Motor brake control circuit and servo driver

Abstract

The application discloses a motor brake control circuit and a servo driver. The circuit comprises a first isolation circuit and a brake driving circuit. The brake driving circuit comprises a trigger circuit, a delay blocking circuit, a first resistor and a driving power supply. The driving power supply is connected to a brake voltage input end of the motor through the first resistor. The delay blocking circuit is connected in parallel with the first resistor. A trigger end of the trigger circuit is connected to the first isolation circuit to receive a trigger signal. The trigger circuit is used for triggering the delay blocking circuit to enter a conduction state after receiving the trigger signal. The delay blocking circuit automatically gradually returns to an open state after entering the conduction state. Since the trigger circuit does not directly output a driving signal to control the brake mechanism, but automatically controls the voltage applied to both ends of the brake mechanism after the trigger circuit is triggered, high-speed components are not needed, and circuit components with lower cost and lower specifications can be adopted, so that the circuit cost is reduced.

Description

Technical Field

[0001] This application relates to the field of circuit technology, and in particular to a motor brake control circuit and servo driver. Background Technology

[0002] After the power is cut off, a motor will continue to rotate for a period of time due to inertia before finally stopping. However, in some scenarios, it is required that the motor stop quickly after the power is cut off to achieve accurate positioning or safety protection. The industry typically uses a brake mechanism to brake the motor. Its working principle is as follows: when the motor is powered on, the brake mechanism is energized and overcomes resistance (such as the tension of a spring) to separate the brake shoes and brake wheel, allowing the motor to run normally. When the power to the motor is cut off, the resistance that separates the brake shoes and brake wheel is lost, causing the brake shoes to grip the brake wheel tightly, thus stopping the motor.

[0003] Therefore, to improve control reliability during motor operation, a high-speed isolation device needs to be installed between the power supply and control signal of the brake mechanism. However, high-speed isolation devices are expensive and require proper debugging, making it impossible to further reduce the cost of motor products. Therefore, the brake control circuit needs further optimization. Summary of the Invention

[0004] This application provides a motor brake control circuit and servo driver, which can reduce the performance requirements of the motor brake circuit, thereby allowing the selection of low-specification and low-cost components and reducing circuit costs.

[0005] An embodiment of the first aspect of this application provides a motor brake control circuit, including:

[0006] The controller is used to output control signals;

[0007] A first isolation circuit is used to convert the control signal into a trigger signal;

[0008] The brake drive circuit includes a trigger circuit, a delay blocking circuit, a first resistor, and a drive power supply. The drive power supply is connected to the brake voltage input terminal of the motor via the first resistor. The delay blocking circuit is connected in parallel with the first resistor. The trigger terminal of the trigger circuit is connected to the first isolation circuit to receive the trigger signal. The trigger circuit is used to trigger the delay blocking circuit to enter the closed state after receiving the trigger signal. After entering the closed state, the delay blocking circuit automatically and gradually returns to the open state.

[0009] The circuit according to the first aspect of the present application has at least the following beneficial effects: In the initial stage of driving the brake mechanism to open, the circuit triggers the delay blocking circuit to enter the closed state through the trigger circuit, and drives the brake mechanism to open with a high voltage. Thereafter, the delay blocking circuit gradually changes from the closed state to the open state. The voltage of the driving power supply is divided by the first resistor to supply power to the brake mechanism. The voltage across the brake mechanism is reduced to the voltage level that maintains the open state of the brake mechanism, thereby reducing the power consumption of the circuit. Since the trigger circuit does not directly output a driving signal to control the brake mechanism, but automatically controls the voltage applied across the brake mechanism after the trigger circuit is triggered, high-speed components are not required, and lower-cost, lower-specification circuit components can be used, thereby reducing the circuit cost.

[0010] In some embodiments, the triggering circuit includes a first switching transistor, a first terminal of which is connected to the delay blocking circuit, a second terminal of which is grounded, a control terminal of which is connected to the first isolation circuit as the trigger terminal, and the trigger signal is a level signal used to trigger the first switching transistor to turn on.

