WO2006136100A1

WO2006136100A1 - Power supplying device and power supplying method

Info

Publication number: WO2006136100A1
Application number: PCT/CN2006/001407
Authority: WO
Inventors: Jianhua Zhang; Hongbo Yu; Jun Qi; Lin Li
Original assignee: Byd Company Limited
Priority date: 2005-06-22
Filing date: 2006-06-21
Publication date: 2006-12-28
Also published as: CN1885672A

Abstract

A power supplying device comprises a DC/DC power supplying module, a storage battery, a charging module and an isolating diode. The input terminal of the DC/DC power supplying module is connected to the input terminal of the charging module to receive the electric power from an external DC power source. The output terminal of the charging module is connected to the positive electrodes of both the isolating diode and the storage battery. The negative electrode of the storage battery is grounded. The negative electrode of the isolating diode is connected to the output terminal of the DC/DC power supplying module to supply electric power to a load.

Description

Power Supplying Device and Power Supplying Method

Field of the Invention

[001] The present invention relates to a power supplying device, and particularly to a power supplying device and a power supplying method using a DC power source and a lead-acid battery connected in parallel.

Description of the Related Art

[002] Figure 1 is a schematic diagram showing a power supplying device in prior art. As shown in figure 1 , most DC power sources for electric apparatus equipped in electric vehicles supply electrical power to loads through a main power supplying circuitry and a standby power supplying circuitry connected in parallel, wherein a

DC/DC circuitry such as PWM (Pulse Width Modulation) switching mode power supply may be employed as the main power supplying circuitry, and a storage battery such as a lead-acid battery may be used as the standby power supplying circuitry. In this manner, the DC/DC circuitry generally has poor anti-current-impulse capability, and can not automatically change the supplying power depending on the variation of loads, therefore the voltage will be rapidly pull-down under the condition of large current output so as to affect the improvement of power supplying efficiency. Furthermore, there is no isolating element between the main DC/DC circuitry and the charging module, thereby the charging safety cannot be guaranteed.

Summary of the Invention

[003] The object of the present invention is to solve the drawbacks of prior art in poor anti-current-impulse capability and low power supplying efficiency, and to provide a reliable and high-efficiency power supplying device and method.

[004] A power supplying device according to the present invention comprises a DC/DC power supplying module, a storage battery, wherein, the device further comprises a charging module and an isolating diode, and the input terminal of the DC/DC power supplying module is connected to the input terminal of the charging module to receive the electrical power from an external DC power source; the output terminal of the charging module is connected to positive electrodes of both the isolating diode and the storage battery; the negative electrode of the storage battery is grounded; and the negative electrode of the isolating diode is connected to the output terminal of the DC/DC power supplying module to supply electrical power to a load.

[005] The present invention further provides a power supplying method comprising a step of connecting the output terminal of a power supplying device with a load to provide electrical power to the load, wherein, the power supplying device is the one provided by the present invention described above.

[006] The device and method provided by the present invention take advantage of the characteristic in that the output voltage of the storage battery is relatively stable, that is, a sudden increase in output current will not result in a rapid decrease in output voltage of the storage battery, therefore the drawbacks that the output voltage is extremely low under the situation of instant overload, could be efficiently overcome, so that a stable output voltage can be guaranteed. Moreover, using a circuit layout with multiple modules connected in parallel may result in an enlarged range of instant power output and improved anti-instant-impulse capability, so that an flexible power adjustment may be obtained to meet the power supplying requirements for a majority of loads and improve the system stability and robustness. Furthermore, parallel connection of respective modules may help each module to have good independence from each other and make it easy for maintenance. Finally, the charging safety may be enhanced due to the isolation between the DC/DC power supplying device and the charging module performed by the isolating diode, and also, the storage battery, which is in a state of being charged for most time due to the above isolation, may show an advantage in sufficient-power and good-performance. Brief Description of the Drawings

[007] Figure 1 is a schematic diagram showing a power supplying device in prior art.

[008] Figure 2 is a block diagram showing a power supplying device provided by the present invention.

[009] Figure 3 is a flow chart showing the power supplying method provided by the present invention.

Description of the Preferred Embodiments [010] Now the embodiments according to the present invention will be described in detail in reference to the drawings.

