SAFETY TECHNOLOGY - VOLTAGE ISLAND, POWER REFERENCER, SUPPLY, AND METHOD FOR THE SAFE CONTROL OF PARALLEL-CONNECTED POWER SECTIONS OF A POWER REFERENCER

Abstract

Safety technology voltage island (22), with a transformer (150) for galvanically isolated coupling of a supply voltage (U) SI ) into the safety technology voltage island (22), at least one coupling module (228, 229) for galvanically isolated coupling in and / or coupling out of control signals (AS20) for a power electronics (62), and at least one isolating element (223) for galvanically isolated output of control signals (S) for a supply voltage (U) of the power electronics (62), wherein the power electronics (62) is designed to control a power-providing device (23) of a power section (20) of a power converter (1), which power section (20) is connected in parallel to another power section (30) of the power converter (1), and wherein the at least two power sections (20, 30) each provide a part of a maximum electrical power required by the load (5).

Description

[0001] The present invention relates to a safety technology voltage island, a power converter, a supply unit, and a method for safely controlling parallel-connected power units of a power converter.

[0002] WO 2013 / 028270 discloses systems and methods for providing safe torque-off signals using communication lines, wherein the signals can be provided, for example, as single-channel signals using DC voltage or AC voltage over two sets of twisted-pair wires. US 2013 / 0215654 A1 discloses a three-phase AC-to-DC converter, a conversion method, and a control system therefor.

[0003] DE 102 37 553 A1 describes a method and device for controlling the intermediate circuit voltage in a voltage-source converter with multiple sub-converters and separate, voltage-controlled intermediate circuits, as well as line-side converters assigned to the respective sub-converters. All sub-converters are controlled by a common voltage regulator, and the intermediate circuit voltage of a sub-converter or the average value of all intermediate circuit voltages is fed back to the input of the voltage regulator with a negative sign.

[0004] Power units, which may be included, for example, in a power converter, such as an inverter or a converter, or in a supply, provide power to a load, which may in particular be a motor of a production plant, etc., or an intermediate circuit.

[0005] The larger the load or the maximum electrical power required by it, the larger the power unit must be. However, the more electrical power the power unit has to provide, and therefore the larger the power unit, the higher the cost of the power unit. A power unit of this type also has the disadvantage that its efficiency drops as the power at the load decreases. This means that a relatively high power loss occurs when only a low power is required at the load. Such a situation arises, for example, when the power unit is only operated at partial load. Partial load operation in a press system occurs in particular when a press jaw intended for pressing a workpiece is not used for pressing but is only moved up for pressing.As a solution to this problem, the applicant is considering providing the electrical power required by the load through at least two power units connected in parallel, which can be switched on or off depending on the load operation. One example would be connecting power units in parallel to increase the output power. For example, if a power output of 1000 kW is required, four power units of 250 kW each are connected in parallel.

[0006] The problem here, however, is that even with such a circuit, safety functions in a machine must be guaranteed in compliance with currently valid rules and standards, such as DIN EN 62061, DIN EN 61800-5-2 or the international standard IEC 61508. For example, a safe shutdown of the power components (= "Safe Torque Off") is achieved by switching off the control of the power transistors.

[0007] Therefore, the object of the present invention is to provide a safety technology voltage island, a power converter, a power supply, and a method for safely controlling parallel-connected power units of a power converter, with which the aforementioned problems can be solved. In particular, a safety technology voltage island, a power converter, a power supply, and a method for safely controlling parallel-connected power units of a power converter are to be provided, in which the division of power units and safety technology for a machine or system equipped with the power units are ensured in compliance with currently applicable rules and standards.

[0008] This object is achieved by a safety technology voltage island according to patent claim 1. The safety technology voltage island comprises a transformer designed as a transmitter for the galvanically isolated coupling of a supply voltage into the safety technology voltage island, at least one coupling module for the galvanically isolated coupling and / or decoupling of control signals for power electronics, and at least one isolating element for the galvanically isolated output of control signals for a supply voltage of the power electronics, wherein the power electronics are designed to control a power-providing device of a power section of a power converter, which power section is connected in parallel to another power section of the power converter, and wherein the at least two power sections each provide a portion of a maximum electrical power required by the load.

[0009] By using power units connected in parallel, the performance of the power converter can be increased compared to a case where only a single power unit is used to provide the electrical power to the load. In this case, it is also possible for individual power units to be switched off during partial load operation. Another option is to design all or some of the power units redundantly in order to prevent the failure of individual units or the entire system. This can prevent production downtimes and, in critical processes such as those found in the chemical industry, prevent damage to a system linked to the failed power converter, which could be a drive or grid inverter. Costs can be saved by avoiding production downtimes and damage to the system.

[0010] The converter enables a safe supply of the electronics of parallel-connected power units. The converter includes integrated safety technology, even for parallel-connected power units. This has the advantage that the power supply (mains voltage) of the power unit does not need to be switched off to prevent the load from operating, for example, when a motor is starting or running as a load.

[0011] A further advantage is that the converter is designed in such a way that an operator of a system equipped with the converter has only one safety technology selection for all parallel-connected power units. This minimizes the wiring effort for the converter and thus the system, thus keeping the costs for the safety technology low.

[0012] Advantageous further embodiments of the safety technology voltage island are specified in the dependent patent claims.

[0013] In the safety technology voltage island, the supply voltage can be an input AC voltage, wherein the safety technology voltage island is designed to generate an output AC voltage that differs in frequency and amplitude from the input AC voltage, or the supply voltage can be an input DC voltage, wherein the safety technology voltage island is designed to generate an output DC voltage from the input AC voltage.

[0014] In one variant, the safety technology voltage island also has diodes to rectify the supply voltage.

[0015] In the case of the safety technology voltage island, it is possible that at least one isolating element is an optocoupler or capacitive coupler or inductive coupler or a high-resistance connection, and / or the safety technology voltage island is designed as a plug-in card.

[0016] The aforementioned object is also achieved by a power converter for providing electrical power for a load according to patent claim 5. The power converter comprises at least two power units, each for providing a portion of the maximum electrical power required by the load, wherein the at least two power units are connected in parallel, and a control unit for controlling the at least two power units, wherein the control unit is designed to provide a secure supply voltage for the at least two power units.

[0017] The power converter achieves the advantages previously mentioned in connection with the safety technology voltage island for the power converter.

[0018] Advantageous further embodiments of the power converter are specified in the dependent patent claims.

[0019] In the power converter, the control part can comprise: a safe supply voltage generating device for generating a safe supply voltage for the at least two power sections, wherein the safe supply voltage is provided for application to the at least two power sections, and a safety control device for two-channel control of the safe supply voltage generating device and for carrying out a diagnosis of the control of the safe supply voltage generating device.

[0020] In the power converter, the at least two power units may each comprise: a power-providing device for providing electrical power to the load, and a PWM signal generating device for generating control signals for the power-providing device. In this case, the at least two power units may each comprise a previously described safety technology voltage island, which is connected between the PWM signal generating device and the power-providing device.

[0021] The aforementioned object is also achieved by a supplier for providing electrical power for an intermediate circuit according to patent claim 9. The supplier comprises at least two power units, each for providing a portion of the maximum electrical power required by the intermediate circuit, wherein the at least two power units are connected in parallel, and a control unit for controlling the at least two power units, wherein the control unit is designed to provide a secure supply voltage for the at least two power units.

[0022] The utility achieves the same benefits for the power converter as previously mentioned with regard to the safety technology voltage island.

[0023] The object is further achieved by a method for the safe control of parallel-connected power components of a power converter according to patent claim 10. The method has the steps of: galvanically isolated coupling, galvanically isolated coupling and / or decoupling, and galvanically isolated output, with at least one isolating element, as specified in claim 10.

[0024] The method achieves the same advantages for the power converter as previously mentioned with regard to the safety technology voltage island.

[0025] Further possible implementations of the invention also include combinations of features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0026] The invention is described in more detail below with reference to the accompanying drawings and exemplary embodiments. They show: Fig. 1 is a block diagram of a power converter according to a first embodiment; Fig. 2 shows a block diagram of a voltage island of the power converter according to a second embodiment; and Fig. 3 a block diagram of a supplier according to a third embodiment.

[0027] In the figures, identical or functionally equivalent elements are provided with the same reference numerals unless otherwise indicated.

[0028] Fig. Figure 1 shows a power converter 1, which is part of a higher-level system 5, such as a press system. The power converter 1 supplies electrical energy or power to a load 7 via power lines 8.

[0029] The power converter 1 can be, for example, an inverter. The power converter 1 can also be, for example, a converter. The load 7 can be, for example, an electrical machine, such as a motor or generator.

[0030] In Fig. 1, the power converter 1 comprises a control section 10, a first power section 20, and a second power section 30. The power sections 20, 30 are connected in parallel. The power sections 20, 30 can each provide a portion of the total electrical energy or power required by the load 7 during full-load operation. In particular, the power sections 20, 30 each provide half of the total electrical energy or power required by the load 7 during full-load operation.

[0031] The control part 10 comprises a safety control device 11 and a safe supply voltage generating device 12. The devices 11, 12 can each be implemented as a plug-in card. The safety control device 11 controls the safe supply voltage generating device 12 via a line 13 using two channels and performs a diagnostic check of the control. Consequently, the safe supply voltage generating device 12 is monitored by the safety control device 11. The safe supply voltage generating device 12 generates a safe supply voltage U SI for the power units 20, 30. The safe supply voltage U SIis applied to the first power section via the first line 15 and to the second power section 30 via the second line 16. If, in another variant, more than two parallel-connected power sections 20, 30 are present, the voltage islands in the additional power sections can be supplied by extending line 15 or 16 to these additional power sections.

[0032] The first power unit 20 has in Fig. 1 a PWM signal generating device 21, a safety technology voltage island 22, and a power-providing device 23. The PWM signal generating device 21 can, for example, be a logic device, which can in particular be a processor, FPGA (FPGA = Field Programmable Gate Array = (logic) gate arrangement programmable in the (application) field), etc. The power-providing device 23 can, for example, be a DC / AC converter, also called a DC / AC converter, and is in particular a power transistor. The PWM signal generating device 21 generates one or more PWM signals (PWM = pulse width modulation) as control signal(s) AS20 for controlling the power-providing device 23. The safety technology voltage island 22 is connected between the PWM signal generating devices 21 and the power-providing device 23.The safety technology voltage island 22 ensures the safe shutdown of the control signals AS20 generated by the PWM signal generating device 21 and output via line 25. Thus, the control signals AS20 generated by the PWM signal generating device 21 and output via line 25 are only output to the power-providing device 23 via line 26 if the safety technology voltage island 22 does not cause these control signals AS20 to be shut down. If the power-providing device 23 is controlled by control signal(s) AS20 from the PWM signal generating device 21, the power section provides electrical power to the load 7. As a result, the load 7 can be operated accordingly; for example, a motor can start, the already running motor can be operated at a higher speed, etc., if the load 7 is a motor.

[0033] The second power unit 30 has in Fig. 1, a PWM signal generating device 31, a safety technology voltage island 32, and a power-providing device 33. The PWM signal generating device 31 can be, for example, a logic device, which can in particular be a processor, FPGA (FPGA = Field Programmable Gate Array = logic gate arrangement programmable in the (application) field), etc. The power-providing device 33 can, for example, be a DC / AC converter, also called a DC / AC converter, and is in particular a power transistor. The PWM signal generating device 31 has the same function as the PWM signal generating device 21 and generates one or more PWM signals (PWM = pulse width modulation) as control signal(s) AS30 for controlling the power-providing device 33. The safety technology voltage island 32 has the same function as the safety technology voltage island 22.And the power-providing device 33 has the same function as the power-providing device 23. Therefore, for the second power section 30, reference is made below to the previous description with respect to the second power section 20. If, in another variant, more than two parallel-connected power sections 20, 30 are present, the additional parallel-connected power sections are constructed according to the same scheme as previously described with respect to the power sections 20, 30.

[0034] In a method for the safe control of parallel-connected power units 20, 30 of the power converter 1, the safety technology of the power converter 1 of the system 5 is selected by an operator via the control unit 10. In this case, one or more dynamic selection signals AW are fed into the safety control device 11. In the safety control device 11, the selection signals AW for the internal safety technology are dynamically monitored and activated. Depending on the selection signals AW, the safe supply voltage generation device 12 is enabled or disabled. The safety control device 11 decides whether the selection signals AW generate the safe supply voltage U SI by the safe supply voltage generating device 12 or not. This allows the generation of the safe supply voltage U SIswitched on or off. Thus, due to the selection of the safety technology by an operator using the selection signal(s) AW, the safe supply voltage U SI be turned on or off.

[0035] If the safe supply voltage generating device 12 generates a safe supply voltage U due to one or more selection signals, SIgenerated, the safe supply voltage is applied or distributed to all parallel-connected power units 20, 30 via the first and second lines 15, 16. In the power units 20, 30, the control signal(s) AS20, AS30 are generated with the aid of the PWM signal generating devices 21, 31, which control the power-providing device(s) 23, 33 and thus generate a rotating field. This rotating field is available via the power lines 8 at the connections of the load 7. The load connections of the power units 20, 30 are connected to one another in such a way that phase U of the first power unit 20 is connected to phase U of the second power unit 30, phase V of the first power unit 20 is connected to phase V of the second power unit 30, and phase W of the first power unit 20 is connected to phase W of the second power unit 30 via the power lines 8. The load terminals of the power units 20, 30 are connected to the load 7 via the power lines 8.

[0036] In order to prevent operation of load 7, for example starting or starting a motor, when selecting the safety technology using the selection signal(s) AW, the control signal(s) AS20, AS30 are routed with power 25 via the safety technology voltage island 22 or with power 35 via the safety technology voltage island 32. If the respective safety technology voltage island 22, 32 is supplied with voltage, for example by a safe supply voltage U SIIf the power supply from the safe supply voltage generating device 12 is applied to the respective safety technology voltage island 22, 32 via lines 15, 16, the control signal(s) AS20, AS30 from the respective PWM signal generating device 21, 31 can reach the power-providing device(s) 23, 33 and generate a rotating field. However, if the respective safety technology voltage island 22, 32 is not supplied, the control signal(s) AS20, AS30 are blocked, and no rotating field can be generated. In the latter case, operation of load 7, for example, starting or starting a motor, is prevented due to the operator's selection of the safety technology.

[0037] The power converter 1 thus comprises an arrangement of devices, the power units 20, 30, which are suitable for generating an output AC voltage that differs in frequency and amplitude from an input AC voltage, wherein at least two such devices are connected in parallel and wherein a control means and / or regulating means in the form of the control unit 10 is provided for implementing a higher-level control function for the parallel-connected devices, wherein each device, the power units 20, 30, is connectable to an input DC voltage as well as to a supply voltage for operating the device electronics, wherein all devices are connected in parallel to the same supply voltage U SI are connected. The power converter 1 as an inverter thus has a DC voltage input and an AC voltage output.

[0038] According to the present embodiment, the two parallel-connected power units 20, 30 can be selected together with the safety technology. This reduces the required wiring effort for the safety technology of the two parallel-connected power units 20, 30.

[0039] In addition, the power converter 1 has an integrated safety technology even when the power units 20, 30 are connected in parallel: In order to prevent operation of the load 7, the voltage supply (mains voltage) of the power units 20, 30 does not have to be switched off in the power converter 1.