[0011] In some embodiments, the delay blocking circuit includes a second switching transistor and a voltage divider circuit. The voltage divider circuit includes a second resistor, a third resistor, and a charging capacitor connected in series. One end of the second resistor serves as one end of the voltage divider circuit and is connected to the connection point between the driving power supply and the first resistor. One end of the charging capacitor serves as the other end of the voltage divider circuit and is connected to the first end of the first switching transistor. The connection point between the second resistor and the third resistor is connected to the control terminal of the second switching transistor. The first end of the second switching transistor is connected to the connection point between the driving power supply and the first resistor. The second end of the second switching transistor is connected to the connection point between the brake voltage input terminal and the first resistor.

[0012] In some embodiments, the first isolation circuit includes a first opto-isolator.

[0013] In some embodiments, a fault detection circuit and a second isolation circuit are further included. The fault detection circuit includes a voltage sampling terminal and a comparison circuit. The comparison circuit is connected to the voltage sampling terminal and the second isolation circuit and is used to compare the voltage at the brake voltage input terminal with the magnitude of a reference voltage and output an indication signal to the second isolation circuit according to the comparison result. The second isolation circuit is used to send a fault signal to the controller according to the indication signal.

[0014] In some embodiments, the reference voltage includes a first reference voltage and a second reference voltage that are not equal, the comparison circuit includes a first comparator and a second comparator, the non-inverting input of the first comparator is connected to the voltage sampling terminal, the inverting input of the first comparator is input to the first reference voltage, the non-inverting input of the second comparator is input to the second reference voltage, and the inverting input is connected to the voltage sampling terminal.

[0015] In some embodiments, the first reference voltage and the second reference voltage are obtained by dividing the voltage of the drive power supply.

[0016] In some embodiments, the second isolation circuit includes a second isolator, and the outputs of the first comparator and the second comparator are both connected to the second isolator;

[0017] Alternatively, the second isolation circuit includes two second isolators, with the outputs of the first comparator and the second comparator respectively connected to the corresponding second isolators, and the two second isolators respectively used to output the fault signal.

[0018] In some embodiments, the second isolator is a second opto-isolator.

[0019] A second aspect of this application provides a servo driver that includes the motor brake control circuit described in the first aspect.

[0020] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0021] Figure 1 This is a connection block diagram of the motor brake control circuit provided in the embodiments of this application;

[0022] Figure 2 This is a partial circuit diagram of the motor brake control circuit provided in the embodiments of this application;

[0023] Figure 3 This is a circuit diagram of a fault detection circuit provided in an embodiment of this application;

[0024] Figure 4 This is a circuit diagram of another fault detection circuit provided in an embodiment of this application. Detailed Implementation

[0025] 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. Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various implementations. Simultaneously, the steps or actions described in the method description can be rearranged or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0026] In the description of this application, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0027] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0028] The brake mechanism, in the absence of power, grips the brake wheel with the brake shoes for emergency braking of the motor. Therefore, in its working principle, it requires power to separate the brake shoes from the brake wheel, allowing the motor to rotate normally. Currently, there are several drive methods for brake mechanisms in the industry, all of which have some problems. For example, using a drive circuit to drive the switching transistor and thus control the voltage across the brake mechanism requires setting PWM (Pulse Width Modulation) parameters to obtain a duty cycle signal suitable for the current operating state. If the PWM parameters are not set properly, the voltage across the brake mechanism will be unstable, resulting in electromagnetic noise and friction between the brake shoes and the brake wheel, affecting the lifespan of the brake mechanism. Another method is to use an isolator to isolate the control signal from the brake power supply. To provide reliable control, a high-speed isolator is usually placed between the switching transistor and the controller to achieve PWM voltage regulation, which increases the circuit cost.

[0029] Based on this, embodiments of this application provide a motor brake control circuit and a servo driver, including a first isolation circuit and a brake drive circuit. The brake drive circuit includes a trigger circuit, a delay blocking circuit, a first resistor, and a drive power supply. The trigger circuit triggers the delay blocking circuit to enter a closed state after receiving a trigger signal. After entering the closed state, the delay blocking circuit automatically and gradually returns to an open state. Since precise PWM signals are not required to directly control the brake mechanism, the accuracy requirements of the signals driving the brake mechanism are reduced, allowing the use of lower-cost, lower-specification circuit components, thereby reducing circuit costs.

