Brake circuit, brake control method, device and servo system

Abstract

The application discloses a braking circuit, a braking control method and device and a servo system. The braking circuit comprises an energy storage device and a power device, which are connected between a positive end of a DC bus and a negative end of the DC bus; a voltage detection module, a first end of which is connected to the positive end of the DC bus and a second end of which is connected to the negative end of the DC bus; and a control module, one end of which is connected to a third end of the voltage detection module and the other end of which is connected to the power device; wherein the control module outputs a voltage-adjustable driving signal to the power device so that the power device works in an active region. The application makes the power device work in the active region, acts as an adjustable resistor, does not need an external braking resistor, eliminates the installation space of the external resistor and a heat dissipation system, reduces the volume of a servo driver, lowers the cost, avoids a large-area loop formed by a long lead wire, reduces electromagnetic interference, and makes a small-power servo driver convenient for compact design.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a braking circuit, braking control method, device and servo system. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in industrial automation, CNC machine tools, and robotics due to their high power density, high efficiency, and excellent control performance. In servo systems, when the motor encounters a sudden load change, performs braking, or decelerates, it enters a generator state, converting mechanical energy into electrical energy and feeding it back to the servo drive. This feedback energy charges the DC bus capacitor of the servo drive, causing the DC bus voltage to rise rapidly. If the bus voltage is too high, it may damage the internal components of the servo drive, seriously affecting the safety and reliability of the servo system.

[0003] Currently, existing technologies mostly employ a combination of power devices and external braking resistors to handle feedback energy. Specifically, the braking circuit of a traditional servo drive typically includes a voltage detection circuit, an IGBT, a controller, and an external braking resistor. When the bus voltage rises to a preset voltage threshold, the controller sends a signal to turn on the IGBT, creating a braking circuit. The external braking resistor then converts electrical energy into heat energy for dissipation, thereby reducing the DC bus voltage. However, existing technologies have the following problems: First, external braking resistors often use leaded aluminum-cased resistors. These resistors are typically large, generate a lot of heat, and require independent installation locations and cooling ducts. This complicates the control cabinet structure, increases system size, and hinders the miniaturization and compact design of servo drives and their control cabinets. Furthermore, poor heat dissipation can lead to overheating and damage of the braking resistor, affecting system reliability. As low-power servo drives and their control cabinets become increasingly miniaturized and power density continues to increase, the size issue of external braking resistors becomes increasingly prominent. Second, external braking resistors and their associated cooling systems increase the system's material and assembly costs. Since the braking resistors need to be installed independently, wiring costs and installation time are also increased. Third, the connecting wires of leaded aluminum-cased resistors are usually long, forming a large current loop at the switching node. When the IGBT switches at high speed, this loop generates strong electromagnetic interference, affecting the system's electromagnetic compatibility performance and potentially interfering with surrounding electronic equipment.

[0004] Therefore, it can be seen that the braking scheme using an external braking resistor in the existing technology has problems such as large size, high cost, and serious electromagnetic interference, which makes it difficult to meet the problem of compact design of low-power servo drivers. Summary of the Invention

[0005] This invention provides a braking circuit, braking control method, device, and servo system, aiming to solve the problem that existing braking circuits, which require an external braking resistor, cannot meet the requirements for compact design of low-power servo drivers.

[0006] In a first aspect, embodiments of the present invention provide a braking circuit, comprising: The energy storage device and power device are both connected between the positive terminal and the negative terminal of the DC bus; the voltage detection module has its first terminal connected to the positive terminal of the DC bus and its second terminal connected to the negative terminal of the DC bus. The control module has one end connected to the third terminal of the voltage detection module and the other end connected to the power device; The control module outputs an adjustable voltage drive signal to the power device so that the power device operates in the active region.

[0007] Secondly, embodiments of the present invention also provide a braking control method, comprising: The estimated junction temperature of the insulated gate bipolar transistor is calculated based on the obtained DC bus voltage and the case temperature of the insulated gate bipolar transistor. The braking current threshold is determined based on the estimated junction temperature and the safe operating area curve of the insulated gate bipolar transistor. Obtain the target braking current, and determine the control current value based on the target braking current and the braking current threshold. The drive voltage is calculated based on the control current value, the DC bus voltage, and the estimated junction temperature. The driving voltage is output to the gate of the insulated gate bipolar transistor (IGBT) to make the IGBT operate in the active region and maintain the collector current of the IGBT equal to the control current value.

