TWI398073B - Power switching apparatus and method thereof - Google Patents

Description

Power switching device and method thereof

The present invention relates to a power switching device and a method thereof, and more particularly to a power switching device capable of generating a smooth voltage curve during power switching, and a method thereof.

The current communication system used in the car, in addition to the vehicle power supply, most of the communication system itself has a backup battery. When the vehicle power supply is powered off, the backup battery continues to supply power to maintain the communication system. The electricity required for work.

This communication system usually includes Global Positioning Module (GPS), Bluetooth (BT) or General Packet Radio Service (GPRS) modules. When these modules are used, they will need to maintain high power at certain times to provide The transient high current is input to the vehicle communication system.

Please refer to FIG. 1 , which is a schematic diagram of voltage switching from different power sources of a conventional power switching device. In the figure, when the voltage supplied by the vehicle power supply is removed, a filter capacitor having a large capacitance value at the output of the DC to DC voltage converter exists, and the conventional power switching device is By directly measuring the voltage of the DC-to-DC voltage converter output, the corresponding measurement control circuit uses a diode or a bipolar transistor plus a voltage dividing resistor. If the diode is used, the existing filter capacitor discharges slowly, so the switching speed is slowed down, and the vehicle supply cannot be switched to the backup battery in time, resulting in a voltage drop phenomenon in the figure, resulting in intermittent power failure, which is easy to cause The GPS or GPRS module is restarted, or the information lost in the use of GPS or GPRS modules. If a bipolar transistor is used with a voltage dividing resistor, since the bipolar transistor has a temperature drift and the ratio of the voltage dividing resistor is large, a large proportional coefficient will amplify the temperature drift. The influence of road stability, and usually the operating temperature range required by the vehicle equipment is relatively wide, generally -40 ° C ~ 85 ° C, so the circuit design of this structure can not meet the low temperature and high temperature working environment at the same time, which will also cause the above problems.

In view of the above problems of the prior art, the object of the present invention is to provide a power switching device and a method thereof, which use a reasonable detection circuit to improve the switching speed and avoid the influence of temperature drift, thereby solving the power failure during the power switching process. problem.

In accordance with the purpose of the present invention, a power switching device is provided for use in a vehicle communication system. The power switching device includes a main power supply, a voltage conversion circuit, a backup power supply, a switching circuit, and a temporary power supply. The main power source is used to provide a first voltage. The voltage conversion circuit is coupled to the main power source to receive the first voltage and convert the first voltage into a second voltage to provide the second voltage to the vehicle communication system. The switching circuit is connected to the voltage conversion circuit, the backup power supply and the vehicle communication system, and detects one of the first voltage value or the second voltage value of the second voltage, when the first voltage value or the second voltage value is less than one When the threshold is thresholded, the switching circuit switches the main power supply to the standby power source to supply power to the vehicle communication system. One end of the temporary power supply is connected between the voltage conversion circuit, the switching circuit and the vehicle communication system to provide the power required for the vehicle communication system during the switching process.

The switching circuit further includes a detection control unit and a switch unit connected in series between the voltage conversion circuit and the standby power source, and the detection control unit detects the first voltage value or the second voltage value, and is turned on by the detection control unit or Turn off this switch unit.

The power switching device further includes a charging circuit connected between the voltage converting circuit and the standby power source to charge the standby power source.

In addition, the present invention further provides a power switching method applied to a vehicle communication system, and the power switching method includes the following steps. First, a first voltage is supplied using a main power source. Reuse one The voltage conversion circuit converts the first voltage to a second voltage. Then, a switching circuit detects a first voltage value of the first voltage or a second voltage value of the second voltage. When the first voltage value or the second voltage value is less than a threshold, the switching circuit switches the main power to Backup power to power the vehicle communication system. Finally, during the switching process, a temporary power source is used to provide the power required by the vehicle communication system.

The switching circuit further includes a detection control unit and a switch unit connected in series between the voltage conversion circuit and the standby power source, and the detection control unit detects the first voltage value or the second voltage value, and is turned on by the detection control unit or Turn off this switch unit.

The power switching method further includes providing a charging circuit connected between the voltage conversion circuit and the standby power source to charge the standby power source.

According to the present invention, the power switching device and the method thereof have the following advantages: the power switching device and the method thereof can adopt a reasonable circuit structure, and can improve the switching speed between the main power source and the backup power source, and It has the problem of temperature drift caused by the temperature effect of the electronic component, thereby solving the problem of information loss in the restart or use of the system vehicle communication system caused by the power failure of the conventional power source switching device during the switching process.

