CN220172855U

CN220172855U - Counter electromotive force absorption circuit for robot motor

Info

Publication number: CN220172855U
Application number: CN202321728857.6U
Authority: CN
Inventors: 李刚; 崔元洋; 郑洋帆
Original assignee: Shanghai Aobo Intelligent Technology Co ltd
Current assignee: Shanghai Aobo Intelligent Technology Co ltd
Priority date: 2023-07-03
Filing date: 2023-07-03
Publication date: 2023-12-12
Anticipated expiration: 2033-07-03

Abstract

The utility model relates to the technical field of robots, in particular to a back electromotive force absorption circuit for a robot motor, which at least comprises the following components: the device comprises an input end, a logic and MOS control circuit, a first N-MOS tube, a charge pump module, a braking module, a current sampling comparison module and a bus output; the logic and MOS control circuit is respectively connected with the charge pump, the G pole of the first N-MOS tube and the signal output end of the current sampling comparison module; the S pole of the first N-MOS tube is connected with the input end, and the D pole of the first N-MOS tube is connected with the bus output; the braking module and the current sampling comparison module are arranged on a connecting line of the D pole of the first N-MOS tube and the bus output. The technical scheme provided by the utility model has the advantages of preventing the current backflow of the bus circuit, small heat productivity of the parasitic diode, good stability of the whole circuit and the like.

Description

Counter electromotive force absorption circuit for robot motor

Technical Field

The utility model relates to the technical field of robots, in particular to a back electromotive force absorption circuit for a robot motor.

Background

When the robot moves, a reverse electromotive force higher than a power supply voltage may be generated due to the three-phase brushless motor in the process of deceleration. In order to prevent the reverse electromotive force from damaging the robot circuitry, a regenerative back electromotive force absorbing circuit is generally provided. The circuit is typically disposed in the robot base.

In the prior art, the circuit mainly comprises a schottky diode, a PWM chopper control circuit, a resistor and an MOS. Wherein, PWM chopper controller can gather the real-time voltage of generating line. When the bus voltage is too high, PWM chopping operation is carried out, then MOS is driven, braking energy is consumed at the resistor end, and therefore the bus voltage is controlled. However, the schottky diode is used to prevent back electromotive force generated by braking energy from flowing back to the power supply, thereby raising the power supply voltage, and further causing overvoltage protection of the power supply and even causing damage to the power supply. In addition, the schottky diode can generate the problem of generating heat under the big electric current work of robot, and cause the diode reverse leakage current to increase, lead to the electric energy utilization ratio to reduce, influence the reliability of robot under the high speed, increase the fault risk. Meanwhile, if the power supply is a battery assembly, the conventional schottky diode system cannot control the current backflow of back electromotive force, and cannot recover energy, so that the battery endurance time is shortened.

Disclosure of Invention

The utility model provides a back electromotive force absorbing circuit for a robot motor, aiming at the technical problems of reduced reliability, reduced electric energy utilization rate and the like of a robot in the prior art that a back electromotive force formed by a Schottky diode absorbs current.

The utility model provides a back electromotive force absorbing circuit for a robot motor, which at least comprises: the device comprises an input end, a logic and MOS control circuit, a first N-MOS tube, a charge pump module, a brake module, a current sampling comparison module, an output bus capacitor and a bus output;

the logic and MOS control circuit is respectively connected with the charge pump module, the G pole of the first N-MOS tube and the signal output end of the current sampling comparison module;

the S pole of the first N-MOS tube is connected with the input end, and the D pole of the first N-MOS tube is connected with the bus output;

the current sampling comparison module and the output bus capacitor are arranged on a connecting line of the D pole of the first N-MOS tube and bus output.

Specifically, one of the concepts of the utility model is to eliminate the heating problem caused by the voltage drop of the schottky diode through the structural design of the circuit, thereby improving the utilization rate of electric energy. It should be noted that, in the prior art, the servo joint of the robot is generally controlled by adopting a FOC algorithm in a closed loop manner. In the FOC microcosmic control flow, there is a control flow in which the upper pipe or the lower pipe of the three-phase half bridge is fully opened. In this flow, when the motor is in a rotating state, the back electromotive force of the motor is not 0 at this time and is positively correlated with the motor rotation speed. In the next stage of microscopic control, the motor back emf may be higher than the bus voltage. With the recent demands of miniaturization and high speed and high load of mechanical arms, the heat generated by the voltage drop of schottky diodes is becoming more and more not smaller.

