A high-voltage brushless motor driver braking circuit
By combining operational amplifiers and hysteresis control circuits, the anti-interference and overcurrent problems of the braking circuit of high-voltage brushless motor drivers are solved, achieving stable braking and protection of components.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HANGZHOU MOREWAY TECH CO LTD
- Filing Date
- 2025-05-26
- Publication Date
- 2026-07-21
AI Technical Summary
The existing high-voltage brushless motor driver braking circuit has weak anti-interference capability and is easily affected by small fluctuations, resulting in frequent operation. Furthermore, abnormal overcurrent in the braking resistor can damage components.
The circuit structure, consisting of an operational amplifier, a hysteresis control circuit, and a field-effect transistor pre-driver chip, avoids frequent operation and overcurrent through voltage hysteresis control and current sampling protection.
It improves the anti-interference capability of the braking circuit, prevents frequent operation, protects the field-effect transistor, avoids component damage, and achieves stable braking.
Smart Images
Figure CN224538077U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electronic circuit technology, and in particular to a high-voltage brushless motor driver braking circuit. Background Technology
[0002] The braking circuit is a crucial component in brushless motor braking. Without its intervention to dissipate energy during braking, rapid braking cannot be achieved. During braking, the voltage across the filter capacitor (i.e., the positive terminal of the brushless motor driver's bus power supply) is pulled high. When the voltage exceeds a certain value, the braking circuit activates, absorbing the energy generated by the motor through the braking resistor, thereby completing the braking process.
[0003] However, the existing braking circuit has the following defects: 1. It has weak anti-interference ability and is easily affected by small fluctuations, which can lead to frequent operation and abnormal increase in the operating frequency of the field-effect transistor; 2. Abnormal overcurrent in the braking resistor can cause component damage. Utility Model Content
[0004] This application provides a high-voltage brushless motor driver braking circuit to at least solve the above-mentioned technical problems existing in the prior art.
[0005] According to a first aspect of this application, a high-voltage brushless motor driver braking circuit is provided, comprising:
[0006] An operational amplifier, wherein the non-inverting input terminal of the operational amplifier is connected to a voltage sampling circuit, the voltage sampling circuit sampling the voltage at the positive terminal of the bus power supply of the brushless motor driver; and a first reference voltage divider circuit is provided at the inverting input terminal of the operational amplifier.
[0007] A hysteresis control circuit is installed between the output terminal and the non-inverting input terminal of the operational amplifier to perform voltage hysteresis control.
[0008] A field-effect transistor (FET) pre-driver chip is provided. The drive input signal terminal of the FET pre-driver chip is connected to the output terminal of an operational amplifier, and the drive output source terminal of the FET pre-driver chip is connected to the gate of the FET. The output signal of the operational amplifier is amplified to control the conduction of the FET. The drain of the FET is connected to a braking resistor.
[0009] In some embodiments of the first aspect of this application, the voltage sampling circuit includes a first resistor, a second resistor, and a third resistor connected in series; the first resistor is connected to the positive terminal of the bus power supply of the brushless motor driver, and the third resistor is grounded; the connection point of the second resistor and the third resistor is connected to the non-inverting input terminal of the operational amplifier.
[0010] In some embodiments of the first aspect of this application, the voltage sampling circuit further includes a first capacitor, a first terminal of which is connected to the non-inverting input terminal of the operational amplifier, and a second terminal of which is grounded.
[0011] In some embodiments of the first aspect of this application, the first reference voltage divider circuit includes a fourth resistor, a fifth resistor, and a second capacitor; the first end of the fourth resistor is connected to the reference voltage, the second end of the fourth resistor, the first end of the fifth resistor, and the first end of the second capacitor are all connected to the inverting input of the operational amplifier, and the second end of the fifth resistor and the second end of the second capacitor are grounded.
