Method for passive arc suppression during an electrical treatment of plants

Abstract

The invention relates to a method for passive arc suppression during an electrical treatment of plants, the method having the step of: (S400) applying a pulse-width-modulated electrical direct current (I) to the plants.

Description

[0001] Method for passive arc suppression during electrical treatment of plants

[0002] The invention relates to a method and a treatment device for passive arc suppression during the electrical treatment of plants. Furthermore, the invention relates to a land vehicle with such a treatment device and a kit containing components of such a treatment device.

[0003] The use of direct electrical current for the electrical treatment of plants is known, for example, from US 2 007 383 and WO 2019 / 052591 A1, while the use of direct or alternating electrical current is known, for example, from WO 2018 / 095450 A1 or WO 2018 / 050142 A1.

[0004] However, as a result of such electrical treatment of plants, so-called arcs form between the plants and applicators, during or after the plants are / were exposed to direct electrical current, for example, due to low-resistance areas in a non-homogeneously growing field of plants. These relatively small discharges can develop into an arc between the electrodes, from which a large arc can arise. Due to relatively high ohmic resistances in the range of 100 ohms to 5 kOhms between the applicators and the plant material or the soil, known methods for arc detection are suitable, e.g.based on the evaluation of voltage and / or current curves here only to a limited extent, since a plurality of arcs overlap over the treatment width of a device for the electrical treatment of plants and the tear-off dynamics generally do not follow simple patterns due to the heterogeneous soil or plant material as is otherwise the case with many technical processes under more homogeneous conditions.

[0005] There is a need to demonstrate ways to achieve simple yet effective arc suppression. The object of the invention is achieved by a method for passive arc suppression during the electrotherapy of plants, comprising the following step:

[0006] Exposing the plants to a pulse-width modulated direct current.

[0007] A direct current is defined as an electric current without a reversal of direction or sign. However, the electric current intensity can vary; it does not have to be constant. For example, a direct current may exhibit a predetermined residual ripple, which is due to the rectification and smoothing of a three-phase or alternating current.

[0008] Pulse-width-modulated direct current is defined as a direct current that, due to modulation or equivalent measures, has at least two different voltage levels, with a second voltage level being significantly higher than a first voltage level. The difference between the two voltage levels exceeds the residual ripple. Furthermore, the lower voltage level is a level at which effective electrotherapy is not expected, while the upper voltage level is a level at which effective electrotherapy of plants is guaranteed. In the case of an arc, the lower voltage level is a level at which the voltage-dependent arc resistance increases. This leads to the arc being extinguished.

[0009] In other words, pulse width modulation (PWM, also known as PLM or PBM) temporarily reduces the electrical voltage applied to the plants during the electrical treatment. This then reduces the strength of the electrical current applied to the plants. Pauses are integrated into the electrical treatment during which arcs are extinguished due to the reduced electrical voltage without reducing the effectiveness of the electrical treatment due to the pulse width modulation. This increases the effectiveness and efficiency of the electrical treatment, as arc-free operation is ensured.

[0010] Unwanted arc formation can be effectively counteracted and thus the efficiency of the electrical treatment of plants can be increased by not taking measures to extinguish the arc upon detection of an arc, but by the method implementing passive arc extinguishing by temporarily reducing the output voltage without detecting an arc.

[0011] According to one embodiment, the pulse-width-modulated direct current is a direct current rectified by a rectifier and smoothed by a smoothing capacitor, wherein a duty cycle of the pulse-width-modulated direct current is selected such that the power delivered by an arc is greater than the supplied electrical power. This is a fixed duty cycle, i.e., the duty cycle is not changed during operation. For example, the lower voltage level is selected such that the energy in the chopping arc is reduced to such an extent that more energy is delivered by the arc than is supplied to it.The time required to reach the lower voltage level from the upper voltage level depends on the resistive load, which in normal operation is determined by the contacted plants and, in the case of an arc, by its electrical resistance. With a lower electrical resistance, as in the case of an arc, the lower voltage level is reached sooner than with a higher electrical resistance, since a smoothing capacitor in a rectifier discharges more quickly in comparison. It is also possible that the lower voltage level is not reached with a higher electrical resistance. The smoothing capacitor is therefore discharged at least to a lower voltage level below the arc burning voltage.In other words, it is not necessary to completely discharge the smoothing capacitor; it is sufficient to discharge the smoothing capacitor to the point where it provides an electrical voltage below the arc voltage required to maintain an arc. This way, breaks in the electrotherapy of plants during which no effective electrotherapy is taking place can be minimized by applying a pulse-width-modulated direct current, thus maximizing the effectiveness of the electrotherapy.

