Direct-current bus capacitor esr detection method and circuit, frequency converter and storage medium

Abstract

The application discloses a DC bus capacitor ESR detection method and circuit, a frequency converter and a storage medium, and belongs to the technical field of power electronics. When the rectifier bridge is in a non-working state, the application executes the following steps: controlling the inverter bridge to be in a preset first working state, so that the inverter bridge outputs a DC component of voltage, and collecting a DC bus voltage and a single-phase output current in real time; controlling the inverter bridge to be in a preset second working state, so that a motor inductance current continues to flow, and collecting the DC bus voltage in real time; and determining the DC bus capacitor ESR based on the DC bus voltage collected when the inverter bridge is in the preset first working state, the single-phase output current, and the DC bus voltage collected when the inverter bridge is in the preset second working state. The application aims to reduce the detection cost of the DC bus capacitor ESR.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, and particularly relates to a DC bus capacitor ESR detection method, circuit, frequency converter and storage medium. BACKGROUND

[0002] With the development of elevator industry for decades, the elevator has become an indispensable part of people's life and is also one of the important building equipment in the urbanization construction of modern society. In order to ensure the stable and rapid operation of the elevator, a frequency converter is arranged in the elevator. In the rectification filtering link of the frequency converter, the use frequency of the large-capacity aluminum electrolytic capacitor is relatively high, and the capacitor ESR (Equivalent Series Resistance) of the electrolytic capacitor will increase exponentially after long-time use, which causes the performance of the product to decrease. Therefore, the capacitor ESR of the electrolytic capacitor needs to be detected, and a warning needs to be given when the capacitor ESR is abnormal, so that the electrolytic capacitor can be replaced when the elevator is maintained, and the elevator is prevented from stopping.

[0003] However, since the DC bus capacitor ESR is parasitic in the capacitor, the existing DC bus capacitor ESR detection method usually damages the structure of the frequency converter, resulting in high detection cost. SUMMARY

[0004] Therefore, the present application provides a DC bus capacitor ESR detection method, circuit, frequency converter and storage medium, which aims to reduce the detection cost of the DC bus capacitor ESR.

[0005] The present application provides a DC bus capacitor ESR detection method, which comprises the following steps:

[0006] When the rectification bridge is in a non-working state, the following step is performed:

[0007] The inverter bridge is controlled to be in a preset first working state, so that the inverter bridge outputs a DC component of voltage, and the DC bus voltage and the single-phase output current are collected in real time;

[0008] The inverter bridge is controlled to be in a preset second working state, so that the motor inductance current continues to flow, and the DC bus voltage is collected in real time;

[0009] Based on the DC bus voltage collected when the inverter bridge is in the preset first working state and the single-phase output current, and the DC bus voltage collected when the inverter bridge is in the preset second working state, the DC bus capacitor ESR is determined.

[0010] Optionally, the DC bus capacitor ESR detection method further comprises:

[0011] Detecting the three-phase input voltage input to the rectifier bridge;

[0012] If the three-phase input voltage is in a decreasing state, it is determined that the rectifier bridge is in a non-operating state.

[0013] Optionally, the preset first working state includes at least one of the following:

[0014] The upper bridge arm of the U phase of the inverter bridge is turned on, and the lower bridge arm is turned off; the upper bridge arm of the V phase of the inverter bridge is turned off, and the lower bridge arm is turned on; the upper bridge arm of the W phase of the inverter bridge is turned off, and the lower bridge arm is turned on;

[0015] And / or, the upper bridge arm of the V phase of the inverter bridge is turned on, and the lower bridge arm is turned off; the upper bridge arm of the U phase of the inverter bridge is turned off, and the lower bridge arm is turned on; the upper bridge arm of the W phase of the inverter bridge is turned off, and the lower bridge arm is turned on;

[0016] And / or, the W-phase upper arm of the inverter bridge is turned on and the lower arm is turned off; the U-phase upper arm of the inverter bridge is turned off and the lower arm is turned on; the V-phase upper arm of the inverter bridge is turned off and the lower arm is turned on.

[0017] Optionally, the preset second working state is opposite to the preset first working state, and the preset second working state includes at least one of the following:

[0018] The lower bridge arm of the U phase of the inverter bridge is turned on, and the upper bridge arm is turned off; the lower bridge arm of the V phase of the inverter bridge is turned off, and the upper bridge arm is turned on; the lower bridge arm of the W phase of the inverter bridge is turned off, and the upper bridge arm is turned on;

[0019] And / or, the V-phase lower bridge arm of the inverter bridge is turned on, and the upper bridge arm is turned off; the U-phase lower bridge arm of the inverter bridge is turned off, and the upper bridge arm is turned on; the W-phase lower bridge arm of the inverter bridge is turned off, and the upper bridge arm is turned on;

[0020] And / or, the W-phase lower bridge arm of the inverter bridge is turned on and the upper bridge arm is turned off; the U-phase lower bridge arm of the inverter bridge is turned off and the upper bridge arm is turned on; the V-phase lower bridge arm of the inverter bridge is turned off and the upper bridge arm is turned on.

[0021] Optionally, the preset second working state includes:

[0022] The U-phase lower bridge arm and the upper bridge arm of the inverter bridge are both turned off; the V-phase lower bridge arm and the upper bridge arm of the inverter bridge are both turned off; the W-phase lower bridge arm and the upper bridge arm of the inverter bridge are both turned off.

[0023] Optionally, the step of determining the ESR of the DC bus capacitor based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in a preset first working state, and the DC bus voltage collected when the inverter bridge is in a preset second working state includes:

[0024] The DC bus capacitor ESR is calculated based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in a preset first working state, and the DC bus voltage collected when the inverter bridge is in a preset second working state, according to a preset DC bus capacitor ESR formula;

[0025] The preset DC bus capacitor ESR formula is:

[0026]

[0027] Among them, the R ESR Characterize the ESR of DC bus capacitor, V dc2 The DC bus voltage V dc1 The DC bus voltage I represents the DC bus voltage collected when the inverter bridge is in the preset first working state. dc Characterizes the single-phase output current.

[0028] The present application also provides a DC bus capacitor ESR detection circuit, comprising a first driving unit, a sampling unit and a control unit; wherein,

[0029] The first driving unit is used to control the inverter bridge to be in a preset first working state when the rectifier bridge is in an inoperative state, so that the inverter bridge outputs a DC component of the voltage; and to control the inverter bridge to be in a preset second working state so that the motor inductance current continues to flow; the sampling unit is used to send the collected DC bus voltage and single-phase output current when the inverter bridge is in the preset first working state, and the DC bus voltage when the inverter bridge is in the preset second working state to the control unit; the control unit is used to determine the DC bus capacitor ESR based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in the preset first working state, and the DC bus voltage collected when the inverter bridge is in the preset second working state.

[0030] Optionally, the sampling unit is also used to collect the three-phase input voltage input to the rectifier bridge and send it to the control unit; the control unit is also used to detect the three-phase input voltage input to the rectifier bridge. If the three-phase input voltage is in a decreasing state, it is determined that the rectifier bridge is in a non-working state.

[0031] The present application also provides a frequency converter, comprising:

[0032] The DC bus capacitor ESR detection circuit as described above;

[0033] A processing chip, wherein the processing chip executes the DC bus capacitor ESR detection method as described above.

[0034] The present application also provides a storage medium having a computer program stored thereon. When the computer program is executed by a processor, the DC bus capacitor ESR detection method as described above is implemented.

[0035] The present application discloses a method, circuit, inverter and storage medium for detecting the ESR of a DC bus capacitor. Compared with the prior art, in which the ESR detection method of the DC bus capacitor usually destroys the structure of the inverter, resulting in excessively high detection costs, the present application performs the following steps when the rectifier bridge is in an inoperative state: controlling the inverter bridge to be in a preset first operating state so that the inverter bridge outputs a DC component of the voltage, and collects the DC bus voltage and the single-phase output current in real time; controlling the inverter bridge to be in a preset second operating state so that the motor inductance current continues to flow, and collects the DC bus voltage in real time; and determining the ESR of the DC bus capacitor based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in the preset first operating state, and the DC bus voltage collected when the inverter bridge is in the preset second operating state. Therefore, when the rectifier bridge is in the non-working state, the present application accurately calculates the ESR of the DC bus capacitor through the DC bus voltage and single-phase output current when the inverter bridge outputs the DC component of the voltage, as well as the DC bus voltage when the motor inductance current is continuing, thereby realizing non-invasive detection of the DC bus capacitor of the inverter and reducing the detection cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0038] Figure 1 This is a flow chart of the first embodiment of the DC bus capacitor ESR detection method of the present application;

[0039] Figure 2 This is a schematic diagram of the circuit structure of the frequency converter of this application;

[0040] Figure 3 This is a structural diagram of the first embodiment of the DC bus capacitor ESR detection circuit of the present application.

