Energy management method for hydroelectric generating set magnetic field energy taking device

Abstract

The invention discloses an energy management method for a hydroelectric generating set magnetic field energy taking device. The energy management method comprises the following steps of S1, offsetting inductive impedance of an energy taking coil by adopting a series resonance matching method; s2, low-loss rectification is realized through a quadruple-voltage active rectification method, and the output voltage is increased; and S3, optimizing energy management based on an RC tracking type maximum power tracking method, converting alternating current obtained by a hydroelectric generating set magnetic field energy obtaining device into direct current capable of being used by a sensor, and meanwhile, meeting the requirements of low power consumption and output stability. According to the invention, a series resonance matching, quadruple voltage active rectification and RC tracking type MPPT three-level collaborative architecture is constructed, the problem of mismatching of inductive impedance of an energy taking coil under a low-frequency magnetic field is solved by accurately designing series resonance parameters, and low loss and stable boosting of quadruple voltage rectification are realized by adopting a low-threshold device and a self-starting mechanism. The maximum power point is accurately locked with ultra-low power consumption based on an RC tracking strategy of an analog circuit, efficiency and stability bottlenecks of non-intrusive energy taking under the low-frequency strong magnetic field environment of the hydroelectric generating set are broken through in cooperation of the three, and efficient conversion from weak magnetic field energy to available direct current of a sensor is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy collection, in particular to an energy management method for a water turbine magnetic field energy harvesting device. BACKGROUND

[0002] In an environmental energy collection system, the alternating weak energy output by the energy harvesting device needs to be converted and managed efficiently through an interface circuit. For the special needs of non-invasive energy harvesting devices in the low-frequency strong magnetic field environment of a water turbine, the traditional interface circuit faces three major technical bottlenecks: 1. The inductive impedance of the energy harvesting coil and the matching efficiency of the subsequent circuit are low, and the reactive power loss is significant; 2. When rectifying low-frequency weak voltage, the energy loss caused by the diode conduction voltage drop is serious; 3. The general traditional MPPT strategy is not suitable for micro-energy collection and application systems due to high power consumption.

[0003] In the prior art, the passive matching circuit cannot adapt to the low-frequency scenario, the diode rectification has low efficiency at low voltage, and the traditional MPPT strategy is not suitable for micro-energy systems due to high power consumption. Therefore, an energy management method that takes into account efficiency and adaptability is urgently needed. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an energy management method for a water turbine magnetic field energy harvesting device to improve the energy conversion efficiency and system stability in a low-frequency strong magnetic field environment.

[0005] To solve the above technical problems, the technical solution adopted by the present application is: an energy management method for a water turbine magnetic field energy harvesting device, comprising the following steps: Step S1, using a series resonance matching method to offset the inductive impedance of the energy harvesting coil; Step S2, using a four-times voltage active rectification method to realize low-loss rectification and improve the output voltage; Step S3, based on an RC tracking maximum power point tracking (MPPT) method to optimize energy management, converting the alternating current obtained by the water turbine magnetic field energy harvesting device into direct current available for sensors, while meeting the requirements of low power consumption and output stability.

[0006] Preferably, in step S1, in the series resonance matching method, the parameter of the resonance capacitor C is calculated by the following formula: ; Where L is the equivalent inductance of the energy harvesting coil, is the frequency of the water turbine magnetic field.

[0007] The energy taking coil is equivalent to an inductance L=14.9 mH and an internal resistance ri=34.2 Ω in series, and when f=50 Hz, C≈68 μF is calculated to offset the inductive impedance of the energy taking coil.

[0008] Preferably, in the step S1, the active power output by the series resonant matching circuit to the load is calculated by the following formula: ; wherein, P is the output active power to the load, V is the output voltage of the magnetic field energy taking device, ri is the equivalent internal resistance of the energy taking coil, L is the equivalent inductance of the energy taking coil, R is the load resistance, and C is the capacitance of the series matching.

[0009] Preferably, in the step S2, the device selection step of the four-voltage active rectification method is: selecting a low threshold MOSFET and an ultra-low power comparator; the low threshold MOSFET is ZXM61N02F and ZXM61P02F, and the gate-source threshold voltage VGS(th) is as low as ±0.7 V; the ultra-low power comparator is TLV3702, and the working current is 560 nA, so as to reduce the energy loss caused by the conduction of the device in the rectification process.

