A circuit for improving the dynamic performance of a magnetic exciting power take-off generating system

Abstract

The application discloses a circuit for improving the dynamic performance of a magnetic excitation type power take-off power generation system, comprising: an isolation sampling unit, which converts the output voltage of the power take-off generator into a voltage sampling signal after voltage division, and the voltage sampling signal is common with the power take-off power generation control circuit; a hysteresis comparison unit, which compares the voltage sampling signal with a preset value, judges whether the current voltage is too high, and outputs corresponding high and low levels; an excitation adjustment enable control unit, which enables the excitation adjustment circuit according to the comparison unit result, disables the excitation adjustment circuit when the voltage is too high, and reduces the excitation current in the excitation winding to zero; a load shedding control unit, which controls the comparison result level signal output by the hysteresis comparison unit, converts the comparison result level signal into a drive signal for driving the on-off of the next stage load shedding main circuit IGBT; and a load shedding main circuit unit, which is parallelly connected between the positive and negative bus bars on the output side of the power take-off generator, is put into or cut off according to the control signal, and realizes the discharge voltage reduction of the bus bar.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power extraction and power generation control, and particularly relates to a circuit for improving the dynamic performance of load switching of a magnetic excitation type power extraction and power generation system. BACKGROUND

[0002] The magnetic excitation type power extraction generator is a generator that generates a magnetic field by supplying power to the excitation coil to realize power generation output. When the power extraction generator output is needed, the controller outputs appropriate excitation current by starting the excitation regulation circuit to generate N and S magnetic poles in the motor, and when the rotor rotates, a rotating magnetic field is formed. The stator winding cuts the magnetic force line to output three-phase alternating voltage. When the output is not needed, the controller can remove the magnetic field induced in the motor by closing the excitation regulation circuit to turn off the motor output.

[0003] The controller can adjust the excitation current according to the real-time output voltage of the generator. When the output voltage is too large, the excitation regulation circuit unit will reduce the excitation current, thereby reducing the magnetic field strength in the motor and controlling the output voltage to decrease; when the output voltage is too small, the excitation regulation circuit unit will increase the excitation current, thereby increasing the magnetic field strength in the motor and controlling the output voltage to increase. The controller realizes the output voltage stabilization control of the generator through this feedback mechanism.

[0004] When the power extraction generator is loaded or unloaded, the load power instantaneously increases or decreases, and the power extraction control circuit needs to adjust the generator output power to increase or decrease to meet the load use demand. For the magnetic excitation type power extraction generator, the increase and decrease of the output power is realized through the control link of "detecting voltage drop or rise - adjusting excitation current - adjusting the magnetic field strength in the motor - adjusting the output voltage of the stator winding", which needs a certain adjustment time, so during the adjustment process, the output voltage will have a large amplitude drop or rise for a short time. Generally, the worse the dynamic performance of the entire control system, the larger the amplitude of the output voltage drop or rise when the load is switched, and the longer the duration, and the greater the adverse effects on the circuit and the load equipment.

[0005] When the load is put in, the output voltage drops due to insufficient power of the generator for a short time. Since the generator itself is designed to meet the use requirements of the load, the output of the generator can be quickly raised back to the original voltage through adjustment, and the impact is not great. When the load is removed, the output voltage rises due to excessive power of the generator for a short time, which poses a risk of overvoltage damage to the controller and load equipment. When the controller adjusts, the excitation current needs to be reduced, but even if the excitation current is reduced to 0, the voltage that has been raised needs to be released through a certain discharge channel. Especially during the process of removing the load, the discharge channel is only the resistance path of the generator output end, and the discharge speed is extremely low, which makes the generator voltage regulation slow. In summary, the process of removing the load needs more attention to the dynamic performance of the power generation system than the process of putting in the load.

