Power supply system

Abstract

The invention discloses a power supply system, which relates to the technical field of power supply and comprises a PID (Proportion Integration Differentiation) control circuit and a voltage control type Buck power supply circuit, the voltage control type Buck power supply circuit comprises a power circuit and a control circuit; the PID control circuit is used for carrying out PID calculation on the deviation of the set voltage and the output voltage of the voltage control type Buck power supply circuit to obtain a reference voltage and outputting the reference voltage to the control circuit; the control circuit is used for controlling the conduction state of a switching tube in the power circuit according to the reference voltage and the output voltage of the voltage control type Buck power supply circuit so as to control the output of the power circuit; the output of the power circuit is used as the output of the voltage control type Buck power supply circuit; and the power circuit is used for carrying out voltage conversion on the voltage of the power supply and outputting. According to the power supply system, hardware loop compensation is replaced by software PID calculation, the stability of the output voltage can be ensured, and the requirements of reflow soldering detection components are met.

Description

Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a power supply system. Background Art

[0002] The requirements of reflow soldering equipment for the accuracy of operating parameters such as temperature and frequency response are getting higher and higher, which makes the requirements for the power supply of reflow soldering detection components also get higher and higher. The voltage-controlled Buck power supply circuit has the advantages of simple circuit structure, strong anti-noise ability, and low output impedance. It is usually used as the power supply of reflow soldering detection components in reflow soldering equipment. In order to make the stability and response speed of the entire system of the voltage-controlled Buck power supply circuit meet the actual needs of the detection component, hardware loop compensation is usually designed to compensate the system by adding zeros and poles. However, it is difficult to design hardware loop compensation, resulting in the working performance of the voltage-controlled Buck power supply circuit unable to meet the needs of the reflow soldering detection component. Therefore, how to solve the above-mentioned technical defects has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0003] The purpose of this application is to provide a power supply system that uses software PID calculation instead of hardware loop compensation to ensure output voltage stability and meet the needs of reflow soldering detection components.

[0004] In order to solve the above technical problems, the present application provides a power supply system, comprising:

[0005] PID control circuit and voltage-controlled Buck power supply circuit; the voltage-controlled Buck power supply circuit includes a power circuit and a control circuit;

[0006] The PID control circuit is used to perform PID calculation on the deviation between the set voltage and the output voltage of the voltage-controlled Buck power supply circuit to obtain a reference voltage, and output the reference voltage to the control circuit;

[0007] The control circuit is used to control the conduction state of the switch tube in the power circuit according to the reference voltage and the output voltage of the voltage-controlled Buck power circuit, so as to control the output of the power circuit; the output of the power circuit serves as the output of the voltage-controlled Buck power circuit;

[0008] The power circuit is used to convert the voltage of the power supply and output it.

[0009] In some embodiments, the PID control circuit comprises:

[0010] PID controller, digital-to-analog conversion device;

[0011] The PID controller is used to perform analog-to-digital conversion on the output voltage of the voltage-controlled Buck power supply circuit to obtain an output voltage in the form of a digital signal, perform PID calculation on the deviation between the set voltage and the output voltage in the form of the converted digital signal, and output a PWM signal;

[0012] The digital-to-analog conversion device is used to perform digital-to-analog conversion on the PWM signal, and output a reference voltage in the form of an analog signal obtained by the conversion to the control circuit.

[0013] In some embodiments, the PID control circuit further includes:

[0014] The communication device is used to communicate with the host computer and receive the set voltage sent by the host computer.

[0015] In some embodiments, the control circuit comprises:

[0016] Sampling circuit, error amplifier circuit, comparison circuit, driver;

[0017] The sampling circuit is used to sample the output voltage of the voltage-controlled Buck power supply circuit;

[0018] The error amplifier circuit is used to compare the output voltage of the voltage-controlled Buck power supply circuit with the reference voltage, and to amplify the deviation between the output voltage of the voltage-controlled Buck power supply circuit and the reference voltage;

[0019] The comparison circuit is used to compare the output of the error amplifier with the output of the sawtooth wave generator;

[0020] The driver is used to control the switch tube in the power circuit according to the output of the comparison circuit.

