Claims:1. An electrical system (300), the electrical system (300) comprising:
an AC generator (305) having output terminals (A, B, and C) and generates an output power at an AC voltage that is dependent on a speed of the AC generator (305);
a first energy storage device (315) that operates at an operating voltage;
a AC/DC power semiconductor bridge circuit (310) having six power semiconductor devices (310-S1 to 310-S6), wherein each device can be controlled with a gate of a corresponding device, wherein the AC/DC power semiconductor bridge circuit (310) further includes an internal reverse diode (D1 to D6) across each of the power semiconductor devices (310-S1 to 310-S6) for reverse current flow, and wherein the AC/DC power semiconductor bridge circuit (310) includes input terminals (A1, B1 and C1) connected to the output terminals (A, B, and C) of the AC generator (305) and converts the AC voltage at the output terminals (A, B, and C) to obtain a DC voltage (420) at a second energy storage device (325);
a switched mode voltage reduction circuit (320) having a power semiconductor switch (320-S7) and a gate for control, wherein the switched mode voltage reduction circuit (320) is connected between the second energy storage device (325) and the first energy storage device (315); and
an embedded controller (330) operationally connected to the AC/DC power semiconductor bridge circuit (310) and the switched mode voltage reduction circuit (320), wherein the embedded controller (330) is configured to operate the electrical system (300) in one of a first mode through signals (330-1) and a second mode through a signal (330-2) based on the speed of the AC generator (305), the terminal voltage of the AC generator (305) detected from a terminal voltage feedback signal (330-3), the operating voltage, and a voltage across the second energy storage device (325) detected from a voltage feedback signal (330-4) from the second energy storage device (325),
wherein the embedded controller (330), in the first mode, controls the gates of one or more of the lower power semiconductor devices (310-S4, 310-S5 and 310-S6) to boost a voltage at the second energy storage device (325) to the operating voltage for charging of the first energy storage device (315); and
wherein the embedded controller (330), in the second mode, controls the gate of the power semiconductor switch (320-S7) to reduce the voltage at the second energy storage device (325) to the operating voltage for charging the first energy storage device (315) by the controlled operation of the power semiconductor switch (320-S7).

2. The electrical system (300) as claimed in claim 1, wherein the embedded controller (330) selects the first mode of operation when the voltage across the second energy storage device (325) is less than the operating voltage of the first energy storage device (315).

3. The electrical system as claimed in claim 1,wherein in the first mode, the embedded controller (330) controls the gates of one or more of the lower power semiconductor devices (310-S4, 310-S5 and 310-S6) at a switching frequency and a duty cycle (465) having ON time period Ton (465-a), and wherein the switching frequency is in a range from about 10 to 20 times the operating frequency measured from the terminal voltage feedback signal (330-3), and the Ton (465-a) is dependent on the terminal voltage of the AC generator (305) and the impedance characteristic of windings of the AC generator (305) for the operating speeds.

4. The electrical system as claimed in claim 3, wherein in the first mode, the embedded controller (330) dynamically adjusts the Ton (465-a) based on a computation of the inductance of the windings (305-a, 305-b, and 305-c) of the AC generator (305) from an actual operating speed of the AC generator (305) and the impedance characteristics stored in a non-volatile memory of the embedded controller (330) dependent on speed.

5. The electrical system (300) as claimed in claim 4, wherein the non-volatile memory of the embedded controller (330) stores the impedance characteristics of the windings (305-a, 305-b, and 305-c) of the AC generator (305) for predefined operating speeds and the embedded controller (330) interpolates the inductance computation from the nearest inductance characteristic stored values of the nearest higher speed and a lower speed to the actual operating speed.

6. The electrical system (300) as claimed in claim 1, wherein in the first mode, the embedded controller (330) continuously switches ON the power semiconductor switch (320-S7).

7. The electrical system (300) as claimed in claim 1, wherein the embedded controller (330) selects the second mode of operation when the voltage across the second energy storage device (325) is more than the operating voltage of the first energy storage device (315).

8. The electrical system (300) as claimed in claim 1, wherein the switched mode voltage reduction circuit (320) is a step down DC/DC voltage converter.

9. The electrical system (300) as claimed in claim 1, wherein the first energy storage device (315) includes one or more battery cells operating at the operating voltage.

