Secondary-side sampling circuit and device with high isolation voltage

Abstract

The application provides a high-isolation-voltage secondary-side sampling circuit and device, which is composed of a first transformer, a multi-vibrator and a second transformer. The primary winding of the first transformer is electrically connected with a power supply end, the secondary winding of the first transformer is electrically connected with the input end of the multi-vibrator, the output end of the multi-vibrator is electrically connected with the secondary winding of the second transformer, and the primary winding of the second transformer is electrically connected with a PWM controller. When the technical scheme is implemented, the second transformer is used as an isolation device, the isolation voltage of which can reach 10,000 volts, meeting the requirement of high isolation voltage, and on this basis, the sampling difficulty of the multi-vibrator to the secondary-side sampling voltage is reduced. Meanwhile, based on the setting of the multi-vibrator, the sampling voltage fed back by the multi-vibrator of the secondary side can reach 2V-60V, that is, the power voltage range supported by sampling is wide, meeting the requirements of most engineering applications, and the applicability is strong.

Description

Technical Field

[0001] This invention relates to the field of circuit control technology, and more specifically to a secondary-side sampling circuit and device with high isolation voltage. Background Technology

[0002] Currently, isolated power supplies are frequently used in high-voltage power supplies or power device drive circuits, requiring high isolation voltages on both the primary and secondary sides. This makes sampling the secondary voltage difficult. Most commercially available isolation solutions use optocouplers, optical fibers, or digital isolation. However, optocouplers have limited lifespans, optical fibers are bulky, and digital isolation offers low isolation voltages. Furthermore, existing methods for sampling the secondary voltage are not only difficult but also often have limited ranges, making them unsuitable for most engineering applications.

[0003] Therefore, existing technologies need to be improved. Summary of the Invention

[0004] The main objective of this invention is to provide a secondary-side sampling circuit and device with high isolation voltage, so as to at least solve the technical problem of difficulty in secondary-side voltage sampling in the driving circuit in related technologies.

[0005] A first aspect of the present invention provides a secondary-side sampling circuit with high isolation voltage, the secondary-side sampling circuit including a first transformer, a multivibrator and a second transformer; the primary winding of the first transformer is electrically connected to a power supply terminal, the secondary winding of the first transformer is electrically connected to the input terminal of the multivibrator, the output terminal of the multivibrator is electrically connected to the secondary winding of the second transformer, and the primary winding of the second transformer is electrically connected to the PWM controller.

[0006] A second aspect of the present invention provides a power control device, including a power supply, a PWM controller, and a secondary sampling circuit as described in the first aspect, wherein the power supply terminal is electrically connected to the input terminal of the secondary sampling circuit, and the PWM controller is electrically connected to the output terminal of the secondary sampling circuit.

[0007] The present invention discloses a high-isolation voltage secondary-side sampling circuit and device, which comprises a first transformer, a multivibrator, and a second transformer. The primary winding of the first transformer is electrically connected to the power supply terminal, the secondary winding of the first transformer is electrically connected to the input terminal of the multivibrator, the output terminal of the multivibrator is electrically connected to the secondary winding of the second transformer, and the primary winding of the second transformer is electrically connected to the PWM controller. By implementing the technical solution of this application, on the one hand, since the second transformer is used as an isolation device, its isolation voltage can reach 10,000 volts, which meets the requirement of high isolation voltage, and on this basis, the sampling difficulty of the multivibrator for the secondary side sampling voltage can be reduced; on the other hand, since the multivibrator is set between the secondary winding of the first transformer and the secondary winding of the second transformer, and since the sampling voltage can be determined by the characteristics of the transistor in the multivibrator, it can usually reach 2V to 60V. That is to say, the sampling voltage fed back by the secondary multivibrator can reach 2V to 60V, which can support a wide range of power supply voltages for sampling, which can meet the needs of most engineering applications and has strong applicability. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of the circuit connection of the high isolation voltage secondary sampling circuit provided in one embodiment of the present invention;

[0010] Figure 2 This is a schematic diagram of the circuit connection of the secondary-side sampling circuit with high isolation voltage provided in one embodiment of the present invention.

