Method of controlling an uninterruptible power supply apparatus

Abstract

A method of controlling an uninterruptible power supply apparatus (UPS) is provided. The UPS apparatus includes at least an AC input voltage, a DC input voltage and a single-phase AC/AC converter. The single-phase AC/AC converter includes an AC inductor, a bus capacitor, a boost arm, a common arm and a buck arm. The method includes steps of: controlling the bus voltage to have a DC component and full-wave rectifying component, and setting a bus voltage parameter K so that the bus voltage approaches to a full-wave rectifying voltage when K approaches to 1, wherein 0≦K≦1.

1 . A method of controlling an uninterruptible power supply apparatus having a bus voltage, an AC input voltage, a DC input voltage and a single-phase AC/AC converter, the single-phase AC/AC converter including an AC inductor, a bus capacitor, a boost arm, a common arm and a buck arm, the method comprising steps of: 
 (a) controlling the bus voltage to have a DC voltage and a full-wave rectifying voltage; and    (b) setting a bus voltage parameter K where 0≦K≦1, so that the bus voltage approaches to the DC voltage when K approaches to 0 and the bus voltage approaches to the full-wave rectifying voltage when K approaches to 1;    wherein when the AC input voltage is normal, the bus voltage is rectified via the single-phase AC/AC converter to output, and when the AC input voltage is abnormal, the DC input voltage is inverted via the single-phase AC/AC converter to output.    
   
   
       2 . The method according to  claim 1 , wherein the uninterruptible power supply apparatus further comprises a switch set, an AC filter and a load.  
   
   
       3 . The method according to  claim 2 , wherein in step (b) when the load is light-load, the bus voltage parameter K is increased to approach to 1, and when the load is heavy-load, the bus voltage parameter K is decreased to approach to 0.  
   
   
       4 . The method according to  claim 1 , further comprising a step of (c) setting a duty cycle d 3  of the buck arm, a duty cycle d 1  of the boost arm and a voltage gain M of the single-phase AC/AC converter to meet an equation of d 3 =M(1−d 1 ).  
   
   
       5 . The method according to  claim 4 , further comprising a step of (d) defining a wave function F of the bus voltage to meet the following conditions; 
 when |sin(wt)|<K, F=|sin(wt)|; and    when |sin(wt)|≧K, F=K, wherein w is an angular velocity, and t is a passing time.    
   
   
       6 . The method according to  claim 5 , wherein the duty cycle d 1  of the boost arm, the voltage gain M of the single-phase AC/AC converter, the bus voltage parameter K and the wave function of the bus voltage F meet an equation d 1 =(2−M)KF.  
   
   
       7 . The method according to  claim 6 , further comprising a step of (d) of controlling one of boost arm and the buck arm to operate under a pulse-width-modulation mode when sin(wt)>1/K, and controlling both of the boost arm and the buck arm to operate under pulse-width-modulation mode when sin(wt)<1/K.  
   
   
       8 . A method of controlling an uninterruptible power supply apparatus having a bus voltage, an AC input voltage, a DC input voltage and a single-phase AC/AC converter comprising an AC inductor, a bus capacitor, a boost arm, a common arm and a buck arm, the method comprising steps of: 
 (a) controlling the bus voltage and making the bus voltage have a waveform including a low slope segment and a full-wave rectifying segment;    (b) setting a bus voltage parameter K representing an amount of an output power, wherein 0≦K≦1; and    (c) regulating a proportion of the low slope segment and the full-wave rectifying segment within a full cycle based on a variation of the bus voltage parameter K, the waveform of the bus voltage during the low slope segment having a slope lower than a further slope of the waveform of the bus voltage during the full-wave rectifying segment;    wherein, when the AC input voltage is normal, the bus voltage is rectified via the single-phase AC/AC converter to output, and when the AC input voltage is abnormal, the DC input voltage is inverted via the single-phase AC/AC converter to output.    
   
   
       9 . The method according to  claim 8 , wherein an average voltage value during the full-wave rectifying segment is larger than that during the low slope segment.  
   
   
       10 . The method according to  claim 8 , further comprising a step of (d) of increasing a duration of the low slope segment and decreasing a duration of the full-wave rectifying segment when the output power decreases.  
   
   
       11 . The method according to  claim 8 , wherein the waveform of the bus voltage is obtained by regulating duty cycles of the boost arm and the buck arm.  
   
   
       12 . A method of controlling an uninterruptible power supply apparatus having a bus voltage, an AC input voltage, a DC voltage and an AC/AC converter, comprising steps of: 
 (a) controlling the bus voltage to have a DC voltage and a full-wave rectifying voltage; and    (b) setting a bus voltage parameter K, where 0≦K≦1, so that the bus voltage approaches to the DC voltage when K approaches to 0 and the bus voltage approaches to the full-wave rectifying voltage when K approaches to 1.