Efficient heating solutions for more battery power and increased comfort in hybrid and electric vehicles
By Jurgen Dunsch, Senior Business Development Manager HV Coolant Heaters, BorgWarner Emissions Systems in Ludwigsburg
BorgWarner’s efficient high- and low-voltage heating solutions for hybrid and electric vehicles represent the state of the art in terms of comfort and safety and meet the high demands of the automotive industry.
The current trend towards electrification is bringing changes with it: the heat management of modern passenger cars is increasingly being decoupled from the internal combustion engine, and assistance from auxiliary heating systems is required. To allow pure electric driving for hybrid and electric vehicles, solutions that compensate for the lack of heating performance are necessary, especially in winter. These have to work without usable exhaust heat – temporarily in hybrid cars and permanently in electric cars – as well as being energy-efficient so as not to have a negative effect on consumption, range and acceleration.
With regard to future-proof heating concepts, BorgWarner’s innovative heat management solutions provide a response to the increasing demand of automotive manufacturers. The company’s Cabin Heater family includes the High-Voltage Coolant Heater (HVCH) and the High- and Low-Voltage Air Heater. The former is also part of BorgWarner’s Battery Heater family. In addition to increased battery-operated ranges, these achieve a pleasant climate in the passenger compartment within an extremely short time, even at low outside temperatures.
The High-Voltage Coolant Heater
BorgWarner’s HVCH is available in power variants from 3 to 10 kW and replaces the internal combustion engine as a source of heat for battery and cabin heat management systems in electric cars. By assisting battery conditioning, it improves the service life and increases the range of the vehicle. In addition, the low thermal mass of this innovative technology allows rapid reaction times for heating up and cooling down, leading to a permanent homogenoustemperature distribution between the battery packs and cells.
Durable Thick Film Heating Elements (TFE) are at the heart of the HVCH – here a stainless steel substrate carries the dielectric layers and the heating resistors. The technology, which BorgWarner offers in “singleplate” and “dual-plate” versions, also allows integrated hot plate temperature measurement. Both versions are integrated into a robust aluminum die-cast housing and display a high power density at the TFE. In addition, the design has a high resistance to thermal shock as well as vibrations, oscillations and mechanical stresses. The crucial advantage of the compact “dual-plate” system is that it has two hot plates allowing it to offer up to 80 percent more heat transfer area.
Moreover, the heating packages are covered with coolant and only cause minimum heat losses –leading to a higher efficiency –and the three-part aluminum housing provides excellent electromagnetic shielding.
BorgWarner has also developed a safety strategy for its intelligent solution and its robust power electronics which ensures the prevention of thermal events such as overheating. As soon as the system detects an error, it switches off automatically.
The High-and Low-Voltage Air Heater
BorgWarner offers the Air Heater with ist weight of 3.24 kg as an easy-to-integrate “plug & play” modular solution and uses it in hybrid and electric vehicles with up to 450 V. By rapidly heating up the air flow coming from the fan, the device with its power of up to 7 kW provides the required temperatures in an extremely short time.
Thanks to its low weight and its compact design, the Air Heater is the ideal solution for modern lightweight construction concepts. In addition, the completely enclosed heating element provides maximum protection against high voltages. In conjunction with the fin design of the Air Heater, the heating element ensures low pressure losses of less than 37 Pa (at 400 m3/h), and this in turn allows the fan to work at lower speeds and reduces the noise level in the passenger compartment.
The two-zone functionality (Fig. 3) of the Air Heater allows the precise individual Regulation of the air flow for driver and passengers – the heat distribution is controlled depending on the demand, and energy losses are avoided. The Air Heater has Protection Class IP67 and is controlled via a high-power CAN (Controller Area Network) bus.
PTC components (temperature-sensitive nonlinear resistors with a positive temperature coefficient) are the technological components at the heart of the Air Heater. Whereas they operate reliably, provide high heating power, display a low electrical resistance and allow a high electricity flow at low surface temperatures, the effect is reversed as temperatures increase. The electricity flow is then reduced by the rising resistance of the ceramic stones and the system releases less heat – in other words, it regulates itself and prevents overheating.
When the usable exhaust heat of the internal combustion engine is limited or missing completely, it is a challenge to heat up the passenger compartment. As a result of the progressive electrification of the powertrain, electric heaters will soon be indispensable. With its advanced high-voltage auxiliary heater systems, BorgWarner not only offers vehicle manufacturers around the globe an intelligent solution for higher battery-operated ranges, but also a safe air-conditioned passenger compartment in hybrid and electric vehicles which is comfortable at all times.
OEM&Supplier, Edition 2/2018