Uninterruptible power supply

In an uninterruptible power supply for transmitting voltage varying interruptible AC electrical power received from a AC input source to a load through a transformer during availability of said power from said AC input source and supplying said load with AC electrical power through said transformer from an auxiliary source during interruption of said power from said AC input source, a method of transferring between sensing the voltage of said electrical power transmitted to said load and sensing the voltage of said received electrical power while supplying said load with AC electrical power, said method comprising:

• A. connecting AC input terminals to said AC input source and connecting load terminals to said load;
• B. selecting an AC sample signal from one of said AC electrical power received at said AC input terminals and said AC electrical power transmitted to said load terminals, said selecting occurring respectively in response to receipt of a switch signal of a standby state or a normal state;
• C. producing a transfer signal of a normal state while the voltage of said AC sample signal continues between certain voltage limits indicating availability of said AC input source AC electrical power and producing a transfer signal of a standby state when the voltage of said AC sample signal exceeds said certain voltage limits indicating interruption of said AC input source of AC electrical power;
• and
• D. producing said switch signal of said normal state to select passing said AC sample signal from said load terminals while said transfer signal continues in said one normal and producing said switch signal of said standby state to select passing said AC sample signal from said AC input terminals while said transfer signal continues in said standby state.

In an uninterruptible power supply for transmitting interruptible AC electrical power from AC input terminals to load terminals through a transformer during availability of said power from said AC input terminals and supplying said load terminals with AC electrical power through said transformer from an auxiliary source during interruption of said power from said AC input terminals, and said supply selecting an AC sample signal from said load terminals and from said AC input terminals, the voltage of which represents the availability of said interruptible AC electrical power, an AC voltage monitor for indicating the value of the voltage of said analog AC sample signal applied thereto relative to certain voltage limits, which define availability of said electrical power from said AC input terminals, said monitor comprising:

• A. high threshold means for producing an analog AC high voltage limit signal in phase with said AC sample signal, said AC high voltage limit signal attaining a maximum absolute voltage of said ceratin limits;
• B. low threshold means for producing an AC analog low voltage limit signal in phase with said AC sample signal, said AC low voltage limit signal attaining a minimum absolute voltage of said certain limits;
• C. voltage comparator means for producing at least one voltage comparator signal that continues in phase with said AC sample signal while the voltage of said AC sample signal continues between said AC high and low voltage limit signals, and that goes out of phase with said AC sample signal when the voltage of said AC sample signal exceeds one of said AC high and low voltage limit signals;
• and
• D. phase comparator means for producing a transfer signal of a normal state while said voltage comparator signal continues in phase with said AC sample signal and a transfer signal of a standby state when said voltage comparator signal goes out of phase with said AC sample signal, said transfer signal of said normal state indicating that said AC sample signal continues within said certain voltage limits and said transfer signal of said standby state indicating that said AC sample signal exceeds said certain voltage limits.

In an uninterruptible power supply for transmitting interruptible AC electrical power from AC input terminals to load terminals through a transformer during availability of said power from said AC input terminals and supplying said load terminals with AC electrical power through said transformer from an auxiliary source during interruption of said power from said AC input terminals, and said supply selecting an AC sample signal from said load terminals and from said AC input terminals, the voltage of which represents availability of said AC electrical power, a method for indicating the value of the voltage of said AC sample signal applied thereto relative to certain voltage limits, which define availability of said electrical power from said AC input terminals, said method comprising:

• A. producing an analog AC high voltage limit voltage signal in phase with said AC sample signal, said AC high voltage signal attaining a maximum absolute voltage of said certain voltage limits;
• B. producing an analog AC low voltage limit signal in phase with said AC sample signal, said AC low voltage limit signal attaining a minimum absolute voltage of said certain voltage limits;
• C. producing at least one voltage comparator signal that continues in phase with said AC sample signal while the voltage of said AC sample signal continues between said AC high and low voltage limit signals, and that goes out of phase with said AC sample signal when the voltage of said AC sample signal exceeds one of said AC high and low voltage limit signals;
• and
• D. producing a transfer signal of a normal state while said voltage comparator signal continues in phase with said AC sample signal and a transfer signal of a standby state when said voltage comparator signal goes out of phase with said AC sample signal, said transfer signal of said normal state indicating that said AC sample signal continues within said certain voltage limits and said transfer signal of said standby state indicating that said AC sample signal exceeds said certain voltage limits.

