Power supply circuit, control method and motor servo control system

Abstract

The invention relates to the technical field of circuits, and discloses a power supply circuit, a control method and a motor servo control system.The power supply circuit comprises a first switch module, a second switch module, a third switch module, a fourth switch module, a first capacitor, a second capacitor and a resistor; the second end of the first switch module is connected with the first end of the second switch module, the first end of the first capacitor is connected with the first end of the first switch module, and the second end of the first capacitor is grounded; the first end of the second capacitor is connected with the second end of the second switch module; the first end of the third switch module is connected with the first end of the first switch module, the second end of the third switch module is connected with the first end of the fourth switch module, and the second end of the fourth switch module is grounded; the first end of the resistor is connected with the second end of the second switch module; therefore, the soft power-on current limiting function and the brake discharging function are achieved, and meanwhile the size of the circuit and the power consumption of the circuit are reduced.

Description

Technical Field

[0001] This application relates to the field of circuit technologies, and particularly to a power supply circuit, a control method, and a motor servo control system. Background Art

[0002] Currently, due to the large DC bus capacitor in the voltage source inverter, a large impact will be brought during power-on. Generally, in practical applications, a soft start resistor is connected in series on the input bus to suppress the inrush current during power-on. After the bus capacitor is fully charged, a relay or a power switch is used to short-circuit the resistor. However, due to the large inrush current and high instantaneous power during power-on, the series resistor heats up quickly and has a large power loss.

[0003] Motor servo control systems often have the condition of regenerative braking, and the bus voltage will rise sharply accordingly. To ensure the safety of the inverter module, most servo motor control systems with a load-carrying condition or regenerative braking must be designed with a braking discharge circuit. The braking discharge circuit includes a discharge resistor and a discharge control switch, and the charge of the bus capacitor is discharged through the discharge resistor. Since the discharge resistor has a large power and a large power loss, and a separate power supply circuit needs to be set up, it often occupies a large volume, which is a great burden on miniaturized devices.

[0004] At present, systems with both soft start current limiting function and braking discharge function are often set up with a soft start resistor and a discharge resistor respectively. The inrush current during power-on is suppressed by connecting resistors in series, and the charge of the bus capacitor is discharged through the discharge resistor. The volume of these two resistors and their power supply circuits often accounts for a large proportion in the whole system, and additional wires are required for off-board connection, which is not conducive to the miniaturization and lightweight design of the system. Summary of the Invention

[0005] The purpose of the embodiments of this application is to provide a power supply circuit, a control method, and a motor servo control system, so as to reduce the size of the circuit and lower the power consumption of the circuit while having the soft start current limiting function and the braking discharge function.

[0006] To solve the above technical problems, an embodiment of the present application provides a power supply circuit, including: a first switch module, a second switch module, a third switch module, a fourth switch module, a first capacitor, a second capacitor, and a resistor; a first end of the first switch module serves as an input end of the power supply circuit, a second end of the first switch module is connected to a first end of the second switch module, and a second end of the second switch module serves as an output end of the power supply circuit; a first end of the first capacitor is connected to the first end of the first switch module, and a second end of the first capacitor is grounded; a first end of the second capacitor is connected to the second end of the second switch module, and a second end of the second capacitor is grounded; a first end of the third switch module is connected to the first end of the first switch module, a second end of the third switch module is connected to a first end of the fourth switch module, and a second end of the fourth switch module is grounded; a first end of the resistor is connected to the second end of the second switch module, and a second end of the resistor is connected to the first end of the fourth switch module; during the power-on stage of the power supply circuit, a soft power-on loop is formed among the body diode in the first switch module, the third switch module, and the resistor; during the braking discharge stage of the power supply circuit, the resistor and the fourth switch module form a discharge loop.

[0007] An embodiment of the present application further provides a control method for a power supply circuit, which is applied to a controller. The controller is connected to control ends of the first switch module, the second switch module, the third switch module, and the fourth switch module of the above-mentioned power supply circuit; the control method includes: when the power supply circuit is in the power-on stage, controlling the first switch module to turn off, the second switch module to turn off, the third switch module to turn on, and the fourth switch module to turn off; when the power supply circuit is in the braking discharge stage, controlling the first switch module to turn on, the second switch module to turn on, the third switch module to turn off, and the fourth switch module to turn on, or controlling the first switch module to turn off, the second switch module to turn on, the third switch module to turn off, and the fourth switch module to turn on.

