Forward and reverse motor control circuit

#Forward and reverse motor control circuit drivers#
#Forward and reverse motor control circuit driver#
#Forward and reverse motor control circuit series#

Note that the two contactors must be electrically and mechanically interlocked so that they cannot be energized simultaneously.

#Forward and reverse motor control circuit series#

The return paths for both starter coils connect in series with the normally closed contacts of the overload relay so that if an overload occurs in either direction, the starter coils will be de-energized and the motor will come to a stop. Since the two motor starters control only one motor, only one set of overload relay heaters need be used. When the reverse contactor is energized, the power contacts connect line L1 to T3, line L2 to T2 and line е…ѓ to T1 at the motor. When the forward contactor is energized, power contacts connect line L1 to T1, line L2 to T2 and line е…ѓ to T3 at the motor. Each of the two different motor starters powers the motor with a different phase rotation. If a motor is to be driven in two directions, then it will require a Forward / Reverse motor starter, which has two three-pole horsepower-rated contactors rather than just one as in the conventional starter. This is known as reversing the phase rotation. Once two of the lines have been switched, the direction of the magnetic fields created in the motor will now cause the shaft to spin in the opposite direction. This can be done at the motor starter or at the motor itself. If a three-phase motor is to be driven in only one direction, and upon its initial energization it is found to be rotating opposite to what is desired, all that is needed is to interchange any two of the three line leads feeding the motor. Swapping out both the TIP120 and relay with higher-rated parts (readily available online) should let you build a much beefier version of this motor control fairly cheaply.Circuits 36 Forward/Reverse Control Circuits This may not work as well as a proper heatsink - but will definitely help. Just cut a 1'x1' piece of the can using scissors - bend up the sides a little, and drill an 5/32' hole to mount it. You can alternately make your own heatsink out of a piece of aluminum can. The heatsink should be installed on the transistor with the 'Enable' pin using a #6 bolt and nut (screw it on tight!). I've verified the Radio Shack 276-1363 heatsink can be installed withoutВ re-solderingВ everything (you may need to bend stuff a little). The TIP120 is rated at 5 amps - but will overheat without a heatsink if run this hard continuously. A TIP120 on its own provides a super-simple way to do single-direction motor control. This gives them much higher 'gain' - meaning they can use a very small current to switch a much larger current. These transistors are actually two transistors chained together into one. This project uses TIP120 'Darlington' transistors. I chose the one featured in this project since Radio Shack stocked it.

#Forward and reverse motor control circuit driver#

It should be possible to build a version of this driver that supports lower voltages by swapping out the relay with one having a lowerВ 'pickup' voltage. Fortunately - the component most likely to burn out is the transistor with the 'Enable' pin - so you're only out a $1.50.

#Forward and reverse motor control circuit drivers#

Unlike many commercial motor drivers - this driver does not have any 'protection' - so if you abuse it too much - it will fail.

It's rated at 130% of nominal - or 15.6v. The relay's coil seems to dictate the maximum voltage this circuit can handle.

If you're having problems with the controller refusing to reverse - it may be that your input voltage is too low. We'll go through all the connections one-by-one. This is listed as 9.6v - but I've found it to function properly as low as about 7.5v.Дon't worry if the schematic doesn't make total sense. The minimum voltage to drive this circuit is determined by the 'pickup' voltage of the relay. The enable pin may be switched on and off very quickly for PWM (pulse width modulation) speed control.Д«oth control pins are connected to the microcontroller via 220 Ohm resistors to limit current. The 'Base' of the second TIP120 is the 'Enable Pin' - turning it on causes the motor to actually run. This is used to turn the motor on and off. The 'Base' of the first TIP120 is the 'Direction Pin' - turning it on and off switches the direction of the motor.ДЄ second TIP120 switches power to common on the relay. Since the microcontroller can't quite produce enough current to drive the relay - a transistor (TIP120) is used to switch it on and off. This in effect reverses the wiring whenever the relay is turned on or off.

The motor is connected to both normally closed and normally open (in reverse) sides of the relay. This circuit uses a DPDT (Double Pole Double Throw) relay to switch which direction the motor is turning.