阅读说明：本技术 一种制动电路控制方法、装置、存储介质及伺服电机 (Braking circuit control method and device, storage medium and servo motor ) 是由 许凤霞 经琦 黄伟庭 唐小珠 董喜航 于力奇 于 2021-08-03 设计创作，主要内容包括：本发明提供一种制动电路控制方法、装置、存储介质及伺服电机,所述方法包括：根据直流侧母线电压确定当前待输出的所述制动电路的开关管驱动信号；获取第一预设时长内的第一开关管累计开通时间和第二开关管累计开通时间的累计开通时间之和；根据所述累计开通时间之和是否大于放电电阻不过载的最长总开通时间,确定输出所述开关管驱动信号或者修正所述开关管驱动信号；其中,若判断所述开通时间之和大于所述最长总开通时间,则输出所述开关管驱动信号；若判断所述开通时间之和小于等于所述最长总开通时间,则修正所述开关管驱动信号。本发明提供的方案能够达到同时控制制动电路和保护制动电阻的目的。(The invention provides a braking circuit control method, a braking circuit control device, a storage medium and a servo motor, wherein the method comprises the following steps: determining a switching tube driving signal of the brake circuit to be output currently according to the voltage of the direct-current side bus; acquiring the sum of the accumulated opening time of the first switching tube and the accumulated opening time of the second switching tube within a first preset time length; determining to output the switch tube driving signal or correct the switch tube driving signal according to whether the sum of the accumulated on-time is larger than the longest total on-time that the discharge resistor is not overloaded; if the sum of the on-time is judged to be larger than the longest total on-time, the switch tube driving signal is output; and if the sum of the on-time is judged to be less than or equal to the longest total on-time, correcting the driving signal of the switching tube. The scheme provided by the invention can achieve the purposes of controlling the brake circuit and protecting the brake resistor at the same time.)

1. A method for controlling a brake circuit, comprising:

determining a switching tube driving signal of the brake circuit to be output currently according to the voltage of the direct-current side bus;

acquiring the sum of the accumulated opening time of the first switch tube within a first preset time length and the accumulated opening time of the second switch tube within a second preset time length;

determining to output the switch tube driving signal or correct the switch tube driving signal according to whether the sum of the accumulated on-time is larger than the longest total on-time that the discharge resistor is not overloaded;

if the sum of the on-time is judged to be larger than the longest total on-time, the switch tube driving signal is output; and if the sum of the on-time is judged to be less than or equal to the longest total on-time, correcting the driving signal of the switching tube.

2. The method of claim 1, wherein determining a current output switch tube drive signal for the braking circuit based on a dc side bus voltage comprises:

when the bus voltage is greater than a first voltage threshold value U1 when the brake circuit starts to discharge, outputting a switch tube opening signal; and when the bus voltage is smaller than a second voltage threshold value U2 when the brake circuit stops discharging, outputting a switch tube turn-off signal.

3. The method of claim 1 or 2, wherein obtaining the sum of the cumulative on-time of the first switch tube for a first preset duration and the cumulative on-time of the second switch tube for a second preset duration comprises:

acquiring the on-time of a second switching tube in the time period of the second preset time which passes at present every time when the second preset time passes within the first preset time, and accumulating to obtain the accumulated on-time of the first switching tube;

and adding the accumulated on-time of the first switching tube obtained by accumulation within the first preset time length and the accumulated on-time of the second switching tube which is not accumulated within the first preset time length to obtain the sum of the accumulated on-time.

4. The method according to claim 3, wherein the second switch tube on-time Tsum2 for the second preset time period is obtained by:

in a time period of a second preset time length, every time a sampling period passes, the second switching tube is turned on for a time period Tsum2 ═ Tsum2+ Tsk;

wherein, Tsk is the switch tube on-time in a sampling period Ts, Tsk ^ Uc ^2/U1^ 2; ts is the sampling period, Uc is the bus voltage, and U1 is the first voltage threshold at which the brake current begins to discharge.

