Driving voltage adjusting circuit and power supplying system

Abstract

A driving voltage adjusting circuit and a power supplying system are proposed. The driving voltage adjusting circuit includes a detecting unit, a voltage dividing unit and an adjusting unit. The detecting unit is disposed and surrounds a switching element of a voltage converter, and is configured to detect a temperature of the switching element. The voltage dividing unit is electrically connected to the detecting unit and the voltage converter, and receives a driving voltage. The voltage dividing unit divides the driving voltage to generate a dividing voltage according to the temperature of the switching element. The adjusting unit is electrically connected to the voltage dividing unit, and receives an input voltage and the dividing voltage. The adjusting unit adjusts the input voltage to output the driving voltage according to the dividing voltage, and the driving voltage is transmitted to the voltage converter. The temperate is positive relative to the driving voltage. Thus, the driving voltage adjusting circuit of the present disclosure can adjust the driving voltage according to the temperature of the voltage converter to reduce the power consumption.

Description

[Technical Field]

[0001] This invention relates to a driving voltage adjustment circuit and a power supply system, and more particularly to a driving voltage adjustment circuit and a power supply system for a voltage converter. [Previous Technology]

[0002] In existing DC-DC voltage converters, the main power loss during light load conditions is due to the switching of the converter's switching elements, while during heavy load conditions, the main power loss is due to the conduction losses of the switching elements. Since the internal resistance of the switching elements varies with the drive voltage, the power loss of the voltage converter can be effectively reduced by appropriately adjusting the drive voltage of the switching elements.

[0003] Furthermore, since the impedance of the switching elements of a voltage converter changes with temperature, the power loss of the voltage converter is also positively correlated with temperature. In view of this, developing a drive voltage regulation circuit and power supply system that can adjust the drive voltage according to the temperature of the switching elements has become a worthwhile research goal for related companies. [Summary of the Invention]

[0004] Therefore, the object of the present invention is to provide a drive voltage adjustment circuit and power supply system, which adjusts the drive voltage of the voltage converter by sensing the temperature of the switching element of the voltage converter through a sensing unit. In this way, the drive voltage adjustment circuit and power supply system of the present invention can adjust the drive voltage according to the temperature of the voltage converter, thereby reducing power loss.

[0005] According to one embodiment of the structural configuration of the present invention, a drive voltage adjustment circuit is provided, comprising a sensing unit, a voltage divider unit, and an adjustment unit. The sensing unit is disposed around a switching element of a voltage converter and is used to sense a temperature of the switching element of the voltage converter. The voltage divider unit is electrically connected to the sensing unit and the voltage converter, and receives a drive voltage. The voltage divider unit divides the drive voltage according to the temperature of the switching element to generate a divided voltage. The adjustment unit is electrically connected to the voltage divider unit and receives an input voltage and the divided voltage. The adjustment unit adjusts the input voltage according to the divided voltage and outputs a drive voltage, which is transmitted to the voltage converter. Temperature is positively correlated with drive voltage.

[0006] According to another embodiment of the structural configuration of the present invention, a power supply system is provided, comprising a voltage converter and a drive voltage adjustment circuit. The voltage converter is driven by a drive voltage and includes a group of switching elements. The group of switching elements includes two switching elements. The drive voltage adjustment circuit includes a sensing unit, a voltage divider unit, and an adjustment unit. The sensing unit is disposed around one of the two switching elements and is used to sense a temperature of the other switching element. The voltage divider unit is electrically connected to the sensing unit and the voltage converter and receives the drive voltage. The voltage divider unit divides the drive voltage according to the temperature of the other switching element to generate a divided voltage. The adjustment unit is electrically connected to the voltage divider unit and receives an input voltage and the divided voltage. The adjustment unit adjusts the input voltage according to the divided voltage to output a drive voltage, which is transmitted to the voltage converter. Temperature is positively correlated with the drive voltage.

Implementation Method

[0007] Please refer to Figures 1 and 2. Figure 1 is a block diagram illustrating a drive voltage adjustment circuit 100 according to a first embodiment of the present invention, and Figure 2 is a circuit diagram illustrating a voltage converter 10 connected to the drive voltage adjustment circuit 100 according to Figure 1. The drive voltage adjustment circuit 100 includes a sensing unit 120, a voltage divider unit 130, and an adjustment unit 140. The sensing unit 120 is disposed around a switching element (i.e., one of the switching elements Ta and Tb in Figure 2) of the voltage converter 10, and is used to sense a temperature of the switching elements Ta and Tb of the voltage converter 10. The voltage divider unit 130 is electrically connected to the sensing unit 120 and the voltage converter 10, and receives a drive voltage Vdr. The voltage divider unit 130 divides the drive voltage Vdr according to the temperature of the switching elements Ta and Tb to generate a divided voltage Vdi. The adjustment unit 140 is electrically connected to the voltage divider unit 130, and receives an input voltage Vi and the divided voltage Vdi. The adjustment unit 140 adjusts the input voltage Vi according to the voltage divider voltage Vdi and outputs a drive voltage Vdr, which is then transmitted to the voltage converter 10. Temperature is positively correlated with the drive voltage Vdr.

