A servo system soft start circuit based on discharge resistance multiplexing

Abstract

The application discloses a kind of based on discharge resistance multiplexing servo system soft start circuit, it is related to servo drive power supply control technical field, to solve the problem that existing servo system in soft start current-limiting resistor and discharge resistor are set respectively, resulting in higher hardware cost and larger circuit board space occupation;Circuit includes rectifier module, bus filter module, soft start module and discharge module;Soft start module includes multiplexing resistance unit, makes multiplexing resistance unit access current-limiting charging path in soft start stage, and bypasses multiplexing resistance unit after soft start ends;Discharge module makes multiplexing resistance unit access discharge path of bus filter module in discharge stage.The application considers soft start current-limiting and bus discharge by multiplexing resistance unit, reduces hardware cost, and reduces circuit board space occupation.

Description

Technical Field

[0001] This invention relates to the field of servo drive power supply control technology, and specifically to a soft-start circuit for a servo system based on discharge resistor reuse. Background Technology

[0002] Servo systems are widely used in industrial robots, CNC machine tools, automated production lines, and precision motion control equipment. Servo systems typically include a rectifier circuit and a DC bus. The AC input power is rectified and charges the bus capacitor to form a relatively stable DC bus voltage, which powers the subsequent inverter and motor drive circuits. Since the bus capacitor is usually quite large, directly charging it during the initial power-up phase can easily generate a large instantaneous inrush current. Therefore, existing servo systems typically include a soft-start circuit. This circuit uses a current-limiting resistor to limit the initial charging current of the bus capacitor and bypasses the current-limiting resistor after the bus voltage is established, allowing the system to enter normal power supply mode.

[0003] In existing servo systems, the soft-start circuit typically uses a separate soft-start current-limiting resistor and its bypass device. Simultaneously, to release the energy stored in the bus capacitor or dissipate the feedback energy generated during servo braking, a corresponding discharge resistor and discharge control circuit are also required. Therefore, the soft-start current-limiting resistor and the discharge resistor are usually arranged as two independent power resistors on the circuit board. Although both primarily consume or limit energy through resistance at different operating stages, existing circuits fail to effectively reuse them. On the one hand, setting up a separate soft-start current-limiting resistor increases the number of power devices and the circuit hardware cost; on the other hand, power resistors themselves have a certain size and require reserved board space and safety clearance, thus limiting the circuit board layout. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a servo system soft start circuit based on discharge resistor reuse to overcome the shortcomings of the prior art, which is that the soft start current limiting resistor and discharge resistor are set separately in the existing servo system, resulting in a large number of power resistor devices, high hardware cost and large space occupied on the circuit board.

[0005] The technical solution is as follows: A soft-start circuit for a servo system based on discharge resistor multiplexing includes: A rectifier module is used to rectify the input AC power and has a first DC terminal and a second DC terminal; The bus filter module is connected between the positive terminal of the bus and the second DC terminal, and is used to filter the rectified DC power. A soft-start module is connected between the first DC terminal and the positive terminal of the bus. The soft-start module includes a multiplexed resistor unit, which is used to connect the multiplexed resistor unit to the current-limiting charging path between the first DC terminal and the positive terminal of the bus during the soft-start phase, and to bypass the multiplexed resistor unit after the soft-start is completed. The discharge module is connected to the multiplexed resistor unit and the second DC terminal respectively, and is used to connect the multiplexed resistor unit to the discharge path of the bus filter module during the discharge phase.

[0006] Furthermore, the rectifier module includes an input protection unit and a rectifier unit; The input protection unit is connected between the input AC power supply and the rectifier unit, and is used to provide input protection for the input AC power. The rectifier unit includes a three-phase rectifier bridge for rectifying three-phase AC power. The two DC output terminals of the three-phase rectifier bridge are respectively formed as the first DC terminal and the second DC terminal. The bus filter module includes a bus filter unit, which includes at least one bus capacitor connected between the positive terminal of the bus and the second DC terminal.

[0007] Furthermore, the soft start module includes a current limiting unit and a bypass unit; The current limiting unit includes the multiplexed resistor unit and the unidirectional conduction unit. The multiplexed resistor unit and the unidirectional conduction unit are connected in series between the first DC terminal and the positive terminal of the bus to form the current limiting charging path. The bypass unit is connected in parallel with the current limiting unit and is used to selectively bypass the current limiting unit in order to establish a power supply path between the first DC terminal and the positive terminal of the bus.

[0008] Furthermore, the multiplexing resistor unit includes a discharge resistor, the unidirectional conduction unit includes a diode, the first end of the discharge resistor is connected to the first DC terminal, the second end of the discharge resistor is connected to the anode of the diode, and the cathode of the diode is connected to the positive terminal of the bus. The bypass unit includes a relay, the switching contacts of which are connected between the first DC terminal and the positive node of the bus, and are connected in parallel with the series branch formed by the discharge resistor and the diode.