5. A method according to any of claims 1-3, characterized in that the maximum total on-time for which the discharge resistor is not overloaded is:

T1＝k*P_R*(t1+t2)/(U1^2/R_R)

wherein k is the power multiplying factor P of the discharge resistor capable of operating for a long time under different heat dissipation conditions_RFor power of braking resistor, R_RFor the resistance value of the brake resistor, t1 is a first preset time period, and t2 is a second preset time period.

6. A braking circuit control device, comprising:

the first determining unit is used for determining a switch tube driving signal of the brake circuit to be output currently according to the voltage of the direct-current side bus;

the acquisition unit is used for acquiring the sum of the accumulated opening time of the first switching tube within a first preset time length and the accumulated opening time of the second switching tube within a second preset time length;

the second determining unit is used for determining to output the switching tube driving signal or correcting the switching tube driving signal according to whether the sum of the accumulated on-time is larger than the longest total on-time that the discharge resistor is not overloaded;

if the sum of the on-time is judged to be larger than the longest total on-time, the switch tube driving signal is output; and if the sum of the on-time is judged to be less than or equal to the longest total on-time, correcting the driving signal of the switching tube.

7. The apparatus according to claim 6, wherein the first determining unit determines the currently output switching tube driving signal of the brake circuit according to the dc-side bus voltage, including:

when the bus voltage is greater than a first voltage threshold value U1 when the brake circuit starts to discharge, outputting a switch tube opening signal; and when the bus voltage is smaller than a second voltage threshold value U2 when the brake circuit stops discharging, outputting a switch tube turn-off signal.

8. The apparatus according to claim 6 or 7, wherein the obtaining unit obtains a sum of accumulated on-times of a first switch tube accumulated on-time within a first preset time period and a second switch tube accumulated on-time within a second preset time period, and includes:

acquiring the on-time of a second switching tube in the time period of the second preset time which passes at present every time when the second preset time passes within the first preset time, and accumulating to obtain the accumulated on-time of the first switching tube;

and adding the accumulated on-time of the first switching tube obtained by accumulation within the first preset time length and the accumulated on-time of the second switching tube which is not accumulated within the first preset time length to obtain the sum of the accumulated on-time.

9. The device of claim 8, wherein the second switch tube on-time Tsum2 in the time period of the second preset time is obtained by:

in a time period of a second preset time length, every time a sampling period passes, the second switching tube is turned on for a time period Tsum2 ═ Tsum2+ Tsk;

wherein, Tsk is the switch tube on-time in a sampling period Ts, Tsk ^ Uc ^2/U1^ 2; ts is the sampling period, Uc is the bus voltage, and U1 is the first voltage threshold at which the brake current begins to discharge.

10. The apparatus according to any of claims 6-9, wherein the maximum total on-time for which the discharge resistor is not overloaded is:

T1＝k*P_R*(t1+t2)/(U1^2/R_R)

wherein k is the power multiplying factor P of the discharge resistor capable of operating for a long time under different heat dissipation conditions_RFor power of braking resistor, R_RFor the resistance value of the brake resistor, t1 is a first preset time period, and t2 is a second preset time period.

11. A storage medium, having stored thereon a computer program which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 5.

12. A servo motor comprising a processor, a memory and a computer program stored on the memory and executable on the processor, the processor when executing the program implementing the steps of the method of any one of claims 1 to 5 or comprising the brake circuit control apparatus of any one of claims 6 to 10.

Technical Field

The present invention relates to the field of control, and in particular, to a method and an apparatus for controlling a braking circuit, a storage medium, and a servo motor.

Background

In a three-phase bridge voltage type inverter circuit, the power supply of a power grid to a servo control system is unidirectional, mechanical energy stored on a motor rotor is converted into electric energy to be fed back to a servo device in the process of speed reduction and braking of a motor, the electric energy is generally stored in an energy storage capacitor element, the energy storage capacitor cannot consume energy, if the energy is not released in time, the voltage on a direct current side is increased, a high-power device of an inverter can be damaged, and an energy storage element can be damaged.

