ALTERNATOR SYSTEM

• US 20030039130A1
• Filed: 08/30/2002
• Published: 02/27/2003
• Est. Priority Date: 03/09/2000
• Status: Active Grant

• Current Assignee: Ecoair Corp.
• Original Assignee: Ecoair Corp.
• Inventors: Curtiss, William P.
• Granted Patent: US 6,545,884 B2
• Time in Patent Office: Days
• US Class Current: 363/37
• CPC Class Codes: G05F 1/613 using semiconductor devices in parallel with the load as final control devices G05F1/461 takes precedence
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: H02J 7/1492 by means of controlling devices between the generator output and the battery
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/009 having two or more independently controlled outputs for DC-DC converter with intermediate AC H02M3/33561
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/1563 without using an external clock H02M3/158 takes precedence
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• CPC Class Codes: H02M 7/06 using discharge tubes without control electrode or semiconductor devices without control electrode
• CPC Class Codes: H02P 9/305 controlling voltage H02P9/302 takes precedence
• CPC Class Codes: H02P 9/307 more than one voltage output
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Abstract

An alternator system (50, 52) that, in one aspect, utilizes a Lundell style alternator that is augmented by power electronic switching components (62) in the output section. In one embodiment, some of these power switching embodiments employ a scaling of stator turns and wire size to achieve the superior performance at higher speeds. The alternator system provides significantly enhanced power capability above idle as compared with classical Lundell alternator systems using Lundell alternators of the same size that are designed with the same power capability at idle. In one preferred dual voltage embodiment, a power switch (semi-conductor) connects the alternator output directly to the low voltage load at low engine speeds and when the power switch is “opened” at higher speeds, the alternator'"'"'s power is channeled to the higher voltage. In a 14-volt/42-volt dual-voltage system, this arrangement provides triple the alternator'"'"'s power capability at high speeds as compared to a conventional unenhanced capabilities of the altenator system of the present invention are accomplished without increasing the alternator size or required current capacity and without using high frequency semiconductor power modulation (106).

Claims

1. A system for enhancing the power output capability of a field controlled alternator having a field winding input and either a single phase or multi-phase alternator stator winding, the system comprising:

a power switching circuit including rectification circuitry for providing a full-wave rectified alternator output, inputs for receiving stator voltages, an input for receiving an operational state command, and a plurality of output voltage nodes, the power switching circuit being configured so that one operational state command effects connection of the alternator'"'"'s full-wave rectified output to one of the output voltage nodes and electrically isolates said one of the output voltage nodes from the remaining output voltage nodes, and another operational state command effects connection of the alternator'"'"'s full wave rectified output to another one of the output voltage nodes and electrically isolates said another one of the output voltage nodes from the remaining output voltage nodes;

an operational state command generator that includes circuitry for determining which operational state command to apply to the power switching circuit, the operational state command generator circuit effecting relatively more effective time in which the power switching circuit has operational states that are associated with relatively higher node voltages as the speed of the alternator increases thereby allowing the equivalent average rectified output of the alternator to increase with the speed of the alternator; and

a voltage regulation circuit for providing a variable current to the field winding input of the alternator so as to maintain the magnitude of one of the node voltages.

2. The system according to claim 1 wherein the plurality of output voltage nodes comprises (n) output voltage nodes, and wherein the power switching circuitry includes (n−

1) switching elements that enable the power switching circuit to transition from one operational state to another operational state.

3. The system according to claim 1 wherein one of the output voltage nodes is a zero voltage node.

4. The system according to claim 1 wherein the output voltage nodes are numerically designated and arranged in a progressive configuration according to the magnitudes of the node voltages.

5. The system according to claim 1 further comprising a plurality of system outputs, some of the system outputs being directly connected to some of the output voltage nodes and some of the system outputs being indirectly connected to the output voltage nodes though auxiliary components such as filters or DC-DC converters.

6. The system according to claim 1 further comprising a plurality of capacitive elements, at least some of the capacitive elements being connected between a pair of output voltage nodes.

7. The system according to claim 6 wherein at least some of the capacitive elements are connected between the output voltage nodes and circuit ground so as to filter the node voltages.

8. The system according to claim 5 wherein one or more of the system outputs are connected to a battery.

9. The system according to claim 5 further including a DC-DC converter having signal terminals connected to the output voltage nodes and other system outputs.

10. The system according to claim 5 wherein the voltage regulator circuit is configured to regulate a voltage that is associated with a system output.

11. The system according to claim 1 further comprising an inductor that is connected between the full-wave rectified output and the output voltage nodes.

