Method and apparatus for protecting a servo braking resistor

Abstract

The application discloses a kind of methods and devices for protecting servo brake resistance, wherein a kind of methods for protecting servo brake resistance, comprising: using current sensor to detect the current passing through brake resistance, and the current is input into signal processor, signal processor judges whether the current is continuous state;When the current on brake resistance is discontinuous state, signal processor does not output control signal;When the current on brake resistance is continuous state, signal processor outputs corresponding control signal.A kind of device for protecting servo brake resistance, comprising: current sensor and signal processor, signal processor is connected with current sensor signal, receives and processes the current detected in current sensor, and outputs corresponding control signal.The application provides a kind of methods and devices for protecting servo brake resistance, judges whether servo driver appears fault, and issues corresponding control signal, handles in time, avoids brake resistance to be burnt out, avoids security risk.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of servo drive, in particular to a method and device for protecting servo braking resistor. BACKGROUND

[0002] Braking resistor is a kind of corrugated resistor, mainly used in the mechanical system of frequency converter control motor fast parking, helping the motor to convert the regenerative energy generated by fast parking into heat energy. Servo driver usually has a built-in braking unit, one end of the braking resistor is connected to the braking unit, and the other end is connected to the positive pole of the DC bus. When the braking unit is working normally, the braking resistor is equivalent to being connected between the positive and negative poles of the bus, and is used to release the regenerative energy generated by the servo. At present, the servo driver in the prior art basically does not have the protection function of braking unit failure. When the braking unit fails or burns out, the braking unit is mostly in a short-circuit state. At this time, the braking resistor will always be connected between the positive and negative poles of the bus, and the average heating power of the braking resistor will far exceed its rated value. The braking resistor will be red or burned, which will cause safety hazards. SUMMARY

[0003] The purpose of the present application is to provide a method and device for protecting servo braking resistor, which detects whether the current through the braking resistor is continuous, judges whether the braking resistor is in the fault state of the servo driver, and sends corresponding control signals for timely processing to avoid the braking resistor from being burned out and safety hazards.

[0004] To solve the above technical problems, the technical scheme provided by the present application is: a method for protecting servo braking resistor, comprising:

[0005] using a current sensor to detect the current passing through the braking resistor and inputting the detected current into a signal processor, and the signal processor judges whether the current is continuous within a scanning period;

[0006] when the current through the braking resistor is discontinuous, the signal processor judges that the braking resistor is in a normal working state, and the signal processor does not output a control signal;

[0007] when the current through the braking resistor is continuous, the signal processor judges that the braking resistor is in a continuous power-on state, and the signal processor outputs a corresponding control signal.

[0008] The present application adopts the above technical scheme, which detects the current flowing through the braking resistor in real time, judges whether the braking resistor is in a long-term power-on state in time, outputs a control signal for warning when the braking resistor is detected to be in a long-term power-on state, and timely responds to disconnect the current of the braking resistor to protect the braking resistor and avoid safety accidents.

[0009] Further, the signal processor outputs a control signal to control the sound-light alarm to give an alarm. After the sound-light alarm gives an alarm, the staff can timely turn off the power supply of the servo driver to protect the braking resistor from burning out due to long-time power-on.

[0010] Further, the signal processor outputs a control signal to control the auxiliary contact of the relay to switch to open circuit. The relay can be directly connected to the safety circuit to control the power supply of the servo driver, or can control a contactor to control the power supply of the braking resistor, thereby protecting the braking resistor.

[0011] Further, the time length of the scanning cycle is set to 5 seconds.

[0012] To solve the above technical problems, the application further provides another technical solution, which is a device for protecting a servo braking resistor, comprising:

[0013] A current sensor is used to detect the current flowing through the braking resistor.

[0014] A signal processor is connected to the current sensor in signal and is used to receive and process the current detected by the current sensor and output a corresponding control signal.

[0015] Further, the signal processor is connected to a sound-light alarm in signal.

[0016] Further, the signal processor is connected to a relay in circuit.