[0008] Thirdly, embodiments of the present invention also provide a braking control device, comprising: The first calculation unit is used to calculate the estimated junction temperature of the insulated gate bipolar transistor based on the acquired DC bus voltage and the case temperature of the insulated gate bipolar transistor. The first determining unit is used to determine the braking current threshold based on the estimated junction temperature and the safe operating area curve of the insulated gate bipolar transistor. The second determining unit acquires the target braking current and determines the control current value based on the target braking current and the braking current threshold. The second calculation unit is used to calculate the driving voltage based on the control current value, the DC bus voltage, and the junction temperature estimate. An output sustaining unit is used to output the driving voltage to the gate of the insulated gate bipolar transistor (IGBT) so that the IGBT operates in the active region and maintains the collector current of the IGBT equal to the control current value.

[0009] Fourthly, embodiments of the present invention also provide a servo system, comprising: A servo driver, comprising a three-phase inverter circuit and the braking circuit described in the first aspect above; The motor is connected to the three-phase inverter circuit and is used to receive the three-phase AC power output by the three-phase inverter circuit to achieve rotation.

[0010] This invention provides a braking circuit, braking control method, device, and servo system. The braking circuit includes: an energy storage device and a power device, both connected between the positive and negative terminals of a DC bus; a voltage detection module, with its first end connected to the positive terminal and its second end connected to the negative terminal of the DC bus; and a control module, with one end connected to the third end of the voltage detection module and the other end connected to the power device. The control module outputs an adjustable drive signal to the power device, causing it to operate in the active region. This invention's solution, by connecting both the power device and the energy storage device to the two ends of the DC bus, detecting the bus voltage with the voltage detection module, and outputting an adjustable drive signal to make the power device operate in the active region (acting as an adjustable resistor), eliminates the need for an external braking resistor, thus eliminating the installation space required for an external resistor and heat dissipation system, reducing the size of the servo driver, lowering costs, and avoiding large-area loops formed by long leads, reducing electromagnetic interference and facilitating compact design of low-power servo drivers. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 A schematic diagram of a servo system provided for the present technology; Figure 2 A circuit diagram of a braking circuit provided for an embodiment of the present invention; Figure 3 A schematic diagram of a servo driver provided for an embodiment of the present invention; Figure 4 A schematic diagram of a servo system provided in an embodiment of the present invention; Figure 5A schematic flowchart of a braking control method provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of a sub-process of a braking control method provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of another sub-process of a braking control method provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of another sub-process of a braking control method provided in an embodiment of the present invention; Figure 9 A schematic block diagram of a braking control device provided in an embodiment of the present invention; Figure 10 This is a schematic block diagram of a servo driver provided in an embodiment of the present invention. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0015] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0016] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0017] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0018] This invention proposes a braking circuit, braking control method, device, and servo system, solving the problem that existing braking circuits require external braking resistors, making it difficult to meet the compact design requirements of low-power servo drivers. In this embodiment, both the power device and the energy storage device are connected to both ends of the DC bus. The voltage detection module detects the bus voltage, and the control module outputs an adjustable drive signal to make the power device work in the active region, acting as an adjustable resistor. This eliminates the need for an external braking resistor, thus eliminating the installation space required for external resistors and heat dissipation systems, reducing the size of the servo driver, and lowering costs. At the same time, it avoids large-area loops formed by long leads, reducing electromagnetic interference and facilitating the compact design of low-power servo drivers.

[0019] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0020] Please see Figure 1 , Figure 1 A schematic diagram of a servo system provided for the prior art, such as Figure 1 As shown, the braking circuit in an existing servo driver includes a DC bus capacitor C. DC Voltage detection circuit, MCU (Micro Controller Unit), IGBT and external braking resistor R brake Among them, the IGBT (Insulated Gate Bipolar Transistor) is a composite power semiconductor device that combines the advantages of MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and BJT (Bipolar Junction Transistor). At the positive terminal V of the DC bus... BUS With DC bus negative terminal P GND The DC bus capacitor C is connected in parallel between them. DC Used to stabilize bus voltage V DC The voltage detection circuit consists of a first voltage divider resistor R1, a second voltage divider resistor R2, and a linear optocoupler. One end of R1 is connected to the positive terminal V of the DC bus. BUS The other end is connected to one end of R2, and the other end of R2 is connected to the negative terminal P of the DC bus. GNDThe connection point of R1 and R2 is connected to the input side of the linear optocoupler, and the output side of the linear optocoupler is connected to the MCU, which is used to isolate and transmit the bus voltage detection signal to the MCU.

