EP4183037A1

EP4183037A1 - Voltage converter having overvoltage protection

Info

Publication number: EP4183037A1
Application number: EP21745971.8A
Authority: EP
Inventors: Sebastian Blume; Thomas SCHIEMER; Tim HUBER; Djordje Vukovic
Original assignee: B&R Industrial Automation GmbH
Current assignee: B&R Industrial Automation GmbH
Priority date: 2020-07-16
Filing date: 2021-07-15
Publication date: 2023-05-24
Also published as: WO2022013367A1; US20230275420A1; CN116210149A; JP2023537666A

Abstract

In order to provide improved overvoltage protection for a voltage converter (2) for converting an input voltage (ue, Ue) into an output DC voltage (Ua), a first shut-off unit (11) is provided which is designed such that, when a first voltage threshold (Ux1) is reached or exceeded by the output DC voltage (Ua), it switches off at least one part of the voltage converter (2) in order to reduce the output DC voltage (Ua). A second shut-off unit (12) is also provided, which is designed to check whether an average value of the output DC voltage has reached or exceeded an average value threshold (Uxm), and when the average value threshold (Uxm) is reached or exceeded, it switches off at least one part of the voltage converter (2) in order to reduce the output DC voltage (Ua).

Description

Voltage converter with overvoltage protection

The present invention relates to a voltage converter for converting an input voltage into an output direct voltage, comprising a first switch-off unit which is designed to switch off at least part of the voltage converter when the equalizing direct voltage reaches or exceeds a first voltage threshold in order to to reduce the output DC voltage. Furthermore, the present invention relates to a method for monitoring an output DC voltage of a voltage converter, wherein a first voltage threshold is provided and wherein when the first voltage threshold is exceeded or reached by the output DC voltage, at least part of the voltage converter is switched off in order to reduce the output DC voltage to reduce.

In electrical systems such as long-stator linear motors or planar motors, actuators are supplied with an output DC voltage by a voltage converter. For this purpose, the output DC voltage is converted from a (usually higher) input voltage using a corresponding voltage converter. If an input DC voltage is converted into an output DC voltage, then a DC voltage converter is provided as the voltage converter. If an AC input voltage is converted into a DC output voltage, a rectifier is provided as a voltage converter. It can also be provided that a rectifier first converts an AC line voltage into a low DC voltage and then the low DC voltage is converted into a small DC voltage via a converter stage of the rectifier or a separately designed DC voltage converter.

The output DC voltage is in a specific voltage range, for example an extra-low voltage range and/or a low-voltage range. The respective voltage range has an upper voltage limit which must not be exceeded by the output DC voltage. Joule heat losses can be minimized in order to increase the efficiency of voltage converters that provide an output direct current. This can be done by the output DC voltage being as close as possible to an upper voltage limit of the associated voltage range. However, to ensure that the output DC voltage does not exceed the voltage limit, it is necessary to monitor the output DC voltage with high precision. For this purpose, a protective circuit for monitoring a voltage threshold can be provided, with the voltage threshold being in the range of the voltage limit of the voltage range. If the voltage threshold is exceeded, it is ensured that at least part of the voltage converter is switched off in order to reduce the output DC voltage and thus keep the voltage threshold being exceeded as short as possible. However, this means that even if the limit is exceeded briefly, as occurs with dynamic load changes, there is a switch-off - although such a short-term excess is not to be classified as critical.

It is an object of the present invention to specify improved overvoltage protection for a voltage converter.

This object is achieved by providing a second switch-off unit, which is designed to check whether a mean value of the output DC voltage has reached or exceeded a mean value threshold and, if the mean value threshold is reached or exceeded, to switch off at least part of the voltage converter in order to to reduce the output DC voltage.

Furthermore, the object is achieved by a method in which it is checked whether a mean value of the output DC voltage reaches or exceeds a mean value threshold, and when the mean value threshold is reached or exceeded, at least part of the voltage converter is switched off in order to reduce the output DC voltage to reduce.

A square mean value (also called the RMS mean value) is preferably considered as the mean value. An arithmetic mean value, for example, can also be considered as the mean value.