[0021] In some embodiments, the sampling circuit comprises:

[0022] A first resistor and a second resistor; one end of the first resistor is connected to the first output end of the power circuit, the other end of the first resistor is connected to one end of the second resistor and the error amplifier, and the other end of the second resistor is connected to the second output end of the power circuit.

[0023] In some embodiments, the error amplifier circuit includes:

[0024] A third resistor, a fourth resistor, and an error amplifier;

[0025] One end of the third resistor is connected to the inverting input terminal of the error amplifier, the other end of the third resistor is connected to the output terminal of the error amplifier, one end of the fourth resistor is connected to the sampling circuit, the other end of the fourth resistor is connected to the inverting input terminal of the error amplifier, and the non-inverting input terminal of the error amplifier is connected to the reference voltage.

[0026] In some embodiments, the comparison circuit comprises:

[0027] PWM comparator; the inverting input terminal of the PWM comparator is connected to the output terminal of the error amplifier circuit, and the non-inverting input terminal of the PWM comparator is connected to the output terminal of the sawtooth wave generator.

[0028] In some embodiments, the power circuit comprises:

[0029] Power supply, switch tube, inductor and filter capacitor;

[0030] The power supply is connected to the switching tube, one end of the inductor is connected to the switching tube, the other end of the inductor is connected to one end of the filter capacitor and serves as the first output end of the power circuit, and the other end of the filter capacitor is connected to the power supply and serves as the second output end of the power circuit.

[0031] In some embodiments, the switch tube includes:

[0032] A first switch tube and a second switch tube; the first end of the first switch tube is connected to the positive output end of the power supply, the second end of the first switch tube is connected to one end of the inductor and the first end of the second switch tube, the third end of the first switch tube is connected to the driver, the second end of the second switch tube is connected to the negative output end of the power supply, and the third end of the second switch tube is connected to the driver.

[0033] In some embodiments, the PID controller is a single chip microcomputer.

[0034] The power supply system provided in the present application includes: a PID control circuit and a voltage-controlled Buck power supply circuit; the voltage-controlled Buck power supply circuit includes a power circuit and a control circuit; the PID control circuit is used to perform PID calculation on the deviation between the set voltage and the output voltage of the voltage-controlled Buck power supply circuit to obtain a reference voltage, and output the reference voltage to the control circuit; the control circuit is used to control the conduction state of the switch tube in the power circuit according to the reference voltage and the output voltage of the voltage-controlled Buck power supply circuit to control the output of the power circuit; the output of the power circuit is used as the output of the voltage-controlled Buck power supply circuit; the power circuit is used to convert the voltage of the power supply and output it.

[0035] It can be seen that the power supply system provided in the present application uses software PID calculation to replace hardware loop compensation. The PID control circuit performs PID calculation on the set voltage and the output voltage deviation of the voltage-controlled Buck power supply circuit to obtain a reference voltage and output the reference voltage. Then, the voltage-controlled Buck power supply circuit outputs a voltage based on the reference voltage. Even when the input voltage and output current change significantly, the output voltage of the voltage-controlled Buck power supply circuit can be guaranteed to be stable, thereby improving the power supply stability and meeting the requirements of reflow soldering detection components. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the prior art and the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A schematic diagram of a power supply system provided in an embodiment of the present application;

[0038] Figure 2 A schematic diagram of a PID control circuit provided in an embodiment of the present application;

[0039] Figure 3 A system block diagram provided for an embodiment of the present application;

[0040] Figure 4 Another system block diagram provided for an embodiment of the present application;

[0041] Figure 5 A schematic diagram of a voltage-controlled Buck power supply circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] The core of this application is to provide a power supply system that uses software PID calculation instead of hardware loop compensation to ensure output voltage stability and meet the needs of reflow soldering detection components.

