Single phase input detection and power source protection
A welding-type power supply that receives alternating current (AC) input power and converts the AC input power to direct current (DC) power to provide power for welding tools. The welding-type power supply is configured to detect whether single phase AC power or three-phase AC power is connected to the input of welding-type power supply. Single phase input power may be detected by sampling ripple voltage of the DC power, either synchronously with the AC input power or synchronously with a signal generated by an output of the welding-type power supply.
1. A welding-type power supply, comprising:
an input configured to receive three-phase alternating current (AC) power;
a rectifier circuit configured to convert the three-phase AC power received at the input to direct current (DC) power at a DC power bus; and
a processor configured to:
monitor a ripple voltage of the DC power at the DC power bus; and
identify one or more voltage samples of the ripple voltage;
detect whether a single-phase AC power source or a three-phase power source is coupled to the input based on the one or more voltage samples of the ripple voltage of the DC power using a voltage sampling timing based on a frequency and voltage of AC power connected to the input.
2. The welding-type power supply of claim 1 , wherein the processor is configured to compare voltage differences between the one or more voltage samples of the DC power bus to detect whether a single-phase AC power source or a three-phase power source is coupled to the input.
3. The welding-type power supply of claim 1 , wherein the processor is configured to:
detect zero-crossings of at least one leg of the AC input power; and
monitor the one or more voltage samples of the DC power bus at predetermined periods of time after detecting a zero-crossing.
4. The welding-type power supply of claim 1 , wherein the processor is configured to power down the welding-type power supply in response to detecting that a single-phase AC power source is coupled to the input.
5. The welding-type power supply of claim 1 , further comprising a power inverter configured to convert the DC power at the DC power bus to output power, wherein the processor is configured to shut down the power inverter in response to detecting that a single-phase AC power source is coupled to the input.
6. The welding-type power supply of claim 1 , further comprising a power inverter configured to convert the DC power at the DC power bus to output power, wherein the processor is configured to limit one of the output current or duty cycle of the power inverter in response to detecting that a single-phase AC power source is coupled to the input.
7. The welding-type power supply of claim 1 , wherein the processor is configured to signal an alarm in response to detecting that a single-phase AC power source is coupled to the input.
8. A welding-type power supply, comprising:
an input configured to receive three-phase alternating current (AC) power;
a rectifier circuit configured to convert the AC power received at the input to direct current (DC) power at a DC power bus; and
a processor configured to:
monitor a frequency of the AC power received at the input;
sample, synchronously with the frequency of the AC power received at the input, one or more pairs of voltage measurements of a ripple voltage on the DC power bus, each pair comprising:
a first measured voltage of the DC power bus; and
a second measured voltage of the DC power bus, the second measured voltage of the DC power bus sampled a first period of time after the first measured voltage, the first period of time based on the frequency of the AC power received at the input;
determine voltage differences for the sampled one or more pairs of voltage measurements;
compute a filtered voltage difference between the sampled one or more pairs of voltage measurements; and
compare the filtered voltage difference to a threshold voltage difference; and
determine that a single-phase AC power source is coupled to the input if the filtered voltage difference is above the threshold voltage difference, and determine that a three-phase AC power source is coupled to the input if the filtered voltage difference is below the threshold voltage difference.
9. The welding-type power supply of claim 8 , wherein the processor is further configured to detect a period of the AC power received at the input, and wherein the first time period is one sixth of the period of the AC power received at the input.
10. The welding-type power supply of claim 8 , wherein the processor is configured to monitor the AC power received at the input via monitoring one leg of the AC power received at the input.
11. The welding-type power supply of claim 10 , wherein the processor is configured to:
detect zero-crossings of the monitored leg of the AC power received at the input; and
for each sampled pair of voltage measurements, sample the first measured voltage a second period of time after detecting a corresponding one of the zero-crossings.
12. The welding-type power supply of claim 8 , wherein the processor is configured to power down the welding-type power supply in response to detecting that a single-phase AC power source is coupled to the input.
13. The welding-type power supply of claim 8 , further comprising a power inverter configured to convert the DC power at the DC power bus to output power, wherein the processor is configured to shut down the power inverter in response to detecting that a single-phase AC power source is coupled to the input.
14. The welding-type power supply of claim 8 , further comprising a power inverter configured to convert the DC power at the DC power bus to output power, wherein the processor is configured to limit one of the output current or duty cycle of the power inverter in response to detecting that a single-phase AC power source is coupled to the input.
15. The welding-type power supply of claim 8 , wherein the processor is configured to signal an alarm in response to detecting that a single-phase AC power source is coupled to the input.