Portable power supply

A power supply apparatus comprising:

• a housing;
• at least one battery receptacle provided on the housing for receiving at least one removable battery pack;
• a modified sine wave inverter configured to convert a direct-current (DO) signal from the at least one battery pack to an alternating current (AC) signal formed as a modified sine wave;
• and
• a controller configured to apply a pulse width modulation (PWM) signal to the inverter for shaping the modified sine wave, wherein for each full cycle of the modified sine wave, the controller is configured to set the duty cycle to approximately 100% within a first period corresponding to a peak area of the modified sine wave, set the duty cycle to less than approximately 100% but greater than approximately 0% within a second period in which the modified sine wave transitions from the peak to a zero-cross following the first period, set the duty cycle to a greater than 50% within a first half of the second period and sets the duty cycle to less than 50% within a second half of the second period and set the duty cycle to approximately 0% within a third period corresponding to the zero-cross of the modified sine wave following the second period.

A power supply apparatus, comprising:

• a housing;
• at least one battery receptacle provided on the housing for receiving at least one removable battery pack;
• a modified sine wave inverter configured to convert a direct-current (DC) signal from the at least one battery pack to an alternating current (AC) signal formed as a modified sine wave;
• a controller configured to apply a pulse-width modulation (PWM) signal to the inverter for shaping the modified sine wave, wherein for each full cycle of the modified sine wave, the controller is configured to set the duty cycle to approximately 100% within a first period corresponding to a peak area of the modified sine wave, set the duty cycle to less than approximately 100% but greater san approximately 0% within a second period in which the modified sine wave transitions from the peak to a zero-cross following the first period, and set the duty cycle to approximately 0% within a third period corresponding to the zero-cross of the modified sine wave following the second period;
• and
• a filter configured to shape the modified sine wave by integrating frequency components thereof, the modified sine wave as shaped by the filter comprising, within each full cycle of the modified sine wave, a first flat portion set to a peak voltage within the first period, at least one sloped portion within the second period, and a second flat portion set to zero within the third period.

A power supply apparatus, comprising:

• a housing;
• at least one battery receptacle provided on the housing for receiving at least one removable battery pack;
• a modified sine wave inverter configured to convert a direct-current (DC) signal from the at least one battery pack to an alternating-current (AC) signal in the form of a modified sine wave;
• a controller configured to apply a pulse-width modulation (PWM) signal to the inverter for shaping the modified sine wave;
• and
• a filter configured to shape the modified sine wave by integrating high frequency components thereof,
• wherein the modified sine wave, after modulation and filtering, comprises a first period corresponding to a peak area of the modified sine wave within which the modified sine wave is maintained at a peak voltage, a duration of the first period being more than half of a duration of a half cycle of the modified sine wave as defined between consecutive zero-crosses of the modified sine wave, a second period in which the modified sine wave is sloped to transition from the peak to a zero-cross following the first period, and a third period corresponding to the zero-cross of the modified sine wave following the second period within which the modified sine wave is maintained at zero, a duration of the third period being less than approximately 10% of the duration of the half cycle of the modified sine wave.

A power supply apparatus comprising:

• a housing;
• at least one battery receptacle provided on the housing for receiving at least one removable battery pack;
• a modified sine wave inverter configured to convert a direct-current (DC) signal from the at least one battery pack to an alternating current (AC) signal in the form of a modified sine wave;
• controller configured to apply a pulse-width modulation (PWM) signal to the inverter for shaping the modified sine wave and set the duty cycle to a greater than 50% within a first half of the second period and sets the duty cycle to less than 50% within a second half of the second period;
• and
• a filter configured to shape the modified sine wave by integrating high frequency components thereof,
• wherein the modified sine wave, after modulation and filtering, comprises a first period corresponding to a peak area of the modified sine wave within which the modified sine wave is maintained at a peak voltage.