Due to the additional monitoring of the mean value of the output DC voltage, the first voltage threshold can be provided as close as possible below the upper voltage limit, which minimizes current heat losses of the voltage converter and increases the efficiency of the voltage converter. In the case of brief peaks in the DC output voltage, the mean value of the DC output voltage is only slightly increased and the mean value threshold is not exceeded. In the event of brief peaks in the output DC voltage, there is therefore no shutdown provided the first voltage threshold is not exceeded. This means that dynamic loads can also be supplied by the output DC voltage. The mean value threshold is preferably lower than the first voltage threshold.

It is particularly advantageous if power switches of the voltage converter are deactivated when the first voltage threshold is reached or exceeded and/or when the mean value threshold is reached or exceeded, for example by directly intervening in a gate control of the power switches. It can also be someone else part or all of the voltage converter is switched off; it is important that the output DC voltage drops as a result of this shutdown.

The second switch-off unit can be an integral part of the voltage converter, preferably an integral part of the first switch-off unit.

The first voltage threshold is preferably below a first voltage limit. Provision is made for the output DC voltage to be reduced within a microsecond or more quickly after the at least part of the voltage converter has been switched off. After the first voltage threshold has been reached or exceeded, a switch-off signal is triggered, whereby at least part of the voltage converter is switched off. However, there may be a switch-off delay between the signal being triggered and the actual switch-off. Due to the switch-off delay, the situation can arise in which the output DC voltage rises above the voltage threshold to a certain extent, even after the switch-off signal has been triggered, before it finally drops. Therefore, by setting the first voltage threshold below the voltage limit, it can be ensured that the first voltage limit itself is not exceeded even if a switch-off delay occurs. With a first voltage limit of 70.2 V, for example, a first voltage threshold in the range from 60 to 70 V, preferably 60 to 65 V, can be provided.

The averaging threshold is preferably below an averaging limit (where the averaging limit is below the first voltage limit). It must be ensured that the mean value of the output DC voltage does not reach or exceed the mean value limit. With an average limit of 60 V, for example, an average threshold of 59.25 V can be provided.

When determining the first voltage limit and/or the mean value threshold, component tolerances, measurement errors, etc. can also be taken into account.

If the mean value of the output DC voltage reaches or exceeds the mean value threshold, at least part of the voltage converter is switched off.

A second voltage threshold, lower than the first voltage threshold, can be provided. If at a first point in time it is detected that the output DC voltage has reached or exceeded the second voltage threshold, then when the output DC voltage reaches or exceeds the second voltage threshold at a second point in time after an interval has elapsed from the first point in time, a reaching or a Exceeding the mean value threshold by the mean value of the output DC voltage closed. The second switch-off unit can be configured to detect at a first point in time when the output DC voltage reaches or exceeds a second voltage threshold that is lower than the first voltage threshold, and at a second point in time after a specified interval has elapsed from the first point in time when the to check the second voltage threshold by the output DC voltage and, if the second voltage threshold is reached or exceeded both at the first point in time and at the second point in time, to conclude that the mean value of the output DC voltage has reached or exceeded the mean value threshold.

Discrete sampling times can be used here as the first and second times, at which the output DC voltage is sampled in a time-discrete manner by a voltage measuring unit provided, for example, in or on the voltage converter and measured in a time-discrete manner. For this purpose, however, it is also possible to use separate points in time, which lie apart from already given sampling points in time, at which the output DC voltage is measured specifically for the comparison with the second voltage threshold.

The use of discrete sampling times of the output DC voltage as the first and second time is also particularly advantageous if the output DC voltage is already sampled with a basic sampling rate in a time-discrete manner, for example due to a measurement by a voltage measuring unit mentioned above. This basic sampling rate for the basic measurement of the output DC voltage can be in the range of 100 kHz or in the MHz range, for example, with the first and second sampling times preferably not representing adjacent basic sampling times defined by the basic sampling rate, but being 0.01 to 100 ms apart, for example , or preferably 0.1 to 100 ms apart, or more preferably 1 to 100 ms apart. Preferably, the distance between the first sampling time and the second sampling time is fixed.