In an uninterruptible power supply for transmitting interruptible AC electrical power from AC input terminals to load terminals through a transformer during availability of said power from said AC input terminals, and supplying said load terminals with AC electrical power through said transformer from a standby source during interruption of said power from said AC input terminals, the supply selecting an AC sample signal from said load and AC input terminals, the voltage of which represents availability of said electrical power, and said supply including a voltage monitor producing, in response to the voltage of said AC sample signal, a forward transfer signal for effecting forward transfer of said power supply from transmitting electrical power to said load terminal to supplying power to said load terminals, a detector circuit for inhibiting said forward transfer of said power supply upon detection of a clipping of the crests of said AC sample signal voltage wave form that otherwise appears to be a low voltage condition normally causing said forward transfer through said monitor producing said forward transfer signal, said detector circuit comprising:

• A. voltage comparator means receiving said AC sample signal voltage wave form and producing a clip detect signal having a width directly varying with the amount of clipping of the crests of said AC sample signal voltage wave form;
• and B. switch means in series with said monitor for disabling production of said forward transfer signal during said clip detect signal.

In an uninterruptible power supply for transmitting interruptible AC electrical power from AC input terminals to load terminals through a transformer during availability of said power from said AC input terminals, and supplying said load terminals with AC electrical power through said transformer from a standby source during interruption of said power from said AC input terminals, the supply selecting an AC sample signal from said load and AC input terminals, the voltage of which represents availability of said electrical power, and said supply including a voltage monitor producing in response to the voltage of said AC sample signal, a forward transfer signal for effecting forward transfer of said power supply from transmitting power to said load terminals to supplying power to said load terminals, a method for inhibiting said forward transfer of said power supply upon detection of a clipping of the crests of said AC sample signal voltage wave form that otherwise appears to said monitor to be a low voltage condition normally causing said forward transfer through said monitor producing said forward transfer signal, said method comprising:

• A. producing a clip detect signal having width directly varying with the amount of clipping of the crests of said AC sample signal voltage wave form;
• and
• B. disabling production of said forward transfer signal during said clip detect signal.

In an uninterruptible power supply for transmitting interruptible AC electrical power from AC input terminals to load terminals through a transformer during availability of said power from said AC input terminals, and supplying said load terminals with AC electrical power through said transformer from a standby source during interruption of said power from said AC input terminals, a phaselocked loop circuit for producing from an oscillator internal said power supply a precision sine wave signal in phase with the phase of the sinusoidal wave form of the AC electrical power, said oscillator being capable of varying the frequency of the precision sine wave signal from a desired frequency equal to that of the AC electrical power in response to the current level of a control signal fed to said oscillator varying from a certain current level, said loop circuit comprising:

• A. phase shifter means receiving said sinusoidal wave form of said AC electrical power and producing a shifted signal having a phase 180 degrees from said sinusoidal wave form;
• B. first divider means receiving said shifted signal and producing a first divided signal therefrom oscillating at a frequency of half that of said shifted signal;
• C. second divider means receiving said precision sine wave signal and producing a second divided signal therefrom oscillating at a frequency of half that of said precision sine wave signal;
• D. gating means receiving said first and second divided signals and producing a synchronizing signal having pulses with varying widths directly related to the phase difference between said first divided signal and said second divided signal;
• and
• E. current generator means receiving said synchronizing signal and producing said control signal having current levels directly related to the varying widths of said pulses of said synchronizing signal,
• F. so that a phase difference between said electrical power sinusoidal wave form and said precision sine wave signal causes said oscillator to vary the frequency of said precision sine wave signal until the phase of said precision sine wave signal matches that of said electrical power sinusoidal wave form.

In an uninterruptible power supply for transmitting interruptible AC electrical power from AC input terminals to load terminals through a transformer during availability of said power from said AC input terminals, and supplying said load terminals with AC electrical power through said transformer from a standby source during interruption of said power from said AC input terminals, a method of producing from an oscillator internal said power supply a precision sine wave in phase with the phase of the sinusoidal wave form of the AC electrical power, said oscillator being capable of varying the frequency of the precision sine wave signal from a desired frequency equal to that of the AC electrical power in response to the current level of a control signal fed to said oscillator varying from a certain current level, said method comprising:

• A. producing a shifted signal having a phase 180 degrees from said sinusoidal wave form of said AC electrical power;
• B. producing a first divided signal oscillating at a frequency of half that of said shifted signal;
• C. producing a second divided signal oscillating at a frequency of half that of said precision sine wave signal;
• D. producing a synchronizing signal having pulses with varying widths directly related to the phase difference between said first divided signal and said second divided signal;
• and
• E. producing said control signal having current levels directly related to the varying widths of said pulses of said synchronizing signal,
• F. so that a phase difference between said electrical power sinusoidal wave form and said precision sine wave signal causes said oscillator to vary the frequency of said precision sine wave signal until the phase of said precision sine wave signal matches that of said electrical power sinusoidal wave form.