10. The electrical system (300) as claimed in claim 1, wherein the second energy storage device (325) is a capacitor.

11. The electrical system (300) as claimed in claim 1, wherein the AC/DC power semiconductor bridge circuit (310) is a controlled rectifier, and wherein the six power semiconductor devices (310-S1 to 310-S6) are MOSFETs.

12. The electrical system (300) as claimed in claim 1, wherein the electrical system (300) comprises a third energy storage device (340) connected across the first energy storage device (315).

13. The electrical system (300) as claimed in claim 1, wherein the electrical system (300) detects the speed of the AC generator (305) from the frequency measured from the terminal voltage feedback signal (330-3) to the embedded controller (330).

14. A method for operating an electrical system (300), the method comprising:
measuring a terminal voltage of an AC generator (305);
measuring a voltage across a second energy storage device (325), wherein the measured voltage is in the form of a DC voltage;
detecting an operating speed of the AC generator (305) based on a frequency of the measured terminal voltage of the AC generator (305);
operating the electrical system (300), by an embedded controller (330), in one of a first mode through signals (330-1) and a second mode through a signal (330-2), based on the operating speed of the AC generator (305) detected from a terminal voltage feedback signal (330-3), the terminal voltage of the AC generator (305) detected from the terminal voltage feedback signal (330-3), an operating voltage of a first energy storage device (315), and the measured voltage across the second energy storage device (325), wherein the operating the electrical system (300) comprises:
controlling gates of one or more of lower power semiconductor devices (310-S4, 310-S5 and 310¬-S6) of an AC/DC power semiconductor bridge circuit (310) in the first mode to boost the voltage at the second energy storage device (325) to the operating voltage and thereby enabling charging of a first energy storage device (315), when the embedded controller (330) selects the first mode of operation; and
controlling a gate of a power semiconductor switch (320-S7) of a switched mode voltage reduction circuit (320) in the second mode of operation to reduce a voltage at the second energy storage device (325) to the operating voltage for charging the first energy storage device (315) by the controlled operation of the power semiconductor switch (320-S7), when the embedded controller (330) selects the second mode of operation.

15. The method as claimed in claim 14, wherein the embedded controller (330) selects the first mode of operation when the voltage across the second energy storage device (325) is less than the operating voltage of the first energy storage device (315).

16. The method as claimed in claim 14, wherein the embedded controller (330) controls the gates of one or more of the lower power semiconductor devices (310-S4, 310-S5 and 310-S6) at a switching frequency and a duty cycle (465) having ON time period Ton (465-a), and wherein the switching frequency is in a range from about 10 to 20 times an operating frequency measured from the terminal voltage feedback signal (330-3), and the Ton (465-a) is dependent on the terminal voltage of the AC generator (305) and impedance characteristics of the windings of the AC generator (305) for the operating speeds.

17. The method as claimed in claim 15, wherein the embedded controller (330) dynamically adjusts the Ton (465-a) based on a computation of the inductance of the windings (305-a, 305-b, and 305-c) from an actual operating speed of the AC generator (305) and the impedance characteristics stored in a non-volatile memory of the embedded controller (330) dependent on speed.

18. The method as claimed in claim 16, wherein the non-volatile memory of the embedded controller (330) stores the impedance characteristics of the windings (305-a, 305-b, and 305-c) of the AC generator (305) for predefined operating speeds and the embedded controller (330) interpolates the inductance computation from the nearest inductance characteristic stored values of the nearest higher speed and a lower speed to the actual operating speed.

19. An electrical system assembly comprises a housing (800), the housing (800) comprising:
an AC generator (305) having:
a rotor (820);
a stator (810) having windings (815); and
a plate (825) fastened to a radial upper periphery of the stator (810) and the windings (815) are provided radially inward with respect to the radial upper periphery so as to be positioned on an inner cavity of the rotor (820); and
a set of electronic power semiconductor devices and control components (805) mounted on the plate (825), wherein the set of electronic power semiconductor devices and control components (805) including:
a AC/DC power semiconductor bridge circuit (310);
a switched mode voltage reduction circuit (320); and
an embedded controller (330) operationally connected to a AC/DC power semiconductor bridge circuit (310) (310).

20. The electrical system assembly as claimed in claim 19, wherein the plate (825) is made from aluminum.
, Description:As Attached