Welding power supply with digital controller
A welding power supply including power conversion circuitry adapted to receive a primary source of power, to utilize one or more power semiconductor switches to chop the primary source of power, and to convert the chopped power to a welding output is provided. The provided welding power supply includes a pulse width modulated (PWM) digital controller including gate drive circuitry that generates a PWM output signal that controls the switching of the one or more power semiconductor switches. The PWM output signal includes a duty cycle term corrected for one or more sources of error in the welding system.
1. A welding power supply, comprising:
power conversion circuitry comprising one or more power semiconductor switches, wherein the power conversion circuitry is configured to receive power from a primary source and to switch the one or more power semiconductor switches between an ON configuration and an OFF configuration to convert the received power to a welding output; and
a pulse width modulated (PWM) digital controller coupled to the power conversion circuitry and configured to receive one or more analog signals, to generate an error signal indicative of a steady state error between a commanded current level and an actual output current level based at least in part on the one or more analog signals, and to calculate a duty cycle term for control of switching of the one or more semiconductor switches based at least in part on the generated error signal.
2. The welding power supply of claim 1 , wherein the duty cycle term is calculated by computing an integral term configured to correct for the steady state error between the commanded current level and the actual output current level.
3. The welding power supply of claim 2 , wherein the PWM digital controller is configured to selectively implement the integral term based at least in part on the error signal.
4. The welding power supply of claim 2 , wherein the PWM digital controller is configured to selectively implement the integral term for certain time periods.
5. The welding power supply of claim 2 , wherein the PWM digital controller is configured to reset the integral term during certain operating conditions.
6. The welding power supply of claim 1 , wherein the PWM controller is configured to limit the duty cycle term to at least one of a preset minimum value and a preset maximum value.
7. The welding power supply of claim 1 , wherein the power conversion circuitry comprises an inverter-type power supply that comprises at least one of a forward circuit, a full bridge inverter, a half bridge inverter, and a flyback circuit.
8. The welding power supply of claim 1 , wherein the one or more analog signals comprise the commanded current level.
9. The welding power supply of claim 1 , wherein the one or more analog signals comprise a current feedback signal.
10. The welding power supply of claim 1 , wherein the one or more analog signals comprise a voltage feedback signal.
11. The welding power supply of claim 1 , wherein the duty cycle term is corrected for a gate drive delay associated with the one or more power semiconductor switches.
12. The welding power supply of claim 1 , wherein the duty cycle term is corrected for a current-dependent or power-dependent loss comprising at least one of a diode voltage drop, a power semiconductor loss, and a leakage inductance.