Applications: motor control
There are numerous applications for the industrial market due to the many related sectors. EBV presents the most exciting application examples within the fields of:
- Test and Measurement
- Factory Automation
- Process Control
- Embedded Computing
- Embedded Vision
- Electronic Payment
- Motor Control
- Power Conversion
- Information and Advertising
Brush DC motor controllers
Brush DC motors are the most widely used drivers due to their low cost and simple drive control options
Typical brush DC motors consist of a rotating electromagnet surrounded by a permanent magnet. Rotational torque is produced by the interaction of the magnetic fields and continuous rotation is produced by changing the polarity of the rotating coil with a mechanical commutator and brushes. Typical brush DC motor drivers consist of a half bridge for single direction operation and an H-bridge configuration for bi-directional control.
Brushless DC motor controllers
BLDC motors are more efficient, run faster and quieter, and require electronics to control the rotating field. They are also cheaper to manufacture and easier to maintain
The brushless DC motor has stator windings and permanent magnets on the rotor. The windings are connected to the control electronics and there are no brushes and commutators inside the motor. The electronics energise the proper windings similar to a commutator; the windings are energised in a moving pattern that rotates around the stator. The energised stator windings lead the rotor magnet. Three-phase inverters are required to drive BLDC motors. These inverters consist of three half H-bridges, where upper and lower switches are controlled using complementary signals. It is important to keep a delay between high-side switch turn off and low-side switch turn on. This will eliminate a potential short across the switches.
AC induction motor controllers
The AC induction motor (ACIM) is the most popular motor used in consumer and industrial applications
In adjustable speed applications, AC motors are powered by inverters. The inverter converts DC power to AC power at the required frequency and amplitude. The inverter consists of three half-bridge units where the upper and lower switches are controlled complementarily. As the power device's turn-off time is longer than its turn-on time, some dead-time must be inserted between the turn-off of one transistor of the half-bridge and turn-on of its complementary device. The output voltage is mostly created by a pulse width modulation (PWM) technique. The three-phase voltage waves are shifted 120° to one another and thus a three-phase motor can be supplied. The three phase topology represents an ideal choice for variable-speed applications. Three phase inverters are commonly used where motor speed can be controlled by simply varying the voltage and frequency of the applied waveform (open-loop V/Hz or scalar control). Alternatively, speed can be controlled by wrapping a speed loop around a torque loop incorporating Field Oriented Control (FOC). FOC is more suitable to a powerful 32-bit processor or DSPs.
Stepper motor controllers
Stepper motors have found their way into many different areas of control systems
The wide popularity of these motors can be attributed in part to the various ways the motor can be driven and because of its compatibility with digital systems. In particular, stepper motors are ideal for control systems that require discrete, easily repeatable movements at moderate to low frequencies. Steppers are most commonly used in open-loop position control applications. In the case of stepper motors, the feedback is not always needed but can still be provided for precision assistance. In contrast, DC motors need feedback because they have a harder time making precision movements and require a circuit that can compensate for the risk of drifting or overshooting a target position. The feedback circuitry for the position of a motor is likely to be more complicated for DC motors than for stepper motors. Stepper motors have worked well in factories and assembly environments, in applications such as robotic arms and precision assembly controls. They can be found in printers, disk drives, toys, cars and a host of other applications and products.
Servo drives are designed to provide precise control, optimum torque and a rich feature set to complement a wide range of our rotary servomotors and linear positioning systems
Servo drives are utilised by machines to offer motion control in dynamic applications. Usually servo drives are commonly paired with servomotors but due to required flexibility in software setups they should be suited to run with most servomotors on the market (including resolvers, incremental encoders, BiSS, EnDat, Hiperface, sine encoders). Servo drives are used for dynamic motion applications where precise positioning, speed control, or torque efficiency is key in the range from 300 watts to 50,000 watts of continuous duty power output. Peak outputs with peak operation can be at 3 times the rated continuous current for a full 5 seconds in certain drives. This allows many applications to use significantly smaller servo drives and expands the dynamic performance of the servo drive lineup. Connectivity is a key aspect in machines so Fieldbus options are plentiful. We support many popular Ethernet Fieldbuses such as EtherCAT, Ethernet /IP, Profinet, and SynqNet as well traditional Fieldbuses including Profibus, Devicenet, CanOpen, S485, RS232, and Sercos II. . (See our FPGA microsite). Servo drives are available with integrated safety functionality which allows machine builders to create inherently safer machines with flexible safety zones requiring less wiring and configuration than ever before.
The position encoder system comprises a readhead with integrated sensing and processing electronics, and a magnetised scale which acts as the information carrier
Magnetised scales have controlled accuracy characteristics and well defined thermal behaviour, making them a reliable measuring standard. The magnetised scale is composed of a thick ferrite polymer composite layer bonded onto a thin steel carrier, either in the form of a strip for linear measurements, or in the form of a disc or ring for rotary measurements. This ferrite layer is magnetised so that south and north poles alternate along the length of the strip or around the circumference of the ring/disc. Hall and/or AMR sensors or sensor arrays inside the readhead convert the magnetisation signature of the scale into electrical signals, which can then be processed into digital counting and reference pulses for incremental encoders, or into position values for absolute encoders. These output signals are available in various forms, depending on the measuring system used. For incremental systems, RS422, open collector, push-pull and analog 1 Vpp sine/cosine signals are available. For absolute systems, several serial communication interfaces commonly found in industry (e.g. BiSS, CAN, SSI, SPI…) and analog current or analog voltage outputs are available. Designed for use in harsh environments, position encoders with magnetised scales can be used in many industrial areas such as industrial automation and assembly systems, metalworking, stone-cutting, sawing, textiles, plastics processing, woodworking, packaging and electronic chip/board production.