[0021] It should be noted that the collector of the IGBT is connected to V. BUS The emitter passes through R brake Connect P GND The gate receives the PWM drive signal from the MCU. The servo driver includes a braking circuit and a three-phase inverter circuit. The servo system includes a servo driver and a permanent magnet synchronous motor (PMSM). The three-phase inverter circuit is connected to the positive terminal V. BUS With DC bus negative terminal P GND Between these, it is used to drive a permanent magnet synchronous motor.

[0022] It should also be noted that during operation, the regenerative current generated by the deceleration of the permanent magnet synchronous motor is directed to C. DC Charging causes V DC Rising. The voltage across the bus is detected by a voltage divider formed by R1 and R2, and transmitted to the MCU after linear optocoupler isolation. When V... DC When the voltage rises to the preset action threshold, the MCU sends a PWM drive signal to turn on the IGBT, thus establishing a braking circuit and allowing electrical energy to flow through R. brake It is converted into heat energy dissipation, making V DC The voltage drops to protect the internal components of the servo drive from overvoltage damage.

[0023] Please see Figure 2 , Figure 2 A circuit diagram of a braking circuit provided in an embodiment of the present invention, such as... Figure 2 As shown, the braking circuit includes an energy storage device and a power device, both of which are connected to the positive terminal V of the DC bus. BUS With DC bus negative terminal P GND Between; voltage detection module, the first end of which is connected to the positive terminal V of the DC bus. BUS The second end is connected to the negative terminal P of the DC bus. GND A control module is provided, with one end connected to the third terminal of the voltage detection module and the other end connected to the power device. The control module outputs an adjustable drive signal to the power device to enable it to operate in the active region. It should be noted that the energy storage device is a DC bus capacitor C. DC The power device is an IGBT (Insulated Gate Bipolar Transistor), meaning the gate of the IGBT is connected to the control module, and the emitter is connected to the negative terminal P of the DC bus. GND The collector is connected to the positive terminal V of the DC bus.BUS .

[0024] It should also be noted that the control module is an MCU, and the voltage detection module includes a first voltage divider resistor R1, a second voltage divider resistor R2, and a linear optocoupler, wherein one end of the first voltage divider resistor R1 is connected to the positive terminal V of the DC bus. BUS One end is connected to one end of the second voltage divider resistor R2, and the other end of the second voltage divider resistor R2 is connected to the negative terminal P of the DC bus. GND The linear optocoupler is connected at one end between the first voltage divider resistor R1 and the second voltage divider resistor R2, and at the other end to the control module.

[0025] Please see Figure 3 , Figure 3 A schematic diagram of a servo driver provided in an embodiment of the present invention is shown below. Figure 3 As shown, the servo driver includes a three-phase inverter circuit and the braking circuit described above. Please refer to [link / reference]. Figure 4 , Figure 4 A schematic diagram of a servo system provided in an embodiment of the present invention is shown below. Figure 4 As shown, the servo system includes a servo driver and a motor. The motor is a permanent magnet synchronous motor, which is connected to the three-phase inverter circuit to receive the three-phase AC power output by the three-phase inverter circuit to achieve rotation.

[0026] It should be noted that, in this embodiment, the positive terminal V of the DC bus... BUS With DC bus negative terminal P GND The DC bus capacitor C is connected in parallel between them. DC Used to stabilize bus voltage V DC R1 and R2 are connected in series across the DC bus. The connection point between R1 and R2 is on the input side of a linear optocoupler, and the output side of the linear optocoupler is connected to the MCU. This is used to isolate and transmit the bus voltage detection signal to the MCU. The collector of the IGBT is connected to VBUS, the emitter is connected to PGND, and the gate receives an adjustable drive signal from the MCU, for example, a drive voltage range of 3~9V. The three-phase inverter circuit is connected to the DC bus to drive the permanent magnet synchronous motor.

[0027] It should also be noted that during operation, the regenerative current generated by the deceleration of the permanent magnet synchronous motor is directed to C. DC Charging causes V DC Rise. The voltage detection circuit monitors the bus voltage in real time and transmits it to the MCU. When V DC When the voltage rises to the preset threshold, the MCU generates a drive signal of variable amplitude and outputs it to the IGBT gate, causing the IGBT to operate in the active region (linear region), which is equivalent to an adjustable resistor. At this time, the IGBT collector current is: Where k is a constant; α is a coefficient between 1 and 2; λ is the modulation coefficient; V GE V is the gate-emitter voltage of the IGBT. GE(th) This is the IGBT gate emitter threshold voltage.

