Current prediction in a switching power supply

• US 20060119331A1
• Filed: 08/01/2005
• Published: 06/08/2006
• Est. Priority Date: 08/02/2004
• Status: Active Grant

• Current Assignee: Electrovaya Incorporated
• Original Assignee: Electrovaya Incorporated
• Inventors: Vandermeer, David, Jacobs, James K., DasGupta, Sankar
• Granted Patent: US 7,391,188 B2
• Time in Patent Office: Days
• US Class Current: 323/235
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/0048 Circuits or arrangements for reducing losses using snubbers H02M1/34
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• CPC Class Codes: H03K 17/08142 in field-effect transistor switches
• CPC Class Codes: H03K 17/133 in field-effect transistor switches
• CPC Class Codes: H03K 17/162 without feedback from the output circuit to the control circuit
• CPC Class Codes: H03K 17/6872 using complementary field-effect transistors
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A high efficiency switching power supply including an analog front end, a battery control circuitry portion, a display and equalization circuitry portion, field effect transistor (FET) drivers, an isolated power supply transformer circuitry (and three associated sets of tap circuitry), microcontroller circuitry, oscillator circuitry, overcharge protection circuitry, programmable logic circuitry portion, and a zero current predictor. Overbiasing of the FET power supply switches, and/or other various circuitry features disclosed herein, helps achieve electrical power efficiencies of preferably greater than 95%, even more preferably greater than 98% and even more preferably greater than 99%. Preferably, the switching power supply has one or more of the following: (1) high electrical power efficiency (>95%. >98%, >99%); (2) overbiasing of a gate of a power supply switch; (3) a power supply switch with a low gate capacitance ratio; (4) multiple modes of operation; and (5) current prediction wherein an inductor voltage is used to control a constant current capacitor whose voltage indicates the level of current in the inductor.

Claims

1. A switching power supply comprising:

at least one power signal input structured as circuitry for providing an input electrical power signal to the switching power supply;

at least one power signal output structured as circuitry for providing an output electrical power signal from the switching power supply;

a passive component set comprising at least one inductor and a capacitor;

an active component set comprising a first power supply switch connected in series between the inductor and capacitor; and

zero current predictor circuitry structured and electrically connected to predict when inductor current will fall to zero and to send a signal to close the first power supply switch based on this prediction.

2. A switching power supply comprising:

at least one power signal input structured as circuitry for providing an input electrical power signal to the switching power supply;

at least one power signal output structured as circuitry for providing an output electrical power signal from the switching power supply;

a passive component set comprising at least one inductor and a capacitor;

an active component set comprising a first power supply switch connected in series between the inductor and capacitor; and

zero current predictor circuitry structured and electrically connected to predict when inductor current will fall to zero and to send a signal to close the first power supply switch based on this prediction, wherein the zero current predictor circuitry comprises a zcp capacitor electrically connected and controlled based on the voltage across the inductor so that the zcp capacitor'"'"'s voltage proportionally mirrors the inductor current.

3. The supply of claim 2 wherein the zero current predictor further comprises a reset circuit structured and electrically connect to short the zcp capacitor after a zero current prediction is made.

4. A switching power supply comprising:

at least one power signal input structured as circuitry for providing an input electrical power signal to the switching power supply;

at least one power signal output structured as circuitry for providing an output electrical power signal from the switching power supply;

a passive component set comprising at least one inductor and a capacitor;

an active component set comprising a first power supply switch connected in series between the inductor and capacitor; and

zero current predictor circuitry structured and electrically connected to predict when inductor current will fall to zero and to send a signal to close the first power supply switch based on this prediction, wherein the zero current predictor circuitry comprises;

a zcp capacitor electrically connected and controlled based on the voltage across the inductor so that the zcp capacitor'"'"'s voltage proportionally mirrors the inductor current;

a zcp integrator is structured and electrically connected to integrate the rate of change of zcp capacitor voltage to determine zcp capacitor voltage; and

a zcp comparator is structured to indicate in an output signal the condition that the zcp voltage determined by the integrator has fallen below a minimum threshold.