Switching power supply high-temperature overcurrent protection circuit under extreme high-temperature environment

Abstract

The application discloses a switch power supply high-temperature overcurrent protection circuit in an extreme high-temperature environment, which comprises a current sampling circuit unit, a rectification filter circuit unit, an overcurrent protection setting circuit unit and a high-temperature PWM control chip. The application solves the technical problem of lacking of adaptive protection circuit in a high-temperature environment (185 DEG C), and breaks through the limitation of the junction temperature of 175 DEG C of a conventional semiconductor device. The protection circuit has the characteristics of wide applicable temperature range, accurate protection point setting, good system response performance and the like, and can be widely applied to various high-temperature switch power supplies, and provides stable and efficient overcurrent protection for power supply equipment in an extreme high-temperature scene.

Description

Technical Field

[0001] This invention relates to the field of high-temperature switching power supply circuit technology, specifically to a high-temperature overcurrent protection circuit for switching power supplies under extreme high-temperature environments. Background Technology

[0002] Currently, conventional thick-film hybrid integrated DC / DC converters are widely used in aerospace, aviation, weaponry, and shipbuilding industries due to their high reliability, long lifespan, and strong resistance to environmental stress. With continuous advancements in science and technology, the requirements for DC / DC converters in complete systems are becoming increasingly stringent, and their development is gradually focusing on higher frequencies, miniaturization, and higher power density. However, at the same time, the market demand for DC / DC converters with the ability to withstand extreme environments such as radiation resistance, extreme high temperatures, and extreme low temperatures is also growing stronger.

[0003] Extremely high-temperature environments exist in scenarios such as deep space exploration, deep well exploration, aircraft engine control systems, and internal combustion engine vehicle control systems. For example, the highest temperature on the lunar surface can reach over 127°C; the operating environment temperature of deep well logging instruments needs to reach over 168°C; the highest operating temperature of aircraft engine control systems can reach over 93°C; and the highest operating temperature of internal combustion engine vehicle control systems can reach over 90°C. Conventional DC / DC converters have a maximum case temperature of 125°C. When operating at an ambient temperature of 90°C, considering the temperature rise of the casing, their performance has reached the limit of existing products and cannot meet temperature derating requirements. Therefore, these special applications urgently require power supply products that can withstand much higher temperatures. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a high-temperature overcurrent protection circuit for switching power supplies under extreme high-temperature environments. This circuit achieves overcurrent protection in products with a maximum case temperature of 185°C, with accurate protection point settings and good system response performance, enabling high-temperature DC / DC converters to achieve precise overcurrent protection.

[0005] To address the aforementioned technical issues, the present invention employs the following technical solution: A high-temperature overcurrent protection circuit for a switching power supply under extreme high-temperature environments, the protection circuit includes: a high-temperature current sampling circuit unit, a high-temperature rectifier and filter circuit unit, an overcurrent protection setting circuit unit, and a high-temperature PWM control chip; The high-temperature current sampling circuit unit is used to sample the input current through a current transformer at a preset ratio to obtain a sampling signal. The high-temperature rectifier and filter circuit unit is used to rectify and filter the sampled signal and convert it into a DC signal; The overcurrent protection setting circuit unit is used to adjust the DC signal to a preset value and then feed it back to the high-temperature PWM control chip, so that the high-temperature PWM control chip is prohibited from output, thereby realizing circuit overcurrent protection.

[0006] As a further improvement to the above technical solution, the applicable temperature range of the high-temperature overcurrent protection circuit is -55 to 185°C.

[0007] As a further improvement to the above technical solution, the high-temperature current sampling circuit unit includes a current transformer T1, a capacitor C1, a capacitor C2, a resistor R1, and a resistor R2; the current transformer T1 is a high-temperature current transformer.

[0008] The primary side of the current transformer T1 is connected to the input current loop of the DC / DC converter, and the secondary side is the current sampling terminal; the two ends of the capacitor C1 and the resistor R1 connected in parallel are respectively connected to the positive and negative terminals of the secondary side of the current transformer T1; the negative terminal of the secondary side of the current transformer T1 is connected to one end of the capacitor C2, and the other end of the capacitor C2 is grounded; the resistor R2 is connected in parallel across the two ends of the capacitor C2.

