An elevator frequency converter and a protection circuit thereof

Abstract

The embodiment of the application discloses an elevator frequency converter and a protection circuit thereof. The elevator frequency converter comprises an inverter bridge, a rectifier bridge, a pre-charge resistor connected to a bus between the inverter bridge and the rectifier bridge, and a plurality of relays connected in parallel with the pre-charge resistor. The protection circuit comprises: a sampling circuit configured to collect a current of at least one of the plurality of relay branches and generate a sampling voltage according to the current; a voltage detection unit configured to output a first level when the sampling voltage meets a preset condition; and an MCU configured to control the power devices in the relays and the inverter bridge to be turned off when the first level is received. Through the embodiment, the power devices and the pre-charge relays are protected.

Description

Technical Field

[0001] This application relates to elevator control technology, and more particularly to an elevator frequency converter and its protection circuit. Background Technology

[0002] The current main topology diagram of elevator frequency converters in the industry is as follows: Figure 1 As shown, after the capacitor is fully charged at the moment of power-on, the relay 4 connected in parallel with the pre-charge resistor is closed, and then the inverter works normally.

[0003] However, the current inverter topology has the following problems:

[0004] 1. As the power of the frequency converter increases, the current flowing through the bus also increases. Therefore, multiple relays 4 need to be connected in parallel to shunt the current, such as... Figure 1 As shown. In this method, when one relay 4 breaks due to wear, the current flowing through other relays 4 exceeds the rated value, which in turn causes other relays that were not damaged to fail in succession.

[0005] 2. When an IGBT (Insulated Gate Bipolar Transistor) experiences a shoot-through short circuit, the protection mechanism fails to activate, resulting in IGBT losses. Summary of the Invention

[0006] This application provides an elevator frequency converter and its protection circuit, which can protect power devices and pre-charge relays.

[0007] This application provides a protection circuit for an elevator frequency converter. The elevator frequency converter may include: an inverter bridge, a rectifier bridge, a pre-charging resistor connected to the busbar between the inverter bridge and the rectifier bridge, and multiple relay branches connected in parallel with the pre-charging resistor. The protection circuit may include:

[0008] The sampling circuit can be configured to collect the current of at least one of the multiple relay branches and generate a sampling voltage based on the current.

[0009] The voltage detection unit can be configured to output a first level when it detects that the sampled voltage meets preset conditions;

[0010] The MCU can be configured to control the relay and the power devices in the inverter bridge to turn off when it receives the first voltage level.

[0011] In one embodiment, the sampling circuit acquiring the current of at least one of the plurality of relay branches may include:

[0012] The sampling circuit is connected in series in at least one of the multiple relay branches.

[0013] In one embodiment, the voltage detection unit may include a first voltage sampling terminal and a second voltage sampling terminal;

[0014] The first voltage sampling terminal can be connected to the first terminal of the sampling circuit, and the second voltage sampling terminal can be connected to the second terminal of the sampling circuit for acquiring the sampling voltage.

[0015] In one embodiment, the MCU controlling the power devices of the relay and the inverter bridge to turn off may include:

[0016] Stop supplying drive signals to the relay and the power device.

[0017] In one embodiment, the preset condition may include: the sampled voltage is less than or equal to a preset first voltage threshold.

[0018] In one embodiment, the preset condition may include: the sampled voltage is greater than or equal to a preset second voltage threshold.

[0019] In one embodiment, the sampling circuit may include at least one Hall sensor.

[0020] In one embodiment, the power device may include an IGBT.

[0021] In one embodiment, the sampling circuit may include at least one sampling resistor; a first end of the sampling resistor may be connected to any contact of one of the plurality of relays, and a second end may be connected to the busbar.

[0022] This application also provides an elevator frequency converter, which may include the aforementioned protection circuit.

[0023] Compared with related technologies, the embodiments of this application may include: the elevator frequency converter may include an inverter bridge, a rectifier bridge, a pre-charging resistor connected on a bus between the inverter bridge and the rectifier bridge, and multiple relay branches connected in parallel with the pre-charging resistor; the protection circuit may include: a sampling circuit configured to be connected in series with the relays, acquiring the current of at least one of the multiple relay branches, and generating a sampling voltage based on the current; a voltage detection unit configured to detect whether the sampling voltage meets a preset condition, and output a first level when the sampling voltage meets the preset condition; and an MCU configured to control the relays and power devices in the inverter bridge to turn off when the first level is received. Through this embodiment, protection of the power devices and the pre-charging relays is achieved.

