Is the ptc heater a new heating method for hybrid and electric vehicles?
In hybrid vehicles and electric vehicles, the engine must frequently operate in a high-efficiency zone. When the engine cannot be used as a heat source under pure electric drive, the vehicle will have no heat source. Especially for the temperature regulation of the cab, an additional heat source is required to ensure comfort and safety. To maximize electric driving range and improve fuel efficiency, heat needs to be generated quickly, efficiently and safely with minimal drain on the traction battery. Webasto has developed a new high voltage heater based on a new patented thermolayer technology. The design concept and research and development results to achieve the goal of the project are introduced.
1. Function and purpose of vehicle heating
Cab heating is an important function to ensure safe and comfortable driving of the vehicle. In addition to the comfort of the cabin and the temperature in the car, the air conditioning system (HVAC) must also ensure certain functions including compliance with regulatory requirements, such as according to European Regulation 672/2010 and the US Federal Motor Vehicle Safety Standard FMVSS103, More than 80% of the ice on the windshield must be removed after 20 minutes. Defrost and dehumidification are 2 other functions required by regulations. Good climate control of the cab is the basis for comfort and safety, which is also an important factor to ensure unaffected driving.
2. Performance
The main requirements for the heater depend on the application of the car, and can be summarized as follows: (1) Highest efficiency; (2) Low or reasonable cost; (3) Fast response time and good controllability; (4) Package size Minimized and light as possible; (5) good reliability; (6) good sustainability and environmental protection.
3. Heating concept
In general, heat concepts can be divided into primary heat sources and secondary heat sources. The main heat source is a heat source that can generate more than 2kW of heat required for temperature adjustment of the cab. The heat generated by the secondary heat source is under 2kW and usually directs its heat to a specific location, such as a seat heater.
3.1 Air heaters and water heating systems
Heating systems can be divided into 2 main categories, depending on whether the heating is achieved by a fuel-based heater or an electric heater: (1) air heaters that heat the air directly, which heats the cab quickly; (2) use cooling A water heater with liquid as a medium heat carrier, which distributes heat better and is integrated in HVAC.
Fuel-fired heaters have been introduced in hybrid and electric vehicles in the past, and their lower electrical consumption allows the electricity to be used to drive the vehicle instead of heating it. Because using an electric heater in winter reduces the range of an electric drive by about 50%, fuel heating is often the method of choice.
However, the need for emission-free vehicle systems necessitates the search for other heating solutions, of which the electric heater concept is a viable solution.
3.2 Electric heater concept
Several existing and potential technologies, such as wirewound resistance or positive temperature coefficient (PTC) heating, were analyzed before development. Four main development goals were evaluated, and several potential technologies were compared against these goals:
(1) In terms of efficiency, the new heater must be efficient and it should be able to provide the required heat output over a wide range of coolant temperatures and at all voltages;
(2) In terms of quality and size, the new heater must be as small as possible and as light as possible;
(3) In terms of usability and cost, the use of rare earth materials and Pb must be avoided, and at the same time, the cost of new products must be competitive;
(4) In terms of safety, any electric shock hazard or burn accident must be prevented under all conditions.