[0041] Description of Figure Numbers:

[0042] Reference Name Reference Name 100 First drive unit 200 Sampling unit 300 Control unit

[0043] The objectives, functional features and advantages of the present application will be further illustrated in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0044] It should be understood that the specific embodiments described herein are merely illustrative of the present application and do not limit the present application.

[0045] The embodiment of the present application provides a DC bus capacitor ESR detection method. Referring to Figure 1 , Figure 1 The figure is a flowchart of the first embodiment of the DC bus capacitor ESR detection method of the present application.

[0046] In the embodiment, the DC bus capacitor ESR detection method comprises the following steps:

[0047] When the rectifier bridge is in a non-working state, the step of:

[0048] Step S10, control the inverter bridge in a preset first working state, so that the inverter bridge outputs a DC component of voltage, and real-time acquisition of DC bus voltage and single-phase output current;

[0049] Step S20, control the inverter bridge in a preset second working state, so that the motor inductance current continues to flow, and real-time acquisition of DC bus voltage;

[0050] Step S30, based on the DC bus voltage acquired when the inverter bridge is in the preset first working state and the single-phase output current, the DC bus voltage acquired when the inverter bridge is in the preset second working state, determine the DC bus capacitor ESR.

[0051] Compared with the prior art, the DC bus capacitor ESR detection method usually destroys the structure of the frequency converter, and after completing the detection of the DC bus capacitor ESR of the frequency converter, the frequency converter needs to be repaired, resulting in high detection cost. In the embodiment, when the rectifier bridge is in a non-working state, the DC bus voltage and the single-phase output current when the inverter bridge outputs a DC component of voltage, and the DC bus current when the motor inductance current continues to flow, are used to accurately calculate the DC bus capacitor ESR, improve the detection accuracy of the DC bus capacitor ESR, and realize non-invasive detection of the DC bus capacitor of the frequency converter, thereby reducing the detection cost.

[0052] The specific steps are as follows:

[0053] Step S10, when the rectifier bridge is in a non-working state, control the inverter bridge in a preset first working state, so that the inverter bridge outputs a DC component of voltage, and real-time acquisition of DC bus voltage and single-phase output current.

[0054] It should be noted that the DC bus capacitor ESR detection method of the embodiment is applied to the frequency converter, and the DC bus capacitor ESR in the frequency converter can be detected. The frequency converter can be a frequency converter used in any device provided with a motor. For example, the device provided with a motor includes but is not limited to an elevator, an air conditioner, a motor train unit, an electric vehicle, and a solar power generation device. Referring to Figure 2 , Figure 2 FIG. 1 is a schematic circuit structure diagram of a frequency converter.

[0055] It should be noted that the implementation premise of the DC bus capacitor ESR detection method of the embodiment is that the rectifier bridge of the frequency converter is in a non-working state. When the rectifier bridge is in a non-working state, it can be considered that the DC bus current I dc is equal to the value of the capacitor current I c .

[0056] Therefore, in the DC bus capacitor ESR detection method of the embodiment, the following steps are further included:

[0057] detecting a three-phase input voltage input to the rectifier bridge;

[0058] If the three-phase input voltage is in a falling state, it is determined that the rectifier bridge is in a non-working state.

[0059] On the contrary, if the three-phase input voltage is in a rising state, it is determined that the rectifier bridge is in a working state.

[0060] It should be noted that by detecting the three-phase input voltage input to the rectifier bridge, it is ensured that the detection of the DC bus capacitor ESR is performed when the rectifier bridge is in a non-working state.