[0012] In some embodiments of the first aspect of this application, the hysteresis control circuit includes a first diode and a sixth resistor. The anode of the first diode is connected to the output terminal of the operational amplifier, the cathode of the first diode is connected to the first terminal of the sixth resistor, and the second terminal of the sixth resistor is connected to the non-inverting input terminal of the operational amplifier.
[0013] In some embodiments of the first aspect of this application, a first signal filtering circuit is provided between the drive input signal terminal of the field-effect transistor pre-driver chip and the output terminal of the operational amplifier. The first signal filtering circuit includes a seventh resistor and a third capacitor. The first end of the seventh resistor is connected to the output terminal of the operational amplifier, the second end of the seventh resistor is connected to the first end of the third capacitor and the drive input signal terminal of the field-effect transistor pre-driver chip, and the second end of the third capacitor is grounded.
[0014] In some embodiments of the first aspect of this application, the field-effect transistor pre-driver chip further includes a comparator input positive terminal, a comparator input negative terminal, and a drive output sink terminal. The comparator input negative terminal is provided with a second reference voltage divider circuit. The source of the field-effect transistor is provided with a current sampling resistor, which is connected to the comparator input positive terminal. The drive output sink terminal is connected to the gate of the field-effect transistor, and the field-effect transistor is controlled to turn off when the input at the comparator input positive terminal is greater than the input at the comparator input negative terminal.
[0015] In some embodiments of the first aspect of this application, the second reference voltage divider circuit includes an eighth resistor, a ninth resistor, and a fourth capacitor. The first end of the ninth resistor is connected to the reference voltage, and the second end of the ninth resistor, the first end of the eighth resistor, and the first end of the fourth capacitor are connected to the comparator input negative terminal of the field-effect transistor pre-driver chip. The second end of the eighth resistor and the fourth capacitor are grounded.
[0016] In some embodiments of the first aspect of this application, a second signal filtering circuit is provided between the current sampling resistor and the positive input terminal of the comparator of the field-effect transistor pre-driver chip. The second signal filtering circuit includes an eleventh resistor and a fifth capacitor. The first end of the eleventh resistor is connected to the current sampling resistor and the source of the field-effect transistor. The second end of the eleventh resistor and the first end of the fifth capacitor are connected to the positive input terminal of the comparator of the field-effect transistor pre-driver chip. The second end of the fifth capacitor is grounded.
[0017] In some embodiments of the first aspect of this application, the braking resistor is provided with a second diode in parallel, the anode of the second diode is connected to the drain of the field-effect transistor, and the cathode of the second diode is connected to the positive terminal of the bus power supply of the brushless motor driver.
[0018] Compared with the prior art, this application has the following advantages:
[0019] 1. This application sets up a hysteresis control circuit between the output terminal and the non-inverting input terminal of the operational amplifier. When the output terminal of the operational amplifier outputs a high level, the voltage of the non-inverting input terminal is increased, thereby realizing voltage hysteresis control and avoiding frequent operation caused by small fluctuations, which would lead to an abnormal increase in the operating frequency of the field-effect transistor.
[0020] 2. This application includes a current sampling resistor to obtain the current magnitude of the braking resistor and convert it into a voltage signal, which is then input to the positive input terminal of the comparator of the field-effect transistor pre-driver chip. When the voltage signal is greater than the negative input terminal of the comparator, the field-effect transistor pre-driver chip controls the field-effect transistor to turn off, preventing abnormal overcurrent in the braking resistor and thus preventing component damage, thereby achieving the effect of overcurrent protection.
[0021] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description
[0022] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which:
[0023] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.
[0024] Figure 1 The circuit block diagram of this application is shown.
[0025] Figure 2 The specific circuit diagram of this application is shown. Detailed Implementation
[0026] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0027] Please refer to Figure 1 and Figure 2 This embodiment provides a high-voltage brushless motor driver braking circuit, including:
[0028] An operational amplifier is provided, wherein the non-inverting input terminal of the operational amplifier is connected to a voltage sampling circuit, the voltage sampling circuit sampling the voltage of the positive terminal VBUS of the bus power supply of the brushless motor driver; and a first reference voltage divider circuit is provided at the inverting input terminal of the operational amplifier.