[0010] Preferably, in the step S2, the four-voltage active rectification method comprises a self-starting control step: when the circuit is initially powered on, passive rectification is realized through the drain-body parasitic diode of the MOSFET; when the output voltage of the circuit reaches the working threshold of the comparator, the comparator drives the MOSFET to switch to the active rectification mode, completing the transition from passive rectification to active rectification and further reducing the conduction loss.

[0011] Preferably, in the step S2, the output characteristics of the four-voltage active rectification method satisfy: when the input is an alternating current with a frequency of 50 Hz and an amplitude of 1 V, the output direct current voltage is stabilized at 3.2 V after being processed by the rectification method, meeting the demand of the sensor for direct current power supply voltage.

[0012] Preferably, in the step S3, the steps of the RC tracking MPPT method include: (1) The output end of the rectification circuit is connected with a filter capacitor, and the voltage VC across the capacitor is calculated by the following formula: ; wherein, , , τ is the charging time constant, and C is the capacitance value, R His the internal resistance of the energy harvester, R c is the equivalent resistance of the capacitor, V H is the voltage of the energy harvester, V 0 is the initial voltage value of the capacitor at time 0; (2) the energy stored in the capacitor , the energy stored in the capacitor E C Taking the derivative with respect to time t, the charging power formula of the capacitor can be obtained: ; The relationship between the charging power P of the capacitor and the capacitor voltage V C can be obtained, that is: ; (3) Taking the extreme value of the above formula, the condition when the charging power takes the maximum value can be obtained, that is: ; That is, the charging power of the capacitor first increases and then decreases with the increase of the capacitor voltage, and has the maximum charging power when the capacitor voltage reaches half of the energy harvester voltage.

[0013] Preferably, in the step S3, the circuit configuration step of the RC tracking MPPT method is: a RC series circuit composed of a capacitor C P and a resistor R P is connected in parallel at the output end of the four times voltage active rectifier circuit, and a differential circuit, a signal processing circuit (envelope detection circuit), a voltage sampling circuit and a comparator are also configured; wherein the differential circuit is used to detect the peak value of the voltage V P across the resistor R RP , the signal processing circuit is used to process the sharp pulse signal output by the differential circuit into a smooth continuous signal, and the voltage sampling circuit is used to form a reference voltage Vref by proportionally reducing the rectified output voltage Vrec.

[0014] Preferably, in the step S3, the parameter determination step of C P and R P is: (1) The output of the energy harvesting device after being processed through steps S1 and S2 is equivalent to a power supply model containing open circuit voltage V H , internal resistance Re and equivalent capacitance Ce, wherein Re and Ce are obtained by actual measurement; (2) Calculate the charging time constant τ e = ReCe of the equivalent capacitor Ce; (3) Set the values of C e and R P according to τ P to ensure that when the voltage VCe reaches the maximum power point voltage V MPP (i.e. MPP =V H / 2), VRP reaches the peak value.

[0015] Preferably, in the step S3, the closed-loop control step of the RC tracking MPPT method is: (1) when Vrec>V MPP (i.e. MPP =V H / 2), Vref> the output signal of the signal processing circuit, the comparator outputs a high level, drives the DC-DC converter to work, and pulls down Vrec; (2) when Vrec<V MPP , Vref< the output signal of the signal processing circuit, the comparator outputs a low level, the DC-DC converter stops working, and Vrec is raised; Through the above control, the energy management process is stabilized at the maximum power point of Vrec=V MPP .

[0016] The present application provides an energy management method for a water turbine generator magnetic field energy taking device, which has the following beneficial effects: 1. Improve the magnetic field energy taking matching efficiency, reduce the reactive loss, and widen the load adaptation range The series resonance matching circuit designed in the present application fundamentally solves the problem of inductive impedance mismatch and large reactive loss of the traditional passive matching circuit in the low frequency scene. Based on the characteristics of the stable frequency of the water turbine generator magnetic field, the resonance capacitor is accurately calculated to completely offset the inductive impedance of the energy taking coil, avoiding the consumption of reactive power by the inductor. Compared with the series and parallel resonance matching characteristics, although the maximum power output of the parallel matching is slightly higher, the series matching can output larger active power in a larger load resistance range, which can adapt to the load fluctuation demand of the water turbine generator energy taking device under different working conditions, solving the problems of narrow load adaptation and unstable power output of the traditional matching circuit.

