AC to DC converter with unity power factor
AssigneeApollo Computer, Inc.
InventorJames B. Williams
Life of this patent
Estimating the term…
Abstract
An AC to DC converter comprises a bridge rectifier followed by a boost circuit. The boost circuit includes an inductor, diode and load capacitor in series and a shunting switch connected to shunt the diode and load capacitor. The control circuit for switching the shunting switch comprises a differential circuit, a multiplier and a duty cycle generator in a feedback loop which maintains a constant output voltage on the capacitor. To eliminate the response to ripple on the output voltage, the differential circuit does not respond to voltages within a dead band.
Claims19
An AC to DC converter comprising a circuit which includes an inductor and a diode connected in series with a load capacitor and a shunting switch connected to shunt the diode and load capacitor, the shunting switch being controlled by a control circuit at a frequency which is high relative to the frequency of the AC input, the control circuit comprising:
- a differential circuit for comparing an output voltage signal, which indicates the voltage on the load capacitor, to at least one reference to generate a multiplier, such that the product of the multiplier and a voltage input signal indicative of the voltage input to the inductor is proportional to current through the inductor required to provide a desired level of the output voltage, the differential circuit including means to eliminate response of the multiplier to expected ripple in the output signal;
- a multiplying circuit for multiplying the multiplier and the voltage input signal to generate a current command signal;
- and
- a duty cycle generator responsive to the current command signal and an inductor current signal, which indicates the current through the inductor, to control the duty cycle of the shunting switch.
An AC to DC converter comprising a circuit which includes an inductor and a diode connected in series with a load capacitor and a shunting switch connected to shunt the diode and load capacitor, the shunting switch being controlled by a control circuit at a frequency which is high relative to the frequency of the AC input, the control circuit comprising:
- a differential circuit for comparing an output voltage signal, which indicates the voltage on the load capacitor, to at least one reference to generate a feedback signal, the differential circuit responding rapidly to levels of the output voltage signal which are outside of high and low limits of amplitude to change the feedback signal, any response of the differential circuit to levels of the output voltage which are within the high and low limits of amplitude being slow;
- and
- a duty cycle generator responsive to the feedback signal to control the duty cycle of the shunting switch.
An AC to DC converter comprising a circuit which includes an inductor and a diode connected in series with a load capacitor and a shunting switch connected to shunt the diode and load capacitor, the shunting switch being controlled by a control circuit at a frequency which is high relative to the frequency of the AC input, the control circuit comprising:
- a differential circuit for comparing an output voltage signal, which indicates the voltage on the load capacitor, to at least one reference to generate a multiplier, such that the product of the multiplier and a voltage input signal indicative of the voltage input to the inductor is proportional to current through the inductor required to provide a desired level of the output voltage, the differential circuit responding rapidly to levels of the output voltage signal which are outside of high and low limits of amplitude to change the multiplier, any response of the differential circuit to levels of the output voltage which are within the high and low limits of amplitude being slow;
- a multiplying circuit for multiplying the multiplier and the voltage input signal to generate a current command signal;
- and
- a duty signal generator responsive to the current command signal and an inductor current signal, which indicates the current through the inductor, to control the duty cycle of the shunting switch.
Dependencies are inferred from the claim text.