H bridge motor drive circuit work principle
I. H Bridge Motor Drive Circuit Figure 4.12 is a typical DC motor control circuit. The circuit has been named "H Bridge Drive Circuit" because its shape is like a letter H. 4 triodes constitute the 4 vertical legs of H, while the motor is the horizontal bar (Note: Figure 4.12) is only a schematic diagram, not a complete circuit diagram, wherein the drive circuit of the triode is not drawn). As shown, the H-bridge motor drive circuit includes four triodes and a motor. To operate the motor, you must turn on a pair of triodes on the diagonal. According to the conduction of different triode pairs, the current may flow from left to right or from right to left to left the motor to control the steering of the motor. FIG. 4.12 H bridge motor drive circuit to make the motor running, the pair of transistors must be turned on the diagonal. For example, as shown, when the tube of Q1 and Q4 is turned on, a current from the positive supply through 4.13 Q1 from left to right through the motor, and then back to the negative power supply through Q4. According to the current arrow in the figure, the flow of the flow direction will drive the motor clockwise. When the triodes Q1 and Q4 are turned on, the current will flow from the left to right, so that the drive motor is rotated in a specific direction (the arrow around the motor indicates the clockwise direction). FIG. 4.13 H-bridge circuit for driving the motor is rotated clockwise in FIG 4.14 shows another case of the transistor Q2 and Q3 is turned on, the current flows from right to left motor. When the triodes Q2 and Q3 are turned on, the current flows from the right to left through the motor, so that the motor is rotated in the other direction (the arrow around the motor is expressed as a counterclockwise direction). FIG. 4.14 H-bridge circuit for driving two motor rotates counterclockwise, and the direction of the control enabled logical drive motor, to ensure that the same side of H bridge two transistors are not simultaneously turned on is important. If the triodes Q1 and Q2 are turned on simultaneously, the current will be directly returned to the negative electrode from the positive electrode through the two triodes. At this time, there is no other load in the circuit except for the triode, the current on the circuit may reach the maximum (this current is only limited by power supply performance), even burn-critical triodes. Based on the above reasons, the switch of the triode is usually controlled in the actual drive circuit. 4.155 is shown in FIG improved circuit based on such considerations, it adds four AND gates and two NAND gates substantially based on the H-bridge circuit. 4 with a "enable" on the door, so that the switch of the entire circuit can be controlled with this signal. Two non-gates can provide one-to-side legs on the h-bridge to be turned on. (The illustrations, like earlier in this section, is not a complete circuit diagram shown in Figure 4.15, in particular in FIG direct connection is not working properly and the transistor gate.) 4.15 and having enable control of direction of the H-bridge circuit logic With the above method, the operation of the motor can use only three control signals: signals in both directions and an enable signal. If the DIR-L signal is 0, the DIR-R signal is 1, and the enable signal is 1, then the triodes Q1 and Q4 are turned on, and the current flows from the left to right (as shown in Figure 4.16); if Dir-L The signal becomes 1, and the DIR-R signal becomes 0, and the Q2 and Q3 will turn on, and the current flows through the motor. FIG using 4.16 enable signal when the direction signal actually used to produce H-bridge with discrete member is troublesome, hopefully, there is a lot encapsulated H-bridge integrated circuit, connected to the power supply, motor and control signals ready for use, within the rated voltage and current is very convenient and reliable. For example, common L293D, L298N, TA7257P, SN754410, and the like. , Reading the full text, the technology area
About μClinux transplantation on ARM7 S3C4510B
Multi-looped into charge and discharge controller design
Interrupt service routines for ARM embedded systems
LED dimming engine design based on 8-bit MCU
How to display Chinese characters, ASCII characters and color graphics on the LCD monitor
Our other product:
