Plant part and plant

Abstract

plant part, comprising a secondary coil inductively coupled to a primary conductor system, which is connected in series or parallel with a capacitance such that the associated resonant frequency substantially corresponds to the alternating current frequency of the primary current, wherein a switch is provided as a decoupling means, with which, when a critical temperature in the region of the coil winding is exceeded, part of the winding of the secondary coil is short-circuited and thus the resonance frequency is detuned in such a way that the flow of the resonance current component is prevented.

Description

[0001] The invention relates to a plant component and a plant.

[0002] Varistors are known for absorbing voltage spikes. However, these cannot electrically store energy and then release it slowly. Furthermore, they only activate after critical voltage values ​​are exceeded.

[0003] DE 44 46 779 C2 and WO 92 / 17929 A1 disclose methods for contactless energy transmission in which there is a weak inductive coupling.

[0004] From JP H1 1 - 164 497 A and from JP H11 - 164 498 A a part of the system is known which has a secondary coil which is inductively coupled to a primary conductor system and which is connected in parallel with a capacitor to form an oscillating circuit in such a way that the associated resonance frequency corresponds to the alternating current frequency of the primary current, wherein a switch is provided as a decoupling means, by means of which the entire coil current can be interrupted and thus switched off when a critical temperature in the area of ​​the coil winding is exceeded.

[0005] From the publication HABIGER, E.: Interference protection circuits for electromagnetically operated devices - a literature review. In Elektrie, Vol. 24, 1973, No. 5, pp. 266-268 - ISSN 0013-5399, a protection module is known that features a rectifier for charging a capacitor with a discharge resistor connected in parallel.

[0006] The invention is based on the object of improving the safety of systems.

[0007] According to the invention, the object is achieved in the system part according to the features specified in claim 1 and in the system according to the features specified in claim 14.

[0008] The advantage here is that the current in the secondary coil has two components. The first is the stepped-up current component, which is familiar from transformers. To this is added a resonant current component, which is caused by the resonant circuit arrangement. The switch interrupts the resonant circuit, thus preventing the flow of current, or at least detunes it, thus preventing the flow of the resonant current component. In the latter case, the stepped-up current component can continue to flow. The resonant circuit arrangement enables the transmission of energy across a large air gap. Despite the large air gap, a high level of efficiency can be achieved. The safety of the system is increased because the supply to the system component is completely or essentially cut off if a critical temperature is exceeded.

[0009] This allows the system component, i.e., the consumer, to be supplied entirely inductively, i.e., contactlessly. The inductive coupling can also be selected to be weak.

[0010] In particular, the system component can be designed as a movable system component, such as a vehicle or trolley.

[0011] If a residual current, i.e. the pure translated current, is not prevented from flowing, but only the resonance current, then an electronic circuit can be supplied from this residual current, which emits a signal to report the status, causes a display of the status or causes the switched-off state to be maintained.

[0012] In an advantageous embodiment, the current in the secondary coil can be switched off using the switch. This is advantageous because the cause of the heating, such as overload, can be eliminated. This reduces the risk of fire. Switching off the switch causes the system component to cool down, and once the temperature falls below the critical level, the system component can be switched on again.

[0013] In an advantageous embodiment, at least part of the winding of the secondary coil can be short-circuited by means of the switch. This advantageously allows a residual current, namely the converted current component, to continue flowing, thus enabling an electronic circuit to maintain the shutdown or to perform another function, or a display or signal, such as a simple contact signal or information transmitted via a bus.

[0014] In an advantageous embodiment, the switch or a temperature sensor that influences and / or determines the switching state of the switch is thermally connected to the secondary coil, in particular arranged in contact with it. This is advantageous because the temperature of the winding can be measured as accurately and quickly as possible. Furthermore, the sensor is thus protected and mechanically connected, and with a suitable choice of potting compound, it is also insulated.

[0015] In an advantageous embodiment, the secondary coil and switch are integrated, in particular, the secondary coil and switch are thermally connected by means of a potting compound. This is advantageous because insulation and thermal coupling can be achieved in a single manufacturing step using this potting compound. Furthermore, protection against vibration is achieved, thus improving the mechanical stability of the connection between the switch or temperature sensor and the secondary coil.

[0016] In an advantageous embodiment, the switch comprises a bimetallic element, in particular a bimetallic switch. This has the advantage of allowing the use of a failure-resistant element.