[0008] In some embodiments, the first switch module, the second switch module, the third switch module, and the fourth switch module are all power switch devices.

[0009] In some embodiments, the power switch device is at least any one of the following: MOS transistor, IGBT transistor.

[0010] In some embodiments, the first capacitor and the second capacitor are any one of the following capacitors: electrolytic capacitor, thin film support capacitor.

[0011] In some embodiments, the first switch module and the second switch module are PMOS transistors, and the third switch module and the fourth switch module are NMOS transistors.

[0012] The technical solutions provided by the embodiments of the present application have at least the following advantages:

[0013] In the embodiments of the present application, the soft power-on function and the bus discharge function are switched by means of a combined switch. Only one resistor needs to be set in the power supply circuit. By multiplexing one resistor, the function of the soft power-on resistor in the soft power-on loop during the power-on stage and the function of the discharge brake resistor in the discharge loop during the braking discharge stage are respectively realized, reducing the volume of the entire circuit. And since only switch devices and resistors need to be set in the entire power supply circuit, the complexity of circuit wiring and thermal design is reduced, and the power loss in the normal working state is also reduced. Thus, while the power supply circuit has the soft power-on current limiting function and the braking discharge function, the size of the circuit is reduced and the power consumption of the circuit is lowered. Description of the Drawings

[0014] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the drawings in the figures do not constitute a proportional limitation.

[0015] Figure 1 is a schematic circuit structure diagram of a power supply circuit according to an embodiment of the present application;

[0016] Figure 2 is a specific circuit structure diagram of a power supply circuit according to an embodiment of the present application;

[0017] Figure 3 is a schematic flowchart of a control method for a power supply circuit according to an embodiment of the present application;

[0018] Figure 4 is a schematic circuit structure diagram of a motor servo control system according to an embodiment of the present application. Detailed Embodiments

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present application, many technical details are presented for the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions required to be protected by the present application can still be implemented. The following division of each embodiment is for convenience of description and should not constitute any limitation on the specific implementation manner of the present application. Each embodiment can be combined and cross-referenced with each other without conflict.

[0020] An embodiment of the present application relates to a power supply circuit, and the specific circuit structure schematic diagram is as follows Figure 1 shown. The power supply circuit includes: a first switch module 101, a second switch module 102, a third switch module 103, a fourth switch module 104, a first capacitor C1, a second capacitor C2, and a resistor R.

[0021] Specifically, the first end of the first switch module serves as the input end IN of the power supply circuit. The second end of the first switch module 101 is connected to the first end of the second switch module 102, and the second end of the second switch module 102 serves as the output end OUT of the power supply circuit. The first end of the first capacitor C1 is connected to the first end of the first switch module 101, and the second end of the first capacitor C1 is grounded. The first end of the second capacitor C2 is connected to the second end of the second switch module 102, and the second end of the second capacitor C2 is grounded. The first end of the third switch module 103 is connected to the first end of the first switch module 101, the second end of the third switch module 103 is connected to the first end of the fourth switch module 104, and the second end of the fourth switch module 104 is grounded. The first end of the resistor R is connected to the second end of the second switch module 102, and the second end of the resistor R is connected to the first end of the fourth switch module 104. During the power-on stage of the power supply circuit, a soft power-on loop is formed among the body diode in the first switch module 101, the third switch module 103, and the resistor R. During the braking discharge stage of the power supply circuit, the resistor R and the fourth switch module 104 form a discharge loop.

[0022] In this embodiment, the soft power-on function and the bus discharge function are switched by means of a combined switch. Only one resistor R needs to be set in the power supply circuit. By reusing one resistor R, the functions of the soft power-on resistor of the soft power-on loop during the power-on stage and the discharge braking resistor of the discharge loop during the braking discharge stage are respectively realized, reducing the volume of the entire circuit. And since only switching devices and the resistor R need to be set in the entire power supply circuit, the complexity of circuit wiring and thermal design is reduced, and the power loss under the normal working state is also reduced. Thus, while the power supply circuit has the soft power-on current limiting function and the braking discharge function, the size of the circuit is reduced and the power consumption of the circuit is lowered.

[0023] Specifically, the first switch module 101, the second switch module 102, the third switch module 103, and the fourth switch module 104 are all power switching devices, and the power switching devices are at least any one of the following: MOS transistor, IGBT transistor; the first capacitor C1 and the second capacitor C2 are any one of the following capacitors: electrolytic capacitor, thin film support capacitor.

