Voltage regulation circuit and method

Abstract

The present invention discloses a voltage regulation circuit and method, wherein the voltage regulation circuit includes a power tube and a driving control circuit thereof, wherein the power tube receives an input voltage and regulates the power tube through the driving control circuit to output an expected output voltage; the driving control circuit is connected to the control end of the power tube, wherein the input voltage is provided with a high potential end and a low potential end; one of the power ends of the power tube is connected to one of the high potential end and the low potential end of the input voltage, wherein the end connected to the power tube serves as the first end of the input voltage, and the other end serves as the second end of the input voltage, wherein the second end of the input voltage and the other power end of the power tube serve together as the output end; at least one impedance element is connected in series in a loop including the input voltage and the power tube, and when the temperature of the power tube reaches the upper temperature limit, the power tube works in a switching mode. In the present invention, the heat generated by the power tube is greatly reduced, which is beneficial to improving the lightning protection and surge protection functions of the circuit.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a voltage regulation circuit and method. Background Art

[0002] Linear voltage regulation circuit is a circuit implementation form to achieve input-output voltage conversion. When the input and output voltages are high voltage, such as hundreds of volts or even several hundred volts, the two ends of the power tube will also be subjected to the corresponding high voltage. In the case of continuous high voltage use, the power tube will heat up. Excessive temperature will affect the normal operation of the voltage regulation circuit, trigger over-temperature protection, and even damage the power tube.

[0003] The existing technology uses Figure 1 The voltage regulation circuit shown receives the input voltage Vin, and adjusts the voltage borne by the power tube M20, thereby outputting the expected output voltage Vout at the output end. Taking the input voltage Vin as 500V and the expected output voltage as 400V as an example, the power tube M20 needs to withstand a voltage of 100V and work in the linear region. However, bearing such a high voltage for a long time can easily cause the temperature of the power tube M20 to be too high, thereby affecting the normal operation of the circuit. In addition, the prior art lacks a low-power lightning protection function, and if it is applicable in the power industry, there are safety hazards. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a voltage regulating circuit for reducing the heat generation of a power tube, so as to solve the technical problem of high heat generation of the power tube in the prior art.

[0005] The technical solution of the present invention is to provide a voltage regulating circuit with the following structure, the voltage regulating circuit includes a power tube and a driving control circuit thereof, the power tube receives an input voltage, and the driving control circuit regulates the power tube to output an expected output voltage;

[0006] The power tube is provided with a first power terminal, a second power terminal and a control terminal, the drive control circuit is connected to the control terminal of the power tube, and the input voltage is provided with a high potential terminal and a low potential terminal;

[0007] One of the power terminals of the power tube is connected to one of the high potential terminal and the low potential terminal of the input voltage, the terminal connected to the power tube serves as the first terminal of the input voltage, and the other terminal serves as the second terminal of the input voltage, the second terminal of the input voltage and the other power terminal of the power tube serve as the output terminal, and the voltage between the two serves as the output voltage;

[0008] At least one impedance element is connected in series in a loop including an input voltage and a power tube. When the temperature of the power tube reaches a first temperature trigger threshold, the power tube operates in a switch mode.

[0009] Optionally, in the switching mode, after the power tube is turned on, when the output voltage reaches a first threshold, the power tube is turned off, and when the output voltage drops to a second threshold, the power tube is turned on again, and when the temperature of the power tube is lower than a second temperature trigger threshold, the switching mode is exited; the first threshold is greater than the second threshold, and the first temperature trigger threshold is greater than the second temperature trigger threshold.

[0010] Optionally, in non-switching mode, the voltage across the power tube is the difference between the input voltage and the expected output voltage.

[0011] Optionally, when the power tube is turned on, in the loop formed between the power tube and the input voltage, the heat generated by the current flowing through the impedance element is greater than the heat generated by the power tube, and when the power tube is turned off, neither the power tube nor the impedance element generates heat.

[0012] Optionally, the output end is connected to a switching power supply, and the switching power supply performs voltage conversion on the output voltage, and then outputs a supply voltage, and supplies power to a load through the supply voltage.

[0013] Optionally, the switching power supply is a flyback converter, the output end of the voltage regulating circuit is connected to the primary input end of the flyback converter, the primary part of the flyback converter includes a primary inductor and a primary switch tube, the primary inductor and the primary switch tube are connected, and their common end is connected to the control end of the power tube via a unidirectional conductive element and a first resistor.

[0014] Optionally, the impedance element is a resistor or a switch tube, and the resistance of the impedance element connected to the loop is between 20 ohms and 100 ohms.

