LDO positive and negative voltage conversion circuit based on discrete device and motor driving system
By using an LDO positive-negative voltage conversion circuit based on discrete devices and utilizing voltage stabilizing and voltage dividing components as well as feedback regulating components, the problems of large circuit size, high cost and low output power in the existing technology are solved, and higher output power and stability are achieved, making it suitable for motor drive systems.
Patent Information
- Application Number
- CN202422581317.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-23
- Publication Date
- 2025-10-17
- Estimated Expiration
- 2034-10-23
AI Technical Summary
In the prior art, circuits that achieve positive and negative voltage outputs require additional integrated chips and complex control mechanisms, which results in increased circuit size, increased costs, and low output power, which cannot meet high-power requirements.
An LDO positive and negative voltage conversion circuit based on discrete devices is adopted, and voltage conversion is performed using voltage stabilizing components, voltage divider components and feedback adjustment components. The LDO positive and negative voltage conversion units composed of discrete components provide positive and negative polarity target output voltages respectively, and feedback adjustment components are used to ensure voltage stability.
It reduces design complexity and cost, improves output power and voltage stability, meets high power requirements, and the discrete devices have good heat dissipation and can output greater power.
Smart Images
Figure CN223451829U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to electronic circuit technical field especially is related to a LDO positive and negative voltage conversion circuit and motor drive system based on discrete device. BACKGROUND
[0002] In modern electronic equipment, positive and negative voltage conversion circuit is used for converting single DC power voltage into positive and negative bipolar voltage to support the operation demand of various circuit modules. The conventional low dropout regulator (LDO) is usually used to provide stable DC power voltage.
[0003] Most of the circuits for realizing positive and negative voltage output currently need to add integrated chips on the basis of LDO, such as using LM27762 to convert positive and negative voltage, and the realization method is to add switching signal and charge pump to output positive and negative voltage at the same time. But the generation of positive and negative voltage needs additional circuit components and complex control mechanism, which leads to the increase of circuit size and cost, and may affect the energy efficiency of the whole system, resulting in low output power and not meeting the demand of high power.
[0004] Therefore, it is an urgent problem to reduce system cost, improve stability and reliability. INVENTION CONTENTS
[0005] The utility model aims at providing a LDO positive and negative voltage conversion circuit and motor drive system based on discrete device to reduce cost, improve output power and stability.
[0006] In the first aspect, a LDO positive and negative voltage conversion circuit based on discrete device is provided, comprising: a power supply, an LDO positive voltage conversion unit and an LDO negative voltage conversion unit, wherein:
[0007] The power supply is used to provide DC input voltage for the LDO positive voltage conversion unit and the LDO negative voltage conversion unit respectively;
[0008] The LDO positive voltage conversion unit and the LDO negative voltage conversion unit are both composed of several discrete devices, and the discrete devices at least include voltage stabilizing device, voltage dividing device and feedback adjusting device. The voltage stabilizing device is used to provide reference voltage, the voltage dividing device is used to adjust DC input voltage to target output voltage according to reference voltage and preset voltage dividing ratio, and the feedback adjusting device is used to adjust output voltage to target output voltage according to the error between actual output voltage and target output voltage. Wherein, the feedback adjusting device in the LDO positive voltage conversion unit is positive feedback adjusting device, and the target output voltage is positive polarity target output voltage; the feedback adjusting device in the LDO negative voltage conversion unit is negative feedback adjusting device, and the target output voltage is negative polarity target output voltage.
[0009] Optionally, the voltage stabilizing component is at least one of a voltage stabilizing diode and a discrete switch voltage regulator.
[0010] Optionally, the voltage dividing component is at least one of a voltage dividing resistor and a potentiometer.
[0011] Optionally, the LDO positive voltage converting unit and the LDO negative voltage converting unit each further comprise a current limiting component for providing a reference current for the voltage stabilizing component, and the current limiting component is at least one of a current limiting resistor and a current limiting diode.
