A variable speed drive (VCD) is a solid state drive that uses power electronics and an array of discrete transistors for the control of alternating current (AC). A variable-speed drive allows the user to adjust the alternating current generated by the drive to a predetermined value, which can be stable or fluctuating. It can also be controlled to a specific range, from a low or zero torque position to over a full rotation. The output signal of a VCD is usually a multiplexer that allows it to communicate with a host computer or other drive devices. Some VCDs are bipolar.
A variable speed drive has many advantages, particularly in applications where a high-precision timing is required. In semiconductor technologies, such as microchip technology, it is important to have a constant, predictable output signal. This is achieved through the use of a rotating collector plate. The rotating collector plate is coupled to a source of sensing media, which provides a reference source of grid voltage. This grid voltage is then converted into a stable magnetic field by a field converting device such as a solenoid or microelectrode.
As an alternative
To electrical drive methods, such as direct drive and screw driven electric motors, the variable speed drives are a very energy-efficient, economical and clean mechanical design. It is used more frequently in the industrial, scientific and business sectors. It is also used in medical equipment such as medical robots controlled by an electronic circuit. In this case, the drive is often protected by a magnetic field generated by an electric motor. These types of drives are increasingly used in the food service industry to provide fast, reliable and energy-efficient packaging solutions.
Variable-speed drives have four speeds (ranging from zero to 500 rpm), a synchronous motor control interface, and a launch product selector. The synchronous motor control interface controls the speed of the motor and provides motor control commands on startup. To make the synchronous control interface reliable and robust, it is usually incorporated within a microcontroller. The launch product selector allows a variable speed drive to be selected by a user-programmable for load and performance needs.
The speed
Variable-speed drives use DC motors rather than AC motors. Because AC motors tend to be more sensitive to changes in the temperature of the air surrounding them, they tend to be less robust and need to be cooled down after operation. On the other hand, the DC motors within a variable speed drive are more robust, especially in long term use. In AC drives, power dissipations lead to heat dissipation problems. This causes short circuits and ultimately failures.
Variable-speed drives also differ from synchronous drive drives in that they provide a motor control signal as soon as the device senses a rotation shift and emits a pulse sequence, rather than waiting for a commanded signal. This provides more freedom and allows for different power conversion product loads to be supported at the same time. Some of the benefits of this are that there is no requirement for an encasement device to limit the number of drives supported, there is no requirement for an external power conversion product to convert the power into the appropriate voltage or current, and there is a possibility that two or more drives can be operated at the same time without any loss of performance.
Speed application
A variable speed drive can be implemented into an application in a variety of ways. One way is with a synchronous or linear control system. This can either be accomplished directly through a series of resistors controlling the drive’s rotation speed. At pre-determined frequencies or through a series of sensors feeding the drive with signals at predetermined frequency intervals. The advantage of this type of system is that the user can program. The drive to run at any desired frequency. And in most cases, there are no frequency limitations. Because the signal can be programmed so that it feeds at a higher frequency when the sensorless control. Is in operation and then slows down as the sensorless control begins to shut down.
Sensor based
Synchronous control systems use an AC electric motor. Typically a synchronous VFDs is coupled with an interface chip that interfaces to the control motor. The advantage of this type of system is that there are no frequency limits. Since the signals can be programmed so that they feed at any desired frequency. And there are also generally less wear and tear on the motors or drive heads. These systems are used primarily in applications where high reliability and ease of operation are critical. Such as military applications, medical imaging, aerospace applications, and manufacturing automation. There are currently a number of completely standalone. U.S.-based manufacturers of this type of drive and the leading supplier of these drives is Power Elf. Other well-known manufacturers include K&N, SEMG, Go Rhino and Analog Products Corporation.
