one. Power conversion module The so-called power supply voltage is the input voltage through the voltage conversion circuit to achieve the boost / buck function for other modules. In the smart car production, the input battery voltage is 7.2V, the required voltage of other modules is as follows: minimum system board / OLED / eagle Eye camera 3.3V, op amp power supply ± 5V, servo power supply 6V, drive circuit 12V, CCD / encoder 5V. Here are some related introductions to the voltage conversion circuit. The voltage regulator circuit is mainly divided into the following categories: LM2940 to 5V: LM2940 is a series linear regulator circuit (only for buck). This type of circuit has simple structure and high stability, but has large power consumption, large volume and low filtering efficiency. It requires large input and output filter capacitors. MC34063 to 12V MC34063 is a switching DC regulator chip (can be used for boost/buck). This type of circuit has low power consumption, high efficiency, small size, light weight and wide voltage regulation range, but its circuit structure is complex and the failure rate is high. The working principle is that when the voltage is boosted, the inside of the chip is continuously turned on by the switch tube (the frequency is related to the timing capacitor), and the energy storage inductor and the capacitor are continuously charged and discharged for a short time to provide energy to the load (the inductor can be selected to be larger) Output continuous DC voltage, Uo=1.25*(1+R4/R3) (see manual formula). MIC29302 to 6V: The MIC29302 is a linear adjustable regulator. It is similar to the 34063 circuit and can be used for high current loads. Its voltage output formula is Uo=1.242*(1+R1/R2). In this example, the output 6V supplies power to the steering gear. LM2663 to -5V: The LM2663 can be used as a simple negative voltage converter that uses only two external capacitors. Note: The reverse connection of the circuit due to manual operation errors and the like should be avoided as much as possible, and the anti-reverse design can be added to the circuit. Unidirectional conductivity using diodes: MOS tube type anti-reverse protection circuit The NMOS transistor is connected to the negative terminal of the power supply, and the gate is turned on at a high level. The PMOS transistor is connected to the positive terminal of the power supply, and the gate is turned on at a low level. (The on-resistance of the NMOS transistor is smaller than that of the PMOS, and it is preferable to select the NMOS) Various anti-reverse interfaces two. Motor drive circuit First, the MCU can output DC signal, but its driving capability is also limited, so the MCU generally uses the driving signal to drive a large power tube such as the Mos tube (LR7843) to generate a large current to drive the motor, and the duty cycle can be The driving chip controls the average voltage applied to the motor to achieve the purpose of speed regulation. The motor drive mainly uses an N-channel MOSFET to build an H-bridge drive circuit. The H-bridge is a typical DC motor control circuit. Because its circuit shape resembles the letter H, it is called the “H-bridgeâ€. The four switches make up the four vertical legs of H, and the motor is the bar in H. In order to make the motor run, it is necessary to turn on a pair of switches on the diagonal line and control the forward and reverse rotation of the motor through different current directions. The connected circuit is as shown in the figure. H-bridge drive principle In the actual drive circuit, the switch is usually conveniently controlled by a hardware circuit. The motor drive board mainly uses two kinds of drive chips, one is a full bridge drive HIP4082, the other is a half bridge drive IR2104, and the half bridge circuit is composed of two MOS tubes. Oscillation, the full bridge circuit is an oscillation composed of four MOS tubes. Among them, IR2104 half-bridge driver chip can drive high-end and low-end two N-channel MOSFETs, can provide large gate drive current, and has hardware dead zone, hardware anti-same arm conduction and other functions. The two-chip IR2104 half-bridge driver chip can be used to form a complete DC motor H-bridge driver circuit, and the IR2104 is inexpensive and has perfect functions. The output power is lower than that of the HIP4082. In addition, because the driver circuit may generate a large recharge current, in order to prevent the impact on the microcontroller, it is better to isolate the chip, there are many ways to isolate the chip, such as 74lvc245, 74hc244, PS2801, etc. These chips are often used as control buses. The driver is to improve the driving ability. After satisfying certain conditions, the output is the same as the input, and the data can be transmitted in one direction, that is, the signal of the single chip can be driven to the chip, and vice versa. Guangzhou Yunge Tianhong Electronic Technology Co., Ltd , https://www.e-cigaretteyfactory.com