Power supply circuit, control method and motor servo control system

Abstract

The application 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, and the second end of the second capacitor is grounded. The first end of the third switch module is connected with the second 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, and the second end of the resistor is connected with the first end of the fourth switch module. Thus, the size of the circuit is reduced, and the power consumption of the circuit is lowered while the soft power-on current-limiting function and the brake discharge function are possessed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit, in particular to a power supply circuit, a control method and a motor servo control system. BACKGROUND

[0002] At present, due to the existence of large DC bus capacitor of voltage type inverter, a great impact will be brought during power-on, and a soft power-on resistor is generally connected in series on the input bus to suppress the power-on impact current in actual application, and a relay or a power switch is used to short the resistance after the bus capacitor charging is completed. However, due to the large impact current during power-on and the high instantaneous power, the series resistance will rapidly heat up and the power loss will be large.

[0003] The motor servo control system often has the working condition of regenerative braking, and the bus voltage will be sharply increased. In order to ensure the safety of the inverter module, most of the servo motor control systems with load following condition or regenerative braking must increase the brake discharge circuit during design. The brake discharge circuit includes a discharge resistance and a discharge control switch, and the electric quantity of the bus capacitor is discharged through the discharge resistance. However, due to the large power of the discharge resistance, the power loss is large, and a separate power supply circuit needs to be set, which often occupies a large volume and is a great burden for small devices.

[0004] At present, the system with soft power-on current limiting function and brake discharge function is often provided with soft power-on resistor and discharge resistor, respectively, and the power-on impact current is suppressed by connecting the resistors in series, and the electric quantity of the bus capacitor is discharged through the discharge resistor. However, the volume of the two resistors and their power supply circuits accounts for a large proportion in the whole system, and additional wires are needed for off-board connection, which is not conducive to the miniaturization and lightweight design of the system. SUMMARY

[0005] The purpose of the embodiment of the present application is to provide a power supply circuit, a control method and a motor servo control system, so as to reduce the size and power consumption of the circuit while having the functions of soft power-on current limiting and brake discharge.

[0006] To solve the above technical problems, embodiments of the present application provide a power supply circuit, comprising: a first switch module, a second switch module, a third switch module, a fourth switch module, a first capacitor, a second capacitor, a resistor; a first end of the first switch module is 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, a second end of the second switch module is 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, 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, a second end of the second capacitor is grounded; a first end of the third switch module is connected to the second 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, 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, a second end of the resistor is connected to the first end of the fourth switch module; in a power-on phase of the power supply circuit, a soft power-on loop is formed among a body diode in the first switch module, the third switch module and the resistor; in a brake bleeding phase of the power supply circuit, a bleeding loop is formed by the resistor and the fourth switch module.

[0007] Embodiments of the present application also provide a control method of a power supply circuit, applied to a controller connected to a control end of a first switch module, a control end of a second switch module, a control end of a third switch module and a control end of a fourth switch module of the power supply circuit; the control method comprises: in a case where the power supply circuit is in a power-on phase, controlling the first switch module to be off, the second switch module to be off, the third switch module to be on and the fourth switch module to be off; in a case where the power supply circuit is in a brake bleeding phase, controlling the first switch module to be on, the second switch module to be on, the third switch module to be off and the fourth switch module to be on, or controlling the first switch module to be off, the second switch module to be on, the third switch module to be off and the fourth switch module to be 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 one of the following: MOS tube, IGBT tube.

[0010] In some embodiments, the first capacitor and the second capacitor are any 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 tubes, and the third switch module and the fourth switch module are NMOS tubes.

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

[0013] The embodiments of the present application realize the switching of the soft power-on function and the bus discharge function by the combination of switches, only one resistor needs to be arranged in the power supply circuit, the function of the soft power-on resistor of the soft power-on circuit in the power-on stage and the function of the discharge brake resistor of the discharge circuit in the brake discharge stage are realized by multiplexing one resistor, the size of the whole circuit is reduced, and since only switch devices and resistors need to be arranged in the whole 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, so that the soft power-on current limiting function and the brake discharge function are realized in the power supply circuit, and the size of the circuit is reduced and the power consumption of the circuit is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0014] One or more embodiments are illustrated by way of example in the drawings in which like reference numerals indicate like elements, and in which: the drawings are not necessarily to scale, except as otherwise noted, and:

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

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

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

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

[0019] In order to make the purposes, technical schemes 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 skilled in the art can understand that in the embodiments of the present application, many technical details are proposed in order to make the readers better understand the present application. However, the technical scheme claimed by the present application can be realized even without these technical details and various changes and modifications based on the following embodiments. The division of the following embodiments is for the convenience of description, and should not constitute any limitation on the specific implementation of the present application, and the embodiments can be combined and referenced with each other on the premise of not contradicting.

