Power converter with circuits for providing gate driving
First Claim
1. A switched mode power supply (SMPS) comprising:
- a pulse-width-modulator (PWM) with a PWM ground referenced positive output, a power section with a power switch (Q1) having a switch control that turns on said switch with a positive voltage at a positive input terminal (GATE) with respect to a negative input terminal (SOURCE) above a threshold voltage and turns off said switch (Q1) with a voltage below said threshold voltage, and a drive section that provides an interface between said PWM and said switch;
wherein said drive section has an input, an output, and an isolation transformer (TX1) disposed in between that isolates the drive section output from the input and having a primary winding (VP1), a first secondary winding (VS1a), and a second secondary winding (VS1b) wherein voltage from said second secondary winding (VS1b) is opposite in polarity to that of said first secondary winding (VS1a) output;
wherein said PWM output is connected to said primary winding (VP1) through a DC-blocking capacitor (C1);
wherein said first secondary winding (VS1a) high side is connected to the positive input terminal (GATE) of said power switch (Q1) via a DC-restore capacitor (C2), said first secondary winding (VS1a) low side is connected to the negative input terminal (SOURCE) of said switch (Q1) and, optionally, a DC-restore diode (D2) is added with its cathode connected to said DC-restore capacitor (C2) terminal opposite the capacitor'"'"'s connection to said first secondary winding (VS1a) high side and with its anode connected to said first secondary winding (VS1a) low side; and
wherein said second secondary winding (VS1b) high side is connected to a first control terminal of a DC-restore capacitor (C2) switch module (X3) and said second secondary winding (VS1b) low side is connected to a second control terminal of said switch module (X3) and to said first secondary winding (VS1a) low side, wherein said switch module (X3) has a switch connected across said DC-restore capacitor (C2), from the capacitor terminal opposite said first secondary winding (VS1a) high side to said first secondary winding (VS1a) low side, wherein said switch module (X3) has timing circuitry which turns off said DC-restore capacitor switch module (X3) after a preset time;
wherein after a voltage pulse is received from said second secondary winding (VS1b), said DC-restore capacitor switch module (X3) connects said DC-restore capacitor (C2) to said first secondary winding (VS1a) low side, but only until the preset time has elapsed.
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Accused Products
Abstract
A switched mode power supply is provided comprising a pulse-width-modulator (PWM), a power section, and a drive section for the power switch. The drive section consists of a new method of driving the power switch where it is desired that the switch terminals be isolated from the PWM ground. The new driver design, which incorporates a small isolation transformer along with unique modifications to the traditional DC restore circuit, is directed to solving problems when PWM type switching power supplies encounter fault conditions such as a short circuit across their output as well as protecting the switch and the load when an ordinary shutdown or disable command is received. One problem that arises with switch drivers that utilize isolation transformers during an overload event or even an ordinary shutdown event is that the driver does not turn off and hold off the power switch when it is commanded to do so. This invention solves these problems by insuring that the appropriate components are de-energized in the classical dc-restore circuit which will prevent the PWM from losing control of the power switch.
196 Citations
24 Claims
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1. A switched mode power supply (SMPS) comprising:
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a pulse-width-modulator (PWM) with a PWM ground referenced positive output, a power section with a power switch (Q1) having a switch control that turns on said switch with a positive voltage at a positive input terminal (GATE) with respect to a negative input terminal (SOURCE) above a threshold voltage and turns off said switch (Q1) with a voltage below said threshold voltage, and a drive section that provides an interface between said PWM and said switch; wherein said drive section has an input, an output, and an isolation transformer (TX1) disposed in between that isolates the drive section output from the input and having a primary winding (VP1), a first secondary winding (VS1a), and a second secondary winding (VS1b) wherein voltage from said second secondary winding (VS1b) is opposite in polarity to that of said first secondary winding (VS1a) output; wherein said PWM output is connected to said primary winding (VP1) through a DC-blocking capacitor (C1); wherein said first secondary winding (VS1a) high side is connected to the positive input terminal (GATE) of said power switch (Q1) via a DC-restore capacitor (C2), said first secondary winding (VS1a) low side is connected to the negative input terminal (SOURCE) of said switch (Q1) and, optionally, a DC-restore diode (D2) is added with its cathode connected to said DC-restore capacitor (C2) terminal opposite the capacitor'"'"'s connection to said first secondary winding (VS1a) high side and with its anode connected to said first secondary winding (VS1a) low side; and wherein said second secondary winding (VS1b) high side is connected to a first control terminal of a DC-restore capacitor (C2) switch module (X3) and said second secondary winding (VS1b) low side is connected to a second control terminal of said switch module (X3) and to said first secondary winding (VS1a) low side, wherein said switch module (X3) has a switch connected across said DC-restore capacitor (C2), from the capacitor terminal opposite said first secondary winding (VS1a) high side to said first secondary winding (VS1a) low side, wherein said switch module (X3) has timing circuitry which turns off said DC-restore capacitor switch module (X3) after a preset time; wherein after a voltage pulse is received from said second secondary winding (VS1b), said DC-restore capacitor switch module (X3) connects said DC-restore capacitor (C2) to said first secondary winding (VS1a) low side, but only until the preset time has elapsed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A switched mode power supply (SMPS) comprising:
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a pulse-width-modulator (PWM) with a PWM ground referenced positive output, a power section with a power switch (Q1) having a switch control that turns on said switch with a positive voltage at a positive input terminal (GATE) with respect to a negative input terminal (SOURCE) above a threshold voltage and turns said switch (Q1) off with a voltage below said threshold voltage, and a drive section that provides an interface between said PWM and said switch; wherein said drive section has an input, an output, and an isolation transformer (TX1) disposed in between that isolates the drive section output from the input and having a primary winding (VP1) and at least one secondary winding (VS1a); wherein said PWM output is connected to said primary winding (VP1) through a DC-blocking capacitor (C1); a diode (D1) connected across said DC-blocking capacitor (C1) with its cathode oriented toward said PWM positive output; wherein said at least one secondary winding (VS1a) high side is connected to the positive input terminal (GATE) of said power switch (Q1) via a DC-restore capacitor (C2), said at least one secondary winding (VS1a) low side is connected to the negative input terminal (SOURCE) of said switch (Q1) as well as to the anode of a DC-restore diode (D2) with its cathode connected to said DC-restore capacitor (C2) terminal opposite the capacitor'"'"'s connection to said first secondary winding (VS1a) high side and with its anode connected to said first secondary winding (VS1a) low side; and a DC-restore capacitor shorting switch (SW2) connected across said DC-restore capacitor (C2) having control terminals that turn said switch on after receiving a signal that turns off said PWM output. - View Dependent Claims (14, 15)
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16. A switched mode power supply (SMPS) comprising:
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a pulse-width-modulator (PWM) with a PWM ground referenced positive output, a power section with a power switch (Q1) having a switch control that turns on said switch with a positive voltage at a positive input terminal (GATE) with respect to a negative input terminal (SOURCE) above a threshold voltage and turns said switch (Q1) off with a voltage below said threshold voltage, and a drive section that provides an interface between said PWM and said switch; wherein said drive section has an input, an output, and an isolation transformer (TX0) disposed in between that isolates the drive section output from the input and having a primary winding (VP0) and a secondary winding (VS0); wherein said PWM output is connected to said primary winding (VP0) through a DC-blocking capacitor (C1); wherein said secondary winding (VS0) high side is connected to the positive input terminal (GATE) of said power switch (Q1) via a DC-restore capacitor (C2), said secondary winding (VS0) low side is connected to the negative input terminal (SOURCE) of said switch (Q1) and, optionally, a DC-restore diode (D2) is added with its cathode connected to said DC-restore capacitor (C2) terminal opposite the capacitor'"'"'s connection to said first secondary winding (VS0) high side and with its anode connected to said first secondary winding (VS0) low side; and wherein said secondary winding (VS0) is further connected to the control terminals of a DC-restore capacitor (C2) switch module (X4), wherein said switch module (X4) has a switch connected across said DC-restore capacitor (C2), from the capacitor terminal opposite said secondary winding (VS0) high side to said secondary winding (VS0) low side, wherein said switch module (X4) has timing circuitry which turns off said DC-restore capacitor switch module (X4) after a preset time; wherein after a voltage pulse is received from said second secondary winding (VS0), said DC-restore switch module connects said DC-restore capacitor (C2) to said secondary winding (VS0) low side, which nuts said DC-restore capacitor (C2) in parallel with said DC-blocking capacitor (C1) to keep VC2 proportional to VC1 as scaled by the transformer (TX0) turns ratio, but only until the preset time has elapsed. - View Dependent Claims (17, 18, 19, 20)
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21. A switched mode power supply (SMPS) comprising:
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a pulse-width-modulator (PWM) with a PWM ground referenced positive output, a power section with a power switch (Q1) having a switch control that turns on said switch with a positive voltage at a positive input terminal (GATE) with respect to a negative input terminal (SOURCE) above a threshold voltage and turns said switch (Q1) off with a voltage below said threshold voltage, and a drive section that provides an interface between said PWM and said switch; wherein said drive section has an input, an output, and an isolation transformer (TX0, TX1) disposed in between that isolates the drive section output from the input and having a primary winding (VP0, VP1) and one or more secondary windings (VS0, VS1a, VS1b); wherein said PWM output is connected to said primary winding (VP0, VP1) through a DC-blocking capacitor (C1); wherein one secondary winding (VS0, VS1a) high side is connected as a gate driver to the positive input terminal (GATE) of said power switch (Q1) via a DC-restore capacitor (C2), said secondary winding gate driver (VS0, VS1a) low side is connected to the negative input terminal (SOURCE) of said switch (Q1), and, optionally, a DC-restore diode (D2) is added with its cathode connected to said DC-restore capacitor (C2) terminal opposite the capacitor'"'"'s connection to said first secondary winding (VS1a) high side and with its anode connected to said first secondary winding (VS0, VS1a) low side; and a DC-restore capacitor (C2) switch module (X3, X4) having a switch connected across said DC-restore capacitor (C2), from the capacitor terminal opposite said secondary winding gate driver (VS0, VS1a) high side to said secondary winding gate driver (VS0, VS1a) low side, wherein said switch module (X3, X4) is configured to accept inputs from one of said one or more secondary windings (VS0, VS1a, VS1b) as a control winding to trigger timing circuitry that controls said DC-restore capacitor switch module (X3, X4) switch; wherein after a voltage pulse is received from said control winding (VS0, VS1a, VS1b), said DC-restore switch module connects said DC-restore capacitor (C2) to said secondary winding gate driver (VS0, VS1a) low side, which puts said DC-restore capacitor (C2) in parallel with said DC-blocking capacitor C1) to keep VC2 proportional to VC1 as scaled by the transformer (TX0, TX1) turns ratio, but only until a preset time has elapsed. - View Dependent Claims (22, 23, 24)
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Specification