[0012] Optionally, the positive feedback adjusting component is composed of two symmetrical signal type NPN bipolar transistors and a power type PNP bipolar transistor; the two symmetrical signal type NPN bipolar transistors are used to compare the error size of the actual output voltage and the positive polarity target output voltage, and the power type PNP bipolar transistor is used to adjust the positive output voltage to the positive polarity target output voltage according to the error size.
[0013] Optionally, the negative feedback adjusting component is composed of two symmetrical signal type PNP bipolar transistors and a power type NPN bipolar transistor; the two symmetrical signal type PNP bipolar transistors are used to compare the error size of the actual output voltage and the negative polarity target output voltage, and the power type NPN bipolar transistor is used to adjust the negative output voltage to the negative polarity target output voltage according to the error size.
[0014] Optionally, the LDO positive voltage converting unit comprises a first voltage stabilizing tube Z1, a first current limiting resistor R1, a second current limiting resistor R2, a power type PNP transistor Q1, a first signal type NPN transistor Q2, a second signal type NPN transistor Q3, a first voltage dividing resistor R3, a second voltage dividing resistor R4, and a first resistor R5; the positive pole of the power supply is connected to the emitter of the power type PNP transistor Q1, the first end of the first current limiting resistor R1, and the first end of the second current limiting resistor R2; the base of the power type PNP transistor Q1 is connected to the second end of the second current limiting resistor R2 and the collector of the first signal type NPN transistor Q2; the collector of the power type PNP transistor Q1, the collector of the second signal type NPN transistor Q3, and the first end of the first voltage dividing resistor R3 are connected to the positive output terminal VCC; the second end of the first current limiting resistor R1 is connected to the base of the first signal type NPN transistor Q2 and the cathode of the first voltage stabilizing tube Z1; the emitters of the first signal type NPN transistor Q2 and the second signal type NPN transistor Q3 are connected to the first end of the first resistor R5; the base of the second signal type NPN transistor Q3 is connected to the second end of the first voltage dividing resistor R3 and the first end of the second voltage dividing resistor R4; the second end of the first resistor R5, the anode of the first voltage stabilizing tube Z1, and the second end of the second voltage dividing resistor R4 are connected to the ground GND.
[0015] Optionally, the LDO negative voltage conversion unit comprises a second stabilizing tube Z2, a third current-limiting resistor R7, a fourth current-limiting resistor R8, a power NPN transistor Q6, a first signal PNP transistor Q4, a second signal PNP transistor Q5, a third voltage dividing resistor R9, a fourth voltage dividing resistor R10 and a second resistor R6; the negative pole of the power supply is connected to the emitter of the power NPN transistor Q6, the first end of the third current-limiting resistor R7 and the first end of the fourth current-limiting resistor R8; the base of the power NPN transistor Q6 is connected to the second end of the fourth current-limiting resistor R8 and the collector of the first signal PNP transistor Q4; the second end of the third current-limiting resistor R7 is connected to the anode of the second stabilizing tube Z2 and the base of the first signal PNP transistor Q4; the emitters of the first signal PNP transistor Q4 and the second signal PNP transistor Q5 are connected to the first end of the second resistor R6; the base of the second signal PNP transistor Q5 is connected to the first end of the third voltage dividing resistor R9 and the first end of the fourth voltage dividing resistor R10; the cathode of the second stabilizing tube Z2, the second end of the second resistor R6 and the second end of the third voltage dividing resistor R9 are grounded GND; the collector of the power NPN transistor Q6, the collector of the second signal PNP transistor Q5 and the second end of the fourth voltage dividing resistor R10 are connected to the negative output voltage VSS.
[0016] Optionally, the power supply comprises a power supply and a flyback converter, and the power supply adjusts the size of the direct current input voltage through the flyback converter.
[0017] In a second aspect, the application provides a motor driving system, comprising an inverter, an IGBT transistor and the LDO positive and negative voltage conversion circuit based on discrete devices according to any one of the first aspect, wherein the LDO positive and negative voltage conversion circuit is used to provide a driving voltage for the IGBT transistor; and the inverter generates alternating current with different frequencies and amplitudes by controlling the switching state of the IGBT transistor.