[0029] Specifically, the operational amplifier is preferably the HT8632, i.e. Figure 2 Operational amplifier U1B in the middle.
[0030] The voltage sampling circuit includes a first resistor R1, a second resistor R2, and a third resistor R3 connected in series. The first resistor R1 is connected to the positive terminal VBUS of the brushless motor driver's bus power supply, and the third resistor R3 is grounded. The connection point of the second resistor R2 and the third resistor R3 is connected to the non-inverting input terminal of the operational amplifier U1B.
[0031] The voltage sampling circuit also includes a first capacitor C1. The first end of the first capacitor C1 is connected to the non-inverting input terminal of the operational amplifier U1B, and the second end of the first capacitor C1 is grounded. The positive terminal VBUS of the bus power supply of the brushless motor driver passes through a voltage divider circuit composed of resistors R1, R2, and R3 and is then filtered by capacitor C1 to obtain a smaller voltage input to the non-inverting input terminal of the operational amplifier U1B.
[0032] The first reference voltage divider circuit includes a fourth resistor R4, a fifth resistor R5, and a second capacitor C2. The first terminal of the fourth resistor R4 is connected to the reference voltage +3.3V. The second terminal of the fourth resistor R4, the first terminal of the fifth resistor R5, and the first terminal of the second capacitor C2 are all connected to the inverting input of operational amplifier U1B. The second terminals of the fifth resistor R5 and the second capacitor C2 are grounded. Resistors R4 and R5 divide the +3.3V power supply, and after filtering by capacitor C2, a reference voltage is obtained and input to the inverting input of operational amplifier U1B.
[0033] A hysteresis control circuit is located between the output terminal and the non-inverting input terminal of the operational amplifier U1B. Specifically, the hysteresis control circuit includes a first diode D1 and a sixth resistor R6. The anode of the first diode D1 is connected to the output terminal of the operational amplifier U1B, the cathode of the first diode D1 is connected to the first terminal of the sixth resistor R6, and the second terminal of the sixth resistor R6 is connected to the non-inverting input terminal of the operational amplifier U1B. When the output terminal of the operational amplifier U1B outputs a high level, the voltage at the non-inverting input terminal is increased, thereby achieving voltage hysteresis control and preventing frequent operation due to small fluctuations, which could lead to an abnormal increase in the operating frequency of the field-effect transistor.
[0034] A field-effect transistor (FET) pre-driver chip U2 has its drive input signal terminal IN connected to the output terminal of operational amplifier U1B. Its drive output source terminal OUTD is connected to the gate of FET Q1 via a tenth resistor R10, amplifying the output signal BRK_IN of operational amplifier U1B to control the conduction of FET Q1. The drain of the FET is connected to a braking resistor P1. When FET Q1 is conducting, the braking resistor P1 absorbs energy from VBUS, achieving braking energy absorption and thus completing braking.
[0035] It is worth mentioning that the braking resistor P1 is also equipped with a second diode D2 connected in reverse parallel. The positive terminal of the second diode D2 is connected to the drain of the field-effect transistor, and the negative terminal of the second diode D2 is connected to the positive terminal VBUS of the brushless motor driver's bus power supply. The second diode D2 is used to absorb the reverse current caused by the parasitic inductance on the braking resistor P1, thereby achieving overvoltage protection for the drain-to-source (VDS) of the field-effect transistor Q1.
[0036] The output signal BRK_IN is the signal at the output terminal of the operational amplifier U1B. This output signal BRK_IN is input to the input terminal of the field-effect transistor pre-driver chip U2 to control the conduction of the field-effect transistor Q1.