[0009] Furthermore, the discharge module includes a discharge switch unit, and the discharge switch unit includes a discharge switch tube; The first end of the discharge switch is connected to the connection node between the discharge resistor and the diode, and the second end of the discharge switch is connected to the second DC terminal. When the relay's switch contacts are closed and the discharge switch is turned on, the positive terminal of the busbar forms the discharge path with the second DC terminal via the relay's switch contacts, the discharge resistor, and the discharge switch.

[0010] Furthermore, it also includes a bus voltage detection module, which is connected between the positive terminal of the bus and the second DC terminal, and is used to detect the bus voltage at both ends of the bus filter module and generate a bus voltage sampling signal; The bus voltage detection module includes a voltage divider sampling unit, a protection unit, and a signal conditioning unit; The voltage divider sampling unit is used to perform voltage divider sampling on the bus voltage to obtain a voltage divider sampling signal; The protection unit is connected to the voltage divider sampling unit and is used to provide voltage limiting protection for the voltage divider sampling signal; The signal conditioning unit is connected to the voltage divider sampling unit and is used to condition the voltage divider sampling signal to obtain the bus voltage sampling signal.

[0011] Furthermore, the voltage divider sampling unit includes a first resistor chain, a second resistor chain, and a filter capacitor. The first resistor chain is connected to the positive terminal of the bus, the second resistor chain is connected to the second DC terminal, and the filter capacitor is connected between the first resistor chain and the second resistor chain. The protection unit includes a voltage limiting protection device, which is connected between the first resistor chain and the second resistor chain; The signal conditioning unit includes an operational amplifier and a feedback resistor. The two input terminals of the operational amplifier are respectively connected to the two sampling output terminals of the voltage divider sampling unit. The feedback resistor is connected between the output terminal of the operational amplifier and one of its input terminals. The output terminal of the operational amplifier is used to output the bus voltage sampling signal.

[0012] Furthermore, it also includes a threshold detection module, which is connected to the bus voltage detection module. The threshold detection module includes an undervoltage detection unit and a pump-up detection unit. The undervoltage detection unit includes a first reference unit, a first comparison unit, and a first isolation output unit. The first reference unit is used to generate a first reference signal, the first comparison unit is used to compare the bus voltage sampling signal with the first reference signal, and the first isolation output unit is used to generate an undervoltage detection signal based on the comparison result of the first comparison unit. The pump-up detection unit includes a second reference unit, a second comparison unit, and a second isolation output unit. The second reference unit is used to generate a second reference signal, the second comparison unit is used to compare the bus voltage sampling signal with the second reference signal, and the second isolation output unit is used to generate a pump-up detection signal based on the comparison result of the second comparison unit.

[0013] Furthermore, it also includes a main control module and a soft start control module; The main control module is connected to the threshold detection module and is used to generate a soft start control signal based on the undervoltage detection signal and a discharge control signal based on the pump-up detection signal. The soft start control module is connected between the main control module and the relay, and the soft start control module includes an isolation unit and a switch drive unit; The isolation unit includes a first optocoupler for isolating and transmitting the soft-start control signal; The switch driving unit includes a first switching transistor, the control terminal of which is connected to the output terminal of the first optocoupler, and the output terminal of which is connected to the coil of the relay, for driving the switch contacts of the relay to open and close according to the soft start control signal after isolation transmission.

[0014] Furthermore, it also includes a discharge control module, which is connected between the main control module and the discharge switch tube. The discharge control module includes an isolation drive unit and a drive output unit. The isolation drive unit includes a second optocoupler for isolated transmission of the discharge control signal; The drive output unit is connected between the output terminal of the second optocoupler and the control terminal of the discharge switch tube, and is used to generate a discharge drive signal according to the discharge control signal after isolation transmission, so as to drive the discharge switch tube to turn on or off.

[0015] This invention, through the inclusion of a soft-start module and a discharge module, allows the multiplexed resistor unit in the soft-start module to be connected to the current-limiting charging path during the soft-start phase and bypassed after the soft-start is completed. During the discharge phase, the discharge module connects the same multiplexed resistor unit to the discharge path of the bus filter module. This enables the same resistor device to perform both soft-start current limiting and bus discharge functions, reducing the need for independently configured power resistor devices, which is beneficial for reducing circuit hardware costs, minimizing circuit board space occupation, and improving the compactness of the circuit layout. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the module structure of the soft-start circuit of the servo system based on the multiplexing of discharge resistors in an embodiment of the present invention; Figure 2 This is a schematic diagram of the circuit structure of the rectifier module, bus filter module, soft starter module and discharge module in an embodiment of the present invention; Figure 3 This is a schematic diagram of the circuit structure of the bus voltage detection module in an embodiment of the present invention; Figure 4 This is a schematic diagram of the circuit structure of the threshold detection module in an embodiment of the present invention; Figure 5 This is a schematic diagram of the circuit structure of the soft start control module in an embodiment of the present invention; Figure 6 This is a schematic diagram of the circuit structure of the discharge control module in an embodiment of the present invention.