[0061] As an example, when the inverter bridge is in a preset first working state: the U-phase upper bridge arm of the inverter bridge is turned on, and the lower bridge arm is turned off; the V-phase upper bridge arm of the inverter bridge is turned off, and the lower bridge arm is turned on; the W-phase upper bridge arm of the inverter bridge is turned off, and the lower bridge arm is turned on. When the inverter bridge is in the above working state (preset first working state), the DC bus current is the U-phase output current, and in the equivalent circuit model of the capacitor, the DC bus voltage is equal to the difference between the capacitor voltage and the voltage of the equivalent series resistance (ESR), that is:

[0062] V dc1 = V c -I dc ×R ESR ;

[0063] wherein V dc1 represents the DC bus voltage collected when the inverter bridge is in the preset first working state, I dc represents the DC bus current (U-phase output current), and RESR Characterizes the ESR of the DC bus capacitor.

[0064] As an example, when the inverter bridge is in the preset first working state: the upper bridge arm of the V phase of the inverter bridge is turned on, and the lower bridge arm is turned off; the upper bridge arm of the U phase of the inverter bridge is turned off, and the lower bridge arm is turned on; the upper bridge arm of the W phase of the inverter bridge is turned off, and the lower bridge arm is turned on. When the inverter bridge is in the above working state (the preset first working state), the DC bus current is the V phase output current, and in the capacitor equivalent circuit model, the DC bus voltage is equal to the difference between the capacitor voltage and the equivalent series resistance (ESR) voltage, that is:

[0065] V dc1 =V c -I dc ×R ESR ;

[0066] Among them, V dc1 Characterizes the DC bus voltage collected when the inverter bridge is in the preset first working state, I dc Characterizes the DC bus current (V phase output current), R ESR Characterizes the ESR of the DC bus capacitor.

[0067] As an example, when the inverter bridge is in the preset first working state: the upper bridge arm of the W phase of the inverter bridge is turned on, and the lower bridge arm is turned off; the upper bridge arm of the U phase of the inverter bridge is turned off, and the lower bridge arm is turned on; the upper bridge arm of the V phase of the inverter bridge is turned off, and the lower bridge arm is turned on. When the inverter bridge is in the above working state (the preset first working state), the DC bus current is the W phase output current, and in the capacitor equivalent circuit model, the DC bus voltage is equal to the difference between the capacitor voltage and the equivalent series resistance (ESR) voltage, that is:

[0068] V dc1 =V c -I dc ×R ESR ;

[0069] Among them, V dc1 Characterizes the DC bus voltage collected when the inverter bridge is in the preset first working state, I dc Characterizes the DC bus current (W phase output current), R ESR Characterizes the ESR of the DC bus capacitor.

[0070] Step S20: Control the inverter bridge to be in a preset second working state to allow the motor inductance current to continue to flow and collect the DC bus voltage in real time.

[0071] As an example, there are two situations for the preset second working state: in one, all bridge arms in the inverter bridge are in the off state, that is, the U-phase lower bridge arm and the upper bridge arm of the inverter bridge are both off; the V-phase lower bridge arm and the upper bridge arm of the inverter bridge are both off; the W-phase lower bridge arm and the upper bridge arm of the inverter bridge are both off; the other, the preset second working state is opposite to the preset first working state.

[0072] When the preset second working state is opposite to the preset first working state:

[0073] If the preset first working state is: the upper bridge arm of the U phase of the inverter bridge is turned on and the lower bridge arm is turned off; the upper bridge arm of the V phase of the inverter bridge is turned off and the lower bridge arm is turned on; the upper bridge arm of the W phase of the inverter bridge is turned off and the lower bridge arm is turned on; then the preset second working state is: the lower bridge arm of the U phase of the inverter bridge is turned on and the upper bridge arm is turned off; the lower bridge arm of the V phase of the inverter bridge is turned off and the upper bridge arm is turned on; the lower bridge arm of the W phase of the inverter bridge is turned off and the upper bridge arm is turned on;

[0074] If the preset first working state is: the upper bridge arm of the V phase of the inverter bridge is turned on and the lower bridge arm is turned off; the upper bridge arm of the U phase of the inverter bridge is turned off and the lower bridge arm is turned on; the upper bridge arm of the W phase of the inverter bridge is turned off and the lower bridge arm is turned on; then the preset second working state is: the lower bridge arm of the V phase of the inverter bridge is turned on and the upper bridge arm is turned off; the lower bridge arm of the U phase of the inverter bridge is turned off and the upper bridge arm is turned on; the lower bridge arm of the W phase of the inverter bridge is turned off and the upper bridge arm is turned on;