The first and second points in time can also be 0.01 to 100 ms apart, or preferably 0.1 to 100 ms apart, or particularly preferably 1 to 100 ms apart, independently of any sampling. The distance between the first point in time and the second point in time is preferably fixed.

In this sense, the second switch-off unit can be designed to conclude whether a, preferably quadratic, mean value of the output DC voltage has reached or exceeded a mean value threshold, with the mean value threshold being less than is the first voltage threshold, and if it is concluded that the mean value threshold has been reached or if it is concluded that it has been exceeded, to switch off at least part of the voltage converter in order to reduce the output DC voltage.

The conclusion that the second voltage threshold has been reached or exceeded both at the first point in time and at the second point in time that the mean value has reached or exceeded the mean value threshold represents a sufficient approximation in practice. In many practical cases, the comparison of the output DC voltage with a second voltage threshold at a first point in time and at a second point in time also represent a more conservative switch-off criterion than the presented comparison of a mean value with a mean value threshold. This is the case in particular when the first point in time and the second point in time are no further apart than 100 ms, for example.

A further aspect that can contribute to realizing a reliable and conservative criterion for a shutdown by comparing the output DC voltage with a second voltage threshold at a first point in time and at a second point in time is the level of the second voltage threshold. If the second voltage threshold is placed sufficiently far below the mean value threshold, it can be assumed in practice, given a suitable choice of the interval between the first point in time and the second point in time, that the conclusion is that the second voltage threshold has been reached or exceeded both at the first point in time and at the second point in time when the mean value reaches or exceeds the mean value threshold, this does not lead to any erroneous non-disconnections. On the contrary, it is sometimes switched off in cases in which the mean value does not actually reach or exceed the mean value threshold.

An example of a sufficiently low selection of the second voltage threshold is the selection of 59.25 V for the second voltage threshold with an average threshold of 60 V, but preferably 58 V can also be selected for the second voltage threshold in this case, most preferably also 57 V Basically, the person skilled in the field of safety technology knows how best to choose the voltage thresholds and the times for their comparison with the output DC voltage in a specific situation.

The interval begins when the second voltage threshold is reached or exceeded at the first point in time and ends at the second point in time. This is a particularly cost-effective way of monitoring the mean value of the DC output voltage. Since, after the second voltage threshold has been reached or exceeded at the first point in time, at a second point in time it is again checked whether the second voltage threshold has been reached or exceeded and only in one case repeated reaching or exceeding a shutdown, it can be ensured that a / a short-term / s reaching / exceeding the second voltage threshold at the first time, eg due to a dynamic load change, a shutdown does not take place immediately. The shutdown only takes place if the second voltage threshold is reached or exceeded even after the interval has expired (ie at the second point in time). However, if the first voltage threshold is reached or exceeded at any point in time, there is always a shutdown.

It is also possible to check whether the second voltage threshold has been reached or exceeded only at the first time, and another voltage threshold different from the second voltage threshold can be checked for being reached or exceeded at the second time after the specified interval has expired. Preferably, however, whether the second voltage threshold has been reached or exceeded is checked both at the beginning of the interval (i.e. at the first point in time) and at the end of the interval (i.e. at the second second point).

If, after the specified interval has expired, it is checked that a voltage threshold other than the second voltage threshold has been reached or exceeded, the second switch-off unit can be configured to indicate a first point in time when the output DC voltage reaches or exceeds a second voltage threshold that is lower than the first voltage threshold detect and at a second point in time, after a predetermined interval has expired from the first point in time, to check whether the output DC voltage has reached or exceeded a third voltage threshold that is less than the second voltage threshold and, if the second voltage threshold has been reached or exceeded, both at the first point in time and at the second point in time, to conclude that the mean value of the DC output voltage has reached or exceeded the mean value threshold.