In order to avoid the overhigh bus voltage, a power electronic switching tube and a braking resistor are usually adopted to be matched, when the motor brakes, the switching tube is started and closed according to the change of the voltage of the direct current network side, so that the braking energy generated by the load side is consumed on the set braking resistor, and the overhigh voltage of the direct current network side caused by the feedback of the braking energy of the load side to the direct current bus side is prevented. When the energy dissipated in the resistor exceeds the overload capability of the brake resistor, the brake resistor is burned out, and therefore, the brake resistor needs to be protected in the brake unit.

Disclosure of Invention

The present invention is directed to overcome the above-mentioned drawbacks of the prior art, and provides a method and an apparatus for controlling a braking circuit, a storage medium, and a servo motor, so as to solve the problem in the prior art that when the energy consumed by a resistor exceeds the overload capability of the braking resistor, the braking resistor is burned out.

One aspect of the present invention provides a method for controlling a brake circuit, including: determining a switching tube driving signal of the brake circuit to be output currently according to the voltage of the direct-current side bus; acquiring the sum of the accumulated opening time of the first switch tube within a first preset time length and the accumulated opening time of the second switch tube within a second preset time length; determining to output the switch tube driving signal or correct the switch tube driving signal according to whether the sum of the accumulated on-time is larger than the longest total on-time that the discharge resistor is not overloaded; if the sum of the on-time is judged to be larger than the longest total on-time, the switch tube driving signal is output; and if the sum of the on-time is judged to be less than or equal to the longest total on-time, correcting the driving signal of the switching tube.

Optionally, determining a currently output switch tube driving signal of the brake circuit according to the dc-side bus voltage includes: when the bus voltage is greater than a first voltage threshold value U1 when the brake circuit starts to discharge, outputting a switch tube opening signal; and when the bus voltage is smaller than a second voltage threshold value U2 when the brake circuit stops discharging, outputting a switch tube turn-off signal.

Optionally, obtaining a sum of accumulated on-time of a first switch tube within a first preset time and accumulated on-time of a second switch tube within a second preset time includes: acquiring the on-time of a second switching tube in the time period of the second preset time which passes at present every time when the second preset time passes within the first preset time, and accumulating to obtain the accumulated on-time of the first switching tube; and adding the accumulated on-time of the first switching tube obtained by accumulation within the first preset time length and the accumulated on-time of the second switching tube which is not accumulated within the first preset time length to obtain the sum of the accumulated on-time.

Optionally, the switching tube on-time Tsum2 in each second preset-duration time period is obtained as follows: in a time period of a second preset time length, every time a sampling period passes, the second switching tube is turned on for a time period Tsum2 ═ Tsum2+ Tsk; wherein, Tsk is the switch tube on-time in a sampling period Ts, Tsk ^ Uc ^2/U1^ 2; ts is the sampling period, Uc is the bus voltage, and U1 is the first voltage threshold at which the brake current begins to discharge.

Optionally, the maximum total on-time for which the discharge resistor is not overloaded is: t1 ═ k × P_R*(t1+t2)/(U1^2/R_R) (ii) a Wherein k is the power multiplying factor P of the discharge resistor capable of operating for a long time under different heat dissipation conditions_RFor power of braking resistor, R_RFor the resistance value of the brake resistor, t1 is a first preset time period, and t2 is a second preset time period.

Another aspect of the present invention provides a braking circuit control apparatus, including: the first determining unit is used for determining a switch tube driving signal of the brake circuit to be output currently according to the voltage of the direct-current side bus; the acquisition unit is used for acquiring the sum of the accumulated opening time of the first switching tube within a first preset time length and the accumulated opening time of the second switching tube within a second preset time length; the second determining unit is used for determining to output the switching tube driving signal or correcting the switching tube driving signal according to whether the sum of the accumulated on-time is larger than the longest total on-time that the discharge resistor is not overloaded; if the sum of the on-time is judged to be larger than the longest total on-time, the switch tube driving signal is output; and if the sum of the on-time is judged to be less than or equal to the longest total on-time, correcting the driving signal of the switching tube.