12. The system according to claim 1 wherein the voltage regulation circuit is configured to limit a node voltage.

13. The system according to claim 1 wherein the operational state command generator is configured to provide operational state commands that enable the power switching circuit to consecutively and discretely transition to operational states that are associated with relatively higher node voltages when the speed of the alternator attains predetermined discrete speeds while the alternator speed is increasing.

14. The system according to claim 13 wherein the operational state command generating circuit includes circuitry for setting each predetermined discrete alternator speed at which an operational state transition occurs while the alternator speed is accelerating to an alternator speed that corresponds to a maximum regulatable load wherein an operational state transition to a next relatively higher operational state results in generally the same maximum regulated output capability in said next relatively higher operational state.

15. The system according to claim 14 wherein the operational state command generator is configured to provide operational state commands that enable the power switching circuit to consecutively and discretely transition to operational states that are associated with relatively lower node voltages when the speed of the alternator attains different discrete speeds while the alternator speed is decreasing and said different discrete speeds are relatively less than said predetermined discrete speeds, and wherein said different discrete speeds are chosen so as to substantially eliminate mode chatter as the power switching circuit transitions from one operational state to another operational state.

16. The system according to claim 1 wherein the operational state generating circuit includes pulse width modulating circuitry that is responsive to alternator speed, the pulse width modulating circuitry that effects transitioning of the power switching circuit from one operational state to another operation state, the pulse width modulating circuitry having a duty cycle and an input for receiving a signal that represents instantaneous alternator speed, the pulse width modulating circuitry being configured so that the duty cycle increases as the alternator speed increases and decreases as the alternator speed decreases.

17. The system according to claim 16 wherein the pulse width modulating circuitry is configured so that the duty cycle varies proportionately from 0% to 100% as the alternator speed changes from first speed to a second speed wherein the ratio of the second speed to the first speed is generally the same as the ratio of a node voltage corresponding to a first operational state to a second relatively lower node voltage corresponding a second operational state.

18. The system according to claim 1 wherein the voltage regulating circuit comprises a closed loop control circuit that further effects regulation of and is responsive to one of the output voltage nodes, the closed loop control circuit varying the duty cycle of the particular pulse width modulating circuitry output signal that causes the power switching circuitry to operate between operational states such that the node voltage is controlled.

19. The system according to claim 18 further wherein the closed loop circuit includes circuitry for varying the alternator field current in order to regulate the other node voltage associated with said another one of the plurality of output voltage nodes.

20. The system according to claim 19 wherein in a first one of the operational states, one of the output voltage nodes provides zero volts and in a second one of the operational states, one of the output voltage nodes provides a primary voltage, the power switching circuit being configured to effectively short out all alternator windings while electrically isolating the other output voltage nodes.

21. The system according to claim 16 further comprising overload power maximization circuitry that comprises:

circuitry for measuring DC bridge current;

circuitry for receiving a reference signal representing optimum power and generating a error signal that represents the difference between the DC bridge current and the reference signal;

means for inputting the error signal into the pulse width modulating circuitry, the error signal increasing the duty cycle of the pulse width modulating circuit so as to increase the time in which the full-wave rectified output is connected to the output voltage nodes that are associated with a relatively higher node voltages.

22. A system for enhancing the power output capability of a field controlled alternator having a field winding input and either a single phase or multi-phase alternator stator winding, the circuitry comprising:

a full-wave rectifier circuit including a DC bridge circuit for receiving an AC voltage from the alternator and providing a full-wave rectified output voltage;

a closed-loop pulse width modulated switching regulator circuit which steps down the full wave rectified output voltage to provide a relatively lower regulated DC output voltage; and

a field winding control circuit for limiting the full-wave rectified output voltage to a predetermined magnitude and to effect reduction in filed current during relatively light alternator loading situations.

23. The system according to claim 22 further comprising overload power maximization circuitry that comprises:

circuitry for measuring DC bridge current;

circuitry for receiving a reference signal representing optimum power and generating a error signal that represents the difference between the DC bridge current and the reference signal;

means for inputting the error signal into the pulse width modulating circuitry, the error signal effecting a decrease in the duty cycle of the pulse width modulating circuit so as to effectively limit the DC bridge current and maximize alternator power capability.

24. The system according to claim 22 further comprising overload power maximization circuitry that comprises:

circuitry for measuring alternator speed;

circuitry for measuring DC bridge voltage;

circuitry for generating a error signal that represents the difference between the signal representing DC bridge voltage and the signal representing alternator speed;

means for inputting the error signal into the pulse width modulating circuitry, the error signal effecting a decrease in the duty cycle of the pulse width modulating circuit so as to effectively limit the DC bridge current and maximize alternator power capability.