[0037] To perform low-pass filtering on the output signal BRK_IN, a first signal filtering circuit is provided between the drive input signal terminal IN of the MOSFET pre-driver chip U2 and the output terminal of the operational amplifier U1B. This first signal filtering circuit includes a seventh resistor R7 and a third capacitor C3. The first end of the seventh resistor R7 is connected to the output terminal of the operational amplifier U1B, and the second end of the seventh resistor R7 is connected to the first end of the third capacitor C3 and the drive input signal terminal IN of the MOSFET pre-driver chip U2. The second end of the third capacitor C3 is grounded. This first signal filtering circuit performs low-pass filtering on the signal at the output terminal of U1B, thereby reducing high-frequency noise interference.
[0038] The field-effect transistor pre-driver chip U2 also includes a comparator input positive terminal VCP+, a comparator input negative terminal VCP-, and a drive output sink terminal OUTS. The comparator input negative terminal VCP- is provided with a second reference voltage divider circuit. The source of the field-effect transistor is provided with a current sampling resistor R12, which is connected to the comparator input positive terminal VCP+. The drive output sink terminal OUTS is connected to the gate of the field-effect transistor. When the input at the comparator input positive terminal VCP+ is greater than the input at the comparator input negative terminal VCP-, the field-effect transistor is turned off.
[0039] Specifically, the second reference voltage divider circuit includes an eighth resistor R8, a ninth resistor R9, and a fourth capacitor C4. The first terminal of the ninth resistor R9 is connected to the reference voltage. The second terminal of the ninth resistor R9, along with the first terminals of the eighth resistor R8 and the fourth capacitor C4, is connected to the comparator negative input VCP- of the MOSFET pre-driver chip U2. The second terminal of the eighth resistor R8 and the fourth capacitor C4 are grounded. Resistors R8 and R9 divide the +3.3V power supply, and after filtering by capacitor C4, a reference voltage is obtained and input to the comparator negative input VCP- of the pre-driver chip U2.
[0040] The current sampling resistor R12 samples the source current of the field-effect transistor Q1 and converts it into a voltage signal, thereby obtaining the magnitude of the current on the braking resistor P1.
[0041] A second signal filtering circuit is provided between the current sampling resistor R12 and the comparator positive input VCP+ of the MOSFET pre-driver chip U2. This second signal filtering circuit includes an eleventh resistor R11 and a fifth capacitor C5. The first end of the eleventh resistor R11 is connected to the current sampling resistor R12 and the source of the MOSFET. The second end of the eleventh resistor R11 and the first end of the fifth capacitor C5 are connected to the comparator positive input VCP+ of the MOSFET pre-driver chip U2. The second end of the fifth capacitor C5 is grounded. The voltage signal sampled by the current sampling resistor R12 is filtered by the low-pass filter circuit composed of resistor R11 and capacitor C5, and then input to the comparator positive input VCP+ of the MOSFET pre-driver chip U2. When this voltage exceeds the voltage at the comparator negative input VCP- of U2, the MOSFET pre-driver chip U2 generates protection and shuts off the output of MOSFET Q1, thus providing overcurrent protection.
[0042] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.
[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.
[0044] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A high-voltage brushless motor driver braking circuit, characterized in that, include: An operational amplifier, wherein the non-inverting input terminal of the operational amplifier is connected to a voltage sampling circuit, the voltage sampling circuit sampling the voltage at the positive terminal of the bus power supply of the brushless motor driver; and a first reference voltage divider circuit is provided at the inverting input terminal of the operational amplifier. A hysteresis control circuit is installed between the output terminal and the non-inverting input terminal of the operational amplifier to perform voltage hysteresis control. A field-effect transistor (FET) pre-driver chip is provided. The drive input signal terminal of the FET pre-driver chip is connected to the output terminal of an operational amplifier, and the drive output source terminal of the FET pre-driver chip is connected to the gate of the FET. The output signal of the operational amplifier is amplified to control the conduction of the FET. The drain of the FET is connected to a braking resistor.