[0017] 2. Reduce the conduction loss in the rectification stage, improve the rectification efficiency and output voltage stability The quadruple voltage active rectifier circuit of the application optimizes the defects of large conduction voltage drop and serious energy loss of traditional diode rectification at low voltage. Low threshold MOSFET and ultra-low power comparator are used to replace traditional diode, which greatly reduces the conduction loss. The circuit has a self-starting mechanism. When initially powered on, the passive rectification start is realized through the MOSFET body parasitic diode, and the active rectification mode is switched after the voltage meets the standard, without the need for additional starting power supply. When the input is a low-frequency weak alternating current of 50Hz and 1V amplitude, a stable 3.2V DC voltage can be output, which not only meets the power supply demand of the hydroelectric generator set sensor, but also improves the efficiency of the traditional passive rectification by more than 30%.

[0018] 3. Realize low-power maximum power tracking, improve energy utilization rate and output stability The RC tracking MPPT strategy of the application breaks through the limitations of traditional MPPT such as high power consumption of digital control algorithm and inadaptation to micro-energy systems. The whole power consumption is only one tenth of that of traditional digital MPPT by using all-analog circuit without complex digital chips. Based on the charging characteristics of the capacitor, it is derived that the charging power is maximum when the capacitor voltage is half of the energy collector voltage. The maximum power point voltage can be locked in real time by tracking the peak voltage across the resistor in the RC circuit. The comparator and DC-DC converter form a closed-loop control, which automatically adjusts when the rectified voltage deviates from the maximum power point voltage, ensuring that the energy harvesting device always works at the maximum power point, and the energy transmission efficiency is improved by more than 25%, and the output power fluctuation amplitude is controlled within ±5%.

[0019] 4. Highly adapt to the low-frequency strong magnetic field environment of hydroelectric generator set, and enable sensor self-power supply system The design of the application fully meets the scene requirements of non-intrusive energy harvesting of hydroelectric generator set, and solves the problem of poor environmental adaptability of traditional interface circuit and inability to support sensor self-power supply. According to the core requirements of low-frequency, strong magnetic field and non-intrusive energy harvesting of hydroelectric generator set, the three-level architecture works cooperatively to avoid the defects of traditional circuit such as sudden drop of efficiency at low frequency and inability to start. The weak alternating energy obtained by the magnetic field energy harvesting device can be efficiently converted into stable DC voltage available for sensors without relying on external power supply. It not only meets the long-term power supply demand of hydroelectric generator set state monitoring sensors such as vibration and temperature sensors, but also reduces the wiring and maintenance cost, and improves the independence and reliability of the hydroelectric generator set monitoring system.

[0020] In summary, through the cooperative optimization of three-level architecture, the application simultaneously realizes four core advantages of high matching efficiency, low rectification loss, low-power MPPT and strong environmental adaptation, effectively breaks through the technical bottleneck of hydroelectric generator set magnetic field energy harvesting, and provides an efficient and stable energy management solution for the hydroelectric generator set sensor self-power supply system. BRIEF DESCRIPTION OF DRAWINGS

[0021] The application will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 A flow chart of the method of the application; Figure 2 A series matching circuit diagram of the application; Figure 3 A comparison chart of output powers of different matching networks under simulation conditions of the application; Figure 4 A simulation result chart of the four-voltage active rectifier circuit of the application; Figure 5 A rectifier circuit diagram of the application; Figure 6 A principle diagram of the RC-based MPPT principle of the application; Figure 7 An MPPT circuit architecture diagram of the application; Figure 8 A control loop structure diagram of the application; Figure 9 An MPPT simulation waveform chart of the energy management circuit of the application. DETAILED DESCRIPTION

[0022] As shown in Figure 1 An energy management method for a water turbine generator magnetic field energy extraction device, comprising the following steps: Step S1, using a series resonance matching method to offset the inductive impedance of the energy extraction coil; Step S2, using a four-voltage active rectifier method to realize low-loss rectification and improve the output voltage; Step S3, based on an RC tracking maximum power point tracking (MPPT) method, optimizing energy management, converting the alternating current obtained by the water turbine generator magnetic field energy extraction device into direct current available for sensors, while meeting the requirements of low power consumption and output stability.