[0040] According to the present exemplary embodiment, the idea is implemented that the control section 10 or a "master" power section, i.e., the power section 20 or the power section 30, has a voltage source that can be safely switched off, the voltage source being initially irrelevant in its form (in particular, rectangular, sine, pulse, combinations thereof, etc.), in its magnitude (i.e., amplitude value), and in its type (i.e., DC voltage, AC voltage, 3-phase, single-phase). This voltage is distributed to the power sections 20, 30, on which a voltage island 22 is located, via which the control signals AS20, AS30 are passed on to the driver stages of the power sections 20, 30.

[0041] In a modification of the first embodiment, the control section 10 is integrated into the first power section 20. Thus, the first power section 20 can act as the master, i.e., the instruction provider, whereas the second power section 30 acts as the slave, i.e., the instruction receiver. Additional power sections could also be connected as slaves.

[0042] Fig. Figure 2 shows a second embodiment of a possible configuration of the safety technology voltage island 22, which can be used in the power section 20 of the first embodiment. The safety technology voltage island 22 can be implemented as a plug-in card.

[0043] Even if this is not shown in the figures, the safety technology voltage island 32 can be constructed in the same way as the safety technology voltage island 22. In addition, a safety technology voltage island of power units that may be present in another application can be constructed in the same way.

[0044] In Fig. 2, the safety technology voltage island 22 has two first diodes 221, two first resistors 222, two isolating elements 223, a second diode 224, a second resistor 225, a third diode 226, a series regulator 227, and digital coupling modules 228, 229. In the present embodiment, the safety technology voltage island 22 is supplied from the first line 15 with the safe supply voltage U S1 the safe supply voltage generating device 12 ( Fig. 1) supplied.

[0045] According to Fig. 2, the centrally generated, safely switchable supply voltage U SI from the first line 15 via a transformer 150. The PWM signal generating device 21, which is a non-safe source of IGBT drive signals, provides drive signals AS20 for the digital coupling module 228, so that the drive signals AS20 are transmitted via the galvanically isolated safety technology voltage island 22. The source 61 provides a non-safe supply voltage U for a driver stage or power electronics 62 for controlling the power-providing device 23 ( Fig. 1). Depending on the design of the driver stage or power electronics 62, it may be that, in order to comply with currently applicable rules and standards, such as DIN EN 62061, DIN EN 61800-5-2, or the international standard IEC 61508, components 221, 222, 223, 63, and 64 can be omitted, and deactivation of the control signals AS20 is sufficient. Alternatively, deactivation of the supply voltage of the driver stages or power electronics 62 is sufficient, and deactivation of the control signals via coupling modules 228 and 229 is not necessary.

[0046] If, in a method for the safe control of parallel-connected power units 20, 30 of the converter 1, the safe supply voltage U SIfed into the safety technology voltage island 22, the alternating voltage of the transformer 150 is rectified via the diodes 221, 224. With the rectified voltage paths with the resistors 222, 225, the isolating elements 223, which are in Fig. 2 are designed as optocouplers and serve to switch off the power supply to the power electronics 62, and supply voltage to the power supply or the series regulator 227 for the digital coupling modules 228, 229. However, at least one of the isolating elements 223 can also be a capacitive coupler or an inductive coupler or a high-impedance connection or high-impedance isolating point.

[0047] As from Fig. 2, in the method, the non-safe supply voltage U of the source 61 is switched off via the isolating elements 223 and transistors 64, 65 with the aid of control signals S as soon as the safe supply voltage U SIfrom the first line 15 via the transformer 150 is no longer supplied. The non-safe supply voltage U of the source 61 supplies both the power electronics 62 itself and, via a resistor 65, a power supply 66 for supplying the secondary side of the digital coupling modules 228, 229. Thus, all paths for transmitting the control signals AS20 are no longer supplied as soon as the central, safe supply voltage U SI on the first line 15 is switched off. Thus, the power electronics 62 and thus the power providing device 23 ( Fig. 1).can no longer be controlled, even if control signals AS20 continue to be output from the non-safe area, which includes elements 21 and 61 to 66.

