Device with an energy accumulator and an electric machine which can be powered by an inverter and method for operating the device

Abstract

This invention relates to an apparatus having an energy storage device and a motor powered by an inverter, and a method for operating the apparatus, wherein the energy storage device forms a series circuit with a first fuse and one or more additional fuses, wherein a driveable contact, particularly a switch, particularly a contactor, is connected in parallel with one of the additional fuses, or a corresponding driveable contact, particularly a switch, particularly a contactor, is connected in parallel with multiple additional fuses respectively, wherein the series circuit supplies power to the DC voltage side interface of the inverter, wherein a device for detecting the voltage present in the series circuit is connected to an electronic control device, which generates a drive signal for one contact or for multiple driveable contacts, wherein, in particular, when the voltage is lower than a corresponding voltage threshold, the corresponding contact is disconnected.

Description

Technical Field

[0001] The present invention relates to a device having an energy storage device, a motor that can be powered by an inverter, and a method for operating the device. Background Technology

[0002] It is well known that inverters can be powered by energy storage devices connected to the DC voltage side interface of the inverter. Energy storage devices are typically known to be capacitors or batteries.

[0003] Furthermore, it is known that the fuse is triggered when the trigger current is exceeded.

[0004] According to DE 10 2013 012 578 A1, there is a device for ensuring the safety of electrical lines.

[0005] A power distribution unit and energy management system for electric vehicles is known from US 2019 / 0 140 245 A1. Summary of the Invention

[0006] Therefore, the object of the present invention is to further improve the safety of devices with inverters.

[0007] According to the invention, this objective is achieved in terms of the device according to claim 1 or 2 and in terms of the method according to claim 10.

[0008] An important feature of this invention in devices with energy storage devices is that the energy storage device forms a series circuit with a first safety device and one or more other safety devices.

[0009] Among them, a controllable contact, especially a switch, especially a contactor, is connected in parallel with another safety device, or corresponding controllable contacts, especially switches, especially contactors, are connected in parallel with multiple other safety devices respectively.

[0010] In this system, a device for detecting the voltage applied to the series circuit is connected to an electronic control device, which generates a drive signal for one contact or for multiple controllable contacts.

[0011] In particular, when the voltage is lower than the corresponding voltage threshold, the corresponding contact is disconnected.

[0012] Advantageously, protection is ensured for the correspondingly different fuses based on the voltage. Therefore, it is advantageous to consider that the maximum possible short-circuit current, limited by the internal resistance of the accumulator, is lower at lower voltages than at higher voltages. This improves safety and protection because the first fuse may not detect the short-circuit current and therefore will not be triggered in voltage ranges below a first threshold (i.e., the voltage threshold).

[0013] Preferably, the safety devices have the same structural type, so that the characteristic curves of different safety devices do not intersect, wherein these characteristic curves respectively represent the correlation between the trigger current and the duration of the current.

[0014] A key feature of the device according to claim 2 is that it is equipped with an energy storage device and a motor powered by an inverter, wherein the energy storage device forms a series circuit with a first fuse and one or more other fuses.

[0015] Among them, a controllable contact, especially a switch, especially a contactor, is connected in parallel with another safety device, or corresponding controllable contacts, especially switches, especially contactors, are connected in parallel with multiple other safety devices respectively.

[0016] The series circuit supplies power to the DC voltage side interface of the inverter.

[0017] The device used to detect the voltage present in the series circuit is connected to the electronic control device, which generates a drive signal for one contact or for multiple controllable contacts.

[0018] In particular, when the voltage is lower than the corresponding voltage threshold, the corresponding contact is disconnected.

[0019] Advantageously, protection is ensured for different fuses based on voltage, for example, protection due to a short circuit in the inverter's power electronics or at one of the inverter's interfaces. Therefore, it is advantageous to consider that the maximum possible short-circuit current, limited by the energy storage's internal resistance, is lower at lower voltages than at higher voltages. This improves safety and protection because the first fuse may not detect the short-circuit current and therefore will not be triggered in voltage ranges below a first threshold (i.e., the voltage threshold).

[0020] Preferably, the safety devices have the same structural type, so that the characteristic curves of different safety devices do not intersect, wherein these characteristic curves respectively represent the correlation between the trigger current and the duration of the current.