[0012] According to a further embodiment, the pulse-width-modulated direct current is a direct current rectified by a rectifier and smoothed by a smoothing capacitor, wherein a duty cycle of the pulse-width-modulated direct current is selected such that a pulse width duration for a lower voltage level corresponds to at least one or a plurality of periods of a rectified alternating current. This ensures that the smoothing capacitor can discharge sufficiently, thus ensuring effective arc suppression.

[0013] According to a further embodiment, a duty cycle of the pulse-width-modulated direct current is selected such that a pulse width duration for a lower voltage level has a duration of 1 ps to 200 ms, in particular 5 ps to 10 ms. This ensures that the electrical treatment is only interrupted for brief moments, thus preventing the effectiveness of the electrical treatment from being reduced.

[0014] According to a further embodiment, a duty cycle of the pulse-width-modulated direct current is selected between 0.5 and one. Thus, the electrical treatment is interrupted by the pulse-width modulation for a maximum of half the time, while electrical treatment takes place in the second half. This allows for particularly effective electrical treatment with simultaneous, reliable arc suppression. The invention further includes a computer program product, a treatment device for passive arc suppression during the electrical treatment of plants, a land vehicle with such a treatment device, and a kit containing components of such a treatment device.

[0015] The invention will now be explained with reference to the figures. They show:

[0016] Figure 1 shows a schematic representation of an embodiment of a

[0017] Land vehicle with a treatment device for the electrical treatment of plants.

[0018] Figure 2 shows a schematic plan view of the device shown in Figure

[0019] 1 shown land vehicle with the treatment device.

[0020] Figure 3 shows a schematic representation of two cantilever arms of the treatment device shown in Figures 1 and 2.

[0021] Figure 4 shows a schematic representation of an applicator unit of the treatment device shown in Figures 1 and 2.

[0022] Figure 5 shows a schematic representation of a circuit arrangement associated with the treatment device.

[0023] Figure 6A shows a schematic representation of a voltage curve.

[0024] Figure 6B shows a schematic representation of a current waveform corresponding to the voltage waveform shown in Figure 6A. Figure 6C shows a schematic representation of the discharge curves of a smoothing capacitor corresponding to Figures 6A and 6B, and

[0025] Figure 7 shows a schematic representation of a process flow for

[0026] Operation of the land vehicle shown in Figures 1 and 2.

[0027] Reference is first made to Figure 1.

[0028] Shown is a land vehicle 2 for use on farmland. In the present embodiment, the land vehicle 2 is a combination consisting of a tractor 4 pulling a trailer 6.

[0029] In the present embodiment, the towing vehicle 4 is designed as a tractor with its own drive, while the trailer 6 does not have its own drive.

[0030] In the present embodiment, a treatment device 8 for the electrical treatment of plants, comprising a wetting module 10 and an electrical module 12, is assigned to the trailer 6. Deviating from the present embodiment, the wetting module 10 and / or the electrical module 12 can be assigned to the towing vehicle 4. If both the wetting module 10 and the electrical module 12 are assigned to the towing vehicle 4, the trailer 6 can be omitted. Furthermore, the wetting module 10 and / or the electrical module 12 can each be designed as individual attachments that can be mounted as needed and dismantled again after use.

[0031] The wetting module 10 is designed to apply a liquid mixture of substances to the plants and / or soil to be treated. The liquid mixture of substances applied to the plants can contain an active ingredient that reduces the electrical contact resistance of plants and / or one or more additional active ingredients. The mixture of substances can also contain other active ingredients.

[0032] The electrical module 12, on the other hand, is designed to apply electrical energy to plants in order to kill them, e.g., as part of green manure control, weed treatment, or desiccation, e.g., of potato plants, cereals, or legumes. The plants can be, in particular, terrestrial plants (Embryophyta), such as higher plants, or vascular plants, especially plants with a structure consisting of roots, stems, and leaves (corms), which are to be controlled or killed accordingly.

[0033] By applying the mixture of substances with a component that reduces contact resistance, electrical contact resistance between applicators 28a, 28b, 28c (see Figure 4) of the electrical module 12 for contacting the plants and the contacted plants can be reduced. Furthermore, the tendency toward arcing is reduced, which reduces energy consumption during such an electrical treatment of plants.

[0034] In the present embodiment, during an electrical treatment of plants, the plants on the agricultural land are exposed to electrical energy in the form of a direct current. In contrast to the present embodiment, plants on non-agricultural land can also be subjected to electrical treatment.

[0035] In the present embodiment, a direct current voltage of 1,600 V to 5,500 V with a maximum residual ripple of 5% to 20% (in the frequency range 60 kHz to 200 kHz) is used for the electrical treatment of plants. To supply, for example, pumps of the wetting module 10 and the electrical module 12 with electrical operating power, a generator 14 is also arranged on the trailer 6 in the present embodiment. The generator 14 provides electrical operating power and is connected to the wetting module 10 and the electrical module 12 to transmit the electrical operating power.

