The H-bridge is a typical DC motor control circuit because its circuit shape is like a letter H, so the name and "H Bridge". The four triodes constitute the four vertical legs of H, while the motor is the horizontal bar (Note: The figure is just a simply intent, not a complete circuit diagram, where the drive circuit of the triode is not drawn).
H-bridge drive principle
1) Motor drive
The circuit first, the single chip can output a DC signal, but its drive can also be limited, so the single-chip is normal to drive the drive signal, drive large power tube such as MOS tube, to generate a large current to drive the motor, and the duty ratio can be driven The chip control is applied to the homogeneous voltage of the motor to the rotational speed conditioning. The motor drive mainly uses the N-channel MOSFET to build an H-bridge drive circuit. The H-bridge is a typical DC motor control circuit. Since its circuit shape is like a letter h, it is called "H Bridge". 4 switches constitute the 4 vertical legs of H, and the motor is the horizontal bar in H. To operate the motor, it is necessary to turn the pair of switches on the diagonal line, and the motor is inversion, and its communication circuit is shown in the figure.
2) H-bridge drive principle
In practice drive circuits, the hardware circuit is usually used to control the switch. The motor drive plate mainly uses two driving chips, one is a full bridge drive HIP4082, one is the half-bridge drive IR2104, half bridge circuit is two MOS tube composed of two MOS Oscillation, the full bridge circuit is an oscillation of four MOS tubes. Among them, the IR2104 type half-bridge drive chip can drive high-end and low-end two N-channel MOSFETs, which can provide larger gate drive currents, and have hardware dead zones, hardware anti-homogeneous arms. The use of two IR2104-type half-bridge drive chips can form a intact DC motor H bridge drive circuit, and IR2104 is low, the function is perfect, and the output power is low in HIP4082, which is much more.
In addition, since the drive circuit may generate a larger recovery current, in order to avoid the impact on the single chip, it is best to isolate the chip, there are many ways, such as 2801, etc., these chips often control the bus driver. Progressive driving can be, after meeting a certain condition, the output is the same, and the data one-way transmission can be stopped, that is, the microcontroller signal can be driven to the drive chip, and it is not possible.
MOS tube H-bridge motor drive circuit diagram
1) Typical MOS Tube H Bridge DC Motor Control Circuit
The circuit has been named "H Bridge Drive Circuit" is because its shape is like a letter H. 4 triodes constitute the 4 vertical legs, while the motor is the horizontal bar (note: Figure 1) is only a diagram, not a intact 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, there is a need to turn on a pair of triodes on the diagonal. According to the conduction conditions of different triode pairs, the current may flow from left to right or from right to left to left the motor, thereby controlling the steering of the motor.
To operate the motor, it is necessary to turn on a pair of triodes on the diagonal line. For example, as shown in FIG. 2, when the Q1 tube and the Q4 tube are turned on, the current passes from the left to the left to the right from the left to right from the power supply positive electrode, and then returns to the power supply negative electrode. 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 is indicated as a clockwise direction).
Figure 3 shows the status of the other pair of transistors Q2 and Q3, and current will flow from the right to left. 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 arrows around the motor are expressed as counterclockwise).
2) Enable control and direction logic
When driving the motor, it is important to ensure that the three triodes on the H bridge are not at the same time. If the triodes Q1 and Q2 are simultaneously turned on, the current will directly return to the negative electrode from the positive electrode. At this time, there is no other load except the triode in the circuit, so that the current on the circuit may reach the maximum (this current is limited only by power supply performance), and even the burnout transistor. Based on the above, the hardware circuit is usually controlled by the hardware circuit to control the switch of the triode in the practice drive circuit.
The improved circuit increases 4 with the door and 2 non-doors on the root of the fundamental H-bridge circuit. 4 to the door with a "enable" gate signal number, so that the switch of the entire circuit can be controlled with this signal. Two non-gates have provided one direction loser that ensures that one triode can be turned on on the hiding leg of the H-bridge in any time. (Like the representation in front of this section, Figure 4 is not a intact circuit diagram, especially in the picture, and the direct connection of the door and triode is not working properly)
With the above measures, the operation of the motor is required to use three signal controls: two direction signals 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 5); 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.
The time division is used, and it is very worker with a discrete component. It is very much, so there are many packaging H-bridge integrated circuits in today's market, which can be applied to the power supply, motor and control signals, rated voltage and current. It is very secure in the internal use. An attached H-bridge drive circuit with two discrete components:
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