[0017] In an advantageous embodiment, a further controllable switch is assigned to the switch, in particular connected in parallel, which can be controlled from a control unit, in particular transferred to the closed state, in such a way that the state of the system component caused by the change in the switching state of the first switch can be permanently maintained as long as the primary current is impressed in the primary conductor system. This is advantageous in that the switched-off state of the system component is maintained even after cooling begins and the temperature falls below the critical temperature. This prevents the secondary coil from heating up again. Hazards are thus avoided and safety increased.

[0018] In an advantageous embodiment, the control can be supplied via a transformer from the switch current. This is advantageous because the control can be supplied from the switch current generated by the first switch, thus allowing the switching state to be permanently determined by the additional switch.

[0019] In an advantageous embodiment, the protection module comprises at least one rectifier designed to charge a capacitor with a discharge resistor connected in parallel. This is advantageous in that the protection module can be constructed simply and compactly and housed in a housing. In particular, the electronics can be encapsulated with a heat-conducting potting compound, and the heat generated during overvoltage can be dissipated via the housing. The protection module comprises, for example, two electrical connections to the outside.

[0020] In addition, the protection module's capacitor is charged to the peak voltage of the applied AC voltage, and after this charging process, the protection module consumes only small amounts of power. However, if the input voltage to the protection module rises rapidly, a high current flows into the protection module, and the associated energy is absorbed up to a corresponding maximum amount in the module, stored, and dissipated as heat via the discharge resistor. For short-term voltage surges, the protection module behaves like a short-term short circuit.

[0021] In an advantageous embodiment, the protection module is arranged in parallel with a switch to prevent overvoltages and / or sparking at the switch contact. The advantage here is that it is not only effective at high voltages, but also at low voltages with every voltage increase. In contrast to varistors, protection against overvoltages is therefore always effective and active.

[0022] In an advantageous embodiment, the protection module is located at the output of a power source. This is advantageous because low voltages occur during normal operation, meaning that overvoltages differ significantly in their values ​​from those occurring during normal operation. Furthermore, a significant portion of the capacitance of the protection module's capacitor(s) can be utilized.

[0023] In an advantageous embodiment, the protection module is provided on a switch for short-circuiting and / or disconnecting a section of track. This is advantageous because such a protection module can be assigned to each switch, thus improving safety against sparking and overvoltage.

[0024] It should be noted that without the protective module according to the invention, in a switch intended to interrupt a low-frequency alternating current of, for example, 50 or 60 Hz, sparking may occur when the switch is opened, thus ionizing the air through which the current continues to flow. However, when the current value crosses zero, this current transmission also ceases because, during the time range of the zero crossing, the current values ​​are low or non-existent for so long that maintaining the ionization of the air becomes impossible. The spark is thus extinguished, and the circuit remains open. Thus, protective circuits are only necessary for switches for low-frequency currents in special cases, such as explosion-proof environments. However, with the invention, medium-frequency alternating current can be switched using the switch, for example frequencies between 10 and 100 kHz. The time for the zero crossing is very short.Thus, the time it takes for the current to drop below critical values ​​is very short, and the ionization of the air is maintained. Sparking remains active, and the switch cannot interrupt the alternating current. This is particularly true for very small and compact switches. Therefore, the invention is advantageous at such high frequencies. The protection module used prevents the occurrence of high voltages when interrupting the alternating current. This prevents the initial formation of spark gaps, making the interruption of medium-frequency alternating currents possible using such small switches. Furthermore, the switch is prevented from burning out.

[0025] In an advantageous embodiment, the protection module is arranged in parallel with a switch that can be used to disconnect the current to a coil. This is advantageous because the overvoltage generated when the switch is opened can be absorbed.

[0026] Key features of the contactless power transmission system with a protection module include a protection module at the output of the feed-in circuit that injects the medium-frequency alternating current into the primary line. This increases system safety by preventing overvoltages and sparking without knowing the exact individual events in the system, such as the shutdown of sections or the activation of loads, etc.

[0027] In an advantageous embodiment, a first protection module is provided on the primary side and / or a second protection module on the secondary side. This is advantageous because the same protection module can be used in different areas, thus increasing the number of units required, thus keeping costs low. Furthermore, a switch can also be used on the secondary side, thus allowing for very good control of the energy flow.

