Un-interruptible power supply

• US 6,479,970 B2
• Filed: 04/03/2001
• Issued: 11/12/2002
• Est. Priority Date: 04/03/2001
• Status: Expired due to Fees

• Current Assignee: Anantha B. Reddy
• Original Assignee: Anantha B. Reddy
• Inventors: Reddy, Anantha B.
• Primary Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/825,475
• Publication Number:
  US 20020140403A1
• Time in Patent Office: 588 Days
• Field of Search: 320/162, 307/66, 307/149, 307/46
• US Class Current: 320/162
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02J 9/067 using multi-primary transformers, e.g. transformer having one primary for each AC energy source and a secondary for the loads
• CPC Class Codes: H02M 7/4807 having a high frequency intermediate AC stage

Abstract

An un-interruptible power supply coupled to a dc input voltage node, having a mode control circuit to monitors the input voltage and to provide a mode selection signal to indicate that the input voltage is above a predetermined level. A high frequency transformer has a primary winding, an output winding and a charger winding. A battery is referenced to a third reference potential node. An input inverter transfers power from the dc input voltage to an output rectifier and to an adaptive converter to charge a battery. The output rectifier and filter provides the output dc voltage referenced to the second reference potential node. The adaptive converter referenced to the third reference potential transfer power from the battery to the transformer charger winding to provide the output dc voltage source.

Claims

1. An un-interruptible power supply coupled to receive a dc input voltage at a dc input voltage node referenced to a first reference potential node, and to provide an isolated output dc voltage referenced to a second reference potential node to a load comprising:

a mode control circuit coupled to monitor the dc input voltage and to provide a mode selection signal having a first state in response to the dc input voltage exceeding a first voltage level and a second state in response to the dc input voltage passing below a second voltage level,

a high frequency transformer having at least a primary winding, an output winding and a charger winding, a battery having a battery voltage at a battery first terminal measured with respect to a battery second terminal, the battery second terminal being coupled to a third reference potential node,

an input inverter referenced to the first reference potential node and coupled to transfer power from the dc input voltage, to provide pulse width modulated power to the primary winding of the high frequency transformer,

an output rectifier and filter driven by the transformer output winding to provide the output dc voltage referenced to the second reference potential node,

an adaptive converter referenced to the third reference potential node and coupled to the transformer charger winding for charging the battery in response to the mode selection signal first state to transfer power from the battery to the transformer charger winding to provide the output dc voltage source in response to the mode selection signal second state.

2. The un-interruptible power supply of claim 1 further comprising:

a micro-controller coupled via signal paths to communicate data and control signals for the control and or performance of at least one of the functions selected from the group of functions including, mode control, and or an external interface control.

3. An un-interruptible power supply coupled to receive a dc input voltage at a dc input voltage node referenced to a first reference potential node, and to provide an isolated output dc voltage referenced to a second reference potential node to a load comprising:

a mode control circuit coupled to monitor the dc input voltage and to provide a mode selection signal having a first state in response to the dc input voltage exceeding a first voltage level and a second state in response to the dc input voltage passing below a second voltage level,

a high frequency transformer having at least a primary winding, an output winding and a charger winding,

a battery having a battery voltage at a battery first terminal measured with respect to a battery second terminal, the battery second terminal being coupled to a third reference potential node,

an input inverter control circuit referenced to the third reference potential node and coupled to sense the battery voltage on the battery first terminal and a predetermined battery reference voltage and to provide an input PWM (pulse width modulated) signal referenced to third reference potential and having a duty cycle characterized to increase for a sensed battery voltage having a value less than a predetermined battery voltage measured with respect to the third reference potential, and decrease for a sensed battery voltage having a value more than the predetermined battery potential,

an input inverter referenced to the first reference potential node and coupled to transfer power from the dc input voltage, the input inverter being responsive to the input PWM signal to provide pulse width modulated power to the primary winding of the high frequency transformer,

an output rectifier and filter driven by the transformer output winding to provide the output dc voltage referenced to the second reference potential node,

an adaptive converter referenced to the third reference potential node and coupled to the transformer charger winding for charging the battery in response to the mode selection signal first state to transfer power from the battery to the transformer charger winding to provide the output dc voltage source in response to the mode selection signal second state.