[0036] In the present exemplary embodiment, the generator 14 is supplied with mechanical operating energy via a power take-off shaft 16 of the towing vehicle 4. In contrast to the present exemplary embodiment, mechanical drive energy for the generator 14 can also be provided via a hydraulic circuit. Furthermore, if the towing vehicle 4 has an electrified drive train, a supply of operating energy can be provided without interposing the generator 14.

[0037] In the present embodiment, generator 14 provides three-phase electrical current with a power of 160 kVA at an electrical voltage of 400 V and a frequency of 50 Hz to 60 Hz. Deviating from the present embodiment, the power and / or voltage of the three-phase electrical current can be higher or lower, e.g., double or only half as high.

[0038] The three-phase electrical current is transmitted via electrical cables to at least one transformation and control unit of the electrical module 12.

[0039] Further details and components of the electrical module 12 will be explained later.

[0040] Reference is now made additionally to Figure 2.

[0041] A plurality of applicator units 18 are arranged next to one another in an applicator row 22 on two extension arms 20a, 20b of the treatment device 8, which can be displaced between a working position (shown) and a non-use position (not shown), wherein the extension direction of the applicator row 22 preferably extends transversely, in the present embodiment at an angle of 90°, to the direction of travel FR of the land vehicle 2.

[0042] Figure 2 shows that, using the treatment device 8, a section A of an area with plants was first wetted with the liquid mixture by the wetting module 10 and then subjected to an electrical treatment by applying a direct electrical current using the electrical module 12. For this purpose, the trailer 6 with the treatment device 8 was moved by the towing vehicle 4 in the direction of travel FR at a speed v of, for example, 6 km / h over the section A of the area and applied with direct electrical current across the entire width b of the applicator row 22. Thus, each of the applicator units 18 treats a strip-shaped section A of the area.

[0043] In the present embodiment, the applicator row 22 covers a total working width of 0.3 m to 48 m, preferably 6 m to 27 m.

[0044] Reference is now made additionally to Figure 3.

[0045] Shown is one of the two cantilever arms 20a, 20b, namely the cantilever arm 20a of the treatment device 8 with the wetting module 10 and the electrical module 12 in the working position.

[0046] In the present exemplary embodiment, the wetting module 10 has a plurality of jointly or individually controllable nozzles 24 for applying the liquid substance mixture to plants, which nozzles are arranged in a row of nozzles 26 parallel to the applicator row 22. Thus, each of the applicator units 18 is assigned at least one of the nozzles 24, so that the respective applicator units 18 and nozzles 24 can interact during operation in such a way that plants are first wetted with the liquid substance mixture using the nozzles 24 and then subjected to an electro-treatment using the applicator units 18. Deviating from the present exemplary embodiment, several rows of nozzles 26 can be provided parallel to the applicator row 22, e.g. in front of and / or behind the applicator row 22. The row of nozzles 26 arranged behind the applicator row 22 can, for example,a second application of the liquid mixture of substances and / or an application of a further liquid second mixture of substances, which differs in composition from the first mixture of substances, to plants.

[0047] In the present embodiment, it is provided that applicators 28a, 28b, 28c (see Figure 4) of the applicator units 18 can be moved individually or in groups into a non-use position. In the present embodiment, this can be achieved by a pivoting movement S1 about a first axis. This relocation of the applicator units 18 into their non-use position can occur independently of the nozzles 24 of the wetting module 10 for applying the liquid substance mixture to plants. In other words, the active nozzles 24 of the wetting module 10 are not relocated but remain in their working position.

[0048] Furthermore, the present embodiment provides for the nozzles 24 of the wetting module 10 to be moved from their working position to a transport position. In the present embodiment, the nozzles 24 of the wetting module 10, together with the applicator units 18 (which are in their non-use position), can be moved to a transport position, e.g., by a second pivoting movement S2 about a second axis whose direction of extension differs from the first axis.

[0049] In other words, in the present embodiment, in a first displacement step, the applicator units 18 are moved from their working position to their non-use position by the first pivoting movement S1. In a second displacement step, the nozzles 24, together with the applicator units 18, are then moved into the transport position by the second pivoting movement S2. Deviating from the present embodiment, it can also be provided that the applicator units 18 and the nozzles 24 can be moved separately from their respective working positions to their respective transport or non-use positions.

[0050] In the present embodiment, the first axis of the first pivoting movement S1 extends transversely to the direction of travel FR and thus in the direction of the respective longitudinal extensions of the two boom arms 20a, 20b, while the second axis of the second pivoting movement S2 extends in the direction of travel FR. In other words, the two boom arms 20a, 20b are folded upwards to bring them into their transport position.