[011] As shown in figure 2, the power supplying device provided by the present invention includes a DC/DC power supplying module 2, a storage battery B, a charging module 1 and an isolating diode D, wherein, the input terminal of the DC/DC power supplying module 2 is connected to the input terminal of the charging module 1 to receive the electrical power from an external DC power source; the output terminal of the charging module 1 is connected to positive electrodes of both the isolating diode D and the storage battery B; the negative electrode of the storage battery B is grounded; and the negative electrode of the isolating diode D is connected to the output terminal of the DC/DC power supplying module 2 to supply electrical power to a load R.

[012] As shown in figure 2, in normal state, that is when the load R is small, the load R is only electrically powered by the DC/DC power supplying device 2, and at this time, the voltage difference between two terminals of the isolating diode D is insufficient to turn on the isolating diode D, and the storage battery B is in a state of being charged or standby. When the load R suddenly increases and reaches a predetermined maximum threshold, the voltage at the output terminal of the DC/DC power supplying device 2 may have an instant decrease, and when the voltage is decreased to a certain level such that the isolating diode D is turned on, the storage battery B begins to supply power to the load R. Further, when the voltage applied to the load R is increased until the voltage difference between two terminals of the isolating diode D is lower than the forward threshold voltage thereof, the isolating diode D is shut off and the storage battery B is in a state of being charged. Accordingly, the utilization of the device provided by the present invention may improve the power safety and reliability, and also, the storage battery, which is in a state of being charged for most of time, may show an advantage in sufficient-power and good-performance.

[013] The DC/DC power supplying device 2 and the charging module 1 may be any types of current DC/DC converters, such as a single-ended forward type, single-ended fly-back type, full bridge type and so on.

[014] According to the present invention, each of the DC/DC power supplying device 2 and the charging module 1 comprises at least two single-ended fly-back DC/DC modules connected in parallel or a high power full bridge DC/DC module. And preferably, the number of the single-ended fly-back DC/DC modules is 2-10. The usage of a circuit layout with multiple modules connected in parallel may result in an enlarged range of instant power output and improved anti-instant-impulse capability, so that an flexible power adjustment may be obtained to meet the power supplying requirements for a majority of loads and improve the system stability and robustness. [015] According to the preferred embodiment, the single-ended fly-back DC/DC module is a single-ended fly-back switching mode power supply employing a PWM chip with current control mode. The PWM chip may include a variety of chips such as UC3842 and UC3843 manufactured by Unitrode Inc. The above two chips, which are widely applicable in low-power switching mode power supply with a voltage ranged in 4.9-5. IV and a power ranged in 20-60W, are popular PWM signal generators with current control mode and have advantages of high precision, stable voltage, simple peripheral circuit and low price.

[016] Preferably, the full bride DC/DC module is a full bridge switching mode power supply adopting a PWM chip with current control mode. The PWM chip described here may include UC3846and SG3525 manufactured by Unitrode Company and STMicroelectronics Inc., respectively. The above two chips, which are widely applicable in low-power or intermediate-power switch mode power are popular PWM signal generators with current control mode and have advantages of high precision, stable voltage, simple peripheral circuit and low price. [017] It could be understood by those skilled in the art that the DC/DC power supplying module 2 and the charging module 1 could be different or identical types. For example, both of them may employ single-ended fly-back type, or the DC/DC power supplying module 2 may employ single-ended fly-back type while the charging module 1 may employ full bridge type. Further, the above description is just directed to the types of both modules, for each different power supplying device, the specification and performance of the DC/DC power supplying module 2 and the charging module 1 may vary depending on the actual requirement of the load, capacity of the storage battery and so on. This may be implemented by those skilled in the art without any inventive efforts, hereby the detailed description will be omitted. [018] The storage battery B, whose energy is mainly supplied by the charging module 1, may be any types of batteries equipped in current vehicles. Generally, when the requirement of loads is not very high, the storage battery B is in a state of being charged or standby. Only after the load R reaches a predetermined maximum threshold and when the output voltage of DC/DC power supplying module 1 drops to a level lower than the voltage of storage battery B and the voltage difference between two terminals of the isolating diode D is higher than the forward threshold voltage thereof, the storage battery B begins to supply power to the load R by changing its state from being charged to discharging and to compensate the insufficient output power caused by the voltage decrease in DC/DC power supplying module 2, such that the load R may be electrically powered by the storage battery B and the DC/DC power supplying module 2 together. The capacity of the storage cell B can be ranged between 12V/24AH to 12V/65AH, and preferably, the storage battery is a 12V/36AH maintenance-free lead-acid battery. This output voltage of this type of storage battery is relatively stable and may not have a rapid decrease with the increase of output current so that the power supplying stability can be guaranteed. [019] The isolating diode D can be selected from any appropriate types of diodes, such as common rectifying diodes, Schottky diode, Super Fast & Ultra Fast Recovery diode and so on. The voltage and current of the diode may be ranged within 20V-200V and 50A-500A respectively, preferably 100V/200A which has the advantages of a certain redundancy for voltage and current, safety and low heat emission. The isolating diode D can keep the storage battery B to be a state of being charged for most of time and to maintain sufficient power and good performance. Meanwhile, the storage battery B could be controlled to supply power to the loads depending on the load variation. [020] The present invention further provides a power supplying method comprising steps of connecting the output terminal of a power supplying device with a load to provide electrical power to the load, wherein, the power supplying device is the one provided by the present invention described above.

