Suspension type linear power supply control system

Abstract

The invention discloses a suspension type linear power supply control system which comprises a power supply rectification unit, an input filtering unit, a control unit, a suspension adjusting unit and a power adjusting unit. The power supply rectification unit serves as a pre-stage power supply of the power adjustment unit and the suspension adjustment unit, a power frequency transformer is adopted to provide stable bus voltage for the power adjustment unit, and a rectifier bridge is adopted to provide resonance fundamental frequency and a reference loop for the suspension adjustment unit. Loop instability caused by voltage fluctuation of a bus at the input end of an adjusting tube is greatly reduced in a mode of adjusting the output reference end of the power supply in a suspension mode; stable control of the voltage difference between the input end and the output end of the adjusting tube is realized, thereby accurately controlling the loss of the adjusting tube and improving the overall efficiency of the power supply; operation risks and safety factors are eliminated, and the reliability of the power supply is improved.

Description

Technical Field

[0001] The invention relates to a linear power supply, in particular to a suspended linear power supply control system. Background Art

[0002] As we all know, linear power supplies have the characteristics of high precision, low ripple noise, superior dynamic performance, and high stability, and are widely used in precision manufacturing and testing experiments. In recent years, with the vigorous development of the semiconductor industry, the demand for semiconductor testing and inspection, especially high-power semiconductor testing and inspection, has become increasingly urgent. The testing and inspection of semiconductors requires the test power supply to have high precision and dynamic performance, otherwise it will greatly affect the accuracy of the test and even cause damage to the device under test. Therefore, the market demand for programmable linear DC regulated power supplies, especially kilowatt power-level linear power supplies, has increased year by year. However, most of the linear DC regulated power supplies independently developed at present have low output power, and the output power of most products is at the level of hundreds of watts. The power they can provide cannot meet the growing demand for high-power testing. Generally speaking, the solution to cope with high power, especially the output power demand of more than 1000W, is to use a switching power supply with higher power density, but the switching power supply cannot meet the high precision, low output ripple noise, high-speed response and high reliability required by precision instrument manufacturing, semiconductor manufacturing and testing fields, and many precision tests and laboratories. Therefore, the development of kilowatt-level linear DC regulated power supplies has become an urgent need for high-end manufacturing and precision measurement laboratories. In recent years, more attention has been paid to the research and development and production of high-power linear DC regulated power supplies.

[0003] At present, there are many power supply manufacturers and a wide variety of power supply products, but there are not many high-precision, high-performance linear DC regulated power supplies with kilowatt power levels, and it is difficult to find high-power linear DC power supply products with an output power of more than 5000W on the market. In response to such needs, the common method people take is to incorporate a high-power high-order low-pass filter at the output end of a high-precision, high-resolution switching power supply. In this way, it can meet the application requirements of high accuracy and ripple noise but low dynamic characteristics and response speed. However, once the application requirements of high accuracy and ripple noise and high dynamic characteristics and response speed are met, the switching power supply is often unable to meet the requirements. The switching power supply has the advantages of high power density and high efficiency. By increasing the number of bits of a given reference value and signal filtering, the output accuracy, output resolution and noise level can be effectively improved. In addition, adding a filter of the corresponding order at the output end of the switching power supply and rationally designing the loop parameters can effectively suppress the output ripple noise and output stability. However, the result of doing so is often to greatly sacrifice the dynamic characteristics and response speed of the entire power supply system, and also put forward higher design requirements for reliability. Therefore, in order to meet the increasing demand for precision testing and manufacturing and avoid the material bottlenecks encountered in the development of switching power supply technology, we still need to make breakthroughs in linear power supply adjustment technology.

[0004] At present, the reason why linear power supplies cannot support high-power application needs is largely due to the large losses of linear power supplies. These losses not only generate useless work and reduce efficiency, but also virtually increase the requirements for heat dissipation and volume of the power supply. Therefore, in order to improve the efficiency of linear power supplies, we need to research and develop a control technology that uses linear adjustment output technology and can effectively improve output efficiency and reduce losses. In this context, the suspended linear power supply control technology came into being.