1‧‧‧Power switching device

10‧‧‧Main power supply

2‧‧‧Car communication system

20‧‧‧Voltage conversion circuit

21‧‧‧Global Positioning Module

22‧‧‧Global Mobile Communications Module

23‧‧‧Common Packet Wireless Service Module

24‧‧‧Bluetooth Module

30‧‧‧Reserved power supply

40‧‧‧Switching circuit

41‧‧‧Detection Control Unit

410‧‧‧Voltage comparator

411‧‧‧Output interface circuit

42‧‧‧Switch unit

50‧‧‧ temporary power supply

60‧‧‧Charging circuit

70‧‧‧Protection circuit

Vref‧‧‧reference voltage

Vcc‧‧‧second voltage

R1‧‧‧first resistance

R2‧‧‧second resistance

R3‧‧‧ third resistor

R4‧‧‧fourth resistor

S1~S6‧‧‧Steps

1 is a schematic diagram of voltage switching of different power sources of a conventional power switching device; FIG. 2 is a block diagram of a first embodiment of a power switching device of the present invention; and FIG. 3 is a power switching device of the present invention; FIG. 4 is a block diagram of the internal structure of the detection control unit of the second embodiment of the present invention; and FIG. 5 is a voltage of the power switching process of the second embodiment of the present invention. FIG. 6 is a flow chart showing the steps of implementing the power switching method of the present invention.

Please refer to FIG. 2, which is a block diagram of a first embodiment of the power switching device of the present invention. In the figure, the power switching device 1 can be applied to the vehicle communication system 2, which can include a global positioning (GPS) module 21, a global mobile communication (GSM) module 22, and a universal packet wireless service (GPRS). Module 23 or Bluetooth (BT) module 24. The power switching device 1 includes a main power supply 10, a voltage conversion circuit 20, a backup power supply 30, a switching circuit 40, and a temporary power supply 50.

In a first implementation, the primary power source 10 can be an on-board battery to provide a first voltage having a voltage value typically between 9 and 32 volts (Volt).

The voltage conversion circuit 20 is connected to the main power source 10 to receive the first voltage and convert the first voltage into a second voltage to provide the second voltage to the vehicle communication system 2. The voltage conversion circuit provides an adjustable output voltage. The second voltage of this embodiment is regulated to 5.12 volts (V) and the output current can be 2.5 amps (A).

Moreover, the switching circuit 40 is connected to the voltage conversion circuit 20, the backup power source 30, and the vehicle communication system 2, and detects a first voltage value of the first voltage or a second voltage value of the second voltage, when the first voltage value or the second When the voltage value is less than the threshold value, the switching circuit 40 switches the power supply source from the main power source 10 to the backup power source 30 to supply power to the vehicle communication system 2.

Further, one end of the temporary power source 50 is connected between the voltage conversion circuit 20, the switching circuit 40, and the vehicle communication system 2. During the switching of the power source, the temporary power source 50 can be supplied with a temporary power input to the vehicle communication system 2. The temporary power source 50 is preferably a capacitor or a super capacitor having a large capacitance value, and the energy storage principle of the capacitor is used to satisfy the switching. Continuous power supply requirements in the process.

Please refer to FIG. 3, which is a block diagram of a second embodiment of the power switching device of the present invention. Compared with the first embodiment, the difference is that the power switching device 1 of the second embodiment further includes a charging circuit 60 connected between the voltage converting circuit 20 and the backup power source 30 to receive the power provided by the voltage converting circuit 20 to the backup power source. 30 charging.

In addition, the switching circuit 40 further includes a detection control unit 41 and a switch unit 42. The detection control unit 41 can detect the first voltage value or the second voltage value, and thereby whether the first voltage value or the second voltage value is less than a threshold value. The on or off state of the switch unit 42 is determined to allow the power provided by the main power source 10 or the backup power source 30 to supply power to the vehicle communication system 2. The switching unit 42 is preferably a metal oxide semiconductor field effect transistor (MOSFET).

The power switching device 1 further increases the protection circuit 70 between the voltage conversion circuit 20 and the temporary power source 50 to prevent the energy generated by the temporary power source 50 during the power supply from being reversed to the voltage conversion circuit 20. The protection unit is preferably a diode (diode), a metal oxide semiconductor field effect transistor (MOSFET) or a direct current to direct current conversion circuit (DCDC), depending on the actual overall architecture. The rest are the same and will not be repeated here.

When the protection circuit 70 is a diode and the detection point of the detection control unit is the second voltage, the threshold value can be divided into three parts. The first part is the maximum value of the minimum operating voltage required by each module such as GPS module 21, GSM module 22, GPRS module 23 and BT module 24, for example, the minimum operating voltage required for GSM module 22 is 3.3. volt. The second part is the voltage drop from the voltage conversion circuit 20 to the vehicular communication system 2. When the protection unit is a diode, the voltage drop across the diode is typically 0.7 volts. The third part is a self-set margin, where the margin is preferably 0.2 volts. Therefore, the threshold is 3.3 V+0.7 V+0.2 V=4.2 V.

Please refer to FIG. 4, which is a structural diagram of an internal circuit of a detection control unit according to a second embodiment of the present invention. In the figure, the detection control unit 41 includes a voltage comparator 410, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and an output interface circuit 411. The electronic components are connected as shown in the figure. I will not repeat them here. After the second voltage value Vcc is divided by the first resistor R1 and the second resistor R2, it is input to the negative input terminal of the voltage comparator 410, and is compared with the reference voltage Vref after being divided by the third resistor R3 and the fourth resistor R4. The reference voltage Vref is not divided, and the output signal is controlled by the output signal to control the output interface circuit 411, thereby determining the on or off state of the switching unit 42.