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0044] In order to make the stability and response speed of the entire system of the voltage-controlled Buck power supply circuit meet the actual needs of the detection component, it is necessary to design loop compensation to compensate the system by adding zeros and poles. However, it is difficult to design hardware loop compensation, which results in the working performance of the voltage-controlled Buck power supply circuit being unable to meet the needs of the reflow soldering detection component. In view of this, in order to solve the above-mentioned technical defects, the present application provides a power supply system that uses software PID (Proportional Integral Derivative) calculation to replace hardware loop compensation, which can ensure the output voltage stability of the voltage-controlled Buck power supply circuit, improve the power supply stability, and meet the needs of the reflow soldering detection component.

[0045] Please refer to Figure 1 , Figure 1 A schematic diagram of a power supply system provided in an embodiment of the present application, referring to Figure 1 As shown, the power supply system includes:

[0046] A PID control circuit 10 and a voltage-controlled Buck power supply circuit 20; the voltage-controlled Buck power supply circuit 20 includes a power circuit 202 and a control circuit 201;

[0047] The PID control circuit 10 is used to perform PID calculation on the deviation between the set voltage and the output voltage of the voltage-controlled Buck power supply circuit 20 to obtain a reference voltage, and output the reference voltage to the control circuit 201;

[0048] The control circuit 201 is used to control the conduction state of the switch tube in the power circuit 202 according to the reference voltage and the output voltage of the voltage-controlled Buck power supply circuit 20, so as to control the output of the power circuit 202; the output of the power circuit 202 serves as the output of the voltage-controlled Buck power supply circuit 20;

[0049] The power circuit 202 is used to convert the voltage of the power supply and output it.

[0050] In this embodiment, a PID control circuit 10 is provided to replace the hardware loop compensation. The PID control circuit 10 performs PID calculation on the deviation of the set voltage and the output voltage of the voltage-controlled Buck power supply circuit 20 to obtain a reference voltage, and outputs the reference voltage to the control circuit 201 in the voltage-controlled Buck power supply circuit 20. The control circuit 201 in the voltage-controlled Buck power supply circuit 20 controls the conduction state of the switch tube in the power circuit 202 in the voltage-controlled Buck power supply circuit 20 according to the output of the PID control circuit 10, thereby controlling the output of the power circuit 202. Among them, the power circuit 202 is responsible for voltage conversion and output of the voltage of the power supply, and the output of the power circuit 202 is used as the output of the voltage-controlled Buck circuit.

[0051] The working process of the power supply system is to set the voltage and output voltage Compare to get the deviation signal , deviation signal After the PID control circuit 201, the compensation signal is obtained That is, the reference voltage, the voltage-controlled Buck power supply circuit 20 outputs the voltage according to the compensation signal. The output of the voltage-controlled Buck power supply circuit 20 can be changed to achieve loop compensation.

[0052] In some embodiments, the PID control circuit 10 includes:

[0053] PID controller, digital-to-analog conversion device;

[0054] The PID controller is used to perform analog-to-digital conversion on the output voltage of the voltage-controlled Buck power supply circuit 20 to obtain an output voltage in the form of a digital signal, perform PID calculation on the deviation between the set voltage and the output voltage in the form of the converted digital signal, and output a PWM signal;

[0055] The digital-to-analog conversion device is used to perform digital-to-analog conversion on the PWM signal, and output a reference voltage in the form of an analog signal obtained by the conversion to the voltage-controlled Buck power supply circuit 20 .

[0056] In some embodiments, the PID controller is a single chip microcomputer.

[0057] refer to Figure 2As shown, the STM32F407 microcontroller is used as a PID controller, and the PID algorithm is used to perform PID calculation on the deviation of the set voltage and the output voltage of the voltage-controlled Buck power supply circuit 20, and the duty cycle of the PWM signal output by the STM32F407 microcontroller is adjusted. The output of the STM32F407 microcontroller is converted by the digital-to-analog conversion device and then outputs the reference voltage. The input voltage Vin can be 24~48V, the output current Io can be 0~4A, and the output voltage Vo can be 20V.