[0020] An embodiment of the present application relates to a power supply circuit, and a specific circuit structure schematic diagram is shown as Figure 1 The power supply circuit comprises 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 is used as an 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 is used as an 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, and the second end of the second capacitor C2 is grounded; the first end of the third switch module 103 is connected to the second 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; in 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; in the brake discharge stage of the power supply circuit, the resistor R and the fourth switch module 104 form a discharge loop.

[0022] The embodiment realizes the switching of the soft power-on function and the bus discharge function by the combination of switches, only one resistor R needs to be arranged in the power supply circuit, the function of the soft power-on resistor of the soft power-on loop in the power-on stage and the function of the discharge brake resistor of the discharge loop in the brake discharge stage are realized by multiplexing one resistor R, the size of the whole circuit is reduced, and since only switch devices and the resistor R need to be arranged in the whole 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, so that the power supply circuit has the soft power-on current limiting function and the brake discharge function, and the size of the circuit is reduced and the power consumption of the circuit is reduced.

[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 switch devices, and the power switch devices are at least any one of the following: MOS tube and IGBT tube; the first capacitor C1 and the second capacitor C2 are any one of the following capacitors: electrolytic capacitor and 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 a direct current end of an inverter, and an alternating current side of the inverter is connected to a motor, so as to provide electric energy for the motor.

[0025] As Figure 2 shown, as a specific circuit structure schematic diagram of the power supply circuit of the embodiment, the embodiment takes the first switch module 101 and the second switch module 102 as PMOS tubes, the third switch module 103 and the fourth switch module 104 as NMOS tubes as an example for description, the first switch module is the first MOS tube Q1, the second switch module is the second MOS tube Q2, the third switch module is the third MOS tube Q3, and the fourth switch module is the fourth MOS tube Q4. In actual application, 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 of the embodiment includes the first MOS tube Q1, the second MOS tube Q2, the third MOS tube Q3, the fourth MOS tube Q4, the resistor R, the first capacitor C1, and the second capacitor C2; the input end IN of the power supply circuit is a direct current power supply, the input end IN is connected with the drain of the first MOS tube Q1 and the positive pole of the first capacitor C1 respectively, the drain of the first MOS tube Q1 is connected with the source of the second MOS tube Q2 and the drain of the third MOS tube Q3 respectively, the drain of the second MOS tube Q2 is connected with the first end of the resistor R, the positive pole of the second capacitor C2, and the output end OUT of the power supply circuit respectively, the source of the third MOS tube Q3 is connected with the second end of the resistor R and the drain of the fourth MOS tube Q4 respectively, and the source of the fourth MOS tube Q4 is connected with the negative pole of the first capacitor C1, the negative pole of the second capacitor C2, and GND.

[0027] Among them, the first capacitor C1 and the second capacitor C2 respectively realize the functions of input and output end OUT voltage stabilization and bus support, the first MOS tube Q1 has a body diode, the anode of the body diode is connected with the drain of the first MOS tube Q1, and the cathode of the body diode is connected with the source of the first MOS tube Q1, so that the body diode can realize the anti-inversion function in the off state of the first MOS tube Q1, the second MOS tube Q2 mainly realizes the function of improving efficiency, the third MOS tube Q3 and the resistor R mainly realize the function of soft power-on, and the fourth MOS tube Q4 and the resistor R mainly realize the function of brake discharge. In the power-on stage of the power supply circuit, the body diode in the first MOS tube Q1, the third MOS tube Q3, and the resistor R form a soft power-on loop; in the brake discharge stage of the power supply circuit, the resistor R and the fourth MOS tube Q4 form a discharge loop, the resistor R is in the soft power-on loop and the brake discharge loop, and 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, the control end of the first MOS Q1, the control end of the second MOS Q2, the control end of the third MOS Q3, and the control end of the fourth MOS Q4 are connected with a controller, and the controller is used to control the conduction and closing of the first MOS Q1, the second MOS Q2, the third MOS Q3, and the fourth MOS Q4, so as to control the conduction of the switch tube combination according to different stages of the power supply circuit, thereby realizing the soft power-on function and the brake bleeder function.