[0051] The liquid substance mixture can have at least one active ingredient component which reduces the electrical contact resistance in the area of ​​the plant surface, wherein the substance mixture has at least a first active ingredient component which contains at least one viscosity-increasing substance selected from the group consisting of pure silicic acids, pyrogenic silicic acids, mixed oxides, magnesium phyllosilicates, organic additives based on biogenic oils and their derivatives, polyamides and modified carbohydrates and at least a second active ingredient component which contains at least one surface-active substance selected from the group consisting of surfactants.

[0052] Furthermore, the liquid mixture can comprise one or more active ingredient components, wherein one of the active ingredient components has multiple effects, such as the effect of a surface-active substance and the effect of a viscosity-increasing substance.

[0053] Furthermore, the liquid mixture of substances can contain a soil activator component as an active ingredient, such as yeast and / or lactic acid bacteria or other components that accelerate composting.

[0054] Reference is now also made to Figure 4. It shows an applicator unit 18, which in the present embodiment comprises three applicators 28a, 28b, 28c for applying direct electrical current to plants. In other words, the applicator unit 18 can also be considered to comprise a trio of applicators in the present embodiment.

[0055] In the present embodiment, the first applicator 28a is electrically connected to a first polarity P1, the second applicator 28b is electrically connected to a second polarity P2, and the third applicator 28c is electrically connected to the first polarity P1.

[0056] In the present embodiment, due to the difference between the two polarities P1, P2, a first electrical voltage is established between the first applicator 28a and the second applicator 28b, and a second electrical voltage is established between the second applicator 28b and the third applicator 28c, both of which are of equal magnitude. Deviating from the present embodiment, the two electrical voltages can also have different values.

[0057] Deviating from the present embodiment, an applicator unit 18 can also have more than three applicators 28a, 28b, 28c or only two applicators 28a, 28b.

[0058] Reference is now made additionally to Figure 5.

[0059] Shown is a circuit arrangement 100 of the treatment device 8, which in the present embodiment is assigned to the electrical module 12.

[0060] In the present exemplary embodiment, at least one circuit arrangement 100 is assigned to each of the applicator units 18 of the applicator row 22, ie each applicator unit 18 of the applicator row 22 has at least one circuit arrangement 100 which is electrically connected to the three applicators 28a, 28b, 28c.

[0061] The circuit arrangement 100 is electrically connected via a contactor assembly 102, e.g., in a control cabinet of the transformation and control unit (not shown), to the three phases L1, L2, L3, and non-detachably to a neutral conductor N of the generator 14. Thus, if necessary, e.g., for safety reasons, the circuit arrangement 100 can be electrically disconnected from the generator 14.

[0062] In the present embodiment, the neutral conductor N is electrically connected to a housing of the circuit arrangement 100 and grounded.

[0063] In the present exemplary embodiment, the circuit arrangement 100 has the following components: a line filter 104, a contactor assembly 106, an inverter 108, a resonant circuit 116, a transformer 122, a rectifier 124 and a control unit 136 for controlling the circuit arrangement 100.

[0064] The line filter 104 is electrically connected to the three phases L1, L2, and L3, which can be isolated by the contactor assembly 106. In the present embodiment, the line filter 104 is designed to filter out interfering frequencies and other interference signals from the three phases L1, L2, and L3.

[0065] The contactor assembly 106 of the circuit arrangement 100 following the mains filter 104 can electrically separate the downstream inverter 108 from the mains filter 104.

[0066] In the present embodiment, inverter 108 is an indirect converter with DC voltage in the intermediate circuit (also known as a voltage-source inverter - VSI). The components of inverter 108 shown are a rectifier, in the present embodiment an AC / DC converter 110, a DC voltage circuit with an intermediate circuit capacitor 112, and an output-side inverter, in the present embodiment a DC / AC converter 114. Deviating from the present embodiment, other converter types can also be used.

[0067] An oscillating circuit 116 is connected to the output side of the inverter 108. For example, the oscillating circuit 116 can be a series oscillating circuit, the components of which are shown as an inductance 118 and a capacitor 120.

[0068] The resonant circuit 116 is electrically connected to an input of the transformer 122. In the present embodiment, the transformer 122 has two magnetically coupled coils, thus providing galvanic isolation between the input side of the transformer 122 and its output side.

[0069] The output side of the transformer 122 is electrically connected to the rectifier 124, which in the present embodiment is a bridge full rectifier with a downstream smoothing capacitor 126.