[0018] Figure label: 100. Rectifier module; 110. Input protection unit; 120. Rectifier unit; 200. Busbar Filtering Module; 300. Soft starter module; 310. Current limiting unit; 320. Bypass unit; 400. Discharge module; 500. Bus voltage detection module; 510. Voltage divider sampling unit; 520. Protection unit; 530. Signal conditioning unit; 600. Threshold detection module; 610. Undervoltage detection unit; 620. Pump rise detection unit; 700. Main control module; 800. Soft start control module; 810. Isolation unit; 820. Switch drive unit; 900. Discharge control module; 910. Isolation drive unit; 920. Drive output unit. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings.

[0020] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive element, but such modifications are protected by patent law as long as they fall within the scope of the claims of the present invention.

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] In one embodiment, such as Figure 1 As shown, a soft-start circuit for a servo system based on discharge resistor multiplexing is provided, including a rectifier module 100, a bus filter module 200, a soft-start module 300, a discharge module 400, a bus voltage detection module 500, a threshold detection module 600, a main control module 700, a soft-start control module 800, and a discharge control module 900.

[0024] The rectifier module 100 has a first DC terminal and a second DC terminal. The first DC terminal is connected to the positive bus node via the soft-start module 300, and the bus filter module 200 is connected between the positive bus node and the second DC terminal. The rectifier module 100 receives input AC power and outputs rectified DC power. The soft-start module 300 establishes a current-limiting charging path during the servo system's power-on process and establishes a bypass power supply path between the first DC terminal and the positive bus node after the soft start is completed. The discharge module 400 is connected to the multiplexed resistor unit and the second DC terminal in the soft-start module 300, respectively, and is used to connect the multiplexed resistor unit to the discharge path of the bus filter module 200 during the discharge phase. The bus voltage detection module 500 is connected to the bus filter module 200 and is used to acquire the bus voltage and generate a bus voltage sampling signal. The threshold detection module 600 is connected between the bus voltage detection module 500 and the main control module 700 and is used to generate a corresponding detection signal based on the bus voltage sampling signal and output the detection signal to the main control module 700.

[0025] Furthermore, the main control module 700 is connected to the soft start control module 800 and the discharge control module 900, respectively. The soft start control module 800 is further connected to the soft start module 300, enabling the main control module 700 to control the operating state of the soft start module 300 through the soft start control module 800; the discharge control module 900 is further connected to the discharge module 400, enabling the main control module 700 to control the operating state of the discharge module 400 through the discharge control module 900. Thus, the circuit forms a main power path consisting of rectification, soft start, and bus filtering, and a detection and control path consisting of bus voltage detection, threshold detection, main control, and corresponding control modules.

[0026] In one embodiment, reference is made to Figure 2 The rectifier module 100 includes an input protection unit 110 and a rectifier unit 120. The input protection unit 110 is connected between the input AC power supply and the rectifier unit 120, and is used to protect the input AC power. Specifically, the input AC power supply can be a three-phase AC power supply, connected to the input protection unit 110 through the R, S, and T three-phase input terminals. The input protection unit 110 may include varistor devices RV1, RV2, and RV3, and capacitors C1, C2, and C3. Varistors RV1, RV2, and RV3 are connected between the three-phase input lines to limit the overvoltage amplitude when a transient overvoltage occurs on the input side. Capacitors C1, C2, and C3 are respectively connected between the corresponding input line and the protective ground terminal PE to suppress high-frequency interference on the input side. Through this structure, surges and interference on the input side can be suppressed before the AC power enters the rectifier unit 120.

[0027] Specifically, the rectifier unit 120 includes a three-phase rectifier bridge DM1. The three AC input terminals AC1, AC2, and AC3 of the three-phase rectifier bridge DM1 are connected to the corresponding phases of the three-phase AC power supply, respectively, to rectify the input three-phase AC power into DC power. The three-phase rectifier bridge DM1 has a positive DC output terminal P and a negative DC output terminal N, wherein the positive DC output terminal P forms the first DC terminal, and the negative DC output terminal N forms the second DC terminal. Thus, the rectifier unit 120 converts the three-phase AC input into DC power for use by the subsequent bus circuit.

[0028] The positive terminal of the bus is the common connection node between the output side of the soft starter module 300 and the positive terminal of the bus filter module 200.

[0029] Specifically, the bus filter module 200 includes a bus filter unit, which may include a bus capacitor C4 and a bus capacitor C5. The bus capacitor C4 and the bus capacitor C5 are respectively connected between the positive terminal of the bus and the second DC terminal N, and are used to filter the rectified DC power and form a relatively stable DC bus voltage at both ends of the bus.

[0030] In other embodiments, the bus filter module 200 may also be equipped with one or more bus capacitors according to the bus capacity and filtering requirements; this embodiment does not limit this.

