With the global energy crisis and environmental pollution becoming more and more serious, new energy vehicles have become the development trend of automobile industry. As a key electronic component, thin film capacitors play a vital role in new energy vehicles.
Thin film capacitor is a capacitor with metal foil as electrode and plastic film such as polyethylene, polypropylene, polystyrene or polycarbonate as dielectric. Thin film capacitors with different dielectric materials have different characteristics. Thin film capacitor has the characteristics of nonpolarity, small dielectric loss, long life, high frequency and excellent temperature characteristics. With the expansion of high-frequency and high-current application scenarios, the share of PP (polypropylene) thin film capacitors with excellent high-frequency characteristics continues to increase.
The working principle of thin film capacitor is based on the action of electric field. When the thin film capacitor is in working state, a voltage is applied between its two electrode plates (usually metal foil), so that an electric field is formed in the thin film material between them. When a voltage is applied between the two plates of a capacitor, an electric field will be formed in a dielectric (such as polyester film, polyimide film, etc.). These dielectric materials can form an electric field between electrons under certain conditions, so that charges can be stored between the two electrodes. Electrons will transfer from one electrode to the other, thus storing charge inside the capacitor. In addition, when the external signal acts on the electrode plates of the capacitor, the potential difference between the two plates of the capacitor will change due to the electric field, which will lead to the change of the capacitance value of the capacitor. This change can be processed by measuring the voltage or charge between the two plates of the capacitor for signal input and output. At the same time, the thin film capacitor can also realize signal processing by changing the intensity of the electric field. When an external signal is applied to the capacitor, the electric field strength will affect the carrier behavior on the insulating film, and then affect the capacitance of the capacitor. By changing the electric field intensity, we can gain, filter and modulate the signal.
Although thin film capacitors can be divided into many types, there are two types that are used the most, one is polypropylene thin film capacitors, also called CBB capacitors, and the other is polyester thin film capacitors.Polypropylene film capacitor, also known as CBB capacitor, has the characteristics of good self-healing, small volume, high voltage resistance, large capacity, low loss, good high-frequency characteristics and high reliability, and is suitable for AC and DC pulse circuits of automobile and motorcycle igniters, controllers, electronic meters, electronic ballasts of electronic instruments, middle and high-grade lamps and ozone generators. There are many CBB capacitors. Take Lorida CBB capacitor as an example, mainly including: CBB21/22 metallized polypropylene film capacitor, CBB20 axial capacitor, CBB21X ultra-small capacitor, CBB13 high-voltage capacitor, CBB81 high-voltage resonant capacitor, MMKP82 double-sided metallized capacitor, MPB boxed metallized polypropylene film capacitor, CBB61 starting capacitor, etc.
Polyester film capacitor metallized polyethylene film capacitor (also called CL capacitor) has good self-healing, small volume, large capacity, high voltage resistance and good reliability, and is suitable for various DC pulse circuits such as electronic instruments, ordinary power supplies, igniters, energy-saving lamps, chargers and communication equipment. Commonly used CL capacitors mainly include: CL21 capacitor, CL21X subminiature capacitor, CL20 axial capacitor, CL23B correction capacitor, CL11 polyester capacitor, etc.
According to electrode types, thin film capacitors can be divided into metal foil electrode type and metallized electrode type. Its structure is divided into three types, one is metal foil, the other is metal coating, and the other is metal foil and metal coating as electrodes. Metallized film capacitor is a capacitor made by evaporating a layer of metal film on the surface of the film instead of metal foil as electrode and winding it (except laminated structure). Because the thickness of metallized film is much smaller than that of metal foil, the volume after winding is much smaller than that of metal foil capacitor. The advantage of metallized film capacitor is "self-healing" characteristic. When high voltage is applied to the weak insulation part of the film, which leads to breakdown, the surrounding evaporated film is instantly oxidized and the insulation state is restored.In new energy vehicles, thin film capacitors are mainly used in key components such as energy recovery system, electric drive system and vehicle charging system.
Energy recovery system
In the energy recovery system of new energy vehicles, the film capacitor is mainly used to store and release regenerative braking energy. When the vehicle is braked, the film capacitor will store the energy generated in the braking process, and then release it when it needs to be accelerated, thus realizing energy recovery. This energy recovery method can not only improve the cruising range of new energy vehicles, but also reduce the dependence on traditional energy sources.
Electric drive system
In the electric drive system of new energy vehicles, as the starting capacitor of the motor, the thin-film capacitor can provide the instantaneous large current needed when the motor starts. Compared with the traditional electrolytic capacitor, the thin-film capacitor has higher power density and longer service life, which can effectively reduce the energy consumption and maintenance cost of electric vehicles.
On-board charging system
In the on-board charging system of new energy vehicles, film capacitors are mainly used in DC-DC converter and AC-DC converter. DC-DC converter can convert high-voltage DC of batteries into low-voltage DC to meet the needs of various electronic devices in electric vehicles, while AC-DC converter can convert AC provided by AC charging piles into DC to charge electric vehicles. The application of film capacitors in these two converters can be
In addition to the above-mentioned main application fields, thin film capacitors are also widely used in air conditioning systems, lighting systems, navigation systems, etc. of new energy vehicles. In these systems, thin film capacitors can provide stable voltage output and ensure the stable operation of the system. As a key electronic component, the thin film capacitor of new energy vehicles plays an important role in the key components of new energy vehicles, such as energy recovery, driving and charging. With the continuous development of new energy vehicle technology, the performance and application fields of thin film capacitors will be further expanded, providing strong support for the popularization and development of new energy vehicles. The application of thin-film capacitors in the field of new energy vehicles still faces some challenges, such as high cost and poor temperature stability. In order to overcome these challenges, Lorida Company is constantly optimizing the materials and structures of thin-film capacitors, improving their performance and reducing their costs, so as to meet the high-performance and low-cost requirements of new energy vehicles for thin-film capacitors.