[0018] Compared with the integrated chip, the LDO positive and negative voltage conversion circuit based on discrete devices and the motor driving system reduce the design complexity and the design and development cost, and the discrete devices have better heat dissipation than the integrated chip, can dissipate more heat, thereby supporting a larger current to flow through the circuit, and can output larger power under the same pressure difference, thereby meeting the demand for large power. BRIEF DESCRIPTION OF DRAWINGS
[0019] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described in the following description are some embodiments of the present application, and all other drawings obtained by those skilled in the art without creative labor on the basis of these drawings also belong to the protection scope of the present application.
[0020] Figure 1 The circuit structure schematic diagram of the LDO positive and negative voltage conversion circuit based on discrete devices provided by the embodiment of the present application is shown in the figure.
[0021] Figure 2 The circuit principle diagram of the LDO positive and negative voltage conversion circuit based on discrete devices provided by the embodiment of the present application is shown in the figure.
[0022] Figure 3 The circuit principle diagram of the LDO positive and negative voltage conversion circuit based on discrete devices provided by another embodiment of the present application is shown in the figure.
[0023] Icon: 101, power supply; 102, LDO positive voltage conversion unit; 103, LDO negative voltage conversion unit; 104, voltage stabilizing component; 105, voltage dividing component; 106, positive feedback adjusting component; 107, current limiting component; 108, negative feedback adjusting component. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical scheme in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.
[0025] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor also belong to the protection scope of the present application.
[0026] It should be noted that: similar labels and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.
[0027] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is typically placed when in use. These terms are intended solely to facilitate the description of this utility model and to simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0028] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.
[0029] It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.
[0030] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.
[0031] The embodiment of the present application provides an LDO positive and negative voltage conversion circuit based on discrete devices, such as Figure 1 As shown, it includes: a power supply 101, an LDO positive voltage conversion unit 102 and an LDO negative voltage conversion unit 103, wherein:
[0032] The power supply 101 is used to provide a DC input voltage to the LDO positive voltage conversion unit 102 and the LDO negative voltage conversion unit 103 respectively;
[0033] The LDO positive voltage conversion unit 102 and the LDO negative voltage conversion unit 103 are both composed of several discrete devices, which at least include a voltage stabilizing device 104, a voltage dividing device 105, and a feedback adjusting device.
[0034] In the embodiment of the present application, the DC input voltage provided by the power supply 101 is 25V, and the pressure difference between the LDO positive voltage conversion unit 102 and the LDO negative voltage conversion unit 103 is a low pressure difference.
[0035] In the embodiment of the present application, the product of the reference voltage and the preset voltage dividing ratio is the output voltage, and the output voltage can be adjusted by adjusting the voltage dividing ratio.
[0036] The present application uses discrete devices for positive and negative voltage conversion, which not only reduces the cost, but also has better heat dissipation than integrated chips, can dissipate more heat, thereby supporting larger current, and can output more power under the same pressure difference, meeting the demand for high power. In addition, through the feedback adjusting device, the output voltage can be stabilized at the target output voltage, improving the stability of the output voltage.
[0037] On the basis of the above embodiment, the voltage stabilizing device 104 at least uses one of a voltage stabilizing diode and a discrete switching voltage stabilizer.
[0038] In the embodiment of the present application, when the voltage stabilizing diode works in the reverse breakdown region, a stable reference voltage can be provided. Common voltage stabilizing diodes are 1N5347BG, 1N5338BG, etc.
[0039] The discrete switching voltage stabilizer is composed of multiple discrete electronic elements, including a control IC, a switching transistor (such as MOSFET), an inductor, a capacitor, a diode, etc. The switching voltage stabilizer converts and stabilizes the voltage through high-frequency switching operation of the switching element (such as MOSFET), has high efficiency, and is suitable for high-power applications.
[0040] On the basis of the above embodiment, the voltage dividing device 105 at least uses one of a voltage dividing resistor and a potentiometer.
[0041] In the embodiment of the present application, the potentiometer is a variable resistor, and the division ratio can be changed by manual adjustment. The voltage division resistor is a variable resistor, and more accurate adjustment can be achieved compared with the potentiometer. The division ratio is changed by adjusting the resistance value of the voltage division resistor, so as to divide the voltage.
