Uninterruptible power supply with low leakage current

A uninterruptible power supply (UPS) having a controllable leakage current, comprising:

• a) a rectifier circuit for converting input AC power into DC power;
• b) an inverter circuit for converting DC power from the rectifier into AC output power, wherein the inverter circuit comprises at least one output switch;
• and
• c) a gate drive circuit for controlling the inverter output switch, wherein the gate drive circuit is responsive to leakage current and controls the inverter output switch such that a dV/dt rate of the output switch is reduced in response to increasing leakage current;
• further comprising a zero phase current transducer for sensing an amount of leakage current.

A uninterruptible power supply (UPS) having a controllable leakage current, comprising:

• a) a rectifier circuit for converting input AC power into DC power;
• b) an inverter circuit for converting DC power from the rectifier into AC output power, wherein the inverter circuit comprises at least one output switch;
• and
• c) a gate drive circuit for controlling the inverter output switch, wherein the gate drive circuit is responsive to leakage current and controls the inverter output switch such that a dV/dt rate of the output switch is reduced in response to increasing leakage current;
• wherein the gate drive circuit comprises:
• a) a I/V converter for converting a current from a leakage current sensor into a voltage, and
• b) a comparator for comparing the voltage from the I/V converter with a reference voltage.

An uninterruptible power supply (UPS) having a controllable leakage current, comprising:

• a) a rectifier circuit for converting input AC power into DC power;
• b) an inverter circuit for converting DC power from the rectifier into AC output power, wherein the inverter circuit comprises at least one output switch;
• c) a gate drive circuit for controlling the inverter output switch, wherein the gate drive circuit is responsive to leakage current and controls the inverter output switch such that a dV/dt rate of the output switch is reduced in response to increasing leakage current;
• and
• wherein the gate drive circuit controls the dV/dt rate of the output switch by varying a gate voltage;
• further comprising a zero phase current transducer for sensing an amount of leakage current.

An uninterruptible power supply (UPS) having a controllable leakage current, comprising:

• a) a rectifier circuit for converting input AC power into DC power;
• b) an inverter circuit for converting DC power from the rectifier into AC output power, wherein the inverter circuit comprises at least one output switch;
• c) a gate drive circuit for controlling the inverter output switch, wherein the gate drive circuit is responsive to leakage current and controls the inverter output switch such that a dV/dt rate of the output switch is reduced in response to increasing leakage current;
• and
• wherein the gate drive circuit controls the dV/dt rate of the output switch by varying a gate voltage;
• wherein the variable gate voltage is provided by a variable voltage DC-DC converter.