Uninterruptible power supply apparatus
View Patent ↗The present uninterruptible power supply apparatus includes a converter ( 5 ) configured to convert AC power into DC power; an inverter ( 10 ) configured to convert DC power into AC power and supply the converted AC power to a load ( 24 ); and a control device ( 18 ) configured to control the converter ( 5 ) and the inverter ( 10 ). The control device ( 18 ) is configured to execute a mode selected from a sinusoidal wave output mode and a waveform distortion generation mode. In the sinusoidal wave output mode, an AC voltage (VO) with a sinusoidal waveform and with no waveform distortion is supplied to the load ( 24 ). In the waveform distortion generation mode, an AC voltage (VO) with waveform distortion within an allowable range for the load ( 24 ) is supplied to the load ( 24 ).
1. An uninterruptible power supply apparatus comprising:
a converter configured to convert AC power supplied from a commercial AC power source into DC power;
an inverter configured to convert DC power into AC power and supply the AC power to a load; and
a control device configured to control the converter and the inverter,
during a normal time when the AC power is supplied from the commercial AC power source, the DC power generated in the converter being supplied to the inverter and stored in a power storage device, and during a power failure time when supply of the AC power from the commercial AC power source is stopped, the DC power in the power storage device being supplied to the inverter,
the control device being configured to execute a mode selected from a first mode and a second mode, in the first mode, a first AC voltage with a sinusoidal waveform and with no waveform distortion being supplied to the load, and in the second mode, a second AC voltage with a waveform distortion within an allowable range for the load being supplied to the load,
the control device being configured to:
when the first mode is selected during the normal time, control the converter to output a first DC voltage and control the inverter to output the first AC voltage with a sinusoidal waveform and with an amplitude smaller than one-half of the first DC voltage; and
when the second mode is selected during the normal time, control the converter to output a second DC voltage smaller than the first DC voltage and control the inverter to output the second AC voltage with a sinusoidal waveform and with an amplitude larger than one-half of the second DC voltage.
2. The uninterruptible power supply apparatus according to claim 1 , wherein the uninterruptible power supply apparatus has an efficiency that is higher during execution of the second mode than during execution of the first mode.
3. The uninterruptible power supply apparatus according to claim 1 , wherein the second AC voltage with the waveform distortion has a trapezoidal waveform.
4. The uninterruptible power supply apparatus according to claim 1 , further comprising a bidirectional chopper configured to supply the DC power generated in the converter to the power storage device during the normal time, and supply the DC power in the power storage device to the inverter during the power failure time.
5. The uninterruptible power supply apparatus according to claim 1 , wherein the control device is configured to set a switching frequency of the inverter to be smaller when the second mode is selected than when the first mode is selected.
6. An uninterruptible power supply apparatus comprising:
a converter configured to convert AC power supplied from a commercial AC power source into DC power;
an inverter configured to convert DC power into AC power and supply the AC power to a load; and
a control device configured to control the converter and the inverter,
during a normal time when the AC power is supplied from the commercial AC power source, the DC power generated in the converter being supplied to the inverter and stored in a power storage device, and during a power failure time when supply of the AC power from the commercial AC power source is stopped, the DC power in the power storage device being supplied to the inverter,
the control device being configured to execute a mode selected from a first mode and a second mode, in the first mode, a first AC voltage with a sinusoidal waveform and with no waveform distortion being supplied to the load, and in the second mode, a second AC voltage with a waveform distortion within an allowable range for the load being supplied to the load,
the load being configured to receive an AC voltage within a range of allowable input voltage to consume constant AC power,
the uninterruptible power supply apparatus having an efficiency that is maximized when a ratio of a load capacity to a rated capacity of the uninterruptible power supply apparatus is a predetermined value,
the control device being configured to control an output voltage of the inverter within the range of allowable input voltage so as to increase the efficiency, when the second mode is selected and when the ratio of the load capacity to the rated capacity is different from the predetermined value.
7. The uninterruptible power supply apparatus according to claim 6 , wherein the control device is configured to decrease an output voltage of the inverter within the range of allowable input voltage of the load and increase a load current so as to increase the efficiency, when the ratio of the load capacity to the rated capacity is lower than the predetermined value.
8. The uninterruptible power supply apparatus according to claim 6 , wherein the control device is configured to increase an output voltage of the inverter within the range of allowable input voltage and decrease a load current so as to increase the efficiency, when the ratio of the load capacity to the rated capacity is higher than the predetermined value.
9. The uninterruptible power supply apparatus according to claim 6 , wherein the control device is configured to set an output voltage of the inverter at a rated voltage when the control device controls the output voltage of the inverter and a load current is varied.
10. The uninterruptible power supply apparatus according to claim 6 , wherein the uninterruptible power supply apparatus has an efficiency that is higher during execution of the second mode than during execution of the first mode.
11. The uninterruptible power supply apparatus according to claim 6 , wherein the second AC voltage with the waveform distortion has a trapezoidal waveform.