[0009] As a further improvement to the above technical solution, the high-temperature rectifier filter circuit unit includes a MOSFET Q1, a resistor R3, and a capacitor C3.

[0010] The source and gate of the MOSFET Q1 are connected to the positive terminal of the secondary side of the current transformer T1; the drain of the MOSFET Q1 is connected to one end of the resistor R3, the other end of the resistor R3 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is grounded.

[0011] As a further improvement to the above technical solution, the overcurrent protection setting circuit unit includes resistor R4, resistor R3 and capacitor C3; wherein resistor R3 and capacitor C3 are shared with the high-temperature rectifier and filter circuit unit.

[0012] One end of the resistor R4 is connected to the drain of the MOS transistor Q1, and the other end is grounded; The connection point between resistor R3 and capacitor C3 leads to a signal line, which is connected to the high-temperature PWM control chip to provide a DC sampling signal to the high-temperature PWM control chip.

[0013] As a further improvement to the above technical solution, the current transformer T1 adopts a flyback topology; the built-in reference voltage of the high-temperature PWM control chip is 3V, and when the DC signal voltage fed back by the overcurrent protection setting circuit unit is greater than 3V, the high-temperature PWM control chip is prohibited from outputting.

[0014] As a further improvement to the above technical solution, the overcurrent protection point of the input current is set by adjusting the turns ratio of the current transformer T1, the resistance value of the resistor R3, the resistance value of the resistor R4, and the capacitance value of the capacitor C3.

[0015] Compared with the prior art, the advantages of the present invention are: The high-temperature overcurrent protection circuit described in this invention breaks through the conventional semiconductor junction temperature limitation of 175°C, and can be used in high-temperature DC / DC converters with a maximum case temperature of 185°C. The function of this protection circuit is to input the current after sampling, rectification, and filtering to the high-temperature PWM control chip. When the input current is too high, the circuit raises the sampling voltage to disable the output of the high-temperature PWM control chip, thereby achieving overcurrent protection. This overcurrent protection circuit expands the application temperature range from the conventional -55 to 125°C to -55 to 185°C, providing precise and stable overcurrent protection for high-temperature converters. This circuit features accurate protection point setting and good system response performance, and can be widely used in various high-temperature switching power supplies. Attached Figure Description

[0016] Figure 1 This is a circuit block diagram of the high-temperature overcurrent protection circuit in this invention; Figure 2 This is a circuit diagram of the high-temperature overcurrent protection circuit in this invention. Detailed Implementation

[0017] The present invention will now be further described with reference to the accompanying drawings.

[0018] like Figure 1 The circuit shown is a high-temperature overcurrent protection circuit for a switching power supply under extreme high-temperature environments, including a high-temperature current sampling circuit unit 1, a high-temperature rectifier and filter circuit unit 2, an overcurrent protection setting circuit unit 3, and a high-temperature PWM control chip 4. Preferably, the high-temperature PWM control chip 4 in this embodiment is a MAGMA chip.

[0019] The input terminal of the high-temperature current sampling circuit unit is connected to the input current. It samples the input current at a certain ratio using a high-temperature current transformer to obtain the required sampling signal. The input terminal of the high-temperature rectifier-filter circuit unit is connected to the output terminal of the current sampling circuit unit. It is used to rectify and filter the sampling signal, converting it into a DC signal. The input terminal of the overcurrent protection setting circuit unit is connected to the output terminal of the rectifier-filter circuit unit. It is used to adjust the DC signal output by the rectifier-filter circuit to a suitable value and feed it back to the high-temperature PWM control chip, thereby disabling the output of the high-temperature PWM control chip and ultimately realizing the overcurrent protection function of the circuit.