[0042] The size of the output voltage can be adjusted by adjusting the division ratio of the voltage division component 105, and the preset division ratio can be set according to the target output voltage.
[0043] On the basis of the above embodiment, the LDO positive voltage conversion unit 102 and the LDO negative voltage conversion unit 103 each further comprise a current limiting component 107 for providing a reference current for the voltage stabilizing component 104, and the current limiting component 107 at least uses one of a current limiting resistor and a current limiting diode.
[0044] By setting the current limiting component 107, the voltage stabilizing component 104 and the feedback adjusting component can be protected.
[0045] On the basis of the above embodiment, the positive feedback adjusting component 106 is composed of two symmetrical signal type NPN bipolar transistors and a power type PNP bipolar transistor. The two symmetrical signal type NPN bipolar transistors are used to compare the error size of the actual output voltage and the positive polarity target output voltage, and the power type PNP bipolar transistor is used to adjust the positive output voltage to the positive polarity target output voltage according to the error size.
[0046] In the embodiment of the present application, the two symmetrical signal type NPN bipolar transistors and the power type PNP bipolar transistor form a positive feedback loop. Specifically, the two symmetrical signal type NPN bipolar transistors form a differential amplifier, which compares the error size of the target output voltage and the actual output voltage by comparing the base voltages of the two NPN bipolar transistors, and feeds back to the power type PNP bipolar transistor. The power type PNP bipolar transistor adjusts the voltage between the emitter and the collector by adjusting the conduction degree, so as to ensure the stable positive voltage output.
[0047] On the basis of the above embodiment, the negative feedback adjusting component 108 is composed of two symmetrical signal type PNP bipolar transistors and a power type NPN bipolar transistor. The two symmetrical signal type PNP bipolar transistors are used to compare the error size of the actual output voltage and the negative polarity target output voltage, and the power type PNP bipolar transistor is used to adjust the negative output voltage to the negative polarity target output voltage according to the error size.
[0048] In the embodiment of the present application, two symmetrical signal type PNP bipolar transistors and one power type NPN bipolar transistor form a negative feedback loop; specifically, the two symmetrical signal type PNP bipolar transistors form a differential amplifier, the error between the target output voltage and the actual output voltage is compared by comparing the base voltages of the two PNP bipolar transistors, and is fed back to the power type NPN bipolar transistor, which adjusts the voltage between the emitter and the collector by adjusting the conduction degree, so as to ensure the stable negative voltage output.
[0049] In one possible implementation, as shown in FIG. 1, the LDO positive voltage conversion unit 102 includes a first voltage stabilizing tube Z1, a first current limiting resistor R1, a second current limiting resistor R2, a power type PNP transistor Q1, a first signal type NPN transistor Q2, a second signal type NPN transistor Q3, a first voltage dividing resistor R3, a second voltage dividing resistor R4, and a first resistor R5. Figure 2 The positive pole of the power supply 101 is connected to the emitter of the power type PNP transistor Q1, the first end of the first current limiting resistor R1, and the first end of the second current limiting resistor R2, respectively; the base of the power type PNP transistor Q1 is connected to the second end of the second current limiting resistor R2 and the collector of the first signal type NPN transistor Q2, respectively; the collector of the power type PNP transistor Q1, the collector of the second signal type NPN transistor Q3, and the first end of the first voltage dividing resistor R3 are connected to the positive output terminal VCC, respectively; the second end of the first current limiting resistor R1 is connected to the base of the first signal type NPN transistor Q2 and the cathode of the first voltage stabilizing tube Z1, respectively; the emitters of the first signal type NPN transistor Q2 and the second signal type NPN transistor Q3 are connected to the first end of the first resistor R5; the base of the second signal type NPN transistor Q3 is connected to the second end of the first voltage dividing resistor R3 and the first end of the second voltage dividing resistor R4, respectively; the second end of the first resistor R5, the anode of the first voltage stabilizing tube Z1, and the second end of the second voltage dividing resistor R4 are connected to the ground GND, respectively.