In the circuit structure provided by the utility model, the logic and MOS control circuit can adjust the pressure difference between the G pole and the S pole of the first N-MOS tube, so that the voltage drop of the parasitic diode of the first N-MOS tube is eliminated, and the technical problem that the Schottky diode is easy to heat under high current is solved. In addition, the current sampling comparison module is used for detecting whether the bus passes through the current or not and sending an electric signal to the logic and MOS control circuit based on the detection condition of the current; the logic and MOS control circuit controls the charge pump module to carry out chopping operation according to the received electric signals, so that the pressure difference between the G pole and the S pole of the first N-MOS tube is adjusted, the first N-MOS tube is driven, and braking energy is consumed on the braking module.

In addition, the output bus capacitor is used for absorbing and storing energy generated by bus output.

Further, the utility model also comprises: the singlechip IO is connected with the logic and MOS control circuit.

Specifically, based on the technical scheme, the logic and MOS control circuit can passively execute operation according to the electric signal input by the current sampling comparison module, and can also execute operation through the single chip microcomputer IO active control logic and the MOS control circuit, so that the maneuverability of the whole circuit is improved.

In some embodiments, the braking module is disposed proximate to the D pole of the first N-MOS transistor and the current sampling comparison module is disposed proximate to the bus output.

Specifically, since the braking module is configured to consume braking energy, if the current sampling comparison module is disposed before the braking module, a current value detected by the current sampling comparison module may be higher, which may result in erroneous output of an electrical signal. At this time, if the first N-MOS transistor is driven based on the error signal, a system abnormality may be caused. Therefore, the technical scheme can improve the accuracy of signal acquisition of the current sampling comparison module and improve the control precision of the whole circuit.

Further, the braking module at least includes: the brake resistor, the second N-MOS tube and the brake controller;

the connecting wire at one end of the brake resistor is connected with the connecting wire of the D pole of the first N-MOS tube and the bus output, and the connecting wire at the other end of the brake resistor is connected with the D pole of the second N-MOS tube;

and the S electrode of the second N-MOS tube is grounded, and the G electrode of the second N-MOS tube is connected with the brake controller.

In some embodiments, the charge pump module comprises a pumping circuit formed by a voltage reducing circuit, and comprises a voltage reducing circuit output source, a first diode, a second diode and a storage capacitor, a pumping capacitor and an inductor which are sequentially connected;

one end of the pumping capacitor is connected between the first diode and the second diode, the other end of the pumping capacitor is connected with the input end of the inductor, and the output end of the inductor is connected with the output source of the voltage reduction circuit.

Specifically, when the voltage of the input end of the inductor is the input end voltage, the output source of the voltage reducing circuit can raise the driving voltage to the input end voltage plus the output source voltage of the voltage reducing circuit, so that the first N-MOS tube is driven.

In some embodiments, the charge pump module may be driven directly from the input to obtain the drive voltage.

Specifically, in order to reduce the complexity of the circuit structure, the charge pump module may be directly connected to the input terminal, and the driving voltage is obtained through the input terminal, so as to realize the conduction of the first N-MOS transistor.

Specifically, the charge pump module is driven by a special charge pump module, and is directly driven through an input end to control the opening and closing of the first N-MOS tube. Because the embodiment adopts a direct power-taking mode, the circuit of the charge pump module can be simplified, and the complexity of the circuit is reduced.

In some embodiments, in a pumping circuit configured by a step-down circuit, a resistance is connected in series between the first capacitor pump_c1 and the second capacitor pump_c2, and/or ESR capacitance of the first capacitor pump_c1 and the second capacitor pump_c2 is increased.