[0030] The motor brake control circuit is described below with reference to the attached diagram:

[0031] Reference Figure 1 and Figure 2 As shown in the embodiment of this application, a motor brake control circuit includes:

[0032] Controller 100 is used to output control signals;

[0033] The first isolation circuit 200 is used to convert the control signal into a trigger signal;

[0034] The brake drive circuit 300 includes a trigger circuit 310, a delay blocking circuit 320, a first resistor R1, and a drive power supply. The drive power supply is connected to the brake voltage input terminal Braker+ of the motor via the first resistor R1. The delay blocking circuit 320 is connected in parallel with the first resistor R1. The trigger terminal of the trigger circuit 310 is connected to the first isolation circuit 200 to receive a trigger signal. The trigger circuit 310 is used to trigger the delay blocking circuit 320 to enter the pass state after receiving the trigger signal.

[0035] In this embodiment, the first resistor R1 and the delay blocking circuit 320 work together to control the voltage on the brake mechanism. When the delay blocking circuit 320 is in the closed state, the first resistor R1 is short-circuited, and the driving power supply directly powers the brake mechanism through the closed state of the delay blocking circuit 320. When the delay blocking circuit 320 is in the open state, the driving power supply powers the brake mechanism after voltage division through the first resistor R1. Therefore, it can be seen that this embodiment controls the voltage across the brake mechanism through the delay blocking circuit 320. The delay blocking circuit 320 is triggered by the trigger circuit 310 and can automatically recover from the blocking state. The brake mechanism requires a higher voltage at the initial opening stage. Therefore, the characteristic of the delay blocking circuit 320 is to make itself in the closed state at the initial triggering stage, and the voltage of the driving power supply is basically directly applied to the brake mechanism, thereby driving the brake mechanism to open with a higher voltage at the initial stage. The delayed blocking circuit 320 can automatically and gradually return to the open circuit state when it is in the closed circuit state. Since the first resistor R1 and the delayed blocking circuit 320 are connected in parallel, when the delayed blocking circuit 320 is in the open circuit state, the voltage of the drive power supply is applied to the brake mechanism after being divided by the first resistor R1. The voltage on the brake mechanism is lower than the initial voltage. By designing the resistance value of the first resistor R1, the brake mechanism can maintain the brake shoe open state with a voltage lower than the initial voltage, thereby reducing the power consumption on the brake mechanism during motor operation.

[0036] The delay blocking circuit 320 is triggered by the trigger circuit 310 according to the trigger signal, and the trigger signal is obtained by the first isolation circuit 200 converting the control signal. According to the above control process, the control circuit of this embodiment does not need a high-speed PWM signal to drive the brake mechanism. Based on the delay blocking circuit 320, the brake mechanism is automatically controlled. Therefore, the requirements for circuit components can be reduced while ensuring the stable driving of the brake mechanism. For example, high-speed isolators are not required, and it is not necessary to quickly control the switching transistor to generate control voltage. Therefore, it is not necessary to use high-specification and high-cost components, nor is it necessary to use precise PWM signals for control, thereby reducing circuit costs.

[0037] In one embodiment, the trigger circuit 310 and the delay blocking circuit 320 can work together using a switching transistor.

[0038] The trigger circuit 310 includes a first switch Q1, the first end of the first switch Q1 is connected to the delay blocking circuit 320, the second end of the first switch Q1 is grounded, the control end of the first switch Q1 is connected to the first isolation circuit 200 as the trigger end, and the trigger signal is a level signal used to trigger the first switch Q1 to conduct.

[0039] The trigger circuit 310 is equipped with a first switch transistor Q1 to respond to the trigger signal issued by the first isolation circuit 200. The first switch transistor Q1 changes from the cut-off state to the on state according to the trigger signal, so that the first terminal and the second terminal are connected. Since the second terminal is grounded, the voltage of the first terminal is pulled down, thereby causing the delay blocking circuit 320 to operate.

[0040] In one embodiment, the first isolation circuit 200 includes a first opto-isolator U1. The first opto-isolator U1 can be triggered to output a high level according to the input signal. When the first isolation circuit 200 receives a control signal, after signal conversion by the first opto-isolator U1, the output terminal of the first isolation circuit 200 outputs a high-level trigger signal, thereby turning on the first switch Q1.