[0029] Specifically, when the input end IN of the power supply circuit is connected with a direct current power supply, 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 Q1 to be off, the second MOS Q2 to be off, the third MOS Q3 to be on, and the fourth MOS Q4 to be off, the body diode of the first MOS Q1, the third MOS 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 Q1, the third MOS Q3, and the resistor R to the output end OUT, realizing the current limiting effect in the process of powering on the motor, and achieving the purpose of soft power-on.

[0030] After the power supply circuit is powered on, the surge current phenomenon disappears, the controller can control the first MOS Q1 to be on, the second MOS Q2 to be on, the third MOS Q3 to be off, and the fourth MOS Q4 to be off, realizing that the input end IN is directly connected with the output end OUT through the first MOS Q1 and the second MOS Q2, at this time, the resistor R has low loss or even no loss, the loss of the entire circuit is reduced to the lowest state, the efficiency of the entire circuit is improved, and the power loss of the circuit is reduced. Alternatively, after the power supply circuit is powered on, the controller can control the first MOS Q1 to be off, the second MOS Q2 to be on, the third MOS Q3 to be off, and the fourth MOS Q4 to be off, realizing that the input end IN is directly connected with the output end OUT through the body diode of the first MOS Q1 and the second MOS Q2, at this time, the resistor R has low loss or even no loss, the loss of the entire circuit is reduced to the lowest state, the efficiency of the entire circuit is improved, and the power loss of the circuit is reduced, and at this time, the first MOS Q1 is off, the body diode of the first MOS Q1 realizes the anti-backflow function, prevents the voltage of the input end IN from being overvoltage when the voltage of the output end OUT is greater than the voltage of the input end IN, and improves the reliability of the circuit.

[0031] When the motor brake, i.e. the motor stops running, the output end OUT voltage of the power supply circuit increases, the second capacitor C2 is charged, so that the voltage of the second capacitor C2 increases, so that the voltage of the second capacitor C2 and the voltage of the output end OUT are both greater than the voltage of the input end IN. At this time, the power supply circuit is in the brake bleeding stage, and the controller can control the first MOS tube Q1 to be turned on, the second MOS tube Q2 to be turned on, the third MOS tube Q3 to be turned off, and the fourth MOS tube Q4 to be turned on. The resistor R and the fourth MOS tube Q4 form a bleeding loop, and the resistor R releases the excess electrical energy in the second capacitor C2.

[0032] Alternatively, in the case where the power supply circuit is in the brake bleeding stage, the controller can control the first MOS tube Q1 to be turned off, the second MOS tube Q2 to be turned on, the third MOS tube Q3 to be turned off, and the fourth MOS tube Q4 to be turned on. The resistor R and the fourth MOS tube Q4 form a bleeding loop, and the resistor R releases the excess electrical energy in the second capacitor C2. At this time, the first MOS tube Q1 is turned off, and the body diode of the first MOS tube Q1 can realize the anti-backflow function to prevent the input end IN voltage from being overvoltage when the voltage of the output end OUT is greater than the voltage of the input end IN. The voltage of the first capacitor C1 is maintained stable, and the reliability of the circuit is improved. After that, when the voltage of the second capacitor C2 and the voltage of the output end OUT are both less than the voltage of the input end IN, the brake bleeding stage of the power supply circuit ends.

[0033] It is worth mentioning that due to the existence of the stray inductance of the resistor R body and its long connecting line, if the controller directly controls the fourth MOS tube Q4 to be turned off, the fourth MOS tube Q4 will be damaged by the stray inductance of the resistor R body and its long connecting line, which reduces the service life of the circuit. Therefore, after the brake bleeding stage of the power supply circuit ends, the controller can control the first MOS tube Q1 to be turned off and the second MOS tube Q2 to be turned on, and control the third MOS tube Q3 to be turned off and the fourth MOS tube Q4 to be turned off. At this time, the stray inductance of the resistor R body and its long connecting line can be realized by the body diode of the third MOS tube Q3 and the second MOS tube Q2, thereby avoiding the overvoltage of the fourth MOS tube Q4 when it is turned off.

