Type of motor

Brushed DC motors typically require a reversible driver and often require pulse width modulation (PWM), braking, and forward and reverse modes. Ideally, the driver of a brushless DC motor should also include a current limiting function and may need to support high-speed driving.

The driver of a three-phase brushless motor, commonly used in applications such as paper feeding or fans, typically needs to be compatible with sensorless motors and/or motors equipped with Hall sensors. Different commutation angles may be involved, and sinusoidal commutation can ensure low noise and low vibration (Figure 1).

When position and holding torque are more important than rotation or general motion, a stepper motor is used. In order to make stepper motors run quietly, they usually use a mixed attenuation function. They usually require two power sources as well as overvoltage and overcurrent protection functions. The stepper motor adopts various driving methods - usually, this method is directly related to the usage of the motor (Figure 2).

Basic parameters of motor driver

Once the type of motor is determined, attention must be paid to certain key parameters related to the motor, including:

Output current

Application voltage (3.3/5, 12, 24/36, 250, 600 V)

Rated power dissipation

Number of outputs

These parameters are very important and will greatly reduce the available selection range of motor drivers.

Application requirements

Electric motors are an important component of printers, vacuum cleaners, cameras, and CNC equipment, not to mention air conditioners, washing machines, and refrigerators. Each of these products requires multiple DC motors to operate, and each motor has its own set of requirements. Once the parameters of the motor and motor driver are determined, the focus should shift to specific requirements related to the application.

printer

The paper mover in the printer uses a stepper motor or a DC brush motor, and the design may require high precision and minimal vibration depending on the printer's objectives. The type and requirements of the motor will vary depending on the type of printer (i.e. industrial printer, thermal printer, inkjet printer, or multifunctional printer). Some battery powered thermal printers may require efficient control solutions to save power, while other printers, such as inkjet printers, may require highly precise positioning (Figure 3).

For example, multifunctional printers typically use three-phase brushless DC motor drivers or stepper motor drivers (single channel or dual channel) to drive the paper feeder. The tray and ink motor typically require a single-chip H-bridge driver. A single channel or dual channel H-bridge with two DC voltage regulators is the most commonly used design for system motor drivers.

robotic vacuum cleaner 

Robot vacuum cleaners require separate motors for suction, rolling, rotating rollers, and side brushes. Although all motors are typically three-phase brushless motors, two different general motor driver categories are used: three-phase brushless motor drivers and discrete H-bridge DC brushless motor drivers. The motor driver used depends on the purpose of the motor in vacuum (Figure 4).

The robot vacuum device is powered by rechargeable batteries, making efficiency a major issue, while also requiring a large amount of power to be supplied to the vacuum motor. In addition, the vacuum motor needs to run quietly, which is another key feature that affects the selection of the motor driver (Figure 5).

camera

The basic function of modern cameras (including SLR cameras, drone cameras, and safety cameras) is the type of motor, such as DC brush motors and stepper motors. The dual H-bridge driver is most commonly used to control the camera motor. When it comes to camera motors, requirements such as high efficiency and compact size are common, and drivers that support highly precise and precise positioning with minimal vibration are also important (Figure 6).

The pan/rotate/tilt function in the camera depends on a low-voltage DC brushless motor with a single channel H-bridge driver or a stepper motor with a compact high-speed H-bridge motor driver with a single channel or six channels. A fully integrated camera driver is available, as is the compact high-speed H-bridge stepper motor driver for cameras and lens motors (including focusing, zoom, and shutter). The autofocus lens motor most commonly relies on a voice coil motor with an open-loop autofocus driver.

CNC motors for small machines

All kinds of small machines rely on CNC (Computer Numerical Control) motors, including laser cutting machines, vinyl cutting machines, 3D printers, small milling machines, lathes, and grinders. A high current, compact, single channel bipolar stepper motor driver is the most common choice for CNC products.

Please remember that these applications involve multi axis positioning, so multiple motors need to work together. Therefore, the selected motor driver must be able to support highly accurate and precise positioning, usually requiring micro step accuracy. In addition, space may be important in these designs.

Factors to Consider for Motor Drivers

When selecting a motor driver, the type of motor and basic driver parameters are the correct starting points, but other factors must be considered. Considering that each application may require multiple motors, it is crucial to consider the specific purpose of each motor in the system.

For example, Rohm has a wide range of motor driver series designed for specific applications. All DC motor drivers are designed to provide high reliability, with internal protection functions and optimized drive waveforms to reduce noise and vibration. In addition, these motor drivers also maintain efficient driving control algorithms.