High-voltage servo driver discharge device based on high-resistance isolation sampling

Abstract

The invention discloses a high-voltage servo driver discharge device based on high-resistance isolation sampling, and the discharge device employs a high-resistance isolation bus sampling design, a bus high voltage is scaled down into a sampling voltage, and the sampling voltage is compared with a discharge threshold voltage through a comparator after conditioning. And the output of the comparator controls the grid voltage of the SiC MOS tube through the isolation driving circuit, so that the on-off of the bleeder resistor connected between the bus voltage and the ground is controlled, and the purpose of discharging when the bus voltage exceeds a threshold value is achieved. The device can protect the high-voltage servo driver from instantaneous high-voltage impact of bus fluctuation, back electromotive force and the like, and normal work of the servo driver is maintained.

Description

Technical Field

[0001] This invention belongs to the field of servo drive technology for motors, and in particular, it is a high-voltage servo driver discharge device based on high-impedance isolation sampling. Background Technology

[0002] Servo systems, as one of the most important control and execution mechanisms in industrial automation, have been widely used in machine tools, textile machinery, printing machinery, and packaging machinery. Meanwhile, with the rapid expansion of industries such as industrial robots and new energy vehicles in recent years, the application scale of servo systems has grown rapidly, and the overall market size has significant growth potential. Servo drivers, as an important component of servo systems, have always been a research focus for scholars both domestically and internationally.

[0003] During the operation of a servo drive motor, the instantaneous and rapid increase in bus voltage occurs during start-up and stop, as well as changes in load (especially sudden changes). If this is not addressed or controlled, the instantaneous voltage stress will directly affect the servo drive, shortening its lifespan or even causing damage and system failure. Therefore, controlling the bus voltage, especially ensuring it does not exceed the servo drive's rated value, is a crucial area for ensuring the normal operation of the servo system.

[0004] The common solution on the market is to use a bleeder circuit to absorb overvoltage surges on the bus. The principle is that when overvoltage occurs, the bleeder circuit is activated, dissipating excess energy through the bleeder resistor. However, most bleeder circuit solutions on the market treat the bleeder switch control and power section as a shared ground, resulting in a non-isolated design. Noise and interference from the power section can be transmitted to the bleeder switch control circuit. When the power section voltage is high, interference that is small in the power section becomes unacceptable to the bleeder switch control circuit, affecting its stability. Furthermore, the high-voltage switching transistor is usually an IGBT, which has a relatively low switching frequency, increasing the risk of slow bleeder response and potential burnout of the main circuit. Summary of the Invention

[0005] The purpose of this invention is to address the problems of interference introduced when the power voltage is high and the slow high-voltage discharge response speed, and to provide a high-voltage servo driver discharge implementation scheme that isolates power-end interference and speeds up the discharge response speed at the slave device end.

[0006] The technical solution to achieve the purpose of this invention is as follows: a high-voltage servo driver discharge device based on high-impedance isolation sampling. The discharge device adopts a high-impedance isolation bus sampling design, which reduces the bus high voltage to a sampling voltage proportionally. After conditioning, it is compared with the discharge threshold voltage by a comparator. The comparator output controls the gate voltage of the SiC MOS transistor through an isolation drive circuit, thereby controlling the on / off state of the discharge resistor connecting the bus voltage and ground, so as to achieve the purpose of discharge when the bus voltage exceeds the threshold.

[0007] Furthermore, the discharge device includes a discharge device control circuit and an isolation drive circuit. The discharge device control circuit includes an isolation power supply module, a bus sampling unit, a voltage conditioning unit, a threshold voltage comparison unit, and a discharge power unit.

[0008] The isolated power supply module is used to convert the control power input into 12V and 5V control power and 12V, 5V and -3.2V drive power, so as to provide stable power to the discharge device control circuit and the isolated drive circuit respectively.

[0009] The bus sampling unit is used to proportionally reduce the bus high voltage to a sampling voltage through high-impedance isolation.

[0010] The voltage conditioning unit is used to condition the sampled voltage to obtain a stable bus conditioning voltage;

[0011] The threshold voltage comparison unit is used to compare the bus conditioning voltage with a customizable threshold voltage, and drive the switch signal to turn on through the isolation drive circuit, thereby controlling the conduction or shutdown of the discharge power unit.

[0012] When the power discharge unit is turned on, it discharges excess power, thereby maintaining the bus conditioning voltage at the threshold voltage level.

[0013] Furthermore, the input and output of the isolated power supply module are not grounded together.

[0014] Furthermore, the voltage range of the control power supply input is 9V to 36V.