[0024] Specifically, the input end IN of the power supply circuit is connected to a power supply, the output end OUT of the power supply circuit is connected to the DC end of an inverter, and the AC side of the inverter is connected to a motor, so as to provide electrical energy for the motor.

[0025] As Figure 2 shown, it is a schematic diagram of the specific circuit structure of the power supply circuit in this embodiment. In this embodiment, the first switch module 101 and the second switch module 102 are PMOS transistors, and the third switch module 103 and the fourth switch module 104 are NMOS transistors as an example for illustration. The first switch module is the first MOS transistor Q1, the second switch module is the second MOS transistor Q2, the third switch module is the third MOS transistor Q3, and the fourth switch module is the fourth MOS transistor Q4. In practical applications, the first switch module 101, the second switch module 102, the third switch module 103, and the fourth switch module 104 can also be other power switch devices.

[0026] The power supply circuit in this embodiment includes the first MOS transistor Q1, the second MOS transistor Q2, the third MOS transistor Q3, the fourth MOS transistor Q4, the resistor R, the first capacitor C1, and the second capacitor C2; the input end IN of the power supply circuit is a DC power supply. The input end IN is respectively connected to the drain of the first MOS transistor Q1 and the positive electrode of the first capacitor C1. The drain of the first MOS transistor Q1 is respectively connected to the source of the second MOS transistor Q2 and the drain of the third MOS transistor Q3. The drain of the second MOS transistor Q2 is respectively connected to the first end of the resistor R, the positive electrode of the second capacitor C2, and the output end OUT of the power supply circuit. The source of the third MOS transistor Q3 is respectively connected to the second end of the resistor R and the drain of the fourth MOS transistor Q4. The source of the fourth MOS transistor Q4, the negative electrode of the first capacitor C1, the negative electrode of the second capacitor C2, and GND are connected.

[0027] Among them, the first capacitor C1 and the second capacitor C2 respectively play the roles of stabilizing the voltage at the input and output ends OUT and supporting the bus. The first MOS transistor Q1 has a body diode. The anode of the body diode is connected to the drain of the first MOS transistor Q1, and the cathode of the body diode is connected to the source of the first MOS transistor Q1. Thus, when the first MOS transistor Q1 is in the off state, the body diode can realize the anti-backflow function. The second MOS transistor Q2 mainly plays the role of improving efficiency. The third MOS transistor Q3 and the resistor R mainly play the role of soft power-on. The fourth MOS transistor Q4 and the resistor R mainly play the role of braking and discharging. During the power-on stage of the power supply circuit, a soft power-on loop is formed among the body diode in the first MOS transistor Q1, the third MOS transistor Q3, and the resistor R; during the braking and discharging stage of the power supply circuit, a discharging loop is formed by the resistor R and the fourth MOS transistor Q4. The resistor R is both in the soft power-on loop and in the braking and discharging loop. The resistor R plays a multiplexing role, thereby simplifying the structure of the power supply circuit and reducing the volume of the power supply circuit.

[0028] Specifically, a controller is connected to the control terminals of the first MOS transistor Q1, the second MOS transistor Q2, the third MOS transistor Q3, and the fourth MOS transistor Q4. The controller is used to control the conduction and cutoff of the first MOS transistor Q1, the second MOS transistor Q2, the third MOS transistor Q3, and the fourth MOS transistor Q4, so as to control the conduction of the switch transistor combination according to different stages of the power supply circuit, thereby realizing the soft power-on function and the brake discharge function.

[0029] Specifically, when a DC power supply is connected to the input terminal IN of the power supply circuit, a surge current may be introduced. At this time, the power supply circuit is in the power-on stage. At this time, the controller controls the first MOS transistor Q1 to be cutoff, the second MOS transistor Q2 to be cutoff, the third MOS transistor Q3 to be conducting, and the fourth MOS transistor Q4 to be cutoff. The body diode of the first MOS transistor Q1, the third MOS transistor Q3, and the resistor R form a soft power-on loop, so that the input current passes through the body diode of the first MOS transistor Q1, the third MOS transistor Q3, and the resistor R to the output terminal OUT, realizing the current limiting effect during the power-on process of the motor and achieving the purpose of soft power-on.