[0023] In step S1, there are two commonly used matching circuits for single-frequency point matching in the matching network, one is a series resonance matching circuit, and the other is a parallel resonance matching circuit. For the series resonance matching circuit, a series capacitor C and an inductor L are selected for resonance; for the parallel resonance matching circuit, a parallel capacitor C and an inductor L are selected for resonance.

[0024] Whether it is a series resonance matching circuit or a parallel resonance matching circuit, impedance matching is achieved at a single fixed resonance frequency. Since the magnetic field frequency of the water turbine generator is usually stable, both series and parallel resonance can be achieved. The load output characteristics of the non-resonance matching circuit and the series-parallel resonance matching circuit are analyzed respectively below to verify the output power improvement effect of the resonance matching circuit and the difference in output characteristics between the series and parallel resonance networks.

[0025] For series matching circuit, the active power expression output to the load is:

[0026] wherein P is the output active power to the load, V is the output voltage of the magnetic field power device, R is the equivalent internal resistance of the power device coil, L is the equivalent inductance of the power coil, R is the load resistance, C is the series matching capacitance.

[0027] Other parameters being unchanged, in order to eliminate the inductance consumption reactive power, the resonance capacitance according to the maximum power transmission theory is:

[0028] For parallel matching circuit, the active power expression output to the load is:

[0029] Other parameters being unchanged, in order to eliminate the inductance consumption reactive power, the resonance capacitance according to the maximum power transmission theory is:

[0030]

[0031] The maximum power output of parallel matching is slightly greater than that of series matching, but the series matching has a larger power output in a larger resistance range, so the series matching circuit is more selected according to the load range. The series resonance matching circuit is designed, the capacitance C and the coil inductance L are selected to resonate, and the inductive impedance is offset, as shown in Figures 2-3 .

[0032] The power coil is equivalent to an inductance L =14.9mH and a series structure of internal resistance r i =34.2Ω, the resonance capacitance calculation is obtained:

[0033] When f=50Hz, C≈68μF is calculated; Step S2 constructs a four-voltage active rectifier circuit according to the analysis of the matching circuit in step S1, and a MOSFET and a comparator are combined to realize low-loss rectification; In order to reduce the conduction loss when low-voltage rectification, a four-voltage active rectifier circuit is designed: 1, device selection: low threshold MOSFET (ZXM61N02F and ZXM61P02F, V GS(th)Low to ± 0.7V) and ultra-low power comparator (TLV3702, operating current 560nA); 2, circuit topology: through four capacitors and MOSFET combination, four times voltage rectifier is realized; 3, self-starting mechanism: when the circuit is powered on, the MOSFET body diode is passively rectified, and when the output voltage reaches the comparator operating threshold, the comparator drives the MOSFET to switch to active rectification mode; 4, simulation verification: when the input is 50Hz, 1V amplitude AC, the output DC voltage is stable at 3.2V, as shown in Figures 4-5 .

[0034] Step S3 makes an energy management scheme according to the active rectifier circuit obtained in step S2 to realize maximum power output; Use the charging characteristics of the capacitor to track the maximum power point: Parallel RC series circuit at the output end of the rectifier circuit, when the switch S is closed, the capacitor C starts to charge through the resistor, and the voltage across the capacitor eventually reaches the voltage of the energy harvester H. When the switch S is opened, the capacitor C supplies power to the load.

[0035] Consider from 0 time to t time, the voltage Vc across the capacitor can be calculated by the following formula: ; Among them, , , The charging time constant is called C, which is the capacitance value, R H The internal resistance of the energy harvester is R c The equivalent resistance of the capacitor is V H The voltage of the energy harvester is V 0 is the initial voltage value of the capacitor at 0 time. When the system is just started, the capacitor voltage is initially 0, then: Consider the capacitor voltage at 0 time is 0, the charging current I C Can be calculated by the following formula: ; It can be seen that the capacitor charging voltage rises rapidly in an exponential law, and the current decreases rapidly in an exponential law, which shows that the charging speed of the capacitor is continuously decreasing, and the charging speed is the largest at the moment of circuit connection.

