Universal Motor Control

[0h1001]

Hi,

I have a 110v 5amp universal drill motor. I wish to design a motor
controller which will allow speed and direction control, and interface at
TTL to a PIC uC. I can run the motors in AC or DC. The motor is a series
or universal type which requires the polarity to be switched at the coils in
order to change direction. There are 4 wires going to the motor, 2 for the
stator and 2 for the rotor coils. Shorting either side of the coils will
change the motor's direction.

I have looked at crydom.com solid state relays to switch coil
polarities, but it would required 6 relays for each motor. ( running on DC
and PWM the relay ) I also have looked at using igbt/mosfet combo, but I
would still need to find a way to change polarity at the coils...

Can anyone point me to any designs/schematics/appnotes available
somwhere on the web to accomplish this?

Cheers,
Steve

 

[CBarn24050]

I have looked at crydom.com solid state relays to switch coil
polarities, but it would required 6 relays for each motor. ( running on DC

Most people use a dpdt switch or relay.

 

[scada]

Hi,

I have a 110v 5amp universal drill motor. I wish to design a motor
controller which will allow speed and direction control, and interface at
TTL to a PIC uC. I can run the motors in AC or DC. The motor is a series
or universal type which requires the polarity to be switched at the coils in
order to change direction. There are 4 wires going to the motor, 2 for the
stator and 2 for the rotor coils. Shorting either side of the coils will
change the motor's direction.

I have looked at crydom.com solid state relays to switch coil
polarities, but it would required 6 relays for each motor. ( running on DC
and PWM the relay ) I also have looked at using igbt/mosfet combo, but I
would still need to find a way to change polarity at the coils...

Can anyone point me to any designs/schematics/appnotes available
somwhere on the web to accomplish this?

Cheers,
Steve

You want an "H Bridge controller" do a Google search....

 

[John Popelish]

Hi,

I have a 110v 5amp universal drill motor. I wish to design a motor
controller which will allow speed and direction control, and interface at
TTL to a PIC uC. I can run the motors in AC or DC. The motor is a series
or universal type which requires the polarity to be switched at the coils in
order to change direction. There are 4 wires going to the motor, 2 for the
stator and 2 for the rotor coils. Shorting either side of the coils will
change the motor's direction.

I have looked at crydom.com solid state relays to switch coil
polarities, but it would required 6 relays for each motor. ( running on DC
and PWM the relay ) I also have looked at using igbt/mosfet combo, but I
would still need to find a way to change polarity at the coils...

Can anyone point me to any designs/schematics/appnotes available
somwhere on the web to accomplish this?

Cheers,
Steve

I think the only way ot get something like smooth reversing control is
to put the armature in series with the power supply to an H bridge PWM
driver, and connect the output of the bridge to the filed (or switch
the field and armature). Coming up with an H bridge circuit that
handles such a variable supply situation will be fun. You are
beginning to see why universal motors are very rare in servo motor
applications.

 

[scada]

coils

You want an "H Bridge controller" do a Google search....

You could put a bridge rectifier between the Stator winding and the Rotor,
and run the motor on DC (AC input towards the Rotor, DC out to the Stator).
That way regardless of the polarity input to the motor, the Stator will only
see the polarity as you wired it. The downfall to this is that you will drop
1.4V to the Stator winding (.7 per diode *2), but that should not be a
problem at 110 VDC. Then you could feed the motor with an H bridge PWM
controller and have speed control and reverse functions!

 

[ACIT]

on but

You could put a bridge rectifier between the Stator winding and the Rotor,
and run the motor on DC (AC input towards the Rotor, DC out to the Stator).
That way regardless of the polarity input to the motor, the Stator will only
see the polarity as you wired it. The downfall to this is that you will drop
1.4V to the Stator winding (.7 per diode *2), but that should not be a
problem at 110 VDC. Then you could feed the motor with an H bridge PWM
controller and have speed control and reverse functions!

Thanks. I think you may be on to something. I'll do some diggin around to
try and understand exactly what you mean. I have 110vac to work with, so I
will run them at 90vdc or so. The drop in current is no problem. Keep me
posted if you have any schematics on this setup.

Cheers