Voltase hobby: motor

Wednesday, November 12, 2014

NJU7365 bassed DC brushless motor driver circuit with explanation

A very simple single phase dc brushless motor driver electronic circuit project can be designed using NJU7365 DC brushless motor driver ic manufactured by New Japan radio Co. LTD .

The NJU7365 is a single phase motor driver ic that include in package MOS FET motor driver , direct PWM input , FG output and thermal shut down circuit . The driver is capable of 1000mA maximum output current and continuous current of 350 mA . This motor driver require few external electronic parts and can be powered from dc power supply from 2 to 5.5 volts .

Tuesday, September 9, 2014

Two Basic Motor Speed Controllers

Here are two simple 12V DC motor speed controllers that can be built for just a few dollars. They exploit the fact that the rotational speed of a DC motor is directly proportional to the mean value of its supply voltage. The first schema shows how variable voltage speed control can be obtained via a potentiometer (VR1) and compound emitter follower (Q1 & Q2). With this arrangement, the motor’s DC voltage can be varied from 0V to about 12V. This type of schema gives good speed control and self-regulation at medium to high speeds but very poor low-speed control and slow starts. The second schema uses a switchmode technique to vary motor speed.

Circuit diagram:

basic-motor-speed-controller-schema-diagram1

Fig.1: a very simple motor speed controller based on a compound emitter follower (Q1 & Q2).

Here a quad NOR gate (IC1) acts as a 50Hz astable multivibrator that generates a rectangular output. The mark-space ratio of the rectangular waveform is fully variable from 20:1 to 1:20 via potentiometer VR1. The output from the multivibrator drives the base of Q1, which in turn drives Q2 and the motor. The motor’s mean supply voltage (integrated over a 50Hz period) is thus fully variable with VR1 but is applied in the form of high-energy "pulses" with peak values of about 12V.

Two Basic Motor Speed Controllers Circuit diagram:

basic-motor-speed-controllers-schema-diagram2

Fig.2: this slightly more complicated schema gives better low speed control and higher torque.

This type of schema gives excellent full-range speed control and gives high motor torque, even at very low speeds. Its degree of speed self-regulation is proportional to the mean value of the applied voltage. Note that for most applications, the power transistor (Q2) in both diagram will need to be mounted on an appropriate heatsink.

Author: Ravi Sumithraarachchi - Copyright: Silicon Chip Electronics

Thursday, September 4, 2014

3 φ Full Wave Controlled Rectifier circuit to control DC Motor Speed

In the given Block and schema diagram of a 3 φ Full Wave Controlled Rectifier schema to control DC shunt motor is shown.

In this schema diagram the field and armature diagram are connected through three phase full wave Controlled rectifier schema.

In three phase supply, each phase is different form other one in 120°, therefore at each out put terminal a, b, & c give the following Sine wave voltage.

Through the three phase controlled rectifier, the three phase supply is converted to a DC and provided to the armature and field of the DC shunt motor.

Through the 3φ full wave Controlled Rectifier, the 3φ AC supply converted to a DC voltage and provide to the armature and field of the DC motor, which flow in shape of T_A (Armature Current) through the ckt (DC motor) due to this controlled Dc the motor start in low speed.

If the DC motor start through ordinary way, then an external resistance is connected in the armature ckt, these resistors in armature ckt controlled the speed of the motor, (Gradually decreases the resistance form the armature ckt) and when total resistance (Resistors) remove form the armature ckt, the motor is rotate at its full speed (RPM). The main purpose of the resistance with the armature ckt is that, to match armature current with internal current (emf) to decreased value.

In case of the controlled rectifiers the resistors are not connected because at motor starting time the SCR connected in armature ckt set the delay angle value ,that the armature resistance controlled the voltage drop in the armature. The armature controlled method is mostly used as compare to the field controlled method,

In armature controlled method the field voltage is kept constant, while the armatures voltages changes.

In the given ckt rectifier converted to the in put DC supply (Full wave) , the rectifier is consistof SCRs , the out put of the SCR is Directly apply to the Armature in a variable shape. The applied voltage can be change form the changing the firing angle of the SCR.

Friday, August 29, 2014

Motor driver L298 Circuit

DC motor driver with H-Bridge IC L293D

IC H Bridge DC motor driver L298 has two H-Bridge circuit in it, so it can be used to download the drive two DC motors. H Bridge DC motor driver L298 each can deliver currents up to 2A. However, in use, the H Bridge DC motor driver L298 can be used in parallel, so the ability to deliver the H Bridge DC motor driver L298 flow into 4A. The consequences of the installation of H Bridge L298 DC motor driver with the parallel mode, you need 2 pieces Bridge H L298 DC motor driver to control two DC motors using H bridge DC motor driver L298 in parallel mode.

H Bridge Pin IC L298 DC motor driver which is connected in parallel operation mode:

* OUT1 connected to OUT4.

* OUT2 OUT3 linked.

* IN1 is connected to IN4.

* IN2 connected to IN3.

* ENABLE ENABLE A linked to B.

OUT1/OUT4 and OUT2/OUT3 associated with DC motors to be controlled.

Please note that the output of the L298 does not have a safety diode. Thus, the need to add two diodes - flyback diodes, with appropriate current capability, at any point output.