[0030] After that, after the power-on of the power supply circuit is completed and the surge current phenomenon disappears, the controller can control the first MOS transistor Q1 to be conducting, the second MOS transistor Q2 to be conducting, the third MOS transistor Q3 to be cutoff, and the fourth MOS transistor Q4 to be cutoff, so as to realize the direct connection between the input terminal IN and the output terminal OUT through the first MOS transistor Q1 and the second MOS transistor Q2. At this time, the resistor R has low loss or even no loss, and the loss of the entire circuit is reduced to the lowest state, improving the efficiency of the entire circuit and reducing the power loss of the circuit. Alternatively, after the power-on of the power supply circuit is completed, the controller can also control the first MOS transistor Q1 to be cutoff, the second MOS transistor Q2 to be conducting, the third MOS transistor Q3 to be cutoff, and the fourth MOS transistor Q4 to be cutoff, so as to realize the direct connection between the input terminal IN and the output terminal OUT through the body diode of the first MOS transistor Q1 and the second MOS transistor Q2. At this time, the resistor R has low loss or even no loss, and the loss of the entire circuit is reduced to the lowest state, improving the efficiency of the entire circuit and reducing the power loss of the circuit. Moreover, at this time, the first MOS transistor Q1 is cutoff, and the body diode of the first MOS transistor Q1 realizes the anti-backflow function, preventing the voltage of the output terminal OUT from being greater than the voltage of the input terminal IN, which may cause the overvoltage of the input terminal IN voltage, and improving the reliability of the circuit.

[0031] When the motor brake is applied, i.e., the motor stops running, the voltage at the output terminal OUT of the power supply circuit increases, and the second capacitor C2 is charged, causing the voltage of the second capacitor C2 to increase. As a result, the voltages of both the second capacitor C2 and the output terminal OUT are greater than the voltage at the input terminal IN. At this time, the power supply circuit is in the brake discharge stage. The controller can control the first MOS transistor Q1 to conduct, the second MOS transistor Q2 to conduct, the third MOS transistor Q3 to turn off, and the fourth MOS transistor Q4 to conduct. The resistor R and the fourth MOS transistor Q4 form a discharge loop, and the resistor R releases the excess electrical energy in the second capacitor C2.

[0032] Alternatively, when the power supply circuit is in the brake discharge stage, the controller can control the first MOS transistor Q1 to turn off, the second MOS transistor Q2 to conduct, the third MOS transistor Q3 to turn off, and the fourth MOS transistor Q4 to conduct. The resistor R and the fourth MOS transistor Q4 form a discharge loop, and the resistor R releases the excess electrical energy in the second capacitor C2. At this time, the first MOS transistor Q1 is turned off, and the body diode of the first MOS transistor Q1 can achieve the anti-backflow function to prevent the situation where the voltage at the input terminal IN is overvoltage when the voltage at the output terminal OUT is greater than the voltage at the input terminal IN. The voltage of the first capacitor C1 remains stable, improving the reliability of the circuit. After that, when the voltages of both the second capacitor C2 and the output terminal OUT are less than the voltage at the input terminal IN, the brake discharge stage of the power supply circuit ends.

[0033] It should be noted that due to the stray inductance current continuation in the resistor R body and its long connection wires, if the controller directly controls the fourth MOS transistor Q4 to turn off, it will cause the fourth MOS transistor Q4 to be damaged by the stray inductance current continuation, reducing the service life of the circuit. Therefore, after the brake discharge stage of the power supply circuit ends in this embodiment, the controller can control the first MOS transistor Q1 to turn off, the second MOS transistor Q2 to conduct, and control the third MOS transistor Q3 to turn off and the fourth MOS transistor Q4 to turn off. At this time, the stray inductance current continuation of the resistor R body and its long connection wires can be achieved through the body diode of the third MOS transistor Q3 and the second MOS transistor Q2, thereby avoiding overvoltage when the fourth MOS transistor Q4 is turned off.

[0034] The embodiment of the present application also provides a control method for a power supply circuit, which is applied to a controller. The controller is connected to the control terminals of the first switch module, the second switch module, the third switch module, and the fourth switch module of the power supply circuit in the above embodiment; as Figure 3 shown, it is a schematic flowchart of the control method in this embodiment. The control method in this embodiment includes the following steps:

[0035] Step 201, when the power supply circuit is in the power-on stage, control the first switch module to turn off, the second switch module to turn off, the third switch module to conduct, and the fourth switch module to turn off.