With an average threshold of 60 V, the second voltage threshold can be chosen as 59.25 V and the third voltage threshold as 58.25 V, or the second voltage threshold can be chosen as 58 V and the third voltage threshold as 57 V, or the second voltage threshold can be chosen as 57 V and the third voltage threshold of 55 V can be chosen. In principle, however, the person skilled in the field of safety technology knows how best to choose the voltage thresholds and the points in time for a comparison with the output DC voltage in a specific situation.

Of course, after the end of an interval, another interval can be provided with a first and second point in time, with a check for reaching or The second voltage source can be exceeded in order to conclude that the mean value of the output DC voltage has reached or exceeded the mean value threshold.

Preferably, the mean value of the DC output voltage is continuously calculated. Accordingly, the second switch-off unit can be designed to continuously form a mean value for the output direct voltage and to check whether the mean value of the output direct voltage reaches or exceeds a specified mean value threshold. The continuous calculation can be used in addition to or instead of checking whether the second voltage threshold has been reached or exceeded take place at the first and second point in time. The mean value is preferably calculated continuously over a predetermined mean value interval.

If a voltage measuring unit of the voltage converter outputs an incorrect voltage value for the DC output voltage, e.g. a measured voltage value of 0 V, this leads to an increase in the DC output voltage (whereby an incorrect measured voltage value, e.g. 0 V, is still displayed) and the output DC voltage as a result the first output threshold and/or the mean value of the output direct voltage reaches or exceeds the mean value threshold. However, if the first and/or second switch-off unit also uses the (incorrect) measured voltage values of the voltage measuring unit associated with the voltage converter to determine the output direct voltage/and/or the mean value of the output direct voltage, this achievement or exceeding of this value is indicated by the first and /or second shutdown unit not recognized.

However, an implausible voltage value can be identified by a plausibility check of the measured voltage values of the output DC voltage that are obtained. However, if, e.g. due to a defect in the voltage measuring unit of the voltage converter, such as a partial break in a resistor, measured voltage values are falsified in such a way that incorrect but plausible DC output voltages (i.e. DC output voltages that are fundamentally possible) occur, this faulty measured voltage value can occur cannot of course be recognized by a plausibility check.

Preferably, therefore, a first voltage measuring unit associated with the first switch-off unit for determining the DC output voltage is designed independently of a voltage measuring unit associated with the voltage converter for determining the DC output voltage and/or a second voltage measuring unit associated with the second switch-off unit for determining the DC output voltage independently of one of the Voltage converter associated voltage measuring unit for determining the output DC voltage executed. This prevents an impermissible measured voltage value from occurring for the first and/or second voltage measuring unit if a single error occurs in the voltage measuring unit of the voltage converter Output DC voltage is generated. Of course, it is particularly advantageous if the first and second switch-off units are designed to be independent not only of the voltage converter but also of one another, for example each having an independent voltage measuring unit. The entire first and/or second switch-off unit can also be designed independently of the voltage converter, with “independent” of course referring to checking whether the voltage thresholds and mean thresholds have been reached or exceeded; when at least part of the voltage converter is switched off, it is of course necessary to intervene in the function of the voltage converter in a suitable manner in order to reduce the output DC voltage.

The first and/or second disconnection unit is preferably designed to be double-fault-safe. A first circuit part and a further circuit part can be provided in each case, which is designed independently of the first circuit part. In this way, a simultaneous influence on the circuit parts by a single fault can be ruled out. For example, the first and further circuit parts can be redundant.

The voltage converter is preferably designed in such a way that a low voltage up to a voltage limit of 60 V is output as the DC output voltage.

The voltage converter is preferably a rectifier for converting an input AC voltage into the output DC voltage or a DC converter for converting an input DC voltage into the output DC voltage.

Furthermore, a long-stator linear motor or planar motor can be provided, which includes a number of actuators and a voltage converter according to the invention for supplying power to the number of actuators using the output DC voltage.

