DUAL VOLTAGE ALTERNATOR SYSTEM

FIELD OF THE INVENTION

The present invention relates to the fields of electrical systems for use of 12 V ECU with Sensors on 24 V vehicle systems. The present invention specifically relates to a dual voltage alternator system for incorporating 12 V ECU system on 24 Vehicle by providing dual voltage supplies with different current loading requirement without the need of expensive DC/DC converter.

BACKGROUND OF THE INVENTION

Various automotive vehicles such as road vehicles, off road vehicles, and the like, utilize an internal combustion engine as a main power plant for driving of the corresponding vehicle. Various associated equipments of the internal combustion engine and the electrical or electronic controlled loads of the vehicle require electrical power. The internal combustion engine is normally provided with an electrical starter motor and other electrically operated devices. The rechargable batteries are utilized as basic power supply for starting of the vehicle as well as for operating the other vehicle loads in the absence of the vehicle engine operation.

Electrical systems of heavy industrial vehicles, buses, large heavy trucks and the like, are developed using 24 volt battery systems. However, certain loads such as electronic control units (ECU), actuators, passive and active sensors, vehicle lighting systems, sound systems and the like, were designed to operate at 12 volts. As a result, practically all 24 volt systems used in vehicles should provide additional 12 volt supply for ECUs and other accessories while providing 24 volt supply for the vehicle and other heavy loads. Since the battery, starter motor, ECUs and other low power devices require electrical power at various voltage levels, some efficient and inexpensive means is needed to provide electrical powers to both the high voltage devices and the low voltage: devices without sacrificing electrical charge balance on the batteries.

Referring to FIG. 1, a block diagram of a conventional starting system with ECU loads of a vehicle is illustrated, in accordance with a prior art. Such electrical system comprises a starter motor 105 that is coupled to an engine 102 mounted on a vehicle chassis 101. A 24 volt battery 104 is adapted for providing 24 volt supply to the starter motor 105, which drives the engine 102 of the vehicle. The conventional system of the automobile sector utilizes a DC/DC converter 106 for converting the 24 volt power supply from the 24 volt battery into 12 volt power supply, which is provided to the ECUs 107 and other accessories requiring 12 volt supply. This approach is quite cumbersome and costly affair for commercial vehicles. Since the DC-DC converters are expensive, the manufacturing cost of the overall system is increased and thus, increases the cost to end-users. Moreover, this method is adapted mostly in industrial application. Hence, it is desirable to provide a system, which is capable of providing dual voltages for operating different rated voltage & power loads in a vehicle.

OBJECT OF THE INVENTION

An object of the present invention is to provide a dual voltage alternator system for providing dual voltages of power requirements for operating different rated voltage loads in a vehicle.

Another object of the present invention is to provide a dual voltage alternator system, which avoids the need for expensive DC/DC converter.

Yet another object of the present invention is to provide a dual voltage alternator system, which avoids failure rate of electronic devices due to inappropriate power supply transient signals.

SUMMARY OF THE INVENTION

According to one aspect, the present invention, which achieves the objectives, relates to a dual voltage alternator system comprising a first power supply means for supplying constant output power of 12 volt to an electronic control unit (ECU) through a main relay. A dual voltage alternator is coupled to a vehicle engine for generating and supplying dual output voltages to the first power supply means. A regulator cum rectifier controller is connected with output terminals of the dual voltage alternator for outputting rectified output. The controller senses voltage of the first power supply means and supplies the rectified power for charging the first power supply means through a charge relay, which achieves dual voltage supply for operating different rated voltage loads in a vehicle without using expensive DC/DC converter and also minimizes failure rate of electronic devices from damage.