[0041] To match the characteristics of the delay blocking circuit 320 triggered by the first switch Q1, the delay blocking circuit 320 includes a second switch Q2 and a voltage divider circuit. The voltage divider circuit includes a second resistor R2, a third resistor R3, and a charging capacitor C2 connected in series. One end of the second resistor R2 serves as one end of the voltage divider circuit, connecting the drive power supply to the connection point of the first resistor R1. One end of the charging capacitor C2 serves as the other end of the voltage divider circuit, connecting to the first end of the first switch Q1. The connection point of the second resistor R2 and the third resistor R3 is connected to the control terminal of the second switch Q2. The first end of the second switch Q2 is connected to the connection point of the drive power supply and the first resistor R1. The second end of the second switch Q2 is connected to the connection point of the brake voltage input terminal Braker+ and the first resistor R1.

[0042] Reference Figure 2It can be seen that the second switch Q2 is connected in parallel across the first resistor R1. The conducting state of the second switch Q2 corresponds to the closed state of the delay blocking circuit 320, and the cut-off state of the second switch Q2 corresponds to the open state of the delay blocking circuit 320. The conduction and cut-off of the second switch Q2 are determined by the voltage at its control terminal. In this embodiment, a voltage divider circuit is designed to adjust the voltage input to the control terminal of the second switch Q2. The voltage divider circuit is connected to the drive power supply and the first terminal of the first switch Q1, and a voltage divider terminal is led out between the second resistor R2 and the third resistor R3 and connected to the control terminal of the second switch Q2. As can be seen from the aforementioned trigger circuit 310, when the second switch is off, the voltage divider circuit does not work, there is no voltage at the control terminal of the second switch Q2, and the second switch Q2 is in the off state. When the first switch Q1 is on, a path is formed across the two ends of the voltage divider circuit, and the driving power supply is grounded through the voltage divider circuit to the second terminal of the first switch Q1. Therefore, the charging capacitor C2 begins to charge, and the voltage at the connection of the second resistor R2 and the third resistor R3 gradually rises until the voltage rises to the conduction voltage of the second switch Q2, at which point the second switch Q2 turns on. By designing the resistance values ​​of the second resistor R2 and the third resistor R3, as well as the capacitance value of the charging capacitor C2, the voltage divider can be used to turn on the second switch Q2 and the time required for the second switch Q2 to turn on can be adjusted.

[0043] Therefore, it can be seen that after the trigger signal turns on the first switch Q1, the second switch Q2 will also turn on, and the charging capacitor C2 continues to charge. During the period when the second switch Q2 is in the conducting state, the first resistor R1 is short-circuited. In the initial stage of triggering, the drive power supply directly applies voltage to the brake mechanism, thereby causing the brake mechanism to open and the motor to work normally. As time goes by, the charging capacitor C2 is fully charged, the second switch Q2 is in the off state, and the voltage of the drive power supply is applied to the brake mechanism after being divided by the first resistor R1. By designing the resistance value of the first resistor R1, the voltage applied to the brake mechanism after the voltage division by the first resistor R1 can be greater than the rated braking voltage of the brake mechanism but less than the opening voltage of the brake mechanism, thus achieving the purpose of energy saving.

[0044] In the current technology, there is a lack of detection circuits for malfunctions in the brake mechanism. The motor brake control circuit of this application embodiment further includes a fault detection circuit 500 and a second isolation circuit 400. The fault detection circuit 500 includes a voltage sampling terminal and a comparison circuit. The comparison circuit is connected to the voltage sampling terminal and the second isolation circuit 400, and is used to compare the voltage at the brake voltage input terminal Braker+ with the reference voltage and output an indication signal to the second isolation circuit 400 according to the comparison result. The second isolation circuit 400 is used to send a fault signal to the controller 100 according to the indication signal. The output terminal of the fault signal is represented as Braker Err.

