stages, and support a product through certification.

The role sits in the US power electronics development team in Atlanta and works closely with firmware, hardware, systems and test engineers.