[0015] Furthermore, the bus sampling unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, and an operational amplifier. The first and third resistors have the same resistance value, both being high-value resistors on the order of tens of MΩ, and are composed of multiple resistors on the order of MΩ connected in series. The second and fourth resistors have the same resistance value, both on the order of hundreds of KΩ. The negative input terminal of the operational amplifier is grounded through the first resistor and connected to the output terminal of the operational amplifier through the second resistor. The positive input terminal of the operational amplifier is connected to the bus voltage VP+ through the third resistor and grounded through the fourth resistor. The operational amplifier outputs a sampling voltage VS+.

[0016] Furthermore, the voltage conditioning unit conditions the sampled voltage, including isolation amplification and differential amplification.

[0017] Furthermore, the power discharge unit includes a power discharge resistor and a SiC MOS transistor. The power discharge resistor is connected between the bus voltage VP+ and the SiC MOS transistor. The isolation drive circuit turns the SiC MOS transistor on or off to enable or disable the power discharge path.

[0018] Furthermore, the threshold voltage can be adjusted within a range of 50V to 780V.

[0019] Furthermore, the device also includes a grounded housing with a printed circuit board inside, where the discharge device control circuit and the isolation drive circuit are centrally located; the SiC MOS transistor is attached to the bottom of the housing using thermal grease.

[0020] Furthermore, the housing has interfaces for external control power supply, busbar, chassis ground and bleed resistor, as well as a knob position for adjusting the threshold voltage.

[0021] Compared with the prior art, the present invention has the following significant advantages:

[0022] (1) By using an isolated power supply module, the power input within a voltage range can be converted into a fixed value control and drive power output. The power output is isolated from the input and not grounded. The interference of the output power supply and subsequent stages will not affect the quality of the input power supply and other isolated power supplies.

[0023] (2) The bus sampling adopts a high-impedance isolation voltage divider sampling method, and the impedance between the bus and the ground is designed to be on the order of 10 MΩ to reduce the current flow.

[0024] (3) By using SiC MOS transistors as power switching transistors, the response speed of the discharge switch is improved, the heat loss on the transistor is reduced, and the discharge power and efficiency are increased.

[0025] (4) This invention can be used in high voltage servo drives and discharge control. It has strong anti-interference ability, fast discharge response speed and high safety.

[0026] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a block diagram illustrating the principle of a high-voltage servo driver discharge device based on high-impedance isolation sampling in one embodiment.

[0028] Figure 2 This is a flowchart illustrating the implementation of the venting device in one embodiment.

[0029] Figure 3 This is a schematic diagram of the bus sampling circuit in one embodiment.

[0030] Figure 4 This is a schematic diagram of the discharge device structure in one embodiment, wherein... Figure 4 (a) in the diagram is a schematic of the external interface. Figure 4 (b) in the figure is a sectional view. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0033] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0034] In one embodiment, combined Figure 1 This invention provides a high-voltage servo driver discharge device based on high-impedance isolation sampling. The discharge device adopts a high-impedance isolation bus sampling design, which proportionally reduces the bus high voltage to a sampling voltage. After conditioning, it is compared with the discharge threshold voltage by a comparator. The comparator output controls the gate voltage of the SiC MOS transistor through an isolation drive circuit, thereby controlling the on / off state of the discharge resistor connecting the bus voltage and ground, so as to achieve the purpose of discharge when the bus voltage exceeds the threshold.

[0035] Furthermore, in one embodiment, the discharge device includes a discharge device control circuit and an isolation drive circuit. The discharge device control circuit includes an isolation power supply module, a bus sampling unit, a voltage conditioning unit, a threshold voltage comparison unit, and a discharge power unit.

[0036] The isolated power supply module is used to convert the control power input into 12V and 5V control power and 12V, 5V and -3.2V drive power, so as to provide stable power to the discharge device control circuit and the isolated drive circuit respectively.

[0037] The bus sampling unit is used to proportionally reduce the bus high voltage to a sampling voltage through high-impedance isolation.

[0038] The voltage conditioning unit is used to condition the sampled voltage to obtain a stable bus conditioning voltage; here, conditioning includes, but is not limited to, isolation amplification and differential amplification.

[0039] The threshold voltage comparison unit is used to compare the bus conditioning voltage with a customizable threshold voltage, and drive the switch signal to turn on through the isolation drive circuit, thereby controlling the conduction or shutdown of the discharge power unit.

[0040] Here, the threshold voltage is achieved through any threshold voltage adjustment circuit, including but not limited to a sliding rheostat.

[0041] When the power discharge unit is turned on, it discharges excess power, thereby maintaining the bus conditioning voltage at the threshold voltage level.