[0028] IGBTs convert electrical energy into heat energy for dissipation, thus enabling V DC The braking circuit in this embodiment does not require an external braking resistor, but instead uses the IGBT itself as an adjustable resistor to dissipate energy. This reduces the size of the servo driver, lowers the cost, avoids electromagnetic interference caused by long leads, and facilitates the compact and efficient design of the servo driver and its control cabinet.

[0029] Please refer to Figure 5 , Figure 5 This is a flowchart illustrating a braking control method provided in an embodiment of the present invention, as shown below. Figure 5 As shown, the braking control method includes steps S110-S150.

[0030] S110. Calculate the estimated junction temperature of the insulated gate bipolar transistor based on the obtained DC bus voltage and the case temperature of the insulated gate bipolar transistor.

[0031] In this embodiment, as Figure 6 As shown, step S110 specifically includes steps S111-S113: S111, acquiring the DC bus voltage and the case temperature of the insulated gate bipolar transistor (IGBT); S112, if the DC bus voltage is not less than a preset voltage threshold, calculating the estimated junction temperature based on the case temperature and the power loss of the IGBT using heat transfer characteristics; S113, using a Kalman filter algorithm to weightedly fuse the case temperature and the estimated junction temperature to obtain the estimated junction temperature of the IGBT. It should be noted that the DC bus voltage is acquired through the first voltage divider resistor, the second voltage divider resistor, and the linear optocoupler of the voltage detection circuit, and the case temperature is measured by a temperature sensor attached to the IGBT's heat dissipation substrate.

[0032] It should also be noted that if the DC bus voltage is not less than a preset voltage threshold, i.e., when the DC bus voltage rises to the preset voltage threshold, the junction temperature estimation prediction process is triggered. The predicted junction temperature is calculated based on the case temperature and the power loss of the insulated-gate bipolar transistor using heat transfer characteristics. Specifically, based on the Foster thermal network model, the cumulative values ​​of the case temperature and power loss after processing with the thermal admittance function are added together to obtain the predicted junction temperature. , among which, T Ch(t) is the shell temperature at time t, and h(t) is the Foster thermal admittance function. P(τ) represents the residual heat contribution of the heat at time τ to the estimated junction temperature at time t after thermal diffusion over time (t-τ), and P(τ) is the power loss at time τ.

[0033] It should be further explained that the Kalman filter algorithm is used to weight and fuse the estimated case temperature and junction temperature to obtain the estimated junction temperature of the insulated-gate bipolar transistor. In the Kalman filter, the state equation is: The observation equation is ,in, Let be the instantaneous temperature difference between the two ends of the i-th RC element at time k. These are the Euler discretization coefficients. To control the gain coefficient, Let be the power loss at time k. Let K be the shell temperature at time k. To measure noise, This is a real-time estimated junction temperature value. The measured case temperature lags behind the actual estimated junction temperature but has no cumulative error, while the predicted junction temperature value has a fast response but has cumulative error. By dynamically adjusting the weights of the two inputs through Kalman gain, the cumulative prediction error and measurement noise are eliminated, resulting in an accurate real-time estimated junction temperature value.

[0034] It should be further explained that the RC unit is the basic building block of the Foster thermal network model. It describes the heat transfer process from the junction to the shell inside the IGBT by using multi-stage RC series, and is the core basis for junction temperature estimation and Kalman filter estimation.

[0035] S120. Determine the braking current threshold based on the estimated junction temperature and the safe operating area curve of the insulated gate bipolar transistor.

[0036] In this embodiment, as Figure 7As shown, step S120 specifically includes steps S121-S123: S121, determining a first current limit under thermal constraints based on the estimated junction temperature and the thermal admittance function of the insulated-gate bipolar transistor (IGBT); S122, determining a second current limit under electrical constraints based on the DC bus voltage and the safe operating area curve of the IGBT; S123, selecting the smaller value between the first and second current limits as the braking current threshold. It should be noted that, based on the Foster thermal network model, the allowable transient power loss under the current estimated junction temperature is calculated using the thermal admittance function to ensure that the peak value of the estimated transient junction temperature of the IGBT does not exceed the upper limit of the estimated junction temperature during braking. The power loss is determined by the braking current threshold and the voltage between the emitter and collector of the IGBT. The maximum allowable current, i.e., the first current limit, is derived from the thermal constraints. This limit dynamically changes with the estimated junction temperature; the higher the estimated junction temperature, the smaller the allowable maximum current, preventing device damage due to overheating.