[0008] Specifically, the sensing unit 120 may be a thermistor with a negative temperature coefficient, the voltage divider unit 130 may be a voltage divider circuit composed of resistors connected in series, and the adjustment unit 140 may be a DC-DC converter or a low dropout regularizer (LDO), but the present invention is not limited thereto.

[0009] In Figure 2, the voltage converter 10 can be a DC-DC converter, which includes a pulse generation circuit 11, two switching elements Ta and Tb, a capacitor C, an inductor L, and a load RL. The pulse generation circuit 11 is used to input a pulse to the switching elements Ta and Tb. The switching elements Ta and Tb are driven by the driving voltage Vdr and switch on alternately according to the voltage level of the pulse. The switching elements Ta and Tb can be metal-oxide-semiconductor field-effect transistors (MOSFETs), whose internal resistance decreases as the gate driving voltage Vdr increases, and the voltage Vout is the output voltage of the voltage converter 10.

[0010] Please refer to Figures 2 and 3. Figure 3 is a voltage diagram of the voltage converter 10 connected according to the drive voltage adjustment circuit 100 in Figure 2. It shows the ground voltage GND, the voltage VLX at terminal LX, the voltage range of terminal BST, and the voltage Vin in the voltage converter 10 of Figure 2. Terminal BST is connected to the drain of switching element Ta, and terminal LX is connected to the source of switching element Ta and the drain of switching element Tb. The voltage VLX at terminal LX is the same as the voltage Vin, while the voltage at terminal BST is the voltage Vin plus the drive voltage Vdr. When the drive voltage Vdr changes with temperature, the voltage at terminal BST is between the maximum value VBST(max) and the minimum value VBST(min), and the voltage difference between the voltage at terminal BST and the voltage VLX is also variable.

[0011] Furthermore, during the operation of the voltage converter 10, the switching elements Ta and Tb alternately conduct and generate heat loss. When the temperature of the switching elements Ta and Tb in the voltage converter 10 rises, the sensing unit 120 senses the temperature of one of the switching elements Ta and Tb, and divides the driving voltage Vdr according to its temperature through the voltage divider unit 130, and adjusts the driving voltage Vdr to the adjusted driving voltage Vdr according to the aforementioned temperature through the adjustment unit 140. In this way, the driving voltage adjustment circuit 100 of the present invention dynamically adjusts the driving voltage Vdr according to the temperature of the switching elements Ta and Tb in the voltage converter 10, which can prevent the power loss of the voltage converter 10 from increasing with temperature.

[0012] Please refer to Figures 1 and 4, where Figure 4 is a schematic diagram illustrating the drive voltage adjustment circuit 100a of the second embodiment of the present invention. The drive voltage adjustment circuit 100a includes a sensing unit 120, a voltage divider unit 130, and an adjustment unit 140a. In the second embodiment, the sensing unit 120 and the voltage divider unit 130 operate in the same way as the sensing unit 120 and the voltage divider unit 130 of the drive voltage adjustment circuit 100 of the first embodiment, and will not be described again. In particular, the adjustment unit 140a is a DC-DC converter, which may include a power amplifier 141, a pulse width modulation controller 142, and a group of switching elements. The power amplifier 141 is electrically connected to the voltage divider unit 130 and generates a comparison signal Sco based on the divided voltage Vdi. The pulse width modulation controller 142 is electrically connected to the power amplifier 141 and generates a pulse signal based on the comparison signal Sco. The switching element group is electrically connected to the pulse width modulation controller 142 and adjusts the input voltage Vi according to the pulse signal to output the drive voltage Vdr. The switching element group may include switching elements T1 and T2. Furthermore, the adjustment unit 140a may further include a filter unit (not shown in the figure), which is electrically connected between the switching element group and the voltage converter (not shown in the figure) to reduce noise in the drive voltage Vdr. The voltage converter may have the same structure as the voltage converter 10 in Figure 2, and the filter unit includes an inductor L and a capacitor C.