[0045] The voltage sampling terminal is used to collect the operating voltage of the brake mechanism, i.e., the voltage at the brake voltage input terminal Braker+. By comparing the collected voltage with a reference voltage, it can be further determined whether a fault has occurred in the brake mechanism. Specifically, in this embodiment, the comparison result of the voltage is detected by the second isolator U2 in the second isolation circuit 400. When the comparison circuit outputs an indication signal corresponding to the comparison result, the second isolation circuit 400 can generate a fault signal based on the indication signal. After the system detects the fault signal, it executes corresponding control actions to ensure the safe operation of the brake mechanism.

[0046] The brake mechanism may experience either an open circuit or a short circuit, therefore the fault detection circuit 500 needs to detect these two states separately. Specifically, the reference voltage includes unequal first and second reference voltages. The comparison circuit includes a first comparator U3A and a second comparator U3B. The non-inverting input of the first comparator U3A is connected to the voltage sampling terminal, and the inverting input of the first comparator U3A receives the first reference voltage. The non-inverting input of the second comparator U3B receives the second reference voltage, and the inverting input is connected to the voltage sampling terminal.

[0047] This embodiment employs two comparators, each corresponding to a different input reference voltage. For ease of explanation, we will use the first comparator U3A and the first reference voltage to detect open-circuit faults in the brake mechanism, and the second comparator U3B and the second reference voltage to detect short-circuit faults in the brake mechanism as an example. (Refer to...) Figure 3 and Figure 4 It can be seen that the first reference voltage is output from the voltage divider circuit composed of the ninth resistor R9 and the tenth resistor R10. One end of this voltage divider circuit is connected to the drive power supply, and the other end is grounded. The magnitude of the first reference voltage is determined by designing the resistance values ​​of the ninth resistor R9 and the tenth resistor R10. The second reference voltage is output from the voltage divider circuit composed of the eleventh resistor R11 and the twelfth resistor R12. One end of this voltage divider circuit is also connected to the drive power supply, and the other end is grounded. The magnitude of the second reference voltage is determined by designing the resistance values ​​of the eleventh resistor R11 and the twelfth resistor R12. The two input terminals of the first comparator U3A are respectively input to the sampled voltage and the first reference voltage, and output a first level signal according to the comparison result. The two input terminals of the second comparator U3B are respectively input to the sampled voltage and the second reference voltage, and output a second level signal according to the comparison result. At this time, the second isolation circuit 400 generates a corresponding fault signal for the system based on the first level signal and the second level signal.

[0048] In one embodiment, the second isolation circuit 400 includes only one second isolator U2, and the outputs of both the first comparator U3A and the second comparator U3B are connected to the second isolator U2. Figure 3As shown, the input terminal of the second isolator U2 is connected to the output terminal of the first comparator U3A and the output terminal of the second comparator U3B. Since the open circuit and short circuit faults of the brake mechanism will not occur at the same time, the second isolation circuit 400 can detect the fault without determining what kind of fault it is, based on the purpose of simplifying the circuit structure. That is, the first level signal and the second level signal trigger the same isolator.

[0049] In another embodiment, the second isolation circuit 400 includes two second isolators. The outputs of the first comparator U5A and the second comparator U5B are respectively connected to the corresponding second isolators, and the two second isolators respectively output fault signals. Figure 4 As shown, U4 and U6 represent two second isolators. Isolators U4 and U6 receive the first level signal and the second level signal, respectively. Therefore, the fault detection circuit 500 is divided into two parts: one part is used to detect open-circuit faults in the brake mechanism, and the other part is used to detect short-circuit faults in the brake mechanism. The two isolators output fault signals respectively, and the system can determine what type of fault has occurred in the brake mechanism. However, the circuit is more complex than the previous embodiment.

[0050] Among them, the second isolator U2 / U4 / U6 of the fault detection circuit 500 can be an opto-isolator to achieve electrical isolation between the brake mechanism and the control system.

[0051] It can be seen that the embodiments of this application have the following advantages compared with existing brake control circuits:

[0052] During the maintenance phase after the brake release, the power consumption of the circuit is significantly reduced, effectively saving energy.

[0053] Since PWM control is not used to adjust the voltage, no additional software program needs to be developed for control.

[0054] There are no sudden changes in voltage and current during the brake control process, and no electromagnetic noise is generated.