[0031] Furthermore, continue to refer to Figure 2 The soft-start module 300 is connected between the first DC terminal P and the positive terminal of the bus. The soft-start module 300 includes a current-limiting unit 310 and a bypass unit 320. The current-limiting unit 310 includes a multiplexed resistor unit and a unidirectional conduction unit. In this embodiment, a discharge resistor R1 is used as the multiplexed resistor unit, and a diode D1 is used as the unidirectional conduction unit. The discharge resistor R1 and the diode D1 are connected in series between the first DC terminal P and the positive terminal of the bus, thereby forming a current-limited charging branch.

[0032] Specifically, the first end of the discharge resistor R1 is connected to the first DC terminal P, the second end of the discharge resistor R1 is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the positive terminal of the bus. Thus, the first DC terminal P, the discharge resistor R1, the diode D1, and the positive terminal of the bus are connected in sequence. The diode D1 is used to limit the current direction in the current-limiting charging branch, allowing current to flow from the first DC terminal P through the discharge resistor R1 to the positive terminal of the bus during the soft-start phase, and cutting off when subjected to reverse voltage.

[0033] Furthermore, the bypass unit 320 and the current limiting unit 310 are connected in parallel. The bypass unit 320 includes a relay RL1, whose switching contacts are connected between the first DC terminal P and the positive terminal of the bus, so that the branch containing the switching contacts of relay RL1 is connected in parallel with the series branch formed by the discharge resistor R1 and the diode D1. By changing the state of the switching contacts of relay RL1, a current path through the current limiting unit 310 or a power supply path bypassing the current limiting unit 310 can be selectively established.

[0034] Optionally, a freewheeling diode D3 can also be connected in parallel across the coil of relay RL1 to provide a freewheeling path when the coil of relay RL1 is de-energized, thereby suppressing the reverse induced voltage generated by the coil.

[0035] Furthermore, the discharge module 400 is connected to the multiplexed resistor unit and the second DC terminal N. Specifically, the discharge module 400 includes a discharge switch unit, which includes a discharge switch transistor Q1. The first end of the discharge switch transistor Q1 is connected to the connection node between the discharge resistor R1 and the diode D1, and the second end of the discharge switch transistor Q1 is connected to the second DC terminal N. When the switch contact of the relay RL1 is closed and the discharge switch transistor Q1 is turned on, the positive terminal of the bus, the switch contact of the relay RL1, the discharge resistor R1, the discharge switch transistor Q1, and the second DC terminal N can sequentially form a discharge path. Thus, the discharge resistor R1 can be connected to the current-limiting charging path and the discharge path through different branches. Since the cathode of the diode D1 is connected to the positive terminal of the bus, during the discharge process, the diode D1 can block the current path flowing from the positive terminal of the bus through the diode D1 to the discharge switch transistor Q1, so that the discharge current on the bus side flows to the second DC terminal N through the switch contact of the relay RL1, the discharge resistor R1, and the discharge switch transistor Q1.

[0036] Furthermore, referring to Figure 3 The bus voltage detection module 500 is connected between the positive terminal of the bus and the second DC terminal N. It is used to detect the bus voltage across the bus filter module 200 and output the bus voltage sampling signal VDC. The bus voltage detection module 500 includes a voltage divider sampling unit 510, a protection unit 520, and a signal conditioning unit 530. The voltage divider sampling unit 510 performs voltage reduction sampling on the bus voltage, the protection unit 520 provides voltage limiting protection for the sampled signal, and the signal conditioning unit 530 further conditions the sampled signal before outputting the bus voltage sampling signal VDC.

[0037] Specifically, the voltage divider sampling unit 510 includes a first resistor chain, a second resistor chain, and a filter capacitor C9. The first resistor chain is connected to the positive terminal of the bus, and the second resistor chain is connected to the second DC terminal N. The two resistor chains divide the voltage across the bus, converting the high voltage on the bus side into a voltage signal suitable for processing by the subsequent detection circuit. In this embodiment, the first resistor chain may include resistors R17, R18, R19, R20, R21, and R22 connected in series, and the second resistor chain may include resistors R9, R10, R11, R12, R13, and R14 connected in series. By sharing the bus voltage through multiple resistors connected in series, the voltage borne by a single resistor can be reduced.

[0038] Furthermore, the filter capacitor C9 is connected between the sampling nodes of the first and second resistor chains to filter the sampling signals formed by the two resistor chains, reducing the impact of high-frequency disturbances in the bus voltage on the subsequent detection results. The voltage divider sampling unit 510 can also be equipped with resistors R15 and R23, which are respectively connected between the sampling nodes of the corresponding resistor chains and the subsequent circuits, so as to lead the voltage-divided sampling signals to the protection unit 520 and the signal conditioning unit 530.

[0039] Specifically, the end of resistor R23 furthest from resistor R22 forms the first sampling output terminal corresponding to the first resistor chain, and the end of resistor R15 furthest from resistor R14 forms the second sampling output terminal corresponding to the second resistor chain. The first sampling output terminal and the second sampling output terminal respectively provide the voltage-divided sampling signal to the protection unit 520 and the signal conditioning unit 530.