[0050] In the embodiment of the present application, the first voltage stabilizing tube Z1 is a voltage stabilizing component 104; the first current limiting resistor R1 and the second current limiting resistor R2 form a current limiting component 107; the first voltage dividing resistor R3 and the second voltage dividing resistor R4 form a voltage dividing component 105; the power type PNP transistor Q1, the first signal type NPN transistor Q2, and the second signal type NPN transistor Q3 form a positive feedback adjusting component 106.
[0051] In one possible implementation, as shown in FIG. 1, the LDO positive voltage conversion unit 102 includes a first voltage stabilizing tube Z1, a first current limiting resistor R1, a second current limiting resistor R2, a power type PNP transistor Q1, a first signal type NPN transistor Q2, a second signal type NPN transistor Q3, a first voltage dividing resistor R3, a second voltage dividing resistor R4, and a first resistor R5. Figure 2As shown, the LDO negative voltage conversion unit 103 includes a second voltage stabilizing tube Z2, a third current limiting resistor R7, a fourth current limiting resistor R8, a power type NPN transistor Q1, a first signal type PNP transistor Q4, a second signal type PNP transistor Q5, a third voltage dividing resistor R9, a fourth voltage dividing resistor R10, and a second resistor R6; the negative electrode of the power supply 101 is connected to the emitter of the power type NPN transistor Q6, the first end of the third current limiting resistor R7, and the first end of the fourth current limiting resistor R8; the base of the power type NPN transistor Q6 is connected to the second end of the fourth current limiting resistor R8 and the collector of the first signal type PNP transistor Q4; the second end of the third current limiting resistor R7 is connected to the anode of the second voltage stabilizing tube Z2 and the base of the first signal type PNP transistor Q4; the emitters of the first signal type PNP transistor Q4 and the second signal type PNP transistor Q5 are connected to the first end of the second resistor R6; the base of the second signal type PNP transistor Q5 is connected to the first end of the third voltage dividing resistor R9 and the first end of the fourth voltage dividing resistor R10; the cathode of the second voltage stabilizing tube Z2, the second end of the second resistor R6, and the second end of the third voltage dividing resistor R9 are grounded GND; the collector of the power type NPN transistor Q6, the collector of the second signal type PNP transistor Q5, and the second end of the fourth voltage dividing resistor R10 are connected to the negative output voltage VSS.
[0052] In the embodiments of the present application, the second voltage stabilizing tube Z2 is a voltage stabilizing component 104; the third current limiting resistor R7 and the fourth current limiting resistor R8 form a current limiting component 107; the third voltage dividing resistor R9 and the fourth voltage dividing resistor R10 form a voltage dividing component 105; the power type NPN transistor Q1, the first signal type PNP transistor Q4, and the second signal type PNP transistor Q5 form a negative feedback adjusting component 108.
[0053] In the embodiments, the working principle of the LDO negative voltage conversion unit 103 is described. The working principle is as follows: the positive electrode of the power supply 101 is connected to GND, and the negative electrode is connected to VSS, so that a negative polarity voltage is output. The base voltage of Q5 is equal to the base voltage of Q4, the base voltage of Q4 is equal to the voltage of the second voltage stabilizing tube Z2, and the negative output voltage VSS = VQ5b*(R9+R10) / R9; VQ5b is the base voltage of Q5, and (R9+R10) / R9 is a voltage dividing ratio.
[0054] In one example, assuming that the reference voltage of the second voltage stabilizing tube Z2 is -2.5V, then VQ5b = -2.5V, and assuming that the target negative polarity output voltage is -5V; then the voltage dividing ratio (R9+R10) / R9 can be set to 2, i.e., R9 = R10, so that VSS = -5V. The voltage dividing ratio can be adjusted according to the size of the target negative polarity output voltage.
[0055] When the output voltage VSS is jittered or the like, the actual output voltage will change, for example, when the actual output voltage VSS = -5.5V, it indicates that the actual output voltage is less than the negative polarity target output voltage, at this time, the base voltage of Q5 is -2.75V, the base voltage is reduced, so that the voltage across the second resistor R6 is also reduced, the current flowing through R6 is reduced, the current flowing through Q4 is also reduced, and the base current of Q6 is also reduced, when the base current of Q6 is reduced, the voltage between the emitter and the collector of Q6 will increase, thereby adjusting VSS to -5V, ensuring stable output.
