SMPS (Switch
Mode Power Supply) Control
This discussion refers to the Mill Table Drive Motor
Control
The circuit starts with a switch mode power supply that converts line
voltage to a DC voltage. This voltage powers
the green "On" lamp and is delivered to the motor direction switch. The power is returned to a power
switch (mosfet) and then to the SMPS negative after going through a sense resistor.
The mosfet switch is turned off and on by pulses coming from a variable pulse
width generator. The width of the on pulse is set by the "Speed Set"
potentiometer.
Fault Detection: This circuit compares the current going through the mosfet switch to
a fixed value and, if this value is exceeded, shuts down the pulse width
generator, turns off the mosfet, and turns on the yellow fault lamp. The
reset button permits the controller to be reactivated.
On-Board Control. The only control on the board sets the motor current
limit which, if exceeded, shuts down the mosfet.
|
|