[0005] The so-called suspended linear power supply control technology is a design technology that controls the voltage difference between the input and output ends of the linear adjustment tube by suspending the potential of the reference end of the power supply output, while ensuring the stability of the power supply output, and then controlling the power loss of the adjustment tube, effectively improving the output efficiency. Due to the current and power dissipation limitations of a single power adjustment tube, most linear power supplies use multiple adjustment tubes in parallel to increase the output current to increase the output power. The more adjustment tubes in parallel, the greater the output power, but the greater the power loss, and the temperature of the adjustment tube rises rapidly, affecting the output stability and safety. Therefore, while increasing the number of adjustment tubes to increase the output power, it is also necessary to effectively control the power loss of each adjustment tube so that the operating temperature of each adjustment tube is kept within its normal operating temperature range. In order to increase the output power of the linear power supply and ensure the stable and reliable operation of the power supply, it is the key to study and design a control method that dynamically controls and maintains the input and output pressure difference of the adjustment tube.

[0006] Prior art 1, technical solution of gear-skipping pre-stabilization technology:

[0007] The so-called jump-shift pre-stabilization technology is a control technology that switches the input voltage of the adjustment tube in steps according to the set value or output value and stabilizes it within a certain voltage range. The technical solution is as follows:

[0008] First, read the power supply output setting value through the control terminal or detect the power supply output value through the power supply readback sampling terminal;

[0009] Afterwards, according to the set value of the power supply output or the output value of the preset gear, the controller is used to determine the voltage value and gear that the input voltage of the adjustment tube needs to be stabilized, or the comparator outputs a control signal to automatically control the gear switching;

[0010] Then, the output end of the power frequency transformer or the previous power supply is switched to the appropriate terminal through soft switching devices such as relays or thyristors, triodes, MOS tubes, etc. to switch the input voltage value of the adjustment tube, thereby achieving the purpose of controlling the voltage difference between the input and output ends of the adjustment tube.

[0011] Disadvantages of pre-stabilization technology

[0012] This power supply control technology uses constant voltage difference control, which can achieve fast and continuous adjustment of the power supply reference terminal voltage, thereby achieving constant input and output voltage difference. However, the jump gear pre-stabilization technology needs to judge the switching gear according to the set value or the read-back sampling value. Some design schemes even require the microprocessor to participate in a series of tasks such as sampling, calculation, judgment and control, and need to consider the actual switching safety issues. Therefore, it is impossible to achieve fast and continuous adjustment of the input and output voltage difference, and can only achieve low-speed input voltage gear adjustment;

[0013] This power supply control technology can achieve stable control of the voltage difference between the input and output ends of the adjustment tube through a feedback loop, while the pre-stabilization technology for skipping gears does not have a loop control mechanism, or may generate large voltage fluctuations during the gear switching process, affecting the gear voltage stability. Therefore, the stability effect of this power supply control technology is better than the pre-stabilization technology for skipping gears without feedback loop control;

[0014] This power supply control technology can achieve fine adjustment of the input-output voltage difference through feedback loop control, while the jump-shift pre-stabilization technology can only achieve coarse adjustment of the input and output within a certain voltage difference range. Therefore, the jump-shift pre-stabilization technology cannot achieve stable power consumption control, which has a certain impact on the stability of the power supply output;

[0015] Since this power supply control technology does not use switching devices such as relays, there are no unreliable factors such as output disconnection and sparking. However, the jump gear pre-stabilization technology has the risk of switching disconnection and relay sparking and damage, and its reliability is subject to certain challenges.

[0016] Prior art 2, technical solution of constant voltage difference bus voltage adjustment technology:

[0017] The so-called constant voltage difference bus voltage adjustment technology is a control technology that dynamically adjusts the bus voltage according to the voltage difference between the input and output of the adjustment tube, so that the voltage difference between the input and output of the adjustment tube is stabilized within a certain voltage range. Its technical solution is as follows:

[0018] First, a given value of the voltage difference between the input and output of the adjustment tube is set, and the actual voltage difference between the input and output of the adjustment tube is detected through the power supply sampling terminal;

[0019] Afterwards, the voltage value that the input voltage of the adjustment tube needs to be stabilized is determined according to the given value of the pressure difference between the input and output of the adjustment tube and the actual pressure difference between the input and output of the adjustment tube detected by the sampling end;

[0020] Then, the adjustment loop dynamically changes the given value of the input voltage of the adjustment tube to change the input voltage value of the adjustment tube, thereby achieving the purpose of stable control of the voltage difference between the input end and the output end of the adjustment tube.