[0040] Furthermore, the protection unit 520 includes a voltage limiting protection device D5, which is connected between the sampling outputs corresponding to the first and second resistor chains. When a transient overvoltage or abnormal voltage occurs in the sampling signal, the voltage limiting protection device D5 can limit the voltage amplitude between the sampling outputs, thereby reducing the impact of abnormal sampling voltage on the subsequent signal conditioning unit 530.

[0041] Furthermore, the signal conditioning unit 530 includes an operational amplifier U1A and a feedback resistor R16. The two input terminals of the operational amplifier U1A are respectively connected to the two sampling output terminals of the voltage divider sampling unit 510, and the feedback resistor R16 is connected between the output terminal of the operational amplifier U1A and one of its input terminals. The operational amplifier U1A performs signal conditioning based on the two sampled signals and outputs a bus voltage sampling signal VDC corresponding to the bus voltage through its output terminal for use by the subsequent threshold detection module 600.

[0042] Optionally, the signal conditioning unit 530 may also include a resistor R24 ​​and a capacitor C10. The resistor R24 ​​is connected between the corresponding input terminal of the operational amplifier U1A and the analog ground AGND, and the capacitor C10 is connected between the power supply terminal of the operational amplifier U1A and the analog ground AGND, so as to form a corresponding input bias and power supply filtering.

[0043] Furthermore, referring to Figure 4 The bus voltage sampling signal VDC output by the bus voltage detection module 500 is further input to the threshold detection module 600. The threshold detection module 600 includes an undervoltage detection unit 610 and a pump-up detection unit 620. The undervoltage detection unit 610 is used to generate an undervoltage detection signal based on the bus voltage sampling signal VDC, and the pump-up detection unit 620 is used to generate a pump-up detection signal based on the bus voltage sampling signal VDC.

[0044] Specifically, the undervoltage detection unit 610 includes a first reference unit, a first comparison unit, and a first isolated output unit. The first reference unit may include resistors R71 and R80, which are connected in series between the reference signal REFS and analog ground AGND. The connection node between them forms the first reference signal DCUV_REF. The first comparison unit may include an operational amplifier U10A, which compares the bus voltage sampling signal VDC with the first reference signal DCUV_REF. The first isolated output unit may include an optocoupler OP15. The bus voltage sampling signal VDC and the first reference signal DCUV_REF are respectively input to the operational amplifier U10A, which compares them and outputs a corresponding level signal based on the comparison result. This comparison result is further input to the optocoupler OP15, and after isolation and transmission via the optocoupler OP15, an undervoltage detection signal DCUV is formed for subsequent processing by the main control module 700.

[0045] Furthermore, the pump-up detection unit 620 includes a second reference unit, a second comparison unit, and a second isolated output unit. The second reference unit may include resistors R95 and R101, which are connected in series between the reference signal REFS and analog ground AGND. The connection node between them is used to form the second reference signal BRPC_REF. The second comparison unit may include an operational amplifier U12A, which compares the bus voltage sampling signal VDC and the second reference signal BRPC_REF. The second isolated output unit may include an optocoupler OP16. The bus voltage sampling signal VDC and the second reference signal BRPC_REF are respectively input to the operational amplifier U12A, which compares them and outputs a corresponding level signal based on the comparison result. This comparison result is further input to the optocoupler OP16, and after isolation and transmission via the optocoupler OP16, a pump-up detection signal BRPC is formed for subsequent processing by the main control module 700.

[0046] Optionally, the first comparator unit may also be equipped with a feedback resistor R82, which is connected between the output of operational amplifier U10A and the corresponding comparator input; the second comparator unit may also be equipped with a feedback resistor R102, which is connected between the output of operational amplifier U12A and the corresponding comparator input. By forming a corresponding comparison hysteresis through the feedback resistors R82 and R102, the frequent switching of the undervoltage detection signal DCUV or the pump-up detection signal BRPC when the bus voltage fluctuates near the corresponding threshold can be reduced.

[0047] Specifically, the undervoltage detection unit 610 may further include resistors R69 and R79, a filter capacitor C104, and resistor R60. Resistor R69 is positioned between the bus voltage sampling signal VDC and operational amplifier U10A; resistor R79 is positioned between the first reference signal DCUV_REF and operational amplifier U10A; filter capacitor C104 is connected between the two input paths of operational amplifier U10A; and resistor R60 is positioned on the input side of optocoupler OP15. The pump-up detection unit 620 may further include resistors R91 and R100, a filter capacitor C109, and resistor R89. Resistor R91 is positioned between the bus voltage sampling signal VDC and operational amplifier U12A; resistor R100 is positioned between the second reference signal BRPC_REF and operational amplifier U12A; filter capacitor C109 is connected between the two input paths of operational amplifier U12A; and resistor R89 ​​is positioned on the input side of optocoupler OP16.

[0048] Furthermore, the main control module 700 is connected to the threshold detection module 600 to receive the undervoltage detection signal DCUV and the pump-up detection signal BRPC output by the threshold detection module 600, and to generate corresponding control signals according to different detection signals.

[0049] The main control module 700 may include a microcontroller, a digital signal processor, a programmable logic device, or other control devices that can output corresponding control signals according to the input detection signal. This embodiment does not specifically limit this.