Specifically, the first capacitor pump_c1 and the second capacitor pump_c2 are used for matching with the charge PUMP to output voltage. Therefore, the first capacitor PUMP_C1 cannot be suddenly changed, so that the voltage is prevented from being raised, and the overvoltage protection of the BUCK controller is prevented from being triggered by mistake. The technical scheme aims to ensure the reliability of the charge PUMP module by adding the first capacitor PUMP_C1 and the second capacitor PUMP_C2.

In some embodiments, the current sampling comparison module comprises a bus current sampler, a differential current detector, a first voltage divider, a hysteresis comparator and a second voltage divider which are sequentially connected;

the second voltage divider is connected with the logic and MOS control circuit.

Specifically, the bus current sampler is used for detecting the current of the bus input end, so as to detect whether the bus output generates high and low currents or not, and feed back an electric signal to the logic and MOS control circuit.

Further, the current sampling comparison module further includes a current detection output disposed between the differential current detector and the first voltage divider.

In some embodiments, the first voltage divider and the second voltage divider may each perform at least one of the following three operations of no conversion, voltage conversion, and impedance conversion.

In summary, the utility model can effectively detect large current when the large current is generated at the bus output through the matching of the input end, the logic and MOS control circuit, the first N-MOS tube, the charge pump module, the brake module, the current sampling comparison module, the bus output and other modules. When large current exists, the logic and MOS control circuit can adjust the output voltage of the charge pump module through the feedback of the electric signal of the singlechip I/O or the current sampling comparison module, so that the problems of increased heating value, reduced electric energy utilization efficiency and the like of the Schottky diode under the large current are solved, and the reliability of the whole circuit is improved. Meanwhile, the Schottky diode system of the absorption circuit can control the back flow of electromotive force and current, and recover the circuit energy, so that the endurance time of the battery is prolonged.

Drawings

The utility model will be described in further detail below in connection with the drawings and the preferred embodiments, but it will be appreciated by those skilled in the art that these drawings are drawn for the purpose of illustrating the preferred embodiments only and thus should not be taken as limiting the scope of the utility model. Moreover, unless specifically indicated otherwise, the drawings are merely schematic representations, not necessarily to scale, of the compositions or constructions of the described objects and may include exaggerated representations.

Fig. 1 is a schematic structural diagram of a back electromotive force absorption circuit for a robot motor according to an embodiment of the present utility model;

fig. 2 is a schematic structural diagram of a back electromotive force absorbing circuit for a robot motor according to still another embodiment of the present utility model;

fig. 3 is a schematic structural diagram of a back emf absorbing circuit for a robot motor according to another embodiment of the utility model.

Detailed Description

The present utility model will be described in detail with reference to fig. 1 to 3.

The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.

The utility model provides a back electromotive force absorption circuit for a robot motor, which has the advantages of good reliability, low heat dissipation capacity of the circuit and the like.

Referring to fig. 1, a schematic structure diagram of a back electromotive force absorption circuit for a robot motor according to an embodiment of the present utility model is shown in fig. 1.

The input end is circuit input, and the bus output is circuit output. The circuit current is output from the input end and the first N-MOS tube to the bus. The logic and MOS control circuit is respectively connected with the charge pump module, the G pole of the first N-MOS tube and the signal output end of the current comparison module.

It is understood that the schematic diagram is based on fig. 1. The absorption circuit provided by the utility model has at least two working states in the working process.

State 1: when a large current passes between the input end and the bus output, the current sampling comparison module is used for collecting current on the circuit, generating a high-level signal according to the collected current condition, transmitting the high-level signal to the logic and MOS control circuit, and controlling the voltage output of the charge pump module to the G pole of the first N-MOS tube according to the obtained high-level signal by the logic and MOS control circuit, so that the difference between the G pole and the S extreme pressure of the first N-MOS tube is larger than a preset threshold value, the first N-MOS tube is opened, the voltage drop of the first N-MOS parasitic diode is eliminated, and the loss is only generated by Rds of the first N-MOS tube. At the moment, the circuit provided by the utility model is regulated according to the large current flowing through the bus circuit, so that the heating value of the circuit is reduced, and the circuit is more stable.