[0036] The capacitor stored energy EC is related to the current voltage of the capacitor, that is: ; The derivative of the stored energy EC with respect to time t is taken, and the charging power formula of the capacitor is obtained: ; Further, the relationship between the charging power P of the capacitor and the capacitor voltage VC is obtained, that is: ; It can be seen that the charging power P of the capacitor is only related to the variable VC, and the rest are constant values. Obviously, the charging power P of the capacitor is a quadratic function of the capacitor charging voltage VC, and has a maximum value. Taking the extreme value of the above formula, the condition for the charging power to take the maximum value is obtained, that is: ; That is, the charging power of the capacitor first increases and then decreases with the increase of the capacitor voltage, and has the maximum charging power when the capacitor voltage reaches half of the energy collector voltage. This conclusion is similar in principle to the open-circuit voltage method in the maximum power tracking (MPPT) theory. When the charging power of the capacitor reaches the maximum, it is the maximum power point of the energy collector transmitting energy to the next stage, which ensures that the energy obtained is transmitted to the next stage as much as possible.

[0037] After the energy collector is rectified, a series RC circuit composed of a capacitor C P and a resistor R P is connected in parallel, and the charging characteristics of the capacitor C P are used to track the maximum power point voltage V MPP , so as to realize the maximum power tracking control of the energy collector. In the RC parallel equivalent circuit, the output of the energy collection device after matching and rectification circuit can be equivalent to a power supply model containing equivalent resistance and equivalent capacitance, and the open-circuit voltage V H , R e is the internal resistance of the energy collector and the double voltage rectifier circuit, C e is the equivalent capacitance of the circuit output, V Ce is the voltage of the output equivalent capacitance C P , R e and C e can be obtained by actual measurement; in the RC circuit, V CP and V RP are the voltages across the introduced capacitor C P and resistor R P , respectively. Therefore, the time constant τ e of the charging process of the capacitor C e can be determined. In the RC circuit, the values of the capacitor C P and the resistor R P can be determined according to the time constant τ e of the charging process of the capacitor C P , and when appropriate C P and RP The parameter value can make the output equivalent capacitance C P The voltage V Ce reach the maximum output power point voltage V MPP When R C The output voltage V RP in the circuit reaches the peak value, so the peak voltage of V RP can be tracked to achieve the MPPT control of the energy collector, as Figure 6 Indicated.

[0038] The MPPT circuit design is shown in the attached Figures 7-8 , which consists of RC circuit, differential circuit, signal processing circuit, voltage sampling circuit and comparator, which is used to realize the energy management circuit to track the maximum power output of the energy collector.

[0039] The differential circuit is used to detect the peak value of the output voltage V RP of the RC circuit. When V RP ( t ) increases with time, the voltage on the input capacitance C D and the input resistance R D2 in the differential circuit will rise with V RP ( t ), but because the capacitor has the characteristics of storing charge, the rising speed of the voltage on the input capacitance C D will be slower than that on the input resistance, so the output of the differential circuit is high level, at this time the high level output is fed back to the capacitance C D through the resistance, so the voltage on the input capacitance C D is greater than that on the input resistance R D2 , at this time the output of the differential circuit is low level. Similarly, when V RP ( t ) decreases with time, the falling speed of the voltage on the input capacitance C D will be slower than that on the input resistance R D2 , at this time the output of the differential circuit is low level. Therefore, in the process of V RP ( t ) changing with time, the differential circuit will continuously output sharp pulse signal.

[0040] The signal processing circuit is an envelope detector circuit, used to smooth and continuous the sharp pulse signal output by the differentiating circuit. Diode D ED It can detect half-wave signals and can also reverse cut off when the differentiating circuit outputs a low level, preventing capacitor... C ED The stored charge flows out in the reverse direction; at the same time, the resistance... R ED With capacitor C ED The constructed low-pass filter can detect and demodulate the modulated signal, wherein the capacitor... C ED The resistor is used to store the high-level pulse output of the differentiating circuit. R ED Used to release capacitor C ED The charge stored on it.

[0041] The voltage sampling circuit proportionally steps down the rectified output voltage Vrec to form a reference voltage. The output voltage of the envelope detector circuit... V ED With voltage divider resistor R S1 and R S2 The reference voltage formed after voltage division V ref The PMOS transistor is controlled by comparing the signals using a comparator TS881 to generate a drive signal. M P1 , M P2 With NMOS transistor M N1 The operating state. Then the comparator LTC1440 will use its own reference voltage. V ref1 Compared with the received output signal from the previous stage, a drive signal for the DC-DC converter is generated.

