Non-isolated resonant DC-DC converter with boost-type voltage doubler output
View Patent ↗A light fixture includes a housing, a non-isolated driver circuit with a boost type voltage doubler output stage, and a light source. The load or light source may be a plurality of LEDs. The housing supports the light source and the driver circuit, and the housing may include a lens for the one or more LEDs of the light source. The driver circuit provides power from the power source to the light source. The light source provides light in response to receiving power. The boost type voltage doubler output stage is a voltage doubler output stage having a boost inductor connected between an input (e.g., connected to an output of an inverter of the driver circuit) and an output (e.g., connected to the load or light source) of the boost type voltage doubler output stage.
1. A driver circuit for providing power from a power source to a load, said driver circuit comprising:
an inverter having a control input, a power input, and an inverter output, wherein:
the power input is configured to connect a direct current (DC) power rail; and
the inverter is configured to provide an alternating current (AC) output signal as a function of a drive signal received at the control input of the inverter;
a voltage doubler output stage having a voltage doubler input and a voltage doubler output, wherein:
the voltage doubler output is configured to connect to the load;
the voltage doubler input is coupled to the inverter output;
the voltage doubler output stage is configured to convert the AC output signal from the inverter into a DC output signal; and
the voltage doubler output stage comprises
a first diode having an anode and a cathode,
a second diode having an anode and a cathode,
a charge capacitor having a first terminal coupled to the voltage doubler input and a second terminal coupled to the cathode of the second diode,
a boost inductor having a first terminal connected to the cathode of the second diode and to the second terminal of the charge capacitor, and a second terminal connected to the anode of the first diode, and
wherein the cathode of the first diode is coupled to the voltage doubler output.
2. The driver circuit of claim 1 , wherein:
the voltage doubler output stage further comprises a current sensing resistor configured to connect in series with the load when the load is connected to the voltage doubler output and to provide a current sensing signal indicative of a current through the load; and
the driver circuit further comprises a controller having an output connected to the control input of the inverter, wherein the controller is configured to receive the current sensing signal and provide the drive signal to the control input of the inverter as a function of the received current sensing signal.
3. The driver circuit of claim 1 , wherein:
the power source is a DC power source configured to provide DC power to the driver circuit; and
the driver circuit further comprises an input stage, said input stage comprising:
a DC to DC converter configured to receive the DC power and provide the DC power rail.
4. The driver circuit of claim 1 , wherein:
the power source is an AC power source configured to provide AC power to the driver circuit; and
the driver circuit further comprises an input stage, said input stage comprising:
an electromagnetic interference (EMI) filter configured to connect to the power source and filter noise from the AC power provided by the AC power source; and
an AC to DC converter configured to receive the filtered AC power from the EMI filter and provide the DC power rail.
5. The driver circuit of claim 1 , wherein:
the inverter has a circuit ground;
the voltage doubler output stage has a circuit ground; and
the circuit ground of the voltage doubler output stage is connected to the circuit ground of the inverter such that the output of the voltage doubler output stage is not electrically isolated from the power input of the inverter.
6. The driver circuit of claim 1 , wherein the voltage doubler output stage further comprises:
an output capacitor connected between the cathode of the first diode and a circuit ground of the voltage doubler output stage; and
a current sensing resistor having a first terminal and a second terminal, wherein the first terminal is connected to the circuit ground of the voltage doubler output stage and the second terminal provides a current sensing signal indicative of a current through the load; and wherein:
the load connects between the second terminal of the current sensing resistor and the cathode of the first diode.
7. The driver circuit of claim 1 , wherein:
the voltage doubler output stage is configured to provide a current sensing signal indicative of a current through the load;
the driver circuit further comprises a controller configured to receive the current sensing signal and provide the drive signal to the inverter as a function of the received current sensing signal; wherein the drive signal comprises a upper switch signal and a lower switch signal and the controller is configured to provide the upper switch signal to an upper switch of the inverter and to provide the lower switch signal to a lower switch of the inverter.
8. The driver circuit of claim 1 , wherein the inverter comprises:
a resonant inductor having a first terminal and a second terminal;
an upper switch connected between the DC power rail and a first terminal of the resonant inductor;
a lower switch connected between the first terminal of the resonant inductor and a circuit ground of the inverter;
a resonant capacitor connected between a second terminal of the resonant inductor and the circuit ground of the inverter;
a DC blocking capacitor connected between the second terminal of the resonant inductor and the output of the inverter; and
an output resistor connected between the output of the inverter and the circuit ground of the inverter.
