US 7,405,494 B2 · AC power supply apparatus, methods and computer program products using PWM synchronization

Abstract

Paralleled uninterruptible power supplies (UPSs) including respective pulse-width modulation (PWM) power converter circuits coupled in common to an AC load bus have PWM cycles that are synchronized. In particular, sampling of control inputs of the PWM power converter circuits may be synchronized, such that, for example, sampling of control inputs to the PWM power converter circuits occurs at substantially the same time for each of the PWM power converter circuits. A common phase reference corresponding to an AC voltage phase for the AC load bus may be provided, and the PWM cycles of each of the power converter circuits may synchronized, e.g., phase locked, to the common phase reference. More particularly, the respective PWM cycles of the UPSs may be phase locked to phase locked sinusoidal reference signals generated at each of the UPSs. Sampling for other control functions may also be synchronized to the PWM cycles.

Claims35

Dependent claims

A method of operating a plurality of paralleled uninterruptible power supplies (UPSs), the UPSs including respective pulse-width modulation (PWM) power converter circuits coupled in common to an AC load bus, the method comprising:

providing a phase reference corresponding to an AC voltage phase for the AC load bus, wherein providing a phase reference corresponding to an AC voltage phase for the AC load bus comprises providing respective sinusoidal reference signals at respective ones of the UPSs;
and
synchronizing PWM cycles of the PWM power converter circuits of each of the power converter circuits to the phase reference, wherein synchronizing PWM cycles of the PWM power converter circuits of each of the power converter circuits to the phase reference comprises synchronizing the respective PWM cycles of the UPSs to the respective sinusoidal reference signals and wherein synchronizing the respective PWM cycles of the UPSs to the respective sinusoidal reference signals comprises:
determining a number of PWM cycles occurring between phase indicia of a sinusoidal reference signal;
and
adjusting a PWM cycle duration responsive to the determined number of PWM cycles.

3 more elements

An uninterruptible power supply (UPS), comprising:

a first PWM power converter circuit configured to be coupled to an AC load bus;
and
a PWM cycle synchronizer circuit operative to synchronize PWM cycles of the PWM power converter circuit to PWM cycles of a second PWM power converter circuit coupled to the AC load bus, wherein the PWM cycle synchronizer circuit is operative to synchronize the PWM cycles of the first PWM power converter circuit to a phase reference corresponding to an AC voltage for the AC load bus, wherein the PWM cycle synchronizer circuit further comprises a sinusoidal reference signal generator circuit operative to generate a sinusoidal reference signal, wherein the PWM cycle synchronizer circuit is operative to synchronize the PWM cycles of the first PWM power converter circuit to the sinusoidal reference signal, and wherein the PWM cycle synchronizer circuit is operative to determine a number of PWM cycles occurring between phase indicia of the sinusoidal reference signal and to adjust a PWM cycle duration responsive to the determined number of PWM cycles.

Dependencies are inferred from the claim text.

AC power supply apparatus, methods and computer program products using PWM synchronization

Life of this patent

AC power supply apparatus, methods and computer program products using PWM synchronization

Life of this patent

Abstract

Claims35