[0058] In some embodiments, the PID control circuit 10 further includes:

[0059] The communication device is used to communicate with the host computer and receive the set voltage sent by the host computer.

[0060] The communication device is responsible for communicating with the host computer. The host computer sends instructions through communication to set the output voltage.

[0061] In some embodiments, the control circuit 201 includes:

[0062] Sampling circuit, error amplifier circuit, comparison circuit, driver;

[0063] The sampling circuit is used to sample the output voltage of the voltage-controlled Buck power supply circuit 20;

[0064] The error amplifier circuit is used to compare the output voltage of the voltage-controlled Buck power supply circuit 20 with the reference voltage, and to amplify the deviation between the output voltage of the voltage-controlled Buck power supply circuit 20 and the reference voltage;

[0065] The comparison circuit is used to compare the output of the error amplifier with the output of the sawtooth wave generator;

[0066] The driver is used to control the switch tube in the power circuit 202 according to the output of the comparison circuit.

[0067] The sampling circuit and the error amplifier circuit form a compensation network.

[0068] The system block diagram of the voltage-controlled Buck power supply circuit 20 is as follows: Figure 3 As shown, Figure 3 middle is the transfer function of the compensation network, is the transfer function of the comparison circuit, is the transfer function of the power circuit 202, is the transfer function of the sampling circuit.

[0069] Therefore, the open-loop transfer function of the system is as follows:

[0070] .

[0071] Due to the new process requirements of the reflow soldering equipment, the power supply requirements for the detection components are that the system gain should be as high as possible under low frequency conditions, and the system phase margin should be greater than 45°, so the above system cannot meet the new process requirements. To this end, this embodiment adds a PID control circuit 10 to compensate the system to meet the new process standards and improve the dynamic response of the system.

[0072] After adding the PID control circuit 10, the power system block diagram is as follows Figure 4 As shown, the open-loop transfer function of the power system is As shown below:

[0073] .

[0074] is the transfer function of the PID control circuit 10, is the set voltage input transfer function, is the transfer function of the output voltage, is the transfer function of the compensation network, is the transfer function of the comparison circuit, is the transfer function of the power circuit 202, is the transfer function of the sampling circuit.

[0075] Through MATLAB simulation, it can be determined that the gain margin of the power supply system after adding the PID control circuit 201 is infinite, which meets the actual process requirements. The new process requirements are greater than 10 dB, and there is sufficient gain margin; the phase margin is 78.5°, which is greater than the new process requirement of greater than or equal to 45°, and there is sufficient phase margin. In addition, the system has sufficient bandwidth after adding the PID control circuit 201. This shows that after adding the PID control circuit 201, the power supply system can quickly respond to changes in load and input voltage, improve the stability of the power supply system, and achieve the design goals of the new reflow soldering process.

[0076] refer to Figure 5 As shown, in some embodiments, the sampling circuit includes:

[0077] A first resistor R1 and a second resistor R2; one end of the first resistor R1 is connected to the first output end of the power circuit 202, the other end of the first resistor R1 is connected to one end of the second resistor R2 and the error amplifier, and the other end of the second resistor R2 is connected to the second output end of the power circuit 202.

[0078] In some embodiments, the error amplifier circuit includes:

[0079] A third resistor R3, a fourth resistor R4, and an error amplifier;

[0080] One end of the third resistor R3 is connected to the inverting input terminal of the error amplifier, the other end of the third resistor R3 is connected to the output terminal of the error amplifier, one end of the fourth resistor R4 is connected to the sampling circuit, the other end of the fourth resistor R4 is connected to the inverting input terminal of the error amplifier, and the non-inverting input terminal of the error amplifier is connected to the reference voltage.