[0037] It should also be noted that the safe operating area curve of the insulated gate bipolar transistor (IGBT) is provided by the device manufacturer, describing the maximum allowable current at different voltages. To ensure that the combination of current and voltage at the moment of turn-off falls within the safe operating area curve, secondary breakdown or permanent damage to the device is avoided. A second current limit is obtained by looking up a table based on the current DC bus voltage. The smaller of the first and second current limits is selected as the braking current threshold to ensure that both thermal and electrical safety constraints are met simultaneously, preventing device damage due to a single constraint.

[0038] S130. Obtain the target braking current, and determine the control current value based on the target braking current and the braking current threshold.

[0039] In this embodiment, the target braking current is obtained, which is dynamically calculated based on a comparison between the DC bus voltage and a set reference value. The smaller value between the target braking current and the braking current threshold is selected as the control current value. Specifically, the PI controller in the motor control loop monitors the DC bus voltage in real time and compares it with a set reference value, which is a preset voltage threshold. When the DC bus voltage exceeds the preset voltage threshold, the PI controller outputs a braking power command, and the target braking current is equal to the braking power command divided by the DC bus voltage. This current reflects the bus voltage control requirements, aiming to maintain the DC bus voltage below a safe value and ensure that the bus voltage remains stable within the set range during braking. The motor control loop is the core control system of the servo drive.

[0040] It should be noted that the smaller value between the target braking current and the braking current threshold is selected as the control current value. The braking current threshold is jointly determined by thermal constraints and electrical constraints. The minimum value between the target braking current and the braking current threshold is taken as the control current value to ensure that the triple constraints of thermal safety, electrical safety, and bus voltage control are met simultaneously, thereby achieving safe and reliable operation of the IGBT in the active region.

[0041] S140. Calculate the driving voltage based on the control current value, the DC bus voltage, and the estimated junction temperature value.

[0042] In this embodiment, as Figure 8 As shown, step S140 specifically includes steps S141-S144: S141, obtaining a preset three-dimensional data table, wherein the three-dimensional data table stores the gate-emitter voltage, collector-emitter voltage, and estimated junction temperature of the insulated-gate bipolar transistor; S142, determining multiple vertices surrounding the current operating point from the three-dimensional data table based on the estimated junction temperature and the DC bus voltage; S143, performing interpolation processing on the multiple vertices to obtain the corresponding curves of gate voltage and collector current under the current estimated junction temperature and the current DC bus voltage; S144, finding the gate voltage that matches the control current value from the corresponding curves, and using it as the driving voltage. It should be noted that the three-dimensional data table is established based on the IGBT transfer characteristic curve and is pre-stored in the control module. It should also be noted that eight vertices are found in three-dimensional space to surround the current operating point: two adjacent temperature points of the estimated junction temperature, two adjacent voltage points of the collector-emitter voltage, and two adjacent voltage points of the gate voltage, ensuring the accuracy of the interpolation calculation.

[0043] S150. The driving voltage is output to the gate of the insulated gate bipolar transistor (IGBT) so that the IGBT operates in the active region and the collector current of the IGBT is maintained equal to the control current value.

[0044] In this embodiment, a driving voltage is applied to the IGBT gate, causing the IGBT to operate in the linear amplification region. At this point, the IGBT is equivalent to an adjustable resistor, and its equivalent impedance dynamically adjusts with the gate voltage. When the collector current deviates from the control current value, the gate voltage amplitude is adjusted via feedback to change the IGBT's conduction level, causing the collector current to return to the control current value. Understandably, this design achieves continuous and controllable energy dissipation, eliminates the need for an external braking resistor, reduces the size of the servo driver and control cabinet, lowers electromagnetic interference, facilitates compact and efficient servo driver design, and ensures the IGBT operates within a safe range, preventing overheating damage.

[0045] For ease of understanding, the braking control process is explained in detail below: When a permanent magnet synchronous motor encounters a sudden load change or executes a deceleration command, the motor enters a generator state, converting mechanical energy into electrical energy and feeding it back to the servo driver. The regenerative current charges the DC bus capacitor, causing the DC bus voltage to rise rapidly.