[0011] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0012] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0013] It should be noted that related terms such as "first" and "second" can be used to describe various components, but these terms do not limit the component. These terms are only used to distinguish one component from another. For example, without departing from the scope of the invention, the first component can be referred to as the second component, and the second component can similarly be referred to as the first component. The term "and / or" refers to any one or more combinations of related and descriptive terms.

[0014] Please see Figure 1 , Figure 1 The diagram shows a circuit connection diagram of a high isolation voltage secondary sampling circuit according to an embodiment of the present invention. Specifically, it includes a first transformer T1, a multivibrator 10, and a second transformer T2, which are connected in sequence. The primary winding of the first transformer T1 is electrically connected to the power supply terminal, the secondary winding of the first transformer T1 is electrically connected to the input terminal of the multivibrator 10, the output terminal of the multivibrator 10 is electrically connected to the secondary winding of the second transformer T2, and the primary winding of the second transformer T2 is electrically connected to the PWM controller.

[0015] Specifically, the first transformer T1 is a device that uses the principle of electromagnetic induction to change AC voltage, and in this embodiment, it mainly functions as a voltage converter. Its primary winding ( Figure 1 The winding on the left side of the first transformer T1 is used to connect to the power supply terminal (the power supply terminal on the power source) and receive the power supply voltage from the power supply terminal. The secondary winding of the first transformer T1 ( Figure 1 The winding on the right side of transformer T1 is used to output the first operating voltage. Specifically, when the supply voltage passes through the first transformer T1, it is converted into the first operating voltage and output from the secondary winding of the first transformer T1.

[0016] Specifically, the multivibrator 10 represents an oscillator that utilizes deep positive feedback to alternately turn two electronic devices on and off through RC coupling, thereby generating a square wave output. The multivibrator 10 has no steady state, only two metastable states (first operating state and second operating state). During operation, the circuit state automatically alternates between these two metastable states, thereby generating a rectangular wave pulse signal, commonly used as a pulse signal source and clock signal in timing circuits. That is, its input terminal is used to acquire the first operating voltage (sampling voltage) from the first transformer T1, and the output terminal of the multivibrator 10 is used to output the second operating voltage; wherein, when the first operating voltage passes through the multivibrator 10, it is converted into the second operating voltage and output from the output terminal of the multivibrator 10.

[0017] Specifically, the second transformer T2 is also a device that uses the principle of electromagnetic induction to change AC voltage, but in this embodiment, its main function is isolation. The secondary winding of the second transformer T2 (Figure 1 The winding on the right side of T2 is used to receive the second operating voltage from the multivibrator 10, and the primary winding of the second transformer is used to output the third operating voltage to the PWM controller.

[0018] When implementing this technical solution, on the one hand, by using the second transformer T2 as an isolation device, its isolation voltage can reach 10,000 volts, meeting the requirement for high isolation voltage, and on this basis, reducing the sampling difficulty of the secondary-side sampling voltage of the multivibrator; on the other hand, since the multivibrator 10 is located between the secondary windings of the first transformer T1 and the secondary windings of the second transformer T2, and since the sampling voltage can be determined by the characteristics of the transistors within the multivibrator 10, various sampling voltages of different magnitudes can be achieved by selecting and matching the components within the multivibrator 10, typically ranging from 2V to 60V. This means that the sampling voltage fed back from the secondary-side multivibrator can reach 2V to 60V, supporting a wide range of power supply voltages for sampling, meeting the needs of most engineering applications and demonstrating strong applicability. Furthermore, compared with traditional isolation solutions using optocouplers, optical fibers, or digital isolation, it also has advantages such as low cost, fewer components, long lifespan, and ease of implementation.

