I. Classification of Inverters
According to the properties of wavestrings
There are two main types: one is the sine wave inverter and the other is the square wave inverter. The sine wave inverter outputs sine wave AC power that is the same as or even better than the power grid we use daily, because it does not have electromagnetic pollution in the power grid. The square wave inverter outputs square wave AC power of poor quality. Its positive maximum value to negative maximum value is generated almost simultaneously, which causes severe instability to the load and the inverter itself. At the same time, its load capacity is poor,[3] only 40-60% of the rated load, and it cannot carry inductive loads. If the load is too large, the third harmonic component contained in the square wave current will increase the capacitive current flowing into the load, and in severe cases, it will damage the power supply filter capacitor of the load. In response to the above shortcomings, quasi-sine wave (or improved sine wave, modified sine wave, simulated sine wave, etc.) inverters have emerged. The output waveform has a time interval between the positive maximum value and the negative maximum value, which improves the performance. However, the waveform of the quasi-sine wave is still composed of broken lines and belongs to the square wave category, and the continuity is not good. In summary, sinusoidal inverters provide high-quality AC power capable of driving any type of load, but they are technically demanding and costly. Quasi-sinusoidal inverters can meet most of our power needs, offering high efficiency, low noise, and a moderate price, making them the mainstream product in the market. Square wave inverters are manufactured using simple multivibrators, a technology dating back to the 1950s, and will gradually be phased out of the market.
Inverters are categorized based on their power source: coal-fired inverters, solar inverters, wind-powered inverters, and nuclear inverters. They are also classified by application: stand-alone inverters and grid-connected inverters. Globally, solar inverters from Europe and America have higher efficiency, with the European standard at 97.2%, but they are also more expensive. Other domestically produced inverters have efficiencies below 90%, but are significantly cheaper than imported ones. Besides power and waveform, inverter efficiency is crucial. Higher efficiency means less energy is wasted in the inverter itself, allowing more energy to be used in appliances, which is especially important when using low-power systems.
According to the nature of the source and flow
An active inverter is an inverter that connects the current in a current circuit to the power grid on the AC side instead of directly connecting it to the load.
Passive inverter: An inverter that allows the current in a current circuit to be directly connected to the load on the AC side without being connected to the power grid (i.e., converting DC power into AC power of a certain frequency or adjustable frequency to supply the load).
Common types
Small and medium power
Small and medium power inverters are a crucial component of residential independent AC photovoltaic systems. Their reliability and efficiency are essential for promoting photovoltaic systems, effectively utilizing energy, and reducing system costs. Therefore, photovoltaic experts from various countries have been working hard to develop inverters suitable for residential use in order to promote the better and faster development of the industry.
Multiple series
Multiple series inverters offer numerous advantages for electric vehicles. The series structure significantly increases the variety of output voltage vectors, enhancing control flexibility and accuracy; it also reduces fluctuations in the motor neutral point voltage. The inverter's bypass capability improves the flexibility of charging and regenerative braking control.
With increasing public concern for the urban environment, the development of electric vehicles has received a rare opportunity. In urban transportation, electric buses, due to their large carrying capacity and high overall efficiency, have become a priority for development. Most electric buses use three-phase AC motors. Because of the high motor power, the components in the three-phase inverter need to withstand high voltage and high current stress. The high dv/dt also results in significant electromagnetic radiation and requires good heat dissipation.
High-power inverters employing multiple series-connected structures reduce the voltage stress on individual components, lowering the requirements for components; they also reduce the dv/dt value, decreasing electromagnetic radiation and significantly reducing component heat generation; and their control performance is improved due to the increased variety of output levels.
Multiple series inverters are suitable for high-power electric vehicle drive systems. The multiple series structure reduces the hazards associated with multiple batteries connected in series, lowers switching stress on components, and reduces electromagnetic radiation. However, it doubles the number of batteries required.
The multi-series series structure significantly increases the variety of output voltage vectors, thereby enhancing control flexibility and improving control accuracy; it also reduces fluctuations in the motor neutral point voltage. To maintain a balanced charge level among each battery bank, it is necessary to ensure consistent battery discharge times during operation. Bypassing allows for flexible charging of the battery banks and control of regenerative braking torque.
In-vehicle
Car inverters typically use a car battery or cigarette lighter socket for power. They first convert low-voltage DC to approximately 265V DC, and then convert the high-voltage DC to 220V, 50Hz AC. Car inverters overcome many limitations of using electrical appliances inside a vehicle. They are not only suitable for in-vehicle systems but can be used wherever a 12V DC power supply is available. Car inverters take into account the external operating environment and will automatically shut down in case of overload or short circuit.
Choosing a vehicle inverter
Vehicle inverters are power supply products that operate in high-current, high-frequency environments, resulting in a relatively high potential failure rate. Therefore, consumers must be cautious when purchasing them. Firstly, consider the inverter's output waveform; it should ideally not be lower than a quasi-sine wave. Secondly, the inverter should have comprehensive circuit protection functions. Thirdly, the manufacturer should offer a good after-sales service commitment. Fourthly, the circuitry and the product should have undergone a period of testing.
1. When choosing a car power supply, in addition to price, the main considerations are the input voltage requirements and output power. Furthermore, since the power of various electrical appliances varies greatly, the car power supply should be selected according to usage needs, with the principle being to choose one that is sufficient for the intended purpose.
2. Depending on the type of electrical appliance used, a suitable vehicle power supply needs to be selected. For everyday resistive electrical appliances, square wave, modified wave, and sine wave inverters can all be used. For inductive electrical appliances, a sine wave inverter must be selected.
3. Square wave/corrected wave inverters cannot power inductive or capacitive loads, cannot power air conditioners or refrigerators, and are unlikely to provide power for high-quality audio and television equipment. Strictly speaking, square wave/corrected wave inverters can affect the lifespan of electrical appliances, problems that do not occur when using sine wave inverters.
4. The cigarette lighter fuse in a typical passenger car is 10A or 15A (10A fuses are mostly found in older models or imported vehicles). This means that the onboard inverter that can be used in a typical passenger car is 120W or 180W. If you need a high-power inverter (over 180W or 200W), be sure to check if there are battery clamps in the packaging. High-power inverters without battery clamps will have limitations when used in passenger cars.
5. Most car power supplies have a fuse at the cigarette lighter socket. Qiqi Auto Accessories Network reminds you to check that this fuse is compatible with the car cigarette lighter fuse when purchasing (theoretically, it should be less than or equal to the cigarette lighter fuse). Only in this way can the cigarette lighter fuse work. Otherwise, it will cause the car cigarette lighter fuse to blow, causing unnecessary trouble.
II. Characteristics of Inverters
1. High conversion efficiency and fast start-up;
2. Excellent safety performance: The product has five protection functions: short circuit, overload, over/under voltage, and over-temperature.
3. Excellent physical properties: The product uses an all-aluminum shell, which has good heat dissipation performance, a hard anodized surface treatment, good abrasion resistance, and can withstand certain external pressure or impact;
4. Strong adaptability and stability under load