[0021] In an advantageous design, the electronic control device includes a comparator that compares the voltage with one or more threshold values ​​and generates a corresponding drive signal associated with the comparison result to drive one or more driveable contacts. It is advantageous that analog circuitry can also be used as the comparator, thus enabling a very fast response when the voltage is below the threshold. Preferably, in the event of a voltage drop, its value or trend over a period of time is pre-calculated, the time period being equal to or exceeding the response time for driving the contacts. Therefore, pre-calculating the voltage is advantageous in motor-type operation.

[0022] In an advantageous design, the minimum triggering current of the first fuse is greater than, in particular, at least five times or at least twice, the minimum triggering current of a fuse connected in parallel with another contact, and in particular, the minimum triggering current of the first fuse is greater than, in particular, the minimum triggering current of multiple fuses connected in parallel with multiple other contacts, also at least five times or at least twice. Advantageously, this provides protection against high voltages and adequate protection against low voltages, a capability that the first fuse cannot guarantee. Therefore, different voltages operate within different voltage ranges to provide protection.

[0023] In an advantageous design, the electronic control devices are powered by a power supply voltage. This is particularly advantageous in the event of a power supply voltage failure, where one or all contacts are disconnected. It is advantageous that the power supply voltage can be used in a simple manner, ensuring safety regardless of the voltage present on the accumulator. Preferably, a 24-volt voltage can be used as the power supply voltage.

[0024] In an advantageous design, the energy storage device has a double-layer capacitor or is designed as a double-layer capacitor, particularly where the double-layer capacitor is designed as a supercapacitor. Advantageously, the energy storage device can be manufactured inexpensively and a large capacity can be achieved in a simple manner.

[0025] In a favorable design, the corresponding fuses are designed as semiconductor fuses. Advantageously, these fuses can be reused multiple times, thus reducing costs.

[0026] In an advantageous design, the electronic control device is also used as the electronic signal device of the inverter. The electronic control device generates pulse-width modulated drive signals, which are then fed to driveable semiconductor switches arranged in parallel on a half-bridge, thus providing AC voltage to the motor at the inverter's AC voltage side interface. Advantageously, the electronic signal devices present on both sides of the inverter can be used to improve safety by employing different fuses.

[0027] An important feature of the present invention in the method for operating the equipment is that the motor operates as either a motor or a generator. In the case of motor operation, one or more contacts are opened based on the voltage detected at the interface on the DC voltage side of the inverter. In the case of generator operation, the motor current at the interface on the AC voltage side of the inverter is detected, and the value of the voltage present at the interface on the DC voltage side of the inverter at a future corresponding time point t+Δt relative to the current time point t plus a time interval Δt is determined, in particular, calculated in advance. Based on this voltage, one or more contacts are driven, in particular, closed.

[0028] The advantage here is that it can provide immediate security and protection from various safety devices.

[0029] In an advantageous design, the time period is equal to or exceeds the response time of the corresponding controllable contact. This is advantageous because it proactively ensures safety and provides an improved performance in line with the expected voltage.

[0030] In an advantageous design, when determining the expected voltage at time point t+Δt, the current voltage and capacity of the energy storage device, i.e., at time point t, are also considered. Advantageously, the current generated by the generator and the voltage at the DC voltage side interface of the inverter are detected, thereby determining the generator's power. Assuming this power remains constant until time point t+Δt, the future voltage can be calculated in advance, taking into account the energy storage device's capacity and the current voltage present at time point t, allowing for corresponding control of the contacts to ensure optimal safety.

[0031] Further advantages are provided by the dependent claims. The invention is not limited to the combination of features of the claims. For those skilled in the art, particularly for purposes proposed and / or by comparison with the prior art, other reasonable combinations of features of the claims and / or individual claims and / or description features and / or drawings are possible. Attached Figure Description

[0032] The invention will now be described in detail with reference to the schematic diagram:

[0033] Figure 1 The diagram shows a device according to the present invention, which has an energy storage 1 and a motor M that can be powered by an inverter 2;

[0034] Figure 2 The figure shows the characteristic curves showing the correlation between the trigger current and the duration of the trigger current. Detailed Implementation

[0035] like Figure 1 As shown, the energy storage device 1 has a voltage between 0 volts and a maximum value, such as 800 volts, depending on its charging state.