[0017] The application has the following beneficial effects: The application is independent of the servo driver and is suitable for detecting the braking resistor of all servo driver products. The Hall current sensor is used to detect whether there is current in the braking resistor, and the duration of the current is used to judge whether the braking unit of the servo driver is normally opened, without the need to detect the size of the braking current value, thereby avoiding the high cost of a large-range current sensor required for detecting a large-current braking unit. The inductive detection on the lead of the braking resistor does not need to be electrically connected to the strong current part of the servo drive circuit and is completely isolated from the strong current of the servo driver, thereby being safe and reliable to use. The sound-light alarm function can remind the on-site staff to take corresponding actions, and the response is more efficient. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a control circuit structure schematic diagram of the application;

[0019] Figure 2 is a connection circuit structure schematic diagram of the servo driver and the braking resistor. DETAILED DESCRIPTION

[0020] The application will be further described below in combination with the drawings and specific embodiments.

[0021] Referring to Figure 1 and Figure 2 The application discloses a method for protecting a servo braking resistor, which comprises the following steps:

[0022] A current sensor 10 is used to detect the current flowing through the braking resistor R, and the detected current is input into a signal processor 20. In a scanning period, the signal processor 20 judges whether the current is continuous or not.

[0023] When the current flowing through the braking resistor R is discontinuous, the signal processor 20 judges that the braking resistor R is in a normal working state, and the signal processor 20 does not output a control signal.

[0024] When the current flowing through the braking resistor R is continuous, the signal processor 20 judges that the braking resistor R is in a continuous conduction state, and the signal processor 20 outputs a corresponding control signal.

[0025] The signal processor 20 outputs the control signal to control the sound-light alarm 30 to give an alarm.

[0026] The signal processor 20 outputs the control signal to control the auxiliary contact of the relay 40 to switch to an open circuit.

[0027] In the embodiment, the length of one scanning period is set to 5 seconds.

[0028] Referring to Figure 2 When the braking unit VT7 inside the servo driver is turned on, the braking resistor R is connected to the positive and negative poles of the bus, and the braking resistor R serves as a load of the bus. The current sensor 10 detects the current flowing through the braking resistor R, and judges the normal working state of the braking resistor R. When the braking unit VT7 inside the servo driver is turned off, one end of the braking resistor R is connected to the bus, and the other end is suspended. The current sensor 10 detects that no current flows through the braking resistor R.

[0029] Further referring to Figure 1 and Figure 2 The application discloses a device for protecting a servo braking resistor, which comprises the following parts:

[0030] A current sensor 10 is used to detect the current flowing through the braking resistor R, wherein the current sensor 10 is preferably a Hall current sensor;

[0031] A signal processor 20 is signal-connected with the current sensor 10, and is used to receive and process the current detected by the current sensor 10, and output a corresponding control signal.

[0032] The signal processor 20 is signal-connected with a sound-light alarm 30. The signal processor 20 is circuit-connected with a relay 40.

[0033] The actual rated power of the braking resistor in practice is small, and the braking resistor is generally used for instantaneous overload, and when the servo driver controls the motor to decelerate or brake, the braking resistor is connected to the circuit through the braking unit inside the servo driver, so that the braking resistor is connected across the positive and negative electrodes of the braking unit and is connected to the braking circuit.

[0034] It should be understood that the current of the braking resistor R is related to the bus voltage and the resistance value itself. When the braking unit of the servo driver is working, the braking resistor has current flowing through it, and when the braking unit is not working, the braking resistor has no current flowing through it. When the braking resistor R is working, the current of the braking resistor is pulsed or continuously for a short time. The signal processor judges the continuous working time of the braking resistor R within the set limited time, compares the time during which the current of the braking resistor R flows with the characteristics of the braking resistor R itself, and judges whether the braking resistor R has abnormal conduction, i.e., whether the braking unit of the servo driver has an abnormal fault. At this time, the application can issue an audible and visual warning, and the relay 40 is controlled to be disconnected.

[0035] In one scanning cycle, when the bus voltage of the braking unit rises to a certain value, the braking unit VT7 is turned on, and the energy is currently dissipated through the braking resistor R, so that the bus voltage does not continue to rise. The braking unit VT7 is turned on when the motor deceleration and braking cause the bus voltage to rise to a certain threshold value. At this time, the voltage across the braking resistor R is turned on, which is used to release the voltage of the bus.