[0055] The brake release and holding device eliminates friction between the brake shoe and the brake wheel, ensuring the lifespan of the brake mechanism;

[0056] The fault detection circuit 500 can effectively detect faults in the brake mechanism, such as short circuits or open circuits, and prompt the user to perform maintenance.

[0057] The motor brake control circuit of this application is illustrated below with a specific example.

[0058] Reference Figure 2As shown, the first isolation circuit 200 in the motor brake control circuit includes a first opto-isolator U1. The input terminal of the first isolation circuit 200 receives the control signal from the control chip through the Braker ctl port. The control signal is the signal that drives the brake mechanism to open. The first isolation circuit 200 converts the control signal into a high-level trigger signal and sends the trigger signal to the trigger circuit 310. The first opto-isolator U1 contains a photosensitive switch. The collector of the switch is connected to the drive power supply, and the emitter of the switch serves as the output terminal connected to the trigger circuit 310. The control signal causes the light-emitting diode in the first opto-isolator U1 to emit light, thereby turning on the switch inside the first opto-isolator U1. The drive power supply provides a high-level trigger signal to the trigger circuit 310 through the switch.

[0059] The trigger circuit 310 includes a first switching transistor Q1. The first terminal of the first switching transistor Q1 is connected to a delay blocking circuit 320, and the second terminal of the first switching transistor Q1 is grounded. The control terminal of the first switching transistor Q1 is connected to the output terminal of the first isolation circuit 200 to receive a high-level trigger signal. At this time, the first switching transistor Q1 is turned on, causing the delay blocking circuit 320 to be pulled down to ground. Additionally, the trigger circuit 310 also includes a Zener diode D3 and a fourth capacitor C4 for overvoltage protection. The Zener diode D3 and the fourth capacitor C4 are connected in parallel, and the cathode of the Zener diode D3 is connected to the control terminal of the first switching transistor Q1, while its anode is grounded.

[0060] The delay blocking circuit 320 includes a second switch Q2 and a voltage divider circuit. The voltage divider circuit includes a second resistor R2, a third resistor R3, and a charging capacitor C2 connected in series. One end of the second resistor R2 serves as one end of the voltage divider circuit, connecting the drive power supply to the connection point of the first resistor R1. One end of the charging capacitor C2 serves as the other end of the voltage divider circuit, connecting the first end of the first switch Q1. The connection point of the second resistor R2 and the third resistor R3 is connected to the control terminal of the second switch Q2. The first end of the second switch Q2 is connected to the connection point of the drive power supply and the first resistor R1. The second end of the second switch Q2 is connected to the connection point of the brake voltage input terminal Braker+ and the first resistor R1.

[0061] The second switch Q2 is connected in parallel across the first resistor R1. The on state of the second switch Q2 corresponds to the closed state of the delay blocking circuit 320, and the off state of the second switch Q2 corresponds to the open state of the delay blocking circuit 320. The on and off states of the second switch Q2 are determined by the voltage at its control terminal. In this embodiment, a voltage divider circuit is designed to adjust the voltage input to the control terminal of the second switch Q2. The voltage divider circuit is connected to the drive power supply and the first terminal of the first switch Q1, and a voltage divider terminal is led out between the second resistor R2 and the third resistor R3 and connected to the control terminal of the second switch Q2. According to the aforementioned trigger circuit 310, when the second switch is off, the voltage divider circuit does not work, the control terminal of the second switch Q2 has no voltage, and the second switch Q2 is in the off state. When the first switch Q1 is on, the two ends of the voltage divider circuit form a path, and the driving power supply is grounded to the second terminal of the first switch Q1 through the voltage divider circuit. Therefore, the charging capacitor C2 starts to charge, and the voltage at the connection of the second resistor R2 and the third resistor R3 gradually rises until the voltage rises to the conduction voltage of the second switch Q2. At this time, the second switch Q2 is turned on.