[0042] Preferably, in some embodiments, the control power supply output ground GND, the drive power supply output ground VN, and the power input ground LGND are isolated from each other, so that drive and high-power interference will not affect the quality of the input power supply and the control power supply.

[0043] Here, the purpose of isolated power supply is to prevent interference during the operation of the power supply from affecting the stability of the control power supply input through the common ground, and to ensure the relative stability of the control circuit of the discharge device.

[0044] Here, the voltage range of the control power supply input is 9V to 36V. A preferred voltage is 24V.

[0045] Preferably, in some embodiments, combined with Figure 3 The bus sampling unit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and an operational amplifier. The first resistor R1 and the third resistor R3 have the same resistance value, both being high-value resistors on the order of tens of MΩ, and are composed of multiple resistors on the order of MΩ connected in series. The second resistor R2 and the fourth resistor R4 have the same resistance value, both on the order of hundreds of KΩ. The negative input terminal of the operational amplifier is grounded through the first resistor R1 and connected to the output terminal of the operational amplifier through the second resistor R2. The positive input terminal of the operational amplifier is connected to the bus voltage VP+ through the third resistor R3 and grounded through the fourth resistor R4. The operational amplifier outputs a sampling voltage VS+.

[0046] Here, the bus sampling circuit employs a high-impedance isolation sampling method. The impedance between the bus (power input VP) and PGND (a single-point connection between PGND and drive power ground VN) is designed to be on the order of tens of MΩ, achieving high-impedance isolation between the power supply and the drive power supply. The bus sampling voltage is then output through a proportional voltage divider circuit. The entire bus sampling circuit reduces interference caused by current in the sampling circuit section.

[0047] Here, R1 and R3 are high-resistance resistors on the order of tens of megaohms, implemented by multiple resistors on the order of megaohms connected in series, to ensure that the voltage across each resistor is not too high when the bus voltage VP+ is very large. R3 and R4 are resistors on the order of hundreds of kΩ, used for voltage division of VP+ and operational amplifier feedback. At this time, the sampling voltage VS+ output by the operational amplifier will be one-hundredth of VP+.

[0048] Preferably, in some embodiments, the power discharge unit includes a power discharge resistor and a SiC MOS transistor. The power discharge resistor is connected between the bus voltage VP+ and the SiC MOS transistor. The isolation drive circuit turns the SiC MOS transistor on or off to enable or disable the power discharge path.

[0049] Specifically, in combination Figure 2 When the bus conditioning voltage is greater than the threshold voltage, the threshold voltage comparator outputs a high level (the isolation drive circuit outputs a high level), and vice versa. The level output by the threshold voltage comparator circuit controls the gate voltage of the SiC MOSFET through the isolation drive circuit. That is, when the isolation drive circuit input is high, the drain-source of the SiC MOSFET is turned on, and vice versa. When the drain-source of the SiC MOSFET is turned on, the bleeder resistor is connected to the power circuit. The power energy is then consumed through the bleeder resistor, thus achieving the effect of power bleedering. In other words, the bus voltage will bleed excess power through the "power bleeder resistor → SiC MOSFET" channel, keeping the bus voltage at the threshold voltage level and preventing high voltage from the bus from being directly applied to the driver's power supply terminal, thereby protecting the driver.

[0050] Here, SiC MOS has the characteristics of high switching frequency and low drain-source resistance. Therefore, the switching response time of the discharge resistor circuit is very short, the discharge speed is faster, and the heat loss is reduced, the temperature rise of the switching transistor is reduced, the discharge power and efficiency are increased, and the device does not generate heat seriously.

[0051] Here, the resistance value, rated voltage, and rated power of the bleeder resistor should be selected reasonably according to the actual situation to ensure that the bleeder device works normally.

[0052] Preferably, in some embodiments, the threshold voltage is adjusted within a range of 50V to 780V.

[0053] Preferably, in some embodiments, combined with Figure 4 The device also includes a grounded housing (providing safety protection, heat dissipation, and installation functions), within which a printed circuit board is housed and fixed to the housing with screws. The discharge device control circuit and isolation drive circuit are centrally located on the printed circuit board; the SiC MOS transistor is attached to the bottom of the housing interior with thermal grease to ensure heat dissipation and is fixed with screws.

[0054] Preferably, in some embodiments, the housing has interfaces for external control power supply, busbar, chassis ground and bleed resistor, as well as a knob position for adjusting the threshold voltage.

[0055] Here, the housing is made of, but is not limited to, aluminum metal, and the housing is connected to the motor housing and the PE of the driver to shield the motor from interference and protect the human body.