4. The un-interruptible power supply of claim 3 further comprising:

a micro-controller coupled via signal paths to communicate data and control signals for the control or performance of at least one of the functions selected from the group of functions including, mode control, input inverter control.

5. An un-interruptible power supply coupled to receive a dc input voltage at a dc input voltage node referenced to a first reference potential node, and to provide an isolated output dc voltage referenced to a second reference potential node to a load comprising:

a mode control circuit coupled to monitor the dc input voltage and to provide a mode selection signal having a first state in response to the dc input voltage exceeding a first voltage level and a second state in response to the dc input voltage passing below a second voltage level,

a high frequency transformer having at least a primary winding, an output winding and a charger winding,

a battery having a battery voltage at a battery first terminal measured with respect to a battery second terminal, the battery second terminal being coupled to a third reference potential node,

an input inverter referenced to the first reference potential node and coupled to transfer power from the dc input voltage, to provide pulse width modulated power to the primary winding of the high frequency transformer,

an output rectifier and filter driven by the transformer output winding to provide the output dc voltage referenced to the second reference potential node,

a battery inverter control circuit referenced to the second reference potential and coupled to sense the isolated output dc voltage and a predetermined output reference voltage to provide a battery PWM (pulse width modulated) signal having a duty cycle characterized to increase for a sensed isolated output dc voltage having a value less than a predetermined output reference voltage, and decrease for a sensed isolated output dc voltage having a value more than the predetermined output reference voltage,

an adaptive converter referenced to the third reference potential node and coupled to the transformer charger winding for charging the battery in response to the mode selection signal first state and being coupled to transfer power from the battery to the transformer charger winding to provide the output dc voltage source in response to the mode selection signal second state.

6. The un-interruptible power supply of claim 5 further comprising:

a micro-controller coupled via signal paths to communicate data and control signals for the control or performance of at least one of the functions selected from the group of functions including, mode control, battery inverter control.

7. An un-interruptible power supply coupled to receive a dc input voltage at a dc input voltage node referenced to a first reference potential at a first reference potential node, and to provide an isolated output dc voltage referenced to a second reference potential node to a load comprising:

a mode control circuit coupled to monitor the dc input voltage and to provide a mode selection signal having a first state in response to the dc input voltage exceeding a first voltage level and a second state in response to the dc input voltage passing below a second voltage level,

a high frequency transformer having at least a primary winding, an output winding and a charger winding,

a battery having a battery voltage at a battery first terminal measured with respect to a battery second terminal, the battery second terminal being coupled to a third reference potential node,

an input inverter control circuit referenced to the third reference potential node and coupled to sense the battery voltage on the battery first terminal and a predetermined battery reference voltage and to provide an input PWM (pulse width modulated) signal referenced to the third reference potential and having a duty cycle characterized to increase for a sensed battery voltage having a value less than a predetermined battery voltage measured with respect to the third reference potential, and decrease for a sensed battery voltage having a value more than the predetermined battery voltage measured with respect to the third reference potential,

an input inverter referenced to the first reference potential node and coupled to transfer power from the dc input voltage, the input inverter being responsive to the input PWM signal to provide pulse width modulated power to the primary winding of the high frequency transformer,

an output rectifier and filter driven by the transformer output winding to provide the isolated output dc voltage referenced to the second reference potential node,

a battery inverter control circuit referenced to the second reference potential and coupled to sense the isolated output dc voltage and a predetermined output reference voltage to provide a battery PWM (pulse width modulated) signal having a duty cycle characterized to increase for a sensed isolated output dc voltage having a value less than a predetermined output reference voltage, and decrease for a sensed isolated output dc voltage having a value more than the predetermined output reference voltage,

an adaptive converter referenced to the third reference potential node and coupled to the transformer charger winding for charging the battery in response to the first mode selection signal first state and being coupled to receive and being responsive to the battery PWM drive signal to transfer power from the battery to the transformer charger winding to provide the isolated output dc voltage source in response to a mode selection signal second state.