[0062] Therefore, it can be seen that after the trigger signal turns on the first switch Q1, the second switch Q2 will also turn on, and the charging capacitor C2 continues to charge. During the period when the second switch Q2 is in the conducting state, the first resistor R1 is short-circuited. In the initial stage of triggering, the drive power supply directly applies voltage to the brake mechanism, thereby causing the brake mechanism to open and the motor to work normally. As time goes by, the charging capacitor C2 is fully charged, the second switch Q2 is in the off state, and the voltage of the drive power supply is applied to the brake mechanism after being divided by the first resistor R1. By designing the resistance value of the first resistor R1, the voltage applied to the brake mechanism after the voltage division by the first resistor R1 can be greater than the rated braking voltage of the brake mechanism but less than the opening voltage of the brake mechanism, thus achieving the purpose of energy saving.

[0063] In this circuit, both the second switch Q2 and the first switch Q1 are connected in parallel with diodes or have a body diode. The motor brake control circuit also includes a first diode D1 and a second diode D2. The first diode D1 is connected in parallel with the voltage divider circuit, and the second diode D2 is connected in parallel with the two voltage input terminals of the brake mechanism. A second capacitor C2 is connected in series between the third resistor R3 and the first terminal of the first switch Q1.

[0064] When controller 100 outputs a control signal (brake release signal), the first opto-isolator U1 turns on, the first switch Q1 conducts, the second capacitor C2 begins charging, and the second switch Q2 also conducts. Because the on-state voltage drop of the second switch Q2 is very low at this time, the voltage output from the drive power supply via the second switch Q2 is high, enabling effective and rapid brake release. When the second capacitor C2 is fully charged, the second switch Q2 turns off, and the voltage from the drive power supply is output to the brake after passing through the first resistor R1. Due to the voltage division by the first resistor R1, the voltage across the brake decreases, and the brake power supply output current decreases, achieving energy saving while effectively maintaining the brake release state. Because the brake voltage is reduced through resistor voltage division, there is no need for rapid switching control voltage via the first switch Q1. Therefore, the isolator does not need to use a high-cost, high-speed optocoupler. The second switch Q2 only carries current for a short time, allowing the use of low-specification, low-cost components.

[0065] The motor brake control circuit also includes a fault detection circuit 500 and a second isolation circuit 400, which have two forms. The first form is as follows: Figure 3 As shown, the second isolation circuit 400 has a second isolator U2, and the second form is as follows: Figure 4 As shown, the second isolation circuit 400 has two second isolators (denoted as U4 and U6).

[0066] Both types of fault detection circuits 500 are identical, including a voltage sampling terminal and a comparator circuit. The voltage sampling terminal is connected to the brake voltage input terminal Braker+. The comparator circuit includes a first comparator U3A and a second comparator U3B. The non-inverting input of the first comparator U3A is connected to the voltage sampling terminal, and the inverting input of the first comparator U3A receives the first reference voltage. The non-inverting input of the second comparator U3B receives the second reference voltage, and the inverting input is connected to the voltage sampling terminal. The first reference voltage is output from the voltage divider circuit composed of the ninth resistor R9 and the tenth resistor R10. One end of this voltage divider circuit is connected to the drive power supply, and the other end is grounded. The magnitude of the first reference voltage is determined by designing the resistance values ​​of the ninth resistor R9 and the tenth resistor R10. The second reference voltage is output from the voltage divider circuit composed of the eleventh resistor R11 and the twelfth resistor R12. One end of this voltage divider circuit is also connected to the drive power supply, and the other end is grounded. The magnitude of the second reference voltage is determined by designing the resistance values ​​of the eleventh resistor R11 and the twelfth resistor R12. In one configuration of the second isolation circuit 400, the outputs of both the first comparator U3A and the second comparator U3B are connected to the same second isolator U2, and the output of the second isolator U2 is connected to the fault signal output terminal BrakerErr. In another configuration of the second isolation circuit 400, the outputs of the first comparator U5A and the second comparator U5B are connected to isolators U4 and U6, respectively, and the outputs of isolators U4 and U6 are connected to the fault signal output terminals BrakerErr1 and BrakerErr2, respectively.