Optionally, the first determining unit, configured to determine a currently output switching tube driving signal of the braking circuit according to a dc-side bus voltage, includes: when the bus voltage is greater than a first voltage threshold value U1 when the brake circuit starts to discharge, outputting a switch tube opening signal; and when the bus voltage is smaller than a second voltage threshold value U2 when the brake circuit stops discharging, outputting a switch tube turn-off signal.

Optionally, the acquiring unit acquires a sum of accumulated on-time of the first switching tube within a first preset time and accumulated on-time of the second switching tube within a second preset time, and includes: acquiring the on-time of a second switching tube in the time period of the second preset time which passes at present every time when the second preset time passes within the first preset time, and accumulating to obtain the accumulated on-time of the first switching tube; and adding the accumulated on-time of the first switching tube obtained by accumulation within the first preset time length and the accumulated on-time of the second switching tube which is not accumulated within the first preset time length to obtain the sum of the accumulated on-time.

Optionally, the second switching tube on-time Tsum2 in each second preset time period is obtained by: in a time period of a second preset time length, every time a sampling period passes, the second switching tube is turned on for a time period Tsum2 ═ Tsum2+ Tsk; wherein, Tsk is the switch tube on-time in a sampling period Ts, Tsk ^ Uc ^2/U1^ 2; ts is the sampling period, Uc is the bus voltage, and U1 is the first voltage threshold at which the brake current begins to discharge.

Optionally, the maximum total on-time for which the discharge resistor is not overloaded is: t1 ═ k × P_R*(t1+t2)/(U1^2/R_R) (ii) a Wherein k is the power multiplying factor P of the discharge resistor capable of operating for a long time under different heat dissipation conditions_RFor power of braking resistor, R_RFor the resistance value of the brake resistor, t1 is a first preset time period, and t2 is a second preset time period.

A further aspect of the invention provides a storage medium having stored thereon a computer program which, when executed by a processor, carries out the steps of any of the methods described above.

A further aspect of the invention provides a servo motor comprising a processor, a memory and a computer program stored on the memory and executable on the processor, the processor implementing the steps of any of the methods described above when executing the program.

In a further aspect, the invention provides a servo motor comprising a brake circuit control device as described in any one of the preceding claims.

According to the technical scheme of the invention, the switching tube driving signal is determined to be output or corrected according to whether the sum of the switching time within the preset time length is greater than the longest total switching time of the non-overload discharge resistor; the overload of the brake resistor is combined with the control logic of the brake circuit, and the duty ratio of a switch tube of the brake circuit is restrained through a brake resistor overload algorithm, so that the purposes of controlling the brake circuit and protecting the brake resistor are achieved simultaneously. The link of detecting the overload fault of the discharge resistor is omitted, and the method is simple in calculation and strong in universality.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a method schematic diagram of one embodiment of a braking circuit control method provided by the present invention;

FIG. 2 is a schematic diagram of an energy consumption braking circuit;

FIG. 3 shows a switching tube actuation time storage logic;

FIG. 4 is a method diagram of one embodiment of a braking circuit control method provided by the present invention;

fig. 5 is a block diagram of an embodiment of a brake circuit control apparatus according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The invention provides a brake circuit control method. The method can be used on devices that employ dynamic braking, such as servo motors, inverters, and/or frequency converters.

