Emergency power supply

Abstract

According to the present invention, an emergency power supply to be coupled to an electric power source providing an incoming AC signal may include an input/output terminal, a battery with a DC voltage, a rectifier coupled directly to the input/output terminal and connected to the battery, an inverter coupled directly to the input/output terminal and connected to the battery, and a control circuit coupled to the rectifier and the inverter so that in a first operational mode the rectifier is coupled to the battery to rectify an incoming AC signal at the input/output terminal to charge the battery and the inverter is decoupled from the battery, and in a second operational mode the inverter is coupled to the battery to invert the DC voltage to provide an outgoing AC signal at the input/output terminal and the rectifier is decoupled from the battery.

I claim:  
     
         1 . An emergency power supply coupled to an electric power source providing an incoming AC signal, the emergency power supply comprising: 
 an input/output terminal;    a battery with a DC voltage;    a rectifier coupled directly to the input/output terminal and connected to the battery;    an inverter coupled directly to the input/output terminal and connected to the battery; and    a control circuit coupled to the rectifier and the inverter so that in a first operational mode the rectifier is coupled to the battery to rectify an incoming AC signal at the input/output terminal to charge the battery and the inverter is decoupled from the battery, and in a second operational mode the inverter is coupled to the battery to invert the DC voltage to provide an outgoing AC signal at the input/output terminal and the rectifier is decoupled from the battery.    
     
     
         2 . The emergency power supply according to  claim 1 , wherein the rectifier further comprises: 
 a first diode with a first terminal coupled to the input/output terminal and a second terminal connected to the battery;    a second diode with a first terminal coupled to the input/output terminal and a second terminal connected to the battery;    a third diode with a first terminal connected to the battery and a second terminal coupled to the input/output terminal; and    a fourth diode with a first terminal connected to the battery and a second terminal coupled to the input/output terminal.    
     
     
         3 . The emergency power supply according to  claim 1 , wherein the inverter further comprises: 
 a first switching element with a first terminal coupled to the input/output terminal and a second terminal connected to the battery;    a second switching element with a first terminal connected to the battery and a second terminal coupled to the input/output terminal;    a third switching element with a first terminal coupled to the input/output terminal and a second terminal connected to the battery;    a fourth switching element with a first terminal coupled to the input/output terminal and a second terminal connected to the battery; and    the control circuit coupled to the first, second, third and fourth transistors so that the first, second, third and fourth transistors are switched to provide an alternating current signal on the input/output terminal from the DC voltage.    
     
     
         4 . The emergency power supply according to  claim 3 , wherein the rectifier further comprises the first, second, third, and fourth switching elements, the control circuit coupled to the first, second, third and fourth switching elements so that the first, second, third and fourth switching elements are switched to rectify the AC signal to provide a direct current signal to charge the battery.  
     
     
         5 . The emergency power supply according to  claim 3 , wherein the first, second, third, and fourth switching elements are transistors.  
     
     
         6 . The emergency power supply according to  claim 5 , wherein the first, second, third and fourth switching elements are MOSFET transistors having an internal diode.  
     
     
         7 . The emergency power supply according to  claim 6 , wherein the rectifier further comprises: 
 a first diode connected with a first terminal coupled to the input/output terminal and a second terminal connected to the battery;    a second diode connected with a first terminal coupled to the input/output terminal and a second terminal connected to the battery;    the internal diode of the first switching element; and    the internal diode of the third switching element.    
     
     
         8 . An emergency power supply according to  claim 5 , wherein the transistors are insulated gate transistors.  
     
     
         9 . An emergency power supply according to  claim 5 , wherein the transistors are bipolar transistors.  
     
     
         10 . The emergency power supply according to  claim 1 , wherein the control circuit further comprises: 
 a sine-wave generator;    a sawtooth generator; and    a comparator coupled to the sine-wave generator and the sawtooth waveform generator to provide a pulse-width modulated signal to control the inverter.