[0028] In an advantageous embodiment, the system for contactless energy transmission to a primary line comprises inductively coupled loads, wherein a substantially constant medium-frequency alternating current is injected into the primary line, in particular, essentially independent of the power drawn by the loads. The advantage here is that the current can be injected independently of the number of loads and the power drawn, and thus the current only needs to be regulated by the feed-in to keep it essentially constant.

[0029] In an advantageous embodiment, the load comprises one or more capacitors connected in series and / or parallel with a secondary coil supplying the load such that the corresponding resonant frequency essentially corresponds to the center frequency. This is advantageous because a large air gap can be realized.

[0030] In an advantageous embodiment, each short-circuitable section of the line is assigned a protection module. This has the advantage of reducing overvoltages that occur during the short-circuiting process.

[0031] In an advantageous embodiment, at least two protection modules are provided. The advantage here is that the same protection modules can always be used.

[0032] Further advantages arise from the subclaims. List of reference symbols 1 medium-frequency voltage source 2 Gyrators 3 first section 4 second section 5 inductively supplied consumers 6 inductively supplied consumers S1 switch S2 switch D1, D2, D3, D4 diodes C1 capacitor R1 resistor SM1 protection module SM2 protection module SM3 protection module

[0033] The invention will now be explained in more detail with the aid of illustrations: In the Fig. 1 shows a protection module for a switch according to the invention. Fig. Figure 2 shows a system for contactless energy transmission, with the protection modules provided at various locations in the system.

[0034] The protection module comprises a rectifier, for example composed of the diodes D1, D2, D3, D4, at least one capacitance, for example as capacitor C1, and at least one discharge resistor R1 for discharging the capacitance.

[0035] If an overvoltage, i.e., a short-term voltage spike, occurs between terminals A1 and A2 of the protection module, the associated energy is absorbed by capacitor C1. This is then discharged via the discharge resistor R1. The protection module absorbs small or large voltage spikes.

[0036] The system according to Fig. 2 comprises a medium-frequency voltage source 1 which can be supplied with three-phase current, comprises a corresponding rectifier and smoothing capacitor, and an output stage which can be supplied therefrom and which comprises power semiconductor switches which can be controlled and operated by a control circuit in a pulse-width modulated manner to generate medium-frequency alternating voltage which is fed to a gyrator 2.

[0037] This transforms the voltage source behavior U1 into a current source behavior I1. Its resonant frequency essentially corresponds to the center frequency.

[0038] This power source supplies primary conductors of track sections, whose line inductances are tuned by serially arranged capacitors in such a way that the resonance frequency of the track section essentially corresponds to the center frequency.

[0039] An essentially constant medium-frequency alternating current flows in the forward and return conductors of the operated sections of the line.

[0040] The loads 5, 6 can be supplied inductively. The loads (5, 6) comprise a secondary coil that is inductively coupled to the primary conductor of the track sections (3, 4). Furthermore, a capacitor is connected in series or parallel to this coil, dimensioned such that the corresponding resonant frequency essentially corresponds to the center frequency. In this way, a high degree of efficiency of the contactless energy transfer can be achieved, even though a large air gap is provided between the primary conductor and the secondary coil.

[0041] The protection module is located in the primary conductor area. The primary line comprises closed loops, each with a forward conductor and a return conductor. A predominantly impressed alternating current flows through these loops, as the gyrator exhibits current-source behavior on the output side. Therefore, a voltage exists at the gyrator on the output side, which increases with increasing power consumption by the loads. The voltage at the gyrator also increases when additional sections or lines are connected in the primary conductor area. The protection module is positioned between the forward conductor and return conductor in such a way that it prevents the destructive risk of overvoltages or voltage spikes. To achieve this, the protection module absorbs a corresponding amount of energy in a very short time, thus preventing overvoltages, sparking in switches, and the like.These occur particularly when rapid current commutations occur, such as when switching off or disconnecting sections of a line. The absorbed energy is then converted into heat via the discharge resistor. During normal operation, when the voltage changes, the capacitor of the protection module is initially charged or discharged until the capacitor voltage essentially corresponds to the peak value of the AC output voltage at the gyrator. With constant power consumption by the loads, the peak voltage remains constant, and thus also the voltage across the capacitor.