[0021] Disadvantages of constant voltage difference bus voltage regulation technology:

[0022] Although the constant voltage difference bus voltage adjustment technology can dynamically adjust the bus voltage in real time, thereby dynamically adjusting the voltage difference between the input and output of the adjustment tube to ensure its stability, frequent adjustment of the bus voltage requires input capacitors and inductors to have a wide range of parameter adaptability, which puts forward higher requirements for input filtering and energy storage devices, otherwise it is easy to cause loop oscillation;

[0023] When the power supply responds quickly, the bus voltage adjustment speed of the constant voltage difference bus voltage adjustment technology cannot match the response speed of the output loop adjustment. If the output changes frequently and at high speed, it is easy to cause output loop oscillation and damage to the adjustment tube. Therefore, the constant voltage difference bus voltage adjustment technology can only achieve low-speed output voltage adjustment.

[0024] The constant voltage difference bus voltage adjustment technology incorporates the bus voltage into the loop control, and has high requirements for the bus voltage. If the load changes greatly, it is easy to cause large fluctuations in the bus voltage, affecting the working state of the adjustment tube, and the reliability is challenged to a certain extent.

[0025] In view of this, the present invention is proposed. Summary of the invention

[0026] The purpose of the present invention is to provide a suspended linear power supply control system to solve the above technical problems existing in the prior art.

[0027] The objective of the present invention is achieved through the following technical solutions:

[0028] The suspension linear power supply control system of the present invention comprises a power supply rectification unit, an input filtering unit, a control unit, a suspension adjustment unit and a power adjustment unit;

[0029] The power supply rectifier unit is used as the front-stage power supply of the power adjustment unit and the suspension adjustment unit, and adopts an industrial frequency transformer to provide a stable bus voltage for the power adjustment unit; and adopts a rectifier bridge to provide a resonant base frequency and a reference circuit for the suspension adjustment unit;

[0030] The input filter unit filters the input power supply for the entire control system and provides necessary energy storage for the subsequent power supply output;

[0031] The control unit includes the main output loop control of the power supply control system, and also provides the system with output setting, voltage difference control setting, voltage and current reading back and power supply protection control;

[0032] The power adjustment unit performs linear power adjustment on the input power supply so that the output is consistent with the output given value set by the control unit;

[0033] The suspension adjustment unit adjusts the potential of the suspension reference to ensure that the voltage difference between the input and output of the adjustment tube is constant when the bus voltage fluctuates or the output voltage changes.

[0034] Compared with the prior art, the suspended linear power supply control system provided by the present invention greatly reduces the loop instability caused by the bus voltage fluctuation at the input end of the adjustment tube by suspending the reference end of the adjustment power supply output; realizes the stable control of the voltage difference between the input end and the output end of the adjustment tube, thereby accurately controlling the loss of the adjustment tube and improving the overall efficiency of the power supply; eliminates the operating risks and safety factors, and improves the reliability of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A block diagram of the overall technical solution of a suspended linear power supply control system provided by an embodiment of the present invention;

[0036] Figure 2 This is the output characteristic curve of IRFP140N;

[0037] Figure 3 This is a schematic diagram of the principle of the pressure difference sampling circuit for adjusting the tube;

[0038] Figure 4 This is a schematic diagram of the error amplifier principle of the floating end adjustment loop;

[0039] Figure 5 This is a schematic diagram of the PWM drive signal generation circuit principle;

[0040] Figure 6 This is the measured waveform of the PWM drive signal output by the floating end adjustment circuit. DETAILED DESCRIPTION

[0041] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] First, the terms that may be used in this article are explained as follows:

[0043] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0044] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0045] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0046] Unless otherwise specified or limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this article can be understood according to specific circumstances.

[0047] The orientation or position relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientation or position relationship shown in the drawings and are only for the convenience and simplification of description, and do not explicitly or implicitly indicate that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation of this document.

[0048] The contents not described in detail in the examples of the present invention belong to the prior art known to professionals in the field. If no specific conditions are specified in the examples of the present invention, the conditions are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used in the examples of the present invention, they are all conventional products that can be purchased commercially.