The present invention is explained in more detail below with reference to FIGS. 1 to 4, which show advantageous configurations of the invention by way of example, schematically and not restrictively. while showing

1 shows a voltage converter with a first and second switch-off unit,

2 independent voltage measuring units of a first and second disconnection unit,

3a an exceeding of the second voltage threshold at a first point in time, 3b an exceeding of the second voltage threshold at a first and second point in time,

4 a mean value threshold being exceeded by a mean value of the output DC voltage,

1a shows a voltage converter 2, which emits an output DC voltage Ua at an output. A voltage measuring unit VO is also provided, which determines the output direct voltage Ua at the output of the voltage converter 2 . The voltage converter 2 includes a voltage regulator 21, which regulates the output DC voltage Ua according to a predetermined setpoint voltage Usoll. For this purpose, the voltage regulator is supplied with the voltage value of the output direct voltage Ua by the voltage measuring unit VO of the voltage converter 2 . The voltage value of the output direct voltage Ua can be recorded continuously over time or sampled in a time-discrete manner. The voltage regulator 21 generates control signals S, which are specified for a power unit 20 of the voltage regulator 21 in order to regulate the output DC voltage Ua in accordance with the setpoint voltage Usoll. A rectifier can be provided as the voltage converter 2, which converts an input AC voltage ue present at an input into the output DC voltage Ua, or a DC voltage converter can be provided, which converts an input DC voltage Ue present at an input into the output DC voltage Ua walks The input AC voltage ue can also first be converted into an intermediate DC voltage at the voltage converter 2, with the intermediate DC voltage being converted into the output DC voltage Ua by a further stage of the voltage converter 2 or by a separately implemented DC voltage converter.

To determine the output direct voltage Ua, the voltage measuring unit VO can sample the output direct voltage Ua with a basic sampling rate at basic sampling times in a time-discrete manner, with the basic sampling rate preferably being in the range of 100 kHz.

The power unit 20 usually includes a number of power switches, which are controlled according to the control signals S. Since the functioning of voltage converters 2 is fundamentally known, it will not be discussed in any more detail at this point.

A number of actuators can be connected to the output of the voltage converter 2, the number of actuators being supplied with the output direct voltage Ua. The voltage converter 2 can, for example, supply actuators of a long-stator linear motor or planar motor with the output DC voltage. The voltage converter 2 includes a first switch-off unit 11, which is designed to switch off at least part of the voltage converter 2 when the equalizing DC voltage Ua reaches or exceeds a first voltage threshold Ux1, in order to reduce the output DC voltage Ua. It is thus ensured that the output direct voltage Ua does not reach or exceed the first voltage threshold Ux1 or only does so for a short time.

The voltage converter 2 also includes a second switch-off unit 12, which is designed to check whether a mean value Uam of the output direct voltage Ua has reached or exceeded a mean value threshold Uxm and, if the mean value threshold Uxa is reached or exceeded, to switch off at least part of the voltage converter 2 cause to reduce the output DC voltage Ua. The second switch-off unit 12 is shown here as an integral part of the voltage converter 2, but can also be designed separately.

The first and/or second switch-off unit 11, 12 can include microprocessor-based hardware, for example a computer or digital signal processor (DSP), on which appropriate software for performing the respective function is executed. The first and/or second switch-off unit 11, 12 can also comprise an integrated circuit, for example an application-specific integrated circuit (ASIC) or a field programmable gate array (FPGA), also with a microprocessor. However, the first and/or second switch-off unit 11, 12 can also comprise an analog circuit or analog computer. Mixed forms are also conceivable. It is also possible for different functions to be implemented on the same hardware

A possible shutdown of at least part of the voltage converter 2, both by the first shutdown unit 11 and by the second shutdown unit 12, is effected by shutdown signals A1, A2, which act on the power unit 20. Circuit breakers of the power unit 20 can be deactivated, for example, by means of corresponding switch-off signals A1, A2.

A first voltage measuring unit V1 associated with the first switch-off unit 11 is preferably provided, which is designed independently of the voltage measuring unit V0 associated with the voltage converter 2 . It is thus possible for the first switch-off unit 11 to determine the value of the output direct voltage Ua even if the voltage measuring unit V0 associated with the voltage converter 2 determines an incorrect value of the output direct voltage Ua.