[0006] In terms of improving the dynamic performance index of the power generation system, the common methods currently include: (1) increasing the total amount of the output side capacitor to reduce the amplitude of the output voltage transformation when the load is switched; this method greatly improves the volume and weight of the controller, has certain effect, but the effect is general; (2) optimizing the design scheme of the excitation adjustment circuit of the controller to improve the response speed of the circuit; this method has very limited improvement on the dynamic index of the whole system; (3) optimizing the motor design, and optimizing the output adjustment capability of the motor through the motor parameters; this method has very limited improvement on the dynamic index of the whole system, and needs to greatly change the motor, which has high cost; (4) standardizing the use mode of the load to realize step-by-step input or removal of the load; this method has high requirements for the user load, and has poor adaptability. SUMMARY

[0007] The technical problem to be solved by the present application is to overcome the risk of overvoltage damage to equipment caused by excessive voltage rise for a short time when the load is removed in the current power generation system, and to provide a circuit for improving the dynamic performance of the load removal of the magnetic excitation type power generation system.

[0008] The technical scheme adopted by the present application is:

[0009] A circuit for improving the dynamic performance of the load removal of the magnetic excitation type power generation system, comprising: an isolation sampling unit, a hysteresis comparison unit, an excitation adjustment enable control unit, an unloading control unit, and an unloading main circuit unit.

[0010] The isolation sampling unit reduces the output voltage of the power generation motor by a certain proportion, converts it into a differential signal with the ground of the power generation control circuit, and then processes the voltage sampling signal.

[0011] The hysteresis comparison unit introduces the voltage sampling signal into a comparison circuit, sets a comparison reference value, and when the output voltage of the power take-off generator exceeds the comparison reference value, the output level of the comparison circuit flips from high to low; when the output voltage of the power take-off generator falls below the comparison reference value again, the output level of the comparison circuit flips again from low to high; the comparison result level signal output by the hysteresis comparison unit is used for next-stage control;

[0012] The excitation regulation enabling control unit uses the comparison result level signal output by the hysteresis comparison unit as an enablement to control the working state of the excitation regulation circuit; if the comparison result level signal is high, the excitation regulation circuit is normally enabled to allow it to normally work to output a PWM pulse to make the excitation winding generate an excitation current; if the comparison result level signal is low, the excitation regulation circuit is disabled to turn off its PWM pulse output to make the excitation current in the excitation winding drop to zero;

[0013] The unloading control unit controls by using the comparison result level signal output by the hysteresis comparison unit to convert it into a drive signal for driving the on-off of the next-stage unloading main circuit unit; when the comparison result level signal is low, the unloading main circuit unit is driven to turn on; when the comparison result level signal is high, the unloading main circuit unit is driven to turn off;

[0014] The unloading main circuit unit has a unloading power resistor connected in parallel between the positive and negative bus bars on the output side of the power take-off generator, and the resistor is connected to the DC bus bar through an IGBT device; when the DC bus bar voltage is too high and needs to be unloaded, the unloading control unit timely drives the IGBT device to turn on to connect the unloading power resistor between the positive and negative poles of the DC bus bar, discharge the charge of the bus capacitor through the resistor, and reduce the bus voltage; after the discharging is completed, the unloading control unit drives the IGBT device to turn off to cut off the unloading power resistor, and the residual electricity on the unloading main circuit unit is released.

[0015] Further, the isolation sampling unit includes a voltage dividing circuit, an isolation operational amplifier circuit, and a difference operational amplifier circuit.

[0016] The voltage dividing circuit uses resistors for voltage division, and a plurality of resistors are connected in series between the positive and negative poles of the output voltage of the power take-off generator, and the voltage on the resistor closest to the negative pole is taken as the output of the voltage dividing circuit and introduced into the next-stage isolation operational amplifier circuit.

[0017] The isolation operational amplifier circuit uses an isolation operational amplifier to convert the voltage dividing sampling signal with the negative pole of the power take-off generator as the ground into a differential output voltage and introduce it into the next-stage difference operational amplifier circuit; the differential output voltage is common to the power take-off generator control circuit.

[0018] The difference operational amplifier circuit carries out subtraction operation on the differential voltage signal between the two ends of the former stage, and obtains the output voltage signal of the power generation control circuit, that is, the sampling voltage signal.

[0019] Further, assuming that the voltage between the positive and negative electrodes of the power generation motor is Uin, the output voltage of the voltage dividing circuit is Uo=(R3 / (R1+R2+R3))×Uin; wherein the resistors R1, R2 and R3 are connected in series between the positive and negative electrodes of the generator output voltage, and the resistor R3 is the resistor closest to the negative electrode, and the voltage taken from the resistor R3 is taken as the output voltage of the voltage dividing circuit.