[0015] Another technical solution provided by the present invention is to provide a voltage regulation method, based on the above voltage regulation circuit, comprising the following steps:

[0016] 1) The input voltage supplies power to the power tube, the power tube operates in the linear region, and the power tube is adjusted by the driving control circuit to output the expected output voltage at the output end;

[0017] 2) When the temperature of the power tube reaches a first temperature trigger threshold, the power tube operates in a switching mode. In the switching mode, after the power tube is turned on, when the output voltage reaches a first threshold, the power tube is turned off. When the output voltage drops to a second threshold, the power tube is turned on again. When the temperature of the power tube is lower than the second temperature trigger threshold, the switching mode is exited; the first threshold is greater than the second threshold.

[0018] Optionally, a switching power supply is connected to the output end of the voltage regulating circuit, and the switching power supply performs voltage conversion on the output voltage to output a supply voltage, and the load is powered by the supply voltage.

[0019] Optionally, the switching power supply is a flyback converter. When the output voltage powers the flyback converter, the output end of the output voltage is connected to the primary input end of the flyback converter. The primary part of the flyback converter includes a primary inductor and a primary switch tube. The primary inductor and the primary switch tube are connected, and their common end is connected to the control end of the power tube via a unidirectional conduction element. The voltage at the common end of the primary inductor and the primary switch tube is higher than the output voltage. When the input voltage is low, the voltage is transmitted to the control end of the power tube via the unidirectional conduction element to turn on the power tube and power the drive control circuit.

[0020] The circuit structure and method of the present invention have the following advantages compared with the prior art: in the present invention, an impedance element is connected in the main circuit. When the temperature of the power tube is too high, the power tube enters the switching mode, and the input voltage is mainly applied to the impedance element. The heat generated during the conduction period of the power tube is greatly reduced, so that the power tube returns to normal temperature; since the impedance element is connected, it is beneficial to improve the lightning protection and surge protection function of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a circuit structure diagram of a linear voltage stabilizing circuit in the prior art;

[0022] Figure 2 is a circuit structure diagram of a voltage regulating circuit of the present invention;

[0023] Figure 3 It is a schematic diagram of the working waveform of the present invention;

[0024] Figure 4 Schematic diagram of the mode control structure. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitution, modification, equivalent method and scheme made within the spirit and scope of the present invention.

[0026] In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without these detailed descriptions.

[0027] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the accompanying drawings are all simplified and not in exact proportion, and are only used for the purpose of conveniently and clearly assisting in explaining the embodiments of the present invention.

[0028] like Figure 2 The circuit structure of the voltage regulating circuit of the present invention is shown in FIG. The voltage regulating circuit includes a power tube M1 and a driving control circuit thereof. The power tube M1 receives an input voltage Vin and is regulated by the driving control circuit to output a desired output voltage.

[0029] In this embodiment, the power tube M1 is provided with a first power end (drain D), a second power end (source S) and a control end (gate G), the drive control circuit is provided with a first end, a second end and a third end, the control end of the power tube is connected to the first end of the drive control circuit, and the second end of the drive control circuit is connected to the second power end of the power tube M1; the first power end of the power tube M1 is connected to the high potential end of the input voltage Vin, and a first resistor R1 is connected between the first power end of the power tube and the control end of the power tube; the third end of the drive control circuit is connected to a second resistor R2;

[0030] The voltage between the low potential end of the input voltage Vin and the second power end of the power tube M1 is used as the output voltage Vout.

[0031] Similarly, the power tube M1 can also be connected to the low potential end of the input voltage Vin, and one end of the power tube M1 and the low potential end of the input voltage Vin serve as the output end. Therefore, in summary, one of the power ends of the power tube M1 is connected to one of the high potential end and the low potential end of the input voltage, the end connected to the power tube serves as the first end of the input voltage, and the other end serves as the second end of the input voltage, the second end of the input voltage and the other power end of the power tube serve together as the output end, and the voltage between the two serves as the output voltage.

[0032] On the basis of the above structure, at least one impedance element is connected in series in the loop including the input voltage Vin and the power tube M1, and when the temperature of the power tube reaches the first temperature trigger threshold T1, the power tube M1 works in the switch mode. In this embodiment, the impedance element is the third resistor R3. The impedance element can also be a resistor series or parallel structure, or a MOS tube, which "transfers" the heat of the power tube M1 to the MOS tube. In this case, the MOS tube works in the saturation region.

[0033] After the input voltage Vin is powered on, the first resistor R1 pulls up the voltage of the control end of the power tube M1 to turn on the power tube, and the second power end of the power tube M1 generates an output voltage and supplies power to the drive control circuit.

[0034] The driving control circuit is integrated in the chip, and the second resistor R2 is an external resistor. The first resistor R1 is connected in parallel with a first capacitor C11; the first capacitor C11 can also achieve lightning protection through capacitor voltage division.