[0019] Please see Figure 2 The secondary sampling circuit also includes a first rectifier and filter circuit 20, which is electrically connected between the secondary winding of the first transformer T1 and the input terminal of the multivibrator 10. Its main function is to rectify and filter the first operating voltage output from the first transformer T1. That is, when the above embodiment includes the first rectifier and filter circuit 20, the first rectifier and filter circuit 20 rectifies and filters the first operating voltage output from the first transformer T1 to obtain a fourth operating voltage. This fourth operating voltage is transmitted to the input terminal of the multivibrator 10, where it is processed, and the resulting second operating voltage is fed back to the secondary winding of the second transformer T2.

[0020] The first rectifier-filter circuit 20 may include a first diode D1 and a third capacitor C3. The anode of the first diode D1 is electrically connected to the same-name terminal of the secondary winding of the first transformer T1, and the cathode of the first diode D1 is electrically connected to both the input terminal of the multivibrator 10 and one end of the third capacitor C3. The other end of the third capacitor C3 is grounded. Thus, the first rectifier-filter circuit 20, composed of the first diode D1 and the third capacitor C3, filters the first operating voltage.

[0021] In some specific embodiments of this example, the multivibrator 10 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2, a first transistor Q1, and a second transistor Q2. The specific connection relationships between the above electronic components are as follows: one end of the first resistor R1 is electrically connected to one end of the second resistor R2, one end of the third resistor R3, one end of the fourth resistor R4, and the first rectifier filter circuit 20; the other end of the first resistor R1 is electrically connected to one end of the first capacitor C1, the collector of the first transistor Q1, and the same-name terminal of the secondary winding of the second transformer T2; the base of the first transistor Q1 is electrically connected to one end of the second capacitor C2 and the other end of the third resistor R3; the emitter of the first transistor Q1 is grounded; the other end of the first capacitor C1 is electrically connected to the other end of the second resistor R2 and the second transistor Q2; the collector of the second transistor Q2 is electrically connected to the other end of the second capacitor C2, the other end of the fourth resistor R4, and the opposite-name terminal of the secondary winding of the second transformer T2; the second transistor Q2 is grounded.

[0022] Specifically, the multivibrator 10, configured with the aforementioned electronic components, operates in two alternating states during implementation: When the multivibrator 10 is in its first operating state, the first transistor Q1 is turned on, with its collector voltage being Vce_sat (Vce_sat is approximately 0V). The first capacitor C1 discharges due to the current flowing through the second resistor R2 and Q1_CE. Because the first capacitor C1 provides a reverse voltage, the second transistor Q2 is turned off. The second capacitor C2 is charged through the fourth resistor R4 and Q1_BE, resulting in a high output voltage (but slightly lower than the power supply voltage due to C2 being charged through R4). This state continues until the first capacitor C1 has completely discharged. The second operating voltage is equal to the difference between the first operating voltage and the forward voltage drop of the first transistor.

[0023] Furthermore, because the second resistor R2 provides base bias, the second transistor Q2 enters the conducting state, and the multivibrator 10 enters state two. That is, when the multivibrator 10 is in the second operating state, the second transistor Q2 enters the conducting state, and the collector voltage of Q2 (i.e., the output voltage) changes from a high potential to Vce_sat. Because the second capacitor C2 provides reverse voltage, the first transistor Q1 is momentarily cut off. Q1 is cut off, causing the collector voltage of Q1 to rise to a high potential. C1 is charged through R1 and Q2_BE, and the current flowing through R3 and Q2_CE of C1 discharges. Because capacitor C2 provides reverse voltage, Q1 is cut off. This state continues until C2 is completely discharged. Because R3 provides bias voltage to the base of Q1, Q1 conducts, causing the multivibrator 10 to enter state one again. That is, the multivibrator 10 operates alternately in the first and second operating states. The second operating voltage is equal to the difference between the first operating voltage and the forward voltage drop of the second transistor.

[0024] It should be noted that, because the turn-on delay time of the first transistor differs from that of the second transistor, during the startup process of the multivibrator circuit: when the circuit is first connected to the power supply, both transistors (Q1 and Q2) are in the off state. However, when the base voltages of these two transistors rise together, since it is impossible to control the turn-on delay of each transistor to be the same during the transistor manufacturing process, one of the transistors will inevitably turn on first. Thus, the circuit enters one of the states, while also ensuring continuous oscillation.