[0081] In some embodiments, the comparison circuit comprises:

[0082] PWM comparator; the inverting input terminal of the PWM comparator is connected to the output terminal of the error amplifier circuit, and the non-inverting input terminal of the PWM comparator is connected to the output terminal of the sawtooth wave generator.

[0083] In some embodiments, the power circuit 202 includes:

[0084] Power supply Vg, switch tube, inductor L and filter capacitor C;

[0085] The power supply Vg is connected to the switching tube, one end of the inductor L is connected to the switching tube, the other end of the inductor L is connected to one end of the filter capacitor C and serves as the first output end of the power circuit 202, and the other end of the filter capacitor C is connected to the power supply Vg and serves as the second output end of the power circuit 202.

[0086] In some embodiments, the switch tube includes:

[0087] A first switch tube T1 and a second switch tube T2; a first end of the first switch tube T1 is connected to the positive output end of the power supply Vg, a second end of the first switch tube T1 is connected to one end of the inductor L and a first end of the second switch tube T2, a third end of the first switch tube T1 is connected to a driver, a second end of the second switch tube T2 is connected to the negative output end of the power supply Vg, and a third end of the second switch tube T2 is connected to the driver.

[0088] Figure 5 Where Rc represents the series equivalent resistance of the filter capacitor C, R L Indicates load.

[0089] The output voltage sampled by the sampling circuit composed of the first resistor R1 and the second resistor R2 is input to the error amplifier. The error amplifier compares the sampled output voltage with the reference voltage, amplifies the deviation between the sampled output voltage and the reference voltage, and outputs it to the PWM comparator. The PWM comparator compares the output of the error amplifier with the output of the sawtooth wave generator. The sawtooth wave generator outputs a sawtooth wave. The driver controls the first switch tube T1 and the second switch tube T2 according to the output of the PWM comparator, thereby realizing the control of the output voltage of the voltage-controlled Buck power supply circuit 20.

[0090] The first switch tube T1 and the second switch tube T2 can be NMOS tubes. The first end of the first switch tube T1 and the first end of the second switch tube T2 are drains of the NMOS tube, the second end of the first switch tube T1 and the second end of the second switch tube T2 are sources of the NMOS tube, and the third end of the first switch tube T1 and the third end of the second switch tube T2 are gates of the NMOS tube. That is, the drain of the first switch tube T1 is connected to the positive output end of the power supply Vg, the source of the first switch tube T1 is connected to one end of the inductor L and the drain of the second switch tube T2, the gate of the first switch tube T1 is connected to the driver, the drain of the second switch tube T2 is connected to the negative output end of the power supply Vg, and the gate of the second switch tube T2 is connected to the driver. The driver controls the first switch tube T1 to turn on or off by controlling the voltage of the gate of the first switch tube T1. The driver controls the second switch tube T2 to turn on or off by controlling the voltage of the gate of the second switch tube T2.

[0091] To summarize, the power supply system provided in the present application uses software PID calculation to replace hardware loop compensation. The PID control circuit performs PID calculation on the set voltage and the output voltage deviation of the voltage-controlled Buck power supply circuit to obtain a reference voltage and output the reference voltage. Then, the voltage-controlled Buck power supply circuit outputs a voltage based on the reference voltage. Even when the input voltage and output current change significantly, the output voltage of the voltage-controlled Buck power supply circuit can be guaranteed to be stable, thereby improving the power supply stability and meeting the requirements of reflow soldering detection components.

[0092] Because the situation is complicated, it is impossible to list them one by one for explanation. Those skilled in the art should be aware that there may be multiple examples based on the basic principles of the embodiments provided by the present invention and in combination with actual conditions, and all of them should be within the scope of the present invention without paying enough creative work.

