A PWM duty cycle control optocoupler linear driving interface circuit

Abstract

This invention discloses a PWM duty cycle controlled optocoupler linear drive interface circuit, relating to the field of signal isolation transmission. The PWM duty cycle controlled optocoupler linear drive interface circuit includes a power supply module for supplying power to a voltage-equivalent module. The advantages of this invention are: it achieves linear control of the optocoupler input current through the PWM signal output of the MCU, realizing signal isolation transmission from a low-voltage weak current area to a high-voltage strong current area in a low-cost manner; it cleverly utilizes the amplification characteristics of operational amplifiers for voltage signals to achieve automatic matching between the MCU's output level and the optocoupler's input level; it enables the MCU to linearly control the optocoupler's input current using PWM; it achieves smooth filtering of the MCU's PWM output, and simultaneously achieves a certain bandwidth gain for the overall interface circuit, thereby enabling the system's control loop to have a settable dynamic response.

Description

Technical Field

[0001] This invention relates to the field of signal isolation transmission, specifically to a PWM duty cycle controlled optocoupler linear drive interface circuit. Background Technology

[0002] In the composition of a new energy vehicle charger control system, such as Figure 1 As shown, the LLC control chip located in the high-voltage isolation zone needs to be controlled by the MCU, while the MCU is generally located in the non-isolated low-voltage zone. In order to enable the MCU located in the non-isolated low-voltage zone to perform linear control on the LLC chip located in the high-voltage isolation zone, using an optocoupler (hereinafter referred to as optocoupler) to achieve isolated signal transmission is a preferred solution with low cost and high reliability.

[0003] However, the nonlinear current-voltage characteristics of the photodiode at the input of the optocoupler prevent linear isolated signal transmission, which requires improvement. Summary of the Invention

[0004] The purpose of this invention is to provide an optocoupler linear drive interface circuit with PWM duty cycle control to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A PWM duty cycle controlled optocoupler linear drive interface circuit includes:

[0007] The power supply module is used to supply power to modules with the same voltage.

[0008] The pre-filtering module is used to filter the PWM signal output by the MCU and output it to the voltage equalization module;

[0009] The voltage equivalence module is used to provide the linear module with a voltage of the same magnitude as the output voltage of the pre-filtering module; and to power the optocoupler output module after passing through the filtering module.

[0010] The filtering module is used to filter the input voltage.

[0011] The linear module is used to ensure that the current at the input of the optocoupler output module is linearly related to the PWM signal output by the MCU, based on the voltage provided by the voltage equalization module.

[0012] The optocoupler output module is used to enable the PWM signal output by the MCU to linearly control the LLC control chip;

[0013] The MCU is connected to the pre-filter module, the pre-filter module is connected to the voltage equivalence module, the power supply module is connected to the voltage equivalence module, the voltage equivalence module is connected to the filter module and the linear module, the filter module is connected to the optocoupler output module, and the optocoupler output module is connected to the linear module and the LLC control chip.

[0014] As a further embodiment of the present invention: the pre-filtering module includes resistor R3, resistor R4, capacitor C6, and capacitor C7. One end of resistor R4 is connected to the MCU, the other end of resistor R4 is connected to one end of capacitor C7 and one end of resistor R3, the other end of capacitor C7 is grounded, the other end of resistor R3 is connected to one end of capacitor C6, the voltage is the same as the module, and the other end of capacitor C6 is grounded.

[0015] As a further embodiment of the present invention: the voltage equivalence module includes a resistor R6 and an amplifier U9. The non-inverting input of the amplifier U9 is connected to one end of the resistor R6 and a pre-filter module. The other end of the resistor R6 is grounded. The inverting input of the amplifier U9 is connected to a linear module. The power supply terminal of the amplifier U9 is connected to a power supply module. The output terminal of the amplifier U9 is connected to a filter module.

[0016] As a further embodiment of the present invention: the power supply module includes a 5V power supply, capacitor C3, and capacitor C4. The 5V power supply is connected to one end of capacitor C3, one end of capacitor C4, and the voltage is the same as the module. The other end of capacitor C3 is grounded, and the other end of capacitor C4 is grounded.

[0017] As a further embodiment of the present invention: the filtering module includes a resistor R5 and a capacitor C2. One end of the resistor R5 is connected to the voltage equalization module, and the other end of the resistor R5 is connected to one end of the capacitor C2 and the optocoupler output module. The other end of the capacitor C2 is grounded.

[0018] As a further embodiment of the present invention: the linear module includes resistor R1, resistor R2, and capacitor C5. One end of resistor R1 is connected to the optocoupler output module, one end of capacitor C5, and the inverting terminal of amplifier U9. The other end of resistor R1 is grounded. The other end of capacitor C5 is connected to one end of resistor R2. The other end of resistor R2 is connected to the output terminal of amplifier U9.