[0049] The suspension linear power supply control system of the present invention comprises a power supply rectification unit, an input filtering unit, a control unit, a suspension adjustment unit and a power adjustment unit;

[0050] The power supply rectifier unit is used as the front-stage power supply of the power adjustment unit and the suspension adjustment unit, and uses an industrial frequency transformer to provide a stable bus voltage for the power adjustment unit; a rectifier bridge is used to provide a resonant base frequency and a reference circuit for the suspension adjustment unit;

[0051] The input filter unit filters the input power supply for the entire control system and provides necessary energy storage for the subsequent power supply output;

[0052] The control unit includes the main output loop control of the power supply control system, and also provides the system with output setting, voltage difference control setting, voltage and current reading back and power supply protection control;

[0053] The power adjustment unit performs linear power adjustment on the input power supply so that the output is consistent with the output given value set by the control unit;

[0054] The suspension adjustment unit adjusts the potential of the suspension reference to ensure that the voltage difference between the input and output of the adjustment tube is constant when the bus voltage fluctuates or the output voltage changes.

[0055] The suspension adjustment unit includes a suspension reference end adjustment circuit, the transformer and the rectifier bridge provide a resonant frequency for the suspension reference end adjustment circuit, and the potential adjustment of the suspension reference end is achieved by the following method:

[0056] The potential adjustment of the suspended reference terminal is realized in the form of a PWM switch. The adjustment circuit needs to generate a PWM wave with a certain resonant frequency. After voltage transformation and rectification, the transformer generates a voltage waveform with a frequency twice that of the industrial frequency to meet the generation of the PWM wave. The voltage pulse of this frequency is input into the monostable multivibrator to generate a pulse with a set pulse width and period. Then, the RC circuit is used to add the necessary time constant and match the parameters of R and C to form a triangular wave. The triangular wave is compared with the readback value of the pressure difference of the adjustment tube to generate a PWM wave for driving the switch adjustment tube, thereby realizing the potential adjustment of the suspended reference terminal, ensuring the stability of the pressure difference between the input and output ends of the power adjustment tube, and then controlling the loss of the power adjustment tube.

[0057] The power adjustment unit provides a resonant frequency through an industrial frequency transformer and a rectifier bridge, thereby generating a PWM wave to drive the switch MOS tube, realizing a suspended "peak shifting" power control, and further controlling the power adjustment tube loss;

[0058] The voltage difference between the input and output ends of the MOS tube is greater than the sum of the drain saturation voltage and the gate-source voltage to ensure that the linear adjustment tube works stably. At this time, the MOS tube can be ensured to work stably in the saturation region without causing output oscillation due to cross-region operation.

[0059] During the design, the current value that needs to flow through each MOS tube is estimated based on the maximum current value output by the power system. In order to ensure the stability of the power system, a certain margin is left for the design current of the power adjustment tube;

[0060] Use a parallel voltage regulator as a given signal source, and reasonably design the pressure difference between the input and output ends of the MOS tube, so that a certain margin is left between the actual working pressure difference and the critical saturation area of ​​the adjustment tube. After the pressure difference is determined, the given setting value of the suspension adjustment feedback loop is also determined accordingly;

[0061] In the sampling circuit design of the voltage difference between the input and output ends of the MOS tube, a differential amplifier is used as the sampling front-end amplifier to improve the stability and accuracy of the suspended reference end adjustment loop.

[0062] The system adopts the isolation control method of the front and rear loop signals to achieve the reliability and safety of the device;

[0063] The system adopts the power frequency transformer and rectifier solution in the front stage, so that the entire suspension end adjustment loop does not involve inductive components and transformers. The power frequency transformer only provides energy and resonant frequency for the system, but does not actually participate in the loop control and will not generate additional zero poles.

[0064] The adjustment of the floating end of the system's rear stage is achieved through PWM switch adjustment. The "DRIVE" signal does not directly drive the linear adjustment tube to achieve the potential adjustment of the floating end. The purpose of this design is to reduce the loss caused by the linear adjustment tube in the process of adjusting the potential of the floating end. Therefore, it is necessary to apply the resonant triangular wave generation circuit mentioned above to achieve it. By comparing the resonant triangular wave with the drive signal "DRIVE" after the pressure difference of the adjustment tube is read back and corrected by the error amplifier, a PWM wave for actually driving the switch adjustment tube can be generated. The PWM wave can generate PWM waves with different duty cycles according to the level of the "DRIVE" signal, thereby realizing the pulse width control of the switch adjustment tube and realizing the potential adjustment of the floating reference end.