[0075] If the preset first working state is: the W-phase upper bridge arm of the inverter bridge is turned on, and the lower bridge arm is turned off; the U-phase upper bridge arm of the inverter bridge is turned off, and the lower bridge arm is turned on; the V-phase upper bridge arm of the inverter bridge is turned off, and the lower bridge arm is turned on; then the preset second working state is: the W-phase lower bridge arm of the inverter bridge is turned on, and the upper bridge arm is turned off; the U-phase lower bridge arm of the inverter bridge is turned off, and the upper bridge arm is turned on; the V-phase lower bridge arm of the inverter bridge is turned off, and the upper bridge arm is turned on.

[0076] When the inverter bridge is in the above-mentioned working state (the second working state), the output current of the inverter bridge is based on the freewheeling of the motor inductance. Since the motor inductance current cannot change suddenly, the DC bus current when the inverter bridge is in the preset second working state is the same as the DC bus current when the inverter bridge is in the preset first working state. In the capacitor equivalent circuit model, the DC bus voltage is equal to the sum of the capacitor voltage and the voltage of the equivalent series resistance (ESR), that is:

[0077] V dc2 =V c +I dc ×R ESR ;

[0078] Among them, V dc2 Characterizes the DC bus voltage collected when the inverter bridge is in the preset second working state, I dcCharacterizes the DC bus current (the same as the DC bus current when the inverter bridge is in the preset first working state), R ESR Characterizes the ESR of the DC bus capacitor.

[0079] As an example, the conduction and shutdown of each phase arm in the inverter bridge are controlled by the drive circuit in the inverter. The drive circuit can generate a pulse drive signal for the switch tube on each phase arm in the inverter bridge. The switch tube on each phase arm in the inverter bridge can be turned on or off according to its corresponding pulse drive signal.

[0080] Step S30: Determine the DC bus capacitor ESR based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in a preset first working state, and the DC bus voltage collected when the inverter bridge is in a preset second working state.

[0081] As an example, the DC bus capacitor ESR is calculated according to a preset DC bus capacitor ESR formula based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in a preset first working state, and the DC bus voltage collected when the inverter bridge is in a preset second working state;

[0082] The preset DC bus capacitor ESR formula is:

[0083]

[0084] Among them, R ESR Characterize the DC bus capacitor ESR, V dc2 Characterizes the DC bus voltage collected when the inverter bridge is in the preset second working state, V dc1 Characterizes the DC bus voltage collected when the inverter bridge is in the preset first working state, I dc Represents the single-phase output current.

[0085] Among them, the preset DC bus capacitor ESR formula is based on the formula V dc1 =V c -I dc ×R ESR And Formula V dc2 =V c +I dc ×R ESR Obtained by joint.

[0086] It should be noted that I dc The characterized single-phase output current is one of the U-phase output current, the V-phase output current and the W-phase output current, which is associated with the preset first working state of the inverter bridge. The specific association relationship can be found in the examples in step S10 and will not be repeated here.

[0087] The present application also provides a DC bus capacitor ESR detection circuit, referring to Figure 3 , Figure 3 This is a structural diagram of the first embodiment of the DC bus capacitor ESR detection circuit of the present application.

[0088] In this embodiment, the DC bus capacitor ESR detection circuit includes a first driving unit 100, a sampling unit 200 and a control unit 300; wherein,

[0089] The first driving unit 100 is configured to control the inverter bridge to be in a preset first working state when the rectifier bridge is in an off-state, so that the inverter bridge outputs a DC component of the voltage; and to control the inverter bridge to be in a preset second working state so that the motor inductor current continues to flow. The sampling unit 200 is configured to send the collected DC bus voltage and single-phase output current when the inverter bridge is in the preset first working state, and the DC bus voltage when the inverter bridge is in the preset second working state, to the control unit 300. The control unit 300 is configured to determine the ESR of the DC bus capacitor based on the DC bus voltage and single-phase output current collected when the inverter bridge is in the preset first working state, and the DC bus voltage collected when the inverter bridge is in the preset second working state. The sampling unit 200 is further configured to collect the three-phase input voltage input to the rectifier bridge and send it to the control unit 300. The control unit 300 is further configured to detect the three-phase input voltage input to the rectifier bridge, and determine that the rectifier bridge is in an off-state if the three-phase input voltage is in a decreasing state.