[0024] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the solutions described in the description and the accompanying drawings. Attached Figure Description

[0025] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0026] Figure 1 This is a schematic diagram of the topology of an elevator frequency converter in related technologies;

[0027] Figure 2 This is a schematic diagram of the elevator inverter topology according to an embodiment of this application;

[0028] Figure 3 This is a block diagram of the elevator frequency converter in an embodiment of this application. Detailed Implementation

[0029] This application describes several embodiments, but these descriptions are exemplary and not restrictive, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0030] This application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive scheme as defined by the claims. Any feature or element of any embodiment may also be combined with features or elements from other inventive schemes to form another unique inventive scheme as defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this application may be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes may be made within the scope of the appended claims.

[0031] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to the steps performed in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0032] This application provides a protection circuit for an elevator frequency converter, such as... Figure 2 As shown, the elevator frequency converter may include: a rectifier bridge 1, an inverter bridge 2, a pre-charging resistor 3 connected to the busbar between the inverter bridge 2 and the rectifier bridge 1, and multiple relay branches 4 connected in parallel with the pre-charging resistor 3. The protection circuit may include:

[0033] The sampling circuit 5 can be configured to collect the current of at least one of the multiple relay branches 4 and generate a sampling voltage based on the current.

[0034] The voltage detection unit 6 can be configured to output a first level (e.g., a high voltage) when it detects that the sampled voltage meets the preset conditions.

[0035] The MCU can be configured to control the relay and the power devices G (e.g., G1, G2, G3, G4, G5, G6) in the inverter bridge 2 to turn off when it receives the first level.

[0036] In one embodiment, the plurality of relays may include relays RY1, RY2, ..., RYn connected in parallel.

[0037] In one embodiment, the sampling circuit acquiring the current of at least one of the plurality of relay branches may include:

[0038] The sampling circuit can be connected in series with at least one of the multiple relay branches.

[0039] In one embodiment, the sampling circuit 5 may be connected in series with at least one relay branch 4. In one embodiment, to save costs, only one sampling circuit 5 may be connected in series with one relay branch 4. If cost is not a concern, one sampling circuit 5 may be connected in series with multiple relay branches 4 respectively, or a sampling circuit 5 may be connected in series with each relay branch 4.

[0040] In one embodiment, after a sampling circuit 5 is connected in series on any one or more relay branches 4, the sampling voltage of the sampling circuit 5 is converted and sent to the MCU. When a relay is damaged and disconnected or a power device (e.g., including but not limited to IGBT) is short-circuited, the sampling voltage will change, so that the sampling voltage meets certain preset conditions. When the sampling voltage meets the preset conditions, the MCU can cut off the control signals of the relay and the power device to avoid further damage to the device and play a protective role.

[0041] In one embodiment, the voltage detection unit may include a first voltage sampling terminal and a second voltage sampling terminal;

[0042] The first voltage sampling terminal can be connected to the first terminal of the sampling circuit, and the second voltage sampling terminal can be connected to the second terminal of the sampling circuit for acquiring the sampling voltage.

[0043] In one embodiment, the preset condition may include: the sampling voltage is less than or equal to a preset first voltage threshold, for example, the sampling voltage may be 0.

[0044] In one embodiment, when the relay in the relay branch 4 where the sampling circuit 5 is located is damaged, the current in the branch where the sampling circuit is located will become 0 or become a very small current value. The corresponding sampling voltage will also change to 0 or a very small voltage value (less than or equal to the first voltage threshold). When the MCU detects that the sampling voltage is 0 or a very small voltage value, it can determine that the relay is damaged. Then it can disconnect the power device and the relay, thereby avoiding the relays that were not damaged before from becoming damaged and failing, and avoiding the loss of power device.

[0045] In one embodiment, the preset conditions may include: the sampled voltage is greater than or equal to a preset second voltage threshold; the second voltage threshold is greater than a first voltage threshold.