2. The high-voltage brushless motor driver braking circuit according to claim 1, characterized in that, The voltage sampling circuit includes a first resistor, a second resistor, and a third resistor connected in series; the first resistor is connected to the positive terminal of the bus power supply of the brushless motor driver, and the third resistor is grounded; the connection point of the second and third resistors is connected to the non-inverting input terminal of the operational amplifier.
3. The high-voltage brushless motor driver braking circuit according to claim 2, characterized in that, The voltage sampling circuit also includes a first capacitor, the first end of which is connected to the non-inverting input of the operational amplifier, and the second end of which is grounded.
4. The high-voltage brushless motor driver braking circuit according to claim 1, characterized in that, The first reference voltage divider circuit includes a fourth resistor, a fifth resistor, and a second capacitor; the first end of the fourth resistor is connected to the reference voltage, and the second end of the fourth resistor, the first end of the fifth resistor, and the first end of the second capacitor are all connected to the inverting input of the operational amplifier. The second end of the fifth resistor and the second end of the second capacitor are grounded.
5. The high-voltage brushless motor driver braking circuit according to claim 1, characterized in that, The hysteresis control circuit includes a first diode and a sixth resistor. The positive terminal of the first diode is connected to the output terminal of the operational amplifier, the negative terminal of the first diode is connected to the first end of the sixth resistor, and the second end of the sixth resistor is connected to the non-inverting input terminal of the operational amplifier.
6. The high-voltage brushless motor driver braking circuit according to claim 1, characterized in that, A first signal filtering circuit is provided between the drive input signal terminal of the field-effect transistor pre-driver chip and the output terminal of the operational amplifier. The first signal filtering circuit includes a seventh resistor and a third capacitor. The first end of the seventh resistor is connected to the output terminal of the operational amplifier, the second end of the seventh resistor is connected to the first end of the third capacitor and the drive input signal terminal of the field-effect transistor pre-driver chip, and the second end of the third capacitor is grounded.
7. The high-voltage brushless motor driver braking circuit according to claim 1, characterized in that, The field-effect transistor pre-driver chip also includes a comparator input positive terminal, a comparator input negative terminal, and a drive output sink terminal. The comparator input negative terminal is provided with a second reference voltage divider circuit. The source of the field-effect transistor is provided with a current sampling resistor, which is connected to the comparator input positive terminal. The drive output sink terminal is connected to the gate of the field-effect transistor. When the input at the comparator input positive terminal is greater than the input at the comparator input negative terminal, the field-effect transistor is turned off.
8. The high-voltage brushless motor driver braking circuit according to claim 7, characterized in that, The second reference voltage divider circuit includes an eighth resistor, a ninth resistor, and a fourth capacitor. The first end of the ninth resistor is connected to the reference voltage. The second end of the ninth resistor, the first end of the eighth resistor, and the first end of the fourth capacitor are connected to the comparator input negative terminal of the field-effect transistor pre-driver chip. The second end of the eighth resistor and the fourth capacitor are grounded.
9. The high-voltage brushless motor driver braking circuit according to claim 7, characterized in that, A second signal filtering circuit is provided between the current sampling resistor and the positive input terminal of the comparator of the field-effect transistor pre-driver chip. The second signal filtering circuit includes an eleventh resistor and a fifth capacitor. The first end of the eleventh resistor is connected to the current sampling resistor and the source of the field-effect transistor. The second end of the eleventh resistor and the first end of the fifth capacitor are connected to the positive input terminal of the comparator of the field-effect transistor pre-driver chip. The second end of the fifth capacitor is grounded.
10. The high-voltage brushless motor driver braking circuit according to claim 1, characterized in that, The braking resistor is equipped with a second diode in parallel. The positive terminal of the second diode is connected to the drain of the field-effect transistor, and the negative terminal of the second diode is connected to the positive terminal of the bus power supply of the brushless motor driver.