[0065] In summary, the suspended linear power supply control system of the embodiment of the present invention:

[0066] The loop instability caused by bus voltage fluctuation at the input end of the adjustment tube is greatly reduced by adjusting the reference end of the power supply output through suspension.

[0067] The voltage difference between the input and output ends of the adjustment tube is stably controlled, thereby accurately controlling the loss of the adjustment tube and improving the overall efficiency of the power supply.

[0068] It eliminates operational risks and safety factors and improves the reliability of power supply.

[0069] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the embodiments of the present invention are described in detail with specific embodiments below.

[0070] Example 1

[0071] like Figures 1 to 6 As shown:

[0072] The technical solution of the present invention has been applied to the latest developed linear power supply products, whose output power is currently 1000W at the lowest and 5000W at the highest, and has formed a series of experimental products within the above power range. MOS tube IRFP140N is used as the linear power adjustment tube in the design.

[0073] like Figure 1 As shown, this is the overall technical solution block diagram of this control technology.

[0074] The main functional units involved in this control technology are five parts: power supply rectifier unit, input filter unit, control unit, suspension adjustment unit and power adjustment unit. The power supply rectifier unit, as the front-stage power supply of the power adjustment unit and the suspension adjustment unit, provides stable power input for the entire system. The power supply rectifier unit in this scheme adopts the scheme of traditional industrial frequency transformer and rectifier bridge, which provides stable bus voltage for the power adjustment unit and resonant base frequency and reference circuit for the suspension adjustment unit; the input filter unit filters the input power supply for the entire control system, making the input power supply waveform smoother and more stable, reducing bus voltage fluctuations, and improving the stability of the entire system loop. In addition, the unit also provides necessary energy storage for the output of the subsequent power supply, so as to better cope with high-response applications; the control unit includes the main output loop control of this power control system, and also provides the system with output setting, voltage difference control setting, voltage and current reading back and power protection control; the power adjustment unit performs power linear adjustment on the input power supply, so that the output is consistent with the output setting value set by the control unit; the suspension adjustment unit adjusts the potential of the suspension reference to meet the constant voltage difference between the input and output of the adjustment tube when the bus voltage fluctuates or the output voltage changes.

[0075] The suspension adjustment unit is the core part of this control technology. The following mainly describes the implementation of this unit in detail:

[0076] The power supply rectifier unit provides the prerequisite for energy and PWM adjustment for the suspension adjustment unit. This control technology adopts the traditional linear power supply front-stage solution of industrial frequency transformer plus rectifier bridge. In this solution, the transformer and rectifier bridge not only have the functions of energy supply, voltage conversion and rectification, but also provide the resonant frequency for the suspension reference end adjustment circuit. Since the potential adjustment of the suspension reference end in this solution is realized in the form of PWM switch, the adjustment circuit needs to generate a PWM wave with a certain resonant frequency. After voltage transformation and rectification, the transformer generates a voltage waveform with a frequency of 2 times the industrial frequency to meet the generation of PWM wave. The voltage pulse of this frequency is input into the monostable multivibrator to generate a pulse with a set pulse width and period, and then the RC circuit is used to add the necessary time constant and match the parameters of R and C to form a triangular wave. The triangular wave is compared with the readback value of the adjustment tube pressure difference to generate a PWM wave for driving the switch adjustment tube, realize the potential adjustment of the suspension reference end, and then ensure the stability of the pressure difference between the input and output ends of the power adjustment tube.