[0036] Reference Figure 2 Taking the first switching module as the first MOS transistor Q1, the second switching module as the second MOS transistor Q2, the third switching module as the third MOS transistor Q3, and the fourth switching module as the fourth MOS transistor Q4 as an example for illustration.

[0037] In the power-on stage, the controller controls the first MOS transistor Q1 to turn off, the second MOS transistor Q2 to turn off, the third MOS transistor Q3 to turn on, and the fourth MOS transistor Q4 to turn off. The body diode of the first MOS transistor Q1, the third MOS transistor Q3, and the resistor R form a soft power-on loop, enabling the input current to pass through the body diode of the first MOS transistor Q1, the third MOS transistor Q3, and the resistor R to the output terminal OUT, achieving the function of current limiting during the motor power-on process and achieving the purpose of soft power-on.

[0038] Step 202, after the power supply circuit finishes power-on, control the first switching module to turn on, the second switching module to turn on, the third switching module to turn off, and the fourth switching module to turn off, or control the first switching module to turn off, the second switching module to turn on, the third switching module to turn off, and the fourth switching module to turn off.

[0039] After the power-on stage ends, the power supply circuit is in a normal working state. The DC current input at the input terminal IN needs to be transmitted to the output terminal OUT through the first MOS transistor Q1 and the second MOS transistor Q2, and then supply power to the motor through the subsequent inverter. Therefore, the controller can achieve this function in the following two ways:

[0040] The first way: that is, the controller controls the first MOS transistor Q1 to turn on, the second MOS transistor Q2 to turn on, the third MOS transistor Q3 to turn off, and the fourth MOS transistor Q4 to turn off, realizing the direct connection between the input terminal IN and the output terminal OUT through the first MOS transistor Q1 and the second MOS transistor Q2. At this time, the resistor R has low loss or even no loss, and the loss of the entire circuit is reduced to the lowest state, improving the efficiency of the entire circuit and reducing the power loss of the circuit.

[0041] The second method: that is, the controller controls the first MOS transistor Q1 to turn off, the second MOS transistor Q2 to turn on, the third MOS transistor Q3 to turn off, and the fourth MOS transistor Q4 to turn off, so that the input terminal IN is directly connected to the output terminal OUT through the body diode of the first MOS transistor Q1 and the second MOS transistor Q2. At this time, the resistor R has low loss or even no loss, and the loss of the entire circuit is reduced to the lowest state, improving the efficiency of the entire circuit and reducing the power loss of the circuit; at the same time, in this way, when the first MOS transistor Q1 is turned off, the body diode of the first MOS transistor Q1 can realize the anti-backflow function, preventing the voltage of the output terminal OUT from being greater than the voltage of the input terminal IN, which may cause overvoltage of the input terminal IN voltage, and improving the reliability of the circuit. Further, since the body diode of the first MOS transistor Q1 can realize the anti-backflow function, even when there are multiple sub-motor systems in the motor servo control system, the body diode of the first switching module can realize the bus anti-backflow function, which can reduce the mutual influence between multiple sub-motor systems and improve the stability of the entire system.

[0042] Step 203, when the power supply circuit is in the braking discharge stage, control the first switching module to turn on, the second switching module to turn on, the third switching module to turn off, and the fourth switching module to turn on, or control the first switching module to turn off, the second switching module to turn on, the third switching module to turn off, and the fourth switching module to turn on.

[0043] Specifically, when the motor brakes, that is, when the motor stops running, the voltage of the output terminal OUT of the power supply circuit increases, and the second capacitor C2 is charged, so that the voltage of the second capacitor C2 increases, and the voltage of the second capacitor C2 and the voltage of the output terminal OUT are both greater than the voltage of the input terminal IN. At this time, it is possible to determine whether the power supply circuit is in the braking discharge stage by comparing the voltage of the second capacitor C2 or the voltage of the output terminal OUT with the preset voltage, that is, the voltage of the input terminal IN.

[0044] When the power supply circuit is in the braking discharge stage, a discharge loop needs to be formed to discharge the excess charge of the second capacitor C2. The controller can discharge the excess charge of the second capacitor C2 in the following two ways:

[0045] The first method: that is, the controller controls the first MOS transistor Q1 to turn on, the second MOS transistor Q2 to turn on, the third MOS transistor Q3 to turn off, and the fourth MOS transistor Q4 to turn on. The resistor R and the fourth MOS transistor Q4 form a discharge loop, and the resistor R releases the excess electrical energy in the second capacitor C2.