[0093] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0094] The power supply system provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0095] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

Claims

1. A power supply system, characterized in that: include: PID control circuit and voltage-controlled Buck power supply circuit; the voltage-controlled Buck power supply circuit includes a power circuit and a control circuit; The PID control circuit is used to perform PID calculation on the deviation between the set voltage and the output voltage of the voltage-controlled Buck power supply circuit to obtain a reference voltage, and output the reference voltage to the control circuit; The control circuit is used to control the conduction state of the switch tube in the power circuit according to the reference voltage and the output voltage of the voltage-controlled Buck power circuit, so as to control the output of the power circuit; the output of the power circuit serves as the output of the voltage-controlled Buck power circuit; The power circuit is used to convert the voltage of the power supply and output it.

2. The power supply system according to claim 1, characterized in that: The PID control circuit comprises: PID controller, digital-to-analog conversion device; The PID controller is used to perform analog-to-digital conversion on the output voltage of the voltage-controlled Buck power supply circuit to obtain an output voltage in the form of a digital signal, perform PID calculation on the deviation between the set voltage and the output voltage in the form of the converted digital signal, and output a PWM signal; The digital-to-analog conversion device is used to perform digital-to-analog conversion on the PWM signal, and output a reference voltage in the form of an analog signal obtained by the conversion to the control circuit.

3. The power supply system according to claim 1, characterized in that: The PID control circuit also includes: The communication device is used to communicate with the host computer and receive the set voltage sent by the host computer.

4. The power supply system according to claim 1, characterized in that: The control circuit comprises: Sampling circuit, error amplifier circuit, comparison circuit, driver; The sampling circuit is used to sample the output voltage of the voltage-controlled Buck power supply circuit; The error amplifier circuit is used to compare the output voltage of the voltage-controlled Buck power supply circuit with the reference voltage, and to amplify the deviation between the output voltage of the voltage-controlled Buck power supply circuit and the reference voltage; The comparison circuit is used to compare the output of the error amplifier with the output of the sawtooth wave generator; The driver is used to control the switch tube in the power circuit according to the output of the comparison circuit.

5. The power supply system according to claim 4, characterized in that: The sampling circuit comprises: A first resistor and a second resistor; one end of the first resistor is connected to the first output end of the power circuit, the other end of the first resistor is connected to one end of the second resistor and the error amplifier, and the other end of the second resistor is connected to the second output end of the power circuit.

6. The power supply system according to claim 4, characterized in that: The error amplification circuit comprises: A third resistor, a fourth resistor, and an error amplifier; One end of the third resistor is connected to the inverting input terminal of the error amplifier, the other end of the third resistor is connected to the output terminal of the error amplifier, one end of the fourth resistor is connected to the sampling circuit, the other end of the fourth resistor is connected to the inverting input terminal of the error amplifier, and the non-inverting input terminal of the error amplifier is connected to the reference voltage.

7. The power supply system according to claim 4, characterized in that: The comparison circuit comprises: PWM comparator; the inverting input terminal of the PWM comparator is connected to the output terminal of the error amplifier circuit, and the non-inverting input terminal of the PWM comparator is connected to the output terminal of the sawtooth wave generator.

8. The power supply system according to claim 1, characterized in that: The power circuit comprises: Power supply, switch tube, inductor and filter capacitor; The power supply is connected to the switching tube, one end of the inductor is connected to the switching tube, the other end of the inductor is connected to one end of the filter capacitor and serves as the first output end of the power circuit, and the other end of the filter capacitor is connected to the power supply and serves as the second output end of the power circuit.

9. The power supply system according to claim 8, characterized in that: The switch tube comprises: A first switch tube and a second switch tube; the first end of the first switch tube is connected to the positive output end of the power supply, the second end of the first switch tube is connected to one end of the inductor and the first end of the second switch tube, the third end of the first switch tube is connected to the driver, the second end of the second switch tube is connected to the negative output end of the power supply, and the third end of the second switch tube is connected to the driver.

10. The power supply system according to claim 2, characterized in that: The PID controller is a single chip microcomputer.

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