[0056] This device can protect the high-voltage servo drive from instantaneous high-voltage impacts such as bus fluctuations and back electromotive force, thus maintaining the normal operation of the servo drive.

[0057] It should be noted that for components without special structural limitations, any component that can achieve the corresponding function in the existing technology is acceptable.

[0058] It should also be noted that the above-mentioned settings, installations, connections, and fixations can be made using, but are not limited to, bolts, threads, etc. Any existing fixed or movable connection scheme can be adapted, as long as the corresponding function can be achieved.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention without departing from its spirit and scope should be included within the protection scope of the present invention.

Claims

1. A high-voltage servo driver discharge device based on high-impedance isolation sampling, characterized in that, The discharge device adopts a high-impedance isolated bus sampling design, which reduces the high voltage of the bus to a sampling voltage proportionally. After conditioning, it is compared with the discharge threshold voltage by a comparator. The output of the comparator controls the gate voltage of the SiC MOS transistor through an isolation drive circuit, thereby controlling the opening and closing of the discharge resistor connecting the bus voltage and ground, so as to achieve the purpose of discharge when the bus voltage exceeds the threshold.

2. The high-voltage servo driver discharge device based on high-impedance isolation sampling according to claim 1, characterized in that, The discharge device includes a discharge device control circuit and an isolation drive circuit. The discharge device control circuit includes an isolation power supply module, a bus sampling unit, a voltage conditioning unit, a threshold voltage comparison unit, and a discharge power unit. The isolated power supply module is used to convert the control power input into 12V and 5V control power and 12V, 5V and -3.2V drive power, so as to provide stable power to the discharge device control circuit and the isolated drive circuit respectively. The bus sampling unit is used to proportionally reduce the bus high voltage to a sampling voltage through high-impedance isolation. The voltage conditioning unit is used to condition the sampled voltage to obtain a stable bus conditioning voltage; The threshold voltage comparison unit is used to compare the bus conditioning voltage with a customizable threshold voltage, and drive the switch signal to turn on through the isolation drive circuit, thereby controlling the conduction or shutdown of the discharge power unit. When the power discharge unit is turned on, it discharges excess power, thereby maintaining the bus conditioning voltage at the threshold voltage level.

3. The high-voltage servo driver discharge device based on high-impedance isolation sampling according to claim 2, characterized in that, The input and output of the isolated power supply module are not grounded.

4. The high-voltage servo driver discharge device based on high-impedance isolation sampling according to claim 2, characterized in that, The voltage range of the control power supply input is 9V to 36V.

5. The high-voltage servo driver discharge device based on high-impedance isolation sampling according to claim 2, characterized in that, The bus sampling unit includes a first resistor (R1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4), and an operational amplifier. The first resistor (R1) and the third resistor (R3) have the same resistance value, both being high-value resistors on the order of tens of MΩ, and are composed of multiple resistors on the order of MΩ connected in series. The second resistor (R2) and the fourth resistor (R4) have the same resistance value, both on the order of hundreds of KΩ. The negative input terminal of the operational amplifier is grounded through the first resistor (R1) and connected to the output terminal of the operational amplifier through the second resistor (R2). The positive input terminal of the operational amplifier is connected to the bus voltage VP+ through the third resistor (R3) and grounded through the fourth resistor (R4). The operational amplifier outputs a sampling voltage VS+.

6. The high-voltage servo driver discharge device based on high-impedance isolation sampling according to claim 2, characterized in that, The voltage conditioning unit conditions the sampled voltage, including isolation amplification and differential amplification.

7. The high-voltage servo driver discharge device based on high-impedance isolation sampling according to claim 2, characterized in that, The power discharge unit includes a power discharge resistor and a SiC MOS transistor. The power discharge resistor is connected between the bus voltage VP+ and the SiC MOS transistor. The isolation drive circuit turns the SiC MOS transistor on or off to enable or disable the power discharge path.

8. The high-voltage servo driver discharge device based on high-impedance isolation sampling according to claim 2, characterized in that, The threshold voltage can be adjusted within the range of 50V to 780V.

9. The high-voltage servo driver discharge device based on high-impedance isolation sampling according to claim 7, characterized in that, The device also includes a grounded housing with a printed circuit board inside. The control circuit and isolation drive circuit of the discharge device are centrally located on the printed circuit board. The SiC MOS transistor is attached to the bottom of the housing with thermal grease.

10. The high-voltage servo driver discharge device based on high-impedance isolation sampling according to claim 2, characterized in that, The housing has interfaces for external control power supply, busbar, chassis ground and bleed resistor, as well as a knob for adjusting the threshold voltage.

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