[0020] Further, the isolation operational amplifier circuit comprises an isolation operational amplifier chip, an operational amplifier and a current limiting resistor R4.

[0021] The output voltage Uo of the voltage dividing circuit is directly input to the input end of the operational amplifier after passing through the current limiting resistor R4, and the isolation operational amplifier chip is powered on both sides, wherein the input side power supply Vccp is the power supply shared with the output end of the power generation motor, the output side power supply Vcc is the power supply of the power generation control circuit, and the output differential voltage signal Vp and Vn of the operational amplifier are shared with the power generation control circuit as GND.

[0022] Further, the voltage comparison result level signal of the power generation motor is logically combined with the enable signal for controlling the start and stop of the power generation motor, and after the logical and operation, the final enable signal is obtained, which is used to control the working state of the excitation regulation circuit.

[0023] Further, the unloading control unit comprises an optical coupling isolation circuit and an IGBT driving circuit, and signal isolation and IGBT driving are realized.

[0024] The optical coupling isolation circuit converts the comparison result level signal output by the hysteresis comparison unit into an IGBT driving input signal by using an optical coupling chip, introduces the comparison result level signal into the negative end of the optical coupling input side, connects the positive end to the power supply of the power generation control circuit, realizes the logic control of the optical coupling opening when the input low level, and uses the optical coupling output as the input of the lower IGBT driving circuit.

[0025] The IGBT driving circuit is in a common ground state with the output loop of the power generation motor, and uses the output of the optical coupling isolation circuit as the input level of the driving IGBT; the IGBT driving circuit uses a pair of triodes in PNP and NPN forms to form a push-pull circuit, and realizes the driving of the unloading main circuit unit.

[0026] Further, the optical coupling isolation circuit comprises resistors R5 and R6; the positive terminal of the input side of the optical coupling is pulled up to the power supply Vcc of the power generation control circuit through the resistor R5; the C pole of the output side of the optical coupling is connected to the power supply Vccp, and the E pole is directly used as the input of the lower IGBT drive circuit as the output level, and the pull-down resistor R6 is added to realize the default output of the optical coupling as low level.

[0027] Further, the IGBT drive circuit comprises resistors R7 and R8 and a TVS tube V3; the current limiting resistor R7 is added to the input side of the G pole of the IGBT, the resistor R8 is arranged between the G pole and the E pole of the IGBT, and the voltage peak of the drive signal is suppressed by arranging the TVS tube V3 in parallel with the resistor R8.

[0028] Further, the unloading main circuit unit comprises an unloading resistor branch and a freewheeling branch.

[0029] The unloading resistor branch is composed of an unloading power resistor and an IGBT device in series and is connected in parallel between the direct current positive bus and the direct current negative bus on the output side of the power generator; wherein the IGBT device is used to realize the input and removal of the unloading main circuit unit in the entire generator output link, and the unloading power resistor is used to release the charge amount on the bus after the input of the unloading main circuit unit, so as to realize the reduction of the bus voltage.

[0030] The freewheeling branch is composed of a power diode, and the power diode is connected in parallel on both sides of the unloading power resistor; when the IGBT device is turned off after the discharge of the generator output side is completed, the parasitic inductance on the line at the unloading power resistor can induce a high voltage, and the high voltage is added between the C pole and the E pole of the IGBT device, and the diode of the freewheeling branch is added to avoid the breakdown of the IGBT device.

[0031] Further, the set comparison reference value is 1.1 times of the rated output voltage of the power generator.

[0032] Compared with the prior art, the application has the following advantages:

[0033] (1) The application directly clears the excitation current by closing the enable when the load is removed, and does not need to adjust the current gradually, so the adjustment speed is fast.

[0034] (2) The application temporarily expands the charge discharge channel when the voltage is too high by adding the unloading circuit, so as to realize rapid voltage reduction.

[0035] (3) The application improves the dynamic performance of the power generation system when the load is removed, avoids the short-time overvoltage, and reduces the overvoltage damage risk of the controller and the load equipment.

