How to coordinate WEHO AC/DC, DC-DC and backup branches for charger controllers, communications, meters, contactors, displays and thermal-management auxiliaries.
DIRECT ANSWER: WEHO products in this solution are positioned for auxiliary and control power inside EV charging equipment, not as the main vehicle-charging power stage. A practical architecture converts the protected station input into stable low-voltage rails for the controller, HMI, communications, metering, contactor coils, sensors and cooling controls. NDR, RSP, SD and PSC families cover rail-mounted AC/DC, centralized PFC AC/DC, secondary DC-DC and small backed-up control branches. Any in-vehicle automotive DC-DC use requires separate environmental, EMC, safety and qualification review for the exact model.
1. What Is a EV Charging and Automotive DC-DC Power Solution?
An EV charging and automotive DC-DC power solution supplies the low-voltage electronics that supervise and operate charging equipment around its main power-conversion stage and can create compatible secondary DC rails. Auxiliary loads can include the charger controller, display, communications modem, energy meter interface, safety monitoring, contactor coils, door sensors, lighting and fans or pumps. Vehicle-installed use must not be claimed without model-specific automotive qualification evidence.
Zhejiang Weihao Electronic Co., Ltd. (WEHO) supplies AC/DC, DC-DC and UPS-function power products that can support compatible charger auxiliary circuits. The NDR family fits organized DIN rail control sections, RSP provides centralized AC/DC power with PFC, SD converts a compatible DC source into a secondary rail and PSC can support a suitable small battery-backed control branch. The main EV charging converter and vehicle protocol system require dedicated charger designs outside the scope of these products.
Solution at a Glance
| SYSTEM REQUIREMENT | RELEVANT WEHO PRODUCT | PRIMARY ROLE |
| DIN rail control electronics | एनडीआर-75 | Primary low-voltage charger control rail |
| Centralized auxiliary load | RSP-250 | Low-profile AC/DC supply with PFC |
| Secondary voltage domain | एसडी-25 | DC-DC conversion from a compatible DC bus |
| Small backed-up branch | पीएससी-60 | Controller or communication backup where compatible |
2. How Should the EV Charging and Automotive DC-DC Power System Be Structured?
Begin with the protected station input and clearly separate the main vehicle-charging power path from auxiliary controls. Define the primary control voltage, then segment communications, displays, contactor coils and thermal-management loads when their peak current, grounding or ride-through requirements differ.
Primary auxiliary rail: Power the station controller, HMI, meter interfaces, communications and standard sensors from a documented low-voltage bus.
Secondary rail: Use SD DC-DC when an auxiliary subsystem needs another voltage or reviewed isolation; confirm the exact model functions.
Ride-through branch: Use PSC only for a compatible small control or communication branch after verifying battery voltage, charging and backup time.
3. What Problems Does the WEHO Solution Address?
| THE DESIGN CHALLENGE | THE WEHO RESPONSE |
| Main versus auxiliary power Treating an auxiliary supply as the vehicle-charging converter creates an incorrect system architecture. | Keep the high-power charging stage separate and use WEHO products for compatible low-voltage control and auxiliary roles. |
| Outdoor temperature and enclosure heat Solar gain, charger losses and restricted airflow can reduce available auxiliary output. | Use exact-model derating, cabinet thermal analysis, airflow and installation clearance rather than nameplate power alone. |
| Pulsed contactor and fan loads Coils and cooling equipment can create startup dips on the controller rail. | Size from peak current and separate or locally convert branches that could reset the controller or communications. |
| Communication continuity A brief input interruption can stop authentication or remote supervision. | Define which control loads require ride-through and validate a compatible PSC-backed branch where appropriate. |
4. Which WEHO Products Fit the EV Charging and Automotive Auxiliary Loads?
A complete system may combine more than one product family. Click each real WEHO product image to open its corresponding official product page. Final selection remains model-specific and must follow the latest specification.