[0042] If a section of the line is short-circuited, for example, by short-circuiting switch S1, the power drawn drops, and the gyrator output voltage drops accordingly. A residual current still flows through S2 in section 4. If switch S2 is subsequently opened to safely shut off all currents in this section 4, the line inductance of the primary line is reduced, and the continuing, essentially constant current, which now flows only through S1, can lead to a brief increase in the gyrator output voltage, which is intercepted by the protection module SM1.

[0043] The SM2 protection module is installed in parallel with switch S1. When the switch is closed, the voltage drop across the switch is negligible. Therefore, the voltage across the protection module's capacitor is also negligible. However, if switch S1 is opened, the voltage across switch S1 could reach dangerously high values ​​if the protection module were not present. This resulting overvoltage is absorbed by the SM2 protection module and thus prevented.

[0044] Furthermore, such a protection module can also be provided on the secondary side. In other embodiments of the invention, an overtemperature shutdown is provided to protect the secondary coil. A protection module SM3 can be arranged on the associated switch S3, again to prevent sparking and overvoltages.

[0045] Preferably, the protection module is always provided in parallel with electrical or electronic switches. Electrical switches include, at least, relays, contactors, and the like. Electronic switches include, at least, controllable power semiconductors such as IGBTs, MOSFET power switches, transistors, thyristors, and the like.

[0046] The loads (5, 6) are supplied with energy contactlessly via the inductive coupling to the primary line. These loads include, for example, electric drive systems requiring more than 100 W. In initial embodiments, information is transmitted by modulated current components higher than the medium frequency. Frequencies between 10 and 100 kHz can advantageously be used as the medium frequency. Thus, frequencies of 100 kHz and above can be used for information transmission. In other embodiments, information can be transmitted using leaky waveguides laid parallel to the primary line or other systems. Additionally, tracking systems can also be arranged in the loads, which enable tracking of the load along the primary line by using sensor coils to detect the relative deviation from the primary line position.

[0047] It is particularly advantageous if the protection module is mounted on a switch located on the secondary side. This is described in the Fig. 3 to 8, wherein a part of the consumer 6 is Fig. 2 is shown in more detail or the secondary circuit is modified overall.

[0048] In Fig. 3, the secondary coil is designed with inductance L, followed in series by capacitance C. The value of L and C is such that the corresponding resonant frequency essentially corresponds to the center frequency of the medium-frequency current impressed in the primary line. The load is labeled V and comprises, for example, a rectifier with a smoothing capacitor from which an electrical device or an electronic circuit is supplied. The switch S is arranged such that the current in the secondary coil can be interrupted. Thus, the entire secondary-side circuit can be switched off. In particular, the switch interrupts the current once a critical temperature in the area of ​​the secondary coil is exceeded.

[0049] For this purpose, in one embodiment according to the invention, the switch is designed as a bimetallic switch and is thermally well coupled to the coil. This increases safety because further heating of the coil area can be prevented if a critical temperature is exceeded.

[0050] A protection module SM is connected in parallel with switch S. This prevents sparks or similar incidents when the switch is interrupted. This increases the service life of switch S and also the safety of the system.

[0051] In another embodiment of the invention, the switch S is not designed as a bimetallic switch, but as a switch with the same effect.

[0052] In another embodiment according to the invention, the switch S is designed as a controllable switch, wherein the signal voltage for controlling is provided as a function of the temperature values ​​detected by a temperature sensor for detecting the secondary coil.

[0053] In the Fig. 4, instead of a serial arrangement of L and C, a parallel arrangement is chosen, whereby again the values ​​of L and C are chosen such that the resonance frequency essentially corresponds to the center frequency. Fig. 4 the current of the now parallel resonant circuit is separated.

[0054] In the Fig. 5, the secondary coil is divided into two partial windings with inductances L1 and L2, with the switch S and protection module being arranged on the partial winding with L2. The dimensioning is as in Fig. 3, where L = L1 + L2 is selected. Thus, when winding L2 is short-circuited, the resonant circuit is detuned by means of switch S such that only a very small current is transmitted via the inductive coupling between L1 and the primary line. With weak coupling, for example a large air gap, only a small residual current is transmitted and the load can essentially not be supplied. However, in a further embodiment of the invention, a circuit part can be provided on the load which can be supplied from the residual current and thus also controls functions for emergencies, such as a display, other types of information or a corresponding signal voltage.