[0036] (4) In this invention, the voltage adoption and enable control units can be reused with the relevant links of the original power generation control circuit. The newly added circuit is small in size and has a better effect than increasing the capacitor capacity to improve the dynamic performance of the system, and it also saves more space. Attached Figure Description

[0037] Figure 1 This is a diagram showing the connection relationships between the modules of the circuit of this invention;

[0038] Figure 2 This is a schematic diagram of the isolation sampling unit according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the unloading control unit according to an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the unloading main circuit unit according to an embodiment of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0042] A power take-off (PTO) control system is a power supply system that uses a specific control strategy to stabilize the output power of a PTO generator. It mainly consists of two parts: the PTO generator and the PTO control circuit. The PTO generator is used to achieve power output, while the PTO control circuit is used to stabilize the output power of the PTO generator. The PTO control circuit comprises multiple functional circuit modules, including a power supply circuit, a status acquisition circuit, a protection judgment circuit, an excitation regulation circuit, a software circuit, and a communication circuit. The circuit provided in this invention for improving the load-shrinking dynamic performance of a magnetically excited PTO system is also one of these functional circuit modules.

[0043] like Figure 1 As shown, this invention provides a circuit for improving the load shedding dynamic performance of a magnetically excited power take-off (MTO) system. The circuit includes an isolation sampling unit, a hysteresis comparison unit, an excitation regulation enable control unit, a load shedding control unit, and a load shedding main circuit unit.

[0044] The isolation sampling unit reduces the output voltage of the power take-off generator proportionally through a voltage divider circuit, converts it into a differential signal with the power take-off generator control circuit using an isolation operational amplifier chip, and then processes it through the operational amplifier chip to obtain the voltage sampling signal.

[0045] The hysteresis comparison unit introduces the generator output voltage sampling signal from the isolation sampling unit into a comparison circuit composed of an operational amplifier, and sets the comparison reference value to about 1.1 times the rated output voltage of the generator. When the generator output voltage exceeds the comparison reference value, the output level of the comparison circuit flips from high to low; when the generator output voltage drops again below the comparison reference value, the output level of the comparison circuit flips again from low to high. The comparison result level signal output by the hysteresis comparison unit is used for the next stage of control;

[0046] The excitation regulation enabling control unit uses the generator voltage comparison result level signal introduced from the previous stage as an enablement to control the working state of the excitation regulation circuit. If the introduction is high, the excitation regulation circuit is normally enabled, and it is allowed to normally work to output PWM pulses to make the excitation winding generate excitation current; if the introduction is low, the excitation regulation circuit is disabled, and its PWM pulse output is turned off to make the excitation current in the excitation winding drop to zero;

[0047] The unloading control unit controls by using the comparison result level signal output by the hysteresis comparison unit, and converts it into a drive signal for driving the on-off of the IGBT of the next stage of unloading main circuit. When the comparison result is low, the unloading circuit IGBT should be driven to turn on; when the comparison result is high, the unloading circuit IGBT should be driven to turn off;

[0048] The unloading main circuit unit is parallelly connected between the positive and negative bus bars on the output side of the power generator, and the resistance is connected to the DC bus bar through an IGBT device. When the DC bus bar voltage rises too high and needs to be unloaded, the unloading control unit timely drives the IGBT to turn on, and the unloading power resistance is connected between the positive and negative poles of the DC bus bar, so that the charge amount of the bus capacitor is quickly discharged through the resistance to reduce the bus voltage. After the discharging is completed, the unloading control unit quickly drives the IGBT to turn off, and the unloading power resistance is cut off, and the residual electricity on the unloading main circuit is quickly released through the freewheeling branch.