[0035] In the switching mode, after the power tube M1 is turned on, when the output voltage Vout reaches the first threshold value Vth1, the power tube M1 is turned off, and when the output voltage drops to the second threshold value Vth2, the power tube M1 is turned on again, and when the temperature of the power tube M1 is lower than the second temperature trigger threshold value T2, the switching mode is exited; the first threshold value Vth1 is greater than the second threshold value Vth2, and the first temperature trigger threshold value T1 is greater than the second temperature trigger threshold value T2.

[0036] In the non-switching mode, the voltage across the power tube M1 is the difference between the input voltage Vin and the expected output voltage. Although the resistance in the loop will produce a voltage drop, the voltage drop is relatively large compared to the input voltage Vin, so in theory, the voltage across the power tube M1 is the difference between the input voltage Vin and the expected output voltage, and it is not required to be exactly equal.

[0037] During the conduction period of the power tube M1, in the loop formed between the power tube M1 and the input voltage Vin, the heat generated by the current flowing through the impedance element (R3 in this embodiment) is greater than the heat generated by the power tube Vin. During the shutdown period of the power tube Vin, neither the power tube Vin nor the impedance element generates heat. The heat generated during the conduction period of the power tube is greatly reduced, so that the power tube returns to normal temperature.

[0038] The output end is connected to a switching power supply, and the switching power supply performs voltage conversion on the output voltage to output a power supply voltage, and supplies power to the load through the power supply voltage.

[0039] The switching power supply is a flyback converter, the output end of the voltage regulating circuit is connected to the primary input end of the flyback converter, the primary part of the flyback converter includes a primary inductor L1 and a primary switch tube M2, the primary inductor L1 and the primary switch tube M2 are connected, and the common end of the two is connected to the control end of the power tube M1 through a unidirectional conduction element and a third resistor R3. With this design, when the input voltage Vin is low, the voltage of the control end of M1 can be raised, and the power tube M1 can be kept turned on, and its second power end can provide stable power to the drive control circuit. The unidirectional conduction element includes a diode D3. Due to the presence of the diode D3, the voltage at point H is higher than the voltage at the control end G of the power tube, and the diode D1 mainly prevents reverse conduction. The diode D3 can also be used as a part of the unidirectional conduction element.

[0040] like Figure 3 As shown, the waveform of the output voltage Vo is illustrated, and the relationship between the output voltage Vo and the first threshold value Vth1 and the second threshold value Vth2 is illustrated. In this embodiment, the first threshold value Vth1 is greater than the second threshold value Vth2. In the switching mode, the average output voltage in one cycle is close to the output voltage in the non-switching mode, and the two are not required to be completely equal. In addition, the output voltage in the non-switching mode can be equal to the first threshold value Vth1 or the second threshold value Vth2.

[0041] like Figure 4 As shown, the mode control structure is illustrated. The mode control structure is located in the drive control circuit, and the drive control circuit is packaged together with the power tube M1. Therefore, detecting the temperature of the package body can characterize the temperature of the power tube M1. The mode control structure includes a temperature detection module and a comparison circuit, and the comparison circuit is a hysteresis comparator Comp1. The temperature detection module detects the temperature in the package body, obtains a temperature value of Ts, and characterizes it with a voltage VTs. The upper threshold and lower threshold of the hysteresis comparator Comp1 are set by parameters, so that its upper threshold is voltage VT1, and the lower threshold is voltage VT2. Voltage VT1 characterizes the first temperature trigger threshold, and voltage VT2 characterizes the second temperature trigger threshold. There is a hysteresis between VT1 and VT2, and the state of the hysteresis comparator Comp1 remains unchanged. The output end of the hysteresis comparator Comp1 is connected to the control end G of the power tube.

[0042] The present invention provides a voltage regulation method, based on the above voltage regulation circuit, comprising the following steps:

[0043] 1) The input voltage supplies power to the power tube, the power tube operates in the linear region, and the power tube is adjusted by the driving control circuit to output the expected output voltage at the output end;

[0044] 2) When the temperature of the power tube reaches a first temperature trigger threshold, the power tube operates in a switching mode. In the switching mode, after the power tube is turned on, when the output voltage reaches a first threshold, the power tube is turned off. When the output voltage drops to a second threshold, the power tube is turned on again. When the temperature of the power tube is lower than the second temperature trigger threshold, the switching mode is exited; the first threshold is greater than the second threshold.

[0045] The second resistor is an external resistor, and the value of the output voltage can be set by setting the resistance value of the second resistor.