State 2: when small current passes between the first output end and the bus output, the current sampling comparison module outputs a low-level signal, and the logic and MOS control circuit controls the first N-MOS transistor to be cut off according to the low-level signal. The parasitic diode of the first N-MOS transistor now exhibits the conventional diode characteristic. When the bus voltage is higher than the input voltage, the parasitic diode can prevent the bus circuit from flowing back, and the generation of leakage current is avoided.

It should be noted that, the large current and the small current can be determined according to the actual use requirement of the absorption circuit, a current judgment threshold can be set, and when the current value obtained by the current sampling comparison module is greater than the current judgment threshold, the current is judged to be large current, and a high level signal is sent to the logic and MOS control circuit; otherwise, a low current is used to send a low level signal.

Further, a preset threshold value of the pressure difference between the G pole and the S pole of the first N-MOS tube is 12V.

In some embodiments, the output bus capacitance is used to recover additional energy generated by the bus circuit.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a back electromotive force absorbing circuit for a robot motor according to another embodiment of the present utility model.

The absorption circuit provided by the utility model further comprises a singlechip IO and/or a braking module. The singlechip IO can also control the logic and MOS control circuit, so that the first N-MOS is switched on and off. The braking module is used for consuming the excessive voltage generated on the bus, so that the bus voltage is controlled.

Referring to fig. 3, fig. 3 is a schematic structural diagram of a back electromotive force absorbing circuit for a robot motor according to another embodiment of the present utility model.

Specifically, a connecting wire at one end of a braking resistor of the braking module is connected with a connecting wire of the D pole of the first N-MOS tube and the output of the bus, and a connecting wire at the other end of the braking resistor is connected with the D pole of the second N-MOS tube; and the S electrode of the second N-MOS tube is grounded, and the G electrode of the second N-MOS tube is connected with the brake controller. See the inner mold shown by reference numeral (3) in fig. 3. Through the structure, the brake module consumes brake energy by utilizing the brake resistor, so that the control of the voltage on the bus is realized. The brake controller can control the second N-MOS tube.

In some embodiments, the output bus capacitor may be understood as being connected in parallel with the bus output, and the output bus capacitor may be composed of one single capacitor, or may be composed of two or more capacitors connected in parallel.

In some embodiments, the charge pump module includes a step-down circuit as shown in (1) and a pump circuit as shown in (2) in fig. 3. The working principle of the charge pump module is that the voltage is alternately changed between 0 and the voltage of the input end due to BUCK chopping control at the input end of the BUCK controller inductor.

Further, the step-down circuit is sequentially connected with a step-down circuit output source, a first diode, a second capacitor PUMP_C2 and a ground;

the pumping circuit shares a voltage reduction circuit output source of the voltage reduction circuit, and is sequentially connected with an inductor, a third N-MOS tube, an input end and a BUCK controller, wherein an S electrode of the third N-MOS tube is connected with the inductor, a D electrode of the third N-MOS tube is connected with the input end and a G electrode of the third N-MOS tube is connected with the BUCK controller;

a third capacitor PUMP_C3, a third diode and a first capacitor PUMP_C1 are arranged at two ends of the first diode in parallel; the connecting wire at one end of the inductor is connected between the output source of the voltage reduction circuit and the third capacitor PUMP_C3, and the connecting wire at the other end of the inductor is connected between the third diode and the first capacitor PUMP_C3;

and a grounding wire is arranged between the third capacitor PUMP_C3 and the third diode.

When the voltage is 0, the voltage of the output source of the voltage reducing circuit is applied to the parallel end of the first capacitor PUMP_C1 and the second capacitor PUMP_C2 after passing through the second diode.

When the voltage is the input voltage, the voltage at two ends of the first capacitor pump_c1 cannot be suddenly changed, and the voltage is raised to the output source+input voltage of the voltage-reducing circuit and stored in the second capacitor pump_c2.

It should be noted that the output source of the step-down circuit is preferably 12V, and the upper and lower input terminals should be understood as homologous inputs.

Furthermore, the BUCK controller can control the third N-MOS tube.

