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Specialised engineering

Power Electronics Design: BMS, DC-DC, EV Charging and Motor Control

Power electronics for battery-powered and high-voltage products: battery management systems, isolated and non-isolated DC-DC converters with GaN or SiC switches, 48 V and 800 V architectures, EV charging electronics and motor drives. We design the power stage, magnetics, protection and control firmware together, and prepare the product for safety and EMC testing.

Quick answer

What we build
Battery management systems, GaN and SiC DC-DC converters, 48 V and 800 V power stages, EV charging electronics and motor drives, covering the hardware, magnetics and control firmware.
Who it is for
EV, energy-storage, robotics and industrial companies, and power-module makers, that need a power stage, BMS or motor controller designed, or an existing design fixed.
Typical timeline
Scoped per project. The proposal sets the milestone plan after a requirements review
Typical cost
Quoted per project as a fixed-scope proposal. For typical ranges, see our hardware development cost benchmarks.
Designed to
IEC 61851-1 and -23 for EV charging (AIS-138 / IS 17017 in India), ISO 15118 and OCPP for charger communication, ISO 6469 and ISO 26262 for vehicles, IEC 62619, AIS-156 (L-category) and AIS-038 Rev 2 (M- and N-category) for batteries, UN 38.3 for battery transport, IEC 62368-1 for power supplies and IEC 61000 for EMC, as the product requires.

Every project is quoted as a fixed-scope proposal within 3–5 business days of a discovery call. Discuss your product

Capabilities

What power electronics do we design?

Battery management systems

BMS hardware and firmware: cell monitoring and balancing, state-of-charge and state-of-health estimation, hardware protection and CAN communication for Li-ion NMC and LFP packs.

DC-DC converters

Isolated and non-isolated converters, from point-of-load stages to 800 V to 48 V intermediate bus converters, using GaN, SiC or silicon switches.

48 V and 800 V architectures

Insulation coordination, pre-charge and discharge circuits, isolated sensing and insulation monitoring for high-voltage battery and bus systems.

EV charging electronics

On-board chargers with power-factor correction, AC charging-station control, DC and bidirectional power stages, and ISO 15118 vehicle-to-charger communication.

Motor drives

BLDC and PMSM inverters and drivers with field-oriented control firmware, for robotic actuators, e-mobility and industrial drives.

Energy storage and solar

Battery management and control electronics for energy-storage systems, and MPPT charge controllers for solar and energy-harvesting products.

Battery management

What does a BMS design project include?

A BMS protects the pack and reports its state. We design the hardware and firmware together, because protection, balancing and state estimation each depend on both.

Cell monitoring and balancing
Cell-voltage and temperature measurement with a dedicated monitoring IC (for example TI BQ769x2, Analog Devices ADBMS/LTC681x or NXP MC33771, chosen for the cell count and chemistry), passive or active balancing, and pack current sensing by shunt or Hall sensor.
Protection that does not depend on the microcontroller
Hardware overcurrent, short-circuit, over- and undervoltage and overtemperature cut-offs that act independently of the MCU, with MOSFET or contactor disconnect, pre-charge and, for high-voltage packs, isolation monitoring.
State estimation
State of charge from coulomb counting corrected by voltage-based estimation, and state-of-health tracking over the life of the pack, for Li-ion NMC and LFP chemistries.
Communication and integration
CAN or CAN FD to the vehicle or system controller, logging and diagnostics, firmware updates and, for traction packs, the functional-safety analysis the vehicle programme requires.

DC-DC conversion

How do you design a DC-DC converter with GaN or SiC?

Converter work starts from the electrical and thermal requirements: input range, output, power, isolation, efficiency and temperature. These are recorded as design targets and compared with measured results on the prototype.

Topology
Non-isolated buck, boost and multiphase stages; isolated LLC resonant, phase-shifted full-bridge and dual-active-bridge stages for bidirectional power flow. The choice follows the voltage ratio, power level, isolation requirement and efficiency target.
GaN, SiC or silicon
GaN transistors suit high switching frequencies and power density at lower voltages, such as 48 V stages. SiC MOSFETs suit high-voltage stages, such as an 800 V input. Silicon stays the lower-cost choice where frequency and efficiency targets allow. Gate drive, dead time and layout follow the device chosen.
Magnetics, layout and thermal design
Transformer and inductor design, low power-loop inductance in the PCB layout, creepage and clearance for the working voltage, and a thermal path from the switches and magnetics to the heatsink or baseplate.
Control and protection
Analog or digital control (for example on a TI C2000 or STM32G4 microcontroller), loop compensation, soft start, current limiting and input and output protection, with telemetry to the host system where needed.