[0090] As an example, the first drive unit 100 can be a drive circuit built into the inverter, which can generate a pulse drive signal for the switch tube on each phase bridge arm in the inverter bridge, and the switch tube on each phase bridge arm in the inverter bridge is turned on or off according to its corresponding pulse drive signal. The sampling unit 200 can be a voltage detection circuit and a current detection circuit built into the inverter; wherein the voltage detection circuit is used to collect the DC bus voltage when the inverter bridge is in a preset first working state and the DC bus voltage when the inverter bridge is in a preset second working state; the current detection circuit is used to collect the single-phase output current when the inverter bridge is in the preset first working state. The control unit 300 can be an MCU (microcontroller unit) built into the inverter.

[0091] It should be noted that the first drive unit 100, sampling unit 200 and control unit 300 in the detection circuit for detecting the ESR of the DC bus capacitor in this embodiment can be the drive circuit, voltage detection circuit, current detection circuit and MCU in the inverter, thereby reducing the detection cost of the ESR of the DC bus capacitor and realizing non-invasive detection of the DC bus capacitor of the inverter at the same time.

[0092] In this embodiment, the process of measuring the ESR of the DC bus capacitor of the inverter using the above-mentioned DC bus capacitor ESR detection circuit is as follows:

[0093] The sampling unit 200 collects the three-phase input voltage input to the rectifier bridge and sends it to the control unit 300;

[0094] The control unit 300 detects the three-phase input voltage input to the rectifier bridge. If the three-phase input voltage is in a decreasing state, it is determined that the rectifier bridge is in an inoperative state; if the three-phase input voltage is in an increasing state, it is determined that the rectifier bridge is in an operative state.

[0095] When the rectifier bridge is in an inoperative state, the first driving unit 100 controls the inverter bridge to be in a preset first operating state so that the inverter bridge outputs a DC component of the voltage. The sampling unit 200 collects the DC bus voltage and the single-phase output current in real time and sends them to the control unit 300.

[0096] After collecting the DC bus voltage and single-phase output current when the inverter bridge is in a preset first working state, the first drive unit 100 controls the inverter bridge to be in a preset second working state to allow the motor inductance current to continue flowing. The sampling unit 200 collects the DC bus voltage in real time and sends it to the control unit 300.

[0097] The DC bus capacitor ESR is calculated based on the DC bus voltage and single-phase output current collected when the inverter bridge is in a preset first working state, and the DC bus voltage collected when the inverter bridge is in a preset second working state, according to a preset DC bus capacitor ESR formula;

[0098] Among them, the preset DC bus capacitor ESR formula is:

[0099]

[0100] Among them, R ESR Characterize the DC bus capacitor ESR, V dc2 Characterizes the DC bus voltage collected when the inverter bridge is in the preset second working state, V dc1 Characterizes the DC bus voltage collected when the inverter bridge is in the preset first working state, I dc Represents the single-phase output current.

[0101] The preset first working state includes at least one of the following:

[0102] The upper bridge arm of the U phase of the inverter bridge is turned on, and the lower bridge arm is turned off; the upper bridge arm of the V phase of the inverter bridge is turned off, and the lower bridge arm is turned on; the upper bridge arm of the W phase of the inverter bridge is turned off, and the lower bridge arm is turned on;

[0103] And / or, the upper bridge arm of the V phase of the inverter bridge is turned on, and the lower bridge arm is turned off; the upper bridge arm of the U phase of the inverter bridge is turned off, and the lower bridge arm is turned on; the upper bridge arm of the W phase of the inverter bridge is turned off, and the lower bridge arm is turned on;

[0104] And / or, the W-phase upper arm of the inverter bridge is turned on and the lower arm is turned off; the U-phase upper arm of the inverter bridge is turned off and the lower arm is turned on; the V-phase upper arm of the inverter bridge is turned off and the lower arm is turned on.