[0055] In Fig. 6 shows the corresponding embodiment, where the resonant circuit is designed in parallel and consists of the capacitance C and the inductance L = L1 + L2. The operating principle is the same as in Fig. 5 in an analogous way about the detuning of the resonant circuit from the figure.

[0056] In Fig. 7, the transformer T is arranged in the current path of switch S, so that its secondary coil can be used to supply a control circuit CTR of switch S2. Thus, when the critical temperature is exceeded for the first time and switch S is short-circuited, the now energized control circuit CTR closes switch S2. Even if the temperature subsequently falls below the critical temperature again, switch S2 remains closed, and the fault that led to the critical temperature being exceeded cannot recur. Only switching off the primary current can then open switch S2.

[0057] In Fig. 8 is the corresponding circuit as in Fig. 7, but the oscillating circuit is as in Fig. 6 is executed.

Claims

[1] Part of the plant, comprising a secondary coil inductively coupled to a primary conductor system, which is connected in series or parallel with a capacitance such that the associated resonant frequency substantially corresponds to the alternating current frequency of the primary current, wherein a switch is provided as a decoupling means, with which, when a critical temperature in the region of the coil winding is exceeded, part of the winding of the secondary coil is short-circuited and thus the resonance frequency is detuned in such a way that the flow of the resonance current component is prevented. [2] Plant part according to claim 1, characterized by that the switch or a temperature sensor influencing and / or determining the switching state of the switch is thermally connected to the secondary coil. [3] Plant part according to one of the preceding claims, characterized by that the secondary coil and switch are integrated. [4] Plant part according to one of the preceding claims, characterized by that the switch includes a bimetallic element. [5] Plant part according to one of the preceding claims, characterized by that a further controllable switch is assigned to the switch, which can be controlled from a control in such a way that the state of the system part caused by the change in the switching state of the first switch can be permanently maintained as long as the primary current is impressed in the primary conductor system. [6] Plant part according to claim 5, characterized by that the control can be supplied from the switch current via a transformer. [7] Plant part according to one of the preceding claims, characterized by that a varistor or a protection module is provided on the switch, which comprises at least one rectifier which is provided for charging a capacitor with which a discharge resistor is connected in parallel. [8] Plant part according to claim 7, characterized by that the protection module is provided in parallel with a switch to prevent overvoltages and / or sparking. [9] Plant part according to one of the preceding claims, characterized by that the switch is intended for switching a medium-frequency alternating current. [10] Plant part according to one of the preceding claims, characterized by that the capacitance of the protection module has a value between 0.1 millifarads and 10 millifarads, with the current having an effective value of less than 100 amperes. [11] Plant part according to one of the preceding claims, characterized by that an additional protection module is provided at the output of a power source of the system. [12] Plant part according to one of the preceding claims, characterized by that an additional protection module is provided on a switch for short-circuiting and / or disconnecting a section of track. [13] Plant part according to one of claims 1 to 10, characterized by that the protection module is provided in parallel to the switch with which part of the coil winding can be short-circuited. [14] System for contactless energy transmission with a contactless inductively supplied system part, wherein at least one switch is provided as a decoupling means for a secondary coil, characterized by , that When a critical temperature in the area of ​​the coil winding is exceeded, a part of the winding of the secondary coil is short-circuited by means of the switch and the resonance frequency is thus detuned in such a way that only the resonance current is prevented from flowing. [15] Plant according to claim 14, characterized by that a protection module is provided at the output of the feed-in circuit that injects the medium-frequency alternating current into the primary line [16] Installation according to claim 14 or 15, characterized bythat a first protection module is provided on the primary side and / or a second protection module is provided on the secondary side. [17] Installation according to one of claims 14 to 16, characterized by that the system for contactless energy transmission to a primary line comprises inductively coupled consumers, wherein a substantially constant medium-frequency alternating current is impressed into the primary line. [18] Plant according to claim 17, characterized by that the consumers comprise one or more capacitors which are connected in series and / or parallel with a secondary coil supplying the consumer in such a way that the corresponding resonance frequency essentially corresponds to the center frequency. [19] Installation according to one of claims 14 to 18, characterized by that each short-circuitable section of the route is assigned a protection module. [20] Installation according to one of claims 14 to 19, characterized bythat at least two protection modules are provided.

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