Furthermore, the dual voltage alternator is in connection with a conventional second power supply means for supplying and charging constant output power of 24 volt to the second power supply means. The controller charges the first power supply means when it senses that the voltage of the first power supply means is less than 14 volts. The controller controls the rectification by switching off the gate signals, when the voltage of first power supply means is higher than the output of the controller. The controller can additionally be connected to a light emitting diode (LED), which acts a charge indicator. The LED glows while the controller charges the first power supply means.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be discussed in greater detail with reference to the accompanying Figures.

FIG. 1 shows a block diagram of a conventional starting system with ECU loads of a vehicle, in accordance with a prior art;

FIG. 2 illustrates a block diagram of a proposed starting system and ECU loads with a dual voltage alternator, in accordance with an exemplary embodiment of the present invention;

FIG. 3 illustrates a circuit diagram depicting three-phase output of a dual voltage alternator, in accordance with an exemplary embodiment of the present invention;

FIG. 4 illustrates a schematic circuit diagram of a dual voltage alternator system using separate 12 V battery, in accordance with one embodiment of the present invention; and

FIG. 5 illustrates a schematic circuit diagram of a dual voltage alternator system using separate 12 V battery, in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 2, a block diagram of a starting cum ECU system of a dual voltage alternator is illustrated, in accordance with an exemplary embodiment of the present invention. The electrical system comprises a dual voltage alternator system and a starter motor 205 that is coupled to an internal combustion engine 202. The internal combustion engine 202 can be mounted on a vehicle chassis 201, where the internal combustion engine 202 is isolated from the starter motor by using an insulated +ve and -ve terminals of starter motor 205. A 24 volt battery 204 is arranged in the vehicle for providing 24 volt supply to the starter motor 205, which drives the combustion engine 202 of the vehicle.

In addition, the dual voltage alternator system is provided with a 12 volt battery 206, a dual voltage alternator 207 and a regulator cum rectifier controller 208. The 12 volt battery 206 can be adapted for supplying a constant output power of 12 volt to an electronic control unit (ECU) 208 before starting a vehicle engine. The ECU 208 is mounted on a vehicle body 203 in the vehicle chassis 201 via bolt connections. The dual voltage alternator 207 is coupled to the internal combustion engine 202, which drives the dual voltage alternator 207 to generate dual output voltages of different current ratings. Output terminals of the dual voltage alternator 207 can be connected to the 24 volt batteries 204 and the 12 volt battery 206 in order to balance the charge on both levels of batteries.

Moreover, the dual voltage alternator 207 also directly provides appropriate power at different voltage levels, i.e. 24 volts and 12 volts, to various vehicle loads during operation of the vehicle and the combustion engine 202. Thus, the dual voltage alternator 207 on the 24 volt commercial vehicle can provide the power supply of 12 volts to the ECUs 107 and other accessories to be operated at 12 volts. Hence, it is possible to achieve dual voltage supplies for operating different rated voltage loads in a vehicle without using expensive DC/DC converter and also minimizes failure rate of any electronic devices due to unwanted voltage spikes.

Referring to FIG. 3, a circuit diagram depicting three-phase output of the dual voltage alternator 207 is illustrated, in accordance with an exemplary embodiment of the present invention. Note that the same reference numbers are assigned to identical components in FIGS. 2-5. The dual voltage alternator 207 is preferably a three-phase alternator with a self-limiting current construction. The three-phase alternator 207 is provided with three phase windings, where the output of the alternator 207 is an alternating current. The output of the dual voltage alternator 207 increases with the speed. However, as the speed increases, the electrical reactance characteristic of dual voltage alternator 207 windings limits the current level to a maximum output. The voltage output is also dependent on the speed and the energization level of an exciter field winding of the alternator 207.

Futher, the alternator 207 includes a built-in voltage regulator that is connected across the output of the alternator windings to limit and maintain an appropriate nominal 24 and 12 volt supply to the 24 volt battery 204 and the 12 volt battery 206. The output terminal of the alternator 207 is additionally connected to the positive terminal of the 24 volt battery 204 through an indicator lamp 301 and an ignition switch 302 of the engine 202. Such alternator 207 eliminates the costly development of DC/DC converter for 24 volt to 12 volt conversions in automotive applications. This alternator 207 also avoids the need of external voltage transient suppressor for EDC system because of its inbuilt zener diode or avalanche diode configuration.