[0049] Preferably, the isolation sampling unit is composed of three circuit modules, namely a voltage dividing circuit, an isolation operational amplifier circuit, and a difference operational amplifier circuit, as shown in Figure 2

[0050] The voltage dividing circuit adopts resistors for voltage division, and a plurality of resistors R1, R2, R3 are connected in series between the positive and negative poles of the generator output voltage, and the voltage on the resistor R3 closest to the negative pole is taken as the output of the voltage dividing circuit and introduced into the next stage of isolation operational amplifier circuit. Assuming that the voltage between the positive and negative poles of the generator output is Uin, the output voltage of the voltage dividing circuit is Uo=(R3 / (R1+R2+R3))×Uin;

[0051] ​The isolated operational amplifier circuit converts the sampling signal of the generator output negative voltage into a differential output voltage, and introduces the differential output voltage into the next stage difference operational amplifier circuit. The isolated operational amplifier can be ISO224 or AMC1200 chip. The output voltage Uo of the previous stage voltage dividing circuit is directly input to the operational amplifier input terminal through the current limiting resistor R4. The isolated operational amplifier needs to be supplied with power on both sides. The input side power supply Vccp is the power supply with the same ground as the output terminal of the power generator. The output side power supply Vcc is the power supply of the power generator control circuit. The operational amplifier output differential voltage signal Vp and Vn have the same ground as the power generator control circuit GND.

[0052] The difference operational amplifier circuit adopts an operational amplifier chip to form a standard difference circuit, and performs subtraction operation on the two ends of the previous stage differential voltage signal to obtain a sampling voltage signal F_Uo which is output to the ground GND of the power generator control circuit.

[0053] Preferably, for the excitation regulation enable control unit, the enable signal for controlling the start and stop of the power generator is usually realized by controlling the enable of the excitation regulation circuit when the power generator system controls the start and stop of the power generation function. Therefore, in this case, for the circuit of the present application, the comparison result level signal introduced from the previous stage and the enable signal for controlling the start and stop of the power generator are logically combined in the excitation regulation enable control unit, and the final enable signal is obtained after logical AND operation, and then used to control the working state of the excitation regulation circuit.

[0054] Preferably, for the unloading control unit, the comparison result level signal belongs to the signal of the power generator control circuit, and the unloading circuit is located on the main loop of the generator output, and the two do not have the same ground. Therefore, the comparison result level signal is first converted by the optocoupler, and then the converted level signal is used to drive the IGBT on-off. Therefore, the unloading control unit is composed of two circuit modules, which are the optocoupler isolation circuit and the IGBT drive circuit, as shown in Figure 3 .

[0055] The optocoupler isolation circuit converts the comparison result level signal output by the hysteresis comparison unit into an IGBT drive input signal by using an optocoupler chip. The optocoupler chip is selected from the single-channel optocoupler chips such as ACPL-217 and TLP176. The comparison result level signal F_ov from the previous stage is introduced into the negative terminal of the optocoupler input side. The positive terminal of the optocoupler input side is pulled up to the power supply Vcc of the power generator control circuit through the resistor R5. In this way, the control logic of turning on the optocoupler when the input is low and turning off the optocoupler when the input is high can be realized. The output side C of the optocoupler is connected to the power supply Vccp, and the output side E is directly used as the input of the next stage IGBT drive circuit, and a pull-down resistor R6 is added to realize the default output (output when the optocoupler is not conducting) of the optocoupler as low level.

[0056] The IGBT driving circuit is in the common ground state with the output loop of the power generator, and the output of the optical coupling isolation circuit is used as the input level of the driving circuit. The driving circuit uses a pair of transistors V1 and V2 in NPN and PNP forms respectively to form a push-pull circuit, and the driving circuit together realizes the driving of the IGBT device of the unloading circuit in the rear stage. The IGBT periphery is configured in a conventional manner: a current limiting resistor R7 is added at the G pole input side of the IGBT, and a TVS tube V3 is added at the resistor R8 between the G and E poles of the IGBT, which is used to suppress the voltage peak of the driving signal.

[0057] Preferably, the unloading main circuit unit is composed of two circuit branches, namely an unloading resistance branch and a freewheeling branch, as shown in the following figure. Figure 4

[0058] The unloading resistance branch is composed of an unloading power resistor R9 and an IGBT device V4 in series, and is connected in parallel between the positive and negative bus bars on the output side of the power generator. The IGBT is used to realize the input and removal of the unloading circuit in the entire generator output link. After the IGBT is turned on, the unloading path is formed between the positive and negative bus bars, and the charge quantity flows into the negative bus bar PGND through the unloading power resistor R9 and the IGBT device V4, and is quickly released, thereby realizing the effect of quickly reducing the bus voltage.