[0077] The power adjustment unit is the core part of the entire power supply system. Its device characteristics and working principles are closely related to the implementation of this technology. From the theory, it can be known that the stable operation of the MOS tube is closely related to the drain saturation voltage of the MOS tube. The drain saturation voltage (drain saturation voltage, Vdsat) refers to the Vds value corresponding to the moment when the drain current of the transistor begins to not change with the change of Vds. Vdsat is not an actual voltage value of the transistor, but is only used to judge the margin reference value of the critical distance from the saturation region. In any case, the relationship between Vds and Vdsat is an important basis for judging whether the MOS tube works in the saturation region. Therefore, to ensure the stable operation of the linear adjustment tube, it is necessary to ensure that the voltage difference between its input and output terminals is greater than the sum of the drain saturation voltage and the gate-source voltage, that is, Vds (min) ≥ Vdsat + Vgs. At this time, the MOS tube can be guaranteed to work stably in the saturation region, and the output oscillation will not be caused by cross-region. During design, the current value that needs to flow through each power tube can be estimated based on the maximum current value output by the power supply system. In order to ensure the stability of the power supply system, a certain margin should be left for the design current of the power adjustment tube in the actual design.

[0078] like Figure 2 As shown in the figure, it is the output characteristic curve of IRFP140N. For example, the design current of each power adjustment tube is 7.5A. From the output characteristic curve, it can be seen that the drain saturation voltage of IRFP140N is about 1V when the drain current is 7.5A, and its Vgs turn-on voltage is at least 2V. Therefore, we only need to ensure that the Vds value is greater than 3V to ensure that the power tube can work stably in its saturation region. Since Vdsat and Vgs will vary within a certain range and are not a fixed value, in order to ensure that all tubes can work stably, considering the universality of the loop given voltage regulator tube parameter selection and the power loss of the adjustment tube, it is necessary to reasonably design the voltage difference between the input and output ends of the adjustment tube, so that the actual working voltage difference and the critical saturation region of the adjustment tube have a certain margin. After the voltage difference is determined, the given setting value of the suspension adjustment feedback loop is also determined. Since we do not need to precisely control the loss of each power regulating tube, the voltage difference between the input and output ends of the power regulating tube does not need to be highly unified. It is sufficient to ensure that the voltage difference is stable. We can consider using a parallel-type voltage regulator as the core component of a given signal source, and there is no need to control the parameter accuracy of the RC circuit. This can make the entire solution simple, reliable and reduce costs.

[0079] In order to improve the stability and accuracy of the suspended reference end adjustment loop, a differential amplifier is used as the sampling front-end amplifier in the sampling circuit design of the voltage difference between the input and output ends of the adjustment tube. It is well known that the differential amplifier can effectively suppress common-mode interference. In addition, the output stability of the error amplifier can be further improved by selecting an operational amplifier with low temperature error in the design. The temperature error is mainly reflected in the influence of temperature on the input offset voltage, and the greater the gain, the more obvious the error. Therefore, in order to improve stability, the voltage gain should be minimized in the design and devices with small offset voltage temperature error should be selected.

[0080] like Figure 3 As shown, it is a schematic diagram of the principle of the voltage difference sampling circuit of the adjustment tube, and the output "BACK" is a read-back single-ended signal of the input and output voltage difference of the power adjustment tube.

[0081] Another advantage of using an industrial frequency transformer and rectifier in the front-end solution of the power supply system is that such a design does not involve inductive components and transformers in the entire floating end adjustment loop. The industrial frequency transformer only provides energy and resonant frequency for the system, but does not actually participate in the loop control and will not generate additional zeros and poles. Therefore, the floating reference end adjustment loop only needs to use a type I error amplifier to meet the design requirements, without using relatively more complex type II and type III error amplifiers. This not only facilitates debugging, but also helps to reduce development and production costs.

[0082] like Figure 4 As shown, it is a schematic diagram of the error amplifier principle of the floating end adjustment loop, and the output "DRIVE" is the power adjustment tube drive level signal.

[0083] In practical applications, the adjustment of the floating end is generally achieved through PWM switch adjustment. The "DRIVE" signal does not directly drive the linear adjustment tube to achieve the potential adjustment of the floating end. The purpose of this design is to reduce the loss caused by the linear adjustment tube in the process of adjusting the potential of the floating end. Therefore, it is necessary to apply the resonant triangular wave generation circuit mentioned above to achieve it. The resonant triangular wave is compared with the drive signal "DRIVE" after the pressure difference of the adjustment tube is read back and corrected by the error amplifier to generate a PWM wave for actually driving the switch adjustment tube. The PWM wave can generate PWM waves with different duty cycles according to the level of the "DRIVE" signal, thereby realizing the pulse width control of the switch adjustment tube and realizing the potential adjustment of the floating reference end.