[0046] When the output voltage supplies power to the flyback converter, the output end of the output voltage is connected to the primary input end of the flyback converter. The primary part of the flyback converter includes a primary inductor and a primary switch tube. The primary inductor and the primary switch tube are connected, and the common end of the two is connected to the control end of the power tube via a unidirectional conduction element. The voltage of the common end of the primary inductor and the primary switch tube is higher than the output voltage. When the input voltage is low, the voltage is transmitted to the control end of the power tube via the unidirectional conduction element to turn on the power tube and supply power to the drive control circuit.

[0047] In the voltage regulation method of the present invention, the technical features that are the same as those of the voltage regulation circuit can refer to the description of the voltage regulation circuit, and some features of the two can be replaced and referenced with each other.

[0048] The above-described implementation methods do not constitute a limitation on the protection scope of the technical solution. Any modification, equivalent replacement and improvement made within the spirit and principle of the above-described implementation methods shall be included in the protection scope of the technical solution.

Claims

1. A voltage regulating circuit, comprising a power tube and a driving control circuit thereof, wherein the power tube receives an input voltage and is regulated by the driving control circuit to output an expected output voltage; characterized in that: The power tube is provided with a first power terminal, a second power terminal and a control terminal, the drive control circuit is connected to the control terminal of the power tube, and the input voltage is provided with a high potential terminal and a low potential terminal; One of the power terminals of the power tube is connected to one of the high potential terminal and the low potential terminal of the input voltage, the terminal connected to the power tube serves as the first terminal of the input voltage, and the other terminal serves as the second terminal of the input voltage, the second terminal of the input voltage and the other power terminal of the power tube serve as the output terminal, and the voltage between the two serves as the output voltage; At least one impedance element is connected in series in a loop including an input voltage and a power tube, and when the temperature of the power tube reaches a first temperature trigger threshold, the power tube operates in a switch mode; Among them, in the switching mode, after the power tube is turned on, when the output voltage reaches a first threshold, the power tube is turned off, and when the output voltage drops to a second threshold, the power tube is turned on again, and when the temperature of the power tube is lower than a second temperature trigger threshold, the switching mode is exited; the first threshold is greater than the second threshold, and the first temperature trigger threshold is greater than the second temperature trigger threshold.

2. The voltage regulating circuit according to claim 1, characterized in that: In the non-switching mode, the voltage across the power tube is the difference between the input voltage and the expected output voltage.

3. The voltage regulating circuit according to claim 1, characterized in that: When the power tube is turned on, in the loop formed between the power tube and the input voltage, the heat generated by the current flowing through the impedance element is greater than the heat generated by the power tube. When the power tube is turned off, neither the power tube nor the impedance element generates heat.

4. The voltage regulating circuit according to claim 1, characterized in that: The output end is connected to a switching power supply, and the switching power supply performs voltage conversion on the output voltage to output a power supply voltage, and supplies power to the load through the power supply voltage.

5. The voltage regulating circuit according to claim 4, characterized in that: The switching power supply is a flyback converter, the output end of the voltage regulating circuit is connected to the primary input end of the flyback converter, the primary part of the flyback converter includes a primary inductor and a primary switch tube, the primary inductor and the primary switch tube are connected, and the common end of the two is connected to the control end of the power tube via a unidirectional conductive element and a first resistor.

6. The voltage regulating circuit according to claim 5, characterized in that: The impedance element is a resistor or a switch tube, and the resistance of the impedance element connected to the loop is between 20 ohms and 100 ohms.

7. A voltage regulation method based on the voltage regulation circuit according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) The input voltage supplies power to the power tube, the power tube operates in the linear region, and the power tube is adjusted by the driving control circuit to output the expected output voltage at the output end; 2) When the temperature of the power tube reaches a first temperature trigger threshold, the power tube operates in a switching mode. In the switching mode, after the power tube is turned on, when the output voltage reaches a first threshold, the power tube is turned off. When the output voltage drops to a second threshold, the power tube is turned on again. When the temperature of the power tube is lower than the second temperature trigger threshold, the switching mode is exited; the first threshold is greater than the second threshold.

8. The voltage regulation method according to claim 7, characterized in that: A switching power supply is connected to the output end of the voltage regulating circuit. After the switching power supply performs voltage conversion on the output voltage, the switching power supply outputs a power supply voltage, and the load is powered by the power supply voltage.

9. The voltage regulation method according to claim 8, characterized in that: The switching power supply is a flyback converter. When the output voltage supplies power to the flyback converter, the output end of the output voltage is connected to the primary input end of the flyback converter. The primary part of the flyback converter includes a primary inductor and a primary switch tube. The primary inductor and the primary switch tube are connected, and the common end of the two is connected to the control end of the power tube via a unidirectional conductive element. The voltage of the common end of the primary inductor and the primary switch tube is higher than the output voltage. When the input voltage is less than a preset value, the voltage is transmitted to the control end of the power tube via the unidirectional conductive element to turn on the power tube and supply power to the drive control circuit.

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