[0036] Preferably, the energy storage device is formed as a double-layer capacitor, especially a supercapacitor. Alternatively or additionally, the energy storage device has an electrochemically operating energy storage unit, especially a battery unit or battery cell.

[0037] Inverter 2, which supplies power to motor M, is powered by energy storage device 1.

[0038] The voltage V appearing at the interface on the DC voltage side of inverter 2 is detected, and the controllable contacts K1, especially contactors and especially relays, are driven according to the value of the detected voltage V.

[0039] With the help of contact K1, a second safety device F2, which is connected in series with the first safety device F1, can be connected.

[0040] The energy storage device 1 and two fuses (F1, F2) are connected in series, and the series circuit formed in this way supplies power to the DC voltage side interface of the inverter 2.

[0041] For maintenance purposes or during repair, accumulator 1 must be discharged to prevent any danger caused by accumulator 1.

[0042] Therefore, the first safety device F1 is designed such that the minimum trigger current of the first safety device is higher than that of the minimum trigger current of the second safety device F2, especially at least five times or at least twice as high.

[0043] For example, the minimum trigger current of the first fuse F1 is about 300 amperes, while the minimum trigger current of the second fuse F2 is about 50 amperes.

[0044] Within a first voltage range above a first threshold voltage V, contact K1 closes, thus providing protection only through the first safety device F1.

[0045] For example, the first threshold is 260 volts.

[0046] Within a second voltage range that is above the second threshold voltage V and below the first threshold voltage V, contact K1 opens and thus the second safety device F2 functions.

[0047] For example, the second threshold is 24 volts.

[0048] There is no dangerous voltage below the second threshold.

[0049] According to the invention, the voltage at the interface on the DC voltage side of the inverter 2 is detected and compared, in particular, with a first threshold voltage using a comparator included in the inverter 2. If a voltage lower than the first threshold voltage is present, the comparator generates a control signal that causes the first contact K1 to open.

[0050] Therefore, under these lower voltage conditions, although the smaller current caused by the internal resistance of the energy storage device 1 is lower than the minimum trigger current of the first fuse F1, the contact K1 is still opened under these lower voltage conditions below the first threshold, thereby making the second fuse F2 effective, and in the event of a fault, especially when a short circuit occurs on the inverter side, the minimum trigger current of the second fuse F2 can be easily reached.

[0051] The internal resistance of accumulator 1 is, for example, 120 milliohms.

[0052] like Figure 2 As shown, if the minimum trigger current persists, especially for more than two or ten minutes, the corresponding fuses (F1, F2) are triggered in the presence of the corresponding minimum trigger current. A faster trigger can be caused by a stronger current, respectively.

[0053] The safety device F1 is preferably designed as a semiconductor safety device, while the safety device F2 is designed as a full-range safety device.

[0054] The electronic control of inverter 2 is implemented such that no current is supplied to motor M when the current is below a first threshold and / or the first motor cannot generate torque when the current is below the first threshold. Furthermore, when the current is below the threshold, the voltage V applied to the DC voltage side only supplies power to the electronic instruments arranged in the switch cabinet including inverter 2, and to the electronic devices required for charging or discharging energy storage 2, especially the charger.

[0055] The contactor's control can be implemented using electronic control devices, which are arranged in the switch cabinet either separately from or integrated within the inverter 2. Preferably, the electronic control devices are also powered by a 24-volt supply. However, contact K1 is only de-energized and thus disconnected, i.e., in particular, opened, when a power supply failure occurs to the electronic control devices. In this way, a second fuse with a minimum trigger current is activated, and when the minimum trigger current of the fuse F2 is exceeded, the energy storage accumulator 2 is isolated or disconnected.

[0056] In another embodiment of the invention, a safety-related state identification is provided in contact K1 by providing an auxiliary contact, thereby preventing overload of the safety device F1 in the event of a fault. In this fault condition, the motor is shut off by the electronic control device.

[0057] Since the switching state of contact K1 is related to safety and can be reliably identified, fuse F2 can also be designed as a semiconductor fuse. Therefore, both fuses F1 and F2 can be designed as semiconductor fuses.

[0058] Therefore, the auxiliary contact on contact K1 is also advantageous because it can detect adhesion of contact K1, especially the contactor contact.