[0084] like Figure 5 As shown in FIG. 1 , it is a schematic diagram of the principle of the PWM drive signal generation circuit, and “DRIVE_MOS” is the PWM signal that drives the switch adjustment tube.

[0085] At present, this technology has gone through multiple verification links such as circuit simulation and circuit measurement. In practical applications, it is necessary to optimize the details of the circuit locally, such as parameter adjustment and matching of the RC circuit, optimization adjustment of the triangle wave amplitude, optimization adjustment of the suspension control loop parameters, etc., and fine-tuning is required according to the actual situation of the circuit application. In addition, physical isolation should be performed when necessary to achieve suspension adjustment and ensure safety.

[0086] like Figure 6 As shown, it is the measured waveform of the PWM drive signal output by the floating end adjustment circuit.

[0087] Beneficial effects brought by the technical solution of the present invention:

[0088] This control technology uses the power frequency transformer as the starting point for resonance generation. It can generate the resonant frequency for the floating reference end switch adjustment without additional circuits. At the same time, it can make full use of the phase difference between the output voltage and current of the power frequency transformer to effectively control the peak loss of the adjustment tube.

[0089] Compared with the previous scheme of adjusting the voltage drop of the power tube in real time, this technical scheme adopts the method of controlling the reference end of the power supply output instead of directly adjusting the bus voltage, which effectively reduces the risk of loop oscillation, reduces the difficulty of loop parameter matching in the design, and improves the stability of the power supply system;

[0090] This control technology adopts an automatic loop control scheme of presetting and real-time acquisition of the input and output pressure difference of the adjustment tube, which not only realizes the fast and stable control of the input and output pressure difference of the adjustment tube, but also realizes the continuous adjustment of the input voltage of the adjustment tube through a purely analog real-time control scheme, thereby reducing the power loss of the power adjustment tube and improving the output power of the linear power supply;

[0091] Compared with the previous pressure difference control scheme, this control technology adopts the scheme of controlling the floating potential of the reference end, without the need to modulate, switch or switch the previous stage output. Therefore, there is no need to use physical switch control devices such as relays and circuit breakers, which effectively avoids unsafe factors such as relay circuit breaking and sparking, and ensures the safety and reliability of the system.

[0092] In specific implementation:

[0093] This control technology can use power devices such as bipolar transistors or IGBTs to replace the switch adjustment MOS tube in this solution to achieve control of the reference end floating potential, thereby achieving control of the constant voltage difference between the input and output ends of the adjustment tube, but its fundamental principle is basically the same as this solution;

[0094] This control technology can use power devices such as bipolar transistors or IGBTs to replace the power adjustment MOS tube in this solution to control the power supply output voltage and current, but its fundamental principle is basically the same as this solution;

[0095] This control technology can use DAC or reference source to replace the design scheme of setting the pressure difference set value of the voltage regulator tube and RC circuit in this scheme to achieve accurate pressure difference setting, but this part is not the core of this technology, and its fundamental principle is basically the same as this scheme;

[0096] This control technology can use self-excited oscillation to generate resonant frequency, but its phase needs to be controlled. The complexity is higher than this solution, but its fundamental principle is basically the same as this solution.

[0097] What are the key technical points and the points to be protected in this invention?

[0098] The key technical points and pre-protection points of the present invention are the following three points:

[0099] The power reference terminal is dynamically suspended to control the voltage difference between the input and output of the linear power adjustment tube, thereby controlling the power adjustment tube loss.

[0100] The power frequency transformer and rectifier bridge are used to provide the resonant frequency, thereby generating a PWM wave to drive the switch MOS tube, realizing the suspended "peak shifting" power control, and further controlling the power adjustment tube loss;

[0101] The potential of the power reference terminal is controlled by PWM switch adjustment, which reduces the control loss.

[0102] The isolation control scheme of the front and rear loop signals is adopted to ensure the reliability and safety of the device.