[0105] When the preset second working state is opposite to the preset first working state, the preset second working state includes at least one of the following:

[0106] The lower bridge arm of the U phase of the inverter bridge is turned on, and the upper bridge arm is turned off; the lower bridge arm of the V phase of the inverter bridge is turned off, and the upper bridge arm is turned on; the lower bridge arm of the W phase of the inverter bridge is turned off, and the upper bridge arm is turned on;

[0107] And / or, the V-phase lower bridge arm of the inverter bridge is turned on, and the upper bridge arm is turned off; the U-phase lower bridge arm of the inverter bridge is turned off, and the upper bridge arm is turned on; the W-phase lower bridge arm of the inverter bridge is turned off, and the upper bridge arm is turned on;

[0108] And / or, the W-phase lower bridge arm of the inverter bridge is turned on and the upper bridge arm is turned off; the U-phase lower bridge arm of the inverter bridge is turned off and the upper bridge arm is turned on; the V-phase lower bridge arm of the inverter bridge is turned off and the upper bridge arm is turned on.

[0109] The preset second working state can also be:

[0110] The U-phase lower bridge arm and the upper bridge arm of the inverter bridge are both turned off; the V-phase lower bridge arm and the upper bridge arm of the inverter bridge are both turned off; the W-phase lower bridge arm and the upper bridge arm of the inverter bridge are both turned off.

[0111] Compared with the prior art, in which the DC bus capacitor ESR detection method usually destroys the structure of the inverter and the inverter needs to be repaired after the detection of the DC bus capacitor ESR of the inverter is completed, resulting in excessively high detection costs, this embodiment accurately calculates the DC bus capacitor ESR by using the DC bus voltage and single-phase output current when the inverter bridge outputs the DC component of the voltage, as well as the DC bus voltage when the motor inductance current is freewheeling, when the rectifier bridge is in an inoperative state. This improves the detection accuracy of the DC bus capacitor ESR and realizes non-invasive detection of the inverter DC bus capacitor, thereby reducing the detection cost.

[0112] The present application also provides a frequency converter, including:

[0113] The DC bus capacitor ESR detection circuit as described above;

[0114] A processing chip, wherein the processing chip executes the DC bus capacitor ESR detection method as described above.

[0115] The implementation principle and beneficial effects of the DC bus capacitor ESR detection method executed by the processing chip of the inverter shown in the embodiment of the present application can be specifically referred to the implementation principle and beneficial effects of the DC bus capacitor ESR detection method shown in any of the above embodiments, and will not be repeated here.

[0116] An embodiment of the present application further provides a storage medium having a computer program stored thereon. When the computer program is executed by a processor, the DC bus capacitor ESR detection method as described above is implemented.

[0117] The specific implementation of the storage medium of the present application is basically the same as the embodiments of the above-mentioned DC bus capacitor ESR detection method, and will not be repeated here.

[0118] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or system. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or system comprising the element.

[0119] The serial numbers of the above embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0120] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0121] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for detecting ESR of a DC bus capacitor, characterized in that: The DC bus capacitor ESR detection method comprises the following steps: When the rectifier bridge is not working, perform the following steps: Controlling the inverter bridge to be in a preset first working state so that the inverter bridge outputs a DC component of the voltage and real-timely collects the DC bus voltage and the single-phase output current; Controlling the inverter bridge to be in a preset second working state to allow the motor inductance current to continue to flow and to collect the DC bus voltage in real time; The DC bus capacitor ESR is determined based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in a preset first working state, and the DC bus voltage collected when the inverter bridge is in a preset second working state.

2. The method for detecting the ESR of a DC bus capacitor according to claim 1, wherein: The DC bus capacitor ESR detection method further includes: Detecting the three-phase input voltage input to the rectifier bridge; If the three-phase input voltage is in a decreasing state, it is determined that the rectifier bridge is in a non-operating state.