[0042] When the rectified voltage V rec Voltage above the maximum power point V MPP At that time, the reference voltage in the sampling circuit V ref The value is high, exceeding the envelope detector output voltage. V ED When the comparator TS881 outputs a high level, the switching transistor... M P1 , M P2 On, switching transistor M N1When the rectified voltage is lower than the maximum power point voltage, the reference voltage in the sampling circuit is lower than the envelope detection output voltage, the non-inverting terminal and the inverting terminal of the comparator TS881 input signals are respectively V ref and the DC-DC converter does not work, the rectified voltage is raised. V rec When the rectified voltage is lower than the maximum power point voltage, the reference voltage in the sampling circuit is lower than the envelope detection output voltage, the non-inverting terminal and the inverting terminal of the comparator TS881 input signals are respectively V rec and the DC-DC converter does not work, the rectified voltage is raised. V MPP When the rectified voltage is lower than the maximum power point voltage, the reference voltage in the sampling circuit is lower than the envelope detection output voltage, the non-inverting terminal and the inverting terminal of the comparator TS881 input signals are respectively V ref and the DC-DC converter does not work, the rectified voltage is raised. V ED When the rectified voltage is lower than the maximum power point voltage, the reference voltage in the sampling circuit is lower than the envelope detection output voltage, the non-inverting terminal and the inverting terminal of the comparator TS881 input signals are respectively M N1 and the DC-DC converter does not work, the rectified voltage is raised. M P1 , M P2 When the rectified voltage is lower than the maximum power point voltage, the reference voltage in the sampling circuit is lower than the envelope detection output voltage, the non-inverting terminal and the inverting terminal of the comparator TS881 input signals are respectively V ref and the DC-DC converter does not work, the rectified voltage is raised. V ref1 Therefore, the energy management circuit can stably work at the maximum power point. V rec

[0043] In order to verify the MPPT characteristics of the control method, the working characteristics of the energy management circuit under the control method are verified by building a simulation model in the LTSpice simulation software, and the simulation results are shown in Figure 9 .

[0044] The application constructs a three-level collaborative architecture of series resonance matching, four times voltage active rectification and RC tracking type MPPT, solves the inductive impedance mismatching problem of the energy taking coil under low frequency magnetic field by accurately designing the series resonance parameters, realizes low loss and stable voltage boosting of four times voltage rectification by using low threshold devices and self-starting mechanism, accurately locks the maximum power point based on the RC tracking strategy of the analog circuit with ultra-low power consumption, and breaks through the efficiency and stability bottleneck of non-intrusive energy taking under the low frequency strong magnetic field environment of the water turbine unit, and realizes the efficient conversion of weak magnetic field energy to direct current available to the sensor.

[0045] The above embodiments are only preferred technical solutions of the application, and should not be regarded as limitations of the application, and the protection scope of the application should be based on the technical solutions claimed in the claims, including equivalent replacement solutions of the technical features claimed in the claims. That is, equivalent replacement improvements within this range are also within the protection scope of the application.​

Claims

1. An energy management method for a magnetic field energy harvesting device in a hydroelectric generator, characterized in that, Includes the following steps: Step S1: Use a series resonant matching method to cancel the inductive impedance of the energy harvesting coil; Step S2: Achieve low-loss rectification and increase output voltage through a quadruple voltage active rectification method; Step S3: Optimize energy management based on RC tracking maximum power point tracking method, convert the AC power obtained by the magnetic field energy harvesting device of the hydropower unit into DC power usable by the sensor, while meeting the requirements of low power consumption and output stability.

2. The energy management method for a magnetic field energy harvesting device in a hydroelectric generator according to claim 1, characterized in that, In step S1, the parameters of the resonant capacitor C in the series resonant matching method are calculated using the following formula: ； Where L is the equivalent inductance of the energy extraction coil. This is the frequency of the magnetic field of the hydroelectric generator unit.

3. The energy management method for a magnetic field energy harvesting device in a hydroelectric generator according to claim 1, characterized in that, In step S1, the active power output by the series resonant matching circuit to the load is calculated using the following formula: ； Among them, For the output active power of the load, The output voltage of the magnetic field energy harvesting device. The equivalent internal resistance of the energy harvesting device coil, The equivalent inductance of the energy extraction coil, For load resistance, For series matching capacitors.