[0103] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A suspended linear power supply control system, characterized in that: It includes a power supply rectifier unit, an input filter unit, a control unit, a suspension adjustment unit and a power adjustment unit; The power supply rectifier unit is used as the front-stage power supply of the power adjustment unit and the suspension adjustment unit, and uses an industrial frequency transformer to provide a stable bus voltage for the power adjustment unit; a rectifier bridge is used to provide a resonant base frequency and a reference circuit for the suspension adjustment unit; The input filter unit filters the input power supply for the entire control system and provides necessary energy storage for the subsequent power supply output; The control unit includes the main output loop control of the power supply control system, and also provides the system with output setting, voltage difference control setting, voltage and current reading back and power supply protection control; The power adjustment unit performs linear power adjustment on the input power supply so that the output is consistent with the output given value set by the control unit; The suspension adjustment unit adjusts the potential of the suspension reference to ensure that the voltage difference between the input and output of the adjustment tube is constant when the bus voltage fluctuates or the output voltage changes.

2. The suspended linear power supply control system according to claim 1, characterized in that: The suspension adjustment unit includes a suspension reference end adjustment circuit, the transformer and the rectifier bridge provide a resonant frequency for the suspension reference end adjustment circuit, and the potential adjustment of the suspension reference end is achieved by the following method: The potential adjustment of the suspended reference terminal is realized in the form of a PWM switch. The adjustment circuit needs to generate a PWM wave with a certain resonant frequency. After voltage transformation and rectification, the transformer generates a voltage waveform with a frequency twice that of the industrial frequency to meet the generation of the PWM wave. The voltage pulse of this frequency is input into the monostable multivibrator to generate a pulse with a set pulse width and period. Then, the RC circuit is used to add the necessary time constant and match the parameters of R and C to form a triangular wave. The triangular wave is compared with the readback value of the pressure difference of the adjustment tube to generate a PWM wave for driving the switch adjustment tube, thereby realizing the potential adjustment of the suspended reference terminal, ensuring the stability of the pressure difference between the input and output ends of the power adjustment tube, and then controlling the loss of the power adjustment tube.

3. The suspended linear power supply control system according to claim 2, characterized in that: The power adjustment unit provides a resonant frequency through an industrial frequency transformer and a rectifier bridge, thereby generating a PWM wave to drive the switch MOS tube, thereby realizing a suspended "peak shifting" power control, and further controlling the power adjustment tube loss; The voltage difference between the input and output ends of the MOS tube is greater than the sum of the drain saturation voltage and the gate-source voltage to ensure that the linear adjustment tube works stably. At this time, the MOS tube can be ensured to work stably in the saturation region without causing output oscillation due to cross-region operation. During the design, the current value that needs to flow through each MOS tube is estimated based on the maximum current value output by the power system. In order to ensure the stability of the power system, a certain margin is left for the design current of the power adjustment tube; Use a parallel voltage regulator as a given signal source, and reasonably design the pressure difference between the input and output ends of the MOS tube, so that a certain margin is left between the actual working pressure difference and the critical saturation area of ​​the adjustment tube. After the pressure difference is determined, the given setting value of the suspension adjustment feedback loop is also determined accordingly; In the sampling circuit design of the voltage difference between the input and output ends of the MOS tube, a differential amplifier is used as the sampling front-end amplifier to improve the stability and accuracy of the suspended reference end adjustment loop.

4. The suspended linear power supply control system according to claim 3, characterized in that: The system adopts the isolation control method of the front and rear loop signals to achieve the reliability and safety of the device; The system adopts the power frequency transformer and rectifier solution in the front stage, so that the entire suspension end adjustment loop does not involve inductive components and transformers. The power frequency transformer only provides energy and resonant frequency for the system, but does not actually participate in the loop control and will not generate additional zero poles. The adjustment of the system's rear-stage floating end is achieved through PWM switch adjustment. The "DRIVE" signal does not directly drive the linear adjustment tube to achieve the potential adjustment of the floating end. The purpose of this design is to reduce the loss caused by the linear adjustment tube in the process of adjusting the potential of the floating end. Therefore, it is necessary to apply the resonant triangular wave generation circuit mentioned above to achieve this. By comparing the resonant triangular wave with the drive signal "DRIVE" after the adjustment tube pressure difference is read back and corrected by the error amplifier, a PWM wave for actually driving the switch adjustment tube can be generated. This PWM wave can generate PWM waves with different duty cycles according to the level of the "DRIVE" signal, thereby realizing the pulse width control of the switch adjustment tube and realizing the potential adjustment of the floating reference end.

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