1、 Product Overview
The bus high-voltage defroster is a specialized front windshield defogging and defrosting equipment for pure electric/hybrid/fuel cell buses. The core adopts high-voltage PTC ceramic positive temperature coefficient heating elements, matched with the bus 400V/600V/800V power battery high-voltage DC platform, equipped with 24V low-voltage control, independent blower, air duct, high-voltage safety circuit and CAN communication control module. It is a standard core component for winter thermal management and driving vision safety of new energy buses.
Two mainstream structural types
Dry direct heating type (independent air PTC defroster)
Directly heated air, independent box, built-in fan, no water pipeline, mostly used for 6-8 meter minibuses and front buses, with a power of 3-12kW;
Integrated water and heating system (water-cooled high-pressure PTC defrosting)
High voltage PTC heating antifreeze, which exchanges heat with the warm air tank to produce hot air, can be linked to battery preheating and vehicle heating. It is mainly used for buses over 10 meters and buses in high-altitude areas, with a power of 10-30 kW.
2、 Working principle
1. Principle of dry direct heating high-pressure defrosting (most commonly used)
High voltage power supply: The vehicle’s power battery outputs 400-800V DC power, which is connected to the PTC heating element. The 24V low-voltage control line and CAN bus receive defrosting commands from the air conditioning panel/VCU;
PTC self limiting temperature heating: Barium titanate ceramic semiconductor has extremely low resistance at low temperatures and rapidly heats up when powered on; When the temperature rises to the set Curie point (100-120 ℃), the resistance index skyrockets, automatically reducing the heating power. It can maintain a constant temperature and prevent dry burning without the need for an additional temperature control valve;
Airflow heat transfer: Equipped with a high-power centrifugal/cross flow fan to draw in fresh air from inside/outside the vehicle, it flows at high speed through PTC aluminum fin heat dissipation body, and the air is quickly heated;
Directional defrosting air supply: Hot air is evenly blown towards the inside of the front windshield through a dedicated air duct, melting frost and evaporating water mist;
Multiple safety loops: built-in temperature sensor, high voltage interlock HVIL, overcurrent/overvoltage/overheating protection, automatic cut-off of high voltage heating when the fan stops, to prevent dry burning and fire; The fault signal is uploaded to the instrument alarm through CAN.
2. Principle of water heated high-pressure defrosting cycle
High voltage PTC heater heats the whole vehicle’s ethylene glycol antifreeze to 60-85 ℃;
The electronic water pump drives the circulation of hot water to the defrosting and warm air tank in the driving area;
The fan blows through the water tank to exchange heat and form hot air, which is then blown towards the front windshield to complete defrosting;
After cooling, the antifreeze flows back to the PTC for reheating, and the cycle continues to heat up, which can synchronously preheat the power battery at low temperatures.
3、 Core functions
1. Basic security functions (mandatory regulatory requirements)
Quick defrosting: In a low-temperature environment of -20 ℃, high-temperature hot air is generated for 30 seconds, and more than 80% of the frost in the front gear is cleared within 20 minutes, meeting the ECE R43 passenger car safety standards;
All day defogging and dehumidification: automatically blowing hot air to eliminate fog on the interior windows and eliminate blurred vision during rainy days and large temperature differences; It can introduce external circulation dry fresh air to reduce the humidity inside the car and provide long-term anti fog.
2. Vehicle heating assistance
Independent heating for the driver’s area. Some integrated models support the switch of air duct in three modes of foot blowing, face blowing and defrosting, giving consideration to driver heating and defrosting;
The water heater model is linked to the vehicle’s heating system, taking into account the output of warm air in the passenger area.
3. Intelligent electronic control function
The CAN bus interacts with the vehicle’s VCU and air conditioning controller, dynamically adjusting the heating power according to environmental temperature and glass humidity levels (with multiple adjustable power levels);
Automatic protection logic: In case of fan failure shutdown, overheating, high voltage leakage, or insulation failure, immediately cut off high voltage and instrument alarm;
High and low temperature adaptive: Low temperature full power output, automatic power reduction and constant temperature after reaching room temperature standards, reducing power consumption.
4. Expanded functions (exclusive to plumbing models)
Low temperature preheating of power battery: Preheat the battery coolant in a sub zero environment to raise the battery to the optimal working range of 20-30 ℃, avoiding range diving and limited charging;
Waste heat recovery: Recovering waste heat from motors and electronic controls to assist in heating and reduce energy consumption of high-voltage PTC.
Post time: Jul-01-2026