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

[0035] In step 201, in the case where the power supply circuit is in the power-on stage, the first switch module is controlled to be turned off, the second switch module is controlled to be turned off, the third switch module is controlled to be turned on, and the fourth switch module is controlled to be turned off.

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

[0037] In the power-on stage, the controller controls the first MOS tube Q1 to be off, the second MOS tube Q2 to be off, the third MOS tube Q3 to be on, and the fourth MOS tube Q4 to be off. The body diode of the first MOS tube Q1, the third MOS tube 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 tube Q1, the third MOS tube Q3, and the resistor R to the output terminal OUT, thereby realizing current limiting during the motor power-on process and achieving the purpose of soft power-on.

[0038] Step 202, after the power supply circuit is powered on, the first switch module is turned on, the second switch module is turned on, the third switch module is turned off, and the fourth switch module is turned off, or the first switch module is turned off, the second switch module is turned on, the third switch module is turned off, and the fourth switch module is turned off.

[0039] After the power-on stage ends, the power supply circuit is in a normal working state, and the direct current input from the input terminal IN needs to be transmitted to the output terminal OUT through the first MOS tube Q1 and the second MOS tube Q2, so as to supply power to the motor through the rear-end inverter. Therefore, the controller can realize this function in the following two ways:

[0040] The first way is that the controller controls the first MOS tube Q1 to be on, the second MOS tube Q2 to be on, the third MOS tube Q3 to be off, and the fourth MOS tube Q4 to be off, so as to realize that the input terminal IN is directly connected with the output terminal OUT through the first MOS tube Q1 and the second MOS tube Q2. At this time, the resistor R has low loss or even no loss, the loss of the entire circuit is reduced to the minimum state, the efficiency of the entire circuit is improved, and the power loss of the circuit is reduced.

[0041] The second mode is that the controller controls the first MOS tube Q1 to be turned off, the second MOS tube Q2 to be turned on, the third MOS tube Q3 to be turned off, and the fourth MOS tube Q4 to be turned off, so that the input end IN is connected with the output end OUT directly through the body diode of the first MOS tube Q1 and the second MOS tube Q2. At this time, the resistance R has low loss or even no loss, the loss of the whole circuit is reduced to the minimum state, the efficiency of the whole circuit is improved, and the power loss of the circuit is reduced. Meanwhile, in this mode, the first MOS tube Q1 is turned off, and the body diode of the first MOS tube Q1 can realize the anti-backflow function, so as to prevent the overvoltage of the input end IN caused by the voltage of the output end OUT being greater than the voltage of the input end IN, and improve the reliability of the circuit. Further, since the body diode of the first MOS tube Q1 can realize the anti-backflow function, even in the case that there are multiple sub-motor systems in the motor servo control system, the body diode of the first switch module can realize the bus anti-backflow function, so as to reduce the mutual influence between the multiple sub-motor systems and improve the stability of the whole system.

[0042] In step 203, when the power supply circuit is in the brake discharge phase, the first switch module is controlled to be turned on, the second switch module is controlled to be turned on, the third switch module is controlled to be turned off, and the fourth switch module is controlled to be turned on, or the first switch module is controlled to be turned off, the second switch module is controlled to be turned on, the third switch module is controlled to be turned off, and the fourth switch module is controlled to be turned on.

[0043] Specifically, when the motor brake, that is, the motor stops running, the voltage of the output end OUT of the power supply circuit increases, the second capacitor C2 is charged, the voltage of the second capacitor C2 increases, and the voltage of the second capacitor C2 and the voltage of the output end OUT are both greater than the voltage of the input end IN. At this time, whether the power supply circuit is in the brake discharge phase can be determined by comparing the voltage of the second capacitor C2 or the voltage of the output end OUT with the preset voltage, that is, the voltage of the input end IN.