[0025] In this multivibrator, the oscillation period T = 1.4 * R2 * C2. The resistance of the second resistor R2 is equal to that of the third resistor R3, the resistance of the first resistor R1 is equal to that of the fourth resistor R4, the capacitance of the second capacitor C2 is equal to that of the third capacitor C3, and the resistance of the second resistor R2 is greater than that of the first resistor R1. While manufacturing errors and temperature affect the oscillation period of the multivibrator, the oscillation period does not affect the sampling accuracy. As long as Q1 and Q2 are saturated and conducting, the output voltage is approximately equal to VCC (sampling voltage) - Vce / sat.

[0026] In some specific embodiments of this implementation, the secondary sampling circuit further includes a second rectifier and filter circuit 30, which is electrically connected between the primary winding of the second transformer T2 and the PWM controller. It performs rectification and filtering on the third operating voltage output from the second transformer T2.

[0027] The second rectifier-filter circuit 30 may include a second diode D2 and a fourth capacitor C4. The anode of the second diode D2 is electrically connected to the same-name terminal of the primary winding of the second transformer T2, and the cathode of the second diode D2 is electrically connected to one end of the fourth capacitor C4 and the PWM controller. The other end of the fourth capacitor C4 is also electrically connected to the PWM controller. That is, the second rectifier-filter circuit 30, composed of the second diode D2 and the fourth capacitor C4, rectifies and filters the third operating voltage output from the same-name terminal of the primary winding of the second transformer T2, and feeds the resulting fifth operating voltage back to the PWM controller, thereby providing a more stable secondary-side sampling voltage for the PWM controller.

[0028] In some specific embodiments of this implementation, the secondary sampling circuit also includes a voltage divider circuit 40, which is electrically connected between the second rectifier filter circuit 30 and the PWM controller. The voltage divider circuit 40 can perform voltage division processing of the fifth working voltage, providing protection for the subsequent PWM controller and preventing the voltage division value from exceeding the power supply of the subsequent circuit.

[0029] In some specific embodiments of this implementation, the first transistor is an NPN transistor, and the second transistor is an NPN transistor. An NPN transistor is a transistor composed of two N-type semiconductors sandwiching a P-type semiconductor; it is also called a bipolar junction transistor (BJT), and can be said to be one of the most important devices in electronic circuits. The transistor is the most important device in electronic circuits; its primary functions are current amplification and switching. It can convert weak electrical signals into signals of a certain strength. Of course, this conversion still follows the law of conservation of energy; it simply converts the energy of the power source into the energy of the signal.

[0030] In an embodiment of the present invention, a power control device is also provided, comprising a power supply, a PWM controller, and the aforementioned secondary-side sampling circuit. The power supply terminal is electrically connected to the input terminal of the secondary-side sampling circuit, and the PWM controller is electrically connected to the output terminal of the secondary-side sampling circuit. Thus, by utilizing the wide range of sampling voltages of the secondary-side sampling circuit, it is possible to adapt to power supplies with different supply voltages, thereby improving adaptability.

[0031] Compared to traditional drive circuits using optocouplers, optical fibers, and digital isolation devices, this technical solution, by employing a second transformer T2 as the isolation device, achieves an isolation voltage of up to 10,000 volts, meeting the high isolation voltage requirements. Furthermore, it reduces the sampling difficulty of the secondary-side sampling voltage for the multivibrator. Since the multivibrator 10 is positioned between the secondary windings of the first transformer T1 and the second transformer T2, and the sampling voltage can be determined by the characteristics of the transistors within the multivibrator 10, various sampling voltages can be achieved through selective configuration of the components within the multivibrator 10, typically ranging from 2V to 60V. This means the sampling voltage fed back from the secondary-side multivibrator can reach 2V to 60V, supporting a wide range of power supply voltages suitable for most engineering applications, demonstrating strong applicability. In addition, compared to traditional isolation schemes using optocouplers, optical fibers, and digital isolation devices, this solution also offers advantages such as low cost, fewer components, longer lifespan, and ease of implementation.