[0013] In detail, the sensing unit 120 is a thermistor, and the voltage divider unit 130 may include two resistors RD1 and RD2, wherein the two resistors RD1 and RD2 are connected in series and connected in parallel with the sensing unit 120. When the sensing unit 120 senses that the temperature of the switching elements Ta and Tb rises, the resistance value of the sensing unit 120 decreases, causing the voltage divider voltage Vdi to decrease accordingly. The power amplifier 141 compares the voltage divider voltage Vdi with the reference voltage Vref to generate a comparison signal Sco. The pulse width modulation controller 142 adjusts the switching frequency of the generated pulse according to the comparison signal Sco, thereby increasing the drive voltage Vdr, and inputting the adjusted drive voltage Vdr to the voltage converter.

[0014] For example, when resistor RD1 is 12KΩ (ohms) and resistor RD2 is 1.8KΩ, the required drive voltage Vdr for the voltage converter is shown in Table 1. As shown in Table 1, when the temperature around the sensing unit 120 rises, the resistance value of the sensing unit 120 decreases, and the drive voltage Vdr generated by the adjustment unit 140a rises accordingly. Therefore, the drive voltage adjustment circuit 100a of the present invention senses the temperature of the highest-temperature switching elements Ta and Tb in the voltage converter through the sensing unit 120, and feeds back the temperature to the adjustment unit 140a through the voltage divider unit 130, thereby increasing the drive voltage Vdr through the adjustment unit 140a, driving the voltage converter with a higher voltage, and improving the conversion efficiency of the voltage converter. Table 1 temperature The resistance value of sensing unit 120 The equivalent resistance value of resistor RD2 and sensing unit 120 Drive voltage Vdr 0°C 357KΩ 1.771KΩ 6.220V 5°C 273KΩ 1.768KΩ 6.228V 10°C 210KΩ 1.765KΩ 6.239V 15°C 163KΩ 1.761KΩ 6.252V 20°C 127KΩ 1.755KΩ 6.269V 25°C 100KΩ 1.749KΩ 6.289V 30°C 79.22KΩ 1.741KΩ 6.314V 35°C 63.17KΩ 1.731KΩ 6.345V 40°C 50.68KΩ 1.720KΩ 6.383V 45°C 40.90KΩ 1.706KΩ 6.428V 50°C 33.20KΩ 1.689KΩ 6.482V 55°C 27.09KΩ 1.670KΩ 6.548V 60°C 22.22KΩ 1.648KΩ 6.625V 65°C 18.32KΩ 1.622KΩ 6.717V

[0015] Please refer to Figures 1 and 5, where Figure 5 is a schematic diagram illustrating the drive voltage adjustment circuit 100b of the third embodiment of the present invention. The drive voltage adjustment circuit 100b includes a sensing unit 120, a voltage divider unit 130, and an adjustment unit 140b. In the third embodiment, the sensing unit 120 and the voltage divider unit 130 operate in the same way as the sensing unit 120 and the voltage divider unit 130 of the drive voltage adjustment circuit 100 of the first embodiment, and will not be described again. In particular, the adjustment unit 140b may be a linear regulator, which may include a power amplifier 141 and a switching element T1. The power amplifier 141 is electrically connected to the voltage divider unit 130 and generates a comparison signal Sco based on the divided voltage Vdi. The switching element T1 is electrically connected to the power amplifier 141 and adjusts the input voltage Vi according to the comparison signal Sco to output a drive voltage Vdr.

[0016] Furthermore, the power amplifier 141 compares the divided voltage Vdi and the reference voltage Vref to generate a comparison signal Sco, and adjusts the input voltage Vi to the drive voltage Vdr according to the comparison signal Sco. In this way, the drive voltage adjustment circuit 100b of the present invention dynamically adjusts the drive voltage Vdr according to the temperature of the voltage converter (not shown), saving the cost of heat dissipation components in the voltage converter.

[0017] Please refer to Figures 6 and 7. Figure 6 is a schematic diagram of a power supply system 200 according to a fourth embodiment of the present invention, and Figure 7 is a circuit diagram of the power supply system 200 according to Figure 6. The power supply system 200 includes a voltage converter 20 and a drive voltage adjustment circuit (not labeled). The voltage converter 20 is driven by a drive voltage Vdr and includes a group of switching elements. The group of switching elements includes two switching elements Ta and Tb. The drive voltage adjustment circuit includes a sensing unit 220, a voltage divider unit 230, and an adjustment unit 240. The sensing unit 220 is disposed around one of the two switching elements Ta and Tb and is used to sense the temperature of the switching element. In Figure 7, the sensing unit 220 is disposed around the switching element Tb as an example and is used to sense the temperature of the switching element Tb. In the fourth embodiment, the voltage divider unit 230 and the adjustment unit 240 operate in the same way as the voltage divider unit 130 and the adjustment unit 140 in the first embodiment, and the voltage converter 20 has the same structure as the voltage converter 10 in Figure 2, which will not be described again. Therefore, the power supply system 200 of the present invention can dynamically adjust the drive voltage Vdr according to the temperature of the voltage converter 20, reducing the power loss generated during the switching of switching elements Ta and Tb, and improving the overall efficiency of the power supply system 200.