[0046] The second method: That is, the controller controls the first MOS transistor Q1 to turn off, the second MOS transistor Q2 to turn on, the third MOS transistor Q3 to turn off, and the fourth MOS transistor Q4 to turn on. The resistor R and the fourth MOS transistor Q4 form a discharge loop, and the resistor R releases the excess electrical energy in the second capacitor C2. At the same time, at this time, the first MOS transistor Q1 is turned off, and the body diode of the first MOS transistor Q1 can achieve the anti-backflow function, preventing the situation that the voltage at the output terminal OUT is greater than the voltage at the input terminal IN, which may cause overvoltage of the voltage at the input terminal IN, so that the voltage of the first capacitor C1 is maintained stable, improving the reliability of the circuit.

[0047] It should be noted that the above description takes the voltage at the input terminal IN as the preset voltage as an example. In actual applications, the preset voltage can be slightly greater than the voltage at the input terminal IN, and it is specifically set according to actual needs. This embodiment does not make specific limitations.

[0048] Step 204, after the braking discharge stage of the power supply circuit ends, control the first switch module to turn off, the second switch module to turn on, and control the third switch module to turn off and the fourth switch module to turn off.

[0049] Specifically, when the excess electrical energy in the second capacitor C2 is released, and the voltage of the second capacitor C2 or the voltage at the output terminal OUT is less than the preset voltage, that is, the voltage at the input terminal IN, the braking discharge stage of the power supply circuit ends.

[0050] In the first method of discharging the excess charge of the second capacitor C2 mentioned above, due to the stray inductance current continuation of the resistor R body and its long connecting wires, if the controller directly controls the fourth MOS transistor Q4 to turn off, it will cause the fourth MOS transistor Q4 to be damaged by the stray inductance current continuation, reducing the service life of the circuit. Therefore, after the braking discharge stage of the power supply circuit ends, the controller controls the first MOS transistor Q1 to switch to the off state, the second MOS transistor Q2 to remain on, and controls the third MOS transistor Q3 to remain off and the fourth MOS transistor Q4 to switch to off. At this time, the stray inductance current continuation of the resistor R body and its long connecting wires can be achieved through the body diode of the third MOS transistor Q3 and the second MOS transistor Q2, thereby avoiding overvoltage when the fourth MOS transistor Q4 is turned off.

[0051] In the second method of discharging the excess charge of the second capacitor C2 as described above, since the first MOS transistor Q1 is in the off state, only the fourth MOS transistor Q4 needs to be controlled to switch to the off state. That is, after the braking discharge stage of the power supply circuit ends, the controller controls the first MOS transistor Q1 to remain off, the second MOS transistor Q2 to remain on, and controls the third MOS transistor Q3 to remain off and the fourth MOS transistor Q4 to switch to the off state. At this time, the stray inductance of the resistor R body and its long connection line can be continued through the body diode of the third MOS transistor Q3 and the second MOS transistor Q2, thereby avoiding overvoltage when the fourth MOS transistor Q4 is turned off.

[0052] The embodiment of the present application also provides a motor servo control system, as Figure 4 shown, which is a schematic circuit diagram of the motor servo control system of this embodiment, including: an inverter 20, a motor M, and the power supply circuit of the above embodiment; the power supply circuit includes: a first switch module 101, a second switch module 102, a third switch module 103, a fourth switch module 104, a first capacitor C1, a second capacitor C2, and a resistor R; the output end of the power supply circuit is connected to the DC end of the inverter 20, and the AC end of the inverter 20 is connected to the motor M.

[0053] The motor servo control system of this embodiment can respectively realize the function of the soft start resistor of the soft start circuit during the power-on stage and the function of the discharge braking resistor of the discharge circuit during the braking discharge stage by using the above power supply circuit and multiplexing a resistor R, reducing the volume of the entire motor servo control system. And since the entire motor servo control system only needs to set switch devices and the resistor R, it reduces the complexity of wiring and thermal design, and also reduces the power loss under normal working conditions. Thus, while the motor servo control system has the functions of soft start current limiting and braking discharge, it reduces the size of the system and lowers the power consumption of the system.

