Power inverter for driving alternating current loads

A power inverter for converting AC line power to DC power comprising:

• a load;
• a high frequency power supply for driving said load;
• a half bridge inverter for converting DC power to a high frequency square wave;
• a resonate network having at least one inductor and one capacitor coupled between said half bridge inverter and said load;
• said resonate network connected with said half bridge inverter for converting said high frequency square wave to a sine wave;
• a microprocessor connected to said half bridge inverter for driving said half bridge inverter at an appropriate frequency;
• a feedback circuit for conveying voltage and current levels to said microprocessor from said load including software incorporated in said microprocessor whereby said voltage and current levels determine if any problems exist in operation of said load and which compensates for causes of any problems or alternately to shut down power supplied to said load or alternately to multiply said voltage and current levels to compute total power in watts supplied to said load and to adjust the frequency to maintain the required power in said load;
• said load includes at least one fluorescent lamp;
• said fluorescent lamp has separately driven heater cathodes and the amount of current currently used to drive at least one heater cathode is fed back to said microprocessor;
• said microprocessor contains software sensing if the high heater current in said lamp starting process has begun as when a ballast is first turned “on” or when said lamp is inserted with the power already applied (relamping hot);
• a software program in said microprocessor that monitors said heater cathode current to determine if said heater cathodes are properly heated (amount of current driving said heater cathodes has dropped);
• and
• said software program operates to then adjust the frequency such as to cause the voltage across said fluorescent lamps to rise until lamp ignition is accomplished.