9. A light fixture comprising:
a light source operable to provide light in response to receiving power;
a driver circuit configured to provide power from a power source to the light source, said driver circuit comprising:
an inverter having a control input, a power input, and an output, wherein:
the power input is connected to a direct current (DC) power rail; and
the inverter is configured to provide an alternating current (AC) output signal as a function of a drive signal received at the control input of the inverter;
a voltage doubler output stage having an input and an output, wherein:
the output is configured to connect to the light source;
the input of the voltage doubler output stage is connected to the output of the inverter;
the voltage doubler output stage is configured to convert the AC output signal from the inverter into a DC output signal; and
the voltage doubler output stage comprises
a first diode having an anode and a cathode,
a second diode having an anode and a cathode,
a charge capacitor having a first terminal coupled to the input of the voltage doubler output stage and a second terminal coupled to the cathode of the second diode,
a boost inductor having a first terminal connected to the cathode of the second diode and to the second terminal of the charge capacitor, and a second terminal coupled to the anode of the first diode, and
wherein the cathode of the first diode is coupled to the output of the voltage doubler output stage; and
a housing configured to support the light source and the driver circuit.
10. The light fixture of claim 9 , wherein:
the voltage doubler output stage further comprises a current sensing resistor configured to connect in series with the light source when the light source is connected to the output of the voltage doubler output stage and provide a current sensing signal indicative of a current through the light source; and
the driver circuit further comprises a controller having an output connected to the control input of the inverter, wherein the controller is configured to receive the current sensing signal and provide the drive signal to the control input of the inverter as a function of the received current sensing signal.
11. The light fixture of claim 9 , wherein:
the power source is a DC power source configured to provide DC power to the driver circuit; and
the driver circuit further comprises an input stage, said input stage comprising:
a DC to DC converter configured to receive the DC power and provide the DC power rail.
12. The light fixture of claim 9 , wherein:
the power source is an AC power source configured to provide AC power to the driver circuit; and
the driver circuit further comprises an input stage, said input stage comprising:
an electromagnetic interference (EMI) filter configured to connect to the power source and filter noise from the AC power provided by the AC power source; and
an AC to DC converter configured to receive the filtered AC power from the EMI filter and provide the DC power rail.
13. The light fixture of claim 9 , wherein:
the inverter has a circuit ground;
the voltage doubler output stage has a circuit ground; and
the circuit ground of the voltage doubler output stage is connected to the circuit ground of the inverter such that the output of the voltage doubler output stage is not electrically isolated from the power input of the inverter.
14. The light fixture of claim 9 , wherein
the light source connects between the cathode of the first diode and the circuit ground of the voltage doubler output stage.
15. The light fixture of claim 9 , wherein:
the voltage doubler output stage is configured to provide a current sensing signal indicative of a current through the light source;
the driver circuit further comprises a controller configured to receive the current sensing signal and provide the drive signal to the inverter as a function of the received current sensing signal; wherein the drive signal comprises a upper switch signal and a lower switch signal and the controller is configured to provide the upper switch signal to an upper switch of the inverter and to provide the lower switch signal to a lower switch of the inverter.
16. The light fixture of claim 9 , wherein the inverter comprises:
a resonant inductor having a first terminal and a second terminal;
an upper switch connected between the DC power rail and a first terminal of the resonant inductor;
a lower switch connected between the first terminal of the resonant inductor and a circuit ground of the inverter;
a resonant capacitor connected between a second terminal of the resonant inductor and the circuit ground of the inverter;
a DC blocking capacitor connected between the second terminal of the resonant inductor and the output of the inverter; and
an output resistor connected between the output of the inverter and the circuit ground of the inverter.
17. A DC-DC converter comprising:
a DC input including a DC power rail and a DC input circuit ground;
a converter output including load terminals configured to couple to a load;
an inverter circuit having an inverter input coupled to the DC power rail and an inverter output, the inverter circuit including a resonant inductor and a resonant capacitor;
a voltage doubler circuit having a voltage doubler input coupled to the inverter output and a voltage doubler output coupled to the load terminals;
wherein the voltage doubler circuit comprises
a first diode having an anode and a cathode,
a second diode having an anode and a cathode,
a charge capacitor having a first terminal coupled to the voltage doubler input and a second terminal coupled to the cathode of the second diode,
a boost inductor having a first terminal connected to the cathode of the second diode and to the second terminal of the charge capacitor, and a second terminal coupled to the anode of the first diode;
wherein the cathode of the first diode is coupled to the voltage doubler output; and
wherein one of the load terminals is an output common terminal electrically coupled to the DC input circuit ground.
18. The DC-DC converter of claim 17 wherein:
the voltage doubler further comprises a current sensing resistor coupled to one of the load terminals and configured to provide a current sensing signal indicative of a current through a load when the load is connected to the load terminals;
the DC-DC converter further comprises a controller having an output connected to an inverter control input; and
the controller is configured to receive the current sensing signal and provide a control signal to the inverter control input as a function of the received current sensing signal.