Motors are one of the largest energy consumers on the factory floor. Almost all of the lifetime cost of a motor is due to energy consumed by the motor. Accurate motor control is the easiest way to minimize energy consumption. High-performance AC motors and Servo motors (AC motor with an encoder or resolver) use discrete analog signal path components as part of the control loop to reduce energy consumption and maximize performance.
National’s precision amplifiers, data converters, temperature sensors, power management, and PHYTER transceivers enable higher-quality products at higher speeds via improved motor control, finer production control, and lower power consumption to reduce production costs. National solutions support high performance simultaneous-sampling AC and servo motor control. National’s IEEE 1588 solutions achieve high-speed synchronization (at tens of nanoseconds) for higher quality at higher speeds.
AC and Servo Motor Systems are used for critical manufacturing and control application in a wide range of industries. High-performance AC and Servo motors use discrete analog signal path components to reduce energy consumption and maximize performance. Motors are one of the largest energy consumers on the factory floor. Almost all of the lifetime cost of a motor on the factory floor is due to energy consumed by the motor. Accurate motor control is the easiest way to minimize this energy consumption. The applications that follow use 12-bit ADCs to provide ±0.024% signal accuracy over temperature, and use 14-bit ADCs to provide ±0.012% signal accuracy over temperature. See the applications below for more product recommendation details:
High-performance AC motors are driven by a 3-phase current. The motor controller adjusts motor torque based on several inputs. The most critical are measurements of the current of 2 phases of the motor. These need to be measured simultaneously. In the diagram below an ADC122S706 is used with 2 current sensors to provide input to the controller. An ADC141S626 and LMP® ampflier provide speed input to the controller. AC Motor Applications: Conveying, pumping, process control and robotics in automotive, food and beverage, chemical, medical, metals and semiconductor industries
Servo drives are AC drives with the addition of an encoder or resolver to provide finer control. Encoders provide better performance than resolvers, however a resolver can be used over a wider temperature range and can tolerate higher shock and vibration. In the case below, an ADC provides input from an optical encoder or resolver to the controller. An amplifier may be required before the ADC to increase the output of the encoder. Servo Drive Applications: CNC machines, semiconductor, LCD and automotive manufacturing, and robotics for molding, surface mount manufacture and material handling
In some areas, like HVAC and commercial washing machines, overall system cost is critical and performance requirements are not as demanding as previously discussed applications. In this case, current and voltage measured before the inverter provide input to the DSP.
Manufacturing systems in applications like paper manufacturing food / beverage packaging and semiconductor processing often require high-speed motion/motor synchronization to maintain product quality at high throughput rates. The IEEE1588 compatible DP83640 10/100 Ethernet PHYTER provides real-time control with individual nodes synchronized to <10 ns accuracy. The DP83849 provides dual-channel capability for critical applications requiring redundancy.