[0032] It should be noted that, for the sake of simplicity, the aforementioned circuit embodiments are described as the connection relationships of various electronic components in the circuit. However, those skilled in the art should understand that this application is not limited to the models of the described electronic components, because according to this application, the models of certain electronic components can be selected according to actual needs and specific power supply requirements. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0033] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0034] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A secondary-side sampling circuit with high isolation voltage, characterized in that, The secondary sampling circuit includes a first transformer, a multivibrator, a second transformer, and a first rectifier and filter circuit. Wherein, the primary winding of the first transformer is electrically connected to the power supply terminal, the secondary winding of the first transformer is electrically connected to the input terminal of the multivibrator, the output terminal of the multivibrator is electrically connected to the secondary winding of the second transformer, the primary winding of the second transformer is electrically connected to the PWM controller, and the first rectifier filter circuit is electrically connected between the secondary winding of the first transformer and the input terminal of the multivibrator. The multivibrator includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a first transistor, and a second transistor; One end of the first resistor is electrically connected to one end of the second resistor, one end of the third resistor, one end of the fourth resistor, and the first rectifier filter circuit. The other end of the first resistor is electrically connected to one end of the first capacitor, the collector of the first transistor, and the same-name terminal of the secondary winding of the second transformer. The base of the first transistor is electrically connected to one end of the second capacitor and the other end of the third resistor. The emitter of the first transistor is grounded. The other end of the first capacitor is electrically connected to the other end of the second resistor and the second transistor. The collector of the second transistor is electrically connected to the other end of the second capacitor, the other end of the fourth resistor, and the opposite-name terminal of the secondary winding of the second transformer. The second transistor is grounded. The secondary winding of the first transformer is used to output a first operating voltage. The output terminal of the multivibrator is used to output a second operating voltage.

2. The secondary-side sampling circuit with high isolation voltage as described in claim 1, characterized in that, The conduction delay time of the first transistor is different from that of the second transistor.

3. The secondary-side sampling circuit with high isolation voltage as described in claim 1, characterized in that, The resistance value of the second resistor is equal to the resistance value of the third resistor, the resistance value of the first resistor is equal to the resistance value of the fourth resistor, the capacitance value of the second capacitor is equal to the capacitance value of the first capacitor, and the resistance value of the second resistor is greater than the resistance value of the first resistor.

4. The secondary-side sampling circuit with high isolation voltage as described in claim 1, characterized in that, When the multivibrator is in the first operating state, the first transistor enters the conducting state, the second transistor enters the cut-off state, and the second operating voltage is equal to the difference between the first operating voltage and the on-state voltage drop of the first transistor. When the multivibrator is in the second operating state, the second transistor enters the conducting state, the first transistor enters the cut-off state, and the second operating voltage is equal to the difference between the first operating voltage and the on-state voltage drop of the second transistor.

5. The secondary-side sampling circuit with high isolation voltage as described in claim 1, characterized in that, The secondary sampling circuit also includes a second rectifier and filter circuit; The second rectifier and filter circuit is electrically connected between the primary winding of the second transformer and the PWM controller.

6. The secondary-side sampling circuit with high isolation voltage as described in claim 5, characterized in that, The secondary sampling circuit also includes a voltage divider circuit; The voltage divider circuit is electrically connected between the second rectifier filter circuit and the PWM controller.

7. The secondary-side sampling circuit with high isolation voltage as described in claim 1, characterized in that, The first transistor is an NPN transistor, and the second transistor is an NPN transistor.

8. A power control device, characterized in that, It includes a power supply, a PWM controller, and a secondary sampling circuit as described in any one of claims 1 to 7, wherein the power supply terminal is electrically connected to the input terminal of the secondary sampling circuit, and the PWM controller is electrically connected to the output terminal of the secondary sampling circuit.

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