[0050] Specifically, the main control module 700 generates a soft-start control signal based on the level of the undervoltage detection signal DCUV, and outputs the soft-start control signal to the soft-start control module 800 so that the soft-start control module 800 can further control the soft-start module 300. The main control module 700 also generates a discharge control signal based on the level of the pump rise detection signal BRPC, and outputs the discharge control signal to the discharge control module 900 so that the discharge control module 900 can further control the discharge module 400.

[0051] Furthermore, referring to Figure 5 The soft start control module 800 is connected between the main control module 700 and the relay RL1, and is used to control the opening and closing of the switch contacts of the relay RL1 according to the soft start control signal output by the main control module 700. The soft start control module 800 includes an isolation unit 810 and a switch drive unit 820.

[0052] Specifically, the isolation unit 810 includes a first optocoupler OP2. The soft start control signal C_RLY output by the main control module 700 is input to the first optocoupler OP2 via resistor R6. The first optocoupler OP2 isolates the soft start control signal C_RLY, thereby achieving electrical isolation between the control side where the main control module 700 is located and the relay drive side, and outputs the isolated soft start control signal to the switch drive unit 820.

[0053] Furthermore, the switch driving unit 820 includes a first switching transistor Q2. The control terminal of the first switching transistor Q2 is connected to the output terminal of the first optocoupler OP2, and the output terminal of the first switching transistor Q2 is connected to the coil of the relay RL1. The switch driving unit 820 may also include resistors R7 and R8, a filter capacitor C8, and a voltage regulator ZD2, used to perform corresponding biasing, filtering, and voltage limiting processing on the driving signal output by the first optocoupler OP2. The first switching transistor Q2 changes its conduction state according to the soft-start control signal after isolation transmission to control the energization state of the coil of the relay RL1, thereby controlling the opening and closing of the switch contacts of the relay RL1.

[0054] Furthermore, referring to Figure 6 The discharge control module 900 is connected between the main control module 700 and the discharge switch Q1, and is used to control the discharge switch Q1 to turn on or off according to the discharge control signal output by the main control module 700. The discharge control module 900 includes an isolation drive unit 910 and a drive output unit 920.

[0055] Specifically, the isolation drive unit 910 includes a second optocoupler OP1. The discharge control signal C_Br output by the main control module 700 is input to the second optocoupler OP1. The second optocoupler OP1 performs isolated transmission of the discharge control signal C_Br to isolate the control side where the main control module 700 is located and the drive side where the discharge module 400 is located. The output terminal of the second optocoupler OP1 is connected to the drive output unit 920 and is used to output the isolated discharge control signal to the drive output unit 920.

[0056] Furthermore, the drive output unit 920 is connected between the output terminal of the second optocoupler OP1 and the control terminal of the discharge switch Q1. Specifically, the drive output unit 920 may include resistors R4 and R5, a filter capacitor C7, and a voltage regulator ZD1. The signal output from the second optocoupler OP1 is processed by the drive output unit 920 to form a discharge drive signal BrDrive. The discharge drive signal BrDrive is further output to... Figure 2 The control terminal of the discharge switch transistor Q1 in the discharge module 400 is used to control the discharge switch transistor Q1 to be turned on or off, thereby realizing the control of the discharge module 400 by the main control module 700.

[0057] Alternatively, the isolation drive unit 910 may also include resistors R2 and R3 and capacitor C6. Resistor R2 is located between the discharge control signal C_Br and the input side of the second optocoupler OP1, resistor R3 is connected to the power supply path of the input side of the second optocoupler OP1, and capacitor C6 is connected between the power supply node VNI of the output side of the second optocoupler OP1 and the second DC terminal N.

[0058] The working principle of this invention is as follows: The operating states of the servo system's soft start circuit can include soft start state, normal power supply state, and discharge state. The discharge state can be entered during normal operation of the servo system based on the bus voltage status.

[0059] In soft-start mode, the three-phase AC power is input to the rectifier unit 120 after passing through the input protection unit 110, and is rectified by the three-phase rectifier bridge DM1 to form the first DC terminal P and the second DC terminal N. At this time, the switching contacts of relay RL1 have not yet established a bypass power supply path between the first DC terminal P and the positive node of the bus. Simultaneously, the discharge switch Q1 remains off. The rectified current flows through the first DC terminal P, sequentially through the discharge resistor R1 and the diode D1, and then enters the positive node of the bus. It then returns to the second DC terminal N through the bus capacitors C4 and C5, thus forming a current-limiting charging path consisting of the first DC terminal P, the discharge resistor R1, the diode D1, the positive node of the bus, the bus capacitor, and the second DC terminal N. During this stage, the discharge resistor R1 is connected in series in the charging path of the bus capacitor to limit the charging current of the bus capacitors C4 and C5. Therefore, the discharge resistor R1 also functions as a soft-start current-limiting resistor.