8. The un-interruptible power supply of claim 7 in which the mode control circuit further comprises:

a comparator circuit for sensing the dc input voltage via a resistor divider network, the comparator having a feedback resistor selected to cause the comparator circuit to have a predetermined hysteresis, the comparator circuit outputting the mode selection signal having the first state in response to the dc input voltage exceeding the first voltage level; and

the mode selection signal having the second state in response to the dc input voltage passing below the second voltage level; and

,

a relay responsive to the mode selection signal first state for providing a contact closure.

9. The un-interruptible power supply of claim 7 wherein the high frequency transformer primary winding, the output winding and the charger windings each have respective first and second terminals;

and,

wherein the input inverter is further characterized to be an H-bridge switching circuit coupled between the dc input voltage node and the first reference potential, the H-Bridge having a left and right branch, each respective branch having a pair of series connected bi-directional semiconductor switching devices, each semiconductor switching device having a bi-directional conduction channel and a control gate, each pair of series connected bi-directional conduction channels being connected at a respective H-bridge output node, each H-Bridge output node being connected to a respective primary winding first and second terminal,

each bi-directional semiconductor switching device control gate being coupled to be driven by a high and low side bootstrap peripheral driver, each bootstrap peripheral driver being driven by isolated input PWM signals.

10. The un-interruptible power supply of claim 9 wherein the high and low side bootstrap peripheral drivers driven by isolated input PWM signals are IR2110 peripheral drivers.

11. The un-interruptible power supply of claim 7 in which the a battery inverter control circuit further comprises:

a current sense resistor in series with the load,

a first amplifier coupled to sense the voltage across the current sense resistor and convert the current amplitude into a current scaled output voltage,

a second amplifier having a first input coupled to sense a portion of the output voltage and a second input coupled to sense a predetermined voltage reference, the second amplifier outputting an amplified difference voltage between the portion of the output voltage and the predetermined reference voltage, and,

a third amplifier having a first input coupled to receive the current scaled output voltage of the first amplifier and a second input coupled to receive the amplified difference voltage between the portion of the output voltage and the predetermined reference voltage, the third amplifier outputting a control level voltage, a comparator having a first input coupled to receive a periodic sawtooth voltage wave form each sawtooth having a duration equal to one half of a total switching cycle, and a second input coupled to receive the control level voltage, the output of the comparator being coupled to start a power cycle at the beginning of each sawtooth voltage waveform, the comparator being coupled to reverse its state in response to the sawtooth voltage exceeding the control level voltage, thereby terminating the power cycle in progress.

12. Un-interruptible power supply of claim 7 wherein the adaptive converter further comprises:

an inductor having a first and second terminal, the first terminal being connected to the battery first terminal, and wherein,

the high frequency transformer charger winding further comprises;

a first segment having a first number of turns having a first and second terminal for coupling power from the battery first terminal to the output winding, the charger winding having a second segment having additional turns terminating at a third terminal, the total winding from the first to the third terminal being characterized and sized for use in delivering power from the input inverter via the primary winding, via the charger winding, via the closed contact, and via the inductor to charge the battery,

the adaptive converter further comprising;

a bridge rectifier circuit having a left and right branch, each branch having a first and second rectifier, each branch of the rectifier circuit having an output end coupled to the inductor second terminal and a return end coupled to the third reference potential, the first and second rectifier of each branch being connected at a respective left and right branch common node, the charger winding first and third terminals being coupled to drive respective bridge rectifier right and left branch common nodes via the mode control circuit contact closure in response to a mode selection signal first state.

13. The Un-interruptible power supply of claim 12 wherein the adaptive converter further comprises:

an H-bridge switching circuit having a left and right branch coupled between the battery first terminal and the third reference potential, each respective branch having a pair of series connected bi-directional semiconductor switching devices, each semiconductor switching device having a bi-directional conduction channel and a control gate, each pair of series connected bi-directional conduction channels being connected at a respective H-bridge output node, each H-Bridge output node being connected to the charger winding first and second terminal,

each bi-directional semiconductor switching device control gate being coupled to and driven by a respective high and low side bootstrap peripheral driver, each bootstrap peripheral driver being driven by a respective complementary battery PWM signal pair in response to the mode control signal being in a second state.