Fig. 2 is a schematic diagram of an energy consumption braking circuit. As shown in fig. 2, the braking circuit adopted in the present invention includes a bus capacitor C1, a braking resistor R1, and a switching tube Q1 (which may be an IGBT, for example), the braking circuit is connected to the dc bus, and P is a connection point of the braking circuit and the dc bus; the bus capacitor C1 is connected between the direct current bus and the reference ground PGND; the brake resistor R1 is connected between the direct current bus and the drain electrode of the switching tube, the source electrode of the switching tube is connected with a reference ground PGND, and the MCU control signal is connected with the base electrode of the switching tube through the driving circuit. Power of brake resistor R1 is P_RResistance value of R_R(ii) a The power factor of the resistor which can be operated for a long time in actual operation is selected (for example, 0.2P is selected under natural cooling condition)_RSelecting 0.5 × P under air cooling condition_R) In this context according to 0.2 × P_R. The voltage threshold at the time of starting discharge of the brake circuit is U1, and the voltage threshold at the time of stopping discharge is U2.

FIG. 1 is a method diagram of an embodiment of a braking circuit control method provided by the present invention.

As shown in fig. 1, according to an embodiment of the present invention, the braking circuit control method includes at least step S110, step S120, step S130, and step S140.

And step S110, determining a switch tube driving signal of the brake circuit to be output currently according to the voltage of the direct-current side bus.

Specifically, the first voltage threshold when the brake circuit starts discharging is U1, and the second voltage threshold when the discharge is stopped is U2. When the bus voltage is greater than a first voltage threshold value U1, namely Uc > U1, a switch tube opening signal is output, and the discharge circuit starts to discharge; when the bus voltage is smaller than a second voltage threshold value U2, namely Uc < U2, a switch tube turn-off signal is output, and the discharge circuit stops discharging.

Step S120, acquiring the sum of the accumulated opening time of the first switch tube within the first preset time and the accumulated opening time of the second switch tube within the second preset time.

In particular, the first preset duration t1 is equally divided into n periods of second preset duration t 2; acquiring the on-time of a second switch tube in the current passing time period of second preset time t2 every time the second preset time t2 passes in the first preset time t1, and accumulating to obtain the accumulated on-time Tsum1 of the first switch tube; and adding the accumulated first switch tube on-time Tsum1 and the second switch tube on-time Tsum2 which is not accumulated in the first preset time length to obtain the accumulated on-time sum Tsum.

More specifically, a period of time t1 (e.g., 100s, which may be adjusted according to actual conditions) is selected, and t1 is divided into n equal smaller periods of time t2 (e.g., 0.5 s). The second switching tube on time Tsum2 in each time period of the second preset time length t2 is obtained as follows:

in a time period of a second preset time length, every time a sampling period passes, the second switching tube is turned on for a time period Tsum2 ═ Tsum2+ Tsk;

wherein, Tsk ═ Ts ^ Uc ^2/U1^ 2; ts is a sampling period, Tsk is the switching tube on-time in one sampling period Ts, and U1 is a first voltage threshold value when the brake current starts to discharge. In a sampling period Ts, if a switching tube in the previous period is switched on, carrying out equivalent calculation of switching time on bus voltage detected in the previous period (since protection threshold values are calculated according to the bus voltage U1, conversion is carried out according to the principle of heat equality), and obtaining the switching time Tsk ═ Ts ^ Uc ^2/U1^ 2; if the switching tube is turned off in the last period, the turn-on time Tsk is 0.

Accumulating the on-time Tsk of the switching tube within each time period of the second preset time t2 to obtain second on-time Tsum2 of the switching tube, storing the second on-time Tsum2 in the array, and sequentially storing the second on-time Tsum in the array when the array is not full; and when the array is full, replacing the data stored in the array at first, and discarding the old data (the size of the array is set according to the number of second preset time in the first preset time, so that the data in the array is always the second switch tube on time obtained every second preset time in the first preset time). For example, after the device starts to operate, when the operation time is less than a second preset time (for example, 0.25s), the accumulated Tsum2 is not stored in the array at this time; when the time reaches 0.5s (the second preset time t2), the value of Tsum2 obtained by accumulation is stored in an array, the value of Tsum2 is cleared, and accumulation is carried out again. When the running time of the equipment reaches 1s (2 × t2), the value of Tsum2 obtained by accumulation is stored in an array, the value of Tsum2 is cleared, accumulation is carried out again, and the operation is repeated. And accumulating the on-time Tsum2 of the second switch tube in the array to obtain Tsum1, and adding the on-time Tsum2 of the second switch tube which is not stored in the array to obtain the total on-time Tsum of the switch tubes. Figure 3 shows the switching tube actuation time storage logic.