Referring to FIG. 4, a schematic circuit diagram of a dual voltage alternator system is illustrated, in accordance with one embodiment of the present invention. This dual voltage alternator system utilizes two separate batteries, i.e. 24 volt battery 204 and 12 volt battery 206, for appropriate power supply. Since the output of the alternator 207 is an alternating current, the three-phase output of the alternator 207 can be connected to a regulator cum rectifier controller 402. The regulator cum rectifier controller 402 rectifies the alternating current output from the output terminals of the alternator 207 into rectified DC output. The rectified DC output from the controller 402 can be supplied to the 12 volt battery 206 through a 12 volt charge relay 406 for charging the 12 volt battery 206 when the controller 402 senses that the voltage of the 12 volt battery 206 is less than 14 volts.

Moreover, the 3 phase output from the alternator 207 is processed by the regulator cum rectifier controller 402 to supply constant output voltage of 12 V with current handling capacity of 10 amps. The regulation of the 3 phase output of the alternator 207 is achieved by the regulator cum rectifier controller 402, which triggers the gate signal in a phase control mode accordingly. In case when the voltage at the 12 volt battery terminals is more than the output from the controller 402, then the controller 402 acts as voltage sensing for controlling the rectification by switching off the gate signals.

The controller 402 can additionally be connected to a light emitting diode (LED) 404, which acts a charge indicator. The LED 404 glows while the controller 402 charges the 12 volt battery 206. Similarly, the 24 volt output from the dual voltage alternator 207 is in connection with the 24 volt battery on the vehicle for providing continuous and intermittent load requirements. The 24 volt battery 204 provides the power supply to the starter motor 205 when the ignition switch 302 is switched on. The 24 volt battery 204 also supplies 24 volt power through an ignition relay 410 for other vehicle loads, which requires 24 volt power supply.
Referring to FIG. 5, a schematic circuit diagram of a dual voltage alternator system is illustrated, in accordance with another embodiment of the present invention. This dual voltage alternator system utilizes the two numbers of existing 12 V batteries 206 of 24 V system instead of separate 12 V battery for ECU as shown in FIG. 4, whereas one of the 12 volt heavy batteries 206 supply 12 volts to the ECU 208 without use of separate medium 12 V battery.

WE CLAIM :
1. A dual voltage alternator system, comprising:

a first power supply means adapted for supplying constant output power of 12 volt to an electronic control unit (ECU) through a main relay;

a dual voltage alternator coupled to and driven by a vehicle engine for generating and supplying dual output voltages of 12 V and 24 V to said first power supply means; and

a regulator cum rectifier controller connected to said dual voltage alternator for outputting rectified power, wherein said regulator cum rectifier controller senses voltage of said first power supply means and supplies the rectified power for charging said first power supply means through a charge relay.

2. The system as claimed in claim 1, wherein said dual voltage alternator is a three-phase dual voltage alternator.

3. The system as claimed in claim 1, wherein said dual voltage alternator is in connection with a second power supply means for supplying and charging constant output power of 24 volt to said second power supply means.

4. The system as claimed in claim 1, wherein said regulator cum rectifier controller connected to said ECU for direct supply of the rectified 12 V power to the said ECU.

5. The system as claimed in claim 1, wherein said regulator cum rectifier controller controls the rectification by switching off the gate signals, when the voltage of said first power supply means is higher than the output of said regulator cum rectifier controller.

6. The system as claimed in claim 1, wherein said regulator cum rectifier
controller connected to a light emitting diode (LED), which acts a charge indicator.

7. The system as claimed in claim 6, wherein said LED glows while said regulator
cum rectifier controller charges said first power supply means.