A second voltage measuring unit V2 associated with the second switch-off unit 12 is preferably provided, which is designed independently of the voltage measuring unit V0 associated with the voltage converter 2 . That's it for the second switch-off unit 12 is able to determine the value of the output direct voltage Ua even if the voltage measuring unit VO associated with the voltage converter 2 determines an incorrect value of the output direct voltage Ua.

If a first and second voltage measuring unit V1, V2 are provided, which are designed independently of a voltage measuring unit VO associated with voltage converter 2, it is particularly advantageous if the first and second voltage measuring units V1, V2 are also designed independently of one another, as shown in Fig. 2 is shown. Alternatively, only a first voltage measuring unit V1 can be provided, which makes the value of the output DC voltage Ua available to both the first switch-off unit 11 and the second switch-off unit 12 .

It is preferably checked whether, at a first point in time t0, a second voltage threshold Ux2, smaller than the first voltage threshold Ux1, has been reached or exceeded by the output direct voltage Ua. If the output direct voltage Ua also reaches or exceeds the second voltage threshold Ux2 at a second point in time t1 after a predetermined interval T1 has elapsed from the first point in time t0, as indicated schematically in FIG. 1b, then it is concluded that the mean value Uam of the output voltage Ua has been exceeded . The second voltage threshold Ux2 preferably corresponds to the mean value threshold Uxm.

If the second voltage threshold Ux2 is briefly exceeded (e.g. due to dynamic load changes and corresponding short-term increased output DC voltage Ua) at the first point in time tO (at the beginning of the interval T1), there is no shutdown - provided the first voltage threshold Ux1 is not exceeded.

3a shows an exemplary output direct voltage Ua, with the output direct voltage Ua reaching and exceeding the second voltage threshold Ux2 at the first point in time tO, but not the second voltage threshold Ux2 at the second point in time t1 after the interval T1 has elapsed (more) achieved or exceeded. The at least part of the voltage converter 2 is therefore not switched off. The output direct voltage Ua also never reaches or exceeds the first voltage threshold Ux1 here, which means that there is also no switch-off in this regard.

If the output direct voltage Ua is greater than or equal to the second voltage threshold, Ux2, at the second point in time t1 after interval T1 has elapsed, at least part of the voltage converter 2 is switched off for this reason 3b shown.

To select the first point in time t0 and the second point in time t1, sampling times can be used in an advantageous manner, at which the output DC voltage is sampled in a time-discrete manner and measured in a time-discrete manner, for example by the voltage measurement unit VO. The basic sampling times, which are defined by the basic sampling rate of the voltage measuring unit VO, can in turn be used to select the sampling times. The first point in time t0 and the second point in time t1 are to be separated by a time interval, this time interval being for example a length of 0.01 to 100 ms, or preferably a length of 0.1 to 100 ms, or particularly preferably a length from 1 to 100 ms. The distance between the first point in time t0 and the second point in time t1 is preferably fixed.

Although FIGS. 3a and 3b show the use of the same second threshold Ux2 at the first point in time t0 and at the second point in time t1, the second threshold Ux2 can alternatively be used at the first point in time t0 and a third one at point in time t1 instead of the second threshold Ux2 Threshold Ux3 are used (not shown). In a preferred manner, the third threshold Ux3 is below the second threshold Ux2. However, it is also conceivable to choose a third threshold Ux3 that is above the second threshold Ux2.

The mean value Uam of the output direct voltage Ua can be continuously calculated in a calculation unit, which is preferably an integral part of the second switch-off unit, and whether a mean value threshold Uxm has been reached or exceeded can be checked. Such a course of the mean value Uam is shown in FIG. 4, with the output direct voltage Ua also being drawn in as a dotted line. The mean value Uam reaches the mean value threshold Uxm at the point marked x, whereby at least part of the voltage converter 2 is switched off, which causes a reduction in the output direct voltage Ua, as can be seen from the associated flattening curve. If the determined mean value Uam were lower than the mean value threshold Uxm, the at least part of the voltage converter 2 would not be switched off (unless the output direct voltage Ua reaches or exceeds the first voltage threshold Ux1).