4. The energy management method for a magnetic field energy harvesting device in a hydroelectric generator according to claim 1, characterized in that, In step S2, the device selection steps for the quadruple voltage active rectification method are as follows: a low-threshold MOSFET and an ultra-low power comparator are selected; the low-threshold MOSFET is of type ZXM61N02F and ZXM61P02F, with a gate-source threshold voltage VGS(th) as low as ±0.7V; the ultra-low power comparator is of type TLV3702, with an operating current of 560nA, in order to reduce the energy loss caused by device conduction during rectification.

5. The energy management method for a magnetic field energy harvesting device in a hydroelectric generator according to claim 4, characterized in that, In step S2, the quadruple voltage active rectification method includes a self-starting control step: when the circuit is initially powered on, passive rectification is achieved through the drain parasitic diode of the MOSFET; when the circuit output voltage reaches the operating threshold of the comparator, the comparator drives the MOSFET to switch to active rectification mode, completing the transition from passive rectification to active rectification, and further reducing conduction losses.

6. The energy management method for a magnetic field energy harvesting device in a hydroelectric generator according to claim 5, characterized in that, In step S2, the output characteristics of the four-voltage active rectification method meet the following requirements: when the input is an AC power with a frequency of 50Hz and an amplitude of 1V, the output DC voltage is stabilized at 3.2V after being processed by the rectification method, which meets the sensor's requirements for DC power supply voltage.

7. The energy management method for a magnetic field energy harvesting device in a hydroelectric generator according to claim 1, characterized in that, In step S3, the steps of the RC tracking MPPT method include: (1) A filter capacitor is connected to the output terminal of the rectifier circuit. The voltage VC across the capacitor is calculated using the following formula: ； in, , , Where C is the charging time constant and C is the capacitance value. R H It is the internal resistance of the energy harvester. R c It is the equivalent resistance of the capacitor. V H It is the voltage of the energy harvester. V 0 is the initial voltage value of the capacitor at time 0; (2) Capacitors store energy Storing energy E C Taking the derivative with respect to time t, we can obtain the formula for the charging power of the capacitor: ； The capacitor charging power P and capacitor voltage V can be obtained. C The relationship between them, namely: ； (3) By finding the extreme value of the above equation, we can obtain the condition under which the charging power reaches its maximum value, that is: ； That is, the capacitor charging power first increases and then decreases as the capacitor voltage increases, and has the maximum charging power when the capacitor voltage reaches half of the energy harvester voltage.

8. The energy management method for a magnetic field energy harvesting device in a hydroelectric generator according to claim 7, characterized in that, In step S3, the circuit configuration step of the RC tracking MPPT method is as follows: a capacitor C is connected in parallel at the output of the quadruple voltage active rectifier circuit. P With resistance R P The circuit consists of an RC series circuit, which also includes a differentiating circuit, a signal processing circuit, a voltage sampling circuit, and a comparator; the differentiating circuit is used to detect R. P Voltage V at both ends RP The peak value is obtained by the signal processing circuit, which processes the sharp pulse signal output by the differentiating circuit into a smooth and continuous signal. The voltage sampling circuit is used to proportionally reduce the rectified output voltage Vrec to form the reference voltage Vref.

9. The energy management method for a magnetic field energy harvesting device in a hydroelectric generator according to claim 8, characterized in that, In step S3, C P With R P The steps for determining the parameters are as follows: (1) The output of the energy harvesting device after processing in steps S1 and S2 is equivalent to including the open-circuit voltage V. H A power supply model with internal resistance Re and equivalent capacitance Ce, where Re and Ce are obtained through actual measurement; (2) Calculate the charging time constant τ of the equivalent capacitance Ce. e =ReCe; (3) According to τ e Setting C P With R P The value of is determined to ensure that when the voltage V of Ce is... Ce Reaching the maximum power point voltage V MPP At that time, VRP reaches its peak.

10. The energy management method for a magnetic field energy harvesting device in a hydroelectric generator according to claim 9, characterized in that, In step S3, the closed-loop control steps of the RC tracking MPPT method are as follows: (1) When Vrec > V MP When Vref > the output signal of the signal processing circuit, the comparator outputs a high level, driving the DC-DC converter to work and pulling Vrec low; (2) When Vrec <V MPP When Vref < the output signal of the signal processing circuit, the comparator outputs a low level, the DC-DC converter stops working, and Vrec is raised; Through the above controls, the energy management process is stabilized at Vrec = V MPP The maximum power point.

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