[0044] When the power supply circuit is in the brake discharge phase, a discharge loop needs to be formed to discharge the excess electric energy of the second capacitor C2. The controller can discharge the excess electric energy of the second capacitor C2 in the following two modes:

[0045] The first mode is that the controller controls the first MOS tube Q1 to be turned on, the second MOS tube Q2 to be turned on, the third MOS tube Q3 to be turned off, and the fourth MOS tube Q4 to be turned on, so that the resistance R and the fourth MOS tube Q4 form a discharge loop, and the resistance R releases the excess electric energy in the second capacitor C2.

[0046] The second mode is that the controller controls the first MOS tube Q1 to be turned off, the second MOS tube Q2 to be turned on, the third MOS tube Q3 to be turned off, and the fourth MOS tube Q4 to be turned on. The resistor R and the fourth MOS tube Q4 form a discharge circuit, and the resistor R releases the excess electrical energy in the second capacitor C2. At the same time, the first MOS tube Q1 is turned off, and the body diode of the first MOS tube Q1 can realize the anti-inversion function, preventing the voltage of the output terminal OUT from being greater than the voltage of the input terminal IN, so as to prevent the overvoltage of the input terminal IN and maintain the voltage of the first capacitor C1 stable, thereby improving the reliability of the circuit.

[0047] It should be noted that the above description takes the preset voltage as the voltage of the input terminal IN as an example. In actual application, the preset voltage can be slightly greater than the voltage of the input terminal IN, and the specific value is set according to actual needs, which is not limited in the embodiment.

[0048] In step 204, after the brake discharge phase of the power supply circuit ends, the first switch module is turned off, the second switch module is turned on, the third switch module is turned off, and the fourth switch module is turned off.

[0049] Specifically, when the excess electrical energy in the second capacitor C2 is discharged, and the voltage of the second capacitor C2 or the voltage of the output terminal OUT is less than the preset voltage, i.e., the voltage of the input terminal IN, the brake discharge phase of the power supply circuit ends.

[0050] In the first mode of discharging the excess electrical energy of the second capacitor C2, the resistor R and the long connecting line thereof have stray inductance. If the controller directly controls the fourth MOS tube Q4 to be turned off, the fourth MOS tube Q4 will be damaged by the stray inductance, which reduces the service life of the circuit. Therefore, after the brake discharge phase of the power supply circuit ends, the controller controls the first MOS tube Q1 to be turned off, the second MOS tube Q2 to be turned on, the third MOS tube Q3 to be turned off, and the fourth MOS tube Q4 to be turned off. At this time, the stray inductance of the resistor R and the long connecting line thereof can be discharged through the body diode of the third MOS tube Q3 and the second MOS tube Q2, thereby avoiding the overvoltage of the fourth MOS tube Q4 when it is turned off.

[0051] In the second method of discharging excess charge from the second capacitor C2, since the first MOSFET Q1 is off, it is only necessary to control the fourth MOSFET Q4 to switch to the off state. That is, after the braking discharge phase of the power supply circuit ends, the controller controls the first MOSFET Q1 to remain off and the second MOSFET Q2 to remain on, and controls the third MOSFET Q3 to remain off and the fourth MOSFET Q4 to switch to the off state. At this time, the stray inductance of the resistor R and its long connecting line can be freewheeled through the body diode of the third MOSFET Q3 and the second MOSFET Q2, thereby avoiding overvoltage when the fourth MOSFET Q4 is turned off.

[0052] This application also provides a motor servo control system, such as... Figure 4 The diagram shown is a schematic of the circuit structure of the motor servo control system of this embodiment, including: inverter 20, motor M, and power supply circuit of the above embodiment; the power supply circuit includes: first switch module 101, second switch module 102, third switch module 103, fourth switch module 1104, first capacitor C1, second capacitor C2, and resistor R; the output terminal of the power supply circuit is connected to the DC terminal of inverter 20, and the AC terminal of inverter 20 is connected to motor M.

[0053] The motor servo control system in this embodiment uses the power supply circuit described above. By reusing a single resistor R, it can realize the functions of the soft power-on resistor in the soft power-on circuit during the power-on phase and the discharge brake resistor in the discharge circuit during the brake discharge phase. This reduces the overall size of the motor servo control system. Furthermore, since the entire motor servo control system only needs to set up switching devices and resistor R, the complexity of wiring and thermal design is reduced, as is the power loss under normal operating conditions. Thus, while the motor servo control system has soft power-on current limiting and brake discharge functions, the system size and power consumption are reduced.