In the following, a possible determination of a first voltage limit and a mean value limit will be described as an example.

If the voltage converter 2 is designed so that the output direct voltage Ua is in the extra low voltage range and also has overvoltage protection, then the voltage converter 2 is called a PELV system (protective extra low voltage). A PELV system must meet the standards DIN EN 61800-5-1 VDE 0160-105-1:2018-09 and DIN EN 60204-1 VDE 0113-1:2019-06. The standard EN61800-5-1 requires an electrical circuit with the following properties under point 3.21: The voltage does not consistently reach or exceed the ELV under both a single fault condition and normal conditions;

- Protective separation from circuits other than PELV or SELV;

Grounding devices for the PELV circuit, its accessible conductive parts, or both

In chapter 4.3.1.1 "Use of the relevant voltage classes (DVC)" the following is stated: Protective measures against electric shock depend on the classification of the circuits according to relevant voltages according to Table 3, which relates the limit values of the working voltage within the circuit to the DVC . The DVC thus specifies the required minimum degree of protection for the circuit.

The associated table 3 is set out in the following chapter 4.3.1.2 "Limit values of the DVC" and shows an output direct voltage with a mean value of maximum 60V for the voltage class DVC A.

According to Chapter 4.3.1.4.3, the following conditions are defined with reference to Table 3: The arithmetic mean value of the output DC voltage may not exceed the upper mean limit of 60 V and the periodic peak value may not exceed 1.17 times the upper mean limit, ie 60 V * 1.17 = 70.2V

In order to achieve maximum efficiency of the voltage converter 2, it is desirable to keep the output direct voltage Ua as high as possible. The periodic peak value, which represents a transient maximum value, is thus selected as the first voltage limit, ie at 70.2 V. A first voltage threshold Ux1 is defined, the value of which is advantageously set below the first voltage limit, for example 63 V If the output direct voltage Ua exceeds this first voltage threshold Ux1, at least part of the voltage converter 2 is switched off immediately in order to reduce the output direct voltage Ua.

Since a maximum mean value (RMS) of 60V is also specified for the DC output voltage Ua for classification as a low voltage system (DVCA), the second voltage limit is selected for the DC output voltage Ua in accordance with the maximum mean value, ie at 60 V. The The value of the mean value threshold Uam and/or the second voltage threshold Ux2 is preferably set below the second voltage limit, for example at 59.25 V. However, the second voltage threshold Ux2 can also correspond to the second voltage limit.

A mean value Uam of the output DC voltage Ua is formed over a predetermined mean value interval tm and a check is made to determine whether the mean value Uam is above a mean value threshold Uxm lies. If this is the case, then the additional condition Z is met and the system is switched off.

If the output direct voltage Ua does not reach or exceed the first voltage threshold Ux1 and if the mean value of the output direct voltage Ua does not reach or exceed the mean value threshold Ux2, then the voltage converter 2 falls into the DVCA class.

As explained above, the mean value Uam can be continuously calculated and compared with the mean value threshold Uxm and/or it can be concluded that the mean value Uam of the output direct voltage Ua has been reached or exceeded if the output direct voltage Ua at a first point in time tO and after reaches or exceeds a second voltage threshold Ua2 (which preferably corresponds to the mean value threshold Uxm) at a second time t1 in an interval T1.

Claims

patent claims

1. Voltage converter (2) for converting an input voltage (ue, Ue) into an output direct voltage (Ua), comprising a first switch-off unit (11), which is designed when a first voltage threshold (Ux1) is reached or exceeded by the DC compensation voltage (Ua) to switch off at least part of the voltage converter (2) in order to reduce the DC output voltage (Ua), characterized in that a second switch-off unit (12) is provided, which is designed to check whether a, preferably quadratic, mean value of the output DC voltage reaches or exceeds a mean value threshold (Uxm) and, when the mean value threshold (Uxm) is reached or exceeded, to switch off at least part of the voltage converter (2) in order to reduce the output DC voltage (Ua ) to reduce.