[0036] The braking resistor can generally withstand 5 seconds of time, and through 5-10 times of overload. In one scanning cycle, when the braking resistor R flows through the braking current for a long time, the braking current of the braking resistor R is detected by the current sensor 10, and the signal processor 20 can judge that the braking unit of the servo driver has a fault causing a short circuit, so that the signal processor 20 timely outputs a control signal to control the audible and visual alarm 30 to alarm and control the normally open contact of the relay 40 to be open. The relay 40 can be directly connected to the safety circuit to control the power supply of the servo driver, or can control a contactor to control the power supply of the braking resistor, thereby protecting the braking resistor.

[0037] In summary, the application has been made as described in the specification and the drawings, and actual samples have been made and tested multiple times. From the effect of the use test, it can be proved that the application can achieve its intended purpose, and the practical value is not in doubt. The above examples are only used to facilitate the illustration of the application and do not limit the application in any form. Any person skilled in the art can make partial changes or modifications to equivalent embodiments within the scope of the technical features disclosed in the application without departing from the technical features of the application, and the changes or modifications do not depart from the technical features of the application.

Claims

1. A method of protecting a servo braking resistor, characterized by, The application relates to a current sensor (10) for detecting the current flowing through a brake resistor R and inputting the detected current into a signal processor (20), and the signal processor (20) judges whether the current is in a continuous state in a scanning cycle. The signal processor (20) judges the continuity of the current in the scanning cycle, and if the time proportion of the continuous current detected in a single scanning cycle exceeds a preset value, the current state is determined as the continuous state. When the current on the brake resistor R is in a discontinuous state, the signal processor (20) judges that the brake resistor R is in a normal working state, and the signal processor (20) does not output a control signal. When the current on the brake resistor R is in a continuous state, the signal processor (20) judges that the brake resistor R is in a continuous energized state, and the signal processor (20) outputs a corresponding control signal to cut off the brake resistor circuit or trigger an alarm. The current sensor is a Hall current sensor, which is sleeved on the brake resistor lead wire in a non-contact mode to detect the current. The continuous state refers to the continuous existence of the current in the scanning cycle, and the continuous time exceeds the pulse duration in the normal working state of the brake resistor. The signal processor (20) outputs a control signal to control the sound-light alarm (30) to issue an alarm.

2. The method of protecting a servo brake resistor as defined in claim 1, characterized by: The signal processor (20) outputs a control signal to control the auxiliary contact of the relay (40) to be switched to an open circuit.

3. The method of protecting a servo brake resistor of claim 1, wherein: The length of a scanning cycle is set as 5 seconds.

4. The method of protecting a servo brake resistor of claim 1, wherein: The application relates to a current sensor (10) for detecting the current flowing through a brake resistor R and inputting the detected current into a signal processor (20), and the signal processor (20) judges whether the current is in a continuous state in a scanning cycle.

5. An arrangement for protecting a servo brake resistor, characterized in that The signal processor (20) judges the continuity of the current in the scanning cycle, and if the time proportion of the continuous current detected in a single scanning cycle exceeds a preset value, the current state is determined as the continuous state. When the current on the brake resistor R is in a discontinuous state, the signal processor (20) judges that the brake resistor R is in a normal working state, and the signal processor (20) does not output a control signal. When the current on the brake resistor R is in a continuous state, the signal processor (20) judges that the brake resistor R is in a continuous energized state, and the signal processor (20) outputs a corresponding control signal to cut off the brake resistor circuit or trigger an alarm. The current sensor is a Hall current sensor, which is sleeved on the brake resistor lead wire in a non-contact mode to detect the current. The signal processor is configured to determine the continuous state when the continuous current time exceeds the normal pulse duration of the brake resistor. The signal processor (20) is signal-connected with a sound-light alarm (30). ​ ​ ​ ​ 6. The apparatus for protecting a servo brake resistor of claim 5, wherein: ​

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