[0059] In another embodiment according to the invention, the series circuit not only has a first fuse F1 and a second fuse F2 connected in parallel with the first contact K1, but also a third or more fuses connected in parallel with corresponding additional contacts. Therefore, the corresponding contacts can be disconnected within their respective voltage ranges. Thus, within the respective voltage ranges, fuses are provided for the corresponding minimum trigger current. The control of these contacts is implemented by the electronic control devices of the inverter 2, or by separate electronic control devices arranged in the switch cabinet including the inverter.

[0060] Compared to the power electronics of inverter 2, the electronic control devices mentioned here are designed only as electronic signal devices and therefore only conduct harmless voltages, especially voltages below the second threshold.

[0061] List of reference numerals in the attached diagram:

[0062] 1. Accumulator

[0063] 2 Inverter

[0064] K1 can drive contacts, especially contactors.

[0065] F1 First Safety Device

[0066] F2 Second Safety Device

[0067] The voltage at the input terminal of the DC voltage side of inverter 2.

[0068] M motor

Claims

1. A device having an energy storage device and a motor that can be powered by an inverter, Its features are, The energy storage device forms a series circuit with the first safety device and one or more other safety devices. In this configuration, a controllable contact is connected in parallel with one of the other safety devices, or corresponding controllable contacts are connected in parallel with each of the multiple other safety devices. The series circuit supplies power to the DC voltage side interface of the inverter. The device for detecting the voltage applied to the series circuit is connected to an electronic control device, which generates a drive signal for the one driveable contact or for these corresponding driveable contacts. The device detects the voltage appearing at the interface on the DC voltage side of the inverter and drives the driveable contact according to the value of the detected voltage. The second fuse device connected in series with the first fuse device can be connected by means of the contact. Wherein, when the voltage is lower than the corresponding voltage threshold, the corresponding contact is disconnected, and the energy storage device has a double-layer capacitor or is designed to be a double-layer capacitor.

2. The device according to claim 1, Its features are, The electronic control device has a comparator that compares the voltage with one or more threshold values ​​and generates a corresponding drive signal associated with the comparison result for driving the one driveable contact or the corresponding driveable contact.

3. The device according to any one of the preceding claims, Its features are, The minimum trigger current of the first fuse is greater than the minimum trigger current of the other fuse connected in parallel with the one controllable contact. The minimum trigger current of the first safety device is greater than the minimum trigger current of the plurality of other safety devices connected in parallel with the corresponding controllable contacts.

4. The device according to claim 1 or 2, Its features are, The electronic control device is powered by a power supply voltage. When the power supply voltage fails, disconnect one or all of the corresponding driveable contacts.

5. The device according to claim 1 or 2, Its features are, The double-layer capacitor is designed as a supercapacitor.

6. The device according to claim 1 or 2, Its features are, The corresponding safety devices were designed as semiconductor safety devices.

7. The device according to claim 1 or 2, Its features are, The electronic control device is also used as an electronic signal device in the inverter, wherein the electronic control device generates a pulse-width modulated drive signal, which is sent to driveable semiconductor switches arranged in a half-bridge connected in parallel, and thus provides an AC voltage to power the motor at the AC voltage side interface of the inverter.

8. The device according to claim 3, characterized in that, The minimum trigger current of the first safety device is at least twice the minimum trigger current of the other safety device connected in parallel with the one controllable contact, and the minimum trigger current of the first safety device is at least twice the minimum trigger current of the plurality of other safety devices connected in parallel with the corresponding controllable contact.

9. A method for operating the device according to any one of the preceding claims, Its features are, The motor operates as either an electric motor or a generator. In the case of motor-driven operation, the one controllable contact or these corresponding controllable contacts are disconnected based on the voltage detected at the DC voltage side interface of the inverter. In the case of generator operation, the motor current at the interface on the AC voltage side of the inverter is detected, and the voltage value at the interface on the DC voltage side of the inverter at the corresponding future time point t+Δt based on each current time point t plus the time interval Δt is calculated in advance. The one controllable contact or these corresponding controllable contacts are driven according to the voltage determined in this way.

10. The method according to claim 9, Its features are, The time interval is equal to or exceeds the response time of the corresponding controllable contact.

11. The method according to claim 9 or 10, Its features are, When determining the expected voltage at time point t+Δt, the current voltage and capacity of the energy storage device, i.e., the voltage detected at time point t, are also taken into account.

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