An uninterruptible power supply for transmitting voltage varying and interruptible AC electrical power received from a AC input source to a load during availability of electrical power from said AC input source and supplying said load with AC electrical power from an auxiliary source during interruption of power from said AC input source, said supply comprising:

• A. AC input terminals adapted to be connected to said AC input source;
• B. load terminals adapted to be connected to said load;
• C. monitor means coupled to said AC input terminals and said load terminals for producing a normal mode signal when the AC electrical power from said AC input source continues within about certain voltage limits and for producing a standby mode signal when AC input source electrical power varies substantially beyond said certain voltage limits to be considered interrupted;
• D. transformer means connected in series between said AC input and load terminals for transmitting AC electrical power from said AC input terminals to said load terminals;
• E. inverter means for supplying AC electrical power to said load terminals through said transformer means upon receipt of an inverter enable signal;
• F. regulator means connected in series with said transformer means between said AC input and load terminals for regulating, in response to a regulator enable signal, to within said certain voltage limits the AC electrical power transmitted to said load terminals from said AC input terminals in response to the AC voltage from said AC input terminals varying substantially at said certain voltage limits, and for disconnecting, in response to a regulator disable signal, said transformer means from said AC input terminals;
• G. sequence means for producing said regulator enable signal and a switch normal signal in response to said normal mode signal and for producing said regulator disable signal, said inverter enable signal and a switch standby signal in response to said standby mode signal;
• and
• H. switch means for connecting said load terminals to said monitor means in response to said switch normal signal and for connecting said AC input terminals to said monitor means in response to said switch standby signal.

A method of transmitting voltage varying and interruptible AC electrical power received form a AC input source to a load during availability of electrical power from said AC input source and supplying said load with AC electrical power from an auxiliary source during interruption of power from said AC input source, said method comprising:

• A. connecting AC input terminals to said AC input source;
• B. connecting load terminals adapted to said load;
• C. producing a normal mode signal from a monitor when the AC electrical power from said AC input source continues within about certain voltage limits and producing a standby mode signal from said monitor when the AC electrical power form said AC input source varies substantially beyond said certain voltage limits to be considered interrupted;
• D. connecting a transformer in series between said AC input and load terminals for transmitting AC electrical power from said AC input terminals to said load terminals;
• E. supplying AC electrical power from an auxiliary source to said load terminals through said transformer upon receipt of an inverter enable signal;
• F. connecting a regulator in series with said transformer between said AC input and load terminals for regulating, in response to a regulator enable signal, to within said certain voltage limits the AC electrical power transmitted to said load terminals from said AC input terminals in response to the AC voltage from said AC input terminals varying substantially at said certain voltage limit, and for disconnecting, in response to a regulator disable signal, said transformer from said AC input terminals;
• G. producing said regulator enable signal and a switch normal signal in response to said normal mode signal and for producing said regulator disable signal, said inverter enable signal and a switch standby signal in response to said standby mode signal;
• and
• H. connecting said load terminals to said monitor in response to said switch normal signal and for connecting said AC input terminals to said monitor in response to said switch standby signal.

An uninterruptible power supply for transmitting voltage varying and interruptible AC electrical power received from a AC input source to a load during availability of electrical power from said AC input source and supplying said load with AC electrical power from an auxiliary source during interruption of power from said AC input source, said supply comprising:

• A. AC input terminals adapted to be connected to said AC input source;
• B. load terminals adapted to be connected to said load;
• C. monitor means coupled to said AC input terminals and said load terminals for producing a normal mode signal when the AC electrical power from said AC input source continues within about certain voltage limits and for producing a standby mode signal when said AC input source electrical power varies substantially beyond said certain voltage limits to be considered interrupted;
• D. transformer means connected in series between said AC input and load terminals for transmitting AC electrical power from said AC input terminals to said load terminals;
• E. inverter means for supplying AC electrical power to said load terminals through said transformer means upon receipt of an inverter enable signal;
• F. regulator means connected in series with said transformer means between said AC input and load terminals for regulating, in response to a regulator enable signal, to within said certain voltage limits the AC electrical power transmitted to said load terminals from said AC input terminals in response to the AC voltage from said AC input terminals varying substantially at said certain voltage limit, and for disconnecting, in response to a regulator disable signal, said transformer means from said AC input terminals;
• G. sequence means for producing said regulator enable signal and a switch normal signal in response to said normal mode signal and for producing said regulator disable signal, said inverter enable signal and a switch standby signal in response to said standby mode signal;,
• H. switch means for connecting said load terminals to said monitor means in response to said switch normal signal and for connecting said AC input terminals to said monitor means in response to said switch standby signal;
• I. clip detector means for inhibiting said monitor from making said standby mode signal upon detection of a clipping of the crests of the AC voltage wave form applied to said monitor from said switch means that otherwise appears to be a low voltage condition normally causing said monitor to produce said standby mode signal;
• and
• J. phase-locked loop means for keeping said inverter means synchronized with the phase of said AC input source electrical power.