[0067] When the controller 100 outputs a control voltage to release the brake, if the brake is disconnected, the voltage at the brake voltage input terminal Braker+ will be higher than the voltage at the tenth resistor R10. The first comparator U3A outputs an ON signal, the second isolator U2 is also ON, and the output H at the fault signal output terminal Braker Err becomes L. If the brake is short-circuited, the voltage drop between the second switch Q2 and the first resistor R1 increases, and the voltage at the brake voltage input terminal Braker+ will be lower than the voltage at the twelfth resistor R12. The first comparator U3A outputs an ON signal, the second isolator U2 is also ON, and the output H at the fault signal output terminal Braker Err becomes L. The controller 100 connects to the fault signal output terminal Braker Err and identifies brake faults based on the level changes (the first method can only identify brake faults, the second method can identify which type of brake fault). To prevent erroneous detection of the brake status, the controller 100 does not detect fault status before the switch Q2 is turned off.

[0068] A second aspect of this application also provides a servo driver, including the motor brake control circuit of any embodiment of the first aspect.

[0069] The above is a detailed description of the preferred embodiments of this application. However, this application is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A motor brake control circuit, characterized by comprising: include: The controller is used to output control signals; A first isolation circuit is used to convert the control signal into a trigger signal; The brake drive circuit includes a trigger circuit, a delay blocking circuit, a first resistor, and a drive power supply. The drive power supply is connected to the brake voltage input terminal of the motor via the first resistor. The delay blocking circuit is connected in parallel with the first resistor. The trigger terminal of the trigger circuit is connected to the first isolation circuit to receive the trigger signal. The trigger circuit is used to trigger the delay blocking circuit to enter the closed state after receiving the trigger signal. After entering the closed state, the delay blocking circuit automatically and gradually returns to the open state. The trigger circuit includes a first switching transistor, and the delay blocking circuit includes a second switching transistor and a voltage divider circuit. The voltage divider circuit includes a second resistor, a third resistor, and a charging capacitor connected in series. One end of the second resistor serves as one end of the voltage divider circuit and is connected to the connection point between the driving power supply and the first resistor. One end of the charging capacitor serves as the other end of the voltage divider circuit and is grounded through the first switching transistor. The connection point between the second resistor and the third resistor is connected to the control terminal of the second switching transistor. The first end of the second switching transistor is connected to the connection point between the driving power supply and the first resistor, and the second end of the second switching transistor is connected to the connection point between the brake voltage input terminal and the first resistor.

2. The circuit according to claim 1, characterized in that, The first terminal of the first switch is connected to the charging capacitor of the delay blocking circuit, the second terminal of the first switch is grounded, the control terminal of the first switch is connected to the first isolation circuit as the trigger terminal, and the trigger signal is a level signal used to trigger the first switch to turn on.

3. The circuit according to claim 1, characterized in that, The first isolation circuit includes a first opto-isolator.

4. The circuit according to any one of claims 1 to 3, characterized in that, It also includes a fault detection circuit and a second isolation circuit. The fault detection circuit includes a voltage sampling terminal and a comparison circuit. The comparison circuit is connected to the voltage sampling terminal and the second isolation circuit. It is used to compare the voltage at the brake voltage input terminal with the reference voltage and output an indication signal to the second isolation circuit according to the comparison result. The second isolation circuit is used to send a fault signal to the controller according to the indication signal.

5. The circuit according to claim 4, characterized in that, The reference voltage includes a first reference voltage and a second reference voltage that are not equal. The comparison circuit includes a first comparator and a second comparator. The non-inverting input of the first comparator is connected to the voltage sampling terminal. The first reference voltage is input to the inverting input of the first comparator. The second reference voltage is input to the non-inverting input of the second comparator. The inverting input is connected to the voltage sampling terminal.

6. The circuit according to claim 5, characterized in that, The first reference voltage and the second reference voltage are obtained by dividing the voltage of the drive power supply.

7. The circuit according to claim 5, characterized in that, The second isolation circuit includes a second isolator, and the outputs of both the first comparator and the second comparator are connected to the second isolator; Alternatively, the second isolation circuit includes two second isolators, with the outputs of the first comparator and the second comparator respectively connected to the corresponding second isolators, and the two second isolators respectively used to output the fault signal.

8. The circuit according to claim 7, characterized in that, The second isolator is a second opto-isolator.

9. A servo driver, characterized in that, Includes the motor brake control circuit as described in any one of claims 1 to 8.

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