Power converter

• US 20060083031A1
• Filed: 09/08/2005
• Published: 04/20/2006
• Est. Priority Date: 09/08/2004
• Status: Active Grant

• Current Assignee: Progressive Dynamics, Inc.
• Original Assignee: Progressive Dynamics, Inc.
• Inventors: Cook, James C. II
• Granted Patent: US 7,782,002 B2
• Time in Patent Office: Days
• US Class Current: 363/20
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/28 using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
• CPC Class Codes: Y10S 388/934 Thermal condition

Abstract

A switch-type power converter comprising an FET switch operating in a variable duty cycle mode under the control of a Unitrode 3846 integrated circuit controller. Indications of excess input voltage and reverse battery connections are provided by circuits including an element which permanently changes state. A cooling fan mounted on a finned heat sink is operated in a variable speed mode. A single thermistor sensor provides inputs to both the fan speed control and a thermal shutdown circuit connected to shut down the gate drives to the FET switch in the event of a high temperature condition. Another shutdown function is provided in response to an input overvoltage condition by way of an operational amplifier. The converter uses foldback for short circuit protection and is compatible with microprocessor units to selectively provide multiple output voltage levels.

Claims

1. A power converter of the type having an input for receiving a supply voltage, a switch, and a duty cycle controller connected to control the switch to regulate an output voltage produced by the converter wherein the improvement comprises:

a first circuit connected to said input and responsive to a first level over-voltage condition at said input for altering operation of duty cycle controller; and

a second circuit connected to said input and responsive to a second level over-voltage condition at said input to irreversibly change state without altering operation of the duty cycle controller.

2. A converter as described in claim 1 wherein the second level is higher than the first level.

3. A power converter as described in claim 1 wherein the first circuit comprises an amplifier circuit connected to said input and to a reference voltage, said amplifier circuit having an output connected to said controller to shut said controller down in response to the first level over-voltage condition.

4. A power converter as described in claim 1 wherein the second circuit comprises the series combination of a non-resettable fuse and a Zener diode connected between said input and ground.

5. A power converter of the type having an input connectible to an AC line voltage source, a rectifier for converting an AC line voltage to DC, a switching circuit comprising at least one power transistor, a transformer having a primary side connected to said rectifier and to said switch circuit and a secondary side connected to a converter output, a controller circuit for operating said switch circuit in a variable duty cycle mode wherein the improvement comprises:

a permanent over-voltage indicator circuit connected between said rectifier and ground and including the series combination of a voltage responsive semi-conductor device and an element which irreversibly changes state in response to the presence of an over-voltage condition at said rectifier output.

6. The power converter described in claim 5 wherein said element is a fuse.

7. The power converter described in claim 5 wherein said semi-conductor device is a Zener diode.

8. The power converter of claim 5 further comprising an over-voltage shut-down circuit connected between said rectifier output and said controller for shutting the controller down under over-voltage conditions.

9. The power converter of claim 8 wherein said over-voltage shut-down circuit further includes an operational amplifier.

10. A power converter of the type comprising an input for receiving a supply voltage, a switch including at least one power transistor, and a duty cycle controller connected to cycle the switch on and off wherein;

the improvement which comprises;

an over-voltage shut-down circuit connected between said input and said controller and comprising an operational amplifier;

said operational amplifier having an output connected to a shut down pin of said controller to terminate cycling of the switch.

11. A power converter of the type comprising a supply voltage input, a switch including at least one power transistor, a controller circuit for cycling the switch in a variable duty cycle mode and a transformer having a primary side connected to the switch and a secondary side connected to a converter output wherein the improvement comprises:

a fan having an electric motor;

a supply circuit connected between the primary side of the transformer and the fan motor; and

a control circuit for operating the fan in a variable speed mode

12. A converter as set forth in claim 11 further including a temperature sensor, the control circuit including an amplifier for establishing a set point voltage, the temperature sensor being connected to an input of said amplifier.

13. A power converter as defined in claim 12 wherein the temperature sensor is a thermistor and the controller further comprises a heat sink, the thermistor and the at least one power transistor being mounted on the heat sink.

14. A power converter as defined in claim 12 further comprising a shut down circuit including a second set point amplifier connected to receive an input from said sensor and having an output connected to said controller to stop cycling the switch when the second set point is reached.

15. A power converter of the type having an input, an output, a switch including a power transistor, and a controller for operating the switch in a variable duty cycle mode, a temperature sensor and a fan, wherein the improvement comprises;

a first set point device having an input connected to said sensor and an output connected to said fan for changing fan speed; and

a second set point device having an input connected to said sensor, and an output connected to said controller to disable the switch.

16. The converter of claim 15 wherein the first and second set point devices are op-amps.

17. The converter of claim 15 wherein the sensor is a thermistor.

18. The converter of claim 15 further including a housing and a heat sink attached to the housing;

the sensor and the power transistor being mounted on direct thermal exchange with the heat sink.

19. A power converter of claim 18 wherein the fan is mounted to the heat sink.

20. A power converter as defined in claim 19 wherein the heat sink is a finned metal body with a mounting end, the surface of said end being achieved to form an air gap between the fan and the heat sink.

21. A power converter for charging a battery and being of the type having a switch, a duty cycle controller connected to the switch, a transformer having a primary side and a secondary side, an output inductor, the primary side being connected to the switch and the secondary side being connected to the output inductor, wherein the improvement comprises:

a circuit for indicating a reverse battery connection to said output inductor and comprising a device connected between the output inductor and ground and effective to irreversibly change state when a reverse battery connection is made.

22. A power converter as defined in claim 21 further including a capacitor connected in parallel with said device.

23. A power converter as defined in claim 22 wherein the device is a Schottky diode.

24. A power converter of the type comprising a switch, a controller for controlling the duty cycle of the switch, a transformer, an output inductor and a converter output terminal, wherein the improvement comprises:

a circuit board having conductive traces formed thereon, the inductor being mounted on the current board such that at least one conductive trace runs from the inductor to the output terminal; and

a heavy gauge wire conductively bonded to and along said one conductive trace.

25. A power converter of the type comprising a switch, a controller for controlling the duty cycle of the switch, a transformer, an output inductor and a converter output terminal, wherein the improvement comprises:

a circuit board having conductive traces formed thereon, at least one trace running from the transformer to the output terminal; and

a heavy gauge wire conductively bonded to and along said one conductive trace.

26. A power converter of the type including a switch, a controller for varying the duty cycle of the switch, a heat sink for the switch and a fan and fan supply voltage source for causing the fan to cause air to flow over the heat sink wherein the improvement comprises:

a heat sensor; and

a fan control circuit, the fan control circuit being operative to control the supply voltage source to vary the speed of the fan in response to increasing temperature of said sensor.

27. A power converter as defined in claim 26 wherein the control circuit includes an op-amp, the sensor being connected to provide an input to the op-amp and the op-amp being connected to regulate the fan supply voltage.

28. A power converter as defined in claim 27 wherein the op-amp includes a feedback circuit which produces an oscillatory output from the op-amp.

29. A power converter as defined in claim 27 further including a second op-amp having an input connected to the sensor, said second op-amp being connected to a shut down pin in said controller.

30. A converter as defined in claim 29 wherein the heat sink is a finned metal body;

said switch having at least one current-carrying component attached to the heat sink.

31. A converter as defined in claim 30 further including a spring clip attaching said one component to the heat sink.