2. Voltage converter (2) according to claim 1, characterized in that the second switch-off unit (12) is an integral part of the voltage converter (2), preferably the first switch-off unit (11).

3. Voltage converter (2) according to claim 1 or 2, characterized in that the second switch-off unit (12) is designed, a first point in time (tO) of reaching or exceeding a second voltage threshold (Ux2), smaller than the first voltage threshold (Ux1), by the output DC voltage (Ua) and at a second point in time (t1) after a predetermined interval (T1) has elapsed from the first point in time (tO) when the second voltage threshold (Ux2) is reached or exceeded by the output DC voltage (Ua ) and, if the second voltage threshold (Ux2) is reached or exceeded both at the first time (tO) and at the second time (t1), to conclude that the mean value of the output direct voltage (Ua) exceeds the mean value threshold ( Uxm) reached or exceeded.

4. Voltage converter (2) according to one of Claims 1 to 3, characterized in that the second switch-off unit (12) is designed to continuously calculate the mean value (Uam) of the output direct voltage (Ua) and increase it with the mean value threshold (Uxm). to compare.

5. Voltage converter (2) according to one of claims 1 to 4, characterized in that one of the first switch-off unit (11) associated voltage measuring unit (V1) for determining the output DC voltage (Ua) independently of a voltage converter (2) associated voltage measuring unit ( V0) for determining the output direct voltage (Ua).

6. Voltage converter (2) according to one of claims 1 to 5, characterized in that one of the second switch-off unit (12) associated voltage measuring unit (V2) for determining the output direct voltage (Ua) independently of a voltage converter (2) associated voltage measuring unit ( VO) for determining the output direct voltage (Ua).

7. Voltage converter (2) according to one of claims 1 to 6, characterized in that the voltage converter (2) is a rectifier for converting an input AC voltage (ue) into the output DC voltage (Ua).

8. Voltage converter (2) according to one of claims 1 to 6, characterized in that the voltage converter (2) is a DC converter for converting an input DC voltage (Ue) into the output DC voltage (Ua).

9. Long-stator linear motor comprising a number of actuators and a voltage converter (2) according to any one of claims 1 to 8 for supplying power to the number of actuators through the output direct voltage (Ua).

10. planar motor, comprising a number of actuators and a voltage converter (2) according to any one of claims 1 to 8 for power supply of the number of actuators by the output DC voltage (Ua).

11. Method for monitoring an output DC voltage (Ua) of a voltage converter (2), wherein a first voltage threshold (Ux1) is provided and wherein when the first voltage threshold (Ux1) is reached or exceeded by the equalizing DC voltage (Ua), at least a shutdown part of the voltage converter takes place in order to reduce the output direct voltage (Ua), characterized in that it is checked whether a, preferably quadratic, mean value (Uam) of the output direct voltage (Ua) reaches or exceeds a mean value threshold (Uxm), and that when the mean value threshold (Uxm) is reached or exceeded, at least part of the voltage converter (2) is switched off in order to reduce the output direct voltage (Ua).

12. The method according to claim 11, characterized in that when the equalizing DC voltage (Ua) reaches or exceeds the first voltage threshold (Ux1) and/or the mean value threshold (Uxm) is reached or exceeded by the mean value (Uam), the circuit breaker of the voltage converter (2) be disabled.

13. The method according to any one of claims 11 to 12, characterized in that a second voltage threshold (Ux2) lower than the first voltage threshold (Ux1) is provided, that a first point in time (tO) of reaching or exceeding the second voltage threshold (Ux2), is detected by the output direct voltage (Ua) and that when the second voltage threshold (Ux2) is reached or exceeded by the output DC voltage (Ua) at a second point in time (t1) after an interval (T1) has elapsed from the first point in time (tO), this indicates that the mean value threshold (Uxm ) is closed by the mean value (Uam) of the output direct voltage (Ua).

14. The method as claimed in claim 13, characterized in that the second voltage threshold (Ux2) corresponds to the mean value threshold (Uxm).

15. The method according to any one of claims 11 to 14, characterized in that the mean value (Uam) of the output direct voltage (Ua) is calculated continuously