[0070] Through the interaction of inverter 108 and resonant circuit 116, as well as transformer 122 with the downstream rectifier 124, in the present embodiment, a three-phase alternating current with an electrical voltage of 400 V can be converted into an electrical direct voltage U of 1,600 V to 5,500 V with a maximum residual ripple of 5% to 20% (in the frequency range 60 kHz to 200 kHz). In contrast to the present embodiment, two-phase alternating current or three-phase current with more than three phases can also be rectified.

[0071] The electrical voltage U is composed of a constant constant value and a residual ripple value, with the residual ripple value fluctuating between a maximum and a minimum value. The difference between the maximum and minimum values ​​corresponds to a peak-to-valley value.

[0072] The peak-to-valley value is less than 1,000 V. In the present embodiment, the peak-to-valley value is in a range from 100 V to 500 V, depending on the load (pure ohmic resistance).

[0073] Thus, in operation, the circuit arrangement 100 provides the first polarity P1, a positive polarity in the present embodiment, at a first output and a second polarity P2, a negative polarity in the present embodiment, at the second output.

[0074] For electrical protection, in the present embodiment, a fuse 128a, 128b is provided between the first applicator 28a and the second applicator 28b or between the second applicator 28b and the third applicator 28c.

[0075] In the present embodiment, the control unit 136 is supplied with operating power from the three phases L1, L2, and L3, with an AC / DC converter 134 connected upstream of the control unit 136 providing a 24 V DC voltage. However, a separate power supply can be provided. This has the advantage that cooling units, such as fans, function independently of power electronics components.

[0076] Furthermore, in the present embodiment, the control unit 136 is connected to a current measuring device 130 and a voltage measuring device 132 in a measured variable transmitting manner.

[0077] The ammeter 130 measures an electrical current intensity of the electrical current I flowing through the first applicator 28a and the second applicator 28b or the second applicator 28b and the third applicator 28c, while the voltmeter 132 measures a voltage level of an electrical voltage U between the first applicator 28a and the second applicator 28b or the second applicator 28b and the third applicator 28c.

[0078] In the present exemplary embodiment, the control unit 136 is configured to control the inverter 108, in particular the DC / AC converter 114, by means of control signals AS such that a substantially constant electrical power is provided by the circuit arrangement 100 through pulse width and / or frequency modulation. A substantially constant electrical power is understood to mean an electrical power whose values ​​fluctuate within a typical range around a power setpoint, ie, which deviate from the power setpoint by, for example, 3%, 5%, or 10%.

[0079] In other words, the control unit 136 of the circuit arrangement 100 permanently detects a respective strength of an electrical direct current I and a level of an electrical voltage U on a secondary side of the transformer 122, so that a value for the ohmic resistance can be determined at any time.

[0080] During operation, the respective control units 136 are given a respective target value SW for the DC power output to be delivered, e.g., by the driver, e.g., based on load distribution. If the respective detected ohmic resistance at the applicators 28a, 28b, 28c is too high (a maximum electrical DC voltage is reached), the DC power output drops in proportion to the ohmic resistance. However, the level of the applied electrical DC voltage U remains unchanged due to a voltage limitation. Since the electrical DC voltage U and the electrical DC current I can now also be measured, a value for the ohmic resistance can be reliably determined in this state as well. The same applies to a current limitation. Once a maximum electrical DC current is reached, the delivered electrical DC power drops linearly with the ohmic resistance.Even in this operating state, the strength of the direct electrical current I and the level of the direct electrical voltage U on the secondary side continue to be reliably measured.

[0081] Reference is now additionally made to Figure 6A.

[0082] In order to counteract unwanted arcing between the first applicator 28a and the second applicator 28b or between the second applicator 28b and the third applicator 28c in the present embodiment, it is provided that shoots and / or leaves and / or roots of a plant contacted by the applicators 28a, 28b, 28c are subjected to a pulse-width modulated direct electrical current I.

[0083] For this purpose, the treatment device 8 can have appropriately designed hardware and / or software components.

[0084] An electrical direct current (I) is defined as an electrical current without a reversal of direction or sign. However, the electrical current intensity can vary; it does not have to be constant. For example, the electrical direct current may exhibit a predetermined residual ripple, which is due to the fact that a three-phase or alternating current has been rectified and smoothed.

[0085] A pulse-width-modulated direct current (I) is defined as an electric direct current that, due to modulation or equivalent measures, has at least two different voltage levels Umax and Umin, with the higher voltage level Umax being significantly higher than the lower voltage level Umin. The higher voltage level Umax has a value for effective electrotherapy of plants, while the lower voltage level Umin is a value below an arc voltage of, for example, 100 V.

[0086] An arc extinguishes when less electrical energy is supplied than is delivered. An arc criterion, such as an arc voltage of 100 V, is defined, for example, depending on the design of the three applicators 28a, 28b, and 28c, such that the power delivered by the arc is greater than the electrical power supplied.