[0046] The voltage detection circuit monitors the DC bus voltage in real time. When the DC bus voltage is not less than a preset voltage threshold, the active braking process is triggered. The control module acquires the case temperature of the insulated gate bipolar transistor (IGBT), calculates the predicted junction temperature based on the case temperature and power loss using heat transfer characteristics, and uses a Kalman filter algorithm to weightedly fuse the predicted case temperature and junction temperature to obtain the estimated junction temperature of the IGBT.

[0047] The first current limit under thermal constraints is determined based on the junction temperature and thermal admittance function, and the second current limit under electrical constraints is determined based on the DC bus voltage and the safe operating area curve. The smaller of the two values ​​is selected as the braking current threshold. Simultaneously, the motor control loop dynamically calculates the target braking current based on the comparison between the DC bus voltage and the set reference value, and selects the smaller of the target braking current and the braking current threshold as the control current value.

[0048] When changes in motor speed cause fluctuations in feedback energy, the control current value is dynamically adjusted accordingly. Based on the real-time junction temperature, DC bus voltage, and control current value, the control module determines the eight vertices surrounding the current operating point from the three-dimensional data table, performs interpolation processing to obtain the corresponding curve of gate voltage and collector current, and finds the gate voltage that matches the control current value as the drive voltage.

[0049] The drive voltage is output to the gate of the insulated-gate bipolar transistor (IGBT), causing the IGBT to operate in the active region. When the motor's feedback energy increases, the control current increases, the drive voltage rises accordingly, the equivalent impedance of the IGBT decreases, and the collector current increases. Conversely, when the feedback energy decreases, the drive voltage decreases, the equivalent impedance increases, and the collector current decreases. By dynamically adjusting the drive voltage amplitude, the collector current is maintained equal to the control current, achieving controllable energy dissipation and stabilizing the DC bus voltage within a safe range. This eliminates the need for an external braking resistor, reducing the size of the servo driver, lowering costs, and minimizing electromagnetic interference.

[0050] In summary, the braking control method in this embodiment eliminates the need for an external braking resistor by having the insulated-gate bipolar transistor (IGBT) operate in the active region as an adjustable resistor. This reduces the installation space required for external resistors and heat dissipation systems, decreases the size of the servo driver and control cabinet, and lowers material and wiring costs. By fusing predicted case and junction temperatures using a Kalman filter algorithm, accurate real-time junction temperature estimates are obtained. Combined with thermal and electrical constraints, the braking current threshold is determined, ensuring the IGBT operates within a safe operating range and preventing overheating damage. Furthermore, the driving voltage is calculated through three-dimensional data table interpolation, dynamically adjusting the equivalent impedance of the IGBT to maintain the collector current equal to the control current value. This achieves controllable energy dissipation, avoids large-area loops formed by long leads, reduces electromagnetic interference, and facilitates compact and efficient design of low-power servo drivers.

[0051] Figure 9 This is a schematic block diagram of a braking control device 200 provided in an embodiment of the present invention. Figure 9 As shown, corresponding to the above braking control method, the present invention also provides a braking control device 200. This braking control device 200 includes a unit for executing the above braking control method, and the device can be configured in the control module of the braking circuit. Specifically, please refer to... Figure 9 The braking control device 200 includes a first calculation unit 201, a first determination unit 202, a second determination unit 203, a second calculation unit 204, and an output maintenance unit 205. Detailed descriptions of each functional module are as follows: The first calculation unit 201 is used to calculate the estimated junction temperature of the insulated gate bipolar transistor based on the acquired DC bus voltage and the case temperature of the insulated gate bipolar transistor. The first determining unit 202 is used to determine the braking current threshold based on the estimated junction temperature and the safe operating area curve of the insulated gate bipolar transistor. The second determining unit 203 acquires the target braking current and determines the control current value based on the target braking current and the braking current threshold. The second calculation unit 204 is used to calculate the driving voltage based on the control current value, the DC bus voltage, and the junction temperature estimate. The output sustaining unit 205 is used to output the driving voltage to the gate of the insulated gate bipolar transistor (IGBT) so that the IGBT operates in the active region and maintains the collector current of the IGBT equal to the control current value.

[0052] In some embodiments, such as this one, the first computing unit 201 is specifically used for: Obtain the DC bus voltage and the case temperature of the insulated gate bipolar transistor; If the DC bus voltage is not less than the preset voltage threshold, the estimated junction temperature is calculated based on the case temperature and the power loss of the insulated gate bipolar transistor using the heat transfer characteristics. The Kalman filter algorithm is used to weight and fuse the estimated value of the case temperature and the predicted value of the junction temperature to obtain the estimated value of the junction temperature of the insulated gate bipolar transistor.