[0056] The working principle of the LDO positive voltage conversion unit is the same as above, and will not be repeated here.
[0057] On the basis of the above embodiment, the power supply 101 includes a power supply and a flyback converter, and the power supply adjusts the size of the direct current input voltage through the flyback converter.
[0058] In one example, as shown in Figure 3 The flyback converter is composed of a field effect transistor Q7, a transformer, an energy storage capacitor C1 and a TVS tube D1. Among them, the DC provides a 12V direct current power supply, generates an alternating current through the opening and closing operation of the field effect transistor Q7, converts it into a 25V direct current through the transformer, and stores it in the energy storage capacitor C1.
[0059] Among them, the TVS tube can quickly respond when transient overvoltage occurs in the circuit, clamp the voltage at a safe level, thereby protecting other components in the circuit from damage.
[0060] Through the power supply 101, the size of the direct current input voltage can be adjusted according to the demand, and the output range of the target output voltage is adjusted, meeting the demand of various output voltages.
[0061] Based on the same technical concept, a motor driving system is provided, which comprises an inverter, an IGBT transistor and the LDO positive and negative voltage conversion circuit based on discrete devices according to any one of the first aspect, and the LDO positive and negative voltage conversion circuit is used to provide a driving voltage for the IGBT transistor; the inverter generates alternating currents with different frequencies and amplitudes by controlling the switching state of the IGBT transistor, so as to control the speed and torque of the motor.
[0062] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. An LDO positive and negative voltage conversion circuit based on discrete devices, characterized in that: include: Power supply, LDO positive voltage conversion unit and LDO negative voltage conversion unit, including: The power supply is used to provide a DC input voltage to the LDO positive voltage conversion unit and the LDO negative voltage conversion unit respectively; The LDO positive voltage conversion unit and the LDO negative voltage conversion unit are both composed of a number of discrete components, which include at least a voltage stabilizing component, a voltage dividing component, and a feedback regulating component. The voltage stabilizing component is used to provide a reference voltage, the voltage dividing component is used to regulate the DC input voltage to a target output voltage based on the reference voltage and a preset voltage dividing ratio, and the feedback regulating component is used to regulate the output voltage to the target output voltage based on the error between the actual output voltage and the target output voltage. The feedback regulating component in the LDO positive voltage conversion unit is a positive feedback regulating component, and the target output voltage is a positive polarity target output voltage; the feedback regulating component in the LDO negative voltage conversion unit is a negative feedback regulating component, and the target output voltage is a negative polarity target output voltage.
2. The LDO positive-negative voltage conversion circuit based on discrete devices according to claim 1, characterized in that: The voltage stabilizing component is at least one of a voltage stabilizing diode and a discrete switching regulator.
3. The LDO positive-negative voltage conversion circuit based on discrete devices according to claim 2, characterized in that: The voltage dividing component is at least one of a voltage dividing resistor and a potentiometer.
4. The LDO positive-negative voltage conversion circuit based on discrete devices according to claim 3, characterized in that: The LDO positive voltage conversion unit and the LDO negative voltage conversion unit both further include a current limiting component, which is used to provide a reference current for the voltage stabilizing component. The current limiting component is at least one of a current limiting resistor and a current limiting diode.
5. The LDO positive-negative voltage conversion circuit based on discrete devices according to claim 4, characterized in that: The positive feedback regulation component consists of two symmetrical signal-type NPN bipolar transistors and one power-type PNP bipolar transistor; the two symmetrical signal-type NPN bipolar transistors are used to compare the error between the actual output voltage and the positive polarity target output voltage, and the power-type PNP bipolar transistor is used to adjust the positive output voltage to the positive polarity target output voltage according to the error.