[0087] A change from the lower voltage level Umin to the upper voltage level Umax and vice versa occurs periodically according to a duty cycle D, which defines a second pulse width duration T2 for the duration of the upper voltage level Umax in relation to a first pulse width duration T1 for the duration of the lower voltage level Umin. The duty cycle D is a fixed duty cycle, i.e., the duty cycle D does not change during operation but remains constant, in particular, independent of a load, and is not used for power control.

[0088] In other words, the level of electrical voltage U applied to the shoot and / or leaves and / or roots of a plant oscillates between the lower voltage level Umin and the upper voltage level Umax. The distance between the two voltage levels Umax, Umin exceeds the residual ripple. In other words, the pulse-width modulated direct current I can be derived from a rectangular pulse train and deviate from an ideal rectangular pulse train due to the residual ripple. An ideal pulse-width modulated direct current I can assume two discrete values, whereas in a rectangular pulse train with residual ripple, an electrical voltage or current can be assigned to two value ranges that do not overlap.

[0089] In the present embodiment, the duty cycle D is 0.5, i.e., the first pulse width duration T1 and the second pulse width duration T2 are of equal length. The duty cycle D can be specified as a fixed value, or the duty cycle D can be freely defined, e.g., from a value range of 0.5 to one. In other words, the pulse-width-modulated direct current I is not a time-discrete signal. Thus, by selecting a duty cycle of one, the pulse width modulation can be practically deactivated, e.g., if it can be assumed that no arcs will form during electrical treatment of plants.

[0090] In the present exemplary embodiment, the circuit arrangement 100 provides such a pulse-width-modulated electrical voltage U to the applicators 28a, 28b, 28c. For this purpose, it is provided that the DC / AC converter 114 is controlled by the control unit 136 using corresponding control signals AS. In contrast to the present exemplary embodiment, it can also be provided that, for example, between the DC / AC converter 114 and the rectifier 124 or downstream of the rectifier 124 and upstream of the smoothing capacitor 126, a controllable switch assembly is provided, with which the smoothing capacitor 126 can be electrically decoupled and then subsequently discharged via the applicators 28a, 28b, 28c.

[0091] Reference is now additionally made to Figure 6B.

[0092] In the present exemplary embodiment, it is provided that the duty cycle D is selected such that the pulse width duration T 1 for the lower voltage level Urnin corresponds to at least a plurality of periods of a rectified alternating current lac flowing in a circuit comprising the output side of the DC / AC converter 114, the inductance 116 and the capacitance 120 of the resonant circuit 116 and the input side of the transformer 122.

[0093] In the present embodiment, the number of periods is five. This means that charging or recharging of the smoothing capacitor 126 is suspended for five periods in the present embodiment, which conversely means that the smoothing capacitor 126 discharges via the applicators 28a, 28b, 28c during these five periods. Deviating from the present embodiment, the number of periods can be any number. For example, deviating from the present embodiment, the number of periods can be in a range from one to ten. It is also possible to use only half periods, as in half-wave control. In other words, the rectified alternating current lac is controlled or regulated by means of an oscillation packet control, in which switching operations are only carried out at the zero crossings of the alternating current lac.

[0094] Thus, the rectifier 124 is supplied with an oscillation packet-controlled alternating current on the input side, while the rectifier 124 provides the pulse-width modulated electrical direct current I on the output side for supplying the plants.

[0095] This enables zero voltage switching (ZVS) and / or zero current switching (ZCS).

[0096] In contrast to the present embodiment, the rectifier 124 can be supplied with a phase-cut and / or phase-cut alternating current on the input side. In other words, a phase-cut control and / or a phase-cut control is used.

[0097] Furthermore, in deviation from the present exemplary embodiment, a rectified electrical current provided on the output side of the rectifier 124 can be pulse-width modulated by appropriately controllable switching elements or equivalent components downstream of the rectifier 124.

[0098] Furthermore, in deviation from the present embodiment, a rectified, pulse-width modulated electrical current can be provided on the output side of the rectifier 124 by temporarily switching off, for example, the inverter 108.

[0099] Reference is now additionally made to Figure 6C.

[0100] Furthermore, in the present exemplary embodiment, the pulse width duration T1 for the lower voltage level Urnin has a duration of 1 ps to 200 ms. In contrast to the present exemplary embodiment, the pulse width duration T1 can also be in a range of 5 ps to 10 ms. The time required to reach the lower voltage level Umin from the upper voltage level Umax depends on the ohmic load, which in normal operation is determined by the plants in contact and, in the case of an arc, by its electrical resistance. With a lower electrical resistance, as in the case of an arc, the lower voltage level Umin is reached sooner than with a higher electrical resistance, since the smoothing capacitor 126 of the rectifier 124 then discharges comparatively faster. It is also possible that the lower voltage level Umin is not reached with a higher electrical resistance.