48 V and 800 V

What changes between 48 V and 800 V designs?

The voltage class sets the safety architecture before any component is chosen.

48 V systems
A 48 V bus can stay within the 60 V DC limit for voltage class A (ISO 6469-3) and ES1 (IEC 62368-1) only if the pack's full-charge and transient voltage stays below 60 V: 14S NMC reaches 58.8 V and 16S LFP 58.4 V, but a 15S NMC pack reaches 63 V at full charge and exceeds it, so it needs the insulation and touch protection of the higher voltage class. Currents are high, so busbar and connector ratings, current sensing and thermal design dominate the design.
400 V and 800 V systems
Reinforced insulation, creepage and clearance to IEC 60664-1, isolated gate drivers and isolated sensing across the barrier, pre-charge, discharge and interlock circuits, and insulation-resistance monitoring.
800 V to 48 V conversion
Isolated intermediate bus converters that step an 800 V DC bus down to 48 V or 54 V for electronic loads, with SiC switches on the high-voltage side and GaN or silicon on the low-voltage side where the design calls for it.
Safety and EMC evidence
Design documentation and test plans for dielectric-strength (hi-pot), insulation-resistance, safety and EMC testing at an accredited laboratory; for lithium packs, UN 38.3 transport testing and, in India, AIS-156 (L-category) or AIS-038 Rev 2 (M- and N-category) battery safety requirements.

EV charging

What EV charging electronics do you design?

On-board chargers
AC-DC on-board chargers with power-factor correction and an isolated DC-DC stage, sized to the vehicle's battery voltage and charging power.
AC charging stations
Charging-station control electronics: control-pilot signalling to SAE J1772 and IEC 61851-1 (AIS-138 and IS 17017 for the Indian market), contactor control, thermal management and load balancing across charge points.
DC and bidirectional charging
Power-conversion and control electronics for DC chargers designed to IEC 61851-23 (with IEC 61851-24 charger-to-vehicle communication; AIS-138 and IS 17017 in India), and bidirectional stages for vehicle-to-grid (V2G) operation, with ISO 15118 communication for Plug & Charge.
Connected chargers
OCPP connection to the charge-point management system, remote diagnostics and OTA firmware updates, built with our firmware and cloud teams.

Motor control

What does a motor-control project include?

Motor control combines a power stage, current and position sensing, and real-time firmware.

Power stage
Three-phase inverter or H-bridge stages with gate drivers, shunt or Hall current sensing and fault protection, sized to the motor and supply voltage.
Control firmware
Field-oriented control (FOC) for BLDC and PMSM motors, six-step commutation where it is enough, and speed and position loops using Hall sensors, incremental encoders or sensorless estimation, on microcontrollers with motor-control timers such as the STM32G4.
Robotic actuators
Compact multi-axis drivers for coreless and brushless micro-motors with high-resolution encoders, for dexterous hands, grippers and prosthetics.
Fault handling and EMC
Overcurrent, stall and overtemperature handling, and layout and filtering to control conducted and radiated emissions from the switching stage.

Process

How we work

  1. Requirements and safety targets

    Agree the electrical, thermal, safety and regulatory requirements; efficiency, power-density and temperature figures are recorded as design targets.

    Deliverable: Requirements and design-target sheet

  2. Architecture and simulation

    Select the topology, switching devices and control approach; estimate losses and temperatures; simulate the power stage and control loop.

    Deliverable: Architecture, loss budget and simulation results

  3. Schematic, magnetics and layout

    Schematic, magnetics design and a PCB layout with low loop inductance, creepage and clearance for the working voltage, and a defined thermal path.

    Deliverable: Schematic, layout, magnetics specifications and BOM

  4. Prototype and characterisation

    Bring-up at reduced voltage first, then efficiency, thermal, transient and protection tests, reported as measured values against the design targets.

    Deliverable: Characterisation report with measured results

  5. Compliance preparation and handoff

    EMC pre-compliance, safety and EMC test plans for the accredited laboratory, and the manufacturing release package.