[0048] Thus, the power converter 1 has integrated safety technology even when the power units 20, 30 are connected in parallel: Due to the described safety technology selection for all power units 20, 30 connected in parallel, the wiring effort for the power converter 1 and thus the system 5 is very low.

[0049] Thus, the power converter 1 represents a circuit component for providing control signals AS20 for the power electronics in the form of the power-providing device 23 of a device (the power section 20), which is suitable for generating an output AC voltage differing in frequency and amplitude from an input DC voltage. The power converter 1 comprises a first means in the form of the control section 10 for the galvanically isolated coupling of a supply voltage, a second means in the form of the coupling modules 228, 229 for the galvanically isolated coupling and decoupling of control signals for the power electronics, and a third means in the form of the isolating elements 223 for the galvanically isolated output of control signals for the supply voltage of the power electronics 62.

[0050] The safety technology voltage island 22 is a galvanically isolated circuit component. This has the advantage that a short circuit of an external signal for the safety technology voltage island 22 does not close a circuit. This ensures that the circuit function implemented on the safety technology voltage island 22 remains intact even in the event of a short circuit.

[0051] Fig. 3 shows a power supply 2 for a higher-level system 5 according to a third exemplary embodiment. A power supply 2 is essentially also a power converter. The power supply 2 is a power converter that draws its power from a grid and makes it available to an intermediate circuit 9 in the form of a direct voltage and a direct current. The power supply 2 is a power converter that is used as a regenerative grid inverter. In contrast, the power converter 1 of the first exemplary embodiment and its modification serves to drive a load 7, in particular a motor. Like the power converter 1 according to the first exemplary embodiment, the power supply 2 according to the third exemplary embodiment also has several power units 20, 30.

[0052] In Fig. 3, the supply unit 2 provides electrical energy or power to the intermediate circuit 9 via power lines 8. The power components 20, 30 are each designed as power transistors. The supply unit 2 is constructed in the same way as in Fig. 1. Therefore, reference is made below to the description of the first embodiment.

[0053] All previously described embodiments of system 5, power converter 1, power supply 2, power units 20, 30, and the method performed by them can be used individually or in any combination. In particular, all features and / or functions of the previously described embodiments can be combined as desired. In addition, the following modifications are conceivable.

[0054] The parts shown in the figures are schematic and may differ in their exact design from the forms shown in the figures, as long as their previously described functions are guaranteed.

[0055] The power units 20, 30 can be connected as a drive package or as a supply package or in another way.

[0056] The number of parallel-connected power units 20, 30 can be freely selected as required. Therefore, more than two parallel-connected power units 20, 30 can be present. In addition to the power units 20, 30, one or more power units can be provided, which are redundant to at least one of the power units 20, 30 and can replace at least one of the power units 20, 30 in the event of a failure.

[0057] The power units 20, 30 can each provide the same amount of power, for example, 250 kW, etc. However, it is also conceivable that one power unit of the power units 20, 30 provides a different amount of power than the other power units 20, 30. If more than one additional power unit is present as a redundant power unit, one or more additional power units can also replace more than one power unit of the power units 20, 30.

[0058] Load 7 does not have to be a three-phase or three-phase load. Load 7 can also be a single-phase or alternating current (AC) or direct current (DC) load. The same applies to intermediate circuit 9.

[0059] The power converter 1 or the supply unit 2 can be used in addition to or as an alternative to a press system in another system 5, such as a manufacturing system for objects such as vehicles, furniture, etc. It is also conceivable for the system 5 to be a rolling mill for rolling sheet metal and / or an injection molding system and / or a printing system, particularly for newspapers. However, other applications for the power converter 1 or the supply unit 2 in a system 5 are also possible, which can be, for example, a crane system, a pump system, an agitator, a ventilation system used, for example, for tunnel ventilation, or a power plant such as a wind and / or hydroelectric power plant.