3. The method for detecting ESR of a DC bus capacitor according to claim 1 or 2, wherein: The preset first working state includes at least one of the following: The upper bridge arm of the U phase of the inverter bridge is turned on, and the lower bridge arm is turned off; the upper bridge arm of the V phase of the inverter bridge is turned off, and the lower bridge arm is turned on; the upper bridge arm of the W phase of the inverter bridge is turned off, and the lower bridge arm is turned on; And / or, the upper bridge arm of the V phase of the inverter bridge is turned on, and the lower bridge arm is turned off; the upper bridge arm of the U phase of the inverter bridge is turned off, and the lower bridge arm is turned on; the upper bridge arm of the W phase of the inverter bridge is turned off, and the lower bridge arm is turned on; And / or, the W-phase upper arm of the inverter bridge is turned on and the lower arm is turned off; the U-phase upper arm of the inverter bridge is turned off and the lower arm is turned on; the V-phase upper arm of the inverter bridge is turned off and the lower arm is turned on.

4. The method for detecting ESR of a DC bus capacitor according to claim 3, wherein: The preset second working state is opposite to the preset first working state, and the preset second working state includes at least one of the following: The lower bridge arm of the U phase of the inverter bridge is turned on, and the upper bridge arm is turned off; the lower bridge arm of the V phase of the inverter bridge is turned off, and the upper bridge arm is turned on; the lower bridge arm of the W phase of the inverter bridge is turned off, and the upper bridge arm is turned on; And / or, the V-phase lower bridge arm of the inverter bridge is turned on, and the upper bridge arm is turned off; the U-phase lower bridge arm of the inverter bridge is turned off, and the upper bridge arm is turned on; the W-phase lower bridge arm of the inverter bridge is turned off, and the upper bridge arm is turned on; And / or, the W-phase lower bridge arm of the inverter bridge is turned on and the upper bridge arm is turned off; the U-phase lower bridge arm of the inverter bridge is turned off and the upper bridge arm is turned on; the V-phase lower bridge arm of the inverter bridge is turned off and the upper bridge arm is turned on.

5. The method for detecting ESR of a DC bus capacitor according to claim 1, wherein: The preset second working state includes: The U-phase lower bridge arm and the upper bridge arm of the inverter bridge are both turned off; the V-phase lower bridge arm and the upper bridge arm of the inverter bridge are both turned off; the W-phase lower bridge arm and the upper bridge arm of the inverter bridge are both turned off.

6. The method for detecting ESR of a DC bus capacitor according to claim 1, wherein: The step of determining the ESR of the DC bus capacitor based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in a preset first working state, and the DC bus voltage collected when the inverter bridge is in a preset second working state, includes: The DC bus capacitor ESR is calculated based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in a preset first working state, and the DC bus voltage collected when the inverter bridge is in a preset second working state, according to a preset DC bus capacitor ESR formula; The preset DC bus capacitor ESR formula is: Among them, the R ESR Characterize the DC bus capacitor ESR, V dc2 The DC bus voltage V dc1 The DC bus voltage I represents the DC bus voltage collected when the inverter bridge is in the preset first working state. dc Characterizes the single-phase output current.

7. A DC bus capacitor ESR detection circuit, characterized in that: It includes a first driving unit, a sampling unit and a control unit; wherein, The first driving unit is used to control the inverter bridge to be in a preset first working state when the rectifier bridge is in an inoperative state, so that the inverter bridge outputs a DC component of the voltage; and to control the inverter bridge to be in a preset second working state so that the motor inductance current continues to flow; the sampling unit is used to send the collected DC bus voltage and single-phase output current when the inverter bridge is in the preset first working state, and the DC bus voltage when the inverter bridge is in the preset second working state to the control unit; the control unit is used to determine the DC bus capacitor ESR based on the DC bus voltage and the single-phase output current collected when the inverter bridge is in the preset first working state, and the DC bus voltage collected when the inverter bridge is in the preset second working state.

8. The DC bus capacitor ESR detection circuit according to claim 7, wherein: The sampling unit is also used to collect the three-phase input voltage of the rectifier bridge and send it to the control unit; the control unit is also used to detect the three-phase input voltage of the rectifier bridge. If the three-phase input voltage is in a decreasing state, it is determined that the rectifier bridge is in a non-working state.

9. A frequency converter, characterized in that: include: The DC bus capacitor ESR detection circuit according to any one of claims 7 to 8; A processing chip, wherein the processing chip executes the DC bus capacitor ESR detection method according to any one of claims 1 to 6.

10. A storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by the processor, the method for detecting the ESR of a DC bus capacitor according to any one of claims 1 to 6 is implemented.

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