[0101] Furthermore, in the present embodiment, the alternating electrical current lac has a frequency in the range of 150 kHz to 200 kHz, e.g., 180 kHz. In other words, in the present embodiment, the output of the DC / AC converter 114 can be considered a source of the alternating electrical current lac with a frequency of 180 kHz.

[0102] In the present exemplary embodiment, the smoothing capacitor 126 is dimensioned such that, in conjunction with an ohmic resistance between the first applicator 28a and the second applicator 28b, or between the second applicator 28b and the third applicator 28c, a discharge time of approximately 45 ps is established, which corresponds to approximately five periods. The electrical voltage drops exponentially, like an RC element. In this case, the electrical voltage can drop to the lower voltage level Umin according to a voltage curve SV1. Alternatively, however—depending on the value of the ohmic resistance—the electrical voltage may not reach the lower voltage level Umin according to a voltage curve SV2.

[0103] If, however, an arc forms between the first applicator 28a and the second applicator 28b, or between the second applicator 28b and the third applicator 28c, the ohmic resistance has a significantly lower value. In this case, the electrical voltage can drop to the lower voltage level Limin according to a voltage curve SV3.

[0104] In the present embodiment, the applicator unit 18 is moved at a speed v of 6 km / h in the direction of travel FR. With a pulse width duration T1 lasting five periods, a strip of approximately 0.1 mm wide in the direction of travel FR remains untreated, so that the effectiveness of the electrotherapy treatment is practically not reduced by the pulse width modulation, and it can also be ruled out that plant parts, such as individual leaves of a plant, remain untreated.

[0105] Reference is now additionally made to Figure 7 in order to explain a method sequence for operating the treatment device 8 for the electro-treatment of plants, in particular for green manure control.

[0106] In a first step S100, the first output of the circuit arrangement 100, which has the first polarity P1, is electrically connected to the first applicator 28a and the third applicator 28c. Furthermore, the second output of the circuit arrangement 100, which has the second polarity P2, is electrically connected to the second applicator 28b.

[0107] In a further step S200, the plant is exposed to the liquid mixture and electrical energy.

[0108] In a further step S300, the first applicator 28a and the second applicator 28b as well as the third applicator 28c are brought into contact with a stem axis and / or leaves of the plant and / or a soil one after the other and / or simultaneously.

[0109] In a further step S400, the contacted stem axis and / or the contacted leaves are directly and / or the roots of the plant are indirectly - ie through the soil - exposed to a pulse-width modulated direct electrical current I.

[0110] The duty cycle D of the pulse-width modulated direct current I can be selected such that the smoothing capacitor 126 is discharged at least to a lower voltage level Urnin below an arc burning voltage as an arc criterion.

[0111] Furthermore, the duty cycle D of the pulse-width modulated direct current I can be selected such that a pulse width duration T1 for a lower voltage level Umin corresponds to at least one or a plurality of periods of a rectified alternating current lac.

[0112] Furthermore, the duty cycle D of the pulse-width modulated direct current I can be selected such that the pulse width duration T1 for the lower voltage level Umin has a pulse width duration of 1 ps to 200 ms, in particular of 5 ps to 10 ms.

[0113] Finally, the duty cycle D of the pulse-width modulated direct current I can be selected between 0.5 and one.

[0114] Deviating from the present embodiment, the order of the steps may also be different. Furthermore, multiple steps may be executed simultaneously. Furthermore, deviating from the present embodiment, individual steps may be skipped or omitted.

[0115] Pulse-width modulation temporarily reduces the electrical voltage applied to the plants during the electrotherapy treatment. This then reduces the strength of the electrical current applied to the plants. Pauses are integrated into the electrotherapy treatment during which arcs are extinguished due to the reduced electrical voltage, without reducing the effectiveness of the electrotherapy treatment. This increases the effectiveness and efficiency of the electrotherapy treatment, ensuring arc-free operation.

[0116] It is therefore possible to effectively counteract unwanted arc formation and thus increase the efficiency of the electrical treatment of plants by not taking measures to extinguish the arc upon detection of an arc, but rather the method implements passive arc extinguishing by temporarily reducing the output voltage without detecting an arc.