[0018] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims. [Simplified Explanation of the Diagram]

[0019] Figure 1 is a block diagram illustrating a drive voltage adjustment circuit according to a first embodiment of the present invention; Figure 2 is a circuit diagram illustrating a voltage converter connected according to the drive voltage adjustment circuit of Figure 1; Figure 3 is a voltage diagram illustrating a voltage converter connected according to the drive voltage adjustment circuit of Figure 2; Figure 4 is a schematic diagram illustrating a drive voltage adjustment circuit according to a second embodiment of the present invention; Figure 5 is a schematic diagram illustrating a drive voltage adjustment circuit according to a third embodiment of the present invention; Figure 6 is a schematic diagram illustrating a power supply system according to a fourth embodiment of the present invention; and Figure 7 is a circuit diagram illustrating a power supply system according to Figure 6.

Claims

1. A drive voltage adjustment circuit, comprising: a sensing unit disposed around a switching element of a voltage converter and used to sense a temperature of the switching element of the voltage converter; a voltage divider unit electrically connected to the sensing unit and the voltage converter, and receiving a drive voltage, the voltage divider unit dividing the drive voltage according to the temperature of the switching element to generate a divided voltage; and an adjustment unit electrically connected to the voltage divider unit, and receiving an input voltage and the divided voltage, the adjustment unit adjusting the input voltage according to the divided voltage to output the drive voltage, the drive voltage being transmitted to the voltage converter; wherein... The temperature is positively correlated with the driving voltage.

2. The drive voltage adjustment circuit as described in claim 1, wherein the adjustment unit is a DC-DC converter or a linear regulator.

3. The drive voltage adjustment circuit as claimed in claim 1, wherein the adjustment unit comprises: a power amplifier electrically connected to the voltage divider unit and generating a comparison signal based on the divided voltage; a pulse width modulation controller electrically connected to the power amplifier and generating a pulse signal based on the comparison signal; and a group of switching elements electrically connected to the pulse width modulation controller and adjusting the input voltage based on the pulse signal to output the drive voltage.

4. The drive voltage adjustment circuit as claimed in claim 3, wherein the adjustment unit further comprises: a filter unit electrically connected between the switching element group and the voltage converter.

5. The drive voltage adjustment circuit as claimed in claim 1, wherein the adjustment unit comprises: a power amplifier electrically connected to the voltage divider unit and generating a comparison signal based on the divided voltage; and another switching element electrically connected to the power amplifier and adjusting the input voltage based on the comparison signal to output the drive voltage.

6. A power supply system comprising: a voltage converter driven by a drive voltage, and comprising: a group of switching elements including two switching elements; and a drive voltage adjustment circuit comprising: a sensing unit disposed around one of the two switching elements and used to sense a temperature of the other of the two switching elements; a voltage divider unit electrically connected to the sensing unit and the voltage converter, and receiving the drive voltage, the voltage divider unit dividing the drive voltage according to the temperature of the other of the two switching elements to generate a divided voltage; and an adjustment unit electrically connected to the voltage divider unit, and receiving an input voltage and the divided voltage, the adjustment unit adjusting the input voltage according to the divided voltage to output the drive voltage, the drive voltage being transmitted to the voltage converter; wherein... The temperature is positively correlated with the driving voltage.

7. The power supply system as described in claim 6, wherein the regulating unit is a DC-DC converter or a linear regulator.

8. The power supply system as claimed in claim 6, wherein the adjustment unit comprises: a power amplifier electrically connected to the voltage divider unit and generating a comparison signal based on the divided voltage; a pulse width modulation controller electrically connected to the power amplifier and generating a pulse signal based on the comparison signal; and another group of switching elements electrically connected to the pulse width modulation controller and adjusting the input voltage based on the pulse signal to output the drive voltage.

9. The power supply system as claimed in claim 8, wherein the adjustment unit further comprises: a filter unit electrically connected between the other switching element group and the voltage converter.

10. The power supply system as claimed in claim 6, wherein the adjustment unit comprises: a power amplifier electrically connected to the voltage divider unit and generating a comparison signal based on the voltage divider voltage; and another switching element electrically connected to the power amplifier and adjusting the input voltage based on the comparison signal to output the drive voltage.

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