Power supply circuit with multiple stages for converting high voltage to low voltage and power train having the same

1. A power supply circuit with a plurality of stages for converting a first voltage to a second voltage where the first voltage is greater than the second voltage, wherein each stage of the power supply circuit comprises:

a first circuit block configured to provide a start-up power to a second circuit block;

the second circuit block configured to generate a Pulse-Width-Modulation (PWM) signal that controls a pulse duration of a transistor;

a third circuit block configured to activate or deactivate the transistor based on the PWM signal;

a fourth circuit block configured to reset a magnetic flux in a transformer to a zero state when the transistor is deactivated; and

a fifth circuit block configured to maintain an output of a stage below a predetermined value by adjusting a voltage across the transformer,

wherein the first circuit block comprises:

a first diode electrically connecting a resistor and a first capacitor, wherein the resistor and the first capacitor are connected to an input of the stage; and

a second diode electrically connecting a second capacitor and the fifth circuit block,

wherein the first diode and the second diode are configured to maintain a voltage across a third capacitor included in the fifth circuit block greater than a voltage across the first capacitor when a power supply in the stage is above a predetermined threshold.

2. The power supply circuit of claim 1 , wherein the second circuit block comprises:

a PWM generator electrically connected to a PWM controller, wherein the PWM generator is configured to:

generate a logic signal indicating whether a sufficient voltage is present at the stage when a voltage across the second capacitor reaches a predetermined state.

3. The power supply circuit of claim 2 , wherein the third circuit block comprises:

the transistor configured to:

cause a current flow that builds the magnetic flux in the transformer when the transistor is activated; and

generate a status signal indicating whether an over-current or an under-current is present at the stage.

4. The power supply circuit of claim 3 , wherein the fourth circuit block comprises:

a third diode electrically connected to the transformer; and

a fourth diode configured to provide a rectified voltage as an input of a next stage,

wherein the transformer is configured to isolate the input of the stage from the output of the stage.

5. The power supply circuit of claim 4 , wherein the fifth circuit block comprises:

a fifth diode electrically connecting the third capacitor and the transformer, wherein the voltage across the third capacitor is generated to regulate a power flow from the stage to the next stage.

6. The power supply circuit of claim 5 , wherein the stage further comprises:

a status comparator configured to:

compare the voltage across the second capacitor with the logic signal; and

output a pass signal when the voltage across the second capacitor meets a predetermined threshold; and

a digital isolator configured to:

pass, to another digital isolator included in the next stage, a set of signals including the pass signal, the PWM signal, and the status signal.

7. The power supply circuit of claim 5 , wherein a final stage further comprises:

a power converter diagnosis system configured to:

receive the set of signals;

determine whether the stage meets a self-diagnosis measurement; and

output a diagnosis signal when the stage is determined to meet the self-diagnosis measurement.

8. The power supply circuit of claim 1 , wherein a number of the plurality of stages is determined based on a voltage at an input of a first stage.

9. The power supply circuit of claim 1 , wherein a functional creepage distance or a minimum creepage distance is maintained within the transformer depending on the stage.

10. A power train in a vehicle comprising:

a generator connecting an engine and a first power converter;

a second power converter connected to a motor, wherein the first power converter and the second power converter are connected through a DC bus; and

a power supply circuit with a plurality of stages configured to convert a first voltage to a second voltage where the first voltage is greater than the second voltage, wherein the power supply circuit is connected to the DC bus,

wherein each stage of the power supply circuit comprises:

a first circuit block configured to provide a start-up power to a second circuit block;

the second circuit block configured to generate a Pulse-Width-Modulation (PWM) signal that controls a pulse duration of a transistor;

a third circuit block configured to activate or deactivate the transistor based on the PWM signal;

a fourth circuit block configured to reset a magnetic flux in a transformer to a zero state when the transistor is deactivated; and

a fifth circuit block configured to maintain an output of a stage below a predetermined value by adjusting a voltage across the transformer,

and wherein the first circuit block comprises:

a first diode electrically connecting a resistor and a first capacitor, wherein the resistor and the first capacitor are connected to the DC bus; and

a second diode electrically connecting a second capacitor and the fifth circuit block,

wherein the first diode and the second diode are configured to maintain a voltage across a third capacitor included in the fifth circuit block greater than a voltage across the first capacitor when a power supply in the stage is above a predetermined threshold.

11. The power train of claim 10 , wherein the second circuit block comprises:

a PWM generator electrically connected to a PWM controller, wherein the PWM generator is configured to:

generate a logic signal indicating whether a sufficient voltage is present at the stage when a voltage across the second capacitor reaches a predetermined state.

12. The power train of claim 11 , wherein the third circuit block comprises:

the transistor configured to:

cause a current flow that builds the magnetic flux in the transformer when the transistor is activated; and

generate a status signal indicating whether an over-current or an under-current is present at the stage.

13. The power train of claim 12 , wherein the fourth circuit block comprises:

a third diode electrically connected to the transformer; and

a fourth diode configured to provide a rectified voltage as an input of a next stage,

wherein the transformer is configured to isolate an input of the stage from the output of the stage.

14. The power train of claim 13 , wherein the fifth circuit block comprises:

a fifth diode electrically connecting the third capacitor and the transformer, wherein the voltage across the third capacitor is generated to regulate a power flow from the stage to the next stage.

15. The power train of claim 14 , wherein the each stage further comprises:

a status comparator configured to:

compare the voltage across the second capacitor with the logic signal; and

output a pass signal when the voltage across the second capacitor meets a predetermined threshold; and

a digital isolator configured to:

pass, to another digital isolator included in the next stage, a set of signals including the pass signal, the PWM signal, and the status signal.

16. The power train of claim 15 , wherein a final stage further comprises:

a power converter diagnosis system configured to:

receive the set of signals;

determine whether the each stage meets a self-diagnosis measurement; and

output a diagnosis signal when the each stage is determined to meet the self-diagnosis measurement.

17. The power train of claim 10 , wherein a number of the plurality of stages is determined based on a voltage at an input of a first stage.

18. The power train of claim 10 , wherein a functional creepage distance or a minimum creepage distance is maintained within the transformer depending on the stage.