[0060] As bus capacitors C4 and C5 charge, the bus voltage detection module 500 continuously acquires the bus voltage and outputs a bus voltage sampling signal VDC. The threshold detection module 600 generates a corresponding detection signal based on the bus voltage sampling signal VDC. When the level of the undervoltage detection signal DCUV output by the undervoltage detection unit 610 indicates that the bus voltage has reached the control condition corresponding to the soft start termination, the main control module 700 generates a soft start control signal based on the undervoltage detection signal DCUV and outputs the soft start control signal to the soft start control module 800. The soft start control module 800 drives the relay RL1 according to the soft start control signal, causing the switch contacts of the relay RL1 to close, thereby establishing a bypass power supply path between the first DC terminal P and the positive node of the bus, and bypassing the current-limiting branch where the discharge resistor R1 and diode D1 are located. Afterwards, the rectified DC power supplies the bus filter module 200 through the bypass power supply path, and the servo system enters the normal power supply stage.

[0061] During normal operation, the bus voltage detection module 500 continues to monitor the bus voltage. When the bus voltage rises and reaches a state requiring discharge, the pump-up detection unit 620 generates a pump-up detection signal BRPC based on the comparison result of the bus voltage sampling signal VDC and the second reference signal BRPC_REF, and outputs the pump-up detection signal BRPC to the main control module 700. The main control module 700 generates a discharge control signal accordingly. After isolation transmission and drive processing by the discharge control module 900, the discharge control signal forms a discharge drive signal BrDrive, which drives the discharge switch Q1 to turn on.

[0062] At this time, the switch contact of relay RL1 is in the closed state. The positive terminal of the bus can be connected to the second DC terminal N in sequence through the switch contact of relay RL1, discharge resistor R1, and discharge switch Q1, thus forming a discharge path consisting of the positive terminal of the bus, the switch contact of relay RL1, discharge resistor R1, discharge switch Q1, and the second DC terminal N. The electrical energy on the bus side is released through the discharge resistor R1. During this stage, the discharge resistor R1 performs the function of the bus discharge resistor.

[0063] After the discharge resistor R1 is connected to the discharge path, it consumes electrical energy on the bus side. When the level of the pump rise detection signal BRPC output by the pump rise detection unit 620 indicates that the bus voltage meets the control conditions for exiting the discharge, the main control module 700 generates a corresponding discharge control signal based on the pump rise detection signal BRPC, and controls the discharge switch Q1 to turn off through the discharge control module 900 to disconnect the discharge path. Thus, the discharge switch Q1 can be turned on or off according to the bus voltage status.

[0064] Therefore, the discharge resistor R1 is connected to the current-limiting charging path during the soft-start phase to undertake the soft-start current-limiting function, and connected to the bus discharge path during the discharge phase to undertake the bus discharge function, so as to realize the function reuse of the same resistor device in different working phases, thus eliminating the need to set up separate soft-start current-limiting resistors and discharge resistors.

[0065] The above is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A soft-start circuit for a servo system based on discharge resistor multiplexing, characterized in that, include: A rectifier module (100) is used to rectify the input AC power and has a first DC terminal and a second DC terminal; The bus filter module (200) is connected between the positive terminal of the bus and the second DC terminal, and is used to filter the rectified DC power. A soft starter module (300) is connected between the first DC terminal and the positive terminal of the bus. The soft starter module (300) includes a multiplexed resistor unit, which is used to connect the multiplexed resistor unit to the current-limiting charging path between the first DC terminal and the positive terminal of the bus during the soft start phase, and to bypass the multiplexed resistor unit after the soft start is completed. The discharge module (400) is connected to the multiplexed resistor unit and the second DC terminal respectively, and is used to connect the multiplexed resistor unit to the discharge path of the bus filter module (200) during the discharge stage.

2. The servo system soft-start circuit based on discharge resistor multiplexing according to claim 1, characterized in that, The rectifier module (100) includes an input protection unit (110) and a rectifier unit (120). The input protection unit (110) is connected between the input AC power supply and the rectifier unit (120) and is used to provide input protection for the input AC power. The rectifier unit (120) includes a three-phase rectifier bridge for rectifying three-phase AC power. The two DC output terminals of the three-phase rectifier bridge are respectively formed as the first DC terminal and the second DC terminal. The bus filter module (200) includes a bus filter unit, which includes at least one bus capacitor connected between the positive terminal of the bus and the second DC terminal.

3. The servo system soft-start circuit based on discharge resistor multiplexing according to claim 1, characterized in that, The soft start module (300) includes a current limiting unit (310) and a bypass unit (320). The current limiting unit (310) includes the multiplexed resistor unit and the unidirectional conduction unit. The multiplexed resistor unit and the unidirectional conduction unit are connected in series between the first DC terminal and the positive terminal of the bus to form the current limiting charging path. The bypass unit (320) is connected in parallel with the current limiting unit (310) to selectively bypass the current limiting unit (310) in order to establish a power supply path between the first DC terminal and the positive terminal of the bus.