[0117] List of reference symbols

[0118] 2 land vehicle

[0119] 4 towing vehicle

[0120] 6 followers

[0121] 8 Treatment device

[0122] 10 Wetting module

[0123] 12 Electrical module

[0124] 14 Generator

[0125] 16 PTO

[0126] 18 Applicator unit

[0127] 20a boom arm

[0128] 20b boom arm

[0129] 22 applicator row

[0130] 24 nozzle

[0131] 26 nozzle rows

[0132] 28a Applicator

[0133] 28b Applicator

[0134] 28c applicator

[0135] 100 circuit arrangement

[0136] 102 Contactor assembly

[0137] 104 line filters

[0138] 106 Contactor assembly

[0139] 108 inverters

[0140] 110 AC / DC converters

[0141] 112 DC link capacitor

[0142] 114 DC / AC converters

[0143] 116 resonant circuit

[0144] 118 Inductance

[0145] 120 capacity

[0146] 122 Transformer

[0147] 124 Rectifier 126 Smoothing capacitor

[0148] 128a fuse

[0149] 128b fuse

[0150] 130 ammeter

[0151] 132 Voltmeter

[0152] 134 AC / DC converters

[0153] 136 Control unit

[0154] A area section

[0155] AS control signal b width

[0156] D Duty cycle

[0157] FR direction of travel

[0158] I direct current lac alternating current

[0159] L1 phase

[0160] L2 phase

[0161] L3 phase

[0162] N neutral conductor

[0163] 51 Swivel movement

[0164] 52 Swivel movement

[0165] SW setpoint

[0166] T1 pulse width duration

[0167] T2 pulse width duration

[0168] U voltage

[0169] Umax upper voltage level

[0170] Umin lower voltage level v driving speed

[0171] S100 step

[0172] S200 Step

[0173] S300 step

[0174] S400 step

Claims

Patent claims 1 . A method for passive arc suppression in an electrical treatment of plants, comprising the step: (S400) Applying a pulse-width modulated direct electrical current (I) to the plants.

2. Method according to claim 1, wherein the pulse-width-modulated direct electrical current (I) is a direct electrical current (I) rectified by a rectifier (124) and smoothed by a smoothing capacitor (126), wherein a duty cycle (D) of the pulse-width-modulated direct electrical current (I) is selected such that a power output by an arc is greater than the supplied electrical power.

3. Method according to claim 1 or 2, wherein the pulse-width-modulated direct electrical current (I) is a direct electrical current (I) rectified by a rectifier (124) and smoothed by a smoothing capacitor (126), wherein a duty cycle (D) of the pulse-width-modulated direct electrical current (I) is selected such that a pulse width duration (T1) for a lower voltage level (Umin) corresponds to at least one or a plurality of periods of a rectified alternating current (lac).

4. Method according to one of claims 1 to 3, wherein a duty cycle (D) of the pulse-width modulated direct current (I) is selected such that a pulse width duration (T 1 ) for a lower voltage level (Umin) has a duration of 1 ps to 200 ms, in particular of 5 ps to 10 ms.

5. Method according to one of claims 1 to 4, wherein a duty cycle (D) of the pulse-width modulated direct current (I) is selected between 0.5 and one.

6. A computer program product designed to carry out a method according to one of claims 1 to 5.

7. Treatment device (8) for the electrical treatment of plants, wherein the treatment device (8) is designed to apply a pulse-width modulated direct electrical current (I) to the plants.

8. Treatment device (8) according to claim 7, wherein the pulse-width-modulated direct electrical current (I) is a direct electrical current (I) rectified by a rectifier (124) and smoothed by a smoothing capacitor (126) of the treatment device (8), wherein the treatment device (8) uses a duty cycle (D) for the pulse-width-modulated direct electrical current (I) which is selected such that a power output by an arc is greater than the supplied electrical power.

9. Treatment device (8) according to claim 7 or 8, wherein the pulse-width-modulated direct electrical current (I) is a direct electrical current (I) rectified by a rectifier (124) and smoothed by a smoothing capacitor (126) of the treatment device (8), wherein the treatment device (8) uses a duty cycle (D) for the pulse-width-modulated direct electrical current (I) selected such that a pulse width duration (T 1 ) for a lower voltage level corresponds to at least one or a plurality of periods of a rectified alternating current (lac).

10. Treatment device (8) according to one of claims 7 to 9, wherein the treatment device (8) uses a duty cycle (D) for the pulse-width modulated direct current (I) which is selected such that a pulse width duration (T1) for a lower voltage level (Urnin) has a duration of 1 ps to 200 ms, in particular of 5 ps to 10 ms.

11. Treatment device (8) according to one of claims 7 to 10, wherein the treatment device (8) is designed to use the duty cycle (D) of the pulse-width modulated direct current (I) between 0.5 and one.

12. Land vehicle (2), in particular trailer (6), with a treatment device (8) according to one of claims 7 to 11.

13. Kit comprising components of a treatment device (8) according to one of claims 7 to 11 for forming a land vehicle (2) according to claim 12.

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