And step S130, determining to output the switch tube driving signal or correct the switch tube driving signal according to whether the sum of the accumulated opening time is larger than the longest total opening time of the discharge resistor without overload.

Specifically, the maximum total on-time T1 for which the discharge resistor is not overloaded is calculated as follows:

T1＝k*P_R*(t1+t2)/(U1^2/R_R)

wherein k is the power multiplying factor of the discharge resistor capable of operating for a long time under different heat dissipation conditions, for example, 0.2 × P is selected under the natural cooling condition_RSelecting 0.5 star PR under the air cooling condition); p_RFor power of braking resistor, R_RFor the resistance value of the brake resistor, t1 is a first preset time period, and t2 is a second preset time period. The period in the entire overload calculation range is t1 to t1+ t2, and therefore, the calculation is performed at the longest period t1+ t2 in calculating the threshold value.

If the sum of the switching-on time is judged to be larger than the longest total switching-on time, a switching tube driving signal is output; and if the sum of the on-time is judged to be less than or equal to the longest total on-time, correcting the driving signal of the switching tube.

Comparing Tsum with T1, and if Tsum is less than or equal to T1, switching the tube according to the result obtained in step 2; if Tsum > T1, the switch tube driving signal is corrected (the discharging action of the discharging switch tube is not performed any more).

For clearly explaining the technical solution of the present invention, the following describes an execution flow of the braking circuit control method provided by the present invention with a specific embodiment.

FIG. 4 is a method diagram of an embodiment of a braking circuit control method provided by the present invention.

Selecting a period of time t1 (for example, 100s, which can be adjusted according to actual conditions), dividing t1 into n equal smaller periods of time t2 (for example, 0.5s), and calculating the maximum total on-time of the discharge resistor without overload as: t1 ═ 0.2 × P_R*(t1+t2)/(U1^2/R_R)。

As shown in fig. 4, the hysteresis discharge control link outputs a switching tube driving signal, and determines the output switching tube driving signal according to the bus voltage, wherein when the bus voltage Uc > U1, a switching tube on signal is output; when the bus voltage Uc is less than U2, outputting a switch tube turn-off signal; in a sampling period Ts, if a switching tube in the previous period is switched on, carrying out equivalent calculation of switching-on time on bus voltage detected in the previous period (since protection threshold values are calculated according to the bus voltage U1, conversion is carried out according to the principle of heat equality), and Tsk ═ Ts × Uc ^2/U1^ 2; if the switching tube is turned off in the last period, Tsk is 0; accumulating the turn-on time Tsk of the switching tube in each t2 time period (for example, 0.5s) to obtain Tsum2, storing the Tsum2 in an array, and sequentially storing the Tsum2 in the array when the array is not full; when the array is full, the data stored in the array is replaced from the data stored in the array first, and old data is discarded. And accumulating the switch tube on-time in the array to obtain Tsum1, and then adding the switch tube on-time with the on-time Tsum2 which is not stored in the array to obtain the total switch tube on-time Tsum. Comparing Tsum with T1, and if Tsum is less than or equal to T1, outputting a determined switch tube driving signal; if Tsum > T1, the switch tube driving signal is corrected (wherein, the driving signal of the switch tube is blocked, and the discharging action of the discharging switch tube is not performed any more).

The invention also provides a control device of the brake circuit. The device can be used on equipment adopting dynamic braking, such as a servo motor, an inverter and/or a frequency converter.