[0020] like Figure 2As shown, the high-temperature current sampling circuit unit 1 includes a high-temperature current transformer T1, capacitors C1 and C2, resistors R1 and R2. The primary side of the current transformer T1 is connected to the input current of the high-temperature DC / DC converter, and the secondary side of the current transformer T1 is the current sampling terminal for acquiring the current signal. Capacitor C1 and resistor R1 are connected in parallel, and the parallel connection is between the positive and negative terminals of the secondary side of the current transformer T1. The negative terminal of the secondary side of the current transformer T1 is connected to one end of capacitor C2, and the other end of capacitor C2 is grounded. Resistor R2 is connected in parallel across capacitor C2. Conventional circuits use diode rectification for sampling, but this invention uses a high-temperature resistant MOS and a source-gate interconnection method, utilizing the more stable switching characteristics and lower on-resistance of the MOS at high temperatures to achieve efficient and accurate sampling. The high-temperature current transformer T1 in this invention is manually wound using high-temperature resistant PE33 magnetic material.

[0021] like Figure 2 As shown, the high-temperature rectifier and filter circuit unit 2 includes a MOSFET Q1, a resistor R3, and a capacitor C3. The source and gate of the MOSFET Q1 are connected to the positive terminal of the secondary side of the current transformer T1 in the high-temperature current sampling circuit 1. The drain of the MOSFET Q1 is connected to one end of the resistor R3, and the other end of the resistor R3 is grounded. Conventional circuits use diode rectification for sampling. This invention uses a high-temperature resistant MOSFET Q1 and a source-gate connection, utilizing the more stable switching characteristics and lower on-resistance of the MOSFET at high temperatures to achieve efficient and accurate sampling.

[0022] like Figure 2 As shown, the overcurrent protection setting circuit unit 3 includes resistors R4 and R3, and capacitor C3; resistors R3 and capacitor C3 are shared with the high-temperature rectifier and filter circuit unit 2. One end of resistor R4 is connected to the drain of MOSFET Q1, and the other end is grounded; one end of capacitor C3 is connected to resistor R3, and the other end is grounded. A signal line is led out from the connection point of resistor R3 and capacitor C3 and connected to the high-temperature PWM control chip to provide the high-temperature PWM control chip with the DC sampling signal required by the chip, providing a basis for overcurrent protection judgment. The PWM control chip compares the sampling signal with its internal reference; if it exceeds the reference value, it limits the chip's PWM output, thereby achieving the protection function.

[0023] In this embodiment, the high-temperature current transformer T1 adopts a flyback topology, and its working principle is as follows: When the input current of the high-temperature DC / DC converter flows through the primary side of T1, the secondary side can acquire a current signal proportional to the turns ratio of the current transformer. The acquired current signal first passes through capacitor C1 and resistor R1 connected in parallel on the secondary side of T1 to filter out the oscillation signal caused by parasitic inductance in the circuit. Then, through capacitor C2 and resistor R2, built-in compensation is added to the circuit, making the sampling signal more stable. The sampled signal after filtering and compensation is sent to MOSFET Q1 for rectification. The rectified signal forms a voltage signal across resistor R4. This voltage signal is filtered again by the filter circuit composed of resistor R3 and capacitor C3, and finally forms a stable DC signal, which is input to the high-temperature PWM control chip 4. When the primary side input current is too large and exceeds the safe range, the corresponding DC sampling signal voltage will rise synchronously. When this voltage is greater than the built-in reference voltage (3V) of the high-temperature PWM control chip 4, the high-temperature PWM control chip 4 will immediately disable the output, and the high-temperature DC / DC converter will enter the overcurrent protection state. When this voltage is not greater than the reference voltage, the chip outputs the PWM signal normally. Based on the above principle, in circuit design, by selecting the appropriate turns ratio of the high-temperature current transformer T1, the resistance values ​​of resistors R3 and R4, and the capacitance value of capacitor C3, the overcurrent point of the input current can be precisely controlled, thereby realizing the overcurrent protection of the high-temperature DC / DC converter.