[0019] As a further embodiment of the present invention: the optocoupler output module includes an optocoupler P1 and a capacitor C1. The first end of the optocoupler P1 is connected to the filter module, the second end of the optocoupler P1 is connected to the linear module, the third end of the optocoupler P1 is connected to ground, the fourth end of the optocoupler P1 is connected to one end of the capacitor C1 and the LLC control chip, and the other end of the capacitor C1 is grounded.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention achieves linear control of the optocoupler input current through the output PWM signal of the MCU, and realizes signal isolation transmission from the low-voltage weak current area to the high-voltage strong current area in a low-cost manner (linear module, voltage equivalent module); it cleverly utilizes the amplification characteristics of the operational amplifier for voltage signals to achieve automatic matching between the output level of the MCU and the input level of the optocoupler; it realizes linear control of the optocoupler input current by the MCU in a PWM manner; it realizes smooth filtering by the MCU output in a PWM manner (pre-filter module, filter module), and at the same time realizes that the overall interface circuit has a certain bandwidth gain (linear module), thereby enabling the system control loop to have a settable dynamic response. Attached Figure Description

[0021] Figure 1 This is a circuit diagram of an optocoupler linear drive interface circuit with PWM duty cycle control. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Please see Figure 1 A PWM duty cycle controlled optocoupler linear drive interface circuit, comprising:

[0024] The power supply module is used to supply power to modules with the same voltage.

[0025] The pre-filtering module is used to filter the PWM signal output by the MCU and output it to the voltage equalization module;

[0026] The voltage equivalence module is used to provide the linear module with a voltage of the same magnitude as the output voltage of the pre-filtering module; and to power the optocoupler output module after passing through the filtering module.

[0027] The filtering module is used to filter the input voltage.

[0028] The linear module is used to ensure that the current at the input of the optocoupler output module is linearly related to the PWM signal output by the MCU, based on the voltage provided by the voltage equalization module.

[0029] The optocoupler output module is used to enable the PWM signal output by the MCU to linearly control the LLC control chip;

[0030] The MCU is connected to the pre-filter module, the pre-filter module is connected to the voltage equivalence module, the power supply module is connected to the voltage equivalence module, the voltage equivalence module is connected to the filter module and the linear module, the filter module is connected to the optocoupler output module, and the optocoupler output module is connected to the linear module and the LLC control chip.

[0031] In this embodiment: Please refer to Figure 1 The pre-filtering module includes resistors R3 and R4, capacitors C6 and C7. One end of resistor R4 is connected to the MCU, and the other end of resistor R4 is connected to one end of capacitor C7 and one end of resistor R3. The other end of capacitor C7 is grounded, and the other end of resistor R3 is connected to one end of capacitor C6. The voltage is the same as the module, and the other end of capacitor C6 is grounded.

[0032] Resistor R3 and capacitor C6, and resistor R4 and capacitor C7 are used for pre-filtering to convert the PWM signal output by the MCU into a stable voltage output to the non-inverting input of amplifier U9.

[0033] In this embodiment: Please refer to Figure 1 The voltage equalization module includes resistor R6 and amplifier U9. The non-inverting input of amplifier U9 is connected to one end of resistor R6 and the pre-filter module. The other end of resistor R6 is grounded. The inverting input of amplifier U9 is connected to the linear module. The power supply terminal of amplifier U9 is connected to the power supply module. The output terminal of amplifier U9 is connected to the filter module.

[0034] Based on the characteristics of the amplifier, the voltage at its non-inverting input is equal to the voltage at its inverting input. Therefore, the voltage at the inverting input corresponds to the PWM signal output by the MCU.

[0035] In this embodiment: Please refer to Figure 1 The power supply module includes a 5V power supply, capacitor C3, and capacitor C4. The 5V power supply is connected to one end of capacitor C3 and one end of capacitor C4, and the voltage is the same as the module. The other end of capacitor C3 is grounded, and the other end of capacitor C4 is grounded.

[0036] The 5V power supply is output to amplifier U9 through capacitors C3 and C4, serving as the power supply for amplifier U9.

[0037] In this embodiment: Please refer to Figure 1 The filter module includes resistor R5 and capacitor C2. One end of resistor R5 is connected to the voltage equalization module, and the other end of resistor R5 is connected to one end of capacitor C2 and the optocoupler output module. The other end of capacitor C2 is grounded.

[0038] Amplifier U9, after passing through a filtering module, becomes the output module of the optocoupler. The input voltage is filtered by a filter circuit consisting of resistor R5 and capacitor C2 to ensure a stable voltage supply.

[0039] In this embodiment: Please refer to Figure 1 The linear module includes resistors R1 and R2, and capacitor C5. One end of resistor R1 is connected to the optocoupler output module, one end of capacitor C5, and the inverting input of amplifier U9. The other end of resistor R1 is grounded. The other end of capacitor C5 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the output of amplifier U9.

