The circuit uses NMOS field effect tube as a power output device, designed and implemented a larger power DC motor H-bridge drive circuit, and a 25D60-24A DC motor having a rated voltage of 3.8A, a 25D60-24A DC motor of a rated current is closed loop control. The circuit's anti-interference ability is strong and has strong applicability in the field of industrial control. Many semiconductor companies have introduced DC motor-specific drive chips, but most of these chips are only suitable for small power DC motors, and their integrated chips are expensive for high-power DC motors.
In the design of the DC motor drive circuit, consider a few points:
1. Function: Is the motor to rotate two-way? Do you need to speed up? For one-way motor drive, only use a high-power triode or field effect tube or relay direct motor
That is, when the motor needs two-way rotation, a H-bridge circuit consisting of four power elements can be used or a double-throwing relay can be used. If you don't need to speed up, just make
Use relays; but if speed control is required, switching elements such as triodes, field effect tubes can be used to implement PWM (pulse width modulation) speed control.
2. Performance: The motor drive circuit for PWM speed control mainly has the following performance indicators.
1) Output current and voltage range, which determines the motor that can drive multiple power.
2) Efficiency, high efficiency not only means saving power, but also reduces the fever of the drive circuit. To improve the efficiency of the circuit, you can work from the switch of the power device and prevent
A problem that the H-bridge or push-pull circuit may occur, that is, two power devices simultaneously turn on the power supply short circuit.
3) The impact on the control input. The power circuit should have good signal isolation on its input to prevent high voltage large currents from entering the main control circuit, which can use high input impedance or
The photocoupler realizes isolation.
4) The impact on the power supply. Candidity can cause the instantial decline in the power supply voltage to cause high-frequency power supply; large currents may cause ground potential floating.
5) Reliability. The motor drive circuit should do as much as possible, no matter what control signal, what passive load, the circuit is safe. H Bridge Drive Circuit: The H bridge motor drive circuit includes four triodes and a motor because its shape is like alpha. It is called the H-bridge drive circuit.
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To operate the motor M, a pair of triodes on the diagonal must be turned on. For example, when the Q1 tube and the Q4 tube are turned on, the current passes from the left to right from 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. The motor rotates clockwise clockwise. When the triodes Q2 and Q3 are turned on, the current will flow from the right to left through the motor, and drive the motor counterclockwise.
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The complete transistor H bridge drive circuit, PWM1, PWM2, control input, PWM1 = 1, PWM2 = 0, PWM = 0, and PWM2 = 1 when the motor is reversed.
PWM1, PWM2 is also the pulse width input of motor speed control.
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The transistor is the most cheap control method, but there is a significant pressure drop on the transistor, which generates power loss, is not high, suitable for use in low voltage, small power.
The figure below is the H-bridge drive circuit composed of field effect tubes, the field effect tube is the highest efficiency, but the price is high, usually applied in high-power motor drive applications.
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The above is a circuit composed of discrete components, and the actual use is cumbersome and the fault rate is high. Usually use integrated H-bridge drive chips, high integration, convenient use, and high reliability. Such as L9110, L298N, LMD18200, TA7257P, SN754410, MC33886, and the like. , Reading the full text, the technology area
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