6. The LDO positive-negative voltage conversion circuit based on discrete devices according to claim 4, characterized in that: The negative feedback regulation component consists of two symmetrical signal-type PNP bipolar transistors and one power-type NPN bipolar transistor; the two symmetrical signal-type PNP bipolar transistors are used to compare the error between the actual output voltage and the negative polarity target output voltage, and the power-type NPN bipolar transistor is used to adjust the negative output voltage to the negative polarity target output voltage according to the error.
7. The LDO positive-negative voltage conversion circuit based on discrete devices according to claim 5, characterized in that: The LDO positive voltage conversion unit includes a first voltage regulator tube Z1, a first current limiting resistor R1, a second current limiting resistor R2, a power type PNP transistor Q1, a first signal type NPN transistor Q2, a second signal type NPN transistor Q3, a first voltage dividing resistor R3, a second voltage dividing resistor R4 and a first resistor R5; the positive electrode of the power supply is respectively connected to the emitter of the power type PNP transistor Q1, the first end of the first current limiting resistor R1, and the first end of the second current limiting resistor R2; the base of the power type PNP transistor Q1 is respectively connected to the second end of the second current limiting resistor R2 and the collector of the first signal type NPN transistor Q2; the collector of the power type PNP transistor Q1, the second The collector of the signal-type NPN transistor Q3 and the first end of the first voltage-dividing resistor R3 are respectively connected to the positive output terminal VCC; the second end of the first current-limiting resistor R1 is respectively connected to the base of the first signal-type NPN transistor Q2 and the cathode of the first voltage-regulating diode Z1; the emitters of the first signal-type NPN transistor Q2 and the second signal-type NPN transistor Q3 are both connected to the first end of the first resistor R5; the base of the second signal-type NPN transistor Q3 is respectively connected to the second end of the first voltage-dividing resistor R3 and the first end of the second voltage-dividing resistor R4; the second end of the first resistor R5, the anode of the first voltage-regulating diode Z1, and the second end of the second voltage-dividing resistor R4 are respectively connected to ground GND.
8. The LDO positive-negative voltage conversion circuit based on discrete devices according to claim 6, characterized in that: The LDO negative voltage conversion unit includes a second voltage regulator tube Z2, a third current limiting resistor R7, a fourth current limiting resistor R8, a power type NPN transistor Q6, a first signal type PNP transistor Q4, a second signal type PNP transistor Q5, a third voltage dividing resistor R9, a fourth voltage dividing resistor R10 and a second resistor R6; the negative electrode of the power supply is respectively connected to the emitter of the power type NPN transistor Q6, the first end of the third current limiting resistor R7, and the first end of the fourth current limiting resistor R8; the base of the power type NPN transistor Q6 is respectively connected to the second end of the fourth current limiting resistor R8 and the collector of the first signal type PNP transistor Q4; the second end of the third current limiting resistor R7 ... The anode of the second voltage-stabilizing tube Z2 and the base of the first signal-type PNP transistor Q4; the emitters of the first signal-type PNP transistor Q4 and the second signal-type PNP transistor Q5 are both connected to the first end of the second resistor R6; the base of the second signal-type PNP transistor Q5 is connected to the first end of the third voltage-dividing resistor R9 and the first end of the fourth voltage-dividing resistor R10; the cathode of the second voltage-stabilizing tube Z2, the second end of the second resistor R6, and the second end of the third voltage-dividing resistor R9 are all grounded GND; the collector of the power-type NPN transistor Q6, the collector of the second signal-type PNP transistor Q5, and the second end of the fourth voltage-dividing resistor R10 are all connected to the negative output voltage VSS.
9. The LDO positive-negative voltage conversion circuit based on discrete devices according to any one of claims 1 to 8, characterized in that: The power supply includes a power supply and a flyback converter, and the power supply adjusts the magnitude of the DC input voltage through the flyback converter.
10. A motor drive system, characterized in that: It comprises an inverter, an IGBT transistor and an LDO positive-negative voltage conversion circuit based on discrete devices as described in any one of claims 1 to 9, wherein the LDO positive-negative voltage conversion circuit is used to provide a driving voltage for the IGBT transistor; the inverter generates alternating current of different frequencies and amplitudes by controlling the switching state of the IGBT transistor.