[0054] It should be noted that in complex multi-motor systems, to avoid mutual interference between motor subsystems, diodes or SCRs (Silicon Controlled Rectifiers) are connected in series in the power supply path of each subsystem to achieve bus backflow prevention. This ensures that when one subsystem's motor undergoes regenerative braking (brake discharge), the bus voltage of other subsystems remains stable. However, this approach increases the complexity of the entire system and results in high power losses in the absence of overvoltage or regenerative braking, thus reducing overall system efficiency. In contrast, the motor servo control system of this embodiment includes the power supply circuit described in the previous embodiment. The body diode of the first switching module alone can achieve bus backflow prevention, eliminating the need to connect diodes or SCRs in series in the power supply path of each subsystem. This improves overall system efficiency while also reducing the overall system size.

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

[0056] Those skilled in the art can understand that the above embodiments are specific embodiments for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application.

Claims

1. A power supply circuit, characterized by comprising: Comprise: The first switch module, the second switch module, the third switch module, the fourth switch module, the first capacitor, the second capacitor, the resistance; The first end of the first switch module is the input end of the power supply circuit, the second end of the first switch module is connected with the first end of the second switch module, and the second end of the second switch module is the output end of the power supply circuit; 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, and the second end of the second capacitor is grounded; The first end of the third switch module is connected with the second 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 resistance is connected with the second end of the second switch module, and the second end of the resistance is connected with the first end of the fourth switch module; In the power-on phase 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 resistance; in the brake bleeding phase of the power supply circuit, a bleeding loop is formed by the resistance and the fourth switch module.

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 of claim 2, wherein, The power switch device is at least any one of the following: MOS tube, IGBT tube.

4. The power supply circuit according to any one of claims 1 to 3, characterized by 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 of claim 3, wherein, The first switch module and the second switch module are PMOS tubes, and the third switch module and the fourth switch module are NMOS tubes.

6. A control method of a power supply circuit, characterized by, The controller is connected with the control end of the first switch module, the control end of the second switch module, the control end of the third switch module and the control end of the fourth switch module of the power supply circuit in any one of claims 1 to 5; the control method comprises: In the case that the power supply circuit is in the power-on phase, the first switch module is controlled to be turned off, the second switch module is controlled to be turned off, the third switch module is controlled to be turned on, and the fourth switch module is controlled to be turned off; In the case that the power supply circuit is in the brake bleeding phase, the first switch module is controlled to be turned on, the second switch module is controlled to be turned on, the third switch module is controlled to be turned off, and the fourth switch module is controlled to be turned on, or the first switch module is controlled to be turned off, the second switch module is controlled to be turned on, the third switch module is controlled to be turned off, and the fourth switch module is controlled to be turned on.

7. The control method of a power supply circuit according to claim 6, wherein After the power supply circuit is powered on, the first switch module is controlled to be turned on, the second switch module is controlled to be turned on, the third switch module is controlled to be turned off, and the fourth switch module is controlled to be turned off, or the first switch module is controlled to be turned off, the second switch module is controlled to be turned on, the third switch module is controlled to be turned off, and the fourth switch module is controlled to be turned off.

8. The control method of a power supply circuit according to claim 6, wherein After the brake bleeding phase of the power supply circuit ends, the first switch module is controlled to be turned off, the second switch module is controlled to be turned on, the third switch module is controlled to be turned off, and the fourth switch module is controlled to be turned off.

9. A control method of a power supply circuit according to any one of claims 6 to 8, characterized by, In the case that the voltage of the second capacitor or the output voltage of the power supply circuit exceeds a preset voltage, the power supply circuit is in a brake bleeding phase; in the case that the voltage of the second capacitor or the output voltage of the power supply circuit is less than the preset voltage, the brake bleeding phase of the power supply circuit ends.

10. An electric motor servo control system characterized by comprising: Comprise: an inverter, a motor, the power supply circuit according to any one of claims 1 to 5; an output end of the power supply circuit is connected to a direct current end of the inverter, and an alternating current end of the inverter is connected to the motor.

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