    Deliverable: Test plans, compliance documentation and release package

Planning

Scope and cost

Start with a non-confidential summary of your product and the milestone you need to reach next.

Planning guides

Power Electronics Development Guide

BMS, GaN/SiC DC-DC for 48 V to 800 V, EV chargers (IEC 61851, OCPP) and motor control: stages, test equipment, standards, costs and timelines.

Plan a power electronics project

Background reading on the standards, devices and industries this work usually involves.

FAQ

Frequently asked questions

Working with Rapid Circuitry

How much does a project cost, and how is pricing structured?

Each project is quoted as a fixed-scope proposal: a statement of work with milestones, deliverables and pricing, sent within 3–5 business days of the discovery call. The price depends on the requirements, how mature the design is, technical complexity, the number of prototype iterations and the validation scope. Longer engagements can also run as a retainer or a hybrid of both. For budgeting before you contact us, our hardware development cost benchmarks and the PCB design, firmware and IoT cost guides give indicative ranges with their assumptions stated. They are planning ranges, not quotes.

How long does a project take?

It depends on the scope and on what already exists when we start. As planning ranges from our cost benchmarks: a single PCB layout takes 2–6 weeks per board and embedded firmware 4–16 weeks. A connected (IoT) product takes 3–12 months from concept to a production-ready design, and a regulated medical device 12–24 months to a 510(k) submission-ready package; from idea to mass production, a typical connected product takes 9–18 months. The proposal sets out a dated milestone plan, and you receive weekly progress updates during the project.

Who owns the intellectual property?

You do. Our contracts assign the intellectual property in the project work product (schematics, PCB design files, firmware source code and documentation) to you on payment, and we hand over the source files, not only fabrication outputs or compiled binaries. The exact terms are set out in the signed agreement for each engagement.

Do you sign NDAs?

Yes. We sign a mutual NDA before any technical discussion of your project. Send your standard NDA or use ours; we return it signed within one business day.

Can you work with clients in the US, Europe and Japan?

Yes. We are based in Hyderabad, India, and work with product teams in India, the United States, the United Kingdom, Germany, Japan, Australia, the Middle East and other markets. Our office hours are 10:30–19:00 India Standard Time (UTC+5:30), Monday to Saturday, and we schedule design reviews across time zones, typically from US Pacific to Central European time. Japan is 3.5 hours ahead of India, so our first four hours overlap the Japanese afternoon. Prototypes and documentation ship by international courier such as DHL or FedEx. Our hardware outsourcing guide covers what to agree before an international project starts.

Do you hand off to manufacturing, and which contract manufacturers do you work with?

Yes. We prepare the manufacturing release package — fabrication and assembly drawings, the BOM with approved manufacturers, programming files and test specifications — and hand it over to the contract manufacturer (EMS) you choose. If you have not chosen one, we help you evaluate candidates through technical capability assessments and a pilot build. See manufacturing support.

Are you ISO 9001 or ISO 13485 certified?

No. Rapid Circuitry does not hold ISO 9001, ISO 13485 or other certificates. Our processes are aligned with ISO 9001:2015, and we design products to the requirements of the standards that apply to them — for example IEC 60601-1 and IEC 62304 for medical devices (with design documentation structured so your ISO 13485 quality system can absorb it) and IEC 61000 for EMC — and we specify IPC-A-610 workmanship classes for assembly. We prepare the product and its documentation for certification testing at accredited laboratories; the certificate or approval is issued for your product by the laboratory, notified body or regulator.

What do you need from me to start?

A short, non-confidential description of the product and what it must do (sensors, connectivity, on-device processing), the target production volume and unit cost, the markets and regulations it must meet (for example FDA, CE or FCC), your timeline, and what already exists: a concept, a proof of concept, schematics, PCB files or firmware. After the NDA, the next step is a 30-minute discovery call with the engineers who would work on the project, followed by the fixed-scope proposal. Send a project brief to begin.

Explore

Electronics design

Precision analog, mixed-signal and power circuits: sensor front ends, power supplies and battery management.

Firmware development

Embedded C/C++ firmware on bare metal, an RTOS or embedded Linux: drivers, bring-up, secure boot and OTA updates.

Connected vehicles

Telematics control units, V2X modules, in-vehicle networking and secure OTA for connected vehicles.