In this embodiment, the detection control unit 41 with a threshold voltage of 4.2 V is used to detect the second voltage value Vcc. When the voltage value of the second voltage Vcc is less than 4.2V, the switch unit 42 is turned on, and the vehicle communication system 2 is used. The power supply is switched from the main power source 10 to the backup power source 30; when the voltage of the main power source 10 is raised to 4.2V+VHYST (VHYST: Voltage Threshold Hysteresis), the switch unit 42 is turned off, and the power supply for the vehicle communication system 2 is reserved. The power source 30 is switched to the main power source 10.

Please refer to FIG. 5, which is a voltage diagram of a power switching process according to a second embodiment of the present invention. In the figure, the main power source 10 is continuously plugged and unplugged, and the backup power source 30 quickly supplies a voltage of 3.4 volts to the vehicle communication system 2, and overcomes the problem of excessive voltage drop gap in the switching process. The purpose of smooth switching.

Please refer to FIG. 6, which is a flow chart of the implementation steps of the power switching method of the present invention. In the figure, the power switching method includes the following steps: In step S1: the first voltage is supplied by using the main power source.

In step S2: the first voltage is converted to the second voltage by the voltage conversion circuit.

In step S3, the voltage value of the first voltage or the voltage value of the second voltage is detected by the switching circuit.

In step S4, it is determined whether the voltage value of the first voltage or the voltage value of the second voltage is less than the threshold value. If the threshold value is less than the threshold value, step S5 is performed, and if it is greater than the threshold value, the process returns to step S1.

At step S5: the switching circuit switches the main power to the standby power source.

At step S6: the temporary power source is used to provide the power required during the switching process.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

1‧‧‧Power switching device

10‧‧‧Main power supply

2‧‧‧Car communication system

20‧‧‧Voltage conversion circuit

21‧‧‧Global Positioning Module

22‧‧‧Global Mobile Communications Module

23‧‧‧Common Packet Wireless Service Module

24‧‧‧Bluetooth Module

30‧‧‧Reserved power supply

40‧‧‧Switching circuit

41‧‧‧Detection Control Unit

42‧‧‧Switch unit

50‧‧‧ temporary power supply

60‧‧‧Charging circuit

70‧‧‧Protection circuit

Claims (10)

A power switching device is applied to a vehicle communication system, the power switching device includes: a main power source, which provides a first voltage; a voltage conversion circuit is connected to the main power source to receive the first voltage, and Converting the first voltage into a second voltage to provide the second voltage to the vehicle communication system; a backup power source; a switching circuit connecting the voltage conversion circuit, the backup power source, and the vehicle communication system, And detecting a first voltage value of the first voltage or a second voltage value of the second voltage, when the first voltage value or the second voltage value is less than a threshold, the switching circuit switches the main a power supply to the backup power supply to supply power to the vehicle communication system; and a temporary power supply, one end of which is connected between the voltage conversion circuit, the switching circuit and the vehicle communication system to provide the vehicle communication during the switching process The power required by the system. The power switching device of claim 1, wherein the switching circuit further comprises a detecting control unit and a switching unit connected in series between the voltage converting circuit and the standby power source, wherein the detecting control unit detects The first voltage value or the second voltage value is turned on and off by the detection control unit. The power switching device of claim 2, wherein the switching unit is a metal oxide semiconductor field effect transistor. The power switching device of claim 1, further comprising a charging circuit connected between the voltage converting circuit and the standby power source to charge the standby power source. The power switching device of claim 1, further comprising a protection circuit connected between the voltage conversion circuit and the temporary power source to prevent power provided by the temporary power source from being output to the voltage conversion circuit. The power switching device according to claim 5, wherein the protection circuit is a diode, a metal oxide semiconductor field effect transistor or a DC-to-DC conversion unit. A power switching method is applied to a vehicle communication system, the power switching method includes the steps of: providing a first voltage by using a main power source; and converting the first voltage to a second voltage by using a voltage conversion circuit; a switching circuit detects a first voltage value of the first voltage or a second voltage value of the second voltage, and when the first voltage value or the second voltage value is less than a threshold, the switching circuit switches the The main power source is supplied to a backup power source to supply power to the vehicle communication system; and during the switching process, a temporary power source is used to supply the power required by the vehicle communication system. The power switching method of claim 7, wherein the switching circuit further comprises a detecting control unit and a switching unit connected in series between the voltage converting circuit and the standby power source, wherein the detecting control unit detects The first voltage value or the second voltage value is turned on and off by the detection control unit. The power switching method of claim 7, further comprising providing a charging circuit connected between the voltage converting circuit and the standby power source to charge the standby power source. The power switching method according to claim 7, further comprising providing a protection circuit connected between the voltage conversion circuit and the temporary power source to prevent the power provided by the temporary power source from being output to the voltage conversion circuit.