[0053] In some embodiments, such as this one, the first determining unit 202 is specifically used for: The first current limit under thermal constraint is determined based on the estimated junction temperature and the thermal admittance function of the insulated gate bipolar transistor. The second current limit under electrical constraints is determined based on the DC bus voltage and the safe operating area curve of the insulated gate bipolar transistor. The smaller value between the first current limit and the second current limit is selected as the braking current threshold.

[0054] In some embodiments, such as this embodiment, the second determining unit 203 is specifically used for: The target braking current is obtained, wherein the target braking current is dynamically calculated based on the comparison result between the DC bus voltage and a set reference value; The smaller value between the target braking current and the braking current threshold is selected as the control current value.

[0055] In some embodiments, such as this one, the second computing unit 204 is specifically used for: Obtain a preset three-dimensional data table, wherein the three-dimensional data table stores the gate-emitter voltage, collector-emitter voltage, and estimated junction temperature of the insulated gate bipolar transistor; Based on the estimated junction temperature and the DC bus voltage, determine multiple vertices surrounding the current operating point from the three-dimensional data table; Interpolation is performed on the multiple vertices to obtain the corresponding curves of gate voltage and collector current under the current estimated junction temperature and current DC bus voltage. The gate voltage that matches the control current value is found from the corresponding curve and used as the driving voltage.

[0056] The aforementioned braking control device can be implemented as a computer program, which can, for example... Figure 10 The control module in the braking circuit shown is running.

[0057] Please see Figure 10 , Figure 10This is a schematic block diagram of a servo driver provided in an embodiment of the present invention. The servo driver 300 is a device that can realize braking control without the need for an external braking resistor.

[0058] See Figure 10 The servo driver 300 includes a processor 302, a memory, and a network interface 305 connected via a system bus 301. The memory may include a non-volatile storage medium 303 and internal memory 304.

[0059] The non-volatile storage medium 303 can store an operating system 3031 and a computer program 3032. When the computer program 3032 is executed, it causes the processor 302 to execute a communication control method for a multi-connected system.

[0060] The processor 302 provides computing and control capabilities to support the operation of the entire servo drive 300.

[0061] The internal memory 304 provides an environment for the execution of the computer program 3032 in the non-volatile storage medium 303. When the computer program 3032 is executed by the processor 302, the processor 302 can execute a communication control method for a multi-connected system.

[0062] This network interface 305 is used for network communication with other devices. Those skilled in the art will understand that... Figure 10 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the servo driver 300 to which the present invention is applied. The specific servo driver 300 may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0063] The processor 302 is used to run a computer program 3032 stored in a memory to implement any embodiment of the communication control method of the multi-unit system described above.

[0064] It should be understood that, in this embodiment of the invention, the processor 302 may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0065] It will be understood by those skilled in the art that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a storage medium, which is a computer-readable storage medium. The computer program is executed by a processor in the computer system to implement the process steps of the embodiments of the above methods.

[0066] Therefore, the present invention also provides a storage medium. This storage medium can be a computer-readable storage medium. The storage medium stores a computer program. When executed by a processor, the computer program causes the processor to perform any embodiment of the communication control method for the multi-connector system described above.

[0067] The storage medium can be any computer-readable storage medium capable of storing program code, such as a USB flash drive, portable hard drive, read-only memory (ROM), magnetic disk, or optical disk.

[0068] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0069] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For example, the division of each unit is merely a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0070] The steps in the method of this invention can be adjusted, merged, or reduced in order according to actual needs. The units in the device of this invention can be merged, divided, or reduced according to actual needs. Furthermore, the functional units in the various embodiments of this invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0071] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a servo driver to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0072] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0073] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Since these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations.

[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A braking circuit, characterized in that, include: The energy storage device and power device are both connected between the positive terminal and the negative terminal of the DC bus; the voltage detection module has its first terminal connected to the positive terminal of the DC bus and its second terminal connected to the negative terminal of the DC bus. The control module has one end connected to the third terminal of the voltage detection module and the other end connected to the power device; The control module outputs an adjustable voltage drive signal to the power device so that the power device operates in the active region.

2. The braking circuit according to claim 1, characterized in that, The power device is an insulated-gate bipolar transistor (IGBT). The gate of the IGBT is connected to the control module, the emitter is connected to the negative terminal of the DC bus, and the collector is connected to the positive terminal of the DC bus.