As shown in fig. 2, the braking circuit adopted in the present invention includes a bus capacitor C1, a braking resistor R1, and a switching tube Q1 (which may be an IGBT, for example), the braking circuit is connected to the dc bus, and P is a connection point of the braking circuit and the dc bus; the bus capacitor C1 is connected between the direct current bus and the reference ground PGND; the brake resistor R1 is connected between the direct current bus and the drain electrode of the switching tube, the source electrode of the switching tube is connected with a reference ground PGND, and the MCU control signal is connected with the base electrode of the switching tube through the driving circuit. Power of brake resistor R1 is P_RResistance value of R_R(ii) a The power factor of the resistor which can be operated for a long time in actual operation is selected (for example, 0.2P is selected under natural cooling condition)_RSelecting 0.5 × P under air cooling condition_R) In this context according to 0.2 × P_R. The voltage threshold at the time of starting discharge of the brake circuit is U1, and the voltage threshold at the time of stopping discharge is U2.

Fig. 5 is a block diagram of an embodiment of a brake circuit control apparatus according to the present invention. As shown in fig. 5, the braking circuit control apparatus 100 includes a first determining unit 110, an obtaining unit 120, and a second determining unit 130.

The first determining unit 110 is configured to determine a switching tube driving signal of the brake circuit to be output currently according to the dc-side bus voltage.

Specifically, the first voltage threshold when the brake circuit starts discharging is U1, and the second voltage threshold when the discharge is stopped is U2. When the bus voltage is greater than a first voltage threshold value U1, namely Uc > U1, a switch tube opening signal is output, and the discharge circuit starts to discharge; when the bus voltage is smaller than a second voltage threshold value U2, namely Uc < U2, a switch tube turn-off signal is output, and the discharge circuit stops discharging.

The obtaining unit 120 is configured to obtain a sum of an accumulated on-time of the first switch tube within a first preset time and an accumulated on-time of the second switch tube within a second preset time.

In particular, the first preset duration t1 is equally divided into n periods of second preset duration t 2; acquiring the on-time of a second switch tube in the current passing time period of second preset time t2 every time the second preset time t2 passes in the first preset time t1, and accumulating to obtain the accumulated on-time Tsum1 of the first switch tube; and adding the accumulated first switch tube on-time Tsum1 and the second switch tube on-time Tsum2 which is not accumulated in the first preset time length to obtain the accumulated on-time sum Tsum.

More specifically, a period of time t1 (e.g., 100s, which may be adjusted according to actual conditions) is selected, and t1 is divided into n equal smaller periods of time t2 (e.g., 0.5 s). The second switching tube on time Tsum2 in each time period of the second preset time length t2 is obtained as follows:

in a time period of a second preset time length, every time a sampling period passes, the second switching tube is turned on for a time period Tsum2 ═ Tsum2+ Tsk;

wherein, Tsk ═ Ts ^ Uc ^2/U1^ 2; tsk is the switching tube on-time within a sampling period Ts, which is the sampling period, and U1 is the first voltage threshold when the brake current starts to discharge. In a sampling period Ts, if a switching tube in the previous period is switched on, carrying out equivalent calculation of switching time on bus voltage detected in the previous period (since protection threshold values are calculated according to the bus voltage U1, conversion is carried out according to the principle of heat equality), and obtaining the switching time Tsk ═ Ts ^ Uc ^2/U1^ 2; if the switching tube is turned off in the last period, the turn-on time Tsk is 0.