14. Un-interruptible power supply of claim 7 wherein the adaptive converter further comprises:

an inductor having a first and second terminal, the first terminal being connected to the battery first terminal, and wherein

the high frequency transformer charger winding further comprises;

a first segment having a first number of turns having a first and second terminal for coupling power from the battery first terminal to the output winding, the charger winding having a second segment having additional turns terminating at a third terminal, the total winding from the first to the third terminal being characterized and sized for use in delivering power from the input inverter via the primary winding, via the charger winding, via the closed contact in response to the mode control signal being in the first state, and via the inductor to charge the battery,

the adaptive converter further comprising;

a shunt diode, the shunt diode being connected from the battery first terminal to the inductor second terminal to be forward biased in response to current leaving the battery when the mode control signal is in the second state,

a bridge rectifier circuit having a left and right branch, each branch having a first and second rectifier, the rectifier circuit having an output end coupled to the inductor second terminal and a return end coupled to the third reference potential, each branch having a first and second rectifier connected at a respective left and right branch common node, the charger winding first and third terminals being coupled to drive respective bridge rectifier left and right branch common nodes via the mode control circuit contact closure in response to a mode selection signal first state.

15. The Un-interruptible power supply of claim 14 wherein the adaptive converter further comprises:

an H-bridge switching circuit coupled between the inductor second terminal and the first reference potential, the H-Bridge having a left and right branch, each respective branch having a pair of series connected bi-directional semiconductor switching devices, each semiconductor switching device having a bi-directional conduction channel and a control gate, each pair of series connected bi-directional conduction channels being connected at a respective H-bridge output node, the left H-Bridge output node being connected to a charger winding first terminal, and the right H-Bridge output node via a closed contact in response to the mode control signal being in a second state to the charger winding second terminal,

each bi-directional semiconductor switching device control gate being coupled to be driven by a high and low side bootstrap peripheral driver, each bootstrap peripheral driver being driven by respective complementary battery PWM signals with the mode control signal in a second state in response to the mode selection signal being in a second state.

16. Un-interruptible power supply of claim 7 wherein the adaptive converter further comprises:

an inductor having a first and second terminal, the first terminal being connected to the battery first terminal,

the high frequency transformer charger winding further comprises;

a center-tapped segment having two end terminals and a center tapped terminal for coupling power from the battery first terminal to the output winding, the charger winding having a second and third segment, each second and third segment having substantially equivalent turns counts and having a first and second terminal, the first terminal of each respective second and third segment being coupled to a respective center-tapped segment end terminal, the second terminal of each center-tapped second and third segment being connected to a respective first and second battery charge diode, each respective battery charge diodes being connected through a contact closure as the mode control signal assumes a first state to the inductor second terminal, the battery charge diodes forming a full wave rectifier, the center taped node being connected to the third reference potential, the combination of the center taped segment and the second and third segments being sized to drive the full wave rectifier formed by the two battery charge diodes to deliver power from the input inverter via the primary winding, via the charger winding, via the contact closure, and via the inductor to charge the battery,

the adaptive converter further comprising;

a full wave synchronous bi-directional rectifier circuit having a left and right branch, each branch having a semiconductor switching device having a conduction channel and a control gate, each conduction channel having a first and second terminal, the left and right branch conduction channel first ends being connected to the inductor first end, the left and right branch conduction channel second ends being connected to respective charger winding center tapped segment ends,

a freewheeling rectifier circuit having an output end coupled to the inductor second terminal and a return end coupled to the third reference potential.

17. The un-interruptible power supply of claim 7 wherein the high frequency transformer is further characterized to have its primary winding, output winding and charger winding isolated from each other.

18. The un-interruptible power supply of claim 7 further comprising:

a micro-controller coupled via signal paths to communicate data and control signals for the control or performance of at least one of the functions selected from the group of functions including, mode control, input inverter control, battery inverter control, and or an external interface control.