[021] As shown in figure 2, according to the method provided by the present invention, said output terminal refers to the output terminal of the DC/DC power supplying module 2, in other words, the negative electrode of the isolating diode D.

[022] Said load according to the method may be any devices that need power supply, such as a motor, an electric apparatus and so on. The power supplying method provided by the present invention is particularly suitable for the loads of vehicles, such as a motor and an electric apparatus equipped in the vehicles.

[023] Figure 3 is a flow chart showing the power supplying method provided by the present invention. As shown, the power supplying method normally includes main power supplying step 100. At step 100, the load R is powered by the DC/DC power supplying module 2. [024] The method may further include auxiliary power supplying step 200. At step 200, when the voltage difference between two terminals of the isolating diode D is higher than the forward threshold voltage thereof, the isolating diode D is turned on and the load R is powered by the storage battery B and the DC/DC power supplying module 2 through the isolating diode D. [025] The method may further include charging step 300, in which, when the isolating diode D is shut off, the storage battery B is charged by the charging module 1.

[026] Generally, when a load in vehicles are powered, the main power supplying step 100, auxiliary power supplying step 200 and charging step 300 are simultaneously or alternatively performed since the electric apparatus such as a motor equipped in vehicles are always changing.

[027] For example, the main power supplying step 100 may be independently performed and at this time the storage battery B is in a state of standby. The main power supplying step 100 and charging step 300 may be simultaneously performed and at this time the storage battery B is being charged by the charging module 1.

[028] Further, generally, the auxiliary power supplying step 200 is independently performed, or simultaneously performed with charging step 300.

[029] While the present invention has been described with reference to exemplary embodiments thereof, it will be apparent to those skilled in the art that various modifications can be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims

1. A power supplying device, comprising a DC/DC power supplying module and a storage battery, wherein, the device further comprises a charging module and an isolating diode, the input terminal of the DC/DC power supplying device is connected to the input terminal of the charging module to receive the electrical power from external DC power source; the output terminal of the charging module is connected to the positive electrode of the isolating diode and the positive electrode of the storage battery respectively; the negative electrode of the storage battery is grounded; and the negative electrode of the isolating diode is connected to the output terminal of the DC/DC power supplying module to supply electrical power to a load.

2. The device as set forth in claim I₉ wherein each of the DC/DC power supplying device and the charging module comprises at least two single-ended fly-back DC/DC modules connected in parallel or a high power full bridge DC/DC module.

3. The device as set forth in claim 2, wherein the number of the single-ended fly-back DC/DC modules is 2-10.

4. The device as set forth in claim 2, wherein the single-ended fly-back DC/DC module is a single-ended fly-back switching mode power supply comprising a PWM chip with current control mode.

5. The device as set forth in claim 4, wherein the PWM chip is UC3842 or

UC3843.

6. The device as set forth in claim 2, wherein, the full bride DC/DC module is a full bridge switching mode power supply comprising a PWM chip with current control mode.

7. The device as set forth in claim 2, wherein the PWM chip is UC3846 or SG3525.

8. The device as set forth in claim 2, wherein the storage battery is a 12V/36AH maintenance-free lead-acid battery.

9. The device as set forth in claim 2, wherein the isolating diode is a 100V/200A diode.

10. A power supplying method comprising connecting the output terminal of a power supplying device to a load to supply electrical power to the load, wherein the power supplying device is any one selected from claim 1 to claim 9.