DC motor drive circuit solution based on 25D60-24A

This circuit uses NMOS field effect tube as power output device, designs and implements high power DC motor H bridge drive circuit, and performs closed loop control on 25D60-24A DC motor with rated voltage of 24V and rated current of 3.8A. The circuit has strong anti-interference ability and strong applicability in the field of industrial control. Many semiconductor companies have launched dedicated DC motor driver chips, but most of these chips are only suitable for low power DC motors. For the drive of high power DC motors, their integrated chips are expensive.

In the design of DC motor drive circuit, the following points should be considered:

1. Function: Is the motor unidirectional or bidirectional? Does it need speed regulation? For unidirectional motor drive, just use a high-power transistor or field effect tube or relay to directly drive the motor. When the motor needs to rotate in both directions, you can use an H-bridge circuit composed of 4 power components or a double-pole double-throw relay. If speed regulation is not required, just use a relay; but if speed regulation is required, you can use transistors, field effect tubes and other switching elements to achieve PWM (pulse width modulation) speed regulation.

2. Performance: For the PWM speed regulation motor drive circuit, the main performance indicators are as follows.

1) Output current and voltage range, which determines how powerful the circuit can drive the motor.

2) Efficiency. High efficiency not only means saving power, but also reduces the heat of the drive circuit. To improve the efficiency of the circuit, we can start from ensuring the switching working state of the power device and preventing common conduction (a problem that may occur in H-bridge or push-pull circuits, that is, two power devices are turned on at the same time to short-circuit the power supply).

3) Impact on the control input. The power circuit should have good signal isolation at its input to prevent high voltage and high current from entering the main control circuit. This can be achieved by using high input impedance or

Optocouplers provide isolation.

4) Impact on power supply: Common-mode conduction can cause a momentary drop in power supply voltage, resulting in high-frequency power supply pollution; large currents may cause ground potential to float.

5) Reliability. The motor drive circuit should be as safe as possible regardless of the control signal or passive load. H-bridge drive circuit: The H-bridge motor drive circuit includes 4 transistors and a motor. It is called an H-bridge drive circuit because its shape resembles the letter 'H'.

To make the motor M run, the pair of transistors on the diagonal must be turned on. For example, when Q1 and Q4 are turned on, the current flows from the positive pole of the power supply through Q1 from left to right through the motor, and then returns to the negative pole of the power supply through Q4. The motor rotates clockwise. When transistors Q2 and Q3 are turned on, the current flows from right to left through the motor, driving the motor to rotate counterclockwise.

Complete transistor H-bridge drive circuit, PWM1, PWM2, are the motor direction control input terminals, PWM1=1, PWM2=0 is forward rotation, PWM=0, PWM2=1 is reverse rotation.

PWM1 and PWM2 are also the pulse width input terminals for motor speed regulation.

Transistor is the cheapest control method, but there is a significant voltage drop on the transistor, which will cause power loss and low efficiency. It is suitable for use in low voltage and low power occasions.

The figure below shows an H-bridge drive circuit composed of field-effect transistors. Field-effect transistors are the most efficient control method, but they are more expensive and are usually used in high-power motor drive applications.

The above circuits are all composed of discrete components. They are difficult to make in actual use and have a high failure rate. Usually, integrated H-bridge driver chips are used, which have high integration, are easy to use, and have high reliability. Such as L9110, L298N, LMD18200, TA7257P, SN754410, MC33886, etc.

L9110 driving circuit:

L9110 is a two-channel push-pull power amplifier ASIC designed for controlling and driving motors. It integrates discrete circuits into a single-chip IC, which reduces the cost of peripheral devices and improves the reliability of the whole machine. The chip has two TTL/CMOS compatible inputs, which can be directly interfaced with the microcontroller and have good anti-interference performance; the two output terminals can directly drive the forward and reverse movement of the motor. It has a large current driving capability, and each channel can pass 750~800mA of continuous current, and the peak current capacity can reach 1.5~2.0A; at the same time, it has a low output saturation voltage drop; the built-in clamping diode can release the reverse impact current of the inductive load, making it safe and reliable in driving relays, DC motors, stepper motors or switching power tubes. L9110 is widely used in circuits such as toy car motor drive, stepper motor drive and switching power tubes.

Wide voltage operating range 2.5V~12v.

L298N driving circuit:

L298N is a high voltage, high current motor driver chip produced by ST. The chip adopts 15-pin package. The main features are: high working voltage, 3~46V, large output current, instantaneous peak current can reach 3A, continuous working current is 2A; rated power is 25W. It contains two H-bridge high voltage and high current full-bridge drivers, which can be used to drive DC motors and stepper motors, relay coils and other inductive loads; it adopts standard logic level signal control and is directly connected to the microcontroller pins; it has two enable control terminals, which allow or prohibit the device from working without being affected by the input signal, and has a logic power input terminal, so that the internal logic circuit part works at low voltage; it can be connected to an external detection resistor to feed back the change to the control circuit. Use L298N chip to drive the motor. The chip can drive a two-phase stepper motor or a four-phase stepper motor, or two DC motors.

VS is the motor drive power supply, and VSS is the logic control power supply.

In the figure below, PA0~PA3 are the I/O pins of the microcontroller, which control the forward and reverse rotation of the two DC motors M1 and M2.

4-phase stepper motor drive circuit

LMD18200 drive circuit:

LMD18200 is an H-bridge component specially designed for motion control launched by National Semiconductor (NS). CMOS control circuit and DMOS power device are integrated on the same chip, with peak output current up to 6A, continuous output current up to 3A, working voltage up to 55V, and temperature alarm, overheating and short circuit protection functions.

Four DMOS tubes are integrated inside to form a standard H-type drive bridge. The charge pump circuit provides gate control voltage for the two switch tubes in the upper bridge arm.

The circuit has an operating frequency of about 300kHz. External capacitors can be connected to pins 1 and 11 to form a second charge pump circuit. The larger the external capacitor, the faster the input capacitor of the switch gate is charged, the shorter the voltage rise time, and the higher the operating frequency can be. Pins 2 and 10 are connected to the DC motor. When rotating forward, the direction of the current should be from pin 10 to pin 10; when rotating reversely, the direction of the current should be from pin 10 to pin 2. The current detection output pin 8 can be connected to a resistor to ground, and the overcurrent condition is output through the resistor. The overcurrent threshold set by the internal protection circuit is 10A. When it exceeds this value, the output will be automatically blocked and the output will be automatically restored periodically. If the overcurrent lasts for a long time, the overheat protection will shut down the entire output. The overheat signal can also be output through pin 9. When the junction temperature reaches 145 degrees, pin 9 has an output signal. PB0 and PB1 are the I/O ports of the microcontroller. PB0 controls the forward and reverse rotation of the motor, and PB1 inputs the pulse width to control the speed of the motor.