Resonant power factor converter

A converter for interpositioning between an AC power source and a DC load to maintain a substantially unity power factor independent of the impedance of the load, said converter having rectifying circuit means for rectifying AC input to produce a DC voltage on a DC buss, an inverter having a power resonant circuit connected to be driven from said DC buss and connected to deliver output power through a rectifying circuit to a DC power storage device for delivering power to a DC load, means for controlling the phase angle between the voltage and current in said power resonant circuit while always maintaining the resonant voltage leading the resonant current, and a control circuit for controlling said means for controlling said phase angle responsive to the output voltage of said DC power storage means, a measured amount of AC line voltage and a measured amount of AC line current to adjust said phase angle in a manner whereby said resonant power circuit draws power from said DC buss to match power delivered to a DC load and said DC buss draws matching power from the AC source with the AC voltage and AC current essentially in phase for unity power factor said means for controlling the phase angle between the voltage and current in said power resonant circuit comprises a variable impedance connected in a resonant tank circuit incorporating a measured amount of resonant current flowing in said power resonant circuit, said control circuit being connected to control said variable impedance to effect the desired phase angle control.

A converter for interpositioning between an AC power source and a DC load to provide substantially unity power factor independent of load imposed on the DC power output, said device comprising rectifier circuit means for connection to an AC source, a power circuit means connected between said rectifier circuit means and a DC power output circuit for drawing power from an AC power source and delivering same to said DC power output circuit as a function of the phase angle between the voltage and current in said power circuit means, and circuit means responsive to a measured AC current demand and a measured actual AC current created when a DC load is placed on said DC power output circuit to control the phase angle of said power current relative to said power circuit voltage in a manner whereby the measured AC current demand and measured actual AC current are essentially identical and the instantaneous power of said power circuit means taken from said rectifier circuit means to meet the DC load demand is essentially equal to the instantaneous AC power delivered to said rectifier circuit means said power circuit means comprises an inverter in the form of a resonant power circuit selected from a parallel resonant circuit and a series parallel resonant circuit driven from said rectifier circuit means by a FET Bridge, and said circuit means for controlling the phase angle of said power circuit voltage and current comprises a resonant tank circuit for controlling the gating of said FET bridge, said resonant tank circuit being linked to resonant current flowing in said resonant power circuit and including a variable impedance for altering the phase of voltage across said tank circuit relative to said resonant power circuit current, said variable impedance being connected to respond to differences in measured line current demand and measured actual line current to control said FET bridge gating in a direction to change the phase angle between the resonant power circuit voltage and current to counteract such differences while always maintaining the resonant power circuit voltage leading the resonant power circuit current.

A converter for interpositioning between an AC power source and a DC load to maintain substantially unity power factor independent of the impedance of the load, said converter comprising a rectifier circuit having minimal power storage connected to feed a DC bus square wave gating means connected to said DC bus, a series parallel resonant power transfer circuit driven by said gating means, said resonant power circuit being connected to deliver power to a DC power storage device constituting a DC power output to which a DC load can be connected, means for varying the phase angle between the voltage across and current in said power resonant circuit to vary the power delivered to said DC storage device while always maintaining the voltage leading the current, and means for controlling said phase angle varying means to match the power taken by said resonant power transfer circuit from an AC source to the power required by a DC load said means for varying the phase angle between the power transfer resonant circuit voltage and current compares a resonant tank circuit and having sampled resonant power circuit current flowing therein, said tank circuit including a variable impedance for varying the phase between the voltage thereacross and the sampled current flowing therein said tank circuit being connected to effect drive of said square wave gating means to reproduce in said power resonant circuit the phase angle between voltage and current obtained in said resonant tank circuit, and said means for controlling said phase angle varying means are connected to control said variable impedance in said resonant tank circuit.