3. The braking circuit according to claim 1, characterized in that, The voltage detection module includes a first voltage divider resistor, a second voltage divider resistor, and a linear optocoupler. One end of the first voltage divider resistor is connected to the positive terminal of the DC bus, and the other end is connected to one end of the second voltage divider resistor. The other end of the second voltage divider resistor is connected to the negative terminal of the DC bus. One end of the linear optocoupler is connected between the first voltage divider resistor and the second voltage divider resistor, and the other end is connected to the control module.

4. A braking control method, applied to a control module in a braking circuit as described in any one of claims 1-3, characterized in that, The method includes: The estimated junction temperature of the insulated gate bipolar transistor is calculated based on the obtained DC bus voltage and the case temperature of the insulated gate bipolar transistor. The braking current threshold is determined based on the estimated junction temperature and the safe operating area curve of the insulated gate bipolar transistor. Obtain the target braking current, and determine the control current value based on the target braking current and the braking current threshold. The drive voltage is calculated based on the control current value, the DC bus voltage, and the estimated junction temperature. The driving voltage is output to the gate of the insulated gate bipolar transistor (IGBT) to make the IGBT operate in the active region and maintain the collector current of the IGBT equal to the control current value.

5. The method according to claim 4, characterized in that, The step of calculating the estimated junction temperature of the insulated gate bipolar transistor (IGBT) based on the acquired DC bus voltage and the case temperature of the IGBT includes: Obtain the DC bus voltage and the case temperature of the insulated gate bipolar transistor; If the DC bus voltage is not less than the preset voltage threshold, the estimated junction temperature is calculated based on the case temperature and the power loss of the insulated gate bipolar transistor using the heat transfer characteristics. The Kalman filter algorithm is used to weight and fuse the estimated value of the case temperature and the predicted value of the junction temperature to obtain the estimated value of the junction temperature of the insulated gate bipolar transistor.

6. The method according to claim 4, characterized in that, The step of determining the braking current threshold based on the estimated junction temperature and the safe operating area curve of the insulated gate bipolar transistor includes: The first current limit under thermal constraint is determined based on the estimated junction temperature and the thermal admittance function of the insulated gate bipolar transistor. The second current limit under electrical constraints is determined based on the DC bus voltage and the safe operating area curve of the insulated gate bipolar transistor. The smaller value between the first current limit and the second current limit is selected as the braking current threshold.

7. The method according to claim 4, characterized in that, The step of acquiring the target braking current and determining the control current value based on the target braking current and the braking current threshold includes: The target braking current is obtained, wherein the target braking current is dynamically calculated based on the comparison result between the DC bus voltage and a set reference value; The smaller value between the target braking current and the braking current threshold is selected as the control current value.

8. The method according to claim 4, characterized in that, The step of calculating the drive voltage based on the control current value, the DC bus voltage, and the estimated junction temperature includes: Obtain a preset three-dimensional data table, wherein the three-dimensional data table stores the gate-emitter voltage, collector-emitter voltage, and estimated junction temperature of the insulated gate bipolar transistor; Based on the estimated junction temperature and the DC bus voltage, determine multiple vertices surrounding the current operating point from the three-dimensional data table; Interpolation is performed on the multiple vertices to obtain the corresponding curves of gate voltage and collector current under the current estimated junction temperature and current DC bus voltage. The gate voltage that matches the control current value is found from the corresponding curve and used as the driving voltage.

9. A braking control device, characterized in that, include: The first calculation unit is used to calculate the estimated junction temperature of the insulated gate bipolar transistor based on the acquired DC bus voltage and the case temperature of the insulated gate bipolar transistor. The first determining unit is used to determine the braking current threshold based on the estimated junction temperature and the safe operating area curve of the insulated gate bipolar transistor. The second determining unit acquires the target braking current and determines the control current value based on the target braking current and the braking current threshold. The second calculation unit is used to calculate the driving voltage based on the control current value, the DC bus voltage, and the junction temperature estimate. An output sustaining unit is used to output the driving voltage to the gate of the insulated gate bipolar transistor (IGBT) so that the IGBT operates in the active region and maintains the collector current of the IGBT equal to the control current value.

10. A servo system, characterized in that, include: A servo driver, comprising a three-phase inverter circuit and a braking circuit as described in any one of claims 1 to 3; The motor is connected to the three-phase inverter circuit and is used to receive the three-phase AC power output by the three-phase inverter circuit to achieve rotation.

Images