[0046] In one embodiment, the case of a sampling circuit 5 connected in series only on one relay branch 4 is used as an example: when the relay 4 on the non-sampling circuit relay branch 4 is damaged or the power device is short-circuited, the current on the relay branch 4 where the sampling circuit 5 is located increases, which in turn causes the voltage on the sampling circuit 5 to increase and exceed the second voltage threshold set by the MCU. At this time, the MCU can cut off the power device and the relay, thereby avoiding damage and failure of the relay that was not damaged, and avoiding further loss of one or more power devices.

[0047] In one embodiment, when multiple relay branches 4 are connected in series with sampling circuits 5, for example, the first sampling circuit is connected in series with the first relay branch, the second sampling circuit is connected in series with the second relay branch, the third sampling circuit is connected in series with the third relay branch, and so on, if the relay in the first relay branch is damaged, the current in the second relay branch, the third relay branch, and so on will all increase. At this time, the sampling voltage corresponding to the first sampling circuit and the sampling voltage corresponding to the second sampling circuit will both increase. When the MCU detects that the sampling voltage has increased to exceed the voltage threshold, it can disconnect the relay and the power device to achieve device protection.

[0048] In one embodiment, the voltage threshold can be set according to different application scenarios and the number of relays connected in succession; the specific value of the voltage threshold is not limited here.

[0049] In one embodiment, the MCU controlling the power devices of the relay and the inverter bridge to turn off may include:

[0050] Stop supplying drive signals to the relay and stop supplying drive signals to the power device.

[0051] In one embodiment, the sampling circuit may be implemented using a Hall sensor or a sampling resistor.

[0052] In one embodiment, at least one of the multiple relay branches 4 is provided with a Hall sensor, which may be surrounding the busbar.

[0053] In one embodiment, the sampling resistor and Hall sensor are readily available, the circuit structure is simple, and the solution is easy to implement.

[0054] This application also provides an elevator frequency converter A, which may include the aforementioned protection circuit B.

[0055] In one embodiment, any of the aforementioned protection circuit embodiments can be applied to this elevator inverter embodiment, and will not be described in detail here.

[0056] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

Claims

1. A protection circuit for an elevator frequency converter, the elevator frequency converter comprising: The system comprises a rectifier bridge, an inverter bridge, a pre-charging resistor connected to a busbar between the rectifier bridge and the inverter bridge, and a plurality of relay branches connected in parallel with the pre-charging resistor, characterized in that the protection circuit includes: The sampling circuit is configured to acquire the current of at least one of the multiple relay branches and generate a sampling voltage. The voltage detection unit is configured to output a first level when the sampled voltage is detected to meet a preset condition; The MCU is configured to control the power devices of the relay and the inverter bridge to turn off when it receives the first level. The preset conditions include: the sampled voltage is less than or equal to a preset first voltage threshold, or the preset conditions include: the sampled voltage is greater than or equal to a preset second voltage threshold, wherein the second voltage threshold is greater than the first voltage threshold.

2. The protection circuit for the elevator frequency converter according to claim 1, characterized in that, The sampling circuit acquires the current of at least one of the multiple relay branches, including: The sampling circuit is connected in series in at least one of the multiple relay branches.

3. The protection circuit for the elevator frequency converter according to claim 2, characterized in that, The voltage detection unit includes a first voltage sampling terminal and a second voltage sampling terminal; The first voltage sampling terminal is connected to the first terminal of the sampling circuit, and the second voltage sampling terminal is connected to the second terminal of the sampling circuit, for acquiring the sampling voltage.

4. The protection circuit for the elevator frequency converter according to claim 1, characterized in that, The MCU controls the power devices of the relay and the inverter bridge to turn off, including: Stop providing drive signals to the relay and the power device.

5. The protection circuit of the elevator frequency converter according to any one of claims 1-4, characterized in that, The power device includes: IGBT.

6. The protection circuit of the elevator frequency converter according to any one of claims 1-4, characterized in that, The sampling circuit includes at least one sampling resistor; the first end of the sampling resistor is connected to any contact of one of the plurality of relays, and the second end is connected to the busbar.

7. The protection circuit for the elevator frequency converter according to any one of claims 1-4, characterized in that, The sampling circuit includes at least one Hall sensor.

8. An elevator frequency converter, characterized in that, Includes the protection circuit described in any one of claims 1-7.

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