KB Electronics, Inc. Manufactures and inventories over 200 different models of our off the shelf Variable Frequency Digital and Hybrid AC Drives (AC Inverters), Variable Speed DC Motor Controls, Brushless DC Drives, Battery DC to DC Controls and Triac Fan Controls.

Speed Control Methods of Various Types of Kazuya SHIRAHATA Oriental Motor Co., Ltd. Offers a wide variety of speed control motors. Our speed control motor packages include the motor, the driver (controller), and a potentiometer which allows for easy speed control adjustment. There are three speed control motor product groups. Who are you school episode 14 sub indo pitch. The 'AC speed control motor unit' that uses the most popular single-phase capacitor-run induction motor, the small and highly efficient 'Brushless DC motor unit', and the 'Inverter unit' that combines a three-phase induction motor with a small inverter. This article explains the structure, principle of speed control and the features of each product group, and our standard products are introduced.

Introduction A large number of motors are being used for general purposes in our surroundings from house-hold equipment to machine tools in industrial facilities. The electric motor is now a necessary and indispensable source of power in many industries. The function and the performance required for these motors are wide-ranging. When focusing attention on the speed control segment of the motor market, servo and stepper motors control their speed with a pulse train, while the induction motor and the brushless DC motor control speed with an external resistor and/or DC voltage.

This article explains the structure, the speed control principle, and the features of the following three product groups that can control the speed relatively easily by using an analog input. • AC speed control motor & gear motors • Brushless DC motor & gear motors • Inverter unit 2. Speed control methods of the various speed control motors The output control method of a speed control circuit can be divided roughly into two groups: phase control and inverter control, which make up the product groups shown in Fig. 1 Classification of Speed Control Motors 2.1.

AC Speed Control Motors 2.1.1. Construction of Motor As shown in Fig. 2, the construction of the single phase and three-phase induction motors includes a stator where the primary winding is wound and a basket-shaped, solid aluminum die cast rotor. The rotor is low-cost because the structure is simple and does not use a magnet. 2 Construction of Induction Motor When the speed of this motor is to be controlled, a tacho-generator is used to detect the speed and is attached to the motor as shown in Fig.

The tacho-generator is made of a magnet connected directly to the motor shaft and a stator coil that detects the magnetic poles, and generates an AC voltage at 12 cycles per revolution. Since this voltage and frequency increase with a rise of the rotational speed, the rotational speed of the motor is controlled based on this signal. 3 AC Speed Control Motor System 2.1.2. Principle of Speed Control Rotational speed N of an induction motor can be shown by the expression (1). When the voltage applied to the motor is increased and decreased, the slip s changes, then the rotational speed N will change.

N= 120 f (1- s)/ P  (1) N: Rotational speed [r/min] F: Frequency 〔Hz〕 P: Number of poles of a motor S: Slip In the case of an induction motor as shown in Fig. 4, a stable range and an unstable range exists in the Rotational Speed - Torque curve. Since it is impossible to reliably operate in the unstable range, simple voltage control (open loop control) is limited to controlling the speed in a narrow range like, N1~N3 in Fig. To make it possible to operate reliably even in the above-mentioned unstable range, it is necessary to detect the rotational speed of the motor and use a voltage control mechanism (closed-loop control) that reduces the speed error when compared to a set value.

4 Rotational Speed - Torque Characteristics of Induction Motors Fig. 5 Simple Voltage Control Available voltage control methods include control by a transformer or by phase control. 6 shows when voltage is controlled by using a transformer. This method is not so easy to do with an AC speed control motor. Alternately, the AC voltage can be adjusted by setting the ON/OFF time of every half cycle of the AC voltage (50 or 60Hz) applied to the motor using a switching element (thyristor or triac) that can directly turn on and off the AC voltage as shown Fig.

Speed control is obtained by the phase control method by controlling the r.m.s. Value of the AC voltage.

6 Voltage Change by Transformer Fig. 7 Voltage Change by Phase Control Fig. 8 Triac Control Circuit This AC speed control method can provide steady speed control by closed-loop phase control even in the unstable range. 9 shows the configuration of the speed control system for an AC speed control motor in a block diagram. 9 Block Diagram of AC Speed Control Motor System Fig. 10 Waveform for Each Block Fig. 10 shows the waveforms of each block.

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