New energy vehicles New energy vehicles refer to the technical principles of using unconventional vehicle fuels as a power source (or using conventional vehicle fuels, using new vehicle power units), advanced technologies in integrated vehicle power control and drive. Advanced, new technology, new structure of the car. The principle of new energy vehicle motor control, its core is the application of frequency control technology.
We know that the types of drive motors used in most new energy vehicles are three-phase permanent magnet synchronous motors, three-phase asynchronous motors, etc. When the input motor is balanced with three-phase balanced sinusoidal AC energy, the motor can rotate and output torque, new energy. The power supply for the car is a DC power supply. When driving the motor, the DC power supplied by the power supply needs to be converted into three-phase AC power. This conversion device is called a motor controller. The English abbreviation is MCU. How does the motor controller work? The following small series will briefly explain the working principle of the motor controller.
Let's take a look at the block diagram of the control system of the permanent magnet synchronous motor of the new energy vehicle (see Figure 1):
In the control method, field oriented control (FOC) and direct torque control (DTC) are two high-performance control strategies for AC motors, which have been widely used in practice. They were originally only used for the control of asynchronous motors. It is extended to the control of synchronous motor and permanent magnet synchronous motor to control the starting, accelerating, running, decelerating and stopping of the motor. According to the different types of motors and the use of the motor, it has the purpose of fast start, fast response, high efficiency, high torque output and high overload capability.
In the motor control, the three-phase inverter (see Figure 2) is the most important part. It converts the input DC power into the power part of the AC power. It belongs to the main circuit part and belongs to the control execution part. It is to explain the working principle of the three-phase inverter.
Next, we have to look inside the inverter, that is, the main circuit circuit diagram (see Figure 3), consisting of six IGBTs (insulated gate bipolar transistors), between each phase output line and the positive and negative DC bus Each IGBT power tube is connected. We call the IGBT and the output node connected to the positive bus as the “upper armâ€. The IGBT and the output node connected to the negative bus are called “lower armâ€, and the upper and lower sides of each phase. The bridge arms are collectively referred to as “half bridgesâ€. The serial numbers of the six IGBTs are generally T1~T6 (VD1~VD6 is used for small series), and the upper arm of the first phase is T1 (or VD1), and the positions of other IGBTs are corresponding. Should be found from the coordinate map of the PWM, Xiaobian here to buy a Guan!
In order to be able to convert the input DC into AC power, the six IGBTs will be turned on and off in sequence from T1~T6 (or VD1~VD6), and sequentially turned on (or turned off) at intervals of 60°, U/ The phase difference of the V/W three phases is 120°, which means that the IGBT with the 120° turn-on (or off) of the first phase (U phase) is the second phase (V phase). The upper arm and the second phase (V phase) upper arm are turned on (or turned off) by 120° IGBT as the upper arm of the third phase (W phase), and the number of the lower arm is well distinguished. Everyone knows that a period of sinusoidal alternating current passes through an angle of 360° (2π), where a positive half wave passes through 180° (π) and enters the third quadrant from the second quadrant, becomes a negative half wave and passes through 180° (π ). Think about it, can the upper and lower arms of each phase be turned on at the same time? Can there be a superposition relationship? The answer is very positive, of course not, because the upper and lower arms are directly connected in the middle and serve as the output of this phase. If there is simultaneous conduction or superimposed conduction, it will lead to direct transconductance between the positive and negative busbars, causing a short circuit. Obviously It is forbidden to happen. Therefore, when the lower arm of the upper arm of a certain phase is incapable of being turned on, that is, it is completely turned off, the upper arm is turned off immediately after being turned on by 180° (π), which is regarded as the phase. Positive half wave. Which of the other is the lower arm that is turned on at the time when the upper arm is turned off and passes through 180° (π). As shown in Figure 4.
The cyclic output of each phase is 120°, and AC power is generated. When the permanent magnet synchronous motor is connected, a rotating magnetic field is established, and the rotor of the motor can rotate and perform external work.
The name of wireless router can be separated out of two keywords: wireless and routing. Understand the technical principle behind these two words, you understand the wireless router.
Wireless is also what we often call Wi-Fi. Wireless routers can convert home broadband from wired to wireless signals, and all devices can happily surf the Internet as long as they connect to their own Wi-Fi. In addition, these devices also form a wireless local area network, where local data is exchanged at high speed and is not limited by the bandwidth of home broadband.
For example, many people have smart speakers in their homes that can be used to control various smart appliances. When you say small X small X, turn on the TV, the speaker actually finds the TV through the LAN and sends instructions, and does not need to connect to the Internet; And if you let it broadcast news, you have to get data through the Internet.
The Local Area Network we talked about earlier, also known as the Intranet, is represented by the Local Area Network (LAN) on the router, so the Wi-Fi signal is also called WLAN(Wireless LAN); The Internet we want to access, also known as the extranet, is represented on the router by the WAN(Wide Area Network).
On the Intranet, the IP address of each device is different, which is called a private address. All devices on the Internet share the same public address, which is assigned by broadband operators such as China Telecom Unicom.
The router is the bridge between the Intranet and the external network. The above mentioned IP address translation, packet forwarding, is the router routing function.
In other words, the router is the hub of the home network, and the data of all the devices must be forwarded through it to access each other or reach the external network, which means that one husband is the key and ten thousand men are not open, so the comprehensive router is also called "home gateway".
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Shenzhen MovingComm Technology Co., Ltd. , https://www.movingcommtech.com