In some embodiments, the circuit sample comparison module includes a sampling circuit shown in (4) and a comparison circuit shown in (5) of fig. 3. The differential current detector can collect the current of the bus current sampler, meanwhile, the signal is transmitted to the same-direction input end of the hysteresis comparator through the transformation of the first transformer, and the signal is compared with the Vref end of the hysteresis comparator, so that an output signal is generated. When the output current is larger than the Vref end current and the hysteresis current, the bus is judged to pass through the large current, and a high-level signal is output. The level signal is input to the logic and MOS control circuit after passing through the second transformer. When the output current is less than or equal to Vref end current and hysteresis current, a small current signal is output.

Further, the bus current sampler is a current detection resistor.

Comparative example 1

In the prior art, when a schottky diode is used as the anti-reflux scheme, the ambient temperature=25 ℃, taking TO-263 encapsulated MBRB60100CT as an example, and rθja is about 50 ℃/W. At 5A, vf is approximately 0.5V, then thermal power p=0.5v×2.5a=2.5W. Wen Sheng ℃is approximately 125 ℃. Junction temperature approximately 150 ℃, already equal to the limiting operating temperature, is extremely dangerous.

Example 1

When the schottky diode is used as the anti-reflux scheme and the technical scheme provided by the utility model is adopted at the same time, the ambient temperature=25 ℃, the TO-263 package CRST045N10NP is taken as an example, rθja is about 62 ℃/W, and RDS (on) =3.6mΩ. At 5A, the thermal power p=3.6mΩ×5a≡2=0.09W. Wen Sheng ℃is approximately 5.58 ℃. Junction temperature is approximately 30 ℃. The effect is thus improved by a factor of approximately 25. The reliability is greatly improved.

The foregoing has outlined rather broadly the more detailed description of the utility model in order that the detailed description of the utility model that follows may be better understood, and in order that the present utility model may be better understood. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the utility model can be made without departing from the principles of the utility model and these modifications and adaptations are intended to be within the scope of the utility model as defined in the following claims.

Claims

1. A back emf absorbing circuit for a robot motor, comprising at least: the device comprises an input end, a logic and MOS control circuit, a first N-MOS tube, a charge pump module, a brake module, a current sampling comparison module, an output bus capacitor and a bus output;

2. A back emf absorbing circuit for a robot motor as defined in claim 1, further comprising: the singlechip IO is connected with the logic and MOS control circuit.

3. A back emf absorbing circuit for a robot motor according to claim 1 or 2, wherein the braking module is disposed adjacent to the D pole of the first N-MOS transistor and the current sampling comparison module is disposed adjacent to the bus bar output.

4. A back emf absorbing circuit for a robot motor according to claim 3, wherein the braking module comprises at least: the brake resistor, the second N-MOS tube and the brake controller;

5. A back electromotive force absorption circuit for a robot motor according to claim 3, wherein the charge pump module comprises a pumping circuit formed by a voltage reduction circuit, and comprises a voltage reduction circuit output source, a first diode, a second diode and an energy storage capacitor, and a pumping capacitor and an inductor which are sequentially connected;

6. A back emf absorbing circuit for a robot motor according to claim 3, wherein the charge pump module is directly drivable from the input to obtain the drive voltage.

7. A back emf absorbing circuit for a robot motor according to claim 5, characterized in that a resistor is connected in series between the first capacitor pump_c1 and the second capacitor pump_c2 and/or the ESR of the first capacitor pump_c1 and the second capacitor pump_c2 is increased.

8. A back electromotive force absorbing circuit for a robot motor according to claim 3, wherein the current sampling comparison module comprises a bus current sampler, a differential current detector, a first voltage divider, a hysteresis comparator and a second voltage divider which are sequentially connected;

the second voltage divider is connected with the logic and MOS control circuit.

9. The back emf sink circuit for a robot motor of claim 8, wherein the current sample comparison module further comprises a current sense output disposed between the differential current detector and the first voltage divider.

10. A back emf absorbing circuit for a robot motor according to claim 9, wherein the first voltage divider and the second voltage divider are each operable to perform at least one of no-conversion, voltage conversion, and impedance conversion.