4. The servo system soft-start circuit based on discharge resistor multiplexing according to claim 3, characterized in that, The multiplexing resistor unit includes a discharge resistor, the unidirectional conduction unit includes a diode, the first end of the discharge resistor is connected to the first DC terminal, the second end of the discharge resistor is connected to the anode of the diode, and the cathode of the diode is connected to the positive terminal of the bus. The bypass unit (320) includes a relay, the switching contacts of which are connected between the first DC terminal and the positive node of the bus, and are connected in parallel with the series branch formed by the discharge resistor and the diode.

5. The servo system soft-start circuit based on discharge resistor multiplexing according to claim 4, characterized in that, The discharge module (400) includes a discharge switch unit, which includes a discharge switch tube; The first end of the discharge switch is connected to the connection node between the discharge resistor and the diode, and the second end of the discharge switch is connected to the second DC terminal. When the relay's switch contacts are closed and the discharge switch is turned on, the positive terminal of the busbar forms the discharge path with the second DC terminal via the relay's switch contacts, the discharge resistor, and the discharge switch.

6. The servo system soft-start circuit based on discharge resistor multiplexing according to claim 5, characterized in that, It also includes a bus voltage detection module (500), which is connected between the positive terminal of the bus and the second DC terminal, and is used to detect the bus voltage at both ends of the bus filter module (200) and generate a bus voltage sampling signal; The bus voltage detection module (500) includes a voltage divider sampling unit (510), a protection unit (520), and a signal conditioning unit (530). The voltage divider sampling unit (510) is used to perform voltage divider sampling on the bus voltage to obtain a voltage divider sampling signal; The protection unit (520) is connected to the voltage divider sampling unit (510) and is used to provide voltage limiting protection for the voltage divider sampling signal; The signal conditioning unit (530) is connected to the voltage divider sampling unit (510) and is used to condition the voltage divider sampling signal to obtain the bus voltage sampling signal.

7. The servo system soft-start circuit based on discharge resistor multiplexing according to claim 6, characterized in that, The voltage divider sampling unit (510) includes a first resistor chain, a second resistor chain, and a filter capacitor. The first resistor chain is connected to the positive terminal of the bus, the second resistor chain is connected to the second DC terminal, and the filter capacitor is connected between the first resistor chain and the second resistor chain. The protection unit (520) includes a voltage limiting protection device, which is connected between the first resistor chain and the second resistor chain; The signal conditioning unit (530) includes an operational amplifier and a feedback resistor. The two input terminals of the operational amplifier are respectively connected to the two sampling output terminals of the voltage divider sampling unit (510). The feedback resistor is connected between the output terminal of the operational amplifier and one of its input terminals. The output terminal of the operational amplifier is used to output the bus voltage sampling signal.

8. The servo system soft-start circuit based on discharge resistor multiplexing according to claim 6, characterized in that, It also includes a threshold detection module (600), which is connected to the bus voltage detection module (500). The threshold detection module (600) includes an undervoltage detection unit (610) and a pump-up detection unit (620). The undervoltage detection unit (610) includes a first reference unit, a first comparison unit, and a first isolation output unit. The first reference unit is used to generate a first reference signal, the first comparison unit is used to compare the bus voltage sampling signal with the first reference signal, and the first isolation output unit is used to generate an undervoltage detection signal based on the comparison result of the first comparison unit. The pump rise detection unit (620) includes a second reference unit, a second comparison unit, and a second isolation output unit. The second reference unit is used to generate a second reference signal, the second comparison unit is used to compare the bus voltage sampling signal with the second reference signal, and the second isolation output unit is used to generate a pump rise detection signal based on the comparison result of the second comparison unit.

9. The servo system soft-start circuit based on discharge resistor multiplexing according to claim 8, characterized in that, It also includes a main control module (700) and a soft start control module (800); The main control module (700) is connected to the threshold detection module (600) and is used to generate a soft start control signal based on the undervoltage detection signal and a discharge control signal based on the pump rise detection signal. The soft start control module (800) is connected between the main control module (700) and the relay. The soft start control module (800) includes an isolation unit (810) and a switch drive unit (820). The isolation unit (810) includes a first optocoupler for isolating and transmitting the soft-start control signal; The switch driving unit (820) includes a first switch transistor, the control terminal of the first switch transistor is connected to the output terminal of the first optocoupler, and the output terminal of the first switch transistor is connected to the coil of the relay, for driving the switch contacts of the relay to open and close according to the soft start control signal after isolation transmission.

10. The servo system soft-start circuit based on discharge resistor multiplexing according to claim 9, characterized in that, It also includes a discharge control module (900), which is connected between the main control module (700) and the discharge switch tube. The discharge control module (900) includes an isolation drive unit (910) and a drive output unit (920). The isolation drive unit (910) includes a second optocoupler for isolating and transmitting the discharge control signal; The drive output unit (920) is connected between the output terminal of the second optocoupler and the control terminal of the discharge switch tube, and is used to generate a discharge drive signal according to the discharge control signal after isolation transmission, so as to drive the discharge switch tube to turn on or off.

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