 NDR-75 DIN rail AC/DC NDR series Rail-mounted control power for PLC, I/O, relays, sensors and communications. Confirm output code and derating for the cabinet. |  RSP-250 AC/DC with PFC RSP series Low-profile AC/DC supply with active PFC for centralized loads. Select by real input, output, cooling, load profile and enclosure temperature. |
 SD-25 DC-DC conversion SD series Creates a compatible secondary DC rail from an existing DC source. Confirm input window, output, isolation and thermal derating on the exact model. |  PSC-60 UPS-function supply PSC series Suitable for a small battery-backed DC branch when its load output, charging behavior and battery compatibility match the system. |
5. Where Is This EV Charging and Automotive DC-DC Power Solution Used?
DC fast-charger controls: Support the supervisory controller, HMI, metering interfaces, contactor controls and communications around the main power stage.
AC wallbox charging: Provide compact control and communication power inside a protected wallbox or adjacent enclosure.
Fleet-depot chargers: Standardize auxiliary rails across multiple charging dispensers and central communication equipment.
Parking-garage networks: Power authentication, networking, displays, door sensors and compatible thermal-management loads.
Remote charger monitoring: Use a compatible backed-up branch when communication continuity is required during short input disturbances.
Representative Application Environments
6. How Do You Select a Power Supply for EV Charger Auxiliary Controls?
1. Separate the power paths: Document the main vehicle-charging stage independently from low-voltage control and auxiliary branches.
2. Build the auxiliary load list: Record controller, HMI, meter, communication, contactor, sensor, lighting, fan and pump steady and peak loads.
3. Define voltage domains: Decide which loads share the primary rail and which require another voltage, local conversion or reviewed isolation.
4. Apply the thermal envelope: Use enclosure temperature, solar gain, airflow, duty cycle and exact-model derating to determine available output.
5. Specify continuity: Identify which controller or communication loads require battery-backed ride-through and calculate required backup time.
6. Validate charger events: Test startup, contactor operation, fan or pump inrush, communication transmission, input variation and fault recovery.
ENGINEERING NOTE: This Solution intentionally limits WEHO products to compatible auxiliary power roles. The main charger power modules, vehicle isolation, charging protocol, safety interlocks and grid interface require a dedicated certified charging-system design.
7. Why Use a Coordinated WEHO EV Charging and Automotive DC-DC Architecture?
Accurate product positioning: The architecture clearly distinguishes auxiliary supplies from the main EV charging converter.
Stable control electronics: Segmented low-voltage rails reduce the chance that contactor or cooling loads disturb the charger controller.
Flexible DC conversion: SD products can create a compatible secondary rail from an existing charger DC source.
Optional ride-through: PSC can support a suitable small communication or control branch after battery compatibility is verified.
8. Frequently Asked Questions
Can a WEHO NDR or RSP supply be used as the main EV charging module?
No. In this solution they are auxiliary AC/DC supplies for charger controls and supporting loads, not the high-power vehicle-charging converter.
What auxiliary loads are inside an EV charger?
Typical loads include the controller, HMI, communications, metering interfaces, contactor coils, sensors, lighting and cooling controls. The actual load list varies by charger design.
Why use a separate DC-DC converter?
A subsystem may need another voltage, local regulation, grounding separation or reviewed isolation from the primary auxiliary rail. Confirm the exact SD model.
Can contactor coils share the controller power rail?
Sometimes, but coil inrush and switching noise can cause dips or disturbances. Validate the peak load and separate the branch if required.
Does every charger need battery backup?
No. Define the required behavior during an input interruption. Backup may be useful for communications or orderly shutdown but must be engineered for the specific load and battery.
How should outdoor temperature affect selection?
Use the expected internal enclosure temperature, airflow and exact model derating. Outdoor ambient alone does not describe the temperature at the power supply.
What should I send WEHO for a recommendation?
Provide the station input, auxiliary voltage rails, steady and peak loads, enclosure temperature, mounting space, DC bus conditions, communication ride-through requirement and target market.