Accumulating the on-time Tsk of the switching tube within each time period of the second preset time t2 to obtain second on-time Tsum2 of the switching tube, storing the second on-time Tsum2 in the array, and sequentially storing the second on-time Tsum in the array when the array is not full; and when the array is full, replacing the data stored in the array at first, and discarding the old data (the size of the array is set according to the number of second preset time in the first preset time, so that the data in the array is always the second switch tube on time obtained every second preset time in the first preset time). For example, after the device starts to operate, when the operation time is less than a second preset time (for example, 0.25s), the accumulated Tsum2 is not stored in the array at this time; when the time reaches 0.5s (the second preset time t2), the value of Tsum2 obtained by accumulation is stored in an array, the value of Tsum2 is cleared, and accumulation is carried out again. When the running time of the equipment reaches 1s (2 × t2), the value of Tsum2 obtained by accumulation is stored in an array, the value of Tsum2 is cleared, accumulation is carried out again, and the operation is repeated. And accumulating the on-time Tsum2 of the second switch tube in the array to obtain Tsum1, and adding the on-time Tsum2 of the second switch tube which is not stored in the array to obtain the total on-time Tsum of the switch tubes. Figure 3 shows the switching tube actuation time storage logic.

The second determining unit 130 is configured to determine to output the switching tube driving signal or correct the switching tube driving signal according to whether the sum of the accumulated on-time is greater than the longest total on-time for which the discharge resistor is not overloaded; if the sum of the on-time is judged to be larger than the longest total on-time, the switch tube driving signal is output; and if the sum of the on-time is judged to be less than or equal to the longest total on-time, correcting the driving signal of the switching tube.

Specifically, the maximum total on-time T1 for which the discharge resistor is not overloaded is calculated as follows:

T1＝k*P_R*(t1+t2)/(U1^2/R_R)

wherein k is the power multiplying factor of the discharge resistor capable of operating for a long time under different heat dissipation conditions, for example, 0.2 × P is selected under the natural cooling condition_RSelecting 0.5 × P under air cooling condition_R)；P_RFor power of braking resistor, R_RFor the resistance value of the brake resistor, t1 is a first preset time period, and t2 is a second preset time period. The period in the entire overload calculation range is t1 to t1+ t2, and therefore, the calculation is performed at the longest period t1+ t2 in calculating the threshold value.

If the sum of the on-time is judged to be larger than the longest total on-time, outputting the switch tube driving signal; and if the sum of the on-time is judged to be less than or equal to the longest total on-time, correcting the driving signal of the switching tube.

Specifically, Tsum is compared with T1, if Tsum is less than or equal to T1, the switch tube outputs according to the determined light-on driving signal; if Tsum > T1, the determined switch tube driving signal is corrected (the discharging operation of the discharging switch tube is not performed any more).

The invention also provides a storage medium corresponding to the braking circuit control method, on which a computer program is stored, which program, when executed by a processor, carries out the steps of any of the methods described above.

The invention also provides a servo motor corresponding to the brake circuit control method, which comprises a brake circuit, a processor, a memory and a computer program stored on the memory and capable of running on the processor, wherein the processor realizes the steps of any one of the methods when executing the program.

The invention also provides a servo motor corresponding to the brake circuit control device, which comprises a brake circuit and any one of the brake circuit control devices.

According to the scheme provided by the invention, the switching tube driving signal is determined to be output or corrected according to whether the sum of the switching time within the preset time length is greater than the longest total switching time of the non-overload discharge resistor; the overload of the brake resistor is combined with the control logic of the brake circuit, and the duty ratio of a switch tube of the brake circuit is restrained through a brake resistor overload algorithm, so that the purposes of controlling the brake circuit and protecting the brake resistor are achieved simultaneously. The link of detecting the overload fault of the discharge resistor is omitted, and the method is simple in calculation and strong in universality.

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope and spirit of the invention and the following claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwired, or a combination of any of these. In addition, each functional unit may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

In the embodiments provided in the present application, it should be understood that the disclosed technology can be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units may be a logical division, and in actual implementation, there may be another division, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, units or modules, and may be in an electrical or other form.

The units described as separate parts may or may not be physically separate, and the parts serving as the control device may or may not be physical units, may be located in one place, or may be distributed on a plurality of units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic or optical disk, and other various media capable of storing program codes.

The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.