Vacuum cleaner having a dual power supply

Abstract

A vacuum cleaner comprising a vacuum motor and a power supply. The power supply comprises input terminals for connection to an AC source, output terminals connected to the vacuum motor, an AC-to-DC stage, and a battery. The AC-to-DC stage converts alternating current drawn from the AC source into direct current that is supplied to the battery and the vacuum motor. The power supply operates in a first mode when disconnected from the AC source and a second mode when connected to the AC source. In the second mode, the vacuum motor operates in either a low-power state or a high-power state. In the low-power state, the vacuum motor and the battery each draw power from the AC source such that the battery charges. When the vacuum motor operates in the high-power state, the vacuum motor draws power from both the AC source and the battery such that battery discharges.

1 . A vacuum cleaner comprising a vacuum motor and a power supply, wherein:
 the power supply comprises input terminals for connection to an AC source, output terminals connected to the vacuum motor, an AC-to-DC stage, and a battery;   the AC-to-DC stage converts alternating current drawn from the AC source into direct current that is supplied to the battery and the vacuum motor;   the power supply operates in a first mode when disconnected from the AC source and a second mode when connected to the AC source;   when the power supply operates in the first mode, the vacuum motor draws power from the battery only; and   when the power supply operates in the second mode:
 the vacuum motor operates in one of a low-power state and a high-power state; 
 the vacuum motor and the battery each draw power from the AC source when the vacuum motor operates in the low-power state such that the battery charges; and 
 the vacuum motor draws power from both the AC source and the battery when the vacuum motor operates in the high-power state such that battery discharges. 
   
     
     
         2 . The vacuum cleaner of  claim 1 , wherein the power drawn by the vacuum motor when the power supply operates in the second mode is no less than the power drawn by the vacuum motor when the power supply operates in the first mode. 
     
     
         3 . The vacuum cleaner of  claim 1 , wherein the power drawn by the vacuum motor is M when the power supply operates in the first mode, the power drawn by the vacuum motor is N when the power supply operates in the second mode and the vacuum motor operates in the low-power state, the power drawn by the vacuum motor is P when the power supply operates in the second mode and the vacuum motor operates in the high-power state, P is greater than both M and N, and N is greater than or equal to M. 
     
     
         4 . The vacuum cleaner of  claim 1 , wherein the power drawn from the battery when the power supply operates in the first mode is at least 200 W. 
     
     
         5 . The vacuum cleaner of  claim 1 , wherein the AC-to-DC stage and the battery are connected in parallel between the input terminals and the output terminals. 
     
     
         6 . The vacuum cleaner of  claim 5 , wherein the AC-to-DC stage outputs a current having a periodic waveform with a ripple of at least 50%. 
     
     
         7 . The vacuum cleaner of  claim 1 , wherein the AC-to-DC stage adjusts the power drawn from the AC source in response to changes in the voltage of the battery. 
     
     
         8 . The vacuum cleaner of  claim 7 , wherein when the voltage of the battery exceeds a threshold, the AC-to-DC stage decreases the power drawn from the AC source such that the power drawn from the AC source by the AC-to-DC stage is less than the power drawn from the power supply by the vacuum motor. 
     
     
         9 . The vacuum cleaner of  claim 8 , wherein, when the voltage of the battery drops below a further threshold, the AC-to-DC stage increases the power drawn from the AC source such that the power drawn from the AC source by the AC-to-DC stage is greater than the power drawn from the power supply by the vacuum motor. 
     
     
         10 . The vacuum cleaner of  claim 1 , wherein the AC-to-DC stage comprises an AC-to-DC converter for rectifying the current drawn from the AC source, a power factor correction (PFC) circuit for regulating the rectified current drawn from the AC source, and a step-down DC-to-DC converter for lowering the voltage of the rectified current.