[0024] In summary, the overcurrent protection circuit described in this invention features accurate protection point setting and good system response performance. It is suitable for high-temperature operating environments ranging from -55°C to 185°C and can be widely applied in various high-temperature switching power supplies, providing stable and efficient overcurrent protection for power products in special scenarios such as deep space exploration, deep well exploration, and high-temperature equipment control systems. For applications in extreme high-temperature environments, this invention proposes a systematic application of all high-temperature components and a method of common-gate connection of high-temperature MOS sources. The systematic application of all high-temperature components solves the problem of the lack of suitable overcurrent protection circuits in extreme high-temperature environments. Through modular design, the independent setting function of protection points is achieved, enabling reliable operation of the protection circuit in a 185°C environment. MOS addresses the problem that ordinary diodes cannot operate in high-temperature environments, while high-temperature diodes suffer from large voltage drops and slow response. The use of source-gate connection achieves low-loss, fast-response signal conversion. Conventional circuits are designed based on a maximum operating temperature of 125°C. In extreme high-temperature environments such as 185°C, the parameters of the components themselves will drift drastically at high temperatures, making it difficult to guarantee normal circuit operation. This invention solves the technical problem of lacking a suitable overcurrent protection circuit under extreme high temperature of 185℃. It adopts MOS source-gate connection, overcoming the technical bias of using diodes for rectification.

[0025] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A high-temperature overcurrent protection circuit for a switching power supply under extreme high-temperature environments, characterized in that, The protection circuit includes: a high-temperature current sampling circuit unit (1), a high-temperature rectifier and filter circuit unit (2), an overcurrent protection setting circuit unit (3), and a high-temperature PWM control chip (4). The high-temperature current sampling circuit unit (1) is used to sample the input current through the current transformer at a preset ratio to obtain the sampling signal. The high-temperature rectifier and filter circuit unit (2) is used to rectify and filter the sampled signal and convert it into a DC signal. The overcurrent protection setting circuit unit (3) is used to adjust the DC signal to a preset value and then feed it back to the high-temperature PWM control chip (4) so ​​that the high-temperature PWM control chip (4) is prohibited from output, thereby realizing circuit overcurrent protection.

2. The high-temperature overcurrent protection circuit for switching power supplies under extreme high-temperature environments according to claim 1, characterized in that, The high-temperature current sampling circuit unit (1) includes a current transformer T1, a capacitor C1, a capacitor C2, a resistor R1, and a resistor R2; the current transformer T1 is a high-temperature current transformer. The primary side of the current transformer T1 is connected to the input current loop of the DC / DC converter, and the secondary side is the current sampling terminal; the two ends of the capacitor C1 and the resistor R1 connected in parallel are respectively connected to the positive and negative terminals of the secondary side of the current transformer T1; the negative terminal of the secondary side of the current transformer T1 is connected to one end of the capacitor C2, and the other end of the capacitor C2 is grounded; the resistor R2 is connected in parallel across the two ends of the capacitor C2.

3. The high-temperature overcurrent protection circuit for switching power supplies under extreme high-temperature environments according to claim 2, characterized in that, The high-temperature rectifier filter circuit unit (2) includes a MOS transistor Q1, a resistor R3 and a capacitor C3; The source and gate of the MOSFET Q1 are connected to the positive terminal of the secondary side of the current transformer T1; the drain of the MOSFET Q1 is connected to one end of the resistor R3, the other end of the resistor R3 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is grounded.

4. The high-temperature overcurrent protection circuit for switching power supplies under extreme high-temperature environments according to claim 3, characterized in that, The overcurrent protection circuit unit (3) includes resistor R4, resistor R3 and capacitor C3; wherein resistor R3 and capacitor C3 are shared with the high temperature rectifier and filter circuit unit (2); One end of the resistor R4 is connected to the drain of the MOS transistor Q1, and the other end is grounded; The connection point between resistor R3 and capacitor C3 leads out a signal line and is connected to the high-temperature PWM control chip (4) to provide a DC sampling signal to the high-temperature PWM control chip (4).

5. The high-temperature overcurrent protection circuit for a switching power supply under extreme high-temperature conditions according to any one of claims 1 to 4, characterized in that, The current transformer T1 adopts a flyback topology; The built-in reference voltage of the high-temperature PWM control chip (4) is 3V. When the DC signal voltage fed back by the overcurrent protection setting circuit unit (3) is greater than 3V, the high-temperature PWM control chip (4) is prohibited from outputting.

6. The high-temperature overcurrent protection circuit for a switching power supply under extreme high-temperature conditions according to any one of claims 1 to 4, characterized in that, The overcurrent protection point of the input current is set by adjusting the turns ratio of the current transformer T1, the resistance value of the resistor R3, the resistance value of the resistor R4, and the capacitance value of the capacitor C3.

Images