[0054] It should be noted that in the related art, in a complex system with multiple motors, in order to avoid mutual influence between each motor subsystem, it is necessary to connect a diode or SCR (Silicon Controlled Rectifier) in series on the power supply path of each subsystem to achieve the function of preventing bus backflow, so that when the motor of each subsystem undergoes regenerative braking, that is, braking discharge, the bus voltage of other subsystems can be stabilized. However, this mode will increase the complexity of the entire system and has a high power loss in the absence of overvoltage or regenerative braking, thereby reducing the efficiency of the entire system. And the motor servo control system of this embodiment includes the power supply circuit of the above embodiment, and the body diode of the first switch module can achieve the function of preventing bus backflow, so that the function of preventing bus backflow can be achieved without connecting a diode or SCR in series on the power supply path of each subsystem. While improving the efficiency of the entire system, it also takes into account reducing the size of the entire system.

[0055] In addition, in order to highlight the innovative parts of this application, units that are not closely related to solving the technical problems proposed in this application are not introduced in this embodiment. However, this does not mean that there are no other units in this embodiment.

[0056] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing this application. In actual applications, various changes can be made to them in form and details without departing from the spirit and scope of this application.

Claims

1. A power supply circuit, characterized in that, Including: A first switch module, a second switch module, a third switch module, a fourth switch module, a first capacitor, a second capacitor, and a resistor; The first end of the first switch module serves as the input end of the power supply circuit, the second end of the first switch module is connected to the first end of the second switch module, and the second end of the second switch module serves as the output end of the power supply circuit; the first end of the first capacitor is connected to the first end of the first switch module, and the second end of the first capacitor is grounded; the first end of the second capacitor is connected to the second end of the second switch module, and the second end of the second capacitor is grounded; The first end of the third switch module is connected to the first end of the first switch module, the second end of the third switch module is connected to the first end of the fourth switch module, and the second end of the fourth switch module is grounded; the first end of the resistor is connected to the second end of the second switch module, and the second end of the resistor is connected to the first end of the fourth switch module; During the power-on stage of the power supply circuit, a soft power-on loop is formed among the body diode in the first switch module, the third switch module, and the resistor; during the braking and discharging stage of the power supply circuit, the resistor and the fourth switch module form a discharging loop.

2. The power supply circuit according to claim 1, characterized in that, The first switch module, the second switch module, the third switch module, and the fourth switch module are all power switch devices.

3. The power supply circuit according to claim 2, characterized in that, The power switch device is at least any one of the following: MOS transistor, IGBT transistor.

4. The power supply circuit according to any one of claims 1 to 3, characterized in that The first capacitor and the second capacitor are any one of the following capacitors: electrolytic capacitor, thin film support capacitor.

5. The power supply circuit according to claim 3, wherein The first switch module and the second switch module are PMOS transistors, and the third switch module and the fourth switch module are NMOS transistors.

6. A control method for a power supply circuit, characterized in that, Applied to a controller, the controller is connected to the control ends of the first switch module, the second switch module, the third switch module, and the fourth switch module of the power supply circuit according to any one of claims 1 to 5; the control method includes: When the power supply circuit is in the power-on stage, controlling the first switch module to turn off, the second switch module to turn off, the third switch module to turn on, and the fourth switch module to turn off; When the power supply circuit is in the braking and discharging stage, controlling the first switch module to turn on, the second switch module to turn on, the third switch module to turn off, and the fourth switch module to turn on, or controlling the first switch module to turn off, the second switch module to turn on, the third switch module to turn off, and the fourth switch module to turn on.

7. The control method of the power supply circuit according to claim 6, characterized in that, After the power-on of the power supply circuit is completed, controlling the first switch module to turn on, the second switch module to turn on, the third switch module to turn off, and the fourth switch module to turn off, or controlling the first switch module to turn off, the second switch module to turn on, the third switch module to turn off, and the fourth switch module to turn off.

8. The control method of the power supply circuit according to claim 6, wherein After the braking and discharging stage of the power supply circuit ends, controlling the first switch module to turn off, the second switch module to turn on, and controlling the third switch module to turn off and the fourth switch module to turn off.

9. The control method of the power supply circuit according to any one of claims 6 to 8, characterized in that, When the voltage of the second capacitor or the output voltage of the power supply circuit exceeds the preset voltage, the power supply circuit is in the braking discharge stage; when the voltage of the second capacitor or the output voltage of the power supply circuit is less than the preset voltage, the braking discharge stage of the power supply circuit ends.

10. A motor servo control system, characterized in that, Comprising: an inverter, a motor, and the power supply circuit according to any one of claims 1 to 5; the output end of the power supply circuit is connected to the DC end of the inverter, and the AC end of the inverter is connected to the motor.

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