Claims

[1] Safety technology voltage island (22), with a transformer (150) for the galvanically isolated coupling of a supply voltage (U SI ) into the safety technology voltage island (22), at least one coupling module (228, 229) for the galvanically isolated coupling and / or decoupling of control signals (AS20) for power electronics (62), and at least one isolating element (223) for the galvanically isolated output of control signals (S) for a supply voltage (U) of the power electronics (62), wherein the power electronics (62) is designed to control a power-providing device (23) of a power section (20) of a power converter (1), which power section (20) is connected in parallel to another power section (30) of the power converter (1), and wherein the at least two power sections (20, 30) each provide a portion of a maximum electrical power required by the load (5). [2] Safety technology voltage island (22) according to claim 1, wherein the supply voltage (U SI ) is an input alternating voltage and wherein the safety technology voltage island (22) is designed to generate an output alternating voltage different in frequency and amplitude from the input alternating voltage, or wherein the supply voltage (U SI ) is an input DC voltage and wherein the safety technology voltage island (22) is designed to generate an output DC voltage from the input DC voltage. [3] Safety technology voltage island (22) according to claim 1 or 2, further comprising diodes (221) for rectifying the supply voltage (U SI ). [4] Safety technology voltage island (22) according to one of the preceding claims, wherein at least one isolating element (223) is an optocoupler or capacitive coupler or inductive coupler or a high-resistance connection, and / or wherein the safety technology voltage island (22) is designed as a plug-in card. [5] Power converter (1) for providing electrical power for a load (7), having at least two power units (20, 30) for each providing a portion of the maximum electrical power required by the load (5), wherein the at least two power units (20, 30) are connected in parallel, and a control unit (10) for controlling the at least two power units (20, 30), wherein the control unit (10) is configured to provide a secure supply voltage (U SI ) for which at least two power units (20, 30) are designed. [6] Power converter (1) according to claim 5, wherein the control part (10) comprises a safe supply voltage generating device (12) for generating a safe supply voltage (U SI ) for the at least two power units (20, 30), wherein the safe supply voltage (U SI ) is provided for application to the at least two power units (20, 30), and a safety control device (11) for two-channel control of the safe supply voltage generating device (12) and for carrying out a diagnosis of the control of the safe supply voltage generating device (12). [7] Power converter (1) according to claim 5 or 6, wherein the at least two power sections (20, 30) each comprise a power providing device (23; 33) for providing electrical power for the load (7), and a PWM signal generating device (21; 31) for generating control signals (AS20; AS30) for the power providing device (23; 33). [8] Power converter (1) according to claim 7, wherein the at least two power sections (20, 30) each have a safety technology voltage island (22; 32) according to one of claims 1 to 4, which is connected between the PWM signal generating device (21; 31) and the power providing device (23; 33). [9] A supply (2) for providing electrical power for an intermediate circuit (9), comprising at least two power units (20, 30) for each providing a portion of the maximum electrical power required by the intermediate circuit (9), wherein the at least two power units (20, 30) are connected in parallel, and a control unit (10) for controlling the at least two power units (20, 30), wherein the control unit (10) is configured to provide a secure supply voltage (U SI ) for which at least two power units (20, 30) are designed. [10] Method for the safe control of parallel-connected power units (20, 30) of a power converter (1), comprising the steps of galvanically isolated coupling, with a transformer (150), a supply voltage (U SI) into a safety technology voltage island (22), galvanically isolated coupling and / or decoupling, with at least one coupling module (228, 229), of control signals (AS20) for power electronics (62), and galvanically isolated output, with at least one isolating element (223), of control signals (S) for a supply voltage (U) of the power electronics (62), wherein the power electronics (62) controls a power-providing device (23) of a power section (20) of a power converter (1), which power section (20) is connected in parallel to at least one other power section (30) of the power converter (1), and wherein the at least two power sections (20, 30) each provide a portion of a maximum electrical power required by the load (5).

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