[0040] The voltage across resistor R1 is the voltage at the inverting input of amplifier U9, corresponding to the PWM signal output by the MCU. Since the resistance value of R1 is fixed, the current across R1 is also fixed, thus determining the current at the input of the optocoupler output module, which is linearly related to the PWM signal output by the MCU. Resistor R2 and capacitor C5 are connected to the negative feedback of amplifier U9, forming an amplifier circuit with a certain bandwidth and gain.

[0041] In this embodiment: Please refer to Figure 1 The optocoupler output module includes an optocoupler P1 and a capacitor C1. The first end of the optocoupler P1 is connected to the filter module, the second end of the optocoupler P1 is connected to the linear module, the third end of the optocoupler P1 is connected to ground, and the fourth end of the optocoupler P1 is connected to one end of the capacitor C1 and the LLC control chip. The other end of the capacitor C1 is grounded.

[0042] The input current of optocoupler P1 is linearly related to the PWM signal output by the MCU, and the output is sent to the LLC control chip. The optocoupler realizes isolated linear transmission between electricity and light, enabling control of high voltage and strong current areas from low voltage and weak current areas.

[0043] The working principle of this invention is as follows: the power supply module supplies power to the voltage equivalence module; the pre-filtering module filters the PWM signal output by the MCU and outputs it to the voltage equivalence module; the voltage equivalence module provides the linear module with a voltage of the same magnitude as the output voltage of the pre-filtering module; and the filtering module supplies power to the optocoupler output module; the filtering module filters the input voltage; the linear module, based on the voltage provided by the voltage equivalence module, makes the current at the input of the optocoupler output module linearly related to the PWM signal output by the MCU; the optocoupler output module enables the PWM signal output by the MCU to linearly control the LLC control chip.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0045] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A PWM duty cycle controlled optocoupler linear drive interface circuit, characterized in that: The optocoupler linear drive interface circuit with PWM duty cycle control includes: The power supply module is used to supply power to modules with the same voltage. The pre-filtering module is used to filter the PWM signal output by the MCU and output it to the voltage equalization module; The voltage equivalence module is used to provide the linear module with a voltage of the same magnitude as the output voltage of the pre-filtering module; and to power the optocoupler output module after passing through the filtering module. The filtering module is used to filter the input voltage. The linear module is used to ensure that the current at the input of the optocoupler output module is linearly related to the PWM signal output by the MCU, based on the voltage provided by the voltage equalization module. The optocoupler output module is used to enable the PWM signal output by the MCU to linearly control the LLC control chip; The MCU is connected to the pre-filter module, the pre-filter module is connected to the voltage equivalence module, the power supply module is connected to the voltage equivalence module, the voltage equivalence module is connected to the filter module and the linear module, the filter module is connected to the optocoupler output module, and the optocoupler output module is connected to the linear module and the LLC control chip. The voltage equivalence module includes resistor R6 and amplifier U9. The non-inverting input of amplifier U9 is connected to one end of resistor R6 and the pre-filter module. The other end of resistor R6 is grounded. The inverting input of amplifier U9 is connected to the linear module. The power supply terminal of amplifier U9 is connected to the power supply module. The output terminal of amplifier U9 is connected to the filter module. The linear module includes resistors R1 and R2, and capacitor C5. One end of resistor R1 is connected to the optocoupler output module, one end of capacitor C5, and the inverting input of amplifier U9. The other end of resistor R1 is grounded. The other end of capacitor C5 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the output terminal of amplifier U9.

2. The optocoupler linear drive interface circuit with PWM duty cycle control according to claim 1, characterized in that, The pre-filtering module includes resistors R3 and R4, and capacitors C6 and C7. One end of resistor R4 is connected to the MCU, and the other end of resistor R4 is connected to one end of capacitor C7 and one end of resistor R3. The other end of capacitor C7 is grounded, and the other end of resistor R3 is connected to one end of capacitor C6. The voltage is the same as the module, and the other end of capacitor C6 is grounded.

3. The optocoupler linear drive interface circuit with PWM duty cycle control according to claim 1, characterized in that, The power supply module includes a 5V power supply, capacitor C3, and capacitor C4. The 5V power supply is connected to one end of capacitor C3 and one end of capacitor C4, with the voltage being the same as the module. The other end of capacitor C3 is grounded, and the other end of capacitor C4 is grounded.

4. The optocoupler linear drive interface circuit with PWM duty cycle control according to claim 1, characterized in that, The filter module includes a resistor R5 and a capacitor C2. One end of the resistor R5 is connected to the voltage equalization module, and the other end of the resistor R5 is connected to one end of the capacitor C2 and the optocoupler output module. The other end of the capacitor C2 is grounded.

5. The optocoupler linear drive interface circuit with PWM duty cycle control according to claim 1, characterized in that, The optocoupler output module includes an optocoupler P1 and a capacitor C1. The first end of the optocoupler P1 is connected to the filter module, the second end of the optocoupler P1 is connected to the linear module, the third end of the optocoupler P1 is connected to ground, and the fourth end of the optocoupler P1 is connected to one end of the capacitor C1 and the LLC control chip. The other end of the capacitor C1 is grounded.

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