[0059] The freewheeling branch is composed of a power diode V5, and the diode is connected in parallel on both sides of the unloading power resistor R9. When the discharging on the output side of the generator is completed, the unloading control unit needs to turn off the IGBT device V4. At this time, the parasitic inductance on the line at the unloading branch power resistor R9 can induce a high voltage, and the voltage can be added between the C pole and the E pole of the IGBT device V4, which has the risk of breaking down the IGBT device. After the freewheeling branch diode V5 is added, the current of the parasitic inductance on the line when the IGBT is turned off continues to flow through the freewheeling branch power diode V5 and quickly decreases to zero, which can avoid generating a high induced voltage, thereby avoiding the above risk.

[0060] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the above disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

[0061] The contents not described in detail in the specification of the present application belong to the known technology of the person skilled in the art.​

Claims

1. A circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system, characterized in that... include: Isolation sampling unit, hysteresis comparison unit, excitation regulation enable control unit, unloading control unit, unloading main circuit unit; The isolation sampling unit reduces the output voltage of the power take-off generator proportionally, converts it into a differential signal that shares a common ground with the power take-off generator control circuit, and then processes it to obtain the voltage sampling signal. The hysteresis comparator unit introduces the voltage sampling signal into the comparator circuit, sets a comparison reference value, and when the output voltage of the power take-off generator exceeds the comparison reference value, the output level of the comparator circuit flips from high level to low level; when the output voltage of the power take-off generator drops below the comparison reference value again, the output level of the comparator circuit flips again from low level to high level; the comparison result level signal output by the hysteresis comparator unit is used for the next level of control. The excitation regulation enable control unit uses the comparison result level signal output by the hysteresis comparator as an enable signal to control the working state of the excitation regulation circuit. If the comparison result signal is high, the excitation regulation circuit is enabled normally, allowing it to output PWM pulses to generate excitation current in the excitation winding; if the comparison result signal is low, the excitation regulation circuit is disabled, its PWM pulse output is turned off, and the excitation current in the excitation winding is reduced to zero. The unloading control unit uses the comparison result level signal output by the hysteresis comparator unit for control, converting it into a drive signal to drive the next stage unloading main circuit unit to turn on and off; when the comparison result level signal is low, the unloading main circuit unit is driven to turn on; when the comparison result level signal is high, the unloading main circuit unit is driven to turn off. The unloading main circuit unit has an unloading power resistor connected in parallel between the positive and negative buses on the output side of the power take-off generator. The resistor is connected to the DC bus through an IGBT device. When the DC bus voltage rises too high and unloading is required, the unloading control unit promptly drives the IGBT device to conduct, connecting the unloading power resistor between the positive and negative terminals of the DC bus. This discharges the charge of the bus capacitor through the resistor, reducing the bus voltage. After the discharge is complete, the unloading control unit drives the IGBT device to turn off, disconnecting the unloading power resistor and releasing the residual charge on the unloading main circuit unit.

2. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 1, characterized in that: The isolated sampling unit includes a voltage divider circuit, an isolation operational amplifier circuit, and a difference operational amplifier circuit; The voltage divider circuit uses resistors to divide the voltage. Multiple resistors are connected in series between the positive and negative terminals of the generator output voltage. The voltage is taken from the resistor closest to the negative terminal as the output of the voltage divider circuit and introduced into the next stage isolation operational amplifier circuit. The isolation operational amplifier circuit uses an isolation operational amplifier to convert the voltage-divided sampling signal, which is grounded at the negative terminal of the power take-off generator, into a differential output voltage, which is then introduced into the next stage differential operational amplifier circuit; this differential output voltage shares a common ground with the power take-off generator control circuit. The differential operational amplifier circuit performs a subtraction operation on the two ends of the preceding differential voltage signal to obtain an output voltage signal to the ground of the power generation control circuit, which is the sampled voltage signal.

3. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 2, characterized in that: Let Uin be the voltage between the positive and negative terminals of the generator output. Then the output voltage of the voltage divider circuit is Uo = (R3 / (R1+R2+R3)) × Uin. Among them, resistors R1, R2, and R3 are connected in series between the positive and negative terminals of the generator output voltage. Resistor R3 is the resistor closest to the negative terminal. The voltage is taken from resistor R3 as the output of the voltage divider circuit.

4. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 2, characterized in that: The isolation operational amplifier circuit includes an isolation operational amplifier chip, an operational amplifier, and a current-limiting resistor R4; The output voltage Uo of the voltage divider circuit is directly input to the input terminal of the operational amplifier after passing through the current limiting resistor R4. The two sides of the isolated operational amplifier chip are powered separately. The input side power supply Vccp is the power supply that shares the same ground as the output terminal of the power take-off generator, and the output side power supply Vcc is the power supply of the power take-off generator control circuit. The differential voltage signals Vp and Vn output by the operational amplifier share the same ground as the power take-off generator control circuit, which is GND.

5. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 1, characterized in that: The voltage comparison result level signal of the power take-off generator is logically combined with the enable signal used to control the start and stop of the power take-off generator. After performing a logical AND operation, the final enable signal is obtained, which is then used to control the working state of the excitation regulation circuit.

6. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 1, characterized in that: The unloading control unit includes an optocoupler isolation circuit and an IGBT drive circuit to achieve signal isolation and IGBT drive. The optocoupler isolation circuit uses an optocoupler chip to convert the comparison result level signal output by the hysteresis comparator unit into an IGBT drive input signal. The comparison result level signal is introduced into the negative terminal of the optocoupler input side, and the positive terminal is connected to the power supply of the power generation control circuit, realizing the logic control of optocoupler turn-on when the input is low; the optocoupler output is used as the input of the next-level IGBT drive circuit. The IGBT drive circuit shares a common ground with the power take-off generator output circuit, and uses the output of the optocoupler isolation circuit as the input level to drive the IGBT. The IGBT drive circuit uses a pair of transistors of PNP and NPN types to form a push-pull circuit to drive the subsequent unloading main circuit unit.

7. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 6, characterized in that: The optocoupler isolation circuit includes resistors R5 and R6. The positive terminal of the input side of the optocoupler is pulled up to the power supply Vcc of the power generation control circuit via resistor R5. The collector (C) of the output side of the optocoupler is connected to the power supply Vccp, and the emitter (E) is used directly as the input of the next-stage IGBT driver circuit as the output level. A pull-down resistor R6 is added to ensure that the optocoupler's default output is low.

8. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 6, characterized in that: The IGBT drive circuit includes resistors R7 and R8, and a TVS diode V3. A current-limiting resistor R7 is added to the gate input side of the IGBT, and a resistor R8 is set between the gate and emitter of the IGBT. The voltage spikes of the drive signal are suppressed by setting the TVS diode V3 in parallel with the resistor R8.

9. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 1, characterized in that: The unloading main circuit unit includes an unloading resistor branch and a freewheeling branch; The unloading resistor branch consists of an unloading power resistor and an IGBT device connected in series and connected in parallel between the positive and negative DC buses on the output side of the power take-off generator. The IGBT device is used to enable and disable the unloading main circuit unit in the entire generator output circuit, and the unloading power resistor is used to release the charge on the bus after the unloading main circuit unit is enabled, thereby reducing the bus voltage. The freewheeling branch consists of a power diode connected in parallel across the unloading power resistor. When the generator output side finishes discharging and the IGBT device is turned off, the parasitic inductance on the line at the unloading power resistor will induce a high voltage. This high voltage is applied between the collector and emitter of the IGBT device. By adding a freewheeling branch diode, the IGBT device is prevented from breaking down.

10. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 1, characterized in that: The set comparison benchmark value is 1.1 times the rated output voltage of the power take-off generator.

11. The circuit for improving the load shedding dynamic performance of a magnetically excited power take-off system according to claim 1, characterized in that: The power take-off (PTO) generator control system is a power system that uses a certain control strategy to regulate the output power of the PTO generator. It includes two parts: the PTO generator and the PTO generator control circuit. The PTO generator is used to realize power output, and the PTO generator control circuit is used to regulate the output power of the PTO generator. The PTO generator control circuit includes a power supply circuit, a status acquisition circuit, a protection judgment circuit, and an excitation regulation circuit.

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